,illustration3 ,from a ,painting by ,james ,hall1 ,esq4 ,engraved by ,s4 ,williams4 ,,strata ,,of ,,red ,,sandstone1 ,,slightly ,,inclined1 ,,resting ,,on ,,vertical ,,schist1 ,,at ,,the ,,siccar ,,point1 ,,berwickshire4 ,,to ,,illustrate ,,unconformable ,,stratification4 ,see page #fj4 ,the mind seemed to grow giddy by looking so far into the abyss of time2 and while we listened with earnestness and admiration to the philosopher who was now unfolding to us the order and series of these wonderful events1 we became sensible how much farther reason may sometimes go than imagination can venture to follow4--,,playfair1 ,biography of ,hutton4 ,a ,,manual ,,of ,,elementary ,,geology3 ,,or1 ,,the ,,ancient ,,changes ,,of ,,the ,,earth ,,and ,,its ,,inhabitants ,,as ,,illustrated ,,by ,,geological ,,monuments4 ,,by ,,sir ,,charles ,,lyell1 ,m4,a4 ,f4,r4,s4 ,,author ,,of ,,principles ,,of ,,geology1 ,,travels ,,in ,,north ,,america1 ,a ,,second ,,visit ,,to ,,the ,,united ,,states1 ,,etc4 ,,etc4 ,it is a philosophy which never rests--its law is progress3 a point which yesterday was invisible is its goal to-day1 and will be its starting post to-morrow4 ,,edinburgh ,,review1 ,no4 #acb4 p4 #hc4 ,july1 #ahcg4 ,,fourth ,,and ,,entirely ,,revised ,,edition4 ,,illustrated ,,with #ejj ,,woodcuts4 ,,london3 ,,john ,,murray1 ,,albemarle ,,street4 #aheb4 ,,london3 ,,spottiswoodes and ,,shaw1 ,new-street-,square4 ,,preface ,,to ,,the ,,fourth ,,edition4 ,in consequence of the rapid sale of the third edition of the ,manual1 of which #bjjj copies were printed in ,january last1 a new edition has been called for in less than a twelvemonth4 ,even in this short interval some new facts of unusual importance in palaeontology have come to light1 or have been verified for the first time4 ,instead of introducing these new discoveries into the body of the work1 which would render them inaccessible to the purchasers of the former edition1 ,i have given them in a postscript to this ,preface 7printed and sold separately71 and have pointed out at the same time their bearing on certain questions of the highest theoretical interest4v-,a ,as on former occasions1 ,i shall take this opportunity of stating that the ,manual is not an epitome of the ,principles of ,geology1 nor intended as introductory to that work4 ,so much confusion has arisen on this subject1 that it is desirable to explain fully the different ground occupied by the two publications4 ,the first five editions of the ,principles comprised a #dth book1 in which some account was given of systematic geology1 and in which the principal rocks composing the earth's crust and their organic remains were described4 ,in subsequent editions this book was omitted1 it having been expanded1 in #ahch1 into a separate treatise called the ,elements of ,geology1 first re-edited in #ahdb1 and again recast and enlarged in #ahea1 and entitled ,a ,manual of ,elementary ,geology4 ,although the subjects of both treatises relate to geology1 as their titles imply1 their scope is very different2 the ,principles containing a view of the modern changes of the earth and its inhabitants1 while the ,manual relates to the monuments of ancient changes4 ,in separating the one from the other1 ,i have endeavoured to render each complete in itself1 and independent2 but if asked by a student which he should read first1 ,i would recommend him to begin with the ,principles1 as he may then proceed from the known to the unknown1 and be provided beforehand with a key for interpreting the ancient phenomena1 whether of the organic or inorganic world1 by reference to changes now in progress4 ,owing to the former incorporation of the two subjects in one work1 and the supposed identity of their subject matter1 it may be useful to give here a brief abstract of the contents of the ,principles1 for the sake of comparison4 ,abstract of the ,principles of ,geology1 ,eighth ,edition4 ,,book ,i4 #a4 ,historical sketch of the early progress of geology1 chaps4 i4 to iv4 #b4 ,circumstances which combined to make the first cultivators of the science regard the former course of nature as different from the present1 and the former changes of the earth's surface as the effects of agents different in kind and degree from those now acting1 chap4 v4 #c4 ,whether the former variations in climate established by geology are explicable by reference to existing causes1 chaps4 vi4 to viii4 #d4 ,theory of the progressive development of organic life in former ages1 and the introduction of man into the earth1 chap4 ix4 #e4 ,supposed former intensity of aqueous and igneous causes considered1 chaps4 x4 and xi4 #f4 ,how far the older rocks differ in texture from those now forming1 chap4 xii4 #g4 ,supposed alternate periods of repose and disorder1 chap4 xiii4 ,,book ,,ii4 ,,changes ,,now ,,in ,,progress ,,in ,,the ,,inorganic ,,world4 #h4 ,aqueous causes now in action3 ,floods--,rivers--,carrying power of ice--,springs and their deposits--,deltas--,waste of cliffs and strata produced by marine currents3 chaps4 xiv4 to xxii4 #i4 ,permanent effects of igneous causes now in operation3 ,active volcanos and earthquakes--their effects and causes3 chaps4 xxiii4 to xxxiii4 ,,book ,,iii4 ,,changes ,,of ,,the ,,organic ,,world ,,now ,,in ,,progress4 #aj4 ,doctrine of the transmutation of species controverted1 chaps4 xxxiv4 and xxxv4 #aa4 ,whether species have a real existence in nature1 chaps4 xxxvi4 and xxxvii4 #ab4 ,laws which regulate the geographical distribution of species1 chaps4 xxxviii4 to xl4 #ac4 ,creation and extinction of species1 chaps4 xli4 to xliv4 #ad4 ,imbedding of organic bodies1 including the remains of man and his works1 in strata now forming1 chaps4 xlv4 to l4 #ae4 ,formation of coral reefs1 chap4 li4 ,it will be seen on comparing this analysis of the contents of the ,principles with the headings of the chapters of the present work 7see p4 xxiii471 that the two treatises have but little in common2 or1 to repeat what ,i have said in the ,preface to the #hth edition of the ,principles1 they have the same kind of connection which ,chemistry bears to ,natural ,philosophy1 each being subsidiary to the other1 and yet admitting of being considered as different departments of science4vi-,a ,,charles ,,lyell4 #aa ,harley ,street1 ,london1 ,december #aj4 #ahea4 ,,footnotes3 v-,a ,postscript to #dth edition of the ,manual1 price #f;d4 vi-,a ,as it is impossible to enable the reader to recognize rocks and minerals at sight by aid of verbal descriptions or figures1 he will do well to obtain a well-arranged collection of specimens1 such as may be procured from ,mr4 ,tennant 7#adi4 ,strand71 teacher of ,mineralogy at ,king's ,college1 ,london4 ,,postscript4 ,tracks of a ,lower ,silurian reptile in ,canada--,chelonian footprints in ,old ,red ,sandstone1 ,morayshire--,skeleton of a reptile in the same formation in ,scotland--,eggs of ,batrachians 787 in a lower division of the ,old ,red1 or ,devonian--,footprints of ,lower ,carboniferous reptiles in the ,united ,states--,fossil rain-marks of the ,carboniferous period in ,nova ,scotia--,triassic ,mammifer from the ,keuper of ,stuttgart--,cretaceous ,gasteropoda--,dicotyledonous leaves in ,lower ,cretaceous strata--,bearing of the recent discoveries above-mentioned on the theory of the progressive development of animal life4 ,tracks of a ,lower ,silurian reptile in ,canada4--,in the year #ahdg1 ,mr4 ,robert ,abraham announced in the ,montreal ,gazette1 of which he was editor1 that the track of a freshwater tortoise had been observed on the surface of a stratum of sandstone in a quarry opened on the banks of the ,st4 ,lawrence at ,beauharnais in ,upper ,canada4 ,the inhabitants of the parish being perfectly familiar with the track of the amphibious mud-turtles or terrapins of their country1 assured ,mr4 ,abraham that the fossil impressions closely resembled those left by the recent species on sand or mud4 ,having satisfied himself of the truth of their report1 he was struck with the novelty and geological interest of the phenomenon4 ,imagining the rock to be the lowest member of the old red sandstone1 he was aware that no traces had as yet been found of a reptile in strata of such high antiquity4 ,he was soon informed by ,mr4 ,logan1 at that time engaged in the geological survey of ,canada1 that the white sandstone above ,montreal was really much older than the ,old ,red1 or ,devonian4 ,it had in fact been ascertained many years before1 by the ,state surveyors of ,new ,york 7who called it the ,potsdam ,sandstone71 to lie at the base of the whole ,silurian series4 ,as such it had been pointed out to me in #ahda1 in the valley of the ,mohawk1 by ,mr4 ,james ,hallvii-,a1 and its position was correctly described by ,mr4 ,emmons1 on the borders of ,lake ,champlain1 where ,i examined it in #ahdb4 ,it has there the character of a shallow-water deposit1 ripple-marked throughout a considerable thickness1 and full of a species of ,lingula4 ,the flat valves of this shell1 of a dark colour1 are so numerous1 and so arranged in horizontal layers1 as to play the part of mica1 causing the rock to divide into laminae1 as in some micaceous sandstones4 ,when ,i mentioned this rock in my ,travelsvii-,b as occurring between ,kingston and ,montreal1 7the same in which the ,chelonian foot-prints have since been found17 ,i spoke of it as the lowest member of the ,lower ,silurian series2 but no traces of any organic being of a higher grade than the ,lingula had then been seen in it1 and ,i called attention to the singular fact1 that the oldest fossil form then known in the world1 was a marine shell strictly referable to a genus now existing4 ,early in the year #ahea1 ,mr4 ,logan laid before the ,geological ,society of ,london a slab of this sandstone from ,beauharnais1 containing no less than twenty-eight foot-prints of the fore and hind feet of a quadruped1 and six casts in plaster of ,paris1 exhibiting a continuation of the same trail4 ,each cast contained from twenty-six to twenty-eight impressions with a median channel equidistant from the two parallel rows of foot-prints1 the one made by the feet of the right side1 the other by those of the left4 ,in these specimens a greater number of successive foot-marks belonging to one and the same series were displayed than had ever before been observed in any rock ancient or modern4 ,mr4 ,abraham has inferred that the breadth of the quadruped was from five to seven inches4 ,a detailed account of the trail was published by ,professor ,owen1 in ,april #ahea1 from which the following extracts are made4 ,the foot-prints are in pairs1 and the pairs extend in two parallel series1 with a channel exactly midway between the right and left series4 ,the pairs of the same side succeed each other at intervals1 varying from one inch and a half to two inches and a half1 the common distance being about two inches4 ,the interval between the right and left pairs1 measured from the inner border of the small prints1 is three inches and a half1 and from the outer border of the exterior or large prints1 is seven inches4 ,the shallow median track is one inch and a quarter in breadth1 varying in depth1 but not in its relative position to the right and left foot prints4 ,the inference to be deduced from these characters is1 that the impressions were made by a quadruped with the hind feet larger and somewhat wider apart than the fore feet1 with both hind and fore feet either very short1 or prevented by some other part of the animal's structure from making long steps2 and with the limbs of the right side wide apart from those of the left2 consequently1 that the quadruped had a broad trunk in proportion to its length1 supported on limbs either short1 or capable only of short steps1 and with rounded and stumpy feet1 not provided with long claws4 ,there are faint traces of a fine reticulate pattern of the cuticle of the sole at the bottom of some of the foot-prints on one portion of the sandstone2 and the surface of the sand is generally smoother there than where not impressed1 which1 with the rising of the sand at the border of the prints1 indicates the weight of the impressing body4 ,the median groove may be interpreted as due either to the abdomen or the tail of the animal2 but as there is no indication of any bending or movement of a tail from side to side1 it was probably scooped out of the soft sand by a hard breast-plate or plastron4 ,if this were so1 it may be inferred that the species was a freshwater or estuary tortoise rather than a land tortoise4viii-,a ,previously to this discovery1 the trias was the oldest stratum in which any remains or signs of a ,chelonian had been detected4 ,numerous other trails have since been observed 7#ahej-ea7 in various localities in ,canada1 all in the same very ancient fossiliferous rock2 and ,mr4 ,logan1 who has visited the spots1 will shortly publish a description of the phenomena4 ,chelonian foot-prints in ,old ,red ,sandstone1 ,morayshire4--,captain ,lambart ,brickenden has just communicated to the ,geological ,society of ,london a drawing and description of a continuous series of no less than thirty-four foot-prints of a quadruped observed in the course of last year 7#ahej71 on a slab of sandstone quarried at ,cummingstone1 near ,elgin1 in ,morayshire1 a rock which has always been considered as an upper member of the ,devonian or ,old ,red4ix-,a ,a part of the track1 the course of which was from ,a to ,b1 is represented in the annexed woodcut1 fig4 #eba4 ,the foot-prints are in pairs1 forming two parallel rows1 which are somewhat less distant from each other than those of the ,lower ,silurian tortoise of ,canada above mentioned4 ,the stride1 on the other hand1 is four inches1 or twice that of the ,beauharnais ,chelonian4 ,the hind foot is exactly of the same size1 being one inch in diameter1 and larger than the fore foot in the proportion of four to three4 ,illustration3 ,fig4 #eba4 ,scale one-sixth the original size4 ,part of the trail of a 7,chelonian87 quadruped from the ,old ,red ,sandstone of ,cummingstone1 near ,elgin1 ,morayshire4--,captain ,brickenden4 ,skeleton of a reptile1 allied to the ,batrachians1 in the ,old ,red ,sandstone of ,morayshire4--,mr4 ,patrick ,duff1 author of a ,sketch of the ,geology of ,morayshire 7,elgin1 #ahdb71 obtained recently 7,october1 #ahea71 from the rock above alluded to1 the first example ever seen of the skeleton of a reptile in the ,old ,red ,sandstone4 ,he has kindly allowed me to give a figure of this fossil1 of which ,dr4 ,mantell has drawn up a detailed osteological account for publication in the ,journal of the ,geological ,society of ,london4 ,the bones in this specimen have decomposed1 but the natural position of almost all of them can be seen1 and nearly perfect casts of their form taken from the hollow moulds which they have left4 ,the matrix is a fine-grained1 whitish sandstone1 with a cement of carbonate of lime4 ,the skeleton exhibits the general characters of the ,lacertians1 blended with peculiarities that are ,batrachian4 ,hence ,dr4 ,mantell infers that this reptile was either a freshwater ,batrachian1 resembling the ,triton1 or a small terrestrial ,lizard4 ,slight indications are visible of very minute conical teeth4 ,captain ,brickenden1 who is well acquainted with the geology of that part of ,scotland1 informs me that this fossil was found in the ,hill of ,spynie1 north of the town of ,elgin1 in a rock quarried for building1 and the same in which the ,chelonian foot-prints1 alluded to in the last page1 occur4 ,the skeleton is about four and a half inches in length1 but part of the tail is concealed in the rock4 ,dr4 ,mantell has proposed for it the generic name of ,telerpeton1 from tele1 afar off1 and herpeton1 a reptile2 while the specific name ,elginense commemorates the principal place near which it was obtained4 ,illustration3 ,fig4 #ebb4 ,natural size4 ,telerpeton ,elginense4 7,mantell47 ,reptile of ,old ,red ,sandstone1 from near ,elgin1 ,morayshire4 ,eggs of ,batrachians 787 in the ,old ,red ,sandstone of ,scotland4--,at page #cdd4 of this work ,i have given two figures 7figs4 #cig and #cih47 of small groups of eggs1 very common in the shales and sandstones of the ,old ,red of ,kincardineshire1 ,forfarshire1 and ,fife4 ,i threw out as a conjecture1 that they might belong to gasteropodous mollusca1 like those represented in fig4 #cii4 p4 #cde42 but ,dr4 ,mantell1 some years ago1 showed me a small bundle of the dried-up eggs of the common ,english frog 7see fig4 #ebd a471 black and carbonaceous1 and so identical in appearance with the fossils in question1 that he suggested the probability of these last being of ,batrachian origin4 ,the plants by which they are often accompanied 7fig4 #cih4 p4 #cdd471 ,i formerly supposed to be ,fuci1 but ,mr4 ,bunbury tells me that their grass-like form agrees well with the idea of their being freshwater1 and of the family ,fluviales4 ,the absence of all shells1 so far as our researches have yet gone1 in the slates and sandstones of ,scotland above alluded to1 raises a presumption against their marine origin1 and a still stronger one against the fossil eggs being those of ,gasteropoda4 ,it is well known that a single female of the ,batrachian tribe ejects annually an astonishing quantity of spawn4 ,mr4 ,newport1 author of many accurate researches into the metamorphoses of the ,amphibia1 having examined my fossils from ,forfarshire1 concurs in ,dr4 ,mantell's opinion that the clusters of eggs 7figs4 #cig4 #cih4 p4 #cdd47 may be those of frogs2 while other larger ones1 occurring singly or in pairs in the same slates1 and often attached to a leaf1 may be the ova of a gigantic ,triton or ,salamander4 7,see figs4 #ebc1 #ebd1 #ebe47 ,i may observe that the subdivision of the ,old ,red ,sandstone1 in which these plants and ova occur 7,no4 #d4 of the section1 fig4 #fb4 p4 #dh471 is considerably lower in position than the rock in which the ,telerpeton of ,elgin is imbedded4 ,illustration3 ,fig4 #ebc4 ,fossil4--,old ,red4 ,fig4 #ebc4 ,slab of ,old ,red ,sandstone1 ,forfarshire1 with eggs of ,batrachians4 a4 ,ova in a carbonized state4 b4 ,egg cells2 the ova shed4 ,illustration3 ,fig4 #ebd4 ,recent4 ,fig4 #ebd4 ,eggs of the common frog1 ,rana temporaria1 in a carbonized state1 from a dried-up pond in ,clapham ,common4 a4 ,the ova4 b4 ,a transverse section of the mass exhibiting the form of the egg-cells4 ,illustration3 ,fig4 #ebe4 ,eggs of ,batrachians4--,old ,red ,sandstone4 ,fig4 #ebe4 ,shale of ,old ,red ,sandstone1 or ,devonian1 ,forfarshire1 with impression of plants and eggs of ,batrachians4 a4 ,two pair of ova resembling those large ,salamanders or ,tritons on the same leaf4 b b4 ,detached ova4 c4 ,egg-cells of frogs or ,ranina4 ,foot-prints of ,lower ,carboniferous reptiles in the ,united ,states4--,i have stated1 at p4 #cdj41 that in #ahdi1 ,mr4 ,isaac ,lea observed the foot-marks of a large reptile in the lowest beds of the coal formation at ,pottsville1 about seventy miles ,n4,e4 of ,philadelphia4 ,these researches have since been carried farther by ,professor ,h4 ,d4 ,rogers1 in the same region of anthracitic coal1 lying on the eastern flank of the ,alleghany ,mountains4 ,beneath the productive coal-measures of that country occurs a dense mass of red shales and sandstones1 which correspond nearly in position to the millstone grit and ,mountain ,limestone of the south-east of ,england4 ,in these beds foot-prints1 referred to three species of quadrupeds1 have lately been detected1 all of them five-toed and in double rows1 with an opposite symmetry1 as if made by right and left feet1 while they likewise display the alternation of fore foot and hind foot4 ,one species1 the largest of the three1 presents a diameter for each foot-print of about two inches1 and shows the fore and hind feet to be nearly equal in dimensions4 ,it exhibits a length of stride of about nine inches1 and a breadth between the right and left treads of nearly four inches4 ,the impressions of the hind feet are but little in the rear of the fore feet4 ,the animal which made them is supposed to have been allied to a ,saurian1 rather than to a ,batrachian or ,chelonian2 but more information is required before so difficult a point can be decided4 ,with these foot-marks were seen shrinkage cracks1 such as are caused by the sun's heat in mud1 and rain-spots1 with the signs of the trickling of water on a wet1 sandy beach2 all confirming the conclusion derived from the foot-prints1 that the quadrupeds belonged to air-breathers1 and not to aquatic races4xii-,a ,the ,cheirotherian foot-prints1 figured by me at p4 #cch41 in which the fore and hind feet are very unequal in size1 betoken a distinct genus1 and occur in the midst of the productive coal measures1 being consequently less ancient4 ,on ,fossil ,rain-marks of the ,carboniferous ,period in ,north ,america4--,having alluded to the spots left by rain on the surface of carboniferous strata in the ,alleghanies1 on which quadrupedal foot-prints are seen1 ,i may mention that similar rain-prints are conspicuous in the coal measures of ,cape ,breton1 in ,nova ,scotia1 in which ,mr4 ,richard ,brown has described ,stigmariae and erect trunks of trees1 and where there are proofs1 as stated at p4 #cbd41 of many fossil forests ranged one above the other4 ,in such a region1 if anywhere1 might we expect to detect evidence of the fall of rain on a sea-beach1 so repeatedly must the conditions of the same area have oscillated between land and sea4 ,the intercalation of deposits1 containing shells of marine or brackish water1 indicate the constant proximity of a body of salt water when the clays which supported the upright trees were formed4 ,in the course of #ahea1 ,mr4 ,brown had the kindness to send me some greenish slates from ,sydney1 ,cape ,breton1 on which are imprinted very delicate impressions of rain-drops1 with several worm-tracks 7a1 b1 fig4 #ebf471 such as usually accompany rain-marks on the recent mud of the ,bay of ,fundy1 and other modern beaches4xii-,b ,illustration3 ,fig4 #ebf4 ,carboniferous rain-prints with worm-tracks 7a1 b7 on green shale1 from ,cape ,breton1 ,nova ,scotia4 ,illustration3 ,fig4 #ebg4 ,casts of rain-prints on a portion of the same slab1 ,no4 #ebf4 seen on the under side of an incumbent layer of arenaceous shale4 ,the arrow represents the direction of the shower4 ,illustration3 ,fig4 #ebh4 ,casts of carboniferous rain-prints and shrinkage-cracks1 7a7 on the under side of a layer of sandstone1 ,cape ,breton1 ,nova ,scotia4 ,the casts of rain-prints1 in figs4 #ebg4 and #ebh41 project from the under side of two layers1 occurring at different levels1 the one a sandy shale1 resting on the green shale 7fig4 #ebf471 the other a sandstone presenting a similar warty or blistered surface1 on which are also observable some small ridges as at a1 which stand out in relief1 and afford evidence of cracks formed by the shrinkage of subjacent clay1 on which rain had fallen4 ,many of the associated sandstones are described by ,mr4 ,brown as ripple-marked4 ,the great humidity of the climate of the coal period had been previously inferred from the nature of its vegetation and the continuity of its forests for hundreds of miles2 but it is satisfactory to have at length obtained such positive proofs of showers of rain1 the drops of which resembled in their average size those which now fall from the clouds4 ,from such data we may presume that the atmosphere of the carboniferous period corresponded in density with that now investing the globe1 and that different currents of air varied then as now1 in temperature1 so as to give rise1 by their mixture1 to the condensation of aqueous vapour4 ,triassic ,mammifer 7,microlestes antiquus ,plieninger47--,in the year #ahdg1 ,professor ,plieninger1 of ,stuttgart1 published a description of two fossil molar teeth1 referred by him to a warm-blooded quadrupedxiii-,a1 which he obtained from a bone-breccia in ,wuertemberg occurring between the lias and the keuper4 ,as the announcement of so novel a fact has never met with the attention it deserved1 we are indebted to ,dr4 ,jaeger1 of ,stuttgart1 for having recently reminded us of it in his ,memoir on the ,fossil ,mammalia of ,wuertemberg4xiii-,b ,fig4 #ebi4 represents the tooth first found1 taken from the plate published in #ahdg1 by ,professor ,plieninger2 and fig4 #ecj4 is a drawing of the same executed from the original by ,mr4 ,hermann von ,meyer1 which he has been kind enough to send me4 ,fig4 #ebi4 is a second and larger molar1 copied from ,dr4 ,jaeger's plate lxxi41 fig4 #ae4 ,illustration3 ,fig4 #ebi4 ,microlestes antiquus1 ,plieninger4 ,molar tooth magnified4 ,upper ,trias1 ,diegerloch1 near ,stuttgart1 ,wuertemberg4 a4 ,view of inner side8 b4 same1 outer side8 c4 ,same in profile4 d4 ,crown of same4 ,illustration3 ,fig4 #ecj4 ,microlestes antiquus1 ,plien4 ,view of same molar as ,no4 #ebi4 ,from a drawing by ,herman von ,meyer4 a4 ,view of inner side8 b4 ,crown of same4 ,illustration3 ,fig4 #eca4 ,molar of ,microlestes8 ,plien4 #d times as large as fig4 #ebi4 ,from the trias of ,diegerloch1 ,stuttgart4 ,professor ,plieninger inferred in #ahdg1 from the double fangs of this tooth and their unequal size1 and from the form and number of the protuberances or cusps on the flat crowns1 that it was the molar of a ,mammifer2 and considering it as predaceous1 probably insectivorous1 he called it ,microlestes1 from mikros1 little1 and lestes1 a beast of prey4 ,soon afterwards1 he found the second tooth also1 at the same locality1 ,diegerloch1 about two miles to the south-east of ,stuttgart4 ,some of its cusps are broken1 but there seem to have been six of them originally4 ,from its agreement in general characters1 it is supposed by ,professor ,plieninger to be referable to the same animal1 but as it is four times as big1 it may perhaps have belonged to another allied species4 ,this molar is attached to the matrix consisting of sandstone1 whereas the tooth1 ,no4 #ebi41 is isolated4 ,several fragments of bone1 differing in structure from that of the associated saurians and fish1 and believed to be mammiferous1 were imbedded near them in the same rock4 ,mr4 ,waterhouse1 of the ,british ,museum1 after studying the annexed figs4 #ebi4 #eca4 and the descriptions of ,prof4 ,plieninger1 observes1 that not only the double roots of the teeth and their crowns presenting several cusps1 resemble those of ,mammalia1 but the cingulum also1 or ridge surrounding the base of that part of the body of the tooth which was exposed or above the gum1 is a character distinguishing them from fish and reptiles4 ,the arrangement of the six cusps or tubercles in two rows1 in fig4 #ebi41 with a groove or depression between them and the oblong form of the tooth1 lead him1 he says1 to regard it as a molar of the lower jaw4 ,both the teeth differ from those of the ,stonesfield ,mammaliaxiv-,a1 but do not supply sufficient data for determining to what order they belonged4 ,even in regard to the ,stonesfield jaws1 where we possess so much ampler materials1 we cannot safely pronounce on the order4 ,professor ,plieninger has sent me a cast of the smaller tooth1 which exhibits well the characteristic mammalian test1 the double fang2 but ,mr4 ,owen1 to whom ,i have shown it1 is not able to recognize its affinity with any mammalian type1 recent or extinct1 known to him4 ,it has already been stated that the stratum in which the above-mentioned fossils occur is intermediate between the lias and the uppermost member of the trias4 ,that it is really triassic may be deduced from the following considerations4 ,in ,wuertemberg there are two bone-beds1 one of great extent1 and very rich in the remains of fish and reptiles1 which intervenes between the muschelkalk and keuper1 the other1 containing the ,microlestes1 less extensive and fossiliferous1 which rests on the keuper1 or superior member of the trias1 and is covered by the sandstone of the lias4 ,the last-mentioned breccia therefore occupies the same place as the well-known ,english bone-bed of ,axmouth and ,aust-cliff near ,bristol1 which is shownxv-,a to include characteristic species of muschelkalk fish1 of the genus ,saurichthys1 ,hybodus1 and ,gyrolepis4 ,in both the ,wuertemberg bone-beds these three genera are also found1 and one of the species1 ,saurichthys ,mougeotii1 is common to both the lower and upper breccias1 as is also a remarkable reptile called ,nothosaurus mirabilis4 ,the ,saurian called ,belodon by ,h4 ,von ,meyer of the ,thecodont family1 is another ,triassic form1 associated at ,diegerloch with ,microlestes4 ,previous to this discovery of ,professor ,plieninger1 the most ancient of known fossil ,mammalia were those of the ,stonesfield slate1 a subdivision of the ,lower ,oolitexv-,b no representative of this class having as yet been met with in the ,fuller's earth1 or inferior ,oolite 7see ,table1 p4 #beh471 nor in any member of the lias4 ,thecodont ,saurians4--,this family of reptiles is common to the ,trias and ,permian groups in ,germany1 and the geologists employed in the government survey of ,great ,britain have come to the conclusion1 that the rock containing the two species alluded to at p4 #cjf41 and of which the teeth are represented in figs4 #cdh1 #cdi41 ought rather to be referred to the ,trias than to the ,permian group4 ,,cretaceous ,,gasteropoda4 ,in speaking of the chalk of ,faxoe in ,denmark 7p4 #baj47 or the highest member of the ,cretaceous series1 ,i have remarked that it is characterized by univalve ,mollusca1 both spiral and patelliform1 which are wanting or rare in the white chalk of ,europe4 ,this last statement requires1 ,i find1 some modification4 ,it holds true in regard to certain forms1 such as ,cypraea and ,oliva1 found at ,faxoe2 but ,m4 ,a4 d',orbigny enumerates #bd species of ,gasteropoda from the white chalk 7,terrain ,senonien7 of ,france alone4 ,the same author describes #acd ,french species of ,gasteropoda from the chloritic chalk marl and upper greensand 7,turonien71 #gg from the gault1 and #ij from the lower greensand 7,neocomien71 in all #cbe species of ,gasteropoda1 from the cretaceous group below the ,maestricht beds4 ,among these he refers #a to the genus ,mitra1 #ag to ,fusus1 #ag to ,trochus1 #d to ,emarginula1 and #cf to ,cerithium4 ,notwithstanding1 therefore1 the peculiarity of the chambered univalves of various genera1 so abundant in the chalk1 the ,mollusca of the period approximate in character to the tertiary and recent ,fauna far more than was formerly supposed4 ,,dicotyledonous ,,leaves ,,in ,,lower ,,cretaceous ,,strata4 ,m4 ,adolphe ,brongniart when founding his classification of the fossiliferous strata in reference to their imbedded fossil plants1 has placed the cretaceous group in the same division with the tertiary1 that is to say1 in his ,age of ,angiosperms4xvi-,a ,this arrangement is based on the fact1 that the cretaceous plants display a transition character from the vegetation of the secondary to that of the tertiary periods4 ,coniferae and ,cycadeae still flourished as in the preceding oolitic and triassic epochs2 but with these fossils1 some well-marked leaves of dicotyledonous trees referred to several species of the genus ,credneria1 had been found in ,germany in the ,quadersandstein and ,plaener-kalk4 ,still more recently1 ,dr4 ,debey of ,aix-la-,chapelle has met with a great variety of other leaves of dicotyledonous plants in the cretaceous floraxvi-,b1 of which he enumerates no less than #bf species1 some of the leaves being from four to six inches in length1 and in a beautiful state of preservation4 ,in the absence of the organs of fructification and of fossil fruits1 the number of species may be exaggerated2 but we may nevertheless affirm1 reasoning from our present data1 that in the lower chalk of ,aix-la-,chapelle1 ,dicotyledonous ,angiosperms flourished nearly in equal proportions with ,gymnosperms2 a fact of great significance1 as some geologists had wished to connect the rarity of dicotyledonous trees with a peculiarity in the state of the atmosphere in the earlier ages of the planet1 imagining that a denser air and noxious gases1 especially carbonic acid in excess1 were adverse to the prevalence1 not only of the quick-breathing classes of animals1 7mammalia and birds17 but to a flora like that now existing1 while it favoured the predominance of reptile life1 and a cryptogamic and gymnospermous flora4 ,the co-existence1 therefore1 of dicotyledonous angiosperms in abundance with ,cycads and ,coniferae1 and with a rich reptilian fauna comprising the ,iguanodon1 ,ichthyosaurus1 ,pliosaurus1 and ,pterodactyl1 in the lower cretaceous series tends1 like the oolitic mammalia of ,stonesfield and ,stuttgart1 and the triassic birds of ,connecticut1 to dispel the idea of a meteorological state of things in the secondary periods widely distinct from that now prevailing4 ,general remarks4--,in the preliminary chapters of ,the ,principles of ,geology1 in the first and subsequent editions1 ,i have considered the question1 how far the changes of the earth's crust in past times confirm or invalidate the popular hypothesis of a gradual improvement in the habitable condition of the planet1 accompanied by a contemporaneous development and progression in organic life4 ,it had long been a favourite theory1 that in the earlier ages to which we can carry back our geological researches1 the earth was shaken by more frequent and terrible earthquakes than now1 and that there was no certainty nor stability in the order of the natural world4 ,a few sea-weeds and zoophytes1 or plants and animals of the simplest organization1 were alone capable of existing in a state of things so unfixed and unstable4 ,but in proportion as the conditions of existence improved1 and great convulsions and catastrophes became rarer and more partial1 flowering plants were added to the cryptogamic class1 and by the introduction of more and more perfect species1 a varied and complex flora was at last established4 ,in like manner1 in the animal kingdom1 the zoophyte1 the brachiopod1 the cephalopod1 the fish1 the reptile1 the bird1 and the warm-blooded quadruped made their entrance into the earth1 one after the other1 until finally1 after the close of the tertiary period1 came the quadrumanous mammalia1 most nearly resembling man in outward form and internal structure1 and followed soon afterwards1 if not accompanied at first1 by the human race itself4 ,the objections which1 in #ahcj1 ,i urged against this doctrinexvii-,a1 in so far as relates to the passage of the earth from a chaotic to a more settled condition1 have since been embraced by a large and steadily increasing school of geologists2 and in reference to the animate world1 it will be seen1 on comparing the present state of our knowledge with that which we possessed twenty years ago1 how fully ,i was justified in declaring the insufficiency of the data on which such bold generalizations1 respecting progressive development1 were based4 ,speaking of the absence1 from the tertiary formations1 of fossil ,quadrumana1 ,i observed1 in #ahcj1 that we had no right to expect to have detected any remains of tribes which live in trees1 until we knew more of those quadrupeds which frequent marshes1 rivers1 and the borders of lakes1 such being usually first met with in a fossil state4xvii-,b ,i also added1 if we are led to infer1 from the presence of crocodiles and turtles in the ,london clay1 and from the cocoa-nuts and spices found in the isle of ,sheppey1 that at the period when our older tertiary strata were formed1 the climate was hot enough for the ,quadrumana1 we nevertheless could not hope to discover any of their skeletons1 until we had made considerable progress in ascertaining what were the contemporary ,pachydermata2 and not one of these has been discovered as yet in any strata of this epoch in ,england4 ,nine years afterwards1 when these fossil ,pachyderms had been found in the ,london clay1 and in the sandy strata at its base1 the remains of a monkey1 of the genus ,macacus1 were detected near ,woodbridge1 in ,suffolk2 and other ,quadrumana had been met with1 a short time previously1 in different stages of the tertiary series1 in ,india1 ,france1 and ,brazil4 ,when we consider the small area of the earth's surface hitherto examined geologically1 and our scanty acquaintance with the fossil ,vertebrata1 even of the environs of great ,european capitals1 it is truly surprising that any naturalist should be rash enough to assume that the ,lower ,eocene deposits mark the era of the first creation of ,quadrumana4 ,it is1 however1 still more unphilosophical to infer from a single extinct species of this order1 obtained in a latitude far from the tropics1 that the ,eocene ,quadrumana had not attained as high a grade of organization as those of our own times1 when the naturalist is acquainted with all1 or nearly all1 the species of monkeys1 apes and orangs which are contemporary with man4 ,to return to the year #ahcj1 ,mammalia had not then been traced to rocks of higher antiquity than the ,stonesfield ,oolite1 whereas we have just seen that memorials of this class have at length made their appearance in the ,trias of ,germany4 ,in #ahcj birds had been discovered no lower in the series than the ,paris gypsum1 or ,middle ,eocene4 ,their bones have now been found both in ,england and the ,swiss ,alps in the ,lower ,eocene1 and their existence has been established by foot-prints in the triassic epoch in ,north ,america 7p4 #big474 ,reptiles in #ahcj had not been detected in rocks older than the ,magnesian limestone1 or ,permian formation2 whereas the skeletons of four species have since been brought to light 7see p4 #ccf47 in the coal-measures1 and one in the ,old ,red sandstone1 of ,europe1 while the footprints of three or four more have been observed in carboniferous rocks of ,north ,america1 not to mention the chelonian trail above described1 from the most ancient of the fossiliferous rocks of ,canada1 the ,potsdam ,sandstone1 which lies at the base of the ,lower ,silurian system4 7,see above1 p4 vii47 ,lastly1 the remains of fish1 which in #ahcj were scarcely recognized in deposits older than the coal1 have now been found plentifully in the ,devonian1 and sparingly in the ,silurian1 strata2 though not in any formation of such high antiquity as the ,chelonian of ,montreal4 ,previously to the discovery last mentioned1 it was by no means uncommon for paleontologists to speak with confidence of fish as having been created before reptiles4 ,it was deemed reasonable to suppose that the introduction of a particular class or order of beings into the planet coincided1 in date1 with the age of the oldest rock to which the remains of that class or order happened then to have been traced back4 ,to be consistent with themselves1 the same naturalists ought now to take for granted that reptiles were called into existence before fish4 ,this they will not do1 because such a conclusion would militate against their favourite hypothesis of an ascending scale1 according to which ,nature evolved the organic world1 rendering it more and more perfect in the lapse of ages4 ,in our efforts to arrive at sound theoretical views on such a question1 it would seem most natural to turn to the marine invertebrate animals as to a class affording the most complete series of monuments that have come down to us1 and where we can find corresponding terms of comparison1 in strata of every age4 ,if1 in this more complete series of her archives1 ,nature had really exhibited a more simple grade of organization in fossils of the remotest antiquity1 we might have suspected that there was some foundation of facts in the theory of successive development4 ,but what do we find8 ,in the ,lower ,silurian there is a full representation of the ,radiata1 ,mollusca1 and ,articulata proper to the sea4 ,the marine ,fauna1 indeed1 in those three classes1 is so rich as almost to imply a more perfect development than that which now peoples the ocean4 ,thus1 in the great division of the ,radiata1 we find asteroid and helianthoid zoophytes1 besides crinoid and cystidean echinoderms4 ,in the ,mollusca of the same most ancient epoch ,m4 ,barrande enumerates1 in ,bohemia alone1 the astonishing number of #bec species of ,cephalopoda4 ,in the ,articulata we have the crustaceans1 represented by more than #bjj species of ,trilobites1 not to mention other genera4 ,it is only then1 in reference to the ,vertebrata1 that the argument of degeneracy in proportion as we trace fossils back to older formations can be maintained2 and the dogma rests mainly for its support on negative evidence1 whether deduced from the entire absence of the fossil representatives of certain classes in particular rocks1 or the low grade of the first few species of a class which chance has thrown in our way4 ,the scarcity of all memorials of birds in strata below the ,eocene1 has been a subject of surprise to some geologists4 ,the bones formerly referred to birds in the ,wealden and ,chalk1 are now admitted to have belonged to flying reptiles1 of various sizes1 one of them from the ,kentish chalk so large as to have measured #af feet #f inches from tip to tip of its outstretched wings4 ,whether some elongated bones of the ,stonesfield ,oolite should be referred to birds1 which they seem greatly to resemble in microscopic structure or to ,pterodactyles1 is a point now under investigation4 ,if it should be proved that no osseous remains of the class ,aves have hitherto been derived from any secondary or primary formation1 we must not too hastily conclude that birds were even scarce in these periods4 ,the rarity of such fossils in the ,eocene marine strata is very striking4 ,in #ahdf1 ,professor ,owen1 in his ,history of the ,fossil ,mammalia and ,birds of ,great ,britain1 was unable to obtain more than four or five fragments of bones and skulls of birds from the ,london ,clay1 by the aid of which four species were recognized4 ,even so recently1 therefore1 as #ahdf1 as much was known of the ,mammalia of the ,stonesfield ,oolite1 as of the ornithic ,fauna of our ,english ,eocene deposits4 ,to reason correctly on the value of negative facts in this branch of ,paleontology1 we must first have ascertained how far the relics of birds are now becoming preserved in new strata1 whether marine1 fluviatile1 or lacustrine4 ,i have explained1 in the ,principles of ,geology1 that the imbedding of the bones of living birds in deposits now in progress in inland lakes appears to be extremely rare4 ,in the shell-marl of ,scotland1 which is made up bodily of the shells of the genera ,limneus1 ,planorbis1 ,succinea1 and ,valvata1 and in which the skeletons of deer and oxen abound1 we find no bones of birds4 ,yet we know that1 before the lakes were drained which yield this marl used in agriculture1 the surface of the water and the bordering swamps were covered with wild ducks1 herons1 and other fowl4 ,they left no memorials behind them1 because1 if they perished on the land1 their bodies decomposed or became the prey of carnivorous animals2 if on the water1 they were buoyant and floated till they were devoured by predaceous fish or birds4 ,the same causes of obliteration have no power to efface the foot-prints which the same creatures may leave1 under favourable circumstances1 imprinted on an ancient mud-bank or shore1 on which new strata may be from time to time thrown down4 ,in the red mud of recent origin spread over wide areas by the high tides of the bay of ,fundy1 innumerable foot-tracks of recent birds 7,tringa minuta7 are preserved in successive layers1 and hardened by the sun4 ,yet none of the bones of these birds1 though diligently searched for1 have yet been discovered in digging trenches through the red mud4 ,it is true that1 in a few spots1 the bones of birds have been met with plentifully in the older tertiary strata1 but always in rocks of freshwater origin1 such as the ,paris gypsum or the lacustrine limestone of the ,limagne d',auvergne4 ,in strata of the same age1 in ,belgium and other ,european countries1 or in the ,united ,states1 where no less careful search has been made1 few1 if any1 fossil birds have come to light4 ,we ought1 therefore1 most clearly to perceive that it is no part of the plan of ,nature to hand down to after times a complete or systematic record of the former history of the animate world4 ,the preservation of the relics1 even of aquatic tribes of animals1 is an exception to the general rule1 although time may so multiply exceptional cases that they may seem to constitute the rule2 and may thus impose upon the imagination1 leading us to infer the non-existence of creatures of which no monuments are extant4 ,hitherto our acquaintance with the birds1 and even the ,mammalia1 of the ,eocene period has depended1 almost everywhere1 on single specimens1 or on a few individuals found in one spot4 ,it has therefore depended on what we commonly call chance2 and we must not wonder if the casual discovery of a tertiary1 secondary1 or primary rock1 rich in fossil impressions of the foot-prints of birds or quadrupeds1 should modify or suddenly overthrow all theories based on negative facts4 ,the chief reason why we meet more readily with the remains of every class in tertiary than in secondary strata1 is simply that the older rocks are more and more exclusively marine in proportion as we depart farther and farther from periods during which the existing continents were built up4 ,the secondary and primary formations are1 for the most part1 marine1--not because the ocean was more universal in past times1 but because the epochs which preceded the ,eocene were so distant from our own1 that entire continents have been since submerged4 ,i have alluded at p4 #bii4 to ,mr4 ,darwin's account of the ,south ,american ,ostriches1 seen on the coast of ,buenos ,ayres1 walking at low water over extensive mud-banks1 which are then dry1 for the sake of feeding on small fish4 ,perhaps no bird of such perfect organization as the eagle or vulture may ever accompany these ostriches4 ,certainly1 we cannot expect the condor of the ,andes to leave its trail on such a shore2 and no traveller1 after searching for footprints along the whole eastern coast of ,south ,america1 would venture to speculate1 from the results of such an inquiry1 on the extent1 variety1 or development of the feathered ,fauna of the interior of that continent4 ,the absence of ,cetacea from rocks older than the ,eocene has been frequently adduced as lending countenance to the theory of the late appearance of the highest class of ,vertebrata on the earth4 ,that we have hitherto failed to detect them in the ,oolite or ,trias1 does not imply1 as we have now seen1 that ,mammalia were not then created4 ,even in the ,eocene strata of ,europe1 the discovery of ,cetaceans has never kept pace with that of land quadrupeds4 ,the only instance cited in ,great ,britain is a species of ,monodon1 from the ,london clay1 of doubtful authenticity as to its geological position4 ,on the other hand1 the gigantic ,zeuglodon of ,north ,america 7see p4 #bjg471 occurs abundantly in the ,middle ,eocene strata of ,georgia and ,alabama1 from which as yet no bones of land-quadrupeds have been obtained4 ,professor ,sedgwick states in a recent workxxi-,a1 that he possesses in the ,woodwardian ,museum1 a mass of anchylosed cervical vertebrae of a whale which he found near ,ely1 and which he believes to have been washed out of the ,kimmeridge clay1 a member of the ,upper ,oolite2 but its true geological site is not well determined4 ,it differs1 says ,professor ,owen1 from any other known fossil or recent whale4 ,in the present imperfect state then of our information1 we can scarcely say more than that the ,cetacea may have been scarce1 in the secondary and primary periods4 ,it is quite conceivable that when aquatic saurians1 some of them carnivorous1 like the ,ichthyosaurus1 were swarming in the sea1 and when there were large herbivorous reptiles1 like the ,iguanodon1 on the land1 such reptiles may1 to a certain extent1 have superseded the ,cetacea1 and discharged their functions in the animal economy4 ,the views which ,i proposed originally in the ,principles of ,geology in opposition to the theory of progressive development may be thus briefly explained4 ,from the earliest period at which plants and animals can be proved to have existed1 there has been a continual change going on in the position of land and sea1 accompanied by great fluctuations of climate4 ,to these ever-varying geographical and climatal conditions the state of the animate world has been unceasingly adapted4 ,no satisfactory proof has yet been discovered of the gradual passage of the earth from a chaotic to a more habitable state1 nor of a law of progressive development governing the extinction and renovation of species1 and causing the ,fauna and ,flora to pass from an embryonic to a more perfect condition1 from a simple to a more complex organization4 ,the principle of adaptation above alluded to1 appears to have been analogous to that which now peoples the arctic1 temperate1 and tropical regions contemporaneously with distinct assemblages of species and genera1 or which independently of mere temperature gives rise to a predominance of the marsupial tribe of quadrupeds in ,australia1 and of the placental tribe in ,asia and ,europe1 or to a profusion of reptiles without mammalia in the ,galapagos ,archipelago1 and of mammalia without reptiles in ,greenland4xxii-,a ,this theory implies1 almost necessarily1 a very unequal representation at successive periods of the principal classes and orders of plants and animals1 if not in the whole globe1 at least throughout very wide areas4 ,thus1 for example1 the proportional number of genera1 species1 and individuals in the vertebrate class may differ1 in two different and distinct epochs1 to an extent unparalleled by any two contemporaneous ,faunas1 because in the course of millions of ages1 the contrast of climate and geographical conditions may exceed the difference now observable in polar and equatorial latitudes4 ,i shall conclude by observing1 that if the doctrine of successive development had been paleontologically true1 as the new discoveries above enumerated show that it is not2 if the sponge1 the cephalopod1 the fish1 the reptile1 the bird1 and the mammifer had followed each other in regular chronological order--the creation of each class being separated from the other by vast intervals of time2 and if it were admitted that ,man was created last of all1 still we should by no means be able to recognize1 in his entrance upon the earth1 the last term of one and the same series of progressive developments4 ,for the superiority of ,man1 as compared to the irrational mammalia1 is one of kind1 rather than of degree1 consisting in a rational and moral nature1 with an intellect capable of indefinite progression1 and not in the perfection of his physical organization1 or those instincts in which he resembles the brutes4 ,he may be considered as a link in the same unbroken chain of being1 if we regard him simply as a new species--a member of the animal kingdom--subject1 like other species1 to certain fixed and invariable laws1 and adapted like them to the state of the animate and inanimate world prevailing at the time of his creation4 ,physically considered1 he may form part of an indefinite series of terrestrial changes past1 present1 and to come2 but morally and intellectually he may belong to another system of things--of things immaterial--a system which is not permitted to interrupt or disturb the course of the material world1 or the laws which govern its changes4xxii-,b ,,footnotes3 vii-,a ,travels in ,north ,america by the ,author1 vol4 ii4 chap4 #bb4 vii-,b ,ibid4 #ahdb4 viii-,a ,quart4 ,journ4 ,geol4 ,soc4 #ahea1 vol4 vii4 p4 #bej4 ix-,a ,the generally received determination of the age of this rock is probably correct2 but as there are no overlying coal-measures and no well-known ,devonian fossils in the whitish stone of ,elgin1 and as ,i have not personally explored the geology of that district1 ,i cannot speak as confidently as in regard to the age of the ,montreal ,chelonian4 xii-,a ,h4 ,d4 ,rogers1 ,proceedings of ,amer4 ,assoc4 of ,science1 ,albany1 #ahea4 xii-,b ,see ,memoir by the ,author1 ,quart4 ,journ4 ,geol4 ,soc41 vol4 vii4 p4 #bdj4 xiii-,a ,wuertembergisch4 ,naturwissen4 ,jahreshefte1 #c ,jahr4 ,stuttgart1 #ahdg4 xiii-,b ,nov4 ,act4 ,acad4 ,caesar4 ,leopold4 ,nat4 ,cur4 #ahej1 p4 #ijb4 ,for figures1 see ibid4 plate xxi4 figs4 #ad1 #ae1 #af1 #ag4 xiv-,a ,see ,manual1 p4 #bfh4 xv-,a ,manual1 p4 #bhi4 xv-,b ,ibid4 p4 #bfh4 xvi-,a ,for ,terminology1 see ,note1 p4 #bbc4 xvi-,b ,quart4 ,journ4 vol4 vii4 ,memoirs1 p4 #aaa4 xvii-,a ,principles1 #ast ed4 chaps4 v4 and ix4 xvii-,b ,ibid4 p4 #aec4 xxi-,a ,preface to #eth ed4 of ,studies of ,university of ,cambridge4 xxii-,a ,principles1 #dth ed4 #ahce1 vol4 i4 p4 #bca1 and vol4 i4 chap4 #i4 subsequent ed4 xxii-,b ,in my ,anniversary ,address1 for #ahea1 to the ,geological ,society1 the reader will find a full discussion of the facts and arguments which bear on the theory of progressive development4--,quart4 ,journ4 ,geol4 ,soc41 vol4 vii4 ,,contents4 ,,chapter ,i4 ,,on ,,the ,,different ,,classes ,,of ,,rocks4 ,geology defined--,successive formation of the earth's crust--,classification of rocks according to their origin and age--,aqueous rocks--,their stratification and imbedded fossils--,volcanic rocks1 with and without cones and craters--,plutonic rocks1 and their relation to the volcanic--,metamorphic rocks and their probable origin--,the term primitive1 why erroneously applied to the crystalline formations--,leading division of the work ,page #a ,,chapter ,,ii4 ,,aqueous ,,rocks--,,their ,,composition ,,and ,,forms ,,of ,,stratification4 ,mineral composition of strata--,arenaceous rocks--,argillaceous--,calcareous--,gyps um--,forms of stratification--,original horizontality--,thinning out--,diagonal arrangement--,ripple mark #aj ,,chapter ,,iii4 ,,arrangement ,,of ,,fossils ,,in ,,strata--,,freshwater ,,and ,,marine4 ,successive deposition indicated by fossils--,limestones formed of corals and shells--,proofs of gradual increase of strata derived from fossils--,serpula attached to spatangus--,wood bored by ,teredina--,tripoli and semi-opal formed of infusoria--,chalk derived principally from organic bodies--,distinction of freshwater from marine formations--,genera of freshwater and land shells--,rules for recognizing marine testacea--,gyrogonite and chara--,freshwater fishes--,alternation of marine and freshwater deposits--,lym-,fiord #ba ,,chapter ,,iv4 ,,consolidation ,,of ,,strata ,,and ,,petrifaction ,,of ,,fossils4 ,chemical and mechanical deposits--,cementing together of particles--,hardening by exposure to air--,concretionary nodules--,consolidating effects of pressure--,mineralization of organic remains--,impressions and casts how formed--,fossil wood--,goeppert's experiments--,precipitation of stony matter most rapid where putrefaction is going on--,source of lime in solution--,silex derived from decomposition of felspar--,proofs of the lapidification of some fossils soon after burial1 of others when much decayed #cc ,,chapter ,v4 ,,elevation ,,of ,,strata ,,above ,,the ,,sea--,,horizontal ,,and ,,inclined ,,stratification4 ,why the position of marine strata1 above the level of the sea1 should be referred to the rising up of the land1 not to the going down of the sea--,upheaval of extensive masses of horizontal strata--,inclined and vertical stratification--,anticlinal and synclinal lines--,bent strata in east of ,scotland--,theory of folding by lateral movement--,creeps--,dip and strike--,structure of the ,jura--,various forms of outcrop--,rocks broken by flexure--,inverted position of disturbed strata--,unconformable stratification--,hutton and ,playfair on the same--,fractures of strata--,polished surfaces--,faults--,appearance of repeated alternations produced by them--,origin of great faults ,page #dd ,,chapter ,,vi4 ,,denudation4 ,denudation defined--,its amount equal to the entire mass of stratified deposits in the earth's crust--,horizontal sandstone denuded in ,ross-shire--,levelled surface of countries in which great faults occur--,coalbrook ,dale--,denuding power of the ocean during the emergence of land--,origin of ,valleys--,obliteration of sea-cliffs--,inland sea-cliffs and terraces in the ,morea and ,sicily--,limestone pillars at ,st4 ,mihiel1 in ,france--in ,canada--in the ,bermudas #ff ,,chapter ,,vii4 ,,alluvium4 ,alluvium described--,due to complicated causes--,of various ages1 as shown in ,auvergne--,how distinguished from rocks in situ--,river-terraces--,parallel roads of ,glen ,roy--,various theories respecting their origin #gi ,,chapter ,,viii4 ,,chronological ,,classification ,,of ,,rocks4 ,aqueous1 plutonic1 volcanic1 and metamorphic rocks1 considered chronologically--,lehman's division into primitive and secondary--,werner's addition of a transition class--,neptunian theory--,hutton on igneous origin of granite--,how the name of primary was still retained for granite--,the term transition1 why faulty--,the adherence to the old chronological nomenclature retarded the progress of geology--,new hypothesis invented to reconcile the igneous origin of granite to the notion of its high antiquity--,explanation of the chronological nomenclature adopted in this work1 so far as regards primary1 secondary1 and tertiary periods #hi ,,chapter ,,ix4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,aqueous ,,rocks4 ,on the three principal tests of relative age--superposition1 mineral character1 and fossils--,change of mineral character and fossils in the same continuous formation--,proofs that distinct species of animals and plants have lived at successive periods--,distinct provinces of indigenous species--,great extent of single provinces--,similar laws prevailed at successive geological periods--,relative importance of mineral and palaeontological characters--,test of age by included fragments--,frequent absence of strata of intervening periods--,principal groups of strata in western ,europe #if ,,chapter ,x4 ,,classification ,,of ,,tertiary ,,formations4--,,post-,,pliocene ,,group4 ,general principles of classification of tertiary strata--,detached formations scattered over ,europe--,strata of ,paris and ,london--,more modern groups--,peculiar difficulties in determining the chronology of tertiary formations--,increasing proportion of living species of shells in strata of newer origin--,terms ,eocene1 ,miocene1 and ,pliocene--,post-,pliocene strata--,recent or human period--,older ,post-,pliocene formations of ,naples1 ,uddevalla1 and ,norway--,ancient upraised delta of the ,mississippi--,loess of the ,rhine ,page #ajd ,,chapter ,,xi4 ,,newer ,,pliocene ,,period4--,,boulder ,,formation4 ,drift of ,scandinavia1 northern ,germany1 and ,russia--,its northern origin--,not all of the same age--,fundamental rocks polished1 grooved1 and scratched--,action of glaciers and icebergs--,fossil shells of glacial period--,drift of eastern ,norfolk--,associated freshwater deposit--,bent and folded strata lying on undisturbed beds--,shells on ,moel ,tryfane--,ancient glaciers of ,north ,wales--,irish drift #aba ,,chapter ,,xii4 ,,boulder ,,formation--continued4 ,difficulty of interpreting the phenomena of drift before the glacial hypothesis was adopted--,effects of intense cold in augmenting the quantity of alluvium--,analogy of erratics and scored rocks in ,north ,america and ,europe--,bayfield on shells in drift of ,canada--,great subsidence and re-elevation of land from the sea1 required to account for glacial appearances--,why organic remains so rare in northern drift--,mastodon giganteus in ,united ,states--,many shells and some quadrupeds survived the glacial cold--,alps an independent centre of dispersion of erratics--,alpine blocks on the ,jura--,recent transportation of erratics from the ,andes to ,chiloe--,meteorite in ,asiatic drift #aca ,,chapter ,,xiii4 ,,newer ,,pliocene ,,strata ,,and ,,cavern ,,deposits4 ,chronological classification of ,pleistocene formations1 why difficult--,freshwater deposits in valley of ,thames--,in ,norfolk cliffs--,in ,patagonia--,comparative longevity of species in the mammalia and testacea--,fluvio-marine crag of ,norwich--,newer ,pliocene strata of ,sicily--,limestone of great thickness and elevation--,alternation of marine and volcanic formations--,proofs of slow accumulation--,great geographical changes in ,sicily since the living fauna and flora began to exist--,osseous breccias and cavern deposits--,sicily--,kirkdale--,origin of stalactite--,australian cave-breccias--,geographical relationship of the provinces of living vertebrata and those of the fossil species of the ,pliocene periods--,extinct struthious birds of ,new ,zealand--,teeth of fossil quadrupeds #adf ,,chapter ,,xiv4 ,,older ,,pliocene ,,and ,,miocene ,,formations4 ,strata of ,suffolk termed ,red and ,coralline crag--,fossils1 and proportion of recent species--,depth of sea and climate--,reference of ,suffolk crag to the older ,pliocene period--,migration of many species of shells southwards during the glacial period--,fossil whales--,subapennine beds--,asti1 ,sienna1 ,rome--,miocene formations--,faluns of ,touraine--,depth of sea and littoral character of fauna--,tropical climate implied by the testacea--,proportion of recent species of shells--,faluns more ancient than the ,suffolk crag--,miocene strata of ,bordeaux and ,piedmont--,molasse of ,switzerland--,tertiary strata of ,lisbon--,older ,pliocene and ,miocene formations in the ,united ,states--,sewalik ,hills in ,india #afa ,,chapter ,,xv4 ,,upper ,,eocene ,,formations4 ,eocene areas in ,england and ,france--,tabular view of ,french ,eocene strata--,upper ,eocene group of the ,paris basin--,same beds in ,belgium and at ,berlin--,mayence tertiary strata--,freshwater upper ,eocene of ,central ,france--,series of geographical changes since the land emerged in ,auvergne--,mineral character an uncertain test of age--,marls containing ,cypris--,oolite of ,eocene period--,indusial limestone and its origin--,fossil mammalia of the upper ,eocene strata in ,auvergne--,freshwater strata of the ,cantal1 calcareous and siliceous--,its resemblance to chalk--,proofs of gradual deposition of strata #agd ,,chapter ,,xvi4 ,,eocene ,,formations--continued4 ,subdivisions of the ,eocene group in the ,paris basin--,gypseous series--,extinct quadrupeds--,impulse given to geology by ,cuvier's osteological discoveries--,shelly sands called sables moyens--,calcaire grossier--,miliolites--,calcaire siliceux--,lower ,eocene in ,france--,lits coquilliers--,sands and plastic clay--,english ,eocene strata--,freshwater and fluvio-marine beds--,barton beds--,bagshot and ,bracklesham division--,large ophidians and saurians--,lower ,eocene and ,london ,clay proper--,fossil plants and shells--,strata of ,kyson in ,suffolk--,fossil monkey and opossum--,mottled clays and sand below ,london ,clay--,nummulitic formation of ,alps and ,pyrenees--,its wide geographical extent--,eocene strata in the ,united ,states--,section at ,claiborne1 ,alabama--,colossal cetacean--,orbitoid limestone--,burr stone #aij ,,chapter ,,xvii4 ,,cretaceous ,,group4 ,divisions of the cretaceous series in ,north-,western ,europe--,upper cretaceous strata--,maestricht beds--,chalk of ,faxoe--,white chalk--,characteristic fossils--,extinct cephalopoda--,sponges and corals of the chalk--,signs of open and deep sea--,white area of white chalk--,its origin from corals and shells--,single pebbles in chalk--,siliceous sandstone in ,germany contemporaneous with white chalk--,upper greensand and gault--,lower cretaceous strata--,atherfield section1 ,isle of ,wight--,chalk of ,south of ,europe--,hippurite limestone--,cretaceous ,flora--,chalk of ,united ,states #bji ,,chapter ,,xviii4 ,,wealden ,,group4 ,the ,wealden divisible into ,weald ,clay1 ,hastings ,sand1 and ,purbeck ,beds--,intercalated between two marine formations--,weald clay and ,cypris-bearing strata--,iguanodon--,hastings sands--,fossil fish--,strata formed in shallow water--,brackish water-beds--,upper1 middle1 and lower ,purbeck--,alternations of brackish water1 freshwater1 and land--,dirt-bed1 or ancient soil--,distinct species of fossils in each subdivision of the ,wealden--,lapse of time implied--,plants and insects of ,wealden--,geographical extent of ,wealden--,its relation to the cretaceous and oolitic periods--,movements in the earth's crust to which it owed its origin and submergence #bbe ,,chapter ,,xix4 ,,denudation ,,of ,,the ,,chalk ,,and ,,wealden4 ,physical geography of certain districts composed of ,cretaceous and ,wealden strata--,lines of inland chalk-cliffs on the ,seine in ,normandy--,outstanding pillars and needles of chalk--,denudation of the chalk and ,wealden in ,surrey1 ,kent1 and ,sussex--,chalk once continuous from the ,north to the ,south ,downs--,anticlinal axis and parallel ridges--,longitudinal and transverse valleys--,chalk escarpments--,rise and denudation of the strata gradual--,ridges formed by harder1 valleys by softer beds--,why no alluvium1 or wreck of the chalk1 in the central district of the ,weald--,at what periods the ,weald valley was denuded--,land has most prevailed where denudation has been greatest--,elephant bed1 ,brighton #bch ,,chapter ,,xx4 ,,oolite ,,and ,,lias4 ,subdivisions of the ,oolitic or ,jurassic group--,physical geography of the ,oolite in ,england and ,france--,upper ,oolite--,portland stone and fossils--,lithographic stone of ,solenhofen--,middle ,oolite1 coral rag--,zoophytes--,nerinaean limestone--,diceras limestone--,oxford clay1 ,ammonites and ,belemnites--,lower ,oolite1 ,crinoideans--,great ,oolite and ,bradford clay--,stonesfield slate--,fossil mammalia1 placental and marsupial--,resemblance to an ,australian fauna--,doctrine of progressive development--,collyweston slates--,yorkshire ,oolitic coal-field--,brora coal--,inferior ,oolite and fossils #beg ,,chapter ,,xxi4 ,,oolite ,,and ,,lias--continued4 ,mineral character of ,lias--,name of ,gryphite limestone--,fossil shells and fish--,ichthyodorulites--,reptiles of the ,lias--,ichthyosaur and ,plesiosaur--,marine ,reptile of the ,galapagos ,islands--,sudden destruction and burial of fossil animals in ,lias--,fluvio-marine beds in ,gloucestershire and insect limestone--,origin of the ,oolite and ,lias1 and of alternating calcareous and argillaceous formations--,oolitic coal-field of ,virginia1 in the ,united ,states #bgc ,,chapter ,,xxii4 ,,trias ,,or ,,new ,,red ,,sandstone ,,group4 ,distinction between ,new and ,old ,red ,sandstone--,between ,upper and ,lower ,new ,red--,the ,trias and its three divisions--,most largely developed in ,germany--,keuper and its fossils--,muschelkalk--,fossil plants of ,bunter--,triassic group in ,england--,bone-bed of ,axmouth and ,aust--,red ,sandstone of ,warwickshire and ,cheshire--,footsteps of ,chirotherium in ,england and ,germany--,osteology of the ,labyrinthodon--,identification of this ,batrachian with the ,chirotherium--,origin of ,red ,sandstone and rock-salt--,hypothesis of saline volcanic exhalations--,theory of the precipitation of salt from inland lakes or lagoons--,saltness of the ,red ,sea--,new ,red ,sandstone in the ,united ,states--,fossil footprints of birds and reptiles in the ,valley of the ,connecticut--,antiquity of the ,red ,sandstone containing them #bhf ,,chapter ,,xxiii4 ,,permian ,,or ,,magnesian ,,limestone ,,group4 ,fossils of ,magnesian ,limestone and ,lower ,new ,red distinct from the ,triassic--,term ,permian--,english and ,german equivalents--,marine shells and corals of ,english ,magnesian limestone--,palaeoniscus and other fish of the marl slate--,thecodont ,saurians of dolomitic conglomerate of ,bristol--,zechstein and ,rothliegendes of ,thuringia--,permian ,flora--,its generic affinity to the carboniferous--,psaronites or tree-ferns #cja ,,chapter ,,xxiv4 ,,the ,,coal ,,or ,,carboniferous ,,group4 ,carboniferous strata in the south-west of ,england--,superposition of ,coal-measures to ,mountain limestone--,departure from this type in north of ,england and ,scotland--,section in ,south ,wales--,underclays with ,stigmaria--,carboniferous ,flora--,ferns1 ,lepidodendra1 ,calamites1 ,asterophyllites1 ,sigillariae1 ,stigmariae1--,coniferae--,endogens--,ab sence of ,exogens--,coal1 how formed--,erect fossil trees--,parkfield ,colliery--,st4 ,etienne1 ,coal-field--,oblique trees or snags--,fossil forests in ,nova ,scotia--,brackish water and marine strata--,origin of ,clay-iron-stone #cjh ,,chapter ,,xxv4 ,,carboniferous ,,group--continued4 ,coal-fields of the ,united ,states--,section of the country between the ,atlantic and ,mississippi--,position of land in the carboniferous period eastward of the ,alleghanies--,mechanically formed rocks thinning out westward1 and limestones thickening--,uniting of many coal-seams into one thick one--,horizontal coal at ,brownsville1 ,pennsylvania--,vast extent and continuity of single seams of coal--,ancient river-channel in ,forest of ,dean coal-field--,absence of earthy matter in coal--,climate of carboniferous period--,insects in coal--,rarity of air-breathing animals--,great number of fossil fish--,first discovery of the skeletons of fossil reptiles--,footprints of reptilians--,mountain limestone--,its corals and marine shells #cbf ,,chapter ,,xxvi4 ,,old ,,red ,,sandstone1 ,,or ,,devonian ,,group4 ,old ,red ,sandstone of ,scotland1 and borders of ,wales--,fossils usually rare--,old ,red in ,forfarshire--,ichthyolites of ,caithness--,distinct lithological type of ,old ,red in ,devon and ,cornwall--,term ,devonian--,organic remains of intermediate character between those of the ,carboniferous and ,silurian systems--,corals and shells--,devonian strata of ,westphalia1 the ,eifel1 ,russia1 and the ,united ,states--,coral reef at ,falls of the ,ohio--,devonian ,flora #cdb ,,chapter ,,xxvii4 ,,silurian ,,group4 ,silurian strata formerly called transition--,term grauwacke--,subdivisions of ,upper and ,lower ,silurian--,ludlow formation and fossils--,wenlock formation1 corals and shells--,caradoc and ,llandeilo beds--,graptolites--,lingula--,trilobite s--,cystideae--,vast thickness of ,silurian strata in ,north ,wales--,unconformability of ,caradoc sandstone--,silurian strata of the ,united ,states--,amount of specific agreement of fossils with those of ,europe--,great number of brachiopods--,deep-sea origin of ,silurian strata--,absence of fluviatile formations--,mineral character of the most ancient fossiliferous rocks #cej ,,chapter ,,xxviii4 ,,volcanic ,,rocks4 ,trap rocks--,name1 whence derived--,their igneous origin at first doubted--,their general appearance and character--,volcanic cones and craters1 how formed--,mineral composition and texture of volcanic rocks--,varieties of felspar--,hornblende and augite--,isomorphism--,rocks1 how to be studied--,basalt1 greenstone1 trachyte1 porphyry1 scoria1 amygdaloid1 lava1 tuff--,alphabetical list1 and explanation of names and synonyms1 of volcanic rocks--,table of the analyses of minerals most abundant in the volcanic and hypogene rocks #cff ,,chapter ,,xxix4 ,,volcanic ,,rocks--continued4 ,trap dike--sometimes project--sometimes leave fissures vacant by decomposition--,branches and veins of trap--,dikes more crystalline in the centre--,foreign fragments of rock imbedded--,strata altered at or near the contact--,obliteration of organic remains--,conversion of chalk into marble--and of coal into coke--,inequality in the modifying influence of dikes--,trap interposed between strata--,columnar and globular structure--,relation of trappean rocks to the products of active volcanos--,submarine lava and ejected matter correspond generally to ancient trap--,structure and physical features of ,palma and some other extinct volcanos #cgh ,,chapter ,,xxx4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,volcanic ,,rocks4 ,tests of relative age of volcanic rocks--,test by superposition and intrusion--,dike of ,quarrington ,hill1 ,durham--,test by alteration of rocks in contact--,test by organic remains--,test of age by mineral character--,test by included fragments--,volcanic rocks of the ,post-,pliocene period--,basalt of ,bay of ,trezza in ,sicily--,post-,pliocene volcanic rocks near ,naples--,dikes of ,somma--,igneous formations of the ,newer ,pliocene period--,val di ,noto in ,sicily #cig ,,chapter ,,xxxi4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,volcanic ,,rocks--continued4 ,volcanic rocks of the ,older ,pliocene period--,tuscany--,rome--,volcanic region of ,olot in ,catalonia--,cones and lava-currents--,ravines and ancient gravel-beds--,jets of air called ,bufadors--,age of the ,catalonian volcanos--,miocene period--,brown-coal of the ,eifel and contemporaneous trachytic breccias--,age of the brown-coal--,peculiar characters of the volcanos of the upper and lower ,eifel--,lake craters--,trass--,hungarian volcanos #djh ,,chapter ,,xxxii4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,volcanic ,,rocks--continued4 ,volcanic rocks of the ,pliocene and ,miocene periods continued--,auvergne--,mont ,dor--,breccias and alluviums of ,mont ,perrier1 with bones of quadrupeds--,river dammed up by lava-current--,range of minor cones from ,auvergne to the ,vivarais--,monts ,dome--,puy de ,come--,puy de ,pariou--,cones not denuded by general flood--,velay--,bones of quadrupeds buried in scoriae--,cantal--,eocene volcanic rocks--,tuffs near ,clermont--,hill of ,gergovia--,trap of ,cretaceous period--,oolitic period--,new ,red ,sandstone period--,carboniferous period--,old ,red ,sandstone period--,rock and ,spindle near ,st4 ,andrews--,silurian period--,cambrian volcanic rocks #dbb ,,chapter ,,xxxiii4 ,,plutonic ,,rocks--,,granite4 ,general aspect of granite--,decomposing into spherical masses--,rude columnar structure--,analogy and difference of volcanic and plutonic formations--,minerals in granite1 and their arrangement--,graphic and porphyritic granite--,mutual penetration of crystals of quartz and felspar--,occasional minerals--,syenite--,syenitic1 talcose1 and schorly granites--,eurite--,passage of granite into trap--,examples near ,christiania and in ,aberdeenshire--,analogy in composition of trachyte and granite--,granite veins in ,glen ,tilt1 ,cornwall1 the ,valorsine1 and other countries--,different composition of veins from main body of granite--,metalliferous veins in strata near their junction with granite--,apparent isolation of nodules of granite--,quartz veins--,whether plutonic rocks are ever overlying--,their exposure at the surface due to denudation #dcf ,,chapter ,,xxxiv4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,plutonic ,,rocks4 ,difficulty in ascertaining the precise age of a plutonic rock--,test of age by relative position--,test by intrusion and alteration--,test by mineral composition--,test by included fragments--,recent and ,pliocene plutonic rocks1 why invisible--,tertiary plutonic rocks in the ,andes--,granite altering ,cretaceous rocks--,granite altering ,lias in the ,alps and in ,skye--,granite of ,dartmoor altering ,carboniferous strata--,granite of the ,old ,red ,sandstone period--,syenite altering ,silurian strata in ,norway--,blending of the same with gneiss--,most ancient plutonic rocks--,granite protruded in a solid form--,on the probable age of the granites of ,arran1 in ,scotland #ddi ,,chapter ,,xxxv4 ,,metamorphic ,,rocks4 ,general character of metamorphic rocks--,gneiss--,hornblende-schist --,mica-schist--,clay-slate--,quartzite- -,chlorite-schist--,metamorphic limestone--,alphabetical list and explanation of other rocks of this family--,origin of the metamorphic strata--,their stratification is real and distinct from cleavage--,joints and slaty cleavage--,supposed causes of these structures--how far connected with crystalline action #dfc ,,chapter ,,xxxvi4 ,,metamorphic ,,rocks--continued4 ,strata near some intrusive masses of granite converted into rocks identical with different members of the metamorphic series--,arguments hence derived as to the nature of plutonic action--,time may enable this action to pervade denser masses--,from what kinds of sedimentary rock each variety of the metamorphic class may be derived--,certain objections to the metamorphic theory considered--,lamination of trachyte and obsidian due to motion--,whether some kinds of gneiss have become schistose by a similar action #dgc ,,chapter ,,xxxvii4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,metamorphic ,,rocks4 ,age of each set of metamorphic strata twofold--,test of age by fossils and mineral character not available--,test by superposition ambiguous--,conversion of dense masses of fossiliferous strata into metamorphic rocks--,limestone and shale of ,carrara--,metamorphic strata of modern periods in the ,alps of ,switzerland and ,savoy--,why the visible crystalline strata are none of them very modern--,order of succession in metamorphic rocks--,uniformity of mineral character--,why the metamorphic strata are less calcareous than the fossiliferous #dha ,,chapter ,,xxxviii4 ,,mineral ,,veins4 ,werner's doctrine that mineral veins were fissures filled from above--,veins of segregation--,ordinary metalliferous veins or lodes--,their frequent coincidence with faults--,proofs that they originated in fissures in solid rock--,veins shifting other veins--,polishing of their walls--,shells and pebbles in lodes--,evidence of the successive enlargement and re-opening of veins--,fournet's observations in ,auvergne--,dimensions of veins--,why some alternately swell out and contract--,filling of lodes by sublimation from below--,chemical and electrical action--,relative age of the precious metals--,copper and lead veins in ,ireland older than ,cornish tin--,lead vein in lias1 ,glamorganshire--,gold in ,russia--,connection of hot springs and mineral veins--,concluding remarks #dhh 99 99 99 99 99 ,dates of the successive ,editions of the ,principles and ,elements 7or ,manual7 of ,geology1 by the ,author4 ,principles1 #ast vol4 in octavo1 published in - - - ,jan4 #ahcj4 ----1 #b;d vol4 do4 - - - - - - - - - - - - - - - - ,jan4 #ahcb4 ----1 #ast vol4 #b;d edition in octavo - - - - - - - #ahcb4 ----1 #b;d vol4 #b;d edition do4 - - - - - - - - - - ,jan4 #ahcc4 ----1 #c;d vol4 #ast edition do4 - - - - - - - - - - ,may #ahcc4 ----1 ,new edition 7called the #c;d7 of the whole work in #d vols4 #abmo4 - - - - - - - - - - - - - - - - - - - ,may #ahcd4 ----1 #dth edition1 #d vols4 #abmo4 - - - - - - - - - ,june #ahce4 ----1 #eth edition1 do4 do4 - - - - - - - - - - - - ,mar4 #ahcg4 ,elements1 #ast edition in one vol4 - - - - - - - - ,july #ahch4 ,principles1 #fth edition1 #c vols4 #abmo4 - - - - - - ,june #ahdj4 ,elements1 #b;d edition in #b vols4 #abmo4 - - - - - - ,july #ahda4 ,principles1 #gth edition in one vol4 #hvo4 - - - - - ,feb4 #ahdg4 ----1 #hth edition1 now published in one vol4 #hvo4 - ,may #ahej4 ,manual of ,elementary ,geology 7or ,elements1 #c;d edition71 now published in one vol4 #hvo4 - - - - - - - - - - - - ,jan4 #ahea4 ,works by ,sir ,charles ,lyell4 ,i4 ,,travels ,,in ,,north ,,america1--#ahda-b4 ,with ,geological ,observations on the ,united ,states1 ,canada1 and ,nova ,scotia4 ,with large coloured geological ,map and ,plates4 #b vols4 post #hvo4 #bas4 ,,ii4 ,a ,,second ,,visit ,,to ,,the ,,united ,,states1--#ahde-f4 ,second ,edition4 #b vols4 post #hvo4 #ahs4 ,,iii4 ,,principles ,,of ,,geology2 or the ,modern ,changes of the ,earth and its ,inhabitants considered1 as illustrative of ,geology4 ,eighth ,edition1 thoroughly revised4 ,with ,maps1 ,plates1 and ,woodcuts4 #hvo4 #ahs4 ,,iv4 ,a ,,manual ,,of ,,elementary ,,geology2 or the ,,ancient ,,changes of the ,earth and its ,inhabitants1 as illustrated by ,geological ,monuments4 ,fourth ,edition4 ,thoroughly revised4 ,with #eca ,woodcuts and ,plates4 #hvo4 #abs4 ,,manual ,,of ,,elementary ,,geology4 ,,chapter ,i4 ,,on ,,the ,,different ,,classes ,,of ,,rocks4 ,geology defined--,successive formation of the earth's crust--,classification of rocks according to their origin and age--,aqueous rocks--,their stratification and imbedded fossils--,volcanic rocks1 with and without cones and craters--,plutonic rocks1 and their relation to the volcanic--,metamorphic rocks and their probable origin--,the term primitive1 why erroneously applied to the crystalline formations--,leading division of the work4 ,of what materials is the earth composed1 and in what manner are these materials arranged8 ,these are the first inquiries with which ,geology is occupied1 a science which derives its name from the ,greek ge1 ge1 the earth1 and logos1 logos1 a discourse4 ,previously to experience we might have imagined that investigations of this kind would relate exclusively to the mineral kingdom1 and to the various rocks1 soils1 and metals1 which occur upon the surface of the earth1 or at various depths beneath it4 ,but1 in pursuing such researches1 we soon find ourselves led on to consider the successive changes which have taken place in the former state of the earth's surface and interior1 and the causes which have given rise to these changes2 and1 what is still more singular and unexpected1 we soon become engaged in researches into the history of the animate creation1 or of the various tribes of animals and plants which have1 at different periods of the past1 inhabited the globe4 ,all are aware that the solid parts of the earth consist of distinct substances1 such as clay1 chalk1 sand1 limestone1 coal1 slate1 granite1 and the like2 but previously to observation it is commonly imagined that all these had remained from the first in the state in which we now see them1--that they were created in their present form1 and in their present position4 ,the geologist soon comes to a different conclusion1 discovering proofs that the external parts of the earth were not all produced in the beginning of things1 in the state in which we now behold them1 nor in an instant of time4 ,on the contrary1 he can show that they have acquired their actual configuration and condition gradually1 under a great variety of circumstances1 and at successive periods1 during each of which distinct races of living beings have flourished on the land and in the waters1 the remains of these creatures still lying buried in the crust of the earth4 ,by the earth's crust1 is meant that small portion of the exterior of our planet which is accessible to human observation1 or on which we are enabled to reason by observations made at or near the surface4 ,these reasonings may extend to a depth of several miles1 perhaps ten miles2 and even then it may be said1 that such a thickness is no more than #a_/djj part of the distance from the surface to the centre4 ,the remark is just2 but although the dimensions of such a crust are1 in truth1 insignificant when compared to the entire globe1 yet they are vast1 and of magnificent extent in relation to man1 and to the organic beings which people our globe4 ,referring to this standard of magnitude1 the geologist may admire the ample limits of his domain1 and admit1 at the same time1 that not only the exterior of the planet1 but the entire earth1 is but an atom in the midst of the countless worlds surveyed by the astronomer4 ,the materials of this crust are not thrown together confusedly2 but distinct mineral masses1 called rocks1 are found to occupy definite spaces1 and to exhibit a certain order of arrangement4 ,the term rock is applied indifferently by geologists to all these substances1 whether they be soft or stony1 for clay and sand are included in the term1 and some have even brought peat under this denomination4 ,our older writers endeavoured to avoid offering such violence to our language1 by speaking of the component materials of the earth as consisting of rocks and soils4 ,but there is often so insensible a passage from a soft and incoherent state to that of stone1 that geologists of all countries have found it indispensable to have one technical term to include both1 and in this sense we find roche applied in ,french1 rocca in ,italian1 and felsart in ,german4 ,the beginner1 however1 must constantly bear in mind1 that the term rock by no means implies that a mineral mass is in an indurated or stony condition4 ,the most natural and convenient mode of classifying the various rocks which compose the earth's crust1 is to refer1 in the first place1 to their origin1 and in the second to their relative age4 ,i shall therefore begin by endeavouring briefly to explain to the student how all rocks may be divided into four great classes by reference to their different origin1 or1 in other words1 by reference to the different circumstances and causes by which they have been produced4 ,the first two divisions1 which will at once be understood as natural1 are the aqueous and volcanic1 or the products of watery and those of igneous action at or near the surface4 ,aqueous rocks4--,the aqueous rocks1 sometimes called the sedimentary1 or fossiliferous1 cover a larger part of the earth's surface than any others4 ,these rocks are stratified1 or divided into distinct layers1 or strata4 ,the term stratum means simply a bed1 or any thing spread out or strewed over a given surface2 and we infer that these strata have been generally spread out by the action of water1 from what we daily see taking place near the mouths of rivers1 or on the land during temporary inundations4 ,for1 whenever a running stream charged with mud or sand1 has its velocity checked1 as when it enters a lake or sea1 or overflows a plain1 the sediment1 previously held in suspension by the motion of the water1 sinks1 by its own gravity1 to the bottom4 ,in this manner layers of mud and sand are thrown down one upon another4 ,if we drain a lake which has been fed by a small stream1 we frequently find at the bottom a series of deposits1 disposed with considerable regularity1 one above the other2 the uppermost1 perhaps1 may be a stratum of peat1 next below a more dense and solid variety of the same material2 still lower a bed of shell-marl1 alternating with peat or sand1 and then other beds of marl1 divided by layers of clay4 ,now1 if a second pit be sunk through the same continuous lacustrine formation1 at some distance from the first1 nearly the same series of beds is commonly met with1 yet with slight variations2 some1 for example1 of the layers of sand1 clay1 or marl1 may be wanting1 one or more of them having thinned out and given place to others1 or sometimes one of the masses first examined is observed to increase in thickness to the exclusion of other beds4 ,the term formation1 which ,i have used in the above explanation1 expresses in geology any assemblage of rocks which have some character in common1 whether of origin1 age1 or composition4 ,thus we speak of stratified and unstratified1 freshwater and marine1 aqueous and volcanic1 ancient and modern1 metalliferous and non-metalliferous formations4 ,in the estuaries of large rivers1 such as the ,ganges and the ,mississippi1 we may observe1 at low water1 phenomena analogous to those of the drained lakes above mentioned1 but on a grander scale1 and extending over areas several hundred miles in length and breadth4 ,when the periodical inundations subside1 the river hollows out a channel to the depth of many yards through horizontal beds of clay and sand1 the ends of which are seen exposed in perpendicular cliffs4 ,these beds vary in colour1 and are occasionally characterized by containing drift-wood or shells4 ,the shells may belong to species peculiar to the river1 but are sometimes those of marine testacea1 washed into the mouth of the estuary during storms4 ,the annual floods of the ,nile in ,egypt are well known1 and the fertile deposits of mud which they leave on the plains4 ,this mud is stratified1 the thin layer thrown down in one season differing slightly in colour from that of a previous year1 and being separable from it1 as has been observed in excavations at ,cairo1 and other places4#c-;,a ,when beds of sand1 clay1 and marl1 containing shells and vegetable matter1 are found arranged in a similar manner in the interior of the earth1 we ascribe to them a similar origin2 and the more we examine their characters in minute detail1 the more exact do we find the resemblance4 ,thus1 for example1 at various heights and depths in the earth1 and often far from seas1 lakes1 and rivers1 we meet with layers of rounded pebbles composed of different rocks mingled together4 ,they are like the shingle of a sea-beach1 or pebbles formed in the beds of torrents and rivers1 which are carried down into the ocean wherever these descend from high grounds bordering a coast4 ,there the gravel is spread out by the waves and currents over a considerable space2 but during seasons of drought the torrents and rivers are nearly dry1 and have only power to convey fine sand or mud into the sea4 ,hence1 alternate layers of gravel and fine sediment accumulate under water1 and such alternations are found by geologists in the interior of every continent4#d-;,a ,if a stratified arrangement1 and the rounded forms of pebbles1 are alone sufficient to lead us to the conclusion that certain rocks originated under water1 this opinion is farther confirmed by the distinct and independent evidence of fossils1 so abundantly included in the earth's crust4 ,by a fossil is meant any body1 or the traces of the existence of any body1 whether animal or vegetable1 which has been buried in the earth by natural causes4 ,now the remains of animals1 especially of aquatic species1 are found almost everywhere imbedded in stratified rocks1 and sometimes1 in the case of limestone1 they are in such abundance as to constitute the entire mass of the rock itself4 ,shells and corals are the most frequent1 and with them are often associated the bones and teeth of fishes1 fragments of wood1 impressions of leaves1 and other organic substances4 ,fossil shells1 of forms such as now abound in the sea1 are met with far inland1 both near the surface1 and at great depths below it4 ,they occur at all heights above the level of the ocean1 having been observed at elevations of #hjjj feet in the ,pyrenees1 #aj1jjj in the ,alps1 #ac1jjj in the ,andes1 and above #af1jjj feet in the ,himalayas4#d-;,b ,these shells belong mostly to marine testacea1 but in some places exclusively to forms characteristic of lakes and rivers4 ,hence it is concluded that some ancient strata were deposited at the bottom of the sea1 and others in lakes and estuaries4 ,when geology was first cultivated1 it was a general belief1 that these marine shells and other fossils were the effects and proofs of the deluge of ,noah2 but all who have carefully investigated the phenomena have long rejected this doctrine4 ,a transient flood might be supposed to leave behind it1 here and there upon the surface1 scattered heaps of mud1 sand1 and shingle1 with shells confusedly intermixed2 but the strata containing fossils are not superficial deposits1 and do not simply cover the earth1 but constitute the entire mass of mountains4 ,nor are the fossils mingled without reference to the original habits and natures of the creatures of which they are the memorials2 those1 for example1 being found associated together which lived in deep or in shallow water1 near the shore or far from it1 in brackish or in salt water4 ,it has1 moreover1 been a favourite notion of some modern writers1 who were aware that fossil bodies could not all be referred to the deluge1 that they1 and the strata in which they are entombed1 might have been deposited in the bed of the ocean during the period which intervened between the creation of man and the deluge4 ,they have imagined that the antediluvian bed of the ocean1 after having been the receptacle of many stratified deposits1 became converted1 at the time of the flood1 into the lands which we inhabit1 and that the ancient continents were at the same time submerged1 and became the bed of the present sea4 ,this hypothesis1 although preferable to the diluvial theory before alluded to1 since it admits that all fossiliferous strata were successively thrown down from water1 is yet wholly inadequate to explain the repeated revolutions which the earth has undergone1 and the signs which the existing continents exhibit1 in most regions1 of having emerged from the ocean at an era far more remote than four thousand years from the present time4 ,ample proofs of these reiterated revolutions will be given in the sequel1 and it will be seen that many distinct sets of sedimentary strata1 each several hundreds or thousands of feet thick1 are piled one upon the other in the earth's crust1 each containing peculiar fossil animals and plants which are distinguishable with few exceptions from species now living4 ,the mass of some of these strata consists almost entirely of corals1 others are made up of shells1 others of plants turned into coal1 while some are without fossils4 ,in one set of strata the species of fossils are marine2 in another1 lying immediately above or below1 they as clearly prove that the deposit was formed in a brackish estuary or lake4 ,when the student has more fully examined into these appearances1 he will become convinced that the time required for the origin of the rocks composing the actual continents must have been far greater than that which is conceded by the theory above alluded to2 and likewise that no one universal and sudden conversion of sea into land will account for geological appearances4 ,we have now pointed out one great class of rocks1 which1 however they may vary in mineral composition1 colour1 grain1 or other characters1 external and internal1 may nevertheless be grouped together as having a common origin4 ,they have all been formed under water1 in the same manner as modern accumulations of sand1 mud1 shingle1 banks of shells1 reefs of coral1 and the like1 and are all characterized by stratification or fossils1 or by both4 ,volcanic rocks4--,the division of rocks which we may next consider are the volcanic1 or those which have been produced at or near the surface whether in ancient or modern times1 not by water1 but by the action of fire or subterranean heat4 ,these rocks are for the most part unstratified1 and are devoid of fossils4 ,they are more partially distributed than aqueous formations1 at least in respect to horizontal extension4 ,among those parts of ,europe where they exhibit characters not to be mistaken1 ,i may mention not only ,sicily and the country round ,naples1 but ,auvergne1 ,velay1 and ,vivarais1 now the departments of ,puy de ,dome1 ,haute ,loire1 and ,ardeche1 towards the centre and south of ,france1 in which are several hundred conical hills having the forms of modern volcanos1 with craters more or less perfect on many of their summits4 ,these cones are composed moreover of lava1 sand1 and ashes1 similar to those of active volcanos4 ,streams of lava may sometimes be traced from the cones into the adjoining valleys1 where they have choked up the ancient channels of rivers with solid rock1 in the same manner as some modern flows of lava in ,iceland have been known to do1 the rivers either flowing beneath or cutting out a narrow passage on one side of the lava4 ,although none of these ,french volcanos have been in activity within the period of history or tradition1 their forms are often very perfect4 ,some1 however1 have been compared to the mere skeletons of volcanos1 the rains and torrents having washed their sides1 and removed all the loose sand and scoriae1 leaving only the harder and more solid materials4 ,by this erosion1 and by earthquakes1 their internal structure has occasionally been laid open to view1 in fissures and ravines2 and we then behold not only many successive beds and masses of porous lava1 sand1 and scoriae1 but also perpendicular walls1 or dikes1 as they are called1 of volcanic rock1 which have burst through the other materials4 ,such dikes are also observed in the structure of ,vesuvius1 ,etna1 and other active volcanos4 ,they have been formed by the pouring of melted matter1 whether from above or below1 into open fissures1 and they commonly traverse deposits of volcanic tuff1 a substance produced by the showering down from the air1 or incumbent waters1 of sand and cinders1 first shot up from the interior of the earth by the explosions of volcanic gases4 ,besides the parts of ,france above alluded to1 there are other countries1 as the north of ,spain1 the south of ,sicily1 the ,tuscan territory of ,italy1 the lower ,rhenish provinces1 and ,hungary1 where spent volcanos may be seen1 still preserving in many cases a conical form1 and having craters and often lava-streams connected with them4 ,there are also other rocks in ,england1 ,scotland1 ,ireland1 and almost every country in ,europe1 which we infer to be of igneous origin1 although they do not form hills with cones and craters4 ,thus1 for example1 we feel assured that the rock of ,staffa1 and that of the ,giant's ,causeway1 called basalt1 is volcanic1 because it agrees in its columnar structure and mineral composition with streams of lava which we know to have flowed from the craters of volcanos4 ,we find also similar basaltic and other igneous rocks associated with beds of tuff in various parts of the ,british ,isles1 and forming dikes1 such as have been spoken of2 and some of the strata through which these dikes cut are occasionally altered at the point of contact1 as if they had been exposed to the intense heat of melted matter4 ,the absence of cones and craters1 and long narrow streams of superficial lava1 in ,england and many other countries1 is principally to be attributed to the eruptions having been submarine1 just as a considerable proportion of volcanos in our own times burst out beneath the sea4 ,but this question must be enlarged upon more fully in the chapters on ,igneous ,rocks1 in which it will also be shown1 that as different sedimentary formations1 containing each their characteristic fossils1 have been deposited at successive periods1 so also volcanic sand and scoriae have been thrown out1 and lavas have flowed over the land or bed of the sea1 at many different epochs1 or have been injected into fissures2 so that the igneous as well as the aqueous rocks may be classed as a chronological series of monuments1 throwing light on a succession of events in the history of the earth4 ,plutonic rocks 7,granite1 c474--,we have now pointed out the existence of two distinct orders of mineral masses1 the aqueous and the volcanic3 but if we examine a large portion of a continent1 especially if it contain within it a lofty mountain range1 we rarely fail to discover two other classes of rocks1 very distinct from either of those above alluded to1 and which we can neither assimilate to deposits such as are now accumulated in lakes or seas1 nor to those generated by ordinary volcanic action4 ,the members of both these divisions of rocks agree in being highly crystalline and destitute of organic remains4 ,the rocks of one division have been called plutonic1 comprehending all the granites and certain porphyries1 which are nearly allied in some of their characters to volcanic formations4 ,the members of the other class are stratified and often slaty1 and have been called by some the crystalline schists1 in which group are included gneiss1 micaceous-schist 7or mica-slate71 hornblende-schist1 statuary marble1 the finer kinds of roofing slate1 and other rocks afterwards to be described4 ,as it is admitted that nothing strictly analogous to these crystalline productions can now be seen in the progress of formation on the earth's surface1 it will naturally be asked1 on what data we can find a place for them in a system of classification founded on the origin of rocks4 ,i cannot1 in reply to this question1 pretend to give the student1 in a few words1 an intelligible account of the long chain of facts and reasonings by which geologists have been led to infer the analogy of the rocks in question to others now in progress at the surface4 ,the result1 however1 may be briefly stated4 ,all the various kinds of granite1 which constitute the plutonic family1 are supposed to be of igneous origin1 but to have been formed under great pressure1 at considerable depths in the earth1 or sometimes1 perhaps1 under a certain weight of incumbent water4 ,like the lava of volcanos1 they have been melted1 and have afterwards cooled and crystallized1 but with extreme slowness1 and under conditions very different from those of bodies cooling in the open air4 ,hence they differ from the volcanic rocks1 not only by their more crystalline texture1 but also by the absence of tuffs and breccias1 which are the products of eruptions at the earth's surface1 or beneath seas of inconsiderable depth4 ,they differ also by the absence of pores or cellular cavities1 to which the expansion of the entangled gases gives rise in ordinary lava4 ,although granite has often pierced through other strata1 it has rarely1 if ever1 been observed to rest upon them1 as if it had overflowed4 ,but as this is continually the case with the volcanic rocks1 they have been styled1 from this peculiarity1 overlying by ,dr4 ,mac,culloch2 and ,mr4 ,necker has proposed the term underlying for the granites1 to designate the opposite mode in which they almost invariably present themselves4 ,metamorphic1 or stratified crystalline rocks4--,the fourth and last great division of rocks are the crystalline strata and slates1 or schists1 called gneiss1 mica-schist1 clay-slate1 chlorite-schist1 marble1 and the like1 the origin of which is more doubtful than that of the other three classes4 ,they contain no pebbles1 or sand1 or scoriae1 or angular pieces of imbedded stone1 and no traces of organic bodies1 and they are often as crystalline as granite1 yet are divided into beds1 corresponding in form and arrangement to those of sedimentary formations1 and are therefore said to be stratified4 ,the beds sometimes consist of an alternation of substances varying in colour1 composition1 and thickness1 precisely as we see in stratified fossiliferous deposits4 ,according to the ,huttonian theory1 which ,i adopt as most probable1 and which will be afterwards more fully explained1 the materials of these strata were originally deposited from water in the usual form of sediment1 but they were subsequently so altered by subterranean heat1 as to assume a new texture4 ,it is demonstrable1 in some cases at least1 that such a complete conversion has actually taken place1 fossiliferous strata having exchanged an earthy for a highly crystalline texture for a distance of a quarter of a mile from their contact with granite4 ,in some cases1 dark limestones1 replete with shells and corals1 have been turned into white statuary marble1 and hard clays into slates called mica-schist and hornblende-schist1 all signs of organic bodies having been obliterated4 ,although we are in a great degree ignorant of the precise nature of the influence exerted in these cases1 yet it evidently bears some analogy to that which volcanic heat and gases are known to produce2 and the action may be conveniently called plutonic1 because it appears to have been developed in those regions where plutonic rocks are generated1 and under similar circumstances of pressure and depth in the earth4 ,whether hot water or steam permeating stratified masses1 or electricity1 or any other causes have co-operated to produce the crystalline texture1 may be matter of speculation1 but it is clear that the plutonic influence has sometimes pervaded entire mountain masses of strata4 ,in accordance with the hypothesis above alluded to1 ,i proposed in the first edition of the ,principles of ,geology 7#ahcc71 the term ,metamorphic for the altered strata1 a term derived from meta1 meta1 trans1 and morphe1 morphe1 forma4 ,hence there are four great classes of rocks considered in reference to their origin1--the aqueous1 the volcanic1 the plutonic1 and the metamorphic4 ,in the course of this work it will be shown1 that portions of each of these four distinct classes have originated at many successive periods4 ,they have all been produced contemporaneously1 and may even now be in the progress of formation4 ,it is not true1 as was formerly supposed1 that all granites1 together with the crystalline or metamorphic strata1 were first formed1 and therefore entitled to be called primitive1 and that the aqueous and volcanic rocks were afterwards superimposed1 and should1 therefore1 rank as secondary in the order of time4 ,this idea was adopted in the infancy of the science1 when all formations1 whether stratified or unstratified1 earthy or crystalline1 with or without fossils1 were alike regarded as of aqueous origin4 ,at that period it was naturally argued1 that the foundation must be older than the superstructure2 but it was afterwards discovered1 that this opinion was by no means in every instance a legitimate deduction from facts2 for the inferior parts of the earth's crust have often been modified1 and even entirely changed1 by the influence of volcanic and other subterranean causes1 while superimposed formations have not been in the slightest degree altered4 ,in other words1 the destroying and renovating processes have given birth to new rocks below1 while those above1 whether crystalline or fossiliferous1 have remained in their ancient condition4 ,even in cities1 such as ,venice and ,amsterdam1 it cannot be laid down as universally true1 that the upper parts of each edifice1 whether of brick or marble1 are more modern than the foundations on which they rest1 for these often consist of wooden piles1 which may have rotted and been replaced one after the other1 without the least injury to the buildings above2 meanwhile1 these may have required scarcely any repair1 and may have been constantly inhabited4 ,so it is with the habitable surface of our globe1 in its relation to large masses of rock immediately below3 it may continue the same for ages1 while subjacent materials1 at a great depth1 are passing from a solid to a fluid state1 and then reconsolidating1 so as to acquire a new texture4 ,as all the crystalline rocks may1 in some respects1 be viewed as belonging to one great family1 whether they be stratified or unstratified1 plutonic or metamorphic1 it will often be convenient to speak of them by one common name4 ,it being now ascertained1 as above stated1 that they are of very different ages1 sometimes newer than the strata called secondary1 the term primary1 which was formerly used for the whole1 must be abandoned1 as it would imply a manifest contradiction4 ,it is indispensable1 therefore1 to find a new name1 one which must not be of chronological import1 and must express1 on the one hand1 some peculiarity equally attributable to granite and gneiss 7to the plutonic as well as the altered rocks71 and1 on the other1 must have reference to characters in which those rocks differ1 both from the volcanic and from the unaltered sedimentary strata4 ,i proposed in the ,principles of ,geology 7first edition1 vol4 iii471 the term hypogene for this purpose1 derived from hypo1 under1 and ginomai1 to be1 or to be born2 a word implying the theory that granite1 gneiss1 and the other crystalline formations are alike nether-formed rocks1 or rocks which have not assumed their present form and structure at the surface4 ,this occurs in the lowest place in the order of superposition4 ,even in regions such as the ,alps1 where some masses of granite and gneiss can be shown to be of comparatively modern date1 belonging1 for example1 to the period hereafter to be described as tertiary1 they are still underlying rocks4 ,they never repose on the volcanic or trappean formations1 nor on strata containing organic remains4 ,they are hypogene1 as being under all the rest4 ,from what has now been said1 the reader will understand that each of the four great classes of rocks may be studied under two distinct points of view2 first1 they may be studied simply as mineral masses deriving their origin from particular causes1 and having a certain composition1 form1 and position in the earth's crust1 or other characters both positive and negative1 such as the presence or absence of organic remains4 ,in the second place1 the rocks of each class may be viewed as a grand chronological series of monuments1 attesting a succession of events in the former history of the globe and its living inhabitants4 ,i shall accordingly proceed to treat of each family of rocks2 first1 in reference to those characters which are not chronological1 and then in particular relation to the several periods when they were formed4 ,,footnotes3 #c-;,a ,see ,principles of ,geology1 by the ,author1 ,index1 ,nile1 ,rivers1 c4 #d-;,a ,see p4 #ah4 #d-;,b ,see ,geograph4 ,journ4 vol4 iv4 p4 #fd4 ,,chapter ,,ii4 ,,aqueous ,,rocks--,,their ,,composition ,,and ,,forms ,,of ,,stratification4 ,mineral composition of strata--,arenaceous rocks--,argillaceous--,calcareous--,gyps um--,forms of stratification--,original horizontality--,thinning out--,diagonal arrangement--,ripple mark4 ,in pursuance of the arrangement explained in the last chapter1 we shall begin by examining the aqueous or sedimentary rocks1 which are for the most part distinctly stratified1 and contain fossils4 ,we may first study them with reference to their mineral composition1 external appearance1 position1 mode of origin1 organic contents1 and other characters which belong to them as aqueous formations1 independently of their age1 and we may afterwards consider them chronologically or with reference to the successive geological periods when they originated4 ,i have already given an outline of the data which led to the belief that the stratified and fossiliferous rocks were originally deposited under water2 but1 before entering into a more detailed investigation1 it will be desirable to say something of the ordinary materials of which such strata are composed4 ,these may be said to belong principally to three divisions1 the arenaceous1 the argillaceous1 and the calcareous1 which are formed respectively of sand1 clay1 and carbonate of lime4 ,of these1 the arenaceous1 or sandy masses1 are chiefly made up of siliceous or flinty grains2 the argillaceous1 or clayey1 of a mixture of siliceous matter1 with a certain proportion1 about a fourth in weight1 of aluminous earth2 and1 lastly1 the calcareous rocks or limestones consist of carbonic acid and lime4 ,arenaceous or siliceous rocks4--,to speak first of the sandy division3 beds of loose sand are frequently met with1 of which the grains consist entirely of silex1 which term comprehends all purely siliceous minerals1 as quartz and common flint4 ,quartz is silex in its purest form2 flint usually contains some admixture of alumine and oxide of iron4 ,the siliceous grains in sand are usually rounded1 as if by the action of running water4 ,sandstone is an aggregate of such grains1 which often cohere together without any visible cement1 but more commonly are bound together by a slight quantity of siliceous or calcareous matter1 or by iron or clay4 ,pure siliceous rocks may be known by not effervescing when a drop of nitric1 sulphuric1 or other acid is applied to them1 or by the grains not being readily scratched or broken by ordinary pressure4 ,in nature there is every intermediate gradation1 from perfectly loose sand1 to the hardest sandstone4 ,in micaceous sandstones mica is very abundant2 and the thin silvery plates into which that mineral divides1 are often arranged in layers parallel to the planes of stratification1 giving a slaty or laminated texture to the rock4 ,when sandstone is coarse-grained1 it is usually called grit4 ,if the grains are rounded1 and large enough to be called pebbles1 it becomes a conglomerate1 or pudding-stone1 which may consist of pieces of one or of many different kinds of rock4 ,a conglomerate1 therefore1 is simply gravel bound together by a cement4 ,argillaceous rocks4--,clay1 strictly speaking1 is a mixture of silex or flint with a large proportion1 usually about one fourth1 of alumine1 or argil2 but1 in common language1 any earth which possesses sufficient ductility1 when kneaded up with water1 to be fashioned like paste by the hand1 or by the potter's lathe1 is called a clay2 and such clays vary greatly in their composition1 and are1 in general1 nothing more than mud derived from the decomposition or wearing down of various rocks4 ,the purest clay found in nature is porcelain clay1 or kaolin1 which results from the decomposition of a rock composed of felspar and quartz1 and it is almost always mixed with quartz4#aa-;,a ,shale has also the property1 like clay1 of becoming plastic in water3 it is a more solid form of clay1 or argillaceous matter1 condensed by pressure4 ,it usually divides into irregular laminae4 ,one general character of all argillaceous rocks is to give out a peculiar1 earthy odour when breathed upon1 which is a test of the presence of alumine1 although it does not belong to pure alumine1 but1 apparently1 to the combination of that substance with oxide of iron4#aa-;,b ,calcareous rocks4--,this division comprehends those rocks which1 like chalk1 are composed chiefly of lime and carbonic acid4 ,shells and corals are also formed of the same elements1 with the addition of animal matter4 ,to obtain pure lime it is necessary to calcine these calcareous substances1 that is to say1 to expose them to heat of sufficient intensity to drive off the carbonic acid1 and other volatile matter1 without vitrifying or melting the lime itself4 ,white chalk is often pure carbonate of lime2 and this rock1 although usually in a soft and earthy state1 is sometimes sufficiently solid to be used for building1 and even passes into a compact stone1 or a stone of which the separate parts are so minute as not to be distinguishable from each other by the naked eye4 ,many limestones are made up entirely of minute fragments of shells and coral1 or of calcareous sand cemented together4 ,these last might be called calcareous sandstones2 but that term is more properly applied to a rock in which the grains are partly calcareous and partly siliceous1 or to quartzose sandstones1 having a cement of carbonate of lime4 ,the variety of limestone called oolite is composed of numerous small egg-like grains1 resembling the roe of a fish1 each of which has usually a small fragment of sand as a nucleus1 around which concentric layers of calcareous matter have accumulated4 ,any limestone which is sufficiently hard to take a fine polish is called marble4 ,many of these are fossiliferous2 but statuary marble1 which is also called saccharine limestone1 as having a texture resembling that of loaf-sugar1 is devoid of fossils1 and is in many cases a member of the metamorphic series4 ,siliceous limestone is an intimate mixture of carbonate of lime and flint1 and is harder in proportion as the flinty matter predominates4 ,the presence of carbonate of lime in a rock may be ascertained by applying to the surface a small drop of diluted sulphuric1 nitric1 or muriatic acids1 or strong vinegar2 for the lime1 having a greater chemical affinity for any one of these acids than for the carbonic1 unites immediately with them to form new compounds1 thereby becoming a sulphate1 nitrate1 or muriate of lime4 ,the carbonic acid1 when thus liberated from its union with the lime1 escapes in a gaseous form1 and froths up or effervesces as it makes its way in small bubbles through the drop of liquid4 ,this effervescence is brisk or feeble in proportion as the limestone is pure or impure1 or1 in other words1 according to the quantity of foreign matter mixed with the carbonate of lime4 ,without the aid of this test1 the most experienced eye cannot always detect the presence of carbonate of lime in rocks4 ,the above-mentioned three classes of rocks1 the siliceous1 argillaceous1 and calcareous1 pass continually into each other1 and rarely occur in a perfectly separate and pure form4 ,thus it is an exception to the general rule to meet with a limestone as pure as ordinary white chalk1 or with clay as aluminous as that used in ,cornwall for porcelain1 or with sand so entirely composed of siliceous grains as the white sand of ,alum ,bay in the ,isle of ,wight1 or sandstone so pure as the grit of ,fontainebleau1 used for pavement in ,france4 ,more commonly we find sand and clay1 or clay and marl1 intermixed in the same mass4 ,when the sand and clay are each in considerable quantity1 the mixture is called loam4 ,if there is much calcareous matter in clay it is called marl2 but this term has unfortunately been used so vaguely1 as often to be very ambiguous4 ,it has been applied to substances in which there is no lime2 as1 to that red loam usually called red marl in certain parts of ,england4 ,agriculturists were in the habit of calling any soil a marl1 which1 like true marl1 fell to pieces readily on exposure to the air4 ,hence arose the confusion of using this name for soils which1 consisting of loam1 were easily worked by the plough1 though devoid of lime4 ,marl slate bears the same relation to marl which shale bears to clay1 being a calcareous shale4 ,it is very abundant in some countries1 as in the ,swiss ,alps4 ,argillaceous or marly limestone is also of common occurrence4 ,there are few other kinds of rock which enter so largely into the composition of sedimentary strata as to make it necessary to dwell here on their characters4 ,i may1 however1 mention two others1--magnesian limestone or dolomite1 and gypsum4 ,magnesian limestone is composed of carbonate of lime and carbonate of magnesia2 the proportion of the latter amounting in some cases to nearly one half4 ,it effervesces much more slowly and feebly with acids than common limestone4 ,in ,england this rock is generally of a yellowish colour2 but it varies greatly in mineralogical character1 passing from an earthy state to a white compact stone of great hardness4 ,dolomite1 so common in many parts of ,germany and ,france1 is also a variety of magnesian limestone1 usually of a granular texture4 ,gypsum4--,gypsum is a rock composed of sulphuric acid1 lime1 and water4 ,it is usually a soft whitish-yellow rock1 with a texture resembling that of loaf-sugar1 but sometimes it is entirely composed of lenticular crystals4 ,it is insoluble in acids1 and does not effervesce like chalk and dolomite1 because it does not contain carbonic acid gas1 or fixed air1 the lime being already combined with sulphuric acid1 for which it has a stronger affinity than for any other4 ,anhydrous gypsum is a rare variety1 into which water does not enter as a component part4 ,gypseous marl is a mixture of gypsum and marl4 ,alabaster is a granular and compact variety of gypsum found in masses large enough to be used in sculpture and architecture4 ,it is sometimes a pure snow-white substance1 as that of ,volterra in ,tuscany1 well known as being carved for works of art in ,florence and ,leghorn4 ,it is a softer stone than marble1 and more easily wrought4 ,forms of stratification4--,a series of strata sometimes consists of one of the above rocks1 sometimes of two or more in alternating beds4 ,thus1 in the coal districts of ,england1 for example1 we often pass through several beds of sandstone1 some of finer1 others of coarser grain1 some white1 others of a dark colour1 and below these1 layers of shale and sandstone or beds of shale1 divisible into leaf-like laminae1 and containing beautiful impressions of plants4 ,then again we meet with beds of pure and impure coal1 alternating with shales and sandstones1 and underneath the whole1 perhaps1 are calcareous strata1 or beds of limestone1 filled with corals and marine shells1 each bed distinguishable from another by certain fossils1 or by the abundance of particular species of shells or zoophytes4 ,this alternation of different kinds of rock produces the most distinct stratification2 and we often find beds of limestone and marl1 conglomerate and sandstone1 sand and clay1 recurring again and again1 in nearly regular order1 throughout a series of many hundred strata4 ,the causes which may produce these phenomena are various1 and have been fully discussed in my treatise on the modern changes of the earth's surface4#ad-;,a ,it is there seen that rivers flowing into lakes and seas are charged with sediment1 varying in quantity1 composition1 colour1 and grain according to the seasons2 the waters are sometimes flooded and rapid1 at other periods low and feeble2 different tributaries1 also1 draining peculiar countries and soils1 and therefore charged with peculiar sediment1 are swollen at distinct periods4 ,it was also shown that the waves of the sea and currents undermine the cliffs during wintry storms1 and sweep away the materials into the deep1 after which a season of tranquillity succeeds1 when nothing but the finest mud is spread by the movements of the ocean over the same submarine area4 ,it is not the object of the present work to give a description of these operations1 repeated as they are1 year after year1 and century after century2 but ,i may suggest an explanation of the manner in which some micaceous sandstones have originated1 those in which we see innumerable thin layers of mica dividing layers of fine quartzose sand4 ,i observed the same arrangement of materials in recent mud deposited in the estuary of ,la ,roche ,st4 ,bernard in ,brittany1 at the mouth of the ,loire4 ,the surrounding rocks are of gneiss1 which1 by its waste1 supplies the mud3 when this dries at low water1 it is found to consist of brown laminated clay1 divided by thin seams of mica4 ,the separation of the mica in this case1 or in that of micaceous sandstones1 may be thus understood4 ,if we take a handful of quartzose sand1 mixed with mica1 and throw it into a clear running stream1 we see the materials immediately sorted by the water1 the grains of quartz falling almost directly to the bottom1 while the plates of mica take a much longer time to reach the bottom1 and are carried farther down the stream4 ,at the first instant the water is turbid1 but immediately after the flat surfaces of the plates of mica are seen alone reflecting a silvery light1 as they descend slowly1 to form a distinct micaceous lamina4 ,the mica is the heavier mineral of the two2 but it remains longer suspended1 owing to its great extent of surface4 ,it is easy1 therefore1 to perceive that where such mud is acted upon by a river or tidal current1 the thin plates of mica will be carried farther1 and not deposited in the same places as the grains of quartz2 and since the force and velocity of the stream varies from time to time1 layers of mica or of sand will be thrown down successively on the same area4 ,original horizontality4--,it has generally been said that the upper and under surfaces of strata1 or the planes of stratification1 as they are termed1 are parallel4 ,although this is not strictly true1 they make an approach to parallelism1 for the same reason that sediment is usually deposited at first in nearly horizontal layers4 ,the reason of this arrangement can by no means be attributed to an original evenness or horizontality in the bed of the sea2 for it is ascertained that in those places where no matter has been recently deposited1 the bottom of the ocean is often as uneven as that of the dry land1 having in like manner its hills1 valleys1 and ravines4 ,yet if the sea should sink1 or the water be removed near the mouth of a large river where a delta has been forming1 we should see extensive plains of mud and sand laid dry1 which1 to the eye1 would appear perfectly level1 although1 in reality1 they would slope gently from the land towards the sea4 ,this tendency in newly-formed strata to assume a horizontal position arises principally from the motion of the water1 which forces along particles of sand or mud at the bottom1 and causes them to settle in hollows or depressions1 where they are less exposed to the force of a current than when they are resting on elevated points4 ,the velocity of the current and the motion of the superficial waves diminish from the surface downwards1 and are least in those depressions where the water is deepest4 ,illustration3 ,fig4 #a4 ,cross section4 ,a good illustration of the principle here alluded to may be sometimes seen in the neighbourhood of a volcano1 when a section1 whether natural or artificial1 has laid open to view a succession of various-coloured layers of sand and ashes1 which have fallen in showers upon uneven ground4 ,thus let ,a ,b 7fig4 #a47 be two ridges1 with an intervening valley4 ,these original inequalities of the surface have been gradually effaced by beds of sand and ashes c1 d1 e1 the surface at e being quite level4 ,it will be seen that although the materials of the first layers have accommodated themselves in a great degree to the shape of the ground ,a ,b1 yet each bed is thickest at the bottom4 ,at first a great many particles would be carried by their own gravity down the steep sides of ,a and ,b1 and others would afterwards be blown by the wind as they fell off the ridges1 and would settle in the hollow1 which would thus become more and more effaced as the strata accumulated from c to e4 ,this levelling operation may perhaps be rendered more clear to the student by supposing a number of parallel trenches to be dug in a plain of moving sand1 like the ,african desert1 in which case the wind would soon cause all signs of these trenches to disappear1 and the surface would be as uniform as before4 ,now1 water in motion can exert this levelling power on similar materials more easily than air1 for almost all stones lose in water more than a third of the weight which they have in air1 the specific gravity of rocks being in general as #b-a_/b when compared to that of water1 which is estimated at #a4 ,but the buoyancy of sand or mud would be still greater in the sea1 as the density of salt water exceeds that of fresh4 ,yet1 however uniform and horizontal may be the surface of new deposits in general1 there are still many disturbing causes1 such as eddies in the water1 and currents moving first in one and then in another direction1 which frequently cause irregularities4 ,we may sometimes follow a bed of limestone1 shale1 or sandstone1 for a distance of many hundred yards continuously2 but we generally find at length that each individual stratum thins out1 and allows the beds which were previously above and below it to meet4 ,if the materials are coarse1 as in grits and conglomerates1 the same beds can rarely be traced many yards without varying in size1 and often coming to an end abruptly4 7,see fig4 #b47 ,illustration3 ,fig4 #b4 ,section of strata of sandstone1 grit1 and conglomerate4 ,illustration3 ,fig4 #c4 ,section of sand at ,sandy ,hill1 near ,biggleswade1 ,bedfordshire4 ,height #bj feet4 7,greensand formation47 ,diagonal or ,cross ,stratification4--,there is also another phenomenon of frequent occurrence4 ,we find a series of larger strata1 each of which is composed of a number of minor layers placed obliquely to the general planes of stratification4 ,to this diagonal arrangement the name of false or cross stratification has been given4 ,thus in the annexed section 7fig4 #c47 we see seven or eight large beds of loose sand1 yellow and brown1 and the lines a1 b1 c1 mark some of the principal planes of stratification1 which are nearly horizontal4 ,but the greater part of the subordinate laminae do not conform to these planes1 but have often a steep slope1 the inclination being sometimes towards opposite points of the compass4 ,when the sand is loose and incoherent1 as in the case here represented1 the deviation from parallelism of the slanting laminae cannot possibly be accounted for by any re-arrangement of the particles acquired during the consolidation of the rock4 ,in what manner then can such irregularities be due to original deposition8 ,we must suppose that at the bottom of the sea1 as well as in the beds of rivers1 the motions of waves1 currents1 and eddies often cause mud1 sand1 and gravel to be thrown down in heaps on particular spots1 instead of being spread out uniformly over a wide area4 ,sometimes1 when banks are thus formed1 currents may cut passages through them1 just as a river forms its bed4 ,suppose the bank ,a 7fig4 #d47 to be thus formed with a steep sloping side1 and the water being in a tranquil state1 the layer of sediment ,no4 #a4 is thrown down upon it1 conforming nearly to its surface4 ,afterwards the other layers1 #b1 #c1 #d1 may be deposited in succession1 so that the bank ,b ,c ,d is formed4 ,if the current then increases in velocity1 it may cut away the upper portion of this mass down to the dotted line e 7fig4 #d471 and deposit the materials thus removed farther on1 so as to form the layers #e1 #f1 #g1 #h4 ,we have now the bank ,b ,c ,d ,e 7fig4 #e471 of which the surface is almost level1 and on which the nearly horizontal layers1 #i1 #aj1 #aa1 may then accumulate4 ,it was shown in fig4 #c4 that the diagonal layers of successive strata may sometimes have an opposite slope4 ,this is well seen in some cliffs of loose sand on the ,suffolk coast4 ,a portion of one of these is represented in fig4 #f41 where the layers1 of which there are about six in the thickness of an inch1 are composed of quartzose grains4 ,this arrangement may have been due to the altered direction of the tides and currents in the same place4 ,illustration3 ,fig4 #d4 ,cross section4 ,illustration3 ,fig4 #e4 ,cross section4 ,illustration3 ,fig4 #f4 ,cliff between ,mismer and ,dunwich4 ,illustration3 ,fig4 #g4 ,section from ,monte ,calvo to the sea by the valley of ,magnan1 near ,nice4 ,a4 ,dolomite and sandstone4 7,greensand formation87 a1 b1 d4 ,beds of gravel and sand4 c4 ,fine marl and sand of ,st4 ,madeleine1 with marine shells4 ,the description above given of the slanting position of the minor layers constituting a single stratum is in certain cases applicable on a much grander scale to masses several hundred feet thick1 and many miles in extent4 ,a fine example may be seen at the base of the ,maritime ,alps near ,nice4 ,the mountains here terminate abruptly in the sea1 so that a depth of many hundred fathoms is often found within a stone's throw of the beach1 and sometimes a depth of #cjjj feet within half a mile4 ,but at certain points1 strata of sand1 marl1 or conglomerate1 intervene between the shore and the mountains1 as in the annexed fig4 #g41 where a vast succession of slanting beds of gravel and sand may be traced from the sea to ,monte ,calvo1 a distance of no less than #i miles in a straight line4 ,the dip of these beds is remarkably uniform1 being always southward or towards the ,mediterranean1 at an angle of about #be deg44 ,they are exposed to view in nearly vertical precipices1 varying from #bjj to #fjj feet in height1 which bound the valley through which the river ,magnan flows4 ,although in a general view1 the strata appear to be parallel and uniform1 they are nevertheless found1 when examined closely1 to be wedge-shaped1 and to thin out when followed for a few hundred feet or yards1 so that we may suppose them to have been thrown down originally upon the side of a steep bank1 where a river or alpine torrent discharged itself into a deep and tranquil sea1 and formed a delta1 which advanced gradually from the base of ,monte ,calvo to a distance of #i miles from the original shore4 ,if subsequently this part of the ,alps and bed of the sea were raised #gjj feet1 the coast would acquire its present configuration1 the delta would emerge1 and a deep channel might then be cut through it by a river4 ,it is well known that the torrents and streams1 which now descend from the alpine declivities to the shore1 bring down annually1 when the snow melts1 vast quantities of shingle and sand1 and then1 as they subside1 fine mud1 while in summer they are nearly or entirely dry2 so that it may be safely assumed1 that deposits like those of the valley of the ,magnan1 consisting of coarse gravel alternating with fine sediment1 are still in progress at many points1 as1 for instance1 at the mouth of the ,var4 ,they must advance upon the ,mediterranean in the form of great shoals terminating in a steep talus2 such being the original mode of accumulation of all coarse materials conveyed into deep water1 especially where they are composed in great part of pebbles1 which cannot be transported to indefinite distances by currents of moderate velocity4 ,by inattention to facts and inferences of this kind1 a very exaggerated estimate has sometimes been made of the supposed depth of the ancient ocean4 ,there can be no doubt1 for example1 that the strata a1 fig4 #g41 or those nearest to ,monte ,calvo1 are older than those indicated by b1 and these again were formed before c2 but the vertical depth of gravel and sand in any one place cannot be proved to amount even to #ajjj feet1 although it may perhaps be much greater1 yet probably never exceeding at any point #cjjj or #djjj feet4 ,but were we to assume that all the strata were once horizontal1 and that their present dip or inclination was due to subsequent movements1 we should then be forced to conclude1 that a sea #i miles deep had been filled up with alternate layers of mud and pebbles thrown down one upon another4 ,in the locality now under consideration1 situated a few miles to the west of ,nice1 there are many geological data1 the details of which cannot be given in this place1 all leading to the opinion1 that when the deposit of the ,magnan was formed1 the shape and outline of the alpine declivities and the shore greatly resembled what we now behold at many points in the neighbourhood4 ,that the beds1 a1 b1 c1 d1 are of comparatively modern date is proved by this fact1 that in seams of loamy marl intervening between the pebbly beds are fossil shells1 half of which belong to species now living in the ,mediterranean4 ,illustration3 ,fig4 #h4 ,slab of ripple-marked 7new red7 sandstone from ,cheshire4 ,ripple mark4--,the ripple mark1 so common on the surface of sandstones of all ages 7see fig4 #h471 and which is so often seen on the sea-shore at low tide1 seems to originate in the drifting of materials along the bottom of the water1 in a manner very similar to that which may explain the inclined layers above described4 ,this ripple is not entirely confined to the beach between high and low water mark1 but is also produced on sands which are constantly covered by water4 ,similar undulating ridges and furrows may also be sometimes seen on the surface of drift snow and blown sand4 ,the following is the manner in which ,i once observed the motion of the air to produce this effect on a large extent of level beach1 exposed at low tide near ,calais4 ,clouds of fine white sand were blown from the neighbouring dunes1 so as to cover the shore1 and whiten a dark level surface of sandy mud1 and this fresh covering of sand was beautifully rippled4 ,on levelling all the small ridges and furrows of this ripple over an area of several yards square1 ,i saw them perfectly restored in about ten minutes1 the general direction of the ridges being always at right angles to that of the wind4 ,the restoration began by the appearance here and there of small detached heaps of sand1 which soon lengthened and joined together1 so as to form long sinuous ridges with intervening furrows4 ,each ridge had one side slightly inclined1 and the other steep2 the lee-side being always steep1 as b1 c1--d1 e2 the windward-side a gentle slope1 as a1 b1--c1 d1 fig4 #i4 ,when a gust of wind blew with sufficient force to drive along a cloud of sand1 all the ridges were seen to be in motion at once1 each encroaching on the furrow before it1 and1 in the course of a few minutes1 filling the place which the furrows had occupied4 ,the mode of advance was by the continual drifting of grains of sand up the slopes a b and c d1 many of which grains1 when they arrived at b and d1 fell over the scarps b c and d e1 and were under shelter from the wind2 so that they remained stationary1 resting1 according to their shape and momentum1 on different parts of the descent1 and a few only rolling to the bottom4 ,in this manner each ridge was distinctly seen to move slowly on as often as the force of the wind augmented4 ,occasionally part of a ridge1 advancing more rapidly than the rest1 overtook the ridge immediately before it1 and became confounded with it1 thus causing those bifurcations and branches which are so common1 and two of which are seen in the slab1 fig4 #h4 ,we may observe this configuration in sandstones of all ages1 and in them also1 as now on the sea-coast1 we may often detect two systems of ripples interfering with each other2 one more ancient and half effaced1 and a newer one1 in which the grooves and ridges are more distinct1 and in a different direction4 ,this crossing of two sets of ripples arises from a change of wind1 and the new direction in which the waves are thrown on the shore4 ,illustration3 ,fig4 #i4 ,sketch of ripples4 ,the ripple mark is usually an indication of a sea-beach1 or of water from #f to #aj feet deep1 for the agitation caused by waves even during storms extends to a very slight depth4 ,to this rule1 however1 there are some exceptions1 and recent ripple marks have been observed at the depth of #fj or #gj feet4 ,it has also been ascertained that currents or large bodies of water in motion may disturb mud and sand at the depth of #cjj or even #dej feet4#ba-;,a ,,footnotes3 #aa-;,a ,the kaolin of ,china consists of #ga4ae parts of silex1 #ae4hf of alumine1 #a4ib of lime1 and #f4gc of water 7,w4 ,phillips1 ,mineralogy1 p4 #cc472 but other porcelain clays differ materially1 that of ,cornwall being composed1 according to ,boase of nearly equal parts of silica and alumine1 with #a per cent4 of magnesia4 7,phil4 ,mag4 vol4 x4 #ahcg47 #aa-;,b ,see ,w4 ,phillips's ,mineralogy1 ,alumine4 #ad-;,a ,consult ,index to ,principles of ,geology1 ,stratification1 ,currents1 ,deltas1 ,water1 c4 #ba-;,a ,siau4 ,edin4 ,new ,phil4 ,journ4 vol4 xxxi42 and ,darwin1 ,volc4 ,islands1 p4 #acd4 ,,chapter ,,iii4 ,,arrangement ,,of ,,fossils ,,in ,,strata--,,freshwater ,,and ,,marine4 ,successive deposition indicated by fossils--,limestones formed of corals and shells ,proofs of gradual increase of strata derived from fossils--,serpula attached to spatangus--,wood bored by ,teredina--,tripoli and semi-opal formed of infusoria--,chalk derived principally from organic bodies--,distinction of freshwater from marine formations--,genera of freshwater and land shells--,rules for recognizing marine testacea--,gyrogonite and chara--,freshwater fishes--,alternation of marine and freshwater deposits--,lym-,fiord4 ,having in the last chapter considered the forms of stratification so far as they are determined by the arrangement of inorganic matter1 we may now turn our attention to the manner in which organic remains are distributed through stratified deposits4 ,we should often be unable to detect any signs of stratification or of successive deposition1 if particular kinds of fossils did not occur here and there at certain depths in the mass4 ,at one level1 for example1 univalve shells of some one or more species predominate2 at another1 bivalve shells2 and at a third1 corals2 while in some formations we find layers of vegetable matter1 commonly derived from land plants1 separating strata4 ,it may appear inconceivable to a beginner how mountains1 several thousand feet thick1 can have become filled with fossils from top to bottom2 but the difficulty is removed1 when he reflects on the origin of stratification1 as explained in the last chapter1 and allows sufficient time for the accumulation of sediment4 ,he must never lose sight of the fact that1 during the process of deposition1 each separate layer was once the uppermost1 and covered immediately by the water in which aquatic animals lived4 ,each stratum in fact1 however far it may now lie beneath the surface1 was once in the state of shingle1 or loose sand or soft mud at the bottom of the sea1 in which shells and other bodies easily became enveloped4 ,by attending to the nature of these remains1 we are often enabled to determine whether the deposition was slow or rapid1 whether it took place in a deep or shallow sea1 near the shore or far from land1 and whether the water was salt1 brackish1 or fresh4 ,some limestones consist almost exclusively of corals1 and in many cases it is evident that the present position of each fossil zoophyte has been determined by the manner in which it grew originally4 ,the axis of the coral1 for example1 if its natural growth is erect1 still remains at right angles to the plane of stratification4 ,if the stratum be now horizontal1 the round spherical heads of certain species continue uppermost1 and their points of attachment are directed downwards4 ,this arrangement is sometimes repeated throughout a great succession of strata4 ,from what we know of the growth of similar zoophytes in modern reefs1 we infer that the rate of increase was extremely slow1 and some of the fossils must have flourished for ages like forest trees1 before they attained so large a size4 ,during these ages1 the water remained clear and transparent1 for such corals cannot live in turbid water4 ,illustration3 ,fig4 #aj4 ,fossil ,gryphaea1 covered both on the outside and inside with fossil serpulae4 ,in like manner1 when we see thousands of full-grown shells dispersed every where throughout a long series of strata1 we cannot doubt that time was required for the multiplication of successive generations2 and the evidence of slow accumulation is rendered more striking from the proofs1 so often discovered1 of fossil bodies having lain for a time on the floor of the ocean after death before they were imbedded in sediment4 ,nothing1 for example1 is more common than to see fossil oysters in clay1 with serpulae1 or barnacles 7acorn-shells71 or corals1 and other creatures1 attached to the inside of the valves1 so that the mollusk was certainly not buried in argillaceous mud the moment it died4 ,there must have been an interval during which it was still surrounded with clear water1 when the testacea1 now adhering to it1 grew from an embryo state to full maturity4 ,attached shells which are merely external1 like some of the serpulae 7a7 in the annexed figure 7fig4 #aj471 may often have grown upon an oyster or other shell while the animal within was still living2 but if they are found on the inside1 it could only happen after the death of the inhabitant of the shell which affords the support4 ,thus1 in fig4 #aj41 it will be seen that two serpulae have grown on the interior1 one of them exactly on the place where the adductor muscle of the ,gryphaea 7a kind of oyster7 was fixed4 ,some fossil shells1 even if simply attached to the outside of others1 bear full testimony to the conclusion above alluded to1 namely1 that an interval elapsed between the death of the creature to whose shell they adhere1 and the burial of the same in mud or sand4 ,the sea-urchins or ,echini1 so abundant in white chalk1 afford a good illustration4 ,it is well known that these animals1 when living1 are invariably covered with numerous spines1 which serve as organs of motion1 and are supported by rows of tubercles1 which last are only seen after the death of the sea-urchin1 when the spines have dropped off4 ,in fig4 #ab4 a living species of ,spatangus1 common on our coast1 is represented with one half of its shell stripped of the spines4 ,in fig4 #aa4 a fossil of the same genus from the white chalk of ,england shows the naked surface which the individuals of this family exhibit when denuded of their bristles4 ,the full-grown ,serpula1 therefore1 which now adheres externally1 could not have begun to grow till the ,spatangus had died1 and the spines were detached4 ,illustration3 ,fig4 #aa4 ,serpula attached to a fossil ,spatangus from the chalk4 ,illustration3 ,fig4 #ab4 ,recent ,spatangus with the spines removed from one side4 b4 ,spine and tubercles1 nat4 size4 a4 ,the same magnified4 ,illustration3 ,fig4 #ac4 a4 ,echinus from the chalk1 with lower valve of the ,crania attached4 b4 ,upper valve of the ,crania detached4 ,now the series of events here attested by a single fossil may be carried a step farther4 ,thus1 for example1 we often meet with a sea-urchin in the chalk 7see fig4 #ac471 which has fixed to it the lower valve of a ,crania1 a genus of bivalve mollusca4 ,the upper valve 7b1 fig4 #ac47 is almost invariably wanting1 though occasionally found in a perfect state of preservation in white chalk at some distance4 ,in this case1 we see clearly that the sea-urchin first lived from youth to age1 then died and lost its spines1 which were carried away4 ,then the young ,crania adhered to the bared shell1 grew and perished in its turn2 after which the upper valve was separated from the lower before the ,echinus became enveloped in chalky mud4 ,it may be well to mention one more illustration of the manner in which single fossils may sometimes throw light on a former state of things1 both in the bed of the ocean and on some adjoining land4 ,we meet with many fragments of wood bored by ship-worms at various depths in the clay on which ,london is built4 ,entire branches and stems of trees1 several feet in length1 are sometimes dug out1 drilled all over by the holes of these borers1 the tubes and shells of the mollusk still remaining in the cylindrical hollows4 ,in fig4 #ae4 e1 a representation is given of a piece of recent wood pierced by the ,teredo navalis1 or common ship-worm1 which destroys wooden piles and ships4 ,when the cylindrical tube d has been extracted from the wood1 a shell is seen at the larger extremity1 composed of two pieces1 as shown at c4 ,in like manner1 a piece of fossil wood 7a1 fig4 #ad47 has been perforated by an animal of a kindred but extinct genus1 called ,teredina by ,lamarck4 ,the calcareous tube of this mollusk was united and as it were soldered on to the valves of the shell 7b71 which therefore cannot be detached from the tube1 like the valves of the recent ,teredo4 ,the wood in this fossil specimen is now converted into a stony mass1 a mixture of clay and lime2 but it must once have been buoyant and floating in the sea1 when the ,teredinae lived upon it1 perforating it in all directions4 ,again1 before the infant colony settled upon the drift wood1 the branch of a tree must have been floated down to the sea by a river1 uprooted1 perhaps1 by a flood1 or torn off and cast into the waves by the wind3 and thus our thoughts are carried back to a prior period1 when the tree grew for years on dry land1 enjoying a fit soil and climate4 #b ,illustrations3 ,fossil and recent wood drilled by perforating ,mollusca4 ,fig4 #ad4 a4 ,fossil wood from ,london clay1 bored by ,teredina4 b4 ,shell and tube of ,teredina personata1 the right-hand figure the ventral1 the left the dorsal view4 ,fig4 #ae4 e4 ,recent wood bored by ,teredo4 d4 ,shell and tube of ,teredo navalis1 from the same4 c4 ,anterior and posterior view of the valves of same detached from the tube4 ,it has been already remarked that there are rocks in the interior of continents1 at various depths in the earth1 and at great heights above the sea1 almost entirely made up of the remains of zoophytes and testacea4 ,such masses may be compared to modern oyster-beds and coral reefs2 and1 like them1 the rate of increase must have been extremely gradual4 ,but there are a variety of stony deposits in the earth's crust1 now proved to have been derived from plants and animals1 of which the organic origin was not suspected until of late years1 even by naturalists4 ,great surprise was therefore created by the recent discovery of ,professor ,ehrenberg of ,berlin1 that a certain kind of siliceous stone1 called tripoli1 was entirely composed of millions of the remains of organic beings1 which the ,prussian naturalist refers to microscopic ,infusoria1 but which most others now believe to be plants4 ,they abound in freshwater lakes and ponds in ,england and other countries1 and are termed ,diatomaceae by those naturalists who believe in their vegetable origin4 ,the substance alluded to has long been well known in the arts1 being used in the form of powder for polishing stones and metals4 ,it has been procured1 among other places1 from ,bilin1 in ,bohemia1 where a single stratum1 extending over a wide area1 is no less than #ad feet thick4 ,this stone1 when examined with a powerful microscope1 is found to consist of the siliceous plates or frustules of the above-mentioned ,diatomaceae1 united together without any visible cement4 ,it is difficult to convey an idea of their extreme minuteness2 but ,ehrenberg estimates that in the ,bilin tripoli there are #da1jjj millions of individuals of the ,gaillonella distans 7see fig4 #ag47 in every cubic inch1 which weighs about #bbj grains1 or about #ahg millions in a single grain4 ,at every stroke1 therefore1 that we make with this polishing powder1 several millions1 perhaps tens of millions1 of perfect fossils are crushed to atoms4 #c ,illustrations3 ,these figures are magnified nearly #cjj times1 except the lower figure of ,g4 ferruginea 7fig4 #ah4 a71 which is magnified #bjjj times4 ,fig4 #af4 ,bacillaria vulgaris8 ,fig4 #ag4 ,gaillonella distans4 ,fig4 #ah4 ,gaillonella ferruginea4 #b ,illustrations3 ,fragment of semi-opal from the great bed of ,tripoli1 ,bilin4 ,fig4 #ai4 ,natural size4 ,fig4 #bj4 ,the same magnified1 showing circular articulations of a species of ,gaillonella1 and spiculae of ,spongilla4 ,the remains of these ,diatomaceae are of pure silex1 and their forms are various1 but very marked and constant in particular genera and species4 ,thus1 in the family ,bacillaria 7see fig4 #af471 the fossils preserved in tripoli are seen to exhibit the same divisions and transverse lines which characterize the living species of kindred form4 ,with these1 also1 the siliceous spiculae or internal supports of the freshwater sponge1 or ,spongilla of ,lamarck1 are sometimes intermingled 7see the needle-shaped bodies in fig4 #bj474 ,these flinty cases and spiculae1 although hard1 are very fragile1 breaking like glass1 and are therefore admirably adapted1 when rubbed1 for wearing down into a fine powder fit for polishing the surface of metals4 ,besides the tripoli1 formed exclusively of the fossils above described1 there occurs in the upper part of the great stratum at ,bilin another heavier and more compact stone1 a kind of semi-opal1 in which innumerable parts of ,diatomaceae and spiculae of the ,spongilla are filled with1 and cemented together by1 siliceous matter4 ,it is supposed that the siliceous remains of the most delicate ,diatomaceae have been dissolved by water1 and have thus given rise to this opal in which the more durable fossils are preserved like insects in amber4 ,this opinion is confirmed by the fact that the organic bodies decrease in number and sharpness of outline in proportion as the opaline cement increases in quantity4 ,in the ,bohemian tripoli above described1 as in that of ,planitz in ,saxony1 the species of ,diatomaceae 7or ,infusoria1 as termed by ,ehrenberg7 are freshwater2 but in other countries1 as in the tripoli of the ,isle of ,france1 they are of marine species1 and they all belong to formations of the tertiary period1 which will be spoken of hereafter4 ,a well-known substance1 called bog-iron ore1 often met with in peat-mosses1 has also been shown by ,ehrenberg to consist of innumerable articulated threads1 of a yellow ochre colour1 composed partly of flint and partly of oxide of iron4 ,these threads are the cases of a minute microscopic body1 called ,gaillonella ferruginea 7fig4 #ah474 #d ,illustrations3 ,cytheridae and ,foraminifera from the chalk4 ,fig4 #ba4 ,cythere1 ,muell4 ,cytherina1 ,lam4 ,fig4 #bb4 ,portion of ,nodosaria4 ,fig4 #bc4 ,cristellaria rotulata4 ,fig4 #bd4 ,rosalina4 ,it is clear that much time must have been required for the accumulation of strata to which countless generations of ,diatomaceae have contributed their remains2 and these discoveries lead us naturally to suspect that other deposits1 of which the materials have usually been supposed to be inorganic1 may in reality have been derived from microscopic organic bodies4 ,that this is the case with the white chalk1 has often been imagined1 this rock having been observed to abound in a variety of marine fossils1 such as shells1 echini1 corals1 sponges1 crustacea1 and fishes4 ,mr4 ,lonsdale1 on examining1 in ,oct4 #ahce1 in the museum of the ,geological ,society of ,london1 portions of white chalk from different parts of ,england1 found1 on carefully pulverizing them in water1 that what appear to the eye simply as white grains were1 in fact1 well preserved fossils4 ,he obtained above a thousand of these from each pound weight of chalk1 some being fragments of minute corallines1 others entire ,foraminifera and ,cytheridae4 ,the annexed drawings will give an idea of the beautiful forms of many of these bodies4 ,the figures a a represent their natural size1 but1 minute as they seem1 the smallest of them1 such as a1 fig4 #bd41 are gigantic in comparison with the cases of ,diatomaceae before mentioned4 ,it has1 moreover1 been lately discovered that the chambers into which these ,foraminifera are divided are actually often filled with thousands of well-preserved organic bodies1 which abound in every minute grain of chalk1 and are especially apparent in the white coating of flints1 often accompanied by innumerable needle-shaped spiculae of sponges4 ,after reflecting on these discoveries1 we are naturally led on to conjecture that1 as the formless cement in the semi-opal of ,bilin has been derived from the decomposition of animal and vegetable remains1 so also even those parts of chalk flints in which no organic structure can be recognized may nevertheless have constituted a part of microscopic animalcules4 ,the dust we tread upon was once alive6--,,byron4 ,how faint an idea does this exclamation of the poet convey of the real wonders of nature6 for here we discover proofs that the calcareous and siliceous dust of which hills are composed has not only been once alive1 but almost every particle1 albeit invisible to the naked eye1 still retains the organic structure which1 at periods of time incalculably remote1 was impressed upon it by the powers of life4 ,freshwater and marine fossils4--,strata1 whether deposited in salt or fresh water1 have the same forms2 but the imbedded fossils are very different in the two cases1 because the aquatic animals which frequent lakes and rivers are distinct from those inhabiting the sea4 ,in the northern part of the ,isle of ,wight a formation of marl and limestone1 more than #ej feet thick1 occurs1 in which the shells are principally1 if not all1 of extinct species4 ,yet we recognize their freshwater origin1 because they are of the same genera as those now abounding in ponds and lakes1 either in our own country or in warmer latitudes4 ,in many parts of ,france1 as in ,auvergne1 for example1 strata of limestone1 marl1 and sandstone are found1 hundreds of feet thick1 which contain exclusively freshwater and land shells1 together with the remains of terrestrial quadrupeds4 ,the number of land shells scattered through some of these freshwater deposits is exceedingly great2 and there are districts in ,germany where the rocks scarcely contain any other fossils except snail-shells 7helices72 as1 for instance1 the limestone on the left bank of the ,rhine1 between ,mayence and ,worms1 at ,oppenheim1 ,findheim1 ,budenheim1 and other places4 ,in order to account for this phenomenon1 the geologist has only to examine the small deltas of torrents which enter the ,swiss lakes when the waters are low1 such as the newly-formed plain where the ,kander enters the ,lake of ,thun4 ,he there sees sand and mud strewed over with innumerable dead land shells1 which have been brought down from valleys in the ,alps in the preceding spring1 during the melting of the snows4 ,again1 if we search the sands on the borders of the ,rhine1 in the lower part of its course1 we find countless land shells mixed with others of species belonging to lakes1 stagnant pools1 and marshes4 ,these individuals have been washed away from the alluvial plains of the great river and its tributaries1 some from mountainous regions1 others from the low country4 ,although freshwater formations are often of great thickness1 yet they are usually very limited in area when compared to marine deposits1 just as lakes and estuaries are of small dimensions in comparison with seas4 ,we may distinguish a freshwater formation1 first1 by the absence of many fossils almost invariably met with in marine strata4 ,for example1 there are no sea-urchins1 no corals1 and scarcely any zoophytes2 no chambered shells1 such as the nautilus1 nor microscopic ,foraminifera4 ,but it is chiefly by attending to the forms of the mollusca that we are guided in determining the point in question4 ,in a freshwater deposit1 the number of individual shells is often as great1 if not greater1 than in a marine stratum2 but there is a smaller variety of species and genera4 ,this might be anticipated from the fact that the genera and species of recent freshwater and land shells are few when contrasted with the marine4 ,thus1 the genera of true mollusca according to ,blainville's system1 excluding those of extinct species and those without shells1 amount to about #bjj in number1 of which the terrestrial and freshwater genera scarcely form more than a sixth4#bh-;,a ,illustration3 ,fig4 #be4 ,cyclas obovata2 fossil4 ,hants4 ,illustration3 ,fig4 #bf4 ,cyrena consobrina2 fossil4 ,grays1 ,essex4 ,illustration3 ,fig4 #bg4 ,anodonta ,cordierii2 fossil4 ,paris4 ,illustration3 ,fig4 #bh4 ,anodonta latimarginatus2 recent4 ,bahia4 ,illustration3 ,fig4 #bi4 ,unio littoralis2 recent4 ,auvergne4 ,almost all bivalve shells1 or those of acephalous mollusca1 are marine1 about ten only out of ninety genera being freshwater4 ,among these last1 the four most common forms1 both recent and fossil1 are ,cyclas1 ,cyrena1 ,unio1 and ,anodonta 7see figures72 the two first and two last of which are so nearly allied as to pass into each other4 ,illustration3 ,fig4 #cj4 ,gryphaea incurva1 ,sow4 7,g4 arcuata1 ,lam47 upper valve4 ,lias4 ,lamarck divided the bivalve mollusca into the ,dimyary1 or those having two large muscular impressions in each valve1 as a b in the ,cyclas1 fig4 #be41 and the ,monomyary1 such as the oyster and scallop1 in which there is only one of these impressions1 as is seen in fig4 #cj4 ,now1 as none of these last1 or the unimuscular bivalves1 are freshwater1 we may at once presume a deposit in which we find any of them to be marine4 ,illustration3 ,fig4 #ca4 ,planorbis euomphalus2 fossil4 ,isle of ,wight4 ,illustration3 ,fig4 #cb4 ,lymnea longiscata2 fossil4 ,hants4 ,illustration3 ,fig4 #cc4 ,paludina lenta2 fossil4 ,hants4 ,the univalve shells most characteristic of freshwater deposits are1 ,planorbis1 ,lymnea1 and ,paludina4 7,see figures47 ,but to these are occasionally added ,physa1 ,succinea1 ,ancylus1 ,valvata1 ,melanopsis1 ,melania1 and ,neritina4 7,see figures47 ,illustration3 ,fig4 #cd4 ,succinea amphibia2 fossil4 ,loess1 ,rhine4 ,illustration3 ,fig4 #ce4 ,ancylus elegans2 fossil4 ,hants4 ,illustration3 ,fig4 #cf4 ,valvata2 fossil4 ,grays1 ,essex4 ,illustration3 ,fig4 #cg4 ,physa hypnorum2 recent4 ,illustration3 ,fig4 #ch4 ,auricula2 recent4 ,ava4 ,illustration3 ,fig4 #ci4 ,melania inquinata4 ,paris ,basin4 ,illustration3 ,fig4 #dj4 ,physa columnaris4 ,paris ,basin4 ,illustration3 ,fig4 #da4 ,melanopsis buccinoidea2 recent4 ,asia4 ,in regard to one of these1 the ,ancylus 7fig4 #ce471 ,mr4 ,gray observes that it sometimes differs in no respect from the marine ,siphonaria1 except in the animal4 ,the shell1 however1 of the ,ancylus is usually thinner4#bi-;,a ,illustration3 ,fig4 #db4 ,neritina globulus4 ,paris basin4 ,illustration3 ,fig4 #dc4 ,nerita granulosa4 ,paris basin4 ,some naturalists include ,neritina 7fig4 #db47 and the marine ,nerita 7fig4 #dc47 in the same genus1 it being scarcely possible to distinguish the two by good generic characters4 ,but1 as a general rule1 the fluviatile species are smaller1 smoother1 and more globular than the marine2 and they have never1 like the ,neritae1 the inner margin of the outer lip toothed or crenulated4 7,see fig4 #dc47 ,illustration3 ,fig4 #dd4 ,cerithium cinctum4 ,paris basin4 ,a few genera1 among which ,cerithium 7fig4 #dd47 is the most abundant1 are common both to rivers and the sea1 having species peculiar to each4 ,other genera1 like ,auricula 7fig4 #ch471 are amphibious1 frequenting marshes1 especially near the sea4 ,illustration3 ,fig4 #de4 ,helix ,turonensis4 ,faluns1 ,touraine4 ,illustration3 ,fig4 #df4 ,cyclostoma elegans4 ,loess4 ,illustration3 ,fig4 #dg4 ,pupa tridens4 ,loess4 ,illustration3 ,fig4 #dh4 ,clausilia bidens4 ,loess4 ,illustration3 ,fig4 #di4 ,bulimus lubricus4 ,loess1 ,rhine4 ,the terrestrial shells are all univalves4 ,the most abundant genera among these1 both in a recent and fossil state1 are ,helix 7fig4 #de471 ,cyclostoma 7fig4 #df471 ,pupa 7fig4 #dg471 ,clausilia 7fig4 #dh471 ,bulimus 7fig4 #di471 and ,achatina2 which two last are nearly allied and pass into each other4 ,illustration3 ,fig4 #ej4 ,ampullaria glauca1 from the ,jumna4 ,the ,ampullaria 7fig4 #ej47 is another genus of shells1 inhabiting rivers and ponds in hot countries4 ,many fossil species have been referred to this genus1 but they have been found chiefly in marine formations1 and are suspected by some conchologists to belong to ,natica and other marine genera4 ,all univalve shells of land and freshwater species1 with the exception of ,melanopsis 7fig4 #da471 and ,achatina1 which has a slight indentation1 have entire mouths2 and this circumstance may often serve as a convenient rule for distinguishing freshwater from marine strata2 since1 if any univalves occur of which the mouths are not entire1 we may presume that the formation is marine4 ,the aperture is said to be entire in such shells as the ,ampullaria and the land shells 7figs4 #de-di471 when its outline is not interrupted by an indentation or notch1 such as that seen at b in ,ancillaria 7fig4 #eb472 or is not prolonged into a canal1 as that seen at a in ,pleurotoma 7fig4 #ea474 ,illustration3 ,fig4 #ea4 ,pleurotoma rotata4 ,subap4 hills1 ,italy4 ,illustration3 ,fig4 #eb4 ,ancillaria subulata4 ,london clay4 ,the mouths of a large proportion of the marine univalves have these notches or canals1 and almost all such species are carnivorous2 whereas nearly all testacea having entire mouths1 are plant-eaters2 whether the species be marine1 freshwater1 or terrestrial4 ,there is1 however1 one genus which affords an occasional exception to one of the above rules4 ,the ,cerithium 7fig4 #dd471 although provided with a short canal1 comprises some species which inhabit salt1 others brackish1 and others fresh water1 and they are said to be all plant-eaters4 ,among the fossils very common in freshwater deposits are the shells of ,cypris1 a minute crustaceous animal1 having a shell much resembling that of the bivalve mollusca4#ca-;,a ,many minute living species of this genus swarm in lakes and stagnant pools in ,great ,britain2 but their shells are not1 if considered separately1 conclusive as to the freshwater origin of a deposit1 because the majority of species in another kindred genus of the same order1 the ,cytherina of ,lamarck 7see above1 fig4 #ba4 p4 #bf471 inhabit salt water2 and1 although the animal differs slightly1 the shell is scarcely distinguishable from that of the ,cypris4 ,the seed-vessels and stems of ,chara1 a genus of aquatic plants1 are very frequent in freshwater strata4 ,these seed-vessels were called1 before their true nature was known1 gyrogonites1 and were supposed to be foraminiferous shells4 7,see fig4 #ec4 a47 ,the ,charae inhabit the bottom of lakes and ponds1 and flourish mostly where the water is charged with carbonate of lime4 ,their seed-vessels are covered with a very tough integument1 capable of resisting decomposition2 to which circumstance we may attribute their abundance in a fossil state4 ,the annexed figure 7fig4 #ed47 represents a branch of one of many new species found by ,professor ,amici in the lakes of northern ,italy4 ,the seed-vessel in this plant is more globular than in the ,british ,charae1 and therefore more nearly resembles in form the extinct fossil species found in ,england1 ,france1 and other countries4 ,the stems1 as well as the seed-vessels1 of these plants occur both in modern shell marl and in ancient freshwater formations4 ,they are generally composed of a large tube surrounded by smaller tubes2 the whole stem being divided at certain intervals by transverse partitions or joints4 7,see b1 fig4 #ec47 ,illustration3 ,fig4 #ec4 ,chara medicaginula2 fossil4 ,isle of ,wight4 a4 ,seed-vessel4 magnified #bj diameters4 b4 ,stem1 magnified4 ,illustration3 ,fig4 #ed4 ,chara elastica2 recent4 ,italy4 a4 ,sessile seed vessel between the division of the leaves of the female plant4 b4 ,transverse section of a branch1 with five seed-vessels magnified1 seen from below upwards4 ,it is not uncommon to meet with layers of vegetable matter1 impressions of leaves1 and branches of trees1 in strata containing freshwater shells2 and we also find occasionally the teeth and bones of land quadrupeds1 of species now unknown4 ,the manner in which such remains are occasionally carried by rivers into lakes1 especially during floods1 has been fully treated of in the ,principles of ,geology4#cb-;,a ,the remains of fish are occasionally useful in determining the freshwater origin of strata4 ,certain genera1 such as carp1 perch1 pike1 and loach 7,cyprinus1 ,perca1 ,esox1 and ,cobitis71 as also ,lebias1 being peculiar to freshwater4 ,other genera contain some freshwater and some marine species1 as ,cottus1 ,mugil1 and ,anguilla1 or eel4 ,the rest are either common to rivers and the sea1 as the salmon2 or are exclusively characteristic of salt water4 ,the above observations respecting fossil fishes are applicable only to the more modern or tertiary deposits2 for in the more ancient rocks the forms depart so widely from those of existing fishes1 that it is very difficult1 at least in the present state of science1 to derive any positive information from ichthyolites respecting the element in which strata were deposited4 ,the alternation of marine and freshwater formations1 both on a small and large scale1 are facts well ascertained in geology4 ,when it occurs on a small scale1 it may have arisen from the alternate occupation of certain spaces by river water and the sea2 for in the flood season the river forces back the ocean and freshens it over a large area1 depositing at the same time its sediment2 after which the salt water again returns1 and1 on resuming its former place1 brings with it sand1 mud1 and marine shells4 ,there are also lagoons at the mouths of many rivers1 as the ,nile and ,mississippi1 which are divided off by bars of sand from the sea1 and which are filled with salt and fresh water by turns4 ,they often communicate exclusively with the river for months1 years1 or even centuries2 and then a breach being made in the bar of sand1 they are for long periods filled with salt water4 ,the ,lym-,fiord in ,jutland offers an excellent illustration of analogous changes2 for1 in the course of the last thousand years1 the western extremity of this long frith1 which is #abj miles in length1 including its windings1 has been four times fresh and four times salt1 a bar of sand between it and the ocean having been as often formed and removed4 ,the last irruption of salt water happened in #ahbd1 when the ,north ,sea entered1 killing all the freshwater shells1 fish1 and plants2 and from that time to the present1 the sea-weed ,fucus vesiculosus1 together with oysters and other marine mollusca1 have succeeded the ,cyclas1 ,lymnea1 ,paludina1 and ,charae4#cc-;,a ,but changes like these in the ,lym-,fiord1 and those before mentioned as occurring at the mouths of great rivers1 will only account for some cases of marine deposits of partial extent resting on freshwater strata4 ,when we find1 as in the south-east of ,england1 a great series of freshwater beds1 #ajjj feet in thickness1 resting upon marine formations and again covered by other rocks1 such as the cretaceous1 more than #ajjj feet thick1 and of deep-sea origin1 we shall find it necessary to seek for a different explanation of the phenomena4#cc-;,b ,,footnotes3 #bh-;,a ,see ,synoptic ,table in ,blainville's ,malacologie4 #bi-;,a ,gray1 ,phil4 ,trans41 #ahce1 p4 #cjb4 #ca-;,a ,for figures of recent species1 see below1 p4 #ahc41 and figs4 of fossils1 see p4 #bbh4 #cb-;,a ,see ,index of ,principles1 ,fossilization4 #cc-;,a ,see ,principles1 ,index1 ,lym-,fiord4 #cc-;,b ,see below1 ,chap4 ,,xviii41 on the ,wealden4 ,,chapter ,,iv4 ,,consolidation ,,of ,,strata ,,and ,,petrifaction ,,of ,,fossils4 ,chemical and mechanical deposits--,cementing together of particles--,hardening by exposure to air--,concretionary nodules--,consolidating effects of pressure--,mineralization of organic remains--,impressions and casts how formed--,fossil wood--,goeppert's experiments--,precipitation of stony matter most rapid where putrefaction is going on--,source of lime in solution--,silex derived from decomposition of felspar--,proofs of the lapidification of some fossils soon after burial1 of others when much decayed4 ,having spoken in the preceding chapters of the characters of sedimentary formations1 both as dependent on the deposition of inorganic matter and the distribution of fossils1 ,i may next treat of the consolidation of stratified rocks1 and the petrifaction of imbedded organic remains4 ,chemical and mechanical deposits4--,a distinction has been made by geologists between deposits of a chemical1 and those of a mechanical1 origin4 ,by the latter name are designated beds of mud1 sand1 or pebbles produced by the action of running water1 also accumulations of stones and scoriae thrown out by a volcano1 which have fallen into their present place by the force of gravitation4 ,but the matter which forms a chemical deposit has not been mechanically suspended in water1 but in a state of solution until separated by chemical action4 ,in this manner carbonate of lime is often precipitated upon the bottom of lakes and seas in a solid form1 as may be well seen in many parts of ,italy1 where mineral springs abound1 and where the calcareous stone1 called travertin1 is deposited4 ,in these springs the lime is usually held in solution by an excess of carbonic acid1 or by heat if it be a hot spring1 until the water1 on issuing from the earth1 cools or loses part of its acid4 ,the calcareous matter then falls down in a solid state1 encrusting shells1 fragments of wood and leaves1 and binding them together4#cd-;,a ,in coral reefs1 large masses of limestone are formed by the stony skeletons of zoophytes2 and these1 together with shells1 become cemented together by carbonate of lime1 part of which is probably furnished to the sea-water by the decomposition of dead corals4 ,even shells of which the animals are still living1 on these reefs1 are very commonly found to be encrusted over with a hard coating of limestone4#cd-;,b ,if sand and pebbles are carried by a river into the sea1 and these are bound together immediately by carbonate of lime1 the deposit may be described as of a mixed origin1 partly chemical1 and partly mechanical4 ,now1 the remarks already made in ,chapter ,,ii4 on the original horizontality of strata are strictly applicable to mechanical deposits1 and only partially to those of a mixed nature4 ,such as are purely chemical may be formed on a very steep slope1 or may even encrust the vertical walls of a fissure1 and be of equal thickness throughout2 but such deposits are of small extent1 and for the most part confined to veinstones4 ,cementing of particles4--,it is chiefly in the case of calcareous rocks that solidification takes place at the time of deposition4 ,but there are many deposits in which a cementing process comes into operation long afterwards4 ,we may sometimes observe1 where the water of ferruginous or calcareous springs has flowed through a bed of sand or gravel1 that iron or carbonate of lime has been deposited in the interstices between the grains or pebbles1 so that in certain places the whole has been bound together into a stone1 the same set of strata remaining in other parts loose and incoherent4 ,proofs of a similar cementing action are seen in a rock at ,kelloway in ,wiltshire4 ,a peculiar band of sandy strata1 belonging to the group called ,oolite by geologists1 may be traced through several counties1 the sand being for the most part loose and unconsolidated1 but becoming stony near ,kelloway4 ,in this district there are numerous fossil shells which have decomposed1 having for the most part left only their casts4 ,the calcareous matter hence derived has evidently served1 at some former period1 as a cement to the siliceous grains of sand1 and thus a solid sandstone has been produced4 ,if we take fragments of many other argillaceous grits1 retaining the casts of shells1 and plunge them into dilute muriatic or other acid1 we see them immediately changed into common sand and mud2 the cement of lime1 derived from the shells1 having been dissolved by the acid4 ,traces of impressions and casts are often extremely faint4 ,in some loose sands of recent date we meet with shells in so advanced a stage of decomposition as to crumble into powder when touched4 ,it is clear that water percolating such strata may soon remove the calcareous matter of the shell2 and1 unless circumstances cause the carbonate of lime to be again deposited1 the grains of sand will not be cemented together2 in which case no memorial of the fossil will remain4 ,the absence of organic remains from many aqueous rocks may be thus explained2 but we may presume that in many of them no fossils were ever imbedded1 as there are extensive tracts on the bottoms of existing seas even of moderate depth on which no fragment of shell1 coral1 or other living creature can be detected by dredging4 ,on the other hand1 there are depths where the zero of animal life has been approached2 as1 for example1 in the ,mediterranean1 at the depth of about #bcj fathoms1 according to the researches of ,prof4 ,e4 ,forbes4 ,in the ,a,egean ,sea a deposit of yellowish mud of a very uniform character1 and closely resembling chalk1 is going on in regions below #bcj fathoms1 and this formation must be wholly devoid of organic remains4#ce-;,a ,in what manner silex and carbonate of lime may become widely diffused in small quantities through the waters which permeate the earth's crust will be spoken of presently1 when the petrifaction of fossil bodies is considered2 but ,i may remark here that such waters are always passing in the case of thermal springs from hotter to colder parts of the interior of the earth2 and as often as the temperature of the solvent is lowered1 mineral matter has a tendency to separate from it and solidify4 ,thus a stony cement is often supplied to any sand1 pebbles1 or fragmentary mixture4 ,in some conglomerates1 like the pudding-stone of ,hertfordshire1 pebbles of flint and grains of sand are united by a siliceous cement so firmly1 that if a block be fractured the rent passes as readily through the pebbles as through the cement4 ,it is probable that many strata became solid at the time when they emerged from the waters in which they were deposited1 and when they first formed a part of the dry land4 ,a well-known fact seems to confirm this idea3 by far the greater number of the stones used for building and road-making are much softer when first taken from the quarry than after they have been long exposed to the air2 and these1 when once dried1 may afterwards be immersed for any length of time in water without becoming soft again4 ,hence it is found desirable to shape the stones which are to be used in architecture while they are yet soft and wet1 and while they contain their quarry-water1 as it is called2 also to break up stone intended for roads when soft1 and then leave it to dry in the air for months that it may harden4 ,such induration may perhaps be accounted for by supposing the water1 which penetrates the minutest pores of rocks1 to deposit1 on evaporation1 carbonate of lime1 iron1 silex1 and other minerals previously held in solution1 and thereby to fill up the pores partially4 ,these particles1 on crystallizing1 would not only be themselves deprived of freedom of motion1 but would also bind together other portions of the rock which before were loosely aggregated4 ,on the same principle wet sand and mud become as hard as stone when frozen2 because one ingredient of the mass1 namely1 the water1 has crystallized1 so as to hold firmly together all the separate particles of which the loose mud and sand were composed4 ,dr4 ,mac,culloch mentions a sandstone in ,skye1 which may be moulded like dough when first found2 and some simple minerals1 which are rigid and as hard as glass in our cabinets1 are often flexible and soft in their native beds2 this is the case with asbestos1 sahlite1 tremolite1 and chalcedony1 and it is reported also to happen in the case of the beryl4#cf-;,a ,the marl recently deposited at the bottom of ,lake ,superior1 in ,north ,america1 is soft1 and often filled with freshwater shells2 but if a piece be taken up and dried1 it becomes so hard that it can only be broken by a smart blow of the hammer4 ,if the lake therefore was drained1 such a deposit would be found to consist of strata of marlstone1 like that observed in many ancient ,european formations1 and like them containing freshwater shells4#cf-;,b ,it is probable that some of the heterogeneous materials which rivers transport to the sea may at once set under water1 like the artificial mixture called pozzolana1 which consists of fine volcanic sand charged with about #bj per cent4 of oxide of iron1 and the addition of a small quantity of lime4 ,this substance hardens1 and becomes a solid stone in water1 and was used by the ,romans in constructing the foundations of buildings in the sea4 ,consolidation in these cases is brought about by the action of chemical affinity on finely comminuted matter previously suspended in water4 ,after deposition similar particles seem to exert a mutual attraction on each other1 and congregate together in particular spots1 forming lumps1 nodules1 and concretions4 ,thus in many argillaceous deposits there are calcareous balls1 or spherical concretions1 ranged in layers parallel to the general stratification2 an arrangement which took place after the shale or marl had been thrown down in successive laminae2 for these laminae are often traced in the concretions1 remaining parallel to those of the surrounding unconsolidated rock4 7,see fig4 #ee47 ,such nodules of limestone have often a shell or other foreign body in the centre4#cg-;,a ,illustration3 ,fig4 #ee4 ,calcareous nodules in ,lias4 ,among the most remarkable examples of concretionary structure are those described by ,professor ,sedgwick as abounding in the magnesian limestone of the north of ,england4 ,the spherical balls are of various sizes1 from that of a pea to a diameter of several feet1 and they have both a concentric and radiated structure1 while at the same time the laminae of original deposition pass uninterruptedly through them4 ,in some cliffs this limestone resembles a great irregular pile of cannon balls4 ,some of the globular masses have their centre in one stratum1 while a portion of their exterior passes through to the stratum above or below4 ,thus the larger spheroid in the annexed section 7fig4 #ef47 passes from the stratum b upwards into a4 ,in this instance we must suppose the deposition of a series of minor layers1 first forming the stratum b1 and afterwards the incumbent stratum a2 then a movement of the particles took place1 and the carbonates of lime and magnesia separated from the more impure and mixed matter forming the still unconsolidated parts of the stratum4 ,crystallization1 beginning at the centre1 must have gone on forming concentric coats1 around the original nucleus without interfering with the laminated structure of the rock4 ,illustration3 ,fig4 #ef4 ,spheroidal concretions in magnesian limestone4 ,when the particles of rocks have been thus re-arranged by chemical forces1 it is sometimes difficult or impossible to ascertain whether certain lines of division are due to original deposition or to the subsequent aggregation of similar particles4 ,thus suppose three strata of grit1 ,a1 ,b1 ,c1 are charged unequally with calcareous matter1 and that ,b is the most calcareous4 ,if consolidation takes place in ,b1 the concretionary action may spread upwards into a part of ,a1 where the carbonate of lime is more abundant than in the rest2 so that a mass1 d1 e1 f1 forming a portion of the superior stratum1 becomes united with ,b into one solid mass of stone4 ,the original line of division d1 e1 being thus effaced1 the line d1 f1 would generally be considered as the surface of the bed ,b1 though not strictly a true plane of stratification4 ,illustration3 ,fig4 #eg4 ,block section4 ,pressure and heat4--,when sand and mud sink to the bottom of a deep sea1 the particles are not pressed down by the enormous weight of the incumbent ocean2 for the water1 which becomes mingled with the sand and mud1 resists pressure with a force equal to that of the column of fluid above4 ,the same happens in regard to organic remains which are filled with water under great pressure as they sink1 otherwise they would be immediately crushed to pieces and flattened4 ,nevertheless1 if the materials of a stratum remain in a yielding state1 and do not set or solidify1 they will be gradually squeezed down by the weight of other materials successively heaped upon them1 just as soft clay or loose sand on which a house is built may give way4 ,by such downward pressure particles of clay1 sand1 and marl1 may become packed into a smaller space1 and be made to cohere together permanently4 ,analogous effects of condensation may arise when the solid parts of the earth's crust are forced in various directions by those mechanical movements afterwards to be described1 by which strata have been bent1 broken1 and raised above the level of the sea4 ,rocks of more yielding materials must often have been forced against others previously consolidated1 and1 thus compressed1 may have acquired a new structure4 ,a recent discovery may help us to comprehend how fine sediment derived from the detritus of rocks may be solidified by mere pressure4 ,the graphite or black lead of commerce having become very scarce1 ,mr4 ,brockedon contrived a method by which the dust of the purer portions of the mineral found in ,borrowdale might be recomposed into a mass as dense and compact as native graphite4 ,the powder of graphite is first carefully prepared and freed from air1 and placed under a powerful press on a strong steel die1 with air-tight fittings4 ,it is then struck several blows1 each of a power of #ajjj tons2 after which operation the powder is so perfectly solidified that it can be cut for pencils1 and exhibits when broken the same texture as native graphite4 ,but the action of heat at various depths in the earth is probably the most powerful of all causes in hardening sedimentary strata4 ,to this subject ,i shall refer again when treating of the metamorphic rocks1 and of the slaty and jointed structure4 ,mineralization of organic remains4--,the changes which fossil organic bodies have undergone since they were first imbedded in rocks1 throw much light on the consolidation of strata4 ,fossil shells in some modern deposits have been scarcely altered in the course of centuries1 having simply lost a part of their animal matter4 ,but in other cases the shell has disappeared1 and left an impression only of its exterior1 or a cast of its interior form1 or thirdly1 a cast of the shell itself1 the original matter of which has been removed4 ,these different forms of fossilization may easily be understood if we examine the mud recently thrown out from a pond or canal in which there are shells4 ,if the mud be argillaceous1 it acquires consistency on drying1 and on breaking open a portion of it we find that each shell has left impressions of its external form4 ,if we then remove the shell itself1 we find within a solid nucleus of clay1 having the form of the interior of the shell4 ,this form is often very different from that of the outer shell4 ,thus a cast such as a1 fig4 #eh41 commonly called a fossil screw1 would never be suspected by an inexperienced conchologist to be the internal shape of the fossil univalve1 b1 fig4 #eh4 ,nor should we have imagined at first sight that the shell a and the cast b1 fig4 #ei41 were different parts of the same fossil4 ,the reader will observe1 in the last-mentioned figure 7b1 fig4 #ei471 that an empty space shaded dark1 which the shell itself once occupied1 now intervenes between the enveloping stone and the cast of the smooth interior of the whorls4 ,in such cases the shell has been dissolved and the component particles removed by water percolating the rock4 ,if the nucleus were taken out a hollow mould would remain1 on which the external form of the shell with its tubercles and striae1 as seen in a1 fig4 #ei41 would be seen embossed4 ,now if the space alluded to between the nucleus and the impression1 instead of being left empty1 has been filled up with calcareous spar1 flint1 pyrites1 or other mineral1 we then obtain from the mould an exact cast both of the external and internal form of the original shell4 ,in this manner silicified casts of shells have been formed2 and if the mud or sand of the nucleus happen to be incoherent1 or soluble in acid1 we can then procure in flint an empty shell1 which in shape is the exact counterpart of the original4 ,this cast may be compared to a bronze statue1 representing merely the superficial form1 and not the internal organization2 but there is another description of petrifaction by no means uncommon1 and of a much more wonderful kind1 which may be compared to certain anatomical models in wax1 where not only the outward forms and features1 but the nerves1 blood-vessels1 and other internal organs are also shown4 ,thus we find corals1 originally calcareous1 in which not only the general shape1 but also the minute and complicated internal organization are retained in flint4 ,illustration3 ,fig4 #eh4 ,phasianella ,heddingtonensis1 and cast of the same4 ,coral ,rag4 ,illustration3 ,fig4 #ei4 ,trochus ,anglicus and cast4 ,lias4 ,such a process of petrifaction is still more remarkably exhibited in fossil wood1 in which we often perceive not only the rings of annual growth1 but all the minute vessels and medullary rays4 ,many of the minute pores and fibres of plants1 and even those spiral vessels which in the living vegetable can only be discovered by the microscope1 are preserved4 ,among many instances1 ,i may mention a fossil tree1 #gb feet in length1 found at ,gosforth near ,newcastle1 in sandstone strata associated with coal4 ,by cutting a transverse slice so thin as to transmit light1 and magnifying it about fifty-five times1 the texture seen in fig4 #fj4 is exhibited4 ,a texture equally minute and complicated has been observed in the wood of large trunks of fossil trees found in the ,craigleith quarry near ,edinburgh1 where the stone was not in the slightest degree siliceous1 but consisted chiefly of carbonate of lime1 with oxide of iron1 alumina1 and carbon4 ,the parallel rows of vessels here seen are the rings of annual growth1 but in one part they are imperfectly preserved1 the wood having probably decayed before the mineralizing matter had penetrated to that portion of the tree4 ,illustration3 ,fig4 #fj4 ,texture of a tree from the coal strata1 magnified4 7,witham47 ,transverse section4 ,in attempting to explain the process of petrifaction in such cases1 we may first assume that strata are very generally permeated by water charged with minute portions of calcareous1 siliceous1 and other earths in solution4 ,in what manner they become so impregnated will be afterwards considered4 ,if an organic substance is exposed in the open air to the action of the sun and rain1 it will in time putrefy1 or be dissolved into its component elements1 which consist chiefly of oxygen1 hydrogen1 and carbon4 ,these will readily be absorbed by the atmosphere or be washed away by rain1 so that all vestiges of the dead animal or plant disappear4 ,but if the same substances be submerged in water1 they decompose more gradually2 and if buried in earth1 still more slowly1 as in the familiar example of wooden piles or other buried timber4 ,now1 if as fast as each particle is set free by putrefaction in a fluid or gaseous state1 a particle equally minute of carbonate of lime1 flint1 or other mineral1 is at hand and ready to be precipitated1 we may imagine this inorganic matter to take the place just before left unoccupied by the organic molecule4 ,in this manner a cast of the interior of certain vessels may first be taken1 and afterwards the more solid walls of the same may decay and suffer a like transmutation4 ,yet when the whole is lapidified1 it may not form one homogeneous mass of stone or metal4 ,some of the original ligneous1 osseous1 or other organic elements may remain mingled in certain parts1 or the lapidifying substance itself may be differently coloured at different times1 or so crystallized as to reflect light differently1 and thus the texture of the original body may be faithfully exhibited4 ,the student may perhaps ask whether1 on chemical principles1 we have any ground to expect that mineral matter will be thrown down precisely in those spots where organic decomposition is in progress8 ,the following curious experiments may serve to illustrate this point4 ,professor ,goeppert of ,breslau attempted recently to imitate the natural process of petrifaction4 ,for this purpose he steeped a variety of animal and vegetable substances in waters1 some holding siliceous1 others calcareous1 others metallic matter in solution4 ,he found that in the period of a few weeks1 or even days1 the organic bodies thus immersed were mineralized to a certain extent4 ,thus1 for example1 thin vertical slices of deal1 taken from the ,scotch fir 7,pinus sylvestris71 were immersed in a moderately strong solution of sulphate of iron4 ,when they had been thoroughly soaked in the liquid for several days they were dried and exposed to a red-heat until the vegetable matter was burnt up and nothing remained but an oxide of iron1 which was found to have taken the form of the deal so exactly that casts even of the dotted vessels peculiar to this family of plants were distinctly visible under the microscope4 ,another accidental experiment has been recorded by ,mr4 ,pepys in the ,geological ,transactions4#da-;,a ,an earthen pitcher containing several quarts of sulphate of iron had remained undisturbed and unnoticed for about a twelvemonth in the laboratory4 ,at the end of this time when the liquor was examined an oily appearance was observed on the surface1 and a yellowish powder1 which proved to be sulphur1 together with a quantity of small hairs4 ,at the bottom were discovered the bones of several mice in a sediment consisting of small grains of pyrites1 others of sulphur1 others of crystallized green sulphate of iron1 and a black muddy oxide of iron4 ,it was evident that some mice had accidentally been drowned in the fluid1 and by the mutual action of the animal matter and the sulphate of iron on each other1 the metallic sulphate had been deprived of its oxygen2 hence the pyrites and the other compounds were thrown down4 ,although the mice were not mineralized1 or turned into pyrites1 the phenomenon shows how mineral waters1 charged with sulphate of iron1 may be deoxydated on coming in contact with animal matter undergoing putrefaction1 so that atom after atom of pyrites may be precipitated1 and ready1 under favourable circumstances1 to replace the oxygen1 hydrogen1 and carbon into which the original body would be resolved4 ,the late ,dr4 ,turner observes1 that when mineral matter is in a nascent state1 that is to say1 just liberated from a previous state of chemical combination1 it is most ready to unite with other matter1 and form a new chemical compound4 ,probably the particles or atoms just set free are of extreme minuteness1 and therefore move more freely1 and are more ready to obey any impulse of chemical affinity4 ,whatever be the cause1 it clearly follows1 as before stated1 that where organic matter newly imbedded in sediment is decomposing1 there will chemical changes take place most actively4 ,an analysis was lately made of the water which was flowing off from the rich mud deposited by the ,hooghly river in the ,delta of the ,ganges after the annual inundation4 ,this water was found to be highly charged with carbonic acid gas holding lime in solution4#da-;,b ,now if newly-deposited mud is thus proved to be permeated by mineral matter in a state of solution1 it is not difficult to perceive that decomposing organic bodies1 naturally imbedded in sediment1 may as readily become petrified as the substances artificially immersed by ,professor ,goeppert in various fluid mixtures4 ,it is well known that the water of springs1 or that which is continually percolating the earth's crust1 is rarely free from a slight admixture either of iron1 carbonate of lime1 sulphur1 silica1 potash1 or some other earthy1 alkaline1 or metallic ingredient4 ,hot springs in particular are copiously charged with one or more of these elements2 and it is only in their waters that silex is found in abundance4 ,in certain cases1 therefore1 especially in volcanic regions1 we may imagine the flint of silicified wood and corals to have been supplied by the waters of thermal springs4 ,in other instances1 as in tripoli and chalk-flint1 it may have been derived in great part1 if not wholly1 from the decomposition of infusoria or diatomaceae1 sponges1 and other bodies4 ,but even if this be granted1 we have still to inquire whence a lake or the ocean can be constantly replenished with the calcareous and siliceous matter so abundantly withdrawn from it by the secretions of these zoophytes4 ,in regard to carbonate of lime there is no difficulty1 because not only are calcareous springs very numerous1 but even rain-water has the power of dissolving a minute portion of the calcareous rocks over which it flows4 ,hence marine corals and mollusca may be provided by rivers with the materials of their shells and solid supports4 ,but pure silex1 even when reduced to the finest powder and boiled1 is insoluble in water1 except at very high temperatures4 ,nevertheless ,dr4 ,turner has well explained1 in an essay on the chemistry of geology#db-;,a1 how the decomposition of felspar may be a source of silex in solution4 ,he has remarked that the siliceous earth1 which constitutes more than half the bulk of felspar1 is intimately combined with alumine1 potash1 and some other elements4 ,the alkaline matter of the felspar has a chemical affinity for water1 as also for the carbonic acid which is more or less contained in the waters of most springs4 ,the water therefore carries away alkaline matter1 and leaves behind a clay consisting of alumine and silica4 ,but this residue of the decomposed mineral1 which in its purest state is called porcelain clay1 is found to contain a part only of the silica which existed in the original felspar4 ,the other part1 therefore1 must have been dissolved and removed2 and this can be accounted for in two ways2 first1 because silica when combined with an alkali is soluble in water2 secondly1 because silica in what is technically called its nascent state is also soluble in water4 ,hence an endless supply of silica is afforded to rivers and the waters of the sea4 ,for the felspathic rocks are universally distributed1 constituting1 as they do1 so large a proportion of the volcanic1 plutonic1 and metamorphic formations4 ,even where they chance to be absent in mass1 they rarely fail to occur in the superficial gravel or alluvial deposits of the basin of every large river4 ,the disintegration of mica also1 another mineral which enters largely into the composition of granite and various sandstones1 may yield silica which may be dissolved in water1 for nearly half of this mineral consists of silica1 combined with alumine1 potash1 and about a tenth part of iron4 ,the oxidation of this iron in the air is the principal cause of the waste of mica4 ,we have still1 however1 much to learn before the conversion of fossil bodies into stone is fully understood4 ,some phenomena seem to imply that the mineralization must proceed with considerable rapidity1 for stems of a soft and succulent character1 and of a most perishable nature1 are preserved in flint2 and there are instances of the complete silicification of the young leaves of a palm-tree when just about to shoot forth1 and in that state which in the ,west ,indies is called the cabbage of the palm4#dc-;,a ,it may1 however1 be questioned whether in such cases there may not have been some antiseptic quality in the water which retarded putrefaction1 so that the soft parts of the buried substance may have remained for a long time without disintegration1 like the flesh of bodies imbedded in peat4 ,mr4 ,stokes has pointed out examples of petrifactions in which the more perishable1 and others where the more durable portions of wood are preserved4 ,these variations1 he suggests1 must doubtless have depended on the time when the lapidifying mineral was introduced4 ,thus1 in certain silicified stems of palm-trees1 the cellular tissue1 that most destructible part1 is in good condition1 while all signs of the hard woody fibre have disappeared1 the spaces once occupied by it being hollow or filled with agate4 ,here1 petrifaction must have commenced soon after the wood was exposed to the action of moisture1 and the supply of mineral matter must then have failed1 or the water must have become too much diluted before the woody fibre decayed4 ,but when this fibre is alone discoverable1 we must suppose that an interval of time elapsed before the commencement of lapidification1 during which the cellular tissue was obliterated4 ,when both structures1 namely1 the cellular and the woody fibre1 are preserved1 the process must have commenced at an early period1 and continued without interruption till it was completed throughout4#dc-;,b ,,footnotes3 #cd-;,a ,see ,principles1 ,index1 ,calcareous ,springs1 c4 #cd-;,b ,ibid4 ,travertin1 ,coral ,reefs1 c4 #ce-;,a ,report ,brit4 ,ass4 #ahdc1 p4 #agh4 #cf-;,a ,dr4 ,mac,culloch1 ,syst4 of ,geol4 vol4 i4 p4 #abc4 #cf-;,b ,princ4 of ,geol41 ,index1 ,superior ,lake4 #cg-;,a ,de la ,beche1 ,geol4 ,researches1 p4 #ie41 and ,geol4 ,observer 7#ahea71 p4 #fhf4 #da-;,a ,vol4 i4 p4 #cii4 first series4 #da-;,b ,piddington1 ,asiat4 ,research4 vol4 xviii4 p4 #bbf4 #db-;,a ,jam4 ,ed4 ,new ,phil4 ,journ4 ,no4 #cj4 p4 #bdf4 #dc-;,a ,stokes1 ,geol4 ,trans41 vol4 v4 p4 #bab4 second series4 #dc-;,b ,ibid4 ,,chapter ,v4 ,,elevation ,,of ,,strata ,,above ,,the ,,sea--,,horizontal ,,and ,,inclined ,,stratification4 ,why the position of marine strata1 above the level of the sea1 should be referred to the rising up of the land1 not to the going down of the sea--,upheaval of extensive masses of horizontal strata--,inclined and vertical stratification--,anticlinal and synclinal lines--,bent strata in east of ,scotland--,theory of folding by lateral movement--,creeps--,dip and strike--,structure of the ,jura--,various forms of outcrop--,rocks broken by flexure--,inverted position of disturbed strata--,unconformable stratification--,hutton and ,playfair on the same--,fractures of strata--,polished surfaces--,faults--,appearance of repeated alternations produced by them--,origin of great faults4 ,land has been raised1 not the sea lowered4--,it has been already stated that the aqueous rocks containing marine fossils extend over wide continental tracts1 and are seen in mountain chains rising to great heights above the level of the sea4 ,hence it follows1 that what is now dry land was once under water4 ,but if we admit this conclusion1 we must imagine1 either that there has been a general lowering of the waters of the ocean1 or that the solid rocks1 once covered by water1 have been raised up bodily out of the sea1 and have thus become dry land4 ,the earlier geologists1 finding themselves reduced to this alternative1 embraced the former opinion1 assuming that the ocean was originally universal1 and had gradually sunk down to its actual level1 so that the present islands and continents were left dry4 ,it seemed to them far easier to conceive that the water had gone down1 than that solid land had risen upwards into its present position4 ,it was1 however1 impossible to invent any satisfactory hypothesis to explain the disappearance of so enormous a body of water throughout the globe1 it being necessary to infer that the ocean had once stood at whatever height marine shells might be detected4 ,it moreover appeared clear1 as the science of ,geology advanced1 that certain spaces on the globe had been alternately sea1 then land1 then estuary1 then sea again1 and1 lastly1 once more habitable land1 having remained in each of these states for considerable periods4 ,in order to account for such phenomena1 without admitting any movement of the land itself1 we are required to imagine several retreats and returns of the ocean2 and even then our theory applies merely to cases where the marine strata composing the dry land are horizontal1 leaving unexplained those more common instances where strata are inclined1 curved1 or placed on their edges1 and evidently not in the position in which they were first deposited4 ,geologists1 therefore1 were at last compelled to have recourse to the other alternative1 namely1 the doctrine that the solid land has been repeatedly moved upwards or downwards1 so as permanently to change its position relatively to the sea4 ,there are several distinct grounds for preferring this conclusion4 ,first1 it will account equally for the position of those elevated masses of marine origin in which the stratification remains horizontal1 and for those in which the strata are disturbed1 broken1 inclined1 or vertical4 ,secondly1 it is consistent with human experience that land should rise gradually in some places and be depressed in others4 ,such changes have actually occurred in our own days1 and are now in progress1 having been accompanied in some cases by violent convulsions1 while in others they have proceeded so insensibly1 as to have been ascertainable only by the most careful scientific observations1 made at considerable intervals of time4 ,on the other hand1 there is no evidence from human experience of a lowering of the sea's level in any region1 and the ocean cannot sink in one place without its level being depressed all over the globe4 ,these preliminary remarks will prepare the reader to understand the great theoretical interest attached to all facts connected with the position of strata1 whether horizontal or inclined1 curved or vertical4 ,now the first and most simple appearance is where strata of marine origin occur above the level of the sea in horizontal position4 ,such are the strata which we meet with in the south of ,sicily1 filled with shells for the most part of the same species as those now living in the ,mediterranean4 ,some of these rocks rise to the height of more than #bjjj feet above the sea4 ,other mountain masses might be mentioned1 composed of horizontal strata of high antiquity1 which contain fossil remains of animals wholly dissimilar from any now known to exist4 ,in the south of ,sweden1 for example1 near ,lake ,wener1 the beds of one of the oldest of the fossiliferous deposits1 namely that formerly called ,transition1 and now ,silurian1 by geologists1 occur in as level a position as if they had recently formed part of the delta of a great river1 and been left dry on the retiring of the annual floods4 ,aqueous rocks of about the same age extend for hundreds of miles over the lake-district of ,north ,america1 and exhibit in like manner a stratification nearly undisturbed4 ,the ,table ,mountain at the ,cape of ,good ,hope is another example of highly elevated yet perfectly horizontal strata1 no less than #cejj feet in thickness1 and consisting of sandstone of very ancient date4 ,instead of imagining that such fossiliferous rocks were always at their present level1 and that the sea was once high enough to cover them1 we suppose them to have constituted the ancient bed of the ocean1 and that they were gradually uplifted to their present height4 ,this idea1 however startling it may at first appear1 is quite in accordance1 as before stated1 with the analogy of changes now going on in certain regions of the globe4 ,thus1 in parts of ,sweden1 and the shores and islands of the ,gulf of ,bothnia1 proofs have been obtained that the land is experiencing1 and has experienced for centuries1 a slow upheaving movement4 ,playfair argued in favour of this opinion in #ahjb2 and in #ahjg1 ,von ,buch1 after his travels in ,scandinavia1 announced his conviction that a rising of the land was in progress4 ,celsius and other ,swedish writers had1 a century before1 declared their belief that a gradual change had1 for ages1 been taking place in the relative level of land and sea4 ,they attributed the change to a fall of the waters both of the ocean and the ,baltic4 ,this theory1 however1 has now been refuted by abundant evidence2 for the alteration of relative level has neither been universal nor every where uniform in quantity1 but has amounted1 in some regions1 to several feet in a century1 in others to a few inches2 while in the southernmost part of ,sweden1 or the province of ,scania1 there has been actually a loss instead of a gain of land1 buildings having gradually sunk below the level of the sea4#df-;,a ,it appears1 from the observations of ,mr4 ,darwin and others1 that very extensive regions of the continent of ,south ,america have been undergoing slow and gradual upheaval1 by which the level plains of ,patagonia1 covered with recent marine shells1 and the ,pampas of ,buenos ,ayres1 have been raised above the level of the sea4#df-;,b ,on the other hand1 the gradual sinking of the west coast of ,greenland1 for the space of more than #fjj miles from north to south1 during the last four centuries1 has been established by the observations of a ,danish naturalist1 ,dr4 ,pingel4 ,and while these proofs of continental elevation and subsidence1 by slow and insensible movements1 have been recently brought to light1 the evidence has been daily strengthened of continued changes of level effected by violent convulsions in countries where earthquakes are frequent4 ,there the rocks are rent from time to time1 and heaved up or thrown down several feet at once1 and disturbed in such a manner1 that the original position of strata may1 in the course of centuries1 be modified to any amount4 ,it has also been shown by ,mr4 ,darwin1 that1 in those seas where circular coral islands and barrier reefs abound1 there is a slow and continued sinking of the submarine mountains on which the masses of coral are based2 while there are other areas of the ,south ,sea1 where the land is on the rise1 and where coral has been upheaved far above the sea-level4 ,it would require a volume to explain to the reader the various facts which establish the reality of these movements of land1 whether of elevation or depression1 whether accompanied by earthquakes or accomplished slowly and without local disturbance4 ,having treated fully of these subjects in the ,principles of ,geology#df-;,c1 ,i shall assume1 in the present work1 that such changes are part of the actual course of nature2 and when admitted1 they will be found to afford a key to the interpretation of a variety of geological appearances1 such as the elevation of horizontal1 inclined1 or disturbed marine strata1 and the superposition of freshwater to marine deposits1 afterwards to be described4 ,it will also appear1 in the sequel1 how much light the doctrine of a continued subsidence of land may throw on the manner in which a series of strata1 formed in shallow water1 may have accumulated to a great thickness4 ,the excavation of valleys also1 and other effects of denudation1 of which ,i shall presently treat1 can alone be understood when we duly appreciate the proofs1 now on record1 of the prolonged rising and sinking of land1 throughout wide areas4 ,to conclude this subject1 ,i may remind the reader1 that were we to embrace the doctrine which ascribes the elevated position of marine formations1 and the depression of certain freshwater strata1 to oscillations in the level of the waters instead of the land1 we should be compelled to admit that the ocean has been sometimes every where much shallower than at present1 and at others more than three miles deeper4 ,illustration3 ,fig4 #fa4 ,vertical conglomerate and sandstone4 ,inclined stratification4--,the most unequivocal evidence of a change in the original position of strata is afforded by their standing up perpendicularly on their edges1 which is by no means a rare phenomenon1 especially in mountainous countries4 ,thus we find in ,scotland1 on the southern skirts of the ,grampians1 beds of pudding-stone alternating with thin layers of fine sand1 all placed vertically to the horizon4 ,when ,saussure first observed certain conglomerates in a similar position in the ,swiss ,alps1 he remarked that the pebbles1 being for the most part of an oval shape1 had their longer axes parallel to the planes of stratification 7,see fig4 #fa474 ,from this he inferred1 that such strata must1 at first1 have been horizontal1 each oval pebble having originally settled at the bottom of the water1 with its flatter side parallel to the horizon1 for the same reason that an egg will not stand on either end if unsupported4 ,some few1 indeed1 of the rounded stones in a conglomerate occasionally afford an exception to the above rule1 for the same reason that we see on a shingle beach some oval or flat-sided pebbles resting on their ends or edges2 these having been forced along the bottom and against each other by a wave or current so as to settle in this position4 ,vertical strata1 when they can be traced continuously upwards or downwards for some depth1 are almost invariably seen to be parts of great curves1 which may have a diameter of a few yards1 or of several miles4 ,i shall first describe two curves of considerable regularity1 which occur in ,forfarshire1 extending over a country twenty miles in breadth1 from the foot of the ,grampians to the sea near ,arbroath4 ,the mass of strata here shown may be nearly #bjjj feet in thickness1 consisting of red and white sandstone1 and various coloured shales1 the beds being distinguishable into four principal groups1 namely1 ,no4 #a4 red marl or shale2 ,no4 #b4 red sandstone1 used for building2 ,no4 #c4 conglomerate2 and ,no4 #d4 grey paving-stone1 and tile-stone1 with green and reddish shale1 containing peculiar organic remains4 ,a glance at the section will show that each of the formations #b1 #c1 #d1 are repeated thrice at the surface1 twice with a southerly1 and once with a northerly inclination or dip1 and the beds in ,no4 #a41 which are nearly horizontal1 are still brought up twice by a slight curvature to the surface1 once on each side of ,a4 ,beginning at the north-west extremity1 the tile-stones and conglomerates ,no4 #d4 and ,no4 #c4 are vertical1 and they generally form a ridge parallel to the southern skirts of the ,grampians4 ,the superior strata ,nos4 #b4 and #a4 become less and less inclined on descending to the valley of ,strathmore1 where the strata1 having a concave bend1 are said by geologists to lie in a trough or basin4 ,through the centre of this valley runs an imaginary line ,a1 called technically a synclinal line1 where the beds1 which are tilted in opposite directions1 may be supposed to meet4 ,it is most important for the observer to mark such lines1 for he will perceive by the diagram1 that in travelling from the north to the centre of the basin1 he is always passing from older to newer beds2 whereas1 after crossing the line ,a1 and pursuing his course in the same southerly direction1 he is continually leaving the newer1 and advancing upon older strata4 ,all the deposits which he had before examined begin then to recur in reversed order1 until he arrives at the central axis of the ,sidlaw hills1 where the strata are seen to form an arch or saddle1 having an anticlinal line ,b1 in the centre4 ,on passing this line1 and continuing towards the ,s4,e41 the formations #d1 #c1 and #b1 are again repeated1 in the same relative order of superposition1 but with a northerly dip4 ,at ,whiteness 7see diagram7 it will be seen that the inclined strata are covered by a newer deposit1 a1 in horizontal beds4 ,these are composed of red conglomerate and sand1 and are newer than any of the groups1 #a1 #b1 #c1 #d1 before described1 and rest unconformably upon strata of the sandstone group1 ,no4 #b4 ,illustration3 ,fig4 #fb4 ,section of ,forfarshire1 from ,n4,w4 to ,s4,e41 from foot of the ,grampians to the sea at ,arbroath 7volcanic or trap rocks omitted74 ,length of section twenty miles4 ,an example of curved strata1 in which the bends or convolutions of the rock are sharper and far more numerous within an equal space1 has been well described by ,sir ,james ,hall4#dh-;,a ,it occurs near ,st4 ,abb's ,head1 on the east coast of ,scotland1 where the rocks consist principally of a bluish slate1 having frequently a ripple-marked surface4 ,the undulations of the beds reach from the top to the bottom of cliffs from #bjj to #cjj feet in height1 and there are sixteen distinct bendings in the course of about six miles1 the curvatures being alternately concave and convex upwards4 ,illustration3 ,fig4 #fc4 ,curved strata of slate near ,st4 ,abb's ,head1 ,berwickshire4 7,sir ,j4 ,hall47 ,illustration3 ,fig4 #fd4 ,block section4 ,an experiment was made by ,sir ,james ,hall1 with a view of illustrating the manner in which such strata1 assuming them to have been originally horizontal1 may have been forced into their present position4 ,a set of layers of clay were placed under a weight1 and their opposite ends pressed towards each other with such force as to cause them to approach more nearly together4 ,on the removal of the weight1 the layers of clay were found to be curved and folded1 so as to bear a miniature resemblance to the strata in the cliffs4 ,we must1 however1 bear in mind1 that in the natural section or sea-cliff we only see the foldings imperfectly1 one part being invisible beneath the sea1 and the other1 or upper portion1 being supposed to have been carried away by denudation1 or that action of water which will be explained in the next chapter4 ,the dark lines in the accompanying plan 7fig4 #fd47 represent what is actually seen of the strata in part of the line of cliff alluded to2 the fainter lines1 that portion which is concealed beneath the sea level1 as also that which is supposed to have once existed above the present surface4 ,illustration3 ,fig4 #fe4 ,experimental set-up4 ,we may still more easily illustrate the effects which a lateral thrust might produce on flexible strata1 by placing several pieces of differently coloured cloths upon a table1 and when they are spread out horizontally1 cover them with a book4 ,then apply other books to each end1 and force them towards each other4 ,the folding of the cloths will exactly imitate those of the bent strata4 7,see fig4 #fe47 ,whether the analogous flexures in stratified rocks have really been due to similar sideway movements is a question of considerable difficulty4 ,it will appear when the volcanic and granitic rocks are described1 that some of them have1 when melted1 been injected forcibly into fissures1 while others1 already in a solid state1 have been protruded upwards through the incumbent crust of the earth1 by which a great displacement of flexible strata must have been caused4 ,but we also know by the study of regions liable to earthquakes1 that there are causes at work in the interior of the earth capable of producing a sinking in of the ground1 sometimes very local1 but sometimes extending over a wide area4 ,the frequent repetition1 or continuance throughout long periods1 of such downward movements seems to imply the formation and renewal of cavities at a certain depth below the surface1 whether by the removal of matter by volcanos and hot springs1 or by the contraction of argillaceous rocks by heat and pressure1 or any other combination of circumstances4 ,whatever conjectures we may indulge respecting the causes1 it is certain that pliable beds may1 in consequence of unequal degrees of subsidence1 become folded to any amount1 and have all the appearance of having been compressed suddenly by a lateral thrust4 ,the ,creeps1 as they are called in coal-mines1 afford an excellent illustration of this fact4--,first1 it may be stated generally1 that the excavation of coal at a considerable depth causes the mass of overlying strata to sink down bodily1 even when props are left to support the roof of the mine4 ,in ,yorkshire1 says ,mr4 ,buddle1 three distinct subsidences were perceptible at the surface1 after the clearing out of three seams of coal below1 and innumerable vertical cracks were caused in the incumbent mass of sandstone and shale1 which thus settled down4#ej-;,a ,the exact amount of depression in these cases can only be accurately measured where water accumulates on the surface1 or a railway traverses a coal-field4 ,illustration3 ,fig4 #ff4 ,section of carboniferous strata1 at ,wallsend1 ,newcastle1 showing ,creeps4 7,j4 ,buddle1 ,esq47 ,horizontal length of section #agd feet4 ,the upper seam1 or main coal1 here worked out1 was #fcj feet below the surface4 ,when a bed of coal is worked out1 pillars or rectangular masses of coal are left at intervals as props to support the roof1 and protect the colliers4 ,thus in fig4 #ff41 representing a section at ,wallsend1 ,newcastle1 the galleries which have been excavated are represented by the white spaces a b1 while the adjoining dark portions are parts of the original coal-seam left as props1 beds of sandy clay or shale constituting the floor of the mine4 ,when the props have been reduced in size1 they are pressed down by the weight of overlying rocks 7no less than #fcj feet thick7 upon the shale below1 which is thereby squeezed and forced up into the open spaces4 ,now it might have been expected1 that instead of the floor rising up1 the ceiling would sink down1 and this effect1 called a ,thrust1 does1 in fact1 take place where the pavement is more solid than the roof4 ,but it usually happens1 in coal-mines1 that the roof is composed of hard shale1 or occasionally of sandstone1 more unyielding than the foundation1 which often consists of clay4 ,even where the argillaceous substrata are hard at first1 they soon become softened and reduced to a plastic state when exposed to the contact of air and water in the floor of a mine4 ,the first symptom of a creep1 says ,mr4 ,buddle1 is a slight curvature at the bottom of each gallery1 as at a1 fig4 #ff43 then the pavement continuing to rise1 begins to open with a longitudinal crack1 as at b3 then the points of the fractured ridge reach the roof1 as at c2 and1 lastly1 the upraised beds close up the whole gallery1 and the broken portions of the ridge are re-united and flattened at the top1 exhibiting the flexure seen at d4 ,meanwhile the coal in the props has become crushed and cracked by pressure4 ,it is also found1 that below the creeps a1 b1 c1 d1 an inferior stratum1 called the metal coal1 which is #c feet thick1 has been fractured at the points e1 f1 g1 h1 and has risen1 so as to prove that the upward movement1 caused by the working out of the main coal1 has been propagated through a thickness of #ed feet of argillaceous beds1 which intervene between the two coal seams4 ,this same displacement has also been traced downwards more than #aej feet below the metal coal1 but it grows continually less and less until it becomes imperceptible4 ,no part of the process above described is more deserving of our notice than the slowness with which the change in the arrangement of the beds is brought about4 ,days1 months1 or even years1 will sometimes elapse between the first bending of the pavement and the time of its reaching the roof4 ,where the movement has been most rapid1 the curvature of the beds is most regular1 and the reunion of the fractured ends most complete2 whereas the signs of displacement or violence are greatest in those creeps which have required months or years for their entire accomplishment4 ,hence we may conclude that similar changes may have been wrought on a larger scale in the earth's crust by partial and gradual subsidences1 especially where the ground has been undermined throughout long periods of time2 and we must be on our guard against inferring sudden violence1 simply because the distortion of the beds is excessive4 ,between the layers of shale1 accompanying coal1 we sometimes see the leaves of fossil ferns spread out as regularly as dried plants between sheets of paper in the herbarium of a botanist4 ,these fern-leaves1 or fronds1 must have rested horizontally on soft mud1 when first deposited4 ,if1 therefore1 they and the layers of shale are now inclined1 or standing on end1 it is obviously the effect of subsequent derangement4 ,the proof becomes1 if possible1 still more striking when these strata1 including vegetable remains1 are curved again and again1 and even folded into the form of the letter ,z1 so that the same continuous layer of coal is cut through several times in the same perpendicular shaft4 ,thus1 in the coal-field near ,mons1 in ,belgium1 these zigzag bendings are repeated four or five times1 in the manner represented in fig4 #fg41 the black lines representing seams of coal4#ec-;,a ,illustration3 ,fig4 #fg4 ,zigzag flexures of coal near ,mons4 ,dip and ,strike4--,in the above remarks1 several technical terms have been used1 such as dip1 the unconformable position of strata1 and the anticlinal and synclinal lines1 which1 as well as the strike of the beds1 ,i shall now explain4 ,if a stratum or bed of rock1 instead of being quite level1 be inclined to one side1 it is said to dip2 the point of the compass to which it is inclined is called the point of dip1 and the degree of deviation from a level or horizontal line is called the amount of dip1 or the angle of dip4 ,thus1 in the annexed diagram 7fig4 #fh471 a series of strata are inclined1 and they dip to the north at an angle of forty-five degrees4 ,the strike1 or line of bearing1 is the prolongation or extension of the strata in a direction at right angles to the dip2 and hence it is sometimes called the direction of the strata4 ,thus1 in the above instance of strata dipping to the north1 their strike must necessarily be east and west4 ,we have borrowed the word from the ,german geologists1 streichen signifying to extend1 to have a certain direction4 ,dip and strike may be aptly illustrated by a row of houses running east and west1 the long ridge of the roof representing the strike of the stratum of slates1 which dip on one side to the north1 and on the other to the south4 ,illustration3 ,fig4 #fh4 ,diagram4 ,a stratum which is horizontal1 or quite level in all directions1 has neither dip nor strike4 ,it is always important for the geologist1 who is endeavouring to comprehend the structure of a country1 to learn how the beds dip in every part of the district2 but it requires some practice to avoid being occasionally deceived1 both as to the point of dip and the amount of it4 ,illustration3 ,fig4 #fi4 ,apparent horizontality of inclined strata4 ,if the upper surface of a hard stony stratum be uncovered1 whether artificially in a quarry1 or by the waves at the foot of a cliff1 it is easy to determine towards what point of the compass the slope is steepest1 or in what direction water would flow1 if poured upon it4 ,this is the true dip4 ,but the edges of highly inclined strata may give rise to perfectly horizontal lines in the face of a vertical cliff1 if the observer see the strata in the line of their strike1 the dip being inwards from the face of the cliff4 ,if1 however1 we come to a break in the cliff1 which exhibits a section exactly at right angles to the line of the strike1 we are then able to ascertain the true dip4 ,in the annexed drawing 7fig4 #fi471 we may suppose a headland1 one side of which faces to the north1 where the beds would appear perfectly horizontal to a person in the boat2 while in the other side facing the west1 the true dip would be seen by the person on shore to be at an angle of #dj deg44 ,if1 therefore1 our observations are confined to a vertical precipice facing in one direction1 we must endeavour to find a ledge or portion of the plane of one of the beds projecting beyond the others1 in order to ascertain the true dip4 ,illustration3 ,fig4 #gj4 ,explanatory sketch4 ,it is rarely important to determine the angle of inclination with such minuteness as to require the aid of the instrument called a clinometer4 ,we may measure the angle within a few degrees by standing exactly opposite to a cliff where the true dip is exhibited1 holding the hands immediately before the eyes1 and placing the fingers of one in a perpendicular1 and of the other in a horizontal position1 as in fig4 #gj4 ,it is thus easy to discover whether the lines of the inclined beds bisect the angle of #ij deg41 formed by the meeting of the hands1 so as to give an angle of #de deg41 or whether it would divide the space into two equal or unequal portions4 ,the upper dotted line may express a stratum dipping to the north2 but should the beds dip precisely to the opposite point of the compass as in the lower dotted line1 it will be seen that the amount of inclination may still be measured by the hands with equal facility4 ,illustration3 ,fig4 #ga4 ,section illustrating the structure of the ,swiss ,jura4 ,illustration3 ,fig4 #gb4 ,ground plan of the denuded ridge1 fig4 #ga4 ,illustration3 ,fig4 #gc4 ,transverse section4 ,it has been already seen1 in describing the curved strata on the east coast of ,scotland1 in ,forfarshire and ,berwickshire1 that a series of concave and convex bendings are occasionally repeated several times4 ,these usually form part of a series of parallel waves of strata1 which are prolonged in the same direction throughout a considerable extent of country4 ,thus1 for example1 in the ,swiss ,jura1 that lofty chain of mountains has been proved to consist of many parallel ridges1 with intervening longitudinal valleys1 as in fig4 #ga41 the ridges being formed by curved fossiliferous strata1 of which the nature and dip are occasionally displayed in deep transverse gorges1 called cluses1 caused by fractures at right angles to the direction of the chain4#ee-;,a ,now let us suppose these ridges and parallel valleys to run north and south1 we should then say that the strike of the beds is north and south1 and the dip east and west4 ,lines drawn along the summits of the ridges1 ,a1 ,b1 would be anticlinal lines1 and one following the bottom of the adjoining valleys a synclinal line4 ,it will be observed that some of these ridges1 ,a1 ,b1 are unbroken on the summit1 whereas one of them1 ,c1 has been fractured along the line of strike1 and a portion of it carried away by denudation1 so that the ridges of the beds in the formations a1 b1 c1 come out to the day1 or1 as the miners say1 crop out1 on the sides of a valley4 ,the ground plan of such a denuded ridge as ,c1 as given in a geological map1 may be expressed by the diagram fig4 #gb41 and the cross section of the same by fig4 #gc4 ,the line ,d ,e1 fig4 #gb41 is the anticlinal line1 on each side of which the dip is in opposite directions1 as expressed by the arrows4 ,the emergence of strata at the surface is called by miners their outcrop or basset4 ,if1 instead of being folded into parallel ridges1 the beds form a boss or dome-shaped protuberance1 and if we suppose the summit of the dome carried off1 the ground plan would exhibit the edges of the strata forming a succession of circles1 or ellipses1 round a common centre4 ,these circles are the lines of strike1 and the dip being always at right angles is inclined in the course of the circuit to every point of the compass1 constituting what is termed a qua-quaversal dip--that is1 turning each way4 ,there are endless variations in the figures described by the basset-edges of the strata1 according to the different inclination of the beds1 and the mode in which they happen to have been denuded4 ,one of the simplest rules with which every geologist should be acquainted1 relates to the ,v-like form of the beds as they crop out in an ordinary valley4 ,first1 if the strata be horizontal1 the ,v-like form will be also on a level1 and the newest strata will appear at the greatest heights4 ,secondly1 if the beds be inclined and intersected by a valley sloping in the same direction1 and the dip of the beds be less steep than the slope of the valley1 then the ,v's1 as they are often termed by miners1 will point upwards 7see fig4 #gd471 those formed by the newer beds appearing in a superior position1 and extending highest up the valley1 as ,a is seen above ,b4 ,illustration3 ,fig4 #gd4 ,slope of valley #dj deg41 dip of strata #bj deg44 ,thirdly1 if the dip of the beds be steeper than the slope of the valley1 then the ,v's will point downwards 7see fig4 #ge471 and those formed of the older beds will now appear uppermost1 as ,b appears above ,a4 ,illustration3 ,fig4 #ge4 ,slope of valley #bj deg41 dip of strata #ej deg44 ,fourthly1 in every case where the strata dip in a contrary direction to the slope of the valley1 whatever be the angle of inclination1 the newer beds will appear the highest1 as in the first and second cases4 ,this is shown by the drawing 7fig4 #gf471 which exhibits strata rising at an angle of #bj deg41 and crossed by a valley1 which declines in an opposite direction at #bj deg44#eg-;,a ,illustration3 ,fig4 #gf4 ,slope of valley #bj deg41 dip of strata #bj deg41 in opposite directions4 ,these rules may often be of great practical utility2 for the different degrees of dip occurring in the two cases represented in figures #gd and #ge4 may occasionally be encountered in following the same line of flexure at points a few miles distant from each other4 ,a miner unacquainted with the rule1 who had first explored the valley 7fig4 #gd471 may have sunk a vertical shaft below the coal seam ,a1 until he reached the inferior bed ,b4 ,he might then pass to the valley fig4 #ge41 and discovering there also the outcrop of two coal seams1 might begin his workings in the uppermost in the expectation of coming down to the other bed ,a1 which would be observed cropping out lower down the valley4 ,but a glance at the section will demonstrate the futility of such hopes4 ,in the majority of cases1 an anticlinal axis forms a ridge1 and a synclinal axis a valley1 as in ,a1 ,b1 fig4 #fb4 p4 #dh42 but there are exceptions to this rule1 the beds sometimes sloping inwards from either side of a mountain1 as in fig4 #gg4 ,illustration3 ,fig4 #gg4 ,cross section4 ,on following one of the anticlinal ridges of the ,jura1 before mentioned1 ,a1 ,b1 ,c1 fig4 #ga41 we often discover longitudinal cracks and sometimes large fissures along the line where the flexure was greatest4 ,some of these1 as above stated1 have been enlarged by denudation into valleys of considerable width1 as at ,c1 fig4 #ga41 which follow the line of strike1 and which we may suppose to have been hollowed out at the time when these rocks were still beneath the level of the sea1 or perhaps at the period of their gradual emergence from beneath the waters4 ,the existence of such cracks at the point of the sharpest bending of solid strata of limestone is precisely what we should have expected2 but the occasional want of all similar signs of fracture1 even where the strain has been greatest1 as at a1 fig4 #ga41 is not always easy to explain4 ,we must imagine that many strata of limestone1 chert1 and other rocks which are now brittle1 were pliant when bent into their present position4 ,they may have owed their flexibility in part to the fluid matter which they contained in their minute pores1 as before described 7p4 #ce471 and in part to the permeation of sea-water while they were yet submerged4 ,illustration3 ,fig4 #gh4 ,strata of chert1 grit1 and marl1 near ,st4 ,jean de ,luz4 ,at the western extremity of the ,pyrenees1 great curvatures of the strata are seen in the sea cliffs1 where the rocks consist of marl1 grit1 and chert4 ,at certain points1 as at a1 fig4 #gh41 some of the bendings of the flinty chert are so sharp1 that specimens might be broken off1 well fitted to serve as ridge-tiles on the roof of a house4 ,although this chert could not have been brittle as now1 when first folded into this shape1 it presents1 nevertheless1 here and there at the points of greatest flexure small cracks1 which show that it was solid1 and not wholly incapable of breaking at the period of its displacement4 ,the numerous rents alluded to are not empty1 but filled with calcedony and quartz4 ,illustration3 ,fig4 #gi4 ,cross section4 g4 gypsum4 m4 marl4 ,between ,san ,caterina and ,castrogiovanni1 in ,sicily1 bent and undulating gypseous marls occur1 with here and there thin beds of solid gypsum interstratified4 ,sometimes these solid layers have been broken into detached fragments1 still preserving their sharp edges 7g g1 fig4 #gi471 while the continuity of the more pliable and ductile marls1 m m1 has not been interrupted4 ,illustration3 ,fig4 #hj4 ,cross section4 ,i shall conclude my remarks on bent strata by stating1 that1 in mountainous regions like the ,alps1 it is often difficult for an experienced geologist to determine correctly the relative age of beds by superposition1 so often have the strata been folded back upon themselves1 the upper parts of the curve having been removed by denudation4 ,thus1 if we met with the strata seen in the section fig4 #hj41 we should naturally suppose that there were twelve distinct beds1 or sets of beds1 ,no4 #a4 being the newest1 and ,no4 #ab4 the oldest of the series4 ,but this section may1 perhaps1 exhibit merely six beds1 which have been folded in the manner seen in fig4 #ha41 so that each of them is twice repeated1 the position of one half being reversed1 and part of ,no4 #a41 originally the uppermost1 having now become the lowest of the series4 ,these phenomena are often observable on a magnificent scale in certain regions in ,switzerland in precipices from #bjjj to #cjjj feet in perpendicular height4 ,in the ,iselten ,alp1 in the valley of the ,lutschine1 between ,unterseen and ,grindelwald1 curves of calcareous shale are seen from #ajjj to #aejj feet in height1 in which the beds sometimes plunge down vertically for a depth of #ajjj feet and more1 before they bend round again4 ,there are many flexures not inferior in dimensions in the ,pyrenees1 as those near ,gavarnie1 at the base of ,mont ,perdu4 ,illustration3 ,fig4 #ha4 ,cross section4 ,illustration3 ,fig4 #hb4 ,curved strata of the ,iselten ,alp4 ,illustration3 ,fig4 #hc4 ,unconformable junction of old red sandstone and ,silurian schist at the ,siccar ,point1 near ,st4 ,abb's ,head1 ,berwickshire4 ,see also ,frontispiece4 ,unconformable stratification4--,strata are said to be unconformable1 when one series is so placed over another1 that the planes of the superior repose on the edges of the inferior 7see fig4 #hc474 ,in this case it is evident that a period had elapsed between the production of the two sets of strata1 and that1 during this interval1 the older series had been tilted and disturbed4 ,afterwards the upper series was thrown down in horizontal strata upon it4 ,if these superior beds1 as d1 d1 fig4 #hc41 are also inclined1 it is plain that the lower strata1 a1 a1 have been twice displaced2 first1 before the deposition of the newer beds1 d1 d1 and a second time when these same strata were thrown out of the horizontal position4 ,playfair has remarked#fj-;,a that this kind of junction which we now call unconformable had been described before the time of ,hutton1 but that he was the first geologist who appreciated its importance1 as illustrating the high antiquity and great revolutions of the globe4 ,he had observed that where such contacts occur1 the lowest beds of the newer series very generally consist of a breccia or conglomerate consisting of angular and rounded fragments1 derived from the breaking up of the more ancient rocks4 ,on one occasion the ,scotch geologist took his two distinguished pupils1 ,playfair and ,sir ,james ,hall1 to the cliffs on the east coast of ,scotland1 near the village of ,eyemouth1 not far from ,st4 ,abb's ,head1 where the schists of the ,lammermuir range are undermined and dissected by the sea4 ,here the curved and vertical strata1 now known to be of ,silurian age1 and which often exhibit a ripple-marked surface#fj-;,b1 are well exposed at the headland called the ,siccar ,point1 penetrating with their edges into the incumbent beds of slightly inclined sandstone1 in which large pieces of the schist1 some round and others angular1 are united by an arenaceous cement4 ,what clearer evidence1 exclaims ,playfair1 could we have had of the different formation of these rocks1 and of the long interval which separated their formation1 had we actually seen them emerging from the bosom of the deep8 ,we felt ourselves necessarily carried back to the time when the schistus on which we stood was yet at the bottom of the sea1 and when the sandstone before us was only beginning to be deposited in the shape of sand or mud1 from the waters of a superincumbent ocean4 ,an epoch still more remote presented itself1 when even the most ancient of these rocks1 instead of standing upright in vertical beds1 lay in horizontal planes at the bottom of the sea1 and was not yet disturbed by that immeasurable force which has burst asunder the solid pavement of the globe4 ,revolutions still more remote appeared in the distance of this extraordinary perspective4 ,the mind seemed to grow giddy by looking so far into the abyss of time2 and while we listened with earnestness and admiration to the philosopher who was now unfolding to us the order and series of these wonderful events1 we became sensible how much farther reason may sometimes go than imagination can venture to follow4#fj-;,c ,in the frontispiece of this volume the reader will see a view of this classical spot1 reduced from a large picture1 faithfully sketched and coloured from nature by the youngest son of the late ,sir ,james ,hall4 ,it was impossible1 however1 to do justice to the original sketch1 in an engraving1 as the contrast of the red sandstone and the light fawn-coloured vertical schists could not be expressed4 ,from the point of view here selected1 the underlying beds of the perpendicular schist1 a1 are visible at b through a small opening in the fractured beds of the covering of red sandstone1 d d1 while on the vertical face of the old schist at a' a a conspicuous ripple-mark is displayed4 ,illustration3 ,fig4 #hd4 ,junction of unconformable strata near ,mons1 in ,belgium4 ,it often happens that in the interval between the deposition of two sets of unconformable strata1 the inferior rock has not only been denuded1 but drilled by perforating shells4 ,thus1 for example1 at ,autreppe and ,gusigny1 near ,mons1 beds of an ancient 7paleozoic7 limestone1 highly inclined1 and often bent1 are covered with horizontal strata of greenish and whitish marls of the ,cretaceous formation4 ,the lowest and therefore the oldest bed of the horizontal series is usually the sand and conglomerate1 a1 in which are rounded fragments of stone1 from an inch to two feet in diameter4 ,these fragments have often adhering shells attached to them1 and have been bored by perforating mollusca4 ,the solid surface of the inferior limestone has also been bored1 so as to exhibit cylindrical and pear-shaped cavities1 as at c1 the work of saxicavous mollusca2 and many rents1 as at b1 which descend several feet or yards into the limestone1 have been filled with sand and shells1 similar to those in the stratum a4 ,fractures of the strata and faults4--,numerous rents may often be seen in rocks which appear to have been simply broken1 the separated parts remaining in the same places2 but we often find a fissure1 several inches or yards wide1 intervening between the disunited portions4 ,these fissures are usually filled with fine earth and sand1 or with angular fragments of stone1 evidently derived from the fracture of the contiguous rocks4 ,the face of each wall of the fissure is often beautifully polished1 as if glazed1 and not unfrequently striated or scored with parallel furrows and ridges1 such as would be produced by the continued rubbing together of surfaces of unequal hardness4 ,these polished surfaces are called by miners slickensides4 ,it is supposed that the lines of the striae indicate the direction in which the rocks were moved4 ,during one of the minor earthquakes in ,chili1 which happened about the year #ahdj1 and was described to me by an eye-witness1 the brick walls of a building were rent vertically in several places1 and made to vibrate for several minutes during each shock1 after which they remained uninjured1 and without any opening1 although the line of each crack was still visible4 ,when all movement had ceased1 there were seen on the floor of the house1 at the bottom of each rent1 small heaps of fine brickdust1 evidently produced by trituration4 ,illustration3 ,fig4 #he4 ,faults4 ,a ,b perpendicular1 ,c ,d oblique to the horizon4 ,it is not uncommon to find the mass of rock1 on one side of a fissure1 thrown up above or down below the mass with which it was once in contact on the other side4 ,this mode of displacement is called a shift1 slip1 or fault4 ,the miner1 says ,playfair1 describing a fault1 is often perplexed1 in his subterraneous journey1 by a derangement in the strata1 which changes at once all those lines and bearings which had hitherto directed his course4 ,when his mine reaches a certain plane1 which is sometimes perpendicular1 as in ,a ,b1 fig4 #he41 sometimes oblique to the horizon 7as in ,c ,d1 ibid471 he finds the beds of rock broken asunder1 those on the one side of the plane having changed their place1 by sliding in a particular direction along the face of the others4 ,in this motion they have sometimes preserved their parallelism1 as in fig4 #he41 so that the strata on each side of the faults ,a ,b1 ,c ,d1 continue parallel to one another2 in other cases1 the strata on each side are inclined1 as in a1 b1 c1 d 7fig4 #hf471 though their identity is still to be recognized by their possessing the same thickness1 and the same internal characters4#fb-;,a ,illustration3 ,fig4 #hf4 ,e ,f1 fault or fissure filled with rubbish1 on each side of which the shifted strata are not parallel4 ,in ,coalbrook ,dale1 says ,mr4 ,prestwich#fb-;,b1 deposits of sandstone1 shale1 and coal1 several thousand feet thick1 and occupying an area of many miles1 have been shivered into fragments1 and the broken remnants have been placed in very discordant positions1 often at levels differing several hundred feet from each other4 ,the sides of the faults1 when perpendicular1 are commonly separated several yards1 but are sometimes as much as #ej yards asunder1 the interval being filled with broken debris of the strata4 ,in following the course of the same fault it is sometimes found to produce in different places very unequal changes of level1 the amount of shift being in one place #cjj1 and in another #gjj feet1 which arises1 in some cases1 from the union of two or more faults4 ,in other words1 the disjointed strata have in certain districts been subjected to renewed movements1 which they have not suffered elsewhere4 ,we may occasionally see exact counterparts of these slips1 on a small scale1 in pits of fine loose sand and gravel1 many of which have doubtless been caused by the drying and shrinking of argillaceous and other beds1 slight subsidences having taken place from failure of support4 ,sometimes1 however1 even these small slips may have been produced during earthquakes2 for land has been moved1 and its level1 relatively to the sea1 considerably altered1 within the period when much of the alluvial sand and gravel now covering the surface of continents was deposited4 ,i have already stated that a geologist must be on his guard1 in a region of disturbed strata1 against inferring repeated alternations of rocks1 when1 in fact1 the same strata1 once continuous1 have been bent round so as to recur in the same section1 and with the same dip4 ,a similar mistake has often been occasioned by a series of faults4 ,illustration3 ,fig4 #hg4 ,apparent alternations of strata caused by vertical faults4 ,if1 for example1 the dark line ,a ,h 7fig4 #hg47 represent the surface of a country on which the strata a b c frequently crop out1 an observer1 who is proceeding from ,h to ,a1 might at first imagine that at every step he was approaching new strata1 whereas the repetition of the same beds has been caused by vertical faults1 or downthrows4 ,thus1 suppose the original mass1 ,a1 ,b1 ,c1 ,d1 to have been a set of uniformly inclined strata1 and that the different masses under ,e ,f1 ,f ,g1 and ,g ,d1 sank down successively1 so as to leave vacant the spaces marked in the diagram by dotted lines1 and to occupy those marked by the continuous lines1 then let denudation take place along the line ,a ,h1 so that the protruding masses indicated by the fainter lines are swept away1--a miner1 who has not discovered the faults1 finding the mass a1 which we will suppose to be a bed of coal four times repeated1 might hope to find four beds1 workable to an indefinite depth1 but first on arriving at the fault ,g he is stopped suddenly in his workings1 upon reaching the strata of sandstone c1 or on arriving at the line of fault ,f he comes partly upon the shale b1 and partly on the sandstone c1 and on reaching ,e he is again stopped by a wall composed of the rock d4 ,illustration3 ,fig4 #hh4 ,cross section4 ,the very different levels at which the separated parts of the same strata are found on the different sides of the fissure1 in some faults1 is truly astonishing4 ,one of the most celebrated in ,england is that called the ninety-fathom dike1 in the coal-field of ,newcastle4 ,this name has been given to it1 because the same beds are ninety fathoms lower on the northern than they are on the southern side4 ,the fissure has been filled by a body of sand1 which is now in the state of sandstone1 and is called the dike1 which is sometimes very narrow1 but in other places more than twenty yards wide4#fd-;,a ,the walls of the fissure are scored by grooves1 such as would have been produced if the broken ends of the rock had been rubbed along the plane of the fault4#fd-;,b ,in the ,tynedale and ,craven faults1 in the north of ,england1 the vertical displacement is still greater1 and has extended in a horizontal direction for a distance of thirty miles or more4 ,some geologists consider it necessary to imagine that the upward or downward movement in these cases was accomplished at a single stroke1 and not by a series of sudden but interrupted movements4 ,this idea appears to have been derived from a notion that the grooved walls have merely been rubbed in one direction4 ,but this is so far from being a constant phenomenon in faults1 that it has often been objected to the received theory respecting those polished surfaces called slickensides 7see above1 p4 #fa471 that the striae are not always parallel1 but often curved and irregular4 ,it has1 moreover1 been remarked1 that not only the walls of the fissure or fault1 but its earthy contents1 sometimes present the same polished and striated faces4 ,now these facts seem to indicate partial changes in the direction of the movement1 and some slidings subsequent to the first filling up of the fissure4 ,suppose the mass of rock ,a1 ,b1 ,c1 to overlie an extensive chasm d e1 formed at the depth of several miles1 whether by the gradual contraction in bulk of a melted mass passing into a solid or crystalline state1 or the shrinking of argillaceous strata1 baked by a moderate heat1 or by the subtraction of matter by volcanic action1 or any other cause4 ,now1 if this region be convulsed by earthquakes1 the fissures f g1 and others at right angles to them1 may sever the mass ,b from ,a and from ,c1 so that it may move freely1 and begin to sink into the chasm4 ,a fracture may be conceived so clean and perfect as to allow it to subside at once to the bottom of the subterranean cavity2 but it is far more probable that the sinking will be effected at successive periods during different earthquakes1 the mass always continuing to slide in the same direction along the planes of the fissures f g1 and the edges of the falling mass being continually more broken and triturated at each convulsion4 ,if1 as is not improbable1 the circumstances which have caused the failure of support continue in operation1 it may happen that when the mass ,b has filled the cavity first formed1 its foundations will again give way under it1 so that it will fall again in the same direction4 ,but1 if the direction should change1 the fact could not be discovered by observing the slickensides1 because the last scoring would efface the lines of previous friction4 ,in the present state of our ignorance of the causes of subsidence1 an hypothesis which can explain the great amount of displacement in some faults1 on sound mechanical principles1 by a succession of movements1 is far preferable to any theory which assumes each fault to have been accomplished by a single upcast or downthrow of several thousand feet4 ,for we know that there are operations now in progress1 at great depths in the interior of the earth1 by which both large and small tracts of ground are made to rise above and sink below their former level1 some slowly and insensibly1 others suddenly and by starts1 a few feet or yards at a time2 whereas there are no grounds for believing that1 during the last #cjjj years at least1 any regions have been either upheaved or depressed1 at a single stroke1 to the amount of several hundred1 much less several thousand feet4 ,when some of the ancient marine formations are described in the sequel1 it will appear that their structure and organic contents point to the conclusion1 that the floor of the ocean was slowly sinking at the time of their origin4 ,the downward movement was very gradual1 and in ,wales and the contiguous parts of ,england a maximum thickness of #cb1jjj feet 7more than six miles7 of ,carboniferous1 ,devonian1 and ,silurian rock was formed1 whilst the bed of the sea was all the time continuously and tranquilly subsiding4#fe-;,a ,whatever may have been the changes which the solid foundation underwent1 whether accompanied by the melting1 consolidation1 crystallization1 or desiccation of subjacent mineral matter1 it is clear from the fact of the sea having remained shallow all the while that the bottom never sank down suddenly to the depth of many hundred feet at once4 ,it is by assuming such reiterated variations of level1 each separately of small vertical amount1 but multiplied by time till they acquire importance in the aggregate1 that we are able to explain the phenomena of denudation1 which will be treated of in the next chapter4 ,by such movements every portion of the surface of the land becomes in its turn a line of coast1 and is exposed to the action of the waves and tides4 ,a country which is undergoing such movement is never allowed to settle into a state of equilibrium1 therefore the force of rivers and torrents to remove or excavate soil and rocky masses is sustained in undiminished energy4 ,,footnotes3 #df-;,a ,in the first three editions of my ,principles of ,geology1 ,i expressed many doubts as to the validity of the alleged proofs of a gradual rise of land in ,sweden2 but after visiting that country1 in #ahcd1 ,i retracted these objections1 and published a detailed statement of the observations which led me to alter my opinion in the ,phil4 ,trans4 #ahce1 ,part ,i4 ,see also the ,principles1 #dth and subsequent editions4 #df-;,b ,see his ,journal of a ,naturalist in ,voyage of the ,beagle1 and his work on ,coral ,reefs4 #df-;,c ,see chapters xxviii4 to xxxi4 inclusive4 #dh-;,a ,edin4 ,trans4 vol4 vii4 pl4 #c4 #ej-;,a ,proceedings of ,geol4 ,soc4 vol4 iii4 p4 #adh4 #ec-;,a ,see plan by ,m4 ,chevalier1 ,burat's ,d',aubuisson1 tom4 ii4 p4 #ccd4 #ee-;,a ,see ,m4 ,thurmann's work1 ,essai sur les ,soulevemens ,jurassiques du ,porrentruy1 ,paris1 #ahcb1 with whom ,i examined part of these mountains in #ahce4 #eg-;,a ,i am indebted to the kindness of ,t4 ,sopwith1 ,esq41 for three models which ,i have copied in the above diagrams2 but the beginner may find it by no means easy to understand such copies1 although1 if he were to examine and handle the originals1 turning them about in different ways1 he would at once comprehend their meaning as well as the import of others far more complicated1 which the same engineer has constructed to illustrate faults4 #fj-;,a ,biographical account of ,dr4 ,hutton4 #fj-;,b ,see above1 p4 #di4 and section4 #fj-;,c ,playfair1 ibid42 see his ,works1 ,edin4 #ahbb1 vol4 iv4 p4 #ha4 #fb-;,a ,playfair1 ,illust4 of ,hutt4 ,theory1 ,sec4 #db4 #fb-;,b ,geol4 ,trans4 second series1 vol4 v4 p4 #deb4 #fd-;,a ,conybeare and ,phillips1 ,outlines1 c4 p4 #cgf4 #fd-;,b ,phillips1 ,geology1 ,lardner's ,cyclop4 p4 #da4 #fe-;,a ,see the results of the ,geological ,survey of ,great ,britain2 ,memoirs1 vols4 i4 and ii41 by ,sir ,h4 ,de la ,beche1 ,mr4 ,a4 ,c4 ,ramsay1 and ,mr4 ,john ,phillips4 ,,chapter ,,vi4 ,,denudation4 ,denudation defined--,its amount equal to the entire mass of stratified deposits in the earth's crust--,horizontal sandstone denuded in ,ross-shire--,levelled surface of countries in which great faults occur--,coalbrook ,dale--,denuding power of the ocean during the emergence of land--,origin of ,valleys--,obliteration of sea-cliffs--,inland sea-cliffs and terraces in the ,morea and ,sicily--,limestone pillars at ,st4 ,mihiel1 in ,france--in ,canada--in the ,bermudas4 ,denudation1 which has been occasionally spoken of in the preceding chapters1 is the removal of solid matter by water in motion1 whether of rivers or of the waves and currents of the sea1 and the consequent laying bare of some inferior rock4 ,geologists have perhaps been seldom in the habit of reflecting that this operation has exerted an influence on the structure of the earth's crust as universal and important as sedimentary deposition itself2 for denudation is the inseparable accompaniment of the production of all new strata of mechanical origin4 ,the formation of every new deposit by the transport of sediment and pebbles necessarily implies that there has been1 somewhere else1 a grinding down of rock into rounded fragments1 sand1 or mud1 equal in quantity to the new strata4 ,all deposition1 therefore1 except in the case of a shower of volcanic ashes1 is the sign of superficial waste going on contemporaneously1 and to an equal amount elsewhere4 ,the gain at one point is no more than sufficient to balance the loss at some other4 ,here a lake has grown shallower1 there a ravine has been deepened4 ,the bed of the sea has in one region been raised by the accumulation of new matter1 in another its depth has been augmented by the abstraction of an equal quantity4 ,when we see a stone building1 we know that somewhere1 far or near1 a quarry has been opened4 ,the courses of stone in the building may be compared to successive strata1 the quarry to a ravine or valley which has suffered denudation4 ,as the strata1 like the courses of hewn stone1 have been laid one upon another gradually1 so the excavation both of the valley and quarry have been gradual4 ,to pursue the comparison still farther1 the superficial heaps of mud1 sand1 and gravel1 usually called alluvium1 may be likened to the rubbish of a quarry which has been rejected as useless by the workmen1 or has fallen upon the road between the quarry and the building1 so as to lie scattered at random over the ground4 ,if1 then1 the entire mass of stratified deposits in the earth's crust is at once the monument and measure of the denudation which has taken place1 on how stupendous a scale ought we to find the signs of this removal of transported materials in past ages6 ,accordingly1 there are different classes of phenomena1 which attest in a most striking manner the vast spaces left vacant by the erosive power of water4 ,i may allude1 first1 to those valleys on both sides of which the same strata are seen following each other in the same order1 and having the same mineral composition and fossil contents4 ,we may observe1 for example1 several formations1 as ,nos4 #a1 #b1 #c1 #d1 in the accompanying diagram 7fig4 #hi472 ,no4 #a4 conglomerate1 ,no4 #b4 clay1 ,no4 #c4 grit1 and ,no4 #d4 limestone1 each repeated in a series of hills separated by valleys varying in depth4 ,when we examine the subordinate parts of these four formations1 we find1 in like manner1 distinct beds in each1 corresponding1 on the opposite sides of the valleys1 both in composition and order of position4 ,no one can doubt that the strata were originally continuous1 and that some cause has swept away the portions which once connected the whole series4 ,a torrent on the side of a mountain produces similar interruptions2 and when we make artificial cuts in lowering roads1 we expose1 in like manner1 corresponding beds on either side4 ,but in nature1 these appearances occur in mountains several thousand feet high1 and separated by intervals of many miles or leagues in extent1 of which a grand exemplification is described by ,dr4 ,mac,culloch1 on the north-western coast of ,ross-shire1 in ,scotland4#fg-;,a ,the fundamental rock of that country is gneiss1 in disturbed strata1 on which beds of nearly horizontal red sandstone rest unconformably4 ,the latter are often very thin1 forming mere flags1 with their surfaces1 distinctly ripple-marked4 ,they end abruptly on the declivities of many insulated mountains1 which rise up at once to the height of about #bjjj feet above the gneiss of the surrounding plain or table land1 and to an average elevation of about #cjjj feet above the sea1 which all their summits generally attain4 ,the base of gneiss varies in height1 so that the lower portions of the sandstone occupy different levels1 and the thickness of the mass is various1 sometimes exceeding #cjjj feet4 ,it is impossible to compare these scattered and detached portions without imagining that the whole country has once been covered with a great body of sandstone1 and that masses from #ajjj to more than #cjjj feet in thickness have been removed4 ,illustration3 ,fig4 #hi4 ,valleys of denudation4 a4 alluvium4 ,illustration3 ,fig4 #ij4 ,denudation of red sandstone on north-west coast of ,ross-shire4 7,mac,culloch47 ,in the ,survey of ,great ,britain 7vol4 i471 ,professor ,ramsay has shown that the missing beds1 removed from the summit of the ,mendips1 must have been nearly a mile in thickness2 and he has pointed out considerable areas in ,south ,wales and some of the adjacent counties of ,england1 where a series of palaeozoic strata1 not less than #aa1jjj feet in thickness1 have been stripped off4 ,all these materials have of course been transported to new regions1 and have entered into the composition of more modern formations4 ,on the other hand1 it is shown by observations in the same ,survey1 that the palaeozoic strata are from #bj1jjj to #cj1jjj feet thick4 ,it is clear that such rocks1 formed of mud and sand1 now for the most part consolidated1 are the monuments of denuding operations1 which took place on a grand scale at a very remote period in the earth's history4 ,for1 whatever has been given to one area must always have been borrowed from another2 a truth which1 obvious as it may seem when thus stated1 must be repeatedly impressed on the student's mind1 because in many geological speculations it is taken for granted that the external crust of the earth has been always growing thicker1 in consequence of the accumulation1 period after period1 of sedimentary matter1 as if the new strata were not always produced at the expense of pre-existing rocks1 stratified or unstratified4 ,by duly reflecting on the fact1 that all deposits of mechanical origin imply the transportation from some other region1 whether contiguous or remote1 of an equal amount of solid matter1 we perceive that the stony exterior of the planet must always have grown thinner in one place whenever1 by accessions of new strata1 it was acquiring density in another4 ,no doubt the vacant space left by the missing rocks1 after extensive denudation1 is less imposing to the imagination than a vast thickness of conglomerate or sandstone1 or the bodily presence as it were of a mountain-chain1 with all its inclined and curved strata4 ,but the denuded tracts speak a clear and emphatic language to our reason1 and1 like repeated layers of fossil nummulites1 corals or shells1 or like numerous seams of coal1 each based on its under clay full of the roots of trees1 still remaining in their natural position1 demand an indefinite lapse of time for their elaboration4 ,no one will maintain that the fossils entombed in these rocks did not belong to many successive generations of plants and animals4 ,in like manner1 each sedimentary deposit attests a slow and gradual action1 and the strata not only serve as a measure of the amount of denudation simultaneously effected elsewhere1 but are also a correct indication of the rate at which the denuding operation was carried on4 ,perhaps the most convincing evidence of denudation on a magnificent scale is derived from the levelled surfaces of districts where large faults occur4 ,i have shown1 in fig4 #hg4 p4 #fc41 and in fig4 #ia41 how angular and protruding masses of rock might naturally have been looked for on the surface immediately above great faults1 although in fact they rarely exist4 ,this phenomenon may be well studied in those districts where coal has been extensively worked1 for there the former relation of the beds which have shifted their position may be determined with great accuracy4 ,thus in the coal field of ,ashby de la ,zouch1 in ,leicestershire 7see fig4 #ia471 a fault occurs1 on one side of which the coal beds a b c d rise to the height of #ejj feet above the corresponding beds on the other side4 ,but the uplifted strata do not stand up #ejj feet above the general surface2 on the contrary1 the outline of the country1 as expressed by the line z z1 is uniform and unbroken1 and the mass indicated by the dotted outline must have been washed away4#fi-;,a ,there are proofs of this kind in some level countries1 where dense masses of strata have been cleared away from areas several hundred square miles in extent4 ,illustration3 ,fig4 #ia4 ,faults and denuded coal strata1 ,ashby de la ,zouch4 7,mammat47 ,in the ,newcastle coal district it is ascertained that faults occur in which the upward or downward movement could not have been less than #adj fathoms1 which1 had they affected equally the configuration of the surface to that amount1 would produce mountains with precipitous escarpments nearly #ajjj feet high1 or chasms of the like depth2 yet is the actual level of the country absolutely uniform--affording no trace whatever of subterranean movements4#fi-;,b ,the ground from which these materials have been removed is usually overspread with heaps of sand and gravel1 formed out of the ruins of the very rocks which have disappeared4 ,thus1 in the districts above referred to1 they consist of rounded and angular fragments of hard sandstone1 limestone1 and ironstone1 with a small quantity of the more destructible shale1 and even rounded pieces of coal4 ,allusion has been already made to the shattered state and discordant position of the carboniferous strata in ,coalbrook ,dale 7p4 #fb474 ,the collier cannot proceed three or four yards without meeting with small slips1 and from time to time he encounters faults of considerable magnitude1 which have thrown the rocks up or down several hundred feet4 ,yet the superficial inequalities to which these dislocated masses originally gave rise are no longer discernible1 and the comparative flatness of the existing surface can only be explained1 as ,mr4 ,prestwich has observed1 by supposing the fractured portions to have been removed by water4 ,it is also clear that strata of red sandstone1 more than #ajjj feet thick1 which once covered the coal1 in the same region1 have been carried away from large areas4 ,that water has1 in this case1 been the denuding agent1 we may infer from the fact that the rocks have yielded according to their different degrees of hardness2 the hard trap of the ,wrekin1 for example1 and other hills1 having resisted more than the softer shale and sandstone1 so as now to stand out in bold relief4#gj-;,a ,origin of valleys4--,many of the earlier geologists1 and ,dr4 ,hutton among them1 taught that rivers have in general hollowed out their valleys4 ,this is true only of rivulets and torrents which are the feeders of the larger streams1 and which1 descending over rapid slopes1 are most subject to temporary increase and diminution in the volume of their waters4 ,the quantity of mud1 sand1 and pebbles constituting many a modern delta proves indisputably that no small part of the inequalities now existing on the earth's surface are due to fluviatile action2 but the principal valleys in almost every great hydrographical basin in the world1 are of a shape and magnitude which imply that they have been due to other causes besides the mere excavating power of rivers4 ,some geologists have imagined that a deluge1 or succession of deluges1 may have been the chief denuding agency1 and they have speculated on a series of enormous waves raised by the instantaneous upthrow of continents or mountain chains out of the sea4 ,but even were we disposed to grant such sudden upheavals of the floor of the ocean1 and to assume that great waves would be the consequence of each convulsion1 it is not easy to explain the observed phenomena by the aid of so gratuitous an hypothesis4 ,on the other hand1 a machinery of a totally different kind seems capable of giving rise to effects of the required magnitude4 ,it has now been ascertained that the rising and sinking of extensive portions of the earth's crust1 whether insensibly or by a repetition of sudden shocks1 is part of the actual course of nature1 and we may easily comprehend how the land may have been exposed during these movements to abrasion by the waves of the sea4 ,in the same manner as a mountain mass may1 in the course of ages1 be formed by sedimentary deposition1 layer after layer1 so masses equally voluminous may in time waste away by inches2 as1 for example1 if beds of incoherent materials are raised slowly in an open sea where a strong current prevails4 ,it is well known that some of these oceanic currents have a breadth of #bjj miles1 and that they sometimes run for a thousand miles or more in one direction1 retaining a considerable velocity even at the depth of several hundred feet4 ,under these circumstances1 the flowing waters may have power to clear away each stratum of incoherent materials as it rises and approaches the surface1 where the waves exert the greatest force2 and in this manner a voluminous deposit may be entirely swept away1 so that1 in the absence of faults1 no evidence may remain of the denuding operation4 ,it may indeed be affirmed that the signs of waste will usually be least obvious where the destruction has been most complete2 for the annihilation may have proceeded so far1 that no ruins are left of the dilapidated rocks4 ,although denudation has had a levelling influence on some countries of shattered and disturbed strata 7see fig4 #hg4 p4 #fc4 and fig4 #ia4 p4 #fi471 it has more commonly been the cause of superficial inequalities1 especially in regions of horizontal stratification4 ,the general outline of these regions is that of flat and level platforms1 interrupted by valleys often of considerable depth1 and ramifying in various directions4 ,these hollows may once have formed bays and channels between islands1 and the steepest slope on the sides of each valley may have been a sea-cliff1 which was undermined for ages1 as the land emerged gradually from the deep4 ,we may suppose the position and course of each valley to have been originally determined by differences in the hardness of the rocks1 and by rents and joints which usually occur even in horizontal strata4 ,in mountain chains1 such as the ,jura before described 7see fig4 #ga4 p4 #ee471 we perceive at once that the principal valleys have not been due to aqueous excavation1 but to those mechanical movements which have bent the rocks into their present form4 ,yet even in the ,jura there are many valleys1 such as ,c 7fig4 #ga471 which have been hollowed out by water2 and it may be stated that in every part of the globe the unevenness of the surface of the land has been due to the combined influence of subterranean movements and denudation4 ,i may now recapitulate a few of the conclusions to which we have arrived3 first1 all the mechanical strata have been accumulated gradually1 and the concomitant denudation has been no less gradual3 secondly1 the dry land consists in great part of strata formed originally at the bottom of the sea1 and has been made to emerge and attain its present height by a force acting from beneath3 thirdly1 no combination of causes has yet been conceived so capable of producing extensive and gradual denudation1 as the action of the waves and currents of the ocean upon land slowly rising out of the deep4 ,now1 if we adopt these conclusions1 we shall naturally be led to look everywhere for marks of the former residence of the sea upon the land1 especially near the coasts from which the last retreat of the waters took place1 and it will be found that such signs are not wanting4 ,i shall have occasion to speak of ancient sea-cliffs1 now far inland1 in the south-east of ,england1 when treating in ,chapter ,,xix4 of the denudation of the chalk in ,surrey1 ,kent1 and ,sussex4 ,lines of upraised sea-beaches of more modern date are traced1 at various levels from #bj to #ajj feet and upwards above the present sea-level1 for great distances on the east and west coasts of ,scotland1 as well as in ,devonshire1 and other counties in ,england4 ,these ancient beach-lines often form terraces of sand and gravel1 including littoral shells1 some broken1 others entire1 and corresponding with species now living on the adjoining coast4 ,but it would be unreasonable to expect to meet everywhere with the signs of ancient shores1 since no geologist can have failed to observe how soon all recent marks of the kind above alluded to are obscured or entirely effaced1 wherever1 in consequence of the altered state of the tides and currents1 the sea has receded for a few centuries4 ,we see the cliffs crumble down in a few years if composed of sand or clay1 and soon reduced to a gentle slope4 ,if there were shells on the beach they decompose1 and their materials are washed away1 after which the sand and shingle may resemble any other alluviums scattered over the interior4 ,illustration3 ,fig4 #ib4 ,section of inland cliff at ,abesse1 near ,dax4 a4 ,sand of the ,landes4 b4 ,limestone4 c4 ,clay4 ,the features of an ancient shore may sometimes be concealed by the growth of trees and shrubs1 or by a covering of blown sand1 a good example of which occurs a few miles west from ,dax1 near ,bordeaux1 in the south of ,france4 ,about twelve miles inland1 a steep bank may be traced running in a direction nearly north-east and south-west1 or parallel to the contiguous coast4 ,this sudden fall of about #ej feet conducts us from the higher platform of the ,landes to a lower plain which extends to the sea4 ,the outline of the ground suggested to me1 as it would do to every geologist1 the opinion that the bank in question was once a sea-cliff1 when the whole country stood at a lower level4 ,but this is no longer matter of conjecture1 for1 in making excavations in #ahcj for the foundation of a building at ,abesse1 a quantity of loose sand1 which formed the slope d e1 was removed2 and a perpendicular cliff1 about #ej feet in height1 which had hitherto been protected from the agency of the elements1 was exposed4 ,at the bottom appeared the limestone b1 containing tertiary shells and corals1 immediately below it the clay c1 and above it the usual tertiary sand a1 of the department of the ,landes4 ,at the base of the precipice were seen large partially rounded masses of rock1 evidently detached from the stratum b4 ,the face of the limestone was hollowed out and weathered into such forms as are seen in the calcareous cliffs of the adjoining coast1 especially at ,biaritz1 near ,bayonne4 ,it is evident that1 when the country was at a somewhat lower level1 the sea advanced along the surface of the argillaceous stratum c1 which1 from its yielding nature1 favoured the waste by allowing the more solid superincumbent stone b to be readily undermined4 ,afterwards1 when the country had been elevated1 part of the sand1 a1 fell down1 or was drifted by the winds1 so as to form the talus1 d e1 which masked the inland cliff until it was artificially laid open to view4 ,when we are considering the various causes which1 in the course of ages1 may efface the characters of an ancient sea-coast1 earthquakes must not be forgotten4 ,during violent shocks1 steep and overhanging cliffs are often thrown down and become a heap of ruins4 ,sometimes unequal movements of upheaval or depression entirely destroy that horizontality of the base-line which constitutes the chief peculiarity of an ancient sea-cliff4 ,it is1 however1 in countries where hard limestone rocks abound1 that inland cliffs retain faithfully the characters which they acquired when they constituted the boundary of land and sea4 ,thus1 in the ,morea1 no less than three1 or even four1 ranges of what were once sea-cliffs are well preserved4 ,these have been described1 by ,,mm4 ,boblaye and ,virlet1 as rising one above the other at different distances from the actual shore1 the summit of the highest and oldest occasionally exceeding #ajjj feet in elevation4 ,at the base of each there is usually a terrace1 which is in some places a few yards1 in others above #cjj yards wide1 so that we are conducted from the high land of the interior to the sea by a succession of great steps4 ,these inland cliffs are most perfect1 and most exactly resemble those now washed by the waves of the ,mediterranean1 where they are formed of calcareous rock1 especially if the rock be a hard crystalline marble4 ,the following are the points of correspondence observed between the ancient coast lines and the borders of the present sea3--#a4 ,a range of vertical precipices1 with a terrace at their base4 #b4 ,a weathered state of the surface of the naked rock1 such as the spray of the sea produces4 #c4 ,a line of littoral caverns at the foot of the cliffs4 #d4 ,a consolidated beach or breccia with occasional marine shells1 found at the base of the cliffs1 or in the caves4 #e4 ,lithodomous perforations4 ,in regard to the first of these1 it would be superfluous to dwell on the evidence afforded of the undermining power of waves and currents by perpendicular precipices4 ,the littoral caves1 also1 will be familiar to those who have had opportunities of observing the manner in which the waves of the sea1 when they beat against rocks1 have power to scoop out caverns4 ,as to the breccia1 it is composed of pieces of limestone and rolled fragments of thick solid shell1 such as ,strombus and ,spondylus1 all bound together by a crystalline calcareous cement4 ,similar aggregations are now forming on the modern beaches of ,greece1 and in caverns on the sea-side2 and they are only distinguishable in character from those of more ancient date1 by including many pieces of pottery4 ,in regard to the lithodomi above alluded to1 these bivalve mollusks are well known to have the power of excavating holes in the hardest limestones1 the size of the cavity keeping pace with the growth of the shell4 ,when living they require to be always covered by salt water1 but similar pear-shaped hollows1 containing the dead shells of these creatures1 are found at different heights on the face of the inland cliffs above mentioned4 ,thus1 for example1 they have been observed near ,modon and ,navarino on cliffs in the interior #abe feet high above the ,mediterranean4 ,as to the weathered surface of the calcareous rocks1 all limestones are known to suffer chemical decomposition when moistened by the spray of the salt water1 and are corroded still more deeply at points lower down where they are just reached by the breakers4 ,by this action the stone acquires a wrinkled and furrowed outline1 and very near the sea it becomes rough and branching1 as if covered with corals4 ,such effects are traced not only on the present shore1 but at the base of the ancient cliffs far in the interior4 ,lastly1 it remains only to speak of the terraces1 which extend with a gentle slope from the base of almost all the inland cliffs1 and are for the most part narrow where the rock is hard1 but sometimes half a mile or more in breadth where it is soft4 ,they are the effects of the encroachment of the ancient sea upon the shore at those levels at which the land remained for a long time stationary4 ,the justness of this view is apparent on examining the shape of the modern shore wherever the sea is advancing upon the land1 and removing annually small portions of undermined rock4 ,by this agency a submarine platform is produced on which we may walk for some distance from the beach in shallow water1 the increase of depth being very gradual1 until we reach a point where the bottom plunges down suddenly4 ,this platform is widened with more or less rapidity according to the hardness of the rocks1 and when upraised it constitutes an inland terrace4 ,but the four principal lines of cliff observed in the ,morea do not imply1 as some have imagined1 four great eras of sudden upheaval2 they simply indicate the intermittence of the upheaving force4 ,had the rise of the land been continuous and uninterrupted1 there would have been no one prominent line of cliff2 for every portion of the surface having been1 in its turn1 and for an equal period of time1 a sea-shore1 would have presented a nearly similar aspect4 ,but if pauses occur in the process of upheaval1 the waves and currents have time to sap1 throw down1 and clear away considerable masses of rock1 and to shape out at certain levels lofty ranges of cliffs with broad terraces at their base4 ,there are some levelled spaces1 however1 both ancient and modern1 in the ,morea1 which are not due to denudation1 although resembling in outline the terraces above described4 ,they may be called ,terraces of ,deposition1 since they have resulted from the gain of land upon the sea where rivers and torrents have produced deltas4 ,if the sedimentary matter has filled up a bay or gulf surrounded by steep mountains1 a flat plain is formed skirting the inland precipices2 and if these deposits are upraised1 they form a feature in the landscape very similar to the areas of denudation before described4 ,in the island of ,sicily ,i have examined many inland cliffs like those of the ,morea2 as1 for example1 near ,palermo1 where a precipice is seen consisting of limestone at the base of which are numerous caves4 ,one of these called ,san ,ciro1 about #b miles distant from ,palermo1 is about #bj feet high1 #aj wide1 and #ahj above the sea4 ,within it is found an ancient beach 7b1 fig4 #ic471 formed of pebbles of various rocks1 many of which must have come from places far remote4 ,broken pieces of coral and shell1 especially of oysters and pectens1 are seen intermingled with the pebbles4 ,immediately above the level of this beach1 serpulae are still found adhering to the face of the rock1 and the limestone is perforated by lithodomi4 ,within the grotto1 also1 at the same level1 similar perforations occur2 and so numerous are the holes1 that the rock is compared by ,hoffmann to a target pierced by musket balls4 ,but in order to expose to view these marks of boring-shells in the interior of the cave1 it was necessary first to remove a mass of breccia1 which consisted of numerous fragments of rock and an immense quantity of bones of the mammoth1 hippopotamus1 and other quadrupeds1 imbedded in a dark brown calcareous marl4 ,many of the bones were rolled as if partially subjected to the action of the waves4 ,below this breccia1 which is about #bj feet thick1 was found a bed of sand filled with sea-shells of recent species2 and underneath the sand1 again1 is the secondary limestone of ,monte ,grifone4 ,the state of the surface of the limestone in the cave above the level of the marine sand is very different from that below it4 ,above1 the rock is jagged and uneven1 as is usual in the roofs and sides of limestone caverns2 below1 the surface is smooth and polished1 as if by the attrition of the waves4 ,illustration3 ,fig4 #ic4 ,cross section4 a4 ,monte ,grifone4 b4 ,cave of ,san ,ciro4#ge-;,a c4 ,plain of ,palermo1 in which are ,newer ,pliocene strata of limestone and sand4 d4 ,bay of ,palermo4 ,the platform indicated at c1 fig4 #ic41 is formed by a tertiary deposit containing marine shells almost all of living species1 and it affords an illustration of the terrace of deposition1 or the last of the two kinds before mentioned 7p4 #gd474 ,there are also numerous instances in ,sicily of terraces of denudation4 ,one of these occurs on the east coast to the north of ,syracuse1 and the same is resumed to the south beyond the town of ,noto1 where it may be traced forming a continuous and lofty precipice1 a b1 fig4 #id41 facing towards the sea1 and constituting the abrupt termination of a calcareous formation1 which extends in horizontal strata far inland4 ,this precipice varies in height from #ejj to #gjj feet1 and between its base and the sea is an inferior platform1 c b1 consisting of similar white limestone4 ,all the beds dip towards the sea1 but are usually inclined at a very slight angle3 they are seen to extend uninterruptedly from the base of the escarpment into the platform1 showing distinctly that the lofty cliff was not produced by a fault or vertical shift of the beds1 but by the removal of a considerable mass of rock4 ,hence we may conclude that the sea1 which is now undermining the cliffs of the ,sicilian coast1 reached at some former period the base of the precipice a b1 at which time the surface of the terrace c b must have been covered by the ,mediterranean4 ,there was a pause1 therefore1 in the upward movement1 when the waves of the sea had time to carve out the platform c b2 but there may have been many other stationary periods of minor duration4 ,suppose1 for example1 that a series of escarpments e1 f1 g1 h1 once existed1 and that the sea1 during a long interval free from subterranean movements1 advances along the line c b1 all preceding cliffs must have been swept away one after the other1 and reduced to the single precipice a b4 ,illustration3 ,fig4 #id4 ,cross section4 ,illustration3 ,fig4 #ie4 ,valley called ,gozzo degli ,martiri1 below ,melilli1 ,val di ,noto4 ,that such a series of smaller cliffs1 as those represented at e1 f1 g1 h1 fig4 #id41 did really once exist at intermediate heights in place of the single precipice a b1 is rendered highly probable by the fact1 that in certain bays and inland valleys opening towards the east coast of ,sicily1 and not far from the section given in fig4 #id41 the solid limestone is shaped out into a great succession of ledges1 separated from each other by small vertical cliffs4 ,these are sometimes so numerous1 one above the other1 that where there is a bend at the head of a valley1 they produce an effect singularly resembling the seats of a ,roman amphitheatre4 ,a good example of this configuration occurs near the town of ,melilli1 as seen in the annexed view 7fig4 #ie474 ,in the south of the island1 near ,spaccaforno1 ,scicli1 and ,modica1 precipitous rocks of white limestone1 ascending to the height of #ejj feet1 have been carved out into similar forms4 ,illustration3 ,fig4 #if4 ,cross section4 ,this appearance of a range of marble seats circling round the head of a valley1 or of great flights of steps descending from the top to the bottom1 on the opposite sides of a gorge1 may be accounted for1 as already hinted1 by supposing the sea to have stood successively at many different levels1 as at a a1 b b1 c c1 in the accompanying fig4 #if4 ,but the causes of the gradual contraction of the valley from above downwards may still be matter of speculation4 ,such contraction may be due to the greater force exerted by the waves when the land at its first emergence was smaller in quantity1 and more exposed to denudation in an open sea2 whereas the wear and tear of the rocks might diminish in proportion as this action became confined within bays or channels closed in on two or three sides4 ,or1 secondly1 the separate movements of elevation may have followed each other more rapidly as the land continued to rise1 so that the times of those pauses1 during which the greatest denudation was accomplished at certain levels1 were always growing shorter4 ,it should be remarked1 that the cliffs and small terraces are rarely found on the opposite sides of the ,sicilian valleys at heights so precisely answering to each other as those given in fig4 #if41 and this might have been expected1 to whichever of the two hypotheses above explained we incline2 for1 according to the direction of the prevailing winds and currents1 the waves may beat with unequal force on different parts of the shore1 so that while no impression is made on one side of a bay1 the sea may encroach so far on the other as to unite several smaller cliffs into one4 ,before quitting the subject of ancient sea-cliffs1 carved out of limestone1 ,i shall mention the range of precipitous rocks1 composed of a white marble of the ,oolitic period1 which ,i have seen near the northern gate of ,st4 ,mihiel in ,france4 ,they are situated on the right bank of the ,meuse1 at a distance of #bjj miles from the nearest sea1 and they present on the precipice facing the river three or four horizontal grooves1 one above the other1 precisely resembling those which are scooped out by the undermining waves4 ,the summits of several of these masses are detached from the adjoining hill1 in which case the grooves pass all round them1 facing towards all points of the compass1 as if they had once formed rocky islets near the shore4#gh-;,a ,captain ,bayfield1 in his survey of the ,gulf of ,st4 ,lawrence1 discovered in several places1 especially in the ,mingan islands1 a counterpart of the inland cliffs of ,st4 ,mihiel1 and traced a succession of shingle beaches1 one above the other1 which agreed in their level with some of the principal grooves scooped out of the limestone pillars4 ,these beaches consisted of calcareous shingle1 with shells of recent species1 the farthest from the shore being #fj feet above the level of the highest tides4 ,in addition to the drawings of the pillars called the flower-pots1 which he has published#gh-;,b1 ,i have been favoured with other views of rocks on the same coast1 drawn by ,lieut4 ,a4 ,bowen1 ,r4 ,n4 7,see fig4 #ig47 ,illustration3 ,fig4 #ig4 ,limestone columns in ,niapisca ,island1 in the ,gulf of ,st4 ,lawrence4 ,height of the second column on the left1 #fj feet4 ,in the ,north-,american beaches above mentioned rounded fragments of limestone have been found perforated by lithodomi2 and holes drilled by the same mollusks have been detected in the columnar rocks or flower-pots1 showing that there has been no great amount of atmospheric decomposition on the surface1 or the cavities alluded to would have disappeared4 ,illustration3 ,fig4 #ih4 ,the ,north ,rocks1 ,bermuda1 lying outside the great coral reef4 ,a4 #af feet high1 and ,b4 #ab feet4 c4 c4 ,hollows worn by the sea4 ,we have an opportunity of seeing in the ,bermuda islands the manner in which the waves of the ,atlantic have worn1 and are now wearing out1 deep smooth hollows on every side of projecting masses of hard limestone4 ,in the annexed drawing1 communicated to me by ,lieut4 ,nelson1 the excavations c1 c1 c1 have been scooped out by the waves in a stone of very modern date1 which1 although extremely hard1 is full of recent corals and shells1 some of which retain their colour4 ,when the forms of these horizontal grooves1 of which the surface is sometimes smooth and almost polished1 and the roofs of which often overhang to the extent of #e feet or more1 have been carefully studied by geologists1 they will serve to testify the former action of the waves at innumerable points far in the interior of the continents4 ,but we must learn to distinguish the indentations due to the original action of the sea1 and those caused by subsequent chemical decomposition of calcareous rocks1 to which they are liable in the atmosphere4 ,notwithstanding the enduring nature of the marks left by littoral action on calcareous rocks1 we can by no means detect sea-beaches and inland cliffs everywhere1 even in ,sicily and the ,morea4 ,on the contrary1 they are1 upon the whole1 extremely partial1 and are often entirely wanting in districts composed of argillaceous and sandy formations1 which must1 nevertheless1 have been upheaved at the same time1 and by the same intermittent movements1 as the adjoining calcareous rocks4 ,,footnotes3 #fg-;,a ,western ,islands1 vol4 ii4 p4 #ic4 pl4 #ca4 fig4 #d4 #fi-;,a ,see ,mammat's ,geological ,facts1 c4 p4 #ij4 and plate4 #fi-;,b ,conybeare's ,report to ,brit4 ,assoc4 #ahdb1 p4 #cha4 #gj-;,a ,prestwich1 ,geol4 ,trans4 second series1 vol4 v4 pp4 #deb4 #dgc4 #ge-;,a ,section given by ,dr4 ,christie1 ,edin4 ,new ,phil4 ,journ4 ,no4 xxiii41 called by mistake the ,cave of ,mardolce1 by the late ,m4 ,hoffmann4 ,see account by ,mr4 ,s4 ,p4 ,pratt1 ,f4 ,g4 ,s4 ,proceedings of ,geol4 ,soc4 ,no4 #cb4 #ahcc4 #gh-;,a ,i was directed by ,m4 ,deshayes to this spot1 which ,i visited in ,june1 #ahcc4 #gh-;,b ,see ,trans4 of ,geol4 ,soc41 second series1 vol4 v4 plate v4 ,,chapter ,,vii4 ,,alluvium4 ,alluvium described--,due to complicated causes--,of various ages1 as shown in ,auvergne--,how distinguished from rocks in situ--,river-terraces--,parallel roads of ,glen ,roy--,various theories respecting their origin4 ,between the superficial covering of vegetable mould and the subjacent rock there usually intervenes in every district a deposit of loose gravel1 sand1 and mud1 to which the name of alluvium has been applied4 ,the term is derived from alluvio1 an inundation1 or alluo1 to wash1 because the pebbles and sand commonly resemble those of a river's bed or the mud and gravel spread over low lands by a flood4 ,a partial covering of such alluvium is found alike in all climates1 from the equatorial to the polar regions2 but in the higher latitudes of ,europe and ,north ,america it assumes a distinct character1 being very frequently devoid of stratification1 and containing huge fragments of rock1 some angular and others rounded1 which have been transported to great distances from their parent mountains4 ,when it presents itself in this form1 it has been called diluvium1 drift1 or the boulder formation2 and its probable connexion with the agency of floating ice and glaciers will be treated of more particularly in the eleventh and twelfth chapters4 ,illustration3 ,fig4 #ii4 ,lavas of ,auvergne resting on alluviums of different ages4 ,the student will be prepared1 by what ,i have said in the last chapter on denudation1 to hear that loose gravel and sand are often met with1 not only on the low grounds bordering rivers1 but also at various points on the sides or even summits of mountains4 ,for1 in the course of those changes in physical geography which may take place during the gradual emergence of the bottom of the sea and its conversion into dry land1 any spot may either have been a sunken reef1 or a bay1 or estuary1 or sea-shore1 or the bed of a river4 ,for this reason it would be unreasonable to hope that we should ever be able to account for all the alluvial phenomena of each particular country1 seeing that the causes of their origin are so complicated4 ,moreover1 the last operations of water have a tendency to disturb and confound together all pre-existing alluviums4 ,hence we are always in danger of regarding as the work of a single era1 and the effect of one cause1 what has in reality been the result of a variety of distinct agents1 during a long succession of geological epochs4 ,much useful instruction may therefore be gained from the exploration of a country like ,auvergne1 where the superficial gravel of very different eras happens to have been preserved by sheets of lava1 which were poured out one after the other at periods when the denudation1 and probably the upheaval1 of rocks were in progress4 ,that region had already acquired in some degree its present configuration before any volcanos were in activity1 and before any igneous matter was superimposed upon the granitic and fossiliferous formations4 ,the pebbles therefore in the older gravels are exclusively constituted of granite and other aboriginal rocks2 and afterwards1 when volcanic vents burst forth into eruption1 those earlier alluviums were covered by streams of lava1 which protected them from intermixture with gravel of subsequent date4 ,in the course of ages1 a new system of valleys was excavated1 so that the rivers ran at lower levels than those at which the first alluviums and sheets of lava were formed4 ,when1 therefore1 fresh eruptions gave rise to new lava1 the melted matter was poured out over lower grounds2 and the gravel of these plains differed from the first or upland alluvium1 by containing in it rounded fragments of various volcanic rocks1 and often bones belonging to distinct groups of land animals which flourished in the country in succession4 ,the annexed drawing will explain the different heights at which beds of lava and gravel1 each distinct from the other in composition and age1 are observed1 some on the flat tops of hills1 #gjj or #hjj feet high1 others on the slope of the same hills1 and the newest of all in the channel of the existing river where there is usually gravel alone1 but in some cases a narrow stripe of solid lava sharing the bottom of the valley with the river4 ,in all these accumulations of transported matter of different ages the bones of extinct quadrupeds have been found belonging to assemblages of land mammalia which flourished in the country in succession1 and which vary specifically1 the one from the other1 in a greater or less degree1 in proportion as the time which separated their entombment has been more or less protracted4 ,the streams in the same district are still undermining their banks and grinding down into pebbles or sand1 columns of basalt and fragments of granite and gneiss2 but the older alluviums1 with the fossil remains belonging to them1 are prevented from being mingled with the gravel of recent date by the cappings of lava before mentioned4 ,but for the accidental interference1 therefore1 of this peculiar cause1 all the alluviums might have passed so insensibly the one into the other1 that those formed at the remotest era might have appeared of the same date as the newest1 and the whole formation might have been regarded by some geologists as the result of one sudden and violent catastrophe4 ,in almost every country1 the alluvium consists in its upper part of transported materials1 but it often passes downwards into a mass of broken and angular fragments derived from the subjacent rock4 ,to this mass the provincial name of rubble1 or brash1 is given in many parts of ,england4 ,it may be referred to the weathering or disintegration of stone on the spot1 the effects of air and water1 sun and frost1 and chemical decomposition4 ,illustration3 ,fig4 #ajj4 ,cross section4 a4 ,vegetable soil4 b4 ,alluvium4 c4 ,mass of same1 apparently detached4 ,the inferior surface of alluvial deposits is often very irregular1 conforming to all the inequalities of the fundamental rocks 7fig4 #ajj474 ,occasionally1 a small mass1 as at c1 appears detached1 and as if included in the subjacent formation4 ,such isolated portions are usually sections of winding subterranean hollows filled up with alluvium4 ,they may have been the courses of springs or subterranean streamlets1 which have flowed through and enlarged natural rents2 or1 when on a small scale and in soft strata1 they may be spaces which the roots of large trees have once occupied1 gravel and sand having been introduced after their decay4 ,illustration3 ,fig4 #aja4 ,sand-pipes in the chalk at ,eaton1 near ,norwich4 ,but there are other deep hollows of a cylindrical form found in ,england1 ,france1 and elsewhere1 penetrating the white chalk1 and filled with sand and gravel1 which are not so readily explained4 ,they are sometimes called sand-pipes1 or sand-galls1 and puits naturels1 in ,france4 ,those represented in the annexed cut were observed by me in #ahci1 laid open in a large chalk-pit near ,norwich4 ,they were of very symmetrical form1 the largest more than #ab feet in diameter1 and some of them had been traced1 by boring1 to the depth of more than #fj feet4 ,the smaller ones varied from a few inches to a foot in diameter1 and seldom descended more than #ab feet below the surface4 ,even where three of them occurred1 as at a1 fig4 #aja41 very close together1 the parting walls of soft white chalk were not broken through4 ,they all taper downwards and end in a point4 ,as a general rule1 sand and pebbles occupy the central parts of each pipe1 while the sides and bottom are lined with clay4 ,mr4 ,trimmer1 in speaking of appearances of the same kind in the ,kentish chalk1 attributes the origin of such sand-galls to the action of the sea on a beach or shoal1 where the waves1 charged with shingle and sand1 not only wear out longitudinal furrows1 such as may be observed on the surface of the chalk near ,norwich when the incumbent gravel is removed1 but also drill deep circular hollows by the rotatory motion imparted to sand and pebbles4 ,such furrows1 as well as vertical cavities1 are now formed1 he observes1 on the coast where the shores are composed of chalk4#hb-;,a ,that the commencement of many of the tubular cavities now under consideration has been due to the cause here assigned1 ,i have little doubt4 ,but such mechanical action could not have hollowed out the whole of the sand-pipes c and d1 fig4 #aja41 because several large chalk-flints seen protruding from the walls of the pipes have not been eroded1 while sand and gravel have penetrated many feet below them4 ,in other cases1 as at b b1 similar unrounded nodules of flint1 still preserving their irregular form and white coating1 are found at various depths in the midst of the loose materials filling the pipe4 ,these have evidently been detached from regular layers of flints occurring above4 ,it is also to be remarked that the course of the same sand-pipe1 b b1 is traceable above the level of the chalk for some distance upwards1 through the incumbent gravel and sand1 by the obliteration of all signs of stratification4 ,occasionally1 also1 as in the pipe d1 the overlying beds of gravel bend downwards into the mouth of the pipe1 so as to become in part vertical1 as would happen if horizontal layers had sunk gradually in consequence of a failure of support4 ,all these phenomena may be accounted for by attributing the enlargement and deepening of the sand-pipes to the chemical action of water charged with carbonic acid1 derived from the vegetable soil and the decaying roots of trees4 ,such acid might corrode the chalk1 and deepen indefinitely any previously existing hollow1 but could not dissolve the flints4 ,the water1 after it had become saturated with carbonate of lime1 might freely percolate the surrounding porous walls of chalk1 and escape through them and from the bottom of the tube1 so as to carry away in the course of time large masses of dissolved calcareous rock#hc-;,a1 and leave behind it on the edges of each tubular hollow a coating of fine clay1 which the white chalk contains4 ,i have seen tubes precisely similar and from #a to #e feet in diameter traversing vertically the upper half of the soft calcareous building stone1 or chalk without flints1 constituting ,st4 ,peter's ,mount1 ,maestricht4 ,these hollows are filled with pebbles and clay1 derived from overlying beds of gravel1 and all terminate downwards like those of ,norfolk4 ,i was informed that1 #f miles from ,maestricht1 one of these pipes1 #b feet in diameter1 was traced downwards to a bed of flattened flints1 forming an almost continuous layer in the chalk4 ,here it terminated abruptly1 but a few small root-like prolongations of it were detected immediately below1 probably where the dissolving substance had penetrated at some points through openings in the siliceous mass4 ,it is not so easy as may at first appear to draw a clear line of distinction between the fixed rocks1 or regular strata 7rocks in situ or in place71 and alluvium4 ,if the bed of a torrent or river be dried up1 we call the gravel1 sand1 and mud left in their channels1 or whatever1 during floods1 they may have scattered over the neighbouring plains1 alluvium4 ,the very same materials carried into a lake1 where they become sorted by water and arranged in more distinct layers1 especially if they inclose the remains of plants1 shells1 or other fossils1 are termed regular strata4 ,in like manner we may sometimes compare the gravel1 sand1 and broken shells1 strewed along the path of a rapid marine current1 with a deposit formed contemporaneously by the discharge of similar materials1 year after year1 into a deeper and more tranquil part of the sea4 ,in such cases1 when we detect marine shells or other organic remains entombed in the strata1 which enable us to determine their age and mode of origin1 we regard them as part of the regular series of fossiliferous formations1 whereas1 if there are no fossils1 we have frequently no power of separating them from the general mass of superficial alluvium4 ,the usual rarity of organic remains in beds of loose gravel and sand is partly owing to the rapid and turbid water in which they were formed having been in a condition unfavourable to the habitation of aquatic beings1 and partly to their porous nature1 which1 by allowing the free percolation of rain-water1 has promoted the decomposition and removal of organic matter4 ,it has long been a matter of common observation that most rivers are now cutting their channels through alluvial deposits of greater depth and extent than could ever have been formed by the present streams4 ,from this fact a rash inference has sometimes been drawn1 that rivers in general have grown smaller1 or become less liable to be flooded than formerly4 ,but such phenomena would be a natural result of any considerable oscillations in the level of the land experienced since the existing valleys originated4 ,suppose part of a continent1 comprising within it a large hydrographical basin like that of the ,mississippi1 to subside several inches or feet in a century1 as the west coast of ,greenland1 extending #fjj miles north and south1 has been sinking for three or four centuries1 between the latitudes #fj deg4 and #fi deg4 ,n4#hd-;,a ,there might be no encroachment of the sea at the river's mouth in consequence of this change of level1 but the fall of the waters flowing from the interior being lessened1 the main river and its tributaries would have less power to carry down to its delta1 and to discharge into the ocean1 the sedimentary matter with which they are annually loaded4 ,they would all begin to raise their channels and alluvial plains by depositing in them the heavier sand and pebbles washed down from the upland country1 and this operation would take place most effectively if the amount of subsidence in the interior was unequal1 and especially if1 on the whole1 it exceeded that of the region near the sea4 ,if then the same area of land be again upheaved to its former height1 the fall1 and consequently the velocity1 of every river would begin to augment4 ,each of them would be less given to overflow its alluvial plain2 and their power of carrying earthy matter seaward1 and of scouring out and deepening their channels1 would continue till1 after a lapse of many thousand years1 each of them would have eroded a new channel or valley through a fluviatile formation of modern date4 ,the surface of what was once the river-plain at the period of greatest depression1 would remain fringing the valley sides in the form of a terrace apparently flat1 but in reality sloping down with the general inclination of the river4 ,everywhere this terrace would present cliffs of gravel and sand1 facing the river4 ,that such a series of movements has actually taken place in the main valley of the ,mississippi and in its tributary valleys during oscillations of level1 ,i have endeavoured to show in my description of that country#he-;,a2 and the freshwater shells of existing species and bones of land quadrupeds1 partly of extinct races preserved in the terraces of fluviatile origin1 attest the exclusion of the sea during the whole process of filling up and partial re-excavation4 ,in many cases1 the alluvium in which rivers are now cutting their channels1 originated when the land first rose out of the sea4 ,if1 for example1 the emergence was caused by a gradual and uniform motion1 every bay and estuary1 or the straits between islands1 would dry up slowly1 and during their conversion into valleys1 every part of the upheaved area would in its turn be a sea-shore1 and might be strewed over with littoral sand and pebbles1 or each spot might be the point where a delta accumulated during the retreat and exclusion of the sea4 ,materials so accumulated would conform to the general slope of a valley from its head to the sea-coast4 ,river terraces4--,we often observe at a short distance from the present bed of a river a steep cliff a few feet or yards high1 and on a level with the top of it a flat terrace corresponding in appearance to the alluvial plain which immediately borders the river4 ,this terrace is again bounded by another cliff1 above which a second terrace sometimes occurs3 and in this manner two or three ranges of cliffs and terraces are occasionally seen on one or both sides of the stream1 the number varying1 but those on the opposite sides often corresponding in height4 ,illustration3 ,fig4 #ajb4 ,river ,terraces and ,parallel ,roads4 ,these terraces are seldom continuous for great distances1 and their surface slopes downwards1 with an inclination similar to that of the river4 ,they are readily explained if we adopt the hypothesis before suggested1 of a gradual rise of the land2 especially if1 while rivers are shaping out their beds1 the upheaving movement be intermittent1 so that long pauses shall occur1 during which the stream will have time to encroach upon one of its banks1 so as to clear away and flatten a large space4 ,this operation being afterwards repeated at lower levels1 there will be several successive cliffs and terraces4 ,parallel roads4--,the parallel shelves1 or roads1 as they have been called1 of ,lochaber or ,glen ,roy and other contiguous valleys in ,scotland1 are distinct both in character and origin from the terraces above described2 for they have no slope towards the sea like the channel of a river1 nor are they the effect of denudation4 ,glen ,roy is situated in the western ,highlands1 about ten miles north of ,fort ,william1 near the western end of the great glen of ,scotland1 or ,caledonian ,canal1 and near the foot of the highest of the ,grampians1 ,ben ,nevis4 ,throughout its whole length1 a distance of more than ten miles1 two1 and in its lower part three1 parallel roads or shelves are traced along the steep sides of the mountains1 as represented in the annexed figure1 fig4 #ajb41 each maintaining a perfect horizontality1 and continuing at exactly the same level on the opposite sides of the glen4 ,seen at a distance1 they appear like ledges or roads1 cut artificially out of the sides of the hills2 but when we are upon them we can scarcely recognize their existence1 so uneven is their surface1 and so covered with boulders4 ,they are from #aj to #fj feet broad1 and merely differ from the side of the mountain by being somewhat less steep4 ,on closer inspection1 we find that these terraces are stratified in the ordinary manner of alluvial or littoral deposits1 as may be seen at those points where ravines have been excavated by torrents4 ,the parallel shelves1 therefore1 have not been caused by denudation1 but by the deposition of detritus1 precisely similar to that which is dispersed in smaller quantities over the declivities of the hills above4 ,these hills consist of clay-slate1 mica-schist1 and granite1 which rocks have been worn away and laid bare at a few points only1 in a line just above the parallel roads4 ,the highest of these roads is about #abej feet above the level of the sea1 the next about #bjj feet lower than the uppermost1 and the third still lower by about #ej feet4 ,it is only this last1 or the lowest of the three1 which is continued throughout ,glen ,spean1 a large valley with which ,glen ,roy unites4 ,as the shelves are always at the same height above the sea1 they become continually more elevated above the river in proportion as we descend each valley2 and they at length terminate very abruptly1 without any obvious cause1 either in the shape of the ground1 or any change in the composition or hardness of the rocks4 ,i should exceed the limits of this work1 were ,i to attempt to give a full description of all the geographical circumstances attending these singular terraces1 or to discuss the ingenious theories which have been severally proposed to account for them by ,dr4 ,mac,culloch1 ,sir ,t4 ,d4 ,lauder1 and ,messrs4 ,darwin1 ,agassiz1 ,milne1 and ,chambers4 ,there is one point1 however1 on which all are agreed1 namely1 that these shelves are ancient beaches1 or littoral formations accumulated round the edges of one or more sheets of water which once stood at the level1 first of the highest shelf1 and successively at the height of the two others4 ,it is well known1 that wherever a lake or marine fiord exists surrounded by steep mountains subject to disintegration by frost or the action of torrents1 some loose matter is washed down annually1 especially during the melting of snow1 and a check is given to the descent of this detritus at the point where it reaches the waters of the lake4 ,the waves then spread out the materials along the shore1 and throw some of them upon the beach2 their dispersing power being aided by the ice1 which often adheres to pebbles during the winter months1 and gives buoyancy to them4 ,the annexed diagram illustrates the manner in which ,dr4 ,mac,culloch and ,mr4 ,darwin suppose the roads to constitute mere indentations in a superficial alluvial coating which rests upon the hillside1 and consists chiefly of clay and sharp unrounded stones4 ,illustration3 ,fig4 #ajc4 ,cross section4 ,a ,b4 ,supposed original surface of rock4 ,c ,d4 ,roads or shelves in the outer alluvial covering of the hill4 ,among other proofs that the parallel roads have really been formed along the margin of a sheet of water1 it may be mentioned1 that wherever an isolated hill rises in the middle of the glen above the level of any particular shelf1 a corresponding shelf is seen at the same level passing round the hill1 as would have happened if it had once formed an island in a lake or fiord4 ,another very remarkable peculiarity in these terraces is this2 each of them comes in some portion of its course to a col1 or passage between the heads of glens1 the explanation of which will be considered in the sequel4 ,those writers who first advocated the doctrine that the roads were the ancient beaches of freshwater lakes1 were unable to offer any probable hypothesis respecting the formation and subsequent removal of barriers of sufficient height and solidity to dam up the water4 ,to introduce any violent convulsion for their removal was inconsistent with the uninterrupted horizontality of the roads1 and with the undisturbed aspect of those parts of the glens where the shelves come suddenly to an end4 ,mr4 ,agassiz and ,dr4 ,buckland1 desirous1 like the defenders of the lake theory1 to account for the limitation of the shelves to certain glens1 and their absence in contiguous glens1 where the rocks are of the same composition1 and the slope and inclination of the ground very similar1 started the conjecture that these valleys were once blocked up by enormous glaciers descending from ,ben ,nevis1 giving rise to what are called in ,switzerland and in the ,tyrol1 glacier-lakes4 ,after a time the icy barrier was broken down1 or melted1 first1 to the level of the second1 and afterwards to that of the third road or shelf4 ,in corroboration of this view1 they contended that the alluvium of ,glen ,roy1 as well as of other parts of ,scotland1 agrees in character with the moraines of glaciers seen in the ,alpine valleys of ,switzerland4 ,allusion will be made in the eleventh chapter to the former existence of glaciers in the ,grampians3 in the mean time it will readily be conceded that this hypothesis is preferable to any previous lacustrine theory1 by accounting more easily for the temporary existence and entire disappearance of lofty transverse barriers1 although the height required for the imaginary dams of ice may be startling4 ,before the idea last alluded to had been entertained1 ,mr4 ,darwin examined ,glen ,roy1 and came to the opinion that the shelves were formed when the glens were still arms of the sea1 and1 consequently1 that there never were any barriers4 ,according to him1 the land emerged during a slow and uniform upward movement1 like that now experienced throughout a large part of ,sweden and ,finland2 but there were certain pauses in the upheaving process1 at which times the waters of the sea remained stationary for so many centuries as to allow of the accumulation of an extraordinary quantity of detrital matter1 and the excavation1 at points immediately above1 of many deep notches and bare cliffs in the hard and solid rock4 ,the phenomena which are most difficult to reconcile with this theory are1 first1 the abrupt cessation of the roads at certain points in the different glens2 secondly1 their unequal number in different valleys connecting with each other1 there being three1 for example1 in ,glen ,roy and only one in ,glen ,spean2 thirdly1 the precise horizontality of level maintained by the same shelf over a space many leagues in length requiring us to assume1 that during a rise of #abej feet no one portion of the land was raised even a few yards above another2 fourthly1 the coincidence of level already alluded to of each shelf with a col1 or the point forming the head of two glens1 from which the rain-waters flow in opposite directions4 ,this last-mentioned feature in the physical geography of ,lochaber seems to have been explained in a satisfactory manner by ,mr4 ,darwin4 ,he calls these cols landstraits1 and regards them as having been anciently sounds or channels between islands4 ,he points out that there is a tendency in such sounds to be silted up1 and always the more so in proportion to their narrowness4 ,in a chart of the ,falkland ,islands by ,capt4 ,sullivan1 ,r4,n41 it appears that there are several examples there of straits where the soundings diminish regularly towards the narrowest part4 ,one is so nearly dry that it can be walked over at low water1 and another1 no longer covered by the sea1 is supposed to have recently dried up in consequence of a small shift in the relative level of sea and land4 ,similar straits1 observes ,mr4 ,chambers1 hovering1 in character1 between sea and land1 and which may be called fords1 are met with in the ,hebrides4 ,such1 for example1 is the passage dividing the islands of ,lewis and ,harris1 and that between ,north ,uist and ,benbecula1 both of which would undoubtedly appear as cols1 coinciding with a terrace or raised beach1 all round the islands1 if the sea were to subside4#hh-;,a ,the precise horizontality of level maintained by the roads or shelves of ,lochaber over an area many leagues in length and breadth1 is a difficulty common in some degree to all the rival hypotheses1 whether of lakes1 or glaciers1 or of the simple upheaval of the land above the sea4 ,for we cannot suppose the roads to be more ancient than the glacial period1 or the era of the boulder formation of ,scotland1 of which ,i shall speak in the eleventh and twelfth chapters4 ,strata of that era of marine origin containing northern shells of existing species have been found at various heights in ,scotland1 some on the east1 and others on the west coast1 from #bj to #djj feet high2 and in one region in ,lanarkshire not less than #ebd feet above high-water mark4 ,it seems1 therefore1 in the highest degree improbable that ,glen ,roy should have escaped entirely the upward movement experienced in so many surrounding regions1--a movement implied by the position of these marine deposits1 in which the shells are almost all of known recent species4 ,but if the motion has really extended to ,glen ,roy and the contiguous glens1 it must have uplifted them bodily1 without in the slightest degree affecting their horizontality2 and this being admitted1 the principal objection to the theory of marine beaches1 founded on the uniformity of upheaval1 is removed1 or is at least common to every theory hitherto proposed4 ,to assume that the ocean has gone down from the level of the uppermost shelf1 or #abej feet1 simultaneously all over the globe1 while the land remained unmoved1 is a view which will find favour with very few geologists1 for the reasons explained in the fifth chapter4 ,the student will perceive1 from the above sketch of the controversy respecting the formation of these curious shelves1 that this problem1 like many others in geology1 is as yet only solved in part2 and that a larger number of facts must be collected and reasoned upon before the question can be finally settled4 ,,footnotes3 #hb-;,a ,trimmer1 ,proceedings of ,geol4 ,soc4 vol4 iv4 p4 #g4 #ahdb4 #hc-;,a ,see ,lyell on ,sand-pipes1 c41 ,phil4 ,mag41 third series1 vol4 xv4 p4 #beg41 ,oct4 #ahci4 #hd-;,a ,principles of ,geology1 #gth ed4 p4 #ejf41 #hth ed4 #eji4 #he-;,a ,second ,visit to the ,u4 ,s4 vol4 ii4 chap4 #cd4 #hh-;,a ,ancient ,sea ,margins1 p4 #aad41 by ,r4 ,chambers4 ,,chapter ,,viii4 ,,chronological ,,classification ,,of ,,rocks4 ,aqueous1 plutonic1 volcanic1 and metamorphic rocks1 considered chronologically--,lehman's division into primitive and secondary--,werner's addition of a transition class--,neptunian theory--,hutton on igneous origin of granite--,how the name of primary was still retained for granite--,the term transition1 why faulty--,the adherence to the old chronological nomenclature retarded the progress of geology--,new hypothesis invented to reconcile the igneous origin of granite to the notion of its high antiquity--,explanation of the chronological nomenclature adopted in this work1 so far as regards primary1 secondary1 and tertiary periods4 ,in the first chapter it was stated that the four great classes of rocks1 the aqueous1 the volcanic1 the plutonic1 and the metamorphic1 would each be considered not only in reference to their mineral characters1 and mode of origin1 but also to their relative age4 ,the preservation of the shelves may have required1 says ,darwin1 the quick growth of green turf on a good soil2 their abrupt cessation may mark the place where the soil was barren1 and when a green sward formed slowly4 ,in regard to the aqueous rocks1 we have already seen that they are stratified1 that some are calcareous1 others argillaceous or siliceous1 some made up of sand1 others of pebbles2 that some contain freshwater1 others marine fossils1 and so forth2 but the student has still to learn which rocks1 exhibiting some or all of these characters1 have originated at one period of the earth's history1 and which at another4 ,to determine this point in reference to the fossiliferous formations is more easy than in any other class1 and it is therefore the most convenient and natural method to begin by establishing a chronology for these fossiliferous strata1 and then to endeavour to refer to the same divisions1 the several groups of plutonic1 volcanic1 and metamorphic rocks4 ,this system of classification is not only recommended by its greater clearness and facility of application1 but is also best fitted to strike the imagination by bringing into one view the past changes of the inorganic world1 and the contemporaneous revolutions of the organic creation4 ,for the sedimentary formations of successive periods are most readily distinguished by the different species of fossil animals and plants which they inclose1 and of which one race after another has flourished and then disappeared from the earth4 ,but before entering specially on the subdivisions of the aqueous rocks arranged according to the order of time1 it will be desirable to say a few words on the chronology of rocks in general1 although in doing so we shall be unavoidably led to allude to some classes of phenomena which the beginner must not yet expect fully to comprehend4 ,it was for many years a received opinion1 that the formation of entire families of rocks1 such as the plutonic and those crystalline schists spoken of in the first chapter as metamorphic1 began and ended before any members of the aqueous and volcanic orders were produced2 and although this idea has long been modified1 and is nearly exploded1 it will be necessary to give some account of the ancient doctrine1 in order that beginners may understand whence many prevailing opinions1 and some part of the nomenclature of geology1 still partially in use1 was derived4 ,about the middle of the last century1 ,lehman1 a ,german miner1 proposed to divide rocks into three classes1 the first and oldest to be called primitive1 comprising the hypogene1 or plutonic and metamorphic rocks2 the next to be termed secondary1 comprehending the aqueous or fossiliferous strata2 and the remainder1 or third class1 corresponding to our alluvium1 ancient and modern1 which he referred to local floods1 and the deluge of ,noah4 ,in the primitive class1 he said1 such as granite and gneiss1 there are no organic remains1 nor any signs of materials derived from the ruins of pre-existing rocks4 ,their origin1 therefore1 may have been purely chemical1 antecedent to the creation of living beings1 and probably coeval with the birth of the world itself4 ,the secondary formations1 on the contrary1 which often contain sand1 pebbles1 and organic remains1 must have been mechanical deposits1 produced after the planet had become the habitation of animals and plants4 ,this bold generalization1 although anticipated in some measure by ,steno1 a century before1 in ,italy1 formed at the time an important step in the progress of geology1 and sketched out correctly some of the leading divisions into which rocks may be separated4 ,about half a century later1 ,werner1 so justly celebrated for his improved methods of discriminating the mineralogical characters of rocks1 attempted to improve ,lehman's classification1 and with this view intercalated a class1 called by him the transition formations1 between the primitive and secondary4 ,between these last he had discovered1 in northern ,germany1 a series of strata1 which in their mineral peculiarities were of an intermediate character1 partaking in some degree of the crystalline nature of micaceous schist and clay-slate1 and yet exhibiting here and there signs of a mechanical origin and organic remains4 ,for this group1 therefore1 forming a passage between ,lehman's primitive and secondary rocks1 the name of uebergang or transition was proposed4 ,they consisted principally of clay-slate and an argillaceous sandstone1 called grauwacke1 and partly of calcareous beds4 ,it happened in the district which ,werner first investigated1 that both the primitive and transition strata were highly inclined1 while the beds of the newer fossiliferous rocks1 the secondary of ,lehman1 were horizontal4 ,to these latter1 therefore1 he gave the name floetz1 or a level floor2 and every deposit more modern than the chalk1 which was classed as the uppermost of the floetz series1 was designated the overflowed land1 an expression which may be regarded as equivalent to alluvium1 although under this appellation were confounded all the strata afterwards called tertiary1 of which ,werner had scarcely any knowledge4 ,as the followers of ,werner soon discovered that the inclined position of the transition beds1 and the horizontality of the floetz1 or newer fossiliferous strata1 were mere local accidents1 they soon abandoned the term floetz2 and the four divisions of the ,wernerian school were then named primitive1 transition1 secondary1 and alluvial4 ,as to the trappean rocks1 although their igneous origin had been already demonstrated by ,arduino1 ,fortis1 ,faujas1 and others1 and especially by ,desmarest1 they were all regarded by ,werner as aqueous1 and as mere subordinate members of the secondary series4#ia-;,a ,this theory of ,werner's was called the ,neptunian1 and for many years enjoyed much popularity4 ,it assumed that the globe had been at first invested by an universal chaotic ocean1 holding the materials of all rocks in solution4 ,from the waters of this ocean1 granite1 gneiss1 and other crystalline formations1 were first precipitated2 and afterwards1 when the waters were purged of these ingredients1 and more nearly resembled those of our actual seas1 the transition strata were deposited4 ,these were of a mixed character1 not purely chemical1 because the waves and currents had already begun to wear down solid land1 and to give rise to pebbles1 sand1 and mud2 nor entirely without fossils1 because a few of the first marine animals had begun to exist4 ,after this period1 the secondary formations were accumulated in waters resembling those of the present ocean1 except at certain intervals1 when1 from causes wholly unexplained1 a partial recurrence of the chaotic fluid took place1 during which various trap rocks1 some highly crystalline1 were formed4 ,this arbitrary hypothesis rejected all intervention of igneous agency1 volcanos being regarded as modern1 partial1 and superficial accidents1 of trifling account among the great causes which have modified the external structure of the globe4 ,meanwhile ,hutton1 a contemporary of ,werner1 began to teach1 in ,scotland1 that granite as well as trap was of igneous origin1 and had at various periods intruded itself in a fluid state into different parts of the earth's crust4 ,he recognized and faithfully described many of the phenomena of granitic veins1 and the alterations produced by them on the invaded strata1 which will be treated of in the thirty-second chapter4 ,he1 moreover1 advanced the opinion1 that the crystalline strata called primitive had not been precipitated from a primaeval ocean1 but were sedimentary strata altered by heat4 ,in his writings1 therefore1 and in those of his illustrator1 ,playfair1 we find the germ of that metamorphic theory which has been already hinted at in the first chapter1 and which will be more fully expounded in the thirty-fourth and thirty-fifth chapters4 ,at length1 after much controversy1 the doctrine of the igneous origin of trap and granite made its way into general favour2 but although it was1 in consequence1 admitted that both granite and trap had been produced at many successive periods1 the term primitive or primary still continued to be applied to the crystalline formations in general1 whether stratified1 like gneiss1 or unstratified1 like granite4 ,the pupil was told that granite was a primary rock1 but that some granites were newer than certain secondary formations2 and in conformity with the spirit of the ancient language1 to which the teacher was still determined to adhere1 a desire was naturally engendered of extenuating the importance of those more modern granites1 the true dates of which new observations were continually bringing to light4 ,a no less decided inclination was shown to persist in the use of the term transition1 after it had been proved to be almost as faulty in its original application as that of floetz4 ,the name of transition1 as already stated1 was first given by ,werner1 to designate a mineral character1 intermediate between the highly crystalline or metamorphic state and that of an ordinary fossiliferous rock4 ,but the term acquired also from the first a chronological import1 because it had been appropriated to sedimentary formations1 which1 in the ,hartz and other parts of ,germany1 were more ancient than the oldest of the secondary series1 and were characterized by peculiar fossil zoophytes and shells4 ,when1 therefore1 geologists found in other districts stratified rocks occupying the same position1 and inclosing similar fossils1 they gave to them also the name of transition1 according to rules which will be explained in the next chapter2 yet1 in many cases1 such rocks were found not to exhibit the same mineral texture which ,werner had called transition4 ,on the contrary1 many of them were not more crystalline than different members of the secondary class2 while1 on the other hand1 these last were sometimes found to assume a semi-crystalline and almost metamorphic aspect1 and thus1 on lithological grounds1 to deserve equally the name of transition4 ,so remarkably was this the case in the ,swiss ,alps1 that certain rocks1 which had for years been regarded by some of the most skilful disciples of ,werner to be transition1 were at last acknowledged1 when their relative position and fossils were better understood1 to belong to the newest of the secondary groups2 nay1 some of them have actually been discovered to be members of the lower tertiary series6 ,if1 under such circumstances1 the name of transition was retained1 it is clear that it ought to have been applied without reference to the age of strata1 and simply as expressive of a mineral peculiarity4 ,the continued appropriation of the term to formations of a given date1 induced geologists to go on believing that the ancient strata so designated bore a less resemblance to the secondary than is really the case1 and to imagine that these last never pass1 as they frequently do1 into metamorphic rocks4 ,the poet ,waller1 when lamenting over the antiquated style of ,chaucer1 complains that-- ,we write in sand1 our language grows1 ,and1 like the tide1 our work o'erflows4 ,but the reverse is true in geology2 for here it is our work which continually outgrows the language4 ,the tide of observation advances with such speed that improvements in theory outrun the changes of nomenclature2 and the attempt to inculcate new truths by words invented to express a different or opposite opinion1 tends constantly1 by the force of association1 to perpetuate error2 so that dogmas renounced by the reason still retain a strong hold upon the imagination4 ,in order to reconcile the old chronological views with the new doctrine of the igneous origin of granite1 the following hypothesis was substituted for that of the ,neptunists4 ,instead of beginning with an aqueous menstruum or chaotic fluid1 the materials of the present crust of the earth were supposed to have been at first in a state of igneous fusion1 until part of the heat having been diffused into surrounding space1 the surface of the fluid consolidated1 and formed a crust of granite4 ,this covering of crystalline stone1 which afterwards grew thicker and thicker as it cooled1 was so hot1 at first1 that no water could exist upon it2 but as the refrigeration proceeded1 the aqueous vapour in the atmosphere was condensed1 and1 falling in rain1 gave rise to the first thermal ocean4 ,so high was the temperature of this boiling sea1 that no aquatic beings could inhabit its waters1 and its deposits were not only devoid of fossils1 but1 like those of some hot springs1 were highly crystalline4 ,hence the origin of the primary or crystalline strata1--gneiss1 mica-schist1 and the rest4 ,afterwards1 when the granitic crust had been partially broken up1 land and mountains began to rise above the waters1 and rains and torrents ground down rock1 so that sediment was spread over the bottom of the seas4 ,yet the heat still remaining in the solid supporting substances was sufficient to increase the chemical action exerted by the water1 although not so intense as to prevent the introduction and increase of some living beings4 ,during this state of things some of the residuary mineral ingredients of the primaeval ocean were precipitated1 and formed deposits 7the transition strata of ,werner71 half chemical and half mechanical1 and containing a few fossils4 ,by this new theory1 which was in part a revival of the doctrine of ,leibnitz1 published in #afhj1 on the igneous origin of the planet1 the old ideas respecting the priority of all crystalline rocks to the creation of organic beings1 were still preserved2 and the mistaken notion that all the semi-crystalline and partially fossiliferous rocks belonged to one period1 while all the earthy and uncrystalline formations originated at a subsequent epoch1 was also perpetuated4 ,it may or may not be true1 as the great ,leibnitz imagined1 that the whole planet was once in a state of liquefaction by heat2 but there are certainly no geological proofs that the granite which constitutes the foundation of so much of the earth's crust was ever at once in a state of universal fusion4 ,on the contrary1 all our evidence tends to show that the formation of granite1 like the deposition of the stratified rocks1 has been successive1 and that different portions of granite have been in a melted state at distinct and often distant periods4 ,one mass was solid1 and had been fractured1 before another body of granitic matter was injected into it1 or through it1 in the form of veins4 ,some granites are more ancient than any known fossiliferous rocks2 others are of secondary2 and some1 such as that of ,mont ,blanc and part of the central axis of the ,alps1 of tertiary origin4 ,in short1 the universal fluidity of the crystalline foundations of the earth's crust1 can only be understood in the same sense as the universality of the ancient ocean4 ,all the land has been under water1 but not all at one time2 so all the subterranean unstratified rocks to which man can obtain access have been melted1 but not simultaneously4 ,in the present work the four great classes of rocks1 the aqueous1 plutonic1 volcanic1 and metamorphic1 will form four parallel1 or nearly parallel1 columns in one chronological table4 ,they will be considered as four sets of monuments relating to four contemporaneous1 or nearly contemporaneous1 series of events4 ,i shall endeavour1 in a subsequent chapter on the plutonic rocks1 to explain the manner in which certain masses belonging to each of the four classes of rocks may have originated simultaneously at every geological period1 and how the earth's crust may have been continually remodelled1 above and below1 by aqueous and igneous causes1 from times indefinitely remote4 ,in the same manner as aqueous and fossiliferous strata are now formed in certain seas or lakes1 while in other places volcanic rocks break out at the surface1 and are connected with reservoirs of melted matter at vast depths in the bowels of the earth1--so1 at every era of the past1 fossiliferous deposits and superficial igneous rocks were in progress contemporaneously with others of subterranean and plutonic origin1 and some sedimentary strata were exposed to heat and made to assume a crystalline or metamorphic structure4 ,it can by no means be taken for granted1 that during all these changes the solid crust of the earth has been increasing in thickness4 ,it has been shown1 that so far as aqueous action is concerned1 the gain by fresh deposits1 and the loss by denudation1 must at each period have been equal 7see above1 p4 #fh472 and in like manner1 in the inferior portion of the earth's crust1 the acquisition of new crystalline rocks1 at each successive era1 may merely have counter-balanced the loss sustained by the melting of materials previously consolidated4 ,as to the relative antiquity of the crystalline foundations of the earth's crust1 when compared to the fossiliferous and volcanic rocks which they support1 ,i have already stated1 in the first chapter1 that to pronounce an opinion on this matter is as difficult as at once to decide which of the two1 whether the foundations or superstructure of an ancient city built on wooden piles1 may be the oldest4 ,we have seen that1 to answer this question1 we must first be prepared to say whether the work of decay and restoration had gone on most rapidly above or below1 whether the average duration of the piles has exceeded that of the stone buildings1 or the contrary4 ,so also in regard to the relative age of the superior and inferior portions of the earth's crust2 we cannot hazard even a conjecture on this point1 until we know whether1 upon an average1 the power of water above1 or that of heat below1 is most efficacious in giving new forms to solid matter4 ,after the observations which have now been made1 the reader will perceive that the term primary must either be entirely renounced1 or1 if retained1 must be differently defined1 and not made to designate a set of crystalline rocks1 some of which are already ascertained to be newer than all the secondary formations4 ,in this work ,i shall follow most nearly the method proposed by ,mr4 ,boue1 who has called all fossiliferous rocks older than the secondary by the name of primary4 ,to prevent confusion1 however1 ,i shall always speak of these1 when they are of the aqueous class1 as the primary fossiliferous formations1 because the word primary has hitherto been almost inseparably connected with the idea of a non-fossiliferous rock4 ,if we can prove any plutonic1 volcanic1 or metamorphic rocks to be older than the secondary formations1 such rocks will also be primary1 according to this system4 ,mr4 ,boue having with great propriety excluded the metamorphic rocks1 as a class1 from the primary formations1 proposed to call them all crystalline schists4 ,as there are secondary fossiliferous strata1 so we shall find that there are plutonic1 volcanic1 and metamorphic rocks of contemporaneous origin1 which ,i shall also term secondary4 ,in the next chapter it will be shown that the strata above the chalk have been called tertiary4 ,if1 therefore1 we discover any volcanic1 plutonic1 or metamorphic rocks1 which have originated since the deposition of the chalk1 these also will rank as tertiary formations4 ,it may perhaps be suggested that some metamorphic strata1 and some granites1 may be anterior in date to the oldest of the primary fossiliferous rocks4 ,this opinion is doubtless true1 and will be discussed in future chapters2 but ,i may here observe1 that when we arrange the four classes of rocks in four parallel columns in one table of chronology1 it is by no means assumed that these columns are all of equal length2 one may begin at an earlier period than the rest1 and another may come down to a later point of time4 ,in the small part of the globe hitherto examined1 it is hardly to be expected that we should have discovered either the oldest or the newest members of each of the four classes of rocks4 ,thus1 if there be primary1 secondary1 and tertiary rocks of the aqueous or fossiliferous class1 and in like manner primary1 secondary1 and tertiary hypogene formations1 we may not be yet acquainted with the most ancient of the primary fossiliferous beds1 or with the newest of the hypogene4 ,,footnotes3 #ia-;,a ,see ,principles1 vol4 i4 chap4 iv4 ,,chapter ,,ix4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,aqueous ,,rocks4 ,on the three principal tests of relative age--superposition1 mineral character1 and fossils--,change of mineral character and fossils in the same continuous formation--,proofs that distinct species of animals and plants have lived at successive periods--,distinct provinces of indigenous species--,great extent of single provinces--,similar laws prevailed at successive geological periods--,relative importance of mineral and palaeontological characters--,test of age by included fragments--,frequent absence of strata of intervening periods--,principal groups of strata in western ,europe4 ,in the last chapter ,i spoke generally of the chronological relations of the four great classes of rocks1 and ,i shall now treat of the aqueous rocks in particular1 or of the successive periods at which the different fossiliferous formations have been deposited4 ,there are three principal tests by which we determine the age of a given set of strata2 first1 superposition2 secondly1 mineral character2 and1 thirdly1 organic remains4 ,some aid can occasionally be derived from a fourth kind of proof1 namely1 the fact of one deposit including in it fragments of a pre-existing rock1 by which the relative ages of the two may1 even in the absence of all other evidence1 be determined4 ,superposition4--,the first and principal test of the age of one aqueous deposit1 as compared to another1 is relative position4 ,it has been already stated1 that where strata are horizontal1 the bed which lies uppermost is the newest of the whole1 and that which lies at the bottom the most ancient4 ,so1 of a series of sedimentary formations1 they are like volumes of history1 in which each writer has recorded the annals of his own times1 and then laid down the book1 with the last written page uppermost1 upon the volume in which the events of the era immediately preceding were commemorated4 ,in this manner a lofty pile of chronicles is at length accumulated2 and they are so arranged as to indicate1 by their position alone1 the order in which the events recorded in them have occurred4 ,in regard to the crust of the earth1 however1 there are some regions where1 as the student has already been informed1 the beds have been disturbed1 and sometimes extensively thrown over and turned upside down4 7,see pp4 #eh1 #ei47 ,but an experienced geologist can rarely be deceived by these exceptional cases4 ,when he finds that the strata are fractured1 curved1 inclined1 or vertical1 he knows that the original order of superposition must be doubtful1 and he then endeavours to find sections in some neighbouring district where the strata are horizontal1 or only slightly inclined4 ,here the true order of sequence of the entire series of deposits being ascertained1 a key is furnished for settling the chronology of those strata where the displacement is extreme4 ,mineral character4--,the same rocks may often be observed to retain for miles1 or even hundreds of miles1 the same mineral peculiarities1 if we follow the planes of stratification1 or trace the beds1 if they be undisturbed1 in a horizontal direction4 ,but if we pursue them vertically1 or in any direction transverse to the planes of stratification1 this uniformity ceases almost immediately4 ,in that case we can scarcely ever penetrate a stratified mass for a few hundred yards without beholding a succession of extremely dissimilar1 calcareous1 argillaceous1 and siliceous rocks4 ,these phenomena lead to the conclusion1 that rivers and currents have dispersed the same sediment over wide areas at one period1 but at successive periods have been charged1 in the same region1 with very different kinds of matter4 ,the first observers were so astonished at the vast spaces over which they were able to follow the same homogeneous rocks in a horizontal direction1 that they came hastily to the opinion1 that the whole globe had been environed by a succession of distinct aqueous formations1 disposed round the nucleus of the planet1 like the concentric coats of an onion4 ,but although1 in fact1 some formations may be continuous over districts as large as half of ,europe1 or even more1 yet most of them either terminate wholly within narrower limits1 or soon change their lithological character4 ,sometimes they thin out gradually1 as if the supply of sediment had failed in that direction1 or they come abruptly to an end1 as if we had arrived at the borders of the ancient sea or lake which served as their receptacle4 ,it no less frequently happens that they vary in mineral aspect and composition1 as we pursue them horizontally4 ,for example1 we trace a limestone for a hundred miles1 until it becomes more arenaceous1 and finally passes into sand1 or sandstone4 ,we may then follow this sandstone1 already proved by its continuity to be of the same age1 throughout another district a hundred miles or more in length4 ,organic remains4--,this character must be used as a criterion of the age of a formation1 or of the contemporaneous origin of two deposits in distant places1 under very much the same restrictions as the test of mineral composition4 ,first1 the same fossils may be traced over wide regions1 if we examine strata in the direction of their planes1 although by no means for indefinite distances4 ,secondly1 while the same fossils prevail in a particular set of strata for hundreds of miles in a horizontal direction1 we seldom meet with the same remains for many fathoms1 and very rarely for several hundred yards1 in a vertical line1 or a line transverse to the strata4 ,this fact has now been verified in almost all parts of the globe1 and has led to a conviction1 that at successive periods of the past1 the same area of land and water has been inhabited by species of animals and plants even more distinct than those which now people the antipodes1 or which now co-exist in the arctic1 temperate1 and tropical zones4 ,it appears1 that from the remotest periods there has been ever a coming in of new organic forms1 and an extinction of those which pre-existed on the earth2 some species having endured for a longer1 others for a shorter1 time2 while none have ever reappeared after once dying out4 ,the law which has governed the creation and extinction of species seems to be expressed in the verse of the poet1-- ,natura il fece1 e poi ruppe la stampa4 ,,ariosto4 ,nature made him1 and then broke the die4 ,and this circumstance it is1 which confers on fossils their highest value as chronological tests1 giving to each of them1 in the eyes of the geologist1 that authority which belongs to contemporary medals in history4 ,the same cannot be said of each peculiar variety of rock2 for some of these1 as red marl and red sandstone1 for example1 may occur at once at the top1 bottom1 and middle of the entire sedimentary series2 exhibiting in each position so perfect an identity of mineral aspect as to be undistinguishable4 ,such exact repetitions1 however1 of the same mixtures of sediment have not often been produced1 at distant periods1 in precisely the same parts of the globe2 and even where this has happened1 we are seldom in any danger of confounding together the monuments of remote eras1 when we have studied their imbedded fossils and relative position4 ,it was remarked that the same species of organic remains cannot be traced horizontally1 or in the direction of the planes of stratification for indefinite distances4 ,this might have been expected from analogy2 for when we inquire into the present distribution of living beings1 we find that the habitable surface of the sea and land may be divided into a considerable number of distinct provinces1 each peopled by a peculiar assemblage of animals and plants4 ,in the ,principles of ,geology1 ,i have endeavoured to point out the extent and probable origin of these separate divisions2 and it was shown that climate is only one of many causes on which they depend1 and that difference of longitude as well as latitude is generally accompanied by a dissimilarity of indigenous species4 ,as different seas1 therefore1 and lakes are inhabited at the same period1 by different aquatic animals and plants1 and as the lands adjoining these may be peopled by distinct terrestrial species1 it follows that distinct fossils will be imbedded in contemporaneous deposits4 ,if it were otherwise--if the same species abounded in every climate1 or in every part of the globe where1 so far as we can discover1 a corresponding temperature and other conditions favourable to their existence are found--the identification of mineral masses of the same age1 by means of their included organic contents1 would be a matter of still greater certainty4 ,nevertheless1 the extent of some single zoological provinces1 especially those of marine animals1 is very great2 and our geological researches have proved that the same laws prevailed at remote periods2 for the fossils are often identical throughout wide spaces1 and in a great number of detached deposits1 in which the mineral nature of the rocks is variable4 ,the doctrine here laid down will be more readily understood1 if we reflect on what is now going on in the ,mediterranean4 ,that entire sea may be considered as one zoological province2 for1 although certain species of testacea and zoophytes may be very local1 and each region has probably some species peculiar to it1 still a considerable number are common to the whole ,mediterranean4 ,if1 therefore1 at some future period1 the bed of this inland sea should be converted into land1 the geologist might be enabled1 by reference to organic remains1 to prove the contemporaneous origin of various mineral masses scattered over a space equal in area to the half of ,europe4 ,deposits1 for example1 are well known to be now in progress in this sea in the deltas of the ,po1 ,rhone1 ,nile1 and other rivers1 which differ as greatly from each other in the nature of their sediment as does the composition of the mountains which they drain4 ,there are also other quarters of the ,mediterranean1 as off the coast of ,campania1 or near the base of ,etna1 in ,sicily1 or in the ,grecian ,archipelago1 where another class of rocks is now forming2 where showers of volcanic ashes occasionally fall into the sea1 and streams of lava overflow its bottom2 and where1 in the intervals between volcanic eruptions1 beds of sand and clay are frequently derived from the waste of cliffs1 or the turbid waters of rivers4 ,limestones1 moreover1 such as the ,italian travertins1 are here and there precipitated from the waters of mineral springs1 some of which rise up from the bottom of the sea4 ,in all these detached formations1 so diversified in their lithological characters1 the remains of the same shells1 corals1 crustacea1 and fish are becoming inclosed2 or1 at least1 a sufficient number must be common to the different localities to enable the zoologist to refer them all to one contemporaneous assemblage of species4 ,there are1 however1 certain combinations of geographical circumstances which cause distinct provinces of animals and plants to be separated from each other by very narrow limits2 and hence it must happen1 that strata will be sometimes formed in contiguous regions1 differing widely both in mineral contents and organic remains4 ,thus1 for example1 the testacea1 zoophytes1 and fish of the ,red ,sea are1 as a group1 extremely distinct from those inhabiting the adjoining parts of the ,mediterranean1 although the two seas are separated only by the narrow isthmus of ,suez4 ,of the bivalve shells1 according to ,philippi1 not more than a fifth are common to the ,red ,sea and the sea around ,sicily1 while the proportion of univalves 7or ,gasteropoda7 is still smaller1 not exceeding eighteen in a hundred4 ,calcareous formations have accumulated on a great scale in the ,red ,sea in modern times1 and fossil shells of existing species are well preserved therein2 and we know that at the mouth of the ,nile large deposits of mud are amassed1 including the remains of ,mediterranean species4 ,it follows1 therefore1 that if at some future period the bed of the ,red ,sea should be laid dry1 the geologist might experience great difficulties in endeavouring to ascertain the relative age of these formations1 which1 although dissimilar both in organic and mineral characters1 were of synchronous origin4 ,but1 on the other hand1 we must not forget that the north-western shores of the ,arabian ,gulf1 the plains of ,egypt1 and the isthmus of ,suez1 are all parts of one province of terrestrial species4 ,small streams1 therefore1 occasional land-floods1 and those winds which drift clouds of sand along the deserts1 might carry down into the ,red ,sea the same shells of fluviatile and land testacea which the ,nile is sweeping into its delta1 together with some remains of terrestrial plants and the bones of quadrupeds1 whereby the groups of strata1 before alluded to1 might1 notwithstanding the discrepancy of their mineral composition and marine organic fossils1 be shown to have belonged to the same epoch4 ,yet while rivers may thus carry down the same fluviatile and terrestrial spoils into two or more seas inhabited by different marine species1 it will much more frequently happen1 that the co-existence of terrestrial species of distinct zoological and botanical provinces will be proved by the identity of the marine beings which inhabited the intervening space4 ,thus1 for example1 the land quadrupeds and shells of the south of ,europe1 north of ,africa1 and north-west of ,asia1 are different1 yet their remains are all washed down by rivers flowing from these three countries into the ,mediterranean4 ,in some parts of the globe1 at the present period1 the line of demarcation between distinct provinces of animals and plants is not very strongly marked1 especially where the change is determined by temperature1 as in seas extending from the temperate to the tropical zone1 or from the temperate to the arctic regions4 ,here a gradual passage takes place from one set of species to another4 ,in like manner the geologist1 in studying particular formations of remote periods1 has sometimes been able to trace the gradation from one ancient province to another1 by observing carefully the fossils of all the intermediate places4 ,his success in thus acquiring a knowledge of the zoological or botanical geography of very distant eras has been mainly owing to this circumstance1 that the mineral character has no tendency to be affected by climate4 ,a large river may convey yellow or red mud into some part of the ocean1 where it may be dispersed by a current over an area several hundred leagues in length1 so as to pass from the tropics into the temperate zone4 ,if the bottom of the sea be afterwards upraised1 the organic remains imbedded in such yellow or red strata may indicate the different animals or plants which once inhabited at the same time the temperate and equatorial regions4 ,it may be true1 as a general rule1 that groups of the same species of animals and plants may extend over wider areas than deposits of homogeneous composition2 and if so1 palaeontological characters will be of more importance in geological classification than mineral composition2 but it is idle to discuss the relative value of these tests1 as the aid of both is indispensable1 and it fortunately happens1 that where the one criterion fails1 we can often avail ourselves of the other4 ,test by included fragments of older rocks4--,it was stated1 that independent proof may sometimes be obtained of the relative date of two formations1 by fragments of an older rock being included in a newer one4 ,this evidence may sometimes be of great use1 where a geologist is at a loss to determine the relative age of two formations from want of clear sections exhibiting their true order of position1 or because the strata of each group are vertical4 ,in such cases we sometimes discover that the more modern rock has been in part derived from the degradation of the older4 ,thus1 for example1 we may find in one part of a country chalk with flints2 and1 in another1 a distinct formation1 consisting of alternations of clay1 sand1 and pebbles4 ,if some of these pebbles consist of similar flint and fossil shells1 sponges1 and foraminiferae1 of the same species as those in the chalk1 we may confidently infer that the chalk is the oldest of the two formations4 ,chronological groups4--,the number of groups into which the fossiliferous strata may be separated are more or less numerous1 according to the views of classification which different geologists entertain2 but when we have adopted a certain system of arrangement1 we immediately find that a few only of the entire series of groups occur one upon the other in any single section or district4 ,illustration3 ,fig4 #ajd4 ,block section4 ,the thinning out of individual strata was before described 7p4 #af474 ,but let the annexed diagram represent seven fossiliferous groups1 instead of as many strata4 ,it will then be seen that in the middle all the superimposed formations are present2 but in consequence of some of them thinning out1 ,no4 #b4 and ,no4 #e4 are absent at one extremity of the section1 and ,no4 #d4 at the other4 ,illustration3 ,fig4 #aje4 ,section ,south of ,bristol4 ,a4 ,c4 ,ramsay4 ,length of section #d miles4 a1 b4 ,level of the sea4 #a4 ,inferior oolite4 #b4 ,lias4 #c4 ,new red sandstone4 #d4 ,magnesian conglomerate4 #e4 ,coal measure4 #f4 ,carboniferous limestone4 #g4 ,old red sandstone4 ,in the annexed diagram1 fig4 #aje41 a real section of the geological formations in the neighbourhood of ,bristol and the ,mendip ,hills1 is presented to the reader as laid down on a true scale by ,professor ,ramsay1 where the newer groups #a1 #b1 #c1 #d4 rest unconformably on the formations #e and #f4 ,here at the southern end of the line of section we meet with the beds ,no4 #c4 7the ,new ,red ,sandstone7 resting immediately on ,no4 #f41 while farther north1 as at ,dundry ,hill1 we behold six groups superimposed one upon the other1 comprising all the strata from the inferior oolite to the coal and carboniferous limestone4 ,the limited extension of the groups #a and #b4 is owing to denudation1 as these formations end abruptly1 and have left outlying patches to attest the fact of their having originally covered a much wider area4 ,in many instances1 however1 the entire absence of one or more formations of intervening periods between two groups1 such as #c4 and #e4 in the same section1 arises1 not from the destruction of what once existed1 but because no strata of an intermediate age were ever deposited on the inferior rock4 ,they were not formed at that place1 either because the region was dry land during the interval1 or because it was part of a sea or lake to which no sediment was carried4 ,in order1 therefore1 to establish a chronological succession of fossiliferous groups1 a geologist must begin with a single section1 in which several sets of strata lie one upon the other4 ,he must then trace these formations1 by attention to their mineral character and fossils1 continuously1 as far as possible1 from the starting point4 ,as often as he meets with new groups1 he must ascertain by superposition their age relatively to those first examined1 and thus learn how to intercalate them in a tabular arrangement of the whole4 ,by this means the ,german1 ,french1 and ,english geologists have determined the succession of strata throughout a great part of ,europe1 and have adopted pretty generally the following groups1 almost all of which have their representatives in the ,british ,islands4 ,groups of ,fossiliferous ,strata observed in ,western ,europe1 arranged in what is termed a descending ,series1 or beginning with the newest4 7,see a more detailed ,tabular view1 pp4 #cfj4 #cfe47 #a4 ,post-,pliocene1 including those of the ,recent1 or human period4 #b4 ,newer ,pliocene1 or ,pleistocene4 #c4 ,older ,pliocene4 ,tertiary1 ,supracretaceous#ajc-;,a1 #d4 ,miocene4 or ,cainozoic4#ajc-;,b #e4 ,eocene4 #f4 ,chalk4 #g4 ,greensand4 #h4 ,wealden4 #i4 ,upper ,oolite4 ,secondary1 or ,mesozoic4#ajc-;,b #aj4 ,middle ,oolite4 #aa4 ,lower ,oolite4 #ab4 ,lias4 #ac4 ,trias4 #ad4 ,permian4 #ae4 ,coal4 #af4 ,old ,red sandstone1 or ,devonian4 ,primary fossiliferous1 #ag4 ,upper ,silurian4 or paleozoic4#ajc-;,b #ah4 ,lower ,silurian4 #ai4 ,cambrian and older fossiliferous strata4 ,it is not pretended that the three principal sections in the above table1 called primary1 secondary1 and tertiary1 are of equivalent importance1 or that the eighteen subordinate groups comprise monuments relating to equal portions of past time1 or of the earth's history4 ,but we can assert that they each relate to successive periods1 during which certain animals and plants1 for the most part peculiar to their respective eras1 have flourished1 and during which different kinds of sediment were deposited in the space now occupied by ,europe4 ,if we were disposed1 on palaeontological grounds#ajc-;,c1 to divide the entire fossiliferous series into a few groups less numerous than those in the above table1 and more nearly co-ordinate in value than the sections called primary1 secondary1 and tertiary1 we might1 perhaps1 adopt the six groups or periods given in the next table 7p4 #ajd474 ,at the same time1 ,i may observe1 that1 in the present state of the science1 when we have not yet compared the evidence derivable from all classes of fossils1 not even those most generally distributed1 such as shells1 corals1 and fish1 such generalizations are premature1 and can only be regarded as conjectural or provisional schemes for the founding of large natural groups4 ,fossiliferous ,strata of ,western ,europe divided into ,six ,groups4 #a4 ,post ,pliocene and from the ,post-,pliocene to the ,tertiary ,eocene inclusive4 #b4 ,cretaceous from the ,maestricht ,chalk to the ,lower ,greensand inclusive4 #c4 ,oolitic from the ,wealden to the ,lias inclusive4 #d4 ,triassic including the ,keuper1 ,muschelkalk1 and ,bunter ,sandstein of the ,germans4 #e4 ,permian1 ,carboniferous1 including ,magnesian ,limestone 7,zechstein71 and ,devonian ,coal1 ,mountain ,limestone1 and ,old ,red sandstone4 #f4 ,silurian and ,cambrian from the ,upper ,silurian to the oldest fossiliferous rocks inclusive4 ,,footnotes3 #ajc-;,a ,for tertiary1 ,sir ,h4 ,de la ,beche has used the term supracretaceous1 a name implying that the strata so called are superior in position to the chalk4 #ajc-;,b ,professor ,phillips has adopted these terms3 ,cainozoic1 from kainos1 cainos1 recent1 and zoon1 zoon1 animal2 ,mesozoic1 from mesos1 mesos1 middle1 c42 ,paleozoic1 from palaios1 palaios1 ancient1 c4 #ajc-;,c ,palaeontology is the science which treats of fossil remains1 both animal and vegetable4 ,etym4 palaios1 palaios1 ancient1 onta1 onta1 beings1 and logos1 logos1 a discourse4 ,,chapter ,x4 ,,classification ,,of ,,tertiary ,,formations4--,,post-,,pliocene ,,group4 ,general principles of classification of tertiary strata--,detached formations scattered over ,europe--,strata of ,paris and ,london--,more modern groups--,peculiar difficulties in determining the chronology of tertiary formations--,increasing proportion of living species of shells in strata of newer origin--,terms ,eocene1 ,miocene1 and ,pliocene--,post-,pliocene strata--,recent or human period--,older ,post-,pliocene formations of ,naples1 ,uddevalla1 and ,norway--,ancient upraised delta of the ,mississippi--,loess of the ,rhine4 ,before describing the most modern of the sets of strata enumerated in the tables given at the end of the last chapter1 it will be necessary to say something generally of the mode of classifying the formations called tertiary4 ,the name of tertiary has been given to them1 because they are all posterior in date to the rocks termed secondary1 of which the chalk constitutes the newest group4 ,these tertiary strata were at first confounded1 as before stated1 p4 #ia41 with the superficial alluviums of ,europe2 and it was long before their real extent and thickness1 and the various ages to which they belong1 were fully recognized4 ,they were observed to occur in patches1 some of freshwater1 others of marine origin1 their geographical area being usually small as compared to the secondary formations1 and their position often suggesting the idea of their having been deposited in different bays1 lakes1 estuaries1 or inland seas1 after a large portion of the space now occupied by ,europe had already been converted into dry land4 ,the first deposits of this class1 of which the characters were accurately determined1 were those occurring in the neighbourhood of ,paris1 described in #ahaj by ,,mm4 ,cuvier and ,brongniart4 ,they were ascertained to consist of successive sets of strata1 some of marine1 others of freshwater origin1 lying one upon the other4 ,the fossil shells and corals were perceived to be almost all of unknown species1 and to have in general a near affinity to those now inhabiting warmer seas4 ,the bones and skeletons of land animals1 some of them of large size1 and belonging to more than forty distinct species1 were examined by ,cuvier1 and declared by him not to agree specifically and for the most part not even generically1 with any hitherto observed in the living creation4 ,strata were soon afterwards brought to light in the vicinity of ,london1 and in ,hampshire1 which1 although dissimilar in mineral composition1 were justly inferred by ,mr4 ,t4 ,webster to be of the same age as those of ,paris1 because the greater number of the fossil shells were specifically identical4 ,for the same reason rocks found on the ,gironde1 in the ,south of ,france1 and at certain points in the ,north of ,italy1 were suspected to be of contemporaneous origin4 ,a variety of deposits were afterwards found in other parts of ,europe1 all reposing immediately on rocks as old or older than the chalk1 and which exhibited certain general characters of resemblance in their organic remains to those previously observed near ,paris and ,london4 ,an attempt was therefore made at first to refer the whole to one period2 and when at length this seemed impracticable1 it was contended that as in the ,parisian series there were many subordinate formations of considerable thickness which must have accumulated one after the other1 during a great lapse of time1 so the various patches of tertiary strata scattered over ,europe might correspond in age1 some of them to the older1 and others to the newer1 subdivisions of the ,parisian series4 ,this error1 although most unavoidable on the part of those who made the first generalizations in this branch of geology1 retarded seriously for some years the progress of classification4 ,a more scrupulous attention to specific distinctions1 aided by a careful regard to the relative position of the strata containing them1 led at length to the conviction that there were formations both marine and freshwater of various ages1 and all newer than the strata of the neighbourhood of ,paris and ,london4 ,one of the first steps in this chronological reform was made in #ahaa1 by an ,english naturalist1 ,mr4 ,parkinson1 who pointed out the fact that certain shelly strata1 provincially termed ,crag in ,suffolk1 lay decidedly over a deposit which was the continuation of the blue clay of ,london4 ,at the same time he remarked that the fossil testacea in these newer beds were distinct from those of the blue clay1 and that while some of them were of unknown species1 others were identical with species now inhabiting the ,british seas4 ,another important discovery was soon afterwards made by ,brocchi in ,italy1 who investigated the argillaceous and sandy deposits replete with shells which form a low range of hills1 flanking the ,apennines on both sides1 from the plains of the ,po to ,calabria4 ,these lower hills were called by him the ,subapennines1 and were formed of strata of different ages1 all newer than those of ,paris and ,london4 ,another tertiary group occurring in the neighbourhood of ,bordeaux and ,dax1 in the south of ,france1 was examined by ,m4 de ,basterot in #ahbe1 who described and figured several hundred species of shells1 which differed for the most part both from the ,parisian series and those of the ,subapennine hills4 ,it was soon1 therefore1 suspected that this fauna might belong to a period intermediate between that of the ,parisian and ,subapennine strata1 and it was not long before the evidence of superposition was brought to bear in support of this opinion2 for other strata1 contemporaneous with those of ,bordeaux1 were observed in one district 7the ,valley of the ,loire71 to overlie the ,parisian formation1 and in another 7in ,piedmont7 to underlie the ,subapennine beds4 ,the first example of these was pointed out in #ahbi by ,m4 ,desnoyers1 who ascertained that the sand and marl of marine origin called ,faluns1 near ,tours1 in the basin of the ,loire1 full of sea-shells and corals1 rested upon a lacustrine formation1 which constitutes the uppermost subdivision of the ,parisian group1 extending continuously throughout a great table-land intervening between the basin of the ,seine and that of the ,loire4 ,the other example occurs in ,italy1 where strata1 containing many fossils similar to those of ,bordeaux1 were observed by ,bonelli and others in the environs of ,turin1 subjacent to strata belonging to the ,subapennine group of ,brocchi4 ,without pretending to give a complete sketch of the progress of discovery1 ,i may refer to the facts above enumerated1 as illustrating the course usually pursued by geologists when they attempt to found new chronological divisions4 ,the method bears some analogy to that pursued by the naturalist in the construction of genera1 when he selects a typical species1 and then classes as congeners all other species of animals and plants which agree with this standard within certain limits4 ,the genera ,a4 and ,c4 having been founded on these principles1 a new species is afterwards met with1 departing widely both from ,a4 and ,c41 but in many respects of an intermediate character4 ,for this new type it becomes necessary to institute the new genus ,b41 in which are included all species afterwards brought to light1 which agree more nearly with ,b4 than with the types of ,a4 or ,c4 ,in like manner a new formation is met with in geology1 and the characters of its fossil fauna and flora investigated4 ,from that moment it is considered as a record of a certain period of the earth's history1 and a standard to which other deposits may be compared4 ,if any are found containing the same or nearly the same organic remains1 and occupying the same relative position1 they are regarded in the light of contemporary annals4 ,all such monuments are said to relate to one period1 during which certain events occurred1 such as the formation of particular rocks by aqueous or volcanic agency1 or the continued existence and fossilization of certain tribes of animals and plants4 ,when several of these periods have had their true places assigned to them in a chronological series1 others are discovered which it becomes necessary to intercalate between those first known2 and the difficulty of assigning clear lines of separation must unavoidably increase in proportion as chasms in the past history of the globe are filled up4 ,every zoologist and botanist is aware that it is a comparatively easy task to establish genera in departments which have been enriched with only a small number of species1 and where there is as yet no tendency in one set of characters to pass almost insensibly1 by a multitude of connecting links1 into another4 ,they also know that the difficulty of classification augments1 and that the artificial nature of their divisions becomes more apparent1 in proportion to the increased number of objects brought to light4 ,but in separating families and genera1 they have no other alternative than to avail themselves of such breaks as still remain1 or of every hiatus in the chain of animated beings which is not yet filled up4 ,so in geology1 we may be eventually compelled to resort to sections of time as arbitrary1 and as purely conventional1 as those which divide the history of human events into centuries4 ,but in the present state of our knowledge1 it is more convenient to use the interruptions which still occur in the regular sequence of geological monuments1 as boundary lines between our principal groups or periods1 even though the groups thus established are of very unequal value4 ,the isolated position of distinct tertiary deposits in different parts of ,europe has been already alluded to4 ,in addition to the difficulty presented by this want of continuity when we endeavour to settle the chronological relations of these deposits1 another arises from the frequent dissimilarity in mineral character of strata of contemporaneous date1 such1 for example1 as those of ,london and ,paris before mentioned4 ,the identity or non-identity of species is also a criterion which often fails us4 ,for this we might have been prepared1 for we have already seen1 that the ,mediterranean and ,red ,sea1 although within #gj miles of each other1 on each side of the ,isthmus of ,suez1 have each their peculiar fauna2 and a marked difference is found in the four groups of testacea now living in the ,baltic1 ,english ,channel1 ,black ,sea1 and ,mediterranean1 although all these seas have many species in common4 ,in like manner a considerable diversity in the fossils of different tertiary formations1 which have been thrown down in distinct seas1 estuaries1 bays1 and lakes1 does not always imply a distinctness in the times when they were produced1 but may have arisen from climate and conditions of physical geography wholly independent of time4 ,on the other hand1 it is now abundantly clear1 as the result of geological investigation1 that different sets of tertiary strata1 immediately superimposed upon each other1 contain distinct imbedded species of fossils1 in consequence of fluctuations which have been going on in the animate creation1 and by which in the course of ages one state of things in the organic world has been substituted for another wholly dissimilar4 ,it has also been shown that in proportion as the age of a tertiary deposit is more modern1 so is its fauna more analogous to that now in being in the neighbouring seas4 ,it is this law of a nearer agreement of the fossil testacea with the species now living1 which may often furnish us with a clue for the chronological arrangement of scattered deposits1 where we cannot avail ourselves of any one of the three ordinary chronological tests2 namely1 superposition1 mineral character1 and the specific identity of the fossils4 ,thus1 for example1 on the ,african border of the ,red ,sea1 at the height of #dj feet1 and sometimes more1 above its level1 a white calcareous formation has been observed1 containing several hundred species of shells differing from those found in the clay and volcanic tuff of the country round ,naples1 and of the contiguous island of ,ischia4 ,another deposit has been found at ,uddevalla1 in ,sweden1 in which the shells do not agree with those found near ,naples4 ,but although in these three cases there may be scarcely a single shell common to the three different deposits1 we do not hesitate to refer them all to one period 7the ,post-,pliocene71 because of the very close agreement of the fossil species in every instance with those now living in the contiguous seas4 ,to take another example1 where the fossil fauna recedes a few steps farther back from our own times4 ,we may compare1 first1 the beds of loam and clay bordering the ,clyde in ,scotland 7called glacial by some geologists71 secondly1 others of fluvio-marine origin near ,norwich1 and1 lastly1 a third set often rising to considerable heights in ,sicily1 and we discover that in every case more than three-fourths of the shells agree with species still living1 while the remainder are extinct4 ,hence we may conclude that all these1 greatly diversified as are their organic remains1 belong to one and the same era1 or to a period immediately antecedent to the ,post-,pliocene1 because there has been time in each of the areas alluded to for an equal or nearly equal amount of change in the marine testaceous fauna4 ,contemporaneousness of origin is inferred in these cases1 in spite of the most marked differences of mineral character or organic contents1 from a similar degree of divergence in the shells from those now living in the adjoining seas4 ,the advantage of such a test consists in supplying us with a common point of departure in all countries1 however remote4 ,but the farther we recede from the present times1 and the smaller the relative number of recent as compared with extinct species in the tertiary deposits1 the less confidence can we place in the exact value of such a test1 especially when comparing the strata of very distant regions2 for we cannot presume that the rate of former alterations in the animate world1 or the continual going out and coming in of species1 has been every where exactly equal in equal quantities of time4 ,the form of the land and sea1 and the climate1 may have changed more in one region than in another2 and consequently there may have been a more rapid destruction and renovation of species in one part of the globe than elsewhere4 ,considerations of this kind should undoubtedly put us on our guard against relying too implicitly on the accuracy of this test2 yet it can never fail to throw great light on the chronological relations of tertiary groups with each other1 and with the ,post-,pliocene period4 ,we may derive a conviction of this truth not only from a study of geological monuments of all ages1 but also by reflecting on the tendency which prevails in the present state of nature to a uniform rate of simultaneous fluctuation in the flora and fauna of the whole globe4 ,the grounds of such a doctrine cannot be discussed here1 and ,i have explained them at some length in the third ,book of the ,principles of ,geology1 where the causes of the successive extinction of species are considered4 ,it will be there seen that each local change in climate and physical geography is attended with the immediate increase of certain species1 and the limitation of the range of others4 ,a revolution thus effected is rarely1 if ever1 confined to a limited space1 or to one geographical province of animals or plants1 but affects several other surrounding and contiguous provinces4 ,in each of these1 moreover1 analogous alterations of the stations and habitations of species are simultaneously in progress1 reacting in the manner already alluded to on the first province4 ,hence1 long before the geography of any particular district can be essentially altered1 the flora and fauna throughout the world will have been materially modified by countless disturbances in the mutual relation of the various members of the organic creation to each other4 ,to assume that in one large area inhabited exclusively by a single assemblage of species any important revolution in physical geography can be brought about1 while other areas remain stationary in regard to the position of land and sea1 the height of mountains1 and so forth1 is a most improbable hypothesis1 wholly opposed to what we know of the laws now governing the aqueous and igneous causes4 ,on the other hand1 even were this conceivable1 the communication of heat and cold between different parts of the atmosphere and ocean is so free and rapid1 that the temperature of certain zones cannot be materially raised or lowered without others being immediately affected2 and the elevation or diminution in height of an important chain of mountains or the submergence of a wide tract of land would modify the climate even of the antipodes4 ,it will be observed that in the foregoing allusions to organic remains1 the testacea or the shell-bearing mollusca are selected as the most useful and convenient class for the purposes of general classification4 ,in the first place1 they are more universally distributed through strata of every age than any other organic bodies4 ,those families of fossils which are of rare and casual occurrence are absolutely of no avail in establishing a chronological arrangement4 ,if we have plants alone in one group of strata and the bones of mammalia in another1 we can draw no conclusion respecting the affinity or discordance of the organic beings of the two epochs compared2 and the same may be said if we have plants and vertebrated animals in one series and only shells in another4 ,although corals are more abundant1 in a fossil state1 than plants1 reptiles1 or fish1 they are still rare when contrasted with shells1 especially in the ,european tertiary formations4 ,the utility of the testacea is1 moreover1 enhanced by the circumstance that some forms are proper to the sea1 others to the land1 and others to freshwater4 ,rivers scarcely ever fail to carry down into their deltas some land shells1 together with species which are at once fluviatile and lacustrine4 ,by this means we learn what terrestrial1 freshwater1 and marine species co-existed at particular eras of the past2 and having thus identified strata formed in seas with others which originated contemporaneously in inland lakes1 we are then enabled to advance a step farther1 and show that certain quadrupeds or aquatic plants1 found fossil in lacustrine formations1 inhabited the globe at the same period when certain fish1 reptiles1 and zoophytes lived in the ocean4 ,among other characters of the molluscous animals1 which render them extremely valuable in settling chronological questions in geology1 may be mentioned1 first1 the wide geographical range of many species2 and1 secondly1 what is probably a consequence of the former1 the great duration of species in this class1 for they appear to have surpassed in longevity the greater number of the mammalia and fish4 ,had each species inhabited a very limited space1 it could never1 when imbedded in strata1 have enabled the geologist to identify deposits at distant points2 or had they each lasted but for a brief period1 they could have thrown no light on the connection of rocks placed far from each other in the chronological1 or1 as it is often termed1 vertical series4 ,many authors have divided the ,european tertiary strata into three groups--lower1 middle1 and upper2 the lower comprising the oldest formations of ,paris and ,london before-mentioned2 the middle those of ,bordeaux and ,touraine2 and the upper all those newer than the middle group4 ,when engaged in #ahbh in preparing my work on the ,principles of ,geology1 ,i conceived the idea of classing the whole series of tertiary strata in four groups1 and endeavouring to find characters for each1 expressive of their different degrees of affinity to the living fauna4 ,with this view1 ,i obtained information respecting the specific identity of many tertiary and recent shells from several ,italian naturalists1 and among others from ,professors ,bonelli1 ,guidotti1 and ,costa4 ,having in #ahbi become acquainted with ,m4 ,deshayes1 of ,paris1 already well known by his conchological works1 ,i learnt from him that he had arrived1 by independent researches1 and by the study of a large collection of fossil and recent shells1 at very similar views respecting the arrangement of tertiary formations4 ,at my request he drew up1 in a tabular form1 lists of all the shells known to him to occur both in some tertiary formation and in a living state1 for the express purpose of ascertaining the proportional number of fossil species identical with the recent which characterized successive groups2 and this table1 planned by us in common1 was published by me in #ahcc4aaj-;,a ,the number of tertiary fossil shells examined by ,m4 ,deshayes was about #cjjj2 and the recent species with which they had been compared about #ejjj4 ,the result then arrived at was1 that in the lower tertiary strata1 or those of ,london and ,paris1 there were about #c-a_/b per cent4 of species identical with recent2 in the middle tertiary of the ,loire and ,gironde about #ag per cent42 and in the upper tertiary or ,subapennine beds1 from #ce to #ej per cent4 ,in formations still more modern1 some of which ,i had particularly studied in ,sicily1 where they attain a vast thickness and elevation above the sea1 the number of species identical with those now living was believed to be from #ij to #ie per cent4 ,for the sake of clearness and brevity1 ,i proposed to give short technical names to these four groups1 or the periods to which they respectively belonged4 ,i called the first or oldest of them ,eocene1 the second ,miocene1 the third ,older ,pliocene1 and the last or fourth ,newer ,pliocene4 ,the first of the above terms1 ,eocene1 is derived from eos1 eos1 dawn1 and kainos1 cainos1 recent1 because the fossil shells of this period contain an extremely small proportion of living species1 which may be looked upon as indicating the dawn of the existing state of the testaceous fauna1 no recent species having been detected in the older or secondary rocks4 ,the term ,miocene 7from meion1 meion1 less1 and kainos1 cainos1 recent7 is intended to express a minor proportion of recent species 7of testacea71 the term ,pliocene 7from pleion1 pleion1 more1 and kainos1 cainos1 recent7 a comparative plurality of the same4 ,it may assist the memory of students to remind them1 that the ,miocene contain a minor proportion1 and ,pliocene a comparative plurality of recent species2 and that the greater number of recent species always implies the more modern origin of the strata4 ,it has sometimes been objected to this nomenclature that certain species of infusoria found in the chalk are still existing1 and1 on the other hand1 the ,miocene and ,older ,pliocene deposits often contain the remains of mammalia1 reptiles1 and fish1 exclusively of extinct species4 ,but the reader must bear in mind that the terms ,eocene1 ,miocene1 and ,pliocene were originally invented with reference purely to conchological data1 and in that sense have always been and are still used by me4 ,the distribution of the fossil species from which the results before mentioned were obtained in #ahcj by ,m4 ,deshayes was as follows3-- ,in the formations of the ,pliocene periods1 older and newer #ggg ,in the ,miocene #ajba ,in the ,eocene #abch ---- #cjcf ---- ,since the year #ahcj the progress of conchological science has been most rapid1 and the number of living species obtained from different parts of the globe has been raised from about #ejjj to more than #aj1jjj4 ,new fossil species have also been added to our collections in great abundance2 and at the same time a more copious supply of individuals both of fossil and recent species1 some of which were previously very rare1 have been procured1 affording more ample data for determining the specific character4 ,besides the reforms introduced in consequence of these new zoological facilities1 other errors of a geological nature have been in many instances removed4 ,,post-,,pliocene ,,formations4 ,i have adopted the term ,post-,pliocene for those strata which are sometimes called post-tertiary or modern1 and which are characterized by having all the imbedded fossil shells identical with species now living1 whereas even the ,newer ,pliocene1 or newest of the tertiary deposits above alluded to1 contain always some small proportion of shells of extinct species4 ,these modern formations1 thus defined1 comprehend not only those strata which can be shown to have originated since the earth was inhabited by man1 but also deposits of far greater extent and thickness1 in which no signs of man or his works can be detected4 ,in some of these1 of a date long anterior to the times of history and tradition1 the bones of extinct quadrupeds have been met with of species which probably never co-existed with the human race1 as1 for example1 the mammoth1 mastodon1 megatherium1 and others1 and yet the shells are the same as those now living4 ,that portion of the post-pliocene group which belongs to the human epoch1 and which is sometimes called ,recent1 forms a very unimportant feature in the geological structure of the earth's crust4 ,i have shown1 however1 in ,the ,principles1 where the recent changes of the earth illustrative of geology are described at length1 that the deposits accumulated at the bottom of lakes and seas within the last #djjj or #ejjj years can neither be insignificant in volume or extent4 ,they lie hidden1 for the most part1 from our sight2 but we have opportunities of examining them at certain points where newly-gained land in the deltas of rivers has been cut through during floods1 or where coral reefs are growing rapidly1 or where the bed of a sea or lake has been heaved up by subterranean movements and laid dry4 ,their age may be recognized either by our finding in them the bones of man in a fossil state1 that is to say1 imbedded in them by natural causes1 or by their containing articles fabricated by the hands of man4 ,thus at ,puzzuoli1 near ,naples1 marine strata are seen containing fragments of sculpture1 pottery1 and the remains of buildings1 together with innumerable shells retaining in part their colour1 and of the same species as those now inhabiting the ,bay of ,baiae4 ,the uppermost of these beds is about #bj feet above the level of the sea4 ,their emergence can be proved to have taken place since the beginning of the sixteenth century4#aab-;,a ,now here1 as in almost every instance where any alterations of level have been going on in historical periods1 it is found that rocks containing shells1 all1 or nearly all1 of which still inhabit the neighbouring sea1 may be traced for some distance into the interior1 and often to a considerable elevation above the level of the sea4 ,thus1 in the country round ,naples1 the post-pliocene strata1 consisting of clay and horizontal beds of volcanic tuff1 rise at certain points to the height of #aejj feet4 ,although the marine shells are exclusively of living species1 they are not accompanied like those on the coast at ,puzzuoli by any traces of man or his works4 ,had any such been discovered1 it would have afforded to the antiquary and geologist matter of great surprise1 since it would have shown that man was an inhabitant of that part of the globe1 while the materials composing the present hills and plains of ,campania were still in the progress of deposition at the bottom of the sea2 whereas we know that for nearly #cjjj years1 or from the times of the earliest ,greek colonists1 no material revolution in the physical geography of that part of ,italy has occurred4 ,in ,ischia1 a small island near ,naples1 composed in like manner of marine and volcanic formations1 ,dr4 ,philippi collected in the stratified tuff and clay ninety-two species of shells of existing species4 ,in the centre of ,ischia1 the lofty hill called ,epomeo1 or ,san ,nicola1 is composed of greenish indurated tuff1 of a prodigious thickness1 interstratified in some parts with marl1 and here and there with great beds of solid lava4 ,visconti ascertained by trigonometrical measurement that this mountain was #bfje feet above the level of the sea4 ,not far from its summit1 at the height of about #bjjj feet1 as also near ,moropano1 a village only #ajj feet lower1 on the southern declivity of the mountain1 ,i collected1 in #ahbh1 many shells of species now inhabiting the neighbouring gulf4 ,it is clear1 therefore1 that the great mass of ,epomeo was not only raised to its present height1 but was also formed beneath the waters1 within the post-pliocene period4 ,it is a fact1 however1 of no small interest1 that the fossil shells from these modern tuffs of the volcanic region surrounding the ,bay of ,baiae1 although none of them extinct1 indicate a slight want of correspondence between the ancient fauna and that now inhabiting the ,mediterranean4 ,philippi informs us that when he and ,m4 ,scacchi had collected ninety-nine species of them1 he found that only one1 ,pecten medius1 now living in the ,red ,sea1 was absent from the ,mediterranean4 ,notwithstanding this1 he adds1 the condition of the sea when the tufaceous beds were deposited must have been considerably different from its present state2 for ,tellina striata was then common1 and is now rare2 ,lucina spinosa was both more abundant and grew to a larger size2 ,lucina fragilis1 now rare1 and hardly measuring #f lines1 then attained the enormous dimensions of #ad lines1 and was extremely abundant2 and ,ostrea lamellosa1 ,broc41 no longer met with near ,naples1 existed at that time1 and attained a size so large that one lower valve has been known to measure #e inches #i lines in length1 #d inches in breadth1 #a-a_/b inch in thickness1 and weighed #bf-a_/b ounces4#aac-;,a ,there are other parts of ,europe where no volcanic action manifests itself at the surface1 as at ,naples1 whether by the eruption of lava or by earthquakes1 and yet where the land and bed of the adjoining sea are undergoing upheaval4 ,the motion is so gradual as to be insensible to the inhabitants1 being only ascertainable by careful scientific measurements compared after long intervals4 ,such an upward movement has been proved to be in progress in ,norway and ,sweden throughout an area about #ajjj miles ,n4 and ,s41 and for an unknown distance ,e4 and ,w41 the amount of elevation always increasing as we proceed towards the ,north ,cape1 where it may equal #e feet in a century4 ,if we could assume that there had been an average rise of #b-a_/b feet in each hundred years for the last fifty centuries1 this would give an elevation of #abe feet in that period4 ,in other words1 it would follow that the shores1 and a considerable area of the former bed of the ,baltic and ,north ,sea1 had been uplifted vertically to that amount1 and converted into land in the course of the last #ejjj years4 ,accordingly1 we find near ,stockholm1 in ,sweden1 horizontal beds of sand1 loam1 and marl containing the same peculiar assemblage of testacea which now live in the brackish waters of the ,baltic4 ,mingled with these1 at different depths1 have been detected various works of art implying a rude state of civilization1 and some vessels built before the introduction of iron1 the whole marine formation having been upraised1 so that the upper beds are now #fj feet higher than the surface of the ,baltic4 ,in the neighbourhood of these recent strata1 both to the north-west and south of ,stockholm1 other deposits similar in mineral composition occur1 which ascend to greater heights1 in which precisely the same assemblage of fossil shells is met with1 but without any intermixture of human bones or fabricated articles4 ,on the opposite or western coast of ,sweden1 at ,uddevalla1 post-pliocene strata1 containing recent shells1 not of that brackish water character peculiar to the ,baltic1 but such as now live in the northern ocean1 ascend to the height of #bjj feet2 and beds of clay and sand of the same age attain elevations of #cjj and even #gjj feet in ,norway1 where they have been usually described as raised beaches4 ,they are1 however1 thick deposits of submarine origin1 spreading far and wide1 and filling valleys in the granite and gneiss1 just as the tertiary formations1 in different parts of ,europe1 cover or fill depressions in the older rocks4 ,it is worthy of remark1 that although the fossil fauna characterizing these upraised sands and clays consists exclusively of existing northern species of testacea1 yet1 according to ,loven 7an able living naturalist of ,norway71 the species do not constitute such an assemblage as now inhabits corresponding latitudes in the ,german ,ocean4 ,on the contrary1 they decidedly represent a more arctic fauna4#aad-;,a ,in order to find the same species flourishing in equal abundance1 or in many cases to find them at all1 we must go northwards to higher latitudes than ,uddevalla in ,sweden1 or even nearer the pole than ,central ,norway4 ,judging by the uniformity of climate now prevailing from century to century1 and the insensible rate of variation in the organic world in our own times1 we may presume that an extremely lengthened period was required even for so slight a modification of the molluscous fauna1 as that of which the evidence is here brought to light4 ,on the other hand1 we have every reason for inferring on independent grounds 7namely1 the rate of upheaval of land in modern times7 that the antiquity of the deposits in question must be very great4 ,for if we assume1 as before suggested1 that the mean rate of continuous vertical elevation has amounted to #b-a_/b feet in a century 7and this is probably a high average71 it would require #bg1ejj years for the sea-coast to attain the height of #gjj feet1 without making allowance for any pauses such as are now experienced in a large part of ,norway1 or for any oscillations of level4 ,in ,england1 buried ships have been found in the ancient and now deserted channels of the ,rother in ,sussex1 of the ,mersey in ,kent1 and the ,thames near ,london4 ,canoes and stone hatchets have been dug up1 in almost all parts of the kingdom1 from peat and shell-marl2 but there is no evidence1 as in ,sweden1 ,italy1 and many other parts of the world1 of the bed of the sea1 and the adjoining coast1 having been uplifted bodily to considerable heights within the human period4 ,recent strata have been traced along the coasts of ,peru and ,chili1 inclosing shells in abundance1 all agreeing specifically with those now swarming in the ,pacific4 ,in one bed of this kind1 in the island of ,san ,lorenzo1 near ,lima1 ,mr4 ,darwin found1 at the altitude of #he feet above the sea1 pieces of cotton-thread1 plaited rush1 and the head of a stalk of ,indian corn1 the whole of which had evidently been imbedded with the shells4 ,at the same height on the neighbouring mainland1 he found other signs corroborating the opinion that the ancient bed of the sea had there also been uplifted #he feet1 since the region was first peopled by the ,peruvian race4#aae-;,a ,but similar shelly masses are also met with at much higher elevations1 at innumerable points between the ,chilian and ,peruvian ,andes and the sea-coast1 in which no human remains were ever1 or in all probability ever will be1 discovered4 ,in the ,west ,indies1 also1 in the island of ,guadaloupe1 a solid limestone occurs1 at the level of the sea-beach1 enveloping human skeletons4 ,the stone is extremely hard1 and chiefly composed of comminuted shell and coral1 with here and there some entire corals and shells1 of species now living in the adjacent ocean4 ,with them are included arrow-heads1 fragments of pottery1 and other articles of human workmanship4 ,a limestone with similar contents has been formed1 and is still forming1 in ,st4 ,domingo4 ,but there are also more ancient rocks in the ,west ,indian ,archipelago1 as in ,cuba1 near the ,havanna1 and in other islands1 in which are shells identical with those now living in corresponding latitudes2 some well-preserved1 others in the state of casts1 all referable to the post-pliocene period4 ,i have already described in the seventh chapter1 p4 #hd41 what would be the effects of oscillations and changes of level in any region drained by a great river and its tributaries1 supposing the area to be first depressed several hundred feet1 and then re-elevated4 ,i believe that such changes in the relative level of land and sea have actually occurred in the post-pliocene era in the hydrographical basin of the ,mississippi and in that of the ,rhine4 ,the accumulation of fluviatile matter in a delta during a slow subsidence may raise the newly gained land superficially at the same rate at which its foundations sink1 so that these may go down hundreds or thousands of feet perpendicularly1 and yet the sea bordering the delta may always be excluded1 the whole deposit continuing to be terrestrial or freshwater in character4 ,this appears to have happened in the deltas both of the ,po and ,ganges1 for recent artesian borings1 penetrating to the depth of #djj feet1 have there shown that fluviatile strata1 with shells of recent species1 together with ancient surfaces of land supporting turf and forests1 are depressed hundreds of feet below the sea level4#aaf-;,a ,should these countries be once more slowly upraised1 the rivers would carve out valleys through the horizontal and unconsolidated strata as they rose1 sweeping away the greater portion of them1 and leaving mere fragments in the shape of terraces skirting newly-formed alluvial plains1 as monuments of the former levels at which the rivers ran4 ,of this nature are the bluffs1 or river cliffs1 now bounding the valley of the ,mississippi throughout a large portion of its course4 ,thus let a b1 fig4 #ajf41 represent the alluvial plain of the ,mississippi1 a plain which1 at the point alluded to1 is more than #cj miles broad1 and is truly a prolongation of the modern delta of that river4 ,it is bounded by bluffs1 the upper portions of which consist1 both on the east and west side1 of shelly loam1 ,no4 #b4 rising from #ajj to #bjj feet above the level of the plain1 and containing land and freshwater shells of the genera ,helix1 ,pupa1 ,succinea1 and ,lymnea1 of the same species as those now inhabiting the neighbouring forests and swamps4 ,in the same loam also1 ,no4 #b41 are found the bones of the ,mastodon1 ,elephant1 ,megalonyx1 and other extinct quadrupeds4 ,illustration3 ,fig4 #ajf4 ,valley of the ,mississippi4 #a4 ,alluvium4 #b4 ,loess4 #c4 f4 ,eocene4 #d4 ,cretaceous4 ,i have endeavoured to show that the deposits forming the delta and alluvial plain of the ,mississippi consist of sedimentary matter1 extending over an area of #cj1jjj square miles1 and known in some parts to be several hundred feet deep4 ,although we cannot estimate correctly how many years it may have required for the river to bring down from the upper country so large a quantity of earthy matter--the data for such a computation being as yet incomplete--we may still approximate to a minimum of the time which such an operation must have taken1 by ascertaining experimentally the annual discharge of water by the ,mississippi1 and the mean annual amount of solid matter contained in its waters4 ,the lowest estimate of the time required would lead us to assign a high antiquity1 amounting to many tens of thousands of years to the existing delta1 the origin of which is nevertheless an event of yesterday when contrasted with those terraces1 c1 and d e1 fig4 #ajf41 formed of the loam ,no4 #b4 above mentioned4 ,these materials of the bluffs a and d were produced1 the reader will observe1 during the first part of that great oscillation of level which depressed to a depth of #bjj feet a larger area than the modern delta and plain of the ,mississippi1 and then restored the region to its former position4#aag-;,a ,loess of the ,valley of the ,rhine4--,a similar succession of geographical changes1 attended by the production of a fluviatile formation1 singularly resembling that which bounds the great plain of the ,mississippi1 seems to have occurred in the hydrographical basin of the ,rhine1 since the time when that basin had already acquired its present outline of hill and valley4 ,i allude to the deposit provincially termed loess in part of ,germany1 or lehm in ,alsace1 filled with land and freshwater shells of existing species4 ,it is a finely comminuted sand or pulverulent loam of a yellowish grey colour1 consisting chiefly of argillaceous matter combined with a sixth part of carbonate of lime1 and a sixth of quartzose and micaceous sand4 ,it often contains calcareous sandy concretions or nodules1 rarely exceeding the size of a man's head4 ,its entire thickness amounts1 in some places1 to between #bjj and #cjj feet2 yet there are often no signs of stratification in the mass1 except here and there at the bottom1 where there is occasionally a slight intermixture of drifted materials derived from subjacent rocks4 ,unsolidified as it is1 and of so perishable a nature1 that every streamlet flowing over it cuts out for itself a deep gully1 it usually terminates in a vertical cliff1 from the surface of which land shells are seen here and there to project in relief4 ,in all these features it presents a precise counterpart to the loess of the ,mississippi4 ,it is so homogeneous as generally to exhibit no signs of stratification1 owing1 probably1 to its materials having been derived from a common source1 and having been accumulated by a uniform action4 ,yet it displays in some few places decided marks of successive deposition1 where coarser and finer materials alternate1 especially near the bottom4 ,calcareous concretions1 also enclosing land-shells1 are sometimes arranged in horizontal layers4 ,it is a remarkable deposit1 from its position1 wide extent1 and thickness1 its homogeneous mineral composition1 and freshwater origin4 ,its distribution clearly shows that after the great valley of the ,rhine1 from ,schaffhausen to ,bonn1 had acquired its present form1 having its bottom strewed over with coarse gravel1 a period arrived when it became filled up from side to side with fine mud1 which was also thrown down in the valleys of the principal tributaries of the ,rhine4 ,thus1 for example1 it may be traced far into ,wuertemberg1 up the valley of the ,neckar1 and from ,frankfort1 up the valley of the ,main1 to above ,dettelbach4 ,i have also seen it spreading over the country of ,mayence1 ,eppelsheim1 and ,worms1 on the left bank of the ,rhine1 and on the opposite side on the table-land above the ,bergstrasse1 between ,wiesloch and ,bruchsal1 where it attains a thickness of #bjj feet4 ,near ,strasburg1 large masses of it appear at the foot of the ,vosges on the left bank1 and at the base of the mountains of the ,black ,forest on the right bank4 ,the ,kaiserstuhl1 a volcanic mountain which stands in the middle of the plain of the ,rhine near ,freiburg1 has been covered almost everywhere with this loam1 as have the extinct volcanos between ,coblentz and ,bonn4 ,near ,andernach1 in the ,kirchweg1 the loess containing the usual shells alternates with volcanic matter2 and over the whole are strewed layers of pumice1 lapilli1 and volcanic sand1 from #aj to #ae feet thick1 very much resembling the ejections under which ,pompeii lies buried4 ,there is no passage at this upper junction from the loess into the pumiceous superstratum2 and this last follows the slope of the hill1 just as it would have done had it fallen in showers from the air on a declivity partly formed of loess4 ,but1 in general1 the loess overlies all the volcanic products1 even those between ,neuwied and ,bonn1 which have the most modern aspect2 and it has filled up in part the crater of the ,roderberg1 an extinct volcano near ,bonn4 ,in #ahcc a well was sunk at the bottom of this crater1 through #gj feet of loess1 in part of which were the usual calcareous concretions4 ,the interstratification above alluded to1 of loess with layers of pumice and volcanic ashes1 has led to the opinion that both during and since its deposition some of the last volcanic eruptions of the ,lower ,eifel have taken place4 ,should such a conclusion be adopted1 we should be called upon to assign a very modern date to these eruptions4 ,this curious point1 therefore1 deserves to be reconsidered2 since it may possibly have happened that the waters of the ,rhine1 swollen by the melting of snow and ice1 and flowing at a great height through a valley choked up with loess1 may have swept away the loose superficial scoriae and pumice of the ,eifel volcanos1 and spread them out occasionally over the yellow loam4 ,sometimes1 also1 the melting of snow on the slope of small volcanic cones may have given rise to local floods1 capable of sweeping down light pumice into the adjacent low grounds4 ,the first idea which has occurred to most geologists1 after examining the loess between ,mayence and ,basle1 is to imagine that a great lake once extended throughout the valley of the ,rhine between those two places4 ,such a lake may have sent off large branches up the course of the ,main1 ,neckar1 and other tributary valleys1 in all of which large patches of loess are now seen4 ,the barrier of the lake might be placed somewhere in the narrow and picturesque gorge of the ,rhine between ,bingen and ,bonn4 ,but this theory fails altogether to explain the phenomena2 when we discover that that gorge itself has once been filled with loess1 which must have been tranquilly deposited in it1 as also in the lateral valley of the ,lahn1 communicating with the gorge4 ,the loess has also overspread the high adjoining platform near the village of ,plaidt above ,andernach4 ,nay1 on proceeding farther down to the north1 we discover that the hills which skirt the great valley between ,bonn and ,cologne have loess on their flanks1 which also covers here and there the gravel of the plain as far as ,cologne1 and the nearest rising grounds4 ,besides these objections to the lake theory1 the loess is met with near ,basle1 capping hills more than #abjj feet above the sea2 so that a barrier of land capable of separating the supposed lake from the ocean would require to be1 at least1 as high as the mountains called the ,siebengebirge1 near ,bonn1 the loftiest summit of which1 the ,oehlberg1 is #abji feet above the ,rhine and #acfi feet above the sea4 ,it would be necessary1 moreover1 to place this lofty barrier somewhere below ,cologne1 or precisely where the level of the land is now lowest4 ,instead1 therefore1 of supposing one continuous lake of sufficient extent and depth to allow of the simultaneous accumulation of the loess1 at various heights1 throughout the whole area where it now occurs1 ,i formerly suggested that1 subsequently to the period when the countries now drained by the ,rhine and its tributaries had nearly acquired their actual form and geographical features1 they were again depressed gradually by a movement like that now in progress on the west coast of ,greenland4#aai-;,a ,in proportion as the whole district was lowered1 the general fall of the waters between the ,alps and the ocean was lessened2 and both the main and lateral valleys1 becoming more subject to river inundations1 were partially filled up with fluviatile silt1 containing land and freshwater shells4 ,when a thickness of many hundred feet of loess had been thrown down slowly by this operation1 the whole region was once more upheaved gradually4 ,during this upward movement most of the fine loam would be carried off by the denuding power of rains and rivers2 and thus the original valleys might have been re-excavated1 and the country almost restored to its pristine state1 with the exception of some masses and patches of loess such as still remain1 and which1 by their frequency and remarkable homogeneousness of composition and fossils1 attest the ancient continuity and common origin of the whole4 ,by imagining these oscillations of level1 we dispense with the necessity of erecting and afterwards removing a mountain barrier sufficiently high to exclude the ocean from the valley of the ,rhine during the period of the accumulation of the loess4 ,the proportion of land shells of the genera ,helix1 ,pupa1 and ,bulimus1 is very large in the loess2 but in many places aquatic species of the genera ,lymnea1 ,paludina1 and ,planorbis are also found4 ,these may have been carried away during floods from shallow pools and marshes bordering the river2 and the great extent of marshy ground caused by the wide overflowings of rivers above supposed would favour the multiplication of amphibious mollusks1 such as the ,succinea 7fig4 #ajg471 which is almost everywhere characteristic of this formation1 and is sometimes accompanied1 as near ,bonn1 by another species1 ,s4 amphibia 7fig4 #cd4 p4 #bi474 ,among other abundant fossils are ,helix plebeium and ,pupa muscorum4 7,see ,figures47 ,both the terrestrial and aquatic shells preserved in the loess are of most fragile and delicate structure1 and yet they are almost invariably perfect and uninjured4 ,they must have been broken to pieces had they been swept along by a violent inundation4 ,even the colour of some of the land shells1 as that of ,helix nemoralis1 is occasionally preserved4 ,illustration3 ,fig4 #ajg4 ,succinea elongata4 ,illustration3 ,fig4 #ajh4 ,pupa muscorum4 ,illustration3 ,fig4 #aji4 ,helix plebeium4 ,bones of vertebrated animals are rare in the loess1 but those of the mammoth1 horse1 and some other quadrupeds have been met with4 ,at the village of ,binningen1 and the hills called ,bruderholz1 near ,basle1 ,i found the vertebrae of fish1 together with the usual shells4 ,these vertebrae1 according to ,m4 ,agassiz1 belong decidedly to the ,shark family1 perhaps to the genus ,lamna4 ,in explanation of their occurrence among land and freshwater shells1 it may be stated that certain fish of this family ascend the ,senegal1 ,amazon1 and other great rivers1 to the distance of several hundred miles from the ocean4#abj-;,a ,at ,cannstadt1 near ,stuttgart1 in a valley also belonging to the hydrographical basin of the ,rhine1 ,i have seen the loess pass downwards into beds of calcareous tuff and travertin4 ,several valleys in northern ,germany1 as that of the ,ilm at ,weimar1 and that of the ,tonna1 north of ,gotha1 exhibit similar masses of modern limestone filled with recent shells of the genera ,planorbis1 ,lymnea1 ,paludina1 c41 from #ej to #hj feet thick1 with a bed of loess much resembling that of the ,rhine1 occasionally incumbent on them4 ,in these modern limestones used for building1 the bones of ,elephas primigenius1 ,rhinoceros tichorinus1 ,ursus spelaeus1 ,hyaena spelaea1 with the horse1 ox1 deer1 and other quadrupeds1 occur2 and in #ahej ,mr4 ,h4 ,credner and ,i obtained in a quarry at ,tonna1 at the depth of #ae feet1 inclosed in the calcareous rock and surrounded with dicotyledonous leaves and petrified leaves1 four eggs of a snake of the size of the largest ,european ,coluber1 which1 with three others1 had been found lying in a series1 or string4 ,they are1 ,i believe1 the first reptilian remains which have been met with in strata of this age4 ,the agreement of the shells in these cases with recent ,european species enables us to refer to a very modern period the filling up and re-excavation of the valleys2 an operation which doubtless consumed a long period of time1 since which the mammiferous fauna has undergone a considerable change4 ,,footnotes3 #aaj-;,a ,see ,princ4 of ,geol4 vol4 iii4 #ast ed4 #aab-;,a ,see ,principles1 ,index1 ,serapis4 #aac-;,a ,geol4 ,quart4 ,journ4 vol4 ii4 ,memoirs1 p4 #ae4 #aad-;,a ,quart4 ,geol4 ,journ4 #d ,mems4 p4 #dh4 #aae-;,a ,journal1 p4 #dea4 #aaf-;,a ,see ,principles1 #hth ed4 pp4 #bfj-bfh4 #aag-;,a ,lyell's ,second ,visit to the ,united ,states1 vol4 ii4 chap4 xxxiv4 #aai-;,a ,princ4 of ,geol4 #c;d edition1 #ahcd1 vol4 iii4 p4 #dad4 #abj-;,a ,proceedings ,geol4 ,soc4 ,no4 #dc4 p4 #bbb4 ,,chapter ,,xi4 ,,newer ,,pliocene ,,period4--,,boulder ,,formation4 ,drift of ,scandinavia1 northern ,germany1 and ,russia--,its northern origin--,not all of the same age--,fundamental rocks polished1 grooved1 and scratched--,action of glaciers and icebergs--,fossil shells of glacial period--,drift of eastern ,norfolk--,associated freshwater deposit--,bent and folded strata lying on undisturbed beds--,shells on ,moel ,tryfane--,ancient glaciers of ,north ,wales--,irish drift4 ,among the different kinds of alluvium described in the seventh chapter1 mention was made of the boulder formation in the north of ,europe1 the peculiar characters of which may now be considered1 as it belongs in part to the post-pliocene1 and partly to the newer pliocene1 period4 ,i shall first allude briefly to that portion of it which extends from ,finland and the ,scandinavian mountains to the north of ,russia1 and the low countries bordering the ,baltic1 and which has been traced southwards as far as the eastern coast of ,england4 ,this formation consists of mud1 sand1 and clay1 sometimes stratified1 but often wholly devoid of stratification1 for a depth of more than a hundred feet4 ,to this unstratified form of the deposit1 the name of till has been applied in ,scotland4 ,it generally contains numerous fragments of rocks1 some angular and others rounded1 which have been derived from formations of all ages1 both fossiliferous1 volcanic1 and hypogene1 and which have often been brought from great distances4 ,some of the travelled blocks are of enormous size1 several feet or yards in diameter2 their average dimensions increasing as we advance northwards4 ,the till is almost everywhere devoid of organic remains1 unless where these have been washed into it from older formations2 so that it is chiefly from relative position that we must hope to derive a knowledge of its age4 ,although a large proportion of the boulder deposit1 or northern drift1 as it has sometimes been called1 is made up of fragments brought from a distance1 and which have sometimes travelled many hundred miles1 the bulk of the mass in each locality consists of the ruins of subjacent or neighbouring rocks2 so that it is red in a region of red sandstone1 white in a chalk country1 and grey or black in a district of coal and coal-shale4 ,the fundamental rock on which the boulder formation reposes1 if it consist of granite1 gneiss1 marble1 or other hard stone capable of permanently retaining any superficial markings which may have been imprinted upon it1 is smoothed or polished1 and usually exhibits parallel striae and furrows having a determinate direction4 ,this direction1 both in ,europe and ,north ,america1 is evidently connected with the course taken by the erratic blocks in the same district being north or south1 or #bj or #cj degrees to the east or west of north1 according as the large angular and rounded stones have travelled4 ,these stones themselves also are often furrowed and scratched on more than one side4 ,illustration3 ,fig4 #aaj4 ,limestone polished1 furrowed1 and scratched by the glacier of ,rosenlaui1 in ,switzerland4 7,agassiz47 a a4 ,white streaks or scratches1 caused by small grains of flint frozen into the ice4 b b4 ,furrows4 ,in explanation of such phenomena ,i may refer the student to what was said of the action of glaciers and icebergs in the ,principles of ,geology4#abb-;,a ,it is ascertained that hard stones1 frozen into a moving mass of ice1 and pushed along under the pressure of that mass1 scoop out long rectilinear furrows or grooves parallel to each other on the subjacent solid rock4 7,see fig4 #aaj47 ,smaller scratches and striae are made on the polished surface by crystals or projecting edges of the hardest minerals1 just as a diamond cuts glass4 ,the recent polishing and striation of limestone by coast-ice carrying boulders even as far south as the coast of ,denmark1 has been observed by ,dr4 ,forchhammer1 and helps us to conceive how large icebergs1 running aground on the bed of the sea1 may produce similar furrows on a grander scale4 ,an account was given so long ago as the year #ahbb1 by ,scoresby1 of icebergs seen by him drifting along in latitudes #fi deg4 and #gj deg4 ,n41 which rose above the surface from #ajj to #bjj feet1 and measured from a few yards to a mile in circumference4 ,many of them were loaded with beds of earth and rock1 of such thickness that the weight was conjectured to be from #ej1jjj to #ajj1jjj tons4#abb-;,b ,a similar transportation of rocks is known to be in progress in the southern hemisphere1 where boulders included in ice are far more frequent than in the north4 ,one of these icebergs was encountered in #ahci1 in mid-ocean1 in the antarctic regions1 many hundred miles from any known land1 sailing northwards1 with a large erratic block firmly frozen into it4 ,in order to understand in what manner long and straight grooves may be cut by such agency1 we must remember that these floating islands of ice have a singular steadiness of motion1 in consequence of the larger portion of their bulk being sunk deep under water1 so that they are not perceptibly moved by the winds and waves even in the strongest gales4 ,many had supposed that the magnitude commonly attributed to icebergs by unscientific navigators was exaggerated1 but now it appears that the popular estimate of their dimensions has rather fallen within than beyond the truth4 ,many of them1 carefully measured by the officers of the ,french exploring expedition of the ,astrolabe1 were between #ajj and #bbe feet high above water1 and from #b to #e miles in length4 ,captain d',urville ascertained one of them which he saw floating in the ,southern ,ocean to be #ac miles long and #ajj feet high1 with walls perfectly vertical4 ,the submerged portions of such islands must1 according to the weight of ice relatively to sea-water1 be from six to eight times more considerable than the part which is visible1 so that the mechanical power they might exert when fairly set in motion must be prodigious4#abc-;,a ,glaciers formed in mountainous regions become laden with mud and stones1 and if they melt away at their lower extremity before they reach the sea1 they leave wherever they terminate a confused heap of unstratified rubbish1 called a moraine1 composed of mud and pieces of all the rocks with which they were loaded4 ,we may expect1 therefore1 to find a formation of the same kind1 resulting from the liquefaction of icebergs1 in tranquil water4 ,but1 should the action of a current intervene at certain points or at certain seasons1 then the materials will be sorted as they fall1 and arranged in layers according to their relative weight and size4 ,hence there will be passages from till1 as it is called in ,scotland1 to stratified clay1 gravel1 and sand1 and intercalations of one in the other4 ,i have yet to mention another appearance connected with the boulder formation1 which has justly attracted much attention in ,norway and other parts of ,europe4 ,abrupt pinnacles and outstanding ridges of rock are often observed to be polished and furrowed on the north1 or strike side as it is called1 or on the side facing the region from which the erratics have come2 while1 on the other side1 which is usually steeper and often perpendicular1 called the lee-side1 such superficial markings are wanting4 ,there is usually a collection on this lee-side of boulders and gravel1 or of large angular fragments4 ,in explanation we may suppose that the north side was exposed1 when still submerged1 to the action of icebergs1 and afterwards1 when the land was upheaved1 of coast-ice1 which ran aground upon shoals1 or was packed on the beach2 so that there would be great wear and tear on the seaward slope1 while1 on the other1 gravel and boulders might be heaped up in a sheltered position4 ,northern origin of erratics4--,that the erratics of northern ,europe have been carried southward cannot be doubted2 those of granite1 for example1 scattered over large districts of ,russia and ,poland1 agree precisely in character with rocks of the mountains of ,lapland and ,finland2 while the masses of gneiss1 syenite1 porphyry1 and trap1 strewed over the low sandy countries of ,pomerania1 ,holstein1 and ,denmark1 are identical in mineral characters with the mountains of ,norway and ,sweden4 ,it is found to be a general rule in ,russia1 that the smaller blocks are carried to greater distances from their point of departure than the larger2 the distance being sometimes #hjj and even #ajjj miles from the nearest rocks from which they were broken off2 the direction having been from ,n4,w4 to ,s4,e41 or from the ,scandinavian mountains over the seas and low lands to the south-east4 ,that its accumulation throughout this area took place in part during the post-pliocene period is proved by its superposition at several points to strata containing recent shells4 ,thus1 for example1 in ,european ,russia1 ,,mm4 ,murchison and ,de ,verneuil found in #ahdj1 that the flat country between ,st4 ,petersburg and ,archangel1 for a distance of #fjj miles1 consisted of horizontal strata1 full of shells similar to those now inhabiting the arctic sea1 on which rested the boulder formation1 containing large erratics4 ,in ,sweden1 in the immediate neighbourhood of ,upsala1 ,i observed1 in #ahcd1 a ridge of stratified sand and gravel1 in the midst of which is a layer of marl1 evidently formed originally at the bottom of the ,baltic1 by the slow growth of the mussel1 cockle1 and other marine shells1 intermixed with some of freshwater species4 ,the marine shells are all of dwarfish size1 like those now inhabiting the brackish waters of the ,baltic2 and the marl1 in which myriads of them are imbedded1 is now raised more than #ajj feet above the level of the ,gulf of ,bothnia4 ,upon the top of this ridge repose several huge erratics1 consisting of gneiss for the most part unrounded1 from #i to #af feet in diameter1 and which must have been brought into their present position since the time when the neighbouring gulf was already characterized by its peculiar fauna4#abd-;,a ,here1 therefore1 we have proof that the transport of erratics continued to take place1 not merely when the sea was inhabited by the existing testacea1 but when the north of ,europe had already assumed that remarkable feature of its physical geography1 which separates the ,baltic from the ,north ,sea1 and causes the ,gulf of ,bothnia to have only one fourth of the saltness belonging to the ocean4 ,in ,denmark1 also1 recent shells have been found in stratified beds1 closely associated with the boulder clay4 ,it was stated that in ,russia the erratics diminished generally in size in proportion as they are traced farther from their source4 ,the same observation holds true in regard to the average bulk of the ,scandinavian boulders1 when we pursue them southwards1 from the south of ,norway and ,sweden through ,denmark and ,westphalia4 ,this phenomenon is in perfect harmony with the theory of ice-islands floating in a sea of variable depth2 for the heavier erratics require icebergs of a larger size to buoy them up2 and1 even when there are no stones frozen in1 more than seven eighths1 and often nine tenths1 of a mass of drift ice is under water4 ,the greater1 therefore1 the volume of the iceberg1 the sooner would it impinge on some shallower part of the sea2 while the smaller and lighter floes1 laden with finer mud and gravel1 may pass freely over the same banks1 and be carried to much greater distances4 ,in those places1 also1 where in the course of centuries blocks have been carried southwards by coast-ice1 having been often stranded and again set afloat in the direction of a prevailing current1 the blocks will be worn and diminish in size the farther they travel from their point of departure4 ,the northern drift of the most southern latitudes is usually of the highest antiquity4 ,in ,scotland it rests immediately on the older rocks1 and is covered by stratified sand and clay1 usually devoid of fossils1 but in which1 at certain points near the east and west coast1 as1 for example1 in the estuaries of the ,tay and ,clyde1 marine shells have been discovered4 ,the same shells have also been met with in the north1 at ,wick in ,caithness1 and on the shores of the ,moray ,frith4 ,the principal deposit on the ,clyde occurs at the height of about #gj feet1 but a few shells have been traced in it as high as #eed feet above the sea4 ,although a proportion of between #he or #ij in #ajj of the imbedded shells are of recent species1 the remainder are unknown2 and even many which are recent now inhabit more northern seas1 where we may1 perhaps1 hereafter find living representatives of some of the unknown fossils4 ,the distance to which erratic blocks have been carried southwards in ,scotland1 and the course they have taken1 which is often wholly independent of the present position of hill and valley1 favours the idea that ice-rafts rather than glaciers were in general the transporting agents4 ,the ,grampians in ,forfarshire and in ,perthshire are from #cjjj to #djjj feet high4 ,to the southward lies the broad and deep valley of ,strathmore1 and to the south of this again rise the ,sidlaw ,hills#abe-;,a to the height of #aejj feet and upwards4 ,on the highest summits of this chain1 formed of sandstone and shale1 and at various elevations1 are found huge angular fragments of mica schist1 some #c and others #ae feet in diameter1 which have been conveyed for a distance of at least #ae miles from the nearest ,grampian rocks from which they could have been detached4 ,others have been left strewed over the bottom of the large intervening vale of ,strathmore4 ,still farther south on the ,pentland ,hills1 at the height of #aajj feet above the sea1 ,mr4 ,maclaren has observed a fragment of mica-schist weighing from #h to #aj tons1 the nearest mountain composed of this formation being #ej miles distant4#abe-;,b ,the testaceous fauna of the boulder period1 in ,scotland1 ,england1 and ,ireland1 has been shown by ,prof4 ,e4 ,forbes to contain a much smaller number of species than that now belonging to the ,british seas1 and to have been also much less rich in species than the ,older ,pliocene fauna of the crag which preceded it4 ,yet the species are nearly all of them now living either in the ,british or more northern seas1 the shells of more arctic latitudes being the most abundant and the most wide spread throughout the entire area of the drift from north to south4 ,this extensive range of the fossils can by no means be explained by imagining the mollusca of the drift to have been inhabitants of a deep sea1 where a more uniform temperature prevailed4 ,on the contrary1 many species were littoral1 and others belonged to a shallow sea1 not above #ajj feet deep1 and very few of them lived1 according to ,prof4 ,e4 ,forbes1 at greater depths than #cjj feet4 ,from what was before stated it will appear that the boulder formation displays almost everywhere1 in its mineral ingredients1 a strange heterogeneous mixture of the ruins of adjacent lands1 with stones both angular and rounded1 which have come from points often very remote4 ,thus we find it in our eastern counties1 as in ,norfolk1 ,suffolk1 ,cambridge1 ,huntingdon1 ,bedford1 ,hertford1 ,essex1 and ,middlesex1 containing stones from the ,silurian and ,carboniferous strata1 and from the lias1 oolite1 and chalk1 all with their peculiar fossils1 together with trap1 syenite1 mica-schist1 granite1 and other crystalline rocks4 ,a fine example of this singular mixture extends to the very suburbs of ,london1 being seen on the summit of ,muswell ,hill1 ,highgate4 ,but south of ,london the northern drift is wanting1 as1 for example1 in the ,wealds of ,surrey1 ,kent1 and ,sussex4 ,norfolk drift4--,the drift can nowhere be studied more advantageously in ,england than in the cliffs of the ,norfolk coast between ,happisburgh and ,cromer4 ,vertical sections1 having an ordinary height of from #ej to #gj feet1 are there exposed to view for a distance of about #bj miles4 ,the name of diluvium was formerly given to it by those who supposed it to have been produced by the violent action of a sudden and transient deluge1 but the term drift has been substituted by those who reject this hypothesis4 ,here1 as elsewhere1 it consists for the most part of clay1 loam1 and sand1 in part stratified1 in part devoid of stratification4 ,pebbles1 together with some large boulders of granite1 porphyry1 greenstone1 lias1 chalk1 and other transported rocks1 are interspersed1 especially through the till4 ,that some of the granitic and other fragments came from ,scandinavia ,i have no doubt1 after having myself traced the course of the continuous stream of blocks from ,norway and ,sweden to ,denmark1 and across the ,elbe1 through ,westphalia1 to the borders of ,holland4 ,we need not be surprised to find them reappear on our eastern coast1 between the ,tweed and the ,thames1 regions not half so remote from parts of ,norway as are many ,russian erratics from the sources whence they came4 ,white chalk rubble1 unmixed with foreign matter1 and even huge fragments of solid chalk1 also occur in many localities in these ,norfolk cliffs4 ,no fossils have been detected in this drift1 which can positively be referred to the era of its accumulation2 but at some points it overlies a freshwater formation containing recent shells1 and at others it is blended with the same in such a manner as to force us to conclude that both were contemporaneously deposited4 ,illustration3 ,fig4 #aaa4 ,the shaded portion consists of ,freshwater beds4 ,intercalation of freshwater beds and of boulder clay and sand at ,mundesley4 ,this interstratification is expressed in the annexed figure1 the dark mass indicating the position of the freshwater beds1 which contain much vegetable matter1 and are divided into thin layers4 ,the imbedded shells belong to the genera ,planorbis1 ,lymnea1 ,paludina1 ,unio1 ,cyclas1 and others1 all of ,british species1 except a minute ,paludina now inhabiting ,france4 7,see fig4 #aab47 ,illustration3 ,fig4 #aab4 ,paludina marginata1 ,michaud4 7,p4 minuta1 ,strickland47 ,the middle figure is of the natural size4 ,the ,cyclas 7fig4 #aac47 is merely a remarkable variety of the common ,english species4 ,the scales and teeth of fish of the genera ,pike1 ,perch1 ,roach1 and others1 accompany these shells2 but the species are not considered by ,m4 ,agassiz to be identical with known ,british or ,european kinds4 ,illustration3 ,fig4 #aac4 ,cyclas 7,pisidium7 amnica1 var48 ,the two middle figures are of the natural size4 ,the series of formations in the cliffs of eastern ,norfolk1 now under consideration1 beginning with the lowest1 is as follows3--,first1 chalk2 secondly1 patches of a marine tertiary formation1 called the ,norwich ,crag1 hereafter to be described2 thirdly1 the freshwater beds already mentioned2 and lastly1 the drift4 ,immediately above the chalk1 or crag1 when that is present1 is found here and there a buried forest1 or a stratum in which the stools and roots of trees stand in their natural position1 the trunks having been broken short off and imbedded with their branches and leaves4 ,it is very remarkable that the strata of the overlying boulder formation have often undergone great derangement at points where the subjacent forest bed and chalk remain undisturbed4 ,there are also cases where the upper portion of the boulder deposit has been greatly deranged1 while the lower beds of the same have continued horizontal4 ,thus the annexed section 7fig4 #aad47 represents a cliff about #ej feet high1 at the bottom of which is till1 or unstratified clay1 containing boulders1 having an even horizontal surface1 on which repose conformably beds of laminated clay and sand about #e feet thick1 which1 in their turn1 are succeeded by vertical1 bent1 and contorted layers of sand and loam #bj feet thick1 the whole being covered by flint gravel4 ,now the curves of the variously coloured beds of loose sand1 loam1 and pebbles are so complicated that not only may we sometimes find portions of them which maintain their verticality to a height of #aj or #ae feet1 but they have also been folded upon themselves in such a manner that continuous layers might be thrice pierced in one perpendicular boring4 ,illustration3 ,fig4 #aad4 ,cliff #ej feet high between ,bacton ,gap and ,mundesley4 ,illustration3 ,fig4 #aae4 ,folding of the strata between ,east and ,west ,runton4 ,illustration3 ,fig4 #aaf4 ,section of concentric beds west of ,cromer4 #a4 ,blue clay4 #b4 ,white sand4 #c4 ,yellow ,sand4 #d4 ,striped loam and clay4 #e4 ,laminated blue clay4 ,at some points there is an apparent folding of the beds round a central nucleus1 as at a1 fig4 #aae41 where the strata seem bent round a small mass of chalk2 or1 as in fig4 #aaf41 where the blue clay1 ,no4 #a41 is in the centre2 and where the other strata1 #b1 #c1 #d1 #e1 are coiled round it2 the entire mass being #bj feet in perpendicular height4 ,this appearance of concentric arrangement around a nucleus is1 nevertheless1 delusive1 being produced by the intersection of beds bent into a convex shape2 and that which seems the nucleus being1 in fact1 the innermost bed of the series1 which has become partially visible by the removal of the protuberant portions of the outer layers4 ,to the north of ,cromer are other fine illustrations of contorted drift reposing on a floor of chalk horizontally stratified and having a level surface4 ,these phenomena1 in themselves sufficiently difficult of explanation1 are rendered still more anomalous by the occasional inclosure in the drift of huge fragments of chalk many yards in diameter4 ,one striking instance occurs west of ,sherringham1 where an enormous pinnacle of chalk1 between #gj and #hj feet in height1 is flanked on both sides by vertical layers of loam1 clay1 and gravel4 7,fig4 #aag47 ,illustration3 ,fig4 #aag4 ,included pinnacle of chalk at ,old ,hythe point1 west of ,sherringham4 d4 ,chalk with regular layers of chalk flints4 c4 ,layer called the pan1 of loose chalk1 flints1 and marine shells of recent species1 cemented by oxide of iron4 ,this chalky fragment is only one of many detached masses which have been included in the drift1 and forced along with it into their present position4 ,the level surface of the chalk in situ 7d7 may be traced for miles along the coast1 where it has escaped the violent movements to which the incumbent drift has been exposed4#abi-;,a ,we are called upon1 then1 to explain how any force can have been exerted against the upper masses1 so as to produce movements in which the subjacent strata have not participated4 ,it may be answered that1 if we conceive the till and its boulders to have been drifted to their present place by ice1 the lateral pressure may have been supplied by the stranding of ice-islands4 ,we learn1 from the observations of ,messrs4 ,dease and ,simpson in the polar regions1 that such islands1 when they run aground1 push before them large mounds of shingle and sand4 ,it is therefore probable that they often cause great alterations in the arrangement of pliant and incoherent strata forming the upper part of shoals or submerged banks1 the inferior portions of the same remaining unmoved4 ,or many of the complicated curvatures of these layers of loose sand and gravel may have been due to another cause1 the melting on the spot of icebergs and coast ice in which successive deposits of pebbles1 sand1 ice1 snow1 and mud1 together with huge masses of rock fallen from cliffs1 may have become interstratified4 ,ice-islands so constituted often capsize when afloat1 and gravel once horizontal may have assumed1 before the associated ice was melted1 an inclined or vertical position4 ,the packing of ice forced up on a coast may lead to similar derangement in a frozen conglomerate of sand or shingle1 and1 as ,mr4 ,trimmer has suggested#acj-;,a1 alternate layers of earthy matter may have sunk down slowly during the liquefaction of the intercalated ice1 so as to assume the most fantastic and anomalous positions1 while the aqueous strata below1 and those afterwards thrown down above1 may be perfectly horizontal4 ,a buried forest has been adverted to as underlying the drift on the coast of ,norfolk4 ,at the time when the trees grew there must have been dry land over a large area1 which was afterwards submerged1 so as to allow a mass of stratified and unstratified drift1 #bjj feet and more in thickness1 to be superimposed4 ,the undermining of the cliffs by the sea in modern times has enabled us to demonstrate1 beyond all doubt1 the fact of this superposition1 and that the forest was not formed along the present coast-line4 ,its situation implies a subsidence of several hundred feet since the commencement of the drift period1 after which there must have been an upheaval of the same ground2 for the forest bed of ,norfolk is now again so high as to be exposed to view at many points at low water2 and this same upward movement may explain why the till1 which is conceived to have been of submarine origin1 is now met with far inland1 and on the summit of hills4 ,the boulder formation of the west of ,england1 observed in ,lancashire1 ,cheshire1 ,shropshire1 ,staffordshire1 and ,worcestershire1 contains in some places marine shells of recent species1 rising to various heights1 from #ajj to #cej feet above the sea4 ,the erratics have come partly from the mountains of ,cumberland1 and partly from those of ,scotland4 ,but it is on the mountains of ,north ,wales that the ,northern drift1 with its characteristic marine fossils1 reaches its greatest altitude4 ,on ,moel ,tryfane1 near the ,menai ,straits1 ,mr4 ,trimmer met with shells of the species commonly found in the drift at the height of #acib feet above the level of the sea4 ,it is remarkable that in the same neighbourhood where there is evidence of so great a submergence of the land during part of the glacial period1 we have also the most decisive proofs yet discovered in the ,british ,isles of subaerial glaciers4 ,dr4 ,buckland published in #ahdb his reasons for believing that the ,snowdonian mountains in ,caernarvonshire were formerly covered with glaciers1 which radiated from the central heights through the seven principal valleys of that chain1 where striae and flutings are seen on the polished rocks directed towards as many different points of the compass4 ,he also described the moraines of the ancient glaciers1 and the rounded bosses or small flattened domes of polished rock1 such as the action of moving glaciers is known to produce in ,switzerland1 when gravel1 sand1 and boulders1 underlying the ice1 are forced along over a foundation of hard stone4 ,mr4 ,darwin1 and subsequently ,prof4 ,ramsay1 have confirmed ,dr4 ,buckland's views in regard to these ,welsh glaciers4 ,nor indeed was it to be expected that geologists should discover proofs of icebergs having abounded in the area now occupied by the ,british ,isles in the ,pleistocene period without sometimes meeting with the signs of contemporaneous glaciers which covered hills even of moderate elevation between the #ejth and #fjth degrees of latitude4 ,in ,ireland the drift exhibits the same general characters and fossil remains as in ,scotland and ,england2 but in the southern part of that island1 ,prof4 ,e4 ,forbes and ,capt4 ,james found in it some shells which show that the glacial sea communicated with one inhabited by a more southern fauna4 ,among other species in the south1 they mention at ,wexford and elsewhere the occurrence of ,nucula ,cobboldiae 7see fig4 #abj4 p4 #adi47 and ,turritella incrassata 7a crag fossil72 also a southern form of ,fusus1 and a ,mitra allied to a ,spanish species4#aca-;,a ,,footnotes3 #abb-;,a ,chap4 xvi4 and the references there given4 #abb-;,b ,voyage in #ahbb1 p4 #bcc4 #abc-;,a ,t4 ,l4 ,hayes1 ,boston ,journ4 ,nat4 ,hist4 #ahdd4 #abd-;,a ,see paper by the author1 ,phil4 ,trans4 #ahce1 p4 #ae4 #abe-;,a ,see above1 section1 p4 #dh4 #abe-;,b ,geol4 of ,fife1 c4 p4 #bbj4 #abi-;,a ,for a full account of the drift of ,east ,norfolk1 see a paper by the author1 ,phil4 ,mag4 ,no4 #ajd4 ,may1 #ahdj4 #acj-;,a ,quart4 ,journ4 ,geol4 ,soc4 vol4 vii4 p4 #bb4 #aca-;,a ,forbes1 ,memoirs of ,geol4 ,survey of ,great ,britain1 vol4 i4 p4 #cgg4 ,,chapter ,,xii4 ,,boulder ,,formation--continued4 ,difficulty of interpreting the phenomena of drift before the glacial hypothesis was adopted--,effects of intense cold in augmenting the quantity of alluvium--,analogy of erratics and scored rocks in ,north ,america and ,europe--,bayfield on shells in drift of ,canada--,great subsidence and re-elevation of land from the sea1 required to account for glacial appearances--,why organic remains so rare in northern drift--,mastodon giganteus in ,united ,states--,many shells and some quadrupeds survived the glacial cold--,alps an independent centre of dispersion of erratics--,alpine blocks on the ,jura--,whether transported by glaciers or floating ice--,recent transportation of erratics from the ,andes to ,chiloe--,meteorite in ,asiatic drift4 ,it will appear from what was said in the last chapter of the marine shells characterizing the boulder formation1 that nine-tenths or more of them belong to species still living4 ,the superficial position of the drift is in perfect accordance with its imbedded organic remains1 leading us to refer its origin to a modern period4 ,if1 then1 we encounter so much difficulty in the interpretation of monuments relating to times so near our own--if in spite of their recent date they are involved in so much obscurity--the student may ask1 not without reasonable alarm1 how we can hope to decipher the records of remote ages4 ,to remove from the mind as far as possible this natural feeling of discouragement1 ,i shall endeavour in this chapter to prove that what seems most strikingly anomalous1 in the erratic formation1 as some call it1 is really the result of that glacial action which has already been alluded to4 ,if so1 it was to be expected that so long as the true origin of so singular a deposit remained undiscovered1 erroneous theories and terms would be invented in the effort to solve the problem4 ,these inventions would inevitably retard the reception of more correct views which a wider field of observation might afterwards suggest4 ,the term diluvium was for a time the popular name of the boulder formation1 because it was referred by some geologists to the deluge4 ,others retained the name as expressive of their opinion that a series of diluvial waves raised by hurricanes and storms1 or by earthquakes1 or by the sudden upheaval of land from the bed of the sea1 had swept over the continents1 carrying with them vast masses of mud and heavy stones1 and forcing these stones over rocky surfaces so as to polish and imprint upon them long furrows and striae4 ,but no explanation was offered why such agency should have been developed more energetically in modern times than at former periods of the earth's history1 or why it should be displayed in its fullest intensity in northern latitudes2 for it is important to insist on the fact1 that the boulder formation is a northern phenomenon4 ,even the southern extension of the drift1 or the large erratics found in the ,alps and the surrounding lands1 especially their occurrence round the highest parts of the chain1 offers such an exception to the general rule as confirms the glacial hypothesis2 for it shows that the transportation of stony fragments to great distances1 and the striation1 polishing1 and grooving of solid floors of rock1 are here again intimately connected with accumulations of perennial snow and ice4 ,that there is some intimate connection between a cold or northern climate and the various geological appearances now commonly called glacial1 cannot be doubted by any one who has compared the countries bordering the ,baltic with those surrounding the ,mediterranean4 ,the smoothing and striation of rocks1 and the erratics1 are traced from the sea-shore to the height of #cjjj feet above the level of the ,baltic1 whereas such phenomena are wholly wanting in countries bordering the ,mediterranean2 and their absence is still more marked in the equatorial parts of ,asia1 ,africa1 and ,america2 but when we cross the southern tropic1 and reach ,chili and ,patagonia1 we again encounter the boulder formation1 between the latitude #da deg4 ,s4 and ,cape ,horn1 with precisely the same characters which it assumes in ,europe4 ,the evidence as to climate derived from the organic remains of the drift is1 as we have seen1 in perfect harmony with the conclusions above alluded to1 the former habits of the species of mollusca being accurately ascertainable1 inasmuch as they belong to species still living1 and known to have at present a wide range in northern seas4 ,but if we are correct in assuming that the northern hemisphere was considerably colder than now during the period under consideration1 owing probably to the greater area and height of arctic lands1 and to the quantity of icebergs which such a geographical state of things would generate1 it may be well to reflect before we proceed farther on the entire modification which extreme cold would produce in the operation of those causes spoken of in the sixth chapter as most active in the formation of alluvium4 ,a large part of the materials derived from the detritus of rocks1 which in warm climates would go to form deltas1 or would be regularly stratified by marine currents1 would1 under arctic influences1 assume a superficial and alluvial character4 ,instead of mud being carried farther from a coast than sand1 and sand farther out than pebbles1--instead of dense stratified masses being heaped up in limited areas1--nearly the whole materials1 whether coarse or fine1 would be conveyed by ice to equal distances1 and huge fragments1 which water alone could never move1 would be borne for hundreds of miles without having their edges worn or fractured2 and the earthy and stony masses1 when melted out of the frozen rafts1 would be scattered at random over the submarine bottom1 whether on mountain tops or in low plains1 with scarcely any relation to the inequalities of the ground1 settling on the crests or ridges of hills in tranquil water as readily as in valleys and ravines4 ,occasionally1 in those deep and uninhabited parts of the ocean1 never reached by any but the finest sediment in a normal state of things1 the bottom would become densely overspread by gravel1 mud1 and boulders4 ,in the ,western ,hemisphere1 both in ,canada and as far south as the #djth and even #chth parallel of latitude in the ,united ,states1 we meet with a repetition of all the peculiarities which distinguish the ,european boulder formation4 ,fragments of rock have travelled for great distances from north to south2 the surface of the subjacent rock is smoothed1 striated1 and fluted2 unstratified mud or till containing boulders is associated with strata of loam1 sand1 and clay1 usually devoid of fossils4 ,where shells are present1 they are of species still living in northern seas1 and half of them identical with those already enumerated as belonging to ,european drift #aj degrees of latitude farther north4 ,the fauna also of the glacial epoch in ,north ,america is less rich in species than that now inhabiting the adjacent sea1 whether in the ,gulf of ,st4 ,lawrence1 or off the shores of ,maine1 or in the ,bay of ,massachusetts4 ,at the southern extremity of its course1 moreover1 it presents an analogy with the drift of the south of ,ireland1 by blending with a more southern fauna1 as for example at ,brooklyn near ,new ,york1 in lat4 #da deg4 ,n41 where1 according to ,,mm4 ,redfield and ,desor1 ,venus mercenaria and other southern species of shells begin to occur as fossils in the drift4 ,the extension on the ,american continent of the range of erratics during the ,pleistocene period to lower latitudes than they reached in ,europe1 agrees well with the present southward deflection of the isothermal lines1 or rather the lines of equal winter temperature4 ,formerly1 as now1 a more extreme climate and a more abundant supply of floating ice prevailed on the western side of the ,atlantic4 ,another resemblance between the distribution of the drift fossils in ,europe and ,north ,america has yet to be pointed out4 ,in ,norway1 ,sweden1 and ,scotland1 as in ,canada and the ,united ,states1 the marine shells are confined to very moderate elevations above the sea 7between #ajj and #gjj feet71 while the erratic blocks and the grooved and polished surfaces of rock extend to elevations of several thousand feet4 ,illustration3 ,fig4 #aah4 ,cross section4 ,k4 ,mr4 ,ryland's house4 h4 ,clay and sand of higher grounds1 with ,saxicava1 c4 g4 ,gravel with boulders4 f4 ,mass of ,saxicava rugosa1 #ab feet thick4 e4 ,sand and loam with ,mya truncata1 ,scalaria ,groenlandica1 c4 d4 ,drift1 with boulders of syenite1 c4 c4 ,yellow sand4 b4 ,laminated clay1 #be feet thick4 ,a4 ,horizontal lower ,silurian strata4 ,b4 ,valley re-excavated4 ,i described in #ahci the fossil shells collected by ,captain ,bayfield from strata of drift at ,beauport near ,quebec1 in lat4 #dg deg41 and drew from them the inference that they indicated a more northern climate1 the shells agreeing in great part with those of ,uddevalla in ,sweden4#acd-;,a ,the shelly beds attain at ,beauport and the neighbourhood a height of #bjj1 #cjj1 and sometimes #djj feet above the sea1 and dispersed through some of them are large boulders of granite1 which could not have been propelled by a violent current1 because the accompanying fragile shells are almost all entire4 ,they seem1 therefore1 said ,captain ,bayfield1 writing in #ahch1 to have been dropped down from melting ice1 like similar stones which are now annually deposited in the ,st4 ,lawrence4#acd-;,b ,i visited this locality in #ahdb1 and made the annexed section1 fig4 #aah41 which will give an idea of the general position of the drift in ,canada and the ,united ,states4 ,i imagine that the whole of the valley ,b was once filled up with the beds b1 c1 d1 e1 f1 which were deposited during a period of subsidence1 and that subsequently the higher country 7h7 was submerged and overspread with drift4 ,the partial re-excavation of ,b took place when this region was again uplifted above the sea to its present height4 ,among the twenty-three species of fossil shells collected by me from these beds at ,beauport1 all were of recent northern species1 except one1 which is unknown as living1 and may be extinct 7see fig4 #aai474 ,i also examined the same formation farther up the valley of the ,st4 ,lawrence1 in the suburbs of ,montreal1 where some of the beds of loam are filled with great numbers of the ,mytilus edulis1 or our common ,european mussel1 retaining both its valves and purple colour4 ,this shelly deposit1 containing ,saxicava rugosa and other characteristic marine shells1 also occurs at an elevated point on the mountain of ,montreal1 #dej feet above the level of the sea4#ace-;,a ,illustration3 ,fig4 #aai4 ,astarte ,laurentiana4 a4 ,outside4 b4 ,inside of right valve4 c4 ,inside of left valve4 ,in my account of ,canada and the ,united ,states1 published in #ahde1 ,i announced the conclusion to which ,i had then arrived1 that to explain the position of the erratics and the polished surfaces of rocks1 and their striae and flutings1 we must assume first a gradual submergence of the land in ,north ,america1 after it had acquired its present outline of hill and valley1 cliff and ravine1 and then its re-emergence from the ocean4 ,when the land was slowly sinking1 the sea which bordered it was covered with islands of floating ice coming from the north1 which1 as they grounded on the coast and on shoals1 pushed along such loose materials of sand and pebbles as lay strewed over the bottom4 ,by this force all angular and projecting points were broken off1 and fragments of hard stone1 frozen into the lower surface of the ice1 had power to scoop out grooves in the subjacent solid rock4 ,the sloping beach1 as well as the floor of the ocean1 might be polished and scored by this machinery2 but no flood of water1 however violent1 or however great the quantity of detritus or size of the rocky fragments swept along by it1 could produce such long1 perfectly straight and parallel furrows1 as are everywhere visible in the ,niagara district1 and generally in the region north of the #djth parallel of latitude4#ace-;,b ,by the hypothesis of such a slow and gradual subsidence of the land we may account for the fact that almost everywhere in ,n4 ,america and ,northern ,europe the boulder formation rests on a polished and furrowed surface of rock1--a fact by no means obliging us to imagine1 as some think1 that the polishing and grooving action was1 as a whole1 anterior in date to the transportation of the erratics4 ,during the successive depression of high land1 varying originally in height from #ajjj to #cjjj feet above the sea-level1 every portion of the surface would be brought down by turns to the level of the ocean1 so as to be converted first into a coast-line1 and then into a shoal2 and at length1 after being well scored by the stranding upon it of thousands of icebergs1 might be sunk to a depth of several hundred fathoms4 ,by the constant depression of land1 the coast would recede farther and farther from the successively formed zones of polished and striated rock1 each outer zone becoming in its turn so deep under water as to be no longer grated upon by the heaviest icebergs4 ,such sunken areas would then simply serve as receptacles of mud1 sand1 and boulders dropped from melting ice1 perhaps to a depth scarcely1 if at all1 inhabited by testacea and zoophytes4 ,meanwhile1 during the formation of the unstratified and unfossiliferous mass in deeper water1 the smoothing and furrowing of shoals and beaches is still going on elsewhere upon and near the coast in full activity4 ,if at length the subsidence should cease1 and the direction of the movement of the earth's crust be reversed1 the sunken area covered with drift would be slowly reconverted into land4 ,the boulder deposit1 before emerging1 would then for a time be brought within the action of the waves1 tides1 and currents1 so that its upper portion1 being partially disturbed1 would have its materials re-arranged and stratified4 ,streams also flowing from the land would in some places throw down layers of sediment upon the till4 ,in that case1 the order of superposition will be1 first and uppermost1 sand1 loam1 and gravel occasionally fossiliferous2 secondly1 an unstratified and unfossiliferous mass1 for the most part of much older date than the preceding1 with angular erratics1 or with boulders interspersed2 and1 thirdly1 beneath the whole1 a surface of polished and furrowed rock4 ,such a succession of events seems to have prevailed very widely on both sides of the ,atlantic1 the travelled blocks having been carried in general from the ,north ,pole southwards1 but mountain chains having in some cases served as independent centres of dispersion1 of which the ,alps present the most conspicuous example4 ,it is by no means rare to meet with boulders imbedded in drift which are worn flat on one or more of their sides1 the surface being at the same time polished1 furrowed1 and striated4 ,they may have been so shaped in a glacier before they reached the sea1 or when they were fixed in the bottom of an iceberg as it ran aground4 ,we learn from ,mr4 ,charles ,martins that the glaciers of ,spitzbergen project from the coast into a sea between #ajj and #djj feet deep2 and that numbers of striated pebbles or blocks are there seen to disengage themselves from the overhanging masses of ice as they melt1 so as to fall at once into deep water4#acf-;,a ,that they should retain such markings when again upraised above the sea ought not to surprise us1 when we remember that rippled sands1 and the cracks in clay dried between high and low water1 and the foot-tracks of animals and rain-drops impressed on mud1 and other superficial markings1 are all found fossil in rocks of various ages4 ,on the other hand1 it is not difficult to account for the absence in many districts of striated and scored pebbles and boulders in glacial deposits1 for they may have been exposed to the action of the waves on a coast while it was sinking beneath or rising above the sea4 ,no shingle on an ordinary sea-beach exhibits such striae1 and at a very short distance from the termination of a glacier every stone in the bed of the torrent which gushes out from the melting ice is found to have lost its glacial markings by being rolled for a distance even of a few hundred yards4 ,the usual dearth of fossil shells in glacial clays well fitted to preserve organic remains may1 perhaps1 be owing1 as already hinted1 to the absence of testacea in the deep sea1 where the undisturbed accumulation of boulders melted out of very large bergs may take place4 ,in the ,a,egean and other parts of the ,mediterranean1 the zero of animal life1 according to ,prof4 ,e4 ,forbes1 is approached at a depth of about #cjj fathoms4 ,in tropical seas it would descend farther down1 just as vegetation ascends higher on the mountains of hot countries4 ,near the pole1 on the other hand1 the same zero would be reached much sooner both on the hills and in the sea4 ,if the ocean was filled with floating bergs1 and a low temperature prevailed in the northern hemisphere during the glacial period1 even the shallow part of the sea might have been uninhabitable1 or very thinly peopled with living beings4 ,it may also be remarked that the melting of ice in some fiords in ,norway freshens the water so as to destroy marine life1 and famines have been caused in ,iceland by the stranding of icebergs drifted from the ,greenland coast1 which have required several years to melt1 and have not only injured the hay harvest by cooling the atmosphere1 but have driven away the fish from the shore by chilling and freshening the sea4 ,if the cold of the glacial epoch came on slowly1 if it was long before it reached its greatest intensity1 and again if it abated gradually1 we may expect to find the earliest and latest formed drift less barren of organic remains than that deposited during the coldest period4 ,we may also expect that along the southern limits of the drift during the whole glacial epoch1 there would be an intimate association of transported matter of northern origin with fossil-bearing sediment1 whether marine or freshwater1 belonging to more southern seas1 rivers1 and continents4 ,that in the ,united ,states1 the ,mastodon giganteus was very abundant after the drift period is evident from the fact that entire skeletons of this animal are met with in bogs and lacustrine deposits occupying hollows in the drift4 ,they sometimes occur in the bottom even of small ponds recently drained by the agriculturist for the sake of the shell marl4 ,i examined one of these spots at ,geneseo in the state of ,new ,york1 from which the bones1 skull1 and tusk of a ,mastodon had been procured in the marl below a layer of black peaty earth1 and ascertained that all the associated freshwater and land shells were of a species now common in the same district4 ,they consisted of several species of ,lymnea1 of ,planorbis bicarinatus1 ,physa heterostropha1 c4 ,in #ahde no less than six skeletons of the same species of ,mastodon were found in ,warren ,county1 ,new ,jersey1 #f feet below the surface1 by a farmer who was digging out the rich mud from a small pond which he had drained4 ,five of these skeletons were lying together1 and a large part of the bones crumbled to pieces as soon as they were exposed to the air4 ,but nearly the whole of the other skeleton1 which lay about #aj feet apart from the rest1 was preserved entire1 and proved the correctness of ,cuvier's conjecture respecting this extinct animal1 namely1 that it had twenty ribs like the living elephant4 ,from the clay in the interior within the ribs1 just where the contents of the stomach might naturally have been looked for1 seven bushels of vegetable matter were extracted4 ,i submitted some of this matter to ,mr4 ,a4 ,henfrey of ,london for microscopic examination1 and he informs me that it consists of pieces of small twigs of a coniferous tree of the ,cypress family1 probably the young shoots of the white cedar1 ,thuja occidentalis1 still a native of ,north ,america1 on which therefore we may conclude that this extinct ,mastodon once fed4 ,another specimen of the same quadruped1 the most complete and probably the largest ever found1 was exhumed in #ahde in the town of ,newburg1 ,new ,york1 the length of the skeleton being #be feet1 and its height #ab feet4 ,the anchylosing of the last two ribs on the right side afforded ,dr4 ,john ,c4 ,warren a true gauge for the space occupied by the intervertebrate substance1 so as to enable him to form a correct estimate of the entire length4 ,the tusks when discovered were #aj feet long1 but a part only could be preserved4 ,the large proportion of animal matter in the tusk1 teeth1 and bones of some of these fossil mammalia is truly astonishing4 ,it amounts in some cases1 as ,dr4 ,c4 ,t4 ,jackson has ascertained by analysis1 to #bg per cent41 so that when all the earthy ingredients are removed by acids1 the form of the bone remains as perfect1 and the mass of animal matter is almost as firm1 as in a recent bone subjected to similar treatment4 ,it would be rash1 however1 to infer from such data that these quadrupeds were mired in modern times1 unless we use that term strictly in a geological sense4 ,i have shown that there is a fluviatile deposit in the valley of the ,niagara1 containing shells of the genera ,melania1 ,lymnea1 ,planorbis1 ,valvata1 ,cyclas1 ,unio1 and ,helix1 c41 all of recent species1 from which the bones of the great ,mastodon have been taken in a very perfect state4 ,yet the whole excavation of the ravine1 for many miles below the ,falls1 has been slowly effected since that fluviatile deposit was thrown down4 ,whether or not1 in assigning a period of more than #cj1jjj years for the recession of the ,falls from ,queenstown to their present site1 ,i have over or under estimated the time required for that operation1 no one can doubt that a vast number of centuries must have elapsed before so great a series of geographical changes were brought about as have occurred since the entombment of this elephantine quadruped4 ,the freshwater gravel which incloses it is decidedly of much more modern origin than the drift or boulder clay of the same region4#ach-;,a ,other extinct animals accompany the ,mastodon giganteus in the post-glacial deposits of the ,united ,states1 among which the ,castoroides ohioensis1 ,foster and ,wyman1 a huge rodent allied to the beaver1 and the ,capybara may be mentioned4 ,but whether the loess1 and other freshwater and marine strata of the ,southern ,states1 in which skeletons of the same ,mastodon are mingled with the bones of the ,megatherium1 ,mylodon1 and ,megalonyx1 were contemporaneous with the drift1 or were of subsequent date1 is a chronological question still open to discussion4 ,it appears clear1 however1 from what we know of the tertiary fossils of ,europe--and ,i believe the same will hold true in ,north ,america--that many species of testacea and some mammalia1 which existed prior to the glacial epoch1 survived that era4 ,as ,european examples among the warm-blooded quadrupeds1 the ,elephas primigenius and ,rhinoceros tichorinus may be mentioned4 ,as to the shells1 whether fresh water1 terrestrial1 or marine1 they need not be enumerated here1 as allusion will be made to them in the sequel1 when the pliocene tertiary fossils of ,suffolk are described4 ,the fact is important1 as refuting the hypothesis that the cold of the glacial period was so intense and universal as to annihilate all living creatures throughout the globe4 ,that the cold was greater for a time than it is now in certain parts of ,siberia1 ,europe1 and ,north ,america1 will not be disputed2 but1 before we can infer the universality of a colder climate1 we must ascertain what was the condition of other parts of the northern1 and of the whole southern1 hemisphere at the time when the ,scandinavian1 ,british1 and ,alpine erratics were transported into their present position4 ,it must not be forgotten that a great deposit of drift and erratic blocks is now in full progress of formation in the southern hemisphere1 in a zone corresponding in latitude to the ,baltic1 and to ,northern ,italy1 ,switzerland1 ,france1 and ,england4 ,should the uneven bed of the southern ocean be hereafter converted by upheaval into land1 the hills and valleys will be strewed over with transported fragments1 some derived from the antarctic continent1 others from islands covered with glaciers1 like ,south ,georgia1 which must now be centres of the dispersion of drift1 although situated in a latitude1 agreeing with that of the ,cumberland mountains in ,england4 ,not only are these operations going on between the #deth and #fjth parallels of latitude south of the line1 while the corresponding zone of ,europe is free from ice2 but1 what is still more worthy of remark1 we find in the southern hemisphere itself1 only #ijj miles distant from ,south ,georgia1 where the perpetual snow reaches to the sea-beach1 lands covered with forests1 as in ,terra del ,fuego4 ,there is here no difference of latitude to account for the luxuriance of vegetation in one spot1 and the absolute want of it in the other2 but among other refrigerating causes in ,south ,georgia may be enumerated the countless icebergs which float from the antarctic zone1 and which chill1 as they melt1 the waters of the ocean1 and the surrounding air1 which they fill with dense fogs4 ,i have endeavoured in the ,principles of ,geology1 chapters #g4 and #h41 to point out the intimate connexion of climate and the physical geography of the globe1 and the dependence of the mean annual temperature1 not only on the height of the dry land1 but on its distribution in high or low latitudes at particular epochs4 ,if1 for example1 at certain periods of the past1 the antarctic land was less elevated and less extensive than now1 while that at the north pole was higher and more continuous1 the conditions of the northern and southern hemispheres might have been the reverse of what we now witness in regard to climate1 although the mountains of ,scandinavia1 ,scotland1 and ,switzerland1 may have been less elevated than at present4 ,but if in both of the polar regions a considerable area of elevated dry land existed1 such a concurrence of refrigerating conditions in both hemispheres might have created for a time an intensity of cold never experienced since2 and such probably was the state of things during that period of submergence to which ,i have alluded in this chapter4 ,alpine erratics4--,although the arctic regions constitute the great centre from which erratics have travelled southwards in all directions in ,europe and ,north ,america1 yet there are some mountains1 as ,i have already stated1 like those of ,north ,wales and the ,alps1 which have served as separate and independent centres for the dispersion of blocks4 ,in illustration of this fact1 the ,alps deserve particular attention1 not only from their magnitude1 but because they lie beyond the ordinary limits of the northern drift of ,europe1 being situated between the #ddth and #dgth degrees of north latitude4 ,on the flanks of these mountains1 and on the ,subalpine ranges of hills or plains adjoining them1 those appearances which have been so often alluded to1 as distinguishing or accompanying the drift1 between the #ejth and #gjth parallels of north latitude1 suddenly reappear1 to assume in a more southern country their most exaggerated form4 ,where the ,alps are highest1 the largest erratic blocks have been sent forth1 as1 for example1 from the regions of ,mont ,blanc and ,monte ,rosa1 into the adjoining parts of ,france1 ,switzerland1 ,austria1 and ,italy1 while in districts where the great chain sinks in altitude1 as in ,carinthia1 ,carniola1 and elsewhere1 no such rocky fragments1 or a few only and of smaller bulk1 have been detached and transported to a distance4 ,in the year #ahba1 ,m4 ,venetz first announced his opinion that the ,alpine glaciers must formerly have extended far beyond their present limits1 and the proofs appealed to by him in confirmation of this doctrine were afterwards acknowledged by ,m4 ,charpentier1 who strengthened them by new observations and arguments1 and declared1 in #ahcf1 his conviction that the glaciers of the ,alps must once have reached as far as the ,jura1 and have carried thither their moraines across the great valley of ,switzerland4 ,m4 ,agassiz1 after several excursions in the ,alps with ,m4 ,charpentier1 and after devoting himself some years to the study of glaciers1 published1 in #ahdj1 an admirable description of them1 and of the marks which attest the former action of great masses of ice over the entire surface of the ,alps and the surrounding country4#adj-;,a ,he pointed out that the surface of every large glacier is strewed over with gravel and stones detached from the surrounding precipices by frost1 rain1 lightning1 or avalanches4 ,and he described more carefully than preceding writers the long lines of these stones1 which settle on the sides of the glacier1 and are called the lateral moraines2 those found at the lower end of the ice being called terminal moraines4 ,such heaps of earth and boulders every glacier pushes before it when advancing1 and leaves behind it when retreating4 ,when the ,alpine glacier reaches a lower and warmer situation1 about #cjjj or #djjj feet above the sea1 it melts so rapidly that1 in spite of the downward movement of the mass1 it can advance no farther4 ,its precise limits are variable from year to year1 and still more so from century to century2 one example being on record of a recession of half a mile in a single year4 ,we also learn from ,m4 ,venetz1 that whereas1 between the eleventh and fifteenth centuries1 all the ,alpine glaciers were less advanced than now1 they began in the seventeenth and eighteenth centuries to push forward so as to cover roads formerly open1 and to overwhelm forests of ancient growth4 ,these oscillations enable the geologist to note the marks which they leave behind them as they retrograde1 and among these the most prominent1 as before stated1 are the terminal moraines1 or mounds of unstratified earth and stones1 often divided by subsequent floods into hillocks1 which cross the valley like ancient earth-works1 or embankments made to dam up the river4 ,some of these transverse barriers were formerly pointed out by ,saussure below the glacier of the ,rhone1 as proving how far it had once transgressed its present boundaries4 ,on these moraines we see many large angular fragments1 which1 having been carried along on the surface of the ice1 have not had their edges worn off by friction2 but the greater number of the boulders1 even those of large size1 have been well rounded1 not by the power of water1 but by the mechanical force of the ice1 which has pushed them against each other1 or against the rocks flanking the valley4 ,others have fallen down the numerous fissures which intersect the glacier1 where1 being subject to the pressure of the whole mass of ice1 they have been forced along1 and either well rounded or ground down into sand1 or even the finest mud1 of which the moraine is largely constituted4 ,as the terminal moraines are the most prominent of all the monuments left by a receding glacier1 so are they the most liable to obliteration2 for violent floods or debacles are often occasioned in the ,alps by the sudden bursting of what are called glacier-lakes4 ,these temporary sheets of water are caused by the damming up of a river by a glacier which has increased during a succession of cold seasons1 and1 descending from a tributary into the main valley1 has crossed it from side to side4 ,on the failure of this icy barrier1 the accumulated waters are let loose1 which sweep away and level all transverse mounds of gravel and loose boulder below1 and spread their materials in confused and irregular beds over the river-plain4 ,another mark of the former action of glaciers1 in situations where they exist no longer1 is the polished1 striated1 and grooved surfaces of rocks already alluded to4 ,stones which lie underneath the glacier and are pushed along by it1 sometimes adhere to the ice1 and as the mass glides slowly along at the rate of a few inches1 or at the utmost two or three feet1 per day1 abrade1 groove1 and polish the rock1 and the larger blocks are reciprocally grooved and polished by the rock on their lower sides4 ,as the forces both of pressure and propulsion are enormous1 the sand1 acting like emery1 polishes the surface2 the pebbles1 like coarse gravers1 scratch and furrow it2 and the large stones scoop out grooves in it4 ,another effect also of this action1 not yet adverted to1 is called roches moutonnees4 ,projecting eminences of rock are smoothed and worn into the shape of flattened domes1 where the glaciers have passed over them4 ,although the surface of almost every kind of rock1 when exposed in the open air1 wastes away by decomposition1 yet some retain for ages their polished and furrowed exterior2 and1 if they are well protected by a covering of clay or turf1 these marks of abrasion seem capable of enduring for ever4 ,they have been traced in the ,alps to great heights above the present glaciers1 and to great horizontal distances beyond them4 ,there are also found1 on the sides of the ,swiss valleys1 round and deep holes1 with polished sides1 such holes as waterfalls make in the solid rock1 but in places remote from running waters1 and where the form of the surface will not permit us to suppose that any cascade could ever have existed4 ,similar cavities are common in hard rocks1 such as gneiss1 in ,sweden1 where they are called giant caldrons1 and are sometimes #aj feet and more in depth2 but in the ,alps and ,jura they often pass into spoon-shaped excavations and prolonged gutters4 ,we learn from ,m4 ,agassiz that hollows of this form are now cut out by streams of water1 which flow along the surface of glaciers1 and then fall into fissures which are open to the bottom4 ,here1 forming a cascade1 the stream cuts a round cavity in the rock with the gravel and sand1 which it either finds there or carries down with it1 and causes to rotate2 and1 as it usually happens that the glacier is advancing1 a locomotive cascade is produced1 which converts the first circular hole into a deep groove4 ,another effect of a glacier is to lodge a ring of stones round the summit of a conical peak which may happen to project through the ice4 ,if the glacier is lowered greatly by melting1 these circles of large angular fragments1 which are called perched blocks1 are left in a singular situation near the top of a steep hill or pinnacle1 the lower parts of which may be destitute of boulders4 ,alpine blocks on the ,jura4--,now some or all the marks above enumerated1--the moraines1 erratics1 polished surfaces1 domes1 striae1 caldrons1 and perched rocks1 are observed in the ,alps at great heights above the present glaciers1 and far below their actual extremities2 also in the great valley of ,switzerland1 #ej miles broad2 and almost everywhere on the ,jura1 a chain which lies to the north of this valley4 ,the average height of the ,jura is about one third that of the ,alps1 and is now entirely destitute of glaciers1 yet it presents almost everywhere similar moraines1 and the same polished and grooved surfaces1 and water-worn cavities4 ,the erratics1 moreover1 which cover it1 present a phenomenon which has astonished and perplexed the geologist for more than half a century4 ,no conclusion can be more incontestible than that these angular blocks of granite1 gneiss1 and other crystalline formations1 came from the ,alps1 and that they have been brought for a distance of #ej miles and upwards across one of the widest and deepest valleys of the world1 so that they are now lodged on the hills and valleys of a chain composed of limestone and other formations1 altogether distinct from those of the ,alps4 ,their great size and angularity1 after a journey of so many leagues1 has justly excited wonder2 for hundreds of them are as large as cottages2 and one in particular1 celebrated under the name of ,pierre a ,bot1 rests on the side of a hill about #ijj feet above the lake of ,neufchatel1 and is no less than #dj feet in diameter4 ,it will be remarked that these blocks on the ,jura offer an exception to the rule before laid down1 as applicable in general to erratics1 since they have gone from south to north4 ,some of the largest masses of granite and gneiss have been found to contain #ej1jjj and #fj1jjj cubic feet of stone1 and one limestone block near ,devens1 which has travelled #cj miles1 contains #afa1jjj cubic feet1 its angles being sharp and unworn4#adc-;,a ,von ,buch1 ,escher1 and ,studer have shown1 from an examination of the mineral composition of the boulders1 that those on the western ,jura1 near ,neufchatel1 have come from the region of ,mont ,blanc and the ,valais2 those on the middle parts of the ,jura from the ,bernese ,oberland2 and those on the eastern ,jura from the ,alps of the small cantons1 ,glaris1 ,schwytz1 ,uri1 and ,zug4 ,the blocks1 therefore1 of these three great districts have been derived from parts of the ,alps nearest to the localities in the ,jura where we now find them1 as if they had crossed the great valley in a direction at right angles to its length3 the most western stream having followed the course of the ,rhone2 the central1 that of the ,aar2 and the eastern1 that of the two great rivers1 ,reuss and ,limmat4 ,the non-intermixture of these groups of travelled fragments1 except near their confines1 was always regarded as most enigmatical by those who adopted the opinion of ,saussure1 that they were all whirled along by a rapid current of muddy water rushing from the ,alps4 ,m4 ,charpentier first suggested1 as before mentioned1 that the ,swiss glaciers once reached continuously to the ,jura1 and conveyed to them these erratics2 but at the same time he conceived that the ,alps were formerly higher than now4 ,m4 ,agassiz1 on the other hand1 instead of introducing distinct and separate glaciers1 imagines that the whole valley of ,switzerland was filled with ice1 and that one great sheet of it extended from the ,alps to the ,jura1 when the two chains were of the same height as now relatively to each other4 ,such an hypothesis labours under this difficulty1 that the difference of altitude1 when distributed over a space of #ej miles1 gives an inclination of no more than two degrees1 or far less than that of any known glaciers4 ,it has1 however1 since received the able support of ,professor ,james ,forbes1 in his excellent work on the ,alps1 published in #ahdc4 ,in the theory which ,i formerly advanced1 jointly with ,mr4 ,darwin#adc-;,b1 it was suggested that the erratics may have been transferred by floating ice to the ,jura1 at the time when the greater part of that chain1 and the whole of the ,swiss valley to the south1 was under the sea4 ,at that period the ,alps may have attained only half their present altitude1 and may yet have constituted a chain as lofty as the ,chilian ,andes1 which1 in a latitude corresponding to ,switzerland1 now send down glaciers to the head of every sound1 from which icebergs1 covered with blocks of granite1 are floated seaward4#add-;,a ,opposite that part of ,chili where the glaciers abound is situated the island of ,chiloe1 #ajj miles in length1 with a breadth of #cj miles1 running parallel to the continent4 ,the channel which separates it from the main land is of considerable depth1 and #be miles broad4 ,parts of its surface1 like the adjacent coast of ,chili1 are overspread with recent marine shells1 showing an upheaval of the land during a very modern period2 and beneath these shells is a boulder deposit1 in which ,mr4 ,darwin found large travelled blocks4 ,one group of fragments were of granite1 which had evidently come from the ,andes1 while in another place angular blocks of syenite were met with4 ,their arrangement may have been due to successive crops of icebergs issuing from different sounds1 to the heads of which glaciers descend from the ,andes4 ,these icebergs1 taking their departure year after year from distinct points1 may have been stranded repeatedly1 in equally distinct groups1 in bays or creeks of ,chiloe1 and on islets off the coast1 so as afterwards to appear1 some on hills and others in valleys1 when that country and the bed of the adjacent sea had been upheaved4 ,a continuance in future of the elevatory movement1 in the region of the ,andes and of ,chiloe1 might cause the former chain to rival the ,alps in altitude1 and give to ,chiloe a height equal to that of the ,jura4 ,the same rise might dry up the channel between ,chiloe and the main land1 so that it would then represent the great valley of ,switzerland4 ,in the course of these changes1 all parts of ,chiloe and the intervening strait1 having in their turn been a sea-shore1 may have been polished and scratched by coast-ice1 and by innumerable icebergs running aground and grating on the bottom4 ,if we apply this hypothesis to ,switzerland and the ,jura1 we are by no means precluded from the supposition that1 in proportion as the land acquired additional height1 and the bed of the sea emerged1 the ,jura itself may have had its glaciers2 and those existing in the ,alps1 which had at first extended to the sea1 may1 during some part of the period of upheaval1 have been prolonged much farther into the valleys than now4 ,at a later period1 when the climate grew milder1 these glaciers may have entirely disappeared from the ,jura1 and may have receded in the ,alps to their present limits1 leaving behind them in both districts those moraines which now attest the former extension of the ice4#add-;,b ,meteorites in drift4--,before concluding my remarks on the northern drift of the ,old ,world1 ,i shall refer to a fact recently announced1 the discovery of a meteoric stone at a great depth in the alluvium of ,northern ,asia4 ,erman1 in his ,archives of ,russia for #ahda 7p4 #cad471 cites a very circumstantial account drawn up by a ,russian miner of the finding of a mass of meteoric iron in the auriferous alluvium of the ,altai4 ,some small fragments of native iron were first met with in the gold-washings of ,petropawlowsker in the ,mrassker ,circle2 but though they attracted attention1 it was supposed that they must have been broken off from the tools of the workmen4 ,at length1 at the depth of #ca feet #e inches from the surface1 they dug out a piece of iron weighing #ag-a_/b pounds1 of a steel-grey colour1 somewhat harder than ordinary iron1 and1 on analysing it1 found it to consist of native iron1 with a small proportion of nickel1 as usual in meteoric stones4 ,it was buried in the bottom of the deposit where the gravel rested on a flaggy limestone4 ,much brown iron ore1 as well as gold1 occurs in the same gravel1 which appears to be part of that extensive auriferous formation in which the bones of the mammoth1 the ,rhinoceros tichorhinus1 and other extinct quadrupeds abound4 ,no sufficient data are supplied to enable us to determine whether it be of ,post-,pliocene or ,newer ,pliocene date4 ,we ought not1 ,i think1 to feel surprise that we have not hitherto succeeded in detecting the signs of such aerolites in older rocks1 for1 besides their rarity in our own days1 those which fell into the sea 7and it is with marine strata that geologists have usually to deal71 being chiefly composed of native iron1 would rapidly enter into new chemical combinations1 the water and mud being charged with chloride of sodium and other salts4 ,we find that anchors1 cannon1 and other cast-iron implements which have been buried for a few hundred years off our ,english coast have decomposed in part or entirely1 turning the sand and gravel which enclosed them into a conglomerate1 cemented together by oxide of iron4 ,in like manner meteoric iron1 although its rusting would be somewhat checked by the alloy of nickel1 could scarcely ever fail to decompose in the course of thousands of years1 becoming oxide1 sulphuret or carbonate of iron1 and its origin being then no longer distinguishable4 ,the greater the antiquity of rocks1--the oftener they have been heated and cooled1 permeated by gases or by the waters of the sea1 the atmosphere or mineral springs1--the smaller must be the chance of meeting with a mass of native iron unaltered2 but the preservation of the ancient meteorite of the ,altai1 and the presence of nickel in these curious bodies1 renders the recognition of them in deposits of remote periods less hopeless than we might have anticipated4 ,,footnotes3 #acd-;,a ,geol4 ,trans4 #b;d series1 vol4 vi4 p4 #ace4 ,mr4 ,smith of ,jordanhill had arrived at similar conclusions as to climate from the shells of the ,scotch ,pleistocene deposits4 #acd-;,b ,proceedings of ,geol4 ,soc4 ,no4 #fc4 p4 #aai4 #ace-;,a ,travels in ,n4 ,america1 vol4 ii4 p4 #ada4 #ace-;,b ,ibid4 p4 #ii4 chap4 xix4 #acf-;,a ,bulletin ,soc4 ,geol4 de ,france1 tom4 iv4 #b;de ser4 p4 #aaba4 #ach-;,a ,see ,travels in ,n4 ,america1 vol4 i4 chap4 ii4 #adj-;,a ,agassiz1 ,etudes sur les ,glaciers4 #adc-;,a ,archiac1 ,hist4 des ,progres1 c4 vol4 ii4 p4 #bdi4 #adc-;,b ,see ,elements of ,geology1 #b;d ed4 #ahda4 #add-;,a ,darwin's ,journal1 p4 #bhc4 #add-;,b ,more recently ,sir ,r4 ,murchison1 having revisited the ,alps1 has declared his opinion that the great granitic blocks of ,mont ,blanc were translated to the ,jura when the intermediate country was under water4--,paper read to ,geol4 ,soc4 ,london1 ,may #cj1 #ahdi4 ,,chapter ,,xiii4 ,,newer ,,pliocene ,,strata ,,and ,,cavern ,,deposits4 ,chronological classification of ,pleistocene formations1 why difficult--,freshwater deposits in valley of ,thames--,in ,norfolk cliffs--,in ,patagonia--,comparative longevity of species in the mammalia and testacea--,fluvio-marine crag of ,norwich--,newer ,pliocene strata of ,sicily--,limestone of great thickness and elevation--,alternation of marine and volcanic formations--,proofs of slow accumulation--,great geographical changes in ,sicily since the living fauna and flora began to exist--,osseous breccias and cavern deposits--,sicily--,kirkdale--,origin of stalactite--,australian cave-breccias--,geographical relationship of the provinces of living vertebrata and those of the fossil species of the ,pliocene periods--,extinct struthious birds of ,new ,zealand--,teeth of fossil quadrupeds4 ,having in the last chapter treated of the boulder formation and its associated freshwater and marine strata as belonging chiefly to the close of the ,newer ,pliocene period1 we may now proceed to other deposits of the same or nearly the same age4 ,it should1 however1 be stated that it is difficult to draw the line of separation between these modern formations1 especially when we are called upon to compare deposits of marine and freshwater origin1 or these again with the ossiferous contents of caverns4 ,if as often as the carcasses of quadrupeds were buried in alluvium during floods1 or mired in swamps1 or imbedded in lacustrine strata1 a stream of lava had descended and preserved the alluvial or freshwater deposits1 as frequently happened in ,auvergne 7see above1 p4 #hj171 keeping them free from intermixture with strata subsequently formed1 then indeed the task of arranging chronologically the whole series of mammaliferous formations might have been easy1 even though many species were common to several successive groups4 ,but when there have been oscillations in the levels of the land1 accompanied by the widening and deepening of valleys at more than one period1--when the same surface has sometimes been submerged beneath the sea1 after supporting forests and land quadrupeds1 and then raised again1 and subject during each change of level to sedimentary deposition and partial denudation1--and when the drifting of ice by marine currents or by rivers1 during an epoch of intense cold1 has for a season interfered with the ordinary mode of transport1 or with the geographical range of species1 we cannot hope speedily to extricate ourselves from the confusion in which the classification of these ,pleistocene formations is involved4 ,at several points in the valley of the ,thames1 remnants of ancient fluviatile deposits occur1 which may differ considerably in age1 although the imbedded land and freshwater shells in each are of recent species4 ,at ,brentford1 for example1 the bones of the ,siberian ,mammoth1 or ,elephas primigenius1 and the ,rhinoceros tichorhinus1 both of them quadrupeds of which the flesh and hair have been found preserved in the frozen soil of ,siberia1 occur abundantly1 with the bones of an hippopotamus1 aurochs1 short-horned ox1 red deer1 rein-deer1 and great cave-tiger or lion4#adg-;,a ,a similar group has been found fossil at ,maidstone1 in ,kent1 and other places1 agreeing in general specifically with the fossil bones detected in the caverns of ,england4 ,when we see the existing rein-deer and an extinct hippopotamus in the same fluviatile loam1 we are tempted to indulge our imaginations in speculating on the climatal conditions which could have enabled these genera to co-exist in the same region4 ,wherever there is a continuity of land from polar to temperate and equatorial regions1 there will always be points where the southern limit of an arctic species meets the northern range of a southern species2 and if one or both have migratory habits1 like the ,bengal tiger1 the ,american bison1 the musk ox1 and others1 they may each penetrate mutually far into the respective provinces of the other4 ,there may also have been several oscillations of temperature during the periods which immediately preceded and followed the more intense cold of the glacial epoch4 ,the strata bordering the left bank of the ,thames at ,grays ,thurrock1 in ,essex1 are probably of older date than those of ,brentford1 although the associated land and freshwater shells are nearly all1 if not all1 identical with species now living4 ,three of the shells1 however1 are no longer inhabitants of ,great ,britain2 namely1 ,paludina marginata 7fig4 #aab4 p4 #abg471 now living in ,france2 ,unio littoralis 7fig4 #bi4 p4 #bh471 now inhabiting the ,loire2 and ,cyrena consobrina 7fig4 #bf4 p4 #bh474 ,the last-mentioned fossil 7a recent ,egyptian shell of the ,nile7 is very abundant at ,grays1 and deserves notice1 because the genus ,cyrena is now no longer ,european4 ,the rhinoceros occurring in the same beds 7,r4 leptorhinus1 see fig4 #aca4 p4 #afj47 is of a different species from that of ,brentford above mentioned1 and the accompanying elephant belongs to the variety called ,elephas meridionalis1 which1 according to ,,mm4 ,owen and ,h4 von ,meyer1 two high authorities1 is the same species as the ,siberian mammoth1 although some naturalists regard it as distinct4 ,with the above mammalia is also found the ,hippopotamus major1 and what is most remarkable in so modern and northern a deposit1 a monkey1 called by ,owen1 ,macacus pliocenus4 ,the submerged forest already alluded to 7p4 #acj47 as underlying the drift at the base of the cliffs of ,norfolk is associated with a bed of lignite and loam1 in which a great number of fossil bones occur1 apparently of the same group as that of ,grays1 just mentioned4 ,it has sometimes been called the ,elephant bed4 ,one portion of it1 which stretches out under the sea at ,happisburgh1 was overgrown in #ahbj by a bank of recent oysters1 and there the fishermen dredged up1 according to ,woodward1 in the course of thirteen years1 together with the oysters1 above #bjjj mammoths' grinders4#adg-;,b ,another portion of the same continuous stratum has yielded at ,bacton1 ,cromer1 and other places on the coast1 the bones of a gigantic beaver 7,trogontherium ,cuvierii1 ,fischer71 as well as the ox1 horse1 and deer1 and both species of rhinoceros1 ,r4 tichorhinus and ,r4 leptorhinus4 ,in studying these and various other similar assemblages of fossils1 we have a good exemplification of the more rapid rate at which the mammiferous fauna1 as compared to the testaceous1 diverges when traced backwards in time from the recent type4 ,i have before hinted1 that the longevity of species in the class of warm-blooded quadrupeds is less great than in that of the mollusca1 the latter having probably more capacity for enduring those changes of climate and other external circumstances which take place in the course of ages on the earth's surface4 ,this phenomenon is by no means confined to ,europe1 for ,mr4 ,darwin found at ,bahia ,blanca1 in ,south ,america1 lat4 #ci deg4 ,s41 near the northern confines of ,patagonia1 fossil remains of the extinct mammiferous genera ,megatherium1 ,megalonyx1 ,toxodon1 and others1 associated with shells1 almost all of species already ascertained to be still living in the contiguous sea#adh-;,a2 the marine mollusca1 as well as those of rivers1 lakes1 or the land1 having died out more slowly than the terrestrial mammalia4 ,i alluded before 7p4 #abe47 to certain marine strata overlying till near ,glasgow1 and at other points on the ,clyde1 in which the shells are for the most part ,british1 with an intermixture of some arctic species2 while others1 about a tenth of the whole1 are supposed to be extinct4 ,this formation may also be called ,newer ,pliocene4 ,fluvio-marine crag of ,norwich4--,at several places within five miles of ,norwich1 on both banks of the ,yare1 beds of sand1 loam1 and gravel1 provincially termed crag1 occur1 in which there is a mixture of marine1 land1 and freshwater shells1 with ichthyolites and bones of mammalia4 ,it is clear that these beds have been accumulated at the bottom of the sea near the mouth of a river4 ,they form patches of variable thickness1 resting on white chalk1 and are covered by a dense mass of stratified flint gravel4 ,the surface of the chalk is often perforated to the depth of several inches by the ,pholas crispata1 each fossil shell still remaining at the bottom of its cylindrical cavity1 now filled up with loose sand which has fallen from the incumbent crag4 ,this species of ,pholas still exists and drills the rocks between high and low water on the ,british coast4 ,the most common shells of these strata1 such as ,fusus striatus1 ,turritella terebra1 ,cardium edule1 and ,cyprina islandica1 are now abundant in the ,british seas2 but with them are some extinct species1 such as ,nucula ,cobboldiae 7fig4 #abj47 and ,tellina obliqua 7fig4 #aba474 ,natica helicoides 7fig4 #abb47 is an example of a species formerly known only as fossil1 but which has now been found living in our seas4 ,among the accompanying bones of mammalia is the ,mastodon angustidens#adi-;,a 7see fig4 #acj471 a portion of the upper jawbone with a tooth having been found by ,mr4 ,wigham at ,postwick1 near ,norwich4 ,as this species has also been found in the ,red ,crag1 both at ,sutton and at ,felixstow1 and had hitherto been regarded as characteristic of formations older than the ,pleistocene1 it may possibly have been washed out of the ,red into the ,norwich ,crag4 ,illustration3 ,fig4 #abj4 ,nucula ,cobboldiae4 ,illustration3 ,fig4 #aba4 ,tellina obliqua4 ,illustration3 ,fig4 #abb4 ,natica helicoides1 ,johnston4 ,among the bones1 however1 respecting the authenticity of which there seems no doubt1 may be mentioned those of the elephant1 horse1 pig1 deer1 and the jaws and teeth of field mice 7fig4 #ada474 ,i have seen the tusk of an elephant from ,bramerton near ,norwich1 to which1 many serpulae were attached1 showing that it had lain for some time at the bottom of the sea of the ,norwich ,crag4 ,at ,thorpe1 near ,aldborough1 and at ,southwold1 in ,suffolk1 this fluvio-marine formation is well exposed in the sea-cliffs1 consisting of sand1 shingle1 loam1 and laminated clay4 ,some of the strata there bear the marks of tranquil deposition1 and in one section a thickness of #dj feet is sometimes exposed to view4 ,some of the lamellibranchiate shells have both valves united1 although mixed with land and freshwater testacea1 and with the bones and teeth of elephant1 rhinoceros1 horse1 and deer4 ,captain ,alexander1 with whom ,i examined these strata in #ahce1 showed me a bed rich in marine shells1 in which he had found a large specimen of the ,fusus striatus1 filled with sand1 and in the interior of which was the tooth of a horse4 ,among the freshwater shells ,i obtained the ,cyrena consobrina 7fig4 #bf4 p4 #bh471 before mentioned1 supposed to agree with a species now living in the ,nile4 ,i formerly classed the ,norwich ,crag as older ,pliocene1 conceiving that more than a third of the fossil testacea were extinct2 but there now seems good reason for believing that several of the rarer shells obtained from these strata do not really belong to a contemporary fauna1 but have been washed out of the older beds of the ,red ,crag2 while other species1 once supposed to have died out1 have lately been met with living in the ,british seas4 ,according to ,mr4 ,searles ,wood1 the total number of marine species does not exceed seventy-six1 of which one tenth only are extinct4 ,of the fourteen associated freshwater shells1 all the species appear to be living4 ,strata containing the same shells as those near ,norwich have been found by ,mr4 ,bean1 at ,bridlington1 in ,yorkshire4 ,newer ,pliocene strata of ,sicily4--,in no part of ,europe are the ,newer ,pliocene formations seen to enter so largely into the structure of the earth's crust1 or to rise to such heights above the level of the sea1 as in ,sicily4 ,they cover nearly half the island1 and near its centre1 at ,castrogiovanni1 they reach an elevation of #cjjj feet4 ,they consist principally of two divisions1 the upper calcareous1 the lower argillaceous1 both of which may be seen at ,syracuse1 ,girgenti1 and ,castrogiovanni4 ,according to ,philippi1 to whom we are indebted for the best account of the tertiary shells of this island1 thirty-five species out of one hundred and twenty-four obtained from the beds in central ,sicily are extinct4 ,of the remainder1 which still live1 five species are no longer inhabitants of the ,mediterranean4 ,when ,i visited ,sicily in #ahbh ,i estimated the proportion of living species as somewhat greater1 partly because ,i confounded with the tertiary formation of central ,sicily the strata at the base of ,etna1 and some other localities1 where the fossils are now proved to agree entirely with the present ,mediterranean fauna4 ,philippi came to the conclusion1 that in ,sicily there is a gradual passage from beds containing #gj per cent4 of recent shells1 to those in which the whole of the fossils are identical with recent species2 but his tables appear scarcely to bear out so important a generalization1 several of the places cited by him in confirmation having as yet furnished no more than twenty or thirty species of testacea4 ,the ,sicilian beds in question probably belong to about the same period as the ,norwich ,crag1 although a geologist1 accustomed to see nearly all the ,pleistocene formations in the north of ,europe occupying low grounds and very incoherent in texture1 is naturally surprised to behold formations of the same age so solid and stony1 of such thickness1 and attaining so great an elevation above the level of the sea4 ,the upper or calcareous member of this group in ,sicily consists in some places of a yellowish-white stone1 like the calcaire grossier of ,paris1 in others1 of a rock nearly as compact as marble4 ,its aggregate thickness amounts sometimes to #gjj or #hjj feet4 ,it usually occurs in regular horizontal beds1 and is occasionally intersected by deep valleys1 such as those of ,sortino and ,pentalica1 in which are numerous caverns4 ,the fossils are in every stage of preservation1 from shells retaining portions of their animal matter and colour1 to others which are mere casts4 ,the limestone passes downwards into a sandstone and conglomerate1 below which is clay and blue marl1 like that of the ,subapennine hills1 from which perfect shells and corals may be disengaged4 ,the clay sometimes alternates with yellow sand4 ,south of the plain of ,catania is a region in which the tertiary beds are intermixed with volcanic matter1 which has been for the most part the product of submarine eruptions4 ,it appears that1 while the clay1 sand1 and yellow limestone before mentioned were in course of deposition at the bottom of the sea1 volcanos burst out beneath the waters1 like that of ,graham ,island1 in #ahca1 and these explosions recurred again and again at distant intervals of time4 ,volcanic ashes and sand were showered down and spread by the waves and currents so as to form strata of tuff1 which are found intercalated between beds of limestone and clay containing marine shells1 the thickness of the whole mass exceeding #bjjj feet4 ,the fissures through which the lava rose may be seen in many places forming what are called dikes4 ,in part of the region above alluded to1 as1 for example1 near ,lentini1 a conglomerate occurs in which ,i observed many pebbles of volcanic rocks covered by full grown serpulae4 ,we may explain the origin of these by supposing that there were some small volcanic islands which may have been destroyed from time to time by the waves1 as ,graham ,island has been swept away since #ahca4 ,the rounded blocks and pebbles of solid volcanic matter1 after being rolled for a time on the beach of such temporary islands1 were carried at length into some tranquil part of the sea1 where they lay for years1 while the marine serpulae adhered to them1 their shells growing and covering their surface1 as they are seen adhering to the shell figured in p4 #bb4 ,finally1 the bed of pebbles was itself covered with strata of shelly limestone4 ,at ,vizzini1 a town not many miles distant to the ,s4,w41 ,i remarked another striking proof of the gradual manner in which these modern rocks were formed1 and the long intervals of time which elapsed between the pouring out of distinct sheets of lava4 ,a bed of oysters no less than #bj feet in thickness rests upon a current of basaltic lava4 ,the oysters are perfectly identifiable with our common eatable species4 ,upon the oyster bed1 again1 is superimposed a second mass of lava1 together with tuff or peperino4 ,in the midst of the same alternating igneous and aqueous formations is seen near ,galieri1 not far from ,vizzini1 a horizontal bed1 about a foot and a half in thickness1 composed entirely of a common ,mediterranean coral 7,caryophyllia caespitosa1 ,lam474 ,these corals stand erect as they grew2 and1 after being traced for hundreds of yards1 are again found at a corresponding height on the opposite side of the valley4 ,illustration3 ,fig4 #abc4 ,caryophyllia caespitosa1 ,lam4 7,cladocora caespitosa1 ,ehr47 a4 ,stem with young stem growing from its side4 a994 ,young stem of same twice magnified4 b4 ,portion of branch1 twice magnified1 with the base of a lateral branch2 the exterior ridges of the main branch appearing through the lamellae of the lateral one4 c4 ,transverse section of same1 proving1 by the integrity of the main branch1 that the lateral one did not originate in a subdivision of the animal4 d4 ,a branch1 having at its base another laterally united to it1 and two young corals at its upper part4 e4 ,a main branch1 with a full grown lateral one4 f4 ,a perfect terminal star4 ,the corals are usually branched1 but not by the division of the animals as some have supposed1 but by the attachment of young individuals to the sides of the older ones2 and we must understand this mode of increase1 in order to appreciate the time which was required for the building up of the whole bed of coral during the growth of many successive generations4#aeb-;,a ,among the other fossil shells met with in these ,sicilian strata1 which still continue to abound in the ,mediterranean1 no shell is more conspicuous1 from its size and frequent occurrence1 than the great scallop1 ,pecten jacobaeus 7see fig4 #abd471 now so common in the neighbouring seas4 ,we see this shell in the calcareous beds at ,palermo in great numbers1 in the limestone at ,girgenti1 and in that which alternates with volcanic rocks in the country between ,syracuse and ,vizzini1 often at great heights above the sea4 ,illustration3 ,fig4 #abd4 ,pecten jacobaeus2 half natural size4 ,the more we reflect on the preponderating number of these recent shells1 the more we are surprised at the great thickness1 solidity1 and height above the sea of the rocky masses in which they are entombed1 and the vast amount of geographical change which has taken place since their origin4 ,it must be remembered that1 before they began to emerge1 the uppermost strata of the whole must have been deposited under water4 ,in order1 therefore1 to form a just conception of their antiquity1 we must first examine singly the innumerable minute parts of which the whole is made up1 the successive beds of shells1 corals1 volcanic ashes1 conglomerates1 and sheets of lava2 and we must afterwards contemplate the time required for the gradual upheaval of the rocks1 and the excavation of the valleys4 ,the historical period seems scarcely to form an appreciable unit in this computation1 for we find ancient ,greek temples1 like those of ,girgenti 7,agrigentum71 built of the modern limestone of which we are speaking1 and resting on a hill composed of the same2 the site having remained to all appearance unaltered since the ,greeks first colonised the island4 ,the modern geological date of the rocks in this region leads to another singular and unexpected conclusion1 namely1 that the fauna and flora of a large part of ,sicily are of higher antiquity than the country itself1 having not only flourished before the lands were raised from the deep1 but even before their materials were brought together beneath the waters4 ,the chain of reasoning which conducts us to this opinion may be stated in a few words4 ,the larger part of the island has been converted from sea into land since the ,mediterranean was peopled with nearly all the living species of testacea and zoophytes4 ,we may therefore presume that1 before this region emerged1 the same land and river shells1 and almost all the same animals and plants1 were in existence which now people ,sicily2 for the terrestrial fauna and flora of this island are precisely the same as that of other lands surrounding the ,mediterranean4 ,there appear to be no peculiar or indigenous species1 and those which are now established there must be supposed to have migrated from pre-existing lands1 just as the plants and animals of the ,neapolitan territory have colonised ,monte ,nuovo1 since that volcanic cone was thrown up in the sixteenth century4 ,such conclusions throw a new light on the adaptation of the attributes and migratory habits of animals and plants to the changes which are unceasingly in progress in the physical geography of the globe4 ,it is clear that the duration of species is so great1 that they are destined to outlive many important revolutions in the configuration of the earth's surface2 and hence those innumerable contrivances for enabling the subjects of the animal and vegetable creation to extend their range2 the inhabitants of the land being often carried across the ocean1 and the aquatic tribes over great continental spaces4 ,it is obviously expedient that the terrestrial and fluviatile species should not only be fitted for the rivers1 valleys1 plains1 and mountains which exist at the era of their creation1 but for others that are destined to be formed before the species shall become extinct2 and1 in like manner1 the marine species are not only made for the deep and shallow regions of the ocean existing at the time when they are called into being1 but for tracts that may be submerged or variously altered in depth during the time that is allotted for their continuance on the globe4 ,,osseous ,,breccias ,,and ,,deposits ,,in ,,caves ,,of ,,the ,,pliocene ,,period4 ,sicily4--,caverns filled with marine breccias1 at the base of ancient sea-cliffs1 have been already mentioned in the sixth chapter2 and it was noticed1 respecting the cave of ,san ,ciro1 near ,palermo 7p4 #ge471 that upon a bed of sand filled with sea-shells1 almost all of recent species1 rests a breccia 7b1 fig4 #ic471 composed of fragments of calcareous rock1 and the bones of animals4 ,in the sand at the bottom of that cave1 ,dr4 ,philippi found about forty-five marine shells1 all clearly identical with recent species1 except two or three4 ,the bones in the incumbent breccia are chiefly those of the mammoth 7,e4 primigenius71 with some belonging to an hippopotamus1 distinct from the recent species1 and smaller than that usually found fossil4 7,see fig4 #acb47 ,several species of deer also1 and1 according to some accounts1 the remains of a bear1 were discovered4 ,these mammalia are probably referable to the ,post-,pliocene period4 ,the ,newer ,pliocene tertiary limestone of the south of ,sicily1 already described1 is sometimes full of caverns2 and the student will at once perceive that all the quadrupeds of which the remains are found in the stalactite of these caverns1 being of later origin than the rocks1 must be referable to the close of the tertiary epoch1 if not of still later date4 ,the situation of one of these caves1 in the valley of ,sortino1 is represented in the annexed section4 ,illustration3 ,fig4 #abe4 ,cross section4 a4 ,alluvium1 containing the remains of quadrupeds b1 b4 ,deposits in caves1 for the most part extinct4 ,c4 ,limestone1 containing the remains of shells1 of which between #gj and #hj per cent4 are recent4 ,england4--,in a cave at ,kirkdale1 about twenty-five miles ,n4,n4,e4 of ,york1 the remains of about #cjj hyaenas1 belonging to individuals of every age1 have been detected4 ,the species 7,hyaena spelaea7 is extinct1 and was larger than the fierce ,hyaena crocuta of ,south ,africa1 which it most resembled4 ,dr4 ,buckland1 after carefully examining the spot1 proved that the ,hyaenas must have lived there2 a fact attested by the quantity of their dung1 which1 as in the case of the living hyaena1 is of nearly the same composition as bone1 and almost as durable4 ,in the cave were found the remains of the ox1 young elephant1 hippopotamus1 rhinoceros1 horse1 bear1 wolf1 hare1 water-rat1 and several birds4 ,all the bones have the appearance of having been broken and gnawed by the teeth of the hyaenas2 and they occur confusedly mixed in loam or mud1 or dispersed through a crust of stalagmite which covers it4 ,in these and many other cases it is supposed that portions of herbivorous quadrupeds have been dragged into caverns by beasts of prey1 and have served as their food1 an opinion quite consistent with the known habits of the living hyaena4 ,no less than thirty-seven species of mammalia are enumerated by ,professor ,owen as having been discovered in the caves of the ,british islands1 of which eighteen appear to be extinct1 while the others still survive in ,europe4 ,they were not washed to the spots where the fossils now occur by a great flood2 but lived and died1 one generation after another1 in the places where they lie buried4 ,among other arguments in favour of this conclusion may be mentioned the great numbers of the shed antlers of deer discovered in caves and in freshwater strata throughout ,england4#aee-;,a ,examples also occur of fissures into which animals have fallen from time to time1 or have been washed in from above1 together with alluvial matter and fragments of rock detached by frost1 forming a mass which may be united into a bony breccia by stalagmitic infiltrations4 ,frequently we discover a long suite of caverns connected by narrow and irregular galleries1 which hold a tortuous course through the interior of mountains1 and seem to have served as the subterranean channels of springs and engulphed rivers4 ,many streams in the ,morea are now carrying bones1 pebbles1 and mud into underground passages of this kind4#aee-;,b ,if1 at some future period1 the form of that country should be wholly altered by subterranean movements and new valleys shaped out by denudation1 many portions of the former channels of these engulphed streams may communicate with the surface1 and become the dens of wild beasts1 or the recesses to which quadrupeds retreat to die4 ,certain caves of ,france1 ,germany1 and ,belgium1 may have passed successively through these different conditions1 and in their last state may have remained open to the day for several tertiary periods4 ,it is nevertheless remarkable1 that on the continent of ,europe1 as in ,england1 the fossil remains of mammalia belong almost exclusively to those of the ,newer ,pliocene and ,post-,pliocene periods1 and not to the ,miocene or ,eocene epochs1 and when they are accompanied by land or river shells1 these agree in great part1 or entirely1 with recent species4 ,as the preservation of the fossil bones is due to a slow and constant supply of stalactite1 brought into the caverns by water dropping from the roof1 the source and origin of this deposit has been a subject of curious inquiry4 ,the following explanation of the phenomenon has been recently suggested by the eminent chemist ,liebig4 ,on the surface of ,franconia1 where the limestone abounds in caverns1 is a fertile soil1 in which vegetable matter is continually decaying4 ,this mould or humus1 being acted on by moisture and air1 evolves carbonic acid which is dissolved by rain4 ,the rain water1 thus impregnated1 permeates the porous limestone1 dissolves a portion of it1 and afterwards1 when the excess of carbonic acid evaporates in the caverns1 parts with the calcareous matter1 and forms stalactite4 ,australian cave-breccias4--,ossiferous breccias are not confined to ,europe1 but occur in all parts of the globe2 and those lately discovered in fissures and caverns in ,australia correspond closely in character with what has been called the bony breccia of the ,mediterranean1 in which the fragments of bone and rock are firmly bound together by a red ochreous cement4 ,some of these caves have been examined by ,sir ,t4 ,mitchell in the ,wellington ,valley1 about #baj miles west of ,sidney1 on the river ,bell1 one of the principal sources of the ,macquarie1 and on the ,macquarie itself4 ,the caverns often branch off in different directions through the rock1 widening and contracting their dimensions1 and the roofs and floors are covered with stalactite4 ,the bones are often broken1 but do not seem to be water-worn4 ,in some places they lie imbedded in loose earth1 but they are usually included in a breccia4 ,the remains found most abundantly are those of the kangaroo1 of which there are four species1 besides which the genera ,hypsiprymnus1 ,phalangista1 ,phascolomys1 and ,dasyurus1 occur4 ,there are also bones1 formerly conjectured by some osteologists to belong to the hippopotamus1 and by others to the dugong1 but which are now referred by ,mr4 ,owen to a marsupial genus1 allied to the ,wombat4 ,illustration3 ,fig4 #abf4 ,macropus atlas1 ,owen4 a4 permanent false molar1 in the alveolus4 ,illustration3 ,fig4 #abg4 ,lowest jaw of largest living species of kangaroo4 7,macropus major47 ,in the fossils above enumerated1 several species are larger than the largest living ones of the same genera now known in ,australia4 ,the annexed figure of the right side of a lower jaw of a kangaroo 7,macropus atlas1 ,owen7 will at once be seen to exceed in magnitude the corresponding part of the largest living kangaroo1 which is represented in fig4 #abg4 ,in both these specimens part of the substance of the jaw has been broken open1 so as to show the permanent false molar 7a4 fig4 #abf47 concealed in the socket4 ,from the fact of this molar not having been cut1 we learn that the individual was young1 and had not shed its first teeth4 ,in fig4 #abh4 a front tooth of the same species of kangaroo is represented4 ,illustration3 ,fig4 #abh4 ,incisor of ,macropus4 ,whether the breccias1 above alluded to1 of the ,wellington ,valley1 appertain strictly to the ,pliocene period cannot be affirmed with certainty1 until we are more thoroughly acquainted with the recent quadrupeds of the same district1 and until we learn what species of fossil land shells1 if any1 are buried in the deposits of the same caves4 ,the reader will observe that all these extinct quadrupeds of ,australia belong to the marsupial family1 or1 in other words1 that they are referable to the same peculiar type of organization which now distinguishes the ,australian mammalia from those of other parts of the globe4 ,this fact is one of many pointing to a general law deducible from the fossil vertebrate and invertebrate animals of the eras immediately antecedent to the human1 namely1 that the present geographical distribution of organic forms dates back to a period anterior to the creation of existing species2 in other words1 the limitation of particular genera or families of quadrupeds1 mollusca1 c41 to certain existing provinces of land and sea1 began before the species now contemporary with man had been introduced into the earth4 ,mr4 ,owen1 in his excellent ,history of ,british ,fossil ,mammals1 has called attention to this law1 remarking that the fossil quadrupeds of ,europe and ,asia differ from those of ,australia or ,south ,america4 ,we do not find1 for example1 in the ,europaeo-,asiatic province fossil kangaroos or armadillos1 but the elephant1 rhinoceros1 horse1 bear1 hyaena1 beaver1 hare1 mole1 and others1 which still characterize the same continent4 ,in like manner in the ,pampas of ,south ,america the skeletons of ,megatherium1 ,megalonyx1 ,glyptodon1 ,mylodon1 ,toxodon1 ,macrauchenia1 and other extinct forms1 are analogous to the living sloth1 armadillo1 cavy1 capybara1 and llama4 ,the fossil quadrumana1 also associated with some of these forms in the ,brazilian caves1 belong to the ,platyrrhine family of monkeys1 now peculiar to ,south ,america4 ,that the extinct fauna of ,buenos ,ayres and ,brazil was very modern has been shown by its relation to deposits of marine shells1 agreeing with those now inhabiting the ,atlantic2 and when in ,georgia in #ahde1 ,i ascertained that the ,megatherium1 ,mylodon1 ,harlanus americanus 7,owen71 ,equus curvidens1 and other quadrupeds allied to the ,pampean type were posterior in date to beds containing marine shells belonging to forty-five recent species of the neighbouring sea4 ,there are indeed some cosmopolite genera1 such as the ,mastodon 7a genus of the elephant family71 and the horse1 which were simultaneously represented by different fossil species in ,europe1 ,north ,america1 and ,south ,america2 but these few exceptions can by no means invalidate the rule which has been thus expressed by ,professor ,owen1 that in the highest organized class of animals the same forms were restricted to the same great provinces at the ,pliocene periods as they are at the present day4 ,however modern1 in a geological point of view1 we may consider the ,pleistocene epoch1 it is evident that causes more general and powerful than the intervention of man have occasioned the disappearance of the ancient fauna from so many extensive regions4 ,not a few of the species had a wide range2 the same ,megatherium1 for instance1 extended from ,patagonia and the river ,plata in ,south ,america1 between latitudes #ca deg4 and #ci deg4 south1 to corresponding latitudes in ,north ,america1 the same animal being also an inhabitant of the intermediate country of ,brazil1 where its fossil remains have been met with in caves4 ,the extinct elephant1 likewise1 of ,georgia 7,elephas primigenius7 has been traced in a fossil state northward from the river ,alatamaha1 in lat4 #cc deg4 #ej' ,n4 to the polar regions1 and then again in the eastern hemisphere from ,siberia to the south of ,europe4 ,if it be objected that1 notwithstanding the adaptation of such quadrupeds to a variety of climates and geographical conditions1 their great size exposed them to extermination by the first hunter tribes1 we may observe that the investigations of ,lund and ,clausen in the ossiferous limestone caves of ,brazil have demonstrated that these large mammalia were associated with a great many smaller quadrupeds1 some of them as diminutive as field mice1 which have all died out together1 while the land shells formerly their contemporaries still continue to exist in the same countries4 ,as we may feel assured that these minute quadrupeds could never have been extirpated by man1 so we may conclude that all the species1 small and great1 have been annihilated one after the other1 in the course of indefinite ages1 by those changes of circumstances in the organic and inorganic world which are always in progress1 and are capable in the course of time of greatly modifying the physical geography1 climate1 and all other conditions on which the continuance upon the earth of any living being must depend4#aeh-;,a ,the law of geographical relationship above alluded to1 between the living vertebrata of every great zoological province and the fossils of the period immediately antecedent1 even where the fossil species are extinct1 is by no means confined to the mammalia4 ,new ,zealand1 when first examined by ,europeans1 was found to contain no indigenous land quadrupeds1 no kangaroos1 or opossums1 like ,australia2 but a wingless bird abounded there1 the smallest living representative of the ostrich family1 called the ,xivi1 by the natives 7,apteryx74 ,in the fossils of the ,post-,pliocene and ,pleistocene period in this same island1 there is the like absence of kangaroos1 opossums1 wombats1 and the rest2 but in their place a prodigious number of well preserved specimens of gigantic birds of the struthious order1 called by ,owen ,dinornis and ,palapteryx1 which are entombed in superficial deposits4 ,these genera comprehended many species1 some of which were #d1 some #g1 others #i1 and others #aa feet in height6 ,it seems doubtful whether any contemporary mammalia shared the land with this population of gigantic feathered bipeds4 ,to those who have never studied comparative anatomy it may seem scarcely credible1 that a single bone taken from any part of the skeleton may enable a skilful osteologist to distinguish1 in many cases1 the genus1 and sometimes the species1 of quadruped to which it belonged4 ,although few geologists can aspire to such knowledge1 which must be the result of long practice and study1 they will nevertheless derive great advantage from learning what is comparatively an easy task1 to distinguish the principal divisions of the mammalia by the forms and characters of their teeth4 ,the annexed figures1 all taken from original specimens1 may be useful in assisting the student to recognize the teeth of many genera most frequently found fossil in ,europe3-- ,illustration3 ,fig4 #abi4 ,elephas primigenius 7or ,mammoth72 molar of upper jaw1 right side2 one third of nat4 size4 a4 grinding surface4 b4 side view4 ,illustration3 ,fig4 #acj4 ,mastodon angustidens 7,norwich ,crag1 ,postwick1 also found in ,red ,crag1 see p4 #adi472 second true molar1 left side1 upper jaw2 grinding surface1 nat4 size4 7,see p4 #adi47 ,illustration3 ,fig4 #aca4 ,rhinoceros4 ,rhinoceros leptorhinus2 fossil from freshwater beds of ,grays1 ,essex 7see p4 #adg472 penultimate molar1 lower jaw1 left side2 two-thirds of nat4 size4 ,illustration3 ,fig4 #acb4 ,hippopotamus4 ,hippopotamus2 from cave near ,palermo 7see p4 #aed472 molar tooth2 two-thirds of nat4 size4 ,illustration3 ,fig4 #acc4 ,pig4 ,sus scrofa1 ,lin4 7common pig72 from shell-marl1 ,forfarshire2 posterior molar1 lower jaw1 nat4 size4 ,illustration3 ,fig4 #acd4 ,horse4 ,equus caballus1 ,lin4 7common horse72 from the shell marl1 ,forfarshire2 second molar1 lower jaw4 a4 grinding surface1 two-thirds nat4 size4 b4 side view of same1 half nat4 size4 ,illustration3 ,fig4 #ace4 ,tapir4 ,tapirus ,americanus2 recent2 third molar1 upper jaw2 nat4 size4 ,illustration3 ,fig4 #acf4 a4 b4 ,deer4 ,elk 7,cervus alces1 ,lin472 recent2 molar of upper jaw4 a4 grinding surface4 b4 side view2 two-thirds of nat4 size4 ,illustration3 ,fig4 #acg4 c4 d4 ,ox4 ,ox1 common1 from shell marl1 ,forfarshire2 true molar upper jaw2 two-thirds nat4 size4 c4 grinding surface4 d4 side view4 ,illustration3 ,fig4 #ach4 ,bear4 a4 canine tooth or tusk of bear 7,ursus spelaeus72 from cave near ,liege4 b4 molar of left side1 upper jaw2 one third of nat4 size4 ,illustration3 ,fig4 #aci4 ,tiger4 c4 canine tooth of tiger 7,felis tigris72 recent4 d4 outside view of posterior molar1 lower jaw2 one-third of nat4 size4 ,illustration3 ,fig4 #adj4 ,hyaena spelaea2 second molar1 left side1 lower jaw2 nat4 size4 ,cave of ,kirkdale4 7,see p4 #aed47 ,illustration3 ,fig4 #ada4 ,teeth of a new species of ,arvicola 7field-mouse72 from the ,norwich ,crag4 7,see p4 #adi47 a4 grinding surface4 b4 side view of same4 c4 nat4 size of a and b4 ,,footnotes3 #adg-;,a ,morris1 ,geol4 ,soc4 ,proceed41 #ahdi4 #adg-;,b ,woodward's ,geology of ,norfolk4 #adh-;,a ,zool4 of ,beagle1 part #a4 pp4 #i4 #aaa4 #adi-;,a ,owen1 ,brit4 ,foss4 ,mamm4 #bga4 ,mastodon longirostris1 ,kaup1 see ibid4 #aeb-;,a ,i am indebted to ,mr4 ,lonsdale for the details above given respecting the structure of this coral4 #aee-;,a ,owen1 ,brit4 ,foss4 ,mam4 xxvi41 and ,buckland1 ,rel4 ,dil4 #ai4 #bd4 #aee-;,b ,see ,principles of ,geology4 #aeh-;,a ,see ,principles of ,geology1 chaps4 xli4 to xliv4 ,,chapter ,,xiv4 ,,older ,,pliocene ,,and ,,miocene ,,formations4 ,strata of ,suffolk termed ,red and ,coralline crag--,fossils1 and proportion of recent species--,depth of sea and climate--,reference of ,suffolk crag to the older ,pliocene period--,migration of many species of shells southwards during the glacial period--,fossil whales--,sub- apennine beds--,asti1 ,sienna1 ,rome--,miocene formations--,faluns of ,touraine--,depth of sea and littoral character of fauna--,tropical climate implied by the testacea--,proportion of recent species of shells--,faluns more ancient than the ,suffolk crag--,miocene strata of ,bordeaux and ,piedmont--,molasse of ,switzerland--,tertiary strata of ,lisbon--,older ,pliocene and ,miocene formations in the ,united ,states--,sewalik ,hills in ,india4 ,the older ,pliocene strata1 which next claim our attention1 are chiefly confined1 in ,great ,britain1 to the eastern part of the county of ,suffolk1 where1 like the ,norwich beds already described1 they are called ,crag1 a provincial name given particularly to those masses of shelly sand which have been used from very ancient times in agriculture1 to fertilize soils deficient in calcareous matter4 ,the relative position of the red crag in ,essex to the ,london clay1 may be understood by reference to the accompanying diagram 7fig4 #adb474 ,illustration3 ,fig4 #adb4 ,cross section4 ,these deposits1 judging by the shells which they contain1 appear1 according to ,professor ,edward ,forbes1 to have been formed in a sea of moderate depth1 generally from #ae to #be fathoms deep1 although in some few spots perhaps deeper4 ,but they may1 nevertheless1 have been accumulated at the distance of #dj or #ej miles from land4 ,the ,suffolk crag is divisible into two masses1 the upper of which has been termed the ,red1 and the lower the ,coralline ,crag4#afb-;,a ,the upper deposit consists chiefly of quartzose sand1 with an occasional intermixture of shells1 for the most part rolled1 and sometimes comminuted4 ,the lower or ,coralline crag is of very limited extent1 ranging over an area about #bj miles in length1 and #c or #d in breadth1 between the rivers ,alde and ,stour4 ,it is generally calcareous and marly--a mass of shells and small corals1 passing occasionally into a soft building stone4 ,at ,sudbourn1 near ,orford1 where it assumes this character1 are large quarries1 in which the bottom of it has not been reached at the depth of #ej feet4 ,at some places in the neighbourhood1 the softer mass is divided by thin flags of hard limestone1 and corals placed in the upright position in which they grew4 ,the ,red crag is distinguished by the deep ferruginous or ochreous colour of its sands and fossils1 the ,coralline by its white colour4 ,both formations are of moderate thickness2 the red crag rarely exceeding #dj1 and the coralline seldom amounting to #bj1 feet4 ,but their importance is not to be estimated by the density of the mass of strata or its geographical extent1 but by the extraordinary richness of its organic remains1 belonging to a very peculiar type1 which seems to characterize the state of the living creation in the north of ,europe during the older ,pliocene era4 ,for a large collection of the fish1 echinoderms1 shells1 and corals of the deposits in ,suffolk1 we are indebted to the labours of ,mr4 ,searles ,wood4 ,of testacea alone he has obtained from #bcj species from the ,red1 and #cde from the ,coralline crag1 about #aej being common to each4 ,the proportion of recent species in the new group is considered by ,mr4 ,wood to be about #gjafb-;,b per cent41 and that in the older or coralline about #fj4 ,when ,i examined these shells of ,suffolk in #ahce1 with the assistance of ,dr4 ,beck1 ,mr4 ,george ,sowerby1 ,mr4 ,searles ,wood1 and other eminent conchologists1 ,i came to the opinion that the extinct species predominated very decidedly in number over the living4 ,recent investigations1 however1 have thrown much new light on the conchology of the ,arctic1 ,scandinavian1 ,british1 and ,mediterranean ,seas4 ,many of the species formerly known only as fossils of the ,crag1 and supposed to have died out1 have been dredged up in a living state from depths not previously explored4 ,other recent species1 before regarded as distinct from the nearest allied ,crag fossils1 have been observed1 when numerous individuals were procured1 to be liable to much greater variation1 both in size and form1 than had been suspected1 and thus have been identified4 ,consequently1 the ,crag fauna has been found to approach much more nearly to the recent fauna of the ,northern1 ,british1 and ,mediterranean ,seas than had been imagined4 ,the analogy of the whole group of testacea to the ,european type is very marked1 whether we refer to the large development of certain genera in number of species or to their size1 or to the suppression or feeble representation of others4 ,the indication also afforded by the entire fauna of a climate not much warmer than that now prevailing in corresponding latitudes1 prepares us to believe that they are not of higher antiquity than the ,older ,pliocene era4#afc-;,a ,illustration3 ,fig4 #adc4 ,section near ,ipswich1 in ,suffolk4 a4 ,red crag4 b4 ,coralline crag4 c4 ,london clay4 ,the position of the red crag in ,essex to the subjacent ,london clay and chalk has been already pointed out 7fig4 #adb474 ,whenever the two divisions are met with in the same district1 the red crag lies uppermost2 and1 in some cases1 as in the section represented in fig4 #adc41 it is observed that the older or coralline mass b had suffered denudation before the newer formation a was thrown down upon it4 ,at ,d there is not only a distinct cliff1 #h or #aj feet high1 of coralline crag1 running in a direction ,n4,e4 and ,s4,w41 against which the red crag abuts with its horizontal layers2 but this cliff occasionally overhangs4 ,the rock composing it is drilled everywhere by ,pholades1 the holes which they perforated having been afterwards filled with sand and covered over when the newer beds were thrown down4 ,as the older formation is shown by its fossils to have accumulated in a deeper sea 7#ae1 and sometimes #be1 fathoms deep or more71 there must no doubt have been an upheaval of the sea-bottom before the cliff here alluded to was shaped out4 ,we may also conclude that so great an amount of denudation could scarcely take place1 in such incoherent materials1 without many of the fossils of the inferior beds becoming mixed up with the overlying crag1 so that considerable difficulty must be occasionally experienced by the palaeontologist in deciding which species belong severally to each group4 ,the red crag being formed in a shallower sea1 often resembles in structure a shifting sand bank1 its layers being inclined diagonally1 and the planes of stratification being sometimes directed in the same quarry to the four cardinal points of the compass1 as at ,butley4 ,that in this and many other localities1 such a structure is not deceptive or due to any subsequent concretionary re-arrangement of particles1 or to mere lines of colour1 is proved by each bed being made up of flat pieces of shell which lie parallel to the planes of the smaller strata4 ,some fossils1 which are very abundant in the red crag1 have never been found in the white or coralline division2 as1 for example1 the ,fusus contrarius 7fig4 #add471 and several species of ,buccinum 7or ,nassa7 and ,murex 7see figs4 #ade1 #adf471 which two genera seem wanting in the lower crag4 #d ,illustrations3 ,fossils characteristic of the ,red ,crag4 ,fig4 #add4 ,fusus contrarius4 ,fig4 #ade4 ,murex alveolatus4 ,fig4 #adf4 ,nassa granulata4 ,fig4 #adg4 ,cypraea coccinelloides4 ,fig4 #add4 half nat4 size2 the others nat4 size4 ,among the bones and teeth of fishes are those of large sharks 7,carcharias71 and a gigantic skate of the extinct genus ,myliobates1 and many other forms1 some common to our seas1 and many foreign to them4 ,the distinctness of the fossils of the coralline crag arises in part from higher antiquity1 and1 in some degree1 from a difference in the geographical conditions of the submarine bottom4 ,the prolific growth of corals1 echini1 and a prodigious variety of testacea1 implies a region of deeper and more tranquil water2 whereas1 the red crag may have formed afterwards on the same spot1 when the water was shallower4 ,in the mean time the climate may have become somewhat cooler1 and some of the zoophytes which flourished in the first period may have disappeared1 so that the fauna of the red crag acquired a character somewhat more nearly resembling that of our northern seas1 as is implied by the large development of certain sections of the genera ,fusus1 ,buccinum1 ,purpura1 and ,trochus1 proper to higher latitudes1 and which are wanting or feebly represented in the inferior crag4 ,some of the corals of the lower crag of ,suffolk belong to genera unknown in the living creation1 and of a very peculiar structure2 as1 for example1 that represented in the annexed fig4 7#adh471 which is one of several species having a globular form4 ,the great number and variety of these zoophytes probably indicate an equable climate1 free from intense cold in winter4 ,on the other hand1 that the heat was never excessive is confirmed by the prevalence of northern forms among the testacea1 such as the ,glycimeris1 ,cyprina1 and ,astarte4 ,of the genus last mentioned 7see fig4 #adi47 there are about fourteen species1 many of them being rich in individuals2 and there is an absence of genera peculiar to hot climates1 such as ,conus1 ,oliva1 ,mitra1 ,fasciolaria1 ,crassatella1 and others4 ,the cowries 7,cypraea1 fig4 #adg471 also1 are small1 and belong to a section 7,trivia7 now inhabiting the colder regions4 ,a large volute1 called ,voluta ,lamberti 7fig4 #aej471 may seem an exception2 but it differs in form from the volutes of the torrid zone1 and may1 like the living ,voluta ,magellanica1 have been fitted for an extra-tropical climate4 ,illustration3 ,fig4 #adh4 ,fascicularia aurantium1 ,milne ,edwards4 ,family1 ,tubuliporidae1 of same author4 ,coral of extinct genus1 from the inferior or coralline crag1 ,suffolk4 a4 exterior4 b4 vertical section of interior4 c4 portion of exterior magnified4 d4 portion of interior magnified1 showing that it is made up of long1 thin1 straight tubes1 united in conical bundles4 ,illustration3 ,fig4 #adi4 ,astarte 7,crassina1 ,lam472 species common to upper and lower crag4 ,astarte ,omalii1 ,lajonkaire2 ,syn4 ,a4 bipartita1 ,sow4 ,min4 ,con4 ,t4 #eba4 f4 #c42 a very variable species most characteristic of the coralline crag1 ,suffolk4 ,illustration3 ,fig4 #aej4 ,voluta ,lamberti1 young individ4 ,the occurrence of a species of ,lingula at ,sutton is worthy of remark1 as these ,brachiopoda seem now confined to more equatorial latitudes1 and the same may be said still more decidedly of a species of ,pyrula1 allied to ,p4 reticulata4 ,whether1 therefore1 we may incline to the belief that the mean annual temperature was higher or lower than now1 we may at least infer that the climate and geographical conditions were by no means the same at the period of the ,suffolk crag as those now prevailing in the same region4 ,of the echinoderms of the coralline crag about eleven species are known1 but some of these are in too fragmentary a condition to admit of exact comparison4 ,of six which are the most perfect1 ,prof4 ,e4 ,forbes has been able to identify three with recent species3 one of which1 of the genus ,echinus1 is ,british2 a second1 ,echinocyamus1 ,british and ,mediterranean2 and a third1 ,echinus monilis1 a ,mediterranean species1 also found fossil in the faluns of ,touraine4 ,one of the most interesting conclusions deduced from a careful comparison of the shells of these ,british ,older ,pliocene strata and those now inhabiting our seas1 has been pointed out by ,prof4 ,e4 ,forbes4 ,it appears that1 during the glacial period1 a period intermediate1 as we have seen1 between that of the crag and our own times1 many shells1 previously established in the temperate zone1 retreated southwards to avoid an uncongenial climate4 ,the ,professor has given a list of fifty shells which inhabited the ,british seas while the coralline and red crag were forming1 and which are wanting in the ,pleistocene or glacial deposits4 ,they must1 therefore1 after their migration to the south1 have made their way northwards again4 ,in corroboration of these views1 it is stated that all these fifty species occur fossil in the ,newer ,pliocene strata of ,sicily1 ,southern ,italy1 and the ,grecian ,archipelago1 where they may have enjoyed1 during the era of floating icebergs1 a climate resembling that now prevailing in higher ,european latitudes4#aff-;,a ,in the red crag at ,felixstow1 in ,suffolk1 ,professor ,henslow has found the ear-bones of no less than four species of cetacea1 which1 according to ,mr4 ,owen1 are the remains of true whales of the family ,balaenidae4 ,mr4 ,wood is of opinion that these cetacea may be of the age of the red crag1 or if not that they may be derived from the destruction of beds of coralline crag4 ,i agree with him that the supposition of their having been washed out of the ,london clay1 in which no ,balaenidae have yet been met with1 is improbable4 ,strata containing fossil shells1 like those of the ,suffolk crag1 above described1 have been found at ,antwerp1 and on the banks of the ,scheldt below that city4 ,in #ahdj ,i observed a small patch of them near ,valognes1 in ,normandy2 and there is also a deposit containing similar fossils at ,st4 ,george ,bohon1 and several places a few leagues to the ,s4 of ,carentan1 in ,normandy2 but they have never been traced farther southwards4 ,subapennine strata4--,the ,apennines1 it is well known1 are composed chiefly of secondary rocks1 forming a chain which branches off from the ,ligurian ,alps and passes down the middle of the ,italian peninsula4 ,at the foot of these mountains1 on the side both of the ,adriatic and the ,mediterranean1 are found a series of tertiary strata1 which form1 for the most part1 a line of low hills occupying the space between the older chain and the sea4 ,brocchi1 as we have seen 7p4 #aje471 was the first ,italian geologist who described this newer group in detail1 giving it the name of the ,subapennines2 and he classed all the tertiary strata of ,italy1 from ,piedmont to ,calabria1 as parts of the same system4 ,certain mineral characters1 he observed1 were common to the whole2 for the strata consist generally of light brown or blue marl1 covered by yellow calcareous sand and gravel4 ,there are also1 he added1 some species of fossil shells which are found in these deposits throughout the whole of ,italy4 ,we have now1 however1 satisfactory evidence that the ,subapennine beds of ,brocchi belong1 at least1 to three periods4 ,to the ,miocene we can refer a portion of the strata of ,piedmont1 those of the hill of the ,superga1 for example2 to the ,older ,pliocene1 part of the strata of northern ,italy1 of ,tuscany1 and of ,rome2 while the tufaceous formations of ,naples1 of ,ischia1 and the calcareous strata of ,otranto1 are referable to the ,newer ,pliocene1 and in great part to the ,post-,pliocene period4 ,that there is a considerable correspondence in the mineral composition of these different ,italian groups is undeniable2 but not that exact resemblance which should lead us to assume a precise identity of age1 unless the fossil remains agreed very closely4 ,it is now indispensable that a new scrutiny should be made in each particular district1 of the fossils derived from the upper and lower beds--especially such localities as ,asti and ,parma1 where the formation attains a great thickness2 and at ,sienna1 where the shells of the incumbent yellow sand are generally believed to approach much more nearly1 as a whole1 to the recent fauna of the ,mediterranean than those in the subjacent blue marl4 ,the greyish brown or blue marl of the ,subapennine formation is very aluminous1 and usually contains much calcareous matter and scales of mica4 ,near ,parma it attains a thickness of #bjjj feet1 and is charged throughout with marine shells1 some of which lived in deep1 others in shallow water1 while a few belong to freshwater genera1 and must have been washed in by rivers4 ,among these last ,i have seen the common ,limnea palustris in the blue marl1 filled with small marine shells4 ,the wood and leaves1 which occasionally form beds of lignite in the same deposit1 may have been carried into the sea by similar causes4 ,the shells1 in general1 are soft when first taken from the marl1 but they become hard when dried4 ,the superficial enamel is often well preserved1 and many shells retain their pearly lustre1 part of their external colour1 and even the ligament which unites the valves4 ,no shells are more usually perfect than the microscopic foraminifera1 which abound near ,sienna1 where more than a thousand full-grown individuals may be sometimes poured out of the interior of a single univalve of moderate dimensions4 ,the other member of the ,subapennine group1 the yellow sand and conglomerate1 constitutes1 in most places1 a border formation near the junction of the tertiary and secondary rocks4 ,in some cases1 as near the town of ,sienna1 we see sand and calcareous gravel resting immediately on the ,apennine limestone1 without the intervention of any blue marl4 ,alternations are there seen of beds containing fluviatile shells1 with others filled exclusively with marine species2 and ,i observed oysters attached to many limestone pebbles4 ,this appears to have been a point where a river1 flowing from the ,apennines1 entered the sea when the tertiary strata were formed4 ,the sand passes in some districts into a calcareous sandstone1 as at ,san ,vignone4 ,its general superposition to the marl1 even in parts of ,italy and ,sicily where the date of its origin is very distinct1 may be explained if we consider that it may represent the deltas of rivers and torrents1 which gained upon the bed of the sea where blue marl had previously been deposited4 ,the latter1 being composed of the finer and more transportable mud1 would be conveyed to a distance1 and first occupy the bottom1 over which sand and pebbles would afterwards be spread1 in proportion as rivers pushed their deltas farther outwards4 ,in some large tracts of yellow sand it is impossible to detect a single fossil1 while in other places they occur in profusion4 ,occasionally the shells are silicified1 as at ,san ,vitale1 near ,parma1 from whence ,i saw two individuals of recent species1 one freshwater and the other marine 7,limnea palustris1 and ,cytherea concentrica1 ,lam471 both perfectly converted into flint4 ,rome4--,the seven hills of ,rome are composed partly of marine tertiary strata1 those of ,monte ,mario1 for example1 of the ,older ,pliocene period1 and partly of superimposed volcanic tuff1 on the top of which are usually cappings of a fluviatile and lacustrine deposit4 ,thus1 on ,mount ,aventine1 the ,vatican1 and the ,capitol1 we find beds of calcareous tufa with incrusted reeds1 and recent terrestrial shells1 at the height of about #bjj feet above the alluvial plain of the ,tiber4 ,the tusk of the mammoth has been procured from this formation1 but the shells appear to be all of living species1 and must have been embedded when the summit of the ,capitol was a marsh1 and constituted one of the lowest hollows of the country as it then existed4 ,it is not without interest that we thus discover the extremely recent date of a geological event which preceded an historical era so remote as the building of ,rome4 ,,miocene ,,formations4 ,faluns of ,touraine4--,the ,miocene strata1 corresponding with those named by many geologists ,middle ,tertiary1 will next claim our attention4 ,near the towns of ,dinan and ,rennes1 in ,brittany1 and again in the provinces bordering the ,loire1 a tertiary formation1 containing another assemblage of fossils1 is met with1 to which the name of ,faluns has been long given by the ,french agriculturists1 who spread the shelly sand and marl over the land1 in the same manner as the crag was formerly much used in ,suffolk4 ,isolated masses of these faluns occur from near the mouth of the ,loire1 near ,nantes1 as far as a district south of ,tours4 ,they are also found at ,pontlevoy1 on the ,cher1 about #gj miles above the junction of that river with the ,loire1 and #cj miles ,s4,e4 of ,tours4 ,i have visited all the localities above mentioned1 and found the beds to consist principally of sand and marl1 in which are shells and corals1 some entire1 some rolled1 and others in minute fragments4 ,in certain districts1 as at ,doue1 in the department of ,maine and ,loire1 #aj miles ,s4,w4 of ,saumur1 they form a soft building-stone1 chiefly composed of an aggregate of broken shells1 corals1 and echinoderms1 united by a calcareous cement2 the whole mass being very like the coralline crag near ,aldborough and ,sudbourn in ,suffolk4 ,the scattered patches of faluns are of slight thickness1 rarely exceeding #ej feet2 and between the district called ,sologne and the sea they repose on a great variety of older rocks2 being seen to rest successively upon gneiss1 clay-slate1 and various secondary formations1 including the chalk2 and1 lastly1 upon the upper freshwater limestone of the ,parisian tertiary series1 which1 as before mentioned 7p4 #ajf471 stretches continuously from the basin of the ,seine to that of the ,loire4 ,at some points1 as at ,louans1 south of ,tours1 the shells are stained of a ferruginous colour1 not unlike that of the red crag of ,suffolk4 ,the species are1 for the most part1 marine1 but a few of them belong to land and fluviatile genera4 ,among the former1 ,helix turonensis 7fig4 #de4 p4 #cj47 is the most abundant4 ,remains of terrestrial quadrupeds are here and there intermixed1 belonging to the genera ,deinotherium1 ,mastodon1 ,rhinoceros1 ,hippopotamus1 ,chaeropotamus1 ,dichobune1 ,deer1 and others1 and these are accompanied by cetacea1 such as the ,lamantine1 ,morse1 ,sea-calf1 and ,dolphin1 all of extinct species4 ,professor ,e4 ,forbes1 after studying the fossil testacea which ,i obtained from these beds2 informs me that he has no doubt they were formed partly on the shore itself at the level of low water1 and partly at very moderate depths1 not exceeding #aj fathoms below that level4 ,the molluscous fauna of the faluns is on the whole much more littoral than that of the red and coralline crag of ,suffolk1 and implies a shallower sea4 ,it is1 moreover1 contrasted with the ,suffolk crag by the indications it affords of an extra-,european climate4 ,thus it contains seven species of ,cypraea1 some larger than any existing cowry of the ,mediterranean1 several species of ,oliva1 ,ancillaria1 ,mitra1 ,terebra1 ,pyrula1 ,fasciolaria1 and ,conus4 ,of the cones there are no less than eight species1 some very large1 whereas the only ,european cone is of diminutive size4 ,the genus ,nerita1 and many others1 are also represented by individuals of a type now characteristic of equatorial seas1 and wholly unlike any ,mediterranean forms4 ,these proofs of a more elevated temperature seem to imply the higher antiquity of the faluns as compared with the ,suffolk crag1 and are in perfect accordance with the fact of the smaller proportion of testacea of recent species found in the faluns4 ,out of #bij species of shells1 collected by myself1 in #ahdj1 at ,pontlevoy1 ,louans1 ,bossee1 and other villages #bj miles south of ,tours2 and at ,savigne1 about #ae miles north-west of that place2 #gb only could be identified with recent species1 which is in the proportion of #be per cent4 ,a large number of the #bij species are common to all the localities1 those peculiar to each not being more numerous than we might expect to find in different bays of the same sea4 ,the total number of mollusca from the faluns1 in my possession1 is #cjb1 of which #de only were found by ,mr4 ,wood to be common to the ,suffolk crag4 ,the number of corals obtained by me at ,doue1 and other localities before adverted to1 amounts to #dc1 as determined by ,mr4 ,lonsdale1 of which #g agree specifically with those of the ,suffolk crag4 ,only one has1 as yet1 been identified with a living species4 ,but it is difficult1 if not impossible1 to institute at present a satisfactory comparison between fossil and recent ,polyparia1 from the deficiency of our knowledge of the living species4 ,some of the genera occurring fossil in ,touraine1 as the ,astrea1 ,lunulites1 and ,dendrophyllia1 have not been found in ,european seas north of the ,mediterranean2 nevertheless the ,polyparia of the faluns do not seem to indicate on the whole so warm a climate as would be inferred from the shells4 ,it was stated that1 on comparing about #cjj species of ,touraine shells with about #dej from the ,suffolk crag1 #de only were found to be common to both1 which is in the proportion of only #ae per cent4 ,the same small amount of agreement is found in the corals also4 ,i formerly endeavoured to reconcile this marked difference in species with the supposed co-existence of the two faunas1 by imagining them to have severally belonged to distinct zoological provinces or two seas1 the one opening to the north1 and the other to the south1 with a barrier of land between them1 like the ,isthmus of ,suez1 separating the ,red ,sea and the ,mediterranean4 ,but ,i now abandon that idea for several reasons2 among others1 because ,i succeeded in #ahda in tracing the ,crag fauna southwards in ,normandy to within #gj miles of the ,falunian type1 near ,dinan1 yet found that both assemblages of fossils retained their distinctive characters1 showing no signs of any blending of species or transition of climate4 ,on a comparison of #bhj ,mediterranean shells with #fjj ,british species1 made for me by an experienced conchologist in #ahda1 #afj were found to be common to both collections1 which is in the proportion of #eg per cent41 a fourfold greater specific resemblance than between the seas of the crag and the faluns1 notwithstanding the greater geographical distance between ,england and the ,mediterranean than between ,suffolk and the ,loire4 ,the principal grounds1 however1 for referring the ,english crag to the older ,pliocene and the ,french faluns to the ,miocene epochs1 consist in the predominance of fossil shells in the ,british strata identifiable with species1 not only still living1 but which are now inhabitants of neighbouring seas1 while the accompanying extinct species are of genera such as characterize ,europe4 ,in the faluns1 on the contrary1 the recent species are in a decided minority1 and many of them1 like the associated extinct testacea1 are much less ,european in character1 and point to the prevalence of a warmer climate1--in other words1 to a state of things receding farther from the present condition of ,europe1 geographically and climatologically1 and doubtless1 therefore1 receding farther in time4 ,bordeaux4--,a great extent of country between the ,pyrenees and the ,gironde is overspread by tertiary deposits1 which have been more particularly studied in the environs of ,bordeaux and ,dax1 from whence about #gjj species of shells have been obtained4 ,a large proportion of these shells belong to the same zoological type as those of ,touraine2 but many are peculiar1 and the whole may possibly constitute a somewhat older division of the ,miocene period than the faluns of the ,loire4 ,we must wait1 however1 for farther investigations1 in order to decide this question with accuracy4 ,piedmont4--,many of the shells peculiar to the hill of the ,superga1 near ,turin1 agree with those found at ,bordeaux and ,dax2 but the proportion of recent species is much less4 ,the strata of the ,superga consist of a bright green sand and marl1 and a conglomerate with pebbles1 chiefly of green serpentine1 and are inclined at an angle of more than #gj deg44 ,this formation1 which attains a great thickness in the valley of the ,bormida1 is probably one of the oldest ,miocene groups hitherto discovered4 ,molasse of ,switzerland4--,if we cross the ,alps1 and pass from ,piedmont to ,savoy1 we find there1 at the northern base of the great chain1 and throughout the lower country of ,switzerland1 a soft green sandstone much resembling some of the beds of the basin of the ,bormida1 above described1 and associated in a similar manner with marls and conglomerate4 ,this formation is called in ,switzerland molasse1 said to be derived from mol1 soft because the stone is easily cut in the quarry4 ,it is of vast thickness1 and probably divisible into several formations4 ,how large a portion of these belong to the ,miocene period cannot yet be determined1 as fossil shells are often entirely wanting4 ,in some places a decided agreement of the fossil fishes of the molasse and faluns has been observed4 ,among those common to both1 ,m4 ,agassiz pointed out to me ,lamna contortidens1 ,myliobates ,studeri1 ,spherodus cinctus1 ,notidanus primigenius1 and others4 ,lisbon4--,marine tertiary strata near ,lisbon contain shells which agree very closely with those of ,bordeaux1 and are therefore referred to the ,miocene era4 ,thus1 out of #aab species collected by ,mr4 ,smith of ,jordanhill1 between #fj and #gj were found to be common to the strata of ,bordeaux and ,dax1 the recent species being in the proportion of #ba per cent4 ,older ,pliocene and ,miocene formations in the ,united ,states4--,between the ,alleghany mountains1 formed of older rocks1 and the ,atlantic1 there intervenes1 in the ,united ,states1 a low region occupied principally by beds of marl1 clay1 and sand1 consisting of the cretaceous and tertiary formations1 and chiefly of the latter4 ,the general elevation of this plain bordering the ,atlantic does not exceed #ajj feet1 although it is sometimes several hundred feet high4 ,its width in the middle and southern states is very commonly from #ajj to #aej miles4 ,it consists1 in the ,south1 as in ,georgia1 ,alabama1 and ,south ,carolina1 almost exclusively of ,eocene deposits2 but in ,north ,carolina1 ,maryland1 ,virginia1 and ,delaware1 more modern strata predominate1 which ,i have assimilated in age to the ,english crag and ,faluns of ,touraine4#agb-;,a ,if1 chronologically speaking1 they can be truly said to be the representatives of these two ,european formations1 they may range in age from the ,older ,pliocene to the ,miocene epoch1 according to the classification of ,european strata adopted in this chapter4 ,the proportion of fossil shells agreeing with recent1 out of #adg species collected by me1 amounted to about #ag per cent41 or one-sixth of the whole2 but as the fossils so assimilated were almost always the same as species now living in the neighbouring ,atlantic1 the number may hereafter be augmented1 when the recent fauna of that ocean is better known4 ,in different localities1 also1 the proportion of recent species varied considerably4 ,illustration3 ,fig4 #aea4 ,fulgur canaliculatus4 ,maryland4 ,illustration3 ,fig4 #aeb4 ,fusus quadricostatus1 ,say4 ,maryland4 ,on the banks of the ,james ,river1 in ,virginia1 about #bj miles below ,richmond1 in a cliff about #cj feet high1 ,i observed yellow and white sands overlying an ,eocene marl1 just as the yellow sands of the crag lie on the blue ,london clay in ,suffolk and ,essex in ,england4 ,in the ,virginian sands1 we find a profusion of an ,astarte 7,a4 undulata1 ,conrad71 which resembles closely1 and may possibly be a variety of1 one of the commonest fossils of the ,suffolk crag 7,a4 bipartita72 the other shells also1 of the genera ,natica1 ,fissurella1 ,artemis1 ,lucina1 ,chama1 ,pectunculus1 and ,pecten1 are analogous to shells both of the ,english crag and ,french faluns1 although the species are almost all distinct4 ,out of #adg of these ,american fossils ,i could only find #ac species common to ,europe1 and these occur partly in the ,suffolk crag1 and partly in the faluns of ,touraine2 but it is an important characteristic of the ,american group1 that it not only contains many peculiar extinct forms1 such as ,fusus quadricostatus1 ,say 7see fig4 #aeb471 and ,venus tridacnoides1 abundant in these same formations1 but also some shells which1 like ,fulgur carica of ,say1 and ,f4 canaliculatus 7see fig4 #aea471 ,calyptraea costata1 ,venus mercenaria1 ,lam41 ,modiola glandula1 ,totten1 and ,pecten magellanicus1 ,lam41 are recent species1 yet of forms now confined to the western side of the ,atlantic1 a fact implying that the beginning of the present geographical distribution of mollusca dates back to a period as remote as that of the ,miocene strata4 ,of ten species of zoophytes which ,i procured on the banks of the ,james ,river1 two were identical with species of the ,faluns of ,touraine4 ,with respect to climate1 ,mr4 ,lonsdale regards these corals as indicating a temperature exceeding that of the ,mediterranean1 and the shells would lead to similar conclusions4 ,those occurring on the ,james ,river are in the #cgth degree of ,n4 latitude1 while the ,french faluns are in the #dgth2 yet the forms of the ,american fossils would scarcely imply so warm a climate as must have prevailed in ,france1 when the ,miocene strata of ,touraine originated4 ,among the remains of fish in these ,post-,eocene strata of the ,united ,states are several large teeth of the shark family1 not distinguishable specifically from fossils of the faluns of ,touraine1 and the ,maltese tertiaries4 ,india4--,the freshwater deposits of the ,sub-,himalayan or ,sewalik ,hills1 described by ,dr4 ,falconer and ,captain ,cautley1 may perhaps be regarded as ,miocene4 ,like the faluns of ,touraine1 they contain the ,deinotherium and ,mastodon4 ,whether any of the associated freshwater and land shells are of recent species is not yet determined4 ,the occurrence in them of a fossil giraffe and hippopotamus1 genera now only living in ,africa1 as well as of a camel1 implies a geographical state of things very different from that now established in the same parts of ,india4 ,the huge ,sivatherium of the same era appears to have been a ruminating quadruped bigger than the rhinoceros1 and provided with a large upper lip1 or probably a short proboscis1 and having two pair of horns1 resembling those of antelopes4 ,several species of monkey belonged to the same fauna2 and among the reptiles1 several crocodiles1 larger than any now living1 and an enormous tortoise1 ,testudo ,atlas1 the curved shell of which measured #bj feet across4 ,,footnotes3 #afb-;,a ,see paper by ,e4 ,charlesworth1 ,esq42 ,london and ,ed4 ,phil4 ,mag4 ,no4 xxxviii4 p4 #ha41 ,aug4 #ahce4 #afb-;,b ,see ,monograph on the ,crag ,mollusca4 ,searles ,wood1 ,paleont4 ,soc4 #ahdh4 #afc-;,a ,in regarding the ,suffolk crag1 both red and coralline1 as older ,pliocene instead of ,miocene1 ,i am only returning to the classification adopted by me in the ,principles and ,elements of ,geology up to the year #ahch4 #aff-;,a ,e4 ,forbes1 ,mem4 ,geol4 ,survey1 ,gt4 ,brit41 vol4 i4 #chf4 #agb-;,a ,proceedings of the ,geol4 ,soc4 vol4 iv4 part #c4 #ahde1 p4 #edg4 ,,chapter ,,xv4 ,,upper ,,eocene ,,formations4 ,eocene areas in ,england and ,france--,tabular view of ,french ,eocene strata--,upper ,eocene group of the ,paris basin--,same beds in ,belgium and at ,berlin--,mayence tertiary strata--,freshwater upper ,eocene of ,central ,france--,series of geographical changes since the land emerged in ,auvergne--,mineral character an uncertain test of age--,marls containing ,cypris--,oolite of ,eocene period--,indusial limestone and its origin--,fossil mammalia of the upper ,eocene strata in ,auvergne--,freshwater strata of the ,cantal1 calcareous and siliceous--,its resemblance to chalk--,proofs of gradual deposition of strata4 ,illustration3 ,fig4 #aec4 ,map of the principal tertiary basins of the ,eocene period4 ,n4 ,b4 ,the space left blank is occupied by secondary formations from the ,devonian or old red sandstone to the chalk inclusive4 ,the tertiary strata described in the preceding chapters are all of them characterized by fossil shells1 of which a considerable proportion are specifically identical with the living mollusca2 and the greater the number1 the more nearly does the entire fauna approach in species and genera to that now inhabiting the adjoining seas4 ,but in the ,eocene formations next to be considered1 the proportion of recent species is very small1 and sometimes scarcely appreciable1 and those agreeing with the fossil testacea often belong to remote parts of the globe1 and to various zoological provinces4 ,this difference in conchological character implies a considerable interval of time between the ,eocene and ,miocene periods1 during which the whole fauna and flora underwent other changes as great1 and often greater1 than those exhibited by the mollusca4 ,in the accompanying map1 the position of several ,eocene areas is pointed out1 such as the basin of the ,thames1 part of ,hampshire1 part of the ,netherlands1 and the country round ,paris4 ,the deposits1 however1 occupying these spaces comprise a great succession of marine and freshwater formations1 which1 although they may all be termed ,eocene1 as being newer than the chalk1 and older than the faluns1 are nevertheless divisible into separate groups1 of high geological importance4 ,the newest of these1 like the ,faluns of the ,loire1 have no true representatives1 or exact chronological equivalents1 in the ,british ,isles4 ,their place in the series will best be understood by referring to the order of superposition of the successive deposits found in the neighbourhood of ,paris4 ,the area which has been called the ,paris basin is about #ahj miles in its greatest length from north-east to south-west1 and about #ij miles from east to west4 ,this space may be described as a depression in the chalk1 which has been filled up by alternating groups of marine and freshwater strata4 ,,mm4 ,cuvier and ,brongniart attempted1 in #ahaj1 to distinguish five different formations1 comprising three freshwater and two marine1 which alternated with each other4 ,it was imagined that the waters of the ocean had been by turns admitted and excluded from the same region2 but the subsequent investigations of several geologists1 especially of ,m4 ,constant ,prevost1#age-;,a have led to great modifications in these theoretical views2 and now that the true order of succession is better understood1 it appears that several of the deposits1 which were supposed to have originated one after the other1 were1 in fact1 in progress at the same time by the joint action of the sea and rivers4 ,the whole series of strata may be divided into three groups1 as expressed in the following table3-- a4 ,upper freshwater limestone1 marls1 and siliceous #a4 ,upper ,eocene millstone4 b4 ,upper marine sands1 or ,fontainebleau sandstone and sand4 a4 ,lower freshwater limestone and marl1 or gypseous series4 b4 ,sandstone and sands with marine shells 7,sables #b4 ,middle ,eocene moyens1 or gres de ,beauchamp74 c4 ,calcaire grossier1 limestone with marine shells4 d4 ,calcaire siliceux1 hard siliceous freshwater limestone1 for the most part contemporaneous with c4 a4 ,lower sands with marine shelly beds 7,sables #c4 ,lower ,eocene inferieurs et lits coquilliers74 b4 ,lower sands1 with lignite and plastic clay 7,sables inferieurs et argiles plastiques74 ,postponing to the next chapter the consideration of the ,middle and ,lower ,eocene groups1 ,i shall now speak of the ,upper ,eocene of ,paris1 and its foreign equivalents4 ,the upper freshwater marls and limestone 7#a4 a7 seem to have been formed in a great number of marshes and shallow lakes1 such as frequently overspread the newest parts of great deltas4 ,it appears that many layers of marl1 tufaceous limestone1 and travertin1 with beds of flint1 continuous or in nodules1 accumulated in these lakes4 ,charae1 aquatic plants1 already alluded to 7see p4 #cb47 left their stems and seed-vessels imbedded both in the marl and flint1 together with freshwater and land shells4 ,some of the siliceous rocks of this formation are used extensively for millstones4 ,the flat summits or platforms of the hills round ,paris1 large areas in the forest of ,fontainebleau1 and the ,plateau de la ,beauce1 between the ,seine and the ,loire1 are chiefly composed of these upper freshwater strata4 ,the upper marine sands 7#a4 b71 consist chiefly of micaceous and quartzose sands1 #hj feet thick4 ,as they succeed throughout an extensive area deposit of a purely freshwater origin 7#b a471 they appear to mark a subsidence of the subjacent soil1 whether it had formed the bottom of an estuary or a lake4 ,the sea1 which afterwards took possession of the same space1 was inhabited by testacea1 almost all of them differing from those found in the lower formations 7#b4 b and #b4 c7 and equally or still more distinct from the ,miocene ,faluns of subsequent date4 ,one of these upper ,eocene strata in the neighbourhood of ,paris has been called the oyster bed1 couche a ,ostrea cyathula1 ,lamk41 which is spread over a remarkably wide area4 ,from the manner in which the oysters lie1 it is inferred that they did not grow on the spot1 but that some current swept them away from a bed of oysters formed in some other part of the bay4 ,the strata of sand which immediately repose on the oyster-bed are quite destitute of organic remains2 and nothing is more common in the ,paris basin1 and in other formations1 than alternations of shelly beds with others entirely devoid of them4 ,the temporary extinction and renewal of animal life at successive periods have been rashly inferred from such phenomena1 which may nevertheless be explained1 as ,m4 ,prevost justly remarks1 without appealing to any such extraordinary revolutions in the state of the animate creation4 ,a current one day scoops out a channel in a bed of shelly sand and mud1 and the next day1 by a slight alteration of its course1 ceases to prey upon the same bank4 ,it may then become charged with sand unmixed with shells1 derived from some dune1 or brought down by a river4 ,in the course of ages an indefinite number of transitions from shelly strata to those without shells may thus be caused4 ,besides these oysters1 ,m4 ,deshayes has described #bi species of shells1 in his work 7,coquilles fossiles de ,paris71 as belonging to this formation1 all save one regarded by him as differing from fossils of the calcaire grossier4 ,since that time the railway cuttings near ,etampes have enabled ,m4 ,hebert to raise the number to #ij4 ,i have myself collected fossils in that district1 where the shells are very entire1 and detachable from the yellow sandy matrix4 ,m4 ,hebert first pointed out that most of them agree specifically with those of ,kleyn ,spauwen1 ,boom1 and other localities of ,limburg in ,flanders1 where they have been studied by ,,mm4 ,nyst and ,de ,koninck4#agf-;,a ,the position in ,belgium of this formation above the older ,eocene group is well seen in the small hill of ,pellenberg1 rising abruptly from the great plain1 half a mile south-east of the city of ,louvain1 where ,i examined it in company with ,m4 ,nyst in #ahej4 ,at the top of the hill1 a thin bed of dark greyish green tile-clay is seen #a-a_/b foot thick1 with casts of ,nucula ,deshaysiana4 ,this clay rests on #ab feet of yellow sand1 separated1 by a band of flint and quartz pebbles1 from a mass of subjacent white sand #ae feet thick1 in which casts of the ,kleyn ,spauwen fossils have been met with4 ,under this is a bed of yellow sand #ab feet thick1 and1 at a lower level1 the railway cuttings have passed through calcareous sands like those of ,brussels1 in which the ,nautilus ,burtini1 and various shells common to the older ,eocene strata of the neighbourhood of ,london1 have been obtained4 ,every new fact which throws light on the true paleontological relations of the strata now under consideration1 7the ,upper ,marine or ,fontainebleau beds of the ,paris basin1 #a4 b1 p4 #age471 deserves more particular attention1 because geologists of high authority differ in opinion as to whether they should be classed as ,eocene or ,miocene4 ,professor ,beyrich has lately described a formation of the same age1 occurring within #g miles of the gates of ,berlin1 near the village of ,hermsdorf1 where1 in the midst of the sands of which that country chiefly consists1 a mass of tile-clay1 more than #dj feet thick1 and of a dark blueish grey colour1 is found1 full of shells1 among which the genera ,fusus and ,pleurotoma predominate1 and among the bivalves1 ,nucula ,deshaysiana1 ,nyst1 an extremely common shell in the ,belgian beds above-mentioned4 ,m4 ,beyrich has identified eighteen out of forty-five species of the ,hermsdorf fossils with the ,belgian species2 and ,i believe that a much larger proportion agree with the ,upper ,eocene of ,belgium1 ,france1 and the ,rhine4 ,on the other hand1 eight of the forty-five species are supposed by him to agree with ,english ,eocene shells4 ,messrs4 ,morris1 ,edwards1 and ,s4 ,wood have compared a small collection1 which ,i obtained of these ,berlin shells1 with the ,eocene fossils of their museums1 and confirmed the result of ,m4 ,beyrich1 the species common to the ,english fossils belonging not simply to the uppermost of our marine beds1 or those of ,barton1 but some of them to lower parts of the series1 such as ,bracklesham and ,highgate4 ,on the other hand1 while these testacea1 like those of ,kleyn ,spauwen and ,etampes1 present many analogies to the ,middle and ,lower ,eocene group1 they differ widely from the ,falun shells1--a fact the more important in reference to ,etampes1 as that locality approaches within #gj miles of ,pontlevoy1 near ,blois1 and within #ajj miles of ,savigne1 near ,tours1 where ,falun shells are found4 ,it is evident that the discordance of species cannot be attributed to distance or geographical causes1 but must be referred to time1 or the different epoch at which the upper marine beds of the ,paris basin and the ,faluns of the ,loire originated4 ,mayence4--,the true chronological relation of many tertiary strata on the banks of the ,rhine has always presented a problem of considerable difficulty4 ,they occupy a tract from #e to #ab miles in breadth1 extending along the left bank of the ,rhine from ,mayence to the neighbourhood of ,manheim1 and are again found to the east1 north1 and south-west of ,frankfort4 ,in some places they have the appearance of a freshwater formation2 but in others1 as at ,alzey1 the shells are for the most part marine4 ,cerithia are in great profusion1 which indicates that the sea where the deposit was formed was fed by rivers2 and the great quantity of fossil land shells1 chiefly of the genus ,helix1 confirm the same opinion4 ,the variety in the species of shells is small1 while the individuals are exceedingly numerous2 a fact which accords perfectly with the idea that the formation may have originated in a gulf or sea which1 like the ,baltic1 was brackish in some parts1 and almost fresh in others4 ,a species of ,paludina 7fig4 #aed471 very nearly resembling the recent ,littorina ulva1 is found throughout this basin4 ,these shells are like grains of rice in size1 and are often in such quantity as to form entire beds of marl and limestone4 ,they are as thick as grains of sand1 in stratified masses from #ae to #cj feet in thickness4 ,illustration3 ,fig4 #aed4 ,paludina4 ,mayence4 ,that these ,rhenish tertiary formations agree more nearly with the ,upper ,eocene deposits above enumerated1 than with any others1 ,i have no doubt1 since ,i had the advantage of comparing 7,august1 #ahej71 with the assistance of ,m4 ,de ,koninck of ,liege1 the fossils from ,kleyn ,spauwen1 ,boom1 and other ,limburg localities1 with those from ,mayence1 ,alzey1 ,weinheim1 and other ,rhenish strata4 ,among the common ,belgian and ,rhenish shells which are identical1 ,i may mention ,cassidaria depressa1 ,tritonium flandricum ,de ,koninck1 ,cerithium tricinctum ,nyst1 ,tornatella simulata1 ,rostellaria ,sowerbyi1 ,nucula ,deshaysiana1 ,corbula pisum1 and ,pectunculus terebratularis4 ,from these ,upper ,eocene deposits of the ,rhine ,m4 ,h4 von ,meyer has obtained a great number of characteristic fossil mammalia1 such as ,palaeomaeryx medius1 ,hyotherium ,meissneri1 ,tapirus ,helveticus1 ,anthracotherium ,alsaticum1 and others4 ,the three first of these are species common to some of the lignite1 or brown coal beds in ,switzerland1 commonly classed with the molasse1 but of which the true age has not yet been distinctly made out4 ,the fossils of the sandy beds of ,eppelsheim1 comprising bones of the ,deinotherium1 ,mastodon1 and other quadrupeds1 are regarded by ,h4 von ,meyer as belonging to a mammiferous fauna quite distinct from that of the ,mayence basin1 and they are probably referable to the ,miocene period4 ,the upper freshwater strata 7#a4 a1 p4 #age471 of the neighbourhood of ,paris1 stretch southwards from the valley of the ,seine to that of the ,loire1 and in the last-mentioned region are seen to be older than the marine faluns1 so that the perforating shells of the ,miocene sea have sometimes bored the hard compact freshwater limestones2 and fragments of the ,upper ,eocene rocks are found at ,pontlevoy and elsewhere1 which have been rolled in the bed of the ,miocene sea4 ,illustration3 ,fig4 #aee4 ,simplified geological map south of ,paris4 ,central ,france4--,lacustrine strata belonging1 for the most part1 to the same ,upper ,eocene series1 are again met with in ,auvergne1 ,cantal1 and ,velay1 the sites of which may be seen in the annexed map4 ,they appear to be the monuments of ancient lakes1 which1 like some of those now existing in ,switzerland1 once occupied the depressions in a mountainous region1 and have been each fed by one or more rivers and torrents4 ,the country where they occur is almost entirely composed of granite and different varieties of granitic schist1 with here and there a few patches of secondary strata1 much dislocated1 and which have probably suffered great denudation4 ,there are also some vast piles of volcanic matter 7see the map71 the greater part of which is newer than the freshwater strata1 and is sometimes seen to rest upon them1 while a small part has evidently been of contemporaneous origin4 ,of these igneous rocks ,i shall treat more particularly in another part of this work4 ,before entering upon any details1 ,i may observe1 that the study of these regions possesses a peculiar interest1 very distinct in kind from that derivable from the investigation either of the ,parisian or ,english tertiary strata4 ,for we are presented in ,auvergne with the evidence of a series of events of astonishing magnitude and grandeur1 by which the original form and features of the country have been greatly changed1 yet never so far obliterated but that they may still1 in part at least1 be restored in imagination4 ,great lakes have disappeared1--lofty mountains have been formed1 by the reiterated emission of lava1 preceded and followed by showers of sand and scoriae1--deep valleys have been subsequently furrowed out through masses of lacustrine and volcanic origin1--at a still later date1 new cones have been thrown up in these valleys1--new lakes have been formed by the damming up of rivers1--and more than one creation of quadrupeds1 birds1 and plants1 ,eocene1 ,miocene1 and ,pliocene1 have followed in succession2 yet the region has preserved from first to last its geographical identity2 and we can still recall to our thoughts its external condition and physical structure before these wonderful vicissitudes began1 or while a part only of the whole had been completed4 ,there was first a period when the spacious lakes1 of which we still may trace the boundaries1 lay at the foot of mountains of moderate elevation1 unbroken by the bold peaks and precipices of ,mont ,dor1 and unadorned by the picturesque outline of the ,puy de ,dome1 or of the volcanic cones and craters now covering the granitic platform4 ,during this earlier scene of repose deltas were slowly formed2 beds of marl and sand1 several hundred feet thick1 deposited2 siliceous and calcareous rocks precipitated from the waters of mineral springs2 shells and insects imbedded1 together with the remains of the crocodile and tortoise1 the eggs and bones of water birds1 and the skeletons of quadrupeds1 some of them belonging to the same genera as those entombed in the ,eocene gypsum of ,paris4 ,to this tranquil condition of the surface succeeded the era of volcanic eruptions1 when the lakes were drained1 and when the fertility of the mountainous district was probably enhanced by the igneous matter ejected from below1 and poured down upon the more sterile granite4 ,during these eruptions1 which appear to have taken place after the disappearance of the ,eocene fauna1 and in the ,miocene epoch1 the mastodon1 rhinoceros1 elephant1 tapir1 hippopotamus1 together with the ox1 various kinds of deer1 the bear1 hyaena1 and many beasts of prey1 ranged the forest1 or pastured on the plain1 and were occasionally overtaken by a fall of burning cinders1 or buried in flows of mud1 such as accompany volcanic eruptions4 ,lastly1 these quadrupeds became extinct1 and gave place to ,pliocene mammalia1 and these1 in their turn1 to species now existing4 ,there are no signs1 during the whole time required for this series of events1 of the sea having intervened1 nor of any denudation which may not have been accomplished by currents in the different lakes1 or by rivers and floods accompanying repeated earthquakes1 during which the levels of the district have in some places been materially modified1 and perhaps the whole upraised relatively to the surrounding parts of ,france4 ,auvergne4--,the most northern of the freshwater groups is situated in the valley-plain of the ,allier1 which lies within the department of the ,puy de ,dome1 being the tract which went formerly by the name of the ,limagne d',auvergne4 ,it is inclosed by two parallel mountain ranges1--that of the ,forez1 which divides the waters of the ,loire and ,allier1 on the east2 and that of the ,monts ,domes1 which separates the ,allier from the ,sioule1 on the west4#aha-;,a ,the average breadth of this tract is about #bj miles2 and it is for the most part composed of nearly horizontal strata of sand1 sandstone1 calcareous marl1 clay1 and limestone1 none of which observe a fixed and invariable order of superposition4 ,the ancient borders of the lake1 wherein the freshwater strata were accumulated1 may generally be traced with precision1 the granite and other ancient rocks rising up boldly from the level country4 ,the actual junction1 however1 of the lacustrine and granitic beds is rarely seen1 as a small valley usually intervenes between them4 ,the freshwater strata may sometimes be seen to retain their horizontality within a very slight distance of the border-rocks1 while in some places they are inclined1 and in few instances vertical4 ,the principal divisions into which the lacustrine series may be separated are the following3--#ast1 ,sandstone1 grit1 and conglomerate1 including red marl and red sandstone4 #b;dly1 ,green and white foliated marls4 #c;dly1 ,limestone or travertin1 often oolitic4 #dthly1 ,gypseous marls4 #a4 a4 ,sandstone and conglomerate4--,strata of sand and gravel1 sometimes bound together into a solid rock1 are found in great abundance around the confines of the lacustrine basin1 containing1 in different places1 pebbles of all the ancient rocks of the adjoining elevated country2 namely1 granite1 gneiss1 mica-schist1 clay-slate1 porphyry1 and others4 ,but these strata do not form one continuous band around the margin of the basin1 being rather disposed like the independent deltas which grow at the mouths of torrents along the borders of existing lakes4 ,at ,chamalieres1 near ,clermont1 we have an example of one of these deltas1 or littoral deposits1 of local extent1 where the pebbly beds slope away from the granite1 as if they had formed a talus beneath the waters of the lake near the steep shore4 ,a section of about #ej feet in vertical height has been laid open by a torrent1 and the pebbles are seen to consist throughout of rounded and angular fragments of granite1 quartz1 primary slate1 and red sandstone2 but without any intermixture of those volcanic rocks which now abound in the neighbourhood1 and which could not have been there when the conglomerate was formed4 ,partial layers of lignite and pieces of wood are found in these beds4 ,at some localities on the margin of the basin quartzose grits are found2 and1 where these rest on granite1 they are sometimes formed of separate crystals of quartz1 mica1 and felspar1 derived from the disintegrated granite1 the crystals having been subsequently bound together by a siliceous cement4 ,in these cases the granite seems regenerated in a new and more solid form2 and so gradual a passage takes place between the rock of crystalline and that of mechanical origin1 that we can scarcely distinguish where one ends and the other begins4 ,in the hills called the ,puy de ,jussat and ,la ,roche1 we have the advantage of seeing a section continuously exposed for about #gjj feet in thickness4 ,at the bottom are foliated marls1 white and green1 about #djj feet thick2 and above1 resting on the marls1 are the quartzose grits1 cemented by calcareous matter1 which is sometimes so abundant as to form imbedded nodules4 ,these sometimes constitute spheroidal concretions #f feet in diameter1 and pass into beds of solid limestone1 resembling the ,italian travertins1 or the deposits of mineral springs4 ,this section is close to the confines of the basin2 so that the lake must here have been filled up near the shore with fine mud1 before the coarse superincumbent sand was introduced4 ,there are other cases where sand is seen below the marl4 #a4 b4 ,red marl and sandstone4--,but the most remarkable of the arenaceous groups is one of red sandstone and red marl1 which are identical in all their mineral characters with the secondary ,new ,red sandstone and marl of ,england4 ,in these secondary rocks the red ground is sometimes variegated with light greenish spots1 and the same may be seen in the tertiary formation of freshwater origin at ,coudes1 on the ,allier4 ,the marls are sometimes of a purplish-red colour1 as at ,champheix1 and are accompanied by a reddish limestone1 like the well-known cornstone1 which is associated with the ,old ,red sandstone of ,english geologists4 ,the red sandstone and marl of ,auvergne have evidently been derived from the degradation of gneiss and mica-schist1 which are seen in situ on the adjoining hills1 decomposing into a soil very similar to the tertiary red sand and marl4 ,we also find pebbles of gneiss1 mica-schist1 and quartz in the coarser sandstones of this group1 clearly pointing to the parent rocks from which the sand and marl are derived4 ,the red beds1 although destitute themselves of organic remains1 pass upwards into strata containing ,eocene fossils1 and are certainly an integral part of the lacustrine formation4 ,from this example the student will learn how small is the value of mineral character alone1 as a test of the relative age of rocks4 #b4 ,green and white foliated marls4--,the same primary rocks of ,auvergne1 which1 by the partial degradation of their harder parts1 gave rise to the quartzose grits and conglomerates before mentioned1 would1 by the reduction of the same materials into powder1 and by the decomposition of their felspar1 mica1 and hornblende1 produce aluminous clay1 and1 if a sufficient quantity of carbonate of lime was present1 calcareous marl4 ,this fine sediment would naturally be carried out to a greater distance from the shore1 as are the various finer marls now deposited in ,lake ,superior4 ,and1 as in the ,american lake1 shingle and sand are annually amassed near the northern shores1 so in ,auvergne the grits and conglomerates before mentioned were evidently formed near the borders4 ,illustration3 ,fig4 #aef4 ,cypris unifasciata1 a living species1 greatly magnified4 a4 ,upper part4 b4 ,side view of the same4 ,illustration3 ,fig4 #aeg4 ,cypris vidua1 a living species1 greatly magnified4#ahc-;,a ,the entire thickness of these marls is unknown2 but it certainly exceeds1 in some places1 #gjj feet4 ,they are1 for the most part1 either light-green or white1 and usually calcareous4 ,they are thinly foliated1--a character which frequently arises from the innumerable thin shells1 or carapace-valves1 of that small animal called ,cypris2 a genus which comprises several species1 of which some are recent1 and may be seen swimming swiftly through the waters of our stagnant pools and ditches4 ,the antennae1 at the end of which are fine pencils of hair1 are the principal organs of motion1 and are seen to vibrate with great rapidity4 ,this animal resides within two small valves1 not unlike those of a bivalve shell1 and moults its integuments periodically1 which the conchiferous mollusks do not4 ,this circumstance may partly explain the countless myriads of the shells of ,cypris which were shed in the ancient lakes of ,auvergne1 so as to give rise to divisions in the marl as thin as paper1 and that1 too1 in stratified masses several hundred feet thick4 ,a more convincing proof of the tranquillity and clearness of the waters1 and of the slow and gradual process by which the lake was filled up with fine mud1 cannot be desired4 ,but we may easily suppose that1 while this fine sediment was thrown down in the deep and central parts of the basin1 gravel1 sand1 and rocky fragments were hurried into the lake1 and deposited near the shore1 forming the group described in the preceding section4 ,not far from ,clermont1 the green marls1 containing the ,cypris in abundance1 approach to within a few yards of the granite which forms the borders of the basin4 ,the occurrence of these marls so near the ancient margin may be explained by considering that1 at the bottom of the ancient lake1 no coarse ingredients were deposited in spaces intermediate between the points where rivers and torrents entered1 but finer mud only was drifted there by currents4 ,the verticality of some of the beds in the above section bears testimony to considerable local disturbance subsequent to the deposition of the marls2 but such inclined and vertical strata are very rare4 ,illustration3 ,fig4 #aeh4 ,vertical strata of marl1 at ,champradelle1 near ,clermont4 ,a4 ,granite4 ,b4 ,space of #fj feet1 in which no section is seen4 ,c4 ,green marl1 vertical and inclined4 ,d4 ,white marl4 #c4 ,limestone1 travertin1 oolite4--,both the preceding members of the lacustrine deposit1 the marls and grits1 pass occasionally into limestone4 ,sometimes only concretionary nodules abound in them2 but these1 where there is an increase in the quantity of calcareous matter1 unite into regular beds4 ,on each side of the basin of the ,limagne1 both on the west at ,gannat1 and on the east at ,vichy1 a white oolitic limestone is quarried4 ,at ,vichy1 the oolite resembles our ,bath stone in appearance and beauty2 and1 like it1 is soft when first taken from the quarry1 but soon hardens on exposure to the air4 ,at ,gannat1 the stone contains land-shells and bones of quadrupeds1 resembling those of the ,paris gypsum4 ,at ,chadrat1 in the hill of ,la ,serre1 the limestone is pisolitic1 the small spheroids combining both the radiated and concentric structure4 ,indusial limestone4--,there is another remarkable form of freshwater limestone in ,auvergne1 called indusial1 from the cases1 or indusiae1 of caddis-worms 7the larvae of ,phryganea72 great heaps of which have been incrusted1 as they lay1 by carbonate of lime1 and formed into a hard travertin4 ,the rock is sometimes purely calcareous1 but there is occasionally an intermixture of siliceous matter4 ,several beds of it are frequently seen1 either in continuous masses1 or in concretionary nodules1 one upon another1 with layers of marl interposed4 ,the annexed drawing 7fig4 #aei47 will show the manner in which one of these indusial beds 7a7 is laid open at the surface1 between the marls 7b b71 near the base of the hill of ,gergovia2 and affords1 at the same time1 an example of the extent to which the lacustrine strata1 which must once have filled a hollow1 have been denuded1 and shaped out into hills and valleys1 on the site of the ancient lakes4 ,illustration3 ,fig4 #aei4 ,bed of indusial limestone1 interstratified with freshwater marl1 near ,clermont 7,kleinschrod47 ,illustration3 ,fig4 #afj4 ,larva of recent ,phryganea4#ahe-;,a ,illustration3 ,fig4 #afa4 a4 ,indusial limestone of ,auvergne4 b4 ,fossil ,paludina magnified4 ,we may often observe in our ponds the ,phryganea 7or ,caddis-fly71 in its caterpillar state1 covered with small freshwater shells1 which they have the power of fixing to the outside of their tubular cases1 in order1 probably1 to give them weight and strength4 ,the individual figured in the annexed cut1 which belongs to a species very abundant in ,england1 has covered its case with shells of a small ,planorbis4 ,in the same manner a large species of caddis-worm1 which swarmed in the ,eocene lakes of ,auvergne1 was accustomed to attach to its dwelling the shells of a small spiral univalve of the genus ,paludina4 ,a hundred of these minute shells are sometimes seen arranged around one tube1 part of the central cavity of which is often empty1 the rest being filled up with thin concentric layers of travertin4 ,the cases have been thrown together confusedly1 and often lie1 as in fig4 #afa41 at right angles one to the other4 ,when we consider that ten or twelve tubes are packed within the compass of a cubic inch1 and that some single strata of this limestone are #f feet thick1 and may be traced over a considerable area1 we may form some idea of the countless number of insects and mollusca which contributed their integuments and shells to compose this singularly constructed rock4 ,it is unnecessary to suppose that the ,phryganeae lived on the spots where their cases are now found2 they may have multiplied in the shallows near the margin of the lake1 or in the streams by which it was fed1 and their cases may have been drifted by a current far into the deep water4 ,in the summer of #ahcg1 when examining1 in company with ,dr4 ,beck1 a small lake near ,copenhagen1 ,i had an opportunity of witnessing a beautiful exemplification of the manner in which the tubular cases of ,auvergne were probably accumulated4 ,this lake1 called the ,fuure-,soe1 occurring in the interior of ,seeland1 is about twenty ,english miles in circumference1 and in some parts #bjj feet in depth4 ,round the shallow borders an abundant crop of reeds and rushes may be observed1 covered with the indusiae of the ,phryganea grandis and other species1 to which shells are attached4 ,the plants which support them are the bullrush1 ,scirpus lacustris1 and common reed1 ,arundo phragmitis1 but chiefly the former4 ,in summer1 especially in the month of ,june1 a violent gust of wind sometimes causes a current by which these plants are torn up by the roots1 washed away1 and floated off in long bands1 more than a mile in length1 into deep water4 ,the ,cypris swarms in the same lake2 and calcareous springs alone are wanting to form extensive beds of indusial limestone1 like those of ,auvergne4 #d4 ,gypseous marls4--,more than #ej feet of thinly laminated gypseous marls1 exactly resembling those in the hill of ,montmartre1 at ,paris1 are worked for gypsum at ,st4 ,romain1 on the right bank of the ,allier4 ,they rest on a series of green cypriferous marls which alternate with grit1 the united thickness of this inferior group being seen1 in a vertical section on the banks of the river1 to exceed #bej feet4 ,general arrangement1 origin1 and age of the freshwater formations of ,auvergne4--,the relations of the different groups above described cannot be learnt by the study of any one section2 and the geologist who sets out with the expectation of finding a fixed order of succession may perhaps complain that the different parts of the basin give contradictory results4 ,the arenaceous division1 the marls1 and the limestone1 may all be seen in some places to alternate with each other2 yet it can1 by no means1 be affirmed that there is no order of arrangement4 ,the sands1 sandstone1 and conglomerate1 constitute in general a littoral group2 the foliated white and green marls1 a contemporaneous central deposit2 and the limestone is for the most part subordinate to the newer portions of both4 ,the uppermost marls and sands are more calcareous than the lower2 and we never meet with calcareous rocks covered by a considerable thickness of quartzose sand or green marl4 ,from the resemblance of the limestones to the ,italian travertins1 we may conclude that they were derived from the waters of mineral springs1--such springs as even now exist in ,auvergne1 and which may be seen rising up through the granite1 and precipitating travertin4 ,they are sometimes thermal1 but this character is by no means constant4 ,it seems that1 when the ancient lake of the ,limagne first began to be filled with sediment1 no volcanic action had yet produced lava and scoriae on any part of the surface of ,auvergne4 ,no pebbles1 therefore1 of lava were transported into the lake1--no fragments of volcanic rocks embedded in the conglomerate4 ,but at a later period1 when a considerable thickness of sandstone and marl had accumulated1 eruptions broke out1 and lava and tuff were deposited1 at some spots1 alternately with the lacustrine strata4 ,it is not improbable that cold and thermal springs1 holding different mineral ingredients in solution1 became more numerous during the successive convulsions attending this development of volcanic agency1 and thus deposits of carbonate and sulphate of lime1 silex1 and other minerals were produced4 ,hence these minerals predominate in the uppermost strata4 ,the subterranean movements may then have continued until they altered the relative levels of the country1 and caused the waters of the lakes to be drained off1 and the farther accumulation of regular freshwater strata to cease4 ,we may easily conceive a similar series of events to give rise to analogous results in any modern basin1 such as that of ,lake ,superior1 for example1 where numerous rivers and torrents are carrying down the detritus of a chain of mountains into the lake4 ,the transported materials must be arranged according to their size and weight1 the coarser near the shore1 the finer at a greater distance from land2 but in the gravelly and sandy beds of ,lake ,superior no pebbles of modern volcanic rocks can be included1 since there are none of these at present in the district4 ,if igneous action should break out in that country1 and produce lava1 scoriae1 and thermal springs1 the deposition of gravel1 sand1 and marl might still continue as before2 but1 in addition1 there would then be an intermixture of volcanic gravel and tuff1 and of rocks precipitated from the waters of mineral springs4 ,although the freshwater strata of the ,limagne approach generally to a horizontal position1 the proofs of local disturbance are sufficiently numerous and violent to allow us to suppose great changes of level since the lacustrine period4 ,we are unable to assign a northern barrier to the ancient lake1 although we can still trace its limits to the east1 west1 and south1 where they were formed of bold granite eminences4 ,nor need we be surprised at our inability to restore entirely the physical geography of the country after so great a series of volcanic eruptions2 for it is by no means improbable that one part of it1 the southern1 for example1 may have been moved upwards bodily1 while others remained at rest1 or even suffered a movement of depression4 ,whether all the freshwater formations of the ,limagne d',auvergne belong to one period1 ,i cannot pretend to decide1 as large masses both of the arenaceous and marly groups are often devoid of fossils4 ,much light has been thrown on the mammiferous fauna by the labours of ,,mm4 ,bravard and ,croizet1 and by those of ,m4 ,pomel4 ,the last-mentioned naturalist has pointed out the specific distinction of all1 or nearly all1 the species of mammalia1 from those of the gypseous series near ,paris4 ,nevertheless1 many of the forms are analogous to those of ,eocene quadrupeds4 ,the ,cainotherium1 for example1 is not far removed from the ,anoplotherium1 and is1 according to ,waterhouse1 the same as the genus ,microtherium of the ,germans4 ,there are two species of marsupial animals allied to ,didelphys1 a genus also found in the ,paris gypsum4 ,the ,amphitragulus elegans of ,pomel1 has been identified with a ,rhenish species from ,weissenau near ,mayence1 called by ,kaup ,dorcatherium nanum2 and other ,auvergne fossils1 e4g41 ,microtherium ,reuggeri1 and a small rodent1 ,titanomys1 are specifically the same with mammalia of the ,mayence basin4 ,cantal4--,a freshwater formation1 very analogous to that of ,auvergne1 is situated in the department of ,haute ,loire1 near the town of ,le ,puy1 in ,velay1 and another occurs near ,aurillac1 in ,cantal4 ,the leading feature of the formation last mentioned1 as distinguished from those of ,auvergne and ,velay1 is the immense abundance of silex associated with calcareous marls and limestone4 ,the whole series may be separated into two divisions2 the lower1 composed of gravel1 sand1 and clay1 such as might have been derived from the wearing down and decomposition of the granitic schists of the surrounding country2 the upper system1 consisting of siliceous and calcareous marls1 contains subordinately gypsum1 silex1 and limestone4 ,the resemblance of the freshwater limestone of the ,cantal1 and its accompanying flint1 to the upper chalk of ,england1 is very instructive1 and well calculated to put the student upon his guard against relying too implicitly on mineral character alone as a safe criterion of relative age4 ,when we approach ,aurillac from the west1 we pass over great heathy plains1 where the sterile mica-schist is barely covered with vegetation4 ,near ,ytrac1 and between ,la ,capelle and ,viscamp1 the surface is strewed over with loose broken flints1 some of them black in the interior1 but with a white external coating2 others stained with tints of yellow and red1 and in appearance precisely like the flint gravel of our chalk districts4 ,when heaps of this gravel have thus announced our approach to a new formation1 we arrive at length at the escarpment of the lacustrine beds4 ,at the bottom of the hill which rises before us1 we see strata of clay and sand1 resting on mica-schist2 and above1 in the quarries of ,belbet1 ,leybros1 and ,bruel1 a white limestone1 in horizontal strata1 the surface of which has been hollowed out into irregular furrows1 since filled up with broken flint1 marl1 and dark vegetable mound4 ,in these cavities we recognize an exact counterpart to those which are so numerous on the furrowed surface of our own white chalk4 ,advancing from these quarries along a road made of the white limestone1 which reflects as glaring a light in the sun1 as do our roads composed of chalk1 we reach1 at length1 in the neighbourhood of ,aurillac1 hills of limestone and calcareous marl1 in horizontal strata1 separated in some places by regular layers of flint in nodules1 the coating of each nodule being of an opaque white colour1 like the exterior of the flinty nodules of our chalk4 ,it will be remembered that the siliceous stone of ,bilin1 called tripoli1 is a freshwater deposit1 and has been shown1 by ,ehrenberg1 to be of infusorial origin 7see p4 #bd474 ,what is true of the ,bohemian flint and opal1 where the beds attain a thickness of #ad feet1 may also1 perhaps1 be found to hold good respecting the silex of ,aurillac1 which may also have been immediately derived from the minute cases of microscopic animalcules4 ,but even if this conclusion be established1 the abundant supply both of siliceous1 calcareous1 and gypseous matter1 which the ancient lakes of ,france received1 may have been connected with the subterranean volcanic agency of which those regions were so long the theatre1 and which may have impregnated the springs with mineral matter1 even before the great outbreak of lava4 ,it is well known that the hot springs of ,iceland1 and many other countries1 contain silex in solution2 and it has been lately affirmed1 that steam at a high temperature is capable of dissolving quartzose rocks without the aid of any alkaline or other flux4#ahi-;,a ,travellers not unfrequently mention1 in their accounts of ,india1 ,australia1 and other distant lands1 that they have seen chalk with flints1 which they have assumed to be of the same age as the ,cretaceous system of ,europe4 ,a hasty observation of the white limestone and flint of ,aurillac might convey the same idea2 but when we turn from the mineral aspect and composition to the organic remains1 we find in the flints of the ,cantal the seed-vessels of the freshwater ,chara1 instead of the marine zoophytes so abundantly imbedded in chalk flints2 and in the limestone we meet with shells of ,limnea1 ,planorbis1 and other lacustrine genera1 instead of the oyster1 terebratula1 and echinus of the ,cretaceous period4 ,proofs of gradual deposition4--,some sections of the foliated marls in the valley of the ,cer1 near ,aurillac1 attest1 in the most unequivocal manner1 the extreme slowness with which the materials of the lacustrine series were amassed4 ,in the hill of ,barrat1 for example1 we find an assemblage of calcareous and siliceous marls2 in which1 for a depth of at least #fj feet1 the layers are so thin1 that thirty are sometimes contained in the thickness of an inch2 and when they are separated1 we see preserved in every one of them the flattened stems of ,charae1 or other plants1 or sometimes myriads of small ,paludinae and other freshwater shells4 ,these minute foliations of the marl resemble precisely some of the recent laminated beds of the ,scotch marl lakes1 and may be compared to the pages of a book1 each containing a history of a certain period of the past4 ,the different layers may be grouped together in beds from a foot to a foot and a half in thickness1 which are distinguished by differences of composition and colour1 the tints being white1 green1 and brown4 ,occasionally there is a parting layer of pure flint1 or of black carbonaceous vegetable matter1 about an inch thick1 or of white pulverulent marl4 ,we find several hills in the neighbourhood of ,aurillac composed of such materials1 for the height of more than #bjj feet from their base1 the whole sometimes covered by rocky currents of trachytic or basaltic lava4#aij-;,a ,thus wonderfully minute are the separate parts of which some of the most massive geological monuments are made up6 ,when we desire to classify1 it is necessary to contemplate entire groups of strata in the aggregate2 but if we wish to understand the mode of their formation1 and to explain their origin1 we must think only of the minute subdivisions of which each mass is composed4 ,we must bear in mind how many thin leaf-like seams of matter1 each containing the remains of myriads of testacea and plants1 frequently enter into the composition of a single stratum1 and how vast a succession of these strata unite to form a single group6 ,we must remember1 also1 that piles of volcanic matter1 like the ,plomb du ,cantal1 which rises in the immediate neighbourhood of ,aurillac1 are themselves equally the result of successive accumulation1 consisting of reiterated sheets of lava1 showers of scoriae1 and ejected fragments of rock4--,lastly1 we must not forget that continents and mountain-chains1 colossal as are their dimensions1 are nothing more than an assemblage of many such igneous and aqueous groups1 formed in succession during an indefinite lapse of ages1 and superimposed upon each other4 ,,footnotes3 #age-;,a ,bulletin des ,sci4 de la ,soc4 ,philom41 ,may1 #ahbe1 p4 #gd4 #agf-;,a ,hebert4 ,bulletin4 #ahdi1 vol4 vi4 #b;d series1 p4 #dei4 #aha-;,a ,scrope1 ,geology of ,central ,france1 p4 #ae4 #ahc-;,a ,see ,desmarest's ,crustacea1 plate #ee4 #ahe-;,a ,i believe that the ,british specimen here figured is ,p4 rhombica1 ,linn4 #ahi-;,a ,see ,proceedings of ,roy4 ,soc41 ,no4 #dd4 p4 #bcc4 #aij-;,a ,lyell and ,murchison1 sur les ,depots ,lacust4 ,tertiaries du ,cantal1 c4 ,ann4 des ,sci4 ,nat4 ,oct4 #ahbi4 ,,chapter ,,xvi4 ,,eocene ,,formations--continued4 ,subdivisions of the ,eocene group in the ,paris basin--,gypseous series--,extinct quadrupeds--,impulse given to geology by ,cuvier's osteological discoveries--,shelly sands called sables moyens--,calcaire grossier--,miliolites--,calcaire siliceux--,lower ,eocene in ,france--,lits coquilliers--,sands and plastic clay--,english ,eocene strata--,freshwater and fluvio-marine beds--,barton beds--,bagshot and ,bracklesham division--,large ophidians and saurians--,lower ,eocene and ,london ,clay proper--,fossil plants and shells--,strata of ,kyson in ,suffolk--,fossil monkey and opossum--,mottled clays and sands below ,london ,clay--,nummulitic formation of ,alps and ,pyrenees--,its wide geographical extent--,eocene strata in the ,united ,states--,section at ,claiborne1 ,alabama--,colossal cetacean--,orbitoid limestone--,burr stone4 ,from what was said in the two preceding chapters1 it has already appeared that we have in ,england no true chronological representative of the ,miocene faluns of the ,loire1 and none of the ,upper ,eocene group described in the last chapter4 ,but1 when we descend to the middle and inferior divisions of the ,eocene system of ,france1 we find that they have their equivalents in ,great ,britain4 ,,middle ,,eocene4--,,france4 ,gypseous series 7#b4 a1 ,table1 p4 #age474--,next below the upper marine sands of the neighbourhood of ,paris1 we find a series of white and green marls1 with subordinate beds of gypsum4 ,these are most largely developed in the central parts of the ,paris basin1 and1 among other places1 in the ,hill of ,montmartre1 where its fossils were first studied by ,m4 ,cuvier4 ,the gypsum quarried there for the manufacture of plaster of ,paris occurs as a granular crystalline rock1 and1 together with the associated marls1 contains land and fluviatile shells1 together with the bones and skeletons of birds and quadrupeds4 ,several land plants are also met with1 among which are fine specimens of the fan palm or palmetto tribe 7,flabellaria74 ,the remains also of freshwater fish and of crocodiles and other reptiles1 occur in the gypsum4 ,the skeletons of mammalia are usually isolated1 often entire1 the most delicate extremities being preserved2 as if the carcasses1 clothed with their flesh and skin1 had been floated down soon after death1 and while they were still swoln by the gases generated by their first decomposition4 ,the few accompanying shells are of those light kinds which frequently float on the surface of rivers1 together with wood4 ,m4 ,prevost has therefore suggested that a river may have swept away the bodies of animals1 and the plants which lived on its borders1 or in the lakes which it traversed1 and may have carried them down into the centre of the gulf into which flowed the waters impregnated with sulphate of lime4 ,we know that the ,fiume ,salso in ,sicily enters the sea so charged with various salts that the thirsty cattle refuse to drink of it4 ,a stream of sulphureous water1 as white as milk1 descends into the sea from the volcanic mountain of ,idienne on the east of ,java2 and a great body of hot water1 charged with sulphuric acid1 rushed down from the same volcano on one occasion1 and inundated a large tract of country1 destroying1 by its noxious properties1 all the vegetation4#aia-;,a ,in like manner the ,pusanibio1 or ,vinegar ,river1 of ,colombia1 which rises at the foot of ,purace1 an extinct volcano1 #g1ejj feet above the level of the sea1 is strongly impregnated with sulphuric and muriatic acids and with oxide of iron4 ,we may easily suppose the waters of such streams to have properties noxious to marine animals1 and in this manner the entire absence of marine remains in the ossiferous gypsum may be explained4#aia-;,b ,there are no pebbles or coarse sand in the gypsum2 a circumstance which agrees well with the hypothesis that these beds were precipitated from water holding sulphate of lime in solution1 and floating the remains of different animals4 ,in this formation the relics of about fifty species of quadrupeds1 including the genera ,paleotherium1 ,anoplotherium1 and others1 have been found1 all extinct1 and nearly four-fifths of them belonging to a division of the order ,pachydermata1 which is now represented by only four living species2 namely three tapirs and the daman of the ,cape4 ,with them a few carnivorous animals are associated1 among which are a species of fox and gennet4 ,of the ,rodentia1 a dormouse and a squirrel2 of the ,insectivora1 a bat2 and of the ,marsupialia 7an order now confined to ,america1 ,australia1 and some contiguous islands71 an opossum1 have been discovered4 ,of birds1 about ten species have been ascertained1 the skeletons of some of which are entire4 ,none of them are referable to existing species4#aib-;,a ,the same remark applies to the fish1 according to ,,mm4 ,cuvier1 and ,agassiz1 as also to the reptiles4 ,among the last are crocodiles and tortoises of the genera ,emys and ,trionyx4 ,the tribe of land quadrupeds most abundant in this formation is such as now inhabits alluvial plains and marshes1 and the banks of rivers and lakes1 a class most exposed to suffer by river inundations4 ,whether the disproportion of carnivorous animals can be ascribed to this cause1 or whether they were comparatively small in number and dimensions1 as in the indigenous fauna of ,australia1 when first known to ,europeans1 is a point on which it would be rash1 perhaps1 to offer an opinion in the present state of our knowledge4 ,illustration3 ,fig4 #afb4 ,paleotherium magnum4 ,the ,paleothere1 above alluded to1 resembled the living tapir in the form of the head1 and in having a short proboscis1 but its molar teeth were more like those of the rhinoceros 7see fig4 #afc474 ,paleotherium magnum was of the size of a horse1 #c or #d feet high4 ,the annexed woodcut1 fig4 #afb41 is one of the restorations which ,cuvier attempted of the outline of the living animal1 derived from the study of the entire skeleton4 ,when the ,french osteologist declared in the early part of the present century1 that all the fossil quadrupeds of the gypsum of ,paris were extinct1 the announcement of so startling a fact1 on such high authority1 created a powerful sensation1 and from that time a new impulse was given throughout ,europe to the progress of geological investigation4 ,eminent naturalists1 it is true1 had long before maintained that the shells and zoophytes1 met with in many ancient ,european rocks1 had ceased to be inhabitants of the earth1 but the majority even of the educated classes continued to believe that the species of animals and plants now contemporary with man1 were the same as those which had been called into being when the planet itself was created4 ,it was easy to throw discredit upon the new doctrine by asking whether corals1 shells1 and other creatures previously unknown1 were not annually discovered8 and whether living forms corresponding with the fossils might not yet be dredged up from seas hitherto unexamined8 ,but from the era of the publication of ,cuvier's ,ossements ,fossiles1 and still more his popular ,treatise called ,a ,theory of the ,earth1 sounder views began to prevail4 ,it was clearly demonstrated that most of the mammalia found in the gypsum of ,montmartre differed even generically from any now existing1 and the extreme improbability that any of them1 especially the larger ones1 would ever be found surviving in continents yet unexplored1 was made manifest4 ,moreover1 the non-admixture of a single living species in the midst of so rich a fossil fauna was a striking proof that there had existed a state of the earth's surface zoologically unconnected with the present order of things4 ,illustration3 ,fig4 #afc4 ,upper molar tooth of ,paleotherium magnum from ,isle of ,wight4 7,owen's ,brit4 ,foss4 p4 #cag47 ,reduced one-third4 ,gres de ,beauchamp 7#b4 b1 ,table1 p4 #age474--;,in some parts of the ,paris basin1 sands and marls1 called the ,gres de ,beauchamp1 or ,sables ,moyens1 divide the gypseous beds from the underlying ,calcaire grossier4 ,these sands contain more than #cjj species of marine shells1 many of them peculiar1 but others common to the underlying marine deposit 7,no4 #b4 c474 ,calcaire grossier 7#b4 c1 ,table1 p4 #age474--,the formation called ,calcaire grossier consists of a coarse limestone1 often passing into sand4 ,it contains the greater number of the fossil shells which characterize the ,paris basin4 ,no less than #djj distinct species have been procured from a single spot near ,grignon1 where they are embedded in a calcareous sand1 chiefly formed of comminuted shells1 in which1 nevertheless1 individuals in a perfect state of preservation1 both of marine1 terrestrial1 and freshwater species1 are mingled together4 ,some of the marine shells may have lived on the spot2 but the ,cyclostoma and ,limnea must have been brought thither by rivers and currents1 and the quantity of triturated shells implies considerable movement in the waters4 ,nothing is more striking in this assemblage of fossil testacea than the great proportion of species referable to the genus ,cerithium 7see fig4 #afd474 ,there occur no less than #acg species of this genus in the ,paris basin1 and almost all of them in the calcaire grossier4 ,now the living ,cerithia inhabit the sea near the mouths of rivers1 where the waters are brackish2 so that their abundance in the marine strata now under consideration is in harmony with the hypothesis1 that the ,paris basin formed a gulf into which several rivers flowed1 the sediment of some of which gave rise to the beds of clay and lignite before mentioned2 while a distinct freshwater limestone1 called calcaire siliceux1 which will presently be described1 was precipitated from the waters of others situated farther to the south4 ,illustration3 ,fig4 #afd4 ,cerithium cinctum4#aid-;,a #d ,illustrations3 ,,eocene ,,foraminifera4 ,fig4 #afe4 ,calcarina rarispina1 ,desh4 b4 natural size4 a1 c4 same magnified4 ,fig4 #aff4 ,spirolina stenostoma1 ,desh4 ,b4 natural size4 ,a1 ,c1 ,d4 same magnified4 ,fig4 #afg4 ,triloculina inflata1 ,desh4 b4 natural size4 a1 c1 d1 same magnified4 ,fig4 #afh4 ,clavulina corrugata1 ,desh4 a4 natural size4 b1 c4 same magnified4 ,in some parts of the calcaire grossier round ,paris1 certain beds occur of a stone used in building1 and called by the ,french geologists ,miliolite limestone4 ,it is almost entirely made up of millions of microscopic shells1 of the size of minute grains of sand1 which all belong to the class ,foraminifera4 ,figures of some of these are given in the annexed woodcut4 ,as this miliolitic stone never occurs in the ,faluns1 or ,miocene strata of ,brittany and ,touraine1 it often furnishes the geologist with a useful criterion for distinguishing the detached ,eocene and ,miocene formations1 scattered over those and other adjoining provinces4 ,the discovery of the remains of ,paleotherium and other mammalia in some of the upper beds of the calcaire grossier shows that these land animals began to exist before the deposition of the overlying gypseous series had commenced4 ,calcaire siliceux4--,this compact siliceous limestone extends over a wide area4 ,it resembles a precipitate from the waters of mineral springs1 and is often traversed by small empty sinuous cavities4 ,it is1 for the most part1 devoid of organic remains1 but in some places contains freshwater and land species1 and never any marine fossils4 ,the siliceous limestone and the calcaire grossier occupy distinct parts of the ,paris basin1 the one attaining its fullest development in those places where the other is of slight thickness4 ,they also alternate with each other towards the centre of the basin1 as at ,sergy and ,osny2 and there are even points where the two rocks are so blended together that portions of each may be seen in hand specimens4 ,thus1 in the same bed1 at ,triel1 we have the compact freshwater limestone1 characterized by its ,limneae1 mingled with the coarse marine limestone1 with its small multilocular shells1 or miliolites1 dispersed through it in countless numbers4 ,these microscopic testacea are also accompanied by ,cerithia and other shells of the calcaire grossier4 ,it is very extraordinary that in this instance both kinds of sediment must have been thrown down together on the same spot1 yet each retains its own peculiar organic remains4 ,from these facts we may conclude1 that while to the north1 where the bay was probably open to the sea1 a marine limestone was formed1 another deposit of freshwater origin was introduced to the southward1 or at the head of the bay2 for it appears that during the ,eocene period1 as now1 the ocean was to the north1 and the continent1 where the great lakes existed1 to the south4 ,from that southern region we may suppose a body of fresh water to have descended1 charged with carbonate of lime and silica1 the water being perhaps in sufficient volume to freshen the upper end of the bay4 ,the gypseous series 7#b4 a1 ,table1 p4 #age471 before described1 was once supposed to be entirely subsequent in origin to the two groups1 called calcaire grossier and calcaire siliceux4 ,but ,m4 ,prevost has pointed out that in some localities they alternate repeatedly with both4 ,the gypsum1 with its associated marl and limestone1 is in greatest force towards the centre of the basin1 where the calcaire grossier and calcaire siliceux are less fully developed4 ,hence ,m4 ,prevost infers1 that while those two principal deposits were gradually in progress1 the one towards the north1 and the other towards the south1 a river descending from the east may have brought down the gypseous and marly sediment4 ,it must be admitted1 as highly probable1 that a bay or narrow sea1 #ahj miles in length1 would receive1 at more points than one1 the waters of the adjoining continent4 ,at the same time1 we must be prepared to find that the simultaneous deposition of two or more sets of strata in one basin1 some freshwater and others marine1 must have produced very complex results4 ,but1 in proportion as it is more difficult in these cases to discover any fixed order of superposition in the associated mineral masses1 so also is it more easy to explain the manner of their origin1 and to reconcile their relations to the agency of known causes4 ,instead of the successive irruptions and retreats of the sea1 and changes in the chemical nature of the fluid1 and other speculations of the earlier geologists1 we are now simply called upon to imagine a gulf1 into one extremity of which the sea entered1 and at the other a large river1 while other streams may have flowed in at different points1 whereby an indefinite number of alternations of marine and freshwater beds would be occasioned4 ,,lower ,,eocene1 ,,france4 ,lits coquilliers 7#c4 a1 ,table1 p4 #age474--;,below the calcaire grossier are extensive deposits of sand1 in the upper parts of which some marine beds1 called lits coquilliers1 occur1 in which ,m4 d',archiac has discovered #bjj species of shells4 ,many of these are peculiar1 but the larger portion appear to agree with species of the calcaire grossier1 so that the line of demarcation usually adopted between the ,french ,lower and ,middle ,eocene formations1 seems not to be very strongly drawn4 ,sands and plastic clay 7#c4 b1 ,table1 p4 #age47--;,at the base of the tertiary system in ,france are extensive deposits of sands1 with occasional beds of clay used for pottery1 and called argile plastique4 ,fossil oysters 7,ostrea bellovacina7 abound in some places1 and in others there is a mixture of fluviatile shells1 such as ,cyrena cuneiformis 7fig4 #ahg4 p4 #bjd471 ,melania inquinata 7fig4 #ahh471 and others1 frequently met with in beds occupying the same position in the valley of the ,thames4 ,layers of lignite also accompany the inferior clays and sands4 ,immediately upon the chalk at the bottom of all the tertiary strata there is often a conglomerate or breccia of rolled and angular chalk flints1 cemented by siliceous sand4 ,these beds appear to be of littoral origin1 and imply the previous emergence of some portions of the chalk1 and its waste by denudation4 ,illustration3 ,fig4 #afi4 ,cardium porulosum4 ,paris and ,london basins4 ,the lower sandy beds of the ,paris basin are often called the sands of the ,soissonais1 from a district so named #ej miles ,n4,e4 of ,paris4 ,one of the shells of the formation is adduced by ,m4 ,deshayes as an example of the changes which certain species underwent in the successive stages of their existence4 ,it seems that different varieties of the ,cardium porulosum are characteristic of different formations4 ,in the ,lower ,eocene of the ,soissonais this shell acquires but a small volume1 and has many peculiarities1 which disappear in the lowest beds of the calcaire grossier4 ,in these the shell attains its full size1 and many distinctive characters1 which are again modified in the uppermost beds of the calcaire grossier2 and these last modifications of form are preserved throughout the whole of the upper marine 7or ,upper ,eocene7 series4#aig-;,a ,,english ,,eocene ,,formations4 ,the ,eocene areas of ,hampshire and ,london are delineated in the map 7fig4 #aec4 p4 #agd474 ,the following table will show the succession of the principal deposits found in our island4 ,the true place of the ,bagshot sands1 in this series1 was never accurately ascertained till ,mr4 ,prestwich published1 in #ahdg1 his classification of the ,english ,eocene strata1 dividing them into three principal formations1 in which the ,bagshot sands occupied the central place4#aig-;,b ,localities4 #a4 ,upper ,eocene4 ,wanting in ,great ,britain4 a4 ,freshwater and ,headon ,hill1 ,isle of fluvio-marine beds4 ,wight2 and ,hordwell ,cliff1 ,hants4 #b4 ,middle ,eocene b4 ,barton beds4 ,barton ,cliff1 ,hants4 c4 ,bagshot and ,bracklesham ,bagshot ,heath1 ,surrey2 sands and clays4 ,bracklesham ,bay1 ,sussex4 a4 ,london ,clay ,proper1 ,highgate ,hill1 and ,bognor beds4 ,middlesex2 ,i4 of ,sheppey2 ,bognor1 #c4 ,lower ,eocene ,sussex4 b4 ,mottled and ,plastic ,newhaven1 ,sussex2 clays and sands4 ,reading1 ,berks2 ,woolwich1 ,kent4 ,illustration3 ,fig4 #agj4 ,lymnea longiscata4 ,freshwater ,eocene strata1 ,isle of ,wight4 ,freshwater beds 7#b4 a1 ,table1 p4 #age474--;,in the northern part of the ,isle of ,wight1 beds of marl1 clay1 and sand1 and a friable limestone1 containing freshwater shells1 are seen1 containing shells of the genera ,lymnea 7see fig4 #agj471 ,planorbis1 ,melanopsis1 ,cyrena1 c41 several of them of the same species as those occurring in the ,eocene beds of the ,paris basin4 ,gyrogonites1 also1 or seed-vessels of ,chara1 exhibiting a similar specific identity1 occur4 ,at ,headon ,hill1 on the western side of the island1 where these beds are seen in the sea-cliffs1 some of the strata contain a few marine and estuary shells1 such as ,cytheraea1 ,corbula1 c41 showing a temporary occupation of the area by brackish or salt water1 after which the river or a lake seems again to have prevailed4 ,a species of fan-palm1 ,flabellaria ,lamanonis1 ,brong41 like one which characterizes the ,parisian ,eocene beds1 has been recently detected by ,dr4 ,mantell in this formation1 in ,whitecliff ,bay1 at the eastern end of the island4 ,several of the species of extinct quadrupeds already alluded to as characterizing the gypsum of ,montmartre have been discovered by ,messrs4 ,pratt and ,fox1 in the ,isle of ,wight1 chiefly at ,binstead1 near ,ryde1 as ,palaeotherium magnum1 ,p4 medium1 ,p4 minus1 ,p4 minimum1 ,p4 curtum1 ,p4 crassum1 also ,anoplotherium commune1 ,a4 secundarium1 ,dichobune cervinum1 and ,chaeropotamus ,cuvieri4 ,in ,hordwell cliff1 also on the ,hampshire coast1 several of these species1 with other quadrupeds of new genera1 such as ,paloplotherium1 ,owen1 have been met with2 and remains of a remarkable carnivorous genus1 ,hyaenodon4 ,these fossils are accompanied by the bones of ,trionyx1 and other tortoises1 and by two land snakes of the genus ,paleryx1 ,owen1 from #c to #d feet long1 also a species of crocodile1 and an alligator4 ,among other fossils collected by ,lady ,hastings1 ,sir ,philip ,egerton has recognized the well-known gar or bony pike of the ,american rivers1 a ganoid fish of the genus ,lepidotus1 with its hard shining scales4 ,the shells of ,hordwell are similar to those of the freshwater beds of the ,isle of ,wight1 and among them are a few specifically undistinguishable from recent testacea1 as ,paludina lenta and ,helix labyrinthica1 the latter discovered by ,mr4 ,s4 ,wood1 and identified with an existing ,n4 ,american helix4 ,the white and green marls of this freshwater series in ,hampshire1 and some of the accompanying limestones1 often resemble those of ,france in mineral character and colour in so striking a manner1 as to suggest the idea that the sediment was derived from the same region1 or produced contemporaneously under very similar geographical circumstances4 ,barton beds4--,both in the cliffs of ,headon ,hill and ,hordwell1 already mentioned1 the freshwater series rests on a mass of pure white sand without fossils1 and this is seen in ,barton ,cliff to overlie a marine deposit1 in which #bji species of testacea have been found4 ,more than half of these are peculiar2 and1 according to ,mr4 ,prestwich1 only #aa of them common to the ,london ,clay proper1 being in the proportion of only #e per cent4 ,on the other hand1 #gj of them agree with the calcaire grossier shells4 ,as this is the newest purely marine bed of the ,eocene series known in ,england1 we might have expected that some of its peculiar fossils would be found to agree with the upper ,eocene strata described in the last chapter1 and accordingly some identifications have been cited with testacea1 both of the ,berlin and ,belgian strata4 ,it is nearly a century since ,brander published1 in #agff1 an account of the organic remains collected from these cliffs1 and his excellent figures of the shells then deposited in the ,british ,museum are justly admired by conchologists for their accuracy4 ,bagshot ,sands 7#b4 c1 ,table1 p4 #aig474--,these beds1 consisting chiefly of siliceous sand1 occupy extensive tracts round ,bagshot1 in ,surrey1 and in the ,new ,forest1 ,hampshire4 ,they succeed next in chronological order1 and may be separated into three divisions1 the upper and lower consisting of light yellow sands1 and the central of dark green sands and brown clays1 the whole reposing on the ,london clay proper4#aii-;,a ,although the ,bagshot beds are usually devoid of fossils1 they contain marine shells in some places1 among which ,venericardia planicosta 7see fig4 #aga47 is abundant1 with ,turritella sulcifera and ,nummulites laevigatus4 7,see fig4 #agd4 p4 #bjj47 ,illustration3 ,fig4 #aga4 ,venericardia planicosta1 ,lamck4 ,cardita planicosta1 ,deshayes4 ,at ,bracklesham ,bay1 near ,chichester1 in ,sussex1 the characteristic shells of this member of the ,eocene series are best seen2 among others1 the huge ,cerithium giganteum1 so conspicuous in the calcaire grossier of ,paris1 where it is sometimes #b feet in length4 ,the volutes and cowries of this formation1 as well as the lunulites and other corals1 seem to favour the idea of a warm climate having prevailed1 which is borne out by the discovery of a serpent ,palaeophis typhaeus1 exceeding1 according to ,mr4 ,owen1 #bj feet in length1 and allied to the ,boa1 ,python1 ,coluber1 and ,hydrus4 ,the compressed form and diminutive size of certain caudal vertebrae indicate so much analogy with ,hydrus as to induce the ,hunterian professor to pronounce the extinct ophidian to have been marine4#aii-;,b ,he had previously combated with so much success the evidence advanced1 to prove the existence in the ,northern ,ocean of sea-serpents in our own times1 that he will not be suspected of any undue bias in contending for their former existence in the ,british ,eocene seas4 ,the climate1 however1 of the ,middle ,eocene period was evidently far more genial2 and amongst the companions of the sea-serpent of ,bracklesham was an extinct ,gavial 7,gavialis ,dixoni1 ,owen71 and numerous fish1 such as now frequent the seas of warm latitudes1 as the sword-fish 7see fig4 #agb4 p4 #bjj47 and gigantic rays of the genus ,miliobates4 7,see fig4 #agc47 ,out of #aic species of testacea procured from the ,bagshot and ,bracklesham beds in ,england1 #abf occur in the ,french calcaire grossier4 ,it was clearly1 therefore1 coeval with that part of the ,parisian series more nearly than with any other4 ,the ,nummulites laevigatus 7see fig4 #agd471 a fossil characteristic of the lower beds of the calcaire grossier1 is abundant at ,bracklesham4 ,illustration3 ,fig4 #agb4 ,prolonged premaxillary bone or sword of a fossil sword-fish 7,caelorhynchus74 ,bracklesham4 ,dixon's ,fossils of ,sussex1 pl4 #h4 ,illustration3 ,fig4 #agc4 ,dental plates of ,myliobates ,edwardsi4 ,bracklesham ,bay4 ,ibid4 pl4 #h4 ,illustration3 ,fig4 #agd4 ,nummulites 7,nummularia7 laevigatus4 ,bracklesham4 ,ibid4 pl4 #h4 a4 section of the nummulite4 b4 group1 with an individual showing the exterior of the shell4 ,london clay proper 7#c4 a1 ,table1 p4 #aig474--,this formation underlies the preceding1 and consists of tenacious brown and blueish grey clay1 with layers of concretions called septaria1 which abound chiefly in the brown clay1 and are obtained in sufficient numbers from the cliffs near ,harwich1 and from shoals of the ,essex coast1 to be used for making ,roman cement4 ,the principal localities of fossils in the ,london clay are ,highgate ,hill1 near ,london1 the island of ,sheppey1 and ,bognor in ,hampshire4 ,out of #acc fossil shells1 ,mr4 ,prestwich found only #bj to be common to the calcaire grossier 7from which #fjj species have been obtained71 while #cc are common to the lits coquilliers 7p4 #aif471 in which only #bjj species are known in ,france4 ,we may presume1 therefore1 that the ,london clay proper is older than the calcaire grossier4 ,this may perhaps remove a difficulty which ,m4 ,adolphe ,brongniart has experienced when comparing the ,eocene ,flora of the neighbourhoods of ,london and ,paris4 ,the fossil species of the island of ,sheppey1 he observes1 indicate a much more tropical climate than the ,eocene ,flora of ,france1 which has been derived principally from the gypseous series4 ,the latter resembles the vegetation of the borders of the ,mediterranean rather than that of an equatorial region4 ,mr4 ,bowerbank1 in a valuable publication on the fossil fruits and seeds of the island of ,sheppey1 near ,london1 has described no less than thirteen fruits of palms of the recent type ,nipa1 now only found in the ,molucca and ,philippine islands4 7,see fig4 #age47 ,these plants are allied to the cocoa-nut tribe on the one side1 and on the other to the ,pandanus1 or screw-pine4 ,species of cocoa-nuts are also met with1 and other kinds of palms2 also three species of ,anona1 or custard-apple2 cucurbitaceous fruits1 also 7the gourd and melon family71 are in considerable abundance4 ,fruits of various species of ,acacia are in profusion2 and1 although less decidedly tropical1 imply a warm climate4 ,illustration3 ,fig4 #age4 ,nipadites ellipticus4 ,bow4 ,fossil palm of ,sheppey4 ,the contiguity of land may be inferred not only from these vegetable productions1 but also from the teeth and bones of crocodiles and turtles1 since these creatures1 as ,mr4 ,conybeare has remarked1 must have resorted to some shore to lay their eggs4 ,of turtles there were numerous species referred to extinct genera1 and1 for the most part1 not equal in size to the largest living tropical turtles4 ,a snake1 which must have been #ac feet long1 of the genus ,palaeophis before mentioned1 has also been described by ,mr4 ,owen from ,sheppey1 of a different species from that of ,bracklesham4 ,a true crocodile1 also1 ,crocodilus toliapicus1 and another ,saurian more nearly allied to the gravial1 accompany the above fossils4 ,a bird allied to the vultures1 and a quadruped of the new genus ,hyracotherium1 allied to the ,hyrax1 ,hog1 and ,chaeropotamus1 are also among the additions made of late years to the palaeontology of this division4 #c ,illustrations3 ,,fossil ,,shells ,,of ,,the ,,london ,,clay4 ,fig4 #agf4 ,mitra scabra4 ,fig4 #agg4 ,rostellaria macroptera1 ,sow4 ,one-third of nat4 size4 ,fig4 #agh4 ,crassatella sulcata4 ,the marine shells of the ,london clay confirm the inference derivable from the plants and reptiles of a high temperature4 ,thus1 many species of ,conus1 ,mitra1 and ,voluta occur1 a large ,cypraea1 a very large ,rostellaria1 and shells of the genera ,terebellum1 ,cancellaria1 ,crassatella1 and others1 with four or more species of ,nautilus 7see fig4 #ahb47 and other cephalopoda of extinct genera1 one of the most remarkable of which is the ,belosepia4#bjb-;,a 7,see fig4 #ahc47 ,illustration3 ,fig4 #agi4 ,nautilus centralis4 ,illustration3 ,fig4 #ahj4 ,voluta athleta4 ,illustration3 ,fig4 #aha4 ,terebellum fusiforme4 ,illustration3 ,fig4 #ahb4 ,aturia zigzag4 ,bronn4 ,syn4 ,nautilus zigzag4 ,sow4 ,london clay4 ,sheppey4 ,illustration3 ,fig4 #ahc4 ,belosepia sepiodea1 ,de ,blainv4 ,london clay4 ,sheppey4 ,the above shells are accompanied by a sword-fish 7,tetrapterus priscus1 ,agassiz71 about #h feet long1 and a saw-fish 7,pristis bisulcatus1 ,ag471 about #aj feet in length2 genera now foreign to the ,british seas4 ,on the whole1 no less than #ej species of fish have been described by ,m4 ,agassiz from these beds in ,sheppey1 and they indicate1 in his opinion1 a warm climate4 ,illustration3 ,fig4 #ahd4 ,molar of monkey 7,macacus74 ,strata of ,kyson in ,suffolk4--,at ,kyson1 a few miles east of ,woodbridge1 a bed of ,eocene clay1 #ab feet thick1 underlies the red crag4 ,beneath it is a deposit of yellow and white sand1 of considerable interest1 in consequence of many peculiar fossils contained in it4 ,its geological position is probably the lowest part of the ,london clay proper4 ,in this sand has been found the first example of a fossil quadrumanous animal discovered in ,great ,britain1 namely1 the teeth and part of a jaw1 shown by ,mr4 ,owen to belong to a monkey of the genus ,macacus 7see fig4 #ahd474 ,the mammiferous fossils1 first met with in the same bed1 were those of an opossum 7,didelphys7 7see fig4 #ahe471 and an insectivorous bat 7fig4 #ahf471 together with many teeth of fishes of the shark family4 ,mr4 ,colchester in #ahdj obtained other mammalian relics from ,kyson1 among which ,mr4 ,owen has recognized several teeth of the genus ,hyracotherium1 and the vertebrae of a large serpent1 probably a ,palaeophis4 ,as the remains both of the ,hyracotherium and ,palaeophis were afterwards met with in the ,london clay1 as before remarked1 these fossils confirmed the opinion previously entertained1 that the ,kyson sand belongs to the ,eocene period4 ,the ,macacus1 therefore1 constitutes the first example of any quadrumanous animal found in strata as old as the ,eocene1 or so far from the equator as lat4 #eb deg4 ,n4 ,it was not until after the year #ahcf that the existence of any fossil quadrumana was brought to light4 ,since that period they have been found in ,france1 ,india1 and ,brazil4 ,illustration3 ,fig4 #ahe4 ,molar tooth and part of jaw of opossum4 ,from ,kyson4#bjc-;,a ,illustration3 ,fig4 #ahf4 ,molars of insectivorous bats1 twice nat4 size4 ,from ,kyson1 ,suffolk4 ,mottled or ,plastic ,clays1 c4 7#c4 b1 ,table1 p4 #aig474--,no formations can be more dissimilar on the whole in mineral character than the ,eocene deposits of ,england and ,paris2 those of our own island being almost exclusively of mechanical origin1--accumulations of mud1 sand1 and pebbles2 while in the neighbourhood of ,paris we find a great succession of strata composed of a coarse white limestone1 and compact siliceous limestone with beds of crystalline gypsum and siliceous sandstone1 and sometimes pure flint used for millstones4 ,hence it is by no means an easy task to institute an exact comparison between the various members of the ,english and ,french series1 and to settle their respective ages4 ,it is clear that a continual change was going on in the fauna and flora by the coming in of new species and the dying out of others2 and contemporaneous changes of geographical conditions were also in progress in consequence of the rising and sinking of the land and bottom of the sea4 ,a particular subdivision1 therefore1 of time was occasionally represented in one area by land1 in another by an estuary1 in a third by the sea1 and even where the conditions were in both areas of a marine character1 there was often shallow water in one1 and deep sea in another1 producing a want of agreement in the state of animal life4 ,at the commencement1 however1 of the ,eocene formations in ,france and ,england1 we find an exception to this rule1 for a marked similarity of mineral character reigns in the lowest division1 whether in the basins of ,paris1 ,hampshire1 or ,london4 ,this uniformity of aspect must be seen in order to be fully appreciated1 since the beds consist simply of sand1 mottled clays1 and well-rolled flint pebbles1 derived from the chalk1 and varying in size from that of a pea to an egg4 ,these strata may be seen at ,reading1 at ,blackheath1 near ,london1 and at ,woolwich4 ,in some of the lowest of them1 banks of oysters are observed1 consisting of ,ostrea bellovicina1 so common in ,france in the same relative position1 and ,ostrea edulina1 scarcely distinguishable from the living eatable species4 ,in this formation at ,bromley1 ,dr4 ,buckland found one large pebble to which five full-grown oysters were affixed1 in such a manner as to show that they had commenced their first growth upon it1 and remained attached to it through life4 ,in several places1 as at ,woolwich on the ,thames1 at ,newhaven in ,sussex1 and elsewhere1 a mixture of marine and freshwater testacea distinguishes this member of the series4 ,among the latter1 ,melania inquinata 7see fig4 #ahh47 and ,cyrena cuneiformis are very common4 ,they probably indicate points where rivers entered the ,eocene sea4 ,illustration3 ,fig4 #ahg4 ,cyrena cuneiformis1 ,min4 ,con4 ,natural size4 ,illustration3 ,fig4 #ahh4 ,melania inquinata1 ,des4 ,nat4 size4 ,syn4 ,cerithium melanoides1 ,min4 ,con4 ,with us as in ,france1 clay of this formation is used in some places1 as near ,poole in ,dorsetshire1 for pottery2 and hence the name of plastic clay was adopted for the group by ,mr4 ,t4 ,webster4 ,lignite also is associated with it in some spots1 as in the ,paris basin4 ,before the minds of geologists had become familiar with the theory of the gradual sinking of the land1 and its conversion into sea at different periods1 and the consequent change from shallow to deep water1 the freshwater and littoral character of this inferior group appeared strange and anomalous4 ,after passing through many hundred feet of ,london clay1 proved by its fossils to have been deposited in salt water of considerable depth1 we arrive at beds of fluviatile origin4 ,thick masses1 also1 of shingle indicate the proximity of land1 where the flints of the chalk were rolled into sand and pebbles1 and spread continuously over wide spaces1 as in the ,isle of ,wight1 in the south of ,hampshire1 and near ,london1 always appearing at the bottom of the ,eocene series4 ,it may be asked why they did not constitute simply a narrow littoral zone1 such as we might look for in strata formed at a moderate distance from the shore4 ,in answer to this inquiry1 the student must be reminded1 that wherever a gently-sloping land is gradually sinking and becoming submerged1 shingle may be heaped up successively over a wide area1 although marine currents have no power of dispersing it simultaneously over a large space4 ,in such cases it is not the shingle which recedes from the coast1 but the coast which recedes from the shingle1 which is formed one mass after another as often as successive portions of the land are converted into sea and others into a sea beach4 ,the ,london area appears to have been upraised before that of ,hampshire1 so that it never became the receptacle of the ,barton clays1 nor of the overlying fluvio-marine and freshwater beds of ,hordwell and the north part of the ,isle of ,wight4 ,on the other hand1 the ,hampshire ,eocene area seems to have emerged before that of ,paris1 so that no marine beds of the ,upper ,eocene era were ever thrown down in ,hampshire4 ,nummulitic formation of the ,alps and ,pyrenees4--,it has long been matter of controversy1 whether the nummulitic rocks of the ,alps and ,pyrenees should be regarded as ,eocene or ,cretaceous2 but the number of geologists of high authority who regard this important group as belonging to the lowest tertiary system of ,europe has for many years been steadily increasing4 ,the late ,m4 ,alex4 ,brongniart first declared the specific identity of many of the shells of this formation with those of the marine strata near ,paris1 although he obtained them from the summit of the ,diablerets1 one of the loftiest of the ,swiss ,alps1 which rises more than #aj1jjj feet above the level of the sea4 ,deposits of the same age1 found on the flanks of the ,pyrenees1 contain also a great number of shells common to the ,paris and ,london areas1 and three or four species only which are common to the cretaceous formation4 ,the calcareous division consists often of a compact crystalline marble1 full of nummulites 7see fig4 #ahi471 shells of the class ,foraminifera4 ,illustration3 ,fig4 #ahi4 ,nummulites4 ,peyrehorade1 ,pyrenees4 a4 external surface of one of the nummulites1 of which longitudinal sections are seen in the limestone4 b4 transverse section of same4 ,the nummulitic limestone of the ,alps is often of great thickness1 and is immediately covered by another series of strata of dark-coloured slates1 marls1 and fucoidal sandstones1 to the whole of which the provincial name of flysch has been given in parts of ,switzerland4 ,the researches of ,sir ,roderick ,murchison in the ,alps in #ahdg enable us to refer the whole of these beds to the ,eocene period1 and it seems probable that they most nearly coincide in age with the ,lower ,eocene4 ,they enter into the disturbed and loftiest portions of the ,alpine chain1 to the elevation of which they enable us therefore to assign a comparatively modern date4 ,the nummulitic formation1 with its characteristic fossils1 plays a far more conspicuous part than any other tertiary group in the solid framework of the earth's crust1 whether in ,europe1 ,asia1 or ,africa4 ,it often attains a thickness of many thousand feet1 and extends from the ,alps to the ,apennines4 ,it is found in the ,carpathians1 and in full force in the north of ,africa1 as1 for example1 in ,algeria and ,morocco4 ,it has also been traced from ,egypt into ,asia ,minor1 and across ,persia by ,bagdad to the mouths of the ,indus4 ,it occurs not only in ,cutch1 but in the mountain ranges which separate ,scinde from ,persia1 and which form the passes leading to ,caboul2 and it has been followed still farther eastward into ,india4 ,some members of this lower tertiary formation in the central ,alps1 including even the superior strata called flysch1 have been converted into crystalline rocks1 and changed into saccharoid marble1 quartz1 rock1 and mica-schist4#bjf-;,a ,,eocene ,,strata ,,in ,,the ,,united ,,states4 ,in ,north ,america the ,eocene formations occupy a large area bordering the ,atlantic1 which increases in breadth and importance as it is traced southwards from ,delaware and ,maryland to ,georgia and ,alabama4 ,they also occur in ,louisiana and other states both east and west of the valley of the ,mississippi4 ,at ,claiborne in ,alabama no less than four hundred species of marine shells1 with many echinoderms and teeth of fish1 characterize one member of this system4 ,among the shells the ,cardita planicosta1 before mentioned 7fig4 #aga4 p4 #aii471 is in abundance2 and this fossil1 and some others identical with ,european species1 or very nearly allied to them1 make it highly probable that the ,claiborne beds agree in age with the central or ,bracklesham group of ,england1 and the calcaire grossier of ,paris4#bjf-;,b ,higher in the series is a remarkable calcareous rock1 formerly called the nummulite limestone1 from the great number of discoid bodies resembling nummulites which it contains1 fossils now referred by ,a4 d',orbigny to the genus ,orbitoides1 which has been demonstrated by ,dr4 ,carpenter to belong to the ,foraminifera4#bjf-;,c ,the following section will enable the reader to understand the position of the three subdivisions of the series1 ,nos4 #a1 #b1 and #c41 the relations of which ,i ascertained in ,clarke ,county1 between the rivers ,alabama and ,tombeckbee4 ,illustration3 ,fig4 #aij4 ,cross section4 #a4 ,sand1 marl1 c41 with numerous fossils4 #b4 ,white or rotten limestone1 with ,zeuglodon4 ,eocene4 #c4 ,orbitoidal1 or so called nummulitic limestone4 #d4 ,overlying formation of sand and clay without fossils4 ,age unknown4 ,the lowest set of strata1 ,no4 #a41 having a thickness of more than #ajj feet1 comprise marly beds1 in which the ,ostrea sellaeformis occurs1 a shell ranging from ,alabama to ,virginia1 and being a representative form of the ,ostrea flabellula of the ,eocene group of ,europe4 ,in others beds of ,no4 #a41 two ,european shells1 ,cardita planicosta1 before mentioned1 and ,solarium canaliculatum are found1 with a great many other species peculiar to ,america4 ,numerous corals1 also1 and the remains of placoid fish and of rays occur1 and the swords1 as they are called1 of sword fishes1 all bearing a great generic likeness to those of the ,eocene strata of ,england and ,france4 ,no4 #b4 7fig4 #aij47 is a white limestone1 sometimes soft and argillaceous1 but in parts very compact and calcareous4 ,it contains several peculiar corals1 and a large ,nautilus allied to ,n4 zigzag1 also in its upper bed a gigantic cetacean1 called ,zeuglodon by ,owen4#bjg-;,a #b ,illustrations3 ,zeuglodon cetoides1 ,owen4 ,basilosaurus1 ,harlan4 ,fig4 #aia4 ,molar tooth1 natural size4 ,fig4 #aib4 ,vertebra1 reduced4 ,the colossal bones of this cetacean are so plentiful in the interior of ,clarke ,county as to be characteristic of the formation4 ,the vertebral column of one skeleton found by ,dr4 ,buckley at a spot visited by me1 extended to the length of nearly #gj feet1 and not far off part of another backbone nearly #ej feet long was dug up4 ,i obtained evidence1 during a short excursion1 of so many localities of this fossil animal within a distance of #aj miles1 as to lead me to conclude that they must have belonged to at least forty distinct individuals4 ,mr4 ,owen first pointed out that the huge animal was not reptilian1 since each tooth was furnished with double roots 7see fig4 #aia471 implanted in corresponding double sockets2 and his opinion of the cetacean nature of the fossil was afterwards confirmed by ,dr4 ,wyman and ,professor ,r4 ,w4 ,gibbes4 ,that it was an extinct species of the whale tribe has since been placed beyond all doubt by the discovery of the entire skull of another fossil of the same family1 found to have the double occipital condyles only met with in mammals1 and the convoluted tympanic bones which are characteristic of cetaceans4 ,near the junction of ,no4 #b4 and the incumbent limestone1 ,no4 #c41 next to be mentioned1 are strata characterized by the following shells3 ,spondylus dumosus 7,plagiostoma dumosum1 ,morton71 ,pecten ,poulsoni1 ,pecten perplanus1 and ,ostrea cretacea4 ,no4 #c4 7fig4 #aij47 is a white limestone1 for the most part made up of the ,orbitoides of d',orbigny before mentioned 7p4 #bjf471 formerly supposed to be a nummulite1 and called ,n4 ,mantelli1 mixed with a few lunulites and small corals and shells4#bjh-;,a ,the origin of this cream-coloured soft stone1 like that of our white chalk1 which it much resembles1 is1 ,i believe1 due to the decomposition of the orbitoides4 ,the surface of the country where it prevails is sometimes marked by the absence of wood1 like our chalk downs1 or is covered exclusively by the ,juniperus ,virginiana1 as certain chalk districts in ,england by yew trees and juniper4 ,some of the shells of this limestone are common to the ,claiborne beds1 but many of them are peculiar4 ,it will be seen in the section 7fig4 #aij4 p4 #aee47 that the strata1 ,nos4 #a1 #b1 #c41 are1 for the most part1 overlaid by a dense formation of sand or clay without fossils4 ,in some points of the bluff or cliff of the ,alabama river1 at ,claiborne1 the beds ,nos4 #a1 #b41 are exposed nearly from top to bottom1 whereas at other points the newer formation1 ,no4 #d41 occupies the face of nearly the whole cliff4 ,the age of this overlying mass has not yet been determined1 as it has hitherto proved destitute of organic remains4 ,the burr-stone strata of the ,southern ,states contain so many fossils agreeing with those of ,claiborne1 that it doubtless belongs to the same part of the ,eocene group1 though ,i was not fortunate enough to see the relations of the two deposits in a continuous section4 ,mr4 ,tuomey considers it as the lower portion of the series4 ,it may1 perhaps1 be a form of the ,claiborne beds in places where lime was wanting1 and where silex1 derived from the decomposition of felspar1 predominated4 ,it consists chiefly of slaty clays1 quartzose sands1 and loam1 of a brick red colour1 with layers of chert or burr-stone1 used in some places for millstones4 ,,footnotes3 #aia-;,a ,leyde ,magaz4 voor ,wetensch ,konst en ,lett41 partie v4 cahier i4 p4 #ga4 ,cited by ,rozet1 ,journ4 de ,geologie1 tom4 i4 p4 #dc4 #aia-;,b ,m4 ,c4 ,prevost1 ,submersions ,iteratives1 c4 ,note #bc4 #aib-;,a ,cuvier1 ,oss4 ,foss41 tom4 iii4 p4 #bee4 #aid-;,a ,this species is found both in the ,paris and ,london basins4 #aig-;,a ,coquilles caracterist4 des ,terrains1 #ahca4 #aig-;,b ,quarterly ,geol4 ,journal1 vol4 iii4 p4 #cec4 #aii-;,a ,prestwich1 ,quart4 ,geol4 ,journ4 vol4 iii4 p4 #chf4 #aii-;,b ,palaeont4 ,soc4 ,monograph4 ,rept4 pt4 ii4 p4 #fa4 #bjb-;,a ,for description of ,eocene ,cephalopoda1 see ,monograph by ,f4 ,e4 ,edwards1 ,palaeontograph4 ,soc4 #ahdi4 #bjc-;,a ,annals of ,nat4 ,hist4 vol4 iv4 ,no4 #bc4 ,nov4 #ahci4 #bjf-;,a ,murchison1 ,quart4 ,journ4 of ,geol4 ,soc4 vol4 v41 and ,lyell1 vol4 vi4 #ahej4 ,anniversary ,address4 #bjf-;,b ,see paper by the author1 ,quart4 ,journ4 ,geol4 ,soc4 vol4 iv1 p4 #ab42 and ,second ,visit to the ,u4 ,s4 vol4 ii4 p4 #ei4 #bjf-;,c ,quart4 ,journ4 ,geol ,soc4 vol4 vi4 p4 #cb4 #bjg-;,a ,see ,memoir by ,r4 ,w4 ,gibbes1 ,journ4 of ,acad4 ,nat4 ,sci4 ,philad4 vol4 i4 #ahdg4 #bjh-;,a ,lyell1 ,quart4 ,journ4 ,geol4 ,soc4 #ahdg1 vol4 iv4 p4 #ae4 ,,chapter ,,xvii4 ,,cretaceous ,,group4 ,divisions of the cretaceous series in ,north-,western ,europe--,upper cretaceous strata--,maestricht beds--,chalk of ,faxoe--,white chalk--,characteristic fossils--,extinct cephalopoda--,sponges and corals of the chalk--,signs of open and deep sea--,wide area of white chalk--,its origin from corals and shells--,single pebbles in chalk--,siliceous sandstone in ,germany contemporaneous with white chalk--,upper greensand and gault--,lower cretaceous strata--,atherfield section1 ,isle of ,wight--,chalk of ,south of ,europe--,hippurite limestone--,cretaceous ,flora--,chalk of ,united ,states4 ,having treated in the preceding chapters of the tertiary strata1 we have next to speak of the uppermost of the secondary groups1 called the ,chalk or ,cretaceous 7,no4 #f4 ,table1 p4 #ajc471 because in those parts of ,europe where it was first studied its upper members are formed of that remarkable white earthy limestone1 termed chalk 7creta74 ,the inferior division consists1 for the most part1 of clays and sands1 called ,greensand1 because some of the sands derive a bright green colour from intermixed grains of chloritic matter4 ,the cretaceous strata in the north-west of ,europe may be thus divided#bji-;,a3 ,upper ,cretaceous4 #a4 ,maestricht beds and ,faxoe limestone4 #b4 ,upper white chalk1 with flints4 #c4 ,lower white chalk1 without flints1 passing downwards into chalk marl1 which is slightly argillaceous4 #d4 ,upper greensand4 #e4 ,gault4 ,lower ,cretaceous4 #f4 ,lower greensand--,ironsand1 clay1 and occasional beds of limestone 7,kentish rag74 ,maestricht ,beds4--,on the banks of the ,meuse1 at ,maestricht1 reposing on ordinary white chalk with flints1 we find an upper calcareous formation about #ajj feet thick1 the fossils of which are1 on the whole1 very peculiar1 and all distinct from tertiary species4 ,some few are of species common to the inferior white chalk1 among which may be mentioned ,belemnites mucronatus 7see fig4 #aig47 and ,pecten quadricostatus4 ,besides the ,belemnite there are other genera1 such as ,ammonite1 ,baculite1 and ,hamite1 never found in strata newer than the cretaceous1 but frequently met with in these ,maestricht beds4 ,on the other hand1 ,volutes and other genera of univalve shells1 usually met with only in tertiary strata1 occur4 ,the upper part of the rock1 about #bj feet thick1 as seen in ,st4 ,peter's ,mount1 in the suburbs of ,maestricht1 abounds in corals1 often detachable from the matrix2 and these beds are succeeded by a soft yellowish limestone #ej feet thick1 extensively quarried from time immemorial for building4 ,the stone below is whiter1 and contains occasional nodules of grey chert or chalcedony4 ,m4 ,bosquet1 with whom ,i lately examined this formation 7,august1 #ahej71 pointed out to me a layer of chalk from #b to #d inches thick1 containing green earth and numerous encrinital stems1 which forms the line of demarcation between the strata containing the fossils peculiar to ,maestricht and the white chalk below4 ,the latter is distinguished by regular layers of black flint in nodules1 and by several shells1 such as ,terebratula carnea 7see fig4 #bja471 wholly wanting in beds higher than the green band4 ,some of the organic remains1 however1 for which ,st4 ,peter's ,mount is celebrated1 occur both above and below that parting layer1 and1 among others1 the great marine reptile1 called ,mosasaurus1 a saurian supposed to have been #bd feet in length1 of which the entire skull and a great part of the skeleton have been found4 ,such remains are chiefly met with in the soft freestone1 the principal member of the ,maestricht beds4 ,chalk of ,faxoe4--,in the island of ,seeland1 in ,denmark1 the newest member of the chalk series1 seen in the sea-cliffs at ,stevens ,klint resting on white chalk with flints1 is a yellow limestone1 a portion of which1 at ,faxoe1 where it is used as a building-stone1 is composed of corals1 even more conspicuously than is usually observed in recent coral reefs4 ,it has been quarried to the depth of more than #dj feet1 but its thickness is unknown4 ,the imbedded shells are chiefly casts1 many of them of univalve mollusca1 which1 as they strictly belong to the ,cretaceous era1 are worthy of notice1 since such forms1 whether spiral or patelliform1 are wanting in the white chalk of ,europe generally4 ,thus1 there are two species of ,cypraea1 one of ,oliva1 two of ,mitra1 four of the genus ,cerithium1 six of ,fusus1 two of ,trochus1 one ,patella1 one ,emarginula1 c41 on the whole1 more than thirty univalves1 spiral or patelliform1 not one of which is common to the white chalk4 ,at the same time1 a large proportion of the accompanying bivalve shells1 echinoderms1 and zoophytes1 are specifically identical with fossils of older parts of the ,cretaceous series4 ,among the cephalopoda of ,faxoe1 may be mentioned ,baculites ,faujasii and ,belemnites mucronatus1 shells of the white chalk4 ,the claws and entire shell of a small crab1 ,brachyurus rugosus 7,schlotheim71 are scattered through the ,faxoe stone1 reminding us of similar crustaceans enclosed in the rocks of many modern coral reefs4#baa-;,a ,some small portions of this coralline formation consist of white earthy chalk2 it is1 therefore1 clear that this substance must have been produced simultaneously1 a fact of some importance1 as bearing on the theory of the origin of white chalk2 for the decomposition of such corals as we see at ,faxoe is capable1 we know1 of forming white mud1 undistinguishable from chalk1 and which we may suppose to have been dispersed far and wide through the ocean1 in which such reefs as that of ,faxoe grew4 ,illustration3 ,fig4 #aic4 ,section from ,hertfordshire1 in ,england1 to ,sena1 in ,france4 ,white ,chalk 7#b4 and #c4 ,tab4 p4 #bji474--,the highest beds of chalk in ,england and ,france consist of a pure1 white1 calcareous mass1 usually too soft for a building stone1 but sometimes passing into a more solid state4 ,it consists1 almost purely1 of carbonate of lime2 the stratification is often obscure1 except where rendered distinct by interstratified layers of flint1 a few inches thick1 occasionally in continuous beds1 but oftener in nodules1 and recurring at intervals from #b to #d feet distant from each other4 ,this upper chalk is usually succeeded1 in the descending order1 by a great mass of white chalk without flints1 below which comes the chalk marl1 in which there is a slight admixture of argillaceous matter4 ,the united thickness of the three divisions in the south of ,england equals1 in some places1 #ajjj feet4#baa-;,b ,the annexed section1 fig4 #aic41 will show the manner in which the white chalk extends from ,england into ,france1 covered by the tertiary strata described in former chapters1 and reposing on lower cretaceous beds4 ,among the conspicuous forms of mollusca wholly foreign to the tertiary and recent periods1 and which we meet with in the white chalk1 are the ,belemnite1 ,ammonite1 ,baculite1 and ,turrilite1 all genera of ,cephalopoda1 a family to which the living cuttle-fish and nautilus belong4 ,illustration3 ,fig4 #aid4 ,portion of ,baculites ,faujasii4 ,maestricht and ,faxoe beds and white chalk4 ,illustration3 ,fig4 #aie4 ,portion of ,baculites anceps4 ,maestricht and ,faxoe beds and white chalk4 ,illustration3 ,fig4 #aif4 ,turrilites4 a4 ,turrilites costatus4 ,chalk marl4 b4 ,same1 showing the indented border of the partition of the chambers4 ,illustration3 ,fig4 #aig4 ,belemnites4 a4 ,belemnites mucronatus4 b4 ,same1 showing internal structure4 ,maestricht1 ,faxoe1 and white chalk4 ,among the brachiopoda in the white chalk1 the ,terebratulae are very abundant4 ,these shells are known to live at the bottom of the sea1 where the water is tranquil and of some depth 7see figs4 #aih1 #aii1 #bjj1 #bja474 ,with these are associated some forms of oyster 7see figs4 #bjb4 and #bjd471 and other bivalves 7figs4 #bjc1 #bje1 #bjf1 #bjg1 #bjh474 ,illustration3 ,fig4 #aih4 ,terebratula plicatilis1 dorsal view4 ,upper white chalk4 ,illustration3 ,fig4 #aii4 ,terebratula plicatilis1 side view4 ,illustration3 ,fig4 #bjj4 ,terebratula pumilus4 7,magas pumilus1 ,sow47 ,upper white chalk4 ,illustration3 ,fig4 #bja4 ,terebratula carnea4 ,upper white chalk4 ,illustration3 ,fig4 #bjb4 ,ostrea vesicularis4 ,gryphaea globosa1 ,min4 ,con4 ,upper chalk and upper greensand4 ,illustration3 ,fig4 #bjc4 ,pecten #e-;costatus4 ,white chalk1 upper and lower greensands4 ,illustration3 ,fig4 #bjd4 ,ostrea carinata4 ,chalk marl1 upper and lower greensands4 ,illustration3 ,fig4 #bje4 ,crania ,parisiensis1 inferior or attached valve4 ,upper white chalk4 ,illustration3 ,fig4 #bjf4 ,plagiostoma ,hoperi1 ,sow4 ,syn4 ,lima ,hoperi4 ,white chalk and upper greensand4 ,illustration3 ,fig4 #bjg4 ,plagiostoma spinosum1 ,sow4 ,syn4 ,spondylus spinosus4 ,upper white chalk4 ,among the rest1 no form marks the cretaceous era in ,europe1 ,america1 and ,india1 in a more striking manner than the extinct genus ,inoceramus 7,catillus of ,lamk471 the shells of which are distinguished by a fibrous texture1 and are often met with in fragments1 having1 probably1 been extremely friable4 ,illustration3 ,fig4 #bjh4 ,inoceramus ,lamarckii4 ,syn4 ,catillus ,lamarckii4 ,white ,chalk 7,dixon's ,geol4 ,sussex1 ,tab4 #bh4 fig4 #bi47 ,illustration3 ,fig4 #bji4 ,eschara disticha4 a4 ,natural size4 b4 ,portion magnified4 ,white chalk4 #b ,illustrations3 ,fig4 #baj4 ,fig4 #baa4 ,a branching sponge in a flint1 from the white chalk4 ,from the collection of ,mr4 ,bowerbank4 ,with these mollusca are many corals 7figs4 #bji1 #baj1 #baa47 and sea urchins 7fig4 #bab471 which are alike marine1 and1 for the most part1 indicative of a deep sea4 ,they are dispersed indifferently through the soft chalk1 and hard flint1 and some of the flinty nodules owe their irregular forms to inclosed zoophytes1 as in the specimen represented in fig4 #baa41 where the hollows in the exterior are caused by the branches of a sponge seen on breaking open the flint1 fig4 #baj4 ,illustration3 ,fig4 #bab4 ,ananchytes ovata4 ,white chalk1 upper and lower4 a4 ,side view4 b4 ,bottom of the shell on which both the oral and anal apertures are placed2 the anal being more round1 and at the smaller end4 ,of the singular family called ,rudistes1 by ,lamarck1 hereafter to be mentioned1 as extremely characteristic of the chalk of ,southern ,europe1 a single representative only 7fig4 #bac47 has been discovered in the white chalk of ,england4 #d ,illustrations3 ,hippurites ,mortoni1 ,mantell4 ,houghton1 ,sussex4 ,white chalk4 ,diameter one seventh of nat4 size4 ,fig4 #bac4 ,two individuals deprived of their opercula1 adhering together4 ,fig4 #bad4 ,same seen from above4 ,fig4 #bae4 ,transverse section of part of the wall of the shell1 magnified to show the structure4 ,fig4 #baf4 ,vertical section of the same4 ,on the side where the shell is thinnest1 there is one external furrow and corresponding internal ridge1 a1 b4 figs4 #bac1 #bad42 but they are usually less prominent than in these figures4 ,this species has been referred to ,hippurites1 but does not1 ,i believe1 fully agree in character with that genus4 ,i have never seen the opercular piece1 or valve1 as it is called by those conchologists who regard the ,rudistes as bivalve mollusca4 ,the specimen above figured was discovered by the late ,mr4 ,dixon4 ,the remains of fishes of the ,upper ,cretaceous formations consist chiefly of teeth of the shark family of genera1 in part common to the tertiary1 and partly distinct4 ,but we meet with no bones of land animals1 nor any terrestrial or fluviatile shells1 nor any plants1 except sea weeds1 and here and there a piece of drift wood4 ,all the appearances concur in leading us to conclude that the white chalk was the product of an open sea of considerable depth4 ,the existence of turtles and oviparous saurians1 and of a ,pterodactyl or winged-lizard1 found in the white chalk of ,maidstone1 implies1 no doubt1 some neighbouring land2 but a few small islets in mid-ocean1 like ,ascension1 so much frequented by migratory droves of turtles1 might perhaps have afforded the required retreat where these creatures might lay their eggs in the sand1 or from which the flying species may have been blown out to sea4 ,of the vegetation of such islands we have scarcely any indication1 but it consisted partly of cycadeous plants2 for a fragment of one of these was found by ,capt4 ,ibbetson in the chalk marl of the ,isle of ,wight1 and is referred by ,a4 ,brongniart to ,clathraria ,lyellii1 ,mantell1 a species common to the antecedent ,wealden period4 ,geographical extent and origin of the ,while ,chalk4--,the area over which the white chalk preserves a nearly homogeneous aspect is so vast1 that the earlier geologists despaired of discovering any analogous deposits of recent date4 ,pure chalk1 of nearly uniform aspect and composition1 is met with in a north-west and south-east direction1 from the north of ,ireland to the ,crimea1 a distance of about #aadj geographical miles2 and in an opposite direction it extends from the south of ,sweden to the south of ,bordeaux1 a distance of about #hdj geographical miles4 ,in ,southern ,russia1 according to ,sir ,r4 ,murchison1 it is sometimes #fjj feet thick1 and retains the same mineral character as in ,france and ,england1 with the same fossils1 including ,inoceramus ,cuvieri1 ,belemnites mucronatus1 and ,ostrea vesicularis4 ,but it would be an error to imagine1 that the chalk was ever spread out continuously over the whole of the space comprised within these limits1 although it prevailed in greater or less thickness over large portions of that area4 ,on turning to those regions of the ,pacific where coral reefs abound1 we find some archipelagoes of lagoon islands1 such as that of the ,dangerous ,archipelago1 for instance1 and that of ,radack1 with several adjoining groups1 which are from #aajj to #abjj miles in length1 and #cjj or #djj miles broad2 and the space to which ,flinders proposed to give the name of the ,corralline ,sea is still larger2 for it is bounded on the east by the ,australian barrier--all formed of coral rock1--on the west by ,new ,caledonia1 and on the north by the reefs of ,louisiade4 ,although the islands in these areas may be thinly sown1 the mud of the decomposing zoophytes may be scattered far and wide by oceanic currents4 ,that this mud would resemble chalk ,i have already hinted when speaking of the ,faxoe limestone1 p4 #baa42 and it was also remarked in an early part of this volume1 that some even of that chalk which appears to an ordinary observer quite destitute of organic remains1 is nevertheless1 when seen under the microscope1 full of fragments of corals and sponges2 together with the valves of entomostraca1 the shells of foraminifera1 and still more minute infusoria4#bae-;,a 7,see p4 #bf47 ,now it had been often suspected1 before these discoveries1 that white chalk might be of animal origin1 even where every trace of organic structure has vanished4 ,this bold idea was partly founded on the fact1 that the chalk consisted of pure carbonate of lime1 such as would result from the decomposition of testacea1 echini1 and corals2 and partly on the passage observable between these fossils when half decomposed and chalk4 ,but this conjecture seemed to many naturalists quite vague and visionary1 until its probability was strengthened by new evidence brought to light by modern geologists4 ,we learn from ,lieutenant ,nelson1 that1 in the ,bermuda ,islands1 there are several basins or lagoons almost surrounded and enclosed by reefs of coral4 ,at the bottom of these lagoons a soft white calcareous mud is formed by the decomposition of ,eschara1 ,flustra1 ,cellepora1 and other corallines4 ,this mud1 when dried1 is undistinguishable from common white earthy chalk2 and some portions of it1 presented to the ,museum of the ,geological ,society of ,london1 might1 after full examination1 be mistaken for ancient chalk1 but for the labels attached to them4 ,about the same time ,mr4 ,c4 ,darwin observed similar facts in the coral islands of the ,pacific2 and came also to the opinion1 that much of the soft white mud found at the bottom of the sea near coral reefs has passed through the bodies of worms1 by which the stony masses of coral are everywhere bored2 and other portions through the intestines of fishes2 for certain gregarious fishes of the genus ,sparus are visible through the clear water1 browsing quietly1 in great numbers1 on living corals1 like grazing herds of graminivorous quadrupeds4 ,on opening their bodies1 ,mr4 ,darwin found their intestines filled with impure chalk4 ,this circumstance is the more in point1 when we recollect how the fossilist was formerly puzzled by meeting1 in chalk1 with certain bodies1 called cones of the larch1 which were afterwards recognized by ,dr4 ,buckland to be the excrement of fish4#baf-;,a ,these spiral coprolites 7see figures71 like the scales and bones of fossil fish in the chalk1 are composed chiefly of phosphate of lime4 #b ,illustrations3 ,fig4 #bag4 ,fig4 #bah4 ,coprolites of fish called ,iulo-eido-copri1 from the chalk4 ,mr4 ,dana1 when describing the elevated coral reef of ,oahu1 in the ,sandwich ,islands1 says1 that some varieties of the rock consist of aggregated shells1 imbedded in a compact calcareous base as firm in texture as any secondary limestone2 while others are like chalk1 having its colour1 its earthy fracture1 its soft homogeneous texture1 and being an equally good writing material4 ,the same author describes1 in many growing coral reefs1 a similar formation of modern chalk1 undistinguishable from the ancient4#baf-;,b ,the extension over a wide submarine area of the calcareous matrix of the chalk1 as well as of the imbedded fossils1 would take place the more readily1 in consequence of the low specific gravity of the shells of mollusca and zoophytes1 when compared with ordinary sand and mineral matter4 ,the mud also derived from their decomposition would be much lighter than argillaceous and other inorganic mud1 and very easily transported by currents1 especially in salt water4 ,single pebbles in chalk4--,the general absence of sand and pebbles in the white chalk has been already mentioned2 but the occurrence here and there1 in the south-east of ,england1 of a few isolated pebbles of quartz and green schist1 some of them #b or #c inches in diameter1 has justly excited much wonder4 ,if these had been carried to the spots where we now find them by waves or currents from the lands once bordering the cretaceous sea1 how happened it that no sand or mud were transported thither at the same time8 ,we cannot conceive such rounded stones to have been drifted like erratic blocks by ice#bag-;,a1 for that would imply a cold climate in the ,cretaceous period2 a supposition inconsistent with the luxuriant growth of large chambered univalves1 numerous corals1 and many fish1 and other fossils of tropical forms4 ,now in ,keeling ,island1 one of those detached masses of coral which rise up in the wide ,pacific1 ,captain ,ross found a single fragment of greenstone1 where every other particle of matter was calcareous2 and ,mr4 ,darwin concludes that it must have come there entangled in the roots of a large tree4 ,he reminds us that ,chamisso1 the distinguished naturalist who accompanied ,kotzebue1 affirms1 that the inhabitants of the ,radack archipelago1 a group of lagoon islands1 in the midst of the ,pacific1 obtained stones for sharpening their instruments by searching the roots of trees which are cast up on the beach4#bag-;,b ,it may perhaps be objected1 that a similar mode of transport cannot have happened in the cretaceous sea1 because fossil wood is very rare in the chalk4 ,nevertheless wood is sometimes met with1 and in the same parts of the chalk where the pebbles are found1 both in soft stone and in a silicified state in flints4 ,in these cases it has often every appearance of having been floated from a distance1 being usually perforated by boring-shells1 such as the ,teredo and ,fistulana4#bag-;,c ,the only other mode of transport which suggests itself is sea-weed4 ,dr4 ,beck informs me1 that in the ,lym-,fiord1 in ,jutland1 the ,fucus vesiculosus1 often called kelp1 sometimes grows to the height of #aj feet1 and the branches rising from a single root form a cluster several feet in diameter4 ,when the bladders are distended1 the plant becomes so buoyant as to float up loose stones several inches in diameter1 and these are often thrown by the waves high up on the beach4 ,the ,fucus giganteus of ,solander1 so common in ,terra del ,fuego1 is said by ,captain ,cook to attain the length of #cfj feet1 although the stem is not much thicker than a man's thumb4 ,it is often met with floating at sea1 with shells attached1 several hundred miles from the spots where it grew4 ,some of these plants1 says ,mr4 ,darwin1 were found adhering to large loose stones in the inland channels of ,terra del ,fuego1 during the voyage of the ,beagle in #ahcd2 and that so firmly1 that the stones were drawn up from the bottom into the boat1 although so heavy that they could scarcely be lifted in by one person4 ,some fossil sea-weeds have been found in the ,cretaceous formation1 but none1 as yet1 of large size4 ,but we must not imagine that because pebbles are so rare in the white chalk of ,england and ,france there are no proofs of sand1 shingle1 and clay having been accumulated contemporaneously even in the ,european seas4 ,the siliceous sandstone1 called upper quader by the ,germans1 overlies white argillaceous chalk1 or plaener-kalk1 a deposit resembling in composition and organic remains the chalk marl of the ,english series4 ,this sandstone contains as many fossil shells common to our white chalk as could be expected in a sea-bottom formed of such different materials4 ,it sometimes attains a thickness of #fjj feet1 and by its jointed structure and vertical precipices1 plays a conspicuous part in the picturesque scenery of ,saxon ,switzerland1 near ,dresden4 ,upper greensand 7#d4 ,tab4 p4 #bji474--,the lower chalk without flints passes gradually downwards1 in the south of ,england1 into an argillaceous limestone1 the chalk marl1 already alluded to1 in which ammonites and other cephalopoda1 so rare in the higher parts of the series1 appear4 ,this marly deposit passes in its turn into beds containing green particles of a chloritic mineral1 called the upper greensand4 ,in parts of ,surrey calcareous matter is largely intermixed1 forming a stone called firestone4 ,in the cliffs of the southern coast of the ,isle of ,wight1 this upper greensand is #ajj feet thick1 and contains bands of siliceous limestone and calcareous sandstone with nodules of chert4 #b ,illustrations3 ,fossils of the ,upper ,greensand4 ,fig4 #bai4 a4 ,terebratula lyra4 ,upper greensand4 b4 ,same1 seen in profile4 ,france4 ,fig4 #bbj4 ,ammonites ,rhotomagensis4 ,upper greensand4 ,illustration3 ,fig4 #bba4 ,hamites spiniger 7,fitton72 near ,folkstone4 ,gault4 ,gault4--,the lowest member of the upper ,cretaceous group1 usually about #ajj feet thick in the ,s4,e4 of ,england1 is provincially termed ,gault4 ,it consists of a dark blue marl1 sometimes intermixed with greensand4 ,many peculiar forms of cephalopoda1 such as the ,hamite 7fig4 #bba47 and ,scaphite1 with other fossils1 characterize this formation1 which1 small as is its thickness1 can be traced by its organic remains to distant parts of ,europe1 as1 for example1 to the ,alps4 ,the phosphate of lime1 found lately near ,farnham1 in ,surrey1 in such abundance as to be used largely by the agriculturist for fertilizing soils1 occurs exclusively1 according to ,mr4 ,r4 ,a4 ,c4 ,austen1 in the upper greensand and gault4 ,it is doubtless of animal origin1 and partly coprolitic1 probably derived from the excrement of fish4 ,,lower ,,cretaceous ,,division4 7,no4 #f4 ,tab4 p4 #bji47 ,that part of the ,cretaceous series which is older than the ,gault has been commonly called the ,lower ,greensand4 ,the greater number of its fossils are specifically distinct from those of the upper cretaceous system4 ,dr4 ,fitton1 to whom we are indebted for an excellent monograph on this formation as developed in ,england1 gives the following as the succession of rocks seen in parts of ,kent4 ,no4 #a4 ,sand1 white1 yellowish1 or ferruginous1 with concretions of limestone and chert #gj feet4 #b4 ,sand with green matter #gj to #ajj feet4 #c4 ,calcareous stone1 called ,kentish rag #fj to #hj feet4 ,in his detailed description of the fine section displayed at ,atherfield1 in the south of the ,isle of ,wight1 we find the limestone wholly wanting2 in fact1 the variations in the mineral composition of this group1 even in contiguous districts1 is very great2 and on comparing the ,atherfield beds with corresponding strata at ,hythe in ,kent1 distant #ie miles1 the whole series has lost half its thickness1 and presents a very dissimilar aspect4#bai-;,a ,on the other hand1 ,professor ,e4 ,forbes has shown that when the sixty-three strata at ,atherfield are severally examined1 the total thickness of which he gives as #hdc feet1 there are some fossils which range through the whole series1 others which are peculiar to particular divisions4 ,as a proof that all belong chronologically to one system1 he states that whenever similar conditions are repeated in overlying strata the same species reappear4 ,changes of depth1 or of the mineral nature of the bottom1 the presence or absence of lime or of peroxide of iron1 the occurrence of a muddy1 or a sandy1 or a gravelly bottom1 are marked by the banishment of certain species and the predominance of others4 ,but these differences of conditions being mineral1 chemical1 and local in their nature1 have nothing to do with the extinction1 throughout a large area1 of certain animals or plants4 ,the rule laid down by this eminent naturalist for enabling us to test the arrival of a new state of things in the animate world1 is the representation by new and different species of corresponding genera of mollusca or other beings4 ,when the forms proper to loose sand or soft clay1 or a stony or calcareous bottom1 or a moderate or a great depth of water1 recur with all the same species1 the interval of time has been1 geologically speaking1 small1 however dense the mass of matter accumulated4 ,but if1 the genera remaining the same1 the species are changed1 we have entered upon a new period2 and no similarity of climate1 or of geographical and local conditions1 can then recall the old species which a long series of destructive causes in the animate and inanimate world has gradually annihilated4 ,on passing from the lower greensand to the gault1 we suddenly reach one of these new epochs1 scarcely any of the fossil species being common to the lower and upper cretaceous systems1 a break in the chain implying no doubt many missing links in the series of geological monuments which we may some day be able to supply4 ,one of the largest and most abundant shells in the lowest strata of the lower greensand1 as displayed in the ,atherfield section1 is the large ,perna mulleti of which a reduced figure is here given 7fig4 #bbb474 ,illustration3 ,fig4 #bbb4 ,perna mulleti4 ,desh4 in ,leym4 a4 ,exterior4 b4 ,hinge of upper valve4 ,in the south of ,england1 during the accumulation of the lower greensand above described1 the bed of the sea appears to have been continually sinking1 from the commencement of the period1 when the freshwater ,wealden beds were submerged1 to the deposition of those strata on which the gault immediately reposes4 ,pebbles of quartzose sandstone1 jasper1 and flinty slate1 together with grains of chlorite and mica1 speak plainly of the nature of the pre-existing rocks1 from the wearing down of which the greensand beds were derived4 ,the land1 consisting of such rocks1 was doubtless submerged before the origin of the white chalk1 as corals can only multiply in the clear waters of the sea in spaces to which no mud or sand are conveyed by currents4 ,,hippurite ,,limestone4 ,difference between the chalk of the north and south of ,europe4--,by the aid of the three tests of relative age1 namely1 superposition1 mineral character1 and fossils1 the geologist has been enabled to refer to the same ,cretaceous period certain rocks in the north and south of ,europe1 which differ greatly1 both in their fossil contents and in their mineral composition and structure4 ,if we attempt to trace the cretaceous deposits from ,england and ,france to the countries bordering the ,mediterranean1 we perceive1 in the first place1 that the chalk and ,greensand in the neighbourhood of ,london and ,paris form one great continuous mass1 the ,straits of ,dover being a trifling interruption1 a mere valley with chalk cliffs on both sides4 ,we then observe that the main body of the chalk which surrounds ,paris stretches from ,tours to near ,poitiers 7see the annexed map1 fig4 #bbc41 in which the shaded part represents chalk74 ,illustration3 ,fig4 #bbc4 ,map of south-western ,france4 ,between ,poitiers and ,la ,rochelle1 the space marked ,a on the map separates two regions of chalk4 ,this space is occupied by the ,oolite and certain other formations older than the ,chalk1 and has been supposed by ,m4 ,e4 de ,beaumont to have formed an island in the cretaceous sea4 ,south of this space we again meet with a formation which we at once recognize by its mineral character to be chalk1 although there are some places where the rock becomes oolitic4 ,the fossils are1 upon the whole1 very similar2 especially certain species of the genera ,spatangus1 ,ananchytes1 ,cidarites1 ,nucula1 ,ostrea1 ,gryphaea 7,exogyra71 ,pecten1 ,plagiostoma 7,lima71 ,trigonia1 ,catillus1 7,inoceramus71 and ,terebratula4#bba-;,a ,but ,ammonites1 as ,m4 d',archiac observes1 of which so many species are met with in the chalk of the north of ,france1 are scarcely ever found in the southern region2 while the genera ,hamite1 ,turrilite1 and ,scaphite1 and perhaps ,belemnite1 are entirely wanting4 ,on the other hand1 certain forms are common in the south which are rare or wholly unknown in the north of ,france4 ,among these may be mentioned many ,hippurites1 ,sphaerulites1 and other members of that great family of mollusca called ,rudistes by ,lamarck1 to which nothing analogous has been discovered in the living creation1 but which is quite characteristic of rocks of the ,cretaceous era in the south of ,france1 ,spain1 ,sicily1 ,greece1 and other countries bordering the ,mediterranean4 ,illustration3 ,fig4 #bbd4 a4 ,radiolites radiosus1 ,d',orb4 7,hippurites1 ,lamk47 b4 ,opercular valve of same4 ,white chalk of ,france4 ,illustration3 ,fig4 #bbe4 ,radiolites foliaceus1 ,d',orb4 ,syn4 ,sphaerulites agariciformis1 ,blainv4 ,white chalk of ,france4 ,illustration3 ,fig4 #bbf4 ,hippurites organisans1 ,desmoulins4 ,upper chalk3--chalk marl of ,pyrenees8#bbb-;,a a4 ,young individual2 when full grown they occur in groups adhering laterally to each other4 b4 ,upper side of the opercular valve1 showing a reticulated structure in those parts1 b1 where the external coating is worn off4 c4 ,upper side of the lower and cylindrical valve4 d4 ,cast of the interior of the lower conical valve4 ,the species called ,hippurites organisans 7fig4 #bbf47 is more abundant than any other in the south of ,europe2 and the geologist should make himself well acquainted with the cast d1 which is far more common in many compact marbles of the upper cretaceous period than the shell itself1 which has often wholly disappeared4 ,the flutings1 or smooth1 rounded1 longitudinal ribs1 representing the form of the interior1 are wholly unlike the hippurite itself1 and in some individuals1 which attain a great size and length1 are very conspicuous4 ,between the region of chalk last mentioned in which ,perigueux is situated1 and the ,pyrenees1 the space ,b intervenes4 7,see ,map1 p4 #bba47 ,here the tertiary strata cover1 and for the most part conceal1 the cretaceous rocks1 except in some spots where they have been laid open by the denudation of newer formations4 ,in these places they are seen still preserving the form of a white chalky rock1 which is charged in part with grains of green sand4 ,even as far south as ,tercis1 on the ,adour1 near ,dax1 where ,i examined them in #ahbh1 the cretaceous rocks retain this character4 ,in that region ,m4 ,grateloup has found in them ,ananchytes ovata 7fig4 #bab471 and other fossils of the ,english chalk1 together with ,hippurites4 ,,flora ,,of ,,the ,,cretaceous ,,period4 ,although the fossil plants of the ,cretaceous era at present known are few in number1 the rocks being principally marine1 they suffice1 according to ,m4 ,ad4 ,brongniart1 to show a transition character between the vegetation of the secondary and that of the tertiary formations4 ,the tertiary strata1 when compared to the older rocks1 are marked by the predominance of ,exogens1 which now constitute three-fourths of the living plants of the globe4#bbc-;,a ,these exogens are wanting in the secondary strata generally1 but in the ,cretaceous period they equal in number the ,gymnogens 7,coniferae and ,cycadeae7 which abounded so much in the preceding ,oolitic period1 and disappeared before the ,eocene rocks were formed4#bbc-;,b ,the discovery of a tree-fern in the ferruginous sands of the ,lower ,cretaceous group of the department of ,ardennes in ,france is one of many signs of the contrast of the flora1 and doubtless of the climate1 of this era with that of the ,pliocene and ,modern periods4 ,,cretaceous ,,rocks ,,in ,,the ,,united ,,states4 ,if we pass to the ,american continent1 we find in the state of ,new ,jersey a series of sandy and argillaceous beds wholly unlike our ,upper ,cretaceous system2 which we can1 nevertheless1 recognize as referable1 paleontologically1 to the same division4 ,that they were about the same age generally as the ,european chalk and greensand1 was the conclusion to which ,dr4 ,morton and ,mr4 ,conrad came after their investigation of the fossils in #ahcd4 ,the strata consist chiefly of greensand and green marl1 with an overlying coralline limestone of a pale yellow colour1 and the fossils1 on the whole1 agree most nearly with those of the upper ,european series1 from the ,maestricht beds to the gault inclusive4 ,i collected sixty shells from the ,new ,jersey deposits in #ahda2 five of which were identical with ,european species--,ostrea larva1 ,o4 vesicularis1 ,gryphaea costata1 ,pecten quinque-costatus1 ,belemnites mucronatus4 ,as some of these have the greatest vertical range in ,europe1 they might be expected more than any others to recur in distant parts of the globe4 ,even where the species are different1 the generic forms1 such as the ,baculite and certain sections of ,ammonites1 as also the ,inoceramus 7see above1 fig4 #bjh47 and other bivalves1 have a decidedly cretaceous aspect4 ,fifteen out of the sixty shells above alluded to1 were regarded by ,professor ,forbes as good geographical representatives of well-known cretaceous fossils of ,europe4 ,the correspondence1 therefore1 is not small1 when we reflect that the part of the ,united ,states where these strata occur is between #cjjj and #djjj miles distant from the chalk of ,central and ,northern ,europe1 and that there is a difference of ten degrees in the latitude of the places compared on opposite sides of the ,atlantic4#bbd-;,a ,fish of the genera ,lamna1 ,galeus1 and ,carcharias are common to ,new ,jersey and the ,european cretaceous rocks4 ,so also is the genus ,mosasaurus among reptiles1 and ,pliosaurus 7,owen71 another saurian likewise obtained from the ,english chalk4 ,from ,new ,jersey the cretaceous formation extends southwards to ,north ,carolina1 ,georgia1 and ,alabama1 cropping out at intervals from beneath the tertiary strata1 between the ,appalachian ,mountains and the ,atlantic4 ,they then sweep round the southern extremity of that chain1 and stretch northwards again to ,tennessee and ,kentucky4 ,they have also been traced far up the valley of the ,missouri #bge ,english miles above its mouth1 to the neighbourhood of ,fort ,leavenworth2 and southwards to ,texas1 according to the observations of ,ferdinand ,roemer2 so that already the area which they are ascertained to occupy in ,north ,america may perhaps equal their extent in ,europe4 ,so little do they resemble mineralogically the ,european white chalk1 that limestone in ,north ,america is1 upon the whole1 an exception to the rule2 and1 even in ,alabama1 where ,i saw a calcareous member of this group1 the marlstones are much more like the ,english and ,french ,lias than any other secondary deposit of the ,old ,world4 ,at the base of the system in ,alabama ,i found dense masses of shingle1 perfectly loose and unconsolidated1 derived from the waste of paleozoic 7or carboniferous7 rocks1 a mass in no way distinguishable1 except by its position1 from ordinary alluvium1 but covered with marls abounding in ,inocerami4 ,in ,texas1 according to ,f4 ,roemer1 the chalk assumes a new lithological type1 a large portion of it consisting of hard siliceous limestone1 but the organic remains leaving no doubt in regard to its age4 ,in ,south ,america the cretaceous strata have been discovered in ,columbia1 as at ,bogota and elsewhere1 containing ,ammonites1 ,hamites1 ,inocerami1 and other characteristic shells4#bbe-;,a ,in the ,south of ,india1 also1 at ,pondicherry1 ,verdachellum1 and ,trinconopoly1 ,messrs4 ,kaye and ,egerton have collected fossils belonging to the cretaceous system4 ,taken in connection with those from the ,united ,states they prove1 says ,prof4 ,e4 ,forbes1 that those powerful causes which stamped a peculiar character on the forms of marine animal life at this period1 exerted their full intensity through the ,indian1 ,european1 and ,american seas4#bbe-;,b ,here1 as in ,north and ,south ,america1 the cretaceous character can be recognized even where there is no specific identity in the fossils2 and the same may be said of the organic type of those rocks in ,europe and ,india which succeed next in the ascending and descending order1 the ,eocene and the ,oolitic4 ,,footnotes3 #bji-;,a ,m4 ,alcide d',orbigny1 in his valuable work entitled ,paleontologie ,francaise1 has adopted new terms for the ,french subdivisions of the ,cretaceous ,series1 which1 so far as they can be made to tally with ,english equivalents1 seem explicable thus3 ,danien4 ,maestricht beds4 ,senonien4 ,upper and lower white chalk1 and chalk marl4 ,turonien4 ,part of the chalk marl and the upper greensand1 the latter being in his last work 7,cours ,elementaire7 termed ,cenomanien4 ,albien4 ,gault4 ,aptien4 ,upper part of lower greensand4 ,neocomien4 ,lower part of same4 #baa-;,a ,see paper by the author1 ,trans4 of ,geol4 ,soc41 vol4 v4 p4 #bdf41 #ahdj4 #baa-;,b ,fitton1 ,geol4 ,trans41 #b;d series1 vol4 iv4 p4 #cai4 #bae-;,a ,proceedings of ,geol4 ,soc41 vol4 iii4 pp4 #g1 #h41 #ahdb4 #baf-;,a ,geol4 ,trans4 ,second ,series1 vol4 iii4 p4 #bcb4 plate #ca4 figs4 #c4 and #aa4 #baf-;,b ,geol4 of ,u4 ,s4 ,exploring ,exped4 p4 #beb4 #ahdi4 #bag-;,a ,see ,chapters ,x4 and ,,xi4 #bag-;,b ,darwin1 p4 #edi4 ,kotzebue's ,first ,voyage1 vol4 iii4 p4 #aee4 #bag-;,c ,mantell1 ,geol4 of ,s4 ,e4 of ,england1 p4 #if4 #bai-;,a ,dr4 ,fitton1 ,quart4 ,geol4 ,journ41 vol4 i4 p4 #agi41 ii4 p4 #ee41 and iii4 p4 #bhi41 where comparative sections and a valuable table showing the vertical range of the various fossils of the lower greensand at ,atherfield is given4 #bba-;,a ,archiac1 sur la ,form4 ,cretacee du ,s4 ,o4 de la ,france1 ,mem4 de la ,soc4 ,geol4 de ,france1 tom4 ii4 #bbb-;,a ,d',orbigny's ,paleontologie ,francaise1 pl4 #ecc4 #bbc-;,a ,in this and subsequent remarks on fossil plants ,i shall often use ,dr4 ,lindley's terms1 as most familiar in this country2 but as those of ,m4 ,a4 ,brongniart are much cited1 it may be useful to geologists to give a table explaining the corresponding names of groups so much spoken of in palaeontology4 ,brongniart4 ,lindley4 ,examples4 ,cryptogamic4 #a4 ,cryptogamous amphigens1 or cellular cryptogamic4 ,thallogens4 ,lichens1 sea-weeds1 fungi4 #b4 ,cryptogamous acrogens4 ,acrogens4 ,mosses1 equisetums1 ferns1 lycopodiums--,lepidodendron4 ,phanerogamic4 #c4 ,dicotyledonous gymnosperms4 ,gymnogens4 ,conifers and ,cycads4 #d4 ,dicot4 ,angiosperms4 ,exogens4 ,compositae1 leguminosae1 umbelliferae1 cruciferae1 heaths1 c4 ,all native ,european trees except conifers4 #e4 ,monocotyledons4 ,endogens4 ,palms1 lilies1 aloes1 rushes1 grasses1 c4 #bbc-;,b ,a4 ,brongniart1 ,veget4 ,foss4 ,dict4 ,univ41 p4 #aaa41 #ahdi4 #bbd-;,a ,see a paper by the author1 ,quart4 ,journ4 ,geol4 ,soc41 vol4 i4 p4 #ee4 #bbe-;,a ,proceed4 ,geol4 ,soc4 iv4 p4 #cia4 #bbe-;,b ,see ,forbes1 ,quart4 ,geol4 ,journ4 vol4 i4 p4 #gi4 ,,chapter ,,xviii4 ,,wealden ,,group4 ,the ,wealden divisible into ,weald ,clay1 ,hastings ,sand1 and ,purbeck ,beds--,intercalated between two marine formations--,weald clay and ,cypris-bearing strata--,iguanodon--,hastings sands--,fossil fish--,strata formed in shallow water--,brackish water-beds--,upper1 middle1 and lower ,purbeck--,alternations of brackish water1 freshwater1 and land--,dirt-bed1 or ancient soil--,distinct species of fossils in each subdivision of the ,wealden--,lapse of time implied--,plants and insects of ,wealden--,geographical extent of ,wealden--,its relation to the cretaceous and oolitic periods--,movements in the earth's crust to which it owed its origin and submergence4 ,beneath the cretaceous rocks in the ,s4,e4 of ,england1 a freshwater formation is found1 called the ,wealden 7see ,nos4 #e4 and #f4 ,map1 p4 #bdb471 which1 although it occupies a small horizontal area in ,europe1 as compared to the chalk1 is nevertheless of great geological interest1 not only from its position1 as being interpolated between two great marine formations 7,nos4 #g4 and #i4 ,table1 p4 #ajc471 but also because the imbedded fossils indicate a grand succession of changes in organic life1 effected during its accumulation4 ,it is composed of three minor divisions1 the ,weald ,clay1 the ,hastings1 and the ,purbeck ,beds1 of which the aggregate thickness in some districts may be #gjj or #hjj feet2 but which would be much more considerable 7perhaps #bjjj feet71 were we to add together the extreme thickness acquired by each of them in their fullest development4 ,the common name of ,wealden was given to the whole1 because it was first studied in parts of ,kent1 ,surrey1 and ,sussex1 called the ,weald1 7see ,map1 p4 #bdb471 and we are indebted to ,dr4 ,mantell for having shown in #ahbb1 in his ,geology of ,sussex1 that the whole group was of fluviatile origin4 ,in proof of this he called attention to the entire absence of ,ammonites1 ,belemnites1 ,terebratulae1 ,echinites1 ,corals1 and other marine fossils1 so characteristic of the cretaceous rocks above1 and of the ,oolitic strata below1 and to the presence of ,paludinae1 ,melaniae1 and various fluviatile shells1 as well as the bones of terrestrial reptiles and the trunks and leaves of land plants4 ,illustration3 ,fig4 #bbg4 ,position of the ,wealden between two marine formations4 ,the evidence of so unexpected a fact as the infra-position of a dense mass of purely freshwater origin to a deep-sea deposit 7a phenomenon with which we have since become familiar1 in other chapters of the earth's autobiography71 was received1 at first1 with no small doubt and incredulity4 ,but the relative position of the beds is unequivocal2 the ,weald ,clay being distinctly seen to pass beneath the ,greensand in various parts of ,surrey1 ,kent1 and ,sussex2 and if we proceed from ,sussex westward to the ,vale of ,wardour1 we there again observe the same formation1 or1 at least1 the lower division of it1 the ,purbeck1 occupying the same relative position1 and resting on the ,oolite 7see fig4 #bbh474 ,or if we pass from the base of the ,south ,downs in ,sussex1 and cross to the ,isle of ,wight1 we there again meet with the ,wealden series reappearing beneath the ,greensand1 and cannot doubt that the beds are prolonged subterraneously1 as indicated by the dotted lines in fig4 #bbi4 ,illustration3 ,fig4 #bbh4 ,cross section4 ,o1 ,oolite4 ,g ,s1 ,greensand1 or ,lower ,cretaceous4 ,illustration3 ,fig4 #bbi4 ,cross section4 ,the minor groups into which the ,wealden has been commonly divided in ,england are1 as before stated1 three1 and they succeed each other in the following descending order#bbg-;,a3-- ,thickness4 #ast4 ,weald ,clay1 sometimes including thin beds of sand and shelly limestone #adj to #bhj ft4 #b;d4 ,hastings ,sand1 in which occur some clays and calcareous grits #djj to #ejj ft4 #c;d4 ,purbeck ,beds1 consisting of various kinds of limestones and marls #aej to #bjj ft4 ,weald ,clay4 ,the first division1 or ,weald ,clay1 is of purely freshwater origin4 ,the uppermost beds are not only conformable1 as ,dr4 ,fitton observes1 to the inferior strata of the ,lower ,greensand1 but of similar mineral composition4 ,to explain this1 we may suppose1 that as the delta of a great river was tranquilly subsiding1 so as to allow the sea to encroach upon the space previously occupied by freshwater1 the river still continued to carry down the same sediment into the sea4 ,in confirmation of this view it may be stated1 that the remains of the ,iguanodon ,mantelli1 a gigantic terrestrial reptile1 very characteristic of the ,wealden1 has been discovered near ,maidstone1 in the overlying ,kentish rag1 or marine limestone of the ,lower ,greensand4 ,hence we may infer that some of the saurians which inhabited the country of the great river continued to live when part of the country had become submerged beneath the sea4 ,thus1 in our own times1 we may suppose the bones of large alligators to be frequently entombed in recent freshwater strata in the delta of the ,ganges4 ,but if part of that delta should sink down so as to be covered by the sea1 marine formations might begin to accumulate in the same space where freshwater beds had previously been formed2 and yet the ,ganges might still pour down its turbid waters in the same direction1 and carry seaward the carcasses of the same species of alligator1 in which case their bones might be included in marine as well as in subjacent freshwater strata4 ,the ,iguanodon1 first discovered by ,dr4 ,mantell1 has left more of its remains in the ,wealden strata of the south-eastern counties1 and ,isle of ,wight1 than any other genus of associated saurians4 ,it was an herbivorous reptile1 and regarded by ,cuvier as more extraordinary than any with which he was acquainted2 for the teeth1 though bearing a great analogy to the modern ,iguanas which now frequent the tropical woods of ,america and the ,west ,indies1 exhibit many striking and important differences 7see fig4 #bcj474 ,it appears that they have been worn by mastication2 whereas the existing herbivorous reptiles clip and gnaw off the vegetable productions on which they feed1 but do not chew them4 ,their teeth1 when worn1 present an appearance of having been chipped off1 and never1 like the fossil teeth of the ,iguanodon1 have a flat ground surface 7see fig4 #bca471 resembling the grinders of herbivorous mammalia4 ,dr4 ,mantell computes that the teeth and bones of this animal which have passed under his examination during the last twenty years1 must have belonged to no less than seventy-one distinct individuals2 varying in age and magnitude from the reptile just burst from the egg1 to one of which the femur measured #bd inches in circumference4 ,yet notwithstanding that the teeth were more numerous than any other bones1 it is remarkable that it was not till the relics of all these individuals had been found1 that a solitary example of part of a jaw-bone was obtained4 ,more recently remains both of the upper and lower jaw have been met with in the ,hastings ,beds in ,tilgate ,forest4 ,their size was somewhat greater than had been anticipated1 and even allowing that the tail was short1 which ,professor ,owen infers from the short bodies of the caudal vertebrae1 ,dr4 ,mantell estimates the probable length of some of these saurians at between #cj and #dj feet4 ,the largest femur yet found measures #d feet #h inches in length1 the circumference of the shaft being #be inches1 and round the condyles #db inches4 #b ,illustrations3 ,teeth of ,iguanodon4 ,fig4 #bcj4 ,partially worn tooth of a young animal4 7,mantell47 ,fig4 #bca4 ,crown of tooth in adult1 worn down4 7,mantell47 ,occasionally bands of limestone1 called ,sussex ,marble1 occur in the ,weald ,clay1 almost entirely composed of a species of ,paludina1 closely resembling the common ,p4 vivipara of ,english rivers4 ,illustration3 ,fig4 #bcb4 ,cypris spinigera1 ,fitton4 ,illustration3 ,fig4 #bcc4 ,cypris ,valdensis1 ,fitton4 7,c4 faba1 ,min4 ,con4 #dhe47 ,illustration3 ,fig4 #bcd4 ,cypris tuberculata1 ,fitton4 ,illustration3 ,fig4 #bce4 ,sample with lamination4 ,shells of the ,cypris1 an animal belonging to the ,crustacea1 and before mentioned 7p4 #ca47 as abounding in lakes and ponds1 are also plentifully scattered through the clays of the ,wealden1 sometimes producing1 like the plates of mica1 a thin lamination 7see fig4 #bce474 ,similar cypriferous marls are found in the lacustrine tertiary beds of ,auvergne 7see above1 p4 #ahc474 ,hastings ,sands4 ,this middle division of the ,wealden consists of sand1 calciferous grit1 clay1 and shale2 the argillaceous strata1 notwithstanding the name1 being nearly in the same proportion as the arenaceous4 ,the calcareous sandstone and grit of ,tilgate ,forest1 near ,cuckfield1 in which the remains of the ,iguanodon and ,hyleosaurus were first found1 constitute an upper member of this formation4 ,the white sand-rock of the ,hastings cliffs1 about #ajj feet thick1 is one of the lower members of the same4 ,the reptiles1 which are very abundant in it1 consist partly of saurians1 already referred by ,owen and ,mantell to eight genera1 among which1 besides those already enumerated1 we find the ,megalosaurus and ,plesiosaurus4 ,the ,pterodactyl1 also a flying reptile1 is met with in the same strata1 and many remains of ,testudinata of the genera ,trionyx and ,emys1 now confined to tropical regions4 ,illustration3 ,fig4 #bcf4 ,lepidotus ,mantelli1 ,agass4 ,wealden4 a4 palate and teeth4 b4 side view of teeth4 c4 scale4 ,the fishes of the ,wealden belong partly to the genera ,pycnodus and ,hybodus 7see figure of genus in ,chap4 ,,xxi471 forms common to the ,wealden and ,oolite2 but the teeth and scales of a species of ,lepidotus are most widely diffused 7see fig4 #bcf474 ,the general form of these fish was that of the carp tribe1 although perfectly distinct in anatomical character1 and more allied to the pike4 ,the whole body was covered with large rhomboidal scales1 very thick1 and having the exposed part covered with enamel4 ,most of the species of this genus are supposed to have been either river fish1 or inhabitants of the coasts1 having not sufficient powers of swimming to advance into the deep sea4 ,illustration3 ,fig4 #bcg4 ,corbula alata1 ,fitton4 ,magnified4 ,the shells of the ,hastings beds belong to the genera ,melanopsis1 ,melania1 ,paludina1 ,cyrena1 ,cyclas1 ,unio1 and others1 which inhabit rivers or lakes2 but one band has been found in ,dorsetshire indicating a brackish state of the water1 and1 in some places1 even a saltness1 like that of the sea1 where the genera ,corbula 7see fig4 #bcg471 ,mytilus1 and ,ostrea occur4 ,at different heights in the ,hastings ,sand1 in the middle of the ,wealden1 we find again and again slabs of sandstone with a strong ripple-mark1 and between these slabs beds of clay many yards thick4 ,in some places1 as at ,stammerham1 near ,horsham1 there are indications of this clay having been exposed so as to dry and crack before the next layer was thrown down upon it4 ,the open cracks in the clay have served as moulds1 of which casts have been taken in relief1 and which are1 therefore1 seen on the lower surface of the sandstone 7see fig4 #bch474 ,illustration3 ,fig4 #bch4 ,underside of slab of sandstone about one yard in diameter4 ,stammerham1 ,sussex4 ,near the same place a reddish sandstone occurs in which are innumerable traces of a fossil vegetable1 apparently ,sphenopteris1 the stems and branches of which are disposed as if the plants were standing erect on the spot where they originally grew1 the sand having been gently deposited upon and around them2 and similar appearances have been remarked in other places in this formation4#bcj-;,a ,in the same division also of the ,wealden1 at ,cuckfield1 is a bed of gravel or conglomerate1 consisting of water-worn pebbles of quartz and jasper1 with rolled bones of reptiles4 ,these must have been drifted by a current1 probably in water of no great depth4 ,illustration3 ,fig4 #bci4 ,sphenopteris gracilis 7,fitton71 from near ,tunbridge ,wells4 a4 portion of the same magnified4 ,from such facts we may infer that1 notwithstanding the great thickness of this division of the ,wealden 7and the same observation applies to the ,weald ,clay and ,purbeck ,beds71 the whole of it was a deposit in water of a moderate depth1 and often extremely shallow4 ,this idea may seem startling at first1 yet such would be the natural consequence of a gradual and continuous sinking of the ground in an estuary or bay1 into which a great river discharged its turbid waters4 ,by each foot of subsidence1 the fundamental rock1 such as the ,portland ,oolite1 would be depressed one foot farther from the surface2 but the bay would not be deepened1 if newly deposited mud and sand should raise the bottom one foot4 ,on the contrary1 such new strata of sand and mud might be frequently laid dry at low water1 or overgrown for a season by a vegetation proper to marshes4 ,purbeck ,beds4 ,immediately below the ,hastings ,sands we find a series of calcareous slates1 marls1 and limestones1 called the ,purbeck ,beds1 because well exposed to view in the sea-cliffs of the ,peninsula of ,purbeck1 especially in ,durlestone ,bay1 near ,swanage4 ,they may also be advantageously studied at ,lulworth ,cove and the neighbouring bays between ,weymouth and ,dorchester4 ,at ,meup's ,bay in particular1 ,prof4 ,e4 ,forbes has recently examined minutely the organic remains of the three members of the ,purbeck group1 displayed there in a vertical section #aee feet thick4 ,to the information previously supplied in the works of ,messrs4 ,webster1 ,fitton1 ,de la ,beche1 ,buckland1 and ,mantell1 he has made most ample and important additions1 so that it will be desirable to give them at some length1 it appearing that the ,upper1 ,middle1 and ,lower ,purbecks are each marked by peculiar species of organic remains1 these again being different1 so far as a comparison has yet been instituted1 from the fossils of the overlying ,hastings ,sands and ,weald ,clay4 ,this result cannot fail to excite much wonder1 and it leads us to suspect that the ,wealden period1 which many geologists have scarcely deigned to notice in their classification1 may comprehend the history of a lapse of time as great as that of the ,oolitic or ,cretaceous eras respectively4#bca-;,a ,upper ,purbeck4--,the highest of the three divisions is purely freshwater1 the strata1 about #ej feet in thickness1 containing shells of the genera ,paludina1 ,physa1 ,lymnea1 ,planorbis1 ,valvata1 ,cyclas1 and ,unio1 with cyprides1 and fish4 ,middle ,purbeck4--,to these succeed the ,middle ,purbeck1 about #cj feet thick1 the uppermost part of which consists of freshwater limestone1 with cyprides1 turtles1 and fish of different species from those in the preceding strata4 ,below the limestone are brackish-water beds full of ,cyrena1 and traversed by bands abounding in ,corvulae and ,melaniae4 ,these are based on a purely marine deposit1 with ,pecten1 ,modiola1 ,avicula1 and ,thracia1 all undescribed shells4 ,below this1 again1 come limestones and shales1 partly of brackish and partly of freshwater origin1 in which many fish1 especially species of ,lepidotus and ,microdon radiatus1 are found1 and a reptile named ,macrorhyncus4 ,among the mollusks1 a remarkable ribbed ,melania1 of the section ,chilira1 occurs4 ,immediately below is the great and conspicuous stratum1 #ab feet thick1 long familiar to geologists under the local name of ,cinder-bed1 formed of a vast accumulation of shells of ,ostrea distorta 7fig4 #bdj474 ,in the uppermost part of this bed ,mr4 ,forbes discovered the first echinoderm as yet known in the ,purbeck series1 a species of ,hemicidaris1 a genus characteristic of the ,oolitic period4 ,it was accompanied by a species of ,perna4 ,below the ,cinder-bed freshwater strata are again seen1 filled in many places with species of ,cypris1 ,valvata1 ,paludina1 ,planorbis1 ,lymnea1 ,physa1 and ,cyclas1 all different from any we had previously seen above4 ,thick siliceous beds of chert1 filled with these fossils1 occur in a beautiful state of preservation1 often converted into chalcedony4 ,among these ,mr4 ,forbes met with gyrogonites 7the spore vesicles of ,charae71 plants never before discovered in rocks older than the ,eocene4 ,again1 beneath these freshwater strata1 a very thin band of greenish shales1 with marine shells and impressions of leaves1 like those of a large ,zostera1 succeeds1 forming the base of the ,middle ,purbeck4 ,illustration3 ,fig4 #bdj4 ,ostrea distorta4 ,cinder-bed4 ,lower ,purbeck4--,beneath the thin marine band last mentioned1 purely freshwater marls occur1 containing species of ,cypris1 ,valvata1 and ,lymnea1 different from those of the ,middle ,purbeck4 ,this is the beginning of the ,inferior division1 which is about #hj feet thick4 ,below the marls are seen more than #cj feet of brackish-water beds1 at ,meup's ,bay1 abounding in a species of ,serpula1 allied to1 if not identical with1 ,serpula coacervites1 found in the ,wealden of ,hanover4 ,there are also shells of the genus ,rissoa 7of the subgenus ,hydrobia71 and a little ,cardium of the subgenus ,protocardium1 in the same beds1 together with ,cypris4 ,some of the cypris-bearing shales are strangely contorted and broken up1 at the west end of the ,isle of ,purbeck4 ,the great dirt-bed or vegetable soil containing the roots and stools of ,cycadeae1 which ,i shall presently describe1 underlies these marls1 resting upon the lowest freshwater limestone1 a rock about #h feet thick1 containing ,cyclades1 ,valvata1 and ,lymnea1 of the same species as those of the uppermost part of the ,lower ,purbeck4 ,this rock rests upon the top beds of the ,portland stone1 which is purely marine1 and between which and the ,purbecks there is no passage4 ,the most remarkable of all the varied successions of beds enumerated in the above list1 is that called by the quarrymen the dirt1 or black dirt1 which was evidently an ancient vegetable soil4 ,it is from #ab to #ah inches thick1 is of a dark brown or black colour1 and contains a large proportion of earthy lignite4 ,through it are dispersed rounded fragments of stone1 from #c to #i inches in diameter1 in such numbers that it almost deserves the name of gravel4 ,many silicified trunks of coniferous trees1 and the remains of plants allied to ,zamia and ,cycas1 are buried in this dirt-bed 7see figure of living ,zamia1 fig4 #bda474 ,these plants must have become fossil on the spots where they grew4 ,the stumps of the trees stand erect for a height of from #a to #c feet1 and even in one instance to #f feet1 with their roots attached to the soil at about the same distances from one another as the trees in a modern forest4#bcc-;,a ,the carbonaceous matter is most abundant immediately around the stumps1 and round the remains of fossil ,cycadeae4#bcc-;,b ,illustration3 ,fig4 #bda4 ,zamia spiralis2 ,southern ,australia4#bcc-;,c ,besides the upright stumps above mentioned1 the dirt-bed contains the stems of silicified trees laid prostrate4 ,these are partly sunk into the black earth1 and partly enveloped by a calcareous slate which covers the dirt-bed4 ,the fragments of the prostrate trees are rarely more than #c or #d feet in length2 but by joining many of them together1 trunks have been restored1 having a length from the root to the branches of from #bj to #bc feet1 the stems being undivided for #ag or #bj feet1 and then forked4 ,the diameter of these near the roots is about #a foot4#bcc-;,d ,root-shaped cavities were observed by ,professor ,henslow to descend from the bottom of the dirt-bed into the subjacent freshwater stone1 which1 though now solid1 must have been in a soft and penetrable state when the trees grew4#bcc-;,e ,illustration3 ,fig4 #bdb4 ,section in ,isle of ,portland1 ,dorset4 7,buckland and ,de la ,beche47 ,the thin layers of calcareous slate 7fig4 #bdb47 were evidently deposited tranquilly1 and would have been horizontal but for the protrusion of the stumps of the trees1 around the top of each of which they form hemispherical concretions4 ,the dirt-bed is by no means confined to the island of ,portland1 where it has been most carefully studied1 but is seen in the same relative position in the cliffs east of ,lulworth ,cove1 in ,dorsetshire1 where1 as the strata have been disturbed1 and are now inclined at an angle of #de deg41 the stumps of the trees are also inclined at the same angle in an opposite direction--a beautiful illustration of a change in the position of beds originally horizontal 7see fig4 #bdc474 ,traces of the dirt-bed have also been observed by ,dr4 ,buckland1 about two miles north of ,thame1 in ,oxfordshire2 and by ,dr4 ,fitton1 in the cliffs of the ,boulonnois1 on the ,french coast2 but1 as might be expected1 this freshwater deposit is of limited extent when compared to most marine formations4 ,illustration3 ,fig4 #bdc4 ,section in cliff east of ,lulworth ,cove4 7,buckland and ,de la ,beche47 ,from the facts above described1 we may infer1 first1 that the superior beds of the ,oolite1 called the ,portland1 which are full of marine shells1 were overspread with fluviatile mud1 which became dry land1 and covered by a forest1 throughout a portion of the space now occupied by the south of ,england1 the climate being such as to admit the growth of the ,zamia and ,cycas4 #b;dly4 ,this land at length sank down and was submerged with its forests beneath a body of fresh water1 from which sediment was thrown down enveloping fluviatile shells4 #c;dly4 ,the regular and uniform preservation of this thin bed of black earth over a distance of many miles1 shows that the change from dry land to the state of a freshwater lake or estuary1 was not accompanied by any violent denudation1 or rush of water1 since the loose black earth1 together with the trees which lay prostrate on its surface1 must inevitably have been swept away had any such violent catastrophe then taken place4 ,the dirt-bed has been described above in its most simple form1 but in some sections the appearances are more complicated4 ,the forest of the dirt-bed was not everywhere the first vegetation which grew in this region4 ,two other beds of carbonaceous clay1 one of them containing ,cycadeae1 in an upright position1 have been found below it1 and one above it#bcd-;,a1 which implies other oscillations in the level of the same ground1 and its alternate occupation by land and water more than once4 ,table showing the changes of medium in which the strata were formed1 from the ,lower ,greensand to the ,portland ,stone inclusive1 in the south-east of ,england4 #a4 ,marine ,lower greensand4 #b4 ,freshwater ,weald clay4 #c4 ,freshwater ,brackish ,hastings sand4 ,freshwater #d4 ,freshwater ,upper ,purbeck4 #e4 ,freshwater ,brackish ,marine ,brackish ,middle ,purbeck4 ,marine ,freshwater ,marine #f4 ,freshwater ,brackish ,land ,freshwater ,land 7dirt-bed7 ,lower ,purbeck4 ,freshwater ,land ,freshwater ,land ,freshwater #g4 ,marine ,portland stone4 ,the annexed tabular view will enable the reader to take in at a glance the successive changes from sea to river1 and from river to sea1 or from these again to a state of land1 which have occurred in this part of ,england between the ,cretaceous and ,oolitic periods4 ,that there have been at least four changes in the species of testacea during the deposition of the ,wealden1 seems to follow from the observations recently made by ,professor ,e4 ,forbes1 so that1 should we hereafter find the signs of many more alternate occupations of the same area by different elements1 it is no more than we might expect4 ,even during a small part of a zoological period1 not sufficient to allow time for many species to die out1 we find that the same area has been laid dry1 and then submerged1 and then again laid dry1 as in the deltas of the ,po and ,ganges1 the history of which has been brought to light by ,artesian borings4#bce-;,a ,we also know that similar revolutions have occurred within the present century 7#ahai7 in the delta of the ,indus in ,cutch#bce-;,b1 where land has been laid permanently under the waters both of the river and sea1 without its soil or shrubs having been swept away4 ,even1 independently of any vertical movements of the ground1 we see in the principal deltas1 such as that of the ,mississippi1 that the sea extends its salt waters annually for many months over considerable spaces1 which1 at other seasons1 are occupied by the river during its inundations4 ,it will be observed that the division of the ,purbecks into upper1 middle1 and lower1 has been made by ,professor ,e4 ,forbes1 strictly on the principle of the entire distinctness of the species of organic remains which they include4 ,the lines of demarcation are not lines of disturbance1 nor indicated by any striking physical characters or mineral changes4 ,the features which attract the eye in the ,purbecks1 such as the dirt-beds1 the dislocated strata at ,lulworth1 and the ,cinder-bed1 do not indicate any breaks in the distribution of organized beings4 ,the causes which led to a complete change of life three times during the deposition of the freshwater and brackish strata must1 says this naturalist1 be sought for1 not simply in either a rapid or a sudden change of their area into land or sea1 but in the great lapse of time which intervened between the epochs of deposition at certain periods during their formation4 ,each dirt-bed may1 no doubt1 be the memorial of many thousand years or centuries1 because we find that #b or #c feet of vegetable soil is the only monument which many a tropical forest has left of its existence ever since the ground on which it now stands was first covered with its shade4 ,yet1 even if we imagined the fossil soils of the ,lower ,purbeck to represent as many ages1 we need not expect on that account to find them constituting the lines of separation between successive strata characterized by different zoological types4 ,the preservation of a layer of vegetable soil1 when in the act of being submerged1 must be regarded as a rare exception to a general rule4 ,it is of so perishable a nature1 that it must usually be carried away by the denuding waves or currents of the sea or by a river2 and many dirt-beds were probably formed in succession1 and annihilated in the ,wealden1 besides those few which now remain4 ,illustration3 ,fig4 #bdd4 ,cone from the ,isle of ,purbeck1 resembling the ,dammara of the ,moluccas4 7,fitton47 ,the plants of the ,wealden1 so far as our knowledge extends at present1 consist chiefly of ,ferns1 ,coniferae 7see fig4 #bdd471 and ,cycadeae1 without any exogens2 the whole more allied to the ,oolitic than to the ,cretaceous vegetation1 although some of the species seem to be common to the chalk4 ,but the vertebrate and invertebrate animals indicate1 in like manner1 a relationship to both these periods1 though a nearer affinity to the ,oolitic4 ,mr4 ,brodie has found the remains of beetles and several insects of the homopterous and trichopterous orders1 some of which now live on plants1 like those of the ,wealden1 while others hover over the surface of our present rivers4 ,but no bones of mammalia have been met with among those of land-reptiles4 ,yet1 as the reader will learn1 in ,chapter ,,xx41 that the relics of marsupial quadrupeds have been detected in still older beds1 and1 as it was so long before a single portion of the jaw of an iguanodon was met with in the ,tilgate quarries 7see p4 #bbh471 we need by no means despair of discovering hereafter some evidence of the existence of warm-blooded quadrupeds at this era4 ,it is1 at least1 too soon to infer1 on mere negative evidence1 that the mammalia were foreign to this fauna4 ,in regard to the geographical extent of the ,wealden1 it cannot be accurately laid down2 because so much of it is concealed beneath the newer marine formations4 ,it has been traced about #bjj ,english miles from west to east1 from ,lulworth ,cove to near ,boulogne1 in ,france2 and about #bbj miles from north-west to south-east1 from ,whitchurch1 in ,buckinghamshire1 to ,beauvais1 in ,france4 ,if the formation be continuous throughout this space1 which is very doubtful1 it does not follow that the whole was contemporaneous2 because1 in all likelihood1 the physical geography of the region underwent frequent change throughout the whole period1 and the estuary may have altered its form1 and even shifted its place4 ,dr4 ,dunker1 of ,cassel1 and ,h4 ,von ,meyer1 in an excellent monograph on the ,wealdens of ,hanover and ,westphalia1 have shown that they correspond so closely1 not only in their fossils1 but also in their mineral characters1 with the ,english series1 that we can scarcely hesitate to refer the whole to one great delta4 ,even then1 the magnitude of the deposit may not exceed that of many modern rivers4 ,thus1 the delta of the ,quorra or ,niger1 in ,africa1 stretches into the interior for more than #agj miles1 and occupies1 it is supposed1 a space of more than #cjj miles along the coast1 thus forming a surface of more than #be1jjj square miles1 or equal to about one half of ,england4#bcg-;,a ,besides1 we know not1 in such cases1 how far the fluviatile sediment and organic remains of the river and the land may be carried out from the coast1 and spread over the bed of the sea4 ,i have shown1 when treating of the ,mississippi1 that a more ancient delta1 including species of shells1 such as now inhabit ,louisiana1 has been upraised1 and made to occupy a wide geographical area1 while a newer delta is forming#bcg-;,b2 and the possibility of such movements1 and their effects1 must not be lost sight of when we speculate on the origin of the ,wealden4 ,if it be asked where the continent was placed from the ruins of which the ,wealden strata were derived1 and by the drainage of which a great river was fed1 we are half tempted to speculate on the former existence of the ,atlantis of ,plato4 ,the story of the submergence of an ancient continent1 however fabulous in history1 must have been true again and again as a geological event4 ,the real difficulty consists in the persistence of a large hydrographical basin1 from whence a great body of fresh water was poured into the sea1 precisely at a period when the neighbouring area of the ,wealden was gradually going downwards #ajjj feet or more perpendicularly4 ,if the adjoining land participated in the movement1 how could it escape being submerged1 or how could it retain its size and altitude so as to continue to be the source of such an inexhaustible supply of fresh water and sediment8 ,in answer to this question1 we are fairly entitled to suggest that the neighbouring land may have been stationary1 or may even have undergone a contemporaneous slow upheaval4 ,there may have been an ascending movement in one region1 and a descending one in a contiguous parallel zone of country2 just as the northern part of ,scandinavia is now rising1 while the middle portion 7that south of ,stockholm7 is unmoved1 and the southern extremity in ,scania is sinking1 or at least has sunk within the historical period4#bcg-;,c ,we must1 nevertheless1 conclude1 if we adopt the above hypothesis1 that the depression of the land became general throughout a large part of ,europe at the close of the ,wealden period1 a subsidence which brought in the cretaceous ocean4 ,,footnotes3 #bbg-;,a ,dr4 ,fitton1 ,geol4 ,trans4 vol4 iv4 p4 #cbj4 ,second ,series4 #bcj-;,a ,mantell1 ,geol4 of ,s4 ,e4 of ,england1 p4 #bdd4 #bca-;,a ,on the ,dorsetshire ,purbecks1 by ,prof4 ,e4 ,forbes1 ,edinb4 ,brit4 ,assoc41 ,aug4 #ahej4 #bcc-;,a ,mr4 ,webster first noticed the erect position of the trees and described the ,dirt-bed4 #bcc-;,b ,fitton1 ,geol4 ,trans41 ,second ,series1 vol4 iv4 pp4 #bbj1 #bba4 #bcc-;,c ,see ,flinders' ,voyage4 #bcc-;,d ,fitton1 ibid4 #bcc-;,e ,buckland and ,de la ,beche1 ,geol4 ,trans41 ,second ,series1 vol4 iv4 p4 #af4 ,mr4 ,forbes has ascertained that the subjacent rock is a freshwater limestone1 and not a portion of the ,portland oolite1 as was previously imagined4 #bcd-;,a ,e4 ,forbes1 ibid4 #bce-;,a ,see ,principles of ,geol41 #hth ed4 pp4 #bfj-bfh4 #bce-;,b ,ibid4 p4 #ddc4 #bcg-;,a ,fitton1 ,geol4 of ,hastings1 p4 #eh42 who cites ,lander's ,travels4 #bcg-;,b ,see above1 p4 #he42 and ,second ,visit to the ,u4 ,s4 vol4 ii4 chap4 xxxiv4 #bcg-;,c ,see the ,author's ,anniv4 ,address1 ,geol4 ,soc4 #ahej1 ,quart4 ,geol4 ,journ4 vol4 vi4 p4 #eb4 ,,chapter ,,xix4 ,,denudation ,,of ,,the ,,chalk ,,and ,,wealden4 ,physical geography of certain districts composed of ,cretaceous and ,wealden strata--,lines of inland chalk-cliffs on the ,seine in ,normandy--,outstanding pillars and needles of chalk--,denudation of the chalk and ,wealden in ,surrey1 ,kent1 and ,sussex--,chalk once continuous from the ,north to the ,south ,downs--,anticlinal axis and parallel ridges--,longitudinal and transverse valleys--,chalk escarpments--,rise and denudation of the strata gradual--,ridges formed by harder1 valleys by softer beds--,why no alluvium1 or wreck of the chalk1 in the central district of the ,weald--,at what periods the ,weald valley was denuded--,land has most prevailed where denudation has been greatest--,elephant bed1 ,brighton4 ,all the fossiliferous formations may be studied by the geologist in two distinct points of view3 first1 in reference to their position in the series1 their mineral character and fossils2 and1 secondly1 in regard to their physical geography1 or the manner in which they now enter1 as mineral masses1 into the external structure of the earth2 forming the bed of lakes and seas1 or the surface and foundation of hills and valleys1 plains and table-lands4 ,some account has already been given on the first head of the ,tertiary1 the ,cretaceous1 and ,wealden strata2 and we may now proceed to consider certain features in the physical geography of these groups as they occur in parts of ,england and ,france4 ,the hills composed of white chalk in the ,s4,e4 of ,england have a smooth rounded outline1 and being usually in the state of sheep pastures1 are free from trees or hedgerows2 so that we have an opportunity of observing how the valleys by which they are drained ramify in all directions1 and become wider and deeper as they descend4 ,although these valleys are now for the most part dry1 except during heavy rains and the melting of snow1 they may have been due to aqueous denudation1 as explained in the sixth chapter2 having been excavated when the chalk emerged gradually from the sea4 ,this opinion is confirmed by the occasional occurrence of long lines of inland cliffs1 in which the strata are cut off abruptly in steep and often vertical precipices4 ,the true nature of such escarpments is nowhere more obvious than in parts of ,normandy1 where the river ,seine and its tributaries flow through deep winding valleys1 hollowed out of chalk horizontally stratified4 ,thus1 for example1 if we follow the ,seine for a distance of about #cj miles from ,andelys to ,elboeuf1 we find the valley flanked on both sides by a deep slope of chalk1 with numerous beds of flint1 the formation being laid open for a thickness of about #bej and #cjj feet4 ,above the chalk is an overlying mass of sand1 gravel1 and clay1 from #cj to #ajj feet thick4 ,the two opposite slopes of the hills a and b1 where the chalk appears at the surface1 are from #b to #d miles apart1 and they are often perfectly smooth and even1 like the steepest of our downs in ,england2 but at many points they are broken by one1 two1 or more ranges of vertical and even overhanging cliffs of bare white chalk with flints4 ,at some points detached needles and pinnacles stand in the line of the cliffs1 or in front of them1 as at c1 fig4 #bde4 ,on the right bank of the ,seine1 at ,andelys1 one range1 about #b miles long1 is seen varying from #ej to #ajj feet in perpendicular height1 and having its continuity broken by a number of dry valleys or coombs1 in one of which occurs a detached rock or needle1 called the ,tete d',homme 7see figs4 #bdf1 #bdg474 ,the top of this rock presents a precipitous face towards every point of the compass2 its vertical height being more than #bj feet on the side of the downs1 and #dj towards the ,seine1 the average diameter of the pillar being #cf feet4 ,its composition is the same as that of the larger cliffs in its neighbourhood1 namely1 white chalk1 having occasionally a crystalline texture like marble1 with layers of flint in nodules and tabular masses4 ,the flinty beds often project in relief #d or #e feet beyond the white chalk1 which is generally in a state of slow decomposition1 either exfoliating or being covered with white powder1 like the chalk cliffs on the ,english coast2 and1 as in them1 this superficial powder contains in some places common salt4 ,illustration3 ,fig4 #bde4 ,section across ,valley of ,seine4 ,illustration3 ,fig4 #bdf4 ,view of the ,tete d',homme1 ,andelys1 seen from above4 ,other cliffs are situated on the right bank of the ,seine1 opposite ,tournedos1 between ,andelys and ,pont de l',arche1 where the precipices are from #ej to #hj feet high3 several of their summits terminate in pinnacles2 and one of them1 in particular1 is so completely detached as to present a perpendicular face #ej feet high towards the sloping down4 ,on these cliffs several ledges are seen1 which mark so many levels at which the waves of the sea may be supposed to have encroached for a long period4 ,at a still greater height1 immediately above the top of this range1 are three much smaller cliffs1 each about #d feet high1 with as many intervening terraces1 which are continued so as to sweep in a semicircular form round an adjoining coomb1 like those in ,sicily before described 7p4 #gf474 ,illustration3 ,fig4 #bdg4 ,side view of the ,tete d',homme4 ,white chalk with flints4 ,illustration3 ,fig4 #bdh4 ,chalk pinnacle at ,senneville4 ,illustration3 ,fig4 #bdi4 ,roches d',orival1 ,elboeuf4 ,if we then descend the river from ,vatteville to a place called ,senneville1 we meet with a singular needle about #ej feet high1 perfectly isolated on the escarpment of chalk on the right bank of the ,seine 7see fig4 #bdh474 ,another conspicuous range of inland cliffs is situated about #ab miles below on the left bank of the ,seine1 beginning at ,elboeuf1 and comprehending the ,roches d',orival 7see fig4 #bdi474 ,like those before described1 it has an irregular surface1 often overhanging1 and with beds of flint projecting several feet4 ,like them1 also1 it exhibits a white powdery surface1 and consists entirely of horizontal chalk with flints4 ,it is #dj miles inland1 its height1 in some parts1 exceeding #bjj feet1 and its base only a few feet above the level of the ,seine4 ,it is broken1 in one place1 by a pyramidal mass or needle1 #bjj feet high1 called the ,roche de ,pignon1 which stands out about #be feet in front of the upper portion of the main cliffs1 with which it is united by a narrow ridge about #dj feet lower than its summit 7see fig4 #bej474 ,like the detached rocks before mentioned at ,senneville1 ,vatteville1 and ,andelys1 it may be compared to those needles of chalk which occur on the coast of ,normandy1 as well as in the ,isle of ,wight and in ,purbeck#bda-;,a 7see fig4 #bea474 ,illustration3 ,fig4 #bej4 ,view of the ,roche de ,pignon1 seen from the south4 ,illustration3 ,fig4 #bea4 ,needle and ,arch of ,etretat1 in the chalk cliffs of ,normandy4 ,height of ,arch #ajj feet4 7,passy47#bda-;,b ,the foregoing description and drawings will show1 that the evidence of certain escarpments of the chalk having been originally sea-cliffs1 is far more full and satisfactory in ,france than in ,england4 ,if it be asked why1 in the interior of our own country1 we meet with no ranges of precipices equally vertical and overhanging1 and no isolated pillars or needles1 we may reply that the greater hardness of the chalk in ,normandy may1 no doubt1 be the chief cause of this difference4 ,but the frequent absence of all signs of littoral denudation in the valley of the ,seine itself is a negative fact of a far more striking and perplexing character4 ,the cliffs1 after being almost continuous for miles1 are then wholly wanting for much greater distances1 being replaced by a green sloping down1 although the beds remain of the same composition1 and are equally horizontal2 and although we may feel assured that the manner of the upheaval of the land1 whether intermittent or not1 must have been the same at those intermediate points where no cliffs exist1 as at others where they are so fully developed4 ,but1 in order to explain such apparent anomalies1 the reader must refer again to the theory of denudation1 as expounded in the #fth chapter2 where it was shown1 first1 that the undermining force of the waves and marine currents varies greatly at different parts of every coast2 secondly1 that precipitous rocks have often decomposed and crumbled down2 and thirdly1 that many terraces and small cliffs may now lie concealed beneath a talus of detrital matter4 ,denudation of the ,weald ,valley4--,no district is better fitted to illustrate the manner in which a great series of strata may have been upheaved and gradually denuded than the country intervening between the ,north and ,south ,downs4 ,this region1 of which a ground plan is given in the accompanying map 7fig4 #beb471 comprises within it the whole of ,sussex1 and parts of the counties of ,kent1 ,surrey1 and ,hampshire4 ,the space in which the formations older than the ,white ,chalk1 or those from the ,gault to the ,hastings sand inclusive1 crop out1 is bounded everywhere by a great escarpment of chalk1 which is continued on the opposite side of the channel in the ,bas ,boulonnais in ,france1 where it forms the semicircular boundary of a tract in which older strata also appear at the surface4 ,the whole of this district may therefore be considered geologically as one and the same4 ,illustration3 ,fig4 #beb4 ,geological ,map of the south-east of ,england and part of ,france1 exhibiting the denudation of the ,weald4 #a4 ,tertiary4 #b4 ,chalk and upper greensand4 #c4 ,gault4 #d4 ,lower ,greensand4 #e4 ,weald clay4 #f4 ,hastings sand4 #g4 ,purbeck beds4 #h4 ,oolite4 ,illustration3 ,fig4 #bec4 ,section from the ,london to the ,hampshire basin across the valley of the ,weald4 #a4 ,tertiary strata4 #b4 ,chalk and firestone4 #c4 ,gault4 #d4 ,lower greensand4 #e4 ,weald clay4 #f4 ,hastings sands4 ,illustration3 ,fig4 #bed4 ,highest point of ,south ,downs1 #heh feet4 ,anticlinal axis of the ,weald4 ,crowborough ,hill1 #hjd feet4 ,highest point of ,north ,downs1 #hhj feet4#bdc-;,a ,section of the country from the confines of the basin of ,london to that of ,hants1 with the principal heights above the level of the sea on a true scale4#bdc-;,b ,the space here inclosed within the escarpment of the chalk affords an example of what has been sometimes called a valley of elevation 7more properly of denudation72 where the strata1 partially removed by aqueous excavation1 dip away on all sides from a central axis4 ,thus1 it is supposed that the area now occupied by the ,hastings sand 7,no4 #f47 was once covered by the ,weald clay 7,no4 #e471 and this again by the ,greensand 7,no4 #d471 and this by the ,gault 7,no4 #c472 and1 lastly1 that the ,chalk 7,no4 #b47 extended originally over the whole space between the ,north and the ,south ,downs4 ,this theory will be better understood by consulting the annexed diagram 7fig4 #bec471 where the dark lines represent what now remains1 and the fainter ones those portions of rock which are believed to have been carried away4 ,at each end of the diagram the tertiary strata 7,no4 #a47 are exhibited reposing on the chalk4 ,in the middle are seen the ,hastings sands 7,no4 #f47 forming an anticlinal axis1 on each side of which the other formations are arranged with an opposite dip4 ,it has been necessary1 however1 in order to give a clear view of the different formations1 to exaggerate the proportional height of each in comparison to its horizontal extent2 and a true scale is therefore subjoined in another diagram 7fig4 #bed471 in order to correct the erroneous impression which might otherwise be made on the reader's mind4 ,in this section the distance between the ,north and ,south ,downs is represented to exceed forty miles2 for the ,valley of the ,weald is here intersected in its longest diameter1 in the direction of a line between ,lewes and ,maidstone4 ,through the central portion1 then1 of the district supposed to be denuded runs a great anticlinal line1 having a direction nearly east and west1 on both sides of which the beds #e1 #d1 #c1 and #b1 crop out in succession4 ,but1 although1 for the sake of rendering the physical structure of this region more intelligible1 the central line of elevation has alone been introduced1 as in the diagrams of ,smith1 ,mantell1 ,conybeare1 and others1 geologists have always been well aware that numerous minor lines of dislocation and flexure run parallel to the great central axis4 ,in the central area of the ,hastings sand the strata have undergone the greatest displacement2 one fault being known1 where the vertical shift of a bed of calcareous grit is no less than #fj fathoms4#bdd-;,a ,much of the picturesque scenery of this district arises from the depth of the narrow valleys and ridges to which the sharp bends and fractures of the strata have given rise2 but it is also in part to be attributed to the excavating power exerted by water1 especially on the interstratified argillaceous beds4 ,besides the series of longitudinal valleys and ridges in the ,weald1 there are valleys which run in a transverse direction1 passing through the chalk to the basin of the ,thames on the one side1 and to the ,english ,channel on the other4 ,in this manner the chain of the ,north ,downs is broken by the rivers ,wey1 ,mole1 ,darent1 ,medway1 and ,stour2 the ,south ,downs by the ,arun1 ,adur1 ,ouse1 and ,cuckmere4#bdd-;,b ,if these transverse hollows could be filled up1 all the rivers1 observes ,mr4 ,conybeare1 would be forced to take an easterly course1 and to empty themselves into the sea by ,romney ,marsh and ,pevensey ,levels4#bde-;,a ,mr4 ,martin has suggested that the great cross fractures of the chalk1 which have become river channels1 have a remarkable correspondence on each side of the valley of the ,weald2 in several instances the gorges in the ,north and ,south ,downs appearing to be directly opposed to each other4 ,thus1 for example1 the defiles of the ,wey in the ,north ,downs1 and of the ,arun in the ,south1 seemed to coincide in direction2 and1 in like manner1 the ,ouse corresponds to the ,darent1 and the ,cuckmere to the ,medway4#bde-;,b ,illustration3 ,fig4 #bee4 ,view of the chalk escarpment of the ,south ,downs4 ,taken from the ,devil's ,dike1 looking towards the west and south-west4 a4 ,the town of ,steyning is hidden by this point4 b4 ,edburton church4 c4 ,road4 d4 ,river ,adur4 ,although these coincidences may1 perhaps1 be accidental1 it is by no means improbable1 as hinted by the author above mentioned1 that great amount of elevation towards the centre of the ,weald district gave rise to transverse fissures4 ,and as the longitudinal valleys were connected with that linear movement which caused the anticlinal lines running east and west1 so the cross fissures might have been occasioned by the intensity of the upheaving force towards the centre of the line4 ,but before treating of the manner in which the upheaving movement may have acted1 ,i shall endeavour to make the reader more intimately acquainted with the leading geographical features of the district1 so far as they are of geological interest4 ,in whatever direction we travel from the tertiary strata of the basins of ,london and ,hampshire towards the valley of the ,weald1 we first ascend a slope of white chalk1 with flints1 and then find ourselves on the summit of a declivity consisting1 for the most part1 of different members of the chalk formation2 below which the upper greensand1 and sometimes1 also1 the gault1 crop out4 ,this steep declivity is the great escarpment of the chalk before mentioned1 which overhangs a valley excavated chiefly out of the argillaceous or marly bed1 termed ,gault 7,no4 #c474 ,the escarpment is continuous along the southern termination of the ,north ,downs1 and may be traced from the sea1 at ,folkestone1 westward to ,guildford and the neighbourhood of ,petersfield1 and from thence to the termination of the ,south ,downs at ,beachy ,head4 ,in this precipice or steep slope the strata are cut off abruptly1 and it is evident that they must originally have extended farther4 ,in the woodcut 7fig4 #bee4 p4 #bde471 part of the escarpment of the ,south ,downs is faithfully represented1 where the denudation at the base of the declivity has been somewhat more extensive than usual1 in consequence of the upper and lower greensand being formed of very incoherent materials1 the upper1 indeed1 being extremely thin and almost wanting4 ,illustration3 ,fig4 #bef4 ,chalk escarpment1 as seen from the hill above ,steyning1 ,sussex4 ,the castle and village of ,bramber in the foreground4 ,the geologist cannot fail to recognize in this view the exact likeness of a sea cliff2 and if he turns and looks in an opposite direction1 or eastward1 towards ,beachy ,head 7see fig4 #bef471 he will see the same line of heights prolonged4 ,even those who are not accustomed to speculate on the former changes which the surface has undergone may fancy the broad and level plain to resemble the flat sands which were laid dry by the receding tide1 and the different projecting masses of chalk to be the headlands of a coast which separated the different bays from each other4 ,in regard to the transverse valleys before mentioned1 as intersecting the chalk hills1 some idea of them may be derived from the subjoined sketch 7fig4 #beg471 of the gorge of the river ,adur1 taken from the summit of the chalk downs1 at a point in the bridle-way leading from the towns of ,bramber and ,steyning to ,shoreham4 ,if the reader will refer again to the view given in a former woodcut 7fig4 #bee4 p4 #bde471 he will there see the exact point where the gorge of which ,i am now speaking interrupts the chalk escarpment4 ,a projecting hill1 at the point a1 hides the town of ,steyning1 near which the valley commences where the ,adur passes directly to the sea at ,old ,shoreham4 ,the river flows through a nearly level plain1 as do most of the others which intersect the hills of ,surrey1 ,kent1 and ,sussex2 and it is evident that these openings1 so far at least as they are due to aqueous erosion1 have not been produced by the rivers1 many of which1 like the ,ouse near ,lewes1 have filled up arms of the sea1 instead of deepening the hollows which they traverse4 ,illustration3 ,fig4 #beg4 ,transverse ,valley of the ,adur in the ,south ,downs4 a4 ,town of ,steyning4 b4 ,river ,adur4 c4 ,old ,shoreham4 ,now1 in order to account for the manner in which the five groups of strata1 #b1 #c1 #d1 #e1 #f1 represented in the map1 fig4 #beb4 and in the section fig4 #bec41 may have been brought into their present position1 the following hypothesis has been very generally adopted3--,suppose the five formations to lie in horizontal stratification at the bottom of the sea2 then let a movement from below press them upwards into the form of a flattened dome1 and let the crown of this dome be afterwards cut off1 so that the incision should penetrate to the lowest of the five groups4 ,the different beds would then be exposed on the surface1 in the manner exhibited in the map1 fig4 #beb4bdg-;,a ,the quantity of denudation or removal by water of stratified masses assumed to have once reached continuously from the ,north to the ,south ,downs is so enormous1 that the reader may at first be startled by the boldness of the hypothesis4 ,but the difficulty vanishes when once sufficient time is allowed for the gradual and successive rise of the strata1 during which the waves and currents of the ocean might slowly accomplish an operation1 which no sudden diluvial rush of waters could possibly have effected4 ,among other proofs of the action of water1 it may be stated that the great longitudinal valleys follow the outcrop of the softer and more incoherent beds1 while ridges or lines of cliff usually occur at those points where the strata are composed of harder stone4 ,thus1 for example1 the chalk with flints1 together with the subjacent upper greensand1 which is often used for building1 under the provincial name of firestone1 has been cut into a steep cliff on that side on which the sea encroached4 ,this escarpment bounds a deep valley1 excavated chiefly out of the soft argillaceous or marly bed1 termed gault 7,no4 #c474 ,in some places the upper greensand is in a loose and incoherent state1 and there it has been as much denuded as the gault2 as1 for example1 near ,beachy ,head2 but farther to the westward it is of great thickness1 and contains hard beds of blue chert and calcareous sandstone or firestone4 ,here1 accordingly1 we find that it produces a corresponding influence on the scenery of the country2 for it runs out like a step beyond the foot of the chalk-hills1 and constitutes a lower terrace1 varying in breadth from a quarter of a mile to three miles1 and following the sinuosities of the chalk escarpment4#bdh-;,a ,illustration3 ,fig4 #beh4 ,cross section4 a4 ,chalk with flints4 b4 ,chalk without flints4 c4 ,upper greensand1 or firestone4 d4 ,gault4 ,it is impossible to desire a more satisfactory proof that the escarpment is due to the excavating power of water during the rise of the strata2 for ,i have shown1 in my account of the coast of ,sicily1 in what manner the encroachments of the sea tend to efface that succession of terraces which must otherwise result from the intermittent upheaval of a coast preyed upon by the waves4#bdh-;,b ,during the interval between two elevatory movements1 the lower terrace will usually be destroyed1 wherever it is composed of incoherent materials2 whereas the sea will not have time entirely to sweep away another part of the same terrace1 or lower platform1 which happens to be composed of rocks of a harder texture1 and capable of offering a firmer resistance to the erosive action of water4 ,as the yielding clay termed gault would be readily washed away1 we find its outcrop marked everywhere by a valley which skirts the base of the chalk hills1 and which is usually bounded on the opposite side by the lower greensand2 but as the upper beds of this last formation are most commonly loose and incoherent1 they also have usually disappeared and increased the breadth of the valley4 ,but in those districts where chert1 limestone1 and other solid materials enter largely into the composition of this formation 7,no4 #d471 they give rise to a range of hills parallel to the chalk1 which sometimes rival the escarpment of the chalk itself in height1 or even surpass it1 as in ,leith ,hill1 near ,dorking4 ,this ridge often presents a steep escarpment towards the soft argillaceous deposit called the ,weald clay 7,no4 #e42 see the strong lines in fig4 #bec4 p4 #bdc471 which usually forms a broad valley1 separating the lower greensand from the ,hastings sands or ,forest ridge2 but where subordinate beds of sandstone of a firmer texture occur1 the uniformity of the plain of ,no4 #e4 is broken by waving irregularities and hillocks4 ,it will be easy to show how closely the superficial inequalities agree with those which we might naturally expect to originate during the gradual rise of the ,wealden district4 ,suppose the line of the most energetic movement to have coincided with what is now the central ridge of the ,weald valley2 in that case the first land which emerged must have been situated where the ,forest ridge is now placed4 ,here many shoals and reefs may first have existed1 and islands of chalk devoured in the course of ages by the ocean 7see fig4 #bec472 so that the top of the shattered dome which first appeared above water may have been utterly destroyed1 and the masses represented by the fainter lines 7fig4 #bec47 removed4 #b ,illustrations3 ,fig4 #bei41 ,fig4 #bfj4 ,the dotted lines represent the sea-level4 ,the upper greensand is represented 7fig4 #bei47 as forming on the left hand a single precipice with the chalk2 while on the right there are two cliffs1 with an intervening terrace1 as before described in fig4 #beh4 ,two strips of land would then remain on each side of a channel1 presenting ranges of white cliffs facing each other4 ,a powerful current might then scoop out a channel in the gault 7,no4 #b474 ,this softer bed would yield with ease in proportion as parts of it were brought up from time to time and exposed to the fury of the waves1 so that large spaces occupied by the harder formation or greensand 7,no4 #c47 would be laid bare4 ,this last rock1 opposing a more effectual resistance1 would next emerge2 while the chalk cliffs1 at the base of which the gault is rapidly undermined1 would recede farther from each other1 after which four parallel strips of land1 or rows of islands1 would be caused1 which are represented by the masses which in fig4 #bfj4 rise above the dotted line indicating the sea-level4 ,in this diagram1 however1 the inclination of the upper surface of the formations 7,nos4 #a4 and #c471 is exaggerated4 ,originally this surface must have been level1 like the submarine terraces produced by denudation1 and described before 7p4 #gd4 and #gg472 but they were afterwards more and more tilted by that general movement to which the region of the ,weald owes its structure4 ,at length1 by the farther elevation of the dome-shaped mass1 the clay 7,no4 #d47 would be brought within reach of the waves1 which would probably gain the more easy access to the subjacent deposit by the rents which would be caused in ,no4 #c41 and in the central part of the ridge where the uplifting force had been exerted with the greatest energy4 ,the opposite cliffs1 in which the greensand 7,no4 #c47 terminates1 would now begin to recede from each other1 having at their base a yielding stratum of clay 7,no4 #d474 ,lastly1 the sea would penetrate to the sand 7,no4 #e471 and then the state of things indicated in the dark lines of the upper section 7fig4 #bec471 would be consummated4 ,illustration3 ,fig4 #bfa4 ,the ,coomb1 near ,lewes4 ,it was stated that there are many lines of flexure and dislocation1 running east and west1 or parallel to the central axis of the ,wealden4 ,they are numerous in the district of the ,hastings sand1 and sometimes occur in the chalk itself4 ,one of the latter kind has given rise to the ravine called the ,coomb1 near ,lewes1 and was first traced out by ,dr4 ,mantell1 in whose company ,i examined it4 ,this coomb is seen on the eastern side of the valley of the ,ouse1 in the suburbs of the town of ,lewes4 ,the steep declivities on each side are covered with green turf1 as is the bottom1 which is perfectly dry4 ,no outward signs of disturbance are visible2 and the connection of the hollow with subterranean movements would not have been suspected by the geologist1 had not the evidence of great convulsions been clearly exposed in the escarpment of the valley of the ,ouse1 and the numerous chalk pits worked at the termination of the ,coomb4 ,by the aid of these we discover that the ravine coincides precisely with a line of fault1 on one side of which the chalk with flints 7a1 fig4 #bfb471 appears at the summit of the hill1 while it is thrown down to the bottom on the other4 ,mr4 ,martin1 in his work on the geology of ,western ,sussex1 published in #ahbh1 threw much light on the structure of the ,wealden by tracing out continuously for miles the direction of many anticlinal lines and cross fractures2 and the same course of investigation has since been followed out in greater detail by ,mr4 ,hopkins4 ,the mathematician last-mentioned has shown that the observed direction of the lines of flexure and dislocation in the ,weald district coincide with those which might have been anticipated theoretically on mechanical principles1 if we assume certain simple conditions under which the strata were lifted up by an expansive subterranean force4 ,he finds by calculation that if this force was applied so as to act uniformly upwards within an elliptic area1 the longitudinal fissures thereby produced would nearly coincide with the outlines of the ellipse1 forming cracks1 which are portions of smaller concentric ellipses1 parallel to the margin of the larger one4 ,these longitudinal fissures would also be intercepted by others running at right angles to them1 and both lines of fracture may have been produced at the same time4#bea-;,a ,in this illustration it is supposed that the expansive force acted simultaneously and with equal intensity at every point within the upheaved area1 and not with greater energy along the central axis or region of principal elevation4 ,illustration3 ,fig4 #bfb4 ,fault in the cliff hills near ,lewes4 ,mantell4 a4 ,chalk with flints4 b4 ,lower chalk4#bea-;,b ,the geologist cannot fail to derive great advantage in his speculations from the mathematical investigation of a problem of this kind1 where results free from all uncertainty are obtained on the assumption of certain simple conditions4 ,such results1 when once ascertained by mathematical methods1 may serve as standard cases1 to which others occurring in nature of a more complicated kind may be referred4 ,in order that a uniform force should cause the strata to attain in the centre of the ellipse a height so far exceeding that which they have reached round the margin1 it is necessary to assume that the mass of upheaved strata offered originally a very unequal degree of resistance to the subterranean force4 ,this may have happened either from their being more fractured in one place than in another1 or from being pressed down by a less weight of incumbent strata2 as if we suppose1 what is far from improbable1 that great denudation had taken place in the middle of the ,wealden before the final and principal upheaval occurred4 ,it is suggested that the beds may have been acted upon somewhat in the manner of a carpet spread out loosely on a floor1 and nailed down round the edges1 which would swell into the shape of a dome if pressed up equally at every point by air admitted from beneath4 ,but when we are reasoning on the particular phenomena of the ,weald1 we have no geological data for determining whether it be more probable that originally the resistance to be overcome was so extremely unequal in different places1 or whether the subterranean force1 instead of being everywhere uniform1 was not applied with very different degrees of intensity beneath distinct portions of the upraised area4 ,the opinion that both the longitudinal and transverse lines of fracture may have been produced simultaneously1 accords well with that expressed by ,m4 ,thurmann1 in his work on the anticlinal ridges and valleys of elevation of the ,bernese ,jura4#beb-;,a ,for the accuracy of his map and sections ,i can vouch1 from personal examination1 in #ahce1 of part of the region surveyed by him4 ,among other results1 at which this author arrived1 it appears that the breadth of all the numerous anticlinal ridges and dome-shaped masses in the ,jura is invariably great in proportion to the number of the formations exposed to view2 or1 in other words1 to the depth to which the superimposed groups of secondary strata have been laid open4 7,see fig4 #ga4 p4 #ee4 for structure of ,jura47 ,he also remarks1 that the anticlinal lines are occasionally oblique and cross each other1 in which case the greatest dislocation of the beds takes place4 ,some of the cross fractures are imagined by him to have been contemporaneous1 others subsequent to the longitudinal ones4 ,i have assumed1 in the former part of this chapter1 that the rise of the ,weald was gradual1 whereas many geologists have attributed its elevation to a single effort of subterranean violence4 ,there appears to them such a unity of effect in this and other lines of deranged strata in the south-east of ,england1 such as that of the ,isle of ,wight1 as is inconsistent with the supposition of a great number of separate movements recurring after long intervals of time4 ,but we know that earthquakes are repeated throughout a long series of ages in the same spots1 like volcanic eruptions4 ,the oldest lavas of ,etna were poured out many thousands1 perhaps myriads of years before the newest1 and yet they1 and the movements accompanying their emission1 have produced a symmetrical mountain2 and if rivers of melted matter thus continue to flow in the same direction1 and towards the same point1 for an indefinite lapse of ages1 what difficulty is there in conceiving that the subterranean volcanic force1 occasioning the rise or fall of certain parts of the earth's crust1 may1 by reiterated movements1 produce the most perfect unity of result8 ,alluvium of the ,weald4--,our next inquiry may be directed to the alluvium strewed over the surface of the supposed area of denudation4 ,has any wreck been left behind of the strata removed8 ,to this we may answer1 that the chalk downs even on their summits are covered every where with gravel composed of unrounded and partially rounded chalk flints1 such as might remain after masses of white chalk had been softened and removed by water4 ,this superficial accumulation of the hard or siliceous materials of the disintegrated strata may be due in some degree to pluvial action2 for during extraordinary rains a rush of water charged with calcareous matter1 of a milk-white colour1 may be seen to descend even gently sloping hills of chalk4 ,if a layer no thicker than the tenth of an inch be removed once in a century1 a considerable mass may in the course of indefinite ages melt away1 leaving nothing save a layer of flinty nodules to attest its former existence4 ,these unrolled flints may remain mixed with others more or less rounded1 which the waves left originally on the surface of the chalk1 when it first emerged from the sea4 ,a stratum of fine clay sometimes covers the surface of slight depressions and the bottom of valleys in the white chalk1 which may represent the aluminous residue of the rock1 after the pure carbonate of lime has been dissolved by rain water1 charged with excess of carbonic acid derived from decayed vegetable matter4#bec-;,a ,although flint gravel is so abundant on the chalk itself1 it is usually wanting in the deep longitudinal valleys at the foot of the chalk escarpment1 although1 in some few instances1 the detritus of the chalk has been traced in patches over the gault1 and even the lower greensand1 for a distance of several miles from the escarpment of the ,north and ,south ,downs4 ,but no vestige of the chalk and its flints has been seen on the central ridge of the ,weald or the ,hastings sands1 but merely gravel derived from the rocks immediately subjacent4 ,this distribution of alluvium1 and especially the absence of chalk detritus in the central district1 agrees well with the theory of denudation before set forth2 for to return to fig4 #bei41 if the chalk 7,no4 #a47 were once continuous and covered every where with flint gravel1 this superficial covering would be the first to be carried away from the highest part of the dome long before any of the gault 7,no4 #b47 was laid bare4 ,now if some ruins of the chalk remain at first on the gault1 these would be1 in a great degree1 cleared away before any part of the lower greensand 7,no4 #c47 is denuded4 ,thus in proportion to the number and thickness of the groups removed in succession1 is the probability lessened of our finding any remnants of the highest group strewed over the bared surface of the lowest4 ,as an exception to the general rule of the small distance to which any wreck of the chalk can be traced from the escarpments of the ,north and ,south ,downs1 ,i may mention a thick bed of chalk flints which occurs near ,barcombe1 about three miles to the north of ,lewes 7see fig4 #bfc471 a place which ,i visited with ,dr4 ,mantell1 to whom ,i am indebted for the accompanying section4 ,even here it will be seen that the gravel reaches no farther than the ,weald ,clay4 ,the same section shows one of the minor east and west anticlinal lines before alluded to 7p4 #bdd474 ,illustration3 ,fig4 #bfc4 ,section from the north escarpment of the ,south ,downs to ,barcombe4 #a4 ,gravel composed of partially rounded chalk flints4 #b4 ,chalk with and without flints4 #c4 ,lowest chalk or chalk marl 7upper greensand wanting74 #d4 ,gault4 #e4 ,lower greensand4 #f4 ,weald clay4 ,at what period the ,weald ,valley was denuded4--,if we inquire at what geological period the denudation of the ,weald was effected1 we shall immediately perceive that the question is limited to this point1 whether it took place during or subsequent to the deposition of the ,eocene strata of the south of ,england4 ,for in the basins of ,london and ,hampshire the ,eocene strata are conformable to the chalk1 being horizontal where the beds of chalk are horizontal1 and vertical where they are vertical1 so that both series of rocks appear to have participated in nearly the same movements4 ,at the eastern extremity of the ,isle of ,wight1 some beds even of the freshwater series have been thrown on their edges1 like those of the ,london clay4 ,nevertheless we can by no means infer that all the tertiary deposits of the ,london and ,hampshire basins once extended like the chalk over the entire valley of the ,weald1 because the denudation of the chalk and greensand may have been going on in the centre of that area1 while contiguous parts of the sea were sufficiently deep to receive and retain the matter derived from that waste4 ,thus while the waves and currents were excavating the longitudinal valleys ,d and ,c 7fig4 #bfd471 the deposits a may have been thrown down to the bottom of the contiguous deep water ,e1 the sediment being drifted through transverse fissures1 as before explained4 ,in this case1 the rise of the formations ,nos4 #a1 #b1 #c1 #d1 #e1 may have been going on contemporaneously with the excavation of the valleys ,c and ,d1 and with the accumulation of the tertiary strata a4 ,illustration3 ,fig4 #bfd4 ,cross section4 ,this idea receives some countenance from the fact of the tertiary strata1 near their junction with the chalk of the ,london and ,hampshire basins1 often consisting of dense beds of sand and shingle1 as at ,blackheath and in the ,addington ,hills near ,croydon4 ,they also contain occasionally freshwater shells and the remains of land animals and plants1 which indicate the former presence of land at no great distance1 some part of which may have occupied the centre of the ,weald4 ,such masses of well-rolled pebbles occurring in the lowest ,eocene strata1 or those called the plastic clay and sands before described 7,no4 #c4 b1 ,tab4 p4 #aig471 imply the neighbourhood of an ancient shore4 ,they also indicate the destruction of pre-existing chalk with flints4 ,at the same time fossil shells of the genera ,melania1 ,cyclas1 and ,unio1 appearing here and there in beds of the same age1 together with plants and the bones of land animals1 bear testimony to contiguous land1 which probably constituted islands scattered over the space now occupied by the tertiary basins of the ,seine and ,thames4 ,the stage of denudation represented in fig4 #bei41 p4 #bdi41 may explain the state of things prevailing at points where such islands existed4 ,by the alternate rising and sinking of the white chalk and older beds1 a large area may have become overspread with gravelly sandy1 and clayey beds of fluvio-marine and shallow-water origin1 before any of the ,london clay proper 7or ,calcaire grossier in ,france7 were superimposed4 ,this may account for the fact that patches of plastic clay and sand 7,no4 #c4 b1 ,tab4 p4 #aig471 are scattered over the surface of the chalk1 reaching in some places to great heights1 and approaching even the edges of the escarpments4 ,we must suppose that subsequently a gradual subsidence took place in certain areas1 which allowed the ,london clay proper to accumulate over the ,lower ,eocene sands and clays1 in a deep sea4 ,during this sinking down 7the vertical amount of which equalled #hjj1 and in parts of the ,isle of ,wight1 according to ,mr4 ,prestwich1 #ahjj feet71 the work of denudation would be unceasing1 being always however confined to those areas where land or islands existed4 ,at length1 when the ,bagshot sand had been in its turn thrown down on the ,london clay1 the space covered by these two formations was again upraised from the sea to about the height which it has since retained4 ,during this upheaval1 the waves would again exert their power1 not only on the white chalk and lower cretaceous and ,wealden strata1 but also on the ,eocene formations of the ,london basin1 excavating valleys and undermining cliffs as the strata emerged from the deep4 ,there are grounds1 as before stated 7p4 #bje471 for presuming that the tertiary area of ,london was converted into land before that of ,hampshire1 and for this reason it contains no marine ,eocene deposits so modern as those of ,barton ,cliff1 or the still newer freshwater and fluvio-marine beds of ,hordwell and the ,isle of ,wight4 ,these last seem unequivocally to demonstrate the local inequality of the upheaving and depressing movements of the period alluded to2 for we find1 in spite of the evidence afforded in ,alum and ,white ,cliff ,bays1 of continued depression to the extent of #ahjj or #bjjj feet1 that at the close of the ,eocene period a dense formation of freshwater strata was produced4 ,the fossils of these strata bear testimony to rivers draining adjacent lands1 and the existence of numerous quadrupeds on those lands4 ,instead of such phenomena1 the signs of an open sea might naturally have been expected as the consequence of so much subsidence1 had not the depression been accompanied or followed by upheaval in a region immediately adjoining4 ,when we attempt to speculate on the geographical changes which took place in the earlier part of the ,eocene epoch1 and to restore in imagination the former state of the physical geography of the south-east of ,england1 we shall do well to bear in mind that wherever there are proofs of great denudation1 there also the greatest area of land has probably existed4 ,in the same space1 moreover1 the oscillations of level1 and the alternate submergence and emergence of coasts1 may be presumed to have been most frequent2 for these fluctuations facilitate the wasting and removing power of waves1 currents1 and rivers4 ,we should also remember that there is always a tendency in the last denuding operations1 to efface all signs of preceding denudation1 or at least all those marks of waste from which alone a geologist can ascertain the date of the removal of the missing strata within the denuded area4 ,it may often be difficult to settle the chronology even of the last of a series of such acts of removal1 but it must be1 in the nature of things1 almost always impossible to assign a date to each of the antecedent denudations4 ,if we wish to determine the times of the destruction of rocks1 we must look any where rather than to the spaces once occupied by the missing rocks4 ,we must inquire to what regions the ruins of the white chalk1 greensand1 ,wealden1 and other strata which have disappeared were transported4 ,we are then led at once to the examination of all the deposits newer than the chalk1 and first to the oldest of these1 the ,lower ,eocene1 and its sand1 shingle1 and clay4 ,in them1 so largely developed in the immediate neighbourhood of the denuded area1 we discover the wreck we are in search of1 regularly stratified1 and inclosing1 in some of its layers1 organic remains of a littoral1 and sometimes fluviatile character4 ,what more can we desire8 ,the shores must have consisted of chalk1 greensand1 and ,wealden1 since these were the only superficial rocks in the south-east of ,england1 at the commencement of the ,eocene epoch4 ,the waves of the sea1 therefore1 and the rivers were grinding down chalk-flints and chert from the greensand into shingle and sand1 or were washing away calcareous and argillaceous matter from the cretaceous and ,wealden beds1 during the whole of the ,eocene period4 ,thus we obtain the date of a great part at least of that enormous amount of denudation of which we have such striking monuments in the space intervening between the ,north and ,south ,downs4 ,illustration3 ,fig4 #bfe4 ,cross section4 ,a4 ,chalk with layers of flint dipping slightly to the south4 b4 ,ancient beach1 consisting of fine sand1 from one to four feet thick1 covered by shingle from five to eight feet thick of pebbles of chalk-flint1 granite1 and other rocks1 with broken shells of recent marine species1 and bones of cetacea4 c4 ,elephant bed1 about fifty feet thick1 consisting of layers of white chalk rubble1 with broken chalk-flints1 in which deposit are found bones of ox1 deer1 horse1 and mammoth4 d4 ,sand and shingle of modern beach4 ,there have been some movements of land on a smaller scale since the ,eocene period in the south-east of ,england4 ,one of the latest of these happened in the ,pleistocene1 or even perhaps as late as the ,post-,pliocene period4 ,the formation called by ,dr4 ,mantell the ,elephant ,bed1 at the foot of the chalk cliffs at ,brighton1 is not merely a talus of calcareous rubble collected at the base of an inland cliff1 but exhibits every appearance of having been spread out in successive horizontal layers by water in motion4 ,the deposit alluded to skirts the shores between ,brighton and ,rottingdean1 and another mass apparently of the same age occurs at ,dover4 ,the phenomena appear to me to suggest the following conclusions3--,first1 the south-eastern part of ,england had acquired its actual configuration when the ancient chalk cliff ,a a was formed1 the beach of sand and shingle b having then been thrown up at the base of the cliff4 ,afterwards the whole coast1 or at least that part of it where the elephant bed now extends1 subsided to the depth of #ej or #fj feet2 and during the period of submergence successive layers of white calcareous rubble c were accumulated1 so as to cover the ancient beach b4 ,subsequently1 the coast was again raised1 so that the ancient shore was elevated to a level somewhat higher than its original position4#beg-;,a ,,footnotes3 #bda-;,a ,an account of these cliffs was read by the author to the ,british ,assoc4 at ,glasgow1 ,sept4 #ahdj4 #bda-;,b ,seine-,inferieure1 p4 #adb4 and pl4 #f4 fig4 #a4 #bdc-;,a ,botley ,hill1 near ,godstone1 in ,surrey1 was found by trigonometrical measurement to be #hhj feet above the level of the sea2 and ,wrotham ,hill1 near ,maidstone1 which appears to be next in height of the ,north ,downs1 #gie feet4 #bdc-;,b ,my friend ,dr4 ,mantell has kindly drawn up this scale at my request4 #bdd-;,a ,fitton1 ,geol4 of ,hastings1 p4 #ee4 #bdd-;,b ,conybeare1 ,outlines of ,geol41 p4 #ha4 #bde-;,a ,ibid41 p4 #ade4 #bde-;,b ,geol4 of ,western ,sussex1 p4 #fa4 #bdg-;,a ,see illustrations of this theory by ,dr4 ,fitton1 ,geol4 ,sketch of ,hastings4 #bdh-;,a ,sir ,e4 ,murchison1 ,geol4 ,sketch of ,sussex1 c41 ,geol4 ,trans41 ,second ,series1 vol4 ii4 p4 #ih4 #bdh-;,b ,see fig4 #id4 p4 #gf4 #bea-;,a ,geol4 ,soc4 ,proceed4 ,no4 #gd4 p4 #cfc4 #ahda1 and ,g4 ,s4 ,trans4 #b ,ser4 v4 #g4 #bea-;,b ,for farther information1 see ,mantell's ,geol4 of ,s4 ,e4 of ,england1 p4 #ceb4 #beb-;,a ,soulevemens ,jurassiques4 ,paris1 #ahcb4 #bec-;,a ,see above1 p4 #hb4 #beg-;,a ,see ,mantell's ,geol4 of ,s4 ,e4 of ,england1 p4 #cb4 ,after re-examining the elephant bed in #ahcd1 ,i was no longer in doubt of its having been a regular subaqueous deposit4 ,in #ahbh1 ,dr4 ,mantell discovered in the shingle below the chalk-rubble the jawbone of a whale #ab feet long1 which must have belonged to an individual from #fj to #gj feet in length1 ,medals of ,creation1 p4 #hbe4 ,,chapter ,,xx4 ,,oolite ,,and ,,lias4 ,subdivisions of the ,oolitic or ,jurassic group--,physical geography of the ,oolite in ,england and ,france--,upper ,oolite--,portland stone and fossils--,lithographic stone of ,solenhofen--,middle ,oolite1 coral rag--,zoophytes--,nerinaean limestone--,diceras limestone--,oxford clay1 ,ammonites and ,belemnites--,lower ,oolite1 ,crinoideans--,great ,oolite and ,bradford clay--,stonesfield slate--,fossil mammalia1 placental and marsupial--,resemblance to an ,australian fauna--,doctrine of progressive development--,collyweston slates--,yorkshire ,oolitic coal-field--,brora coal--,inferior ,oolite and fossils4 ,,oolitic ,,or ,,jurassic ,,group4--,below the freshwater group called the ,wealden1 or1 where this is wanting1 immediately beneath the ,cretaceous formation1 a great series of marine strata1 commonly called the ,oolite1 occurs in ,england and many other parts of ,europe4 ,this group has been so named1 because1 in the countries where it was first examined1 the limestones belonging to it had an oolitic structure 7see p4 #ab474 ,these rocks occupy in ,england a zone which is nearly #cj miles in average breadth1 and extends across the island1 from ,yorkshire in the north-east1 to ,dorsetshire in the south-west4 ,their mineral characters are not uniform throughout this region2 but the following are the names of the principal subdivisions observed in the central and south-eastern parts of ,england3-- ,,oolite4 ,upper a4 ,portland stone and sand4 b4 ,kimmeridge clay4 ,middle c4 ,coral rag4 d4 ,oxford clay4 ,lower e4 ,cornbrash and ,forest marble4 f4 ,great ,oolite and ,stonesfield slate4 g4 ,fuller's earth4 h4 ,inferior ,oolite4 ,the ,lias then succeeds to the ,inferior ,oolite4 ,the ,upper oolitic system of the above table has usually the ,kimmeridge clay for its base2 the ,middle oolitic system1 the ,oxford clay4 ,the ,lower system reposes on the ,lias1 an argillo-calcareous formation1 which some include in the ,lower ,oolite1 but which will be treated of separately in the next chapter4 ,many of these subdivisions are distinguished by peculiar organic remains2 and though varying in thickness1 may be traced in certain directions for great distances1 especially if we compare the part of ,england to which the above-mentioned type refers with the north-east of ,france1 and the ,jura mountains adjoining4 ,in that country1 distant above #djj geographical miles1 the analogy to the ,english type1 notwithstanding the thinness1 or occasional absence of the clays1 is more perfect than in ,yorkshire or ,normandy4 ,physical geography4--,the alternation1 on a grand scale1 of distinct formations of clay and limestone1 has caused the oolitic and liassic series to give rise to some marked features in the physical outline of parts of ,england and ,france4 ,wide valleys can usually be traced throughout the long bounds of country where the argillaceous strata crop out2 and between these valleys the limestones are observed1 composing ranges of hills1 or more elevated grounds4 ,these ranges terminate abruptly on the side on which the several clays rise up from beneath the calcareous strata4 ,illustration3 ,fig4 #bff4 ,cross section4 ,the annexed diagram will give the reader an idea of the configuration of the surface now alluded to1 such as may be seen in passing from ,london to ,cheltenham1 or in other parallel lines1 from east to west1 in the southern part of ,england4 ,it has been necessary1 however1 in this drawing1 greatly to exaggerate the inclination of the beds1 and the height of the several formations1 as compared to their horizontal extent4 ,it will be remarked1 that the lines of cliff1 or escarpment1 face towards the west in the great calcareous eminences formed by the ,chalk and the ,upper1 ,middle1 and ,lower ,oolites2 and at the base of which we have respectively the ,gault1 ,kimmeridge clay1 ,oxford clay1 and ,lias4 ,this last forms1 generally1 a broad vale at the foot of the escarpment of inferior oolite1 but where it acquires considerable thickness1 and contains solid beds of marlstone1 it occupies the lower part of the escarpment4 ,the external outline of the country which the geologist observes in travelling eastward from ,paris to ,metz is precisely analogous1 and is caused by a similar succession of rocks intervening between the tertiary strata and the ,lias2 with this difference1 however1 that the escarpments of ,chalk1 ,upper1 ,middle1 and ,lower ,oolites1 face towards the east instead of the west4 ,the ,chalk crops out from beneath the tertiary sands and clays of the ,paris basin1 near ,epernay1 and the ,gault from beneath the ,chalk and ,upper ,greensand at ,clermont-en-,argonne2 and passing from this place by ,verdun and ,etain to ,metz1 we find two limestone ranges1 with intervening vales of clay1 precisely resembling those of southern and central ,england1 until we reach the great plain of ,lias at the base of the ,inferior ,oolite at ,metz4 ,it is evident1 therefore1 that the denuding causes have acted similarly over an area several hundred miles in diameter1 sweeping away the softer clays more extensively than the limestones1 and undermining these last so as to cause them to form steep cliffs wherever the harder calcareous rock was based upon a more yielding and destructible clay4 ,this denudation probably occurred while the land was slowly rising out of the sea4#bei-;,a ,upper ,oolite4 ,the ,portland stone has already been mentioned as forming in ,dorsetshire the foundation on which the freshwater limestone of the ,lower ,purbeck reposes 7see p4 #bcb474 ,it supplies the well-known building stone of which ,st4 ,paul's and so many of the principal edifices of ,london are constructed4 ,this upper member1 characterized by peculiar marine fossils1 rests on a dense bed of sand1 called the ,portland sand1 below which is the ,kimmeridge clay4 ,in ,england these ,upper ,oolite formations are almost wholly confined to the southern counties4 ,corals are rare in them1 although one species is found plentifully at ,tisbury1 in ,wiltshire1 in the ,portland sand converted into flint and chert1 the original calcareous matter being replaced by silex 7fig4 #bfg474 ,illustration3 ,fig4 #bfg4 ,columnaria oblonga1 ,blainv4 ,as seen on a polished slab of chert from the sand of the ,upper ,oolite1 ,tisbury4 ,among the characteristic fossils of the ,upper ,oolite1 may be mentioned the ,ostrea deltoidea 7fig4 #bfi471 found in the ,kimmeridge clay throughout ,england and the north of ,france1 and also in ,scotland1 near ,brora4 ,the ,gryphaea virgula 7fig4 #bfh471 also met with in the same clay near ,oxford1 is so abundant in the ,upper ,oolite of parts of ,france as to have caused the deposit to be termed marnes a gryphees virgules4 ,near ,clermont1 in ,argonne1 a few leagues from ,st4 ,menehould1 where these indurated marls crop out from beneath the gault1 ,i have seen them1 on decomposing1 leave the surface of every ploughed field literally strewed over with this fossil oyster4 #b ,illustrations3 ,upper ,oolite3 ,kimmeridge clay4 #a_/d nat4 size4 ,fig4 #bfh4 ,gryphaea virgula4 ,fig4 #bfi4 ,ostrea deltoidea4 ,illustration3 ,fig4 #bgj4 ,trigonia gibbosa4 #a_/b nat4 size4 a4 the hinge4 ,portland ,oolite1 ,tisbury4 ,the ,kimmeridge clay consists1 in great part1 of a bituminous shale1 sometimes forming an impure coal several hundred feet in thickness4 ,in some places in ,wiltshire it much resembles peat2 and the bituminous matter may have been1 in part at least1 derived from the decomposition of vegetables4 ,but as impressions of plants are rare in these shales1 which contain ammonites1 oysters1 and other marine shells1 the bitumen may perhaps be of animal origin4 ,the celebrated lithographic stone of ,solenhofen1 in ,bavaria1 belongs to one of the upper divisions of the oolite1 and affords a remarkable example of the variety of fossils which may be preserved under favourable circumstances1 and what delicate impressions of the tender parts of certain animals and plants may be retained where the sediment is of extreme fineness4 ,although the number of testacea in this slate is small1 and the plants few1 and those all marine1 ,count ,munster had determined no less than #bcg species of fossils when ,i saw his collection in #ahcc2 and among them no less than seven species of flying lizards1 or pterodactyls1 six saurians1 three tortoises1 sixty species of fish1 forty-six of crustacea1 and twenty-six of insects4 ,these insects1 among which is a libellula1 or dragon-fly1 must have been blown out to sea1 probably from the same land to which the flying lizards1 and other contemporaneous reptiles1 resorted4 ,middle ,oolite4 ,coral ,rag4--,one of the limestones of the ,middle ,oolite has been called the ,coral ,rag1 because it consists1 in part1 of continuous beds of petrified corals1 for the most part retaining the position in which they grew at the bottom of the sea4 ,they belong chiefly to the genera ,caryophyllia 7fig4 #bga471 ,agaricia1 and ,astrea1 and sometimes form masses of coral #ae feet thick4 ,in the annexed figure of an ,astrea1 from this formation1 it will be seen that the cup-shaped cavities are deepest on the right-hand side1 and that they grow more and more shallow1 till those on the left side are nearly filled up4 ,the last-named stars are supposed to be ,polyparia of advanced age4 ,these coralline strata extend through the calcareous hills of the ,n4,w4 of ,berkshire1 and north of ,wilts1 and again recur in ,yorkshire1 near ,scarborough4 ,illustration3 ,fig4 #bga4 ,caryophyllia annularis1 ,parkin4 ,coral rag1 ,steeple ,ashton4 ,illustration3 ,fig #bgb4 ,astrea4 ,coral rag4 ,one of the limestones of the ,jura1 referred to the age of the ,english coral rag1 has been called ,nerinaean limestone 7,calcaire a ,nerinees7 by ,m4 ,thirria2 ,nerinaea being an extinct genus of univalve shells1 much resembling the ,cerithium in external form4 ,the annexed section 7fig4 #bgc47 shows the curious form of the hollow part of each whorl1 and also the perforation which passes up the middle of the columella4 ,n4 ,goodhallii 7fig4 #bgd47 is another ,english species of the same genus1 from a formation which seems to form a passage from the ,kimmeridge clay to the coral rag4#bfa-;,a ,illustration3 ,fig4 #bgc4 ,nerinaea hieroglyphica4 ,coral rag4 ,illustration3 ,fig4 #bgd4 ,nerinaea ,goodhallii1 ,fitton4 ,coral rag1 ,weymouth4 #a_/d nat4 size4 ,a division of the oolite in the ,alps1 regarded by most geologists as coeval with the ,english coral rag1 has been often named ,calcaire a ,dicerates1 or ,diceras limestone1 from its containing abundantly a bivalve shell 7see fig4 #bge47 of a genus allied to the ,chama4 ,illustration3 ,fig4 #bge4 ,cast of ,diceras arietina4 ,coral rag1 ,france4 ,illustration3 ,fig4 #bgf4 ,cidaris coronata4 ,coral rag4 ,oxford ,clay4--,the coralline limestone1 or coral rag1 above described1 and the accompanying sandy beds1 called calcareous grits of the ,middle ,oolite1 rests on a thick bed of clay1 called the ,oxford clay1 sometimes not less than #ejj feet thick4 ,in this there are no corals1 but great abundance of cephalopoda of the genera ,ammonite and ,belemnite4 7,see fig4 #bgg47 ,in some of the clay of very fine texture ammonites are very perfect1 although somewhat compressed1 and are seen to be furnished on each side of the aperture with a single horn-like projection 7see fig4 #bgh474 ,these were discovered in the cuttings of the ,great ,western ,railway1 near ,chippenham1 in #ahda1 and have been described by ,mr4 ,pratt4#bfb-;,a ,illustration3 ,fig4 #bgg4 ,belemnites hastatus4 ,oxford ,clay4 ,illustration3 ,fig4 #bgh4 ,ammonites ,jason1 ,reinecke4 ,syn4 ,a4 ,elizabethae1 ,pratt4 ,oxford clay1 ,christian ,malford1 ,wiltshire4 ,illustration3 ,fig4 #bgi4 ,belemnites ,puzosianus1 ,d',orb4 ,oxford ,clay1 ,christian ,malford4 a1 a4 projecting processes of the shell or phragmocone4 b1 c4 broken exterior of a conical shell called the phragmocone1 which is chambered within1 or composed of a series of shallow concave cells pierced by a siphuncle4 c1 d4 ,the guard or osselet1 which is commonly called the belemnite4 ,similar elongated processes have been also observed to extend from the shells of some belemnites discovered by ,dr4 ,mantell in the same clay 7see fig4 #bgi471 who1 by the aid of this and other specimens1 has been able to throw much light on the structure of this singular extinct form of cuttle-fish4#bfc-;,a ,lower ,oolite4 ,the upper division of this series1 which is more extensive than the preceding or ,middle ,oolite1 is called in ,england the ,cornbrash4 ,it consists of clays and calcareous sandstones1 which pass downwards into the ,forest marble1 an argillaceous limestone1 abounding in marine fossils4 ,in some places1 as at ,bradford1 this limestone is replaced by a mass of clay4 ,the sandstones of the ,forest ,marble of ,wiltshire are often ripple-marked and filled with fragments of broken shells and pieces of drift-wood1 having evidently been formed on a coast4 ,rippled slabs of fissile oolite are used for roofing1 and have been traced over a broad band of country from ,bradford1 in ,wilts1 to ,tetbury1 in ,gloucestershire4 ,these calcareous tile-stones are separated from each other by thin seams of clay1 which have been deposited upon them1 and have taken their form1 preserving the undulating ridges and furrows of the sand in such complete integrity1 that the impressions of small footsteps1 apparently of crabs1 which walked over the soft wet sands1 are still visible4 ,in the same stone the claws of crabs1 fragments of echini1 and other signs of a neighbouring beach are observed4#bfc-;,b ,great ,oolite4--,although the name of coral-rag has been appropriated1 as we have seen1 to a member of the ,upper ,oolite before described1 some portions of the ,lower ,oolite are equally intitled in many places to be called coralline limestones4 ,thus the ,great ,oolite near ,bath contains various corals1 among which the ,eunomia radiata 7fig4 #bhj47 is very conspicuous1 single individuals forming masses several feet in diameter2 and having probably required1 like the large existing brain-coral 7,meandrina7 of the tropics1 many centuries before their growth was completed4 ,illustration3 ,fig4 #bhj4 ,eunomia radiata1 ,lamouroux4 a4 section transverse to the tubes4 b4 vertical section1 showing the radiation of the tubes4 c4 portion of interior of tubes magnified1 showing striated surface4 ,illustration3 ,fig4 #bha4 ,apiocrinites rotundus1 or ,pear ,encrinite2 ,miller4 ,fossil at ,bradford1 ,wilts4 a4 ,stem of ,apiocrinites1 and one of the articulations1 natural size4 b4 ,section at ,bradford of great oolite and overlying clay1 containing the fossil encrinites4 ,see text4 c4 ,three perfect individuals of ,apiocrinites1 represented as they grew on the surface of the ,great ,oolite4 d4 ,body of the ,apiocrinites rotundus4 ,different species of ,crinoideans1 or stone-lilies1 are also common in the same rocks with corals2 and1 like them1 must have enjoyed a firm bottom1 where their root1 or base of attachment1 remained undisturbed for years 7c1 fig4 #bha474 ,such fossils1 therefore1 are almost confined to the limestones2 but an exception occurs at ,bradford1 near ,bath1 where they are enveloped in clay4 ,in this case1 however1 it appears that the solid upper surface of the ,great ,oolite had supported1 for a time1 a thick submarine forest of these beautiful zoophytes1 until the clear and still water was invaded by a current charged with mud1 which threw down the stone-lilies1 and broke most of their stems short off near the point of attachment4 ,the stumps still remain in their original position2 but the numerous articulations once composing the stem1 arms1 and body of the zoophyte1 were scattered at random through the argillaceous deposit in which some now lie prostrate4 ,these appearances are represented in the section b1 fig4 #bha41 where the darker strata represent the ,bradford clay1 which some geologists class with the ,forest marble1 others with the ,great ,oolite4 ,the upper surface of the calcareous stone below is completely incrusted over with a continuous pavement1 formed by the stony roots or attachments of the ,crinoidea2 and besides this evidence of the length of time they had lived on the spot1 we find great numbers of single joints1 or circular plates of the stem and body of the encrinite1 covered over with serpulae4 ,now these serpulae could only have begun to grow after the death of some of the stone-lilies1 parts of whose skeletons had been strewed over the floor of the ocean before the irruption of argillaceous mud4 ,in some instances we find that1 after the parasitic serpulae were full grown1 they had become incrusted over with a coral1 called ,berenicea diluviana2 and many generations of these polyps had succeeded each other in the pure water before they became fossil4 ,illustration3 ,fig4 #bhb4 a4 ,single plate or articulation of an ,encrinite overgrown with serpulae and corals4 ,natural size ,bradford clay4 b4 ,portion of the same magnified1 showing the coral ,berenicea diluviana covering one of the serpulae4 ,we may1 therefore1 perceive distinctly that1 as the pines and cycadeous plants of the ancient dirt bed1 or fossil forest1 of the ,lower ,purbeck were killed by submergence under fresh water1 and soon buried beneath muddy sediment1 so an invasion of argillaceous matter put a sudden stop to the growth of the ,bradford ,encrinites1 and led to their preservation in marine strata4#bfe-;,a ,such differences in the fossils as distinguish the calcareous and argillaceous deposits from each other1 would be described by naturalists as arising out of a difference in the stations of species2 but besides these1 there are variations in the fossils of the higher1 middle1 and lower part of the oolitic series1 which must be ascribed to that great law of change in organic life by which distinct assemblages of species have been adapted1 at successive geological periods1 to the varying conditions of the habitable surface4 ,in a single district it is difficult to decide how far the limitation of species to certain minor formations has been due to the local influence of stations1 or how far it has been caused by time or the creative and destroying law above alluded to4 ,but we recognize the reality of the last-mentioned influence1 when we contrast the whole oolitic series of ,england with that of parts of the ,jura1 ,alps1 and other distant regions1 where there is scarcely any lithological resemblance2 and yet some of the same fossils remain peculiar in each country to the ,upper1 ,middle1 and ,lower ,oolite formations respectively4 ,mr4 ,thurmann has shown how remarkably this fact holds true in the ,bernese ,jura1 although the argillaceous divisions1 so conspicuous in ,england1 are feebly represented there1 and some entirely wanting4 ,illustration3 ,fig4 #bhc4 ,terebratula digona4 ,bradford clay4 ,nat4 size4 ,the ,bradford clay above alluded to is sometimes #fj feet thick1 but1 in many places1 it is wanting2 and1 in others1 where there are no limestones1 it cannot easily be separated from the clays of the overlying forest marble and underlying fuller's earth4 ,the calcareous portion of the ,great ,oolite consists of several shelly limestones1 one of which1 called the ,bath ,oolite1 is much celebrated as a building stone4 ,in parts of ,gloucestershire1 especially near ,minchinhampton1 the ,great ,oolite1 says ,mr4 ,lycett1 must have been deposited in a shallow sea1 where strong currents prevailed1 for there are frequent changes in the mineral character of the deposit1 and some beds exhibit false stratification4 ,in others1 heaps of broken shells are mingled with pebbles of rocks foreign to the neighbourhood1 and with fragments of abraded madrepores1 dicotyledonous wood1 and crabs' claws4 ,the shelly strata1 also1 have occasionally suffered denudation1 and the removed portions have been replaced by clay4#bff-;,a ,in such shallow-water beds cephalopoda are rare1 and1 instead of ammonites and belemnites1 numerous genera of carnivorous trachelipods appear4 ,out of one hundred and forty-two species of univalves obtained from the ,minchinhampton beds1 ,mr4 ,lycett found no less than forty-one to be carnivorous4 ,they belong principally to the genera ,buccinum1 ,pleurotoma1 ,rostellaria1 ,murex1 and ,fusus1 and exhibit a proportion of zoophagous species not very different from that which obtains in warm seas of the recent period4 ,these conchological results are curious and unexpected1 since it was imagined that we might look in vain for the carnivorous trachelipods in rocks of such high antiquity as the ,great ,oolite1 and it was a received doctrine that they did not begin to appear in considerable numbers till the ,eocene period when those two great families of cephalopoda1 the ammonites and belemnites1 had become extinct4 ,stonesfield slate4--,the slate of ,stonesfield has been shown by ,mr4 ,lonsdale to lie at the base of the ,great ,oolite4#bff-;,b ,it is a slightly oolitic shelly limestone1 forming large spheroidal masses imbedded in sand1 only #f feet thick1 but very rich in organic remains4 ,it contains some pebbles of a rock very similar to itself1 and which may be portions of the deposit1 broken up on a shore at low water or during storms1 and redeposited4 ,the remains of belemnites1 trigoniae1 and other marine shells1 with fragments of wood1 are common1 and impressions of ferns1 cycadeae1 and other plants4 ,several insects1 also1 and1 among the rest1 the wing-covers of beetles1 are perfectly preserved 7see fig4 #bhd471 some of them approaching nearly to the genus ,buprestis4#bfg-;,a ,the remains1 also1 of many genera of reptiles1 such as ,plesiosaur1 ,crocodile1 and ,pterodactyl1 have been discovered in the same limestone4 ,illustration3 ,fig4 #bhd4 ,elytron of ,buprestis8 ,stonesfield4 ,illustration3 ,fig4 #bhe4 ,bone of a reptile1 formerly supposed to be the ulna of a ,cetacean2 from the ,great ,oolite of ,enstone1 near ,woodstock4 ,but the remarkable fossils for which the ,stonesfield slate is most celebrated1 are those referred to the mammiferous class4 ,the student should be reminded that in all the rocks described in the preceding chapters as older than the ,eocene1 no bones of any land quadruped1 or of any cetacean1 have been discovered4 ,yet we have seen that terrestrial plants were not rare in the lower cretaceous formation1 and that in the ,wealden there was evidence of freshwater sediment on a large scale1 containing various plants1 and even ancient vegetable soils with the roots and erect stumps of trees4 ,we had also in the same ,wealden many land-reptiles and winged-insects1 which renders the absence of terrestrial quadrupeds the more striking4 ,the want1 however1 of any bones of whales1 seals1 dolphins1 and other aquatic mammalia1 whether in the chalk or in the upper or middle oolite1 is certainly still more remarkable4 ,formerly1 indeed1 a bone from the great oolite of ,enstone1 near ,woodstock1 in ,oxfordshire1 was cited1 on the authority of ,cuvier1 as referable to this class4 ,dr4 ,buckland1 who stated this in his ,bridgewater ,treatise#bfg-;,b1 had the kindness to send me the supposed ulna of a whale1 that ,mr4 ,owen might examine into its claims to be considered as cetaceous4 ,it is the opinion of that eminent comparative anatomist that it cannot have belonged to the cetacea1 because the fore-arm in these marine mammalia is invariably much flatter1 and devoid of all muscular depressions and ridges1 one of which is so prominent in the middle of this bone1 represented in the above cut 7fig4 #bhe474 ,in saurians1 on the contrary1 such ridges exist for the attachment of muscles2 and to some animal of that class the bone is probably referable4 ,illustration3 ,fig4 #bhf4 ,amphitherium ,prevostii4 ,stonesfield ,slate4 ,natural size4 a4 coronoid process4 b4 condyle4 c4 angle of jaw4 d4 double-fanged molars4 ,these observations are made to prepare the reader to appreciate more justly the interest felt by every geologist in the discovery in the ,stonesfield slate of no less than seven specimens of lower jaws of mammiferous quadrupeds1 belonging to three different species and to two distinct genera1 for which the names of ,amphitherium and ,phascolotherium have been adopted4 ,when ,cuvier was first shown one of these fossils in #ahah1 he pronounced it to belong to a small ferine mammal1 with a jaw much resembling that of an opossum1 but differing from all known ferine genera1 in the great number of the molar teeth1 of which it had at least ten in a row4 ,since that period1 a much more perfect specimen of the same fossil1 obtained by ,dr4 ,buckland 7see fig4 #bhf471 has been examined by ,mr4 ,owen1 who finds that the jaw contained on the whole twelve molar teeth1 with the socket of a small canine1 and three small incisors1 which are in situ1 altogether amounting to sixteen teeth on each side of the lower jaw4 ,illustration3 ,fig4 #bhg4 ,amphitherium ,broderipii4 ,natural size4 ,stonesfield ,slate4 ,the only question which could be raised respecting the nature of these fossils was1 whether they belonged to a mammifer1 a reptile1 or a fish4 ,now on this head the osteologist observes that each of the seven half jaws is composed of but one single piece1 and not of two or more separate bones1 as in fishes and most reptiles1 or of two bones1 united by a suture1 as in some few species belonging to those classes4 ,the condyle1 moreover 7b1 fig4 #bhf471 or articular surface1 by which the lower jaw unites with the upper1 is convex in the ,stonesfield specimens1 and not concave as in fishes and reptiles4 ,the coronoid process 7a1 fig4 #bhf47 is well developed1 whereas it is wanting or very small1 in the inferior classes of vertebrata4 ,lastly1 the molar teeth in the ,amphitherium and ,phascolotherium have complicated crowns1 and two roots 7see d1 fig4 #bhf471 instead of being simple and with single fangs4#bfi-;,a ,illustration3 ,fig4 #bhh4 ,tupaia ,tana4 ,right ramus of lower jaw1 natural size4 ,a recent insectivorous mammal from ,sumatra4 #b ,illustrations3 ,part of lower jaw of ,tupaia ,tana2 twice natural size4 ,fig4 #bhi4 ,end view seen from behind1 showing the very slight inflection of the angle at c4 ,fig4 #bij4 ,side view of same4 #b ,illustrations3 ,part of lower jaw of ,didelphis ,azarae2 recent1 ,brazil4 ,natural size4 ,fig4 #bia4 ,end view seen from behind1 showing the inflection of the angle of the jaw1 c4 d4 ,fig4 #bib4 ,side view of same4 ,the only question1 therefore1 which could fairly admit of controversy was limited to this point1 whether the fossil mammalia found in the lower oolite of ,oxfordshire ought to be referred to the marsupial quadrupeds1 or to the ordinary placental series4 ,cuvier had long ago pointed out a peculiarity in the form of the angular process 7c1 figs4 #bia4 and #bib47 of the lower jaw1 as a character of the genus ,didelphys2 and ,mr4 ,owen has since established its generality in the entire marsupial series4 ,in all these pouched quadrupeds1 this process is turned inwards1 as at c d1 fig4 #bia4 in the ,brazilian opossum1 whereas in the placental series1 as at c1 figs4 #bij4 and #bhi4 there is an almost entire absence of such inflection4 ,the ,tupaia ,tana of ,sumatra has been selected by my friend ,mr4 ,waterhouse1 for this illustration1 because that small insectivorous quadruped bears a great resemblance to those of the ,stonesfield ,amphitherium4 ,by clearing away the matrix from the specimen of ,amphitherium ,prevostii above represented 7fig4 #bhf471 ,mr4 ,owen ascertained that the angular process 7c7 bent inwards in a slighter degree than in any of the known marsupialia2 in short1 the inflection does not exceed that of the mole or hedgehog4 ,this fact turns the scale in favour of its affinities to the placental insectivora4 ,nevertheless1 the ,amphitherium offers some points of approximation in its osteology to the marsupials1 especially to the ,myrmecobius1 a small insectivorous quadruped of ,australia1 which has nine molars on each side of the lower jaw1 besides a canine and three incisors4#bfi-;,b ,another species of ,amphitherium has been found at ,stonesfield 7fig4 #bhg4 p4 #bfh471 which differs from the former 7fig4 #bhf47 principally in being larger4 ,illustration3 ,fig4 #bic4 ,phascolotherium ,bucklandi1 ,owen4 a4 natural size4 b4 molar of same magnified4 ,the second mammiferous genus discovered in the same slates was named originally by ,mr4 ,broderip ,didelphys ,bucklandi 7see fig4 #bic471 and has since been called ,phascolotherium by ,owen4 ,it manifests a much stronger likeness to the marsupials in the general form of the jaw1 and in the extent and position of its inflected angle1 while the agreement with the living genus ,didelphys in the number of the premolar and molar teeth1 is complete4#bgj-;,a ,on reviewing1 therefore1 the whole of the osteological evidence1 it will be seen that we have every reason to presume that the ,amphitherium and ,phascolotherium of ,stonesfield represent both the placental and marsupial classes of mammalia2 and if so1 they warn us in a most emphatic manner1 not to found rash generalizations respecting the non-existence of certain classes of animals at particular periods of the past1 on mere negative evidence4 ,the singular accident of our having as yet found nothing but the lower jaws of seven individuals1 and no other bones of their skeletons1 is alone sufficient to demonstrate the fragmentary manner in which the memorials of an ancient terrestrial fauna are handed down to us4 ,we can scarcely avoid suspecting that the two genera above described1 may have borne a like insignificant proportion to the entire assemblage of warm-blooded quadrupeds which flourished in the islands of the oolitic sea4 ,mr4 ,owen has remarked that as the marsupial genera1 to which the ,phascolotherium is most nearly allied1 are now confined to ,new ,south ,wales and ,van ,diemen's ,land1 so also is it in the ,australian seas1 that we find the ,cestracion1 a cartilaginous fish which has a bony palate1 allied to those called ,acrodus and ,psammodus 7see figs4 #cjg1 #cjh4 p4 #bge471 so common in the oolite and lias4 ,in the same ,australian seas1 also1 near the shore1 we find the living ,trigonia1 a genus of mollusca so frequently met with in the ,stonesfield slate4 ,so1 also1 the ,araucarian pines are now abundant1 together with ferns1 in ,australia and its islands1 as they were in ,europe in the oolitic period4 ,many botanists incline to the opinion1 that the ,thuja1 ,pine1 ,cycas1 ,zamia1 in short1 all the gymnogens1 belong to a less highly developed type of flowering plants than do the exogens2 but even if this be admitted1 no naturalist can ascribe a low standard of organization to the oolitic flora1 since we meet with endogens of the most perfect structure in oolitic rocks1 both above and below the ,stonesfield slate1 as1 for example1 the ,podocarya of ,buckland1 a fruit allied to the ,pandanus1 found in the ,inferior ,oolite 7see fig4 #bid471 and the ,carpolithes conica of the ,coral rag4 ,the doctrine1 therefore1 of a regular series of progressive development at successive eras in the animal and vegetable kingdoms1 from beings of a more simple to those of a more complex organization1 receives a check1 if not a refutation1 from the facts revealed to us by the study of the ,lower ,oolites4 ,illustration3 ,fig4 #bid4 ,portion of a fossil fruit of ,podocarya magnified4 7,buckland's ,bridgew4 ,treat4 ,pl4 #fc47 ,inferior ,oolite1 ,charmouth1 ,dorset4 ,the ,stonesfield slate1 in its range from ,oxfordshire to the north-east1 is represented by flaggy and fissile sandstones1 as at ,collyweston in ,northamptonshire1 where1 according to the researches of ,messrs4 ,ibbetson and ,morris1 it contains many shells1 such as ,trigonia angulata1 also found at ,stonesfield4 ,but the ,northamptonshire strata of this age assume a more marine character1 or appear at least to have been formed farther from land4 ,they inclose1 however1 some fossil ferns1 such as ,pecopteris polypodioides1 of species common to the oolites of the ,yorkshire coast#bga-;,a1 where rocks of this age put on all the aspect of a true coal-field2 thin seams of coal having actually been worked in them for more than a century4 ,illustration3 ,fig4 #bie4 ,pterophyllum comptum4 7,syn4 ,cycadites comptus47 ,upper sandstone and shale1 ,gristhorpe1 near ,scarborough4 ,in the north-west of ,yorkshire1 the formation alluded to consists of an upper and a lower carbonaceous shale1 abounding in impressions of plants1 divided by a limestone considered by many geologists as the representative of the ,great ,oolite2 but the scarcity of marine fossils makes all comparisons with the subdivisions adopted in the south extremely difficult4 ,a rich harvest of fossil ferns has been obtained from the upper carbonaceous shales and sandstones at ,gristhorpe1 near ,scarborough 7see figs4 #bie1 #bif474 ,the lower shales are well exposed in the sea-cliffs at ,whitby1 and are chiefly characterized by ferns and cycadeae4 ,they contain1 also1 a species of calamite1 and a fossil called ,equisetum columnare1 which maintains an upright position in sandstone strata over a wide area4 ,shells of the genus ,cypris and ,unio1 collected by ,mr4 ,bean from these ,yorkshire coal-bearing beds1 point to the estuary or fluviatile origin of the deposit4 ,illustration3 ,fig4 #bif4 ,hemitelites ,brownii1 ,goepp4 ,syn4 ,phlebopteris contigua1 ,lind4 ,hutt4 ,upper carbonaceous strata1 ,lower ,oolite1 ,gristhorpe1 ,yorkshire4 ,at ,brora1 in ,sutherlandshire1 a coal formation1 probably coeval with the above1 or belonging to some of the lower divisions of the ,oolitic period1 has been mined extensively for a century or more4 ,it affords the thickest stratum of pure vegetable matter hitherto detected in any secondary rock in ,england4 ,one seam of coal of good quality has been worked #c-a_/b feet thick1 and there are several feet more of pyritous coal resting upon it4 ,inferior ,oolite4--,between the ,great and ,inferior ,oolite1 near ,bath1 an argillaceous deposit called the fuller's earth1 occurs1 but is wanting in the north of ,england4 ,the ,inferior ,oolite is a calcareous freestone1 usually of small thickness1 which sometimes rests upon1 or is replaced by1 yellow sands1 called the sands of the ,inferior ,oolite4 ,these last1 in their turn1 repose upon the lias in the south and west of ,england4 ,among the characteristic shells of the ,inferior ,oolite1 ,i may instance ,terebratula spinosa 7fig4 #big471 and ,pholadomya fidicula 7fig4 #bih474 ,the extinct genus ,pleurotomaria is also a form very common in this division as well as in the ,oolitic system generally4 ,it resembles the ,trochus in form1 but is marked by a singular cleft 7a1 fig4 #bii47 on the right side of the mouth4 ,illustration3 ,fig4 #big4 ,terebratula spinosa4 ,inferior ,oolite4 ,illustration3 ,fig4 #bih4 a4 ,pholadomya fidicula1 #a_/c nat4 size4 ,inf4 ,ool4 b4 ,heart-shaped anterior termination of the same4 ,illustration3 ,fig4 #bii4 ,pleurotomaria ornata4 ,ferruginous ,oolite1 ,normandy4 ,inferior ,oolite1 ,england4 ,as illustrations of shells having a great vertical range1 ,i may allude to ,trigonia clavellata1 found in the ,upper and ,inferior ,oolite1 and ,t4 costata1 common to the ,upper1 ,middle1 and ,lower ,oolite2 also ,ostrea ,marshii 7fig4 #cjj471 common to the ,cornbrash of ,wilts and the ,inferior ,oolite of ,yorkshire2 and ,ammonites striatulus 7fig4 #cja47 common to the ,inferior ,oolite and ,lias4 ,illustration3 ,fig4 #cjj4 ,ostrea ,marshii4 #a_/b nat4 size4 ,middle and ,lower ,oolite4 ,illustration3 ,fig4 #cja4 ,ammonites striatulus1 ,sow4 #a_/c nat4 size4 ,inferior ,oolite and ,lias4 ,such facts by no means invalidate the general rule1 that certain fossils are good chronological tests of geological periods2 but they serve to caution us against attaching too much importance to single species1 some of which may have a wider1 others a more confined vertical range4 ,we have before seen that1 in the successive tertiary formations1 there are species common to older and newer groups1 yet these groups are distinguishable from one another by a comparison of the whole assemblage of fossil shells proper to each4 ,,footnotes3 #bei-;,a ,see ,chapters ,,vi4 and ,,xix4 #bfa-;,a ,fitton1 ,geol4 ,trans41 ,second ,series1 vol4 iv4 pl4 #bc4 fig4 #ab4 #bfb-;,a ,s4 ,p4 ,pratt1 ,annals of ,nat4 ,hist41 ,november1 #ahda4 #bfc-;,a ,see ,phil4 ,trans4 #ahej1 p4 #cic4 #bfc-;,b ,p4 ,scrope1 ,geol4 ,proceed41 ,march1 #ahca4 #bfe-;,a ,for a fuller account of these ,encrinites1 see ,buckland's ,bridgewater ,treatise1 vol4 i4 p4 #dbi4 #bff-;,a ,lycett1 ,quart4 ,geol4 ,journ4 vol4 iv4 p4 #ahc4 #bff-;,b ,proceedings ,geol4 ,soc4 vol4 i4 p4 #dad4 #bfg-;,a ,see ,buckland's ,bridgewater ,treatise2 and ,brodie's ,fossil ,insects1 where it is suggested that these elytra may belong to ,priomus4 #bfg-;,b ,vol4 i4 p4 #aae4 #bfi-;,a ,i have given a figure in the ,principles of ,geology1 chap4 ix41 of another ,stonesfield specimen of ,amphitherium ,prevostii1 in which the sockets and roots of the teeth are finely exposed4 #bfi-;,b ,a figure of this recent ,myrmecobius will be found in the ,principles1 chap4 ix4 #bgj-;,a ,owen's ,british ,fossil ,mammals1 p4 #fb4 #bga-;,a ,ibbetson and ,morris1 ,report of ,brit4 ,ass41 #ahdg1 p4 #aca4 ,,chapter ,,xxi4 ,,oolite ,,and ,,lias--continued4 ,mineral character of ,lias--,name of ,gryphite limestone--,fossil shells and fish--,ichthyodorulites--,reptiles of the ,lias--,ichthyosaur and ,plesiosaur--,marine ,reptile of the ,galapagos ,islands--,sudden destruction and burial of fossil animals in ,lias--,fluvio-marine beds in ,gloucestershire and insect limestone--,origin of the ,oolite and ,lias1 and of alternating calcareous and argillaceous formations--,oolitic coal-field of ,virginia1 in the ,united ,states4 ,,lias4--,the ,english provincial name of ,lias has been very generally adopted for a formation of argillaceous limestone1 marl1 and clay1 which forms the base of the ,oolite1 and is classed by many geologists as part of that group4 ,they pass1 indeed1 into each other in some places1 as near ,bath1 a sandy marl called the marlstone of the ,lias being interposed1 and partaking of the mineral characters of the upper lias and inferior oolite4 ,these last-mentioned divisions have also some fossils in common1 such as the ,avicula inaequivalvis 7fig4 #cjb474 ,nevertheless the ,lias may be traced throughout a great part of ,europe as a separate and independent group1 of considerable thickness1 varying from #ejj to #ajjj feet1 containing many peculiar fossils1 and having a very uniform lithological aspect4 ,although usually conformable to the oolite1 it is sometimes1 as in the ,jura1 unconformable4 ,in the environs of ,lons-le-,saulnier1 for instance1 in the department of ,jura1 the strata of lias are inclined at an angle of about #de deg41 while the incumbent oolitic marls are horizontal4 ,illustration3 ,fig4 #cjb4 ,avicula inaequivalvis1 ,sow4 ,the peculiar aspect which is most characteristic of the ,lias in ,england1 ,france1 and ,germany1 is an alternation of thin beds of blue or grey limestone with a surface becoming light-brown when weathered1 these beds being separated by dark-coloured narrow argillaceous partings1 so that the quarries of this rock1 at a distance1 assume a striped and riband-like appearance4#bgd-;,a ,although the prevailing colour of the limestone of this formation is blue1 yet some beds of the lower lias are of a yellowish white colour1 and have been called white lias4 ,in some parts of ,france1 near the ,vosges mountains1 and in ,luxembourg1 ,m4 ,e4 de ,beaumont has shown that the lias containing ,gryphaea arcuata1 ,plagiostoma giganteum 7see fig4 #cjc471 and other characteristic fossils1 becomes arenaceous2 and around the ,hartz1 in ,westphalia and ,bavaria1 the inferior parts of the lias are sandy1 and sometimes afford a building stone4 ,illustration3 ,fig4 #cjc4 ,plagiostoma giganteum4 ,lias4 ,illustration3 ,fig4 #cjd4 ,gryphaea incurva1 ,sow4 7,g4 arcuata1 ,lam47 ,illustration3 ,fig4 #cje4 ,nautilus truncatus4 ,lias4 ,the name of ,gryphite limestone has sometimes been applied to the lias1 in consequence of the great number of shells which it contains of a species of oyster1 or ,gryphaea 7fig4 #cjd41 see also fig4 #cj4 p4 #bi474 ,many cephalopoda1 also1 such as ,ammonite1 ,belemnite1 and ,nautilus 7fig4 #cje471 prove the marine origin of the formation4 ,illustration3 ,fig4 #cjf4 ,scales of ,lepidotus gigas1 ,agas4 a4 two of the scales detached4 ,the fossil fish resemble generically those of the oolite1 belonging all1 according to ,m4 ,agassiz1 to extinct genera1 and differing remarkably from the ichthyolites of the ,cretaceous period4 ,among them is a species of ,lepidotus 7,l4 gigas1 ,agas47 7fig4 #cjf471 which is found in the lias of ,england1 ,france1 and ,germany4#bge-;,a ,this genus was before mentioned 7p4 #bbi47 as occurring in the ,wealden1 and is supposed to have frequented both rivers and coasts4 ,the teeth of a species of ,acrodus1 also1 are very abundant in the lias 7fig4 #cjg474 ,illustration3 ,fig4 #cjg4 ,acrodus nobilis1 ,agas4 7tooth72 commonly called fossil leach4 ,lias1 ,lyme ,regis1 and ,germany4 ,illustration3 ,fig4 #cjh4 ,hybodus reticulatus1 ,agas4 ,lias1 ,lyme ,regis4 a4 ,part of fin1 commonly called ,ichthyodorulite4 b4 ,tooth4 ,but the remains of fish which have excited more attention than any others1 are those large bony spines called ichthyodorulites 7a1 fig4 #cjh471 which were once supposed by some naturalists to be jaws1 and by others weapons1 resembling those of the living ,balistes and ,silurus2 but which ,m4 ,agassiz has shown to be neither the one nor the other4 ,the spines1 in the genera last mentioned1 articulate with the backbone1 whereas there are no signs of any such articulation in the ichthyodorulites4 ,these last appear to have been bony spines which formed the anterior part of the dorsal fin1 like that of the living genera ,cestracion and ,chimaera 7see a1 fig4 #cji474 ,in both of these genera1 the posterior concave face is armed with small spines like that of the fossil ,hybodus 7fig4 #cjh471 one of the shark family found fossil at ,lyme ,regis4 ,such spines are simply imbedded in the flesh1 and attached to strong muscles4 ,they serve1 says ,dr4 ,buckland1 as in the ,chimaera 7fig4 #cji471 to raise and depress the fin1 their action resembling that of a moveable mast1 raising and lowering backwards the sail of a barge4#bgf-;,a ,illustration3 ,fig4 #cji4 ,chimaera monstrosa4#bgf-;,b a4 ,spine forming anterior part of the dorsal fin4 ,reptiles of the ,lias4--,it is not1 however1 the fossil fish which form the most striking feature in the organic remains of the ,lias2 but the reptiles1 which are extraordinary for their number1 size1 and structure4 ,among the most singular of these are several species of ,ichthyosaurus and ,plesiosaurus4 ,the genus ,ichthyosaurus1 or fish-lizard1 is not confined to this formation1 but has been found in strata as high as the chalk-marl and gault of ,england1 and as low as the muschelkalk of ,germany1 a formation which immediately succeeds the lias in the descending order4#bgf-;,c ,it is evident from their fish-like vertebrae1 their paddles1 resembling those of a porpoise or whale1 the length of their tail1 and other parts of their structure1 that the habits of the ,ichthyosaurs were aquatic4 ,their jaws and teeth show that they were carnivorous2 and the half-digested remains of fishes and reptiles1 found within their skeletons1 indicate the precise nature of their food4#bgf-;,d ,a specimen of the hinder fin or paddle of ,ichthyosaurus communis was discovered in #ahdj at ,barrow-on-,soar1 by ,sir ,p4 ,egerton1 which distinctly exhibits on its posterior margin the remains of cartilaginous rays that bifurcate as they approach the edge1 like those in the fin of a fish 7see a1 fig4 #cab474 ,it had previously been supposed1 says ,mr4 ,owen1 that the locomotive organs of the ,ichthyosaurus were enveloped1 while living1 in a smooth integument1 like that of the turtle and porpoise1 which has no other support than is afforded by the bones and ligaments within2 but it now appears that the fin was much larger1 expanding far beyond its osseous framework1 and deviating widely in its fish-like rays from the ordinary reptilian type4 ,in fig4 #cab4 the posterior bones1 or digital ossicles of the paddle1 are seen near b2 and beyond these is the dark carbonized integument of the terminal half of the fin1 the outline of which is beautifully defined4#bgg-;,a ,mr4 ,owen believes that1 besides the fore-paddles1 these short-and stiff-necked saurians were furnished with a tail-fin without bones and purely tegumentary1 expanding in a vertical direction2 an organ of motion which enabled them to turn their heads rapidly4#bgg-;,b ,illustration3 ,fig4 #caj4 ,ichthyosaurus communis1 restored by ,conybeare and ,cuvier4 a4 costal vertebrae4 ,illustration3 ,fig4 #caa4 ,plesiosaurus dolichodeirus1 restored by ,rev4 ,w4 ,d4 ,conybeare4 a4 cervical vertebra4 ,illustration3 ,fig4 #cab4 ,posterior part of hind fin or paddle of ,ichthyosaurus communis4 ,mr4 ,conybeare was enabled1 in #ahbd1 after examining many skeletons nearly perfect1 to give an ideal restoration of the osteology of this genus1 and of that of the ,plesiosaurus4#bgh-;,a 7,see figs4 #caj1 #caa47 ,the latter animal had an extremely long neck and small head1 with teeth like those of the crocodile1 and paddles analogous to those of the ,ichthyosaurus1 but larger4 ,it is supposed to have lived in shallow seas and estuaries1 and to have breathed air like the ,ichthyosaur1 and our modern cetacea4#bgh-;,b ,some of the reptiles above mentioned were of formidable dimensions4 ,one specimen of ,ichthyosaurus platyodon1 from the lias at ,lyme1 now in the ,british ,museum1 must have belonged to an animal more than #bd feet in length2 and another of the ,plesiosaurus1 in the same collection1 is #aa feet long4 ,the form of the ,ichthyosaurus may have fitted it to cut through the waves like the porpoise2 but it is supposed that the ,plesiosaurus1 at least the long-necked species 7fig4 #caa471 was better suited to fish in shallow creeks and bays defended from heavy breakers4 ,in many specimens both of ,ichthyosaur and ,plesiosaur the bones of the head1 neck1 and tail1 are in their natural position1 while those of the rest of the skeleton are detached and in confusion4 ,mr4 ,stutchburg has suggested that their bodies after death became inflated with gases1 and1 while the abdominal viscera were decomposing1 the bones1 though disunited1 were retained within the tough dermal covering as in a bag1 until the whole1 becoming water-logged1 sank to the bottom4#bgh-;,c ,as they belonged to individuals of all ages they are supposed1 by ,dr4 ,buckland1 to have experienced a violent death2 and the same conclusion might also be drawn from their having escaped the attacks of their own predaceous race1 or of fishes1 found fossil in the same beds4 ,illustration3 ,fig #cac4 ,amblyrhynchus cristatus1 ,bell4 ,length varying from #c to #d feet4 ,the only existing marine lizard now known4 a4 ,tooth1 natural size and magnified4 ,for the last twenty years1 anatomists have agreed that these extinct saurians must have inhabited the sea2 and it was argued that1 as there are now chelonians1 like the tortoise1 living in fresh water1 and others1 as the turtle1 frequenting the ocean1 so there may have been formerly some saurians proper to salt1 others to fresh water4 ,the common crocodile of the ,ganges is well known to frequent equally that river and the brackish and salt water near its mouth2 and crocodiles are said in like manner to be abundant both in the rivers of the ,isla de ,pinos 7or ,isle of ,pines71 south of ,cuba1 and in the open sea round the coast4 ,more recently a saurian has been discovered of aquatic habits and exclusively marine4 ,this creature was found in the ,galapagos ,islands1 during the visit of ,h4 ,m4 ,s4 ,beagle to that archipelago1 in #ahce1 and its habits were then observed by ,mr4 ,darwin4 ,the islands alluded to are situated under the equator1 nearly #fjj miles to the westward of the coast of ,south ,america4 ,they are volcanic1 some of them being #cjjj or #djjj feet high2 and one of them1 ,albemarle ,island1 #ge miles long4 ,the climate is mild2 very little rain falls2 and1 in the whole archipelago1 there is only one rill of fresh water that reaches the coast4 ,the soil is for the most part dry and harsh1 and the vegetation scanty4 ,the birds1 reptiles1 plants1 and insects are1 with very few exceptions1 of species found no where else in the world1 although all partake1 in their general form1 of a ,south ,american type4 ,of the mammalia1 says ,mr4 ,darwin1 one species alone appears to be indigenous1 namely1 a large and peculiar kind of mouse2 but the number of lizards1 tortoises1 and snakes is so great1 that it may be called a land of reptiles4 ,the variety1 indeed1 of species is small2 but the individuals of each are in wonderful abundance4 ,there is a turtle1 a large tortoise 7,testudo ,indicus71 four lizards1 and about the same number of snakes1 but no frogs or toads4 ,two of the lizards belong to the family ,iguanidae of ,bell1 and to a peculiar genus 7,amblyrhynchus7 established by that naturalist1 and so named from their obtusely truncated head and short snout4#bgi-;,a ,of these lizards one is terrestrial in its habits1 and burrows in the ground1 swarming everywhere on the land1 having a round tail1 and a mouth somewhat resembling in form that of the tortoise4 ,the other is aquatic1 and has its tail flattened laterally for swimming 7see fig4 #cac474 ,this marine saurian1 says ,mr4 ,darwin1 is extremely common on all the islands throughout the archipelago4 ,it lives exclusively on the rocky sea-beaches1 and ,i never saw one even ten yards inshore4 ,the usual length is about a yard1 but there are some even #d feet long4 ,it is of a dirty black colour1 sluggish in its movements on the land2 but1 when in the water1 it swims with perfect ease and quickness by a serpentine movement of its body and flattened tail1 the legs during this time being motionless1 and closely collapsed on its sides4 ,their limbs and strong claws are admirably adapted for crawling over the rugged and fissured masses of lava which everywhere form the coast4 ,in such situations1 a group of six or seven of these hideous reptiles may oftentimes be seen on the black rocks1 a few feet above the surf1 basking in the sun with outstretched legs4 ,their stomachs1 on being opened1 were found to be largely distended with minced sea-weed1 of a kind which grows at the bottom of the sea at some little distance from the coast4 ,to obtain this1 the lizards go out to sea in shoals4 ,one of these animals was sunk in salt water1 from the ship1 with a heavy weight attached to it1 and on being drawn up again after an hour it was quite active and unharmed4 ,it is not yet known by the inhabitants where this animal lays its eggs2 a singular fact1 considering its abundance1 and that the natives are well acquainted with the eggs of the terrestrial ,amblyrhynchus1 which is also herbivorous4#bhj-;,a ,in those deposits now forming by the sediment washed away from the wasting shores of the ,galapagos ,islands the remains of saurians1 both of the land and sea1 as well as of chelonians and fish1 may be mingled with marine shells1 without any bones of land quadrupeds or batrachian reptiles2 yet even here we should expect the remains of marine mammalia to be imbedded in the new strata1 for there are seals1 besides several kinds of cetacea1 on the ,galapagian shores2 and1 in this respect1 the parallel between the modern fauna1 above described1 and the ancient one of the lias1 would not hold good4 ,sudden destruction of saurians4--,it has been remarked1 and truly1 that many of the fish and saurians1 found fossil in the lias1 must have met with sudden death and immediate burial2 and that the destructive operation1 whatever may have been its nature1 was often repeated4 ,sometimes1 says ,dr4 ,buckland1 scarcely a single bone or scale has been removed from the place it occupied during life2 which could not have happened had the uncovered bodies of these saurians been left1 even for a few hours1 exposed to putrefaction1 and to the attacks of fishes1 and other smaller animals at the bottom of the sea4#bhj-;,b ,not only are the skeletons of the ,ichthyosaurs entire1 but sometimes the contents of their stomachs still remain between their ribs1 as before remarked1 so that we can discover the particular species of fish on which they lived1 and the form of their excrements4 ,not unfrequently there are layers of these coprolites1 at different depths in the lias1 at a distance from any entire skeletons of the marine lizards from which they were derived2 as if1 says ,sir ,h4 ,de la ,beche1 the muddy bottom of the sea received small sudden accessions of matter from time to time1 covering up the coprolites and other exuviae which had accumulated during the intervals4#bha-;,a ,it is farther stated that1 at ,lyme ,regis1 those surfaces only of the coprolites which lay uppermost at the bottom of the sea have suffered partial decay1 from the action of water before they were covered and protected by the muddy sediment that has afterwards permanently enveloped them4#bha-;,b ,numerous specimens of the pen-and-ink fish 7,sepia loligo1 ,lin42 ,loligo vulgaris1 ,lam47 have also been met with in the lias at ,lyme1 with the ink-bags still distended1 containing the ink in a dried state1 chiefly composed of carbon1 and but slightly impregnated with carbonate of lime4 ,these cephalopoda1 therefore1 must1 like the saurians1 have been soon buried in sediment2 for1 if long exposed after death1 the membrane containing the ink would have decayed4#bha-;,c ,as we know that river fish are sometimes stifled1 even in their own element1 by muddy water during floods1 it cannot be doubted that the periodical discharge of large bodies of turbid fresh water into the sea may be still more fatal to marine tribes4 ,in the ,principles of ,geology ,i have shown that large quantities of mud and drowned animals have been swept down into the sea by rivers during earthquakes1 as in ,java1 in #afii2 and that undescribable multitudes of dead fishes have been seen floating on the sea after a discharge of noxious vapours during similar convulsions4#bha-;,d ,but1 in the intervals between such catastrophes1 strata may have accumulated slowly in the sea of the lias1 some being formed chiefly of one description of shell1 such as ammonites1 others of gryphites4 ,from the above remarks the reader will infer that the lias is for the most part a marine deposit4 ,some members1 however1 of the series1 especially in the lowest part of it1 have an estuary character1 and must have been formed within the influence of rivers4 ,in ,gloucestershire1 where there is a good type of the lias of the ,west of ,england1 it may be divided into an upper mass of shale with a base of marlstone1 and a lower series of shales with underlying limestones and shales4 ,we learn from the researches of the ,rev4 ,p4 ,b4 ,brodie#bha-;,e1 that in the superior of these two divisions numerous remains of insects and plants have been detected in several places1 mingled with marine shells2 but in the inferior division similar fossils are still more plentiful4 ,one band1 rarely exceeding a foot in thickness1 has been named the insect limestone4 ,it passes upwards into a shale containing ,cypris and ,estheria1 and is charged with the wing-cases of several genera of coleoptera1 and with some nearly entire beetles1 of which the eyes are preserved4 ,the nervures of the wings of neuropterous insects 7fig4 #cad47 are beautifully perfect in this bed4 ,ferns1 with leaves of monocotyledonous plants1 and freshwater shells1 such as ,cyclas and ,unio1 accompany the insects in some places1 while in others marine shells predominate1 the fossils varying apparently as we examine the bed nearer or farther from the ancient land1 or the source whence the fresh water was derived4 ,there are two1 or even three1 bands of insect limestone in several sections1 and they have been ascertained by ,mr4 ,brodie to retain the same lithological and zoological characters when traced from the centre of ,warwickshire to the borders of the southern part of ,wales4 ,after studying #cjj specimens of these insects from the lias1 ,mr4 ,westwood declares that they comprise both wood-eating and herb-devouring beetles of the ,linnean genera ,elater1 ,carabus1 c41 besides grasshoppers 7,gryllus71 and detached wings of dragon-flies and may-flies1 or insects referable to the ,linnean genera ,libellula1 ,ephemera1 ,hemerobius1 and ,panorpa1 in all belonging to no less than twenty-four families4 ,the size of the species is usually small1 and such as taken alone would imply a temperate climate2 but many of the associated organic remains of other classes must lead to a different conclusion4 ,illustration3 ,fig4 #cad4 ,wing of a neuropterous insect1 from the ,lower ,lias1 ,gloucestershire4 7,rev4 ,b4 ,brodie47 ,fossil plants4--,among the vegetable remains of the ,lias1 several species of ,zamia have been found at ,lyme ,regis1 and the remains of coniferous plants at ,whitby4 ,fragments of wood are common1 and often converted into limestone4 ,that some of this wood1 though now petrified1 was soft when it first lay at the bottom of the sea1 is shown by a specimen now in the museum of the ,geological ,society 7see fig4 #cae471 which has the form of an ammonite indented on its surface4 ,illustration3 ,fig4 #cae4 ,petrified wood4 ,m4 ,ad4 ,brongniart enumerates forty-seven liassic acrogens1 most of them ferns2 and fifty gymnogens1 of which thirty-nine are cycads1 and eleven conifers4 ,among the cycads the predominance of ,zamites and ,nilsonia1 and among the ferns the numerous genera with leaves having reticulated veins 7as in fig4 #bif4 p4 #bgb471 are mentioned as botanical characteristics of this era4#bhb-;,a ,origin of the ,oolite and ,lias4--,if we now endeavour to restore1 in imagination1 the ancient condition of the ,european area at the period of the ,oolite and ,lias1 we must conceive a sea in which the growth of coral reefs and shelly limestones1 after proceeding without interruption for ages1 was liable to be stopped suddenly by the deposition of clayey sediment4 ,then1 again1 the argillaceous matter1 devoid of corals1 was deposited for ages1 and attained a thickness of hundreds of feet1 until another period arrived when the same space was again occupied by calcareous sand1 or solid rocks of shell and coral1 to be again succeeded by the recurrence of another period of argillaceous deposition4 ,mr4 ,conybeare has remarked of the entire group of ,oolite and ,lias1 that it consists of repeated alternations of clay1 sandstone1 and limestone1 following each other in the same order4 ,thus the clays of the lias are followed by the sands of the inferior oolite1 and these again by shelly and coralline limestone 7,bath oolite1 c472 so1 in the middle oolite1 the ,oxford clay is followed by calcareous grit and coral rag2 lastly1 in the upper oolite1 the ,kimmeridge clay is followed by the ,portland sand and limestone4#bhc-;,a ,the clay beds1 however1 as ,sir ,h4 ,de la ,beche remarks1 can be followed over larger areas than the sands or sandstones4#bhc-;,b ,it should also be remembered that while the oolitic system becomes arenaceous1 and resembles a coal-field in ,yorkshire1 it assumes1 in the ,alps1 an almost purely calcareous form1 the sands and clays being omitted2 and even in the intervening tracts1 it is more complicated and variable than appears in ordinary descriptions4 ,nevertheless1 some of the clays and intervening limestones do1 in reality1 retain a pretty uniform character1 for distances of from #djj to #fjj miles from east to west and north to south4 ,according to ,m4 ,thirria1 the entire oolitic group in the department of the ,haute-,saone1 in ,france1 may be equal in thickness to that of ,england2 but the importance of the argillaceous divisions is in the inverse ratio to that which they exhibit in ,england1 where they are about equal to twice the thickness of the limestones1 whereas1 in the part of ,france alluded to1 they reach only about a third of that thickness4#bhc-;,c ,in the ,jura the clays are still thinner2 and in the ,alps they thin out and almost vanish4 ,in order to account for such a succession of events1 we may imagine1 first1 the bed of the ocean to be the receptacle for ages of fine argillaceous sediment1 brought by oceanic currents1 which may have communicated with rivers1 or with part of the sea near a wasting coast4 ,this mud ceases1 at length1 to be conveyed to the same region1 either because the land which had previously suffered denudation is depressed and submerged1 or because the current is deflected in another direction by the altered shape of the bed of the ocean and neighbouring dry land4 ,by such changes the water becomes once more clear and fit for the growth of stony zoophytes4 ,calcareous sand is then formed from comminuted shell and coral1 or1 in some cases1 arenaceous matter replaces the clay2 because it commonly happens that the finer sediment1 being first drifted farthest from coasts1 is subsequently overspread by coarse sand1 after the sea has grown shallower1 or when the land1 increasing in extent1 whether by upheaval or by sediment filling up parts of the sea1 has approached nearer to the spots first occupied by fine mud4 ,in order to account for another great formation1 like the ,oxford clay1 again covering one of coral limestone1 we must suppose a sinking down like that which is now taking place in some existing regions of coral between ,australia and ,south ,america4 ,the occurrence of subsidences1 on so vast a scale1 may have caused the bed of the ocean and the adjoining land1 throughout great parts of the ,european area1 to assume a shape favourable to the deposition of another set of clayey strata2 and this change may have been succeeded by a series of events analogous to that already explained1 and these again by a third series in similar order4 ,both the ascending and descending movements may have been extremely slow1 like those now going on in the ,pacific2 and the growth of every stratum of coral1 a few feet of thickness1 may have required centuries for its completion1 during which certain species of organic beings disappeared from the earth1 and others were introduced in their place2 so that1 in each set of strata1 from the ,upper ,oolite to the ,lias1 some peculiar and characteristic fossils were embedded4 ,oolite and ,lias of the ,united ,states4 ,illustration3 ,fig4 #caf4 ,section showing the geological position of the ,james ,river1 or ,east ,virginian ,coal-field4 ,a4 ,granite1 gneiss1 c4 ,b4 ,coal-measures4 ,c4 ,tertiary strata4 ,d4 ,drift or ancient alluvium4 ,there are large tracts on the globe1 as in ,russia and the ,united ,states1 where all the members of the oolitic series are unrepresented4 ,in the state of ,virginia1 however1 at the distance of about #ac miles eastward of ,richmond1 the capital of that ,state1 there is a regular coal-field occurring in a depression of the granite rocks 7see section1 fig4 #caf471 which ,professor ,w4 ,b4 ,rogers first correctly referred to the age of the lower part of the ,jurassic group4 ,this opinion ,i was enabled to confirm after collecting a large number of fossil plants1 fish1 and shells1 and examining the coal-field throughout its whole area4 ,it extends #bf miles from north to south1 and from #d to #ab1 from east to west4 ,the plants consist chiefly of zamites1 calamites1 and equisetums1 and these last are very commonly met with in a vertical position more or less compressed perpendicularly4 ,it is clear that they grew in the places where they now lie buried in strata of hardened sand and mud4 ,i found them maintaining their erect attitude1 at points many miles distant from others1 in beds both above and between the seams of coal4 ,in order to explain this fact we must suppose such shales and sandstones to have been gradually accumulated during the slow and repeated subsidence of the whole region4 ,it is worthy of remark that the ,equisetum columnare of these ,virginian rocks appears to be undistinguishable from the species found in the oolitic sandstones near ,whitby in ,yorkshire1 where it also is met with in an upright position4 ,one of the ,american ferns1 ,pecopteris ,whitbyensis1 is also a species common to the ,yorkshire oolites4#bhe-;,a ,these ,virginian coal-measures are composed of grits1 sandstones1 and shales1 exactly resembling those of older or primary date in ,america and ,europe1 and they rival or even surpass the latter in the richness and thickness of the seams4 ,one of these1 the main seam1 is in some places from #cj to #dj feet thick1 composed of pure bituminous coal4 ,on descending a shaft #hjj feet deep1 in the ,blackheath mines in ,chesterfield county1 ,i found myself in a chamber more than #dj feet high1 caused by the removal of this coal4 ,timber props of great strength supported the roof1 but they were seen to bend under the incumbent weight4 ,the coal is like the finest kinds shipped at ,newcastle1 and when analysed yields the same proportions of carbon and hydrogen1 a fact worthy of notice when we consider that this fuel has been derived from an assemblage of plants very distinct specifically1 and in part generically1 from those which have contributed to the formation of the ancient or paleozoic coal4 ,the fossil fish of these ,richmond strata belong to the liassic genus ,tetragonolepis1 and to a new genus which ,i have called ,dictyopyge4 ,shells are very rare1 as usually in all coal-bearing deposits1 but a species of ,posidonomya is in such profusion in some shaley beds as to divide them like the plates of mica in micaceous shales 7see fig4 #cag474 ,illustration3 ,fig4 #cag4 ,oolitic coal-shale1 ,richmond1 ,virginia4 a4 ,posidonomya4 b4 young of same4 ,in ,india1 especially in ,cutch1 a formation occurs clearly referable to the oolitic and liassic type1 as shown by the shells1 corals1 and plants2 and there also coal has been procured from one member of the group4 ,,footnotes3 #bgd-;,a ,conyb4 and ,phil4 p4 #bfa4 #bge-;,a ,agassiz1 ,pois4 ,fos4 vol4 ii4 tab4 #bh1 #bi4 #bgf-;,a ,bridgewater ,treatise1 p4 #bij4 #bgf-;,b ,agassiz1 ,poissons ,fossiles1 vol4 iii4 tab4 ,c4 fig4 #a4 #bgf-;,c ,ibid4 p4 #afh4 #bgf-;,d ,ibid4 p4 #ahg4 #bgg-;,a ,geol4 ,soc4 ,proceedings1 vol4 iii4 p4 #aeg4 #ahci4 #bgg-;,b ,geol4 ,trans4 ,second ,series1 vol4 v4 p4 #eaa4 #bgh-;,a ,geol4 ,trans41 ,second ,series1 vol4 i4 pl4 #di4 #bgh-;,b ,conybeare and ,de la ,beche4 ,geol4 ,trans42 and ,buckland1 ,bridgew4 ,treat41 p4 #bjc4 #bgh-;,c ,quart4 ,geol4 ,journ4 vol4 ii4 p4 #daa4 #bgi-;,a ,amblys1 amblys1 blunt2 and rhygchos1 rhynchus1 snout4 #bhj-;,a ,darwin's ,journal1 chap4 xix4 #bhj-;,b ,bridgew4 ,treat41 p4 #abe4 #bha-;,a ,geological ,researches1 p4 #ccd4 #bha-;,b ,buckland1 ,bridgew4 ,treat41 p4 #cjg4 #bha-;,c ,ibid4 #bha-;,d ,see ,principles1 ,index1 ,lancerote1 ,graham ,island1 ,calabria4 #bha-;,e ,a ,history of ,fossil ,insects1 c4 #ahde4 ,london4 #bhb-;,a ,tableau des ,veg4 ,fos4 #ahdi1 p4 #aje4 #bhc-;,a ,con4 and ,phil41 p4 #aff4 #bhc-;,b ,geol4 ,researches1 p4 #ccg4 #bhc-;,c ,burat's ,d',aubuisson1 tom4 ii4 p4 #def4 #bhe-;,a ,see description of the coal-field by the author1 and the plants by ,c4 ,j4 ,f4 ,bunbury1 ,esq41 ,quart4 ,geol4 ,journ41 vol4 iii4 p4 #bha4 ,,chapter ,,xxii4 ,,trias ,,or ,,new ,,red ,,sandstone ,,group4 ,distinction between ,new and ,old ,red ,sandstone--,between ,upper and ,lower ,new ,red--,the ,trias and its three divisions--,most largely developed in ,germany--,keuper and its fossils--,muschelkalk--,fossil plants of ,bunter--,triassic group in ,england--,bone-bed of ,axmouth and ,aust--,red ,sandstone of ,warwickshire and ,cheshire--,footsteps of ,chirotherium in ,england and ,germany--,osteology of the ,labyrinthodon--,identification of this ,batrachian with the ,chirotherium--,origin of ,red ,sandstone and ,rock-salt--,hypothesis of saline volcanic exhalations--,theory of the precipitation of salt from inland lakes or lagoons--,saltness of the ,red ,sea--,new ,red ,sandstone in the ,united ,states--,fossil footprints of birds and reptiles in the ,valley of the ,connecticut--,antiquity of the ,red ,sandstone containing them4 ,between the ,lias and the ,coal1 or ,carboniferous group1 there is interposed1 in the midland and western counties of ,england1 a great series of red loams1 shales1 and sandstones1 to which the name of the ,new ,red ,sandstone formation was first given1 to distinguish it from other shales and sandstones called the ,old ,red 7c1 fig4 #cah471 often identical in mineral character1 which lie immediately beneath the coal 7b74 ,illustration3 ,fig4 #cah4 ,cross section4 a4 ,new red sandstone4 b4 ,coal4 c4 ,old red4 ,the name of ,red ,marl has been incorrectly applied to the red clays of this formation1 as before explained 7p4 #ac471 for they are remarkably free from calcareous matter4 ,the absence1 indeed1 of carbonate of lime1 as well as the scarcity of organic remains1 together with the bright red colour of most of the rocks of this group1 causes a strong contrast between it and the ,jurassic formations before described4 ,before the distinctness of the fossil remains characterizing the upper and lower part of the ,english ,new ,red had been clearly recognized1 it was found convenient to have a common name for all the strata intermediate in position between the ,lias and ,coal2 and the term ,poikilitic was proposed by ,messrs4 ,conybeare and ,buckland#bhf-;,a1 from poikilos1 poikilos1 variegated1 some of the most characteristic strata of this group having been called variegated by ,werner1 from their exhibiting spots and streaks of light-blue1 green1 and buff colour1 in a red base4 ,a single term1 thus comprehending both ,upper and ,lower ,new ,red1 or the ,triassic and ,permian groups of modern classifications1 may still be useful in describing districts where we have to speak of masses of red sandstone and shale1 referable1 in part1 to both these eras1 but which1 in the absence of fossils1 it is impossible to divide4 ,trias or ,upper ,new ,red ,sandstone ,group4 ,the accompanying table will explain the subdivisions generally adopted for the uppermost of the two systems above alluded to1 and the names given to them in ,england and on the ,continent4 ,synonyms4 ,german4 ,french4 a4 ,saliferous and gypseous shales and ,keuper ,marnes irisees4 ,trias or ,upper sandstone ,new ,red ,sandstone b4 7wanting in ,england7 ,muschelkalk ,muschelkalk1 ou calcaire coquillier4 c4 ,sandstone and ,bunter- ,gres bigarre4 quartzose conglomerate sandstein ,i shall first describe this group as it occurs in ,south ,western and ,north ,western ,germany1 for it is far more fully developed there than in ,england or ,france4 ,it has been called the ,trias by ,german writers1 or the ,triple ,group1 because it is separable into three distinct formations1 called the ,keuper1 the ,muschelkalk1 and the ,bunter-sandstein4 ,illustration3 ,fig4 #cai4 ,equisetites columnaris4 7,syn4 ,equisetum columnare47 ,fragment of stem1 and small portion of same magnified4 ,keuper4 ,the ,keuper1 the first or newest of these1 is #ajjj feet thick in ,wuertemberg1 and is divided by ,alberti into sandstone1 gypsum1 and carbonaceous slate-clay4#bhg-;,a ,remains of ,reptiles1 called ,nothosaurus and ,phytosaurus1 have been found in it with ,labyrinthodon2 the detached teeth1 also1 of placoid fish and of rays1 and of the genera ,saurichthys and ,gyrolepis 7figs4 #cbe1 #cbf1 p4 #bhi474 ,the plants of the ,keuper are generically very analogous to those of the lias and oolite1 consisting of ferns1 equisetaceous plants1 cycads1 and conifers1 with a few doubtful monocotyledons4 ,a few species1 such as ,equisetites columnaris1 are common to this group1 and the oolite4 ,the ,muschelkalk consists chiefly of a compact1 greyish limestone1 but includes beds of dolomite in many places1 together with gypsum and rock-salt4 ,this limestone1 a rock wholly unrepresented in ,england1 abounds in fossil shells1 as the name implies4 ,among the cephalopoda there are no belemnites1 and no ammonites with foliated sutures1 as in the incumbent lias and oolite1 but a genus allied to the ,ammonite1 called ,ceratite by ,de ,haan1 in which the descending lobes 7see a1 b1 c1 fig4 #cbj47 terminate in a few small denticulations pointing inwards4 ,among the bivalve shells1 the ,posidonia minuta1 ,goldf4 7,posidonomya minuta1 ,bronn7 7see fig4 #cba471 is abundant1 ranging through the ,keuper1 ,muschelkalk1 and ,bunter-sandstein2 and ,avicula socialis1 fig4 #cbb41 having a similar range1 is very characteristic of the ,muschelkalk in ,germany1 ,france1 and ,poland4 ,illustration3 ,fig4 #cbj4 ,ceratites nodosus4 ,muschelkalk4 a4 ,side view4 b4 ,front view4 c4 ,partially denticulated outline of the septa dividing the chambers4 ,illustration3 ,fig4 #cba4 ,posidonia minuta1 ,goldf4 7,posidonomya minuta1 ,bronn47 ,illustration3 ,fig4 #cbb4 ,avicula4 ,characteristic of the ,muschelkalk4 a4 ,avicula socialis4 b4 ,side view of same4 ,the abundance of the heads and stems of lily encrinites1 ,encrinus liliiformis 7or ,encrinites moniliformis71 show the slow manner in which some beds of this limestone have been formed in clear sea-water4 ,illustration3 ,fig4 #cbc4 ,voltzia4 ,bunter-sandstein4 a4 ,voltzia heterophylla4 7,syn4 ,voltzia brevifolia47 b4 portion of same magnified to show fructification4 ,sulzbad4 ,the ,bunter-sandstein consists of various coloured sandstones1 dolomites1 and red-clays1 with some beds1 especially in the ,hartz1 of calcareous pisolite or roe-stone1 the whole sometimes attaining a thickness of more than #ajjj feet4 ,the sandstone of the ,vosges1 according to ,von ,meyer1 is proved1 by the presence of ,labyrinthodon1 to belong to this lowest member of the ,triassic group4 ,at ,sulzbad 7or ,soultz-les-bains71 near ,strasburg1 on the flanks of the ,vosges1 many plants have been obtained from the bunter1 especially conifers of the extinct genus ,voltzia1 peculiar to this period1 in which even the fructification has been preserved4 7,see fig4 #cbc47 ,out of thirty species of ferns1 cycads1 conifers1 and other plants1 enumerated by ,m4 ,ad4 ,brongniart1 in #ahdi1 as coming from the gres bigarre1 or ,bunter1 not one is common to the ,keuper4#bhh-;,a ,the footprints of a reptile 7,labyrinthodon7 have been observed on the clays of this member of the ,trias1 near ,hildburghausen1 in ,saxony1 impressed on the upper surface of the beds1 and standing out as casts in relief from the under sides of incumbent slabs of sandstone4 ,to these ,i shall again allude in the sequel2 they attest1 as well as the accompanying ripple-marks1 and the cracks which traverse the clays1 the gradual formation in shallow water1 and sometimes between high and low water1 of the beds of this formation4 ,triassic group in ,england4 ,in ,england the ,lias is succeeded by conformable strata of red and green marl1 or clay4 ,there intervenes1 however1 both in the neighbourhood of ,axmouth1 in ,devonshire1 and in the cliffs of ,westbury and ,aust1 in ,gloucestershire1 on the banks of the ,severn1 a dark-coloured stratum1 well known by the name of the bone-bed4 ,it abounds in the remains of saurians and fish1 and was formerly classed as the lowest bed of the ,lias2 but ,sir ,p4 ,egerton has shown that it should be referred to the ,upper ,new ,red ,sandstone1 for it contains an assemblage of fossil fish which are either peculiar to this stratum1 or belong to species well known in the ,muschelkalk of ,germany4 ,these fish belong to the genera ,acrodus1 ,hybodus1 ,gyrolepis1 and ,saurichthys4 ,among those common to the ,english bone-bed and the ,muschelkalk of ,germany are ,hybodus plicatilis 7fig4 #cbd471 ,saurichthys apicalis 7fig4 #cbe471 ,gyrolepis tenuistriatus 7fig4 #cbf471 and ,g4 ,albertii4 ,remains of saurians have also been found in the bone-bed1 and plates of an ,encrinus4 ,illustration3 ,fig4 #cbd4 ,hybodus plicatilis4 ,teeth4 ,bone-bed1 ,aust and ,axmouth4 ,illustration3 ,fig4 #cbe4 ,saurichthys apicalis4 ,tooth2 nat4 size1 and magnified4 ,axmouth4 ,illustration3 ,fig4 #cbf4 ,gyrolepis tenuistriatus4 ,scale2 nat4 size1 and magnified4 ,axmouth4 ,the strata of red and green marl1 which follow the bone-bed in the descending order at ,axmouth and ,aust1 are destitute of organic remains2 as is the case1 for the most part1 in the corresponding beds in almost every part of ,england4 ,but fossils have lately been found at a few localities in sandstones of this formation1 in ,worcestershire and ,warwickshire1 and among them the bivalve shell called ,posidonia minuta1 ,goldf41 before mentioned 7fig4 #cba4 p4 #bhh474 ,the upper member of the ,english ,new ,red containing this shell1 in those parts of ,england1 is1 according to ,messrs4 ,murchison and ,strickland1 #fjj feet thick1 and consists chiefly of red marl or slate1 with a band of sandstone4 ,spines of ,hybodus1 called ichthyodorulites1 teeth of fishes1 and footprints of reptiles1 with remains of a saurian called ,rhyncosaurus1 were observed by the same geologists in these strata4#bij-;,a ,in ,cheshire and ,lancashire the gypseous and saliferous red shales and loams of the ,trias are between #ajjj and #aejj feet thick4 ,in some places lenticular masses of rock-salt are interpolated between the argillaceous beds1 the origin of which will be spoken of in the sequel4 ,illustration3 ,fig4 #cbg4 ,single footstep of ,chirotherium4 ,bunter ,sandstein1 ,saxony2 one eighth of nat4 size4 ,illustration3 ,fig4 #cbh4 ,line of footsteps on slab of sandstone4 ,hildburghausen1 in ,saxony4 ,the lower division or ,english representative of the ,bunter attains a thickness of #fjj feet in the counties last mentioned4 ,besides red and green shales and red sandstones1 it comprises much soft white quartzose sandstone1 in which the trunks of silicified trees have been met with at ,allesley ,hill1 near ,coventry4 ,several of them were a foot and a half in diameter1 and some yards in length1 decidedly of coniferous wood1 and showing rings of annual growth4#bij-;,b ,impressions1 also1 of the footsteps of animals have been detected in ,lancashire and ,cheshire in this formation4 ,some of the most remarkable occur a few miles from ,liverpool1 in the whitish quartzose sandstone of ,storton ,hill1 on the west side of the ,mersey4 ,they bear a close resemblance to tracks first observed in a member of the ,upper ,new ,red ,sandstone1 at the village of ,hesseberg1 near ,hildburghausen1 in ,saxony1 to which ,i have already alluded4 ,for many years these footprints have been referred to a large unknown quadruped1 provisionally named ,chirotherium by ,professor ,kaup1 because the marks both of the fore and hind feet resembled impressions made by a human hand4 7,see fig4 #cbg47 ,the footmarks at ,hesseberg are partly concave and partly in relief2 the former1 or the depressions1 are seen upon the upper surface of the sandstone slabs1 but those in relief are only upon the lower surfaces1 being in fact natural casts1 formed in the subjacent footprints as in moulds4 ,the larger impressions1 which seem to be those of the hind foot1 are generally #h inches in length1 and #e in width1 and one was #ab inches long4 ,near each large footstep1 and at a regular distance 7about an inch and a half71 before it1 a smaller print of a fore foot1 #d inches long and #c inches wide1 occurs4 ,the footsteps follow each other in pairs1 each pair in the same line1 at intervals of #ad inches from pair to pair4 ,the large as well as the small steps show the great toes alternately on the right and left side2 each step makes the print of five toes1 the first or great toe being bent inwards like a thumb4 ,though the fore and hind foot differ so much in size1 they are nearly similar in form4 ,the similar footmarks afterwards observed in a rock of corresponding age at ,storton ,hill1 were imprinted on five thin beds of clay1 superimposed one upon the other in the same quarry1 and separated by beds of sandstone4 ,on the lower surface of the sandstone strata1 the solid casts of each impression are salient1 in high relief1 and afford models of the feet1 toes1 and claws of the animals which trod on the clay4 ,as neither in ,germany nor in ,england any bones or teeth had been met with in the same identical strata as the footsteps1 anatomists indulged1 for several years1 in various conjectures respecting the mysterious animals from which they might have been derived4 ,professor ,kaup suggested that the unknown quadruped might have been allied to the ,marsupialia2 for in the kangaroo the first toe of the fore foot is in a similar manner set obliquely to the others1 like a thumb1 and the disproportion between the fore and hind feet is also very great4 ,but ,m4 ,link conceived that some of the four species of animals of which the tracks had been found in ,saxony might have been gigantic ,batrachians2 and ,dr4 ,buckland designated some of the footsteps as those of a small web-footed animal1 probably crocodilean4 ,in the course of these discussions several naturalists of ,liverpool1 in their report on the ,storton quarries1 declared their opinion that each of the thin seams of clay in which the sandstone casts were moulded had formed successively a surface above water1 over which the ,chirotherium and other animals walked1 leaving impressions of their footsteps1 and that each layer had been afterwards submerged by a sinking down of the surface1 so that a new beach was formed at low water above the former1 on which other tracks were then made4 ,the repeated occurrence of ripple-marks at various heights and depths in the red sandstone of ,cheshire had been explained in the same manner4 ,it was also remarked that impressions of such depth and clearness could only have been made by animals walking on the land1 as their weight would have been insufficient to make them sink so deeply in yielding clay under water4 ,they must therefore have been air-breathers4 ,when the inquiry had been brought to this point1 the reptilian remains discovered in the ,trias1 both of ,germany and ,england1 were carefully examined by ,mr4 ,owen4 ,he found1 after a microscopic investigation of the teeth from the ,german sandstone called ,keuper1 and from the sandstone of ,warwick and ,leamington1 that neither of them could be referred to true saurians1 although they had been named ,mastodonsaurus and ,phytosaurus by ,jaeger 7fig4 #cbi474 ,it appeared that they were of the ,batrachian order1 and attested the former existence of frogs of gigantic dimensions in comparison with any now living4 ,both the ,continental and ,english fossil teeth exhibited a most complicated texture1 differing from that previously observed in any reptile1 whether recent or extinct1 but most nearly analogous to the ,ichthyosaurus4 ,a section of one of these teeth exhibits a series of irregular folds1 resembling the labyrinthic windings of the surface of the brain2 and from this character ,mr4 ,owen has proposed the name ,labyrinthodon for the new genus4 ,by his permission1 the annexed representation 7fig4 #ccj47 of part of one is given from his ,odontography1 plate #fd4 ,a4 ,the entire length of this tooth is supposed to have been about three inches and a half1 and the breadth at the base one inch and a half4 ,illustration3 ,fig4 #cbi4 ,tooth of ,labyrinthodon2 nat4 size4 ,warwick sandstone4 ,illustration3 ,fig4 #ccj4 ,transverse section of tooth of ,labyrinthodon ,jaegeri1 ,owen 7,mastodonsaurus ,jaegeri1 ,meyer72 nat4 size1 and a segment magnified4 a4 ,pulp cavity1 from which the processes of pulp and dentine radiate4 ,when ,mr4 ,owen had satisfied himself1 from an inspection of the cranium1 jaws1 and teeth1 that a gigantic ,batrachian had existed at the period of the ,trias or ,upper ,new ,red ,sandstone1 he soon found1 from the examination of various bones derived from the same formation1 that he could define three species of ,labyrinthodon1 and that in this genus the hind extremities were much larger than the anterior ones4 ,this circumstance1 coupled with the fact of the ,labyrinthodon having existed at the period when the ,chirotherian footsteps were made1 was the first step towards the identification of those tracks with the newly discovered ,batrachian4 ,it was at the same time observed that the footmarks of ,chirotherium were more like those of toads than of any other living animal2 and1 lastly1 that the size of the three species of ,labyrinthodon corresponded with the size of three different kinds of footprints which had already been supposed to belong to three distinct ,chirotheria4 ,it was moreover inferred1 with confidence1 that the ,labyrinthodon was an air-breathing reptile from the structure of the nasal cavity1 in which the posterior outlets were at the back part of the mouth1 instead of being directly under the anterior or external nostrils4 ,it must have respired air after the manner of saurians1 and may therefore have imprinted on the shore those footsteps1 which1 as we have seen1 could not have originated from an animal walking under water4 ,it is true that the structure of the foot is still wanting1 and that a more connected and complete skeleton is required for demonstration2 but the circumstantial evidence above stated is strong enough to produce the conviction that the ,chirotherium and ,labyrinthodon are one and the same4 ,in order to show the manner in which one of these formidable ,batrachians may have impressed the mark of its feet upon the shore1 ,mr4 ,owen has attempted a restoration1 of which a reduced copy is annexed4 ,illustration3 ,fig4 #cca4 ,labyrinthodon pachygnathus1 ,owen4 ,the only bones of this species at present known are those of the head1 the pelvis1 and part of the scapula1 which are shown by stronger lines in the above figure4 ,there is reason for believing that the head was not smooth externally1 but protected by bony scutella4 ,origin of ,red ,sandstone and ,rock ,salt4 ,we have seen that1 in various parts of the world1 red and mottled clays1 and sandstones1 of several distinct geological epochs1 are found associated with salt1 gypsum1 magnesian limestone1 or with one or all of these substances4 ,there is1 therefore1 in all likelihood1 a general cause for such a coincidence4 ,nevertheless1 we must not forget that there are dense masses of red and variegated sandstones and clays1 thousands of feet in thickness1 and of vast horizontal extent1 wholly devoid of saliferous or gypseous matter4 ,there are also deposits of gypsum and of muriate of soda1 as in the blue clay formation of ,sicily1 without any accompanying red sandstone or red clay4 ,to account for deposits of red mud and red sand1 we have simply to suppose the disintegration of ordinary crystalline or metamorphic schists4 ,thus1 in the eastern ,grampians of ,scotland1 as1 for example1 in the north of ,forfarshire1 the mountains of gneiss1 mica-schist1 and clay-slate1 are overspread with alluvium1 derived from the disintegration of those rocks2 and the mass of detritus is stained by oxide of iron1 of precisely the same colour as the ,old ,red ,sandstone of the adjoining ,lowlands4 ,now this alluvium merely requires to be swept down to the sea1 or into a lake1 to form strata of red sandstone and red marl1 precisely like the mass of the ,old ,red or ,new ,red systems of ,england1 or those tertiary deposits of ,auvergne 7see p4 #ahb471 before described1 which are in lithological characters quite undistinguishable4 ,the pebbles of gneiss in the ,eocene red sandstone of ,auvergne point clearly to the rocks from which it has been derived4 ,the red colouring matter may1 as in the ,grampians1 have been furnished by the decomposition of hornblende1 or mica1 which contain oxide of iron in large quantity4 ,it is a general fact1 and one not yet accounted for1 that scarcely any fossil remains are preserved in stratified rocks in which this oxide of iron abounds2 and when we find fossils in the ,new or ,old ,red ,sandstone in ,england1 it is in the grey1 and usually calcareous beds1 that they occur4 ,the gypsum and saline matter1 occasionally interstratified with such red clays and sandstones of various ages1 primary1 secondary1 and tertiary1 have been thought by some geologists to be of volcanic origin4 ,submarine and subaerial exhalations often occur in regions of earthquakes and volcanos far from points of actual eruption1 and charged with sulphur1 sulphuric salts1 and with common salt or muriate of soda4 ,in a word1 they are vents by which all the products which issue in a state of sublimation from the craters of active volcanos1 obtain a passage from the interior of the earth to the surface4 ,that such gaseous emanations and mineral springs1 impregnated with the ingredients before enumerated1 and often intensely heated1 continue to flow out unaltered in composition and temperature for ages1 is well known4 ,but before we can decide on their real instrumentality in producing in the course of ages beds of gypsum1 salt1 and dolomite1 we require to know what are the chemical changes actually in progress in seas where this volcanic agency is at work4 ,yet the origin of rock-salt is a problem of so much interest in theoretical geology as to demand a full discussion of another hypothesis advanced on the subject2 namely1 that which attributes the precipitation of the salt to evaporation1 whether of inland lakes or of lagoons communicating with the ocean4 ,at ,northwich1 in ,cheshire1 two beds of salt1 in great part unmixed with earthy matter1 attain the extraordinary thickness of #ij and even #ajj feet4 ,the upper surface of the highest bed is very uneven1 forming cones and irregular figures4 ,between the two masses there intervenes a bed of indurated clay1 traversed with veins of salt4 ,the highest bed thins off towards the south-west1 losing #ae feet in thickness in the course of a mile4#bie-;,a ,the horizontal extent of these particular masses in ,cheshire and ,lancashire is not exactly known2 but the area1 containing saliferous clays and sandstones1 is supposed to exceed #aej miles in diameter1 while the total thickness of the trias in the same region is estimated by ,mr4 ,ormerod at more than #agjj feet4 ,ripple-marked sandstones1 and the footprints of animals1 before described1 are observed at so many levels that we may safely assume the whole area to have undergone a slow and gradual depression during the formation of the ,red ,sandstone4 ,the evidence of such a movement1 wholly independent of the presence of salt itself1 is very important in reference to the theory under consideration4 ,in the ,principles of ,geology 7chap4 #bh471 ,i published a map1 furnished to me by the late ,sir ,alexander ,burnes1 of that singular flat region called the ,runn of ,cutch1 near the delta of the ,indus1 which is #gjjj square miles in area1 or equal in extent to about one-fourth of ,ireland4 ,it is neither land nor sea1 but is dry during a part of every year1 and again covered by salt water during the monsoons4 ,some parts of it are liable1 after long intervals1 to be overflowed by river-water4 ,its surface supports no grass1 but is encrusted over1 here and there1 by a layer of salt1 about an inch in depth1 caused by the evaporation of sea-water4 ,certain tracts have been converted into dry land by upheaval during earthquakes since the commencement of the present century1 and1 in other directions1 the boundaries of the ,runn have been enlarged by subsidence4 ,that successive layers of salt might be thrown down1 one upon the other1 over thousands of square miles1 in such a region1 is undeniable4 ,the supply of brine from the ocean would be as inexhaustible as the supply of heat from the sun to cause evaporation4 ,the only assumption required to enable us to explain a great thickness of salt in such as area is1 the continuance1 for an indefinite period1 of a subsiding movement1 the country preserving all the time a general approach to horizontality4 ,pure salt could only be formed in the central parts of basins1 where no sand could be drifted by the wind1 or sediment be brought by currents4 ,should the sinking of the ground be accelerated1 so as to let in the sea freely1 and deepen the water1 a temporary suspension of the precipitation of salt would be the only result4 ,on the other hand1 if the area should dry up1 ripple-marked sands and the footprints of animals might be formed1 where salt had previously accumulated4 ,according to this view the thickness of the salt1 as well as of the accompanying beds of mud and sand1 becomes a mere question of time1 or requires simply a repetition of similar operations4 ,mr4 ,hugh ,miller1 in an able discussion of this question1 refers to ,dr4 ,frederick ,parrot's account1 in his journey to ,ararat 7#ahcf71 of the salt lakes of ,asia4 ,in several of these lakes west of the river ,manech1 the water1 during the hottest season of the year1 is covered on its surface with a crust of salt nearly an inch thick1 which is collected with shovels into boats4 ,the crystallization of the salt is effected by rapid evaporation from the sun's heat and the supersaturation of the water with muriate of soda2 the lake being so shallow that the little boats trail on the bottom and leave a furrow behind them1 so that the lake must be regarded as a wide pan of enormous superficial extent1 in which the brine can easily reach the degree of concentration required4 ,another traveller1 ,major ,harris1 in his ,highlands of ,ethiopia1 describes a salt lake1 called the ,bahr ,assal1 near the ,abyssinian frontier1 which once formed the prolongation of the ,gulf of ,tadjara1 but was afterwards cut off from the gulf by a broad bar of lava or of land upraised by an earthquake4 ,fed by no rivers1 and exposed in a burning climate to the unmitigated rays of the sun1 it has shrunk into an elliptical basin1 seven miles in its transverse axis1 half filled with smooth water of the deepest caerulian hue1 and half with a solid sheet of glittering snow-white salt1 the offspring of evaporation4 ,if1 says ,mr4 ,hugh ,miller1 we suppose1 instead of a barrier of lava1 that sand-bars were raised by the surf on a flat arenaceous coast during a slow and equable sinking of the surface1 the waters of the outer gulf might occasionally topple over the bar1 and supply fresh brine when the first stock had been exhausted by evaporation4#bif-;,a ,we may add that the permanent impregnation of the waters of a large shallow basin with salt1 beyond the proportion which is usual in the ocean1 would cause it to be uninhabitable by mollusca or fish1 as is the case in the ,dead ,sea1 and the muriate of soda might remain in excess1 even though it were occasionally replenished by irruptions of the sea4 ,should the saline deposit be eventually submerged1 it might1 as we have seen from the example of the ,runn of ,cutch1 be covered by a freshwater formation containing fluviatile organic remains2 and in this way the apparent anomaly of beds of sea-salt and clays devoid of marine fossils1 alternating with others of freshwater origin1 may be explained4 ,dr4 ,g4 ,buist1 in a recent communication to the ,bombay ,geographical ,society 7vol4 ix471 has asked how it happens that the ,red ,sea should not exceed the open ocean in saltness1 by more than #a_/ajth per cent4 ,the ,red ,sea receives no supply of water from any quarter save through the ,straits of ,babelmandeb2 and there is not a single river or rivulet flowing into it from a circuit of #djjj miles of shore4 ,the countries around are all excessively sterile and arid1 and composed1 for the most part1 of burning deserts4 ,from the ascertained evaporation in the sea itself1 ,dr4 ,buist computes that nearly #h feet of pure water must be carried off from the whole of its surface annually1 this being probably equivalent to #a_/ajjth part of its whole volume4 ,the ,red ,sea1 therefore1 ought to have #a per cent4 added annually to its saline contents2 and as these constitute #d per cent4 by weight1 or #b-a_/b per cent4 in volume of its entire mass1 it ought1 assuming the average depth to be #hjj feet1 which is supposed to be far beyond the truth1 to have been converted into one solid salt formation in less than #cjjj years4#big-;,a ,does the ,red ,sea receive a supply of water from the ocean1 through the narrow ,straits of ,babelmandeb1 sufficient to balance the loss by evaporation8 ,and is there an undercurrent of heavier saline water annually flowing outwards8 ,if not1 in what manner is the excess of salt disposed of8 ,an investigation of this subject by our nautical surveyors may perhaps aid the geologist in framing a true theory of the origin of rock-salt4 ,on the ,new ,red ,sandstone of the valley of the ,connecticut ,river in the ,united ,states4 ,in a depression of the granitic or hypogene rocks in the ,states of ,massachusetts and ,connecticut1 strata of red sandstone1 shale1 and conglomerate are found occupying an area more than #aej miles in length from north to south1 and about #e to #aj miles in breadth1 the beds dipping to the eastward at angles varying from #e to #ej degrees4 ,the extreme inclination of #ej degrees is rare1 and only observed in the neighbourhood of masses of trap which have been intruded into the red sandstone while it was forming1 or before the newer parts of the deposit had been completed4 ,having examined this series of rocks in many places1 ,i feel satisfied that they were formed in shallow water1 and for the most part near the shore1 and that some of the beds were from time to time raised above the level of the water1 and laid dry1 while a newer series1 composed of similar sediment1 was forming4 ,the red flags of thin-bedded sandstone are often ripple-marked1 and exhibit on their under sides casts of cracks formed in the underlying red and green shales4 ,these last must have shrunk by drying before the sand was spread over them4 ,on some shales of the finest texture impressions of rain drops may be seen1 and casts of them in the incumbent argillaceous sandstones4 ,having observed similar markings produced by showers1 of which the precise date was known1 on the recent red mud of the ,bay of ,fundy1 and casts in relief of the same1 on layers of dried mud thrown down by subsequent tides1 ,i feel no doubt in regard to the origin of some of the ancient ,connecticut impressions4 ,i have also seen on the mud-flats of the ,bay of ,fundy the footmarks of birds 7,tringa minuta71 which daily run along the borders of that estuary at low water1 and which ,i have described in my ,travels4#big-;,b ,similar layers of red mud1 now hardened and compressed into shale1 are laid open on the banks of the ,connecticut1 and retain faithfully the impressions and casts of the feet of numerous birds and reptiles which walked over them at the time when they were deposited1 probably in the ,triassic ,period4 ,according to ,professor ,hitchcock1 the footprints of no less than thirty-two species of bipeds1 and twelve of quadrupeds1 have been already detected in these rocks4 ,thirty of these are believed to be those of birds1 four of lizards1 two of chelonians1 and six of batrachians4 ,the tracks have been found in more than twenty places1 scattered through an extent of nearly #hj miles from north to south1 and they are repeated through a succession of beds attaining at some points a thickness of more than #ajjj feet1 which may have been thousands of years in forming4#bih-;,a ,illustration3 ,fig4 #ccb4 ,footprints of a bird4 ,turner's ,falls1 ,valley of the ,connecticut4 7,see ,dr4 ,deane1 ,mem4 of ,amer4 ,acad4 vol4 iv4 #ahdi47 ,as considerable scepticism is naturally entertained in regard to the nature of the evidence derived from footprints1 it may be well to enumerate some facts respecting them on which the faith of the geologist may rest4 ,when ,i visited the ,united ,states in #ahdb1 more than #bjjj impressions had been observed by ,professor ,hitchcock1 in the district alluded to1 and all of them were indented on the upper surface of the layers1 while the corresponding casts1 standing out in relief1 were always on the lower surfaces or planes of the strata4 ,if we follow a single line of marks we find them uniform in size1 and nearly uniform in distance from each other1 the toes of two successive footprints1 turning alternately right and left 7see fig4 #ccb474 ,such single lines indicate a biped2 and there is generally such a deviation from a straight line1 in any three successive prints1 as we remark in the tracks left by birds4 ,there is also a striking relation between the distance separating two footprints in one series and the size of the impressions2 in other words1 an obvious proportion between the length of the stride and the dimension of the creature which walked over the mud4 ,if the marks are small1 they may be half an inch asunder2 if gigantic1 as1 for example1 where the toes are #bj inches long1 they are occasionally #d feet and a half apart4 ,the bipedal impressions are for the most part trifid1 and show the same number of joints as exist in the feet of living tridactylous birds4 ,now such birds have three phalangeal bones for the inner toe1 four for the middle and five for the outer one 7see fig4 #ccb472 but the impression of the terminal joint is that of the nail only4 ,the fossil footprints exhibit regularly1 where the joints are seen1 the same number2 and we see in each continuous line of tracks the three-jointed and five-jointed toes placed alternately outwards1 first on the one side and then on the other4 ,it is not often that the matrix has been fine enough to retain impressions of the integument or skin of the foot2 but in one fine specimen found at ,turner's ,falls on the ,connecticut1 by ,dr4 ,deane1 these markings are well preserved1 and have been recognized by ,mr4 ,owen as resembling the skin of the ostrich1 and not that of reptiles4#bih-;,b ,much care is required to ascertain the precise layer of a laminated rock on which an animal has walked1 because the impression usually extends downwards through several laminae2 and if the upper layer originally trodden upon is wanting1 one or more joints1 or even in some cases an entire toe1 which sank less deep into the soft ground1 may disappear1 and yet the remainder of the footprint be well defined4 ,the size of several of the fossil impressions of the ,connecticut red sandstone so far exceeds that of any living ostrich1 that naturalists at first were extremely adverse to the opinion of their having been made by birds1 until the bones and almost entire skeleton of the ,dinornis and of other feathered giants of ,new ,zealand were discovered4 ,their dimensions have at least destroyed the force of this particular objection4 ,the magnitude of the impressions of the feet of a heavy animal1 which has walked on soft mud1 increases for some distance below the surface originally trodden upon4 ,in order1 therefore1 to guard against exaggeration1 the casts rather than the mould are relied on4 ,these casts show that some of the fossil birds had feet four times as large as the ostrich1 but not perhaps larger than the ,dinornis4 ,some of the quadrupedal footprints which accompany those of birds are analogous to ,european ,chirotheria1 and with a similar disproportion between the hind and fore feet4 ,others resemble that remarkable reptile1 the ,rhyncosaurus of the ,english ,trias1 a creature having some relation in its osteology both to chelonians and birds4 ,other imprints1 again1 are like those of turtles4 ,among the supposed bipedal tracks1 a single distinct example only has been observed of feet in which there are four toes directed forwards4 ,in this case a series of four footprints is seen1 each #bb inches long and #ab wide1 with joints much resembling those in the toes of birds4 ,professor ,agassiz has suggested that it might have belonged to a gigantic bipedal batrachian2 but the evidence on this subject is too defective to warrant such a bold conjecture1 and if we were to give the reins to our imagination1 we might as well conceive a bird having four toes projecting forwards as a huge two-legged frog4 ,nor should we forget that some quadrupeds place the hind foot so precisely on the spot just quitted by the fore foot1 as to produce a single line of imprints like a biped4 ,no bones have as yet been met with1 whether of reptiles or birds1 in the rocks of the ,connecticut1 but there are numerous coprolites2 and an ingenious argument has been derived by ,mr4 ,dana1 from the analysis of these bodies1 and the proportion they contain of uric acid1 phosphate of lime1 carbonate of lime1 and organic matter1 to show that1 like guano1 they are the droppings of birds1 rather than of reptiles4#bii-;,a ,mr4 ,darwin1 in his ,journal of a ,voyage in the ,beagle1 informs us that the ,south ,american ostriches1 although they live on vegetable matter1 such as roots and grass1 are repeatedly seen at ,bahia ,blanca 7lat4 #ci deg4 ,s471 on the coast of ,buenos ,ayres1 coming down at low water to the extensive mud-banks which are then dry1 for the sake1 as the ,gauchos say1 of feeding on small fish4 ,they readily take to the water1 and have been seen at the bay of ,san ,blas1 and at ,port ,valdez1 in ,patagonia1 swimming from island to island4#cjj-;,a ,it is therefore evident1 that in our times a ,south ,american mud-bank might be trodden simultaneously by ostriches1 alligators1 tortoises1 and frogs2 and the impressions left1 in the nineteenth century1 by the feet of these various tribes of animals1 would not differ from each other more entirely than do those attributed to birds1 saurians1 chelonians1 and batrachians1 in the rocks of the ,connecticut4 ,to determine the exact age of the red sandstone and shale containing these ancient footprints in the ,united ,states1 is not possible at present4 ,no fossil shells have yet been found in the deposit1 nor plants in a determinable state4 ,the fossil fish are numerous and very perfect2 but they are of a peculiar type1 which was originally referred to the genus ,palaeoniscus1 but has since1 with propriety1 been ascribed1 by ,sir ,philip ,egerton1 to a new genus4 ,to this he has given the name of ,ischypterus1 from the great size and strength of the fulcral rays of the dorsal fin 7from ischys2 strength1 and pteron1 a fin74 ,they differ from ,palaeoniscus1 as ,mr4 ,redfield first pointed out1 by having the vertebral column prolonged to a more limited extent into the upper lobe of the tail1 or1 in the language of ,m4 ,agassiz1 they are less heterocercal4 ,the teeth also1 according to ,sir ,p4 ,egerton1 who1 in #ahdd1 examined for me a fine series of specimens which ,i procured at ,durham1 ,connecticut1 differ from those of ,palaeoniscus in being strong and conical4 ,that the sandstones containing these fish are of older date than the strata containing coal1 before described 7p4 #bhd47 as occurring near ,richmond in ,virginia1 is highly probable4 ,these were shown to be as old at least as the oolite and lias4 ,the higher antiquity of the ,connecticut beds cannot be proved by direct superposition1 but may be presumed from the general structure of the country4 ,that structure proves them to be newer than the movements to which the ,appalachian or ,alleghany chain owes its flexures1 and this chain includes the ancient coal formation among its contorted rocks4 ,the unconformable position of this ,new ,red with ornithichnites on the edges of the inclined primary or paleozoic rocks of the ,appalachians is seen at #d4 of the section1 fig4 #cgi4 p4 #cbg4 ,the absence of fish with decidedly heterocercal tails may afford an argument against the ,permian age of the formation2 and the opinion that the red sandstone is triassic1 seems1 on the whole1 the best that we can embrace in the present state of our knowledge4 ,,footnotes3 #bhf-;,a ,buckland1 ,bridgew4 ,treat41 vol4 ii4 p4 #ch4 #bhg-;,a ,monog4 des ,bunten ,sandsteins4 #bhh-;,a ,tableau des ,genres de ,veg4 ,fos41 ,dict4 ,univ4 #ahdi4 #bij-;,a ,geol4 ,trans41 ,second ,series1 vol4 v4 #bij-;,b ,buckland1 ,proc4 ,geol4 ,soc4 vol4 ii4 p4 #dci42 and ,murchison and ,strickland ,geol4 ,trans41 ,second ,ser41 vol4 v4 p4 #cdg4 #bie-;,a ,ormerod1 ,quart4 ,geol4 ,journ4 #ahdh1 vol4 iv4 p4 #bgg4 #bif-;,a ,hugh ,miller1 ,first ,impressions of ,england1 #ahdg1 pp4 #ahc4 #bad4 #big-;,a ,buist1 ,trans4 of ,bombay ,geograph4 ,soc4 #ahej1 vol4 ix4 p4 #ch4 #big-;,b ,travels in ,north ,america1 vol4 ii4 p4 #afh4 #bih-;,a ,hitchcock1 ,mem4 of ,amer4 ,acad4 ,new ,ser41 vol4 iii4 p4 #abi4 #bih-;,b ,this specimen is now in ,dr4 ,mantell's museum4 #bii-;,a ,amer4 ,journ4 of ,sci4 vol4 xlviii4 p4 #df4 #cjj-;,a ,journal of ,voyage of ,beagle1 c4 #b;d edition1 p4 #hi4 #ahde4 ,,chapter ,,xxiii4 ,,permian ,,or ,,magnesian ,,limestone ,,group4 ,fossils of ,magnesian ,limestone and ,lower ,new ,red distinct from the ,triassic--,term ,permian--,english and ,german equivalents--,marine shells and corals of ,english ,magnesian limestone--,palaeoniscus and other fish of the marl slate--,thecodont ,saurians of dolomitic conglomerate of ,bristol--,zechstein and ,rothliegendes of ,thuringia--,permian ,flora--,its generic affinity to the carboniferous--,psaronites or tree-ferns4 ,when the use of the term ,poikilitic was explained in the last chapter1 ,i stated1 that in some parts of ,england it is scarcely possible to separate the red marls and sandstones so called 7originally named the ,new ,red71 into two distinct geological systems4 ,nevertheless1 the progress of investigation1 and a careful comparison of ,english rocks between the lias and the coal with those occupying a similar geological position in ,germany and ,russia1 has enabled geologists to divide the ,poikilitic formation2 and has even shown that the lowermost of the two divisions is more closely connected1 by its fossil remains1 with the carboniferous group than with the trias4 ,if1 therefore1 we are to draw a line between the secondary and primary fossiliferous strata1 as between the tertiary and secondary1 it must run through the middle of what was once called the ,new ,red1 or ,poikilitic group4 ,the inferior half of this group will rank as ,primary or ,paleozoic1 while its upper member will form the base of the ,secondary series4 ,for the lower1 or ,magnesian ,limestone division of ,english geologists1 ,sir ,r4 ,murchison has proposed the name of ,permian1 from ,perm1 a ,russian government where these strata are more extensively developed than elsewhere1 occupying an area twice the size of ,france1 and containing an abundant and varied suite of fossils4 ,mr4 ,king1 in his valuable monograph1 recently published1 of the ,permian fossils of ,england1 has given a table of the following six members of the ,permian system of the north of ,england1 with what he conceives to be the corresponding formations in ,thuringia4#cja-;,a ,north of ,england4 ,thuringia4 #a4 ,crystalline or concretionary1 #a4 ,stinkstein4 and non-crystalline limestone4 #b4 ,brecciated and pseudo-brecciated #b4 ,rauchwacke4 limestone4 #c4 ,fossiliferous limestone4 #c4 ,dolomit1 or ,upper ,zechstein4 #d4 ,compact limestone4 #d4 ,zechstein1 or ,lower ,zechstein4 #e4 ,marl-slate4 #e4 ,mergel-schiefer1 or ,kupferschiefer4 #f4 ,inferior sandstones of various #f4 ,rothliegendes4 colours4 ,i shall proceed1 therefore1 to treat briefly of these subdivisions1 beginning with the highest1 and referring the reader1 for a fuller description of the lithological character of the whole group1 as it occurs in the north of ,england1 to a valuable memoir by ,professor ,sedgwick1 published in #ahce4cjb-;,a ,crystalline or concretionary limestone 7,no4 #a474--,this formation is seen upon the coast of ,durham and ,yorkshire1 between the ,wear and the ,tees4 ,among its characteristic fossils are ,schizodus ,schlotheimi 7fig4 #ccc47 and ,mytilus septifer 7fig4 #cce474 ,illustration3 ,fig4 #ccc4 ,schizodus ,schlotheimi1 ,geinitz4 ,syn4 ,axinus obscurus1 ,sow4 ,crystalline limestone1 ,permian4 ,illustration3 ,fig4 #ccd4 ,schizodus truncatus1 ,king2 to show hinge4 ,permian4 ,illustration3 ,fig4 #cce4 ,mytilus septifer1 ,king4 ,syn4 ,modiola acuminata1 ,james ,sow4 ,permian crystalline limestone4 ,these shells occur at ,hartlepool and ,sunderland1 where the rock assumes an oolitic and botryoidal character4 ,some of the beds in this division are ripple-marked2 and ,mr4 ,king imagines that the absence of corals and the character of the shells indicate shallow water4 ,in some parts of the coast of ,durham1 where the rock is not crystalline1 it contains as much as forty-four per cent4 of carbonate of magnesia1 mixed with carbonate of lime4 ,in other places1--for it is extremely variable in structure1--it consists chiefly of carbonate of lime1 and has concreted into globular and hemispherical masses1 varying from the size of a marble to that of a cannon-ball1 and radiating from the centre4 ,occasionally earthy and pulverulent beds pass into compact limestone or hard granular dolomite4 ,the stratification is very irregular1 in some places well-defined1 in others obliterated by the concretionary action which has re-arranged the materials of the rocks subsequently to their original deposition4 ,examples of this are seen at ,pontefract and ,ripon in ,yorkshire4 ,the brecciated limestone 7,no4 #b47 contains no fragments of foreign rocks1 but seems composed of the breaking-up of the ,permian limestone itself1 about the time of its consolidation4 ,some of the angular masses in ,tynemouth ,cliff are #b feet in diameter4 ,this breccia is considered by ,professor ,sedgwick as one of the forms of the preceding limestone1 ,no4 #a41 rather than as regularly underlying it4 ,the fragments are angular and never water-worn1 and appear to have been re-cemented on the spot where they were formed4 ,it is1 therefore1 suggested that they may have been due to those internal movements of the mass which produced the concretionary structure2 but the subject is very obscure1 and after studying the phenomenon in the ,marston ,rocks1 on the coast of ,durham1 ,i found it impossible to form any positive opinion on the subject4 ,the well-known brecciated limestones of the ,pyrenees appeared to me to present the nearest analogy1 but on a much smaller scale4 ,the fossiliferous limestone 7,no4 #c47 is regarded by ,mr4 ,king as a deep-water formation1 from the numerous delicate corals which it includes4 ,one of these1 ,fenestella retiformis 7fig4 #ccf471 is a very variable species1 and has received many different names4 ,it sometimes attains a large size1 measuring #h inches in width4 ,the same zoophyte is also found abundantly in the ,permian of ,germany4 ,illustration3 ,fig4 #ccf4 ,fenestella4 a4 ,fenestella retiformis1 ,schlot4 ,syn4 ,gorgonia infundibuliformis1 ,goldf42 ,retepora flustracea1 ,phillips4 b4 ,part of the same highly magnified4 ,magnesian limestone1 ,humbleton ,hill1 near ,sunderland4#cjc-;,a ,shells of the genera ,spirifer and ,productus1 which do not occur in strata newer than the ,permian1 are abundant in this division of the series in the ordinary yellow magnesian limestone4 7,see figs4 #ccg1 #cch47 ,illustration3 ,fig4 #ccg4 ,productus calvus1 ,sow4 ,min4 ,con4 ,syn4 ,productus horridus1 ,bronn's ,index1 c41 ,king's ,monogr41 c42 ,leptaena1 ,dalman4 ,magnesian ,limestone4 ,illustration3 ,fig4 #cch4 ,spirifer undulatus1 ,sow4 ,min4 ,con4 ,syn4 ,triogonotreta undulata1 ,king's ,monogr4 ,magnesian ,limestone4 ,the compact limestone 7,no4 #d47 also contains organic remains1 especially corallines1 and is intimately connected with the preceding4 ,beneath it lies the marl-slate 7,no4 #e471 which consists of hard1 calcareous shales1 marl-slate1 and thin-bedded limestones4 ,at ,east ,thickley1 in ,durham1 where it is thirty feet thick1 this slate has yielded many fine specimens of fossil fish of the genera ,palaeoniscus1 ,pygopterus1 ,coelacanthus1 and ,platysomus1 genera which are all found in the coal-measures of the carboniferous epoch1 and which therefore1 says ,mr4 ,king1 probably lived at no great distance from the shore4 ,but the ,permian species are peculiar1 and1 for the most part1 identical with those found in the marl-slate or copper-slate of ,thuringia4 ,illustration3 ,fig4 #cci4 ,restored outline of a fish of the genus ,palaeoniscus1 ,agass4 ,palaeothrissum1 ,blainville4 ,the ,palaeoniscus above mentioned belongs to that division of fishes which ,m4 ,agassiz has called ,heterocercal1 which have their tails unequally bilobate1 like the recent shark and sturgeon1 and the vertebral column running along the upper caudal lobe4 7,see fig4 #cdj47 ,the ,homocercal fish1 which comprise almost all the #hjjj species at present known in the living creation1 have the tail-fin either single or equally divided2 and the vertebral column stops short1 and is not prolonged into either lobe4 7,see fig4 #cda47 ,illustration3 ,fig4 #cdj4 ,shark4 ,heterocercal4 ,illustration3 ,fig4 #cda4 ,shad4 7,clupea1 ,herring tribe47 ,homocercal4 ,now it is a singular fact1 first pointed out by ,agassiz1 that the heterocercal form1 which is confined to a small number of genera in the existing creation1 is universal in the ,magnesian limestone1 and all the more ancient formations4 ,it characterizes the earlier periods of the earth's history1 when the organization of fishes made a greater approach to that of saurian reptiles than at later epochs4 ,in all the strata above the ,magnesian limestone the homocercal tail predominates4 ,a full description has been given by ,sir ,philip ,egerton of the species of fish characteristic of the marl-slate in ,mr4 ,king's monograph before referred to1 where figures of the ichthyolites which are very entire and well preserved1 will be found4 ,even a single scale is usually so characteristically marked as to indicate the genus1 and sometimes even the particular species4 ,they are often scattered through the beds singly1 and maybe useful to a geologist in determining the age of the rock4 ,illustration3 ,fig4 #cdb4 ,palaeoniscus comtus1 ,agassiz4 ,scale magnified4 ,marl-slate4 ,illustration3 ,fig4 #cdc4 ,palaeoniscus elegans1 ,sedg4 ,under surface of scale magnified4 ,marl-slate4 ,illustration3 ,fig4 #cdd4 ,palaeoniscus glaphyrus1 ,ag4 ,under surface of scale magnified4 ,marl-slate4 ,illustration3 ,fig4 #cde4 ,coelacanthus caudalis1 ,egerton4 ,scale showing granulated surface magnified4 ,marl-slate4 #b ,illustrations3 ,scales of fish4 ,magnesian limestone4 ,fig4 #cdf4 ,pygopterus mandibularis1 ,ag4 ,marl-slate4 a4 ,outside of scale magnified4 b4 ,under surface of same4 ,fig4 #cdg4 ,acrolepis ,sedgwickii1 ,ag4 ,marl-slate4 ,the inferior sandstones 7,no4 #f4 ,tab4 p4 #cja471 which lie beneath the marl-slate1 consist of sandstone and sand1 separating the magnesian limestone from the coal1 in ,yorkshire and ,durham4 ,in some instances1 red marl and gypsum have been found associated with these beds4 ,they have been classed with the magnesian limestone by ,professor ,sedgwick1 as being nearly co-extensive with it in geographical range1 though their relations are very obscure4 ,in some regions we find it stated that the imbedded plants are all specifically identical with those of the carboniferous series2 and1 if so1 they probably belong to that epoch2 for the true ,permian flora appears1 from the researches of ,,mm4 ,murchison and de ,verneuil in ,russia1 and of ,colonel von ,gutbier in ,saxony1 to be1 with few exceptions1 distinct from that of the coal 7see p4 #cjg474 ,dolomitic conglomerate of ,bristol4--,near ,bristol1 in ,somersetshire1 and in other counties bordering the ,severn1 the unconformable beds of the ,lower ,new ,red1 resting immediately upon the ,coal1 consist of a conglomerate called dolomitic1 because the pebbles of older rocks are cemented together by a red or yellow base of dolomite or magnesian limestone4 ,this conglomerate or breccia1 for the imbedded fragments are sometimes angular1 occurs in patches over the whole of the downs near ,bristol1 filling up the hollows and irregularities in the mountain limestone1 and being principally composed at every spot of the debris of those rocks on which it immediately rests4 ,at one point we find pieces of coal shale1 in another of mountain limestone1 recognizable by its peculiar shells and zoophytes4 ,fractured bones1 also1 and teeth of saurians1 are dispersed through some parts of the breccia4 ,these saurians 7which until the discovery of the ,archegosaurus in the coal were the most ancient examples of fossil reptiles7 are all distinguished by having the teeth implanted deeply in the jaw-bone1 and in distinct sockets1 instead of being soldered1 as in frogs1 to a simple alveolar parapet4 ,in the dolomitic conglomerate near ,bristol the remains of species of two distinct genera have been found1 called ,thecodontosaurus and ,palaeosaurus by ,dr4 ,riley and ,mr4 ,stutchbury#cjf-;,a2 the teeth of which are conical1 compressed1 and with finely serrated edges 7figs4 #cdh and #cdi474 ,illustration3 ,fig4 #cdh4 ,tooth of ,palaeosaurus platyodon1 nat4 size4 ,illustration3 ,fig4 #cdi4 ,tooth of ,thecodontosaurus1 #c times magnified4 ,in ,russia1 also1 ,thecodont saurians occur1 in beds of the ,permian age1 of several genera1 while others named ,protorosaurus are met with in the ,zechstein of ,thuringia4 ,this family of reptiles is allied to the living monitor1 and its appearance in a primary or paleozoic formation1 observes ,mr4 ,owen1 is opposed to the doctrine of the progressive development of reptiles from fish1 or from simpler to more complex forms2 for1 if they existed at the present day1 these monitors would take rank at the head of the ,lacertian order4#cjf-;,b ,in ,russia the ,permian rocks are composed of white limestone1 with gypsum and white salt2 and of red and green grits1 with occasionally copper ore2 also magnesian limestones1 marlstones1 and conglomerates4 ,the country of ,mansfeld1 in ,thuringia1 may be called the classic ground of the ,lower ,new ,red1 or ,magnesian ,limestone1 or ,permian formation1 on the ,continent4 ,it consists there principally of1 first1 the ,zechstein1 corresponding to the upper portion of our ,english series2 and1 secondly1 the marl-slate1 with fish of species identical with those of the bed so called in ,durham4 ,this slaty marlstone is richly impregnated with copper pyrites1 for which it is extensively worked4 ,magnesian limestone1 gypsum1 and rock-salt1 occur among the superior strata of this group4 ,at its base lies the ,rothliegendes1 supposed to correspond with the ,inferior or ,lower ,new ,red ,sandstone above mentioned1 which occupies a similar place in ,england between the marl-slate and coal4 ,its local name of ,rothliegendes1 red-lyer1 or ,roth-todt-liegendes1 red-dead-lyer1 was given by the workmen in the ,german mines from its red colour1 and because the copper has died out when they reach this rock1 which is not metalliferous4 ,it is1 in fact1 a great deposit of red sandstone and conglomerate1 with associated porphyry1 basaltic trap1 and amygdaloid4 ,permian ,flora4--,we learn from the recent investigation of ,colonel von ,gutbier1 that in the ,permian rocks of ,saxony no less than sixty species of fossil plants have been met with1 forty of which have not yet been found elsewhere4 ,two or three of these1 as ,calamites gigas1 ,sphenopteris erosa1 and ,s4 lobata1 are also met with in the government of ,perm in ,russia4 ,seven others1 and among them ,neuropteris ,loshii1 ,pecopteris arborescens1 and ,p4 similis1 with several species of ,walchia 7,lycopodites71 are common to the coal-measures4 ,among the genera also enumerated by ,colonel ,gutbier are ,asterophyllites and ,annularia1 so characteristic of the carboniferous period2 also ,lepidodendron1 which is common to the ,permian of ,saxony1 ,thuringia1 and ,russia1 although not abundant4 ,noeggerathia 7see fig4 #cej471 supposed by ,a4 ,brongniart to be allied to ,cycas1 is another link between the ,permian and carboniferous vegetation4 ,coniferae1 of the ,araucarian division1 also occur2 but these are likewise met with both in older and newer rocks4 ,the plants called ,sigillaria and ,stigmaria1 so marked a feature in the carboniferous period1 are as yet wanting4 ,illustration3 ,fig4 #cej4 ,noeggerathia cuneifolia4 ,ad4 ,brongniart4#cjg-;,a ,among the remarkable fossils of the rothliegendes1 or lowest part of the ,permian in ,saxony and ,bohemia1 are the silicified trunks of tree-ferns called generically ,psaronius4 ,their bark was surrounded by a dense mass of air-roots1 which often constituted a great addition to the original stem1 so as to double or quadruple its diameter4 ,the same remark holds good in regard to certain living extra-tropical arborescent ferns1 particularly those of ,new ,zealand4 ,psaronites are also found in the uppermost coal of ,autun in ,france1 and in the upper coal-measures of the ,state of ,ohio in the ,united ,states1 but specifically different from those of the rothliegendes4 ,they serve to connect the ,permian flora with the more modern portion of the preceding or carboniferous group4 ,upon the whole1 it is evident that the ,permian plants approach nearer to the carboniferous ones than to the triassic2 and the same may be said of the ,permian fauna4 ,,footnotes3 #cja-;,a ,palaeontographical ,society1 #ahdh1 ,london4 #cjb-;,a ,trans4 ,geol4 ,soc4 ,lond41 ,second ,series1 vol4 iii4 p4 #cg4 #cjc-;,a ,king's ,monograph1 pl4 #b4 #cjf-;,a ,see paper by ,messrs4 ,riley and ,stutchbury1 ,geol4 ,trans41 ,second ,series1 vol4 v4 p4 #cdi41 plate #bi41 figures #b4 and #e4 #cjf-;,b ,owen1 ,report on ,reptiles1 ,british ,assoc41 ,eleventh ,meeting1 #ahda1 p4 #aig4 #cjg-;,a ,murchison's ,russia1 vol4 ii4 pl4 ,a4 fig4 #c4 ,,chapter ,,xxiv4 ,,the ,,coal1 ,,or ,,carboniferous ,,group4 ,carboniferous strata in the south-west of ,england--,superposition of ,coal-measures to ,mountain limestone--,departure from this type in ,north of ,england and ,scotland--,section in ,south ,wales--,underclays with ,stigmaria--,carboniferous ,flora--,ferns1 ,lepidodendra1 ,calamites1 ,asterophyllites1 ,sigillariae1 ,stigmariae--,coniferae--,endogens--,abs ence of ,exogens--,coal1 how formed--,erect fossil trees--,parkfield ,colliery--,st4 ,etienne1 ,coal-field--,oblique trees or snags--,fossil forests in ,nova ,scotia--,brackish water and marine strata--,origin of ,clay-iron-stone4 ,the next group which we meet with in the descending order is the ,carboniferous1 commonly called ,the ,coal2 because it contains many beds of that mineral1 in a more or less pure state1 interstratified with sandstones1 shales1 and limestones4 ,the coal itself1 even in ,great ,britain and ,belgium1 where it is most abundant1 constitutes but an insignificant portion of the whole mass4 ,in the north of ,england1 for example1 the thickness of the coal-bearing strata has been estimated at #cjjj feet1 while the various coal-seams1 #bj or #cj in number1 do not in the aggregate exceed #fj feet4#cjh-;,a ,the carboniferous formation comprises two very distinct members3 #ast1 that usually called the ,coal-measures1 of mixed freshwater1 terrestrial1 and marine origin1 often including seams of coal2 #b;dly1 that named in ,england the ,mountain or ,carboniferous limestone1 of purely marine origin1 and containing corals1 shells1 and encrinites4 ,in the south-western part of our island1 in ,somersetshire and ,south ,wales1 the three divisions usually spoken of by ,english geologists are3 #a4 ,coal-measures ,strata of shale1 sandstone1 and grit1 with occasional seams of coal1 from #fjj to #ab1jjj feet thick4 #b4 ,millstone grit ,a coarse quartzose sandstone passing into a conglomerate1 sometimes used for millstones1 with beds of shale2 usually devoid of coal2 occasionally above #fjj feet thick4 #c4 ,mountain or ,a calcareous rock containing marine shells and ,carboniferous corals2 devoid of coal2 thickness variable1 limestone sometimes #ijj feet4 ,the millstone grit may be considered as one of the coal sandstones of coarser texture than usual1 with some accompanying shales1 in which coal plants are occasionally found4 ,in the north of ,england some bands of limestone1 with pectens1 oysters1 and other marine shells1 occur in this grit1 just as in the regular coal-measures1 and even a few seams of coal4 ,i shall treat1 therefore1 of the whole group1 as consisting of two divisions only1 the ,coal-measures and ,mountain ,limestone4 ,the latter is found in the southern ,british coal-fields1 at the base of the system1 or immediately in contact with the subjacent ,old ,red ,sandstone2 but as we proceed northwards to ,yorkshire and ,northumberland it begins to alternate with true coal-measures1 the two deposits forming together a series of strata about #ajjj feet in thickness4 ,to this mixed formation succeeds the great mass of genuine mountain limestone4#cji-;,a ,farther north1 in the ,fifeshire coal-field in ,scotland1 we observe a still wider departure from the type of the south of ,england1 or a more complete intercalation of dense masses of marine limestones with sandstones1 and shales containing coal4 ,,coal-,,measures4 ,in ,south ,wales the coal-measures have been ascertained by actual measurement to attain the extraordinary thickness of #ab1jjj feet1 the beds throughout1 with the exception of the coal itself1 appearing to have been formed in water of moderate depth1 during a slow but perhaps intermittent depression of the ground1 in a region to which rivers were bringing a never-failing supply of muddy sediment and sand4 ,the same area was sometimes covered with vast forests1 such as we see in the deltas of great rivers in warm climates1 which are liable to be submerged beneath fresh or salt water should the ground sink vertically a few feet4 ,in one section near ,swansea1 in ,south ,wales1 where the total thickness of strata is #cbdf feet1 we learn from ,sir ,h4 ,de la ,beche that there are ten principal masses of sandstone4 ,one of these is #ejj feet thick1 and the whole of them make together a thickness of #babe feet4 ,they are separated by masses of shale1 varying in thickness from #aj to #ej feet4 ,the intercalated coal-beds1 sixteen in number1 are generally from #a to #e feet thick1 one of them1 which has two or three layers of clay interposed1 attaining #i feet4#cji-;,b ,at other points in the same coal-field the shales predominate over the sandstones4 ,the horizontal extent of some seams of coal is much greater than that of others1 but they all present one characteristic feature1 in having1 each of them1 what is called its underclay4 ,these underclays1 co-extensive with every layer of coal1 consist of arenaceous shale1 sometimes called firestone1 because it can be made into bricks which stand the fire of a furnace4 ,they vary in thickness from #f inches to more than #aj feet2 and ,mr4 ,logan first announced to the scientific world in #ahda that they were regarded by the colliers in ,south ,wales as an essential accompaniment of each of the one hundred seams of coal met with in their coal-field4 ,they are said to form the floor on which the coal rests2 and some of them have a slight admixture of carbonaceous matter1 while others are quite blackened by it4 ,all of them1 as ,mr4 ,logan pointed out1 are characterized by inclosing a peculiar species of fossil vegetable called ,stigmaria1 to the exclusion of other plants4 ,it was also observed that1 while in the overlying shales or roof of the coal1 ferns and trunks of trees abound without any ,stigmariae1 and are flattened and compressed1 those singular plants in the underclays always retain their natural forms1 branching freely1 and sending out their slender leaves1 as they were formerly styled1 through the mud in all directions4 ,several species of ,stigmaria had long been known to botanists1 and described by them1 before their position under each seam of coal was pointed out4 ,it was conjectured that they might be aquatic1 perhaps floating plants1 which sometimes extended their branches and leaves freely in fluid mud1 and which were finally enveloped in the same mud4 ,,carboniferous ,,flora4 ,these statements will suffice to convince the reader that we cannot arrive at a satisfactory theory of the origin of coal till we understand the true nature of ,stigmaria2 and in order to explain what is now known of this plant1 and of others which have contributed by their decay to produce coal1 it will be necessary to offer a brief preliminary sketch of the whole carboniferous flora1 an assemblage of fossil plants1 with which we are better acquainted than with any other which flourished antecedently to the tertiary epoch4 ,it should also be remarked that ,goeppert has ascertained that the remains of every family of plants scattered through the coal-measures are sometimes met with in the pure coal itself1 a fact which adds greatly to the geological interest attached to this flora4 ,ferns4--,the number of species of carboniferous plants hitherto described amounts1 according to ,m4 ,ad4 ,brongniart1 to about #ejj4 ,these may perhaps be a fragment only of the entire flora1 but they are enough to show that the state of the vegetable world was then extremely different from that now established4 ,we are struck at the first glance with the similarity of many of the ferns to those now living1 and the dissimilarity of almost all the other fossils except the coniferae4 ,among the ferns1 as in the case of ,pecopteris for example 7fig4 #cea471 it is not always easy to decide whether they should be referred to different genera from those established for the classification of living species2 whereas1 in regard to most of the other contemporary tribes1 with the exception of the coniferae1 it is often difficult to guess the family1 or even the class1 to which they belong4 ,the ferns of the carboniferous period are generally without organs of fructification1 but in some specimens these are well preserved4 ,in the general absence of such characters1 they have been divided into genera1 distinguished chiefly by the branching of the fronds1 and the way in which the veins of the leaves are disposed4 ,the larger portion are supposed to have been of the size of ordinary ,european ferns1 but some were decidedly arborescent1 especially the group called ,caulopteris1 by ,lindley1 and the ,psaronius of the upper or newest coal-measures1 before alluded to 7p4 #cjg474 ,illustration3 ,fig4 #cea4 ,pecopteris lonchitica4 7,foss4 ,flo4 #aec47 ,illustration3 ,fig4 #ceb4 ,sphenopteris4 7,foss4 ,flo4 #aja47 a4 ,sphenopteris crenata4 b4 ,the same1 magnified4 ,illustration3 ,fig4 #cec4 ,caulopteris primaeva1 ,lindley4 ,all the recent tree-ferns belong to one tribe 7,polypodiaceae71 and to a small number only of genera in that tribe1 in which the surface of the trunk is marked with scars1 or cicatrices1 left after the fall of the fronds4 ,these scars resemble those of ,caulopteris 7see fig4 #cec474 ,no less than #bej ferns have already been obtained from the coal strata2 and even if we make some reduction on the ground of varieties which have been mistaken1 in the absence of their fructification1 for species1 still the result is singular1 because the whole of ,europe affords at present no more than #ej indigenous species4 #c ,illustrations3 ,living tree-ferns of different genera4 7,ad4 ,brong47 ,fig4 #ced4 ,tree-fern from ,isle of ,bourbon4 ,fig4 #cee4 ,cyathea glauca1 ,mauritius4 ,fig4 #cef4 ,tree fern from ,brazil4 #c ,illustrations3 ,lepidodendron ,sternbergii4 ,coal-measures1 near ,newcastle4 ,fig4 #ceg4 ,branching trunk1 #di feet long1 supposed to have belonged to ,l4 ,sternbergii4 7,foss4 ,flo4 #bjc47 ,fig4 #ceh4 ,branching stem with bark and leaves of ,l4 ,sternbergii4 7,foss4 ,flo4 #d47 ,fig4 #cei4 ,portion of same nearer the root2 natural size4 7,ibid47 ,lepidodendra4--,these fossils belong to the family of ,lycopodiums1 yet most of them grew to the size of large trees4 ,the annexed figures represent a large fossil ,lepidodendron1 #di feet long1 found in ,jarrow ,colliery1 near ,newcastle1 lying in shale parallel to the planes of stratification4 ,fragments of others1 found in the same shale1 indicate1 by the size of the rhomboidal scars which cover them1 a still greater magnitude4 ,the living club-mosses1 of which there are about #bjj species1 are abundant in tropical climates1 where one species is sometimes met with attaining a height of #c feet4 ,they usually creep on the ground1 but some stand erect1 as the ,l4 densum1 from ,new ,zealand 7fig4 #cfj474 ,illustration3 ,fig4 #cfj4 ,lycopodium4 a4 ,lycopodium densum2 banks of ,r4 ,thames1 ,new ,zealand4 b4 branch1 natural size4 c4 part of same1 magnified4 ,in the carboniferous strata of ,coalbrook ,dale1 and in many other coal-fields1 elongated cylindrical bodies1 called fossil cones1 named by ,m4 ,adolphe ,brongniart ,lepidostrobus1 are met with4 7,see fig4 #cfa47 ,they often form the nucleus of concretionary balls of clay-iron-stone1 and are well preserved1 exhibiting a conical axis1 around which a great quantity of scales were compactly imbricated4 ,the opinion of ,m4 ,brongniart is now generally adopted1 that the ,lepidostrobus is the fruit of ,lepidodendron4 ,illustration3 ,fig4 #cfa4 ,lepidostrobus ornatus1 ,brong42 half nat4 size4 ,shropshire4 ,illustration3 ,fig4 #cfb4 ,calamites cannaeformis1 ,schlot4 7,foss4 ,flo4 #gi47 ,lower end with rootlets4 ,illustration3 ,fig4 #cfc4 ,calamites ,suckowii1 ,brong42 natural size4 ,common in coal throughout ,europe4 ,equisetaceae4--,to this family belong two species of the genus ,equisetites1 allied to the living horse-tail which now grows in marshy grounds4 ,other species1 which have jointed stems1 depart more widely from ,equisetum1 but are yet of analogous organization4 ,they differed from it principally in being furnished with a thin bark1 which is represented in the stem of ,c4 ,suckowii 7fig4 #cfc471 in which it will be seen that the striped external pattern does not agree with that left on the stone where the bark is stripped off2 so that if the two impressions were seen separately1 they might be mistaken for two distinct species4 ,the tallest living horse-tails are only #b or #c feet high in ,europe1 and even in tropical climates only attain1 as in the case of ,equisetum giganteum1 discovered by ,humboldt and ,bonpland1 in ,south ,america1 a height of about #e feet1 the stem being an inch in diameter4 ,several of the ,calamites of the coal acquired the height and dimensions of small trees4 ,illustration3 ,fig4 #cfd4 ,asterophyllites foliosa4 7,foss4 ,flo4 #be47 ,coal-measures1 ,newcastle4 ,asterophyllites4--,in this family1 ,m4 ,brongniart includes several genera1 and among them ,calamodendron1 ,asterophyllites1 and ,annularia4 ,the graceful plant1 represented in the annexed figure1 is supposed to be the branch of a shrub called ,calamodendron1 a new genus1 divided off by ,brongniart from the ,calamites of former authors4 ,its pith and medullary rays seem to show that it was dicotyledonous1 and it appears to have been allied1 by the nature of its tissue1 to the gymnogens1 or1 still more1 to the ,sigillaria1 which will next be mentioned4 ,sigillaria4--,a large portion of the trees of the carboniferous period belonged to this genus1 of which about thirty-five species are known4 ,the structure1 both internal and external1 was very peculiar1 and1 with reference to existing types1 very anomalous4 ,they were formerly referred1 by ,m4 ,ad4 ,brongniart1 to ferns1 which they resemble in the scalariform texture of their vessels1 and1 in some degree1 in the form of the cicatrices left by the base of the leafstalks which have fallen off 7see fig4 #cfe474 ,but with these points of analogy to cryptogamia1 they combine an internal organization much resembling that of cycads1 and some of them are ascertained to have had long linear leaves1 quite unlike those of ferns4 ,they grew to a great height1 from #cj to #fj1 or even #gj feet1 with regular cylindrical stems1 and without branches1 although some species were dichotomous towards the top4 ,their fluted trunks1 from #a to #e feet in diameter1 appear to have decayed rapidly in the interior1 so as to become hollow1 when standing2 when1 therefore1 they were thrown prostrate on the mud1 they were squeezed down and flattened4 ,hence1 we find the bark of the two opposite sides 7now converted into bright shining coal7 to constitute two horizontal layers1 one upon the other1 half an inch1 or an inch1 in thickness4 ,these same trunks1 when they are placed obliquely or vertically to the planes of stratification1 retain their original rounded form1 and are uncompressed1 the cylinder of bark having been filled with sand1 which now affords a cast of the interior4 ,illustration3 ,fig4 #cfe4 ,sigillaria laevigata1 ,brong4 ,stigmaria4--,this fossil1 the importance of which has already been pointed out1 was formerly conjectured to be an aquatic plant4 ,it is now ascertained to be the root of ,sigillaria4 ,the connection of the roots with the stem1 previously suspected1 on botanical grounds1 by ,brongniart1 was first proved1 by actual contact1 in the ,lancashire coal-field1 by ,mr4 ,binney4 ,the fact has lately been shown1 even more distinctly1 by ,mr4 ,richard ,brown1 in his description of the ,stigmariae occurring in the underclays of the coal-seams of the ,island of ,cape ,breton1 in ,nova ,scotia4 ,illustration3 ,fig4 #cff4 ,stigmaria attached to a trunk of ,sigillaria4#cae-;,a ,in a specimen of one of these1 represented in the annexed figure 7fig4 #cff471 the spread of the roots was #af feet1 and some of them sent out rootlets1 in all directions1 into the surrounding clay4 ,the manner of attachment of the fibres to the stem resembles that of a ball and socket joint1 the base of each rootlet being concave1 and fitting on to a tubercle 7see figs4 #cfg and #cfh474 ,rows of these tubercles are arranged spirally round each root1 which have always a medullary cavity and woody texture1 much resembling that of ,sigillaria1 the structure of the vessels being1 like it1 scalariform4 ,illustration3 ,fig4 #cfg4 ,surface of another individual of same species1 showing form of tubercles4 7,foss4 ,flo4 #cd47 ,illustration3 ,fig4 #cfh4 ,stigmaria ficoides1 ,brong4 ,one fourth of nat4 size4 7,foss4 ,flo4 #cb47 ,conifers4--,the coniferous trees of this period are referred to five genera2 the woody structure of some of them showing that they were allied to the ,araucarian division of pines1 more than to any of our common ,european firs4 ,some of their trunks exceeded #dd feet in height4 ,endogens4--,hitherto but few monocotyledonous plants have been discovered in the coal-strata4 ,most of these consist of fruits referred by some botanists to palms4 ,the three-sided nuts1 called ,trigonocarpum1 seven species of which are known1 appear to have the best claim to rank as palms1 although ,m4 ,ad4 ,brongniart entertains some doubt even as to their being monocotyledons4 ,exogens4 ,the entire absence1 so far as our paleontological investigations have hitherto gone1 of ordinary dicotyledons or exogens in the coal measures1 is most remarkable4 ,hence1 ,m4 ,adolphe ,brongniart has called this period the age of acrogens1 in consequence of the vast preponderance of ferns and ,lepidodendra4#caf-;,a ,nevertheless1 a forest of the period1 now under consideration1 may have borne a considerable resemblance to those woody regions of ,new ,zealand1 in which ferns1 arborescent and herbaceous1 and lycopodiums1 with many coniferae1 abound4 ,the comparative proportion of living ferns and ,araucariae1 in ,norfolk ,island1 to all the other plants1 appears to be very similar to that formerly borne by these tribes respectively in a forest of the coal-period4 ,i have already stated that ,professor ,goeppert1 after examining the fossil vegetables of the coal-fields of ,germany1 has detected1 in beds of pure coal1 remains of plants of every family hitherto known to occur fossil in the coal4 ,many seams1 he remarks1 are rich in ,sigillaria1 ,lepidodendron1 and ,stigmaria1 the latter in such abundance1 as to appear to form the bulk of the coal4 ,in some places1 almost all the plants are calamites1 in others ferns4#caf-;,b ,coal1 how formed--,erect trees4--,i shall now consider the manner in which the above-mentioned plants are imbedded in the strata1 and how they may have contributed to produce coal4 ,some of the plants of our coal1 says ,dr4 ,buckland1 grew on the identical banks of sand1 silt1 and mud1 which1 being now indurated to stone and shale1 form the strata that accompany the coal2 whilst other portions of these plants have been drifted to various distances from the swamps1 savannahs1 and forests that gave them birth1 particularly those that are dispersed through the sandstones1 or mixed with fishes in the shale beds4 ,at ,balgray1 three miles north of ,glasgow1 says the same author1 ,i saw in the year #ahbd1 as there still may be seen1 an unequivocal example of the stumps of several stems of large trees1 standing close together in their native place1 in a quarry of sandstone of the coal formation4#cag-;,a ,between the years #ahcg and #ahdj1 six fossil trees were discovered in the coal-field of ,lancashire1 where it is intersected by the ,bolton railway4 ,they were all in a vertical position1 with respect to the plane of the bed1 which dips about #ae deg4 to the south4 ,the distance between the first and the last was more than #ajj feet1 and the roots of all were imbedded in a soft argillaceous shale4 ,in the same plane with the roots is a bed of coal1 eight or ten inches thick1 which has been ascertained to extend across the railway1 or to the distance of at least ten yards4 ,just above the covering of the roots1 yet beneath the coal seam1 so large a quantity of the ,lepidostrobus variabilis was discovered inclosed in nodules of hard clay1 that more than a bushel was collected from the small openings around the base of the trees 7see figure of this genus1 p4 #cac474 ,the exterior trunk of each was marked by a coating of friable coal1 varying from one quarter to three quarters of an inch in thickness2 but it crumbled away on removing the matrix4 ,the dimensions of one of the trees is #ae-a_/b feet in circumference at the base1 #g-a_/b feet at the top1 its height being #aa feet4 ,all the trees have large spreading roots1 solid and strong1 sometimes branching1 and traced to a distance of several feet1 and presumed to extend much farther4 ,mr4 ,hawkshaw1 who has described these fossils1 thinks that1 although they were hollow when submerged1 they may have consisted originally of hard wood throughout2 for solid dicotyledonous trees1 when prostrated in tropical forests1 as in ,venezuela1 on the shore of the ,caribbean ,sea1 were observed by him to be destroyed in the interior1 so that little more is left than an outer shell1 consisting chiefly of the bark4 ,this decay1 he says1 goes on most rapidly in low and flat tracks1 in which there is a deep rich soil and excessive moisture1 supporting tall forest-trees and large palms1 below which bamboos1 canes1 and minor palms flourish luxuriantly4 ,such tracts1 from their lowness1 would be most easily submerged1 and their dense vegetation might then give rise to a seam of coal4#cag-;,b ,in a deep valley near ,capel-,coelbren1 branching from the higher part of the ,swansea valley1 four stems of upright ,sigillariae were seen1 in #ahch1 piercing through the coal-measures of ,s4 ,wales2 one of them was #b feet in diameter1 and one #ac feet and a half high1 and they were all found to terminate downwards in a bed of coal4 ,they appear1 says ,sir ,h4 ,de la ,beche1 to have constituted a portion of a subterranean forest at the epoch when the lower carboniferous strata were formed4#cah-;,a ,in a colliery near ,newcastle1 say the authors of the ,fossil ,flora1 a great number of ,sigillariae were placed in the rock as if they had retained the position in which they grew4 ,not less than thirty1 some of them #d or #e feet in diameter1 were visible within an area of #ej yards square1 the interior being sandstone1 and the bark having been converted into coal4 ,the roots of one individual were found imbedded in shale2 and the trunk1 after maintaining a perpendicular course and circular form for the height of about #aj feet1 was then bent over so as to become horizontal4 ,here it was distended laterally1 and flattened so as to be only one inch thick1 the flutings being comparatively distinct4#cah-;,b ,such vertical stems are familiar to our miners1 under the name of coal-pipes4 ,one of them1 #gb feet in length1 was discovered1 in #ahbi1 near ,gosforth1 about five miles from ,newcastle1 in coal-grit1 the strata of which it penetrated4 ,the exterior of the trunk was marked at intervals with knots1 indicating the points at which branches had shot off4 ,the wood of the interior had been converted into carbonate of lime2 and its structure was beautifully shown by cutting transverse slices1 so thin as to be transparent4 7,see p4 #dj47 ,these coal-pipes are much dreaded by our miners1 for almost every year in the ,bristol1 ,newcastle1 and other coal-fields1 they are the cause of fatal accidents4 ,each cylindrical cast of a tree1 formed of solid sandstone1 and increasing gradually in size towards the base1 and being without branches1 has its whole weight thrown downwards1 and receives no support from the coating of friable coal which has replaced the bark4 ,as soon1 therefore1 as the cohesion of this external layer is overcome1 the heavy column falls suddenly in a perpendicular or oblique direction from the roof of the gallery whence coal has been extracted1 wounding or killing the workman who stands below4 ,it is strange to reflect how many thousands of these trees fell originally in their native forests in obedience to the law of gravity2 and how the few which continued to stand erect1 obeying1 after myriads of ages1 the same force1 are cast down to immolate their human victims4 ,it has been remarked1 that if1 instead of working in the dark1 the miner was accustomed to remove the upper covering of rock from each seam of coal1 and to expose to the day the soils on which ancient forests grew1 the evidence of their former growth would be obvious4 ,thus in ,south ,staffordshire a seam of coal was laid bare in the year #ahdd1 in what is called an open work at ,parkfield ,colliery1 near ,wolverhampton4 ,in the space of about a quarter of an acre the stumps of no less than #gc trees with their roots attached appeared1 as shown in the annexed plan 7fig4 #cfi471 some of them more than #h feet in circumference4 ,the trunks1 broken off close to the root1 were lying prostrate in every direction1 often crossing each other4 ,one of them measured #ae1 another #cj feet in length1 and others less4 ,they were invariably flattened to the thickness of one or two inches1 and converted into coal4 ,their roots formed part of a stratum of coal #aj inches thick1 which rested on a layer of clay #b inches thick1 below which was a second forest1 resting on a #b-;foot seam of coal4 ,five feet below this again was a third forest with large stumps of ,lepidodendra1 ,calamites1 and other trees4 ,illustration3 ,fig4 #cfi4 ,ground-plan of a fossil forest1 ,parkfield ,colliery1 near ,wolverhampton1 showing the position of #gc trees in a quarter of an acre4#cai-;,a ,in the account given1 in #ahba1 by ,m4 ,alex4 ,brongniart of the coal-mine of ,treuil1 at ,st4 ,etienne1 near ,lyons1 he states1 that distinct horizontal strata of micaceous sandstone are traversed by vertical trunks of monocotyledonous vegetables1 resembling bamboos or large ,equiseta4#cai-;,b ,since the consolidation of the stone1 there has been here and there a sliding movement1 which has broken the continuity of the stems1 throwing the upper parts of them on one side1 so that they are often not continuous with the lower4 ,from these appearances it was inferred that we have here the monuments of a submerged forest4 ,i formerly objected to this conclusion1 suggesting that1 in that case1 all the roots ought to have been found at one and the same level1 and not scattered irregularly through the mass4 ,i also imagined that the soil to which the roots were attached should have been different from the sandstone in which the trunks are enclosed4 ,having1 however1 seen calamites near ,pictou1 in ,nova ,scotia1 buried at various heights in sandstone and in similar erect attitudes1 ,i have now little doubt that ,m4 ,brongniart's view was correct4 ,these plants seem to have grown on a sandy soil1 liable to be flooded from time to time1 and raised by new accessions of sediment1 as may happen in swamps near the banks of a large river in its delta4 ,trees which delight in marshy grounds are not injured by being buried several feet deep at their base2 and other trees are continually rising up from new soils1 several feet above the level of the original foundation of the morass4 ,in the banks of the ,mississippi1 when the water has fallen1 ,i have seen sections of a similar deposit in which portions of the stumps of trees with their roots in situ appeared at many different heights4#cbj-;,a ,illustration3 ,fig4 #cgj4 ,section showing the erect position of fossil trees in coal sandstone at ,st4 ,etienne4 7,alex4 ,brongniart47 ,when ,i visited1 in #ahdc1 the quarries of ,treuil above-mentioned1 the fossil trees seen in fig4 #cgj4 were removed1 but ,i obtained proofs of other forests of erect trees in the same coal-field4 ,illustration3 ,fig4 #cga4 ,inclined position of a fossil tree1 cutting through horizontal beds of sandstone1 ,craigleith quarry1 ,edinburgh4 ,angle of inclination from a to b #bg deg44 ,snags4--,in #ahcj1 a slanting trunk was exposed in ,craigleith quarry1 near ,edinburgh1 the total length of which exceeded #fj feet4 ,its diameter at the top was about #g inches1 and near the base it measured #e feet in its greater1 and #b feet in its lesser width4 ,the bark was converted into a thin coating of the purest and finest coal1 forming a striking contrast in colour with the white quartzose sandstone in which it lay4 ,the annexed figure represents a portion of this tree1 about #ae feet long1 which ,i saw exposed in #ahcj1 when all the strata had been removed from one side4 ,the beds which remained were so unaltered and undisturbed at the point of junction1 as clearly to show that they had been tranquilly deposited round the tree1 and that the tree had not subsequently pierced through them1 while they were yet in a soft state4 ,they were composed chiefly of siliceous sandstone1 for the most part white2 and divided into laminae so thin1 that from six to fourteen of them might be reckoned in the thickness of an inch4 ,some of these thin layers were dark1 and contained coaly matter2 but the lowest of the intersected beds were calcareous4 ,the tree could not have been hollow when imbedded1 for the interior still preserved the woody texture in a perfect state1 the petrifying matter being1 for the most part1 calcareous4#cba-;,a ,it is also clear1 that the lapidifying matter was not introduced laterally from the strata through which the fossil passes1 as most of these were not calcareous4 ,it is well known that1 in the ,mississippi and other great ,american rivers1 where thousands of trees float annually down the stream1 some sink with their roots downwards1 and become fixed in the mud4 ,thus placed1 they have been compared to a lance in rest2 and so often do they pierce through the bows of vessels which run against them1 that they render the navigation extremely dangerous4 ,mr4 ,hugh ,miller mentions four other huge trunks exposed in quarries near ,edinburgh1 which lay diagonally across the strata at an angle of about #cj deg41 with their lower or heavier portions downwards1 the roots of all1 save one1 rubbed off by attrition4 ,one of these was #fj and another #gj feet in length1 and from #d to #f feet in diameter4 ,illustration3 ,fig4 #cgb4 ,section of the cliffs of the ,south ,joggins1 near ,minudie1 ,nova ,scotia4 ,the number of years for which the trunks of trees1 when constantly submerged1 can resist decomposition1 is very great2 as we might suppose from the durability of wood1 in artificial piles1 permanently covered by water4 ,hence these fossil snags may not imply a rapid accumulation of beds of sand1 although the channel of a river or part of a lagoon is often filled up in a very few years4 ,nova ,scotia4--,one of the finest examples in the world of a succession of fossil forests of the carboniferous period1 laid open to view in a natural section1 is that seen in the lofty cliffs bordering the ,chignecto ,channel1 a branch of the ,bay of ,fundy1 in ,nova ,scotia4#cba-;,b ,in the annexed section 7fig4 #cgb471 which ,i examined in ,july1 #ahdb1 the beds from c to i are seen all dipping the same way1 their average inclination being at an angle of #bd deg4 ,s4,s4,w4 ,the vertical height of the cliffs is from #aej to #bjj feet2 and between d and g1 in which space ,i observed seventeen trees in an upright position1 or1 to speak more correctly1 at right angles to the planes of stratification1 ,i counted nineteen seams of coal1 varying in thickness from #b inches to #d feet4 ,at low tide a fine horizontal section of the same beds is exposed to view on the beach4 ,the thickness of the beds alluded to1 between d and g1 is about #b1ejj feet1 the erect trees consisting chiefly of large ,sigillariae1 occurring at ten distinct levels1 one above the other2 but ,mr4 ,logan1 who afterwards made a more detailed survey of the same line of cliffs1 found erect trees at seventeen levels1 extending through a vertical thickness of #d1eae feet of strata2 and he estimated the total thickness of the carboniferous formation1 with and without coal1 at no less than #ad1egj feet1 every where devoid of marine organic remains4#cbb-;,a ,the usual height of the buried trees seen by me was from #f to #h feet2 but one trunk was about #be feet high and #d feet in diameter1 with a considerable bulge at the base4 ,in no instance could ,i detect any trunk intersecting a layer of coal1 however thin2 and most of the trees terminated downwards in seams of coal4 ,some few only were based in clay and shale1 none of them in sandstone4 ,the erect trees1 therefore1 appeared in general to have grown on beds of coal4 ,in some of the underclays ,i observed ,stigmaria4 ,illustration3 ,fig4 #cgc4 ,fossil tree at right angles to planes of stratification4 ,coal measures1 ,nova ,scotia4 ,in regard to the plants1 they belonged to the same genera1 and most of them to the same species1 as those met with in the distant coal-fields of ,europe4 ,in the sandstone1 which filled their interiors1 ,i frequently observed fern leaves1 and sometimes fragments of ,stigmaria1 which had evidently entered together with sediment after the trunk had decayed and become hollow1 and while it was still standing under water4 ,thus the tree1 a b1 fig4 #cgc41 the same which is represented at a1 fig4 #cgd41 or in the bed e in the larger section1 fig4 #cgb41 is a hollow trunk #e feet #h inches in length1 traversing various strata1 and cut off at the top by a layer of clay #b feet thick on which rests a seam of coal 7b1 fig4 #cgd47 #a foot thick4 ,on this coal again stood two large trees 7c and d71 while at a greater height the trees f and g rest upon a thin seam of coal 7e71 and above them is an underclay1 supporting the #d-;foot coal4 ,illustration3 ,fig4 #cgd4 ,erect fossil trees4 ,coal-measures1 ,nova ,scotia4 ,if we now return to the tree first mentioned 7fig4 #cgc471 we find the diameter 7a b7 #ad inches at the top and #af inches at the bottom1 the length of the trunk #e feet #h inches4 ,the strata in the interior consisted of a series entirely different from those on the outside4 ,the lowest of the three outer beds which it traversed consisted of purplish and blue shale 7c1 fig4 #cgc471 #b feet thick1 above which was sandstone 7d7 #a foot thick1 and1 above this1 clay 7e7 #b feet #h inches4 ,but1 in the interior1 were nine distinct layers of different composition3 at the bottom1 first1 shale #d inches1 then sandstone #a foot1 then shale #d inches1 then sandstone #d inches1 then shale #aa inches1 then clay 7f7 with nodules of ironstone #b inches1 then pure clay #b feet1 then sandstone #c inches1 and1 lastly1 clay #d inches4 ,owing to the outward slope of the face of the cliff1 the section 7fig4 #cgc47 was not exactly perpendicular to the axis of the tree2 and hence1 probably1 the apparent sudden termination at the base without a stump and roots4 ,in this example the layers of matter in the inside of the tree are more numerous than those without2 but it is more common in the coal-measures of all countries to find a cylinder of pure sandstone1--the cast of the interior of a tree1 intersecting a great many alternating beds of shale and sandstone1 which originally enveloped the trunk as it stood erect in the water4 ,such a want of correspondence in the materials outside and inside1 is just what we might expect if we reflect on the difference of time at which the deposition of sediment will take place in the two cases2 the imbedding of the tree having gone on for many years before its decay had made much progress4 ,the high tides of the ,bay of ,fundy1 rising more than #fj feet1 are so destructive as to undermine and sweep away continually the whole face of the cliffs1 and thus a new crop of erect trees is brought into view every three or four years4 ,they are known to extend over a space between two and three miles from north to south1 and more than twice that distance from east to west1 being seen in the banks of streams intersecting the coal-field4 ,in ,cape ,breton1 ,mr4 ,richard ,brown has observed in the ,sydney coal-field a total thickness of coal-measures1 without including the underlying millstone grit1 of #ahdc feet1 dipping at an angle of #h deg44 ,he has published minute details of the whole series1 showing at how many different levels erect trees occur1 consisting of ,sigillaria1 ,lepidodendron1 ,calamite1 and other genera4 ,in one place eight erect trunks1 with roots and rootlets attached to them1 were seen at the same level1 within a horizontal space #hj feet in length4 ,beds of coal of various thickness are interstratified4 ,some of the associated strata are ripple-marked1 with impressions of rain-drops4 ,taking into account forty-one clays filled with roots of ,stigmaria in their natural position1 and eighteen layers of upright trees at other levels1 there is1 on the whole1 clear evidence of at least fifty-nine fossil forests1 ranged one above the other1 in this coal-field1 in the above-mentioned thickness of strata4#cbd-;,a ,the fossil shells in ,cape ,breton and in the ,nova ,scotia section 7fig4 #cgb471 consisting of ,cypris1 ,unio 7871 ,modiola1 ,microconchus carbonarius 7see fig4 #cge471 and ,spirorbis1 seem to indicate brackish water2 but we ought never to be surprised if1 in pursuing the same stratum1 we come to a fresh or purely marine deposit2 for this will depend upon our taking a direction higher up or lower down the ancient river or delta deposit4 ,when the ,purbeck beds of the ,wealden were described in ,chap4 ,,xviii41 ,i endeavoured to explain the intimate connection of strata formed at a river's mouth1 or in the tranquil lagoons of the delta1 or in the sea1 after a slight submergence of the land1 with its dirt-beds4 ,in the ,english coal-fields the same association of fresh1 or rather brackish water with marine strata1 in close connection with beds of coal of terrestrial origin1 has been frequently recognized4 ,thus1 for example1 a deposit near ,shrewsbury1 probably formed in brackish water1 has been described by ,sir ,r4 ,murchison as the youngest member of the carboniferous series of that district1 at the point where the coal-measures are in contact with the ,permian or ,lower ,new ,red4 ,it consists of shales and sandstones about #aej feet thick1 with coal and traces of plants2 including a bed of limestone1 varying from #b to #i feet in thickness1 which is cellular1 and resembles some lacustrine limestones of ,france and ,germany4 ,it has been traced for #cj miles in a straight line1 and can be recognized at still more distant points4 ,the characteristic fossils are a small bivalve1 having the form of a ,cyclas1 a small ,cypris 7fig4 #cgf471 and the microscopic shell of an annelid of an extinct genus called ,microconchus 7fig4 #cge471 allied to ,serpula or ,spirorbis4 ,in the lower coal-measures of ,coalbrook ,dale1 the strata1 according to ,mr4 ,prestwich1 often change completely within very short distances1 beds of sandstone passing horizontally into clay1 and clay into sandstone4 ,the coal-seams often wedge out or disappear2 and sections1 at places nearly contiguous1 present marked lithological distinctions4 ,in this single field1 in which the strata are from #gjj to #hjj feet thick1 between forty and fifty species of terrestrial plants have been discovered1 besides several fishes and trilobites of forms distinct from those occurring in the ,silurian strata4 ,also upwards of forty species of mollusca1 among which are two or three referred to the freshwater genus ,unio1 and others of marine forms1 such as ,nautilus1 ,orthoceras1 ,spirifer1 and ,productus4 ,mr4 ,prestwich suggests that the intermixture of beds containing freshwater shells with others full of marine remains1 and the alternation of coarse sandstone and conglomerate with beds of fine clay or shale containing the remains of plants1 may be explained by supposing the deposit of ,coalbrook ,dale to have originated in a bay of the sea or estuary into which flowed a considerable river subject to occasional freshes4#cbe-;,a #b ,illustrations3 ,freshwater ,fossils--,coal4 ,fig4 #cge4 a4 ,microconchus carbonarius4 b4 var4 of same2 nat4 size1 and magnified4 ,fig4 #cgf4 ,cypris inflata1 natural size1 and magnified4 ,murchison4#cbe-;,b ,in the ,edinburgh coal-field1 at ,burdiehouse1 fossil fishes1 mollusca1 and cypris1 very similar to those in ,shropshire and ,staffordshire1 have been found by ,dr4 ,hibbert4#cbe-;,c ,in the coal-field also of ,yorkshire there are freshwater strata1 some of which contain shells referred to the genus ,unio2 but in the midst of the series there is one thin but very widely spread stratum1 abounding in fishes and marine shells1 such as ,ammonites ,listeri 7fig4 #cgg471 ,orthoceras1 and ,avicula papyracea1 ,goldf4 7fig4 #cgh47cbe-;,d ,illustration3 ,fig4 #cgg4 ,ammonites ,listeri1 ,sow4 ,illustration3 ,fig4 #cgh4 ,avicula papyracea1 ,goldf4 7,pecten papyraceus1 ,sow47 ,no similarly intercalated layer of marine shells has been noticed in the neighbouring coal-field of ,newcastle1 where1 as in ,south ,wales and ,somersetshire1 the marine deposits are entirely below those containing terrestrial and freshwater remains4#cbf-;,a ,clay-iron-stone4--,bands and nodules of clay-iron-stone are common in coal-measures1 and are formed1 says ,sir ,h4 ,de la ,beche1 of carbonate of iron1 mingled mechanically with earthy matter1 like that constituting the shales4 ,mr4 ,hunt1 of the ,museum of ,practical ,geology1 instituted a series of experiments to illustrate the production of this substance1 and found that decomposing vegetable matter1 such as would be distributed through all coal strata1 prevented the farther oxidation of the proto-salts of iron1 and converted the peroxide into protoxide by taking a portion of its oxygen to form carbonic acid4 ,such carbonic acid1 meeting with the protoxide of iron in solution1 would unite with it and form a carbonate of iron2 and this mingling with fine mud1 when the excess of carbonic acid was removed1 might form beds or nodules of argillaceous iron-stone4#cbf-;,b ,,footnotes3 #cjh-;,a ,phillips2 art4 ,geology1 ,encyc4 ,britan4 #cji-;,a ,sedgwick1 ,geol4 ,trans41 ,second ,series1 vol4 iv42 and ,phillips1 ,geol4 of ,yorksh4 part #b4 #cji-;,b ,memoirs of ,geol4 ,survey1 vol4 i4 p4 #aie4 #cae-;,a ,the trunk in this case is referred by ,mr4 ,brown to ,lepidodendron1 but his illustrations seem to show the usual markings assumed by ,sigillaria near its base4 #caf-;,a ,for terminology of classification of plants1 see above1 note1 p4 #bbc4 #caf-;,b ,quart4 ,geol4 ,journ41 vol4 v41 ,mem41 p4 #ag4 #cag-;,a ,anniv4 ,address to ,geol4 ,soc41 #ahdj4 #cag-;,b ,hawkshaw1 ,geol4 ,soc4 ,proceedings1 ,nos4 #fd4 and #fi4 #cah-;,a ,geol4 ,report on ,cornwall1 c4 p4 #adc4 #cah-;,b ,lindley and ,hutton1 ,foss4 ,flo4 part #f4 p4 #aej4 #cai-;,a ,see papers by ,messrs4 ,beckett and ,ick4 ,proceed4 in ,geol4 ,soc41 vol4 iv4 p4 #bhg4 #cai-;,b ,annales des ,mines1 #ahba4 #cbj-;,a ,principles of ,geol41 #hth ed41 p4 #bae4 #cba-;,a ,see figures of texture1 ,witham1 ,foss4 ,veget41 pl4 #c4 #cba-;,b ,see ,lyell's ,travels in ,n4 ,america1 vol4 ii4 p4 #agi4 #cbb-;,a ,quart4 ,geol4 ,journ41 vol4 ii4 p4 #agg4 #cbd-;,a ,geol4 ,quart4 ,journ41 vol4 ii4 p4 #cic42 and vol4 vi4 p4 #aae4 #cbe-;,a ,prestwich1 ,geol4 ,trans41 #b;d ,series1 vol4 v4 p4 #ddj4 ,murchison1 ,silurian ,system1 p4 #aje4 #cbe-;,b ,silurian ,system1 p4 #hd4 #cbe-;,c ,trans4 ,roy4 ,soc4 ,edin4 vol4 xiii4 ,horner1 ,edin4 ,new ,phil4 ,journ41 ,april1 #ahcf4 #cbe-;,d ,phillips2 art4 ,geology1 ,encyc4 ,metrop41 p4 #eij4 #cbf-;,a ,phillips2 art4 ,geology1 ,encyc4 ,metrop41 p4 #eib4 #cbf-;,b ,memoirs of ,geol4 ,survey1 pp4 #ea4 #bee1 c4 ,,chapter ,,xxv4 ,,carboniferous ,,group--continued4 ,coal-fields of the ,united ,states--,section of the country between the ,atlantic and ,mississippi--,position of land in the carboniferous period eastward of the ,alleghanies--,mechanically formed rocks thinning out westward1 and limestones thickening--,uniting of many coal-seams into one thick one--,horizontal coal at ,brownsville1 ,pennsylvania--,vast extent and continuity of single seams of coal--,ancient river-channel in ,forest of ,dean coal-field--,absence of earthy matter in coal--,climate of carboniferous period--,insects in coal--,rarity of air-breathing animals--,great number of fossil fish--,first discovery of the skeletons of fossil reptiles--,footprints of reptilians--,mountain limestone--,its corals and marine shells4 ,it was stated in the last chapter that a great uniformity prevails in the fossil plants of the coal-measures of ,europe and ,north ,america2 and ,i may add that four-fifths of those collected in ,nova ,scotia have been identified with ,european species4 ,hence the former existence at the remote period under consideration 7the carboniferous7 of a continent or chain of islands where the ,atlantic now rolls its waves seems a fair inference4 ,nor are there wanting other and independent proofs of such an ancient land situated to the eastward of the present ,atlantic coast of ,north ,america2 for the geologist deduces the same conclusion from the mineral composition of the carboniferous and some older groups of rocks as they are developed on the eastern flanks of the ,alleghanies1 contrasted with their character in the low country to the westward of those mountains4 ,the annexed diagram 7fig4 #cgi47 will assist the reader in understanding the phenomena now alluded to1 although ,i must guard him against supposing that it is a true section4 ,a great number of details have of necessity been omitted1 and the scale of heights and horizontal distances are unavoidably falsified4 ,illustration3 ,fig4 #cgi4 ,diagram explanatory of the geological structure of a part of the ,united ,states between the ,atlantic and the ,mississippi4 ,length from ,e4 to ,w4 #hej miles4 ,appalachian ,coal ,field4 ,alleghanies1 or ,appalachians4 ,same section--continued4 ,mississippi4 ,illinois ,coal ,field4 ,cincinnati4 ,appalachian ,coal ,field4 ,a ,b4 ,atlantic plain4 ,b ,c4 ,atlantic slope4 ,c ,d4 ,alleghanies or ,appalachian chain4 ,d ,e4 ,appalachian coal-field west of the mountains4 ,e ,f4 ,dome-shaped outcrop of strata on the ,ohio1 older than the coal4 ,f ,g4 ,illinois coal-field4 h4 ,falls and rapids of the rivers at the junction of the hypogene and newer formations4 i1 k1 l1 m4 ,parallel folds of ,appalachians becoming successively more open1 and flatter in going from ,e4 to ,w4 ,references to the different ,formations4 #a4 ,miocene tertiary4 #b4 ,eocene tertiary4 #c4 ,cretaceous strata4 #d4 ,red sandstone with ornithichnites 7new red or trias87 usually much invaded by trap4 #e4 ,coal-measures 7bituminous coal74 #e' ,anthracitic coal-measures4 #e'' ,carboniferous limestone of the ,illinois coal-field1 wanting in the ,appalachian4 #f4 ,old red or ,devonian1 ,olive slate1 c4 #g4 ,primary fossiliferous or ,silurian strata4 #h4 ,hypogene strata1 or gneiss1 mica schist1 c41 with granite veins4 ,note4 ,the dotted lines at i and k express portions of rock removed by denudation1 the amount of which may be estimated by supposing similar lines prolonged from other points where different strata end abruptly at the surface4 ,n4,b4 ,the lower section at 9999 joins on to the upper one at 994 ,starting from the shores of the ,atlantic1 on the eastern side of the ,continent1 we first come to a low region 7,a ,b71 which was called the alluvial plain by the first geographers4 ,it is occupied by tertiary and cretaceous strata1 before described 7pp4 #aga4 #bjf4 and #bbd471 which are nearly horizontal4 ,the next belt1 from ,b to ,c1 consists of granitic rocks 7hypogene71 chiefly gneiss and mica-schist1 covered occasionally with unconformable red sandstone1 ,no4 #d4 7,new ,red or ,trias871 remarkable for its ornithichnites 7see p4 #cbg474 ,sometimes1 also1 this sandstone rests on the edges of the disturbed paleozoic rocks 7as seen in the section74 ,the region 7,b ,c71 sometimes called the ,atlantic ,slope1 corresponds nearly in average width with the low and flat plain 7,a1 ,b71 and is characterized by hills of moderate height1 contrasting strongly1 in their rounded shape and altitude1 with the long1 steep1 and lofty parallel ridges of the ,alleghany mountains4 ,the outcrop of the strata in these ridges1 like the two belts of hypogene and newer rocks 7,a ,b1 and ,b ,c71 above alluded to1 when laid down on a geological map1 exhibit long stripes of different colours1 running in a ,n4,e4 and ,s4,w4 direction1 in the same way as the lias1 chalk1 and other secondary formations in the middle and eastern half of ,england4 ,the narrow and parallel zones of the ,appalachians here mentioned1 consist of strata1 folded into a succession of convex and concave flexures1 subsequently laid open by denudation4 ,the component rocks are of great thickness1 all referable to the ,silurian1 ,devonian1 and ,carboniferous formations4 ,there is no principal or central axis1 as in the ,pyrenees and many other chains--no nucleus to which all the minor ridges conform2 but the chain consists of many nearly equal and parallel foldings1 having what is termed an anticlinal and synclinal arrangement 7see above1 p4 #dh474 ,this system of hills extends1 geologically considered1 from ,vermont to ,alabama1 being more than #ajjj miles long1 from #ej to #aej miles broad1 and varying in height from #bjjj to #fjjj feet4 ,sometimes the whole assemblage of ridges runs perfectly straight for a distance of more than #ej miles1 after which all of them wheel round together1 and take a new direction1 at an angle of #bj or #cj degrees to the first4 ,we are indebted to the state surveyors of ,virginia and ,pennsylvania1 ,prof4 ,w4 ,b4 ,rogers and his brother ,prof4 ,h4 ,d4 ,rogers1 for the important discovery of a clue to the general law of structure prevailing throughout this range of mountains1 which1 however simple it may appear when once made out and clearly explained1 might long have been overlooked2 amidst so great a mass of complicated details4 ,it appears that the bending and fracture of the beds is greatest on the south-eastern or ,atlantic side of the chain1 and the strata become less and less disturbed as we go westward1 until at length they regain their original or horizontal position4 ,by reference to the section 7fig4 #cgi471 it will be seen that on the eastern side1 or in the ridges and troughs nearest the ,atlantic1 south-eastern dips predominate1 in consequence of the beds having been folded back upon themselves1 as in i1 those on the north-western side of each arch having been inverted4 ,the next set of arches 7such as k7 are more open1 each having its western side steepest2 the next 7l7 opens out still more widely1 the next 7m7 still more1 and this continues until we arrive at the low and level part of the ,appalachian coal-field 7,d ,e74 ,in nature or in a true section1 the number of bendings or parallel folds is so much greater that they could not be expressed in a diagram without confusion4 ,it is also clear that large quantities of rock have been removed by aqueous action or denudation1 as will appear if we attempt to complete all the curves in the manner indicated by the dotted lines at i and k4 ,the movements which imparted so uniform an order of arrangement to this vast system of rocks must have been1 if not contemporaneous1 at least parts of one and the same series1 depending on some common cause4 ,their geological date is well defined1 at least within certain limits1 for they must have taken place after the deposition of the carboniferous strata 7,no4 #e471 and before the formation of the red sandstone 7,no4 #d474 ,the greatest disturbing and denuding forces have evidently been exerted on the south-eastern side of the chain2 and it is here that igneous or plutonic rocks are observed to have invaded the strata1 forming dykes1 some of which run for miles in lines parallel to the main direction of the ,appalachians1 or ,n4,n4,e4 and ,s4,s4,w4 ,the thickness of the carboniferous rocks in the region ,c is very great1 and diminishes rapidly as we proceed to the westward4 ,the surveys of ,pennsylvania and ,virginia show that the south-east was the quarter whence the coarser materials of these strata were derived1 so that the ancient land lay in that direction4 ,the conglomerate which forms the general base of the coal-measures is #aejj feet thick in the ,sharp ,mountain1 where ,i saw it 7at ,c7 near ,pottsville2 whereas it has only a thickness of #ejj feet1 about thirty miles to the north-west1 and dwindles gradually away when followed still farther in the same direction1 till its thickness is reduced to #cj feet4#cbi-;,a ,the limestones1 on the other hand1 of the coal-measures1 augment as we trace them westward4 ,similar observations have been made in regard to the ,silurian and ,devonian formations in ,new ,york2 the sandstones and all the mechanically-formed rocks thinning out as they go westward1 and the limestones thickening1 as it were1 at their expense4 ,it is1 therefore1 clear that the ancient land was to the east1 where the ,atlantic now is2 the deep sea1 with its banks of coral and shells to the west1 or where the hydrographical basin of the ,mississippi is now situated4 ,in that region1 near ,pottsville1 where the thickness of the coal-measures is greatest1 there are thirteen seams of anthracitic coal1 several of them more than #b yards thick4 ,some of the lowest of these alternate with beds of white grit and conglomerate of coarser grain than ,i ever saw elsewhere1 associated with pure coal4 ,the pebbles of quartz are often of the size of a hen's egg4 ,on following these pudding-stones and grits for several miles from ,pottsville1 by ,tamaqua1 to the ,lehigh ,summit ,mine1 in company with ,mr4 ,h4 ,d4 ,rogers1 in #ahda1 he pointed out to me that the coarse-grained strata and their accompanying shales gradually thin out1 until seven seams of coal1 at first widely separated1 are brought nearer and nearer together1 until they successively unite2 so that at last they form one mass1 between #dj and #ej feet thick4 ,i saw this enormous bed of anthracitic coal quarried in the open air at ,mauch ,chunk 7or the ,bear ,mountain71 the overlying sandstone1 #dj feet thick1 having been removed bodily from the top of the hill1 which1 to use the miner's expression1 had been scalped4 ,the accumulation of vegetable matter now constituting this vast bed of anthracite1 may perhaps1 before it was condensed by pressure and the discharge of its hydrogen1 oxygen1 and other volatile ingredients1 have been between #bjj and #cjj feet thick4 ,the origin of such a vast thickness of vegetable remains1 so unmixed with earthy ingredients1 can1 ,i think1 be accounted for in no other way1 than by the growth1 during thousands of years1 of trees and ferns1 in the manner of peat1--a theory which the presence of the ,stigmaria in situ under each of the seven layers of anthracite1 fully bears out4 ,the rival hypothesis1 of the drifting of plants into a sea or estuary1 leaves the absence of sediment1 or1 in this case1 of sand and pebbles1 wholly unexplained4 ,illustration3 ,fig4 #chj4 ,cross section4 ,illustration3 ,fig4 #cha4 ,cross section4 ,but the student will naturally ask1 what can have caused so many seams of coal1 after they had been persistent for miles1 to come together and blend into one single seam1 and that one equal in the aggregate to the thickness of the several separate seams8 ,often had the same question been put by ,english miners before a satisfactory answer was given to it by the late ,mr4 ,bowman4 ,the following is his solution of the problem4 ,let a a'1 fig4 #chj41 be a mass of vegetable matter1 capable1 when condensed1 of forming a #c-;foot seam of coal4 ,it rests on the underclay b b'1 filled with roots of trees in situ1 and it supports a growing forest 7,c ,d74 ,suppose that part of the same forest ,d ,e had become submerged by the ground sinking down #be feet1 so that the trees have been partly thrown down and partly remain erect in water1 slowly decaying1 their stumps and the lower parts of their trunks being enveloped in layers of sand and mud1 which are gradually filling up the lake ,d ,f4 ,when this lake or lagoon has at length been entirely silted up and converted into land1 say1 in the course of a century1 the forest ,c ,d will extend once more continuously over the whole area ,c ,f1 as in fig4 #cha41 and another mass of vegetable matter 7g g'71 forming #c feet more of coal1 may accumulate from ,c to ,f4 ,we then find in the region ,f1 two seams of coal 7a' and g'7 each #c feet thick1 and separated by #be feet of sandstone and shale1 with erect trees based upon the lower coal1 while1 between ,d and ,c1 we find these two seams united into a #b-yard coal4 ,it may be objected that the uninterrupted growth of plants during the interval of a century will have caused the vegetable matter in the region ,c ,d to be thicker than the two distinct seams a' and g' at ,f2 and no doubt there would actually be a slight excess representing one generation of trees with the remains of other plants1 forming half an inch or an inch of coal2 but this would not prevent the miner from affirming that the seam a g1 throughout the area ,c ,d1 was equal to the two seams a' and g' at ,f4 ,the reader has seen1 by reference to the section 7fig4 #cgi4 p4 #cbg471 that the strata of the ,appalachian coal-field assume an horizontal position west of the mountains4 ,in that less elevated country1 the coal-measures are intersected by three great navigable rivers1 and are capable of supplying for ages1 to the inhabitants of a densely peopled region1 an inexhaustible supply of fuel4 ,these rivers are the ,monongahela1 the ,alleghany1 and the ,ohio1 all of which lay open on their banks the level seams of coal4 ,looking down the first of these at ,brownsville1 we have a fine view of the main seam of bituminous coal #aj feet thick1 commonly called the ,pittsburg seam1 breaking out in the steep cliff at the water's edge2 and ,i made the accompanying sketch of its appearance from the bridge over the river 7see fig4 #chb474 ,here the coal1 #aj feet thick1 is covered by carbonaceous shale 7b71 and this again by micaceous sandstone 7c74 ,horizontal galleries may be driven everywhere at very slight expense1 and so worked as to drain themselves1 while the cars1 laden with coal and attached to each other1 glide down on a railway1 so as to deliver their burden into barges moored to the river's bank4 ,the same seam is seen at a distance1 on the right bank 7at a71 and may be followed the whole way to ,pittsburg1 fifty miles distant4 ,as it is nearly horizontal1 while the river descends it crops out at a continually increasing1 but never at an inconvenient1 height above the ,monongahela4 ,below the great bed of coal at ,brownsville is a fire-clay #ah inches thick1 and below this1 several beds of limestone1 below which again are other coal seams4 ,i have also shown in my sketch another layer of workable coal 7at d d71 which breaks out on the slope of the hills at a greater height4 ,here almost every proprietor can open a coal-pit on his own land1 and the stratification being very regular1 he may calculate with precision the depth at which coal may be won4 ,the ,appalachian coal-field1 of which these strata form a part 7from ,c to ,e1 section1 fig4 #cgi41 p4 #cbg471 is remarkable for its vast area2 for1 according to ,professor ,h4 ,d4 ,rogers1 it stretches continuously from ,n4,e4 to ,s4,w41 for a distance of #gbj miles1 its greatest width being about #ahj miles4 ,on a moderate estimate1 its superficial area amounts to #fc1jjj square miles4 ,illustration3 ,fig4 #chb4 ,view of the great ,coal ,seam on the ,monongahela at ,brownsville1 ,pennsylvania1 ,u4 ,s4 a4 ,ten-foot seam of coal4 b4 ,black bituminous or carbonaceous shale1 #aj feet thick4 c4 ,micaceous sandstone4 d d4 ,upper seam of coal1 #f feet thick4 ,this coal formation1 before its original limits were reduced by denudation1 must have measured #ijj miles in length1 and in some places more than #bjj miles in breadth4 ,by again referring to the section 7fig4 #cgi41 p4 #cbg471 it will be seen that the strata of coal are horizontal to the westward of the mountains in the region ,d ,e1 and become more and more inclined and folded as we proceed eastward4 ,now it is invariably found1 as ,professor ,h4 ,d4 ,rogers has shown by chemical analysis1 that the coal is most bituminous towards its western limit1 where it remains level and unbroken1 and that it becomes progressively debituminized as we travel south-eastward towards the more bent and distorted rocks4 ,thus1 on the ,ohio1 the proportion of hydrogen1 oxygen1 and other volatile matters1 ranges from forty to fifty per cent4 ,eastward of this line1 on the ,monongahela1 it still approaches forty per cent41 where the strata begin to experience some gentle flexures4 ,on entering the ,alleghany ,mountains1 where the distinct anticlinal axes begin to show themselves1 but before the dislocations are considerable1 the volatile matter is generally in the proportion of eighteen or twenty per cent4 ,at length1 when we arrive at some insulated coal-fields 7#e'1 fig4 #cgi47 associated with the boldest flexures of the ,appalachian chain1 where the strata have been actually turned over1 as near ,pottsville1 we find the coal to contain only from six to twelve per cent4 of bitumen1 thus becoming a genuine anthracite4#ccc-;,a ,it appears from the researches of ,liebig and other eminent chemists1 that when wood and vegetable matter are buried in the earth1 exposed to moisture1 and partially or entirely excluded from the air1 they decompose slowly and evolve carbonic acid gas1 thus parting with a portion of their original oxygen4 ,by this means1 they become gradually converted into lignite or wood-coal1 which contains a larger proportion of hydrogen than wood does4 ,a continuance of decomposition changes this lignite into common or bituminous coal1 chiefly by the discharge of carburetted hydrogen1 or the gas by which we illuminate our streets and houses4 ,according to ,bischoff1 the inflammable gases which are always escaping from mineral coal1 and are so often the cause of fatal accidents in mines1 always contain carbonic acid1 carburetted hydrogen1 nitrogen1 and olefiant gas4 ,the disengagement of all these gradually transforms ordinary or bituminous coal into anthracite1 to which the various names of splint coal1 glance coal1 culm1 and many others1 have been given4 ,we have seen that1 in the ,appalachian coal-field1 there is an intimate connection between the extent to which the coal has parted with its gaseous contents1 and the amount of disturbance which the strata have undergone4 ,the coincidence of these phenomena may be attributed partly to the greater facility afforded for the escape of volatile matter1 where the fracturing of the rocks had produced an infinite number of cracks and crevices1 and also to the heat of the gases and water penetrating these cracks1 when the great movements took place1 which have rent and folded the ,appalachian strata4 ,it is well known that1 at the present period1 thermal waters and hot vapours burst out from the earth during earthquakes1 and these would not fail to promote the disengagement of volatile matter from the carboniferous rocks4 ,continuity of seams of coal4--,as single seams of coal are continuous over very wide areas1 it has been asked1 how forests could have prevailed uninterruptedly over such wide spaces1 without being oftener flooded by turbid rivers1 or1 when submerged1 denuded by marine currents4 ,it appears1 from the description of the ,cape ,breton coal-field1 by ,mr4 ,richard ,brown1 that false stratification is common in the beds of sand1 and some partial denudation of these1 at least1 must often have taken place during the accumulation of the carboniferous series4 ,in the ,forest of ,dean1 ancient river-channels are found1 which pass through beds of coal1 and in which rounded pebbles of coal occur4 ,they are of older date than the overlying and undisturbed coal-measures4 ,the late ,mr4 ,buddle1 who described them to me1 told me he had seen similar phenomena in the ,newcastle coal-field4 ,nevertheless1 instances of these channels are much more rare than we might have anticipated1 especially when we remember how often the roots of trees 7,stigmariae7 have been torn up1 and drifted in broken fragments into the grits and sandstones4 ,the prevalence of a downward movement is1 no doubt1 the principal cause which has saved so many extensive seams of coal from destruction by fluviatile action4 ,the purity of the coal1 or its non-intermixture with earthy matter1 presents another theoretical difficulty to many geologists1 who are inclined to believe that the trees and smaller plants of the carboniferous period grew in extensive swamps1 rather than on land not liable to be inundated4 ,it appears1 however1 that in the alluvial plain and delta of the ,mississippi1 extensive cypress swamps1 as they are called1 densely covered with various trees1 occur1 into which no matter held in mechanical suspension is ever introduced during the greatest inundations1 inasmuch as they are all surrounded by a dense marginal belt of reeds1 canes1 and brushwood4 ,through this thick barrier the river-water must pass1 so that it is invariably well filtered before it can reach the interior of the forest-covered area1 within which1 vegetable matter is continually accumulating from the decay of trees and semi-aquatic plants4 ,in proof of this1 ,i may observe1 that whenever any part of a swamp is dried up1 during an unusually hot season1 and the wood set on fire1 pits are burnt into the ground many feet deep1 or as far down as the fire can descend without meeting with water1 and it is then found that scarcely any residuum or earthy matter is left4#ccd-;,a ,at the bottom of these cypress swamps of the ,mississippi1 a bed of clay is found1 with roots of the tall cypress 7,taxodium distichum71 just as the underclays of the coal are filled with ,stigmaria4 ,climate of ,coal ,period4--,so long as the botanist taught that a tropical climate was implied by the carboniferous flora1 geologists might well be at a loss to reconcile the preservation of so much vegetable matter with a high temperature2 for heat hastens the decomposition of fallen leaves and trunks of trees1 whether in the atmosphere or in water4#cce-;,a ,it is well known that peat1 so abundant in the bogs of high latitudes1 ceases to grow in the swamps of warmer regions4 ,it seems1 however1 to have become a more and more received opinion1 that the coal-plants do not1 on the whole1 indicate a climate resembling that now enjoyed in the equatorial zone4 ,tree-ferns range as far south as the southern part of ,new ,zealand1 and ,araucarian pines occur in ,norfolk ,island4 ,a great predominance of ferns and lycopodiums indicates warmth1 moisture1 equability of temperature1 and freedom from frost1 rather than intense heat2 and we know too little of the sigillariae1 calamites1 asterophyllites1 and other peculiar forms of the carboniferous period1 to be able to speculate with confidence on the kind of climate they may have required4 ,no doubt1 we are entitled to presume1 from the corals and cephalopoda of the mountain limestone1 that a warm temperature characterized the northern seas in the carboniferous era2 but the absence of cold may have given rise 7as at present in the seas of the ,bermudas1 under the influence of the gulf stream7 to a very wide geographical range of stone-building corals and shell-bearing cuttle-fish1 without its being necessary to call in the aid of tropical heat4#cce-;,b ,,carboniferous ,,reptiles4 ,where we have evidence in a single coal-field1 as in that of ,nova ,scotia1 or ,south ,wales1 of fifty or even a hundred ancient forests buried one above the other1 with the roots of trees still in their original position1 and with some of the trunks still remaining erect1 we are apt to wonder that until the year #ahdd no remains of contemporaneous air-breathing creatures1 except a few insects1 had been discovered4 ,no vertebrated animals more highly organized than fish1 no mammalia or birds1 no saurians1 frogs1 tortoises1 or snakes1 were yet known in rocks of such high antiquity4 ,in the coal-field of ,coalbrook ,dale mention had been made of two species of beetles of the family ,curculionidae1 and of a neuropterous insect resembling the genus ,corydalis1 with another related to the ,phasmidae4#cce-;,c ,in other coal-measures in ,europe we find notice of a scorpion and of a moth allied to ,tinea1 also of one air-breathing crustacean1 or land-crab4 ,yet ,agassiz had already described in his great work on fossil fishes more than one hundred and fifty species of ichthyolites from the coal strata1 ninety-four belonging to the families of shark and ray1 and fifty-eight to the class of ganoids4 ,some of these fish are very remote in their organization from any now living1 especially those of the family called ,sauroid by ,agassiz2 as ,megalichthys1 ,holoptychius1 and others1 which are often of great size1 and all predaceous4 ,their osteology1 says ,m4 ,agassiz1 reminds us in many respects of the skeletons of saurian reptiles1 both by the close sutures of the bones of the skull1 their large conical teeth striated longitudinally 7see fig4 #chc471 the articulations of the spinous processes with the vertebrae1 and other characters4 ,yet they do not form a family intermediate between fish and reptiles1 but are true fish1 though doubtless more highly organized than any living fish4#ccf-;,a ,illustration3 ,fig4 #chc4 ,holoptychius ,hibberti1 ,ag4 ,fifeshire coal-field2 natural size4 ,the annexed figure represents a large tooth of the ,megalichthys1 found by ,mr4 ,horner in the ,cannel coal of ,fifeshire4 ,it probably inhabited an estuary1 like many of its contemporaries1 and frequented both rivers and the sea4 ,illustration3 ,fig4 #chd4 ,archegosaurus minor1 ,goldfuss4 ,fossil reptile from the coal-measures1 ,saarbrueck4 ,at length1 in #ahdd1 the first skeleton of a true reptile was announced from the coal of ,muenster-,appel in ,rhenish ,bavaria1 by ,h4 von ,meyer1 under the name of ,apateon pedestris1 the animal being supposed to be nearly related to the salamanders4 ,three years later1 in #ahdg1 ,prof4 von ,dechen found in the coal-field of ,saarbrueck1 at the village of ,lebach1 between ,strasburg and ,treves1 the skeletons of no less than three distinct species of air-breathing reptiles1 which were described by the late ,prof4 ,goldfuss under the generic name of ,archegosaurus4 ,the ichthyolites and plants found in the same strata1 left no doubt that these remains belonged to the true coal period4 ,the skulls1 teeth1 and the greater portions of the skeleton1 nay1 even a large part of the skin1 of two of these reptiles have been faithfully preserved in the centre of spheroidal concretions of clay-iron-stone4 ,the largest of these lizards1 ,archegosaurus ,decheni1 must have been #c feet #f inches long4 ,the annexed drawing represents the smallest of the three of the natural size4 ,they were considered by ,goldfuss as saurians1 but by ,herman von ,meyer as most nearly allied to the ,labyrinthodon1 and therefore connected with the batrachians1 as well as the lizards4 ,the remains of the extremities leave no doubt that they were quadrupeds1 provided1 says ,von ,meyer1 with hands and feet terminating in distinct toes2 but these limbs were weak1 serving only for swimming or creeping4 ,the same anatomist has pointed out certain points of analogy between their bones and those of the ,proteus anguinus2 and ,mr4 ,owen has observed to me that they make an approach to the ,proteus in the shortness of their ribs4 ,two of these ancient reptiles retain a large part of the outer skin1 which consisted of long1 narrow1 wedge-shaped1 tile-like1 and horny scales1 arranged in rows 7see fig4 #che474 ,illustration3 ,fig4 #che4 ,imbricated covering of skin of ,archegosaurus medius1 ,goldf42 magnified4#ccg-;,a ,cheirotherian footprints in coal measures1 ,united ,states4--,in #ahdd1 the very year when the ,apateon or ,salamander of the coal was first met with in the country between the ,moselle and the ,rhine1 ,dr4 ,king published an account of the footprints of a large reptile discovered by him in ,north ,america4 ,these occur in the coal strata of ,greensburg1 in ,westmoreland ,county1 ,pennsylvania2 and ,i had an opportunity of examining them in #ahdf4 ,i was at once convinced of their genuineness1 and declared my conviction on that point1 on which doubts had been entertained both in ,europe and the ,united ,states4 ,the footmarks were first observed standing out in relief from the lower surface of slabs of sandstone1 resting on thin layers of fine unctuous clay4 ,i brought away one of these masses1 which is represented in the accompanying drawing 7fig4 #chf474 ,it displays1 together with footprints1 the casts of cracks 7a1 a'7 of various sizes4 ,the origin of such cracks in clay1 and casts of the same1 has before been explained1 and referred to the drying and shrinking of mud1 and the subsequent pouring of sand into open crevices4 ,it will be seen that some of the cracks1 as at b1 c1 traverse the footprints1 and produce distortion in them1 as might have been expected1 for the mud must have been soft when the animal walked over it and left the impressions2 whereas1 when it afterwards dried up and shrank1 it would be too hard to receive such indentations4 ,no less than twenty-three footsteps were observed by ,dr4 ,king in the same quarry before it was abandoned1 the greater part of them so arranged 7see fig4 #chg47 on the surface of one stratum as to imply that they were made successively by the same animal4 ,everywhere there was a double row of tracks1 and in each row they occur in pairs1 each pair consisting of a hind and fore foot1 and each being at nearly equal distances from the next pair4 ,in each parallel row the toes turn the one set to the right1 the other to the left4 ,in the ,european ,cheirotherium1 before mentioned 7p4 #bij471 both the hind and fore feet have each five toes1 and the size of the hind foot is about five times as large as the fore foot4 ,in the ,american fossil the posterior footprint is not even twice as large as the anterior1 and the number of toes is unequal1 being five in the hinder and four in the anterior foot4 ,in this1 as in the ,european ,cheirotherium1 one toe stands out like a thumb1 and these thumb-like toes turn the one set to the right1 and the other to the left4 ,the ,american ,cheirotherium was evidently a broader animal1 and belonged to a distinct genus from that of the triassic age in ,europe4#cch-;,a ,illustration3 ,fig4 #chf4 ,scale one-sixth the original4 ,slab of sandstone from the coal-measures of ,pennsylvania1 with footprints of air-breathing reptile and casts of cracks4 ,we may assume that the reptile which left these prints on the ancient sands of the coal-measures was an air-breather1 because its weight would not have been sufficient under water to have made impressions so deep and distinct4 ,the same conclusion is also borne out by the casts of the cracks above described1 for they show that the clay had been exposed to the air and sun1 so as to have dried and shrunk4 ,illustration3 ,fig4 #chg4 ,series of reptilian footprints in the coal-strata of ,westmoreland ,county1 ,pennsylvania4 a4 ,mark of nail8 ,the geological position of the sandstone of ,greensburg is perfectly clear1 being situated in the midst of the ,appalachian coal-field1 having the main bed of coal1 called the ,pittsburg seam1 above mentioned 7p4 #cca471 #c yards thick1 #ajj feet above it1 and worked in the neighbourhood1 with several other seams of coal at lower levels4 ,the impressions of ,lepidodendron1 ,sigillaria1 ,stigmaria1 and other characteristic carboniferous plants1 are found both above and below the level of the reptilian footsteps4 ,analogous footprints of a large reptile of still older date have since been found 7#ahdi71 by ,mr4 ,isaac ,lea1 in the lowest beds of the coal formation at ,pottsville1 near ,philadelphia1 so that we may now be said to have the footmarks of two reptilians of the coal period1 and the skeletons of four4#cdj-;,a ,,carboniferous ,,or ,,mountain ,,limestone4 ,we have already seen that this rock lies sometimes entirely beneath the coal-measures1 while1 in other districts1 it alternates with the shales and sandstone of the coal4 ,in both cases it is destitute of land plants1 and usually charged with corals1 which are often of large size2 and several species belong to the lamelliferous class of ,lamarck1 which enter largely into the structure of coral reefs now growing4 ,there are also a great number of ,crinoidea 7see fig4 #chh471 and a few ,echinoderms1 associated with the zoophytes above mentioned4 ,the ,brachiopoda constitute a large proportion of the ,mollusca1 many species being referable to two extinct genera1 ,spirifer 7or ,spirifera7 7fig4 #chi471 and ,productus 7,leptaena7 7fig4 #cij474 ,illustration3 ,fig4 #chh4 ,cyathocrinites planus1 ,miller4 ,mountain limestone4 ,illustration3 ,fig4 #chi4 ,spirifer glaber1 ,sow4 ,mountain limestone4 ,illustration3 ,fig4 #cij4 ,productus ,martini1 ,sow4 7,p4 semireticulatus1 ,flem47 ,mountain limestone4 ,among the spiral univalve shells the extinct genus ,euomphalus 7see fig4 #cia47 is one of the commonest fossils of the ,mountain limestone4 ,in the interior it is often divided into chambers 7see fig4 #cia4 d72 the septa or partitions not being perforated1 as in foraminiferous shells1 or in those having siphuncles1 like the ,nautilus4 ,the animal appears1 like the recent ,bulimus decollatus1 to have retreated at different periods of its growth1 from the internal cavity previously formed1 and to have closed all communication with it by a septum4 ,the number of chambers is irregular1 and they are generally wanting in the innermost whorl4 ,illustration3 ,fig4 #cia4 ,euomphalus pentagulatus1 ,min4 ,con4 ,mountain limestone4 a4 ,upper side2 b4 lower1 or umbilical side2 c4 view showing mouth which is less pentagonal in older individuals2 d4 view of polished section1 showing internal chambers4 ,illustration3 ,fig4 #cib4 ,portion of ,orthoceras laterale1 ,phillips4 ,mountain limestone4 ,there are also many univalve and bivalve shells of existing genera in the ,mountain limestone1 such as ,turritella1 ,buccinum1 ,patella1 ,isocardia1 ,nucula1 and ,pecten4#cda-;,a ,but the ,cephalopoda depart1 in general1 more widely from living forms1 some being generically distinct from all those found in strata newer than the coal4 ,in this number may be mentioned ,orthoceras1 a siphuncled and chambered shell1 like a ,nautilus uncoiled and straightened4 ,some species of this genus are several feet long 7fig4 #cib474 ,the ,goniatite is another genus1 nearly allied to the ,ammonite1 from which it differs in having the lobes of the septa free from lateral denticulations1 or crenatures2 so that the outline of these is continuous and uninterrupted 7see a1 fig4 #cic474 ,their siphon is small1 and in the form of the striae of growth they resemble ,nautili4 ,another extinct generic form of ,cephalopod1 abounding in the ,mountain limestone1 and not found in strata of later date1 is the ,bellerophon 7fig4 #cid471 of which the shell1 like the living ,argonaut1 was without chambers4 ,illustration3 ,fig4 #cic4 ,goniatites evolutus1 ,phillips4#cdb-;,a ,mountain limestone4 ,illustration3 ,fig4 #cid4 ,bellerophon costatus1 ,sow4#cdb-;,b ,mountain limestone4 ,,footnotes3 #cbi-;,a ,h4 ,d4 ,rogers1 ,trans4 ,assoc4 ,amer4 ,geol41 #ahdj-db1 p4 #ddj4 #ccc-;,a ,trans4 of ,ass4 of ,amer4 ,geol41 p4 #dgj4 #ccd-;,a ,lyell's ,second ,visit to the ,u4 ,s41 vol4 ii4 p4 #bde4 ,american ,journ4 of ,sci41 #b;d series1 vol4 v4 p4 #ag4 #cce-;,a ,principles of ,geol41 p4 #fif4 #cce-;,b ,for changes in climate1 see ,principles of ,geol41 chaps4 vii4 and viii4 #cce-;,c ,geol4 ,trans41 #b;d series1 vol4 vi4 p4 #ccj4 #ccf-;,a ,agassiz1 ,poiss4 ,foss41 lib4 #d4 p4 #fb4 and liv4 #e4 p4 #hh4 #ccg-;,a ,goldfuss1 ,neue ,jenaische ,lit4 ,zeit41 #ahdh2 and ,von ,meyer1 ,quart4 ,geol4 ,journ41 vol4 iv4 p4 #ea41 memoirs4 #cch-;,a ,see ,lyell's ,second ,visit1 c41 vol4 ii4 p4 #cje4 #cdj-;,a ,these impressions1 found by ,mr4 ,lea1 were imagined to be in a rock as ancient as the old red sandstone2 but1 according to ,mr4 ,h4 ,d4 ,rogers1 they are in the lowest part of the coal formation4 #cda-;,a ,phillips1 ,geol4 of ,yorksh41 vol4 ii4 p4 #bjh4 #cdb-;,a ,phillips1 ,geol4 of ,yorksh41 pl4 #bj4 fig4 #fe4 #cdb-;,b ,ibid41 pl4 #ag4 fig4 #ae4 ,,chapter ,,xxvi4 ,,old ,,red ,,sandstone1 ,,or ,,devonian ,,group4 ,old ,red ,sandstone of ,scotland1 and borders of ,wales--,fossils usually rare--,old ,red in ,forfarshire--,ichthyolites of ,caithness--,distinct lithological type of ,old ,red in ,devon and ,cornwall--,term ,devonian--,organic remains of intermediate character between those of the ,carboniferous and ,silurian systems--,corals and shells--,devonian strata of ,westphalia1 the ,eifel1 ,russia1 and the ,united ,states--,coral reef at ,falls of the ,ohio--,devonian flora4 ,it was stated in ,chap4 ,,xxii4 that the ,carboniferous formation is surmounted by one called the ,new ,red1 and underlaid by another called the ,old ,red ,sandstone4#cdb-;,c ,the ,british strata of the last mentioned series were first recognized in ,herefordshire and ,scotland as of great thickness1 and immediately subjacent to the coal2 but they were in general so barren of organic remains1 that it was difficult to find paleontological characters of sufficient importance to distinguish them as an independent group4 ,in ,scotland1 and on the borders of ,wales1 the ,old ,red consists chiefly of red sandstone1 conglomerate1 and shale1 with few fossils2 but limestones of the same age1 peculiarly rich in organic remains1 were at length found in ,devonshire4 ,i shall first advert to the characters of the group as developed in ,herefordshire1 ,worcestershire1 ,shropshire1 and ,south ,wales4 ,its thickness has been estimated at #hjjj feet1 and it has been subdivided into-- #ast4 ,a quartzose conglomerate passing downwards into chocolate-red and green sandstone and marl4 #b;d4 ,cornstone and marl--red and green argillaceous spotted marls1 with irregular courses of impure concretionary limestone1 provincially called ,cornstone4 ,here1 as usual1 fossils are extremely rare in the clays and sandstones in which the red oxide of iron prevails2 but remains of fishes of the genera ,cephalaspis and ,onchus have been discovered in the ,cornstone4 ,the whole of the northern part of ,scotland1 from ,cape ,wrath to the southern flank of the ,grampians1 has been well described by ,mr4 ,miller as consisting of a nucleus of granite1 gneiss1 and other hypogene rocks1 which seem as if set in a sandstone frame4#cdc-;,a ,the beds of the ,old ,red ,sandstone constituting this frame1 may once perhaps have extended continuously over the entire ,grampians before the upheaval of that mountain range2 for one band of the sandstone follows the course of the ,moray ,frith far into the interior of the great ,caledonian valley2 and detached hills and island-like patches occur in several parts of the interior1 capping some of the higher summits in ,sutherlandshire1 and appearing in ,morayshire like oases among the granite rocks of ,strathspey4 ,on the western coast of ,ross-shire1 the ,old ,red forms those three immense insulated hills before described 7p4 #fg471 where beds of horizontal sandstone1 #cjjj feet high1 rest unconformably on a base of gneiss1 attesting the vast denudation which has taken place4 ,but in order to observe the uppermost part of the ,old ,red1 we must travel south of the ,grampians1 and examine its junction with the bottom of the ,carboniferous series in ,fifeshire4 ,this upper member may be seen in ,dura ,den1 south of ,cupar1 to consist of a belt of yellow sandstone1 in which ,dr4 ,fleming first discovered scales of ,holoptychius1 and in which species of fish of the genera ,pterichthys1 ,pamphractus1 and others1 have been met with4 7,for genus ,pterichthys1 see fig4 #djj4 p4 #cde47 ,the beds next below the yellow sandstone are well seen in the large zone of ,old ,red which skirts the southern flank of the ,grampians from ,stonehaven to the ,frith of ,clyde4 ,it there forms1 together with trap1 the ,sidlaw ,hills and the strata of the valley of ,strathmore4 ,a section of this region has been already given 7p4 #dh471 extending from the foot of the ,grampians in ,forfarshire to the sea at ,arbroath1 a distance of about #bj miles1 where the entire series of strata is several thousand feet thick1 and may be divided into three principal masses3 #ast1 and uppermost1 red and mottled marls1 cornstone1 and sandstone 7,nos4 #a4 and #b4 of the section72 #b;d1 ,conglomerate1 often of vast thickness 7,no4 #c4 ibid472 #c;d1 ,roofing and paving stone1 highly micaceous1 and containing a slight admixture of carbonate of lime 7,no4 #d4 ibid474 ,in the first of these divisions1 which may be considered as succeeding the yellow sandstone of ,fifeshire before mentioned1 a gigantic species of fish of the genus ,holoptychius has been found at ,clashbinnie near ,perth4 ,some scales 7see fig4 #cie47 have been seen which measured #c inches in length by #b-a_/b in breadth4 ,at the top of the next division1 or immediately under the conglomerate 7,no4 #c4 p4 #dh471 there have been found in ,forfarshire some remarkable crustaceans1 with several fish of the genus named by ,agassiz ,cephalaspis1 or buckler-headed1 from the extraordinary shield which covers the head 7see fig4 #cif471 and which has often been mistaken for that of a trilobite1 of the division ,asaphus4 ,illustration3 ,fig4 #cie4 ,scale of ,holoptychius nobilissimus1 ,agas4 ,clashbinnie4 ,nat4 size4 ,species of the same genus are considered in ,england as characteristic of the second or ,cornstone division 7p4 #cdc474 ,illustration3 ,fig4 #cif4 ,cephalaspis ,lyellii1 ,agass4 ,length #f-c_/d inches4 ,from a specimen in my collection found at ,glammiss1 in ,forfarshire4 ,see other figures1 ,agassiz1 vol4 ii4 tab4 #a4 a4 and #a4 b4 a4 ,one of the peculiar scales with which the head is covered when perfect4 ,these scales are generally removed1 as in the specimen above figured4 b1 c4 ,scales from different parts of the body and tail4 ,illustration3 ,fig4 #cig4 ,eggs of gasteropodous mollusk8 ,lower beds of ,old ,red1 ,ley's ,mill1 ,forfarshire4 ,illustration3 ,fig4 #cih4 ,fucoids and eggs of gasteropodous mollusk8 ,lower ,old ,red1 ,fife4 ,in the same grey paving-stones and coarse roofing-slates1 in which the ,cephalaspis occurs1 in ,forfarshire and ,kincardineshire1 the remains of marine plants or fucoids abound4 ,they are frequently accompanied by groups of hexagonal1 or nearly hexagonal markings1 which consist of small flattened carbonaceous bodies1 placed in a slight depression of the sandstone or shale4 7,see figs4 #cig and #cih47 ,they much resemble in form the spawn of the recent ,natica 7see fig4 #cii471 in which the eggs are arranged in a thin layer of sand1 and seem to have acquired a polygonal form by pressing against each other4 ,the substance of the egg1 if fossilized1 might give rise to small pellicles of carbonaceous matter4 ,illustration3 ,fig4 #cii4 ,fragment of spawn of ,british species of ,natica4 ,these fossils ,i have met with1 both to the north of ,strathmore1 in the vertical shale beneath the conglomerate1 and in the same beds in the ,sidlaw hills1 at all the points where fig4 #d4 is introduced in the section1 p4 #dh4 ,illustration3 ,fig4 #djj4 ,pterichthys1 ,agassiz2 upper side1 showing mouth2 as restored by ,h4 ,miller4#cde-;,a ,beds of red shale and red sandstone1 sometimes associated with pudding-stone 7older than ,no4 #c41 fig4 #fb4 p4 #dh471 and destitute of organic remains1 separate1 in the region of ,strathmore1 the above-described fossiliferous strata from the older crystalline rocks of the ,grampians4 ,but1 in the north of ,scotland1 we find1 at the base of the ,old ,red1 other grey slaty sandstones1 in the counties of ,banff1 ,nairn1 ,moray1 ,cromarty1 ,caithness1 and in ,orkney1 rich in ichthyolites of peculiar forms1 belonging to the genera ,pterichthys 7fig4 #djj471 ,coccosteus1 ,diplopterus1 ,dipterus1 ,cheiracanthus1 and others of ,agassiz4 ,five species of ,pterichthys have been found in this lowest division of the ,old ,red4 ,the wing-like appendages1 whence the genus is named1 were first supposed by ,mr4 ,miller to be paddles1 like those of the turtle2 but ,agassiz regards them as weapons of defence1 like the occipital spines of the ,river ,bull-head 7,cottus gobio1 ,linn472 and considers the tail to have been the only organ of motion4 ,the genera ,dipterus and ,diplopterus are so named1 because their two dorsal fins are so placed as to front the anal and ventral fins1 so as to appear like two pairs of wings4 ,they have bony enamelled scales4 ,south ,devon and ,cornwall4--,a great step was made in the classification of the slaty and calciferous strata of ,south ,devon and ,cornwall in #ahcg1 when a large portion of the beds1 previously referred to the transition or most ancient fossiliferous series1 were found to belong in reality to the period of the ,old ,red ,sandstone4 ,for this reform we are indebted to the labours of ,professor ,sedgwick and ,sir ,r4 ,murchison1 assisted by a suggestion of ,mr4 ,lonsdale1 who1 in #ahcg1 after examining the ,south ,devonshire fossils1 perceived that some of them agreed with those of the ,carboniferous group1 others with those of the ,silurian1 while many could not be assigned to either system1 the whole taken together exhibiting a peculiar and intermediate character4 ,but these paleontological observations alone would not have enabled us to assign1 with accuracy1 the true place in the geological series of these slate-rocks and limestones of ,south ,devon1 had not ,messrs4 ,sedgwick and ,murchison1 in #ahcf and #ahcg1 discovered that the culmiferous or anthracitic shales of ,north ,devon belonged to the ,coal1 and not1 as preceding observers had imagined1 to the transition period4 ,as the strata of ,south ,devon here alluded to are far richer in organic remains than the red sandstones of contemporaneous date in ,herefordshire and ,scotland1 the new name of the ,devonian system was proposed as a substitute for that of ,old ,red ,sandstone4 ,the rocks of this group in ,south ,devon consist1 in great part1 of green chloritic slates1 alternating with hard quartzose slates and sandstones4 ,here and there calcareous slates are interstratified with blue crystalline limestone1 and in some divisions conglomerates1 passing into red sandstone4 ,the link supplied by the whole assemblage of imbedded fossils1 connecting as it does the paleontology of the ,silurian and ,carboniferous groups1 is one of the highest interest1 and equally striking1 whether we regard the genera of corals or of shells4 ,the species are almost all distinct4 ,among the more abundant corals1 we find the genera ,favosites and ,cyathophyllum1 common on the one hand to the ,mountain limestone1 and on the other to the ,silurian system4 ,some few even of the species are common to the ,devonian and ,silurian groups1 as1 for example1 ,favosites polymorpha 7fig4 #dja471 very abundant in ,south ,devon4 ,illustration3 ,fig4 #dja4 ,favosites polymorpha1 ,goldf41 ,s4 ,devon4 ,from a polished specimen4 a4 portion of the same1 magnified to show the pores4 ,the ,cyathophyllum caespitosum 7fig4 #djb47 and ,porites pyriformis 7fig4 #dbd4 p4 #cef47 are more peculiarly characteristic of the ,devonian rocks4 ,in regard to the shells1 all the brachiopodous genera1 such as ,terebratula1 ,orthis1 ,spirifer1 ,atrypa1 and ,productus1 which are found in the ,mountain limestone1 occur1 together with those of the ,silurian system1 except the ,pentamerus4 ,some forms1 however1 seem exclusively ,devonian1 as for example1 ,calceola sandalina 7fig4 #djc47 and ,strygocephalus ,burtini 7fig4 #djd471 which have been met with both in the ,eifel1 in ,germany1 and in ,devonshire1 in the very lowest ,devonian beds4 ,illustration3 ,fig4 #djb4 ,cyathophyllum4 a4 ,cyathophyllum caespitosum1 ,goldf41 ,plymouth4 b4 a terminal star4 c4 vertical section exhibiting transverse plates1 and part of another branch4 ,among the peculiar lamellibranchiate bivalves1 also common to ,devonshire and the ,eifel1 we find ,megalodon cucullatus 7fig4 #dje474 ,several spiral univalves are abundant1 among which are many species of ,pleurotomaria and ,euomphalus4 ,among the ,cephalopoda we find ,bellerophon and ,orthoceras1 as in the ,silurian and ,carboniferous groups1 and ,goniatite and ,cyrtoceras1 as in the ,carboniferous4 ,in some of the upper ,devonian beds1 a shell1 resembling a flattened ,goniatite1 occurs1 called ,clymenia1 by ,munster 7,endosiphonites1 ,ansted4#cdg-;,a74 ,illustration3 ,fig4 #djc4 ,calceola sandalina1 ,lam4 ,eifel2 also ,south ,devon4 a4 both valves united4 b4 inner side of opercular valve4 ,illustration3 ,fig4 #djd4 ,strygocephalus ,burtini4 7,terebratula porrecta1 ,sow47 ,eifel2 also ,south ,devon4 a4 valves united4 b4 side view of same4 c4 interior of larger valve1 showing thick partition1 and thinner one continued from it4 ,illustration3 ,fig4 #dje4 ,megalodon cucullatus1 ,sow4 ,eifel2 also ,bradley1 ,s4 ,devon4 a4 the valves united4 b4 interior of valve1 showing the large cardinal tooth4 ,illustration3 ,fig4 #djf4 ,clymenia linearis1 ,munster4 7,endosiphonites carinatus1 ,ansted47 ,cornwall4 ,a peculiar species of trilobite1 called ,brontes flabellifer 7fig4 #djg471 is found in the ,devonian strata of the ,eifel and in ,south ,devon4 ,it should be observed1 however1 that the head in the specimen here figured by ,goldfuss1 the most perfect which could be obtained1 is incomplete1 and a restoration has been attempted by ,mr4 ,salter in fig4 #djh41 from data supplied by other species of the same genus occurring in older rocks4 ,illustration3 ,fig4 #djg4 ,brontes flabellifer1 ,goldf4 ,eifel2 also ,s4 ,devon4 ,illustration3 ,fig4 #djh4 ,restored outline of head of ,brontes flabellifer4 ,for determining the true equivalents of the ,devonian group in the ,rhenish provinces and adjacent parts of ,germany1 we are indebted to the labours of ,messrs4 ,sedgwick and ,murchison1 in #ahci1 from which it appears that rocks of that age emerge from beneath the coal-field of ,westphalia1 and are also found in troughs among the ,silurian rocks in ,nassau4 ,many of the limestones1 particularly those on the river ,lahn1 are identical1 both in structure and in coralline remains1 with the beautiful marbles of ,babbacombe1 ,torquay1 and ,plymouth4 ,the limestones of the ,eifel1 long ago celebrated for their fossils1 and which lie in a basin supported by ,silurian rocks1 are found to be referable to the lower part of the ,devonian system4 ,in ,russia1 also1 ,messrs4 ,murchison and ,de ,verneuil have shown 7#ahdj7 that the ,old ,red group occupies a wide area south from ,st4 ,petersburg4 ,it was formerly supposed to be the ,new ,red ,sandstone1 on account of its saliferous and gypseous beds2 but it is now proved to be the ,old ,red by containing ichthyolites of genera which characterize this group in the ,british ,isles1 as1 for example1 ,holoptychius1 ,coccosteus1 ,diplopterus1 c4#cdi-;,a1 associated with mollusca found in the ,devonian of ,western ,europe4 ,among the fish are also many species of sharks of the ,cestraciont division1 a fact worthy of notice1 because the squaloid fishes of the present day offer the highest organization of the brain and of the generative organs1 and make1 in these respects1 the nearest approach to the higher vertebrate classes4 ,devonian ,strata in the ,united ,states4 ,the position of this formation between the carboniferous rocks of ,pennsylvania and ,ohio1 is pointed out in the section1 fig4 #cgi4 p4 #cbg41 and it is a remark of ,m4 de ,verneuil that in no ,european country is there so complete and uninterrupted a development of the ,devonian system as in ,north ,america4 ,at the falls of the ,ohio1 at ,louisville1 in ,kentucky1 there is a grand display of one of the limestones of this period1 resembling a modern coral reef4 ,a wide extent of surface is exposed in a series of horizontal ledges1 at all seasons1 when the water is not high2 and the softer parts of the stone having decomposed and wasted away1 the harder calcareous corals stand out in relief1 and many of them send out branches from their erect stems precisely as if they were living4 ,among other species ,i observed large masses1 not less than #e feet in diameter1 of ,favosites gothlandica1 with its beautiful honeycomb structure well displayed1 and1 by the side of it1 the ,favistella1 combining a similar honeycombed form with the star of the ,astrea4 ,there was also the cup-shaped ,cyathophyllum1 and the delicate network of the ,fenestella1 and that elegant and well-known ,european species of fossil1 called the chain coral1 ,catenipora escharoides1 with a profusion of others 7see fig4 #dbc4 p4 #cee474 ,these coralline forms were mingled with the joints1 stems1 and occasionally the heads1 of lily encrinites4 ,although hundreds of fine specimens have been detached from these rocks1 to enrich the museums of ,europe and ,america1 another crop is constantly working its way out1 under the action of the stream1 and of the sun and rain1 in the warm season when the channel is laid dry4 ,the waters of the ,ohio1 when ,i visited the spot in ,april1 #ahdf1 were more than #dj feet below their highest level1 and #bj feet above their lowest1 so that large spaces of bare rock were exposed to view4#cdi-;,b ,devonian ,flora4 ,with the exception of the fucoids above mentioned 7p4 #cdd471 but little is known with certainty of the plants of the ,devonian group4 ,those found in the department of ,la ,sarthe in ,france1 and in various parts of ,brittany1 formerly referred to the ,devonian era1 have been shown 7in #ahej71 by ,m4 de ,verneuil1 to belong to the carboniferous series4 ,the same may be said of the species of ,lepidodendron1 ,knorria1 ,calamite1 ,sagenaria1 and other genera recently figured 7#ahej71 by ,mr4 ,f4 ,a4 ,roemer1 from the formation called ,greywacke a ,posodonomyes in the ,hartz4#cej-;,a ,they are accompanied by ,goniatites reticulatus ,phillips1 ,g4 intercostatus ,phil41 and other mountain limestone species1 and had been previously assigned to the oldest part of the carboniferous series by ,messrs4 ,murchison and ,sedgwick4 ,if hereafter we should become well acquainted with the land plants of the ,devonian era1 we may confidently expect that nearly all of them will agree generically with those of the carboniferous period1 but the species will be as different as are the ,devonian vertebrate and invertebrate animals from the fossil species of the ,coal4 ,,footnotes3 #cdb-;,c ,see section1 fig4 #cah4 p4 #bhg4 #cdc-;,a ,the ,old ,red ,sandstone1 by ,hugh ,miller1 #ahda4 #cde-;,a ,old ,red ,sandstone4 ,plate #a4 fig4 #a4 ,mr4 ,m4's description of the fish is most graphic and correct4 #cdg-;,a ,camb4 ,phil4 ,trans41 vol4 vi4 pl4 #h4 fig4 #b4 #cdi-;,a ,see ,proceedings of ,geol4 ,soc41 and the anniversary speech of ,dr4 ,buckland1 ,p4 ,g4 ,s41 for #ahda4 #cdi-;,b ,lyell's ,second ,visit to the ,united ,states1 vol4 ii4 p4 #bgg4 #cej-;,a ,memoir on the ,hartz1 ,palaeontographica of ,dunker and ,von ,meyer1 part iii4 ,,chapter ,,xxvii4 ,,silurian ,,group4 ,silurian strata formerly called transition--,term grauwacke--,subdivisions of ,upper and ,lower ,silurian--,ludlow formation and fossils--,wenlock formation1 corals and shells--,caradoc and ,llandeilo beds--,graptolites--,lingula--,trilobite s--,cystideae--,vast thickness of ,silurian strata in ,north ,wales--,unconformability of ,caradoc sandstone--,silurian strata of the ,united ,states--,amount of specific agreement of fossils with those of ,europe--,great number of brachiopods--,deep-sea origin of ,silurian strata--,absence of fluviatile formations--,mineral character of the most ancient fossiliferous rocks4 ,we come next in the descending order to the most ancient of the primary fossiliferous rocks1 that series which comprises the greater part of the strata formerly called transition by ,werner1 for reasons explained in ,chap4 ,,viii41 pp4 #ia and #ib4 ,geologists have also applied to these older strata the general name of grauwacke1 by which the ,german miners designate a particular variety of sandstone1 usually an aggregate of small fragments of quartz1 flinty slate 7or ,lydian stone71 and clay-slate cemented together by argillaceous matter4 ,far too much importance has been attached to this kind of rock1 as if it belonged to a certain epoch in the earth's history1 whereas a similar sandstone or grit is found sometimes in the ,old ,red1 and in the ,millstone ,grit of the ,coal1 and sometimes in certain ,cretaceous and even ,eocene formations in the ,alps4 ,the name of ,silurian was first proposed by ,sir ,roderick ,murchison1 for a series of fossiliferous strata lying below the ,old ,red ,sandstone1 and occupying that part of ,wales and some contiguous counties of ,england1 which once constituted the kingdom of the ,silures1 a tribe of ancient ,britons4 ,the strata have been divided into ,upper and ,lower ,silurian1 and these again in the region alluded to admit of several well-marked subdivisions1 all of them explained in the following table4 ,,upper ,,silurian ,,rocks4 ,prevailing ,thickness ,organic ,lithological in ,feet4 ,remains4 characters4 ,finely laminated ,tilestones4 reddish and #hjj8 green sandstones and shales4 #a4 ,ludlow ,marine mollusca of formation ,upper ,micaceous grey almost every order1 ,ludlow4 sandstone4 the ,brachiopoda most abundant4 ,serpula1 ,aymestry ,argillaceous ,corals1 ,sauroid fish1 limestone4 limestone4 #bjjj ,fuci4 ,lower ,shale1 with ,ludlow4 concretions of limestone4 ,wenlock ,concretionary ,marine mollusca of limestone4 limestone4 various orders as #b4 ,wenlock #ahjj before1 ,crustaceans formation4 of the ,trilobite family4 ,wenlock ,argillaceous ,oldest bones of shale4 shale4 fish yet known4 ,,lower ,,silurian ,,rocks4 ,flags of shelly limestone and ,crinoidea1 ,corals1 #c4 ,caradoc ,caradoc sandstone1 thick #bejj ,mollusca1 chiefly formation4 sandstones4 bedded white ,brachiopoda1 freestone4 ,trilobites4 #d4 ,llandeilo ,llandeilo ,dark coloured #abjj ,mollusca1 formation4 flags4 calcareous flags4 ,trilobites4 ,,upper ,,silurian ,,rocks4 ,ludlow formation4--,this member of the ,upper ,silurian group1 as will be seen by the above table1 is of great thickness1 and subdivided into four parts1--the ,tilestone1 the ,upper and ,lower ,ludlow1 and the intervening ,aymestry limestone4 ,each of these may be distinguished near the town of ,ludlow1 and at other places in ,shropshire and ,herefordshire1 by peculiar organic remains4 #a4 ,tilestones4--,this uppermost division was originally classed by ,sir ,r4 ,murchison with the ,old ,red ,sandstone1 because they decompose into a red soil throughout the ,silurian region4 ,at the same time he regarded the tilestones as a transition group forming a passage from ,silurian to ,old ,red4 ,it is now ascertained that the fossils agree in great part specifically1 and in general character entirely1 with those of the succeeding formation4 #b4 ,upper ,ludlow4--,the next division1 called the ,upper ,ludlow1 consists of grey calcareous sandstone1 decomposing into soft mud1 and contains1 among other shells1 the ,lingula cornea1 which is common to it and the lowest1 or tilestone beds of the ,old ,red4 ,but the ,orthis orbicularis is peculiar to the ,upper ,ludlow1 and very common2 and the lowest or mudstone beds1 are loaded for a thickness of #cj feet with ,terebratula navicula 7fig4 #daj471 in vast numbers4 ,among the cephalopodous mollusca occur the genera ,bellerophon and ,orthoceras1 and among the crustacea the ,homalonotus 7fig4 #dah4 p4 #ced474 ,a coral called ,favosites polymorpha1 ,goldf4 7fig4 #dja4 p4 #cdf47 is found both in this subdivision and in the ,devonian system4 ,illustration3 ,fig4 #dji4 ,orthis orbicularis1 ,j4 ,sow4 ,delbury4 ,upper ,ludlow4 ,illustration3 ,fig4 #daj4 ,terebratula navicula1 ,j4 ,sow4 ,aymestry limestone2 also in ,upper and ,lower ,ludlow4 ,among the fossil shells are species of ,leptaena1 ,orthis1 ,terebratula1 ,avicula1 ,trochus1 ,orthoceras1 ,bellerophon1 and others4#ceb-;,a ,some of the ,upper ,ludlow sandstones are ripple-marked1 thus affording evidence of gradual deposition2 and the same may be said of the accompanying fine argillaceous shales which are of great thickness1 and have been provincially named mudstones4 ,in these shales many zoophytes are found enveloped in an erect position1 having evidently become fossil on the spots where they grew at the bottom of the sea4 ,the facility with which these rocks1 when exposed to the weather1 are resolved into mud1 proves that1 notwithstanding their antiquity1 they are nearly in the state in which they were first thrown down4 ,the scales1 spines 7ichthyodorulites71 jaws1 and teeth of fish of the genera ,onchus1 ,plectrodus1 and others of the same family1 have been met with in the ,upper ,ludlow rocks4 ,illustration3 ,fig4 #daa4 ,pentamerus ,knightii1 ,sow4 ,aymestry4 a4 view of both valves united4 b4 longitudinal section through both valves1 showing the central plate or septum2 half nat4 size4 #c4 ,aymestry limestone4--,the next group is a subcrystalline and argillaceous limestone1 which is in some places #ej feet thick1 and distinguished around ,aymestry by the abundance of ,pentamerus ,knightii1 ,sow4 7fig4 #daa471 also found in the ,lower ,ludlow4 ,this genus of brachiopoda has only been found in the ,silurian strata4 ,the name was derived from pente1 pente1 five1 and meros1 meros1 a part1 because both valves are divided by a central septum1 making four chambers1 and in one valve the septum itself contains a small chamber1 making five2 but neither the structure of this shell1 nor the connection of the animal with its several parts1 are as yet understood4 ,messrs4 ,murchison and ,de ,verneuil discovered this species dispersed in myriads through a white limestone of upper ,silurian age1 on the banks of the ,is1 on the eastern flank of the ,urals in ,russia4 ,illustration3 ,fig4 #dab4 ,lingula ,lewisii1 ,j4 ,sow4 ,abberley ,hills4 ,three other abundant shells in the ,aymestry limestone are1 #ast1 ,lingula ,lewisii 7fig4 #dab472 #b;d1 ,terebratula ,wilsoni1 ,sow4 7fig4 #dac471 which is also common to the ,lower ,ludlow and ,wenlock limestone2 #c;d1 ,atrypa reticularis1 ,lin4 7fig4 #dad471 which has a very wide range1 being found in every part of the ,silurian system1 except the ,llandeilo flags4 ,illustration3 ,fig4 #dac4 ,terebratula ,wilsoni1 ,sow4 ,aymestry4 ,illustration3 ,fig4 #dad4 ,atrypa reticularis4 ,linn4 ,syn4 ,terebratula affinis1 ,min4 ,con4 ,aymestry4 a4 upper valve4 b4 lower4 c4 anterior margin of the valves4 #d4 ,lower ,ludlow shale4--,a dark grey argillaceous deposit1 containing1 among other fossils1 the new genera of chambered shells1 the ,phragmoceras of ,broderip1 and the ,lituites of ,breyn 7see figs4 #dae1 #daf474 ,the latter is partly straight and partly convoluted1 nearly as in ,spirula4 ,illustration3 ,fig4 #dae4 ,phragmoceras ventricosum1 ,j4 ,sow4 7,orthoceras ventricosum1 ,stein47 ,aymestry2 #a_/d nat4 size4 ,illustration3 ,fig4 #daf4 ,lituites giganteus1 ,j4 ,sow4 ,near ,ludlow2 also in the ,aymestry and ,wenlock limestones2 #a_/d nat4 size4 ,illustration3 ,fig4 #dag4 ,fragments of ,orthoceras4 a4 ,fragment of ,orthoceras ,ludense1 ,j4 ,sow4 b4 ,polished section1 showing siphuncle4 ,ludlow4 ,the ,orthoceras ,ludense 7fig4 #dag471 as well as the shell last mentioned1 is peculiar to this member of the series4 ,the ,homalonotus delphinocephalus 7fig4 #dah47 is common to this division and to the ,wenlock limestone4 ,this crustacean belongs to a group of trilobites which has been met with in the ,silurian rocks only1 and in which the tripartite character of the dorsal crust is almost lost4 ,illustration3 ,fig4 #dah4 ,homalonotus delphinocephalus1 ,koenig4#ced-;,a ,dudley ,castle2 #a_/b nat4 size4 ,a species of ,graptolite1 ,g4 ,ludensis1 ,murch4 7fig4 #dai471 a form of zoophyte which has not yet been met with in strata newer than the ,silurian1 occurs in the ,lower ,ludlow4 ,wenlock formation4--,we next come to the ,wenlock formation1 which has been divided 7see ,table1 p4 #cea47 into #a4 ,wenlock limestone1 formerly well known to collectors by the name of the ,dudley limestone1 which forms a continuous ridge1 ranging for about #bj miles from ,s4,w4 to ,n4,e41 about a mile distant from the nearly parallel escarpment of the ,aymestry limestone4 ,the prominence of this rock in ,shropshire1 like that of ,aymestry1 is due to its solidity1 and to the softness of the shales above and below4 ,it is divided into large concretional masses of pure limestone1 and abounds in trilobites1 among which the prevailing species are ,phacops caudatus 7fig4 #dbb47 and ,calymene ,blumenbachii1 commonly called the ,dudley trilobite4 ,the latter is often found coiled up like a wood-louse 7see fig4 #dbj474 ,illustration3 ,fig4 #dai4 ,graptolithus ,ludensis1 ,murchison4 ,lower ,ludlow4 ,illustration3 ,fig4 #dbj4 ,calymene ,blumenbachii1 ,brong4 ,wenlock1 ,l4 ,ludlow1 and ,aym4 limest4 ,illustration3 ,fig4 #dba4 ,leptaena depressa4 ,wenlock4 ,illustration3 ,fig4 #dbb4 ,phacops caudatus1 ,brong4 ,wenlock1 ,aym4 limest41 and ,l4 ,ludlow4 ,leptaena depressa1 ,sow41 is common in this rock1 but also ranges through the ,lower ,ludlow1 ,wenlock shale1 and ,caradoc ,sandstone4 ,illustration3 ,fig4 #dbc4 ,catenipora escharoides4 ,among the corals in which this formation is very rich1 the ,catenipora escharoides1 ,lam4 7fig4 #dbc471 or chain coral1 may be pointed out as one very easily recognized1 and widely spread in ,europe1 ranging through all parts of the ,silurian group1 from the ,aymestry limestone to the bottom of the series4 ,another coral1 the ,porites pyriformis1 is also met with in profusion2 a species common to the ,devonian rocks4 ,cystiphyllum ,siluriense 7fig4 #dbe47 is a species peculiar to the ,wenlock limestone4 ,this new genus1 the name of which is derived from kystis1 a bladder1 and phyllon1 a leaf1 was instituted by ,mr4 ,lonsdale for corals of the ,silurian and ,devonian groups4 ,it is composed of small bladder-like cells 7see fig4 #dbe4 b474 #b4 ,the ,wenlock ,shale1 which exceeds #gjj feet in thickness1 contains many species of brachiopoda1 such as a small variety of the ,lingula ,lewisii 7fig4 #dab471 and the ,atrypa reticularis 7fig4 #dad47 before mentioned1 and it will be seen that several other fossils before enumerated range into this shale4 ,illustration3 ,fig4 #dbd4 ,porites pyriformis1 ,ehren4 ,wenlock limest4 and shale4 ,also in ,aymestry limestone1 and ,l4 ,ludlow4 a4 ,vertical section1 showing transverse lamellae4 ,illustration3 ,fig4 #dbe4 ,cystiphyllum4 a4 ,cystiphyllum ,siluriense1 ,lonsd4 ,wenlock4 b4 ,section of portion1 showing cells4 ,,lower ,,silurian ,,rocks4 ,the ,lower ,silurian rocks have been subdivided into two portions4 #a4 ,the ,caradoc sandstone1 which abuts against the trappean chain called the ,caradoc ,hills1 in ,shropshire4 ,its thickness is estimated at #bejj feet1 and the larger proportion of its fossils are specifically distinct from those of the ,upper ,silurian rocks4 ,among them we find many trilobites and shells of the genera ,orthoceras1 ,nautilus1 and ,bellerophon2 and among the ,brachiopoda the ,pentamerus oblongus and ,p4 laevis 7fig4 #dbf471 which are very abundant and peculiar to this bed2 also ,orthis grandis 7fig4 #dbg471 and a fossil of well-defined form1 ,tentaculites annulatus1 ,schlot4 7fig4 #dbh471 which ,mr4 ,salter has shown to be referable to the ,annelids and to the same tribe as ,serpula4 ,illustration3 ,fig4 #dbf4 ,pentamerus laevis1 ,sow4 ,caradoc ,sandstone4 ,perhaps the young of ,pentamerus oblongus4 a1 b4 ,views of the shell itself1 from figures in ,murchison's ,sil4 ,syst4 c4 ,cast with portion of shell remaining1 and with the hollow of the central septum filled with spar4 d4 ,internal cast of a valve1 the space once occupied by the septum being represented by a hollow in which is seen a cast of the chamber within the septum4 ,illustration3 ,fig4 #dbg4 ,cast of ,orthis grandis1 ,j4 ,sow4 ,horderley2 two-thirds of nat4 size4 ,illustration3 ,fig4 #dbh4 ,tentaculites scalaris1 ,schlot4 ,eastnor ,park2 nat4 size1 and magnified4 ,the most ancient bony remains of fish yet discovered in ,great ,britain are those obtained from the ,wenlock limestones2 but coprolites referred to fish occur still lower in the ,silurian series in ,wales4 ,illustration3 ,fig4 #dbi4 ,ogygia ,buchii1 ,burmeister4 ,syn4 ,asaphus ,buchii1 ,brong4 #a_/d nat4 size4 ,radnorshire4 #b4 ,the ,llandeilo flags1 so named from a town in ,caermarthenshire1 form the base of the ,silurian system1 consisting of dark-coloured micaceous grit1 frequently calcareous1 and distinguished by containing the large trilobites ,asaphus ,buchii and ,a4 tyrannus1 ,murch41 both of which are peculiar to these rocks4 ,several species of ,graptolites 7fig4 #dcj47 occur in these beds4 ,illustration3 ,fig4 #dcj4 a1 b4 ,graptolithus ,murchisonii1 ,beck4 ,llandeilo flags4 ,illustration3 ,fig4 #dca4 ,g4 foliaceus1 ,murchison4 ,llandeilo flags4 ,in the fine shales of this formation ,graptolites are very abundant4 ,i collected these same bodies in great numbers in ,sweden and ,norway in #ahce-f1 both in the higher and lower shales of the ,silurian system2 and was informed by ,dr4 ,beck of ,copenhagen1 that they were fossil zoophytes related to the genera ,pennatula and ,virgularia1 of which the living species now inhabit mud and slimy sediment4 ,the most eminent naturalists still hold to this opinion4 ,a species of ,lingula is met with in the lowest part of the ,llandeilo beds2 and it is remarkable that this brachiopod is among the earliest1 if not the most ancient animal form detected in the lowest ,silurian of ,north ,america4 ,these inhabitants of the seas1 of so remote an epoch1 belonged so strictly to the living genus ,lingula1 as to demonstrate1 like the pteriform ferns of the coal1 through what incalculable periods of time the same plan and type of organization has sometimes prevailed4 ,among the forms of trilobite extremely characteristic of the ,lower ,silurian throughout ,europe and ,north ,america1 the ,trinucleus may be mentioned4 ,this family of crustaceans appears to have swarmed in the ,silurian seas1 just as crabs1 shrimps1 and other genera of crustaceans abound in our own4 ,burmeister1 in his work on the organization of trilobites1 supposes them to have swum at the surface of the water in the open sea and near coasts1 feeding on smaller marine animals1 and to have had the power of rolling themselves into a ball as a defence against injury4 ,they underwent various transformations analogous to those of living crustaceans4 ,m4 ,barrande1 author of a work on the ,silurian rocks of ,bohemia1 has traced the same species from the young state just after its escape from the egg to the adult form1 through various metamorphoses1 each having the appearance of a distinct species4 ,yet1 notwithstanding the numerous species of preceding naturalists which he has thus succeeded in uniting into one1 he announces a forthcoming work in which descriptions and figures of #bej species of ,trilobite will be given4 ,illustration3 ,fig4 #dcb4 ,trinucleus ornatus1 ,burm4 ,cystideae4--,among the additions which recent research has made to the paleontology of the oldest ,silurian rocks1 none are more remarkable than the radiated animals called ,cystideae4 ,their structure and relations were first elucidated in an essay published by ,von ,buch at ,berlin in #ahde4 ,they are usually met with as spheroidal bodies covered with polygonal plates1 with a mouth on the upper side1 and a point of attachment for a stem b 7which is almost always broken off7 on the lower4 7,see fig4 #dcc47 ,they are considered by ,professor ,e4 ,forbes as intermediate between the crinoids and echinoderms4 ,the ,sphaeronites here represented 7fig4 #dcc47 occurs in the ,llandeilo beds in ,wales4#ceh-;,a ,illustration3 ,fig4 #dcc4 ,sphaeronites balticus1 ,eichwald4 7,of the family ,cystideae47 a4 mouth4 b4 point of attachment of stem4 ,lower ,silurian1 ,shole's ,hook and ,bala4 ,thickness and unconformability of ,silurian strata4--,according to the observation of our government surveyors in ,north ,wales1 the ,lower ,silurian strata of that region attain1 in conjunction with the contemporaneous volcanic rocks1 the extraordinary thickness of #bg1jjj feet4 ,one of the groups1 called the trappean1 consisting of slates and associated volcanic ash and greenstone1 is #ae1jjj feet thick4 ,another series1 called the ,bala group1 composed of slates and grits with an impure limestone rich in organic remains1 is #i1jjj feet thick4#cei-;,a ,throughout ,north ,wales the ,wenlock shales rest unconformably upon the ,caradoc sandstones2 and the ,caradoc is in its turn unconformable to the ,llandeilo beds1 showing a considerable interval of time between the deposition of this group and that of the formations next above and below it4 ,the ,caradoc sandstone in the neighbourhood of the ,longmynd ,hills in ,shropshire1 appears to ,professor ,e4 ,forbes to have been a deep-sea deposit formed around the margin of high and steep land4 ,that land consisted partly of upraised ,llandeilo flags and partly of rocks of still older date4#cei-;,b ,such evidence of the successive disturbance of strata during the ,silurian period in ,great ,britain is what we might look for when we have discovered the signs of so grand a series of volcanic eruptions as the contemporaneous greenstones and tuffs of the ,welsh mountains afford4 ,silurian ,strata of the ,united ,states4 ,the position of some of these strata1 where they are bent and highly inclined in the ,appalachian chain1 or where they are nearly horizontal to the west of that chain1 is shown in the section1 fig4 #cgi4 p4 #cbg4 ,but these formations can be studied still more advantageously north of the same line of section1 in the states of ,new ,york1 ,ohio1 and other regions north and south of the great ,canadian lakes4 ,here they are found1 as in ,russia1 in horizontal position1 and are more rich in well-preserved fossils than in almost any spot in ,europe4 ,the ,american strata may readily be divided into ,upper and ,lower ,silurian1 corresponding in age and fossils to the ,european divisions bearing the same names4 ,the subordinate members of the ,new ,york series1 founded on lithological and geographical considerations1 are most useful in the ,united ,states1 but even there are only of local importance4 ,some few of them1 however1 tally very exactly with ,english divisions1 as for example the limestone1 over which the ,niagara is precipitated at the great cataract1 which1 with its underlying shales1 agrees paleontologically with the ,wenlock limestone and shale of ,siluria4 ,there is also a marked general correspondence in the succession of fossil forms1 and even species1 as we trace the organic remains downwards from the highest to the lowest beds4 ,mr4 ,d4 ,sharpe1 in his report on the mollusca collected by me from these strata in ,north ,america#cei-;,c1 has concluded that the number of species common to the ,silurian rocks1 on both sides of the ,atlantic1 is between #cj and #dj per cent42 a result which1 although no doubt liable to future modification1 when a larger comparison shall have been made1 proves1 nevertheless1 that many of the species had a wide geographical range4 ,it seems that comparatively few of the gasteropods and lamellibranchiate bivalves of ,north ,america can be identified specifically with ,european fossils1 while no less than two-fifths of the brachiopoda are the same4 ,in explanation of these facts1 it is suggested1 that most of the recent brachiopoda 7especially the orthidiform ones7 are inhabitants of deep water1 and may have had a wider geographical range than shells living near shore4 ,the predominance of bivalve mollusca of this peculiar class has caused the ,silurian period to be sometimes styled the age of brachiopods4 ,whether the ,silurian rocks are of deep-water origin4--,the grounds relied upon by ,professor ,e4 ,forbes1 for inferring that the larger part of the ,silurian ,fauna is indicative of a sea more than #gj fathoms deep1 are the following3 first1 the small size of the greater number of conchifera2 secondly1 the paucity of pectinibranchiata 7or spiral univalves72 thirdly1 the great number of floaters1 such as ,bellerophon1 ,orthoceras1 c42 fourthly1 the abundance of orthidiform brachiopoda2 fifthly1 the absence or great rarity of fossil fish4 ,it is doubtless true that some living ,terebratulae1 on the coast of ,australia1 inhabit shallow water2 but all the known species1 allied in form to the extinct ,orthis1 inhabit the depths of the sea4 ,it should also be remarked that ,mr4 ,forbes1 in advocating these views1 was well aware of the existence of shores1 bounding the ,silurian sea in ,shropshire1 and of the occurrence of littoral species of this early date in the northern hemisphere4 ,such facts are not inconsistent with his theory2 for he has shown1 in another work1 how1 on the coast of ,lycia1 deep-sea strata are at present forming in the ,mediterranean1 in the vicinity of high and steep land4 ,had we discovered the ancient delta of some large ,silurian river1 we should doubtless have known more of the shallow1 and brackish water1 and fluviatile animals1 and of the terrestrial flora of the period under consideration4 ,to assume that there were no such deltas in the ,silurian world1 would be almost as gratuitous an hypothesis1 as for the inhabitants of the coral islands of the ,pacific to indulge in a similar generalization respecting the actual condition of the globe4#cfj-;,a ,mineral ,character of ,silurian ,strata4 ,in lithological character1 the ,silurian strata vary greatly when we trace them through ,europe and ,north ,america4 ,the shales called mudstones are as little altered from some deposits1 found in recent submarine banks1 as are those of many tertiary formations4 ,we meet with red sandstone and red marl1 with gypsum and salt1 of ,upper ,silurian date1 in the ,niagara district1 which might be mistaken for trias4 ,the whitish granular sandstone at the base of the ,silurian series in ,sweden resembles the tertiary siliceous grit of ,fontainebleau4 ,the ,calcareous ,grit1 oolite1 and pisolite of ,upper ,silurian age in ,gothland1 are described by ,sir ,r4 ,murchison as singularly like rocks of the oolitic period near ,cheltenham2 and1 not to cite more examples1 the ,wenlock or ,dudley limestone often resembles a modern coral-reef4 ,if1 therefore1 uniformity of aspect has been thought characteristic of rocks of this age1 the idea must have arisen from the similarity of feature acquired by strata subject to metamorphic action4 ,this influence1 seeing that the causes of change are always shifting the theatre of their principal development1 must be multiplied throughout a wider geographical area by time1 and become more general in any given system of rocks in proportion to their antiquity4 ,we are now acquainted with dense groups of ,eocene slates in the ,alps1 which were once mistaken by experienced geologists for ,transition or ,silurian formations4 ,the error arose from attaching too great importance to mineral character as a test of age1 for the tertiary slates in question having acquired that crystalline texture which is in reality most prevalent in the most ancient sedimentary formations4 ,,cambrian ,,group4 ,below the ,silurian strata in ,north ,wales1 and in the region of the ,cumberland lakes1 there are some slaty rocks1 devoid of organic remains1 or in which a few obscure traces only of fossils have been detected 7for which the names of ,cambrian and ,cumbrian have been proposed74 ,whether these will ever be entitled by the specific distinctness of their fossils to rank as independent groups1 we have not yet sufficient data to determine4 99 99 99 99 99 ,,tabular ,,view ,,of ,,fossiliferous ,,strata1 ,showing the ,order of ,superposition or ,chronological ,succession of the principal ,european ,groups4 ,i4 ,,post-,,tertiary4 ,a4 ,,post-,,pliocene4 ,periods and ,groups4 ,examples4 ,observations4 #a4 ,recent4 ,peat mosses and shell-marl1 ,all the imbedded shells1 with bones of land animals1 freshwater and marine1 human remains1 and works of living species1 of art4 with occasional human remains and ,newer parts of modern deltas works of art4 and coral reefs4 #b4 ,post-,pliocene4 ,clay1 marl1 and volcanic tuff ,all the shells of living of ,ischia1 p4 #aac4 species4 ,no human remains or works ,loess of the ,rhine1 p4 #aag4 of art4 ,bones of quadrupeds1 partly ,newer part of boulder of extinct species4 formation1 with erratics1 p4 #abd4 ,,ii4 ,,tertiary4 ,b4 ,,pliocene4 #c4 ,newer ,pliocene ,boulder formation or drift of ,three-fourths of the or ,pleistocene4 northern ,europe and ,north fossil shells of ,america1 chaps4 #aa4 #ab4 existing species4 ,cavern deposits and osseous ,a majority of the breccias1 p4 #aec4 mammalia extinct2 but the genera ,fluvio-marine crag of ,norwich1 corresponding with p4 #adh4 those now surviving in the same great ,limestone of ,girgenti1 geographical and in ,sicily1 p4 #aeb4 zoological province1 p4 #aeg4 ,during part of this period icebergs frequent in the seas of the northern hemisphere1 and glaciers on hills of moderate height4 #d4 ,older ,pliocene4 ,red and ,coralline crag of ,a third or more of the ,suffolk1 p4 #afb4 species of mollusca extinct4 ,subapennine beds1 p4 #aff4 ,nearly1 if not all1 the mammalia extinct4 ,c4 ,,miocene4 #e4 ,miocene4 ,faluns of ,touraine1 p4 #afh4 ,about two-thirds of the species of shells ,part of ,bordeaux beds1 p4 #aga4 extinct4 ,part of ,molasse of ,the recent species of ,switzerland1 p4 #aga4 shells often not found in the adjoining seas1 but in warmer latitudes4 ,all the mammalia extinct4 ,d4 ,,eocene4 #f4 ,upper ,eocene4 ,upper marine of ,paris basin1 ,fossil shells of the ,fontainebleau sandstone1 ,eocene period1 with p4 #age4 very few exceptions1 extinct4 ,those which ,upper freshwater and millstone are identified with of same4 living species rarely ,kleyn ,spauwen beds1 p4 #agf4 belong to neighbouring regions4 ,hermsdorf tile-clay1 near ,berlin4 ,all the mammalia of extinct species1 and ,mayence tertiary strata1 the greater part of p4 #agg4 them of extinct genera4 ,freshwater beds of ,limagne d',auvergne1 p4 #aha4 ,plants of ,upper ,eocene1 indicating a south #g4 ,middle ,eocene4 ,paris gypsum with ,european or ,paleotherium1 c41 p4 #aia4 ,mediterranean climate2 those of ,lower ,eocene1 ,freshwater and fluvio-marine a tropical climate4 beds of ,headon ,hill1 ,isle of ,wight1 p4 #aig4 ,barton beds1 ,hants1 p4 #aih4 ,calcaire ,grossier1 ,paris1 p4 #aic4 ,bagshot and ,bracklesham beds1 ,surrey and ,sussex1 p4 #aih4 #h4 ,lower ,eocene4 ,london clay proper of ,highgate ,hill and ,sheppey1--,bognor beds1 ,sussex1 p4 #bjj4 ,sables inferieurs1 and lits coquilliers of ,paris basin1 p4 #aif4 ,mottled and plastic clays and sands of the ,hampshire and ,london basins1 p4 #bjc4 ,sables inferieurs and argiles plastiques of ,paris basin1 p4 #aif4 ,nummulitic formation of the ,alps1 p4 #bje4 ,,iii4 ,,secondary4 ,e4 ,,cretaceous4 ,sec4 ,,upper ,,cretaceous4 #i4 ,maestricht ,yellowish white limestone of ,ammonite1 ,baculite1 and beds4 ,maestricht1 p4 #bji4 ,belemnite1 associated with ,cypraea1 ,oliva1 ,coralline limestone of ,faxoe1 ,mitra1 ,trochus1 c4 ,denmark1 p4 #baj4 ,large marine saurians4 #aj4 ,upper ,white ,white chalk with flints of ,marine limestone ,chalk4 ,north and ,south formed in part of ,downs1--,surrey and ,sussex1 decomposed corals4 p4 #baa4 #aa4 ,lower ,white ,chalk without flints1 and ,chalk4 chalk marl1 ibid4 #ab4 ,upper ,loose sand1 with bright green ,greensand4 particles1 ibid4 ,firestone of ,merstham1 ,kent1 p4 #bah4 ,marly stone1 with layers of chert1 south of ,isle of ,wight4 #ac4 ,gault4 ,dark blue marl at base of ,numerous extinct genera chalk escarpment1--,kent of conchiferous and ,sussex1 p4 #bah4 cephalopoda1 ,hamite1 ,scaphite1 ,ammonite1 c4 ,sec4,sec4 ,,lower ,,cretaceous4 #ad4 ,lower ,sand with green matter1--,weald ,species of shells1 c41 ,greensand4 of ,kent and ,sussex1 nearly all distinct p4 #bai4 from those of ,upper ,cretaceous2 most of ,white1 yellowish1 and the genera the same4 ferruginous sand1 with concretions of limestone and chert1--,atherfield1 ,isle of ,wight4 ,limestone called ,kentish ,rag ,f4 ,,wealden4 #ae4 ,weald ,clay4 ,clay with occasional bands of ,of freshwater origin4 limestone1--,weald of ,kent1 ,shells of ,surrey1 and ,sussex1 p4 #bbg4 pulmoniferous mollusca1 and of ,cypris4 ,land reptiles4 #af4 ,hastings ,sand4 ,sand with calciferous grit and ,freshwater with clay1--,hastings1 ,sussex1 intercalated bed of ,cuckfield1 ,kent1 p4 #bbi4 brackish and salt water origin4 ,shells of fluviatile and lacustrine genera4 ,reptiles of the genera ,pterodactyle1 ,iguanodon1 ,megalosaurus1 ,plesiosaurus1 ,trionyx1 and ,emys4 #ag4 ,purbeck ,beds4 ,limestones1 calcareous slates ,chiefly freshwater1 and and marls1 p4 #bca4 divisible into three groups1 each containing distinct species of freshwater mollusca and of entomostraca4 ,alternations of deposits formed in fresh1 brackish1 and marine water1 and of ancient soils formed on land and retaining roots of trees4 ,plants chiefly cycads and conifers1 p4 #bca4 ,g4 ,,oolite4 #ah4 ,upper ,oolite4 a4 ,portland building stone1 ,ammonites and ,belemnites p4 #bei4 numerous4 b4 ,portland sand4 ,large saurians1 as ,pterodactyles1 c4 ,kimmeridge clay1 ,plesiosaurs1 ,dorsetshire1 p4 #bfj4 ,ichthyosaurs4 #ai4 ,middle ,oolite4 a4 ,coral ,rag1 p4 #bfj4 ,no cetaceans yet known1 ,calcareous freestones1 but three species of oolitic1 often full of terrestrial mammalia1 corals4 ,oxfordshire4 p4 #bfg1 #bfh4 ,preponderance of b4 ,oxford clay--,dark blue ganoid fish4 ,the clay1--,oxfordshire and plants chiefly cycads1 midland counties1 p4 #bfb4 conifers1 and ferns1 with a few palms4 #bj4 ,lower ,oolite4 a4 ,cornbrash and forest marble1 ,wiltshire1 p4 #bfc4 b4 ,great oolite and ,stonesfield slate1--,bath1 ,bradford1 ,stonesfield near ,woodstock1 ,oxfordshire1 p4 #bff4 c4 ,fuller's earth1--,clay containing fuller's earth near ,bath1 p4 #bgb4 d4 ,inferior oolite1 calcareous freestone1 and yellow sands1--,cotteswold ,hills1 ,dundry ,hill1 near ,bristol1 p4 #bgb4 ,h4 ,,lias4 #ba4 ,lias4 ,argillaceous limestone1 marl ,mollusca1 reptiles1 and clay1--,lyme ,regis1 and fish of genera ,dorsetshire1 p4 #bgc4 analogous to the oolitic4 ,i4 ,,trias4 #bb4 ,upper ,trias4 ,keuper of ,germany1 or ,batrachian reptiles1 variegated marls--,red1 grey1 e4g4 ,labyrinthodon1 green1 blue1 and white marls ,rhyncosaurus1 c4 and sandstones with ,cephalopoda3 gypsum--,wuertemberg1 bone-bed ,ceratites4 ,no of ,axmouth1 ,dorset1 p4 #bhi4 ,belemnites4 ,plants3 ,ferns1 ,cycads1 ,conifers4 #bc4 ,middle ,trias ,compact greyish limestone ,with ,equisetites or with beds of dolomite and and ,calamite4 ,muschelkalk4 gypsum1--,north of ,germany1 p4 #bhg4 ,wanting in ,england4 #bd4 ,lower ,trias4 ,variegated or ,bunter sandstone ,plants different for of ,germans--,red and white the most part from spotted sandstone with those of the ,upper gypsum and rock-salt1 ,p4 #bhh ,trias4 ,part of ,new ,red sandstone of of ,cheshire with rock-salt1 p4 #bid4 ,,iv4 ,,primary4 ,k4 ,,permian4 #be4 ,upper ,permian4 ,yellow magnesian limestone1 ,organic remains1 both ,yorkshire and ,durham1 animal and vegetable1 ,p4 #cja4 more allied to primary than to secondary ,zechstein of ,thuringia1 ,upper periods4 part of ,permian beds1 ,russia4 #bf4 ,lower ,permian4 a4 ,marl slate of ,durham and ,thecodont saurians4 ,thuringia4 ,heterocercal fish of genus ,palaeoniscus1 c4 b4 ,lower ,new ,red sandstone of north of ,england and ,rothliegendes of ,germany4 a4 and b4 ,lower part of ,permian beds1 ,russia1 p4 #cja4 ,l4 ,,carboniferous4 #bg4 ,coal measures4 a4 ,strata of sandstone and ,great thickness of shale1 with beds of strata of coal1--,s4 ,wales and fluvio-marine origin1 ,northumberland1 p4 #cji4 with beds of coal of vegetable origin1 b4 ,millstone grit1--,s4 based on soils ,wales1 ,bristol coal-field1 retaining the roots ,yorkshire1 p4 #cjh4 of trees4 ,oldest of known reptiles or ,archegosaurus4 ,sauroid fish4 #bh4 ,mountain ,carboniferous or mountain ,brachiopoda of genus limestone4 limestone1 with marine ,productus4 shells and corals4 ,cephalopoda of genera ,mendip ,hills1 and many parts ,cyrtoceras1 ,goniatite1 of ,ireland1 p4 #cdj4 ,orthoceras4 ,crustaceans of the genus ,phillipsia4 ,crinoideans abundant4 ,m4 ,,devonian4 #bi4 ,upper a4 ,yellow sandstone of ,dura ,tribe of fish with hard ,devonian4 ,den1 ,fife4 coverings like chelonians1 b4 ,red sandstone and marl ,pterichthys1 with cornstone of ,pamphractus1 c42 ,herefordshire and also of genera ,forfarshire4 ,cephalaspis1 ,holoptichius1 c4 ,paving and roofing-stone1 ,forfarshire4 ,no reptiles yet known4 ,upper part of ,devonian beds of ,south ,devon4 #cj4 ,lower ,grey sandstone with ,fish1 partly of same ,devonian4 ,ichthyolites1--,caithness1 genera1 but of ,cromarty1 and ,orkney1 ,lower distinct species from part of ,devonian beds of those in ,upper ,south ,devon1 and green ,devonian2 also chloritic slates of ,osteolepis1 ,cornwall1 limestone of ,coccosteus1 ,gerolstein1 ,eifel4 ,glyptolepis1 ,dipterus1 c4 ,n4 ,,silurian4 #ca4 ,upper a4 ,tilestone of ,brecon and ,oldest of fossil fish ,silurian4 ,caermarthen4 yet discovered4 b4 ,limestone and shale1 ,trilobites and ,ludlow1 ,shropshire4 ,graptolites abundant4 c4 ,wenlock or ,dudley ,brachiopoda very limestone4 numerous4 ,cephalopoda3 ,bellerophon1 ,orthoceras4 ,same genera of #cb4 ,lower a4 ,caradoc sandstone1 ,caer invertebrate animals ,silurian4 ,caradoc1 ,shropshire4 as in ,upper ,silurian1 but species chiefly b4 ,llandeilo flags1 distinct4 ,trinucleus calcareous flags and caractaci1 ,cystideae1 schists1--,builth1 p4 #ceh4 ,radnorshire1 ,llandeilo1 ,caermarthenshire4 ,no land plants yet known4 ,footprints of tortoise1 see note1 p4 #cfj4 ,,footnotes3 #ceb-;,a ,murchison1 ,silurian ,system1 p4 #aih1 #aii4 #ced-;,a ,silurian ,system1 pl4 #g4 bis4 fig4 #a4 b4 #ceh-;,a ,quart4 ,geol4 ,journ41 vol4 ii4 p4 #aa42 and ,memoirs of ,geol4 ,survey1 vol4 ii4 p4 #eah4 #cei-;,a ,quart4 ,geol4 ,journ41 vol4 iv4 p4 #cjj4 #cei-;,b ,ibid41 #bii4 #cei-;,c ,ibid41 #ade4 #cfj-;,a ,since this was written1 ,mr4 ,logan has discovered chelonian footprints in the lowest fossiliferous beds of the ,silurian series1 near ,montreal1 in ,canada4 ,professor ,owen inclines to refer them to the genus ,emys4--,quart4 ,journ4 ,g4 ,s41 vol4 vii4 p4 lxxvi4 ,,chapter ,,xxviii4 ,,volcanic ,,rocks4 ,trap rocks--,name1 whence derived--,their igneous origin at first doubted--,their general appearance and character--,volcanic cones and craters1 how formed--,mineral composition and texture of volcanic rocks--,varieties of felspar--,hornblende and augite--,isomorphism--,rocks1 how to be studied--,basalt1 greenstone1 trachyte1 porphyry1 scoria1 amygdaloid1 lava1 tuff--,alphabetical list1 and explanation of names and synonyms1 of volcanic rocks--,table of the analyses of minerals most abundant in the volcanic and hypogene rocks4 ,the aqueous or fossiliferous rocks having now been described1 we have next to examine those which may be called volcanic1 in the most extended sense of that term4 ,suppose a a in the annexed diagram1 to represent the crystalline formations1 such as the granitic and metamorphic2 b b the fossiliferous strata2 and c c the volcanic rocks4 ,these last are sometimes found1 as was explained in the first chapter1 breaking through a and b1 sometimes overlying both1 and occasionally alternating with the strata b b4 ,they also are seen1 in some instances1 to pass insensibly into the unstratified division of a1 or the ,plutonic rocks4 ,illustration3 ,fig4 #dcd4 ,cross section4 a4 ,hypogene formations1 stratified and unstratified4 b4 ,aqueous formations4 c4 ,volcanic rocks4 ,when geologists first began to examine attentively the structure of the northern and western parts of ,europe1 they were almost entirely ignorant of the phenomena of existing volcanos4 ,they also found certain rocks1 for the most part without stratification1 and of a peculiar mineral composition1 to which they gave different names1 such as basalt1 greenstone1 porphyry1 and amygdaloid4 ,all these1 which were recognized as belonging to one family1 were called trap by ,bergmann1 from trappa1 ,swedish for a flight of steps--a name since adopted very generally into the nomenclature of the science2 for it was observed that many rocks of this class occurred in great tabular masses of unequal extent1 so as to form a succession of terraces or steps on the sides of hills4 ,this configuration appears to be derived from two causes4 ,first1 the abrupt original terminations of sheets of melted matter1 which have spread1 whether on the land or bottom of the sea1 over a level surface4 ,for we know1 in the case of lava flowing from a volcano1 that a stream1 when it has ceased to flow1 and grown solid1 very commonly ends in a steep slope1 as at a1 fig4 #dce4 ,but1 secondly1 the step-like appearance arises more frequently from the mode in which horizontal masses of igneous rock1 such as b c1 intercalated between aqueous strata1 have1 subsequently to their origin1 been exposed1 at different heights1 by denudation4 ,such an outline1 it is true1 is not peculiar to trap rocks2 great beds of limestone1 and other hard kinds of stone1 often presenting similar terraces and precipices3 but these are usually on a smaller scale1 or less numerous1 than the volcanic steps1 or form less decided features in the landscape1 as being less distinct in structure and composition from the associated rocks4 ,illustration3 ,fig4 #dce4 ,step-like appearance of trap4 ,although the characters of trap rocks are greatly diversified1 the beginner will easily learn to distinguish them as a class from the aqueous formations4 ,sometimes they present themselves1 as already stated1 in tabular masses1 which are not divided into strata3 sometimes in shapeless lumps and irregular cones1 forming chains of small hills4 ,often they are seen in dikes and wall-like masses1 intersecting fossiliferous beds4 ,the rock is occasionally found divided into columns1 often decomposing into balls of various sizes1 from a few inches to several feet in diameter4 ,the decomposing surface very commonly assumes a coating of a rusty iron colour1 from the oxidation of ferruginous matter1 so abundant in the traps in which augite or hornblende occur2 or1 in the felspathic varieties of trap1 it acquires a white opaque coating1 from the bleaching of the mineral called felspar4 ,on examining any of these volcanic rocks1 where they have not suffered disintegration1 we rarely fail to detect a crystalline arrangement in one or more of the component minerals4 ,sometimes the texture of the mass is cellular or porous1 or we perceive that it has once been full of pores and cells1 which have afterwards become filled with carbonate of lime1 or other infiltrated mineral4 ,most of the volcanic rocks produce a fertile soil by their disintegration4 ,it seems that their component ingredients1 silica1 alumina1 lime1 potash1 iron1 and the rest1 are in proportions well fitted for vegetation4 ,as they do not effervesce with acids1 a deficiency of calcareous matter might at first be suspected2 but although the carbonate of lime is rare1 except in the nodules of amygdaloids1 yet it will be seen that lime sometimes enters largely into the composition of augite and hornblende4 7,see ,table1 p4 #cgg47 ,cones and ,craters4--,in regions where the eruption of volcanic matter has taken place in the open air1 and where the surface has never since been subjected to great aqueous denudation1 cones and craters constitute the most striking peculiarity of this class of formations4 ,many hundreds of these cones are seen in central ,france1 in the ancient provinces of ,auvergne1 ,velay1 and ,vivarais1 where they observe1 for the most part1 a linear arrangement1 and form chains of hills4 ,although none of the eruptions have happened within the historical era1 the streams of lava may still be traced distinctly descending from many of the craters1 and following the lowest levels of the existing valleys4 ,the origin of the cone and crater-shaped hill is well understood1 the growth of many having been watched during volcanic eruptions4 ,a chasm or fissure first opens in the earth1 from which great volumes of steam and other gases are evolved4 ,the explosions are so violent as to hurl up into the air fragments of broken stone1 parts of which are shivered into minute atoms4 ,at the same time melted stone or lava usually ascends through the chimney or vent by which the gases make their escape4 ,although extremely heavy1 this lava is forced up by the expansive power of entangled gaseous fluids1 chiefly steam or aqueous vapour1 exactly in the same manner as water is made to boil over the edge of a vessel when steam has been generated at the bottom by heat4 ,large quantities of the lava are also shot up into the air1 where it separates into fragments1 and acquires a spongy texture by the sudden enlargement of the included gases1 and thus forms scoriae1 other portions being reduced to an impalpable powder or dust4 ,the showering down of the various ejected materials round the orifice of eruption gives rise to a conical mound1 in which the successive envelopes of sand and scoriae form layers1 dipping on all sides from a central axis4 ,in the mean time a hollow1 called a crater1 has been kept open in the middle of the mound by the continued passage upwards of steam and other gaseous fluids4 ,the lava sometimes flows over the edge of the crater1 and thus thickens and strengthens the sides of the cone2 but sometimes it breaks it down on one side1 and often it flows out from a fissure at the base of the hill 7see fig4 #dcf474cfh-;,a ,illustration3 ,fig4 #dcf4 ,part of the chain of extinct volcanos called the ,monts ,dome1 ,auvergne4 7,scrope47 ,composition and nomenclature4--,before speaking of the connection between the products of modern volcanos and the rocks usually styled trappean1 and before describing the external forms of both1 and the manner and position in which they occur in the earth's crust1 it will be desirable to treat of their mineral composition and names4 ,the varieties most frequently spoken of are basalt1 greenstone1 syenitic greenstone1 clinkstone1 claystone1 and trachyte2 while those founded chiefly on peculiarities of texture1 are porphyry1 amygdaloid1 lava1 tuff1 scoriae1 and pumice4 ,it may be stated generally1 that all these are mainly composed of two minerals1 or families of simple minerals1 felspar and hornblende2 some almost entirely of hornblende1 others of felspar4 ,these two minerals may be regarded as two groups1 rather than species4 ,felspar1 for example1 may be1 first1 common felspar1 that is to say1 potash-felspar1 in which the alkali is potash 7see table1 p4 #cgg472 or1 secondly1 albite1 that is to say1 soda-felspar1 where the alkali is soda instead of potash2 or1 thirdly1 ,labrador-felspar 7,labradorite71 which differs not only in its iridescent hues1 but also in its angle of fracture or cleavage1 and its composition4 ,we also read much of two other kinds1 called glassy felspar and compact felspar1 which1 however1 cannot rank as varieties of equal importance1 for both the albitic and common felspar appear sometimes in transparent or glassy crystals2 and as to compact felspar1 it is a compound of a less definite nature1 sometimes containing both soda and potash2 and which might be called a felspathic paste1 being the residuary matter after portions of the original matrix have crystallized4 ,the other group1 or hornblende1 consists principally of two varieties2 first1 hornblende1 and1 secondly1 augite1 which were once regarded as very distinct1 although now some eminent mineralogists are in doubt whether they are not one and the same mineral1 differing only as one crystalline form of native sulphur differs from another4 ,the history of the changes of opinion on this point is curious and instructive4 ,werner first distinguished augite from hornblende2 and his proposal to separate them obtained afterwards the sanction of ,hauey1 ,mohs1 and other celebrated mineralogists4 ,it was agreed that the form of the crystals of the two species were different1 and their structure1 as shown by cleavage1 that is to say1 by breaking or cleaving the mineral with a chisel1 or a blow of the hammer1 in the direction in which it yields most readily4 ,it was also found by analysis that augite usually contained more lime1 less alumina1 and no fluoric acid2 which last1 though not always found in hornblende1 often enters into its composition in minute quantity4 ,in addition to these characters1 it was remarked as a geological fact1 that augite and hornblende are very rarely associated together in the same rock2 and that when this happened1 as in some lavas of modern date1 the hornblende occurs in the mass of the rock1 where crystallization may have taken place more slowly1 while the augite merely lines cavities where the crystals may have been produced rapidly4 ,it was also remarked1 that in the crystalline slags of furnaces1 augitic forms were frequent1 the hornblendic entirely absent2 hence it was conjectured that hornblende might be the result of slow1 and augite of rapid cooling4 ,this view was confirmed by the fact1 that ,mitscherlich and ,berthier were able to make augite artificially1 but could never succeed in forming hornblende4 ,lastly1 ,gustavus ,rose fused a mass of hornblende in a porcelain furnace1 and found that it did not1 on cooling1 assume its previous shape1 but invariably took that of augite4 ,the same mineralogist observed certain crystals in rocks from ,siberia which presented a hornblende cleavage1 while they had the external form of augite4 ,if1 from these data1 it is inferred that the same substance may assume the crystalline forms of hornblende or augite indifferently1 according to the more or less rapid cooling of the melted mass1 it is nevertheless certain that the variety commonly called augite1 and recognized by a peculiar crystalline form1 has usually more lime in it1 and less alumina1 than that called hornblende1 although the quantities of these elements do not seem to be always the same4 ,unquestionably the facts and experiments above mentioned show the very near affinity of hornblende and augite2 but even the convertibility of one into the other by melting and recrystallizing1 does not perhaps demonstrate their absolute identity4 ,for there is often some portion of the materials in a crystal which are not in perfect chemical combination with the rest4 ,carbonate of lime1 for example1 sometimes carries with it a considerable quantity of silex into its own form of crystal1 the silex being mechanically mixed as sand1 and yet not preventing the carbonate of lime from assuming the form proper to it4 ,this is an extreme case1 but in many others some one or more of the ingredients in a crystal may be excluded from perfect chemical union2 and1 after fusion1 when the mass recrystallizes1 the same elements may combine perfectly or in new proportions1 and thus a new mineral may be produced4 ,or some one of the gaseous elements of the atmosphere1 the oxygen for example1 may1 when the melted matter reconsolidates1 combine with some one of the component elements4 ,the different quantity of the impurities or refuse above alluded to1 which may occur in all but the most transparent and perfect crystals1 may partly explain the discordant results at which experienced chemists have arrived in their analysis of the same mineral4 ,for the reader will find that a mineral determined to be the same by its physical characters1 crystalline form1 and optical properties1 has often been declared by skilful analyzers to be composed of distinct elements4 7,see the table at p4 #cgg47 ,this disagreement seemed at first subversive of the atomic theory1 or the doctrine that there is a fixed and constant relation between the crystalline form and structure of a mineral1 and its chemical composition4 ,the apparent anomaly1 however1 which threatened to throw the whole science of mineralogy into confusion1 was in a great degree reconciled to fixed principles by the discoveries of ,professor ,mitscherlich at ,berlin1 who ascertained that the composition of the minerals which had appeared so variable1 was governed by a general law1 to which he gave the name of isomorphism 7from isos1 isos1 equal1 and morphe1 morphe1 form74 ,according to this law1 the ingredients of a given species of mineral are not absolutely fixed as to their kind and quality2 but one ingredient may be replaced by an equivalent portion of some analogous ingredient4 ,thus1 in augite1 the lime may be in part replaced by portions of protoxide of iron1 or of manganese1 while the form of the crystal1 and the angle of its cleavage planes1 remain the same4 ,these vicarious substitutions1 however1 of particular elements cannot exceed certain defined limits4 ,having been led into this digression on the recent progress of mineralogy1 ,i may here observe that the geological student must endeavour as soon as possible to familiarize himself with the characters of five at least of the most abundant simple minerals of which rocks are composed4 ,these are1 felspar1 quartz1 mica1 hornblende1 and carbonate of lime4 ,this knowledge cannot be acquired from books1 but requires personal inspection1 and the aid of a teacher4 ,it is well to accustom the eye to know the appearance of rocks under the lens4 ,to learn to distinguish felspar from quartz is the most important step to be first aimed at4 ,in general we may know the felspar because it can be scratched with the point of a knife1 whereas the quartz1 from its extreme hardness1 receives no impression4 ,but when these two minerals occur in a granular and uncrystallized state1 the young geologist must not be discouraged if1 after considerable practice1 he often fails to distinguish them by the eye alone4 ,if the felspar is in crystals1 it is easily recognized by its cleavage3 but when in grains the blow-pipe must be used1 for the edges of the grains can be rounded in the flame1 whereas those of quartz are infusible4 ,if the geologist is desirous of distinguishing the three varieties of felspar above enumerated1 or hornblende from augite1 it will often be necessary to use the reflecting goniometer as a test of the angle of cleavage1 and shape of the crystal4 ,the use of this instrument will not be found difficult4 ,the external characters and composition of the felspars are extremely different from those of augite or hornblende2 so that the volcanic rocks in which either of these minerals decidedly predominates1 are easily recognized4 ,but there are mixtures of the two elements in every possible proportion1 the mass being sometimes exclusively composed of felspar1 at other times solely of augite1 or1 again1 of both in equal quantities4 ,occasionally1 the two extremes1 and all the intermediate gradations1 may be detected in one continuous mass4 ,nevertheless there are certain varieties or compounds which prevail so largely in nature1 and preserve so much uniformity of aspect and composition1 that it is useful in geology to regard them as distinct rocks1 and to assign names to them1 such as basalt1 greenstone1 trachyte1 and others1 already mentioned4 ,basalt4--,as an example of rocks in which augite greatly prevails1 basalt may first be mentioned4 ,although we are more familiar with this term than with that of any other kind of trap1 it is difficult to define it1 the name having been used so vaguely4 ,it has been very generally applied to any trap rock of a black1 bluish1 or leaden-grey colour1 having a uniform and compact texture4 ,most strictly1 it consists of an intimate mixture of augite1 felspar1 and iron1 to which a mineral of an olive green colour1 called olivine1 is often superadded1 in distinct grains or nodular masses4 ,the iron is usually magnetic1 and is often accompanied by another metal1 titanium4 ,augite is the predominant mineral1 the felspar being in much smaller proportions4 ,there is no doubt that many of the fine-grained and dark-coloured trap rocks1 called basalt1 contained hornblende in the place of augite2 but this will be deemed of small importance after the remarks above made4 ,other minerals are occasionally found in basalt2 and this rock may pass insensibly into almost every variety of trap1 especially into greenstone1 clinkstone1 and wacke1 which will be presently described4 ,greenstone1 or ,dolerite1 is usually defined as a granular rock1 the constituent parts of which are hornblende and imperfectly crystallized felspar2 the felspar being more abundant than in basalt2 and the grains or crystals of the two minerals more distinct from each other4 ,this name may also be extended to those rocks in which augite is substituted for hornblende 7the dolorite of some authors71 or to those in which albite replaces common felspar1 forming the rock sometimes called ,andesite4 ,syenitic greenstone4--,the highly crystalline compounds of the same two minerals1 felspar and hornblende1 having a granitiform texture1 and with occasionally some quartz accompanying1 may be called ,syenitic greenstone1 a rock which frequently passes into ordinary trap1 and as frequently into granite4 ,trachyte4--,a porphyritic rock of a whitish or greyish colour1 composed principally of glassy felspar1 with crystals of the same1 generally with some hornblende and some titaniferous iron4 ,in composition it is extremely different from basalt1 this being a felspathic1 as the other is an augitic1 rock4 ,it has a peculiar rough feel1 whence the name trachys1 trachus1 rough4 ,some varieties of trachyte contain crystals of quartz4 ,illustration3 ,fig4 #dcg4 ,porphyry4 ,white crystals of felspar in a dark base of hornblende and felspar4 ,porphyry is merely a certain form of rock1 very characteristic of the volcanic formations4 ,when distinct crystals of one or more minerals are scattered through an earthy or compact base1 the rock is termed a porphyry 7see fig4 #dcg474 ,thus trachyte is porphyritic2 for in it1 as in many modern lavas1 there are crystals of felspar2 but in some porphyries the crystals are of augite1 olivine1 or other minerals4 ,if the base be greenstone1 basalt1 or pitchstone1 the rock may be denominated greenstone-porphyry1 pitchstone-porphyry1 and so forth4 ,amygdaloid4--,this is also another form of igneous rock1 admitting of every variety of composition4 ,it comprehends any rock in which round or almond-shaped nodules of some mineral1 such as agate1 calcedony1 calcareous spar1 or zeolite1 are scattered through a base of wacke1 basalt1 greenstone1 or other kind of trap4 ,it derives its name from the ,greek word amygdala1 an almond4 ,the origin of this structure cannot be doubted1 for we may trace the process of its formation in modern lavas4 ,small pores or cells are caused by bubbles of steam and gas confined in the melted matter4 ,after or during consolidation1 these empty spaces are gradually filled up by matter separating from the mass1 or infiltered by water permeating the rock4 ,as these bubbles have been sometimes lengthened by the flow of the lava before it finally cooled1 the contents of such cavities have the form of almonds4 ,in some of the amygdaloidal traps of ,scotland1 where the nodules have decomposed1 the empty cells are seen to have a glazed or vitreous coating1 and in this respect exactly resemble scoriaceous lavas1 or the slags of furnaces4 ,illustration3 ,fig4 #dch4 ,scoriaceous lava in part converted into an amygdaloid4 ,montagne de la ,veille1 ,department of ,puy de ,dome1 ,france4 ,the annexed figure represents a fragment of stone taken from the upper part of a sheet of basaltic lava in ,auvergne4 ,one half is scoriaceous1 the pores being perfectly empty2 the other part is amygdaloidal1 the pores or cells being mostly filled up with carbonate of lime1 forming white kernels4 ,scoriae and ,pumice may next be mentioned as porous rocks1 produced by the action of gases on materials melted by volcanic heat4 ,scoriae are usually of a reddish-brown and black colour1 and are the cinders and slags of basaltic or augitic lavas4 ,pumice is a light1 spongy1 fibrous substance1 produced by the action of gases on trachytic and other lavas2 the relation1 however1 of its origin to the composition of lava is not yet well understood4 ,von ,buch says that it never occurs where only ,labrador-felspar is present4 ,lava4--,this term has a somewhat vague signification1 having been applied to all melted matter observed to flow in streams from volcanic vents4 ,when this matter consolidates in the open air1 the upper part is usually scoriaceous1 and the mass becomes more and more stony as we descend1 or in proportion as it has consolidated more slowly and under greater pressure4 ,at the bottom1 however1 of a stream of lava1 a small portion of scoriaceous rock very frequently occurs1 formed by the first thin sheet of liquid matter1 which often precedes the main current1 or in consequence of the contact with water in or upon the damp soil4 ,the more compact lavas are often porphyritic1 but even the scoriaceous part sometimes contains imperfect crystals1 which have been derived from some older rocks1 in which the crystals pre-existed1 but were not melted1 as being more infusible in their nature4 ,although melted matter rising in a crater1 and even that which enters rents on the side of a crater1 is called lava1 yet this term belongs more properly to that which has flowed either in the open air or on the bed of a lake or sea4 ,if the same fluid has not reached the surface1 but has been merely injected into fissures below ground1 it is called trap4 ,there is every variety of composition in lavas2 some are trachytic1 as in the ,peak of ,teneriffe2 a great number are basaltic1 as in ,vesuvius and ,auvergne2 others are andesitic1 as those of ,chili2 some of the most modern in ,vesuvius consist of green augite1 and many of those of ,etna of augite and ,labrador-felspar4#cgd-;,a ,trap tuff1 volcanic tuff4--,small angular fragments of the scoriae and pumice1 above mentioned1 and the dust of the same1 produced by volcanic explosions1 form the tuffs which abound in all regions of active volcanos1 where showers of these materials1 together with small pieces of other rocks ejected from the crater1 fall down upon the land or into the sea4 ,here they often become mingled with shells1 and are stratified4 ,such tuffs are sometimes bound together by a calcareous cement1 and form a stone susceptible of a beautiful polish4 ,but even when little or no lime is present1 there is a great tendency in the materials of ordinary tuffs to cohere together4 ,besides the peculiarity of their composition1 some tuffs1 or volcanic grits1 as they have been termed1 differ from ordinary sandstones by the angularity of their grains4 ,when the fragments are coarse1 the rock is styled a volcanic breccia4 ,tufaceous conglomerates result from the intermixture of rolled fragments or pebbles of volcanic and other rocks with tuff4 ,according to ,mr4 ,scrope1 the ,italian geologists confine the term tuff1 or tufa1 to felspathose mixtures1 and those composed principally of pumice1 using the term peperino for the basaltic tuffs4#cgd-;,b ,the peperinos thus distinguished are usually brown1 and the tuffs grey or white4 ,we meet occasionally with extremely compact beds of volcanic materials1 interstratified with fossiliferous rocks4 ,these may sometimes be tuffs1 although their density or compactness is such as to cause them to resemble many of those kinds of trap which are found in ordinary dikes4 ,the chocolate-coloured mud1 which was poured for weeks out of the crater of ,graham's ,island1 in the ,mediterranean1 in #ahca1 must1 when unmixed with other materials1 have constituted a stone heavier than granite4 ,each cubic inch of the impalpable powder which has fallen for days through the atmosphere1 during some modern eruptions1 has been found to weigh1 without being compressed1 as much as ordinary trap rocks1 and to be often identical with these in mineral composition4 ,the fusibility of the igneous rocks generally exceeds that of other rocks1 for there is much alkaline matter and lime in their composition1 which serves as a flux to the large quantity of silica1 which would be otherwise so refractory an ingredient4 ,it is remarkable that1 notwithstanding the abundance of this silica1 quartz1 that is1 crystalline silica1 is usually wanting in the volcanic rocks1 or is present only as an occasional mineral1 like mica4 ,the elements of mica1 as of quartz1 occur in lava and trap2 but the circumstances under which these rocks are formed are evidently unfavourable to the development of mica and quartz1 minerals so characteristic of the hypogene formations4 ,it would be tedious to enumerate all the varieties of trap and lava which have been regarded by different observers as sufficiently abundant to deserve distinct names1 especially as each investigator is too apt to exaggerate the importance of local varieties which happen to prevail in districts best known to him4 ,it will be useful1 however1 to subjoin here1 in the form of a glossary1 an alphabetical list of the names and synonyms most commonly in use1 with brief explanations1 to which ,i have added a table of the analysis of the simple minerals most abundant in the volcanic and hypogene rocks4 ,explanation of the names1 synonyms1 and mineral composition of the more abundant volcanic rocks4 ,,amphibolite4 ,see ,hornblende rock1 amphibole being ,hauey's name for hornblende4 ,,amygdaloid4 ,a particular form of volcanic rock2 see p4 #cgb4 ,,augite ,,rock4 ,a kind of basalt or greenstone1 composed wholly or principally of granular augite4 7,leonhard's ,mineralreich1 #b;d edition1 p4 #he47 ,,augitic-,,porphyry4 ,crystals of ,labrador-felspar and of augite1 in a green or dark grey base4 7,rose1 ,ann4 des ,mines1 tom4 #h4 p4 #bb4 #ahce47 ,,basalt4 ,chiefly augite--an intimate mixture of augite and felspar with magnetic iron1 olivine1 c4 ,see p4 #cga4 ,the yellowish green mineral called olivine1 can easily be distinguished from yellowish felspar by its infusibility1 and having no cleavage4 ,the edges turn brown in the flame of the blow-pipe4 ,,basanite4 ,name given by ,alex4 ,brongniart to a rock1 having a base of basalt1 with more or less distinct crystals of augite disseminated through it4 ,,claystone and ,,claystone-,,porphyry4 ,an earthy and compact stone1 usually of a purplish colour1 like an indurated clay2 passes into hornstone2 generally contains scattered crystals of felspar and sometimes of quartz4 ,,clinkstone4 ,syn4 ,phonolite1 fissile ,petrosilex2 a greenish or greyish rock1 having a tendency to divide into slabs and columns2 hard1 with clean fracture1 ringing under the hammer2 principally composed of compact felspar1 and1 according to ,gmelin1 of felspar and mesotype4 7,leonhard1 ,mineralreich1 p4 #ajb47 ,a rock much resembling clinkstone1 and called by some ,petrosilex1 contains a considerable percentage of quartz and felspar4 ,as both trachyte and basalt pass into clinkstone1 the rock so called must be very various in composition4 ,,compact ,,felspar1 which has also been called ,petrosilex2 the rock so called includes the hornstone of some mineralogists1 is allied to clinkstone1 but is harder1 more compact1 and translucent4 ,it is a varying rock1 of which the chemical composition is not well defined1 and is perhaps the same as that of clay4 7,mac,culloch's ,classification of ,rocks1 p4 #dha47 ,dr4 ,mac,culloch says1 that it contains both potash and soda4 ,,cornean4 ,a variety of claystone allied to hornstone4 ,a fine homogeneous paste1 supposed to consist of an aggregate of felspar1 quartz1 and hornblende1 with occasionally epidote1 and perhaps chlorite2 it passes into compact felspar and hornstone4 7,de la ,beche1 ,geol4 ,trans4 second series1 vol4 #b4 p4 #c47 ,,diallage ,,rock4 ,syn4 ,euphotide1 ,gabbro1 and some ,ophiolites4 ,compounded of felspar and diallage1 sometimes with the addition of serpentine1 or mica1 or quartz4 7,mac,culloch4 ibid4 p4 #fdh47 ,,diorite4 ,a kind of greenstone1 which see4 ,components1 felspar and hornblende in grains4 ,according to ,rose1 ,ann4 des ,mines1 tom4 #h4 p4 #d41 diorite consists of albite and hornblende4 ,,dioritic-,,porphyry4 ,a porphyritic greenstone1 composed of crystals of albite and hornblende1 in a greenish or blackish base4 7,rose1 ibid4 p4 #aj47 ,,dolerite4 ,formerly defined as a synonym of greenstone1 which see4 ,but1 according to ,rose 7ibid4 p4 #cb471 its composition is black augite and ,labrador-felspar2 according to ,leonhard 7,mineralreich1 c4 p4 #gg471 augite1 ,labrador-felspar1 and magnetic iron4 ,,domite4 ,an earthy trachyte1 found in the ,puy de ,dome1 in ,auvergne4 ,,euphotide4 ,a mixture of grains of ,labrador-felspar and diallage4 7,rose1 ibid4 p4 #ai47 ,according to some1 this rock is defined to be a mixture of augite or hornblende1 and saussurite1 a mineral allied to jade4 7,allan's ,mineralogy1 p4 #aeh47 ,see ,diallage rock4 ,,felspar-,,porphyry4 ,syn4 ,hornstone-porphyry2 a base of felspar1 with crystals of felspar1 and crystals and grains of quartz4 ,see also ,hornstone4 ,,gabbro1 see ,diallage rock4 ,,greenstone4 ,syn4 ,dolerite and diorite2 components1 hornblende and felspar1 or augite and felspar in grains4 ,see above1 p4 #cgb4 ,,greystone4 7,graustein of ,werner47 ,lead grey and greenish rock1 composed of felspar and augite1 the felspar being more than seventy-five per cent4 7,scrope1 ,journ4 of ,sci4 ,no4 #db4 p4 #bba47 ,greystone lavas are intermediate in composition between basaltic and trachytic lavas4 ,,hornblende ,,rock4 ,a greenstone1 composed principally of granular hornblende1 or augite4 7,leonhard1 ,mineralreich1 c41 p4 #he47 ,,hornstone1 ,,hornstone-,,porphyry4 ,a kind of felspar porphyry 7,leonhard1 ibid471 with a base of hornstone1 a mineral approaching near to flint1 differing from compact felspar in being infusible4 ,,hypersthene ,,rock1 a mixture of grains of ,labrador-felspar and hypersthene 7,rose1 ,ann4 des ,mines1 tom4 #h4 p4 #ac471 having the structure of syenite or granite2 abundant among the traps of ,skye4 ,some geologists consider it a greenstone1 in which hypersthene replaces hornblende4 ,,laterite4 ,a red jaspery rock1 composed of silicate of alumina and oxide of iron4 ,abundant in the ,deccan1 in ,india2 and referred to the trap formation2 from ,later1 a brick or tile4 ,,melaphyre4 ,a variety of black porphyry1 the base being black augite with crystals of felspar2 from melas1 melas1 black4 ,,obsidian4 ,vitreous lava like melted glass1 nearly allied to pitchstone4 ,,ophiolite1 sometimes same as ,diallage rocks 7,leonhard1 p4 #gg472 sometimes a kind of serpentine4 ,,ophite4 ,a green porphyritic rock composed chiefly of hornblende1 with crystals of that mineral in a base of the same1 mixed with some felspar4 ,it passes into serpentine by a mixture of talc4 7,burat's d',aubuisson1 tom4 ii4 p4 #fc47 ,,pearlstone4 ,a volcanic rock1 having the lustre of mother of pearl2 usually having a nodular structure2 intimately related to obsidian1 but less glassy4 ,,peperino4 ,a form of volcanic tuff1 composed of basaltic scoriae4 ,see p4 #cgd4 ,,petrosilex4 ,see ,clinkstone and ,compact ,felspar4 ,,phonolite4 ,syn4 of ,clinkstone1 which see4 ,,pitchstone4 ,vitreous lava1 less glassy than obsidian2 a blackish green rock resembling glass1 having a resinous lustre and appearance of pitch2 composition various1 usually felspar and augite2 passes into basalt2 occurs in veins1 and in ,arran forms a dike thirty feet wide1 cutting through sandstone2 forms the outer walls of some basaltic dikes4 ,,porphyry4 ,any rock in which detached crystals of felspar1 or of one or more minerals1 are diffused through a base4 ,see p4 #cgb4 ,,pozzolana4 ,a kind of tuff4 ,see p4 #cf4 ,,pumice4 ,a light1 spongy1 fibrous form of trachyte4 ,see p4 #cgc4 ,,pyroxenic-,,porphyry1 same as augitic-porphyry1 pyroxene being ,hauey's name for augite4 ,,scoriae4 ,syn4 volcanic cinders2 reddish brown or black porous form of lava4 ,see p4 #cgc4 ,,serpentine4 ,a greenish rock1 in which there is much magnesia2 usually contains diallage1 which is nearly allied to the simple mineral called serpentine4 ,occurs sometimes1 though rarely1 in dikes1 altering the contiguous strata2 is indifferently a member of the trappean or hypogene series4 ,,syenitic-,,greenstone2 composition1 crystals or grains of felspar and hornblende4 ,see p4 #cgb4 ,,tephrine1 synonymous with lava4 ,name proposed by ,alex4 ,brongniart4 ,,toadstone4 ,a local name in ,derbyshire for a kind of wacke1 which see4 ,,trachyte4 ,chiefly composed of glassy felspar1 with crystals of glassy felspar4 ,see p4 #cgb4 ,,trap ,,tuff4 ,see p4 #cgd4 ,,trass4 ,a kind of tuff or mud poured out by lake craters during eruptions2 common in the ,eifel1 in ,germany4 ,,tufaceous ,,conglomerate4 ,see p4 #cgd4 ,,tuff4 ,syn4 ,trap-tuff1 volcanic tuff4 ,see p4 #cgd4 ,,vitreous ,,lava4 ,see ,pitchstone and ,obsidian4 ,,volcanic ,,tuff4 ,see p4 #cgd4 ,,wacke4 ,a soft and earthy variety of trap1 having an argillaceous aspect4 ,it resembles indurated clay1 and when scratched exhibits a shining streak4 ,,whinstone4 ,a ,scotch provincial term for greenstone and other hard trap rocks4 ,,analysis ,,of ,,minerals ,,most ,,abundant ,,in ,,the ,,volcanic ,,and ,,hypogene ,,rocks4 ,silica4 ,alu- ,mag- ,lime4 ,pot- ,soda4 ,iron4 ,manga- ,remain- mina4 nesia4 ash4 ,oxide4 nese4 der4 ,actinolite #fd4 -- #bb4 -- -- -- #c4 a #dc4je ,c4 7,bergman7 trace ,albite 7,rose7 #fh4hd #bj4ec -- a trace -- #i4ab -- -- -- --7mean of #d #fi4de #ai4dd #j4ac #j4bb -- #i4ie a -- -- analyses7 trace ,augite 7,rose7 #ec4cf -- #d4ii #bb4ai -- -- #ag4ch #j4ji -- --7mean of #d #ec4eg #a4 #aa4bf #bj4i -- -- #aj4ge #j4fg -- analyses7 ,carbonate of -- -- -- #ef4cc -- -- -- -- -- ,lime 7,biot7 ,chiastolite #fh4di #cj4ag #d4ab -- -- -- #b4g -- #j4bg ,w4 7,landgrabe7 ,chlorite #bf4 #ah4e #h4 -- -- #b4 #dc4 -- -- 7,vauquelin7 --7mean of #c #bg4dc #ag4i #ad4ef #j4ej #a4ef -- #cj4fc -- #f4ib ,w4 analyses7 ,diallage #fj4 -- #bg4e -- -- -- #aj4e -- -- 7,klaproth7 --7mean of #c #dc4cc #b4b #bf4da #e4eh -- -- #aa4ec -- #h4ed ,w4 analyses7 ,epidote #cg4 #ba4 -- #ae4 -- -- #bd4 #a4e -- 7,vauquelin7 ,felspar1 #fb4hc #ag4jb -- #c4 - #ac4 -- #a4 -- -- common 7,vauq47 --7,rose7 #ff4ge #ag4e -- #a4be #ab4 -- #j4ge -- -- --7mean of #g #fd4jd #ah4id -- #j4gf #ac4ff -- #j4gd -- -- analyses7 ,garnet #ce4ge #bg4be -- -- -- -- #cf4 #j4be -- 7,klaproth7 --7,phillips7 #dc4 #af4 -- #bj4 -- -- #af4 -- -- ,hornblende #db4 #ab4 #b4be #aa4 a -- #cj4 #j4be -- 7,klap47 trace --7,bonsdorff47 #de4fi #ab4ah #ah4gi #ac4he -- -- #g4cb #j4bb #a4e ,f4 ,hypersthene #ed4be #b4be #ad4 #a4e -- -- #bd4e a #a4 ,w4 7,klaproth7 trace ,labrador- #ee4ge #bf4e -- #aa4 -- #d4 #a4be -- #j4e ,w4 felspar 7,klap47 ,leucite #ec4ge #bd4fb -- -- #ba4ce -- -- -- -- 7,klap47 ,mesotype #ed4fd #ai4gj -- #a4fa -- #ae4ji -- -- #i4hc ,w4 7,gehlen7 ,mica #db4e #aa4e #i4 -- #aj4 -- #bb4 #b4 -- 7,klaproth7 --7,vauquelin7 #ej4 #ce4 -- #a4cc -- -- #g4 -- -- --7mean of #c #de4hc #bb4eh -- -- #aa4jh -- #ad4 #a4de -- analyses7 ,olivine #ej4 -- #ch4e -- -- -- #ab4 -- -- 7,klaproth7 ,schorl or #ce4dh #cd4ge #d4fh -- #j4dh #a4ge #ag4dd #a4hi #d4jb ,b4 ,tourmaline 7,gmelin7 --7mean of #f #cf4jc #ce4hb #d4dd #j4bh #j4ga #a4if #ac4ga #a4fb -- analyses7 ,serpentine #dc4jg #j4be #dj4cg #j4e -- -- #a4ag -- #ab4de ,w4 7,hisinger7 --7mean of #e #cg4bi #d4ig #cf4h #b4hi -- -- #c4ad -- #ab4gg ,w4 analyses7 ,steatite #fd4 -- #bb4 -- -- -- #c4 -- #e4 ,w4 7,vauquelin7 --7mean of #c #dh4c #f4ah #bf4fe -- -- -- #b4 -- #i4e ,w4 anal4 by ,klap47 ,talc4 #fa4ge -- #cj4e -- #b4ge -- #b4e -- -- 7,klaproth7 ,in the last column of the above ,table1 the letters ,b4 ,c4 ,f4 ,w4 represent ,boracic acid1 ,carbonic acid1 ,fluoric acid1 and ,water4 ,,footnotes3 #cfh-;,a ,for a description and theory of active volcanos1 see ,principles of ,geology1 chaps4 xxiv4 to xxvii4 #cgd-;,a ,g4 ,rose1 ,ann4 des ,mines1 tom4 viii4 p4 #cb4 #cgd-;,b ,geol4 ,trans4 vol4 ii4 p4 #baa4 #b;d series4 ,,chapter ,,xxix4 ,,volcanic ,,rocks--continued4 ,trap dikes--sometimes project--sometimes leave fissures vacant by decomposition--,branches and veins of trap--,dikes more crystalline in the centre--,foreign fragments of rock imbedded--,strata altered at or near the contact--,obliteration of organic remains--,conversion of chalk into marble--and of coal into coke--,inequality in the modifying influence of dikes--,trap interposed between strata--,columnar and globular structure--,relation of trappean rocks to the products of active volcanos--,submarine lava and ejected matter corresponds generally to ancient trap--,structure and physical features of ,palma and some other extinct volcanos4 ,having in the last chapter spoken of the composition and mineral characters of volcanic rocks1 ,i shall next describe the manner and position in which they occur in the earth's crust1 and their external forms4 ,now the leading varieties1 such as basalt1 greenstone1 trachyte1 porphyry1 and the rest1 are found sometimes in dikes penetrating stratified and unstratified formations1 sometimes in shapeless masses protruding through or overlying them1 or in horizontal sheets intercalated between strata4 ,volcanic dikes4--,fissures have already been spoken of as occurring in all kinds of rocks1 some a few feet1 others many yards in width1 and often filled up with earth or angular pieces of stone1 or with sand and pebbles4 ,instead of such materials1 suppose a quantity of melted stone to be driven or injected into an open rent1 and there consolidated1 we have then a tabular mass resembling a wall1 and called a trap dike4 ,it is not uncommon to find such dikes passing through strata of soft materials1 such as tuff or shale1 which1 being more perishable than the trap1 are often washed away by the sea1 rivers1 or rain1 in which case the dike stands prominently out in the face of precipices1 or on the level surface of a country4 7,see the annexed figure4#cgh-;,a7 ,illustration3 ,fig4 #dci4 ,dike in inland valley1 near the ,brazen ,head1 ,madeira4 ,in the islands of ,arran1 ,skye1 and other parts of ,scotland1 where sandstone1 conglomerate1 and other hard rocks are traversed by dikes of trap1 the converse of the above phenomenon is seen4 ,the dike having decomposed more rapidly than the containing rock1 has once more left open the original fissure1 often for a distance of many yards inland from the sea-coast1 as represented in the annexed view 7fig4 #ddj474 ,in these instances1 the greenstone of the dike is usually more tough and hard than the sandstone2 but chemical action1 and chiefly the oxidation of the iron1 has given rise to the more rapid decay4 ,illustration3 ,fig4 #ddj4 ,fissures left vacant by decomposed trap4 ,strathaird1 ,skye4 7,mac,culloch47 ,there is yet another case1 by no means uncommon in ,arran and other parts of ,scotland1 where the strata in contact with the dike1 and for a certain distance from it1 have been hardened1 so as to resist the action of the weather more than the dike itself1 or the surrounding rocks4 ,when this happens1 two parallel walls of indurated strata are seen protruding above the general level of the country1 and following the course of the dike4 ,illustration3 ,fig4 #dda4 ,trap veins in ,airdnamurchan4 ,as fissures sometimes send off branches1 or divide into two or more fissures of equal size1 so also we find trap dikes bifurcating and ramifying1 and sometimes they are so tortuous as to be called veins1 though this is more common in granite than in trap4 ,the accompanying sketch 7fig4 #dda47 by ,dr4 ,mac,culloch represents part of a sea-cliff in ,argyleshire1 where an overlying mass of trap1 b1 sends out some veins which terminate downwards4 ,another trap vein1 a a1 cuts through both the limestone1 c1 and the trap1 b4 ,in fig4 #ddb41 a ground plan is given of a ramifying dike of greenstone1 which ,i observed cutting through sandstone on the beach near ,kildonan ,castle1 in ,arran4 ,the larger branch varies from #e to #g feet in width1 which will afford a scale of measurement for the whole4 ,illustration3 ,fig4 #ddb4 ,ground plan of greenstone dike traversing sandstone4 ,arran4 ,in the ,hebrides and other countries1 the same masses of trap which occupy the surface of the country far and wide1 concealing the subjacent stratified rocks1 are seen also in the sea cliffs1 prolonged downwards in veins or dikes1 which probably unite with other masses of igneous rock at a greater depth4 ,the largest of the dikes represented in the annexed diagram1 and which are seen in part of the coast of ,skye1 is no less than #ajj feet in width4 ,illustration3 ,fig4 #ddc4 ,trap dividing and covering sandstone near ,suishnish in ,skye4 7,mac,culloch47 ,every variety of trap-rock is sometimes found in these dikes1 as basalt1 greenstone1 felspar-porphyry1 and more rarely trachyte4 ,the amygdaloidal traps also occur1 and even tuff and breccia1 for the materials of these last may be washed down into open fissures at the bottom of the sea1 or during eruptions on the land may be showered into them from the air4 ,some dikes of trap may be followed for leagues uninterruptedly in nearly a straight direction1 as in the north of ,england1 showing that the fissures which they fill must have been of extraordinary length4 ,dikes more crystalline in the centre4--,in many cases trap at the edges or sides of a dike is less crystalline or more earthy than in the centre1 in consequence of the melted matter having cooled more rapidly by coming in contact with the cold sides of the fissure2 whereas1 in the centre1 the matter of the dike being kept long in a fluid or soft state1 the crystals are slowly formed4 ,in the ancient part of ,vesuvius1 called ,somma1 a thin band of half-vitreous lava is found at the edge of some dikes4 ,at the junction of greenstone dikes with limestone1 a sahlband1 or selvage1 of serpentine is occasionally observed4 ,illustration3 ,fig4 #ddd4 ,syenitic greenstone dike of ,naesodden1 ,christiania4 b4 imbedded fragment of crystalline schist surrounded by a band of greenstone4 ,on the left shore of the fiord of ,christiania1 in ,norway1 ,i examined1 in company with ,professor ,keilhau1 a remarkable dike of syenitic greenstone1 which is traced through ,silurian strata1 until at length1 in the promontory of ,naesodden1 it enters mica-schist4 ,fig4 #ddd4 represents a ground plan1 where the dike appears #h paces in width4 ,in the middle it is highly crystalline and granitiform1 of a purplish colour1 and containing a few crystals of mica1 and strongly contrasted with the whitish mica-schist1 between which and the syenitic rock there is usually on each side a distinct black band1 #ah inches wide1 of dark greenstone4 ,when first seen1 these bands have the appearance of two accompanying dikes2 yet they are1 in fact1 only the different form which the syenitic materials have assumed where near to or in contact with the mica-schist4 ,at one point1 a1 one of the sahlbands terminates for a space2 but near this there is a large detached block1 b1 having a gneiss-like structure1 consisting of hornblende and felspar1 which is included in the midst of the dike4 ,round this a smaller encircling zone is seen1 of dark basalt1 or fine-grained greenstone1 nearly corresponding to the larger ones which border the dike1 but only #a inch wide4 ,it seems1 therefore1 evident that the fragment1 b1 has acted on the matter of the dike1 probably by causing it to cool more rapidly1 in the same manner as the walls of the fissure have acted on a larger scale4 ,the facts1 also1 illustrate the facility with which a granitiform syenite may pass into ordinary rocks of the volcanic family4 ,illustration3 ,fig4 #dde4 ,greenstone dike1 with fragments of gneiss4 ,sorgenfri1 ,christiania4 ,the fact above alluded to1 of a foreign fragment1 such as b1 fig4 #ddd41 included in the midst of the trap1 as if torn off from some subjacent rock or the walls of a fissure1 is by no means uncommon4 ,a fine example is seen in another dike of greenstone1 #aj feet wide1 in the northern suburbs of ,christiania1 in ,norway1 of which the annexed figure is a ground plan4 ,the dike passes through shale1 known by its fossils to belong to the ,silurian series4 ,in the black base of greenstone are angular and roundish pieces of gneiss1 some white1 others of a light flesh-colour1 some without lamination1 like granite1 others with laminae1 which1 by their various and often opposite directions1 show that they have been scattered at random through the matrix4 ,these imbedded pieces of gneiss measure from #a to about #h inches in diameter4 ,rocks altered by volcanic dikes4--,after these remarks on the form and composition of dikes themselves1 ,i shall describe the alterations which they sometimes produce in the rocks in contact with them4 ,the changes are usually such as the intense heat of melted matter and the entangled gases might be expected to cause4 ,plas-,newydd4--,a striking example1 near ,plas-,newydd1 in ,anglesea1 has been described by ,professor ,henslow4#cha-;,a ,the dike is #acd feet wide1 and consists of a rock which is a compound of felspar and augite 7dolerite of some authors74 ,strata of shale and argillaceous limestone1 through which it cuts perpendicularly1 are altered to a distance of #cj1 or even1 in some places1 to #ce feet from the edge of the dike4 ,the shale1 as it approaches the trap1 becomes gradually more compact1 and is most indurated where nearest the junction4 ,here it loses part of its schistose structure1 but the separation into parallel layers is still discernible4 ,in several places the shale is converted into hard porcellanous jasper4 ,in the most hardened part of the mass the fossil shells1 principally ,producti1 are nearly obliterated2 yet even here their impressions may frequently be traced4 ,the argillaceous limestone undergoes analogous mutations1 losing its earthy texture as it approaches the dike1 and becoming granular and crystalline4 ,but the most extraordinary phenomenon is the appearance in the shale of numerous crystals of analcime and garnet1 which are distinctly confined to those portions of the rock affected by the dike4#chb-;,a ,some garnets contain as much as #bj per cent4 of lime1 which they may have derived from the decomposition of the fossil shells or ,producti4 ,the same mineral has been observed1 under very analogous circumstances1 in ,high ,teesdale1 by ,professor ,sedgwick1 where it also occurs in shale and limestone1 altered by basalt4#chb-;,b ,antrim4--,in several parts of the county of ,antrim1 in the north of ,ireland1 chalk with flints is traversed by basaltic dikes4 ,the chalk is there converted into granular marble near the basalt1 the change sometimes extending #h or #aj feet from the wall of the dike1 being greatest near the point of contact1 and thence gradually decreasing till it becomes evanescent4 ,the extreme effect1 says ,dr4 ,berger1 presents a dark brown crystalline limestone1 the crystals running in flakes as large as those of coarse primitive 7metamorphic7 limestone2 the next state is saccharine1 then fine grained and arenaceous2 a compact variety1 having a porcellanous aspect and a bluish-grey colour1 succeeds3 this1 towards the outer edge1 becomes yellowish-white1 and insensibly graduates into the unaltered chalk4 ,the flints in the altered chalk usually assume a grey yellowish colour4#chb-;,c ,all traces of organic remains are effaced in that part of the limestone which is most crystalline4 ,illustration3 ,fig4 #ddf4 ,basaltic dikes in chalk in island of ,rathlin1 ,antrim4 ,ground plan1 as seen on the beach4 7,conybeare and ,buckland4#chb-;,d7 ,the annexed drawing 7fig4 #ddf47 represents three basaltic dikes traversing the chalk1 all within the distance of #ij feet4 ,the chalk contiguous to the two outer dikes is converted into a finely granular marble1 m m1 as are the whole of the masses between the outer dikes and the central one4 ,the entire contrast in the composition and colour of the intrusive and invaded rocks1 in these cases1 renders the phenomena peculiarly clear and interesting4 ,another of the dikes of the north-east of ,ireland has converted a mass of red sandstone into hornstone4#chb-;,e ,by another1 the slate clay of the coal measures has been indurated1 and has assumed the character of flinty slate#chc-;,a2 and in another place the slate clay of the lias has been changed into flinty slate1 which still retains numerous impressions of ammonites4#chc-;,b ,it might have been anticipated that beds of coal would1 from their combustible nature1 be effected in an extraordinary degree by the contact of melted rock4 ,accordingly1 one of the greenstone dikes of ,antrim1 on passing through a bed of coal1 reduces it to a cinder for the space of #i feet on each side4#chc-;,c ,at ,cockfield ,fell1 in the north of ,england1 a similar change is observed4 ,specimens taken at the distance of about #cj yards from the trap are not distinguishable from ordinary pit coal2 those nearer the dike are like cinders1 and have all the character of coke2 while those close to it are converted into a substance resembling soot4#chc-;,d ,as examples might be multiplied without end1 ,i shall merely select one or two others1 and then conclude4 ,the rock of ,stirling ,castle is a calcareous sandstone1 fractured and forcibly displaced by a mass of greenstone which has evidently invaded the strata in a melted state4 ,the sandstone has been indurated1 and has assumed a texture approaching to hornstone near the junction4 ,in ,arthur's ,seat and ,salisbury ,craig1 near ,edinburgh1 a sandstone which comes in contact with greenstone is converted into a jaspideous rock4#chc-;,e ,the secondary sandstones in ,skye are converted into solid quartz in several places1 where they come in contact with veins or masses of trap2 and a bed of quartz1 says ,dr4 ,mac,culloch1 found near a mass of trap1 among the coal strata of ,fife1 was in all probability a stratum of ordinary sandstone1 having been subsequently indurated and turned into quartzite by the action of heat4#chc-;,f ,but although strata in the neighbourhood of dikes are thus altered in a variety of cases1 shale being turned into flinty slate or jasper1 limestone into crystalline marble1 sandstone into quartz1 coal into coke1 and the fossil remains of all such strata wholly and in part obliterated1 it is by no means uncommon to meet with the same rocks1 even in the same districts1 absolutely unchanged in the proximity of volcanic dikes4 ,this great inequality in the effects of the igneous rocks may often arise from an original difference in their temperature1 and in that of the entangled gases1 such as is ascertained to prevail in different lavas1 or in the same lava near its source and at a distance from it4 ,the power also of the invaded rocks to conduct heat may vary1 according to their composition1 structure1 and the fractures which they may have experienced1 and perhaps1 also1 according to the quantity of water 7so capable of being heated7 which they contain4 ,it must happen in some cases that the component materials are mixed in such proportions as prepare them readily to enter into chemical union1 and form new minerals2 while in other cases the mass may be more homogeneous1 or the proportions less adapted for such union4 ,we must also take into consideration1 that one fissure may be simply filled with lava1 which may begin to cool from the first2 whereas in other cases the fissure may give passage to a current of melted matter1 which may ascend for days or months1 feeding streams which are overflowing the country above1 or are ejected in the shape of scoriae from some crater4 ,if the walls of a rent1 moreover1 are heated by hot vapour before the lava rises1 as we know may happen on the flanks of a volcano1 the additional caloric supplied by the dike and its gases will act more powerfully4 ,illustration3 ,fig4 #ddg4 ,trap interposed between displaced beds of limestone and shale1 at ,white ,force1 ,high ,teesdale1 ,durham4 7,sedgwick4#chd-;,a7 ,intrusion of trap between strata4--,in proof of the mechanical force which the fluid trap has sometimes exerted on the rocks into which it has intruded itself1 ,i may refer to the ,whin-,sill1 where a mass of basalt1 from #fj to #hj feet in height1 represented by a1 fig4 #ddg41 is in part wedged in between the rocks of limestone1 b1 and shale1 c1 which have been separated from the great mass of limestone and shale1 d1 with which they were united4 ,the shale in this place is indurated2 and the limestone1 which at a distance from the trap is blue1 and contains fossil corals1 is here converted into granular marble without fossils4 ,masses of trap are not unfrequently met with intercalated between strata1 and maintaining their parallelism to the planes of stratification throughout large areas4 ,they must in some places have forced their way laterally between the divisions of the strata1 a direction in which there would be the least resistance to an advancing fluid1 if no vertical rents communicated with the surface1 and a powerful hydrostatic pressure was caused by gases propelling the lava upwards4 ,columnar and globular structure4--,one of the characteristic forms of volcanic rocks1 especially of basalt1 is the columnar1 where large masses are divided into regular prisms1 sometimes easily separable1 but in other cases adhering firmly together4 ,the columns vary in the number of angles1 from three to twelve2 but they have most commonly from five to seven sides4 ,they are often divided transversely1 at nearly equal distances1 like the joints in a vertebral column1 as in the ,giant's ,causeway1 in ,ireland4 ,they vary exceedingly in respect to length and diameter4 ,dr4 ,mac,culloch mentions some in ,skye which are about #djj feet long2 others1 in ,morven1 not exceeding an inch4 ,in regard to diameter1 those of ,ailsa measure #i feet1 and those of ,morven an inch or less4#che-;,a ,they are usually straight1 but sometimes curved2 and examples of both these occur in the island of ,staffa4 ,in a horizontal bed or sheet of trap the columns are vertical2 in a vertical dike they are horizontal4 ,among other examples of the last-mentioned phenomenon is the mass of basalt1 called the ,chimney1 in ,st4 ,helena 7see fig4 #ddh471 a pile of hexagonal prisms1 #fd feet high1 evidently the remainder of a narrow dike1 the walls of rock which the dike originally traversed having been removed down to the level of the sea4 ,in fig4 #ddi4 a small portion of this dike is represented on a less reduced scale4#che-;,b ,illustration3 ,fig4 #ddh4 ,volcanic dike composed of horizontal prisms4 ,st4 ,helena4 ,illustration3 ,fig4 #ddi4 ,small portion of the dyke in ,fig4 #ddh4 ,illustration3 ,fig4 #dej4 ,lava of ,la ,coupe d',ayzac1 near ,antraigue1 in the province of ,ardeche4 ,it being assumed that columnar trap has consolidated from a fluid state1 the prisms are said to be always at right angles to the cooling surfaces4 ,if these surfaces1 therefore1 instead of being either perpendicular1 or horizontal1 are curved1 the columns ought to be inclined at every angle to the horizon2 and there is a beautiful exemplification of this phenomenon in one of the valleys of the ,vivarais1 a mountainous district in the ,south of ,france1 where1 in the midst of a region of gneiss1 a geologist encounters unexpectedly several volcanic cones of loose sand and scoriae4 ,from the crater of one of these cones called ,la ,coupe d',ayzac1 a stream of lava descends and occupies the bottom of a narrow valley1 except at those points where the river ,volant1 or the torrents which join it1 have cut away portions of the solid lava4 ,the accompanying sketch 7fig4 #dej47 represents the remnant of the lava at one of the points where a lateral torrent joins the main valley of the ,volant4 ,it is clear that the lava once filled the whole valley up to the dotted line d a2 but the river has gradually swept away all below that line1 while the tributary torrent has laid open a transverse section2 by which we perceive1 in the first place1 that the lava is composed1 as usual in this country1 of three parts3 the uppermost1 at a1 being scoriaceous2 the second1 b1 presenting irregular prisms2 and the third1 c1 with regular columns1 which are vertical on the banks of the ,volant1 where they rest on a horizontal base of gneiss1 but which are inclined at an angle of #de deg4 at g1 and then horizontal at f1 their position having been every where determined1 according to the law before mentioned1 by the concave form of the original valley4 ,illustration3 ,fig #dea4 ,columnar basalt in the ,vicentin4 7,fortis47 ,in the annexed figure 7#dea47 a view is given of some of the inclined and curved columns which present themselves on the sides of the valleys in the hilly region north of ,vicenza1 in ,italy1 and at the foot of the higher ,alps4#chf-;,a ,unlike those of the ,vivarais1 last mentioned1 the basalt of this country was evidently submarine1 and the present valleys have since been hollowed out by denudation4 ,the columnar structure is by no means peculiar to the trap rocks in which hornblende or augite predominate2 it is also observed in clinkstone1 trachyte1 and other felspathic rocks of the igneous class1 although in these it is rarely exhibited in such regular polygonal forms4 ,illustration3 ,fig4 #deb4 ,basaltic pillars of the ,kaesegrotte1 ,bertrich-,baden1 half way between ,treves and ,coblentz4 ,height of grotto1 from #g to #h feet4 ,it has been already stated that basaltic columns are often divided by cross joints4 ,sometimes each segment1 instead of an angular1 assumes a spheroidal form1 so that a pillar is made up of a pile of balls1 usually flattened1 as in the ,cheese-grotto at ,bertrich-,baden1 in the ,eifel1 near the ,moselle 7fig4 #deb474 ,the basalt1 there1 is part of a small stream of lava1 from #cj to #dj feet thick1 which has proceeded from one of several volcanic craters1 still extant1 on the neighbouring heights4 ,the position of the lava bordering the river in this valley might be represented by a section like that already given at fig4 #dej4 p4 #che41 if we merely supposed inclined strata of slate and the argillaceous sandstone called greywacke to be substituted for gneiss4 ,in some masses of decomposing greenstone1 basalt1 and other trap rocks1 the globular structure is so conspicuous that the rock has the appearance of a heap of large cannon balls4 ,illustration3 ,fig4 #dec4 ,globiform pitchstone4 ,chiaja di ,luna1 ,isle of ,ponza4 7,scrope47 ,a striking example of this structure occurs in a resinous trachyte or pitchstone-porphyry in one of the ,ponza islands1 which rise from the ,mediterranean1 off the coast of ,terracina and ,gaeta4 ,the globes vary from a few inches to three feet in diameter1 and are of an ellipsoidal form 7see fig4 #dec474 ,the whole rock is in a state of decomposition1 and when the balls1 says ,mr4 ,scrope1 have been exposed a short time to the weather1 they scale off at a touch into numerous concentric coats1 like those of a bulbous root1 inclosing a compact nucleus4 ,the laminae of this nucleus have not been so much loosened by decomposition2 but the application of a ruder blow will produce a still further exfoliation4#chg-;,a ,a fissile texture is occasionally assumed by clinkstone and other trap rocks1 so that they have been used for roofing houses4 ,sometimes the prismatic and slaty structure is found in the same mass4 ,the causes which give rise to such arrangements are very obscure1 but are supposed to be connected with changes of temperature during the cooling of the mass1 as will be pointed out in the sequel4 7,see ,chaps4 ,,xxxv4 and ,,xxxvi47 ,relation of ,trappean ,rocks to the products of active ,volcanos4 ,when we reflect on the changes above described in the strata near their contact with trap dikes1 and consider how great is the analogy in composition and structure of the rocks called trappean and the lavas of active volcanos1 it seems difficult at first to understand how so much doubt could have prevailed for half a century as to whether trap was of igneous or aqueous origin4 ,to a certain extent1 however1 there was a real distinction between the trappean formations and those to which the term volcanic was almost exclusively confined4 ,the trappean rocks first studied in the north of ,germany1 and in ,norway1 ,france1 ,scotland1 and other countries1 were either such as had been formed entirely under deep water1 or had been injected into fissures and intruded between strata1 and which had never flowed out in the air1 or over the bottom of a shallow sea4 ,when these products1 therefore1 of submarine or subterranean igneous action were contrasted with loose cones of scoriae1 tuff1 and lava1 or with narrow streams of lava in great part scoriaceous and porous1 such as were observed to have proceeded from ,vesuvius and ,etna1 the resemblance seemed remote and equivocal4 ,it was1 in truth1 like comparing the roots of a tree with its leaves and branches1 which1 although they belong to the same plant1 differ in form1 texture1 colour1 mode of growth1 and position4 ,the external cone1 with its loose ashes and porous lava1 may be likened to the light foliage and branches1 and the rocks concealed far below1 to the roots4 ,but it is not enough to say of the volcano1 quantum vertice in auras ,a,etherias1 tantum radice in ,tartara tendit1 for its roots do literally reach downwards to ,tartarus1 or to the regions of subterranean fire2 and what is concealed far below1 is probably always more important in volume and extent than what is visible above ground4 ,illustration3 ,fig4 #ded4 ,strata intersected by a trap dike1 and covered with alluvium4 ,we have already stated how frequently dense masses of strata have been removed by denudation from wide areas 7see ,chap4 ,,vi472 and this fact prepares us to expect a similar destruction of whatever may once have formed the uppermost part of ancient submarine or subaerial volcanos1 more especially as those superficial parts are always of the lightest and most perishable materials4 ,the abrupt manner in which dikes of trap usually terminate at the surface 7see fig4 #ded471 and the water-worn pebbles of trap in the alluvium which covers the dike1 prove incontestably that whatever was uppermost in these formations has been swept away4 ,it is easy1 therefore1 to conceive that what is gone in regions of trap may have corresponded to what is now visible in active volcanos4 ,it will be seen in the following chapters1 that in the earth's crust there are volcanic tuffs of all ages1 containing marine shells1 which bear witness to eruptions at many successive geological periods4 ,these tuffs1 and the associated trappean rocks1 must not be compared to lava and scoriae which had cooled in the open air4 ,their counterparts must be sought in the products of modern submarine volcanic eruptions4 ,if it be objected that we have no opportunity of studying these last1 it may be answered1 that subterranean movements have caused1 almost everywhere in regions of active volcanos1 great changes in the relative level of land and sea1 in times comparatively modern1 so as to expose to view the effects of volcanic operations at the bottom of the sea4 ,thus1 for example1 the recent examination of the igneous rocks of ,sicily1 especially those of the ,val di ,noto1 has proved that all the more ordinary varieties of ,european trap have been there produced under the waters of the sea1 at a modern period2 that is to say1 since the ,mediterranean has been inhabited by a great proportion of the existing species of testacea4 ,these igneous rocks of the ,val di ,noto1 and the more ancient trappean rocks of ,scotland and other countries1 differ from subaerial volcanic formations in being more compact and heavy1 and in forming sometimes extensive sheets of matter intercalated between marine strata1 and sometimes stratified conglomerates1 of which the rounded pebbles are all trap4 ,they differ also in the absence of regular cones and craters1 and in the want of conformity of the lava to the lowest levels of existing valleys4 ,it is highly probable1 however1 that insular cones did exist in some parts of the ,val di ,noto3 and that they were removed by the waves1 in the same manner as the cone of ,graham island1 in the ,mediterranean1 was swept away in #ahca1 and that of ,nyoee1 off ,iceland1 in #aghc4chi-;,a ,all that would remain in such cases1 after the bed of the sea has been upheaved and laid dry1 would be dikes and shapeless masses of igneous rock1 cutting through sheets of lava which may have spread over the level bottom of the sea1 and strata of tuff1 formed of materials first scattered far and wide by the winds and waves1 and then deposited4 ,trap conglomerates also1 to which the action of the waves must give rise during the denudation of such volcanic islands1 will emerge from the deep whenever the bottom of the sea becomes land4 ,the proportion of volcanic matter which is originally submarine must always be very great1 as those volcanic vents which are not entirely beneath the sea1 are almost all of them in islands1 or1 if on continents1 near the shore4 ,this may explain why extended sheets of trap so often occur1 instead of narrow threads1 like lava streams4 ,for1 a multitude of causes tend1 near the land1 to reduce the bottom of the sea to a nearly uniform level1--the sediment of rivers1--materials transported by the waves and currents of the sea from wasting cliffs1--showers of sand and scoriae ejected by volcanos1 and scattered by the wind and waves4 ,when1 therefore1 lava is poured out on such a surface1 it will spread far and wide in every direction in a liquid sheet1 which may afterwards1 when raised up1 form the tabular capping of the land4 ,as to the absence of porosity in the trappean formations1 the appearances are in a great degree deceptive1 for all amygdaloids are1 as already explained1 porous rocks1 into the cells of which mineral matter1 such as silex1 carbonate of lime1 and other ingredients1 have been subsequently introduced 7see p4 #cgc472 sometimes1 perhaps1 by secretion during the cooling and consolidation of lavas4 ,in the ,little ,cumbray1 one of the ,western ,islands1 near ,arran1 the amygdaloid sometimes contains elongated cavities filled with brown spar2 and when the nodules have been washed out1 the interior of the cavities is glazed with the vitreous varnish so characteristic of the pores of slaggy lavas4 ,even in some parts of this rock which are excluded from air and water1 the cells are empty1 and seem to have always remained in this state1 and are therefore undistinguishable from some modern lavas4#cij-;,a ,dr4 ,mac,culloch1 after examining with great attention these and the other igneous rocks of ,scotland1 observes1 that it is a mere dispute about terms1 to refuse to the ancient eruptions of trap the name of submarine volcanos2 for they are such in every essential point1 although they no longer eject fire and smoke4#cij-;,b ,the same author also considers it not improbable that some of the volcanic rocks of the same country may have been poured out in the open air4#cij-;,c ,although the principal component minerals of subaerial lavas are the same as those of intrusive trap1 and both the columnar and globular structure are common to both1 there are1 nevertheless1 some volcanic rocks which never occur as lava1 such as greenstone1 clinkstone1 the more crystalline porphyries1 and those traps in which quartz and mica appear as constituent parts4 ,in short1 the intrusive trap rocks1 forming the intermediate step between lava and the plutonic rocks1 depart in their characters from lava in proportion as they approximate to granite4 ,these views respecting the relations of the volcanic and trap rocks will be better understood when the reader has studied1 in the #cc;d chapter1 what is said of the plutonic formations4 ,,form1 ,,structure1 ,,and ,,origin ,,of ,,volcanic ,,mountains4 ,the origin of volcanic cones with crater-shaped summits has been alluded to in the last chapter 7p4 #cfh471 and more fully explained in the ,principles of ,geology 7chaps4 xxiv4 to xxvii471 where ,vesuvius1 ,etna1 ,santorin1 and ,barren ,island were described4 ,the more ancient portions of those mountains or islands1 formed long before the times of history1 exhibit the same external features and internal structure which belong to most of the extinct volcanos of still higher antiquity4 ,the island of ,palma1 for example1 one of the ,canaries1 offers an excellent illustration of what1 in common with many others1 ,i regard as the ruins of a large dome-shaped mass formed by a series of eruptions proceeding from a crater at the summit1 this crater having been since replaced by a larger cavity1 the origin of which has afforded geologists an ample field for discussion and speculation4 ,illustration3 ,fig4 #dee4 ,view of the ,isle of ,palma1 and of the entrance into the central cavity or ,caldera4 ,from ,von ,buch's ,canary ,islands4 ,illustration3 ,fig4 #def4 ,map of the ,caldera of ,palma and the great ravine1 called ,barranco de las ,angustias4 ,from ,survey of ,capt4 ,vidal1 ,r4,n41 #ahcg4 ,von ,buch1 in his excellent account of the ,canaries1 has given us a graphic picture of this island1 which consists chiefly of a single mountain 7fig4 #dee474 ,this mountain has the general form of a great truncated cone1 with a huge and deep cavity in the middle1 about six miles in diameter1 called by the inhabitants the ,caldera1 or cauldron4 ,the range of precipices surrounding the ,caldera are no less than #djjj feet in their average height2 at one point1 where they are highest1 they are #ggcj feet above the level of the sea4 ,the external flanks of the cone incline gently in every direction towards the base of the island1 and are in part cultivated2 but the walls and bottom of the ,caldera present on all sides rugged and uncultivated rocks1 almost completely devoid of vegetation4 ,so steep are these walls1 that there is no part by which they can be descended1 and the only entrance is by a great ravine1 or ,barranco1 as it is called 7see b b'1 map1 fig4 #def471 which extends from the sea to the interior of the great cavity1 and by its jagged1 broken1 and precipitous sides1 exhibits to the geologist a transverse section of the rocks of which the whole mountain is composed4 ,by this means1 we learn that the cone is made up of a great number of sloping beds1 which dip outwards in every direction from the centre of the void space1 or from the hollow axis of the cone4 ,the beds consist chiefly of sheets of basalt1 alternating with conglomerates2 the materials of the latter being in part rounded1 as if rolled by water in motion4 ,the inclination of all the beds corresponds to that of the external slope of the island1 being greatest towards the ,caldera1 and least steep when they are nearest the sea4 ,there are a great number of tortuous veins1 and many dikes of lava or trap1 chiefly basaltic1 and most of them vertical1 which cut through the sloping beds laid open to view in the great gorge or ,barranco4 ,these dikes and veins are more and more abundant as we approach the ,caldera1 being therefore most numerous where the slope of the beds is greatest4 ,assuming the cone to be a pile of volcanic materials ejected by a long succession of eruptions 7a point on which all geologists are agreed71 we have to account for the ,caldera and the great ,barranco4 ,i conceive that the cone itself may be explained1 in accordance with what we know of the ordinary growth of volcanos#cib-;,a1 by supposing most of the eruptions to have taken place from one or more central vents1 at or near the summit of the cone1 before it was truncated4 ,from this culminating point1 sheets of lava flowed down one after the other1 and showers of ashes or ejected stones4 ,the volcano may1 in the earlier stages of its growth1 have been in great part submerged1 like ,stromboli1 in the sea2 and1 therefore1 some of the fragments of rock cast out of its crater may not only have been rolled by torrents sweeping down the mountain's side1 but have also been rounded by the waves of the sea1 as we see happen on the beach near ,catania1 on which the modern lavas of ,etna are broken up4 ,the increased number of dykes1 as we approach the axis of the cone1 agrees well with the hypothesis of the eruptions having been most frequent towards the centre4 ,there are three known causes or modes of operation1 which may have conduced towards the vast size of the ,caldera4 ,first1 the summit of a conical mountain may have fallen in1 as happened in the case of ,capacurcu1 one of the ,andes1 according to tradition1 in the year #adfb1 and of many other volcanic mountains4#cic-;,a ,sections seem wanting1 to supply us with all the data required for judging fairly of the tenability of this hypothesis4 ,it appears1 however1 from ,captain ,vidal's survey 7see fig4 #def471 that a hill of considerable height rises up from the bottom of the ,caldera1 the structure of which1 if it be any where laid open1 might doubtless throw much light on this subject4 ,secondly1 an original crater may have been enlarged by a vast gaseous explosion1 never followed by any subsequent eruption4 ,a serious objection to this theory arises from our not finding that the exterior of the cone supports a mass of ruins1 such as ought to cover it1 had so enormous a volume of matter1 partly made up of the solid contents of the dikes1 been blown out into the air4 ,in that case1 an extensive bed of angular fragments of stone1 and of fine dust1 might be looked for1 enveloping the entire exterior of the mountain up to the very rim of the ,caldera1 and ought nowhere to be intersected by a dike4 ,the absence of such a formation has induced ,von ,buch to suppose that the missing portion of the cone was engulphed4 ,it should1 however1 be remembered1 that in existing volcanos1 large craters1 two or three miles in diameter1 are sometimes formed by explosions1 or by the discharge of great volumes of steam4 ,there is yet another cause to which the extraordinary dimensions of the ,caldera may1 in part at least1 be owing2 namely1 aqueous denudation4 ,von ,buch has observed1 that the existence of a single deep ravine1 like the ,great ,barranco1 is a phenomenon common to many extinct volcanos1 as well as to some active ones4 ,now1 it will be seen by ,captain ,vidal's map 7fig4 #def4 p4 #cia471 that the sea-cliff at ,point ,juan ,graje1 #ghj feet high1 now constituting the coast at the entrance of the great ravine1 is continuous with an inland cliff which bounds the same ravine on its north-western side4 ,no one will dispute that the precipice1 at the base of which the waves are now beating1 owes its origin to the undermining power of the sea4 ,it is natural1 therefore1 to attribute the extension of the same cliff to the former action of the waves1 exerted at a time when the relative level of the island and the ocean were different from what they are now4 ,but if the waves and tides had power to remove the rocks once filling a great gorge which is #g miles long1 and1 in its upper part1 #bjjj feet deep1 can we doubt that the same power may have cleared out much of the solid mass now missing in the ,great ,caldera8 ,the theory advanced to account for the configuration of ,palma1 commonly called the elevation crater theory1 is this4 ,all the alternating masses of basalt and conglomerate1 intersected in the ,barranco1 or abruptly cut off in the escarpment or walls of the ,caldera1 were at first disposed in horizontal masses on the level floor of the ocean1 and traversed1 when in that position1 by all the basaltic dikes which now cut through them4 ,at length they were suddenly uplifted by the explosive force of elastic vapours1 which raised the mass bodily1 so as to tilt the beds on all sides away from the centre of elevation1 causing at the same time an opening at the culminating point4 ,besides many other objections which may be urged against this hypothesis1 it leaves unexplained the unbroken continuity of the rim of the ,caldera1 which is uninterrupted in all places save one#cid-;,a1 namely1 that where the great gorge or ,barranco occurs4 ,as a more natural way of explaining the phenomenon1 the following series of events may be imagined4 ,the principal vent1 from which a large part of the materials of the cone were poured or thrown out1 was left empty after the last escape of vapour1 when the volcano became extinct4 ,we learn from ,mr4 ,dana's valuable work on the geology of the ,united ,states' ,exploring ,expedition1 published in #ahdi1 that two of the principal volcanos of the ,sandwich ,islands1 ,mounts ,loa and ,kea in ,owyhee1 are huge flattened volcanic cones1 #ae1jjj feet high 7see fig4 #deg471 each equalling two and a half ,etnas in their dimensions4 ,illustration3 ,fig4 #deg4 ,mount ,loa1 in the ,sandwich ,islands4 7,dana7 a4 ,crater at the summit4 b4 ,the lateral crater of ,kilauea4 ,the dotted lines indicate a supposed column of solid rock caused by the lava consolidating after eruptions4 ,from the summits of these lofty though featureless hills1 and from vents not far below their summits1 successive streams of lava1 often #b miles or more in width1 and sometimes #bf miles long1 have flowed4 ,they have been poured out one after the other1 some of them in recent times1 in every direction from the apex of the cone1 down slopes varying on an average from #d degrees to #h degrees2 but at some places considerably steeper4#cid-;,b ,sometimes deep rents open on the sides of these cones1 which are filled by streams of lava passing over them1 the liquid matter in such cases probably uniting in the fissure with other lava melted in subterranean reservoirs below1 and thus explaining the origin of one great class of lateral dikes1 on ,etna1 ,palma1 and other cones4 ,if the flattened domes1 such as those here alluded to in the ,sandwich ,islands1 instead of being inland1 and above water1 were situated in mid-ocean1 like the ,island of ,st4 ,paul1 and for the most part submerged 7see figs4 #deh1 #dei1 #dfj471 and if a gradual upheaval of such a dome should then take place1 the denuding power of the sea could scarcely fail to play an important part in modifying the form of the volcanic mountain as it rose4 ,the crater will almost invariably have one side much lower than all the others1 namely1 that side towards which the prevailing winds never blow1 and to which1 therefore1 showers of dust and scoriae are rarely carried during eruptions4 ,there will also be one point on this windward or lowest side more depressed than all the rest1 by which the sea may enter as often as the tide rises1 or as often as the wind blows from that quarter4 ,for the same reason that the sea continues to keep open a single entrance into the lagoon of an atoll or annular coral reef1 it will not allow this passage into the crater to be stopped up1 but scour it out1 at low tide1 or as often as the wind changes4 ,the channel1 therefore1 will always be deepened in proportion as the island rises above the level of the sea1 at the rate perhaps of a few feet or yards in a century4 ,illustration3 ,fig4 #deh4 ,map of the ,island of ,st4 ,paul1 in the ,indian ,ocean1 lat4 #ch deg4 #dd' ,s41 long4 #gg deg4 #cg' ,e41 surveyed by ,capt4 ,blackwood1 ,r4,n41 #ahdb4 ,illustration3 ,fig4 #dei4 ,view of the ,crater of the ,island of ,st4 ,paul4 ,the island of ,st4 ,paul may perhaps be motionless2 but if1 like many other parts of the earth's crust1 it should begin to undergo a gradual upheaval1 or if1 as has happened to the shores of the ,bay of ,baiae1 its level should oscillate1 with a tendency upon the whole to increased elevation1 the same power which has cut away part of the cone1 and caused the cliffs now seen on the north-east side of the island1 would have power to undermine the walls of the crater1 and enlarge its diameter1 keeping open the channel1 by which it enters into it4 ,this ravine might be excavated to the depth of #ahj feet 7the present depth of the crater71 and its length might be extended to many miles according to the size of the submerged part of the cone4 ,the crater is only a mile in diameter1 and the surrounding cliffs1 where loftiest1 only #hjj feet high1 so that the size of this cone and crater is insignificant when compared to those in the ,sandwich ,islands1 and ,i have merely selected it because it affords an example of a class of insular volcanos1 into the craters of which the sea now enters by a single passage4 ,the crater of ,vesuvius in #ahbb was #bjjj feet deep2 and if it were a half submerged cone1 like ,st4 ,paul1 the excavating power of the ocean might in conjunction with gaseous explosions and co-operating with a gradual upheaving force1 give rise to a caldera on as grand a scale as that exhibited by ,palma4 ,illustration3 ,fig4 #dfj4 ,side view of the ,island of ,st4 ,paul 7,n4,e4 side74 ,nine-pin rocks two miles distant4 7,captain ,blackwood47 ,if1 after the geographical changes above supposed1 the volcanic fires long dormant should recover their energy1 they might1 as in the case of ,teneriffe1 ,vesuvius1 ,santorin1 and ,barren ,island1 discharge from the old central vent1 long sealed up at the bottom of the caldera1 new floods of lava and clouds of elastic vapours4 ,should this happen1 a new cone will be built up in the middle of the cavity or circular bay1 formed1 partly by explosion1 partly perhaps by engulphment1 and partly by aqueous denudation4 ,in the island of ,palma this last phase of volcanic activity has never occurred2 but the subterranean heat is still in full operation beneath the ,canary ,islands1 so that we know not what future changes it may be destined to undergo4 ,,footnotes3 #cgh-;,a ,i have been favoured with this drawing by ,captain ,b4 ,hall4 #cha-;,a ,cambridge ,transactions1 vol4 i4 p4 #djb4 #chb-;,a ,cambridge ,trans41 vol4 i4 p4 #daj4 #chb-;,b ,ibid4 vol4 ii4 p4 #age4 #chb-;,c ,dr4 ,berger1 ,geol4 ,trans41 #ast series1 vol4 iii4 p4 #agb4 #chb-;,d ,geol4 ,trans41 #ast series1 vol4 iii4 p4 #baj4 and plate #aj4 #chb-;,e ,ibid4 p4 #bja4 #chc-;,a ,geol4 ,trans41 #ast series1 vol4 iii4 p4 #bje4 #chc-;,b ,ibid4 p4 #bac42 and ,playfair1 ,illust4 of ,hutt4 ,theory1 p4 #bec4 #chc-;,c ,geol4 ,trans41 #ast series1 vol4 iii4 p4 #bjf4 #chc-;,d ,sedgwick1 ,camb4 ,trans4 vol4 ii4 p4 #cg4 #chc-;,e ,illust4 of ,hutt4 ,theory1 ,sec4 #bec4 and #bfa4 ,dr4 ,mac,culloch1 ,geol4 ,trans41 #ast series1 vol4 ii4 p4 #cje4 #chc-;,f ,syst4 of ,geol4 vol4 i4 p4 #bjf4 #chd-;,a ,camb4 ,trans4 vol4 ii4 p4 #ahj4 #che-;,a ,mac,cul4 ,syst4 of ,geol4 vol4 ii4 p4 #acg4 #che-;,b ,seale's ,geognosy of ,st4 ,helena1 plate #i4 #chf-;,a ,fortis4 ,mem4 sur l',hist4 ,nat4 de l',italie1 tom4 i4 p4 #bcc4 plate #g4 #chg-;,a ,scrope1 ,geol4 ,trans4 vol4 ii4 p4 #bje4 #b;d series4 #chi-;,a ,see ,princ4 of ,geol41 ,index1 ,graham ,island1 ,nyoee1 ,conglomerates1 volcanic1 c4 #cij-;,a ,mac,culloch1 ,west4 ,isl41 vol4 ii4 p4 #dhg4 #cij-;,b ,syst4 of ,geol41 vol4 ii4 p4 #aad4 #cij-;,c ,ibid4 #cib-;,a ,see ,principles1 chaps4 xxiv-xxvii4 #cic-;,a ,see ,principles1 chaps4 xxvi4 and xxx42 #hth ed4 p4 #cig-dge4 #cid-;,a ,see ,principles of ,geol4 ch4 xxiv4 7#hth ed4 p4 #cee474 #cid-;,b ,see ,lyell on ,craters of ,denudation1 ,quart4 ,geol4 ,journ4 vol4 vi4 p4 #bcb4 ,,chapter ,,xxx4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,volcanic ,,rocks4 ,tests of relative age of volcanic rocks--,test by superposition and intrusion--,dike of ,quarrington ,hill1 ,durham--,test by alteration of rocks in contact--,test by organic remains--,test of age by mineral character--,test by included fragments--,volcanic rocks of the ,post-,pliocene period--,basalt of ,bay of ,trezza in ,sicily--,post-,pliocene volcanic rocks near ,naples--,dikes of ,somma--,igneous formations of the ,newer ,pliocene period--,val di ,noto in ,sicily4 ,having referred the sedimentary strata to a long succession of geological periods1 we have next to consider how far the volcanic formations can be classed in a similar chronological order4 ,the tests of relative age in this class of rocks are four3--#ast1 superposition and intrusion1 with or without alteration of the rocks in contact2 #b;d1 organic remains2 #c;d1 mineral character2 #dth1 included fragments of older rocks4 ,illustration3 ,fig4 #dfa4 ,cross section4 ,tests by superposition1 c4--,if a volcanic rock rests upon an aqueous deposit1 the former must be the newest of the two1 but the like rule does not hold good where the aqueous formation rests upon the volcanic1 for melted matter1 rising from below1 may penetrate a sedimentary mass without reaching the surface1 or may be forced in conformably between two strata1 as b at ,d in the annexed figure 7fig4 #dfa471 after which it may cool down and consolidate4 ,superposition1 therefore1 is not of the same value as a test of age in the unstratified volcanic rocks as in fossiliferous formations4 ,we can only rely implicitly on this test where the volcanic rocks are contemporaneous1 not where they are intrusive4 ,now they are said to be contemporaneous if produced by volcanic action1 which was going on simultaneously with the deposition of the strata with which they are associated4 ,thus in the section at ,d 7fig4 #dfa471 we may perhaps ascertain that the trap b flowed over the fossiliferous bed c1 and that1 after its consolidation1 a was deposited upon it1 a and c both belonging to the same geological period4 ,but if the stratum a be altered by b at the point of contact1 we must then conclude the trap to have been intrusive1 or if1 in pursuing b for some distance1 we find at length that it cuts through the stratum a1 and then overlies it as at ,e4 ,we may1 however1 be easily deceived in supposing a volcanic rock to be intrusive1 when in reality it is contemporaneous2 for a sheet of lava1 as it spreads over the bottom of the sea1 cannot rest everywhere upon the same stratum1 either because these have been denuded1 or because1 if newly thrown down1 they thin out in certain places1 thus allowing the lava to cross their edges4 ,besides1 the heavy igneous fluid will often1 as it moves along1 cut a channel into beds of soft mud and sand4 ,suppose the submarine lava ,f to have come in contact in this manner with the strata a1 b1 c1 and that after its consolidation1 the strata d1 e1 are thrown down in a nearly horizontal position1 yet so as to lie unconformably to ,f1 the appearance of subsequent intrusion will here be complete1 although the trap is in fact contemporaneous4 ,we must not1 therefore1 hastily infer that the rock ,f is intrusive1 unless we find the strata d or e to have been altered at their junction1 as if by heat4 ,illustration3 ,fig4 #dfb4 ,cross section4 ,when trap dikes were described in the preceding chapter1 they were shown to be more modern than all the strata which they traverse4 ,a basaltic dike at ,quarrington ,hill1 near ,durham1 passes through coal-measures1 the strata of which are inclined1 and shifted so that those on the north side of the dike are #bd feet above the level of the corresponding beds on the south side 7see section1 fig4 #dfc474 ,but the horizontal beds of overlying ,red ,sandstone and ,magnesian ,limestone are not cut through by the dike4 ,now here the coal-measures were not only deposited1 but had subsequently been disturbed1 fissured1 and shifted1 before the fluid trap now forming the dike was introduced into a rent4 ,it is also clear that some of the upper edges of the coal strata1 together with the upper part of the dike1 had been subsequently removed by denudation before the lower ,new ,red ,sandstone and ,magnesian ,limestone were superimposed4 ,even in this case1 however1 although the date of the volcanic eruption is brought within narrow limits1 it cannot be defined with precision2 it may have happened either at the close of the ,carboniferous period1 or early in that of the ,lower ,new ,red ,sandstone1 or between these two periods1 when the state of the animate creation and the physical geography of ,europe were gradually changing from the type of the ,carboniferous era to that of the ,permian4 ,illustration3 ,fig4 #dfc4 ,section at ,quarrington ,hill1 east of ,durham4 7,sedgwick47 a4 ,magnesian ,limestone 7,permian74 b4 ,lower ,new ,red ,sandstone4 c4 ,coal strata4 ,the test of age by superposition is strictly applicable to all stratified volcanic tuffs1 according to the rules already explained in the case of other sedimentary deposits4 7,see p4 #if47 ,test of age by organic remains4--,we have seen how1 in the vicinity of active volcanos1 scoriae1 pumice1 fine sand1 and fragments of rock are thrown up into the air1 and then showered down upon the land1 or into neighbouring lakes or seas4 ,in the tuffs so formed shells1 corals1 or any other durable organic bodies which may happen to be strewed over the bottom of a lake or sea will be imbedded1 and thus continue as permanent memorials of the geological period when the volcanic eruption occurred4 ,tufaceous strata thus formed in the neighbourhood of ,vesuvius1 ,etna1 ,stromboli1 and other volcanos now active in islands or near the sea1 may give information of the relative age of these tuffs at some remote future period when the fires of these mountains are extinguished4 ,by such evidence we can distinctly establish the coincidence in age of volcanic rocks1 and the different primary1 secondary1 and tertiary fossiliferous strata already considered4 ,the tuffs now alluded to are not exclusively marine1 but include1 in some places1 freshwater shells2 in others1 the bones of terrestrial quadrupeds4 ,the diversity of organic remains in formations of this nature is perfectly intelligible1 if we reflect on the wide dispersion of ejected matter during late eruptions1 such as that of the volcano of ,coseguina1 in the province of ,nicaragua1 ,january #ai4 #ahce4 ,hot cinders and fine scoriae were then cast up to a vast height1 and covered the ground as they fell to the depth of more than #aj feet1 and for a distance of #h leagues from the crater in a southerly direction4 ,birds1 cattle1 and wild animals were scorched to death in great numbers1 and buried in these ashes4 ,some volcanic dust fell at ,chiapa1 upwards of #abjj miles to windward of the volcano1 a striking proof of a counter current in the upper region of the atmosphere2 and some on ,jamaica1 about #gjj miles distant to the north-east4 ,in the sea1 also1 at the distance of #aajj miles from the point of eruption1 ,captain ,eden of the ,conway sailed #dj miles through floating pumice1 among which were some pieces of considerable size4#cii-;,a ,test of age by mineral composition4--,as sediment of homogeneous composition1 when discharged from the mouth of a large river1 is often deposited simultaneously over a wide space1 so a particular kind of lava1 flowing from a crater during one eruption1 may spread over an extensive area2 as in ,iceland in #aghc1 when the melted matter1 pouring from ,skaptar ,jokul1 flowed in streams in opposite directions1 and caused a continuous mass1 the extreme points of which were #ij miles distant from each other4 ,this enormous current of lava varied in thickness from #ajj feet to #fjj feet1 and in breadth from that of a narrow river gorge to #ae miles4#cii-;,b ,now1 if such a mass should afterwards be divided into separate fragments by denudation1 we might still perhaps identify the detached portions by their similarity in mineral composition4 ,nevertheless1 this test will not always avail the geologist2 for1 although there is usually a prevailing character in lava emitted during the same eruption1 and even in the successive currents flowing from the same volcano1 still1 in many cases1 the different parts even of one lava-stream1 or1 as before stated1 of one continuous mass of trap1 vary so much in mineral composition and texture as to render these characters of minor importance when compared to their value in the chronology of the fossiliferous rocks4 ,it will1 however1 be seen in the description which follows1 of the ,european trap rocks of different ages1 that they had often a peculiar lithological character1 resembling the differences before remarked as existing between the modern lavas of ,vesuvius1 ,etna1 and ,chili4 7,see p4 #cgh47 ,it has been remarked that in ,auvergne1 the ,eifel1 and other countries where trachyte and basalt are both present1 the trachytic rocks are for the most part older than the basaltic4 ,these rocks do1 indeed1 sometimes alternate partially1 as in the volcano of ,mont ,dor1 in ,auvergne2 but the great mass of trachyte occupies in general an inferior position1 and is cut through and overflowed by basalt4 ,it can by no means be inferred that trachyte predominated greatly at one period of the earth's history and basalt at another1 for we know that trachytic lavas have been formed at many successive periods1 and are still emitted from many active craters2 but it seems that in each region1 where a long series of eruptions have occurred1 the more felspathic lavas have been first emitted1 and the escape of the more augitic kinds has followed4 ,the hypothesis suggested by ,mr4 ,scrope may1 perhaps1 afford a solution of this problem4 ,the minerals1 he observes1 which abound in basalt are of greater specific gravity than those composing the felspathic lavas2 thus1 for example1 hornblende1 augite1 and olivine are each more than three times the weight of water2 whereas common felspar1 albite1 and ,labrador felspar1 have each scarcely more than #b-a_/b times the specific gravity of water2 and the difference is increased in consequence of there being much more iron in a metallic state in basalt and greenstone than in trachyte and other felspathic lavas and traps4 ,if1 therefore1 a large quantity of rock be melted up in the bowels of the earth by volcanic heat1 the denser ingredients of the boiling fluid may sink to the bottom1 and the lighter remaining above would in that case be first propelled upwards to the surface by the expansive power of gases4 ,those materials1 therefore1 which occupied the lowest place in the subterranean reservoir will always be emitted last1 and take the uppermost place on the exterior of the earth's crust4 ,test by included fragments4--,we may sometimes discover the relative age of two trap rocks1 or of an aqueous deposit and the trap on which it rests1 by finding fragments of one included in the other1 in cases such as those before alluded to1 where the evidence of superposition alone would be insufficient4 ,it is also not uncommon to find conglomerates almost exclusively composed of rolled pebbles of trap1 associated with stratified rocks in the neighbourhood of masses of intrusive trap4 ,if the pebbles agree generally in mineral character with the latter1 we are then enabled to determine the age of the intrusive rock by knowing that of the fossiliferous strata associated with the conglomerate4 ,the origin of such conglomerates is explained by observing the shingle beaches composed of trap pebbles in modern volcanic islands1 or at the base of ,etna4 ,post-,pliocene ,period 7including the ,recent74--,i shall now select examples of contemporaneous volcanic rocks of successive geological periods1 to show that igneous causes have been in activity in all past ages of the world1 and that they have been ever shifting the places where they have broken out at the earth's surface4 ,one portion of the lavas1 tuffs1 and trap dikes of ,etna1 ,vesuvius1 and the ,island of ,ischia1 has been produced within the historical era2 another1 and a far more considerable part1 originated at times immediately antecedent1 when the waters of the ,mediterranean were already inhabited by the existing species of testacea4 ,the southern and eastern flanks of ,etna are skirted by a fringe of alternating sedimentary and volcanic deposits1 of submarine origin1 as at ,aderno1 ,trezza1 and other places4 ,of sixty-five species of fossil shells which ,i procured in #ahbh from this formation1 near ,trezza1 it was impossible to distinguish any from species now living in the neighbouring sea4 ,illustration3 ,fig4 #dfd4 ,view of the ,isle of ,cyclops in the ,bay of ,trezza4#dja-;,a ,the ,cyclopian ,islands1 called by the ,sicilians ,dei ,faraglioni1 in the sea cliffs of which these beds of clay1 tuff1 and associated lava are laid open to view1 are situated in the ,bay of ,trezza1 and may be regarded as the extremity of a promontory severed from the main land4 ,here numerous proofs are seen of submarine eruptions1 by which the argillaceous and sandy strata were invaded and cut through1 and tufaceous breccias formed4 ,inclosed in these breccias are many angular and hardened fragments of laminated clay in different states of alteration by heat1 and intermixed with volcanic sands4 ,the loftiest of the ,cyclopian islets1 or rather rocks1 is about #bjj feet in height1 the summit being formed of a mass of stratified clay1 the laminae of which are occasionally subdivided by thin arenaceous layers4 ,these strata dip to the ,n4,w41 and rest on a mass of columnar lava 7see fig4 #dfd47 in which the tops of the pillars are weathered1 and so rounded as to be often hemispherical4 ,in some places in the adjoining and largest islet of the group1 which lies to the north-eastward of that represented in the drawing 7fig4 #dfd471 the overlying clay has been greatly altered1 and hardened by the igneous rock1 and occasionally contorted in the most extraordinary manner2 yet the lamination has not been obliterated1 but1 on the contrary1 rendered much more conspicuous1 by the indurating process4 ,illustration3 ,fig4 #dfe4 ,contortions of strata in the largest of the ,cyclopian ,islands4 ,in the annexed woodcut 7fig4 #dfe47 ,i have represented a portion of the altered rock1 a few feet square1 where the alternating thin laminae of sand and clay have put on the appearance which we often observe in some of the most contorted of the metamorphic schists4 ,a great fissure1 running from east to west1 nearly divides this larger island into two parts1 and lays open its internal structure4 ,in the section thus exhibited1 a dike of lava is seen1 first cutting through an older mass of lava1 and then penetrating the superincumbent tertiary strata4 ,in one place the lava ramifies and terminates in thin veins1 from a few feet to a few inches in thickness4 7,see fig4 #dff47 ,the arenaceous laminae are much hardened at the point of contact1 and the clays are converted into siliceous schist4 ,in this island the altered rocks assume a honeycombed structure on their weathered surface1 singularly contrasted with the smooth and even outline which the same beds present in their usual soft and yielding state4 ,the pores of the lava are sometimes coated1 or entirely filled1 with carbonate of lime1 and with a zeolite resembling analcime1 which has been called cyclopite4 ,the latter mineral has also been found in small fissures traversing the altered marl1 showing that the same cause which introduced the minerals into the cavities of the lava1 whether we suppose sublimation or aqueous infiltration1 conveyed it also into the open rents of the contiguous sedimentary strata4 ,illustration3 ,fig4 #dff4 ,post-,pliocene strata invaded by lava1 ,isle of ,cyclops 7horizontal section74 a4 ,lava4 b4 ,laminated clay and sand4 c4 ,the same altered4 ,post-,pliocene formations near ,naples4--,i have traced in the ,principles of ,geology the history of the changes which the volcanic region of ,campania is known to have undergone during the last #bjjj years4 ,the aggregate effect of igneous operations during that period is far from insignificant1 comprising as it does the formation of the modern cone of ,vesuvius since the year #gi1 and the production of several minor cones in ,ischia1 together with that of ,monte ,nuovo in the year #aech4 ,lava-currents have also flowed upon the land and along the bottom of the sea--volcanic sand1 pumice1 and scoriae have been showered down so abundantly1 that whole cities were buried--tracts of the sea have been filled up or converted into shoals--and tufaceous sediment has been transported by rivers and land-floods to the sea4 ,there are also proofs1 during the same recent period1 of a permanent alteration of the relative levels of the land and sea in several places1 and of the same tract having1 near ,puzzuoli1 been alternately upheaved and depressed to the amount of more than #bj feet4 ,in connection with these convulsions1 there are found1 on the shores of the ,bay of ,baiae1 recent tufaceous strata1 filled with articles fabricated by the hands of man1 and mingled with marine shells4 ,it was also stated in this work 7p4 #aac471 that when we examine this same region1 it is found to consist largely of tufaceous strata1 of a date anterior to human history or tradition1 which are of such thickness as to constitute hills from #ejj to more than #bjjj feet in height4 ,these post-pliocene strata1 containing recent marine shells1 alternate with distinct currents and sheets of lava which were of contemporaneous origin2 and we find that in ,vesuvius itself1 the ancient cone called ,somma is of far greater volume than the modern cone1 and is intersected by a far greater number of dikes4 ,in contrasting this ancient part of the mountain with that of modern date1 one principal point of difference is observed2 namely1 the greater frequency in the older cone of fragments of altered sedimentary rocks ejected during eruptions4 ,we may easily conceive that the first explosions would act with the greatest violence1 rending and shattering whatever solid masses obstructed the escape of lava and the accompanying gases1 so that great heaps of ejected pieces of rock would naturally occur in the tufaceous breccias formed by the earliest eruptions4 ,but when a passage had once been opened1 and an habitual vent established1 the materials thrown out would consist of liquid lava1 which would take the form of sand and scoriae1 or of angular fragments of such solid lavas as may have choked up the vent4 ,among the fragments which abound in the tufaceous breccias of ,somma1 none are more common than a saccharoid dolomite1 supposed to have been derived from an ordinary limestone altered by heat and volcanic vapours4 ,carbonate of lime enters into the composition of so many of the simple minerals found in ,somma1 that ,m4 ,mitscherlich1 with much probability1 ascribes their great variety to the action of the volcanic heat on subjacent masses of limestone4 ,dikes of ,somma4--,the dikes seen in the great escarpment which ,somma presents towards the modern cone of ,vesuvius are very numerous4 ,they are for the most part vertical1 and traverse at right angles the beds of lava1 scoriae1 volcanic breccia1 and sand1 of which the ancient cone is composed4 ,they project in relief several inches1 or sometimes feet1 from the face of the cliff1 being extremely compact1 and less destructible than the intersected tuffs and porous lavas4 ,in vertical extent they vary from a few yards to #ejj feet1 and in breadth from #a to #ab feet4 ,many of them cut all the inclined beds in the escarpment of ,somma from top to bottom1 others stop short before they ascend above half way1 and a few terminate at both ends1 either in a point or abruptly4 ,in mineral composition they scarcely differ from the lavas of ,somma1 the rock consisting of a base of leucite and augite1 through which large crystals of augite and some of leucite are scattered4#djd-;,a ,examples are not rare of one dike cutting through another1 and in one instance a shift or fault is seen at the point of intersection4 ,in some cases1 however1 the rents seem to have been filled laterally1 when the walls of the crater had been broken by star-shaped cracks1 as seen in the accompanying woodcut 7fig4 #dfg474 ,but the shape of these rents is an exception to the general rule2 for nothing is more remarkable than the usual parallelism of the opposite sides of the dikes1 which correspond almost as regularly as the two opposite faces of a wall of masonry4 ,this character appears at first the more inexplicable1 when we consider how jagged and uneven are the rents caused by earthquakes in masses of heterogeneous composition1 like those composing the cone of ,somma4 ,in explanation of this phenomenon1 ,m4 ,necker refers us to ,sir ,w4 ,hamilton's account of an eruption of ,vesuvius in the year #aggi1 who records the following facts3--,the lavas1 when they either boiled over the crater1 or broke out from the conical parts of the volcano1 constantly formed channels as regular as if they had been cut by art down the steep part of the mountain2 and1 whilst in a state of perfect fusion1 continued their course in those channels1 which were sometimes full to the brim1 and at other times more or less so1 according to the quantity of matter in motion4 ,illustration3 ,fig4 #dfg4 ,dikes or veins at the ,punta del ,nasone on ,somma4 7,necker4#dje-;,a7 ,these channels1 upon examination after an eruption1 ,i have found to be in general from two to five or six feet wide1 and seven or eight feet deep4 ,they were often hid from the sight by a quantity of scoriae that had formed a crust over them2 and the lava1 having been conveyed in a covered way for some yards1 came out fresh again into an open channel4 ,after an eruption1 ,i have walked in some of those subterraneous or covered galleries1 which were exceedingly curious1 the sides1 top1 and bottom being worn perfectly smooth and even in most parts1 by the violence of the currents of the red-hot lavas which they had conveyed for many weeks successively4#dje-;,b ,now1 the walls of a vertical fissure1 through which lava has ascended in its way to a volcanic vent1 must have been exposed to the same erosion as the sides of the channels before adverted to4 ,the prolonged and uniform friction of the heavy fluid1 as it is forced and made to flow upwards1 cannot fail to wear and smooth down the surfaces on which it rubs1 and the intense heat must melt all such masses as project and obstruct the passage of the incandescent fluid4 ,the texture of the ,vesuvian dikes is different at the edges and in the middle4 ,towards the centre1 observes ,m4 ,necker1 the rock is larger grained1 the component elements being in a far more crystalline state2 while at the edge the lava is sometimes vitreous1 and always finer grained4 ,a thin parting band1 approaching in its character to pitchstone1 occasionally intervenes1 on the contact of the vertical dike and intersected beds4 ,m4 ,necker mentions one of these at the place called ,primo ,monte1 in the ,atrio del ,cavallo2 and when on ,somma1 in #ahbh1 ,i saw three or four others in different parts of the great escarpment4 ,these phenomena are in perfect harmony with the results of the experiments of ,sir ,james ,hall and ,mr4 ,gregory ,watt1 which have shown that a glassy texture is the effect of sudden cooling1 and that1 on the contrary1 a crystalline grain is produced where fused minerals are allowed to consolidate slowly and tranquilly under high pressure4 ,it is evident that the central portion of the lava in a fissure would1 during consolidation1 part with its heat more slowly than the sides1 although the contrast of circumstances would not be so great as when we compare the lava at the bottom and at the surface of a current flowing in the open air4 ,in this case the uppermost part1 where it has been in contact with the atmosphere1 and where refrigeration has been most rapid1 is always found to consist of scoriform1 vitreous1 and porous lava2 while at a greater depth the mass assumes a more lithoidal structure1 and then becomes more and more stony as we descend1 until at length we are able to recognize with a magnifying glass the simple minerals of which the rock is composed4 ,on penetrating still deeper1 we can detect the constituent parts by the naked eye1 and in the ,vesuvian currents distinct crystals of augite and leucite become apparent4 ,the same phenomenon1 observes ,m4 ,necker1 may readily be exhibited on a smaller scale1 if we detach a piece of liquid lava from a moving current4 ,the fragment cools instantly1 and we find the surface covered with a vitreous coat2 while the interior1 although extremely fine-grained1 has a more stony appearance4 ,it must1 however1 be observed1 that although the lateral portions of the dikes are finer grained than the central1 yet the vitreous parting layer before alluded to is rare in ,vesuvius4 ,this may1 perhaps1 be accounted for1 as the above-mentioned author suggests1 by the great heat which the walls of a fissure may acquire before the fluid mass begins to consolidate1 in which case the lava1 even at the sides1 would cool very slowly4 ,some fissures1 also1 may be filled from above1 as frequently happens in the volcanos of the ,sandwich ,islands1 according to the observations of ,mr4 ,dana2 and in this case the refrigeration at the sides would be more rapid than when the melted matter flowed upwards from the volcanic foci1 in an intensely heated state4 ,mr4 ,darwin informs me that in ,st4 ,helena almost every dike has a vitreous selvage4 ,the rock composing the dikes both in the modern and ancient part of ,vesuvius is far more compact than that of ordinary lava1 for the pressure of a column of melted matter in a fissure greatly exceeds that in an ordinary stream of lava2 and pressure checks the expansion of those gases which give rise to vesicles in lava4 ,there is a tendency in almost all the ,vesuvian dikes to divide into horizontal prisms1 a phenomenon in accordance with the formation of vertical columns in horizontal beds of lava2 for in both cases the divisions which give rise to the prismatic structure are at right angles to the cooling surfaces4 ,newer ,pliocene ,period--,val di ,noto4--,i have already alluded 7see p4 #aej47 to the igneous rocks which are associated with a great marine formation of limestone1 sand1 and marl1 in the southern part of ,sicily1 as at ,vizzini and other places4 ,in this formation1 which was shown to belong to the ,newer ,pliocene period1 large beds of oysters and corals repose upon lava1 and are unaltered at the point of contact4 ,in other places we find dikes of igneous rock intersecting the fossiliferous beds1 and converting the clays into siliceous schist1 the laminae being contorted and shivered into innumerable fragments at the junction1 as near the town of ,vizzini4 ,the volcanic formations of the ,val di ,noto usually consist of the most ordinary variety of basalt1 with or without olivine4 ,the rock is sometimes compact1 often very vesicular4 ,the vesicles are occasionally empty1 both in dikes and currents1 and are in some localities filled with calcareous spar1 arragonite1 and zeolites4 ,the structure is1 in some places1 spheroidal2 in others1 though rarely1 columnar4 ,i found dikes of amygdaloid1 wacke1 and prismatic basalt1 intersecting the limestone at the bottom of the hollow called ,gozzo degli ,martiri1 below ,melilli4 #b ,illustrations3 ,fig4 #dfh4 ,fig4 #dfi4 ,ground-plan of dikes near ,palagonia4 a4 ,lava4 b4 ,peperino1 consisting of volcanic sand1 mixed with fragments of lava and limestone4 ,dikes4--,dikes of vesicular and amygdaloidal lava are also seen traversing marine tuff or peperino1 west of ,palagonia1 some of the pores of the lava being empty1 while others are filled with carbonate of lime4 ,in such cases1 we may suppose the peperino to have resulted from showers of volcanic sand and scoriae1 together with fragments of limestone1 thrown out by a submarine explosion1 similar to that which gave rise to ,graham ,island in #ahca4 ,when the mass was1 to a certain degree1 consolidated1 it may have been rent open1 so that the lava ascended through fissures1 the walls of which were perfectly even and parallel4 ,after the melted matter that filled the rent in fig4 #dfh4 had cooled down1 it must have been fractured and shifted horizontally by a lateral movement4 ,in the second figure 7fig4 #dfi471 the lava has more the appearance of a vein which forced its way through the peperino4 ,it is highly probable that similar appearances would be seen1 if we could examine the floor of the sea in that part of the ,mediterranean where the waves have recently washed away the new volcanic island2 for when a superincumbent mass of ejected fragments has been removed by denudation1 we may expect to see sections of dikes traversing tuff1 or1 in other words1 sections of the channels of communication by which the subterranean lavas reached the surface4 ,,footnotes3 #cii-;,a ,caldcleugh1 ,phil4 ,trans4 #ahcf4 p4 #bg41 and ,official ,documents of ,nicaragua4 #cii-;,b ,see ,principles1 ,index1 ,skaptar ,jokul4 #dja-;,a ,this view of the ,isle of ,cyclops is from an original drawing by my friend the late ,captain ,basil ,hall1 ,r4 ,n4 #djd-;,a ,consult the valuable memoir of ,m4 ,l4 ,a4 ,necker1 ,mem4 de la ,soc4 de ,phys4 et d',hist4 ,nat4 de ,geneve1 tom4 ii4 part i4 ,nov4 #ahbb4 #dje-;,a ,from a drawing of ,m4 ,necker1 in ,mem4 above cited4 #dje-;,b ,phil4 ,trans41 vol4 lxx41 #aghj4 ,,chapter ,,xxxi4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,volcanic ,,rocks--continued4 ,volcanic rocks of the ,older ,pliocene period--,tuscany--,rome--,volcanic region of ,olot in ,catalonia--,cones and lava-currents--,ravines and ancient gravel-beds--,jets of air called ,bufadors--,age of the ,catalonian volcanos--,miocene period--,brown-coal of the ,eifel and contemporaneous trachytic breccias--,age of the brown-coal--,peculiar characters of the volcanos of the upper and lower ,eifel--,lake craters--,trass--,hungarian volcanos4 ,older ,pliocene period--,tuscany4--,in ,tuscany1 as at ,radicofani1 ,viterbo1 and ,aquapendente1 and in the ,campagna di ,roma1 submarine volcanic tuffs are interstratified with the ,older ,pliocene strata of the ,subapennine hills1 in such a manner as to leave no doubt that they were the products of eruptions which occurred when the shelly marls and sands of the ,subapennine hills were in the course of deposition4 ,catalonia4--,geologists are far from being able1 as yet1 to assign to each of the volcanic groups scattered over ,europe a precise chronological place in the tertiary series2 but ,i shall describe here1 as probably referable to some part of the ,pliocene period1 a district of extinct volcanos near ,olot1 in the north of ,spain1 which is little known1 and which ,i visited in the summer of #ahcj4 ,the whole extent of country occupied by volcanic products in ,catalonia is not more than fifteen geographical miles from north to south1 and about six from east to west4 ,the vents of eruption range entirely within a narrow band running north and south2 and the branches1 which are represented as extending eastward in the map1 are formed simply of two lava-streams--those of ,castell ,follit and ,cellent4 ,illustration3 ,fig4 #dgj4 ,volcanic district of ,catalonia4 ,dr4 ,maclure1 the ,american geologist1 was the first who made known the existence of these volcanos#dji-;,a2 and1 according to his description1 the volcanic region extended over twenty square leagues1 from ,amer to ,massanet4 ,i searched in vain in the environs of ,massanet1 in the ,pyrenees1 for traces of a lava-current2 and ,i can say1 with confidence1 that the adjoining map gives a correct view of the true area of the volcanic action4 ,geological structure of the district4--,the eruptions have burst entirely through fossiliferous rocks1 composed in great part of grey and greenish sandstone and conglomerate1 with some thick beds of nummulitic limestone4 ,the conglomerate contains pebbles of quartz1 limestone1 and ,lydian stone4 ,this system of rocks is very extensively spread throughout ,catalonia2 one of its members being a red sandstone1 to which the celebrated salt-rock of ,cardona1 usually considered as of the cretaceous era1 is subordinate4 ,near ,amer1 in the ,valley of the ,ter1 on the southern borders of the region delineated in the map1 primary rocks are seen1 consisting of gneiss1 mica-schist1 and clay-slate4 ,they run in a line nearly parallel to the ,pyrenees1 and throw off the fossiliferous strata from their flanks1 causing them to dip to the north and north-west4 ,this dip1 which is towards the ,pyrenees1 is connected with a distinct axis of elevation1 and prevails through the whole area described in the map1 the inclination of the beds being sometimes at an angle of between #dj and #ej degrees4 ,it is evident that the physical geography of the country has undergone no material change since the commencement of the era of the volcanic eruptions1 except such as has resulted from the introduction of new hills of scoriae1 and currents of lava upon the surface4 ,if the lavas could be remelted and poured out again from their respective craters1 they would descend the same valleys in which they are now seen1 and re-occupy the spaces which they at present fill4 ,the only difference in the external configuration of the fresh lavas would consist in this1 that they would nowhere be intersected by ravines1 or exhibit marks of erosion by running water4 ,volcanic cones and lavas4--,there are about fourteen distinct cones with craters in this part of ,spain1 besides several points whence lavas may have issued2 all of them arranged along a narrow line running north and south1 as will be seen in the map4 ,the greatest number of perfect cones are in the immediate neighbourhood of ,olot1 some of which 7,nos4 #b1 #c4 and #e47 are represented in the annexed woodcut2 and the level plain on which that town stands has clearly been produced by the flowing down of many lava-streams from those hills into the bottom of a valley1 probably once of considerable depth1 like those of the surrounding country4 ,illustration3 ,fig4 #dga4 ,view of the ,volcanos around ,olot in ,catalonia4 ,in this drawing an attempt is made to represent1 by the shading of the landscape1 the different geological formations of which the country is composed4#daj-;,a ,the white line of mountains 7,no4 #a47 in the distance is the ,pyrenees1 which are to the north of the spectator1 and consist of hypogene and ancient fossiliferous rocks4 ,in front of these are the fossiliferous formations 7,no4 #d47 which are in shade4 ,the hills #b1 #c4 #e4 are volcanic cones1 and the rest of the ground on which the sunshine falls is strewed over with volcanic ashes and lava4 ,the ,fluvia1 which flows near the town of ,olot1 has cut to the depth of only #dj feet through the lavas of the plain before mentioned4 ,the bed of the river is hard basalt2 and at the bridge of ,santa ,madalena are seen two distinct lava-currents1 one above the other1 separated by a horizontal bed of scoriae #h feet thick4 ,in one place1 to the south of ,olot1 the even surface of the plain is broken by a mound of lava1 called the ,bosque de ,tosca1 the upper part of which is scoriaceous1 and covered with enormous heaps of fragments of basalt1 more or less porous4 ,between the numerous hummocks thus formed are deep cavities1 having the appearance of small craters4 ,the whole precisely resembles some of the modern currents of ,etna1 or that of ,come1 near ,clermont2 the last of which1 like the ,bosque de ,tosca1 supports only a scanty vegetation4 ,most of the ,catalonian volcanos are as entire as those in the neighbourhood of ,naples1 or on the flanks of ,etna4 ,one of these1 called ,montsacopa 7,no4 #c4 fig4 #dga471 is of a very regular form1 and has a circular depression or crater at the summit4 ,it is chiefly made up of red scoriae1 undistinguishable from that of the minor cones of ,etna4 ,the neighbouring hills of ,olivet 7,no4 #b47 and ,garrinada 7,no4 #e47 are of similar composition and shape4 ,the largest crater of the whole district occurs farther to the east of ,olot1 and is called ,santa ,margarita4 ,it is #dee feet deep1 and about a mile in circumference4 ,like ,astroni1 near ,naples1 it is richly covered with wood1 wherein game of various kinds abounds4 ,illustration3 ,fig4 #dgb4 ,cross section4 a4 ,secondary conglomerate4 b4 ,thin seams of volcanic sand and scoriae4 ,although the volcanos of ,catalonia have broken out through sandstone1 shale1 and limestone1 as have those of the ,eifel1 in ,germany1 to be described in the sequel1 there is a remarkable difference in the nature of the ejections composing the cones in these two regions4 ,in the ,eifel1 the quantity of pieces of sandstone and shale thrown out from the vents is often so immense as far to exceed in volume the scoriae1 pumice1 and lava2 but ,i sought in vain in the cones near ,olot for a single fragment of any extraneous rock2 and ,don ,francisco ,bolos1 an eminent botanist of ,olot1 informed me that he had never been able to detect any4 ,volcanic sand and ashes are not confined to the cones1 but have been sometimes scattered by the wind over the country1 and drifted into narrow valleys1 as is seen between ,olot and ,cellent1 where the annexed section 7fig4 #dgb47 is exposed4 ,the light cindery volcanic matter rests in thin regular layers1 just as it alighted on the slope formed by the solid conglomerate4 ,no flood could have passed through the valley since the scoriae fell1 or these would have been for the most part removed4 ,illustration3 ,fig4 #dgc4 ,section above the bridge of ,cellent4 a4 ,scoriaceous lava4 b4 ,schistose basalt4 c4 ,columnar basalt4 d4 ,scoria1 vegetable soil1 and alluvium4 e4 ,nummulitic limestone4 4f ,micaceous grey sandstone4 ,the currents of lava in ,catalonia1 like those of ,auvergne1 the ,vivarais1 ,iceland1 and all mountainous countries1 are of considerable depth in narrow defiles1 but spread out into comparatively thin sheets in places where the valleys widen4 ,if a river has flowed on nearly level ground1 as in the great plain near ,olot1 the water has only excavated a channel of slight depth2 but where the declivity is great1 the stream has cut a deep section1 sometimes by penetrating directly through the central part of a lava-current1 but more frequently by passing between the lava and the secondary rock which bounds the valley4 ,thus1 in the accompanying section1 at the bridge of ,cellent1 six miles east of ,olot1 we see the lava on one side of the small stream2 while the inclined stratified rocks constitute the channel and opposite bank4 ,the upper part of the lava at that place1 as is usual in the currents of ,etna and ,vesuvius1 is scoriaceous2 farther down it becomes less porous1 and assumes a spheroidal structure2 still lower it divides in horizontal plates1 each about #b inches in thickness1 and is more compact4 ,lastly1 at the bottom is a mass of prismatic basalt about #e feet thick4 ,the vertical columns often rest immediately on the subjacent secondary rocks2 but there is sometimes an intervention of such sand and scoriae as cover the country during volcanic eruptions1 and which when unprotected1 as here1 by superincumbent lava1 is washed away from the surface of the land4 ,sometimes1 the bed d contains a few pebbles and angular fragments of rock2 in other places fine earth1 which may have constituted an ancient vegetable soil4 ,in several localities1 beds of sand and ashes are interposed between the lava and subjacent stratified rock1 as may be seen if we follow the course of the lava-current which descends from ,las ,planas towards ,amer1 and stops two miles short of that town4 ,the river there has often cut through the lava1 and through #ah feet of underlying limestone4 ,occasionally an alluvium1 several feet thick1 is interspersed between the igneous and marine formation2 and it is interesting to remark that in this1 as in other beds of pebbles occupying a similar position1 there are no rounded fragments of lava2 whereas in the most modern gravel-beds of rivers of this country1 volcanic pebbles are abundant4 ,the deepest excavation made by a river through lava1 which ,i observed in this part of ,spain1 is that seen in the bottom of a valley near ,san ,feliu de ,pallerols1 opposite the ,castell de ,stolles4 ,the lava there has filled up the bottom of a valley1 and a narrow ravine has been cut through it to the depth of #ajj feet4 ,in the lower part the lava has a columnar structure4 ,a great number of ages were probably required for the erosion of so deep a ravine2 but we have no reason to infer that this current is of higher antiquity than those of the plain near ,olot4 ,the fall of the ground1 and consequent velocity of the stream1 being in this case greater1 a more considerable volume of rock may have been removed in the same time4 ,illustration3 ,fig4 #dgd4 ,section at ,castell ,follit4 ,a4 ,church and town of ,castell ,follit1 overlooking precipices of basalt4 ,b4 ,small island1 on each side of which branches of the river ,teronel flow to meet the ,fluvia4 c4 ,precipice of basaltic lava1 chiefly columnar1 about #acj feet in height4 d4 ,ancient alluvium1 underlying the lava-current4 e4 ,inclined strata of secondary sandstone4 ,i shall describe one more section to elucidate the phenomena of this district4 ,a lava-stream1 flowing from a ridge of hills on the east of ,olot1 descends a considerable slope1 until it reaches the valley of the river ,fluvia4 ,here1 for the first time1 it comes in contact with running water1 which has removed a portion1 and laid open its internal structure in a precipice about #acj feet in height1 at the edge of which stands the town of ,castell ,follit4 ,by the junction of the rivers ,fluvia and ,teronel1 the mass of lava has been cut away on two sides2 and the insular rock ,b 7fig4 #dgd47 has been left1 which was probably never so high as the cliff ,a1 as it may have constituted the lower part of the sloping side of the original current4 ,from an examination of the vertical cliffs1 it appears that the upper part of the lava on which the town is built is scoriaceous1 passing downwards into a spheroidal basalt2 some of the huge spheroids being no less than #f feet in diameter4 ,below this is a more compact basalt1 with crystals of olivine4 ,there are in all five distinct ranges of basalt1 the uppermost spheroidal1 and the rest prismatic1 separated by thinner beds not columnar1 and some of which are schistose4 ,these were probably formed by successive flows of lava1 whether during the same eruption or at different periods4 ,the whole mass rests on alluvium1 ten or twelve feet in thickness1 composed of pebbles of limestone and quartz1 but without any intermixture of igneous rocks2 in which circumstance alone it appears to differ from the modern gravel of the ,fluvia4 ,bufadors4--,the volcanic rocks near ,olot have often a cavernous structure1 like some of the lavas of ,etna2 and in many parts of the hill of ,batet1 in the environs of the town1 the sound returned by the earth1 when struck1 is like that of an archway4 ,at the base of the same hill are the mouths of several subterranean caverns1 about twelve in number1 which are called in the country bufadors1 from which a current of cold air issues during summer1 but which in winter is said to be scarcely perceptible4 ,i visited one of these bufadors in the beginning of ,august1 #ahcj1 when the heat of the season was unusually intense1 and found a cold wind blowing from it1 which may easily be explained2 for as the external air1 when rarefied by heat1 ascends1 the pressure of the colder and heavier air of the caverns in the interior of the mountain causes it to rush out to supply its place4 ,in regard to the age of these ,spanish volcanos1 attempts have been made to prove1 that in this country1 as well as in ,auvergne and the ,eifel1 the earliest inhabitants were eye-witnesses to the volcanic action4 ,in the year #adba1 it is said1 when ,olot was destroyed by an earthquake1 an eruption broke out near ,amer1 and consumed the town4 ,the researches of ,don ,francisco ,bolos have1 ,i think1 shown1 in the most satisfactory manner1 that there is no good historical foundation for the latter part of this story2 and any geologist who has visited ,amer must be convinced that there never was any eruption on that spot4 ,it is true that1 in the year above mentioned1 the whole of ,olot1 with the exception of a single house1 was cast down by an earthquake2 one of those shocks which1 at distant intervals during the last five centuries1 have shaken the ,pyrenees1 and particularly the country between ,perpignan and ,olot1 where the movements1 at the period alluded to1 were most violent4 ,the annihilation of the town may1 perhaps1 have been due to the cavernous nature of the subjacent rocks2 for ,catalonia is beyond the line of those ,european earthquakes which have1 within the period of history1 destroyed towns throughout extensive areas4 ,as we have no historical records1 then1 to guide us in regard to the extinct volcanos1 we must appeal to geological monuments4 ,the annexed diagram will present to the reader1 in a synoptical form1 the results obtained from numerous sections4 ,the more modern alluvium 7d7 is partial1 and has been formed by the action of rivers and floods upon the lava2 whereas the older gravel 7b7 was strewed over the country before the volcanic eruptions4 ,in neither have any organic remains been discovered2 so that we can merely affirm1 as yet1 that the volcanos broke out after the elevation of some of the newest rocks of the nummulitic 7,eocene87 series of ,catalonia1 and before the formation of an alluvium 7d7 of unknown date4 ,the integrity of the cones merely shows that the country has not been agitated by violent earthquakes1 or subjected to the action of any great transient flood since their origin4 ,illustration3 ,fig4 #dge4 ,superposition of rocks in the volcanic district of ,catalonia4 a4 ,sandstone and nummulitic limestone4 b4 ,older alluvium without volcanic pebbles4 c4 ,cones of scoriae and lava4 d4 ,newer alluvium4 ,east of ,olot1 on the ,catalonian coast1 marine tertiary strata occur1 which1 near ,barcelona1 attain the height of about #ejj feet4 ,from the shells which ,i collected1 these strata appear to correspond in age with the ,subapennine beds2 and it is not improbable that their upheaval from beneath the sea took place during the period of volcanic eruption round ,olot4 ,in that case these eruptions may have occurred at the close of the ,older ,pliocene era1 but perhaps subsequently1 for their age is at present quite uncertain4 ,miocene period--,volcanic rocks of the ,eifel4--,the chronological relations of the volcanic rocks of the ,lower ,rhine and the ,eifel are also involved in a considerable degree of ambiguity2 but we know that some portion of them were coeval with the deposition of a tertiary formation1 called ,brown-,coal by the ,germans1 which probably belongs to the ,miocene1 if not referable to the ,upper ,eocene1 epoch4 ,this ,brown-,coal is seen on both sides of the ,rhine1 in the neighbourhood of ,bonn1 resting unconformably on highly inclined and vertical strata of ,silurian and ,devonian rocks4 ,its position1 and the space occupied by the volcanic rocks1 both of the ,westerwald and ,eifel1 will be seen by referring to the map in the next page 7fig4 #dgf471 for which ,i am indebted to ,mr4 ,horner1 whose residence in the country has enabled him to verify the maps of ,,mm4 ,noeggerath and ,von ,oeynhausen1 from which that now given has been principally compiled4 ,the ,brown-,coal formation consists of beds of loose sand1 sandstone1 and conglomerate1 clay with nodules of clay-ironstone1 and occasionally silex4 ,layers of light brown1 and sometimes black lignite1 are interstratified with the clays and sands1 and often irregularly diffused through them4 ,they contain numerous impressions of leaves and stems of trees1 and are extensively worked for fuel1 whence the name of the formation4 ,illustration3 ,fig4 #dgf4 ,map of the volcanic region of the ,upper and ,lower ,eifel4 #abcde ,english ,miles4 ,volcanic ,district ,a4 of the ,upper ,eifel4 ,b4 of the ,lower ,eifel4 ,trachyte4 ,points of eruption1 with craters and scoriae4 ,basalt4 ,brown-coal4 ,n4,b4 ,the country in that part of the map which is left blank is composed of inclined ,silurian and ,devonian rocks4 ,in several places1 layers of trachytic tuff are interstratified1 and in these tuffs are leaves of plants identical with those found in the brown-coal1 showing that1 during the period of the accumulation of the latter1 some volcanic products were ejected4 ,the varieties of wood in the lignite are said to belong entirely to dicotyledonous trees2 but among the impressions of leaves1 collected by ,mr4 ,horner1 some were referred by ,mr4 ,lindley to a palm1 perhaps of the genus ,chamaerops1 and others resembled the ,cinnamomum dulce1 and ,podocarpus macrophylla1 which would also indicate a warm climate4#daf-;,a ,the other organic remains of the brown-coal are principally fishes2 they are found in a bituminous shale1 called paper-coal1 from being divisible into extremely thin leaves4 ,the individuals are very numerous2 but they appear to belong to about five species1 which ,m4 ,agassiz informs me are all extinct1 and hitherto peculiar to this brown-coal4 ,they belong to the freshwater genera ,leuciscus1 ,aspius1 and ,perca4 ,the remains of frogs also1 of an extinct species1 have been discovered in the paper-coal2 and a complete series may be seen in the museum at ,bonn1 from the most imperfect state of the tadpole to that of the full-grown animal4 ,with these a salamander1 scarcely distinguishable from the recent species1 has been found1 and several remains of insects4 ,the brown-coal was evidently a freshwater formation2 but fossil shells have been scarcely ever found in it2 although near ,marienforst1 in the vicinity of ,bonn1 large blocks have been met with of a white opaque chert1 containing numerous casts of freshwater shells1 which appear to belong to ,planorbis rotundatus and ,limnea longiscata1 two species common both to the ,middle and ,upper ,eocene periods4 ,it is very probable that the brown-coal may be connected in age with those fluvio-marine formations which are found in higher parts of the valley of the ,rhine1 as at ,mayence before mentioned 7p4 #agg474 ,a vast deposit of gravel1 chiefly composed of pebbles of white quartz1 but containing also a few fragments of other rocks1 lies over the brown-coal formation1 forming sometimes only a thin covering1 at others attaining a thickness of more than #ajj feet4 ,this gravel is very distinct in character from that now forming the bed of the ,rhine4 ,it is called ,kiesel gerolle by the ,germans1 often reaches great elevations1 and is covered in several places with volcanic ejections4 ,it is evident that the country has undergone great changes in its physical geography since this gravel was formed2 for its position has scarcely any relation to the existing drainage of the country1 and all the more modern volcanic rocks of the same region are posterior to it in date4 ,some of the newest beds of volcanic sand1 pumice1 and scoriae are interstratified near ,andernach and elsewhere with the loam called loess1 which was before described as being full of land and freshwater shells of recent species1 and referable to the ,post-,pliocene period4 ,i have before hinted 7see p4 #aah47 that this intercalation of volcanic matter between beds of loess may possibly be explained without supposing the last eruptions of the ,lower ,eifel to have taken place so recently as the era of the deposition of the loess2 but farther researches should be directed to the investigation of this curious point4 ,the igneous rocks of the ,westerwald1 and of the mountains called the ,siebengebirge1 consist partly of basaltic and partly of trachytic lavas1 the latter being in general the more ancient of the two4 ,there are many varieties of trachyte1 some of which are highly crystalline1 resembling a coarse-grained granite1 with large separate crystals of felspar4 ,trachytic tuff is also very abundant4 ,these formations1 some of which were certainly contemporaneous with the origin of the brown-coal1 were the first of a long series of eruptions1 the more recent of which happened when the country had acquired nearly all its present geographical features4 ,newer volcanos of the ,eifel4--,lake-craters4--,as ,i recognized in the more modern volcanos of the ,eifel characters distinct from any previously observed by me in those of ,france1 ,italy1 or ,spain1 ,i shall briefly describe them4 ,the fundamental rocks of the district are grey and red sandstones and shales1 with some associated limestones1 replete with fossils of the ,devonian or ,old ,red ,sandstone group4 ,the volcanos broke out in the midst of these inclined strata1 and when the present systems of hills and valleys had already been formed4 ,the eruptions occurred sometimes at the bottom of deep valleys1 sometimes on the summit of hills1 and frequently on intervening platforms4 ,in travelling through this district we often fall upon them most unexpectedly1 and may find ourselves on the very edge of a crater before we had been led to suspect that we were approaching the site of any igneous outburst4 ,thus1 for example1 on arriving at the village of ,gemund1 immediately south of ,daun1 we leave the stream1 which flows at the bottom of a deep valley in which strata of sandstone and shale crop out4 ,we then climb a steep hill1 on the surface of which we see the edges of the same strata dipping inwards towards the mountain4 ,when we have ascended to a considerable height1 we see fragments of scoriae sparingly scattered over the surface2 till1 at length1 on reaching the summit1 we find ourselves suddenly on the edge of a tarn1 or deep circular lake-basin4 ,illustration3 ,fig4 #dgg4 ,the ,gemunder ,maar4 ,illustration3 ,fig4 #dgh4 ,cross section4 a4 ,village of ,gemund4 b4 ,gemunder ,maar4 c4 ,weinfelder ,maar4 d4 ,schalkenmehren ,maar4 ,this1 which is called the ,gemunder ,maar1 is the first of three lakes which are in immediate contact1 the same ridge forming the barrier of two neighbouring cavities 7see fig4 #dgg474 ,on viewing the first of these1 we recognize the ordinary form of a crater1 for which we have been prepared by the occurrence of scoriae scattered over the surface of the soil4 ,but on examining the walls of the crater we find precipices of sandstone and shale which exhibit no signs of the action of heat2 and we look in vain for those beds of lava and scoriae1 dipping in opposite directions on every side1 which we have been accustomed to consider as characteristic of volcanic craters4 ,as we proceed1 however1 to the opposite side of the lake1 and afterwards visit the craters c and d 7fig4 #dgh471 we find a considerable quantity of scoriae and some lava1 and see the whole surface of the soil sparkling with volcanic sand1 and strewed with ejected fragments of half-fused shale1 which preserves its laminated texture in the interior1 while it has a vitrified or scoriform coating4 ,a few miles to the south of the lakes above mentioned occurs the ,pulvermaar of ,gillenfeld1 an oval lake of very regular form1 and surrounded by an unbroken ridge of fragmentary materials1 consisting of ejected shale and sandstone1 and preserving a uniform height of about #aej feet above the water4 ,the side slope in the interior is at an angle of about #de degrees2 on the exterior1 of #ce degrees4 ,volcanic substances are intermixed very sparingly with the ejections1 which in this place entirely conceal from view the stratified rocks of the country4#dai-;,a ,illustration3 ,fig4 #dgi4 ,outline of ,mosenberg1 ,upper ,eifel4 ,the ,meerfelder ,maar is a cavity of far greater size and depth1 hollowed out of similar strata2 the sides presenting some abrupt sections of inclined secondary rocks1 which in other places are buried under vast heaps of pulverized shale4 ,i could discover no scoriae amongst the ejected materials1 but balls of olivine and other volcanic substances are mentioned as having been found4#dai-;,b ,this cavity1 which we must suppose to have discharged an immense volume of gas1 is nearly a mile in diameter1 and is said to be more than one hundred fathoms deep4 ,in the neighbourhood is a mountain called the ,mosenberg1 which consists of red sandstone and shale in its lower parts1 but supports on its summit a triple volcanic cone1 while a distinct current of lava is seen descending the flanks of the mountain4 ,the edge of the crater of the largest cone reminded me much of the form and characters of that of ,vesuvius2 but ,i was much struck with the precipitous and almost overhanging wall or parapet which the scoriae presented towards the exterior1 as at a b 7fig4 #dgi472 which ,i can only explain by supposing that fragments of red-hot lava1 as they fell round the vent1 were cemented together into one compact mass1 in consequence of continuing to be in a half-melted state4 ,if we pass from the ,upper to the ,lower ,eifel1 from ,a to ,b 7see map1 p4 #daf471 we find the celebrated lake-crater of ,laach1 which has a greater resemblance than any of those before mentioned to the ,lago di ,bolsena1 and others in ,italy--being surrounded by a ridge of gently sloping hills1 composed of loose tuffs1 scoriae1 and blocks of a variety of lavas4 ,one of the most interesting volcanos on the left bank of the ,rhine is called the ,roderberg4 ,it forms a circular crater nearly a quarter of a mile in diameter1 and #ajj feet deep1 now covered with fields of corn4 ,the highly inclined strata of ancient sandstone and shale rise even to the rim of one side of the crater2 but they are overspread by quartzose gravel1 and this again is covered by volcanic scoriae and tufaceous sand4 ,the opposite wall of the crater is composed of cinders and scorified rock1 like that at the summit of ,vesuvius4 ,it is quite evident that the eruption in this case burst through the sandstone and alluvium which immediately overlies it2 and ,i observed some of the quartz pebbles mixed with scoriae on the flanks of the mountain1 as if they had been cast up into the air1 and had fallen again with the volcanic ashes4 ,i have already observed1 that a large part of this crater has been filled up with loess 7p4 #aah474 ,the most striking peculiarity of a great many of the craters above described1 is the absence of any signs of alteration or torrefaction in their walls1 when these are composed of regular strata of ancient sandstone and shale4 ,it is evident that the summits of hills formed of the above-mentioned stratified rocks have1 in some cases1 been carried away by gaseous explosions1 while at the same time no lava1 and often a very small quantity only of scoriae1 has escaped from the newly formed cavity4 ,there is1 indeed1 no feature in the ,eifel volcanos more worthy of note1 than the proofs they afford of very copious aeriform discharges1 unaccompanied by the pouring out of melted matter1 except1 here and there1 in very insignificant volume4 ,i know of no other extinct volcanos where gaseous explosions of such magnitude have been attended by the emission of so small a quantity of lava4 ,yet ,i looked in vain in the ,eifel for any appearances which could lend support to the hypothesis1 that the sudden rushing out of such enormous volumes of gas had ever lifted up the stratified rocks immediately around the vent1 so as to form conical masses1 having their strata dipping outwards on all sides from a central axis1 as is assumed in the theory of elevation craters1 alluded to at the end of ,chap4 ,,xxix4 ,trass4--,in the ,lower ,eifel1 eruptions of trachytic lava preceded the emission of currents of basalt1 and immense quantities of pumice were thrown out wherever trachyte issued4 ,the tufaceous alluvium called trass1 which has covered large areas in this region and choked up some valleys now partially re-excavated1 is unstratified4 ,its base consists almost entirely of pumice1 in which are included fragments of basalt and other lavas1 pieces of burnt shale1 slate1 and sandstone1 and numerous trunks and branches of trees4 ,if this trass was formed during the period of volcanic eruptions it may perhaps have originated in the manner of the moya of the ,andes4 ,we may easily conceive that a similar mass might now be produced1 if a copious evolution of gases should occur in one of the lake basins4 ,the water might remain for weeks in a state of violent ebullition1 until it became of the consistency of mud1 just as the sea continued to be charged with red mud round ,graham's ,island1 in the ,mediterranean1 in the year #ahca4 ,if a breach should then be made in the side of the cone1 the flood would sweep away great heaps of ejected fragments of shale and sandstone1 which would be borne down into the adjoining valleys4 ,forests might be torn up by such a flood1 and thus the occurrence of the numerous trunks of trees dispersed irregularly through the trass1 can be explained4 ,hungary4--,m4 ,beudant1 in his elaborate work on ,hungary1 describes five distinct groups of volcanic rocks1 which although nowhere of great extent1 form striking features in the physical geography of that country1 rising as they do abruptly from extensive plains composed of tertiary strata4 ,they may have constituted islands in the ancient sea1 as ,santorin and ,milo now do in the ,grecian ,archipelago2 and ,m4 ,beudant has remarked that the mineral products of the last-mentioned islands resemble remarkably those of the ,hungarian extinct volcanos1 where many of the same minerals as opal1 calcedony1 resinous silex 7silex resinite71 pearlite1 obsidian1 and pitchstone abound4 ,the ,hungarian lavas are chiefly felspathic1 consisting of different varieties of trachyte2 many are cellular1 and used as millstones2 some so porous and even scoriform as to resemble those which have issued in the open air4 ,pumice occurs in great quantity2 and there are conglomerates1 or rather breccias1 wherein fragments of trachyte are bound together by pumiceous tuff1 or sometimes by silex4 ,it is probable that these rocks were permeated by the waters of hot springs1 impregnated1 like the ,geysers1 with silica2 or in some instances1 perhaps1 by aqueous vapours1 which1 like those of ,lancerote1 may have precipitated hydrate of silica4 ,by the influence of such springs or vapours the trunks and branches of trees washed down during floods1 and buried in tuffs on the flanks of the mountains1 are supposed to have become silicified4 ,it is scarcely possible1 says ,m4 ,beudant1 to dig into any of the pumiceous deposits of these mountains without meeting with opalized wood1 and sometimes entire silicified trunks of trees of great size and weight4 ,it appears from the species of shells collected principally by ,m4 ,boue1 and examined by ,m4 ,deshayes1 that the fossil remains imbedded in the volcanic tuffs1 and in strata alternating with them in ,hungary1 are of the ,miocene type1 and not identical1 as was formerly supposed1 with the fossils of the ,paris basin4 ,,footnotes3 #dji-;,a ,maclure1 ,journ4 de ,phys41 vol4 lxvi4 p4 #bai41 #ahjh2 cited by ,daubeny1 ,description of ,volcanos1 p4 #bd4 #daj-;,a ,this view is taken from a sketch which ,i made on the spot in #ahcj4 #daf-;,a ,trans4 of ,geol4 ,soc41 #b;d series1 vol4 v4 #dai-;,a ,scrope1 ,edin4 ,journ4 of ,sci41 ,june1 #ahbf1 p4 #ade4 #dai-;,b ,hibbert1 ,extinct ,volcanos of the ,rhine1 p4 #bd4 ,,chapter ,,xxxii4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,volcanic ,,rocks--continued4 ,volcanic rocks of the ,pliocene and ,miocene periods continued--,auvergne--,mont ,dor--,breccias and alluviums of ,mont ,perrier1 with bones of quadrupeds--,river dammed up by lava-current--,range of minor cones from ,auvergne to the ,vivarais--,monts ,dome--,puy de ,come--,puy de ,pariou--,cones not denuded by general flood--,velay--,bones of quadrupeds buried in scoriae--,cantal--,eocene volcanic rocks--,tuffs near ,clermont--,hill of ,gergovia--,trap of ,cretaceous period--,oolitic period--,new ,red ,sandstone period--,carboniferous period--,old ,red ,sandstone period--,rock and ,spindle near ,st4 ,andrews--,silurian period--,cambrian volcanic rocks4 ,tertiary ,volcanic ,rocks4--,auvergne4--,the extinct volcanos of ,auvergne and ,cantal in ,central ,france seem to have commenced their eruptions in the ,upper ,eocene period1 but to have been most active during the ,miocene and ,pliocene eras4 ,i have already alluded to the grand succession of events1 of which there is evidence in ,auvergne since the last retreat of the sea 7see p4 #agh474 ,the earliest monuments of the tertiary period in that region are lacustrine deposits of great thickness 7#b4 fig4 #dhj4 p4 #dbd471 in the lowest conglomerates of which are rounded pebbles of quartz1 mica-schist1 granite1 and other non-volcanic rocks1 without the slightest intermixture of igneous products4 ,to these conglomerates succeed argillaceous and calcareous marls and limestones 7#c4 fig4 #dhj47 containing ,upper ,eocene shells and bones of mammalia1 the higher beds of which sometimes alternate with volcanic tuff of contemporaneous origin4 ,after the filling up or drainage of the ancient lakes1 huge piles of trachytic and basaltic rocks1 with volcanic breccias1 accumulated to a thickness of several thousand feet1 and were superimposed upon granite1 or the contiguous lacustrine strata4 ,the greater portion of these igneous rocks appear to have originated during the ,miocene and ,pliocene periods2 and extinct quadrupeds of those eras1 belonging to the genera ,mastodon1 ,rhinoceros1 and others1 were buried in ashes and beds of alluvial sand and gravel1 which owe their preservation to overspreading sheets of lava4 ,in ,auvergne the most ancient and conspicuous of the volcanic masses is ,mont ,dor1 which rests immediately on the granitic rocks standing apart from the freshwater strata4#dbb-;,a ,this great mountain rises suddenly to the height of several thousand feet above the surrounding platform1 and retains the shape of a flattened and somewhat irregular cone1 all the sides sloping more or less rapidly1 until their inclination is gradually lost in the high plain around4 ,this cone is composed of layers of scoriae1 pumice-stones1 and their fine detritus1 with interposed beds of trachyte and basalt1 which descend often in uninterrupted sheets1 till they reach and spread themselves round the base of the mountain4#dbc-;,a ,conglomerates1 also1 composed of angular and rounded fragments of igneous rocks1 are observed to alternate with the above2 and the various masses are seen to dip off from the central axis1 and to lie parallel to the sloping flanks of the mountain4 ,the summit of ,mont ,dor terminates in seven or eight rocky peaks1 where no regular crater can now be traced1 but where we may easily imagine one to have existed1 which may have been shattered by earthquakes1 and have suffered degradation by aqueous agents4 ,originally1 perhaps1 like the highest crater of ,etna1 it may have formed an insignificant feature in the great pile1 and may frequently have been destroyed and renovated4 ,according to some geologists1 this mountain1 as well as ,vesuvius1 ,etna1 and all large volcanos1 has derived its dome-like form not from the preponderance of eruptions from one or more central points1 but from the upheaval of horizontal beds of lava and scoriae4 ,i have explained my reasons for objecting to this view at the close of ,chap4 ,,xxix41 when speaking of ,palma1 and in the ,principles of ,geology4#dbc-;,b ,the average inclination of the dome-shaped mass of ,mont ,dor is #h deg4 #f'1 whereas in ,mounts ,loa and ,kea1 before mentioned1 in the ,sandwich ,islands 7see fig4 #deg4 p4 #cid471 the flanks of which have been raised by recent lavas1 we find from ,mr4 ,dana's description that the one has a slope of #f deg4 #cj'1 the other of #g deg4 #df'4 ,we may1 therefore1 reasonably question whether there is any absolute necessity for supposing that the basaltic currents of the ancient ,french volcano were at first more horizontal than they are now4 ,nevertheless it is highly probable that during the long series of eruptions required to give rise to so vast a pile of volcanic matter1 which is thickest at the summit or centre of the dome1 some dislocation and upheaval took place2 and during the distension of the mass1 beds of lava and scoriae may1 in some places1 have acquired a greater1 in others a less inclination1 than that which at first belonged to them4 ,respecting the age of the great mass of ,mont ,dor1 we cannot come at present to any positive decision1 because no organic remains have yet been found in the tuffs1 except impressions of the leaves of trees of species not yet determined4 ,we may certainly conclude1 that the earliest eruptions were posterior in origin to those grits1 and conglomerates of the freshwater formation of the ,limagne1 which contain no pebbles of volcanic rocks2 while1 on the other hand1 some eruptions took place before the great lakes were drained2 and others occurred after the desiccation of those lakes1 and when deep valleys had already been excavated through freshwater strata4 ,in the annexed section1 ,i have endeavoured to explain the geological structure of a portion of ,auvergne1 which ,i re-examined in #ahdc4dbc-;,c ,it may convey some idea to the reader of the long and complicated series of events1 which have occurred in that country1 since the first lacustrine strata 7,no4 #b47 were deposited on the granite 7,no4 #a474 ,the changes of which we have evidence are the more striking1 because they imply great denudation1 without there being any proofs of the intervention of the sea during the whole period4 ,it will be seen that the upper freshwater beds 7,no4 #c471 once formed in a lake1 must have suffered great destruction before the excavation of the valleys of the ,couze and ,allier had begun4 ,in these freshwater beds1 ,upper ,eocene fossils1 as described in ,chap4 ,,xv41 have been found4 ,the basaltic dike #d' is one of many examples of the intrusion of volcanic matter through the ,eocene freshwater beds1 and may have been of ,upper ,eocene or ,miocene date1 giving rise1 when it reached the surface and overflowed1 to such platforms of basalt1 as often cap the tertiary hills in ,auvergne1 and one of which 7#d7 is seen on ,mont ,perrier4 ,illustration3 ,fig4 #dhj4 ,section from the valley of the ,couze at ,nechers1 through ,mont ,perrier and ,issoire to the ,valley of the ,allier1 and the ,tour de ,boulade1 ,auvergne4 #aj4 ,lava-current of ,tartaret near its termination at ,nechers4 #i4 ,bone-bed1 red sandy clay under the lava of ,tartaret4 #h4 ,bone-bed of the ,tour de ,boulade4 #g4 ,alluvium newer than ,no4 #f4 #f4 ,alluvium with bones of hippopotamus4 #e c4 ,trachytic breccia resembling #e a4 #e b4 ,upper bone-bed of ,perrier1 gravel1 c4 #e a4 ,pumiceous breccia and conglomerate1 angular masses of trachyte1 quartz1 pebbles1 c4 #e4 ,lower bone-bed of ,perrier1 ochreous sand and gravel4 #d a4 ,basaltic dyke4 #d4 ,basaltic platform4 #c4 ,upper freshwater beds1 limestone1 marl1 gypsum1 c4 #b4 ,lower freshwater formation1 red clay1 green sand1 c4 #a4 ,granite4 ,it not unfrequently happens that beds of gravel containing bones of extinct mammalia are detected under these very ancient sheets of basalt1 as between ,no4 #d4 and the freshwater strata1 ,no4 #c41 at ,a1 from which it is clear that the surface of #c formed at that period the lowest level at which the waters then draining the country flowed4 ,next in age to this basaltic platform comes a patch of ochreous sand and gravel 7,no4 #e471 containing many bones of quadrupeds4 ,upon this rests a pumiceous breccia and conglomerate1 with angular masses of trachyte1 and some quartz pebbles4 ,this deposit is followed by #e b1 which is similar to #e1 and #e c similar to the trachytic breccia #e a4 ,these two breccias are supposed1 from their similarity to others found on ,mount ,dor1 to have descended from the flanks of that mountain during eruptions2 and the interstratified alluvial deposits contain the remains of mastodon1 rhinoceros1 tapir1 deer1 beaver1 and quadrupeds of other genera referable to about forty species1 all of which are extinct4 ,i formerly supposed them to belong to the same era as the ,miocene faluns of ,touraine2 but1 whether they may not rather be ascribed to the older ,pliocene epoch is a question which farther inquiries and comparisons must determine4 ,whatever be their date in the tertiary series1 they are quadrupeds which inhabited the country when the formations #e and #e c originated4 ,probably they were drowned during floods1 such as rush down the flanks of volcanos during eruptions1 when great bodies of steam are emitted from the crater1 or when1 as we have seen1 both on ,etna and in ,iceland in modern times1 large masses of snow are suddenly melted by lava1 causing a deluge of water to bear down fragments of igneous rocks mixed with mud1 to the valleys and plains below4 ,it will be seen that the valley of the ,issoire1 down which these ancient inundations swept1 was first excavated at the expense of the formations #b1 #c1 and #d1 and then filled up by the masses #e and #e c1 after which it was re-excavated before the more modern alluviums 7,nos4 #f4 and #g47 were formed4 ,in these again other fossil mammalia of distinct species have been detected by ,m4 ,bravard1 the bones of an hippopotamus having been found among the rest4 ,at length1 when the valley of the ,allier was eroded at ,issoire down to its lowest level1 a talus of angular fragments of basalt and freshwater limestone 7,no4 #h47 was formed1 called the bone-bed of the ,tour de ,boulade1 from which a great many other mammalia have been collected by ,,mm4 ,bravard and ,pomel4 ,in this assemblage the ,elephas primigenius1 ,rhinoceros tichorinus1 ,deer 7including rein-deer71 ,equus1 ,bos1 ,antelope1 ,felis1 and ,canis1 were included4 ,even this deposit seems hardly to be the newest in the neighbourhood1 for if we cross from the town of ,issoire 7see fig4 #dhj47 over ,mont ,perrier to the adjoining valley of the ,couze1 we find another bone-bed 7,no4 #i471 overlaid by a current of lava 7,no4 #aj474 ,the history of this lava-current1 which terminates a few hundred yards below the point ,no4 #aj41 in the suburbs of the village of ,nechers1 is interesting4 ,it forms a long narrow stripe more than #ac miles in length1 at the bottom of the valley of the ,couze1 which flows out of a lake at the foot of ,mont ,dor4 ,this lake is caused by a barrier thrown across the ancient channel of the ,couze1 consisting partly of the volcanic cone called the ,puy de ,tartaret1 formed of loose scoriae1 from the base of which has issued the lava-current before mentioned4 ,the materials of the dam which blocked up the river1 and caused the ,lac de ,chambon1 are also1 in part1 derived from a land-slip which may have happened at the time of the great eruption which formed the cone4 ,this cone of ,tartaret affords an impressive monument of the very different dates at which the igneous eruptions of ,auvergne have happened2 for it was evidently thrown up at the bottom of the existing valley1 which is bounded by lofty precipices composed of sheets of ancient columnar trachyte and basalt1 which once flowed at very high levels from ,mont ,dor4#dbe-;,a ,when we follow the course of the river ,couze1 from its source in the lake of ,chambon1 to the termination of the lava-current at ,nechers1 a distance of thirteen miles1 we find that the torrent has in most places cut a deep channel through the lava1 the lower portion of which is columnar4 ,in some narrow gorges it has even had power to remove the entire mass of basaltic rock1 though the work of erosion must have been very slow1 as the basalt is tough and hard1 and one column after another must have been undermined and reduced to pebbles1 and then to sand4 ,during the time required for this operation1 the perishable cone of ,tartaret1 composed of sand and ashes1 has stood uninjured1 proving that no great flood or deluge can have passed over this region in the interval between the eruption of ,tartaret and our own times4 ,if we now return to the section 7fig4 #dhj471 ,i may observe that the lava-current of ,tartaret1 which has diminished greatly in height and volume near its termination1 presents here a steep and perpendicular face #be feet in height towards the river4 ,beneath it is the alluvium ,no4 #i41 consisting of a red sandy clay1 which must have covered the bottom of the valley when the current of melted rock flowed down4 ,the bones found in this alluvium1 which ,i obtained myself1 consisted of a species of field-mouse1 ,arvicola1 and the molar tooth of an extinct horse1 ,equus fossilis4 ,the other species1 obtained from the same bed1 are referable to the genera ,sus1 ,bos1 ,cervus1 ,felis1 ,canis1 ,martes1 ,talpa1 ,sorex1 ,lepus1 ,sciurus1 ,mus1 and ,lagomys1 in all no less than forty-three species1 all closely allied to recent animals1 yet nearly all of them1 according to ,m4 ,bravard1 showing some points of difference1 like those which ,mr4 ,owen discovered in the case of the horse above alluded to4 ,the bones1 also1 of a frog1 snake1 and lizard1 and of several birds1 were associated with the fossils before enumerated1 and several recent land shells1 such as ,cyclostoma elegans1 ,helix hortensis1 ,h4 nemoralis1 ,h4 lapicida1 and ,clausilia rugosa4 ,if the animals were drowned by floods1 which accompanied the eruptions of the ,puy de ,tartaret1 they would give an exceedingly modern geological date to that event1 which must1 in that case1 have belonged to the ,newer-,pliocene1 or1 perhaps1 the ,post-,pliocene period4 ,that the current1 which has issued from the ,puy de ,tartaret1 may nevertheless be very ancient in reference to the events of human history1 we may conclude1 not only from the divergence of the mammiferous fauna from that of our day1 but from the fact that a ,roman bridge of such form and construction as continued in use down to the fifth century1 but which may be older1 is now seen at a place about a mile and a half from ,st4 ,nectaire4 ,this ancient bridge spans the river ,couze with two arches1 each about #ad feet wide4 ,these arches spring from the lava of ,tartaret1 on both banks1 showing that a ravine precisely like that now existing1 had already been excavated by the river through that lava thirteen or fourteen centuries ago4 ,in ,central ,france there are several hundred minor cones1 like that of ,tartaret1 a great number of which1 like ,monte ,nuovo1 near ,naples1 may have been principally due to a single eruption4 ,most of these cones range in a linear direction from ,auvergne to the ,vivarais1 and they were faithfully described so early as the year #ahjb1 by ,m4 de ,montlosier4 ,they have given rise chiefly to currents of basaltic lava4 ,those of ,auvergne called the ,monts ,dome1 placed on a granitic platform1 form an irregular ridge 7see fig4 #dcf471 about #ah miles in length1 and #b in breadth4 ,they are usually truncated at the summit1 where the crater is often preserved entire1 the lava having issued from the base of the hill4 ,but frequently the crater is broken down on one side1 where the lava has flowed out4 ,the hills are composed of loose scoriae1 blocks of lava1 lapilli1 and pozzuolana1 with fragments of trachyte and granite4 ,puy de ,come4--,the ,puy de ,come and its lava-current1 near ,clermont1 may be mentioned as one of these minor volcanos4 ,this conical hill rises from the granitic platform1 at an angle of about #dj deg41 to the height of more than #ijj feet4 ,its summit presents two distinct craters1 one of them with a vertical depth of #bej feet4 ,a stream of lava takes its rise at the western base of the hill1 instead of issuing from either crater1 and descends the granitic slope towards the present site of the town of ,pont ,gibaud4 ,thence it pours in a broad sheet down a steep declivity into the valley of the ,sioule1 filling the ancient river-channel for the distance of more than a mile4 ,the ,sioule1 thus dispossessed of its bed1 has worked out a fresh one between the lava and the granite of its western bank2 and the excavation has disclosed1 in one spot1 a wall of columnar basalt about #ej feet high4#dbg-;,a ,the excavation of the ravine is still in progress1 every winter some columns of basalt being undermined and carried down the channel of the river1 and in the course of a few miles rolled to sand and pebbles4 ,meanwhile the cone of ,come remains stationary1 its loose materials being protected by a dense vegetation1 and the hill standing on a ridge not commanded by any higher ground whence floods of rain-water may descend4 ,puy ,rouge4--,at another point1 farther down the course of the ,sioule1 we find a second illustration of the same phenomenon in the ,puy ,rouge1 a conical hill to the north of the village of ,pranal4 ,the cone is composed entirely of red and black scoriae1 tuff1 and volcanic bombs4 ,on its western side there is a worn-down crater1 whence a powerful stream of lava has issued1 and flowed into the valley of the ,sioule4 ,the river has since excavated a ravine through the lava and subjacent gneiss1 to the depth of #djj feet4 ,on the upper part of the precipice forming the left side of this ravine1 we see a great mass of black and red scoriaceous lava2 below this a thin bed of gravel1 evidently an ancient river-bed1 now at an elevation of #ej feet above the channel of the ,sioule4 ,the gravel again rests upon gneiss1 which has been eroded to the depth of #ej feet4 ,it is quite evident in this case1 that1 while the basalt was gradually undermined and carried away by the force of running water1 the cone whence the lava issued escaped destruction1 because it stood upon a platform of gneiss several hundred feet above the level of the valley in which the force of running water was exerted4 ,puy de ,pariou4--,the brim of the crater of the ,puy de ,pariou1 near ,clermont1 is so sharp1 and has been so little blunted by time1 that it scarcely affords room to stand upon4 ,this and other cones in an equally remarkable state of integrity have stood1 ,i conceive uninjured1 not in spite of their loose porous nature1 as might at first be naturally supposed1 but in consequence of it4 ,no rills can collect where all the rain is instantly absorbed by the sand and scoriae1 as is remarkably the case on ,etna2 and nothing but a waterspout breaking directly upon the ,puy de ,pariou could carry away a portion of the hill1 so long as it is not rent or engulphed by earthquakes4 ,hence it is conceivable that even those cones which have the freshest aspect1 and most perfect shape1 may lay claim to very high antiquity4 ,dr4 ,daubeny has justly observed1 that had any of these volcanos been in a state of activity in the age of ,julius ,caesar1 that general1 who encamped upon the plains of ,auvergne1 and laid siege to its principal city 7,gergovia1 near ,clermont71 could hardly have failed to notice them4 ,had there been any record of their eruptions in the time of ,pliny or ,sidonius ,apollinaris1 the one would scarcely have omitted to make mention of it in his ,natural ,history1 nor the other to introduce some allusion to it among the descriptions of this his native province4 ,this poet's residence was on the borders of the ,lake ,aidat1 which owed its very existence to the damming up of a river by one of the most modern lava-currents4#dbh-;,a ,velay4--,the observations of ,m4 ,bertrand de ,doue have not yet established that any of the most ancient volcanos of ,velay were in action during the ,eocene period4 ,there are beds of gravel in ,velay1 as in ,auvergne1 covered by lava at different heights above the channels of the existing rivers4 ,in the highest and most ancient of these alluviums the pebbles are exclusively of granitic rocks2 but in the newer1 which are found at lower levels1 and which originated when the valleys had been cut to a greater depth1 an intermixture of volcanic rocks has been observed4 ,at ,st4 ,privat d',allier a bed of volcanic scoriae and tuff was discovered by ,dr4 ,hibbert1 inclosed between two sheets of basaltic lava2 and in this tuff were found the bones of several quadrupeds1 some of them adhering to masses of slaggy lava4 ,among other animals were ,rhinoceros leptorhinus1 ,hyaena spelaea1 and a species allied to the spotted hyaena of the ,cape1 together with four undetermined species of deer4#dbh-;,b ,the manner of the occurrence of these bones reminds us of the published accounts of an eruption of ,coseguina1 #ahce1 in ,central ,america 7see p4 #cii471 during which hot cinders and scoriae fell and scorched to death great numbers of wild and domestic animals and birds4 ,plomb du ,cantal4--,in regard to the age of the igneous rocks of the ,cantal1 we can at present merely affirm1 that they overlie the ,eocene lacustrine strata of that country 7see ,map1 p4 #agi474 ,they form a great dome-shaped mass1 having an average slope of only #d deg41 which has evidently been accumulated1 like the cone of ,etna1 during a long series of eruptions4 ,it is composed of trachytic1 phonolitic1 and basaltic lavas1 tuffs1 and conglomerates1 or breccias1 forming a mountain several thousand feet in height4 ,dikes also of phonolite1 trachyte1 and basalt are numerous1 especially in the neighbourhood of the large cavity1 probably once a crater1 around which the loftiest summits of the ,cantal are ranged circularly1 few of them1 except the ,plomb du ,cantal1 rising far above the border or ridge of this supposed crater4 ,a pyramidal hill1 called the ,puy ,griou1 occupies the middle of the cavity4#dbi-;,a ,it is clear that the volcano of the ,cantal broke out precisely on the site of the lacustrine deposit before described 7p4 #ahh471 which had accumulated in a depression of a tract composed of micaceous schist4 ,in the breccias1 even to the very summit of the mountain1 we find ejected masses of the freshwater beds1 and sometimes fragments of flint1 containing ,eocene shells4 ,valleys radiate in all directions from the central heights of the mountain1 increasing in size as they recede from those heights4 ,those of the ,cer and ,jourdanne1 which are more than #bj miles in length1 are of great depth1 and lay open the geological structure of the mountain4 ,no alternation of lavas with undisturbed ,eocene strata has been observed1 nor any tuffs containing freshwater shells1 although some of these tuffs include fossil remains of terrestrial plants1 said to imply several distinct restorations of the vegetation of the mountain in the intervals between great eruptions4 ,on the northern side of the ,plomb du ,cantal1 at ,la ,vissiere1 near ,murat1 is a spot1 pointed out on the ,map 7p4 #agi471 where freshwater limestone and marl are seen covered by a thickness of about #hjj feet of volcanic rock4 ,shifts are here seen in the strata of limestone and marl4#dbi-;,b ,eocene period4--,in treating of the lacustrine deposits of ,central ,france1 in the fifteenth chapter1 it was stated that1 in the arenaceous and pebbly group of the lacustrine basins of ,auvergne1 ,cantal1 and ,velay1 no volcanic pebbles had ever been detected1 although massive piles of igneous rocks are now found in the immediate vicinity4 ,as this observation has been confirmed by minute research1 we are warranted in inferring that the volcanic eruptions had not commenced when the older subdivisions of the freshwater groups originated4 ,in ,cantal and ,velay no decisive proofs have yet been brought to light that any of the igneous outbursts happened during the deposition of the freshwater strata2 but there can be no doubt that in ,auvergne some volcanic explosions took place before the drainage of the lakes1 and at a time when the ,upper ,eocene species of animals and plants still flourished4 ,thus1 for example1 at ,pont du ,chateau1 near ,clermont1 a section is seen in a precipice on the right bank of the river ,allier1 in which beds of volcanic tuff alternate with a freshwater limestone1 which is in some places pure1 but in others spotted with fragments of volcanic matter1 as if it were deposited while showers of sand and scoriae were projected from a neighbouring vent4#dcj-;,a ,another example occurs in the ,puy de ,marmont1 near ,veyres1 where a freshwater marl alternates with volcanic tuff containing ,eocene shells4 ,the tuff or breccia in this locality is precisely such as is known to result from volcanic ashes falling into water1 and subsiding together with ejected fragments of marl and other stratified rocks4 ,these tuffs and marls are highly inclined1 and traversed by a thick vein of basalt1 which1 as it rises in the hill1 divides into two branches4 ,gergovia4--,the hill of ,gergovia1 near ,clermont1 affords a third example4 ,i agree with ,,mm4 ,dufrenoy and ,jobert that there is no alternation here of a contemporaneous sheet of lava with freshwater strata1 in the manner supposed by some other observers#dcj-;,b2 but the position and contents of some of the associated tuffs1 prove them to have been derived from volcanic eruptions which occurred during the deposition of the lacustrine strata4 ,illustration3 ,fig4 #dha4 ,hill of ,gergovia4 ,the bottom of the hill consists of slightly inclined beds of white and greenish marls1 more than #cjj feet in thickness1 intersected by a dike of basalt1 which may be studied in the ravine above the village of ,merdogne4 ,the dike here cuts through the marly strata at a considerable angle1 producing1 in general1 great alteration and confusion in them for some distance from the point of contact4 ,above the white and green marls1 a series of beds of limestone and marl1 containing freshwater shells1 are seen to alternate with volcanic tuff4 ,in the lowest part of this division1 beds of pure marl alternate with compact fissile tuff1 resembling some of the subaqueous tuffs of ,italy and ,sicily called peperinos4 ,occasionally fragments of scoriae are visible in this rock4 ,still higher is seen another group of some thickness1 consisting exclusively of tuff1 upon which lie other marly strata intermixed with volcanic matter4 ,among the species of fossil shells which ,i found in these strata were ,melania inquinata1 a ,unio1 and a ,melanopsis1 but they were not sufficient to enable me to determine with precision the age of the formation4 ,there are many points in ,auvergne where igneous rocks have been forced by subsequent injection through clays and marly limestones1 in such a manner that the whole has become blended in one confused and brecciated mass1 between which and the basalt there is sometimes no very distinct line of demarcation4 ,in the cavities of such mixed rocks we often find calcedony1 and crystals of mesotype1 stilbite1 and arragonite4 ,to formations of this class may belong some of the breccias immediately adjoining the dike in the hill of ,gergovia2 but it cannot be contended that the volcanic sand and scoriae interstratified with the marls and limestones in the upper part of that hill were introduced1 like the dike1 subsequently1 by intrusion from below4 ,they must have been thrown down like sediment from water1 and can only have resulted from igneous action1 which was going on contemporaneously with the deposition of the lacustrine strata4 ,the reader will bear in mind that this conclusion agrees well with the proofs1 adverted to in the fifteenth chapter1 of the abundance of silex1 travertin1 and gypsum precipitated when the upper lacustrine strata were formed2 for these rocks are such as the waters of mineral and thermal springs might generate4 ,cretaceous period4--,although we have no proof of volcanic rocks erupted in ,england during the deposition of the chalk and greensand1 it would be an error to suppose that no theatres of igneous action existed in the cretaceous period4 ,m4 ,virlet1 in his account of the geology of the ,morea1 p4 #bje41 has clearly shown that certain traps in ,greece1 called by him ophiolites1 are of this date2 as those1 for example1 which alternate conformably with cretaceous limestone and greensand between ,kastri and ,damala in the ,morea4 ,they consist in great part of diallage rocks and serpentine1 and of an amygdaloid with calcareous kernels1 and a base of serpentine4 ,in certain parts of the ,morea1 the age of these volcanic rocks is established by the following proofs3 first1 the lithographic limestones of the ,cretaceous era are cut through by trap1 and then a conglomerate occurs1 at ,nauplia and other places1 containing in its calcareous cement many well-known fossils of the chalk and greensand1 together with pebbles formed of rolled pieces of the same ophiolite1 which appear in the dikes above alluded to4 ,period of ,oolite and ,lias4--,although the green and serpentinous trap rocks of the ,morea belong chiefly to the ,cretaceous era1 as before mentioned1 yet it seems that some eruptions of similar rocks began during the ,oolitic period#dca-;,a2 and it is probable1 that a large part of the trappean masses1 called ophiolites in the ,apennines1 and associated with the limestone of that chain1 are of corresponding age4 ,that part of the volcanic rocks of the ,hebrides1 in our own country1 originated contemporaneously with the ,oolite which they traverse and overlie1 has been ascertained by ,prof4 ,e4 ,forbes1 in #ahej4 ,trap of the ,new ,red ,sandstone period4--,in the southern part of ,devonshire1 trappean rocks are associated with ,new ,red ,sandstone1 and1 according to ,sir ,h4 ,de la ,beche1 have not been intruded subsequently into the sandstone1 but were produced by contemporaneous volcanic action4 ,some beds of grit1 mingled with ordinary red marl1 resemble sands ejected from a crater2 and in the stratified conglomerates occurring near ,tiverton are many angular fragments of trap porphyry1 some of them one or two tons in weight1 intermingled with pebbles of other rocks4 ,these angular fragments were probably thrown out from volcanic vents1 and fell upon sedimentary matter then in the course of deposition4#dcb-;,a ,carboniferous period4--,two classes of contemporaneous trap rocks have been ascertained by ,dr4 ,fleming to occur in the coal-field of the ,forth in ,scotland4 ,the newest of these1 connected with the higher series of coal-measures1 is well exhibited along the shores of the ,forth1 in ,fifeshire1 where they consist of basalt with olivine1 amygdaloid1 greenstone1 wacke1 and tuff4 ,they appear to have been erupted while the sedimentary strata were in a horizontal position1 and to have suffered the same dislocations which those strata have subsequently undergone4 ,in the volcanic tuffs of this age are found not only fragments of limestone1 shale1 flinty slate1 and sandstone1 but also pieces of coal4 ,the other or older class of carboniferous traps are traced along the south margin of ,stratheden1 and constitute a ridge parallel with the ,ochils1 and extending from ,stirling to near ,st4 ,andrews4 ,they consist almost exclusively of greenstone1 becoming1 in a few instances1 earthy and amygdaloidal4 ,they are regularly interstratified with the sandstone1 shale1 and ironstone of the lower ,coal-measures1 and1 on the ,east ,lomond1 with ,mountain ,limestone4 ,i examined these trap rocks in #ahch1 in the cliffs south of ,st4 ,andrews1 where they consist in great part of stratified tuffs1 which are curved1 vertical1 and contorted1 like the associated coal-measures4 ,in the tuff ,i found fragments of carboniferous shale and limestone1 and intersecting veins of greenstone4 ,at one spot1 about two miles from ,st4 ,andrews1 the encroachment of the sea on the cliffs has isolated several masses of trap1 one of which 7fig4 #dhb47 is aptly called the rock and spindle1#dcb-;,b for it consists of a pinnacle of tuff1 which may be compared to a distaff1 and near the base is a mass of columnar greenstone1 in which the pillars radiate from a centre1 and appear at a distance like the spokes of a wheel4 ,the largest diameter of this wheel is about twelve feet1 and the polygonal terminations of the columns are seen round the circumference 7or tire1 as it were1 of the wheel71 as in the accompanying figure4 ,i conceive this mass to be the extremity of a string or vein of greenstone1 which penetrated the tuff4 ,the prisms point in every direction1 because they were surrounded on all sides by cooling surfaces1 to which they always1 arrange themselves at right angles1 as before explained 7p4 #che474 ,illustration3 ,fig4 #dhb4 ,rock and ,spindle1 ,st4 ,andrews4 a4 ,unstratified tuff4 b4 ,columnar greenstone4 c4 ,stratified tuff4 ,illustration3 ,fig4 #dhc4 ,columns of ,greenstone1 seen endwise4 ,a trap dike was pointed out to me by ,dr4 ,fleming1 in the parish of ,flisk1 in the northern part of ,fifeshire1 which cuts through the grey sandstone and shale1 forming the lowest part of the ,old ,red ,sandstone4 ,it may be traced for many miles1 passing through the amygdaloidal and other traps of the hill called ,normans ,law4 ,in its course it affords a good exemplification of the passage from the trappean into the plutonic1 or highly crystalline texture4 ,professor ,gustavus ,rose1 to whom ,i submitted specimens of this dike1 finds the rock1 which he calls dolerite1 to consist of greenish black augite and ,labrador felspar1 the latter being the most abundant ingredient4 ,a small quantity of magnetic iron1 perhaps titaniferous1 is also present4 ,the result of this analysis is interesting1 because both the ancient and modern lavas of ,etna consist in like manner of augite1 ,labradorite1 and titaniferous iron4 ,trap of the ,old ,red sandstone period4--,by referring to the section explanatory of the structure of ,forfarshire1 already given 7p4 #dh471 the reader will perceive that beds of conglomerate1 ,no4 #c41 occur in the middle of the ,old ,red sandstone system1 #a1 #b1 #c1 #d4 ,the pebbles in these conglomerates are sometimes composed of granitic and quartz rocks1 sometimes exclusively of different varieties of trap1 which1 although purposely omitted in the above section1 are often found either intruding themselves in amorphous masses and dikes into the old fossiliferous tilestones1 ,no4 #d41 or alternating with them in conformable beds4 ,all the different divisions of the red sandstone1 #a1 #b1 #c1 #d1 are occasionally intersected by dikes1 but they are very rare in ,nos4 #a4 and #b41 the upper members of the group consisting of red shale and red sandstone4 ,these phenomena1 which occur at the foot of the ,grampians1 are repeated in the ,sidlaw ,hills2 and it appears that in this part of ,scotland1 volcanic eruptions were most frequent in the earlier part of the ,old ,red sandstone period4 ,the trap rocks alluded to consist chiefly of felspathic porphyry and amygdaloid1 the kernels of the latter being sometimes calcareous1 often calcedonic1 and forming beautiful agates4 ,we meet also with claystone1 clinkstone1 greenstone1 compact felspar1 and tuff4 ,some of these rocks flowed as lavas over the bottom of the sea1 and enveloped quartz pebbles which were lying there1 so as to form conglomerates with a base of greenstone1 as is seen in ,lumley ,den1 in the ,sidlaw ,hills4 ,on either side of the axis of this chain of hills 7see section1 p4 #dh471 the beds of massive trap1 and the tuffs composed of volcanic sand and ashes1 dip regularly to the south-east or north-west1 conformably with the shales and sandstones4 ,silurian period4--,it appears from the investigations of ,sir ,r4 ,murchison in ,shropshire1 that when the lower ,silurian strata of that county were accumulating1 there were frequent volcanic eruptions beneath the sea2 and the ashes and scoriae then ejected gave rise to a peculiar kind of tufaceous sandstone or grit1 dissimilar to the other rocks of the ,silurian series1 and only observable in places where syenitic and other trap rocks protrude4 ,these tuffs occur on the flanks of the ,wrekin and ,caer ,caradoc1 and contain ,silurian fossils1 such as casts of encrinites1 trilobites1 and mollusca4 ,although fossiliferous1 the stone resembles a sandy claystone of the trap family4#dce-;,a ,thin layers of trap1 only a few inches thick1 alternate1 in some parts of ,shropshire and ,montgomeryshire1 with sedimentary strata of the lower ,silurian system4 ,this trap consists of slaty porphyry and granular felspar rock1 the beds being traversed by joints like those in the associated sandstone1 limestone1 and shale1 and having the same strike and dip4#dce-;,b ,in ,radnorshire there is an example of twelve bands of stratified trap1 alternating with ,silurian schists and flagstones1 in a thickness of #cej feet4 ,the bedded traps consist of felspar-porphyry1 clinkstone1 and other varieties2 and the interposed ,llandeilo flags are of sandstone and shale1 with trilobites and graptolites4#dce-;,c ,the vast thickness of contemporaneous trappean rocks of lower ,silurian date in ,north ,wales1 explored by our government surveyors1 has been already alluded to4#dce-;,d ,cambrian volcanic rocks4--,professor ,sedgwick1 in his account of the geology of ,cumberland1 has described various trap rocks which accompany the green slates of the ,cambrian system1 beneath all the rocks containing organic remains4 ,different felspathic and porphyritic rocks and greenstones occur1 not only in dikes1 but in conformable beds2 and there is occasionally a passage from these igneous rocks to some of the green quartzose slates4 ,professor ,sedgwick supposes these porphyries to have originated contemporaneously with the stratified chloritic slates1 the materials of the slates having been supplied1 in part at least1 by submarine eruptions oftentimes repeated4#dce-;,e ,,footnotes3 #dbb-;,a ,see the map1 p4 #agi4 #dbc-;,a ,scrope's ,central ,france1 p4 #ih4 #dbc-;,b ,see chaps4 xxiv41 xxv41 and xxvi41 #gth and #hth editions4 #dbc-;,c ,see ,quarterly ,geol4 ,journ41 vol4 ii4 p4 #gg4 #dbe-;,a ,for a view of ,puy de ,tartaret and ,mont ,dor1 see ,scrope's ,volcanos of ,central ,france4 #dbg-;,a ,scrope's ,central ,france1 p4 #fj41 and plate4 #dbh-;,a ,daubeny on ,volcanos1 p4 #ad4 #dbh-;,b ,edin4 ,journ4 of ,sci41 ,no4 iv4 ,n4 ,s4 p4 #bgf4 ,figures of some of these remains are given by ,m4 ,bertrand de ,doue1 ,ann4 ,de la ,soc4 d',agricult4 de ,puy1 #ahbh4 #dbi-;,a ,mem4 de la ,soc4 ,geol4 de ,france1 tom4 i4 p4 #age4 #dbi-;,b ,see ,lyell and ,murchison1 ,ann4 de ,sci4 ,nat41 ,oct4 #ahbi4 #dcj-;,a ,see ,scrope's ,central ,france1 p4 #ba4 #dcj-;,b ,ibid1 p4 #g4 #dca-;,a ,boblaye and ,virlet1 ,morea1 p4 #bc4 #dcb-;,a ,de la ,beche1 ,geol4 ,proceedings1 ,no4 #da4 p4 #aif4 #dcb-;,b ,the rock1 as ,english readers of ,burn's poems may remember1 is a ,scotch term for distaff4 #dce-;,a ,murchison1 ,silurian ,system1 c4 p4 #bcj4 #dce-;,b ,ibid41 p4 #bgb4 #dce-;,c ,ibid41 p4 #cbe4 #dce-;,d ,chap4 ,,xxvii4 p4 #cef4 #dce-;,e ,geol4 ,trans41 #b;d series1 vol4 iv4 p4 #ee4 ,,chapter ,,xxxiii4 ,,plutonic ,,rocks--,,granite4 ,general aspect of granite--,decomposing into spherical masses--,rude columnar structure--,analogy and difference of volcanic and plutonic formations--,minerals in granite1 and their arrangement--,graphic and porphyritic granite--,mutual penetration of crystals of quartz and felspar--,occasional minerals--,syenite--,syenitic1 talcose1 and schorly granites--,eurite--,passage of granite into trap--,examples near ,christiania and in ,aberdeenshire--,analogy in composition of trachyte and granite--,granite veins in ,glen ,tilt1 ,cornwall1 the ,valorsine1 and other countries--,different composition of veins from main body of granite--,metalliferous veins in strata near their junction with granite--,apparent isolation of nodules of granite--,quartz veins--,whether plutonic rocks are ever overlying--,their exposure at the surface due to denudation4 ,the plutonic rocks may be treated of next in order1 as they are most nearly allied to the volcanic class already considered4 ,i have described1 in the first chapter1 these plutonic rocks as the unstratified division of the crystalline or hypogene formations1 and have stated that they differ from the volcanic rocks1 not only by their more crystalline texture1 but also by the absence of tuffs and breccias1 which are the products of eruptions at the earth's surface1 or beneath seas of inconsiderable depth4 ,they differ also by the absence of pores or cellular cavities1 to which the expansion of the entangled gases gives rise in ordinary lava4 ,from these and other peculiarities it has been inferred1 that the granites have been formed at considerable depths in the earth1 and have cooled and crystallized slowly under great pressure1 where the contained gases could not expand4 ,the volcanic rocks1 on the contrary1 although they also have risen up from below1 have cooled from a melted state more rapidly upon or near the surface4 ,from this hypothesis of the great depth at which the granites originated1 has been derived the name of ,plutonic rocks4 ,the beginner will easily conceive that the influence of subterranean heat may extend downwards from the crater of every active volcano to a great depth below1 perhaps several miles or leagues1 and the effects which are produced deep in the bowels of the earth may1 or rather must be1 distinct2 so that volcanic and plutonic rocks1 each different in texture1 and sometimes even in composition1 may originate simultaneously1 the one at the surface1 the other far beneath it4 ,by some writers1 all the rocks now under consideration have been comprehended under the name of granite1 which is1 then1 understood to embrace a large family of crystalline and compound rocks1 usually found underlying all other formations2 whereas we have seen that trap very commonly overlies strata of different ages4 ,granite often preserves a very uniform character throughout a wide range of territory1 forming hills of a peculiar rounded form1 usually clad with a scanty vegetation4 ,the surface of the rock is for the most part in a crumbling state1 and the hills are often surmounted by piles of stones like the remains of a stratified mass1 as in the annexed figure1 and sometimes like heaps of boulders1 for which they have been mistaken4 ,the exterior of these stones1 originally quadrangular1 acquires a rounded form by the action of air and water1 for the edges and angles waste away more rapidly than the sides4 ,a similar spherical structure has already been described as characteristic of basalt and other volcanic formations1 and it must be referred to analogous causes1 as yet but imperfectly understood4 ,illustration3 ,fig4 #dhd4 ,mass of granite near the ,sharp ,tor1 ,cornwall4 ,although it is the general peculiarity of granite to assume no definite shapes1 it is nevertheless occasionally subdivided by fissures1 so as to assume a cuboidal1 and even a columnar1 structure4 ,examples of these appearances may be seen near the ,land's ,end1 in ,cornwall4 7,see figure47 ,illustration3 ,fig4 #dhe4 ,granite having a cuboidal and rude columnar structure1 ,land's ,end1 ,cornwall4 ,the plutonic formations also agree with the volcanic1 in having veins or ramifications proceeding from central masses into the adjoining rocks1 and causing alterations in these last1 which will be presently described4 ,they also resemble trap in containing no organic remains2 but they differ in being more uniform in texture1 whole mountain masses of indefinite extent appearing to have originated under conditions precisely similar4 ,they also differ in never being scoriaceous or amygdaloidal1 and never forming a porphyry with an uncrystalline base1 or alternating with tuffs4 ,nor do they form conglomerates1 although there is sometimes an insensible passage from a fine to a coarse-grained granite1 and occasionally patches of a fine texture are imbedded in a coarser variety4 ,illustration3 ,fig4 #dhf4 ,gneiss4 7,see description1 p4 #dfd47 ,felspar1 quartz1 and mica are usually considered as the minerals essential to granite1 the felspar being most abundant in quantity1 and the proportion of quartz exceeding that of mica4 ,these minerals are united in what is termed a confused crystallization2 that is to say1 there is no regular arrangement of the crystals in granite1 as in gneiss 7see fig4 #dhf471 except in the variety termed graphic granite1 which occurs mostly in granitic veins4 ,this variety is a compound of felspar and quartz1 so arranged as to produce an imperfect laminar structure4 ,the crystals of felspar appear to have been first formed1 leaving between them the space now occupied by the darker-coloured quartz4 ,this mineral1 when a section is made at right angles to the alternate plates of felspar and quartz1 presents broken lines1 which have been compared to ,hebrew characters4 #b ,illustrations3 ,graphic granite4 ,fig4 #dhg4 ,section parallel to the laminae4 ,fig4 #dhh4 ,section transverse to the laminae4 ,as a general rule1 quartz1 in a compact or amorphous state1 forms a vitreous mass1 serving as the base in which felspar and mica have crystallized2 for although these minerals are much more fusible than silex1 they have often imprinted their shapes upon the quartz4 ,this fact1 apparently so paradoxical1 has given rise to much ingenious speculation4 ,we should naturally have anticipated that1 during the cooling of the mass1 the flinty portion would be the first to consolidate2 and that the different varieties of felspar1 as well as garnets and tourmalines1 being more easily liquefied by heat1 would be the last4 ,precisely the reverse has taken place in the passage of most granitic aggregates from a fluid to a solid state1 crystals of the more fusible minerals being found enveloped in hard1 transparent1 glassy quartz1 which has often taken very faithful casts of each1 so as to preserve even the microscopically minute striations on the surface of prisms of tourmaline4 ,various explanations of this phenomenon have been proposed by ,,mm4 de ,beaumont1 ,fournet1 and ,durocher4 ,they refer to ,m4 ,gaudin's experiments on the fusion of quartz1 which show that silex1 as it cools1 has the property of remaining in a viscous state1 whereas alumina never does4 ,this gelatinous flint is supposed to retain a considerable degree of plasticity long after the granitic mixture has acquired a low temperature2 and ,m4 ,e4 de ,beaumont suggests1 that electric action may prolong the duration of the viscosity of silex4 ,occasionally1 however1 we find the quartz and felspar mutually imprinting their forms on each other1 affording evidence of the simultaneous crystallization of both4#dci-;,a ,illustration3 ,fig4 #dhi4 ,porphyritic granite4 ,land's ,end1 ,cornwall4 ,porphyritic granite4--,this name has been sometimes given to that variety in which large crystals of felspar1 sometimes more than #c inches in length1 are scattered through an ordinary base of granite4 ,an example of this texture may be seen in the granite of the ,land's ,end1 in ,cornwall 7fig4 #dhi474 ,the two larger prismatic crystals in this drawing represent felspar1 smaller crystals of which are also seen1 similar in form1 scattered through the base4 ,in this base also appear black specks of mica1 the crystals of which have a more or less perfect hexagonal outline4 ,the remainder of the mass is quartz1 the translucency of which is strongly contrasted to the opaqueness of the white felspar and black mica4 ,but neither the transparency of the quartz1 nor the silvery lustre of the mica1 can be expressed in the engraving4 ,the uniform mineral character of large masses of granite seems to indicate that large quantities of the component elements were thoroughly mixed up together1 and then crystallized under precisely similar conditions4 ,there are1 however1 many accidental1 or occasional1 minerals1 as they are termed1 which belong to granite4 ,among these black schorl or tourmaline1 actinolite1 zircon1 garnet1 and fluor spar1 are not uncommon2 but they are too sparingly dispersed to modify the general aspect of the rock4 ,they show1 nevertheless1 that the ingredients were not everywhere exactly the same2 and a still greater variation may be traced in the ever-varying proportions of the felspar1 quartz1 and mica4 ,syenite4--,when hornblende is the substitute for mica1 which is very commonly the case1 the rock becomes ,syenite3 so called from the celebrated ancient quarries of ,syene in ,egypt4 ,it has all the appearance of ordinary granite1 except when mineralogically examined in hand specimens1 and is fully entitled to rank as a geological member of the same plutonic family as granite4 ,syenite1 however1 after maintaining the granitic character throughout extensive regions1 is not uncommonly found to lose its quartz1 and to pass insensibly into syenitic greenstone1 a rock of the trap family4 ,werner considered syenite as a binary compound of felspar and hornblende1 and regarded quartz as merely one of its occasional minerals4 ,syenitic-granite4--,the quadruple compound of quartz1 felspar1 mica1 and hornblende1 may be so termed4 ,this rock occurs in ,scotland and in ,guernsey4 ,talcose granite1 or ,protogine of the ,french1 is a mixture of felspar1 quartz1 and talc4 ,it abounds in the ,alps1 and in some parts of ,cornwall1 producing by its decomposition the china clay1 more than #ab1jjj tons of which are annually exported from that country for the potteries4#ddj-;,a ,schorl rock1 and schorly granite4--,the former of these is an aggregate of schorl1 or tourmaline1 and quartz4 ,when felspar and mica are also present1 it may be called schorly granite4 ,this kind of granite is comparatively rare4 ,eurite4--,a rock in which all the ingredients of granite are blended into a finely granular mass4 ,crystals of quartz and mica are sometimes scattered through the base of ,eurite4 ,pegmatite4--,a name given by ,french writers to a variety of granite2 a granular mixture of quartz and felspar2 frequent in granite veins2 passes into graphic granite4 ,all these granites pass into certain kinds of trap1 a circumstance which affords one of many arguments in favour of what is now the prevailing opinion1 that the granites are also of igneous origin4 ,the contrast of the most crystalline form of granite1 to that of the most common and earthy trap1 is undoubtedly great2 but each member of the volcanic class is capable of becoming porphyritic1 and the base of the porphyry may be more and more crystalline1 until the mass passes to the kind of granite most nearly allied in mineral composition4 ,the minerals which constitute alike the granitic and volcanic rocks consist1 almost exclusively1 of seven elements1 namely1 silica1 alumina1 magnesia1 lime1 soda1 potash1 and iron2 and these may sometimes exist in about the same proportions in a porous lava1 a compact trap1 or a crystalline granite4 ,it may perhaps be found1 on farther examination--for on this subject we have yet much to learn--that the presence of these elements in certain proportions is more favourable than in others to their assuming a crystalline or true granitic structure2 but it is also ascertained by experiment1 that the same materials may1 under different circumstances1 form very different rocks4 ,the same lava1 for example1 may be glassy1 or scoriaceous1 or stony1 or porphyritic1 according to the more or less rapid rate at which it cools2 and some trachytes and syenitic-greenstones may doubtless form granite and syenite1 if the crystallization take place slowly4 ,it has also been suggested that the peculiar nature and structure of granite may be due to its retaining in it that water which is seen to escape from lavas when they cool slowly1 and consolidate in the atmosphere4 ,boutigny's experiments have shown that melted matter1 at a white heat1 requires to have its temperature lowered before it can vapourize water2 and such discoveries1 if they fail to explain the manner in which granites have been formed1 serve at least to remind us of the entire distinctness of the conditions under which plutonic and volcanic rocks must be produced4#dda-;,a ,it would be easy to multiply examples and authorities to prove the gradation of the granitic into the trap rocks4 ,on the western side of the fiord of ,christiania1 in ,norway1 there is a large district of trap1 chiefly greenstone-porphyry1 and syenitic-greenstone1 resting on fossiliferous strata4 ,to this1 on its southern limit1 succeeds a region equally extensive of syenite1 the passage from the volcanic to the plutonic rock being so gradual that it is impossible to draw a line of demarcation between them4 ,the ordinary granite of ,aberdeenshire1 says ,dr4 ,mac,culloch1 is the usual ternary compound of quartz1 felspar1 and mica2 but sometimes hornblende is substituted for the mica4 ,but in many places a variety occurs which is composed simply of felspar and hornblende2 and in examining more minutely this duplicate compound1 it is observed in some places to assume a fine grain1 and at length to become undistinguishable from the greenstones of the trap family4 ,it also passes in the same uninterrupted manner into a basalt1 and at length into a soft claystone1 with a schistose tendency on exposure1 in no respect differing from those of the trap islands of the western coast4#dda-;,b ,the same author mentions1 that in ,shetland1 a granite composed of hornblende1 mica1 felspar1 and quartz1 graduates in an equally perfect manner into basalt4#dda-;,c ,in ,hungary there are varieties of trachyte1 which1 geologically speaking1 are of modern origin1 in which crystals1 not only of mica1 but of quartz1 are common1 together with felspar and hornblende4 ,it is easy to conceive how such volcanic masses may1 at a certain depth from the surface1 pass downwards into granite4 #b ,illustrations3 ,fig4 #dij4 ,fig4 #dia4 ,junction of granite and argillaceous schist in ,glen ,tilt4 7,mac,culloch47#ddb-;,a ,i have already hinted at the close analogy in the forms of certain granitic and trappean veins2 and it will be found that strata penetrated by plutonic rocks have suffered changes very similar to those exhibited near the contact of volcanic dikes4 ,thus1 in ,glen ,tilt1 in ,scotland1 alternating strata of limestone and argillaceous schist come in contact with a mass of granite4 ,the contact does not take place as might have been looked for1 if the granite had been formed there before the strata were deposited1 in which case the section would have appeared as in fig4 #dij42 but the union is as represented in fig4 #dia41 the undulating outline of the granite intersecting different strata1 and occasionally intruding itself in tortuous veins into the beds of clay-slate and limestone1 from which it differs so remarkably in composition4 ,the limestone is sometimes changed in character by the proximity of the granitic mass or its veins1 and acquires a more compact texture1 like that of hornstone or chert1 with a splintery fracture1 effervescing feebly with acids4 ,the annexed diagram 7fig4 #dib47 represents another junction1 in the same district1 where the granite sends forth so many veins as to reticulate the limestone and schist1 the veins diminishing towards their termination to the thickness of a leaf of paper or a thread4 ,in some places fragments of granite appear entangled1 as it were1 in the limestone1 and are not visibly connected with any larger mass2 while sometimes1 on the other hand1 a lump of the limestone is found in the midst of the granite4 ,the ordinary colour of the limestone of ,glen ,tilt is lead blue1 and its texture large-grained and highly crystalline2 but where it approximates to the granite1 particularly where it is penetrated by the smaller veins1 the crystalline texture disappears1 and it assumes an appearance exactly resembling that of hornstone4 ,the associated argillaceous schist often passes into hornblende slate1 where it approaches very near to the granite4#ddb-;,b ,illustration3 ,fig4 #dib4 ,junction of granite and limestone in ,glen ,tilt4 7,mac,culloch47 a4 ,granite4 b4 ,limestone4 c4 ,blue argillaceous schist4 ,the conversion of the limestone in these and many other instances into a siliceous rock1 effervescing slowly with acids1 would be difficult of explanation1 were it not ascertained that such limestones are always impure1 containing grains of quartz1 mica1 or felspar disseminated through them4 ,the elements of these minerals1 when the rock has been subjected to great heat1 may have been fused1 and so spread more uniformly through the whole mass4 ,illustration3 ,fig4 #dic4 ,granite veins traversing clay slate4 ,table ,mountain1 ,cape of ,good ,hope4#ddc-;,a ,in the plutonic1 as in the volcanic rocks1 there is every gradation from a tortuous vein to the most regular form of a dike1 such as intersect the tuffs and lavas of ,vesuvius and ,etna4 ,dikes of granite may be seen1 among other places1 on the southern flank of ,mount ,battock1 one of the ,grampians1 the opposite walls sometimes preserving an exact parallelism for a considerable distance4 ,as a general rule1 however1 granite veins in all quarters of the globe are more sinuous in their course than those of trap4 ,they present similar shapes at the most northern point of ,scotland1 and the southernmost extremity of ,africa1 as the annexed drawings will show4 ,it is not uncommon for one set of granite veins to intersect another2 and sometimes there are three sets1 as in the environs of ,heidelberg1 where the granite on the banks of the river ,necker is seen to consist of three varieties1 differing in colour1 grain1 and various peculiarities of mineral composition4 ,one of these1 which is evidently the second in age1 is seen to cut through an older granite2 and another1 still newer1 traverses both the second and the first4 ,in ,shetland there are two kinds of granite4 ,one of them1 composed of hornblende1 mica1 felspar1 and quartz1 is of a dark colour1 and is seen underlying gneiss4 ,the other is a red granite1 which penetrates the dark variety everywhere in veins4#ddd-;,a ,illustration3 ,fig4 #did4 ,granite veins traversing gneiss1 ,cape ,wrath4 7,mac,culloch47#ddd-;,b ,illustration3 ,fig4 #die4 ,granite veins traversing gneiss at ,cape ,wrath1 in ,scotland4 7,mac,culloch47 ,the accompanying sketches will explain the manner in which granite veins often ramify and cut each other 7figs4 #did4 and #die474 ,they represent the manner in which the gneiss at ,cape ,wrath1 in ,sutherlandshire1 is intersected by veins4 ,their light colour1 strongly contrasted with that of the hornblende-schist1 here associated with the gneiss1 renders them very conspicuous4 ,granite very generally assumes a finer grain1 and undergoes a change in mineral composition1 in the veins which it sends into contiguous rocks4 ,thus1 according to ,professor ,sedgwick1 the main body of the ,cornish granite is an aggregate of mica1 quartz1 and felspar2 but the veins are sometimes without mica1 being a granular aggregate of quartz and felspar4 ,in other varieties quartz prevails to the almost entire exclusion both of felspar and mica2 in others1 the mica and quartz both disappear1 and the vein is simply composed of white granular felspar4#ddd-;,c ,fig4 #dif4 is a sketch of a group of granite veins in ,cornwall1 given by ,messrs4 ,von ,oeynhausen and ,von ,dechen4#dde-;,a ,the main body of the granite here is of a porphyritic appearance1 with large crystals of felspar2 but in the veins it is fine-grained1 and without these large crystals4 ,the general height of the veins is from #af to #bj feet1 but some are much higher4 ,illustration3 ,fig4 #dif4 ,granite veins passing through hornblende slate1 ,carnsilver ,cove1 ,cornwall4 ,in the ,valorsine1 a valley not far from ,mont ,blanc in ,switzerland1 an ordinary granite1 consisting of felspar1 quartz1 and mica1 sends forth veins into a talcose gneiss 7or stratified protogine71 and in some places lateral ramifications are thrown off from the principal veins at right angles 7see fig4 #dig471 the veins1 especially the minute ones1 being finer grained than the granite in mass4 ,illustration3 ,fig4 #dig4 ,veins of granite in talcose gneiss4 7,l4 ,a4 ,necker47 ,it is here remarked1 that the schist and granite1 as they approach1 seem to exercise a reciprocal influence on each other1 for both undergo a modification of mineral character4 ,the granite1 still remaining unstratified1 becomes charged with green particles2 and the talcose gneiss assumes a granitiform structure without losing its stratification4#dde-;,b ,professor ,keilhau drew my attention to several localities in the country near ,christiania1 where the mineral character of gneiss appears to have been affected by a granite of much newer origin1 for some distance from the point of contact4 ,the gneiss1 without losing its laminated structure1 seems to have become charged with a larger quantity of felspar1 and that of a redder colour1 than the felspar usually belonging to the gneiss of ,norway4 ,granite1 syenite1 and those porphyries which have a granitiform structure1 in short all plutonic rocks1 are frequently observed to contain metals1 at or near their junction with stratified formations4 ,on the other hand1 the veins which traverse stratified rocks are1 as a general law1 more metalliferous near such junctions than in other positions4 ,hence it has been inferred that these metals may have been spread in a gaseous form through the fused mass1 and that the contact of another rock1 in a different state of temperature1 or sometimes the existence of rents in other rocks in the vicinity1 may have caused the sublimation of the metals4#ddf-;,a ,there are many instances1 as at ,markerud1 near ,christiania1 in ,norway1 where the strike of the beds has not been deranged throughout a large area by the intrusion of granite1 both in large masses and in veins4 ,this fact is considered by some geologists to militate against the theory of the forcible injection of granite in a fluid state4 ,but it may be stated in reply1 that ramifying dikes of trap1 which almost all now admit to have been once fluid1 pass through the same fossiliferous strata1 near ,christiania1 without deranging their strike or dip4#ddf-;,b ,illustration3 ,fig4 #dih4 ,general view of junction of granite and schist of the ,valorsine4 7,l4 ,a4 ,necker47 ,the real or apparent isolation of large or small masses of granite detached from the main body1 as at a b1 fig4 #dih41 and above1 fig4 #dib41 and a1 fig4 #dig41 has been thought by some writers to be irreconcilable with the doctrine usually taught respecting veins2 but many of them may1 in fact1 be sections of root-shaped prolongations of granite2 while1 in other cases1 they may in reality be detached portions of rock having the plutonic structure4 ,for there may have been spots in the midst of the invaded strata1 in which there was an assemblage of materials more fusible than the rest1 or more fitted to combine readily into some form of granite4 ,veins of pure quartz are often found in granite1 as in many stratified rocks1 but they are not traceable1 like veins of granite or trap1 to large bodies of rock of similar composition4 ,they appear to have been cracks1 into which siliceous matter was infiltered4 ,such segregation1 as it is called1 can sometimes be shown to have clearly taken place long subsequently to the original consolidation of the containing rock4 ,thus1 for example1 in the gneiss of ,tronstad ,strand1 near ,drammen1 in ,norway1 the annexed section is seen on the beach4 ,it appears that the alternating strata of whitish granitiform gneiss1 and black hornblende-schist1 were first cut through by a greenstone dike1 about #b-a_/b feet wide2 then the crack a b passed through all these rocks1 and was filled up with quartz4 ,the opposite walls of the vein are in some parts incrusted with transparent crystals of quartz1 the middle of the vein being filled up with common opaque white quartz4 ,illustration3 ,fig4 #dii4 a1 b4 ,quartz vein passing through gneiss and greenstone1 ,tronstad ,strand1 near ,christiania4 ,illustration3 ,fig4 #ejj4 ,euritic porphyry alternating with primary fossiliferous strata1 near ,christiania4 ,we have seen that the volcanic formations have been called overlying1 because they not only penetrate others1 but spread over them4 ,mr4 ,necker has proposed to call the granites the underlying igneous rocks1 and the distinction here indicated is highly characteristic4 ,it was indeed supposed by some of the earlier observers1 that the granite of ,christiania1 in ,norway1 was intercalated in mountain masses between the primary or paleozoic strata of that country1 so as to overlie fossiliferous shale and limestone4 ,but although the granite sends veins into these fossiliferous rocks1 and is decidedly posterior in origin1 its actual superposition in mass has been disproved by ,professor ,keilhau1 whose observations on this controverted point ,i had opportunities in #ahcg of verifying4 ,there are1 however1 on a smaller scale1 certain beds of euritic porphyry1 some a few feet1 others many yards in thickness1 which pass into granite1 and deserve perhaps to be classed as plutonic rather than trappean rocks1 which may truly be described as interposed conformably between fossiliferous strata1 as the porphyries 7a c1 fig4 #ejj471 which divide the bituminous shales and argillaceous limestones1 f f4 ,but some of these same porphyries are partially unconformable1 as b1 and may lead us to suspect that the others also1 notwithstanding their appearance of interstratification1 have been forcibly injected4 ,some of the porphyritic rocks above mentioned are highly quartzose1 others very felspathic4 ,in proportion as the masses are more voluminous1 they become more granitic in their texture1 less conformable1 and even begin to send forth veins into contiguous strata4 ,in a word1 we have here a beautiful illustration of the intermediate gradations between volcanic and plutonic rocks1 not only in their mineralogical composition and structure1 but also in their relations of position to associated formations4 ,if the term overlying can in this instance be applied to a plutonic rock1 it is only in proportion as that rock begins to acquire a trappean aspect4 ,it has been already hinted that the heat1 which in every active volcano extends downwards to indefinite depths1 must produce simultaneously very different effects near the surface1 and far below it2 and we cannot suppose that rocks resulting from the crystallizing of fused matter under a pressure of several thousand feet1 much less miles1 of the earth's crust can resemble those formed at or near the surface4 ,hence the production at great depths of a class of rocks analogous to the volcanic1 and yet differing in many particulars1 might almost have been predicted1 even had we no plutonic formations to account for4 ,how well these agree1 both in their positive and negative characters1 with the theory of their deep subterranean origin1 the student will be able to judge by considering the descriptions already given4 ,it has1 however1 been objected1 that if the granitic and volcanic rocks were simply different parts of one great series1 we ought to find in mountain chains volcanic dikes passing upwards into lava1 and downwards into granite4 ,but we may answer1 that our vertical sections are usually of small extent2 and if we find in certain places a transition from trap to porous lava1 and in others a passage from granite to trap1 it is as much as could be expected of this evidence4 ,the prodigious extent of denudation which has been already demonstrated to have occurred at former periods1 will reconcile the student to the belief that crystalline rocks of high antiquity1 although deep in the earth's crust when originally formed1 may have become uncovered and exposed at the surface4 ,their actual elevation above the sea may be referred to the same causes to which we have attributed the upheaval of marine strata1 even to the summits of some mountain chains4 ,but to these and other topics1 ,i shall revert when speaking1 in the next chapter1 of the relative ages of different masses of granite4 ,,footnotes3 #dci-;,a ,bulletin1 #b;d serie1 iv4 #acjd42 and ,archiac1 ,hist4 des ,progres de ,geol41 i4 #ch4 #ddj-;,a ,boase on ,primary ,geology1 p4 #af4 #dda-;,a ,bulletin1 vol4 iv41 #b;d ser41 pp4 #acah4 and #acbj4 #dda-;,b ,syst4 of ,geol41 vol4 i4 p4 #aeg4 #dda-;,c ,ibid41 p4 #aeh4 #ddb-;,a ,geol4 ,trans41 #ast series1 vol4 iii4 pl4 #ba4 #ddb-;,b ,mac,culloch1 ,geol4 ,trans41 vol4 iii4 p4 #bei4 #ddc-;,a ,capt4 ,b4 ,hall1 ,trans4 ,roy4 ,soc4 ,edin41 vol4 vii4 #ddd-;,a ,mac,culloch1 ,syst4 of ,geol41 vol4 i4 p4 #eh4 #ddd-;,b ,western ,islands1 pl4 #ca4 #ddd-;,c ,on ,geol4 of ,cornwall1 ,camb4 ,trans4 vol4 i4 p4 #abd4 #dde-;,a ,phil4 ,mag4 and ,annals1 ,no4 #bg4 new series1 ,march1 #ahbi4 #dde-;,b ,necker1 sur la ,val4 de ,valorsine1 ,mem4 de la ,soc4 de ,phys4 de ,geneve1 #ahbh4 ,i visited1 in #ahcb1 the spot referred to in fig4 #dig4 #ddf-;,a ,necker1 ,proceedings of ,geol4 ,soc41 ,no4 #bf4 p4 #cib4 #ddf-;,b ,see ,keilhau's ,gaea ,norvegica2 ,christiania1 #ahch4 ,,chapter ,,xxxiv4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,plutonic ,,rocks4 ,difficulty in ascertaining the precise age of a plutonic rock--,test of age by relative position--,test by intrusion and alteration--,test by mineral composition--,test by included fragments--,recent and ,pliocene plutonic rocks1 why invisible--,tertiary plutonic rocks in the ,andes--,granite altering ,cretaceous rocks--,granite altering ,lias in the ,alps and in ,skye--,granite of ,dartmoor altering ,carboniferous strata--,granite of the ,old ,red ,sandstone period--,syenite altering ,silurian strata in ,norway--,blending of the same with gneiss--,most ancient plutonic rocks--,granite protruded in a solid form--,on the probable age of the granites of ,arran1 in ,scotland4 ,when we adopt the igneous theory of granite1 as explained in the last chapter1 and believe that different plutonic rocks have originated at successive periods beneath the surface of the planet1 we must be prepared to encounter greater difficulty in ascertaining the precise age of such rocks1 than in the case of volcanic and fossiliferous formations4 ,we must bear in mind1 that the evidence of the age of each contemporaneous volcanic rock was derived1 either from lavas poured out upon the ancient surface1 whether in the sea or in the atmosphere1 or from tuffs and conglomerates1 also deposited at the surface1 and either containing organic remains themselves1 or intercalated between strata containing fossils4 ,but all these tests fail when we endeavour to fix the chronology of a rock which has crystallized from a state of fusion in the bowels of the earth4 ,in that case1 we are reduced to the following tests2 #ast1 relative position2 #b;dly1 intrusion1 and alteration of the rocks in contact2 #c;dly1 mineral characters2 #dthly1 included fragments4 ,test of age by relative position4--,unaltered fossiliferous strata of every age are met with reposing immediately on plutonic rocks2 as at ,christiania1 in ,norway1 where the ,newer ,pliocene deposits rest on granite2 in ,auvergne1 where the freshwater ,eocene strata1 and at ,heidelberg1 on the ,rhine1 where the ,new ,red sandstone1 occupy a similar place4 ,in all these1 and similar instances1 inferiority in position is connected with the superior antiquity of granite4 ,the crystalline rock was solid before the sedimentary beds were superimposed1 and the latter usually contain in them rounded pebbles of the subjacent granite4 ,test by intrusion and alteration4--,but when plutonic rocks send veins into strata1 and alter them near the point of contact1 in the manner before described 7p4 #ddb471 it is clear that1 like intrusive traps1 they are newer than the strata which they invade and alter4 ,examples of the application of this test will be given in the sequel4 ,test by mineral composition4--,notwithstanding a general uniformity in the aspect of plutonic rocks1 we have seen in the last chapter that there are many varieties1 such as ,syenite1 ,talcose granite1 and others4 ,one of these varieties is sometimes found exclusively prevailing throughout an extensive region1 where it preserves a homogeneous character2 so that having ascertained its relative age in one place1 we can easily recognize its identity in others1 and thus determine from a single section the chronological relations of large mountain masses4 ,having observed1 for example1 that the syenitic granite of ,norway1 in which the mineral called zircon abounds1 has altered the ,silurian strata wherever it is in contact1 we do not hesitate to refer other masses of the same zircon-syenite in the south of ,norway to the same era4 ,some have imagined that the age of different granites might1 to a great extent1 be determined by their mineral characters alone2 syenite1 for instance1 or granite with hornblende1 being more modern than common or micaceous granite4 ,but modern investigations have proved these generalizations to have been premature4 ,the syenitic granite of ,norway already alluded to may be of the same age as the ,silurian strata1 which it traverses and alters1 or may belong to the ,old ,red sandstone period2 whereas the granite of ,dartmoor1 although consisting of mica1 quartz1 and felspar1 is newer than the coal4 7,see p4 #def47 ,test by included fragments4--,this criterion can rarely be of much importance1 because the fragments involved in granite are usually so much altered1 that they cannot be referred with certainty to the rocks whence they were derived4 ,in the ,white ,mountains1 in ,north ,america1 according to ,professor ,hubbard1 a granite vein traversing granite1 contains fragments of slate and trap1 which must have fallen into the fissure when the fused materials of the vein were injected from below#dej-;,a1 and thus the granite is shown to be newer than certain superficial slaty and trappean formations4 ,recent and ,pliocene plutonic rocks1 why invisible4--,the explanation already given in the #bith and in the last chapter1 of the probable relation of the plutonic to the volcanic formations1 will naturally lead the reader to infer1 that rocks of the one class can never be produced at or near the surface without some members of the other being formed below simultaneously1 or soon afterwards4 ,it is not uncommon for lava-streams to require more than ten years to cool in the open air2 and where they are of great depth1 a much longer period4 ,the melted matter poured from ,jorullo1 in ,mexico1 in the year #agei1 which accumulated in some places to the height of #eej feet1 was found to retain a high temperature half a century after the eruption4#dej-;,b ,we may conceive1 therefore1 that great masses of subterranean lava may remain in a red-hot or incandescent state in the volcanic foci for immense periods1 and the process of refrigeration may be extremely gradual4 ,sometimes1 indeed1 this process may be retarded for an indefinite period1 by the accession of fresh supplies of heat2 for we find that the lava in the crater of ,stromboli1 one of the ,lipari ,islands1 has been in a state of constant ebullition for the last two thousand years2 and we may suppose this fluid mass to communicate with some caldron or reservoir of fused matter below4 ,in the ,isle of ,bourbon1 also1 where there has been an emission of lava once in every two years for a long period1 the lava below can scarcely fail to have been permanently in a state of liquefaction4 ,if then it be a reasonable conjecture1 that about #bjjj volcanic eruptions occur in the course of every century1 either above the waters of the sea or beneath them#dea-;,a1 it will follow1 that the quantity of plutonic rock generated1 or in progress during the ,recent epoch1 must already have been considerable4 ,but as the plutonic rocks originate at some depth in the earth's crust1 they can only be rendered accessible to human observation1 by subsequent upheaval and denudation4 ,between the period when a plutonic rock crystallizes in the subterranean regions1 and the era of its protrusion at any single point of the surface1 one or two geological periods must usually intervene4 ,hence1 we must not expect to find the ,recent or ,newer ,pliocene granites laid open to view1 unless we are prepared to assume that sufficient time has elapsed since the commencement of the ,newer ,pliocene period for great upheaval and denudation4 ,a plutonic rock1 therefore1 must1 in general1 be of considerable antiquity relatively to the fossiliferous and volcanic formations1 before it becomes extensively visible4 ,as we know that the upheaval of land has been sometimes accompanied in ,south ,america by volcanic eruptions and the emission of lava1 we may conceive the more ancient plutonic rocks to be forced upwards to the surface by the newer rocks of the same class formed successively below1--subterposition in the plutonic1 like superposition in the sedimentary rocks1 being usually characteristic of a newer origin4 ,in the accompanying diagram 7fig4 #eja471 an attempt is made to show the inverted order in which sedimentary and plutonic formations may occur in the earth's crust4 ,the oldest plutonic rock1 ,no4 ,i41 has been upheaved at successive periods until it has become exposed to view in a mountain-chain4 ,this protrusion of ,no4 ,i4 has been caused by the igneous agency which produced the newer plutonic rocks ,nos4 ,,ii4 ,,iii4 and ,,iv4 ,part of the primary fossiliferous strata1 ,no4 #a41 have also been raised to the surface by the same gradual process4 ,it will be observed that the ,recent strata ,no4 #d41 and the ,recent granite or plutonic rock ,no4 ,,iv41 are the most remote from each other in position1 although of contemporaneous date4 ,according to this hypothesis1 the convulsions of many periods will be required before ,recent granite will be upraised so as to form the highest ridges and central axes of mountain-chains4 ,during that time the ,recent strata ,no4 #d4 might be covered by a great many newer sedimentary formations4 ,illustration3 ,fig4 #eja4 ,diagram showing the relative position which the plutonic and sedimentary formations of different ages may occupy4 ,i4 ,primary plutonic4 #d4 ,recent strata4 ,,ii4 ,secondary plutonic4 #c4 ,tertiary strata4 ,,iii4 ,tertiary plutonic4 #b4 ,secondary strata4 ,,iv4 ,recent plutonic4 #a4 ,primary fossiliferous strata4 ,the metamorphic rocks are not indicated in this diagram2 but the student will infer1 from what has been said in ,chap4 ,,xxxii41 that some portions of the stratified formations ,nos4 #a4 and #b4 invaded by granite will have become metamorphic4 ,eocene granite and plutonic rocks4--,in a former part of this volume 7p4 #bje471 the great nummulitic formation of the ,alps and ,pyrenees was referred to the ,eocene period1 and it follows that those vast movements which have raised fossiliferous rocks from the level of the sea to the height of more than #aj1jjj feet above its level have taken place since the commencement of the tertiary epoch4 ,here1 therefore1 if anywhere1 we might expect to find hypogene formations of ,eocene date breaking out in the central axis or most disturbed region of the loftiest chain in ,europe4 ,accordingly1 in the ,swiss ,alps1 even the flysch1 or upper portion of the nummulitic series1 has been occasionally invaded by plutonic rocks1 and converted into crystalline schists of the hypogene class4 ,there can be little doubt that even the talcose granite of ,mont ,blanc itself has been in a fused or pasty state since the flysch was deposited at the bottom of the sea2 and the question as to its age is not so much whether it be a secondary or tertiary granite1 as whether it should be assigned to the ,eocene or ,miocene epoch4 ,great upheaving movements have been experienced in the region of the ,andes1 during the ,post-,pliocene period4 ,in some part1 therefore1 of this chain1 we may expect to discover tertiary plutonic rocks laid open to view4 ,what we already know of the structure of the ,chilian ,andes seems to realize this expectation4 ,in a transverse section1 examined by ,mr4 ,darwin1 between ,valparaiso and ,mendoza1 the ,cordillera was found to consist of two separate and parallel chains1 formed of sedimentary rocks of different ages1 the strata in both resting on plutonic rocks1 by which they have been altered4 ,in the western or oldest range1 called the ,peuquenes1 are black calcareous clay-slates1 rising to the height of nearly #ad1jjj feet above the sea1 in which are shells of the genera ,gryphaea1 ,turritella1 ,terebratula1 and ,ammonite4 ,these rocks are supposed to be of the age of the central parts of the secondary series of ,europe4 ,they are penetrated and altered by dikes and mountain masses of a plutonic rock1 which has the texture of ordinary granite1 but rarely contains quartz1 being a compound of albite and hornblende4 ,the second or eastern chain consists chiefly of sandstones and conglomerates1 of vast thickness1 the materials of which are derived from the ruins of the western chain4 ,the pebbles of the conglomerates are1 for the most part1 rounded fragments of the fossiliferous slates before mentioned4 ,the resemblance of the whole series to certain tertiary deposits on the shores of the ,pacific1 not only in mineral character1 but in the imbedded lignite and silicified woods1 leads to the conjecture that they also are tertiary4 ,yet these strata are not only associated with trap rocks and volcanic tuffs1 but are also altered by a granite consisting of quartz1 felspar1 and talc4 ,they are traversed1 moreover1 by dikes of the same granite1 and by numerous veins of iron1 copper1 arsenic1 silver1 and gold2 all of which can be traced to the underlying granite4#dec-;,a ,we have1 therefore1 strong ground to presume that the plutonic rock1 here exposed on a large scale in the ,chilian ,andes1 is of later date than certain tertiary formations4 ,but the theory adopted in this work of the subterranean origin of the hypogene formations would be untenable1 if the supposed fact here alluded to1 of the appearance of tertiary granite at the surface was not a rare exception to the general rule4 ,a considerable lapse of time must intervene between the formation in the nether regions of plutonic and metamorphic rocks1 and their emergence at the surface4 ,for a long series of subterranean movements must occur before such rocks can be uplifted into the atmosphere or the ocean2 and1 before they can be rendered visible to man1 some strata which previously covered them must usually have been stripped off by denudation4 ,we know that in the ,bay of ,baiae1 in #aech1 in ,cutch in #ahai1 and on several occasions in ,peru and ,chili1 since the commencement of the present century1 the permanent upheaval or subsidence of land has been accompanied by the simultaneous emission of lava at one or more points in the same volcanic region4 ,from these and other examples it may be inferred that the rising or sinking of the earth's crust1 operations by which sea is converted into land1 and land into sea1 are a part only of the consequences of subterranean igneous action4 ,it can scarcely be doubted that this action consists1 in a great degree1 of the baking1 and occasionally the liquefaction1 of rocks1 causing them to assume1 in some cases a larger1 in others a smaller volume than before the application of heat4 ,it consists also in the generation of gases1 and their expansion by heat1 and the injection of liquid matter into rents formed in superincumbent rocks4 ,the prodigious scale on which these subterranean causes have operated in ,sicily since the deposition of the ,newer ,pliocene strata will be appreciated1 when we remember that throughout half the surface of that island such strata are met with1 raised to the height of from #ej to that of #bjjj and even #cjjj feet above the level of the sea4 ,in the same island also the older rocks which are contiguous to these marine tertiary strata must have undergone1 within the same period1 a similar amount of upheaval4 ,the like observations may be extended to nearly the whole of ,europe1 for1 since the commencement of the ,eocene period1 the entire ,european area1 including some of the central and very lofty portions of the ,alps themselves1 as ,i have elsewhere shown#ded-;,a1 has1 with the exception of a few districts1 emerged from the deep to its present altitude2 and even those tracts1 which were already dry land before the ,eocene era1 have almost everywhere acquired additional height4 ,a large amount of subsidence has also occurred during the same period1 so that the extent of the subterranean spaces which have either become the receptacles of sunken fragments of the earth's crust1 or have been rendered capable of supporting other fragments at a much greater height than before1 must be so great that they probably equal1 if not exceed in volume1 the entire continent of ,europe4 ,we are entitled1 therefore1 to ask what amount of change of equivalent importance can be proved to have occurred in the earth's crust within an equal quantity of time anterior to the ,eocene epoch4 ,they who contend for the more intense energy of subterranean causes in the remoter eras of the earth's history1 may find it more difficult to give an answer to this question than they anticipated4 ,the principal effect of volcanic action in the nether regions1 during the tertiary period1 seems to have consisted in the upheaval to the surface of hypogene formations of an age anterior to the carboniferous4 ,the repetition of another series of movements1 of equal violence1 might upraise the plutonic and metamorphic rocks of many secondary periods2 and if the same force should still continue to act1 the next convulsions might bring up to the day the tertiary and recent hypogene rocks4 ,in the course of such changes many of the existing sedimentary strata would suffer greatly by denudation1 others might assume a metamorphic structure1 or become melted down into plutonic and volcanic rocks4 ,meanwhile the deposition of a vast thickness of new strata would not fail to take place during the upheaval and partial destruction of the older rocks4 ,but ,i must refer the reader to the last chapter but one of this volume for a fuller explanation of these views4 ,illustration3 ,fig4 #ejb4 ,block section4 ,cretaceous period4--,it will be shown in the next chapter that chalk1 as well as lias1 has been altered by granite in the eastern ,pyrenees4 ,whether such granite be cretaceous or tertiary cannot easily be decided4 ,suppose b1 c1 d1 to be three members of the ,cretaceous series1 the lowest of which1 b1 has been altered by the granite ,a1 the modifying influence not having extended so far as c1 or having but slightly affected its lowest beds4 ,now it can rarely be possible for the geologist to decide whether the beds d existed at the time of the intrusion of ,a1 and alteration of b and c1 or whether they were subsequently thrown down upon c4 ,as some ,cretaceous rocks1 however1 have been raised to the height of more than #ijjj feet in the ,pyrenees1 we must not assume that plutonic formations of the same age may not have been brought up and exposed by denudation1 at the height of #bjjj or #cjjj feet on the flanks of that chain4 ,period of ,oolite and ,lias4--,in the department of the ,hautes ,alpes1 in ,france1 near ,vizille1 ,m4 ,elie de ,beaumont traced a black argillaceous limestone1 charged with belemnites1 to within a few yards of a mass of granite4 ,here the limestone begins to put on a granular texture1 but is extremely fine-grained4 ,when nearer the junction it becomes grey1 and has a saccharoid structure4 ,in another locality1 near ,champoleon1 a granite composed of quartz1 black mica1 and rose-coloured felspar1 is observed partly to overlie the secondary rocks1 producing an alteration which extends for about #cj feet downwards1 diminishing in the beds which lie farthest from the granite4 7,see fig4 #ejc47 ,in the altered mass the argillaceous beds are hardened1 the limestone is saccharoid1 the grits quartzose1 and in the midst of them is a thin layer of an imperfect granite4 ,it is also an important circumstance that near the point of contact1 both the granite and the secondary rocks become metalliferous1 and contain nests and small veins of blende1 galena1 iron1 and copper pyrites4 ,the stratified rocks become harder and more crystalline1 but the granite1 on the contrary1 softer and less perfectly crystallized near the junction4#def-;,a ,illustration3 ,fig4 #ejc4 ,junction of granite with ,jurassic or ,oolite strata in the ,alps1 near ,champoleon4 ,although the granite is incumbent in the above section 7fig4 #ejc471 we cannot assume that it overflowed the strata1 for the disturbances of the rocks are so great in this part of the ,alps that they seldom retain the position which they must originally have occupied4 ,a considerable mass of syenite1 in the ,isle of ,skye1 is described by ,dr4 ,mac,culloch as intersecting limestone and shale1 which are of the age of the lias4#def-;,b ,the limestone1 which1 at a greater distance from the granite1 contains shells1 exhibits no traces of them near its junction1 where it has been converted into a pure crystalline marble4#def-;,c ,at ,predazzo1 in the ,tyrol1 secondary strata1 some of which are limestones of the ,oolitic period1 have been traversed and altered by plutonic rocks1 one portion of which is an augitic porphyry1 which passes insensibly into granite4 ,the limestone is changed into granular marble1 with a band of serpentine at the junction4#def-;,d ,carboniferous period4--,the granite of ,dartmoor1 in ,devonshire1 was formerly supposed to be one of the most ancient of the plutonic rocks1 but is now ascertained to be posterior in date to the culm-measures of that county1 which1 from their position1 and as containing true coal-plants1 are regarded by ,professor ,sedgwick and ,sir ,r4 ,murchison as members of the true carboniferous series4 ,this granite1 like the syenitic granite of ,christiania1 has broken through the stratified formations without much changing their strike4 ,hence1 on the north-west side of ,dartmoor1 the successive members of the culm-measures abut against the granite1 and become metamorphic as they approach4 ,these strata are also penetrated by granite veins1 and plutonic dikes1 called elvans4#deg-;,a ,the granite of ,cornwall is probably of the same date1 and1 therefore1 as modern as the ,carboniferous strata1 if not much newer4 ,silurian period4--,it has long been known that the granite near ,christiania1 in ,norway1 is of newer origin than the ,silurian strata of that region4 ,von ,buch first announced1 in #ahac1 the discovery of its posteriority in date to limestones containing orthocerata and trilobites4 ,the proofs consist in the penetration of granite veins into the shale and limestone1 and the alteration of the strata1 for a considerable distance from the point of contact1 both of these veins and the central mass from which they emanate4 7,see p4 #ddg47 ,von ,buch supposed that the plutonic rock alternated with the fossiliferous strata1 and that large masses of granite were sometimes incumbent upon the strata2 but this idea was erroneous1 and arose from the fact that the beds of shale and limestone often dip towards the granite up to the point of contact1 appearing as if they would pass under it in mass1 as at a1 fig4 #ejd41 and then again on the opposite side of the same mountain1 as at b1 dip away from the same granite4 ,when the junctions1 however1 are carefully examined1 it is found that the plutonic rock intrudes itself in veins1 and nowhere covers the fossiliferous strata in large overlying masses1 as is so commonly the case with trappean formations4#deg-;,b ,illustration3 ,fig4 #ejd4 ,cross section4 ,now this granite1 which is more modern than the ,silurian strata of ,norway1 also sends veins in the same country into an ancient formation of gneiss2 and the relations of the plutonic rock and the gneiss1 at their junction1 are full of interest when we duly consider the wide difference of epoch which must have separated their origin4 ,illustration3 ,fig4 #eje4 ,granite sending veins into ,silurian strata and ,gneiss1--,christiania1 ,norway4 ,the length of this interval of time is attested by the following facts3--,the fossiliferous1 or ,silurian beds1 rest unconformably upon the truncated edges of the gneiss1 the inclined strata of which had been disturbed and denuded before the sedimentary beds were superimposed 7see fig4 #eje474 ,the signs of denudation are twofold2 first1 the surface of the gneiss is seen occasionally1 on the removal of the newer beds1 containing organic remains1 to be worn and smoothed2 secondly1 pebbles of gneiss have been found in some of the transition strata4 ,between the origin1 therefore1 of the gneiss and the granite there intervened1 first1 the period when the strata of gneiss were inclined2 secondly1 the period when they were denuded2 thirdly1 the period of the deposition of the transition deposits4 ,yet the granite produced1 after this long interval1 is often so intimately blended with the ancient gneiss1 at the point of junction1 that it is impossible to draw any other than an arbitrary line of separation between them2 and where this is not the case1 tortuous veins of granite pass freely through gneiss1 ending sometimes in threads1 as if the older rock had offered no resistance to their passage4 ,it seems necessary1 therefore1 to conceive that the gneiss was softened and more or less melted when penetrated by the granite4 ,but had such junctions alone been visible1 and had we not learnt1 from other sections1 how long a period elapsed between the consolidation of the gneiss and the injection of this granite1 we might have suspected that the gneiss was scarcely solidified1 or had not yet assumed its complete metamorphic character1 when invaded by the plutonic rock4 ,from this example we may learn how impossible it is to conjecture whether certain granites in ,scotland1 and other countries1 which send veins into gneiss and other metamorphic rocks1 are primary1 or whether they may not belong to some secondary or tertiary period4 ,oldest granites4--,it is not half a century since the doctrine was very general that all granitic rocks were primitive1 that is to say1 that they originated before the deposition of the first sedimentary strata1 and before the creation of organic beings 7see above1 p4 #i474 ,but so greatly are our views now changed1 that we find it no easy task to point out a single mass of granite demonstrably more ancient than all the known fossiliferous deposits4 ,could we discover some ,lower ,cambrian strata resting immediately on granite1 there being no alterations at the point of contact1 nor any intersecting granitic veins1 we might then affirm the plutonic rock to have originated before the oldest known fossiliferous strata4 ,still it would be presumptuous to suppose that when a small part only of the globe has been investigated1 we are acquainted with the oldest fossiliferous strata in the crust of our planet4 ,even when these are found1 we cannot assume that there never were any antecedent strata containing organic remains1 which may have become metamorphic4 ,if we find pebbles of granite in a conglomerate of the ,lower ,cambrian system1 we may then feel assured that the parent granite was formed before the ,lower ,cambrian formation4 ,but if the incumbent strata be merely ,silurian or ,upper ,cambrian1 the fundamental granite1 although of high antiquity1 may be posterior in date to known fossiliferous formations4 ,protrusion of solid granite4--,in part of ,sutherlandshire1 near ,brora1 common granite1 composed of felspar1 quartz1 and mica1 is in immediate contact with ,oolitic strata1 and has clearly been elevated to the surface at a period subsequent to the deposition of those strata4#dei-;,a ,professor ,sedgwick and ,sir ,r4 ,murchison conceive that this granite has been upheaved in a solid form2 and that in breaking through the submarine deposits1 with which it was not perhaps originally in contact1 it has fractured them so as to form a breccia along the line of junction4 ,this breccia consists of fragments of shale1 sandstone1 and limestone1 with fossils of the oolite1 all united together by a calcareous cement4 ,the secondary strata1 at some distance from the granite1 are but slightly disturbed1 but in proportion to their proximity the amount of dislocation becomes greater4 ,if we admit that solid hypogene rocks1 whether stratified or unstratified1 have in such cases been driven upwards so as to pierce through yielding sedimentary deposits1 we shall be enabled to account for many geological appearances otherwise inexplicable4 ,thus1 for example1 at ,weinboehla and ,hohnstein1 near ,meissen1 in ,saxony1 a mass of granite has been observed covering strata of the ,cretaceous and ,oolitic periods for the space of between #cjj and #djj yards square4 ,it appears clearly from a recent ,memoir of ,dr4 ,b4 ,cotta on this subject#dei-;,b1 that the granite was thrust into its actual position when solid4 ,there are no intersecting veins at the junction--no alteration as if by heat1 but evident signs of rubbing1 and a breccia in some places1 in which pieces of granite are mingled with broken fragments of the secondary rocks4 ,as the granite overhangs both the lias and chalk1 so the lias is in some places bent over strata of the cretaceous era4 ,relative age of the granites of ,arran4--,in this island1 the largest in the ,firth of ,clyde1 being twenty miles in length from north to south1 the four great classes of rocks1 the fossiliferous1 volcanic1 plutonic1 and metamorphic1 are all conspicuously displayed within a very small area1 and with their peculiar characters strongly contrasted4 ,in the north of the island the granite rises to the height of nearly #cjjj feet above the sea1 terminating in mountainous peaks4 7,see section1 fig4 #ejf47 ,on the flanks of the same mountains are chloritic-schists1 blue roofing-slate1 and other rocks of the metamorphic order 7,no4 #a471 into which the granite 7,no4 #b47 sends veins4 ,this granite1 therefore1 is newer than the hypogene schists 7,no4 #a471 which it penetrates4 ,these schists are highly inclined4 ,upon them rest beds of conglomerate and sandstone 7,no4 #c471 which are referable to the ,old ,red formation1 to which succeed various shales and limestones 7,no4 #d47 containing the fossils of the ,carboniferous period1 upon which are other strata of sandstone and conglomerate 7upper part of ,no4 #d471 in which no fossils have been met with1 which it is conjectured may belong to the ,new ,red sandstone period4 ,all the preceding formations are cut through by the volcanic rocks 7,no4 #e471 which consist of greenstone1 basalt1 pitchstone1 claystone-porphyry1 and other varieties4 ,these appear either in the form of dikes1 or in dense masses from #ej to #gjj feet in thickness1 overlying the strata 7,no4 #d474 ,they sometimes pass into syenite of so crystalline a form1 that it may rank as a plutonic formation2 and in one region1 at ,ploverfield1 in ,glen ,cloy1 a fine-grained granite 7#f4 a7 is seen associated with the trap formation1 and sending veins into the sandstone or into the upper strata of ,no4 #d4 ,this interesting discovery of granite in the southern region of ,arran1 at a point where it is separated from the northern mass of granite by a great thickness of secondary strata and overlying trap1 was made by ,mr4 ,l4 ,a4 ,necker of ,geneva1 during his survey of ,arran in #ahci4 ,we also learn from the recent investigations of ,prof4 ,a4 ,c4 ,ramsay1 that a similar fine-grained granite 7,no4 #f4 b7 appears in the interior of the northern granitic district1 forming the nucleus of it1 and sending veins into the older coarse-grained granite 7,no4 #b474 ,the trap dikes which penetrate the older granite are cut off1 according to ,mr4 ,ramsay1 at the junction of the fine grained4 ,it is not improbable that the granite 7,no4 #f4 b7 may be of the same age as that of ,ploverfield 7,no4 #f4 a71 and this again may belong to the same geological epoch as the trap formations 7,no4 #e474 ,if there be any difference of date1 it would seem that the fine-grained granite must be newer than the trappean rocks4 ,but1 on the other hand1 the coarser granite 7,no4 #b47 may be the oldest rock in ,arran1 with the exception of the hypogene slates 7,no4 #a471 into which it sends veins4 ,illustration3 ,fig4 #ejf4 ,general ,section of ,arran from north to south4 #a4 ,metamorphic or ,hypogene schists1 the oldest formations in ,arran4 #b4 ,coarse-grained granite sending veins into the schists1 ,no4 #a4 #c4 ,old ,red ,sandstone and ,conglomerate containing pebbles exclusively derived from the rocks1 ,no #a41 without any intermixture of granitic fragments4 #d4 ,carboniferous strata and red sandstone 7,new ,red874 #e4 ,trap1 overlying and in dikes1 passing occasionally into ,syenites of the ,plutonic class4 #f4 a4 ,fine-grained granite1 associated with the overlying trap1 ,no4 #e4 #f4 b4 ,similar fine-grained granite1 sending veins into the older granite1 ,no4 #b41 and cutting off the trappean dikes1 c1 d4#dfa-;,a ,an objection may perhaps at first be started to this conclusion1 derived from the curious and striking fact1 the importance of which was first emphatically pointed out by ,dr4 ,mac,culloch1 that no pebbles of granite occur in the conglomerates of the red sandstone in ,arran1 although these conglomerates are several hundred feet in thickness1 and lie at the foot of lofty granite mountains1 which tower above them4 ,as a general rule1 all such aggregates of pebbles and sand are mainly composed of the wreck of pre-existing rocks occurring in the immediate vicinity4 ,the total absence therefore of granitic pebbles has justly been a theme of wonder to those geologists who have successively visited ,arran1 and they have carefully searched there1 as ,i have done myself1 to find an exception1 but in vain4 ,the rounded masses consist exclusively of quartz1 chlorite-schist1 and other members of the metamorphic series2 nor in the newer conglomerates of ,no4 #d4 have any granitic fragments been discovered4 ,are we then entitled to affirm that the coarse-grained granite 7,no4 #b471 like the fine-grained variety 7,no4 #f4 a71 is more modern than all the other rocks of the island8 ,this we cannot assume at present1 but we may confidently infer that when the various beds of sandstone and conglomerate were formed1 no granite had reached the surface1 or had been exposed to denudation in ,arran4 ,it is clear that the crystalline schists were ground into sand and shingle when the strata ,no4 #c4 were deposited1 and at that time the waves had never acted upon the granite1 which now sends its veins into the schist4 ,may we then conclude1 that the schists suffered denudation before they were invaded by granite8 ,this opinion1 although not inadmissible1 is by no means fully borne out by the evidence4 ,for at the time when the ,old ,red sandstone originated1 the metamorphic strata may have formed islands in the sea1 as in fig4 #ejg41 over which the breakers rolled1 or from which torrents and rivers descended1 carrying down gravel and sand4 ,the plutonic rock or granite 7,b7 may even then have been previously injected at a certain depth below1 and yet may never have been exposed to denudation4 ,illustration3 ,fig4 #ejg4 ,cross section4 ,as to the time and manner of the subsequent protrusion of the coarse-grained granite 7,no4 #b471 this rock may have been thrust up bodily1 in a solid form1 during that long series of igneous operations which produced the trappean and plutonic formations 7,nos4 #e41 #f4 a1 and #f4 b74 ,we have shown that these eruptions1 whatever their date1 were posterior to the deposition of all the fossiliferous strata of ,arran4 ,we can also prove that subsequently both the granitic and trappean rocks underwent great aqueous denudation1 which they probably suffered during their emergence from the sea4 ,the fact is demonstrated by the abrupt truncation of numerous dikes1 such as those at c1 d1 e1 which are cut off on the surface of the granite and trap4 ,the overlying trap also ceases very abruptly on approaching the boundary of the great hypogene region1 and terminates in a steep escarpment facing towards it as at f1 fig4 #ejf4 ,when in its original fluid state it could not have come thus suddenly to an end1 but must have filled up the hollow now separating it from the hypogene rocks1 had such a hollow then existed4 ,this necessity of supposing that both the trap and the conglomerate once extended farther1 and that veins such as c1 d1 fig4 #ejf41 were once prolonged farther upwards1 prepares us to believe that the whole of the northern granite may at one time have been covered by newer formations1 under the pressure of which1 before its protrusion1 it assumed its highly crystalline texture4 ,the theory of the protrusion in a solid form of the northern nucleus of granite is confirmed by the manner in which the hypogene slates 7,no4 #a47 and the beds of conglomerate 7,no4 #c47 dip away from it on all sides4 ,in some places indeed the slates are inclined towards the granite1 but this exception might have been looked for1 because these hypogene strata have undergone disturbances at more than one geological epoch1 and may at some points1 perhaps1 have their original order of position inverted4 ,the high inclination1 therefore1 and the quaquaversal dip of the beds around the borders of the granitic boss1 and the comparative horizontality of the fossiliferous strata in the southern part of the island1 are facts which all accord with the hypothesis of a great amount of movement at that point where the granite is supposed to have been thrust up bodily1 and where we may conceive it to have been distended laterally by the repeated injection of fresh supplies of melted materials4#dfc-;,a ,,footnotes3 #dej-;,a ,silliman's ,journ41 ,no4 #fi4 p4 #abc4 #dej-;,b ,see ,principles1 ,index1 ,jorullo4 #dea-;,a ,principles1 ,index1 ,volcanic ,eruptions4 #dec-;,a ,darwin1 pp4 #cij4 #djf42 second edition1 p4 #cai4 #ded-;,a ,see map of ,europe and explanation1 in ,principles1 book i4 #def-;,a ,elie de ,beaumont1 sur les ,montagnes de l',oisans1 c4 ,mem4 de la ,soc4 d',hist4 ,nat4 de ,paris1 tom4 v4 #def-;,b ,see ,murchison1 ,geol4 ,trans41 #b;d series1 vol4 ii4 part ii4 pp4 #caa-cba4 #def-;,c ,western ,islands1 vol4 i4 p4 #ccj4 plate #ah41 figs4 #c1 #d4 #def-;,d ,von ,buch1 ,annales de ,chimie1 c4 #deg-;,a ,proceedings of ,geol4 ,soc41 vol4 ii4 p4 #efb4 #deg-;,b ,see the ,gaea ,norvegica and other works of ,keilhau1 with whom ,i examined this country4 #dei-;,a ,murchison1 ,geol4 ,trans41 #b;d series1 vol4 ii4 p4 #cjg4 #dei-;,b ,geognostische ,wanderungen1 ,leipzig1 #ahch4 #dfa-;,a ,in the above section ,i have attempted to represent the new discoveries made since #ahci1 by ,mr4 ,necker and ,mr4 ,a4 ,c4 ,ramsay1 in regard to the plutonic formations1 #f4 a1 and #f4 b4 #dfc-;,a ,for the geology of ,arran consult the works of ,drs4 ,hutton and ,mac,culloch1 the ,memoirs of ,messrs4 ,von ,dechen and ,oeynhausen1 that of ,professor ,sedgwick and ,sir ,r4 ,murchison 7,geol4 ,trans4 #b;d series71 ,mr4 ,l4 ,a4 ,necker's ,memoir1 read to the ,royal ,soc4 of ,edin4 #bjth ,april1 #ahdj1 and ,mr4 ,ramsay's ,geol4 of ,arran1 #ahda4 ,i examined myself a large part of ,arran in #ahcf4 ,,chapter ,,xxxv4 ,,metamorphic ,,rocks4 ,general character of metamorphic rocks--,gneiss--,hornblende-schist-- ,mica-schist--,clay-slate--,quartzite--, chlorite-schist--,metamorphic limestone--,alphabetical list and explanation of other rocks of this family--,origin of the metamorphic strata--,their stratification is real and distinct from cleavage--,joints and slaty cleavage--,supposed causes of these structures--,how far connected with crystalline action4 ,we have now considered three distinct classes of rocks3 first1 the aqueous1 or fossiliferous2 secondly1 the volcanic2 and1 thirdly1 the plutonic1 or granitic2 and we have now1 lastly1 to examine those crystalline 7or hypogene7 strata to which the name of metamorphic has been assigned4 ,the last-mentioned term expresses1 as before explained1 a theoretical opinion that such strata1 after having been deposited from water1 acquired1 by the influence of heat and other causes1 a highly crystalline texture4 ,they who still question this opinion may call the rocks under consideration the stratified hypogene1 or schistose hypogene formations4 ,these rocks1 when in their most characteristic or normal state1 are wholly devoid of organic remains1 and contain no distinct fragments of other rocks1 whether rounded or angular4 ,they sometimes break out in the central parts of narrow mountain chains1 but in other cases extend over areas of vast dimensions1 occupying1 for example1 nearly the whole of ,norway and ,sweden1 where1 as in ,brazil1 they appear alike in the lower and higher grounds4 ,in ,great ,britain1 those members of the series which approach most nearly to granite in their composition1 as gneiss1 mica-schist1 and hornblende-schist1 are confined to the country north of the rivers ,forth and ,clyde4 ,many attempts have been made to trace a general order of succession or superposition in the members of this family2 gneiss1 for example1 having been often supposed to hold invariably a lower geological position than mica-schist4 ,but although such an order may prevail throughout limited districts1 it is by no means universal1 nor even general1 throughout the globe4 ,to this subject1 however1 ,i shall again revert1 in the last chapter of this volume1 when the chronological relations of the metamorphic rocks are pointed out4 ,the following may be enumerated as the principal members of the metamorphic class3--gneiss1 mica-schist1 hornblende-schist1 clay-slate1 chlorite-schist1 hypogene or metamorphic limestone1 and certain kinds of quartz-rock or quartzite4 ,illustration3 ,fig4 #ejh4 ,fragment of gneiss1 natural size2 section at right angles to planes of stratification4 ,gneiss4--,the first of these1 gneiss1 may be called stratified granite1 being formed of the same materials as granite1 namely1 felspar1 quartz1 and mica4 ,in the specimen here figured1 the white layers consist almost exclusively of granular felspar1 with here and there a speck of mica and grain of quartz4 ,the dark layers are composed of grey quartz and black mica1 with occasionally a grain of felspar intermixed4 ,the rock splits most easily in the plane of these darker layers1 and the surface thus exposed is almost entirely covered with shining spangles of mica4 ,the accompanying quartz1 however1 greatly predominates in quantity1 but the most ready cleavage is determined by the abundance of mica in certain parts of the dark layer4 ,instead of these thin laminae1 gneiss is sometimes simply divided into thick beds1 in which the mica has only a slight degree of parallelism to the planes of stratification4 ,the term gneiss1 however1 in geology is commonly used in a wider sense1 to designate a formation in which the above-mentioned rock prevails1 but with which any one of the other metamorphic rocks1 and more especially hornblende-schist1 may alternate4 ,these other members of the metamorphic series are1 in this case1 considered as subordinate to the true gneiss4 ,the different varieties of rock allied to gneiss1 into which felspar enters as an essential ingredient1 will be understood by referring to what was said of granite4 ,thus1 for example1 hornblende may be superadded to mica1 quartz1 and felspar1 forming a syenitic gneiss2 or talc may be substituted for mica1 constituting talcose gneiss1 a rock composed of felspar1 quartz1 and talc1 in distinct crystals or grains 7stratified protogine of the ,french74 ,hornblende-schist is usually black1 and composed principally of hornblende1 with a variable quantity of felspar1 and sometimes grains of quartz4 ,when the hornblende and felspar are nearly in equal quantities1 and the rock is not slaty1 it corresponds in character with the greenstones of the trap family1 and has been called primitive greenstone4 ,it may be termed hornblende rock4 ,some of these hornblendic masses may really have been volcanic rocks1 which have since assumed a more crystalline or metamorphic texture4 ,mica-schist1 or ,micaceous schist1 is1 next to gneiss1 one of the most abundant rocks of the metamorphic series4 ,it is slaty1 essentially composed of mica and quartz1 the mica sometimes appearing to constitute the whole mass4 ,beds of pure quartz also occur in this formation4 ,in some districts1 garnets in regular twelve-sided crystals form an integrant part of mica-schist4 ,this rock passes by insensible gradations into clay-slate4 ,clay-slate1 or ,argillaceous schist4--,this rock resembles an indurated clay or shale1 is for the most part extremely fissile1 often affording good roofing slate4 ,it may consist of the ingredients of gneiss1 or of an extremely fine mixture of mica and quartz1 or talc and quartz4 ,occasionally it derives a shining and silky lustre from the minute particles of mica or talc which it contains4 ,it varies from greenish or bluish-grey to a lead colour4 ,it may be said of this1 more than of any other schist1 that it is common to the metamorphic and fossiliferous series1 for some clay-slates taken from each division would not be distinguishable by mineralogical characters4 ,quartzite1 or ,quartz rock1 is an aggregate of grains of quartz1 which are either in minute crystals1 or in many cases slightly rounded1 occurring in regular strata1 associated with gneiss or other metamorphic rocks4 ,compact quartz1 like that so frequently found in veins1 is also found together with granular quartzite4 ,both of these alternate with gneiss or mica-schist1 or pass into those rocks by the addition of mica1 or of felspar and mica4 ,chlorite-schist is a green slaty rock1 in which chlorite is abundant in foliated plates1 usually blended with minute grains of quartz1 or sometimes with felspar or mica4 ,often associated with1 and graduating into1 gneiss and clay-slate4 ,hypogene1 or ,metamorphic limestone4--,this rock1 commonly called primary limestone1 is sometimes a thick bedded white crystalline granular marble used in sculpture2 but more frequently it occurs in thin beds1 forming a foliated schist much resembling in colour and appearance certain varieties of gneiss and mica-schist4 ,it alternates with both these rocks1 and in like manner with argillaceous schist4 ,it then usually contains some crystals of mica1 and occasionally quartz1 felspar1 hornblende1 and talc4 ,this member of the metamorphic series enters sparingly into the structure of the hypogene districts of ,norway1 ,sweden1 and ,scotland1 but is largely developed in the ,alps4 ,before offering any farther observations on the probable origin of the metamorphic rocks1 ,i subjoin1 in the form of a glossary1 a brief explanation of some of the principal varieties and their synonymies4 ,,actinolite-,,schist4 ,a slaty foliated rock1 composed chiefly of actinolite1 7an emerald-green mineral1 allied to hornblende17 with some admixture of felspar1 or quartz1 or mica4 ,,ampelite4 ,aluminous slate 7,brongniart72 occurs both in the metamorphic and fossiliferous series4 ,,amphibolite4 ,hornblende rock1 which see4 ,,argillaceous-,,schist1 or ,,clay-,,slate4 ,see p4 #dfe4 ,,arkose4 ,term used by ,brongniart for granular ,quartzite1 which see4 ,,chiastolite-,,slate scarcely differs from clay-slate1 but includes numerous crystals of ,chiastolite2 in considerable thickness in ,cumberland4 ,chiastolite occurs in long slender rhomboidal crystals4 ,for composition1 see ,table1 p4 #cgg4 ,,chlorite-,,schist4 ,a green slaty rock1 in which chlorite1 a green scaly mineral1 is abundant4 ,see p4 #dfe4 ,,clay-,,slate1 or ,,argillaceous-,,schist4 ,see p4 #dfe4 ,,eurite and ,,euritic ,,porphyry4 ,a base of compact felspar1 with grains of laminar felspar1 and often mica and other minerals disseminated 7,brongniart74 ,m4 ,d',aubuisson regards eurite as an extremely fine-grained granite1 in which felspar predominates1 the whole forming an apparently homogeneous rock4 ,eurite has been already mentioned as a plutonic rock1 but occurs also in beds subordinate to gneiss or mica-slate4 ,,gneiss4 ,a stratified or laminated rock1 same composition as granite4 ,see p4 #dfd4 ,,hornblende ,,rock1 or ,,amphibolite4 ,composed of hornblende and felspar4 ,the same composition as hornblende-schist1 stratified1 but not fissile4 ,see p4 #cgf4 ,,hornblende-,,schist1 or ,,slate4 ,composed chiefly of hornblende1 with occasionally some felspar4 ,see p4 #dfd4 ,,hornblendic or ,,syenitic-,,gneiss4 ,composed of felspar1 quartz1 and hornblende4 ,,hypogene ,,limestone4 ,see p4 #dfe4 ,,marble4 ,see p4 #dfe4 ,,mica-,,schist1 or ,,micaceous-,,schist4 ,a slaty rock1 composed of mica and quartz in variable proportions4 ,see p4 #dfe4 ,,mica-,,slate4 ,see ,,mica-,,schist1 p4 #dfe4 ,,phyllade4 ,d',aubuisson's term for clay-slate1 from phullas1 a heap of leaves4 ,,primary ,,limestone4 ,see ,,hypogene ,,limestone1 p4 #dfe4 ,,protogine4 ,see ,,talcose-,,gneiss1 p4 #dfd42 when unstratified it is ,talcose-granite4 ,,quartz ,,rock1 or ,,quartzite4 ,a stratified rock2 an aggregate of grains of quartz4 ,see p4 #dfe4 ,,serpentine occurs in both divisions of the hypogene series1 as a stratified or unstratified rock2 contains much magnesia2 is chiefly composed of the mineral called serpentine1 mixed with diallage1 talc1 and steatite4 ,the pure varieties of this rock1 called noble serpentine1 consist of a hydrated silicate of magnesia1 generally of a greenish colour3 this base is commonly mixed with oxide of iron4 ,,talcose-,,gneiss4 ,same composition as talcose-granite or protogine1 but either stratified or laminated4 ,see p4 #dfd4 ,,talcose-,,schist consists chiefly of talc1 or of talc and quartz1 or of talc and felspar1 and has a texture something like that of clay-slate4 ,,whitestone4 ,same as ,eurite4 ,origin of the ,metamorphic ,strata4 ,having said thus much of the mineral composition of the metamorphic rocks1 ,i may combine what remains to be said of their structure and history with an account of the opinions entertained of their probable origin4 ,at the same time1 it may be well to forewarn the reader that we are here entering upon ground of controversy1 and soon reach the limits where positive induction ends1 and beyond which we can only indulge in speculations4 ,it was once a favourite doctrine1 and is still maintained by many1 that these rocks owe their crystalline texture1 their want of all signs of a mechanical origin1 or of fossil contents1 to a peculiar and nascent condition of the planet at the period of their formation4 ,the arguments in refutation of this hypothesis will be more fully considered when ,i show1 in the last chapter of this volume1 to how many different ages the metamorphic formations are referable1 and how gneiss1 mica-schist1 clay-slate1 and hypogene limestone 7that of ,carrara for example71 have been formed1 not only since the first introduction of organic beings into this planet1 but even long after many distinct races of plants and animals had passed away in succession4 ,the doctrine respecting the crystalline strata1 implied in the name metamorphic1 may properly be treated of in this place2 and we must first inquire whether these rocks are really entitled to be called stratified in the strict sense of having been originally deposited as sediment from water4 ,the general adoption by geologists of the term stratified1 as applied to these rocks1 sufficiently attests their division into beds very analogous1 at least in form1 to ordinary fossiliferous strata4 ,this resemblance is by no means confined to the existence in both of an occasional slaty structure1 but extends to every kind of arrangement which is compatible with the absence of fossils1 and of sand1 pebbles1 ripple-mark1 and other characters which the metamorphic theory supposes to have been obliterated by plutonic action4 ,thus1 for example1 we behold alike in the crystalline and fossiliferous formations an alternation of beds varying greatly in composition1 colour1 and thickness4 ,we observe1 for instance1 gneiss alternating with layers of black hornblende-schist1 or with granular quartz1 or limestone2 and the interchange of these different strata may be repeated for an indefinite number of times4 ,in the like manner1 mica-schist alternates with chlorite-schist1 and with granular limestone in thin layers4 ,as in fossiliferous formations strata of pure siliceous sand alternate with micaceous sand and with layers of clay1 so in the crystalline or metamorphic rocks we have beds of pure quartzite alternating with mica-schist and clay-slate4 ,as in the secondary and tertiary series we meet with limestone alternating again and again with micaceous or argillaceous sand1 so we find in the hypogene1 gneiss and mica-schist alternating with pure and impure granular limestones4 ,it has also been shown that the ripple-mark is very commonly repeated throughout a considerable thickness of fossiliferous strata2 so in mica-schist and gneiss1 there is sometimes an undulation of the laminae on a minute scale1 which may1 perhaps1 be a modification of similar inequalities in the original deposit4 ,in the crystalline formations also1 as in many of the sedimentary before described1 single strata are sometimes made up of laminae placed diagonally1 such laminae not being regularly parallel to the planes of cleavage4 ,illustration3 ,fig4 #eji4 ,lamination of clay-slate1 ,montagne de ,seguinat1 near ,gavarnie1 in the ,pyrenees4 ,this disposition of the layers is illustrated in the accompanying diagram1 in which ,i have represented carefully the stratification of a coarse argillaceous schist1 which ,i examined in the ,pyrenees1 part of which approaches in character to a green and blue roofing slate1 while part is extremely quartzose1 the whole mass passing downwards into micaceous schist4 ,the vertical section here exhibited is about #c feet in height1 and the layers are sometimes so thin that fifty may be counted in the thickness of an inch4 ,some of them consist of pure quartz4 ,the inference drawn from the phenomena above described in favour of the aqueous origin of clay-slate and other crystalline strata1 is greatly strengthened by the fact that many of these metamorphic rocks occasionally alternate with1 and sometimes pass by intermediate gradations into1 rocks of a decidedly mechanical origin1 and exhibiting traces of organic remains4 ,the fossiliferous formations1 moreover1 into which this passage is effected1 are by no means invariably of the same age nor of the highest antiquity1 as will be afterwards explained4 ,stratification of the metamorphic rocks distinct from cleavage4--,the beds into which gneiss1 mica-schist1 and hypogene limestone divide1 exhibit most commonly1 like ordinary strata1 a want of perfect geometrical parallelism4 ,for this reason1 therefore1 in addition to the alternate recurrence of layers of distinct materials1 the stratified arrangement of the crystalline rocks cannot be explained away by supposing it to be simply a divisional structure like that to which we owe some of the slates used for writing and roofing4 ,slaty cleavage1 as it has been called1 has in many cases been produced by the regular deposition of thin plates of fine sediment one upon another2 but there are many instances where it is decidedly unconnected with such a mode of origin1 and where it is not even confined to the aqueous formations4 ,some kinds of trap1 for example1 as clinkstone1 split into laminae1 and are used for roofing4 ,there are1 says ,professor ,sedgwick1 three distinct forms of structure exhibited in certain rocks throughout large districts3 viz4--,first1 stratification2 secondly1 joints2 and thirdly1 slaty cleavage2 the two last having no connection with true bedding1 and having been superinduced by causes absolutely independent of gravitation4 ,all these different structures must have different names1 even though there be some cases where it is impossible1 after carefully studying the appearances1 to decide upon the class to which they belong4#dfi-;,a ,joints4--,now1 in regard to the second of these forms of structure or joints1 they are natural fissures which often traverse rocks in straight and well-determined lines4 ,they afford to the quarryman1 as ,sir ,r4 ,murchison observes1 when speaking of the phenomena1 as exhibited in ,shropshire and the neighbouring counties1 the greatest aid in the extraction of blocks of stone2 and1 if a sufficient number cross each other1 the whole mass of rock is split into symmetrical blocks4#dfi-;,b ,the faces of the joints are for the most part smoother and more regular than the surfaces of true strata4 ,the joints are straight-cut chinks1 often slightly open1 often passing1 not only through layers of successive deposition1 but also through balls of limestone or other matter which have been formed by concretionary action1 since the original accumulation of the strata4 ,such joints1 therefore1 must often have resulted from one of the last changes superinduced upon sedimentary deposits4#dfi-;,c ,in the annexed diagram the flat surfaces of rock ,a1 ,b1 ,c1 represent exposed faces of joints1 to which the walls of other joints1 ,j ,j1 are parallel4 ,s ,s are the lines of stratification2 ,d ,d are lines of slaty cleavage1 which intersect the rock at a considerable angle to the planes of stratification4 ,illustration3 ,fig4 #eaj4 ,stratification1 joints1 and cleavage4 ,joints1 according to ,professor ,sedgwick1 are distinguishable from lines of slaty cleavage in this1 that the rock intervening between two joints has no tendency to cleave in a direction parallel to the planes of the joints1 whereas a rock is capable of indefinite subdivision in the direction of its slaty cleavage4 ,in some cases where the strata are curved1 the planes of cleavage are still perfectly parallel4 ,this has been observed in the slate rocks of part of ,wales 7see fig4 #eaa471 which consist of a hard greenish slate4 ,the true bedding is there indicated by a number of parallel stripes1 some of a lighter and some of a darker colour than the general mass4 ,such stripes are found to be parallel to the true planes of stratification1 wherever these are manifested by ripple-mark1 or by beds containing peculiar organic remains4 ,some of the contorted strata are of a coarse mechanical structure1 alternating with fine-grained crystalline chloritic slates1 in which case the same slaty cleavage extends through the coarser and finer beds1 though it is brought out in greater perfection in proportion as the materials of the rock are fine and homogeneous4 ,it is only when these are very coarse that the cleavage planes entirely vanish4 ,these planes are usually inclined at a very considerable angle to the planes of the strata4 ,in the ,welsh chains1 for example1 the average angle is as much as from #cj deg4 to #dj deg44 ,sometimes the cleavage planes dip towards the same point of the compass as those of stratification1 but more frequently to opposite points4 ,it may be stated as a general rule1 that when beds of coarser materials alternate with those composed of finer particles1 the slaty cleavage is either entirely confined to the fine-grained rock1 or is very imperfectly exhibited in that of coarser texture4 ,this rule holds1 whether the cleavage is parallel to the planes of stratification or not4 ,illustration3 ,fig4 #eaa4 ,parallel planes of cleavage intersecting curved strata4 7,sedgwick47 ,in the ,swiss and ,savoy ,alps1 as ,mr4 ,bakewell has remarked1 enormous masses of limestone are cut through so regularly by nearly vertical partings1 and these are often so much more conspicuous than the seams of stratification1 that an inexperienced observer will almost inevitably confound them1 and suppose the strata to be perpendicular in places where in fact they are almost horizontal4#dgj-;,a ,now these joints are supposed to be analogous to those partings which have been already observed to separate volcanic and plutonic rocks into cuboidal and prismatic masses4 ,on a small scale we see clay and starch when dry split into similar shapes1 which is often caused by simple contraction1 whether the shrinking be due to the evaporation of water1 or to a change of temperature4 ,it is well known that many sandstones and other rocks expand by the application of moderate degrees of heat1 and then contract again on cooling2 and there can be no doubt that large portions of the earth's crust have1 in the course of past ages1 been subjected again and again to very different degrees of heat and cold4 ,these alternations of temperature have probably contributed largely to the production of joints in rocks4 ,in some countries1 as in ,saxony1 where masses of basalt rest on sandstone1 the aqueous rock has for the distance of several feet from the point of junction assumed a columnar structure similar to that of the trap4 ,in like manner some hearthstones1 after exposure to the heat of a furnace without being melted1 have become prismatic4 ,certain crystals also acquire by the application of heat a new internal arrangement1 so as to break in a new direction1 their external form remaining unaltered4 ,sir ,r4 ,murchison observes1 that in referring both joints and slaty cleavage to crystalline action1 we are borne out by a well-known analogy in which crystallization has in like manner given rise to two distinct kinds of structure in the same body4 ,thus1 for example1 in a six-sided prism of quartz1 the planes of cleavage are distinct from those of the prism4 ,it is impossible to cleave the crystals parallel to the plane of the prism1 just as slaty rocks cannot be cleaved parallel to the joints2 but the quartz crystal1 like the older schists1 may be cleaved ad infinitum in the direction of the cleavage planes4#dga-;,a ,it seems1 therefore1 that the fissures called joints may have been the result of different causes1 as of some modification of crystalline action1 or simple contraction during consolidation1 or during a change of temperature4 ,and there are cases where joints may have been due to mechanical violence1 and the strain exerted on strata during their upheaval1 or when they have sunk down below their former level4 ,professor ,phillips has suggested that the previous existence of divisional planes may often have determined1 and must greatly have modified1 the lines and points of fracture caused in rocks by those forces to which they owe their elevation or dislocations4 ,these lines and points being those of least resistance1 cannot fail to have influenced the direction in which the solid mass would give way on the application of external force4 ,professor ,phillips has also remarked that in some slaty rocks the form of the outline of fossil shells and trilobites has been much changed by distortion1 which has taken place in a longitudinal1 transverse1 or oblique direction4 ,this change1 he adds1 seems to be the result of a creeping movement of the particles of the rock along the planes of cleavage1 its direction being always uniform over the same tract of country1 and its amount in space being sometimes measurable1 and being as much as a quarter or even half an inch4 ,the hard shells are not affected1 but only those which are thin4#dga-;,b ,mr4 ,d4 ,sharpe1 following up the same line of inquiry1 came to the conclusion1 that the present distorted forms of the shells in certain ,british slate rocks may be accounted for by supposing that the rocks in which they are imbedded have undergone compression in a direction perpendicular to the planes of cleavage1 and a corresponding expansion in the direction of the dip of the cleavage4#dga-;,c ,mr4 ,darwin infers from his observations1 that in ,south ,america the strike of the cleavage planes is very uniform over wide regions1 and that it corresponds with the strike of the planes of foliation in the gneiss and mica-schists of the same parts of ,chili1 ,tierra del ,fuego1 c4 ,the explanation which he suggests1 is based upon a combination of mechanical and crystalline forces4 ,the planes1 he says1 of cleavage1 and even the foliation of mica-schist and gneiss1 may be intimately connected with the planes of different tension to which the area was long subjected1 after the main fissures or axis of upheavement had been formed1 but before the final consolidation of the mass and the total cessation of all molecular movement4#dgb-;,a ,i have already stated that some extremely fine slates are perfectly parallel to the planes of stratification1 as those of the ,niesen1 for example1 near the ,lake of ,thun1 in ,switzerland1 which contain fucoids1 and are no doubt due to successive aqueous deposition4 ,even where the slates are oblique to the general planes of the strata1 it by no means follows as a matter of course that they have been caused by crystalline action1 for they may be the result of that diagonal lamination which ,i have before described 7p4 #ag474 ,in this case1 however1 there is usually much irregularity1 whereas cleavage planes oblique to the true stratification1 which are referred to a crystalline action1 are often perfectly symmetrical1 and observe a strict geometrical parallelism1 even when the strata are contorted1 as already described 7p4 #dgj474 ,professor ,sedgwick1 speaking of the planes of slaty cleavage1 where they are decidedly distinct from those of sedimentary deposition1 declares his opinion that no retreat of parts1 no contraction in the dimensions of rocks in passing to a solid state1 can account for the phenomenon4 ,it must be referred to crystalline or polar forces acting simultaneously1 and somewhat uniformly1 in given directions1 on large masses having a homogeneous composition4 ,sir ,john ,herschel1 in allusion to slaty cleavage1 has suggested1 that if rocks have been so heated as to allow a commencement of crystallization2 that is to say1 if they have been heated to a point at which the particles can begin to move amongst themselves1 or at least on their own axes1 some general law must then determine the position in which these particles will rest on cooling4 ,probably that position will have some relation to the direction in which the heat escapes4 ,now1 when all1 or a majority of particles of the same nature1 have a general tendency to one position1 that must of course determine a cleavage plane4 ,thus we see the infinitesimal crystals of fresh precipitated sulphate of barytes1 and some other such bodies1 arrange themselves alike in the fluid in which they float2 so as1 when stirred1 all to glance with one light1 and give the appearance of silky filaments4 ,some sorts of soap1 in which insoluble margarates#dgb-;,b exist1 exhibit the same phenomenon when mixed with water2 and what occurs in our experiments on a minute scale may occur in nature on a great one4#dgb-;,c ,,footnotes3 #dfi-;,a ,geol4 ,trans41 #b;d series1 vol4 iii4 p4 #dhj4 #dfi-;,b ,the ,silurian ,system of ,rocks1 as developed in ,salop1 ,hereford1 c41 p4 #bde4 #dfi-;,c ,ibid41 p4 #bdf4 #dgj-;,a ,introduction to ,geology1 chap4 iv4 #dga-;,a ,silurian ,system of ,rocks1 c41 p4 #bdf4 #dga-;,b ,report1 ,brit4 ,ass41 ,cork1 #ahdc1 p4 #fj4 #dga-;,c ,quart4 ,geol4 ,journ41 vol4 iii4 p4 #hg4 #ahdg4 #dgb-;,a ,geol4 ,obs4 on ,s4 ,america1 #ahdf1 p4 #afh4 #dgb-;,b ,margaric acid is an oleaginous acid1 formed from different animal and vegetable fatty substances4 ,a margarate is a compound of this acid with soda1 potash1 or some other base1 and is so named from its pearly lustre4 #dgb-;,c ,letter to the author1 dated ,cape of ,good ,hope1 ,feb4 #bj4 #ahcf4 ,,chapter ,,xxxvi4 ,,metamorphic ,,rocks--continued4 ,strata near some intrusive masses of granite converted into rocks identical with different members of the metamorphic series--,arguments hence derived as to the nature of plutonic action--,time may enable this action to pervade denser masses--,from what kinds of sedimentary rock each variety of the metamorphic class may be derived--,certain objections to the metamorphic theory considered--,lamination of trachyte and obsidian due to motion--,whether some kinds of gneiss have become schistose by a similar action4 ,it has been seen that geologists have been very generally led to infer1 from the phenomena of joints and slaty cleavage1 that mountain masses1 of which the sedimentary origin is unquestionable1 have been acted upon simultaneously by vast crystalline forces4 ,that the structure of fossiliferous strata has often been modified by some general cause since their original deposition1 and even subsequently to their consolidation and dislocation1 is undeniable4 ,these facts prepare us to believe that still greater changes may have been worked out by a greater intensity1 or more prolonged development of the same agency1 combined1 perhaps1 with other causes4 ,now we have seen that1 near the immediate contact of granitic veins and volcanic dikes1 very extraordinary alterations in rocks have taken place1 more especially in the neighbourhood of granite4 ,it will be useful here to add other illustrations1 showing that a texture undistinguishable from that which characterizes the more crystalline metamorphic formations1 has actually been superinduced in strata once fossiliferous4 ,in the southern extremity of ,norway there is a large district1 on the west side of the fiord of ,christiania1 in which granite or syenite protrudes in mountain masses through fossiliferous strata1 and usually sends veins into them at the point of contact4 ,the stratified rocks1 replete with shells and zoophytes1 consist chiefly of shale1 limestone1 and some sandstone1 and all these are invariably altered near the granite for a distance of from #ej to #djj yards4 ,the aluminous shales are hardened and have become flinty4 ,sometimes they resemble jasper4 ,ribboned jasper is produced by the hardening of alternate layers of green and chocolate-coloured schist1 each stripe faithfully representing the original lines of stratification4 ,nearer the granite the schist often contains crystals of hornblende1 which are even met with in some places for a distance of several hundred yards from the junction2 and this black hornblende is so abundant that eminent geologists1 when passing through the country1 have confounded it with the ancient hornblende-schist1 subordinate to the great gneiss formation of ,norway4 ,frequently1 between the granite and the hornblende slate1 above mentioned1 grains of mica and crystalline felspar appear in the schist1 so that rocks resembling gneiss and mica-schist are produced4 ,fossils can rarely be detected in these schists1 and they are more completely effaced in proportion to the more crystalline texture of the beds1 and their vicinity to the granite4 ,in some places the siliceous matter of the schist becomes a granular quartz2 and when hornblende and mica are added1 the altered rock loses its stratification1 and passes into a kind of granite4 ,the limestone1 which at points remote from the granite is of an earthy texture1 blue colour1 and often abounds in corals1 becomes a white granular marble near the granite1 sometimes siliceous1 the granular structure extending occasionally upwards of #djj yards from the junction2 and the corals being for the most part obliterated1 though sometimes preserved1 even in the white marble4 ,both the altered limestone and hardened slate contain garnets in many places1 also ores of iron1 lead1 and copper1 with some silver4 ,these alterations occur equally1 whether the granite invades the strata in a line parallel to the general strike of the fossiliferous beds1 or in a line at right angles to their strike1 as will be seen by the accompanying ground plan4#dgd-;,a ,illustration3 ,fig4 #eab4 ,altered zone of fossiliferous slate and limestone near granite4 ,christiania4 ,the arrows indicate the dip1 and the straight lines the strike1 of the beds4 ,the indurated and ribboned schists above mentioned bear a strong resemblance to certain shales of the coal found at ,russell's ,hall1 near ,dudley1 where coal-mines have been on fire for ages4 ,beds of shale of considerable thickness1 lying over the burning coal1 have been baked and hardened so as to acquire a flinty fracture1 the layers being alternately green and brick-coloured4 ,the granite of ,cornwall1 in like manner1 sends forth veins into a coarse argillaceous-schist1 provincially termed killas4 ,this killas is converted into hornblende-schist near the contact with the veins4 ,these appearances are well seen at the junction of the granite and killas1 in ,st4 ,michael's ,mount1 a small island nearly #cjj feet high1 situated in the bay1 at a distance of about three miles from ,penzance4 ,the granite of ,dartmoor1 in ,devonshire1 says ,sir ,h4 ,de la ,beche1 has intruded itself into the slate and slaty sandstone called greywacke1 twisting and contorting the strata1 and sending veins into them4 ,hence some of the slate rocks have become micaceous2 others more indurated1 and with the characters of mica-slate and gneiss2 while others again appear converted into a hard-zoned rock strongly impregnated with felspar4#dge-;,a ,we learn from the investigations of ,m4 ,dufrenoy1 that in the eastern ,pyrenees there are mountain masses of granite posterior in date to the formations called lias and chalk of that district1 and that these fossiliferous rocks are greatly altered in texture1 and often charged with iron-ore1 in the neighbourhood of the granite4 ,thus in the environs of ,st4 ,martin1 near ,st4 ,paul de ,fenouillet1 the chalky limestone becomes more crystalline and saccharoid as it approaches the granite1 and loses all trace of the fossils which it previously contained in abundance4 ,at some points1 also1 it becomes dolomitic1 and filled with small veins of carbonate of iron1 and spots of red iron-ore4 ,at ,rancie the lias nearest the granite is not only filled with iron-ore1 but charged with pyrites1 tremolite1 garnet1 and a new mineral somewhat allied to felspar1 called1 from the place in the ,pyrenees where it occurs1 couzeranite4 ,now the alterations above described as superinduced in rocks by volcanic dikes and granite veins1 prove incontestably that powers exist in nature capable of transforming fossiliferous into crystalline strata--powers capable of generating in them a new mineral character1 similar1 nay1 often absolutely identical1 with that of gneiss1 mica-schist1 and other stratified members of the hypogene series4 ,the precise nature of these altering causes1 which may provisionally be termed plutonic1 is in a great degree obscure and doubtful2 but their reality is no less clear1 and we must suppose the influence of heat to be in some way connected with the transmutation1 if1 for reasons before explained1 we concede the igneous origin of granite4 ,the experiments of ,gregory ,watt1 in fusing rocks in the laboratory1 and allowing them to consolidate by slow cooling1 prove distinctly that a rock need not be perfectly melted in order that a re-arrangement of its component particles should take place1 and a partial crystallization ensue4#dge-;,b ,we may easily suppose1 therefore1 that all traces of shells and other organic remains may be destroyed2 and that new chemical combinations may arise1 without the mass being so fused as that the lines of stratification should be wholly obliterated4 ,we must not1 however1 imagine that heat alone1 such as may be applied to a stone in the open air1 can constitute all that is comprised in plutonic action4 ,we know that volcanos in eruption not only emit fluid lava1 but give off steam and other heated gases1 which rush out in enormous volume1 for days1 weeks1 or years continuously1 and are even disengaged from lava during its consolidation4 ,when the materials of granite1 therefore1 came in contact with the fossiliferous stratum in the bowels of the earth under great pressure1 the contained gases might be unable to escape2 yet when brought into contact with rocks1 might pass through their pores with greater facility than water is known to do 7p4 #ce474 ,these aeriform fluids1 such as sulphuretted hydrogen1 muriatic acid1 and carbonic acid1 issue in many places from rents in rocks1 which they have discoloured and corroded1 softening some and hardening others4 ,if the rocks are charged with water1 they would pass through more readily2 for1 according to the experiments of ,henry1 water1 under an hydrostatic pressure of #if feet1 will absorb three times as much carbonic acid gas as it can under the ordinary pressure of the atmosphere4 ,although this increased power of absorption would be diminished1 in consequence of the higher temperature found to exist as we descend in the earth1 yet ,professor ,bischoff has shown that the heat by no means augments in such a proportion as to counteract the effect of augmented pressure4#dgf-;,a ,there are other gases1 as well as the carbonic acid1 which water absorbs1 and more rapidly in proportion to the amount of pressure4 ,now even the most compact rocks may be regarded1 before they have been exposed to the air and dried1 in the light of sponges filled with water2 and it is conceivable that heated gases brought into contact with them1 at great depths1 may be absorbed readily1 and transfused through their pores4 ,although the gaseous matter first observed would soon be condensed1 and part with its heat1 yet the continual arrival of fresh supplies from below might1 in the course of ages1 cause the temperature of the water1 and with it that of the containing rock1 to be materially raised4 ,m4 ,fournet1 in his description of the metalliferous gneiss near ,clermont1 in ,auvergne1 states that all the minute fissures of the rock are quite saturated with free carbonic acid gas1 which rises plentifully from the soil there and in many parts of the surrounding country4 ,the various elements of the gneiss1 with the exception of the quartz1 are all softened2 and new combinations of the acid1 with lime1 iron1 and manganese1 are continually in progress4#dgf-;,b ,another illustration of the power of subterranean gases is afforded by the stufas of ,st4 ,calogero1 situated in the largest of the ,lipari ,islands4 ,here1 according to the description published by ,hoffmann1 horizontal strata of tuff1 extending for #d miles along the coast1 and forming cliffs more than #bjj feet high1 have been discoloured in various places1 and strangely altered by the all-penetrating vapours4 ,dark clays have become yellow1 or often snow-white2 or have assumed a chequered or brecciated appearance1 being crossed with ferruginous red stripes4 ,in some places the fumaroles have been found by analysis to consist partly of sublimations of oxide of iron2 but it also appears that veins of chalcedony and opal1 and others of fibrous gypsum1 have resulted from these volcanic exhalations4#dgf-;,c ,the reader may also refer to ,m4 ,virlet's account of the corrosion of hard1 flinty1 and jaspideous rocks near ,corinth1 by the prolonged agency of subterranean gases#dgg-;,a2 and to ,dr4 ,daubeny's description of the decomposition of trachytic rocks in the ,solfatara1 near ,naples1 by sulphuretted hydrogen and muriatic acid gases4#dgg-;,b ,although in all these instances we can only study the phenomena as exhibited at the surface1 it is clear that the gaseous fluids must have made their way through the whole thickness of porous or fissured rocks1 which intervene between the subterranean reservoirs of gas and the external air4 ,the extent1 therefore1 of the earth's crust1 which the vapours have permeated and are now permeating1 may be thousands of fathoms in thickness1 and their heating and modifying influence may be spread throughout the whole of this solid mass4 ,we learn from ,professor ,bischoff that the steam of a hot spring at ,aix-la-,chapelle1 although its temperature is only from #acc deg4 to #afg deg4 ,f41 has converted the surface of some blocks of black marble into a doughy mass4 ,he conceives1 therefore1 that steam in the bowels of the earth having a temperature equal or even greater than the melting point of lava1 and having an elasticity of which even ,papin's digester can give but a faint idea1 may convert rocks into liquid matter4#dgg-;,c ,the above observations are calculated to meet some of the objections which have been urged against the metamorphic theory on the ground of the small power of rocks to conduct heat2 for it is well known that rocks1 when dry and in the air1 differ remarkably from metals in this respect4 ,it has been asked how the changes which extend merely for a few feet from the contact of a dike could have penetrated through mountain masses of crystalline strata several miles in thickness4 ,now it has been stated that the plutonic influence of the syenite of ,norway has sometimes altered fossiliferous strata for a distance of a quarter of a mile1 both in the direction of their dip and of their strike4 7,see fig4 #eab4 p4 #dgd47 ,this is undoubtedly an extreme case2 but is it not far more philosophical to suppose that this influence may1 under favourable circumstances1 affect denser masses1 than to invent an entirely new cause to account for effects merely differing in quantity1 and not in kind8 ,the metamorphic theory does not require us to affirm that some contiguous mass of granite has been the altering power2 but merely that an action1 existing in the interior of the earth at an unknown depth1 whether thermal1 electrical1 or other1 analogous to that exerted near intruding masses of granite1 has1 in the course of vast and indefinite periods1 and when rising perhaps from a large heated surface1 reduced strata thousands of yards thick to a state of semi-fusion1 so that on cooling they have become crystalline1 like gneiss4 ,granite may have been another result of the same action in a higher state of intensity1 by which a thorough fusion has been produced2 and in this manner the passage from granite into gneiss may be explained4 ,some geologists are of opinion1 that the alternate layers of mica and quartz1 or mica and felspar1 or lime and felspar1 are so much more distinct1 in certain metamorphic rocks1 than the ingredients composing alternate layers in many sedimentary deposits1 that the similar particles must be supposed to have exerted a molecular attraction for each other1 and to have thus congregated together in layers more distinct in mineral composition than before they were crystallized4 ,in considering1 then1 the various data already enumerated1 the forms of stratification in metamorphic rocks1 their passage on the one hand into the fossiliferous1 and on the other into the plutonic formations1 and the conversions which can be ascertained to have occurred in the vicinity of granite1 we may conclude that gneiss and mica-schist may be nothing more than altered micaceous and argillaceous sandstones that granular quartz may have been derived from siliceous sandstone1 and compact quartz from the same materials4 ,clay-slate may be altered shale1 and granular marble may have originated in the form of ordinary limestone1 replete with shells and corals1 which have since been obliterated2 and1 lastly1 calcareous sands and marls may have been changed into impure crystalline limestones4 ,hornblende-schist1 says ,dr4 ,mac,culloch1 may at first have been mere clay2 for clay or shale is found altered by trap into ,lydian stone1 a substance differing from hornblende-schist almost solely in compactness and uniformity of texture4#dgh-;,a ,in ,shetland1 remarks the same author1 argillaceous-schist 7or clay-slate71 when in contact with granite1 is sometimes converted into hornblende-schist1 the schist becoming first siliceous1 and ultimately1 at the contact1 hornblende-schist4#dgh-;,b ,the anthracite and plumbago associated with hypogene rocks may have been coal2 for not only is coal converted into anthracite in the vicinity of some trap dikes1 but we have seen that a like change has taken place generally even far from the contact of igneous rocks1 in the disturbed region of the ,appalachians4#dgh-;,c ,at ,worcester1 in the state of ,massachusetts1 #de miles due west of ,boston1 a bed of plumbago and impure anthracite occurs1 interstratified with mica-schist4 ,it is about #b feet in thickness1 and has been made use of both as fuel1 and in the manufacture of lead pencils4 ,at the distance of #cj miles from the plumbago1 there occurs1 on the borders of ,rhode ,island1 an impure anthracite in slates1 containing impressions of coal-plants of the genera ,pecopteris1 ,neuropteris1 ,calamites1 c4 ,this anthracite is intermediate in character between that of ,pennsylvania and the plumbago of ,worcester1 in which last the gaseous or volatile matter 7hydrogen1 oxygen1 and nitrogen7 is to the carbon only in the proportion of #c per cent4 ,after traversing the country in various directions1 ,i came to the conclusion that the carboniferous shales or slates with anthracite and plants1 which in ,rhode ,island often pass into mica-schist1 have at ,worcester assumed a perfectly crystalline and metamorphic texture2 the anthracite having been nearly transmuted into that state of pure carbon which is called plumbago or graphite4#dgi-;,a ,the total absence of any trace of fossils has inclined many geologists to attribute the origin of crystalline strata to a period antecedent to the existence of organic beings4 ,admitting1 they say1 the obliteration1 in some cases1 of fossils by plutonic action1 we might still expect that traces of them would oftener occur in certain ancient systems of slate1 in which1 as in ,cumberland1 some conglomerates occur4 ,but in urging this argument1 it seems to have been forgotten that there are stratified formations of enormous thickness1 and of various ages1 and some of them very modern1 all formed after the earth had become the abode of living creatures1 which are1 nevertheless1 in certain districts1 entirely destitute of all vestiges of organic bodies4 ,in some1 the traces of fossils may have been effaced by water and acids1 at many successive periods2 and it is clear1 that1 the older the stratum1 the greater is the chance of its being non-fossiliferous1 even if it has escaped all metamorphic action4 ,it has been also objected to the metamorphic theory1 that the chemical composition of the secondary strata differs essentially from that of the crystalline schists1 into which they are supposed to be convertible4#dgi-;,b ,the primary schists1 it is said1 usually contain a considerable proportion of potash or of soda1 which the secondary clays1 shales1 and slates do not1 these last being the result of the decomposition of felspathic rocks1 from which the alkaline matter has been abstracted during the process of decomposition4 ,but this reasoning proceeds on insufficient and apparently mistaken data2 for a large portion of what is usually called clay1 marl1 shale1 and slate does actually contain a certain1 and often a considerable1 proportion of alkali2 so that it is difficult1 in many countries1 to obtain clay or shale sufficiently free from alkaline ingredients to allow of their being burnt into bricks or used for pottery4 ,thus the argillaceous shales and slates of the ,old ,red sandstone1 in ,forfarshire and other parts of ,scotland1 are so much charged with alkali1 derived from triturated felspar1 that1 instead of hardening when exposed to fire1 they sometimes melt into a glass4 ,they contain no lime1 but appear to consist of extremely minute grains of the various ingredients of granite1 which are distinctly visible in the coarser-grained varieties1 and in almost all the interposed sandstones4 ,these laminated clays and shales might certainly1 if crystallized1 resemble in composition many of the primary strata4 ,there is also potash in fossil vegetable remains1 and soda in the salts by which strata are sometimes so largely impregnated1 as in ,patagonia4 ,another objection has been derived from the alternation of highly crystalline strata with others having a less crystalline texture4 ,the heat1 it is said1 in its ascent from below1 must have traversed the less altered schists before it reached a higher and more crystalline bed4 ,in answer to this1 it may be observed1 that if a number of strata differing greatly in composition from each other be subjected to equal quantities of heat1 there is every probability that some will be more fusible than others4 ,some1 for example1 will contain soda1 potash1 lime1 or some other ingredient capable of acting as a flux2 while others may be destitute of the same elements1 and so refractory as to be very slightly affected by a degree of heat capable of reducing others to semi-fusion4 ,nor should it be forgotten that1 as a general rule1 the less crystalline rocks do really occur in the upper1 and the more crystalline in the lower part of each metamorphic series4 ,there are geologists1 however1 of high authority1 who admit the metamorphic origin of gneiss and mica-schist even on a grand scale in some mountain-chains1 and who nevertheless believe that gneiss has in some instances been an eruptive rock1 deriving its lamination from motion when in a fluid or viscous state4 ,mr4 ,scrope1 in his description of the ,ponza ,islands1 ascribes the zoned structure of the ,hungarian perlite 7a semi-vitreous trachyte7 to its having subsided1 in obedience to the impulse of its own gravity1 down a slightly inclined plane1 while possessed of an imperfect fluidity4 ,in the islands of ,ponza and ,palmarola1 the direction of the zones is more frequently vertical than horizontal1 because the mass was impelled from below upwards4#dhj-;,a ,in like manner1 ,mr4 ,darwin attributes the lamination and fissile structure of volcanic rocks of the trachytic series1 including some obsidians in ,ascension1 ,mexico1 and elsewhere1 to their having moved when liquid in the direction of the laminae4 ,the zones consist sometimes of layers of air-cells drawn out and lengthened in the supposed direction of the moving mass4 ,he compares this division into parallel zones1 thus caused by the stretching of a pasty mass as it flowed slowly onwards1 to the zoned or ribboned structure of ice1 which ,professor ,james ,forbes has so ably explained1 showing that it is due to the fissuring of a viscous body in motion4#dhj-;,b ,mr4 ,darwin also imagines the lamination or foliation1 as he terms it1 of gneiss and mica-schist in ,south ,america to be the extreme result of that process of which cleavage is the first effect4#dhj-;,c ,m4 ,elie de ,beaumont1 while he regards the greater part of the gneiss and mica-schist of the ,alps as sedimentary strata altered by plutonic action1 still conceives that some of the ,alpine gneiss may have been erupted1 or1 in other words1 may be granite drawn out into parallel laminae in the manner of trachyte as above alluded to4#dhj-;,d ,opinions such as these1 and others which might be cited1 prove the difficulty of arriving at clear theoretical views on this subject4 ,i may also add another difficulty4 ,in many extensive regions experienced geologists have been at a loss to decide which of two sets of divisional planes were referable to cleavage and which to stratification2 and that1 too1 where the rocks are of undisputed aqueous origin4 ,after much doubt1 they have sometimes discovered that they had at first mistaken the lines of cleavage for those of deposition1 because the former were by far the most marked of the two4 ,now if such slaty masses should become highly crystalline1 and be converted into gneiss1 hornblende-schist1 or any other member of the hypogene class1 the cleavage planes would be more likely to remain visible than those of stratification4 ,but although the cause last-mentioned may1 in some instances1 be a vera causa1 as applied to gneiss and mica-schist1 ,i believe it to be an exception to the general rule4 ,nor would it1 ,i conceive1 produce that kind of irregular parallelism in the laminae which belongs to so many of the hypogene rocks of the ,grampians1 ,pyrenees1 and the ,white mountains of ,north ,america1 where ,i have chiefly studied them4 ,but it will be impossible for the reader duly to appreciate the propriety of the term metamorphic1 as applied to the strata formerly called primitive1 until ,i have shown1 in the next chapter1 at how many distinct periods these crystalline strata have been formed4 ,,footnotes3 #dgd-;,a ,keilhau1 ,gaea ,norvegica1 pp4 #fa-fc4 #dge-;,a ,geol4 ,manual1 p4 #dgi4 #dge-;,b ,phil4 ,trans41 #ahjd4 #dgf-;,a ,poggendorf's ,annalen1 ,no4 xvi41 #b;d series1 vol4 iii4 #dgf-;,b ,see ,principles1 ,index1 ,carbonated ,springs1 c4 #dgf-;,c ,hoffmann's ,liparischen ,inseln1 p4 #ch4 ,leipzig1 #ahcb4 #dgg-;,a ,see ,princ4 of ,geol42 and ,bulletin de la ,soc4 ,geol4 de ,france1 tom4 ii4 p4 #bcj4 #dgg-;,b ,see ,princ4 of ,geol42 and ,daubeny's ,volcanos1 p4 #afg4 #dgg-;,c ,jam4 ,ed4 ,new ,phil4 ,journ41 ,no4 #ea4 p4 #dc4 #dgh-;,a ,syst4 of ,geol41 vol4 i4 p4 #baj4 #dgh-;,b ,ibid41 p4 #baa4 #dgh-;,c ,see above1 pp4 #cbg1 #ccc4 #dgi-;,a ,see ,lyell1 ,quart4 ,geol4 ,journ41 vol4 i4 p4 #aii4 #dgi-;,b ,dr4 ,boase1 ,primary ,geology1 p4 #cai4 #dhj-;,a ,geol4 ,trans41 #b;d series1 vol4 ii4 p4 #bbg4 #dhj-;,b ,darwin1 ,volcanic ,islands1 pp4 #fi1 #gj4 #dhj-;,c ,geol4 ,obs4 in ,s4 ,america1 p4 #afg4 ,see also above1 p4 #dga4 #dhj-;,d ,bulletin1 vol4 iv4 p4 #acja4 ,,chapter ,,xxxvii4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,metamorphic ,,rocks4 ,age of each set of metamorphic strata twofold--,test of age by fossils and mineral character not available--,test by superposition ambiguous--,conversion of dense masses of fossiliferous strata into metamorphic rocks--,limestone and shale of ,carrara--,metamorphic strata of modern periods in the ,alps of ,switzerland and ,savoy--,why the visible crystalline strata are none of them very modern--,order of succession in metamorphic rocks--,uniformity of mineral character--,why the metamorphic strata are less calcareous than the fossiliferous4 ,according to the theory adopted in the last chapter1 the age of each set of metamorphic strata is twofold--they have been deposited at one period1 they have become crystalline at another4 ,we can rarely hope to define with exactness the date of both these periods1 the fossils having been destroyed by plutonic action1 and the mineral characters being the same1 whatever the age4 ,superposition itself is an ambiguous test1 especially when we desire to determine the period of crystallization4 ,suppose1 for example1 we are convinced that certain metamorphic strata in the ,alps1 which are covered by cretaceous beds1 are altered lias2 this lias may have assumed its crystalline texture in the cretaceous or in some tertiary period1 the ,eocene for example4 ,if in the latter1 it should be called ,eocene when regarded as a metamorphic rock1 although it be liassic when considered in reference to the era of its deposition4 ,according to this view1 the superposition of chalk does not prevent the subjacent metamorphic rock from being ,eocene4 ,if1 however1 in the progress of science1 we should succeed in ascertaining the twofold chronological relations of the metamorphic formations1 it might be useful to adopt a twofold terminology4 ,we might call the strata above alluded to ,liassic-,eocene1 or ,liassic-,cretaceous strata of the ,hypogene class2 the first term referring to the era of deposition1 the second to that of crystallization4 ,when discussing the ages of the plutonic rocks1 we have seen that examples occur of various primary1 secondary1 and tertiary deposits converted into metamorphic strata1 near their contact with granite4 ,there can be no doubt in these cases that strata1 once composed of mud1 sand1 and gravel1 or of clay1 marl1 and shelly limestone1 have for the distance of several yards1 and in some instances several hundred feet1 been turned into gneiss1 mica-schist1 hornblende-schist1 chlorite-schist1 quartz rock1 statuary marble1 and the rest4 7,see the two preceding ,chapters47 ,but when the metamorphic action has operated on a grander scale1 it tends entirely to destroy all monuments of the date of its development4 ,it may be easy to prove the identity of two different parts of the same stratum2 one1 where the rock has been in contact with a volcanic or plutonic mass1 and has been changed into marble or hornblende-schist1 and another not far distant1 where the same bed remains unaltered and fossiliferous2 but when we have to compare two portions of a mountain chain--the one metamorphic1 and the other unaltered--all the labour and skill of the most practised observers are required4 ,i shall mention one or two examples of alteration on a grand scale1 in order to explain to the student the kind of reasoning by which we are led to infer that dense masses of fossiliferous strata have been converted into crystalline rocks4 ,northern ,apennines--,carrara4--,the celebrated marble of ,carrara1 used in sculpture1 was once regarded as a type of primitive limestone4 ,it abounds in the mountains of ,massa ,carrara1 or the ,apuan ,alps1 as they have been called1 the highest peaks of which are nearly #fjjj feet high4 ,its great antiquity was inferred from its mineral texture1 from the absence of fossils1 and its passage downwards into talc-schist and garnetiferous mica-schist2 these rocks again graduating downwards into gneiss1 which is penetrated1 at ,forno1 by granite veins4 ,now the researches of ,,mm4 ,savi1 ,boue1 ,pareto1 ,guidoni1 ,de la ,beche1 ,hoffmann1 and ,pilla1 have demonstrated that this marble1 once supposed to be formed before the existence of organic beings1 is1 in fact1 an altered limestone of the ,oolitic period1 and the underlying crystalline schists are secondary sandstones and shales1 modified by plutonic action4 ,in order to establish these conclusions it was first pointed out1 that the calcareous rocks bordering the ,gulf of ,spezia1 and abounding in ,oolitic fossils1 assume a texture like that of ,carrara marble1 in proportion as they are more and more invaded by certain trappean and plutonic rocks1 such as diorite1 euphotide1 serpentine1 and granite1 occurring in the same country4 ,it was then observed that1 in places where the secondary formations are unaltered1 the uppermost consist of common ,apennine limestone with nodules of flint1 below which are shales1 and at the base of all1 argillaceous and siliceous sandstones4 ,in the limestone1 fossils are frequent1 but very rare in the underlying shale and sandstone4 ,then a gradation was traced laterally from these rocks into another and corresponding series1 which is completely metamorphic2 for at the top of this we find a white granular marble1 wholly devoid of fossils1 and almost without stratification1 in which there are no nodules of flint1 but in its place siliceous matter disseminated through the mass in the form of prisms of quartz4 ,below this1 and in place of the shales1 are talc-schists1 jasper1 and hornstone2 and at the bottom1 instead of the siliceous and argillaceous sandstones1 are quartzite and gneiss4#dhc-;,a ,had these secondary strata of the ,apennines undergone universally as great an amount of transmutation1 it would have been impossible to form a conjecture respecting their true age2 and then1 according to the common method of geological classification1 they would have ranked as primary rocks4 ,in that case the date of their origin would have been thrown back to an era antecedent to the deposition of the ,lower ,silurian or ,cambrian strata1 although in reality they were formed in the ,oolitic period1 and altered at some subsequent and perhaps much later epoch4 ,alps of ,switzerland4--,in the ,alps1 analogous conclusions have been drawn respecting the alteration of strata on a still more extended scale4 ,in the eastern part of that chain1 some of the primary fossiliferous strata1 as well as the older secondary formations1 together with the oolitic and cretaceous rocks1 are distinctly recognizable4 ,tertiary deposits also appear in a less elevated position on the flanks of the ,eastern ,alps2 but in the ,central or ,swiss ,alps1 the primary fossiliferous and older secondary formations disappear1 and the ,cretaceous1 ,oolitic1 ,liassic1 and at some points even the ,eocene strata1 graduate insensibly into metamorphic rocks1 consisting of granular limestone1 talc-schist1 talcose-gneiss1 micaceous schist1 and other varieties4 ,in regard to the age of this vast assemblage of crystalline strata1 we can merely affirm that some of the upper portions are altered newer secondary1 and some of them even ,eocene deposits2 but we cannot avoid suspecting that the disappearance both of the older secondary and primary fossiliferous rocks may be owing to their having been all converted in this region into crystalline schist4 ,it is difficult to convey to those who have never visited the ,alps a just idea of the various proofs which concur to produce this conviction4 ,in the first place1 there are certain regions where ,oolitic1 ,cretaceous1 and ,eocene strata have been turned into granular marble1 gneiss1 and other metamorphic schists1 near their contact with granite4 ,this fact shows undeniably that plutonic causes continued to be in operation in the ,alps down to a late period1 even after the deposition of some of the nummulitic or older ,eocene formations4 ,having established this point1 we are the more willing to believe that many inferior fossiliferous rocks1 probably exposed for longer periods to a similar action1 may have become metamorphic to a still greater extent4 ,we also discover in parts of the ,swiss ,alps dense masses of secondary and even tertiary strata1 which have assumed that semi-crystalline texture which ,werner called transition1 and which naturally led his followers1 who attached great importance to mineral characters taken alone1 to class them as transition formations1 or as groups older than the lowest secondary rocks4 7,see p4 #ib47 ,now1 it is probable that these strata have been affected1 although in a less intense degree1 by that same plutonic action which has entirely altered and rendered metamorphic so many of the subjacent formations2 for in the ,alps1 this action has by no means been confined to the immediate vicinity of granite4 ,granite1 indeed1 and other plutonic rocks1 rarely make their appearance at the surface1 notwithstanding the deep ravines which lay open to view the internal structure of these mountains4 ,that they exist below at no great depth we cannot doubt1 and we have already seen 7p4 #dde47 that at some points1 as in the ,valorsine1 near ,mont ,blanc1 granite and granitic veins are observable1 piercing through talcose gneiss1 which passes insensibly upwards into secondary strata4 ,it is certainly in the ,alps of ,switzerland and ,savoy1 more than in any other district in ,europe1 that the geologist is prepared to meet with the signs of an intense development of plutonic action2 for here we find the most stupendous monuments of mechanical violence1 by which strata thousands of feet thick have been bent1 folded1 and overturned4 7,see p4 #eh47 ,it is here that marine secondary formations of a comparatively modern date1 such as the ,oolitic and ,cretaceous1 have been upheaved to the height of #ab1jjj1 and some ,eocene strata to elevations of #aj1jjj feet above the level of the sea2 and even deposits of the ,miocene era have been raised #djjj or #ejjj feet1 so as to rival in height the loftiest mountains in ,great ,britain4 ,if the reader will consult the works of many eminent geologists who have explored the ,alps1 especially those of ,,mm4 ,de ,beaumont1 ,studer1 ,necker1 ,boue1 and ,murchison1 he will learn that they all share1 more or less fully1 in the opinions above expressed4 ,it has1 indeed1 been stated by ,,mm4 ,studer and ,hugi1 that there are complete alternations on a large scale of secondary strata1 containing fossils1 with gneiss and other rocks1 of a perfectly metamorphic structure4 ,i have visited some of the most remarkable localities referred to by these authors2 but although agreeing with them that there are passages from the fossiliferous to the metamorphic series far from the contact of granite or other plutonic rocks1 ,i was unable to convince myself that the distinct alternations of highly crystalline1 with unaltered strata above alluded to1 might not admit of a different explanation4 ,in one of the sections described by ,m4 ,studer in the highest of the ,bernese ,alps1 namely in the ,roththal1 a valley bordering the line of perpetual snow on the northern side of the ,jungfrau1 there occurs a mass of gneiss #ajjj feet thick1 and #ae1jjj feet long1 which ,i examined1 not only resting upon1 but also again covered by strata containing oolitic fossils4 ,these anomalous appearances may partly be explained by supposing great solid wedges of intrusive gneiss to have been forced in laterally between strata to which ,i found them to be in many sections unconformable4 ,the superposition1 also1 of the gneiss to the oolite may1 in some cases1 be due to a reversal of the original position of the beds in a region where the convulsions have been on so stupendous a scale4 ,on the ,sattel also1 at the base of the ,gestellihorn1 above ,enzen1 in the valley of ,urbach1 near ,meyringen1 some of the intercalations of gneiss between fossiliferous strata may1 ,i conceive1 be ascribed to mechanical derangement4 ,almost any hypothesis of repeated changes of position may be resorted to in a region of such extraordinary confusion4 ,the secondary strata may first have been vertical1 and then certain portions may have become metamorphic 7the plutonic influence ascending from below71 while intervening strata remained unchanged4 ,the whole series of beds may then again have been thrown into a nearly horizontal position1 giving rise to the superposition of crystalline upon fossiliferous formations4 ,it was remarked1 in ,chap4 ,,xxxiv41 that as the hypogene rocks1 both stratified and unstratified1 crystallize originally at a certain depth beneath the surface1 they must always1 before they are upraised and exposed at the surface1 be of considerable antiquity1 relatively to a large portion of the fossiliferous and volcanic rocks4 ,they may be forming at all periods2 but before any of them can become visible1 they must be raised above the level of the sea1 and some of the rocks which previously concealed them must have been removed by denudation4 ,order of succession in metamorphic rocks4--,there is no universal and invariable order of superposition in metamorphic rocks1 although a particular arrangement may prevail throughout countries of great extent1 for the same reason that it is traceable in those sedimentary formations from which crystalline strata are derived4 ,thus1 for example1 we have seen that in the ,apennines1 near ,carrara1 the descending series1 where it is metamorphic1 consists of1 #ast1 saccharine marble2 #b;dly1 talcose-schist2 and #c;dly1 of quartz-rock and gneiss2 where unaltered1 of1 #ast1 fossiliferous limestone2 #b;dly1 shale2 and #c;dly1 sandstone4 ,but if we investigate different mountain chains1 we find gneiss1 mica-schist1 hornblende-schist1 chlorite-schist1 hypogene1 limestone1 and other rocks1 succeeding each other1 and alternating with each other1 in every possible order4 ,it is1 indeed1 more common to meet with some variety of clay-slate forming the uppermost member of a metamorphic series than any other rock2 but this fact by no means implies1 as some have imagined1 that all clay-slates were formed at the close of an imaginary period1 when the deposition of the crystalline strata gave way to that of ordinary sedimentary deposits4 ,such clay-slates1 in fact1 are variable in composition1 and sometimes alternate with fossiliferous strata1 so that they may be said to belong almost equally to the sedimentary and metamorphic order of rocks4 ,it is probable that had they been subjected to more intense plutonic action1 they would have been transformed into hornblende-schist1 foliated chlorite-schist1 scaly talcose-schist1 mica-schist1 or other more perfectly crystalline rocks1 such as are usually associated with gneiss4 ,uniformity of mineral character in ,hypogene rocks4--,humboldt has emphatically remarked1 that when we pass to another hemisphere1 we see new forms of animals and plants1 and even new constellations in the heavens2 but in the rocks we still recognize our old acquaintances1--the same granite1 the same gneiss1 the same micaceous schist1 quartz-rock1 and the rest4 ,it is certainly true that there is a great and striking general resemblance in the principal kinds of hypogene rocks1 although of very different ages and countries2 but it has been shown that each of these are1 in fact1 geological families of rocks1 and not definite mineral compounds4 ,they are much more uniform in aspect than sedimentary strata1 because these last are often composed of fragments varying greatly in form1 size1 and colour1 and contain fossils of different shapes and mineral composition1 and acquire a variety of tints from the mixture of various kinds of sediment4 ,the materials of such strata1 if melted and made to crystallize1 would be subject to chemical laws1 simple and uniform in their action1 the same in every climate1 and wholly undisturbed by mechanical and organic causes4 ,nevertheless1 it would be a great error to assume that the hypogene rocks1 considered as aggregates of simple minerals1 are really more homogeneous in their composition than the several members of the sedimentary series4 ,in the first place1 different assemblages of hypogene rocks occur in different countries2 and1 secondly1 in any one district1 the rocks which pass under the same name are often extremely variable in their component ingredients1 or at least in the proportions in which each of these are present4 ,thus1 for example1 gneiss and mica-schist1 so abundant in the ,grampians1 are wanting in ,cumberland1 ,wales1 and ,cornwall2 in parts of the ,swiss and ,italian ,alps1 the gneiss and granite are talcose1 and not micaceous1 as in ,scotland2 hornblende prevails in the granite of ,scotland--schorl in that of ,cornwall--albite in the plutonic rocks of the ,andes--common felspar in those of ,europe4 ,in one part of ,scotland1 the mica-schist is full of garnets2 in another it is wholly devoid of them3 while in ,south ,america1 according to ,mr4 ,darwin1 it is the gneiss1 and not the mica-schist1 which is most commonly garnetiferous4 ,and not only do the proportional quantities of felspar1 quartz1 mica1 hornblende1 and other minerals1 vary in hypogene rocks bearing the same name2 but what is still more important1 the ingredients1 as we have seen1 of the same simple mineral are not always constant 7p4 #cfi41 and table1 p4 #cgg474 ,the ,metamorphic strata1 why less calcareous than the fossiliferous4--,it has been remarked1 that the quantity of calcareous matter in metamorphic strata1 or1 indeed1 in the hypogene formations generally1 is far less than in fossiliferous deposits4 ,thus the crystalline schists of the ,grampians in ,scotland1 consisting of gneiss1 mica-schist1 hornblende-schist1 and other rocks1 many thousands of yards in thickness1 contain an exceedingly small proportion of interstratified calcareous beds1 although these have been the objects of careful search for economical purposes4 ,yet limestone is not wanting in the ,grampians1 and it is associated sometimes with gneiss1 sometimes with mica-schist1 and in other places with other members of the metamorphic series4 ,but where limestone occurs abundantly1 as at ,carrara1 and in parts of the ,alps1 in connection with hypogene rocks1 it usually forms one of the superior members of the crystalline group4 ,the scarcity1 then1 of carbonate of lime in the plutonic and metamorphic rocks generally1 seems to be the result of some general cause4 ,so long as the hypogene rocks were believed to have originated antecedently to the creation of organic beings1 it was easy to impute the absence of lime to the non-existence of those mollusca and zoophytes by which shells and corals are secreted2 but when we ascribe the crystalline formations to plutonic action1 it is natural to inquire whether this action itself may not tend to expel carbonic acid and lime from the materials which it reduces to fusion or semi-fusion4 ,although we cannot descend into the subterranean regions where volcanic heat is developed1 we can observe in regions of spent volcanos1 such as ,auvergne and ,tuscany1 hundreds of springs1 both cold and thermal1 flowing out from granite and other rocks1 and having their waters plentifully charged with carbonate of lime4 ,the quantity of calcareous matter which these springs transfer1 in the course of ages1 from the lower parts of the earth's crust to the superior or newly formed parts of the same1 must be considerable4#dhg-;,a ,if the quantity of siliceous and aluminous ingredients brought up by such springs were great1 instead of being utterly insignificant1 it might be contended that the mineral matter thus expelled implies simply the decomposition of ordinary subterranean rocks2 but the prodigious excess of carbonate of lime over every other element must1 in the course of time1 cause the crust of the earth below to be almost entirely deprived of its calcareous constituents1 while we know that the same action imparts to newer deposits1 ever forming in seas and lakes1 an excess of carbonate of lime4 ,calcareous matter is poured into these lakes1 and the ocean1 by a thousand springs and rivers2 so that part of almost every new calcareous rock chemically precipitated1 and of many reefs of shelly and coralline stone1 must be derived from mineral matter subtracted by plutonic agency1 and driven up by gas and steam from fused and heated rocks in the bowels of the earth4 ,not only carbonate of lime1 but also free carbonic acid gas is given off plentifully from the soil and crevices of rocks in regions of active and spent volcanos1 as near ,naples1 and in ,auvergne4 ,by this process1 fossil shells or corals may often lose their carbonic acid1 and the residual lime may enter into the composition of augite1 hornblende1 garnet1 and other hypogene minerals4 ,that the removal of the calcareous matter of fossil shells is of frequent occurrence1 is proved by the fact of such organic remains being often replaced by silex or other minerals1 and sometimes by the space once occupied by the fossil being left empty1 or only marked by a faint impression4 ,we ought not indeed to marvel at the general absence of organic remains from the crystalline strata1 when we bear in mind how often fossils are obliterated1 wholly or in part1 even in tertiary formations--how often vast masses of sandstone and shale1 of different ages1 and thousands of feet thick1 are devoid of fossils--how certain strata may first have been deprived of a portion of their fossils when they became semi-crystalline1 or assumed the transition state of ,werner--and how the remaining organic remains have been effaced when they were rendered metamorphic4 ,some rocks of the last-mentioned class1 moreover1 must have been exposed again and again to renewed plutonic action4 ,,footnotes3 #dhc-;,a ,see notices of ,savi1 ,hoffmann1 and others1 referred to by ,boue1 ,bull4 de la ,soc4 ,geol4 de ,france1 tom4 v4 p4 #cag42 and tom4 iii4 p4 xliv42 also ,pilla1 cited by ,murchison1 ,quart4 ,geol4 ,journ41 vol4 v4 p4 #bff4 #dhg-;,a ,see ,principles1 ,index1 ,calcareous ,springs4 ,,chapter ,,xxxviii4 ,,mineral ,,veins4 ,werner's doctrine that mineral veins were fissures filled from above--,veins of segregation--,ordinary metalliferous veins or lodes--,their frequent coincidence with faults--,proofs that they originated in fissures in solid rock--,veins shifting other veins--,polishing of their walls--,shells and pebbles in lodes--,evidence of the successive enlargement and re-opening of veins--,fournet's observations in ,auvergne--,dimensions of veins--,why some alternately swell out and contract--,filling of lodes by sublimation from below--,chemical and electrical action--,relative age of the precious metals--,copper and lead veins in ,ireland older than ,cornish tin--,lead vein in lias1 ,glamorganshire--,gold in ,russia--,connection of hot springs and mineral veins--,concluding remarks4 ,the manner in which metallic substances are distributed through the earth's crust1 and more especially the phenomena of those nearly vertical and tabular masses of ore called mineral veins1 from which the larger part of the precious metals used by man are obtained1--these are subjects of the highest practical importance to the miner1 and of no less theoretical interest to the geologist4 ,the views entertained respecting metalliferous veins have been modified1 or1 rather1 have undergone an almost complete revolution1 since the middle of the last century1 when ,werner1 as director of the ,school of ,mines1 at ,freiberg in ,saxony1 first attempted to generalize the facts then known4 ,he taught that mineral veins had originally been open fissures which were gradually filled up with crystalline and metallic matter1 and that many of them1 after being once filled1 had been again enlarged or re-opened4 ,he also pointed out that veins thus formed are not all referable to one era1 but are of various geological dates4 ,such opinions1 although slightly hinted at by earlier writers1 had never before been generally received1 and their announcement by one of high authority and great experience constituted an era in the science4 ,nevertheless1 ,i have shown1 when tracing1 in another work1 the history and progress of geology1 that ,werner was far behind some of his predecessors in his theory of the volcanic rocks1 and less enlightened than his contemporary1 ,dr4 ,hutton1 in his speculations as to the origin of granite4#dhi-;,a ,according to him1 the plutonic formations1 as well as the crystalline schists1 were substances precipitated from a chaotic fluid in some primeval or nascent condition of the planet2 and the metals1 therefore1 being closely connected with them1 had partaken1 according to him1 of a like mysterious origin4 ,he also held that the trap rocks were aqueous deposits1 and that dikes of porphyry1 greenstone1 and basalt1 were fissures filled with their several contents from above4 ,hence he naturally inferred that mineral veins had derived their component materials from an incumbent ocean1 rather than from a subterranean source2 that these materials had been first dissolved in the waters above1 instead of having risen up by sublimation from lakes and seas of igneous matter below4 ,in proportion as the hypothesis of a primeval fluid1 or chaotic menstruum1 was abandoned1 in reference to the plutonic formations1 and when all geologists had come to be of one mind as to the true relation of the volcanic and trappean rocks1 reasonable hopes began to be entertained that the phenomena of mineral veins might be explained by known causes1 or by chemical1 thermal1 and electrical agency still at work in the interior of the earth4 ,the grounds of this conclusion will be better understood when the geological facts brought to light by mining operations have been described and explained4 ,on different kinds of mineral veins4--,every geologist is familiarly acquainted with those veins of quartz which abound in hypogene strata1 forming lenticular masses of limited extent4 ,they are sometimes observed1 also1 in sandstones and shales4 ,veins of carbonate of lime are equally common in fossiliferous rocks1 especially in limestones4 ,such veins appear to have once been chinks or small cavities1 caused1 like cracks in clay1 by the shrinking of the mass1 which has consolidated from a fluid state1 or has simply contracted its dimensions in passing from a higher to a lower temperature4 ,siliceous1 calcareous1 and occasionally metallic matters1 have sometimes found their way simultaneously into such empty spaces1 by infiltration from the surrounding rocks1 or by segregation1 as it is often termed4 ,mixed with hot water and steam1 metallic ores may have permeated a pasty matrix until they reached those receptacles formed by shrinkage1 and thus gave rise to that irregular assemblage of veins1 called by the ,germans a stockwerk1 in allusion to the different floors on which the mining operations are in such cases carried on4 ,the more ordinary or regular veins are usually worked in vertical shafts1 and have evidently been fissures produced by mechanical violence4 ,they traverse all kinds of rocks1 both hypogene and fossiliferous1 and extend downwards to indefinite or unknown depths4 ,we may assume that they correspond with such rents as we see caused from time to time by the shock of an earthquake4 ,metalliferous veins1 referable to such agency1 are occasionally a few inches wide1 but more commonly #c or #d feet4 ,they hold their course continuously in a certain prevailing direction for miles or leagues1 passing through rocks varying in mineral composition4 #c ,illustrations3 ,fig4 #eac4 ,fig4 #ead4 ,fig4 #eae4 ,vertical sections of the mine of ,huel ,peever1 ,redruth1 ,cornwall4 ,that metalliferous veins were fissures4--,as some intelligent miners1 after an attentive study of metalliferous veins1 have been unable to reconcile many of their characteristics with the hypothesis of fissures1 ,i shall begin by stating the evidence in its favour4 ,the most striking fact perhaps which can be adduced in its support is1 the coincidence of a considerable proportion of mineral veins with faults1 or those dislocations of rocks which are indisputably due to mechanical force1 as above explained 7p4 #fb474 ,there are even proofs in almost every mining district of a succession of faults1 by which the opposite walls of rents1 now the receptacles of metallic substances1 have suffered displacement4 ,thus1 for example1 suppose a a1 fig4 #eac41 to be a tin lode in ,cornwall1 the term lode being applied to veins containing metallic ores4 ,this lode1 running east and west1 is a yard wide1 and is shifted by a copper lode 7b b71 of similar width4 ,the first fissure 7a a7 has been filled with various materials1 partly of chemical origin1 such as quartz1 fluor-spar1 peroxide of tin1 sulphuret of copper1 arsenical pyrites1 bismuth1 and sulphuret of nickel1 and partly of mechanical origin1 comprising clay and angular fragments or detritus of the intersected rocks4 ,the plates of quartz and the ores are1 in some places1 parallel to the vertical sides or walls of the vein1 being divided from each other by alternating layers of clay1 or other earthy matter4 ,occasionally the metallic ores are disseminated in detached masses among the veinstones4 ,it is clear that1 after the gradual introduction of the tin and other substances1 the second rent 7b b7 was produced by another fracture accompanied by a displacement of the rocks along the plane of b b4 ,this new opening was then filled with minerals1 some of them resembling those in a a1 as fluor-spar 7or fluate of lime7 and quartz2 others different1 the copper being plentiful and the tin wanting or very scarce4 ,we must next suppose the shock of a third earthquake to occur1 breaking asunder all the rocks along the line c c1 fig4 #ead42 the fissure in this instance1 being only #f inches wide1 and simply filled with clay1 derived1 probably1 from the friction of the walls of the rent1 or partly1 perhaps1 washed in from above4 ,this new movement has heaved the rock in such a manner as to interrupt the continuity of the copper vein 7b b71 and1 at the same time1 to shift or heave laterally in the same direction a portion of the tin vein which had not previously been broken4 ,again1 in fig4 #eae4 we see evidence of a fourth fissure 7d d71 also filled with clay1 which has cut through the tin vein 7a a71 and has lifted it slightly upwards towards the south4 ,the various changes here represented are not ideal1 but are exhibited in a section obtained in working an old ,cornish mine1 long since abandoned1 in the parish of ,redruth1 called ,huel ,peever1 and described both by ,mr4 ,williams and ,mr4 ,carne4#dia-;,a ,the principal movement here referred to1 or that of c c1 fig4 #eae41 extends through a space of no less than #hd feet2 but in this1 as in the case of the other three1 it will be seen that the outline of the country above1 or the geographical features of ,cornwall1 are not affected by any of the dislocations1 a powerful denuding force having clearly been exerted subsequently to all the faults4 7,see above1 p4 #fi47 ,it is commonly said in ,cornwall1 that there are eight distinct systems of veins which can in like manner be referred to as many successive movements or fractures2 and the ,german miners of the ,hartz ,mountains speak also of eight systems of veins1 referable to as many periods4 ,besides the proofs of mechanical action already explained1 the opposite walls of veins are frequently polished and striated1 as if they had undergone great friction1 and this even in cases where there has been no shift4 ,we may attribute such rubbing to a vibratory motion known to accompany earthquakes1 and to produce trituration on the opposite walls of rents4 ,similar movements have sometimes occurred in mineral veins which had been wholly or partially filled up2 for included pieces of rock1 detached from the sides1 are found to be rounded1 polished1 and striated4 ,that a great many veins communicated originally with the surface of the country above1 or with the bed of the sea1 is proved by the occurrence in them of well rounded pebbles1 agreeing with those in superficial alluviums1 as in ,auvergne and ,saxony4 ,in ,bohemia1 such pebbles have been met with at the depth of #ahj fathoms4 ,in ,cornwall1 ,mr4 ,carne mentions true pebbles of quartz and slate in a tin lode of the ,relistran ,mine1 at the depth of #fjj feet below the surface4 ,they were cemented by oxide of tin and bisulphuret of copper1 and were traced over a space more than #ab feet long and as many wide4#dib-;,a ,marine fossil shells1 also1 have been found at great depths1 having probably been engulphed during submarine earthquakes4 ,thus1 a gryphaea is stated by ,m4 ,virlet to have been met with in a lead-mine near ,semur1 in ,france1 and a madrepore in a compact vein of cinnabar in ,hungary4#dib-;,b ,when different sets or systems of veins occur in the same country1 those which are supposed to be of contemporaneous origin1 and which are filled with the same kind of metals1 often maintain a general parallelism of direction4 ,thus1 for example1 both the tin and copper veins in ,cornwall run nearly east and west1 while the lead-veins run north and south2 but there is no general law of direction common to different mining districts4 ,the parallelism of the veins is another reason for regarding them as ordinary fissures1 for we observe that contemporaneous trap dikes1 admitted by all to be masses of melted matter which have filled rents1 are often parallel4 ,assuming1 then1 that veins are simply fissures in which chemical and mechanical deposits have accumulated1 we may next consider the proofs of their having been filled gradually and often during successive enlargements4 ,i have already spoken of parallel layers of clay1 quartz1 and ore4 ,werner himself observed1 in a vein near ,gersdorff1 in ,saxony1 no less than thirteen beds of different minerals1 arranged with the utmost regularity on each side of the central layer4 ,this layer was formed of two beds of calcareous spar1 which had evidently lined the opposite walls of a vertical cavity4 ,the thirteen beds followed each other in corresponding order1 consisting of fluor-spar1 heavy spar1 galena1 c4 ,in these cases1 the central mass has been last formed1 and the two plates which coat the outer walls of the rent on each side are the oldest of all4 ,if they consist of crystalline precipitates1 they may be explained by supposing the fissure to have remained unaltered in its dimensions1 while a series of changes occurred in the nature of the solutions which rose up from below2 but such a mode of deposition1 in the case of many successive and parallel layers1 appears to be exceptional4 ,if a veinstone consist of crystalline matter1 the points of the crystals are always turned inwards1 or towards the centre of the vein2 in other words1 they point in that direction where there was most space for the development of the crystals4 ,thus each new layer receives the impression of the crystals of the preceding layer1 and imprints its crystals on the one which follows1 until at length the whole of the vein is filled3 the two layers which meet dovetail the points of their crystals the one into the other4 ,but in ,cornwall1 some lodes occur where the vertical plates1 or combs1 as they are there called1 exhibit crystals so dovetailed as to prove that the same fissure has been often enlarged4 ,sir ,h4 ,de la ,beche gives the following curious and instructive example 7fig4 #eaf47 from a copper-mine in granite1 near ,redruth4#dic-;,a ,each of the plates or combs 7a1 b1 c1 d1 e1 f7 are double1 having the points of their crystals turned inwards along the axis of the comb4 ,the sides or walls 7#b1 #c1 #d1 #e1 and #f7 are parted by a thin covering of ochreous clay1 so that each comb is readily separable from another by a moderate blow of the hammer4 ,the breadth of each represents the whole width of the fissure at six successive periods1 and the outer walls of the vein1 where the first narrow rent was formed1 consisted of the granitic surfaces #a and #g4 ,illustration3 ,fig4 #eaf4 ,copper lode1 near ,redruth1 enlarged at six successive periods4 ,a somewhat analogous interpretation is applicable to numbers of other cases1 where clay1 sand1 or angular detritus1 alternate with ores and veinstones4 ,thus1 we may imagine the sides of a fissure to be encrusted with siliceous matter1 as ,von ,buch observed1 in ,lancerote1 the walls of a volcanic crater formed in #agca to be traversed by an open rent in which hot vapours had deposited hydrate of silica1 the incrustation nearly extending to the middle4#dic-;,b ,such a vein may then be filled with clay or sand1 and afterwards re-opened1 the new rent dividing the argillaceous deposit1 and allowing a quantity of rubbish to fall down4 ,various metals and spars may then be precipitated from aqueous solutions among the interstices of this heterogeneous mass4 ,that such changes have repeatedly occurred1 is demonstrated by occasional cross-veins1 implying the oblique fracture of previously formed chemical and mechanical deposits4 ,thus1 for example1 ,m4 ,fournet1 in his description of some mines in ,auvergne worked under his superintendence1 observes1 that the granite of that country was first penetrated by veins of granite1 and then dislocated1 so that open rents crossed both the granite and the granitic veins4 ,into such openings1 quartz1 accompanied by sulphurets of iron and arsenical pyrites1 was introduced4 ,another convulsion then burst open the rocks along the old line of fracture1 and the first set of deposits were cracked and often shattered1 so that the new rent was filled1 not only with angular fragments of the adjoining rocks1 but with pieces of the older veinstones4 ,polished and striated surfaces on the sides or in the contents of the vein also attest the reality of these movements4 ,a new period of repose then ensued1 during which various sulphurets were introduced1 together with hornstone quartz1 by which angular fragments of the older quartz before mentioned were cemented into a breccia4 ,this period was followed by other dilatations of the same veins1 and other sets of mineral deposits1 until1 at last1 pebbles of the basaltic lavas of ,auvergne1 derived from superficial alluviums1 probably of ,miocene or older ,pliocene date1 were swept into the veins4 ,i have not space to enumerate all the changes minutely detailed by ,m4 ,fournet1 but they are valuable1 both to the miner and geologist1 as showing how the supposed signs of violent catastrophes may be the monuments1 not of one paroxysmal shock1 but of reiterated movements4 ,such repeated enlargement and re-opening of veins might have been anticipated1 if we adopt the theory of fissures1 and reflect how few of them have ever been sealed up entirely1 and that a country with fissures only partially filled must naturally offer much feebler resistance along the old lines of fracture than any where else4 ,it is quite otherwise in the case of dikes1 where each opening has been the receptacle of one continuous and homogeneous mass of melted matter1 the consolidation of which has taken place under considerable pressure4 ,trappean dikes can rarely fail to strengthen the rocks at the points where before they were weakest2 and if the upheaving force is again exerted in the same direction1 the crust of the earth will give way anywhere rather than at the precise points where the first rents were produced4 ,a large proportion of metalliferous veins have their opposite walls nearly parallel1 and sometimes over a wide extent of country4 ,there is a fine example of this in the celebrated vein of ,andreasberg in the ,hartz1 which has been worked for a depth of #ejj yards perpendicularly1 and #bjj horizontally1 retaining almost every where a width of #c feet4 ,but many lodes in ,cornwall and elsewhere are extremely variable in size1 being #a or #b inches in one part1 and then #h or #aj feet in another1 at the distance of a few fathoms1 and then again narrowing as before4 ,such alternate swelling and contraction is so often characteristic as to require explanation4 ,the walls of fissures in general1 observes ,sir ,h4 ,de la ,beche1 are rarely perfect planes throughout their entire course1 nor could we well expect them to be so1 since they commonly pass through rocks of unequal hardness and different mineral composition4 ,if1 therefore1 the opposite sides of such irregular fissures slide upon each other1 that is to say1 if there be a fault1 as in the case of so many mineral veins1 the parallelism of the opposite walls is at once entirely destroyed1 as will be readily seen by studying the annexed diagrams4 ,illustration3 ,fig4 #eag4 ,schematic sketch4 ,illustration3 ,fig4 #eah4 ,schematic sketch4 ,illustration3 ,fig4 #eai4 ,schematic sketch4 ,let a b1 fig4 #eag41 be a line of fracture traversing a rock1 and let a b1 fig4 #eah41 represent the same line4 ,now1 if we cut a piece of paper representing this line1 and then move the lower portion of this cut paper sideways from a to a'1 taking care that the two pieces of paper still touch each other at the points #a1 #b1 #c1 #d1 #e1 we obtain an irregular aperture at c1 and isolated cavities at d d d1 and when we compare such figures with nature we find that1 with certain modifications1 they represent the interior of faults and mineral veins4 ,if1 instead of sliding the cut paper to the right hand1 we move the lower part towards the left1 about the same distance that it was previously slid to the right1 we obtain considerable variation in the cavities so produced1 two long irregular open spaces1 f f1 fig4 #eai41 being then formed4 ,this will serve to show to what slight circumstances considerable variations in the character of the openings between unevenly fractured surfaces may be due1 such surfaces being moved upon each other1 so as to have numerous points of contact4 ,illustration3 ,fig4 #ebj4 ,schematic sketch4 ,most lodes are perpendicular to the horizon1 or nearly so2 but some of them have a considerable inclination or hade1 as it is termed1 the angles of dip varying from #ae deg4 to #de deg44 ,the course of a vein is frequently very straight2 but if tortuous1 it is found to be choked up with clay1 stones1 and pebbles1 at points where it departs most widely from verticality4 ,hence at places1 such as a1 fig4 #ebj41 the miner complains that the ores are nipped1 or greatly reduced in quantity1 the space for their free deposition having been interfered with in consequence of the pre-occupancy of the lode by earthy materials4 ,when lodes are many fathoms wide1 they are usually filled for the most part with earthy matter1 and fragments of rock1 through which the ores are much disseminated4 ,the metallic substances frequently coat or encircle detached pieces of rock1 which our miners call horses or riders4 ,that we should find some mineral veins which split into branches is also natural1 for we observe the same in regard to open fissures4 ,chemical deposits in veins4--,if we now turn from the mechanical to the chemical agencies which have been instrumental in the production of mineral veins1 it may be remarked that those parts of fissures which were not choked up with the ruins of fractured rocks must always have been filled with water2 and almost every vein has probably been the channel by which hot springs1 so common in countries of volcanos and earthquakes1 have made their way to the surface4 ,for we know that the rents in which ores abound extend downwards to vast depths1 where the temperature of the interior of the earth is more elevated4 ,we also know that mineral veins are most metalliferous near the contact of plutonic and stratified formations1 especially where the former send veins into the latter1 a circumstance which indicates an original proximity of veins at their inferior extremity to igneous and heated rocks4 ,it is moreover acknowledged that even those mineral and thermal springs which1 in the present state of the globe1 are far from volcanos1 are nevertheless observed to burst out along great lines of upheaval and dislocation of rocks4#dif-;,a ,it is also ascertained that all the substances with which hot springs are impregnated agree with those discharged in a gaseous form from volcanos4 ,many of these bodies occur as veinstones2 such as silex1 carbonate of lime1 sulphur1 fluor-spar1 sulphate of barytes1 magnesia1 oxide of iron1 and others4 ,i may add that1 if veins have been filled with gaseous emanations from masses of melted matter1 slowly cooling in the subterranean regions1 the contraction of such masses as they pass from a plastic to a solid state would1 according to the experiments of ,deville on granite 7a rock which may be taken as a standard71 produce a reduction in volume amounting to #aj per cent4 ,the slow crystallization1 therefore1 of such plutonic rocks supplies us with a force not only capable of rending open the incumbent rocks by causing a failure of support1 but also of giving rise to faults whenever one portion of the earth's crust subsides slowly while another contiguous to it happens to rest on a different foundation1 so as to remain unmoved4 ,although we are led to infer1 from the foregoing reasoning1 that there has often been an intimate connection between metalliferous veins and hot springs holding mineral matter in solution1 yet we must not on that account expect that the contents of hot springs and mineral veins would be identical4 ,on the contrary1 ,m4 ,e4 de ,beaumont has judiciously observed that we ought to find in veins those substances which1 being least soluble1 are not discharged by hot springs1--or that class of simple and compound bodies which the thermal waters ascending from below would first precipitate on the walls of a fissure1 as soon as their temperature began slightly to diminish4 ,the higher they mount towards the surface1 the more will they cool1 till they acquire the average temperature of springs1 being in that case chiefly charged with the most soluble substances1 such as the alkalis1 soda and potash4 ,these are not met with in veins1 although they enter so largely into the composition of granitic rocks4#dif-;,b ,to a certain extent1 therefore1 the arrangement and distribution of metallic matter in veins may be referred to ordinary chemical action1 or to those variations in temperature1 which waters holding the ores in solution must undergo1 as they rise upwards from great depths in the earth4 ,but there are other phenomena which do not admit of the same simple explanation4 ,thus1 for example1 in ,derbyshire1 veins containing ores of lead1 zinc1 and copper1 but chiefly lead1 traverse alternate beds of limestone and greenstone4 ,the ore is plentiful where the walls of the rent consist of limestone1 but is reduced to a mere string when they are formed of greenstone1 or toadstone1 as it is called provincially4 ,not that the original fissure is narrower where the greenstone occurs1 but because more of the space is there filled with veinstones1 and the waters at such points have not parted so freely with their metallic contents4 ,lodes in ,cornwall1 says ,mr4 ,robert ,w4 ,fox1 are very much influenced in their metallic riches by the nature of the rock which they traverse1 and they often change in this respect very suddenly1 in passing from one rock to another4 ,thus many lodes which yield abundance of ore in granite1 are unproductive in clay-slate1 or killas1 and vice versa4 ,the same observation applies to killas and the granitic porphyry called elvan4 ,sometimes1 in the same continuous vein1 the granite will contain copper1 and the killas tin1 or vice versa4#dig-;,a ,mr4 ,fox1 after ascertaining the existence at present of electric currents in some of the metalliferous veins in ,cornwall1 has speculated on the probability of the same cause having acted originally on the sulphurets and muriates of copper1 tin1 iron1 and zinc1 dissolved in the hot water of fissures1 so as to determine the peculiar mode of their distribution4 ,after instituting experiments on this subject1 he even endeavoured to account for the prevalence of an east and west direction in the principal ,cornish lodes by their position at right angles to the earth's magnetism2 but ,mr4 ,henwood and other experienced miners have pointed out objections to the theory2 and it must be owned that the direction of veins in different mining districts varies so entirely that it seems to depend on lines of fracture1 rather than on the laws of voltaic electricity4 ,nevertheless1 as different kinds of rock would be often in different electrical conditions1 we may readily believe that electricity must often govern the arrangement of metallic precipitates in a rent4 ,i have observed1 says ,mr4 ,r4 ,fox1 that when the chloride of tin in solution is placed in the voltaic circuit1 part of the tin is deposited in a metallic state at the negative pole1 and part at the positive one1 in the state of a peroxide1 such as it occurs in our ,cornish mines4 ,this experiment may serve to explain why tin is found contiguous to1 and intermixed with1 copper ore1 and likewise separated from it1 in other parts of the same lode4#dig-;,b ,relative age of the different metals4--,after duly reflecting on the facts above described1 we cannot doubt that mineral veins1 like eruptions of granite or trap1 are referable to many distinct periods of the earth's history1 although it may be more difficult to determine the precise age of veins2 because they have often remained open for ages1 and because1 as we have seen1 the same fissure1 after having been once filled1 has frequently been re-opened or enlarged4 ,but besides this diversity of age1 it has been supposed by some geologists that certain metals have been produced exclusively in earlier1 others in more modern times1--that tin1 for example1 is of higher antiquity than copper1 copper than lead or silver1 and all of them more ancient than gold4 ,i shall first point out that the facts once relied upon in support of some of these views are contradicted by later experience1 and then consider how far any chronological order of arrangement can be recognized in the position of the precious and other metals in the earth's crust4 ,in the first place1 it is not true that veins in which tin abounds are the oldest lodes worked in ,great ,britain4 ,the government survey of ,ireland has demonstrated1 that in ,wexford veins of copper and lead 7the latter as usual being argentiferous7 are much older than the tin of ,cornwall4 ,in each of the two countries a very similar series of geological changes has occurred at two distinct epochs1--in ,wexford1 before the ,devonian strata were deposited2 in ,cornwall1 after the carboniferous epoch4 ,to begin with the ,irish mining district3 ,we have granite in ,wexford1 traversed by granite veins1 which veins also intrude themselves into the ,silurian strata1 the same ,silurian rocks as well as the veins having been denuded before the ,devonian beds were superimposed4 ,next we find1 in the same county1 that elvans1 or straight dikes of porphyritic granite1 have cut through the granite and the veins before mentioned1 but have not penetrated the ,devonian rocks4 ,subsequently to these elvans1 veins of copper and lead were produced1 being of a date certainly posterior to the ,silurian1 and anterior to the ,devonian2 for they do not enter the latter1 and1 what is still more decisive1 streaks or layers of derivative copper have been found near ,wexford in the ,devonian1 not far from points where mines of copper are worked in the ,silurian strata4#dih-;,a ,although the precise age of such copper lodes cannot be defined1 we may safely affirm that they were either filled at the close of the ,silurian or commencement of the ,devonian period4 ,besides copper1 lead1 and silver1 there is some gold in these ancient or primary metalliferous veins4 ,a few fragments also of tin found in ,wicklow in the drift are supposed to have been derived from veins of the same age4#dih-;,b ,next1 if we turn to ,cornwall1 we find there also the monuments of a very analogous sequence of events4 ,first the granite was formed2 then1 about the same period1 veins of fine-grained granite1 often tortuous 7see fig4 #dif41 p4 #dde471 penetrating both the outer crust of granite and the adjoining fossiliferous or primary rocks1 including the coal-measures2 thirdly1 elvans1 holding their course straight through granite1 granitic veins1 and fossiliferous slates2 fourthly1 veins of tin also containing copper1 the first of those eight systems of fissures of different ages already alluded to1 p4 #dia4 ,here1 then1 the tin lodes are newer than the elvans4 ,it has indeed been stated by some ,cornish miners that the elvans are in some few instances posterior to the oldest tin-bearing lodes1 but the observations of ,sir ,h4 ,de la ,beche during the survey led him to an opposite conclusion1 and he has shown how the cases referred to in corroboration can be otherwise interpreted4#dii-;,a ,we may1 therefore1 assert that the most ancient ,cornish lodes are younger than the coal-measures of that part of ,england1 and it follows that they are of a much later date than the ,irish copper and lead of ,wexford and some adjoining counties4 ,how much later it is not so easy to declare1 although probably they are not newer than the beginning of the ,permian period1 as no tin lodes have been discovered in any red sandstone of the ,poikilitic group1 which overlies the coal in the south-west of ,england4 ,there are lead veins in the ,mendip hills which extend through the mountain limestone into the ,permian or ,dolomitic conglomerate1 and others in ,glamorganshire which enter the lias4 ,those worked near ,frome1 in ,somersetshire1 have been traced into the ,inferior ,oolite4 ,in ,bohemia1 the rich veins of silver of ,joachimsthal cut through basalt containing olivine1 which overlies tertiary lignite1 in which are leaves of dicotyledonous trees4 ,this silver1 therefore1 is decidedly a tertiary formation4 ,in regard to the age of the gold of the ,ural ,mountains1 in ,russia1 which1 like that of ,california1 is obtained chiefly from auriferous alluvium1 we can merely affirm that it occurs in veins of quartz in the schistose and granitic rocks of that chain4 ,sir ,r4 ,murchison observes1 that no gold has yet been found in the ,permian conglomerates which lie at the base of the ,ural ,mountains1 although large quantities of iron and copper detritus are mixed with the rolled pebbles of these same ,permian strata4 ,hence it seems that the ,uralian quartz veins1 containing gold and platinum1 were not exposed to aqueous denudation during the ,permian era4 ,but we cannot feel sure1 from any data yet before us1 that such auriferous veins of quartz may not be as old as the tin lodes of ,cornwall1 in which1 as well as the more ancient copper lodes of ,ireland1 some gold has been detected4 ,we are also unable at present to assign to the gold veins of ,brazil1 ,peru1 or ,california1 their respective geological dates4 ,but1 although enough is known to show that ,ovid's line about the ,age of ,gold1 ,aurea prima sata est aetas1 would1 by no means1 be an apt motto for a treatise on mining1 it would be equally rash in the present state of our inquiries to affirm1 as some have done1 that gold was the last-formed of metals4 ,it has been remarked by ,m4 de ,beaumont1 that lead and some other metals are found in dikes of basalt and greenstone1 as well as in mineral veins connected with trap rocks1 whereas tin is met with in granite and in veins associated with the granitic series4 ,if this rule hold true generally1 the geological position of tin in localities accessible to the miners will belong1 for the most part1 to rocks older than those bearing lead4 ,the tin veins will be of higher relative antiquity for the same reason that the underlying igneous formations or granites which are visible to man are older1 on the whole1 than the overlying or trappean formations4 ,if different sets of fissures1 originating simultaneously at different levels in the earth's crust1 and communicating1 some of them1 with volcanic1 others with heated plutonic masses1 be filled with different metals1 it will follow that those formed farthest from the surface will usually require the longest time before they can be exposed superficially4 ,in order to bring them into view1 or within reach of the miner1 a greater amount of upheaval and denudation must take place in proportion as they have lain deeper when first formed4 ,a considerable series of geological revolutions must intervene before any part of the fissure1 which has been for ages in the proximity of the plutonic rocks1 so as to receive the gases discharged from it when it was cooling1 can emerge into the atmosphere4 ,but ,i need not enlarge on this subject1 as the reader will remember what was said in the #cjth1 #cdth1 and #cgth chapters1 on the chronology of the volcanic and hypogene formations4 99 99 99 99 99 ,concluding ,remarks4--,the theory of the origin of the hypogene rocks1 at a variety of successive periods1 as expounded in two of the chapters just cited1 and still more the doctrine that such rocks may be now in the daily course of formation1 has made and still makes its way1 but slowly1 into favour4 ,the disinclination to embrace it has arisen partly from an inherent obscurity in the very nature of the evidence of plutonic action when developed on a great scale1 at particular periods4 ,it has also sprung1 in some degree1 from extrinsic considerations2 many geologists having been unwilling to believe the doctrine of the transmutation of fossiliferous into crystalline rocks1 because they were desirous of finding proofs of a beginning1 and of tracing back the history of our terraqueous system to times anterior to the creation of organic beings4 ,but if these expectations have been disappointed1 if we have found it impossible to assign a limit to that time throughout which it has pleased an ,omnipotent and ,eternal ,being to manifest his creative power1 we have at least succeeded beyond all hope in carrying back our researches to times antecedent to the existence of man4 ,we can prove that man had a beginning1 and that1 all the species now contemporary with man1 and many others which preceded1 had also a beginning1 and that1 consequently1 the present state of the organic world has not gone on from all eternity1 as some philosophers have maintained4 ,it can be shown that the earth's surface has been remodelled again and again2 mountain chains have been raised or sunk2 valleys formed1 filled up1 and then re-excavated2 sea and land have changed places2 yet throughout all these revolutions1 and the consequent alterations of local and general climate1 animal and vegetable life has been sustained4 ,this has been accomplished without violation of the laws now governing the organic creation1 by which limits are assigned to the variability of species4 ,the succession of living beings appears to have been continued not by the transmutation of species1 but by the introduction into the earth from time to time of new plants and animals1 and each assemblage of new species must have been admirably fitted for the new states of the globe as they arose1 or they would not have increased and multiplied and endured for indefinite periods4#eja-;,a ,astronomy had been unable to establish the plurality of habitable worlds throughout space1 however favourite a subject of conjecture and speculation2 but geology1 although it cannot prove that other planets are peopled with appropriate races of living beings1 has demonstrated the truth of conclusions scarcely less wonderful1--the existence on our own planet of so many habitable surfaces1 or worlds as they have been called1 each distinct in time1 and peopled with its peculiar races of aquatic and terrestrial beings4 ,the proofs now accumulated of the close analogy between extinct and recent species are such as to leave no doubt on the mind that the same harmony of parts and beauty of contrivance which we admire in the living creation1 has equally characterized the organic world at remote periods4 ,thus as we increase our knowledge of the inexhaustible variety displayed in living nature1 and admire the infinite wisdom and power which it displays1 our admiration is multiplied by the reflection1 that it is only the last of a great series of pre-existing creations1 of which we cannot estimate the number or limit in times past4#eja-;,b ,,footnotes3 #dhi-;,a ,principles1 c4 chap4 iv4 #hth ed4 p4 #di4 #dia-;,a ,geol4 ,trans4 vol4 iv4 p4 #aci42 ,trans4 ,roy4 ,geol4 ,society ,cornwall1 vol4 ii4 p4 #ij4 #dib-;,a ,carne1 ,trans4 of ,geol4 ,soc4 ,cornwall1 vol4 iii4 p4 #bch4 #dib-;,b ,fournet1 ,etudes sur les ,depots ,metalliferes4 #dic-;,a ,geol4 ,rep4 on ,cornwall1 p4 #cdj4 #dic-;,b ,principles1 ch4 xxvii4 #hth ed4 p4 #dbb4 #dif-;,a ,see ,dr4 ,daubeny's ,volcanos4 #dif-;,b ,bulletin1 iv4 p4 #abgh4 #dig-;,a ,r4 ,w4 ,fox on ,mineral ,veins1 p4 #aj4 #dig-;,b ,ibid4 p4 #ch4 #dih-;,a ,i am indebted to ,sir ,h4 ,de la ,beche for this information4 ,see also maps and sections of ,irish ,survey4 #dih-;,b ,sir ,h4 ,de la ,beche1 ,,ms4 notes on ,irish ,survey4 #dii-;,a ,report on ,geology of ,cornwall1 p4 #caj4 #eja-;,a ,see ,principles of ,geol41 ,book #c4 #eja-;,b ,see the author's ,anniv4 ,address to the ,geol4 ,soc4 #ahcg4 ,proceedings of ,g4 ,s4 ,no4 #di4 p4 #ebj4 ,,index4 ,a4 ,a,egean ,sea1 mud of1 #ce4 animal life in depths of1 #acg4 ,agassiz1 ,m41 cited1 #aib4 #bgf4 #cjj4 #cce4 #cdd4 #cde4 on parallel roads1 #hg4 on fossil fishes of molasse and faluns1 #aga4 on fossil fish of ,lias1 #bge4 on fossil fish in ,permian marl-slate1 #cjd4 on fish from ,sheppey1 #bjb4 on foot-prints1 #bii4 on fishes of brown coal1 #dag4 on glaciers1 #adj4 #adc4 ,age of formation determined by fragments of older rock1 #aja4 of metamorphic rocks1 #dhb4 test of1 in plutonic rocks by relative position1 #ddi4 of ,spanish volcanos1 #dad4 of volcanic rocks1 how tested1 #cig-djj4 ,aix-la-,chapelle1 hot spring at1 #dgg4 ,alabaster defined1 #ac4 ,alabama1 cretaceous shingle of1 #bbe4 ,alberti on the ,keuper1 #bhg4 ,alexander1 ,capt41 marine shells in crag1 found by1 #adi4 ,alluvium1 term explained1 #gi4 in ,auvergne1 #hj4 of the ,wealden1 #beb4 ,alps1 nummulitic formation of1 #bje4 curved strata of1 #eh4 ,swiss and ,savoy1 cleavage of1 #dgj4 of ,switzerland1 #dhc4 ,alpine blocks on the ,jura1 #adb4 erratics1 #adj4 ,altered rocks1 #cha4 #def4 by subterranean gases1 #dgf4 ,alternations of rocks1 #ad4 of marine and freshwater formations1 #cb4 ,alumine in rocks1 #aa4 ,amblyrhynchus cristatus1 #bgi4 ,america1 ,north1 lithodomi in beaches of1 #gh4 ,south1 cretaceous strata1 #bbe4 ,south1 gradual rise of parts of1 #df4 ,south1 fossils of1 #aeg4 ,amygdaloid1 #cgb4 ,amphitherium1 #bfh4 ,andelys1 chalk cliffs at1 #bci4 ,andernach1 strata near1 #dag4 ,andes1 plutonic rocks of1 #dec4 rocks drifted from to ,chiloe1 #add4 ,anthracite in ,rhode ,island1 #dgh4 ,anticlinal line1 #dh4 #eg4 ,antrim1 rocks altered by dikes in1 #chb4 ,antwerp1 strata like ,suffolk crag near1 #aff4 ,apateon pedestris1 a carboniferous reptile1 #ccf4 ,apennines1 limestone in1 #dhb4 ,appalachian coal-field1 #cbi4 ,appalachians1 altered rocks in1 #dgh4 ,apteryx in ,new ,zealand1 #aeh4 ,aqueous rocks defined1 #b4 rocks1 mineral character of1 #ig4 deposits1 superposition of1 #if4 ,arbroath1 section from1 to the ,grampians1 #dh4 ,archegosaurus1 figure of1 #ccg4 ,archiac1 ,m41 cited1 #adc4 on fossils in chalk1 #bba4 on shells in ,french ,lower ,eocene1 #aif4 ,ardeche1 lava in1 #che4 ,arenaceous rocks described1 #aa4 ,argillaceous rocks1 #aa4 schist1 #dfe4 ,argile plastique1 or ,lower ,eocene1 #aif4 ,argyleshire1 trap-vein in cliff1 #cgi4 ,arran1 age of granite in1 #dei4 section of1 #dfa4 dike of greenstone in1 #cgi4 ,arthur's ,seat1 altered strata of1 #chc4 ,ashby-de-la-,zouch1 fault in coal-field of1 #fi4 ,ascension1 lamination of volcanic rocks in1 #dhj4 ,asterophyllites1 #cad4 ,asti1 formations at1 #afg4 ,atherfield1 cretaceous strata of1 #bai4 ,augite1 #cfi4 ,aurillac1 freshwater strata of1 #ahh4 ,austen1 ,mr41 ,r4 ,a4 ,c41 on phosphate of lime1 #bai4 ,australian cave-breccias1 #aee4 ,auvergne freshwater formations1 #ahf4 succession of changes in1 #ahj4 lacustrine strata1 #aha4 mineral veins of1 #dic4 indusial limestone1 #ahd4 extinct volcanos of1 #dbb4 alluvium in1 #hj4 ,aymestry limestone1 #ceb4 ,b4 ,bagshot sands1 #aii4 ,bacillaria1 fossil in tripoli1 #be4 ,baiae1 ,bay of1 strata in1 #djc4 ,bakewell1 ,mr41 on cleavages of ,alps1 #dgj4 ,balgray1 near ,glasgow1 stumps of trees in coal1 #cag4 ,bahia ,blanca1 fossil remains at1 #adh4 ,baltic1 brackish water strata on coast of1 #aad4 ,barcombe1 chalk flints near1 #bec4 ,barton ,cliff1 #aih4 ,barrande1 ,m41 on trilobites1 #ceh4 ,basterot1 ,m4 de1 on tertiaries of south of ,france1 #aje4 ,basalt1 #cga4 columnar in the ,eifel1 #chg4 columnar1 near ,vicenza1 #chf4 columnar1 structure of1 #chd4 ,basset1 term explained1 #ef4 ,batrachian1 eggs of1 in ,old ,red1 ,scotland1 ,postscript1 x4 ,bayfield1 ,capt41 on fossil shells in ,canada1 #acd4 on inland cliffs in ,gulf of ,st4 ,lawrence1 #gh4 ,bean1 ,mr41 shells similar to those in ,norwich crag found in ,yorkshire by1 #adi4 ,bean1 ,mr41 on fossil shells from oolite1 #bgb4 ,beachy ,head1 chalk cliffs near1 #bdf4 ,beaumont1 ,m4 ,e4 de1 on rocks of ,hautes ,alpes1 #dee4 on lamination of volcanic rocks1 #dhj4 ,beaumont1 ,m4 ,e4 de1 on ,swiss ,alps1 #dhd4 on quartz1 #dci4 on oolite formation in ,france1 #bba4 ,beck1 ,dr41 on kelp1 #bag4 on graptolites1 #ceg4 cited1 #afb4 #ahf4 ,belemnite in ,oxford clay1 #bfb4 ,berger1 ,dr41 on rocks altered by dikes1 #chb4 ,bergmann on trap1 #cff4 ,berlin1 tertiary strata near1 #agg4 ,bermuda ,islands1 lagoons in1 #baf4 rocks of1 #gh4 ,bernese ,alps1 gneiss in1 #dhd4 ,berthier1 on augite and hornblende1 #cfi4 ,beudant1 ,m41 on ,hungary1 #dba4 ,beyrich1 ,prof41 on tertiary strata near ,berlin1 #agg4 ,biaritz1 calcareous cliffs of1 #gb4 ,bilin1 tripoli1 composed of infusoria1 #be4 ,binney1 ,mr41 on stigmaria and sigillaria1 #cae4 ,birds1 footprints of1 #bih4 fossil1 scarcity of1 ,postscript1 xix4 ,bischoff1 ,prof41 experiments on heat1 #dgf4 on steam at a high temperature1 #dgg4 ,blainville1 on number of genera of mollusca1 #bh4 ,boase1 ,dr41 cited1 #dgi4 ,boblaye1 ,m41 on inland cliffs1 #gc4 cited1 #dca4 ,bog-iron ore1 #bf4 ,borrowdale1 black-lead of1 #ch4 ,bordeaux1 tertiary deposits of1 #aga4 ,bosquet1 ,m41 on ,maestricht beds1 #baj4 ,bothnia1 ,gulf of1 land upheaved1 #de4 ,boue1 ,m41 on arrangement of rocks1 #ie4 on fossil shells in ,hungary1 #dba4 on ,carrara marble1 #dhb4 on ,swiss ,alps1 #dhd4 ,bonelli1 on strata in ,italy1 #ajf4 ,boulder formation in ,canada1 #acc4 period1 fauna of1 #abf4 formation1 mineral ingredients of1 #abf4 formation in ,england1 #acj4 ,boulders1 #abc4 striated1 #acf4 ,boutigny1 ,m41 cited1 #dda4 ,bowen1 ,lieut4 ,a41 ,r4,n41 drawings of rocks in ,gulf of ,st4 ,lawrence1 #gh4 ,bowerbank1 ,mr41 on fossil flora of ,sheppey1 #bjj4 ,bowman1 ,mr41 on coal-seams1 #ccj4 ,bracklesham ,bay1 characteristic shells of1 #aii4 ,brash1 term1 explained1 #ha4 ,bravard1 ,m41 on ,auvergne mammalia1 #ahh4 #dbe4 ,breccia on ancient coast lines1 #gc4 ,brickenden1 ,captain1 on ,elgin fossils1 ,postscript1 ix4 ,brighton1 elephant bed of1 #bef4 ,bristol1 dolomitic conglomerate near1 #cje4 section of strata near1 #ajb4 ,brocchi1 on ,subapennines1 #aje4 #afg4 ,brockedon1 ,mr41 on black-lead1 #ch4 ,broderip1 ,mr41 cited1 #bgj4 ,brodie1 ,rev4 ,p4,b41 on fossil insects1 #bha4 cited1 #bjg4 ,bromley1 oyster-bed near1 #bjd4 ,brongniart1 ,m4 ,adolphe1 on ,eocene flora1 #bjj4 on flora of cretaceous period1 #bbc4 on fossil plants in lias1 #bhb4 on plants of ,bunter sandstein1 #bhh4 on fossil fir-cones1 #cac4 on ,permian flora1 #cjg4 on sigillaria1 #cad4 on asterophyllites1 #cad4 on stigmaria1 #cae4 age of acrogens1 #caf4 on endogens1 #caf4 ,brongniart1 ,m4 ,alex41 on ,paris tertiaries1 #ajd4 on ,eocene formation1 #age4 on shells of nummulitic formation1 #bje4 on coal mine near ,lyons1 #cai4 ,brora1 coal formation1 #bgb4 ,brora1 granite near1 #deh4 ,brown1 ,mr4 ,richard1 on stigmariae1 #cae4 on coal formation1 #dae4 on ,cape ,breton coal-field1 #cbd4 #ccd4 on carboniferous rain-prints1 ,postscript1 xii4 ,buckland1 ,dr41 on cave at ,kirkdale1 #aed4 on coal plants1 #cag4 on coprolites in chalk1 #baf4 on fish of ,lias1 #bgf4 on footprints1 #bia4 on mountains of ,caernarvonshire1 #acj4 on oyster bed near ,bromley1 #bjd4 on parallel roads1 #hg4 on term ,poikilitic1 #bhf4 on saurians of ,lias1 #bgh4 on sudden destruction of saurians1 #bhj4 cited1 #aee4 #bca4 #bcc4 #bfg4 #bfh4 ,buddle1 ,mr41 on creeps in coal mines1 #ej4 on ancient river-channels of coal period1 #ccd4 ,buist1 ,dr4 ,g41 on saltness of ,red ,sea1 #bif4 ,bunbury1 ,mr4 ,c4 ,j4 ,f41 on plants of coal-field1 #bhe4 ,bunter sandstein1 #bhh4 ,burmeister on trilobites1 #ceh4 ,burnes1 ,sir ,a41 cited1 #bie4 ,c4 ,caernarvonshire1 ancient glaciers of1 #acj4 ,calamites1 figures of1 #cac4 near ,pictou1 #cai4 ,calcaire grossier1 #aic4 siliceux1 #aie4 ,calcareous rocks1 #ab4 rocks of ,gulf of ,spezia1 #dhb4 cliffs of ,biaritz1 #gb4 ,caldcleugh1 ,mr41 cited1 #cii4 ,caldera of ,palma1 #cib4 ,cambrian group1 #cfa4 volcanic rocks1 #dce4 ,campagna di ,roma1 tuffs of1 #djh4 ,canada1 shells in drift of1 #acd4 ,cantal1 freshwater formation of1 #ahh4 igneous rocks of1 #dbi4 freshwater beds of1 #dbi4 ,cape ,breton1 coal measures of1 #cbd4 ,wrath1 granite veins in1 #ddd4 ,caradoc sandstone1 #cef4 ,carbonaceous shale1 #bga4 ,carbonate of lime scarce in metamorphic rocks1 #dhg4 ,carbonate of lime in rocks1 how tested1 #ab4 ,carboniferous group1 #cjh4 flora1 #caj4 period1 plutonic rocks of1 #def4 period1 volcanic rocks of1 #dcb4 reptiles1 #cce4 ,carne1 ,mr41 on ,cornish lodes1 #dia4 #dib4 ,carrara marble1 #dhb4 ,caryophyllia caespitosa1 bed of1 in ,sicily1 #aea4 ,castrogiovanni1 bent strata near1 #eh4 ,catalonia1 volcanic region of1 #djh4 ,cautley1 ,captain1 on ,sewalik hills1 #agc4 ,caves in ,europe1 #aee4 at ,kirkdale1 #aed4 in ,sicily1 #aec4 in ,australia1 #aef4 ,central ,france1 ,upper ,eocene of1 #agh4 ,cetacea1 fossil1 rarity of1 ,postscript1 xxi4 ,chalk1 pinnacle of1 near ,sherringham1 #abi4 of ,faxoe1 #baj4 and ,postscript1 xv4 white1 fossils of1 #bf4 white1 section of1 #baa4 white1 extent and origin of1 #bae4 white1 animal origin of1 #baf4 pebbles in1 #bag4 difference of1 in north and south of ,europe1 #bba4 ,chalk cliffs1 inland1 on ,seine1 #bch4 needles of1 in ,normandy1 #bda4 flints1 bed of1 near ,barcombe1 #bec4 ,chambers1 ,mr41 cited1 #hh4 ,chamisso1 cited1 #bag4 ,chara1 in freshwater strata1 #ca4 in flints of ,cantal1 #ahi4 in ,eocene strata of ,france1 #agf4 in ,purbeck beds1 #bcb4 ,charlesworth1 ,mr4 ,e41 cited1 on ,crag1 #afb4 ,charpentier1 ,m41 on ,alpine glaciers1 #adj4 on ,swiss glaciers1 #adc4 ,cheirotherium1 footprints of1 #bij4 #ccg4 ,chemical and mechanical deposits1 #cc4 ,chili1 earthquake in1 #fa4 gold mines in1 #dgb4 ,chiloe1 rocks drifted from ,andes to1 #add4 ,chlorite schist1 #dfe4 ,christiania1 dike near1 #chj4 trap rocks1 passage of granite into1 at1 #dda4 granite near1 #deg4 gneiss near1 #ddf4 intrusion of granite into beds near1 #ddf4 ,chronological groups1 #aja4 ,cinder-bed1 ,purbeck1 #bca4 ,claiborne1 marine shells of1 #bjf4 ,clausen1 ,mr41 cited1 #aeh4 ,clay1 defined1 #aa4 ,clay-slate1 #dfe4 #dfh4 ,clay-ironstone1 #cbf4 ,clays1 plastic1 #bjc4 ,cleavage of rocks1 #dfh4 ,climate of drift period1 #aci4 of coal period1 #cce4 ,coal1 zigzag flexures of1 near ,mons group1 #cjh4 measures1 #cjh4 #cji4 how formed1 #cag4 pipes1 danger of1 #cah4 mine1 near ,lyons1 #cai4 seam at ,brownsville1 ,pennsylvania1 view of1 #ccb4 conversion of into lignite1 #ccc4 formation at ,brora1 #bgb4 seams1 continuity of1 #ccd4 period1 climate of1 #cce4 strata1 footprints of reptiles in1 #ccg4 ,coal-field at ,burdiehouse1 #cbe4 of ,ashby-de-la-,zouch1 #fi4 ,united ,states1 diagram of1 #cbg4 of ,yorkshire1 fossils of1 #cbe4 ,coalbrook ,dale1 beetles in coal of1 #cce4 fossil cones in1 #cac4 coal measures of1 #cbd4 faults in1 #fb4 ,cockfield ,fell1 rocks altered by dikes1 #chc4 ,columbia1 vinegar river of1 #aia4 ,colchester1 ,mr41 on mammalian remains at ,kyson1 #bjc4 ,come1 ravine in lava of1 #dbg4 ,cones in ,val di ,noto1 #chi4 and craters1 absence of1 in ,england1 #f4 and craters1 #cfg4 ,conifers1 fossil trees1 #caf4 ,concretionary structure1 #cg4 ,conglomerate1 or pudding-stone1 #aa4 dolomitic1 #cje4 vertical in ,scotland1 c41 #dg4 ,connecticut1 valley of the1 #big4 beds1 antiquity of1 #cjj4 ,conrad1 ,mr41 on cretaceous rocks1 #bbd4 ,conybeare1 ,mr41 cited1 #fd4 #fi4 #bdd4 #bgd4 on ,plesiosaurus1 #bgh4 on oolite and lias1 #bhc4 on term ,poikilitic1 #bhf4 on crocodiles1 #bja4 ,cook1 ,capt41 on ,fucus giganteus1 #bag4 ,coprolites in chalk1 #baf4 ,coralline crag1 fossils in1 #afd4 ,coral islands and reefs1 #cd4 #df4 rag of ,oolite1 #bfj4 ,corals1 figures of1 in crag1 #afe4 of ,devonian system1 #cdf4 of ,devonian strata in ,united ,states1 #cdi4 in ,wenlock formation1 #cee4 ,corinth1 corrosion of rocks by gases near1 #dgg4 ,cornbrash1 #bfc4 ,cornwall1 granite veins in1 #dde4 #dgd4 mineral veins in1 #dij4 #did4 tin of1 newer than ,irish copper1 #dii4 ,cotta1 ,dr4 ,b41 on granite in ,saxony1 #dei4 ,crag coralline1 fossils in1 #afd4 comparison of faluns and1 #agj4 of ,suffolk1 red and coralline1 #aje4 #afb4 fluvio-marine1 ,norwich1 #adh4 ,craigleith fossil trees1 #dj4 quarry1 slanting tree in1 #cbj4 ,crater of ,island of ,st4 ,paul1 #cie4 ,craven fault1 #fd4 ,creeps in coal-mines described1 #eb4 ,credneria in ,quadersandstein1 ,postscript1 xvi4 ,cretaceous rocks of ,pyrenees1 #dee4 group1 #bji4 #bai4 and ,postscript1 xvi4 strata in ,south ,america and ,india1 #bbe4 period1 plutonic rocks of1 #dee4 volcanic rocks1 #dca4 rocks in ,united ,states1 #bbd4 ,crocodiles near ,cuba1 #bgi4 ,croizet1 ,m41 on ,auvergne fossil mammalia1 #ahh4 ,cromer1 contorted drift near1 #abi4 ,crop out1 term explained1 #ee4 ,crust of earth defined1 #b4 ,crystalline limestone1 #cjb4 rocks1 erroneously termed primitive1 #i4 schists defined1 #g4 ,curved strata1 #dg4 strata1 experiments to illustrate1 #di4 ,cutch1 ,runn of1 #bie4 ,cuvier1 ,m41 on ,eocene formation1 #age4 on ,amphitherium1 #bfh4 cited1 #aib4 on tertiary strata near ,paris1 #ajd4 on fossils of ,montmartre1 #aia4 ,cyclopian ,islands1 #dja4 ,cypris in ,lias1 #bha4 in ,wealden1 #bbh4 in marl of ,auvergne1 #ahc4 ,cystideae in ,silurian rocks1 #ceh4 ,d4 ,dana1 ,mr41 on coprolites of birds1 #bii4 on coral reef in ,sandwich ,islands1 #baf4 on volcanos of ,sandwich ,islands1 #cid4 #djf4 #dbc4 ,dartmoor1 granite of1 #def4 ,darwin1 ,mr41 cited1 #bag4 on boulders and glaciers in ,south ,america1 #add4 on cleavage in ,south ,america1 #dga4 on coral islands of ,pacific1 #baf4 on dike in ,st4 ,helena1 #djf4 on habits of ostrich1 #bii4 and ,postscript1 xx4 on fossils in ,south ,america1 #adh4 on ,fucus giganteus1 #bag4 on gradual rise of part of ,s4 ,america1 #df4 on lamination of volcanic rocks1 #dhj4 on parallel roads1 #hg4 on plutonic rocks of ,andes1 #dec4 on recent strata near ,lima1 #aae4 on saurians in ,galapagos ,islands1 #bgi4 on sinking of coral reefs1 #df4 on ,welsh glaciers1 #aca4 ,daubeny1 ,dr41 on the ,solfatara1 #dgg4 ,daubeny1 ,dr41 on volcanos in ,auvergne1 #dbh4 ,dax1 inland cliff at1 #gb4 ,deane1 ,dr41 on footprints1 #bih4 ,dean1 forest of1 coal in1 #ccd4 ,dechen1 ,prof4 von1 on reptiles in ,saarbrueck coal-field1 #ccf4 ,de ,koninck1 cited1 #agf4 #agh4 ,de la ,beche1 ,sir ,h41 cited1 #bca4 #bcc4 #bha4 on ,carrara marble1 #dhb4 on clay beds1 #bhc4 on clay-ironstone1 #cbf4 on coal-measures near ,swansea1 #cji4 on fossil trees1 ,s4 ,wales1 #cah4 on granite of ,dartmoor1 #dgd4 on mineral veins1 #dic4 #die4 #dih4 on term supracretaceous1 #ajc4 on trap of ,new ,red ,sandstone period1 #dcb4 ,deluge1 #d4 ,denudation explained1 #ff4 of the ,weald ,valley1 #bdb4 terraces of1 in ,sicily1 #ge4 ,derbyshire1 lead veins of1 #dig4 ,deshayes1 ,m41 identification of shells1 #agf4 on fossil shells in ,hungary1 #dba4 on ,lower ,eocene shells1 #aif4 on tertiary classification1 #aaj4 ,desmarest1 cited1 #ahc4 on trappean rocks1 #ia4 ,desnoyers1 ,m41 on ,faluns of ,touraine1 #ajf4 ,desor1 ,m41 on glacial fauna in ,n4 ,america1 #acc4 ,devonian flora1 #cdi4 strata in ,united ,states1 #cdi4 system1 term explained1 #cdf4 ,diagonal1 or cross stratification1 #af4 ,dicotyledonous leaves in chalk1 ,postscript1 xvi4 ,dike in ,st4 ,helena1 #djf4 ,dikes at ,palagonia in ,sicily1 #djg4 trappean1 crystalline in centre1 #chj4 defined1 #f4 in ,scotland1 #cgh4 of ,somma1 #djd4 ,diluvium1 popular explanation of term1 #acb4 ,dip1 term explained1 #ec4 ,dolerite1 or greenstone1 #cgb4 ,dolomite defined1 #ac4 ,dolomitic conglomerate1 #cje4 ,doue1 ,m4 ,b4 de1 on volcanos of ,velay1 #dbh4 ,drift contorted1 near ,cromer1 #abi4 in ,ireland1 #aca4 in ,norfolk1 #abf4 meteorites in1 #ade4 northern1 in ,scotland1 #abe4 northern1 in ,north ,wales1 #acj4 of ,scandinavia1 ,north ,germany1 and ,russia1 #aba4 period1 climate of1 #aci4 period1 subsidence in1 #ace4 shells in ,canada1 #acd4 ,dudley limestone1 #ced4 shales of coal near1 #dgd4 ,dufrenoy1 ,m41 on granite of ,pyrenees1 #dge4 ,duff1 ,mr4 ,p41 on reptile of ,old ,red1 ,postscript1 ix4 on hill of ,gergovia1 #dcj4 ,dunker1 ,dr41 on ,wealden of ,hanover1 #bcg4 ,e4 ,echinoderms of coralline crag1 #aff4 ,echinus1 figure of1 #bc4 ,egerton1 ,mr41 on fossils of ,southern ,india1 #bbe4 ,egerton1 ,sir ,p41 on fish of marl slate1 #cjd4 on fossil fish of ,connecticut beds1 #cjj4 on fossils of ,isle of ,wight1 #aih4 on saurians and fish in ,new ,red ,sandstone1 #bhi4 on ,ichthyosaurus1 #bgf4 ,eggs1 fossil1 of snake1 #abj4 ,ehrenberg1 ,prof41 on bog-iron ore1 #bf4 on infusoria1 #bd4 ,elephant bed1 ,brighton1 #bef4 ,elephas primigenius1 jaw figured1 #aei4 ,elvans of ,ireland and ,cornwall1 #dih4 term explained1 #deg4 ,encrinites1 figure of1 #bfd4 ,endogens1 #caf4 ,eocene1 foraminifera1 #aid4 formations1 #agd4 formations in ,england1 #aig4 granite1 #dea4 lower1 in ,france1 #agf-aia4 middle1 in ,france1 #aia4 strata1 in ,united ,states1 #bjf4 upper1 near ,louvain1 #agg4 term defined1 #aaa4 upper1 of ,central ,france1 #agh4 volcanic rocks1 #dbi4 ,equisetaceae1 #cac4 ,equisetum of ,virginian oolite1 #bhd4 ,equisetum giganteum1 #cad4 ,erman on meteoric iron in ,russia1 #ade4 ,erratics1 ,alpine1 #adj4 northern origin of1 #abc4 ,escher1 ,m41 on boulders of ,jura1 #adc4 ,etna1 deposits of1 #dja4 ,eurite1 #ddj4 ,euritic porphyry described1 #ddg4 ,exogens1 #caf4 ,f4 ,faluns of ,touraine1 #ajf4 #afh4 ,faluns1 comparison of1 and crag1 #agj4 ,falconer1 ,dr41 on ,sewalik ,hills1 #agc4 ,falkland ,islands1 #hh4 ,farnham1 phosphate of lime near1 #bai4 ,fault1 term explained1 #fb4 ,faults1 origin of1 #fd4 ,faxoe1 chalk of1 #baj4 and ,postscript1 xv4 ,felixstow1 remains of cetacea found near1 #aff4 ,felspar1 #cfi4 ,ferns in coal-measures1 #caj4 ,fife1 altered rock in1 #chc4 ,fifeshire1 trap dike in1 #dcd4 ,megalichthys found in ,cannel coal in1 #ccf4 ,fishes1 fossil1 of ,upper ,cretaceous1 #bad4 of ,old ,red ,sandstone1 #cdc4 of ,wealden1 #bbi4 fossil1 of brown coal1 #daf4 ,fissures filled with metallic matter1 #dij4 ,see mineral veins4 ,fitton1 ,dr41 on division of lower cretaceous formation1 #bai4 cited1 #bbg4 #bca4 #bcc4 #bcg4 #bdd4 #bdg4 ,fleming1 ,dr41 on scales of fish in ,old ,red1 #cdc4 on trap-rocks in coal-field of ,forth1 #dcb4 on trap dike in ,fifeshire1 #dcd4 ,flora1 carboniferous1 #caj4 cretaceous1 #bbc4 ,devonian1 #cdi4 of ,london ,clay1 #bjj4 permian1 #cje4 #cjg4 ,floetz1 term explained1 #ia4 ,flysch1 explanation of term1 #bjf4 ,footprints of birds1 #big4 and ,postscript1 xx4 of reptilians1 #ccg4 fossil1 #bhi4 #bij4 #bia4 #big4 ,foraminifera in chalk1 #bf4 ,eocene1 #aid4 ,forbes1 ,prof4 ,e41 on ,caradoc sandstone1 #cei4 on ,cystideae1 #ceh4 on shells in crag deposits1 #afb4 on cretaceous fossil shells1 #bbd4 on fossils of the faluns1 #afi4 on fossils in drift in ,south ,ireland1 #aca4 on deep-sea origin of ,silurian strata1 #cfj4 on echinoderms of coralline crag1 #aff4 on fauna of boulder period1 #abe4 on migrations of mollusca in glacial period1 #aff4 on fossils of ,purbeck group1 #bca4 #bcc4 on strata at ,atherfield1 #bai4 on changes of ,wealden testacea1 #bce4 on volcanic rocks of ,oolite period1 #dcb4 on depth of animal life in ,a,egean1 #ce4 #acg4 cited1 #bbe4 ,forbes1 ,prof4 ,james1 on zones in volcanic rocks1 #dhj4 on the ,alps1 #adc4 ,forchhammer1 on scratched limestone1 #abb4 ,forest1 fossil1 in ,norfolk1 #abg4 #acj4 ,forfarshire1 ,old ,red ,sandstone in1 #dgi4 ,formation1 term defined1 #c4 ,fossil1 term defined1 #d4 ,fossils of chalk and greensand1 figures of1 #bab4 in chalk at ,faxoe1 #baj4 of coralline crag1 #afd4 of ,devonian system1 #cdf4 and ,postscript1 x4 xi4 of ,eocene strata in ,united ,states1 #bjg4 in faluns of ,touraine1 #afi4 freshwater and marine1 #bg4 of ,isle of ,wight1 #aih4 of ,lias1 #bgd4 of ,ludlow formation1 #ceb4 of mountain limestone1 #cdj4 of ,london ,clay1 #bjj4 of ,maestricht beds1 #bji4 of ,lower ,greensand1 #bbj4 of ,new ,red ,sandstone1 #bhg4 and ,postscript1 xiii4 of ,oolite1 #bei4 #bff4 of ,red ,crag1 #afd4 of ,silurian rocks1 #cec4 and ,postscript1 vii4 of ,solenhofen1 #bfj4 of ,upper ,greensand1 #bah4 of ,wealden1 #bcf4 test of the age of formations1 #ih4 ,fossil fish of ,permian limestone1 #cjc4 of ,connecticut beds1 #cjj4 of ,richmond1 ,u4 ,s41 strata1 #bhe4 of ,old ,red ,sandstone1 #cdc4 scales of ,permian1 figured1 #cje4 footsteps1 #bhi4 #bij4 #bia4 ferns in carbonaceous shale1 #bga4 forest in ,nova ,scotia1 #cba4 forest near ,wolverhampton1 #cai4 forest in ,isle of ,portland1 #bcc4 plants in ,wealden1 #bcj4 plants of ,lias1 #bhb4 plants of ,bunter sandstein1 #bhh4 trees erect1 #cag4 wood1 petrifaction of1 #ci4 wood perforated by ,teredina1 #bd4 remains in caves1 #aed4 shells from ,etna1 #dja4 shells near ,grignon1 #aic4 shells of ,mayence strata1 #agh4 shells in ,virginia1 #agb4 ,fossiliferous strata1 tabular view of1 #cfa4 ,fournet1 ,m41 on mineral veins of ,auvergne1 #dic4 on disintegration of rocks1 #dgf4 on quartz1 #dci4 ,fox1 ,mr4 ,r4 ,w41 #dgb4 on ,cornish lodes1 #dig4 ,fox1 ,rev4 ,mr41 on extinct quadrupeds of ,isle of ,wight1 #aih4 ,freshwater beds of ,isle of ,wight1 #aig4 deposits in valley of ,thames1 #adf4 land shells numerous in1 #bg4 ,freshwater formations of ,auvergne1 #ahf4 ,freshwater formation1 how distinguished from marine1 #bg4 #bh4 #cj4 remains of fish in1 #cb4 associated with ,norfolk drift1 #abg4 ,chara in1 #ca4 ,cypris in1 #ca4 ,freshwater shells in brown coal near ,bonn1 #dag4 ,fucus giganteus1 #bag4 vesiculosus1 growth of1 in ,jutland1 #bag4 vesiculosus in ,lym-,fiord1 #cc4 ,fundy1 ,bay of1 impressions in red mud of1 #big4 ,g4 ,gaillonella fossil in ,tripoli1 #be4 ferruginea in bog-iron ore1 #bf4 ,galapagos ,islands1 animals of1 #bgi4 ,garnets in altered rock1 #chb4 ,gases1 subterranean rocks altered by1 #dgf4 ,gault1 #bah4 ,gavarnie1 flexures of strata1 #ei4 ,geology defined1 #a4 ,gergovia1 hill of1 #dcj4 ,giant's ,causeway1 columns at1 #chd4 ,gibbes1 ,r4 ,w41 cited1 #bjg4 ,glacial phenomena1 northern1 origin of1 #acb4 ,glaciers1 ,alpine1 #adj4 ,glaciers on ,caernarvonshire mountains1 #acj4 ,glasgow1 marine strata near1 #adh4 ,glen ,roy1 parallel roads of1 #hf4 ,glen ,tilt1 granite of1 #ddb4 ,gneiss1 altered by granite1 #dde4 in ,bernese ,alps1 #dhd4 at ,cape ,wrath1 #ddd4 near ,christiania1 #ddf4 described1 #dfd4 ,gold1 age of1 in ,ireland1 #dih4 age of1 in ,ural ,mountains1 #dii4 ,goldfuss1 ,prof41 on reptiles in coal-field1 #ccf4 ,goeppert1 ,prof41 on beds of coal1 #caf4 on petrifaction1 #dj4 ,graham's ,island1 #chi4 #djg4 ,grampians1 old red conglomerates in1 #dg4 ,granite described1 #g4 #dcf4 #dch4 #ddd4 passage of into trap1 #dda4 porphyritic1 #dci4 and limestone1 junction of in ,glen ,tilt1 #ddb4 syenitic1 #ddj4 talcose1 #ddj4 schorly1 #ddj4 of ,cornwall and ,dartmoor1 #dgd4 of ,swiss ,alps1 #dhd4 rocks in connection with mineral veins1 #ejj4 of ,saxony1 #dei4 ,granites1 oldest1 #deh4 varieties of1 #ddd4 veins in ,cornwall1 #dde4 veins in ,cape ,wrath1 #ddd4 veins in ,table ,mountain1 #ddc4 vein in ,white ,mountains1 #dej4 of ,arran1 age of1 #dei4 near ,christiania1 #deg4 dikes in ,mount ,battock1 #ddc4 ,graphite1 powder of1 consolidated by pressure1 #ch4 ,graptolites1 #ceg4 ,grateloup1 ,m41 on fossils in chalk1 #bbc4 ,grauwacke1 term explained1 #cej4 ,greenland1 sinking of coast1 #df4 ,greensand1 upper1 #bah4 fossils of1 #bab4 ,greensburg1 ,pennsylvania1 footprints of reptile in coal strata at1 #ccg4 ,greenstone or ,dolerite1 #cgb4 dike of1 in ,arran1 #cgi4 ,gres de ,beauchamp1 ,paris ,basin1 #aic4 ,grignon1 fossil shells near1 #aic4 ,grit defined1 #aa4 ,guadaloupe1 human skeleton of1 #aae4 ,guidoni on ,carrara marble1 #dhb4 ,gutbier1 ,col4 von1 on ,permian flora1 #cje4 #cjg4 ,gryphaea1 fossil figure of1 #bb4 ,gypseous marls1 #ahf4 series1 #aia4 ,gypsum defined1 #ac4 ,h4 ,hall1 ,sir ,jas41 experiments on fused minerals1 #djf4 on curved strata1 #dh4 ,capt4 ,b41 cited1 #cgh4 #dja4 #ddc4 ,hamilton1 ,sir ,w41 on eruption of ,vesuvius1 #dje4 ,harris1 ,major1 on salt lake in ,ethiopia1 #bif4 ,hartz1 ,bunter sandstein of1 #bhh4 ,hastings1 ,lady1 fossils collected by1 #aih4 ,hastings sand1 #bbi4 bed1 shells of1 #bbi4 ,hautes ,alpes1 rocks of1 #dee4 ,hauey cited1 #cfi4 ,hawkshaw1 ,mr41 on fossil trees in coal1 #cag4 ,hayes1 ,t4 ,l41 on icebergs1 #abc4 ,hebert1 ,m41 cited on ,upper ,eocene beds1 #agf4 ,hebrides1 dikes of trap in1 #cgi4 ,heidelberg1 varieties of granite near1 #ddd4 ,henfrey1 ,mr4 ,a41 on food of ,mastodon1 #ach4 ,henslow1 ,prof41 on fossil cetacea in ,suffolk1 #aff4 on fossil forests1 #bcc4 on dike and altered rock near ,plas ,newydd1 #cha4 ,henry1 ,mr41 cited1 #dgf4 ,herschel1 ,sir ,j41 on slaty cleavage1 #dgb4 ,hertfordshire pudding-stone1 #ce4 ,hibbert1 ,dr41 on volcanic rocks1 #dbh4 on coal field at ,burdiehouse1 #cbe4 cited1 #dai4 ,high ,teesdale1 garnets in altered rock at1 #chb4 ,hildburghausen1 footprints of reptile at1 #bhi4 #bij4 ,hippurite limestone1 #bba4 ,hitchcock1 ,prof41 on footprints1 #big4 ,hoffmann1 ,mr41 on ,lipari ,islands1 cited1 #dgf4 on cave near ,palermo1 #gd4 on ,carrara marble1 #dhb4 ,hooghly river1 analysis of water1 #da4 ,hopkins1 ,mr41 on fractures in ,weald1 #bea4 ,horizontality of strata1 #ae4 of roads of ,lochaber1 #hh4 ,hornblende1 #cfi4 schist1 #dfd4 #dgh4 ,horner1 ,mr41 on geology of ,eifel1 #dae4 on ,megalichthys1 #ccf4 ,hubbard1 ,prof41 on granite vein in ,white ,mountains1 #dej4 ,hugi1 ,m41 on ,swiss ,alps1 #dhd4 ,humboldt1 cited1 #cad4 on uniform character of rocks1 #dhf4 ,hungary1 trachyte of1 #ddb4 volcanic rocks of1 #dba4 ,hunt1 ,mr41 experiments on clay-ironstone1 #cbf4 ,hutton1 opinions of1 #fj4 ,huttonian theory1 #ib4 ,hypogene1 term defined1 #i4 rocks1 mineral character of1 #dhe4 or metamorphic limestone1 #dfe4 ,i4 ,ibbetson1 ,capt41 on chalk ,isle of ,wight1 #bae4 ,ice1 rocks drifted by1 #abb4 ,icebergs1 stranding of1 #abi4 #acg4 ,iceland1 icebergs drifted to1 #acg4 ,ichthyolites of ,old ,red ,sandstone1 #cdi4 ,ichthyosaurus communis1 figure of1 #bgg4 ,igneous rocks1 #f4 of ,siebengebirge and ,westerwald1 #dag4 rocks of ,val di ,noto1 #chi4 ,iguanodon ,mantelli1 #bbg4 #bbi4 ,india1 cretaceous system in1 #bbe4 freshwater deposits of1 #agc4 oolitic formation in1 #bhe4 ,indusial limestone1 ,auvergne1 #ahd4 ,infusoria in tripoli1 #bd4 ,inland sea-cliffs in ,south of ,england1 #ga4 ,insects in ,lias1 #bha4 ,ireland1 drift in1 #aca4 ,ischia1 volcanic cones in1 #djc4 ,post-,pliocene strata of1 #aac4 ,isle of ,wight1 freshwater beds of1 #aig4 ,isomorphism1 theory of1 #cgj4 ,j4 ,jackson1 ,dr4 ,c4 ,t41 analysis of fossil bones1 #ach4 ,james1 ,capt41 on fossils in drift ,south ,ireland1 #aca4 ,java1 stream of sulphureous water1 #aia4 ,jobert1 ,m41 on hill of ,gergovia1 #dcj4 ,joints1 #dfi4 ,jorullo1 lava stream of1 #dej4 ,jura1 alpine blocks on1 #adb4 limestone1 #bfa4 structure of1 #ee4 ,k4 ,kangaroo1 fossil and recent1 jaws figured1 #aef4 ,kaup1 ,prof41 on footprints of ,cheirotherium1 #bij4 ,kaye1 ,mr41 on fossils of ,southern ,india1 #bbe4 ,keeling ,island1 fragment of greenstone in1 #bag4 ,keilhau1 ,prof41 cited1 #deg4 #dgd4 on dike of greenstone1 #chj4 on gneiss near ,christiania1 #ddf4 on granite1 #ddg4 ,kelloway rock1 #cd4 ,kentish chalk1 sand-galls in1 #hb4 ,keuper1 the1 #bhg4 ,killas in granite of ,cornwall1 #dgd4 ,kimmeridge clay1 #bfj4 and ,postscript1 xxi4 ,king1 ,dr41 on footprints of reptile1 #ccg4 ,king1 ,mr41 on ,permian group and fossils1 #cja4 #cjb4 ,kirkdale1 cave at1 #aed4 ,kotzebue cited1 #bag4 ,kyson1 in ,suffolk1 strata of1 #bjb4 ,l4 ,labyrinthodon1 #bib4 #bhh4 #bhi4 ,lacustrine strata of ,auvergne1 #aha4 ,lagoons at mouth of rivers1 #cc4 of ,bermuda ,islands1 #baf4 ,lake craters of ,eifel1 #dai4 crater of ,laach1 #dbj4 ,lamarck on bivalve mollusca1 #bi4 ,land1 rising and sinking1 #de4 ,laterite1 #cgf4 ,lava1 #cgc4 current1 ,auvergne1 #dbe4 relation to trap1 #chg4 stream of ,jorullo1 #dej4 of ,stromboli1 #dej4 ,lea1 ,mr41 footprints of reptile discovered by1 #cdj4 ,lead1 veins of1 in ,permian rocks1 #dii4 ,lehman on classification of rocks1 #ij4 ,leibnitz1 theory of1 #id4 ,lepidodendra1 #cab4 ,lewes1 coomb near1 #bej4 ,lias1 #bgc4 period1 ,volcanic rocks1 #dca4 at ,lyme ,regis1 #bha4 plutonic rocks of1 #dee4 and oolite1 origin of1 #bhb4 fossil plants of1 #bhb4 ,liebig1 ,prof41 on conversion of coal into lignite1 #ccc4 on preservation of fossil bones in caverns1 #aee4 ,lima1 recent strata of1 #aae4 ,limagne d',auvergne1 freshwater formations of1 #ahg4 ,lime1 scarcity of1 in metamorphic rocks1 #dhg4 ,limestone1 brecciated1 #cjb4 crystalline1 #cjb4 compact1 #cjc4 fossiliferous1 #cjc4 hippurite1 #bba4 indusial1 ,auvergne1 #ahd4 of ,jura1 #bfa4 magnesian1 #cja4 mountain fossils of1 #cdj4 primary or metamorphic1 #dfe4 in ,germany1 of ,devonian system1 #cdh4 ,lindley1 ,dr41 cited1 #bbc4 on leaves in lignite1 #daf4 ,link1 ,m41 on footprints1 #bia4 ,lipari ,islands1 rocks altered by gases in1 #dgf4 ,lisbon1 marine tertiary strata near1 #aga4 ,lithodomi in beaches of ,n4 ,america1 #gh4 in inland cliffs1 #gc4 ,llandeilo flags1 #ceg4 ,loam defined1 #ac4 ,lochaber1 parallel roads of1 #hf4 ,lodes4 ,see ,mineral ,veins1 #dij4 ,loess of valley of ,rhine1 #aag4 fossil land shells of1 figured1 #abj4 ,logan1 ,mr41 on coal measures of ,south ,wales1 #caj4 on fossil forest in ,nova ,scotia1 #cbb4 on reptilian foot-prints in lowest ,silurian in ,canada1 ,postscript1 viii4 ,london clay1 #bjj4 ,lonsdale1 ,mr41 cited1 #aeb42 on corals1 #agc4 on corals of ,normandy1 #agj4 on corals in ,wenlock formation1 #cee4 on fossils in white chalk1 #bf4 on old red sandstone of ,s4 ,devon1 #cde4 on ,stonesfield slate1 #bff4 ,louvain1 ,eocene strata near1 #agg4 ,loven on shells of ,norway1 #aad4 ,ludlow formation1 #cea4 ,lund1 cited1 #aeh4 ,lycett1 ,mr41 on shells of oolite1 #bff4 ,lyme ,regis1 lias at1 #bha4 ,lym-,fiord invaded by the sea1 #cc4 kelp in1 #bag4 ,lyons1 coal mine near1 #cai4 ,m4 ,macacus1 in ,eocene formation1 #bjc4 ,maclaren1 ,mr41 on erratic blocks in ,pentlands1 #abe4 ,maclure1 ,dr41 on volcanos in ,catalonia1 #dji4 ,mac,culloch1 ,dr41 cited1 #ddb4 on altered rock in ,fife1 #chc4 on basaltic columns in ,skye1 #che4 on denudation1 #fg4 on granite of ,aberdeenshire1 #dda4 on igneous rocks of ,scotland1 #cij4 on ,isle of ,skye1 #cf4 #def4 on hornblende schist1 #dgh4 on overlying rocks1 #h4 on parallel roads1 #hg4 on pebbles of granite1 #dfj4 on trap vein in ,argyleshire1 #cgi4 ,madeira1 view of dike in inland valley in1 #cgh4 ,maestricht beds1 #bji4 ,magnesian limestone1 concretionary structure of1 #cg4 defined1 #ac4 groups1 #cja4 ,maidstone1 fossils in white chalk of1 #bad4 ,mammalia1 extinct1 above drift in ,united ,states1 #ach4 extinct1 of basin of ,mississippi1 #aaf4 fossil teeth of1 figured1 #afj4 ,mammat's ,geological ,facts cited1 #fi4 ,mammifer in trias near ,stuttgart1 ,postscript1 xiii4 ,mansfield in ,thuringia1 ,permian formation at1 #cjf4 ,mantell1 ,dr41 cited1 #bag4 #bbi4 #bca4 #bea4 on belemnite1 #bfc4 on chalk flints1 #bec4 on ,brighton elephant bed1 #beg4 on freshwater beds of ,isle of ,wight1 #aih4 on iguanodon1 #bbg4 on ,wealden group1 #bbf4 on reptile in ,old ,red1 ,postscript1 x4 ,marble defined1 #ab4 ,marl defined1 #ac4 in ,lake ,superior1 #cf4 red and green in ,england1 #bhi4 ,marl-slate defined1 #ac4 ,martin1 ,mr41 cited1 #bej4 on cross fractures in chalk1 #bde4 ,martins1 ,mr4 ,c41 on glaciers of ,spitzbergen1 #acf4 ,map to illustrate denudation of ,weald1 #bdb4 ,map of ,eocene beds of central ,france1 #agi4 ,massachusetts1 plumbago in1 #dgh4 ,mastodon angustidens1 jaw1 figure of1 #aei4 ,mastodon giganteus1 in ,united ,states1 #acg4 ,mayence tertiary strata1 #agg4 ,mediterranean and ,red ,sea1 distinct species in1 #ajj4 deposits forming in1 #ii4 ,megalichthys in ,cannel coal of ,fifeshire1 #ccf4 ,megatherium in ,south ,america1 #aeh4 ,menai ,straits1 marine shells in drift1 #acj4 ,mendips1 denudation in1 #fh4 ,metalliferous veins4 ,see ,mineral ,veins4 ,metals1 supposed relative ages of1 #dig4 ,metamorphic rocks1 #dfc4 defined1 #h4 why less calcareous than fossiliferous1 #dhg4 order of succession1 #dhe4 glossary of1 #dff4 ,metamorphic strata1 origin of1 #dfg4 ,metamorphic structure1 origin of1 #dgg4 ,meteorites in drift1 #ade4 ,mexico1 lamination of volcanic rocks in1 #dhj4 ,meyer1 ,m4 ,h4 von1 cited1 #adg4 on fossil mammalia of ,rhine1 #agh4 on reptile in coal1 #ccf4 #ccg4 on sandstone of ,vosges1 #bhh4 on ,wealden of ,hanover and ,westphalia1 #bcg4 ,mica schist1 #dfe4 ,micaceous sandstone1 origin of1 #ad4 ,microlestes antiquus1 triassic mammifer1 ,postscr41 xiv4 ,miller1 ,mr4 ,h41 on origin of rock salt1 #bie4 on old red sandstone1 #cdc4 on fossil trees of coal near ,edinburgh1 #cba4 ,minchinhampton1 fossil shells at1 #bff4 ,mineral character of aqueous rocks1 #ig4 composition1 test of age of volcanic rocks1 #cii4 springs1 connected with mineral veins1 #dif4 veins and faults1 #dhh4 #dij4 of different ages1 #dij4 #dih4 #dii4 veins1 pebbles in1 #dib4 subsequently enlarged and re-opened1 #dib4 veins1 various forms of1 #dhi4 veins near granite1 #dif4 ,mineralization of organic remains1 #ch4 ,miocene formations1 #afh4 in ,united ,states1 #aga4 period1 volcanic rocks of1 #dae4 term defined1 #aaa4 ,mississippi1 fluviatile strata and delta of1 #aae4 #aaf4 ,mitchell1 ,sir ,t41 on ,australian caves1 #aef4 ,mitscherlich1 ,prof41 on augite and hornblende1 #cfi4 on isomorphism1 #cgj4 on mineral composition of ,somma1 #djd4 ,modon1 lithodomi in cliff at1 #gc4 ,molasse of ,switzerland1 #aga4 ,mons1 flexures of coal at1 #ec4 ,mont ,blanc1 granite of1 #dec4 ,mont ,dor1 ,auvergne1 #dbb4 ,monte ,calvo1 section of1 #ah4 ,montlosier1 ,m41 on ,auvergne volcanos1 #dbg4 ,moraine1 term explained1 #abc4 ,moraines of glaciers1 #ada4 ,morea1 inland sea-cliffs of1 #gc4 trap of1 #dca4 ,morris1 ,mr41 cited1 #agg4 on fossils at ,brentford1 #adg4 ,morton1 ,dr41 on cretaceous rocks1 #bbd4 ,morven1 basaltic columns in1 #che4 ,mosasaurus in ,st4 ,peter's ,mount1 #baj4 ,mountain limestone1 fossils of1 #cdj4 ,munster1 ,count1 on fossils of ,solenhofen1 #bfj4 ,murchison1 ,sir ,r41 cited1 #bdh4 #cbd4 on new red sandstone1 #bij4 on age of ,alps1 #bjf4 on age of gold in ,russia1 #dii4 on erratic blocks of ,alps1 #add4 on granite1 #def4 #dei4 on primary strata in ,russia1 #abd4 on joints and cleavage1 #dfi4 #dga4 on old red sandstone of ,s4 ,devon1 #cde4 #cdh4 on pentamerus1 #cec4 on ,permian flora1 #cje4 on ,silurian strata of ,shropshire1 #dcd4 on ,swiss ,alps1 #dhd4 on term ,permian1 #cja4 on term ,silurian1 #cej4 on tilestones1 #cea4 ,muschelkalk1 #bhg4 ,n4 ,naples1 post-pliocene formations near1 #djc4 recent strata near1 #aab4 ,navarino1 lithodomi found in cliff at1 #gc4 ,necker1 ,m4 ,l4 ,a41 cited1 #dde4 on composition of cone of ,somma1 #djd4 on granite in ,arran1 #dfj4 on granitic rocks1 #ddg4 on ,swiss ,alps1 #dhd4 terms granite underlying1 #h4 ,nelson1 ,lieut41 drawing of ,bermuda1 #gi4 on ,bermuda ,island1 #baf4 ,neptunian theory1 #ia4 ,newcastle coal field1 great faults in1 #fd4 ,newcastle1 fossil tree near1 #cab4 #cah4 ,new ,jersey1 ,mastodon giganteus in1 #acg4 ,new red sandstone1 distinction from old1 #bhf4 its subdivisions1 #bhg4 of ,united ,states1 #big4 trap of1 #dcb4 ,new ,zealand1 absence of quadrupeds1 #aeh4 ,niagara1 recent shells in valley of1 #ach4 ,noeggerath1 ,m41 cited1 #dae4 ,nomenclature1 changes of1 #ic4 ,norfolk1 buried forest1 #abg4 #acj4 #adg4 drift1 #abf4 ,normandy chalk1 cliffs1 and needles1 #bda4 ,northwich1 beds of salt at1 #bid4 ,norwich crag1 fluvio-marine1 #adh4 sand-pipes near1 #hb4 ,nova ,scotia1 coal seams of ,cape ,breton1 #cae4 fossil forest of coal in1 #cba4 ,nummulites1 figures of1 #bjj4 #bje4 ,nummulitic formation1 #bje4 ,nyst1 ,m41 cited1 #agf4 ,o4 ,oeynhausen1 ,m4 von1 on ,cornish granite veins1 #dde4 ,olot1 extinct volcanos near1 #djh4 ,old red sandstone1 #cdb4 in ,forfarshire1 #dgh4 trap of1 #dcd4 ,oolite1 #beg4 and lias1 origin of1 #bhb4 inferior1 fossils of1 #bgb4 in ,france1 #bei4 plutonic rocks of1 #dee4 term defined1 #ab4 volcanic rocks of1 #dca4 ,oolitic group in ,france1 #bhc4 ,orbigny1 ,m4 d'1 cited1 #bbb4 on fossils of nummulitic limestone1 #bjf4 on subdivisions of cretaceous series1 #bji4 ,organic remains1 criterion of age of formation1 #ih4 test of age of volcanic rocks1 #cii4 ,ormerod1 ,mr41 on trias of ,cheshire1 #bie4 ,overlying1 term applied to volcanic rocks1 #h4 ,owen1 ,prof41 cited1 #aee4 #aff4 #bbi4 #bfg4 #bfh4 #bgj4 #bia4 on amphitherium1 #bfi4 on birds in ,new ,zealand1 #aeh4 on caves in ,england1 #aed4 on footprints1 #bih4 on fossils in ,australia1 #aef4 on fossil monkey1 #bjb4 on fossil quadrupeds1 #aeg4 on ichthyosaurus1 #bgf4 on reptile in coal1 #ccg4 on serpent of ,bracklesham1 #aii4 on snake at ,sheppey1 #bja4 on thecodont saurians1 #cjf4 on zeuglodon1 #bjg4 #bjh4 on reptile in ,silurian rocks1 ,postscript1 viii4 ,oxford clay1 #bfb4 ,oyster beds1 #bjd4 ,p4 ,pacific1 coral reefs of1 #bae4 ,palaeontology1 term explained1 #ajc4 ,palagonia1 dikes at1 #djg4 ,paleotherium magnum1 figure of1 #aib4 tooth of1 #aic4 ,palermo1 caves near1 #gd4 ,palma1 ,isle of1 map and view of1 #cia4 ,parallel roads1 #hf4 ,pareto1 ,m41 on ,carrara marble1 #dhb4 ,paris basin1 #ic4 ,parkinson1 ,mr41 on crag1 #aje4 ,parrot1 ,dr4 ,f41 on salt lakes of ,asia1 #bie4 ,pebbles in chalk1 #bag4 ,pegmatite1 #ddj4 ,pentamerus ,knightii1 #ceb4 ,pentland hills1 ,mr4 ,maclaren on1 #abe4 ,pepys1 ,mr41 cited1 #da4 ,permian flora1 distinct from coal1 #cje4 formation in ,thuringia1 #cjf4 group1 term explained1 #cja4 ,petrifaction of fossil wood1 #ci4 ,petrifaction1 process of1 #dc4 ,philippi1 ,dr41 on fossil shells near ,naples1 #aac4 on marine shells in caves of ,sicily1 #aed4 on tertiary shells of ,sicily1 #aej4 ,phillips1 ,prof41 cited1 #bgd4 #cji4 on cleavage1 #dga4 on terminology1 #ajc4 ,phillips1 ,mr4 ,w41 on kaolin of ,china1 #aa4 ,phosphate of lime1 #bai4 ,phryganea1 figure of1 #ahe4 indusiae of1 #ahf4 ,pictou1 ,nova ,scotia1 calamites near1 #cai4 ,pilla1 ,m41 on age of ,carrara marble1 #dhb4 ,planitz1 tripoli of1 #bf4 ,plas ,newydd1 rock altered by dike near1 #cha4 ,plastic clays1 #bjc4 ,playfair1 cited1 #de4 #ib4 #chc4 on faults1 #fb4 on ,huttonian theory of stratification1 #fj4 ,plesiosaurus1 figure of1 #bgg4 ,plieninger1 ,professor1 on triassic mammifer1 ,postscript1 xiii4 ,pliocene1 newer period1 #aba4 newer1 strata1 #adf4 strata in ,sicily1 #aej4 older1 in ,united ,states1 #aga4 strata1 #afa4 period1 volcanic rocks of1 #djg4 #djh4 term defined1 #aaa4 ,plomb du ,cantal1 described1 #dbi4 ,plumbago in ,massachusetts1 #dgh4 ,plutonic rocks1 #g4 #ddf4 age of1 #dci4 of carboniferous period1 #def4 of oolite and lias1 #dee4 recent and pliocene1 #dej4 of ,silurian period1 #deg4 age1 how tested1 #ddi4 ,plutonic and sedimentary rocks1 diagram of1 #deb4 ,poggendorf1 cited1 #dgf4 ,poikilitic formation1 #cja4 term explained1 #bhf4 ,pomel1 ,m41 on mammalia of ,auvergne1 #ahh4 #dbe4 ,ponza ,islands1 structure of1 #chg4 #dhj4 ,porphyritic granite1 #dci4 ,porphyry1 #cgb4 ,portland1 ,isle of1 fossil forest in1 #bcc4 ,portland stone1 #bei4 ,post-pliocene formations1 #aaa4 period1 volcanic rocks1 #dja4 ,potsdam sandstone1 reptilian1 ,postscript1 vii4 xviii4 ,pottsville1 coal seams near1 #cbi4 footprints of reptile near1 #cdj4 ,pozzolana1 #cf4 ,pratt1 ,mr41 on ammonites1 #bfb4 on extinct quadrupeds of ,isle of ,wight1 #aih4 ,predazzo1 altered rocks at1 #def4 ,prestwich1 ,mr41 cited1 #fi4 on ,english ,eocene strata1 #aig4 #aih4 #bjj4 on coal measures of ,coalbrook ,dale1 #fb4 #cbd4 ,prevost1 ,m4 ,c41 on ,paris basin1 #age4 #agf4 #aie4 ,progressive development1 theory of1 ,postscript1 xvi4 ,psaronites in ,germany and ,france1 #cjg4 ,pumice1 #cgc4 ,purbeck beds1 #bca4 ,puy de ,tartaret1 #dbe4 ,puy de ,pariou1 #dbh4 ,puzzuoli1 elevation and depression of land at1 #djc4 ,pyrenees1 cretaceous rocks of1 #dee4 curvatures of strata1 #eh4 granite of1 #dge4 nummulitic formation of1 #bje4 ,q4 ,quadrumana fossil1 ,postscript1 xvii4 ,quarrington ,hill1 basaltic dike near1 #cih4 ,quartz1 #dch4 ,quartzite1 or quartz rock1 #dfe4 ,r4 ,radnorshire1 stratified trap of1 #dbe4 ,rain-prints1 fossil in coal shale1 ,postscript1 xii4 ,ramsay1 ,prof4 ,a4 ,c41 on denudation1 #fh4 on granite in ,arran1 #dfj4 on section near ,bristol1 #ajb4 on ,welsh glaciers1 #aca4 ,recent strata defined1 #aab4 near ,naples1 #aab4 ,redfield1 ,mr41 on glacial fauna in ,america1 #acc4 on fossil fish1 #cjj4 ,red sandstone1 origin of1 #bic4 ,red ,sea and ,mediterranean1 distinct species in1 #ajj4 ,red ,sea1 saltness of1 #bif4 ,reptiles1 carboniferous1 #cce4 #ccf4 of lias1 #bgf4 fossil eggs of1 #abj4 ,reptile1 in ,lower ,silurian1 ,postscript1 vii4 in ,old ,red ,sandstone of ,morayshire1 ,postscript1 ix4 ,rhine1 valley1 loess of1 #aag4 ,ripple-mark1 formation of1 #ai4 ,river channels1 ancient1 #ccd4 ,river1 excavation through lava by1 #dac4 terraces1 #he4 ,rock1 term defined1 #b4 ,rocks1 four classes of1 contemporaneous1 #i4 classification of1 #ij4 composed of fossil zoophytes and shells1 #bd4 trappean1 #ia4 ,roderberg1 extinct volcano of1 #dbj4 ,rogers1 ,prof4 ,h4 ,d41 on coal field1 ,united ,states1 #cbh4 cited1 #cdj4 on reptilian footprints in coal1 ,postscript1 xi4 ,rogers1 ,prof4 ,w4 ,b41 on oolitic coal field1 ,united ,states1 #bhd4 #cbh4 ,rome1 formations at1 #afh4 ,roemer1 ,f41 on chalk in ,texas1 #bbe4 ,m4 ,f4 ,a41 on flora of ,hartz1 #cej4 ,rose1 ,prof4 ,g41 cited1 #cgd4 #dcd4 on hornblende1 #cfi4 ,rosenlaui1 limestone scratched by glacier of1 #abb4 ,ross1 ,captain1 on greenstone in ,keeling ,island1 #bag4 ,ross-shire1 denudation in1 #fg4 ,rothliegendes1 lower1 or ,permian1 #cjf4 ,rozet1 ,m41 cited1 #aia4 ,rubble1 term explained1 #ha4 ,russia1 erratic blocks in1 #abd4 fossil meteoric iron in1 #ade4 ,permian rocks in1 #cjf4 ,s4 ,saarbrueck coal field1 reptile found in1 #ccf4 ,st4 ,abb's ,head1 curved strata near1 #di4 ,st4 ,andrews1 trap rocks in cliffs near1 #dcb4 #dcc4 ,st4 ,helena1 basalt in1 #che4 #djf4 ,st4 ,lawrence1 gulf of1 inland beaches and cliffs1 #gh4 ,st4 ,mihiel1 inland cliffs near1 #gg4 ,st4 ,paul1 island of1 #cid4 ,st4 ,peter's ,mount1 ,maestricht1 fossils in1 #baj4 sand-pipes in1 #hc4 ,salisbury ,crag1 altered strata of1 #chc4 ,salt rock1 origin of1 #bid4 precipitation of1 #bid4 at ,northwich1 #bid4 lakes of ,asia1 #bif4 ,salter1 ,mr41 on fossil of ,caradoc sandstone1 #cef4 ,sand-pipes near ,maestricht1 #hc4 or sand-galls1 term explained1 #hb4 near ,norwich1 #hb4 ,sandstone1 siliceous1 #bah4 with cracks in ,wealden1 #bcj4 ,sandwich ,islands1 coral reef in1 #baf4 volcanos of1 #cid4 #djf4 #dbc4 ,saurians of lias1 #bgh4 thecodont1 #cjf4 ,saussure1 ,m41 on moraines1 #ada4 on vertical conglomerates1 #dg4 ,savi1 ,m41 on ,carrara marble1 #dhb4 ,saxony1 granite in1 #dei4 ,schist1 hornblende1 and mica1 #dfd4 #dfe4 argillaceous1 #dfe4 chlorite1 #dfe4 ,schorl rock and schorly granite1 #ddj4 ,scoresby on icebergs1 #abb4 ,scoriae1 #cgc4 ,scotland1 carboniferous traps of1 #dcb4 northern drift in1 #abe4 old red sandstone of1 #cdc4 ,scrope1 ,mr41 cited1 #aha4 #bfc4 #dai4 #dbc4 #dbe4 #dbg4 #dcj4 on globular structure of traps1 #chg4 on ,ponza ,islands1 #dhj4 on trachyte1 basalt1 and tuff1 #cgd4 #djj4 ,sea cliffs1 inland1 #ga4 ,section of ,wealden1 #bdc4 ,section of white chalk from ,england to ,france1 #baa4 ,section of volcanic rocks1 ,auvergne1 #dbd4 ,sedgwick1 ,prof41 cited1 #cji4 #chc4 on brecciated limestone1 #cjb4 on concretionary magnesian limestone1 #cg4 on ,devonian group1 #cdh4 on garnets in altered rock1 #chb4 on granite1 #def4 #dei4 on ,permian sandstones1 #cje4 on joints and cleavage1 #dfi4 #dga4 on mineral composition of granite1 #ddd4 on old red of ,devon and ,cornwall1 #cde4 on structure of rocks1 #dfh4 on trap rocks of ,cumberland1 #dce4 ,segregation in mineral veins1 #dhi4 ,semi-opal1 infusoria in1 #bf4 ,serpulae1 on volcanic rocks1 in ,sicily1 #aea4 ,sewalik ,hills1 freshwater deposits1 #agc4 ,shale1 carbonaceous1 #bga4 defined1 #aa4 ,shales of coal near ,dudley1 #dgd4 ,sharpe1 ,mr4 ,d41 on mollusca in ,silurian strata1 #cei4 on slaty cleavage1 #dga4 ,shells1 fossil1 in ,purbeck1 #bca4 fossil1 useful in classification1 #aji4 in ,canada drift1 #acd4 recent1 in valley of ,niagara1 #ach4 species of1 near ,lisbon1 #aga4 ,sheppey1 ,isle of1 fossil flora of1 #bjj4 ,sherringham1 mass of chalk in drift1 #abi4 ,shetland1 granite of1 #dda4 #ddd4 hornblende schist of1 #dgh4 ,shrewsbury1 coal deposit near1 #cbd4 ,sicily1 ,fiume ,salso in1 #aia4 inland cliffs in1 #gd4 newer pliocene strata of1 #aej4 terraces of denudation in1 #ge4 ,sidlaw ,hills1 trap of old red sandstone1 #dcd4 ,siebengebirge1 igneous rocks of1 #dag4 ,sienna1 formations at1 #afg4 ,sigillaria1 #cad4 #cah4 ,siliceous limestone defined1 #ab4 rocks defined1 #aa4 ,silliman1 ,prof41 cited1 #dej4 ,silurian1 name explained1 #cej4 period1 plutonic rocks of1 #deg4 rocks1 table of1 #cea4 strata1 mineral character of1 #cfj4 strata of ,united ,states1 #cei4 strata1 thickness of1 #ceh4 strata1 reptile in1 ,postscript1 vii4 volcanic rocks1 #dcd4 ,simpson1 ,mr41 on ice islands1 #abi4 ,sivatherium described1 #agc4 ,skaptar ,jokul1 eruption of1 #cii4 ,skye1 rocks of1 #chc4 #def4 basaltic columns in1 #che4 dikes in ,isle of1 #chj4 sandstone in1 #cf4 ,slaty cleavage1 #dfh4 ,slickensides1 term defined1 #fa4 ,smith1 ,mr41 of ,jordan ,hill1 on ,pleistocene1 #acd4 on shells near ,lisbon1 #aga4 ,snags1 fossil1 #cbj4 ,snakes' eggs1 fossil at ,tonna near ,gotha1 #abj4 ,solenhofen1 lithographic stone of1 #bfj4 ,solfatara1 decomposition of rocks in the1 #dgg4 ,somma1 #djd4 lava at1 #chj4 ,sopwith1 ,mr4 ,t41 models by1 #eg4 ,sortino1 cave in valley of1 #aed4 ,south ,devon and ,cornwall1 old red of1 #cae4 ,south ,downs1 view of1 #bde4 ,sowerby1 ,mr4 ,g41 cited1 #afb4 ,spatangus1 figure of1 #bc4 ,spezia1 gulf of1 calcareous rocks in1 #dhb4 ,spitzbergen1 glaciers of1 #acf4 ,sponges1 figures of1 in chalk1 #bac4 ,spongilla of ,lamarck1 in tripoli1 #be4 ,springs1 mineral4 ,see ,mineral ,springs1 #dij4 ,staffa1 basaltic columns in1 #che4 ,steno on classification of rocks1 #ij4 ,stigmaria1 #caj4 #cae4 in fossil forest1 ,nova ,scotia1 #cbb4 ,stirling ,castle1 rock of1 altered by dike1 #chc4 ,stokes1 ,mr41 on petrifaction1 #dc4 ,stonesfield slate1 #bff4 ,stonesfield1 fossil mammalia1 #bfh4 and ,postscript1 xviii4 ,storton ,hill1 footprints at1 #bia4 ,strata1 term defined1 #b4 arrangement of1 determined by fossils1 #ba4 #bb4 consolidation of1 #cd4 curved and vertical1 #dg4 #eh4 elevation of1 above the sea1 #dd4 fossiliferous1 tabular view of1 #cfa4 horizontality of1 #ae4 #de4 metamorphic origin of1 #dfg4 mineral composition of1 #aj4 outcrop of1 #ef4 tertiary classification of1 #acd4 ,stratification1 forms of1 #ac4 #af4 #dg4 unconformable1 #ei4 ,strickland1 ,mr41 on new red sandstone1 #bij4 ,strike1 term explained1 #ec4 ,stromboli1 lava of1 #dej4 ,studer1 ,m41 on ,swiss ,alps1 #dhd4 on boulders of ,jura1 #adc4 ,stutchbury1 ,mr41 cited1 #cjf4 ,subapennine strata1 #aje4 #aff4 ,subsidence in drift period1 #ace4 ,suffolk crag1 #afb4 ,sullivan1 ,capt41 chart of ,falkland ,islands1 #hh4 ,superior1 ,lake1 marl in1 #cf4 ,superposition of aqueous deposits1 #if4 of volcanic rocks1 test of age1 #cbg4 ,supracretaceous1 term explained1 #ajc4 ,sussex marble1 #bbh4 ,swansea1 coal measures near1 #cji4 valley stems of ,sigillaria1 #cag4 ,sydney coal field1 ,cape ,breton1 #cbd4 ,syenite1 #ddj4 ,syenitic granite1 #ddj4 greenstone1 #cgb4 ,synclinal line1 term defined1 #dh4 ,t4 ,table ,mountain1 strata horizontal1 #de4 ,mountain1 granite veins in1 #ddc4 ,talcose granite1 #ddj4 ,tartaret1 ,puy de1 cone of1 #dbe4 ,teeth of fossil mammalia1 figures of1 #afj4 ,teredina1 fossil wood bored by1 #bd4 ,teredo navalis boring wood1 #bc4 ,terra del ,fuego1 #aci4 ,fucus giganteus in1 #bag4 ,tertiary1 term explained1 #ajd4 strata1 tabular view of1 #cfb4 ,touraine1 faluns of1 #afh4 ,trachyte1 #cgb4 of ,hungary1 #ddb4 ,trachytic rocks1 older than basalt1 #djj4 ,transition1 term explained1 #ib4 ,trap1 term explained1 #cff4 dike in ,fifeshire1 #dcd4 globular structure of1 #chg4 intrusion of1 between strata1 #chd4 various ages of1 #dcb4 #dcd4 passage of granite into1 #dda4 in ,radnorshire1 #dce4 rocks1 relation to lava1 #chg4 rocks1 lithological character of1 #djj4 in ,lower ,eifel1 #dbj4 ,trappean rocks1 #ia4 ,trap-tuff1 #cgd4 ,tertiary deposits1 #aga4 #agg4 #agh4 ,texas1 chalk in1 #bbe4 ,thames valley1 freshwater deposits in1 #adf4 ,thecodont ,saurians1 #cjf4 ,saurians1 age of1 ,postscript1 xv4 ,thirria1 ,m41 on oolitic group in ,france1 #bhc4 ,thurmann1 ,m41 cited1 #ee4 #beb4 #bff4 ,thuja occidentalis in stomach of mastodon1 #ach4 ,till1 term explained1 #aba4 origin of1 #abc4 ,tilestone1 #cea4 ,tilgate ,forest1 remains in1 #bbi4 ,tin1 veins of1 in ,cornwall1 #dij4 #dih4 ,tiverton trap1 porphyry near1 #dcb4 ,travertin1 how deposited1 #cd4 ,tree ferns in ,permian formation1 #cjg4 ,trias1 or new red sandstone1 #bhf4 #bhi4 and ,postsc41 xiii4 in ,cheshire and ,lancashire1 #bij4 #bie4 ,trilobite in ,devonian strata1 #cdh4 ,trilobites of ,lower ,silurian1 #ceg4 ,trimmer1 ,mr41 on sand-galls1 #hb4 on shells in drift near ,menai ,straits1 #acj4 ,tripoli composed of infusoria1 #bd4 ,tuff1 volcanic1 and trap1 #f4 #cgd4 ,tuffs on ,wrekin and ,caer ,caradoc1 #dcd4 ,tuomey1 ,mr41 cited1 #bjh4 ,turner1 ,dr41 cited1 #da4 #db4 ,tuscany1 volcanic rocks of1 #djh4 ,tynedale fault1 #fd4 ,tynemouth ,cliff1 limestone at1 #cjb4 ,u4 ,uddevalla1 shells of1 compared with those near ,naples1 #ajh4 ,underlying1 term applied to granite1 #h4 ,united ,states1 coal field of1 #cbf4 cretaceous formation in1 #bbd4 ,devonian strata in1 #cdi4 ,eocene strata in1 #bjf4 older ,pliocene and ,miocene formations in1 #aga4 oolite and lias of1 #bhd4 ,silurian strata of1 #cei4 ,upsala1 strata containing ,baltic shells near1 #abd4 ,v4 ,val di ,noto1 composition of1 #djg4 igneous rocks of1 #chi4 inland cliffs in1 #gf4 ,valleys1 origin of1 #gj4 transverse of ,weald1 #bdd4 ,valorsine granite1 #dde4 ,veins1 mineral4 ,see ,mineral ,veins1 #dhh4 ,veinstones in parallel layers1 #dic4 ,velay1 volcanos of1 #dbh4 ,venetz1 ,m41 on ,alpine glaciers1 #adj4 ,verneuil1 ,m4 de1 on ,devonian ,flora1 #cej4 on horizontal strata in ,russia1 #abd4 on the old red sandstone in ,russia1 #cdh4 on ,pentamerus ,knightii1 #cec4 on ,permian flora1 #cje4 ,vesuvius1 eruption of1 #dje4 ,vicenza1 basaltic columns near1 #chf4 ,vidal1 ,capt41 survey by1 #cic4 ,virginia1 ,u4 ,s41 fossil shells in1 #agb4 ,virlet1 ,m41 on corrosion of rocks by gases1 #dgg4 on geology of ,morea1 #dca4 on inland cliffs1 #gc4 ,volcanic mountains1 form of1 #e4 #cij4 dikes1 #cgh4 ,volcanic rocks1 age of1 #cig4 described1 #e4 #che4 analysis of minerals in1 #cgg4 ,cambrian1 #dce4 composition and nomenclature1 #cfh4 of ,hungary1 #dba4 post-pliocene period1 #dja4 test of age of1 #djj4 ,silurian1 #dcd4 ,volcanic tuff1 #cgd4 ,volcanos of ,auvergne1 #dbb4 extinct1 #djh4 #dbj4 #dbb4 newer1 of ,eifel1 #dah4 in ,spain1 age of1 #dad4 round ,olot in ,catalonia1 #daj4 ,von ,buch1 ,baron1 cited1 #cgc4 #def4 #deg4 on boulders of ,jura1 #adc4 on ,canary ,islands1 #cib4 on ,cystideae1 #ceh4 on land rising1 #de4 ,von ,dechen1 ,m41 on granite veins in ,cornwall1 #dde4 ,oeynhausen1 ,m41 cited1 #dae4 ,w4 ,waller quoted1 #ic4 ,warren1 ,dr4 ,j4 ,c41 on skeleton of ,mastodon giganteus1 #ach4 ,waterhouse1 ,mr41 cited1 #ahh4 #bfi4 on triassic mammifer1 ,postscript1 xiv4 ,watt1 ,mr4 ,g41 experiments on fused rocks1 #djf4 #dge4 ,weald clay1 #bbg4 ,weald valley1 denuded at what period1 #bed4 ,wealden1 term explained1 #bbe4 #bbf4 the fracture and upheaval of1 #bea4 extent of formation1 #bcf4 period1 changes during1 #bce4 ,wealden1 plants and animals of1 #bbi4 #bcf4 ,webster1 ,mr4 ,t41 cited1 #aje4 #bca4 #bcc4 ,wellington ,valley1 caves in1 #aef4 ,wener ,lake1 horizontal ,silurian strata of1 #de4 ,wenlock formation1 #ced4 ,werner on classification of rocks1 #ij4 on mineral veins1 #dhh4 on volcanic rocks1 #cfi4 ,westerwald1 igneous rocks of1 #dag4 ,westwood1 ,mr41 on beetles in lias1 #bhb4 ,whin-,sill1 intrusion of trap between strata1 #chd4 ,white chalk1 #baa4 ,white mountains1 granite vein in1 #dej4 ,wigham1 ,mr41 on fossils near ,norwich1 #adi4 ,wolverhampton1 fossil forest near1 #cai4 ,wood1 ,mr4 ,searles1 on fossils of crag1 #afb4 on fossils of ,isle of ,wight1 #aih4 on number of shells in crag1 #adi4 on cetacea of crag1 #aff4 cited1 #agj4 #agg4 ,woodward1 ,mr41 on mammoth bones1 ,norfolk1 #adg4 ,wrekin1 trap of1 #gj4 ,wyman1 ,dr41 cited1 #bjh4 ,z4 ,zamia1 at ,lyme ,regis1 #bhb4 ,zamia spiralis1 figure of1 #bcc4 ,zechstein1 #cjf4 ,zeuglodon cetoides1 #bjg4 and ,postscript1 xxi4 ,,london3 ,,spottiswoodes and ,,shaw1 ,new-street-,square4 ,,albemarle ,,street1 ,july #e1 #ahea4 ,,mr4 ,,murray',s ,list of ,recent ,works 99 99 99 99 99 ,,history ,,of ,,the ,,roman ,,state2 ,,from #ahae-ahej4 ,,by ,,lugia ,,carlo ,,farini4 ,,translated ,,from ,,the ,,italian ,,by ,,the ,,right ,,hon4 ,w4 ,e4 ,,gladstone1 ,m4,p4 #b ,vols4 #hvo4 #bds4 99 99 99 99 99 ,,the ,,exposition ,,of #ahea2 ,,or1 ,,views ,,of ,,the ,,industry1 ,,the ,,science1 ,,and ,,the ,,government ,,of ,,england4 ,,by ,,charles ,,babbage1 ,,esq41 ,author of the ,economy of ,manufactures and ,machinery4 ,second ,edition1 with an ,appendix4 #hvo4 #fs4 #f;d4 99 99 99 99 99 ,,the ,,dovecote ,,and ,,the ,,aviary2 ,,or1 ,,the ,,natural ,,history ,,of ,,pigeons ,,and ,,other ,,domestic ,,birds1 ,,with ,,hints ,,for ,,their ,,management4 ,,by ,,the ,,rev4 ,,edmund ,,saul ,,dixon1 ,m4,a41 ,author of ,ornamental and ,domestic ,poultry4 ,with ,numerous ,woodcuts4 ,fcap4 #hvo4 #gs4 #f;d4 99 99 99 99 99 ,,memoir ,,of ,,the ,,life ,,of ,,the ,,late ,,bishop ,,stanley4 ,,prefixed ,,to ,a ,,selection ,,from ,,his ,,addresses ,,and ,,charges4 ,,by ,,the ,,rev4 ,,arthur ,,penrhyn ,,stanley1 ,m4,a4 #hvo4 #ajs4 #f;d4 ,the memoir is executed with feeling1 and1 as might be expected from the biographer of ,dr4 ,arnold1 with great skill4 ,mr4 ,stanley brings out into strong relief the more attractive parts of his father's character1 and suggests the best defence--namely1 the consistent uprightness and perfect sincerity of his motives--for the more questionable policy1 on some memorable occasions1 of the bishop4 ,morning ,chronicle4 99 99 99 99 99 ,a ,,pastoral ,,letter ,,on ,,the ,,state ,,of ,,the ,,church1 ,,by ,,henry ,,lord ,,bishop ,,of ,,exeter4 ,eighth ,edition4 #hvo4 #ds4 99 99 99 99 99 ,,the ,,acts ,,of ,,the ,,synod ,,of ,,exeter4 ,,holden ,,in ,,the ,,chapter ,,house ,,of ,,the ,,cathedral ,,church ,,of ,,exeter4 ,,on ,,june #be1 #bf1 and #bg1 #ahea4 #hvo4 33 ,the ,sermon may be had separately1 price #as4 99 99 99 99 99 ,,the ,,evangelical ,,and ,,tractarian ,,movements4 ,,by ,,archdeacon ,,wilberforce4 7,a ,charge delivered to and published by ,request of the ,clergy47 #hvo4 #as4 99 99 99 99 99 ,a ,,history ,,of ,,erastianism4 ,,by ,,archdeacon ,,wilberforce4 #afmo4 #cs4 99 99 99 99 99 ,,catholic ,,safeguards ,,against ,,the ,,errors1 ,,corruptions1 ,,and ,,novelties ,,of ,,the ,,church ,,of ,,rome4 ,,being ,,discourses ,,and ,,tracts ,,selected ,,from ,,the ,,works ,,of ,,eminent ,,divines ,,of ,,the ,,church ,,of ,,england ,,who ,,lived ,,during ,,the #ag,,th ,,century2 ,,with ,,preface1 ,,records1 ,,and ,a ,,carefully ,,compiled ,,index4 ,,by ,,rev4 ,,james ,,brogden1 ,m4,a4 #c ,vols4 #hvo4 #cfs4 99 99 99 99 99 ,,records ,,of ,,the ,,supremacy ,,of ,,the ,,crown1 ,,and ,,the ,,civil ,,and ,,religious ,,liberties ,,of ,,the ,,people ,,of ,,england4 ,,by ,,rev4 ,,james ,,brogden4 #hvo4 #ds4 99 99 99 99 99 ,,horae ,,aegyptiacae2 ,,or1 ,,the ,,chronology ,,of ,,ancient ,,egypt4 ,,discovered ,,from ,,astronomical ,,and ,,hieroglyphic ,,records ,,upon ,,its ,,monuments ,,including ,,many ,,dates ,,found ,,in ,,coeval ,,inscriptions4 ,,by ,,reginald ,,stuart ,,poole1 ,,esq4 ,with ,plates4 #hvo4 #ajs4 #f;d4 ,the substance of ,mr4 ,poole's valuable work appeared originally in a series of papers in this journal4 ,since their publication the author has devoted further time and attention to the subject2 and it may safely be asserted that in their present amended and enlarged form1 they are among the most important contributions that have yet been made to the study of ,egyptian ,chronology and history4 ,we are indebted for the publication of the present valuable work to the liberality of the ,duke of ,northumberland1 whose warm and generous support of literature and art deserves our grateful acknowledgments4 ,literary ,gazette4 99 99 99 99 99 ,,lavengro2 ,,the ,,scholar--,,the ,,gipsy--,,and ,,the ,,priest4 ,,by ,,george ,,borrow1 ,,esq4 ,author of ,the ,bible in ,spain1 ,the ,gipsies of ,spain1 c4 c4 ,with a ,portrait4 #c ,vols4 ,post #hvo4 #cjs4 ,we trust our extracts have exhibited enough of one at least of the many aspects of ',lavengro' to convince the reader that neither is it a work to be read cursorily1 nor to be handled easily1 by any of the silver-fork school of critics4 ,these volumes are indeed replete with life1 with earnest sympathy for all genuine workers1 with profound insight into the wants and wishes of the poor and uneducated1 and a lofty disdain of the conventional 'shams' and pretensions which fetter the spirits or impede the energies of mankind4 ,nor is a feeling for the beautiful less conspicuous in its pages4 ,a quiet market-town1 environed by green meadows or bosomed in tufted trees2 an old mercantile and ecclesiastical city1 with a history stretching from the times of the ,caesars to the times of ,george ,,iii42 the treeless plain1 the broad river1 the holt1 the dingle1 the blacksmith's forge1 are all in their turn sketched freely and vividly by ,mr4 ,borrow's pencil4 ,in his portraitures of ruder life he is unsurpassed2 a dog-fight1 a prize-fight1 an ale-house kitchen1 ,greenwich ,fair1 a savage group of wandering tinkers1 are delineated in words as ,wilkie or ,hogarth might have depicted them in colours4 ,we are embarrassed by the riches spread before us4 ,we have not touched upon the gipsy scenes in ',lavengro' because in any work of ,mr4 ,borrow's these will naturally be the first to draw the reader's attention4 ,neither have we aimed at abridging or forestalling any portions of a book which has a panoramic unity of its own1 and of which scarcely a page is without its proper interest4 ,if we have succeeded in persuading our readers to regard ,mr4 ,borrow as partly an historian and partly as a poet1 as well as to look for more in his volumes than mere excitement or amusement1 our purpose is attained1 and we may securely commend him to the goodly company he will find therein4 ',lavengro1' however1 is not concluded2 a fourth volume will explain and gather up much of what is now somewhat obscure and fragmentary1 and impart a more definite character to the philological and physiological hints comprised in those now before us4 ,enough1 indeed1 and more than enough1 is written to prove that the author possesses1 in no ordinary measure1 'the vision and the faculty divine' for discerning and discriminating what is noble in man and what is beautiful in nature4 ,we trust ,mr4 ,borrow will speedily bring forth the remaining acts of his 'dream of adventure1' and with good heart and hope pursue his way rejoicing1 regardless of the misconceptions or misrepresentations of critics who judge through a mist of conventionalities1 and who themselves1 whether travelled or untravelled1 have not1 like ,lavengro1 grappled with the deeper thoughts and veracities of human life4--,tait's ,magazine4 99 99 99 99 99 ,,england ,,in ,,the ,,nineteenth ,,century3 ,,political1 ,,social1 ,,and ,,industrial4 ,,by ,,william ,,johnston1 ,,esq4 #b ,vols4 ,post #hvo4 #ahs4 ,this book is a somewhat undigested mass of valuable matter1 interspersed occasionally with reflections of much interest and observations of considerable originality4 ,the author is unquestionably a man of talent2 he writes with vigour and smartness2 he has taken pains in the collection of most of his materials2 and his statistics are arranged with great care and managed with unusual skill4 ,in this point he is much superior to his prototype and apparent master1 ,mr4 ,alison4 ,mr4 ,johnston's work is readable and well-written1 abounding with information of many kinds4--,edinburgh ,review4 99 99 99 99 99 ,,the ,,saxon ,,in ,,ireland3 ,,being ,,notes ,,of ,,the ,,rambles ,,of ,,an ,,englishman ,,in ,,the ,,west ,,of ,,ireland ,,in ,,search ,,of ,a ,,settlement4 ,with ,map4 ,post #hvo4 #is4 #f;d4 ,a valuable testimony to the capabilities of ,ireland4--,observer4 ,let the intending emigrant devote a few hours to the perusal of this volume4 ,the work possesses deeper interest than even could be claimed for it from its fascinating descriptions4--,illustrated ,news4 99 99 99 99 99 ,,sleep ,,and ,,dreams3 ,,two ,,lectures ,,delivered ,,at ,,the ,,bristol ,,literary ,,and ,,philosophical ,,institution4 ,,by ,,john ,,addington ,,symonds1 ,m4,d41 ,consulting ,physician to the ,bristol ,general ,hospital4 #hvo4 #bs4 #f;d4 99 99 99 99 99 ,,the ,,palaces ,,of ,,nineveh ,,and ,,persepolis ,,restored4 ,,an ,,essay ,,on ,,ancient ,,assyrian ,,and ,,persian ,,architecture4 ,,by ,,james ,,fergusson ,,esq41 ,with ,woodcuts4 #hvo4 #afs4 ,this book contains many things of general interest relating to one of the most wonderful discoveries that has occurred in the history of the world4 ,mr4 ,fergusson writes very dispassionately4 ,what he has said deserves serious consideration4--,gentleman's ,magazine4 99 99 99 99 99 ,,shall ,,we ,,keep ,,the ,,crystal ,,palace ,,and ,,have ,,riding ,,and ,,walking ,,in ,,all ,,weathers1 ,,among ,,flowers1 ,,sculpture1 ,,and ,,fountains8 ,,by ,,denarius4 #hvo4 #f;d4 99 99 99 99 99 ,,memoirs ,,of ,,robert ,,plumer ,,ward4 ,,with ,,his ,,correspondence1 ,,diaries1 ,,and ,,literary ,,remains4 ,,by ,,the ,,hon4 ,,edmund ,,phipps4 ,with ,portrait4 #b ,vols4 #hvo4 #bhs4 ,the most valuable portions of ,mr4 ,ward's diary are its illustrations of the character of the ,duke of ,wellington4 ,the great soldier1 then in the flush of his military triumph1 was also in the prime of his power and activity2 and ,mr4 ,ward gives us an insight into his business habits1 his method of arguing public questions1 his ready resource and never-tiring energy1 which possesses occasionally a striking interest4--,examiner4 99 99 99 99 99 ,,the ,,military ,,events ,,in ,,italy1 #ahdh-i4 ,,translated ,,from ,,the ,,german4 ,,by ,,the ,,right ,,hon4 ,,the ,,earl ,,of ,,ellesmere4 ,with a ,map4 ,post #hvo4 #is4 ,military history is1 as the ,earl of ,ellesmere declares1 a rare article in ,english literature2 and1 therefore1 he thought that the most authentic extant narrative of the operations implied in the title page of the present book1 written by an impartial ,swiss1 would not be an unwelcome addition to the ,british library4 ,his lordship has judged rightly2 the work of which he has presented a version is a worthy labour1 and the events to which it relates are of the last importance4 ,it is written with judgment1 and has been translated with care4--,morning ,chronicle4 99 99 99 99 99 ,a ,,transport ,,voyage ,,to ,,the ,,mauritius1 ,,by ,,way ,,of ,,the ,,cape ,,of ,,good ,,hope ,,and ,,st4 ,,helena4 ,,by ,,the ,,author ,,of ,,paddiana4 ,post #hvo4 #is4 #f;d4 ,this book reminds us of one of those pleasant fellows1 whom one sometimes meets with in company1 who has an anecdote or a story ready a propos of everything1 whose fund of amusing tales is inexhaustible1 and who rattling on from one thing to another1 will keep a whole table in a roar1 or a whole drawing-room in high glee4 ,even such is our author4 ,he gossips on and on1 telling now of one adventure1 and then of another2 his volume is a perfect chaos of racy reminiscences graphically told4--,john ,bull4 99 99 99 99 99 ,,admiralty ,,manual ,,of ,,scientific ,,enquiry ,,for ,,the ,,use ,,of ,,officers ,,and ,,travellers ,,in ,,general4 ,,by ,,professors ,,whewell1 ,,airy1 ,,owen1 ,,sir ,w4 ,,hooker1 ,,capt4 ,,beechey1 ,j4 ,r4 ,,hamilton1 ,,esq41 ,,sir ,,john ,,herschel1 c4 ,,edited ,,by ,,sir ,,john ,f4 ,,herschel1 ,,bart4 ,second ,edition4 ,post #hvo4 #ajs4 #f;d4 33 ,published by ,authority of the ,lords ,commissioners of the ,admiralty4 99 99 99 99 99 ,,lives ,,of ,,the ,,chief ,,justices ,,of ,,england4 ,,from ,,the ,,norman ,,conquest ,,to ,,the ,,death ,,of ,,lord ,,mansfield4 ,,by ,,lord ,,chief ,,justice ,,campbell4 #b ,vols4 #hvo4 #cjs4 ,there is1 indeed1 in ,lord ,campbell's works much instruction2 his subjects have been so happily selected1 that it was scarcely possible that there should not be4 ,an eminent lawyer and statesman could not write the lives of great statesmen and lawyers without interweaving curious information1 and suggesting valuable principles of judgment and useful practical maxims3 but it is not for these that his works will be read4 ,their principal merit is their easy animated flow of interesting narrative4 ,no one possesses better than ,lord ,campbell the art of telling a story3 of passing over what is commonplace2 of merely suggesting what may be inferred2 of explaining what is obscure2 and of placing in strong light the details of what is interesting4--,edinburgh ,review4 99 99 99 99 99 ,,the ,,forty-,,five4 ,,being ,a ,,narrative ,,of ,,the ,,rebellion ,,in ,,scotland ,,of #agde2 ,,by ,,lord ,,mahon4 ,post #hvo4 #cs4 ,this is a very comprehensive and lively sketch of the famous ',rebellion' so vividly remembered1 even after the lapse of a century1 by the people of ,scotland4 ,the incidents of that unfortunate invasion from first to last1 from the landing of ,charles 7,july #beth7 in ,borrodale1 with the 'seven men of ,moidart1' to the fatal battle of ,culloden 7#afth ,april1 #agdf71 are minutely and faithfully recorded2 but we have no doubt the reader will be most and mainly interested in the personal history and adventures of the ,pretender himself4 ,the character of the ,prince is admirably drawn1 and generously vindicated from the calumnies heaped upon him by his adversaries after his fall4 ,it will perhaps surprise some to learn1 that he was so illiterate as scarcely to be master of the most common elements of education4 ',his letters1' says ,lord ,mahon1 'which ,i have seen among the ,stuart papers1 are written in a large1 rude1 rambling hand1 like a schoolboy's4 ,in spelling they are still more deficient4' ,we recommend ,lord ,mahon's narrative as a very agreeable sketch of a stirring and eventful period4--,edinburgh ,advertiser4 99 99 99 99 99 ,a ,,history ,,of ,,greece4 ,,from ,,the ,,earliest ,,period ,,to ,,the ,,end ,,of ,,the ,,peloponnesian ,,war4 ,,by ,,george ,,grote1 ,,esq4 ,vols4 ,i4-,,viii4 ,with ,maps4 #hvo4 #afs4 each4 ,the ,work may be obtained in ,portions1 as it was published3-- ,,vols4 ,i4-,,ii4 ,,legendary ,,greece4 ,,grecian ,,history ,,to ,,the ,,reign ,,of ,,peisistratus ,,at ,,athens4 ,,vols4 ,,iii4-,,iv4 ,,history ,,of ,,early ,,athens1 ,,and ,,the ,,legislation ,,of ,,solon4 ,,grecian ,,colonies4 ,,view ,,of ,,the ,,contemporary ,,nations ,,surrounding ,,greece4 ,,grecian ,,history ,,down ,,to ,,the ,,first ,,persian ,,invasion1 ,,and ,,the ,,battle ,,of ,,marathon4 ,,vols4 ,v4-,,vi4 ,,persian ,,war ,,and ,,invasion ,,of ,,greece ,,by ,,xerxes4 ,,period ,,between ,,the ,,persian ,,and ,,the ,,peloponnesian ,,wars4 ,,peloponnesian ,,war ,,down ,,to ,,the ,,expedition ,,of ,,the ,,athenians ,,against ,,syracuse4 ,,vols4 ,,vii4-,,viii4 ,,the ,,peace ,,of ,,nikias ,,down ,,to ,,the ,,battle ,,of ,,knidus ,b4,c4 #dba ,,to #cid4 ,,socrates ,,and ,,the ,,sophists4 99 99 99 99 99 ,,kugler',s ,,handbook ,,illustrated4 ,,the ,,schools ,,of ,,painting ,,in ,,italy4 ,,from ,,the ,,earliest ,,times4 ,,translated ,,from ,,the ,,german ,,by ,a ,,lady1 ,,and ,,edited ,,with ,,notes ,,by ,,sir ,,charles ,,lock ,,eastlake1 ,president of the ,royal ,academy4 ,a ,new ,edition4 #b ,vols4 ,post #hvo4 #bds4 ,we cannot leave this subject 7,christian ,art1 its present state and its prospects71 without reverting to ,sir ,c4 ,eastlake's edition of ,kugler's ,handbook of ,painting1 not for the sake of reviewing it1--for it is a work now of established reputation1--but for the purpose of recommending it as being upon the whole by far the best manual we are acquainted with1 for every one who1 without the opportunity of foreign and particularly ,italian travel1 desires to make a real study of art4 ,its method1 its chronological arrangement1 and its generally judicious criticism1 make it most instructive to a learner4 ,we may add that the present edition is enlarged just where the former one needed enlargement1 and the ,handbook is now far more satisfactory as to the early religious schools than it was before4 ,the edition is beautifully got up1 and so profusely and judiciously illustrated by one hundred woodcuts drawn by ,scharf1 that it would be next to impossible to speak too highly in its praise1 even were its matter less valuable and important than it is4--,the ,ecclesiastic4 99 99 99 99 99 ,,christianity ,,in ,,ceylon3 ,,its ,,introduction ,,and ,,progress ,,under ,,the ,,portuguese1 ,,dutch1 ,,british1 ,,and ,,american ,,missions4 ,,by ,,sir ,,james ,,emerson ,,tennent1 ,k4,c4,s41 ,,ll4,d4 ,with ,illustrations4 #hvo4 #ads4 ,to those who take either a religious or a philosophical interest in the subject1 ,sir ,emerson ,tennent's volume may be safely recommended1 as a clear1 succinct1 sensible1 and flowing account4 ,the work also possesses a living animation arising from the author's knowledge of the country and the people4--,spectator4 99 99 99 99 99 ,,the ,,lexington ,,papers4 ,,the ,,courts ,,of ,,london ,,and ,,vienna ,,in ,,the #ag,,th ,,century4 ,,extracted ,,from ,,the ,,private ,,and ,,official ,,correspondence ,,of ,,lord ,,lexington1 ,,while ,,british ,,minister ,,at ,,vienna1 #afid-ih4 ,,edited ,,by ,,the ,,hon4 ,h4 ,,manners ,,sutton4 #hvo4 #ads4 99 99 99 99 99 ,,the ,,law ,,and ,,practice ,,of ,,naval ,,courts-,,martial4 ,,by ,,william ,,hickman1 ,r4,n41 ,late ,secretary to ,commodore ,sir ,charles ,hotham1 ,k4,c4,b4 #hvo4 #ajs4 #f;d4 99 99 99 99 99 ,a ,,manual ,,of ,,elementary ,,geology2 ,,or1 ,,the ,,ancient ,,changes ,,of ,,the ,,earth ,,and ,,its ,,inhabitants1 ,,as ,,illustrated ,,by ,,its ,,geological ,,monuments4 ,,by ,,sir ,,charles ,,lyell1 ,f4,r4,s41 ,p4,g4,s4 ,third ,edition1 thoroughly revised1 and illustrated with #ebj ,woodcuts4 #hvo4 #abs4 ,the production of one of our most eminent geologists in an age of many4 ,though styled a 'third edition1' it is in reality a new book4 ,this could not be otherwise if the task were well done2 for the science of which ,sir ,charles ,lyell treats is assuming new aspects every year4 ,it is continually advancing and ever growing4 ,as it advances1 its steps become firmer and surer2 as it grows1 its framework becomes more compact1 and its organization more perfect4 ,they who take up the hammer to follow it must toil with unflagging tread to keep pace with its onward progress4 ,if they lag behind1 they can scarcely hope to overtake4 ,none among its votaries has marked each movement more minutely1 or weighed its value and purpose more judiciously1 than the distinguished author of this ,manual4 ,he has indeed done his task well1 and both the beginner and the experienced investigator will find his book an invaluable guide and companion4--,literary ,gazette4 99 99 99 99 99 ,,commentaries ,,on ,,the ,,war ,,in ,,russia ,,and ,,germany ,,of #ahac-ad4 ,,by ,,colonel ,,the ,,hon4 ,,george ,,cathcart1 ,deputy-,lieutenant of the ,tower of ,london4 ,with ,plans4 #hvo4 #ads4 ,as a ,treatise on the ,science of ,war1 these ,commentaries ought to find their way into the hands of every soldier4 ,in them is to be found an accurate record of events of which no military man should be ignorant4--,morning ,chronicle4 99 99 99 99 99 ,,modern ,,domestic ,,cookery4 ,,founded ,,upon ,,principles ,,of ,,economy ,,and ,,practical ,,knowledge4 ,,and ,,adapted ,,for ,,the ,,use ,,of ,,private ,,families4 ,with #ajj ,woodcuts4 ,post #hvo4 #fs4 ,the advanced state of cookery having rendered ,mrs4 ,rundell's work obsolete1 the publisher has caused it to be remodelled and improved to such an extent as to give it a claim to the title of an original production4 ,the receipts of the late ,miss ,emma ,roberts have been revised and added to the work2 and it has had the advantage of being subjected besides to the careful inspection of a 'professional gentleman'--,economy combined with excellence--is the aim1 end1 and object which it cannot be doubted will be obtained if its prescriptions are attended to4 ,it is fuller than the former ,domestic ,cookery1 of which it is an improved and amended edition--it is more simple and comprehensible in its language2 it contains several diagrams not to be found in its predecessor2 and it possesses various minor qualities1 which increase its value in a tenfold degree1 and make it1 to say the least1 equal to any other book of the kind in the ,english language4--,observer4 ,,albemarle ,,street1 ,july #e1 #ahea4 ,,mr4 ,,murray',s ,list of ,works in the ,press4 99 99 99 99 99 ,selections from the ,despatches of the ,duke of ,wellington4 ,,by ,,the ,,late ,,col4 ,,gurwood1 ,c4,b41 ,k4,c4,t4,s4 ,a ,new ,edition4 ,one ,volume4 #hvo4 99 99 99 99 99 ,history of ,england1 from the ,peace of ,utrecht4 ,,vols4 #e #f--,,the ,,first ,,years ,,of ,,the ,,american ,,war3 #agfc--aghj4 ,,by ,,lord ,,mahon1 ,m4,p4 #b ,vols4 #hvo4 99 99 99 99 99 ,lives of the ,friends and ,contemporaries of ,lord ,chancellor ,clarendon4 ,,illustrative ,,of ,,portraits ,,in ,,his ,,gallery2 ,,with ,,an ,,account ,,of ,,the ,,origin ,,of ,,the ,,collection2 ,,and ,a ,,descriptive ,,catalogue ,,of ,,the ,,pictures4 ,,by ,,lady ,,theresa ,,lewis4 ,with ,portraits4 #b ,vols4 #hvo4 99 99 99 99 99 ,the ,treasures of ,art in ,great ,britain4 ,,being ,,an ,,account ,,of ,,the ,,chief ,,collections ,,of ,,paintings1 ,,sculpture1 ,,mss4 ,,miniatures1 c41 c41 ,,obtained ,,from ,,personal ,,inspection ,,during ,,visits ,,in #ahcf ,,and #ahej4 7,,being ,a ,,revised ,,and ,,greatly ,,enlarged ,,version ,,of ,,art ,,and ,,artists ,,in ,,england47 ,,by ,,dr4 ,,waagen1 ,director of the ,royal ,gallery of ,pictures at ,berlin4 #b ,vols4 #hvo4 99 99 99 99 99 ,the ,grenville ,papers2 ,,being ,,the ,,private ,,correspondence ,,of ,,richard ,,grenville1 ,,earl ,,temple1 ,k4,g41 ,,and ,,his ,,brother1 ,,the ,,right ,,honourable ,,george ,,grenville1 ,,their ,,friends ,,and ,,contemporaries1 ,,formerly ,,preserved ,,at ,,stowe--,,now ,,for ,,the ,,first ,,time ,,made ,,public4 ,among the contents of this highly important accession to the ,history of ,great ,britain in the middle of the ,eighteenth ,century1 will be found ,letters from ,h4 ,m4 ,,king ,,george ,,the ,,third4 ,h4 ,r4 ,h4 ,,william ,,duke ,,of ,,cumberland4 ,,dukes ,,of3-- ,,newcastle4 ,,devonshire4 ,,grafton4 ,,bedford4 ,,marquess3-- ,,granby4 ,,earls3-- ,,bute4 ,,temple4 ,,sandwich4 ,,egremont4 ,,halifax4 ,,hardwicke4 ,,chatham4 ,,mansfield4 ,,northington4 ,,suffolk4 ,,hillsborough4 ,,hertford4 ,,lords3-- ,,lyttleton4 ,,camden4 ,,holland4 ,,clive4 ,,george ,,sackville4 ---- ,,marshal ,,conway4 ,,horace ,,walpole 7,,earl ,,of ,,orford74 ,,edmund ,,burke4 ,,george ,,grenville4 ,,john ,,wilkes4 ,,william ,,gerard ,,hamilton4 ,,augustus ,,hervey4 ,,mr4 ,,jenkinson 7first ,,earl ,,of ,,liverpool74 ,,mr4 ,,whately4 ,,mr4 ,,wedderburn 7,,earl ,,of ,,roslyn74 ,,mr4 ,,charles ,,yorke4 ,,mr4 ,,hans ,,stanley4 ,,mr4 ,,charles ,,townsend4 ,,mr4 ,,calcraft4 ,,mr4 ,,rigby4 ,,mr4 ,,knox4 ,,mr4 ,,charles ,,lloyd4 ,,and ,,the ,,author ,,of ,,the ,,letters ,,of ,,junius4 ,,including ,,also1 ,mr4 ,grenville's ,diary of ,political ,events2 ,,particularly ,,during ,,the ,,period ,,of ,,his ,,administration ,,as ,,first ,,lord ,,of ,,the ,,treasury1 ,,from #agfc ,,to #agfe4 ,,edited ,,by ,,william ,,james ,,smith1 ,,esq4 #hvo4 99 99 99 99 99 ,personal ,narrative of an ,englishman ,domesticated in ,abyssinia4 ,,by ,,mansfield ,,parkyns1 ,,esq4 ,with ,illustrations4 #hvo4 99 99 99 99 99 ,lives of the ,three ,devereux1 ,earls of ,essex1 ,,from #aedj ,,to #afdf4 #a4 ,,the ,,earl ,,marshall ,,of ,,ireland4--#b4 ,,the ,,favourite4--#c4 ,,the ,,general ,,of ,,the ,,parliament4 ,,founded ,,upon ,,letters ,,and ,,documents ,,chiefly ,,unpublished4 ,,by ,,the ,,hon4 ,,captain ,,devereux1 ,r4,n4 #b ,vols4 #hvo4 99 99 99 99 99 ,the ,present ,state of the ,republic of the ,rio de la ,plata 7,buenos ,ayres74 ,,its ,,geography1 ,,resources1 ,,statistics1 ,,commerce1 ,,debt1 ,,etc41 ,,described4 ,,with ,,the ,,history ,,of ,,the ,,conquest ,,of ,,the ,,country ,,by ,,the ,,spaniards4 ,,by ,,sir ,,woodbine ,,parish1 ,f4,r4,s41 ,k4,c4,h1 ,f4,g4,s41 ,formerly ,her ,majesty's ,consul ,general and ,charge d' ,affaires at ,buenos ,ayres4 ,with ,new ,map and ,illustrations4 #hvo4 99 99 99 99 99 ,contrasts of ,foreign and ,english ,society2 ,,or1 ,,records ,,and ,,recollections ,,of ,a ,,residence ,,in ,,various ,,parts ,,of ,,the ,,continent ,,and ,,england4 ,,by ,,mrs4 ,,austin4 #b ,vols4 ,post #hvo4 99 99 99 99 99 ,the ,hand2 ,,its ,,mechanism ,,and ,,endowments1 ,,as ,,evincing ,,design4 ,,by ,,the ,,late ,,sir ,,charles ,,bell4 ,a ,new ,edition4 ,woodcuts4 ,post #hvo4 99 99 99 99 99 ,naval and ,military ,technological ,dictionary4 ,,english ,,and ,,french4--,,french ,,and ,,english4 ,,for ,,the ,,use ,,of ,,soldiers1 ,,sailors1 ,,and ,,engineers4 ,,by ,,colonel ,,burn1 ,assistant ,inspector of ,artillery4 ,small #hvo4 99 99 99 99 99 ,the ,life and ,reminiscences of ,thomas ,stothard1 ,r4,a4 ,,by ,,mrs4 ,,bray4 ,with numerous ,illustrations from his ,chief ,works1 drawn on ,wood by ,g4 ,,scharf1 ,jun41 and printed in a novel and beautiful style4 ,with a ,portrait4 ,small #dto4 99 99 99 99 99 ,life and ,works of ,alexander ,pope4 ,,edited ,,with ,,notes4 ,,by ,,the ,,right ,,hon4 ,,john ,,wilson ,,croker4 ,portraits4 #d vols4 #hvo4 99 99 99 99 99 ,dictionary of ,greek and ,roman ,geography4 ,,by ,,william ,,smith1 ,,ll4,d4 ,with an ,historical ,atlas4 #hvo4 99 99 99 99 99 ,a ,church ,dictionary4 ,,by ,,walter ,,farquhar ,,hook1 ,d4,d41 ,vicar of ,leeds4 ,sixth ,edition1 revised and enlarged4 ,one ,volume4 #hvo4 ,in this edition1 besides the addition of many new articles1 all those relating to important ,doctrinal and ,liturgical ,subjects have been enlarged4 ,the authorities on which statements have been made1 are given1 with copious extracts from the works of our ,standard ,divines4 ,special reference has been made to the ,romish ,controversy4 ,attention has also been paid to the subjects of ,ecclesiastical and ,civil ,law1 and to the ,statute ,law of ,england in ,church ,matters4--,extract from the ,preface4 99 99 99 99 99 ,history of ,ancient ,pottery2 ,,egyptian1 ,,asiatic1 ,,greek1 ,,roman1 ,,etruscan1 ,,and ,,celtic4 ,,by ,,samuel ,,birch1 ,f4,s4,a4 ,assistant ,keeper of the ,antiquities in the ,british ,museum4 ,with ,illustrations4 #hvo4 ,,uniform ,,with ,,marryat',s ,,modern ,,pottery ,,and ,,porcelain4 99 99 99 99 99 ,a ,sketch of ,madeira in #ahej4 ,,by ,,edward ,,vernon ,,harcourt4 ,a ,,handbook ,,for ,,the ,,use ,,of ,,travellers ,,or ,,invalids ,,visiting ,,the ,,island4 ,with a ,map and ,woodcuts4 ,post #hvo4 99 99 99 99 99 ,the ,history of ,herodotus4 ,a ,,new ,,english ,,version4 ,,translated ,,from ,,the ,,text ,,of ,,gaisford1 ,,and ,,edited ,,by ,,rev4 ,,george ,,rawlinson1 ,m4,a41 ,exeter ,college1 ,oxford4 ,,assisted ,,by ,,colonel ,,rawlinson1 ,c4,b41 ,,and ,,sir ,j4 ,g4 ,,wilkinson1 ,f4,r4,s41 ,,with ,,copious ,,notes ,,and ,,appendices1 ,,illustrating ,,the ,,history ,,and ,,geography ,,of ,,herodotus1 ,,from ,,the ,,most ,,recent ,,sources ,,of ,,information1 ,,embodying ,,the ,,chief ,,results1 ,,historical ,,and ,,ethnographical1 ,,which ,,have ,,been ,,arrived ,,at ,,in ,,the ,,progress ,,of ,,cuneiform ,,and ,,hieroglyphical ,,discovery4 #d ,vols4 #hvo4 ,the translation itself has been undertaken from a conviction of the entire inadequacy of any existing version to the wants of the time4 ,the gross unfaithfulness of ,beloe1 and the extreme unpleasantness of his style1 render his translation completely insufficient in an age which dislikes affectation and requires accuracy2 while the only other complete ,english versions which exist are at once too close to the original to be perused with any pleasure by the general reader1 and also defective in respect of scholarship4 99 99 99 99 99 ,a ,treatise on ,naval ,gunnery1 ,,for ,,the ,,use ,,of ,,officers ,,and ,,for ,,the ,,training ,,of ,,seamen ,,gunners4 ,,with ,,descriptions ,,of ,,the ,,guns ,,introduced ,,since ,,the ,,late ,,war4 ,,by ,,lieut4-,,gen4 ,,sir ,,howard ,,douglas1 ,,bart41 ,g4,c4,b4 ,third ,edition1 revised4 ,plates4 #hvo4 99 99 99 99 99 ,considerations on ,steam ,warfare and ,naval ,shell-,firing2 ,,by ,,lieut4-,,gen4 ,,sir ,,howard ,,douglas1 ,,bart4 #hvo4 99 99 99 99 99 ,letters and ,journals of ,general ,sir ,hudson ,lowe1 ,,revealing ,,the ,,true ,,history ,,of ,,napoleon ,,at ,,st4 ,,helena4 ,,partly ,,compiled ,,and ,,arranged ,,by ,,the ,,late ,,sir ,,nicholas ,,harris ,,nicolas4 ,with ,portrait4 #c ,vols4 #hvo4 ,from these papers the world will at last learn1 as it ought long ago to have learnt1 the truth1 and the whole truth1 respecting the captivity of ,napoleon4--,quarterly ,review4 99 99 99 99 99 ,home ,sermons2 ,,or1 ,,sermons ,,written ,,for ,,sunday ,,reading ,,in ,,families4 ,,by ,,rev4 ,,john ,,penrose1 ,m4,a41 #hvo4 99 99 99 99 99 ,history of ,greece for ,schools4 ,,on ,,the ,,plan ,,of ,,mrs4 ,,markham',s ,,histories4 ,with ,woodcuts4 ,post #hvo4 99 99 99 99 99 ,state ,papers of ,henry the ,eighth's ,reign1 ,,comprising ,,the ,,correspondence ,,between ,,the ,,english ,,government ,,and ,,the ,,continental ,,powers1 ,,from ,,the ,,period ,,of ,,the ,,election ,,of ,,charles ,v4 ,,to ,,the ,,death ,,of ,,henry ,,viii4 ,with ,indexes4 ,vols4 ,,vi-,,xi4 #dto4 99 99 99 99 99 ,the ,official ,handbook4 ,,being ,a ,,manual ,,of ,,historical ,,and ,,political ,,reference ,,for ,,all ,,classes4 ,one ,volume4 ,fcap4 #hvo4 ,the design of this ,work is to show concisely the machinery by which the ,,government of the country is carried on1 giving such a succinct account of the duties1 emoluments1 and authorities of the various ,,public ,,departments1 with their political relations1 as will1 it is hoped1 render the volume a useful manual of reference to all strangers and ,foreigners desirous to make themselves acquainted with ,british ,institutions4 99 99 99 99 99 ,the ,british ,museum2 ,,handbook ,,to ,,the ,,antiquities ,,and ,,sculpture ,,there4 ,,by ,w4 ,s4 ,w4 ,,vaux1 ,m4,a41 ,f4,s4,a41 ,assistant in the ,department of ,antiquities in the ,british ,museum4 ,with ,woodcuts4 ,post #hvo4 99 99 99 99 99 ,handbook of ,chronology4 ,,alphabetically ,,arranged ,,to ,,facilitate ,,reference4 ,one ,volume1 #hvo4 ,this work will enable the student or general reader1 or man of the world1 to put his finger at once upon the date of any particular event by means of a careful alphabetical classified arrangement of the various elaborate chronologies which have been given to the world4 ,it has been prepared with such care as will render it--it is hoped--a trustworthy book of reference4 ,it contains the dates of the events which mark the rise1 progress1 decline1 and fall of states2 and the changes in the fortunes of nations4 ,alliances1 wars1 battles1 sieges1 and treaties of peace2 geographical discoveries1 the settlement of colonies1 and their subsequent story2--with all occurrences of general historic interest--are recorded in it4 ,it further includes the years of the leading incidents in the lives of men eminent for worth1 knowledge1 rank1 or fame2 and of the writings1 c41 c41 by which they are chiefly known2 discoveries in every department of science2 and inventions and improvements1 mechanical1 social1 domestic1 and economical4 99 99 99 99 99 ,handbook for ,syria and the ,holy ,land4 ,with ,maps4 ,post #hvo4 99 99 99 99 99 ,handbook for ,england and ,wales2 ,giving an account of the ,,places and ,,objects best worth visiting in ,england1 more especially those rendered interesting by ,historical ,associations1 or likely to attract the notice of intelligent strangers and passing travellers2 arranged in connexion with the most frequented ,roads and ,railways in ,england4 ,showing1 at the same time1 the way of seeing them to the best advantage1 with the least expenditure of time and money4 ,this work will appear in portions1 as follows3-- ,,part ,i4--,,the ,,eastern ,,counties2 ,,including ,,essex1 ,,suffolk1 ,,norfolk1 ,,cambridge1 ,,and ,,lincoln4 7,nearly ,ready47 ,,part ,,ii4--,,midland ,,counties2 ,,herts1 ,,bedford1 ,,northampton1 ,,leicester1 ,,bucks1 ,,nottinghamshire4 ,,part ,,iii4--,,derbyshire ,,and ,,yorkshire4 ,,part ,,iv4--,,durham1 ,,northumberland1 ,,staffordshire1 ,,cheshire1 ,,lancashire1 ,,cumberland1 ,,the ,,lakes4 ,,part ,v4--,,berks1 ,,bucks1 ,,oxfordshire1 ,,warwick1 ,,gloucester1 ,,worcester1 ,,hereford1 ,,shropshire1 ,,cheshire4 ,,part ,,vi4--,,north ,,and ,,south ,,wales4 ,,part ,,vii4--,,devon ,,and ,,cornwall4 7,ready47 ,,part ,,viii4--,,somerset1 ,,wilts1 ,,dorset4 ,,part ,,ix4--,,hampshire1 ,,isle ,,of ,,wight1 ,,sussex1 ,,surrey1 ,,kent4 ,,also1 ,a ,,condensed ,,handbook ,,of ,,all ,,england ,,in ,,one ,,volume4 ,with ,map and ,plans4 ,post #hvo4 99 99 99 99 99 ,handbook of ,architecture4 ,,being ,a ,,concise ,,and ,,popular ,,account ,,of ,,the ,,different ,,styles ,,prevailing ,,in ,,all ,,ages ,,and ,,countries ,,of ,,the ,,world4 ,,with ,a ,,description ,,of ,,the ,,most ,,remarkable ,,buildings4 ,,by ,,james ,,fergusson1 ,,esq41 ,author of ,indian ,architecture1 ,palaces of ,nineveh and ,persepolis ,restored4 ,with very numerous ,illustrations on ,wood4 #hvo4 ,uniform with ,,kugler',s ,,handbook ,,of ,,painting4 99 99 99 99 99 ,handbook to the ,cathedrals of ,england4 ,,containing ,a ,,short ,,description ,,of ,,each4 ,,by ,,the ,,rev4 ,g4 ,a4 ,,poole1 ,m4,a41 ,vicar of ,welford4 ,with ,illustrative ,woodcuts4 ,small #hvo4 99 99 99 99 99 ,handbook for the ,environs of ,london2 ,,with ,,hints ,,for ,,excursions ,,by ,,rail--,,river--,,and ,,road4 ,,by ,,peter ,,cunningham1 ,f4,s4,a4 ,post #hvo4 99 99 99 99 99 ,handbook of ,modern ,london2 ,,or1 ,,london ,,as ,,it ,,is4 ,,giving ,,full ,,descriptions ,,of ,,all ,,places ,,and ,,objects ,,of ,,interest ,,in ,,the ,,metropolis ,,and ,,its ,,vicinity4 ,with a ,clue-,map of ,london1 ,plans1 c4 #ahmo4 99 99 99 99 99 ,a ,popular ,account of ,nineveh and its ,remains4 ,,by ,,austen ,h4 ,,layard1 ,d4,c4,l4 ,,abridged ,,and ,,condensed ,,from ,,his ,,larger ,,work4 ,with ,numerous ,woodcuts4 ,post #hvo4 99 99 99 99 99 ,,bradbury ,,and ,,evans1 ,,printers1 ,,whitefriars4 ,transcriber's ,notes3 ,passages in italics are indicated by underscore4 ,passages in fracture style are indicated by fracture4 ,all ,greek has been transliterated and placed between ,greek4 ,illustrations have been moved from the middle of a paragraph to the closest paragraph break4 ,in the footnote #ccf-;,a 7page #ccf7 lib4 or liv4 might be printed wrong4 ,on page #ahe a footnote anchor was added to fig4 #afj #ahe-;,a4 ,on page #bae an potential anchor for footnote #bae-;,a was guessed and added4 ,on page #bde an anchor for footnote #bde-;,a was added4 ,on page #bhj a footnote anchor #bhj-;,b was added4 ,other than the corrections listed below1 printer's inconsistencies in spelling1 punctuation1 hyphenation1 and ligature usage have been retained4 ,the use of capital letters in names1 scientific classifications1 locations1 and time periods_/eras is not consistent in this book1 they have been kept as printed and only changed when an obvious error occurred4 ,the system of abbreviations and punctuation in citations and figure captions can vary1 the text has been kept as printed and only changed when an obvious error occurred4 ,the punctuation in the index was inconsistent1 all commas in listings for page numbers have been changed into full stops1 they are not specially mentioned_/marked in the list of changes4 ,the alphabetic order in the index is sometimes inconsistent but has been kept as printed4 ,palaeomaeryx 7page #agh7 is known in the literature by ,paleomeryx 7http3_/_/www4paleodatabase4org7 as well as ,palaeomeryx4 ,palaeoniscus is known in the literature as ,palaeoniscus4 ,inoceramus ,cuvieri is today known as ,inoceramus cuvieri 7ref3 ,cretaceous ,fossils of ,north ,america74 ,different spelling of ,ashby de la ,zouch 7text7 and ,ashby-de-la-,zouch 7index7 was retained4 ,older or unusual forms of spelling of some ,german and ,french towns and locations have been retained 7e4g4 ,bertrich-,baden--,bad ,bertrich1 ,roderberg--,rodderberg1 ,gemunder ,maar--,gemuender ,maar1 ,boulade--,boulaide1 ,pont ,gibaud--,pontgibaud1 ,saarbrueck--,saarbruecken74 ,the following words have been retained in both versions3 ,agas4 and ,agass4 brachiopod1 brachiopods and brachiopoda 7as well as with capital letters or lower case7 ,bunter ,sandstein and ,bunter-,sandstein 7as well as various combinations with ,bunter1 bunter1 sandstein1 ,sandstein7 ,cheirotherium and ,chirotherium as cheirotherian and chirotherian ,didelphis and ,didelphys dike_/s and dyke_/s foot-print_/s and footprint_/s foot-marks and footmarks gault and ,gault ,g_/grauwacke and ,g_/grauwacke and their ,english translations 7greywacke7 greensand and ,greensand as well as their variations ,holoptichius 7e4g4 ,lyell7 and ,holoptychius 7general usage7 ,ichthyolites and ,icthyolites iron-stones and ironstones jaw-bone and jawbone ,keuper and keuper ,lias and lias ,liege and ,liege ,muschelkalk and muschelkalk non-fossiliferous and nonfossiliferous ,old ,red ,sandstone and old red sandstone with all variations ,p_/palaeo9999 and ,p_/paleo9999 with all variations from paleontological to paleozoic ,pozzolana and ,pozzuolana 7recent form7 primaeval and primeval quaquaversal and qua-quaversal ,rhinoceros tichorhinus and ,rhinoceros tichorinus scoria and scoriae ,senonien and ,senonien tilestone_/s and ,t_/tile-stone_/s ,the following misprints have been corrected3 changed to recognise rocks into to recognize rocks page vi changed a fresh-water or into a freshwater or page viii changed belong to gasterodous into belong to gasteropodous page x changed ,ova in a carbonised state4 into ,ova in a carbonized state4 page xi 7fig4 #ebc;a7 changed ,wuertembergisch4 ,naturwissen ,jahreshefte into ,wuertembergisch4 ,naturwissen4 ,jahreshefte footnote xiii-,a changed by ,herman von ,meyer into by ,herman von ,meyer4 page xiv 7fig4 #ecj7 changed near ,stuttgart1 ,wurtemberg4 into near ,stuttgart1 ,wuertemberg4 page xiv changed is characterised by into is characterized by page xvi changed genus ,sauricthys1 ,hybodus1 into genus ,saurichthys1 ,hybodus1 page xv changed ,sauricthys ,mougeotii1 is into ,saurichthys ,mougeotii1 is page xv changed in the ,quader ,sand-stein and into in the ,quadersandstein and page xvi changed of organisation in fossils into of organization in fossils page xix changed or to ,plerodactyles into or to ,pterodactyles page xix changed class ,aves have hither to into class ,aves have hitherto page xix changed bored by teredina into bored by ,teredina page xxiii changed near ,st4 ,andrew's into near ,st4 ,andrews page xxix changed ,sub-marine lava and into ,submarine lava and page xxix changed ,granite of ,dartmore altering into ,granite of ,dartmoor altering page xxx changed ,concluding remarks #dhi into ,concluding remarks #dhh page xxxi changed occasionally characterised by into occasionally characterized by page #c changed are all characterised into are all characterized page #e changed ,loire1 and ,ardeche1 into ,loire1 and ,ardeche1 page #e changed ,giants' ,causeway1 called into ,giant's ,causeway1 called page #f changed cooled and crystallised1 into cooled and crystallized1 page #g changed by ,dr4 ,mac ,culloch into by ,dr4 ,mac,culloch page #h changed afterwards super-imposed1 and into afterwards superimposed1 and page #i changed causes1 while super-imposed into causes1 while superimposed page #i changed 7,green-sand formation47 into 7,greensand formation47 page #af changed annexed fig4 7#g471 into annexed fig4 #g41 page #ah changed 7,green-sand formation87 into 7,greensand formation87 page #ah changed bored by teredina into bored by ,teredina page #ba changed great bed of tripoli1 ,bilin4 into great bed of ,tripoli1 ,bilin4 page #be 7figs4 #ai_/bj7 changed figure number figure #cd into figure #cc page #bi changed information from icthyolites into information from ichthyolites page #cb changed confined to vein-stones4 into confined to veinstones4 page #cd changed the drying and skrinking into the drying and shrinking page #fc changed conglomerate1 ,n4 #b4 clay1 into conglomerate1 ,no4 #b4 clay1 page #fg changed described by ,dr4 ,macculloch1 into described by ,dr4 ,mac,culloch1 page #fg changed of ,ross-shire4 7,macculloch47 into of ,ross-shire4 7,mac,culloch47 page #fg 7fig4 #ij7 changed ,dax1 near ,bourdeaux into ,dax1 near ,bordeaux page #gb changed indicate the intermittance into indicate the intermittence page #gd changed figure number #if to figure #ic page #ge changed ,modica1 precipitious into ,modica1 precipitous page #gg changed them by ,dr4 ,macculloch1 into them by ,dr4 ,mac,culloch1 page #hf changed ,dr4 ,macculloch and into ,dr4 ,mac,culloch and page #hg changed have ever re-appeared into have ever reappeared page #ih changed fossilisation of certain into fossilization of certain page #ajf changed hills called ,bruder ,holz into hills called ,bruderholz page #abj changed near ,stuttgardt1 in into near ,stuttgart1 in page #abj changed stones have travelled into stones have travelled4 page #aba changed already characterised by into already characterized by page #abd changed neighbourhood of ,upsal1 into neighbourhood of ,upsala1 page #abd changed ,isles of sub-aerial glaciers4 into ,isles of subaerial glaciers4 page #acj added ,,boulder ,,formation--continued4 to chapter heading page #aca changed its materials rearranged into its materials re-arranged page #acf changed chapters #g and #h41 into chapters #g4 and #h41 page #aci changed to coexist in into to co-exist in page #adg changed class of warm-blodded into class of warm-blooded page #adh changed speces of deer into species of deer page #aed changed skeletons of ,magatherium1 into skeletons of ,megatherium1 page #aeg changed student to recognise the into student to recognize the page #aei changed b4 nat4 size of a and b4 into c4 nat4 size of a and b4 page #afa 7fig4 #ada7 changed overan are a into over an area page #afb changed concretionary rearrangement of into concretionary re-arrangement of page #afd changed ,faseicularia aurantium into ,fascicularia aurantium page #afe 7fig4 #adh7 changed v4 exterior4 into a4 exterior4 page #afe 7fig4 #adh47 changed climates1 such a into climates1 such as page #afe changed clayslate1 and various into clay-slate1 and various page #afi changed from the ,appenines into from the ,apennines page #afh changed #ag per cent1 into #ag per cent41 page #agb changed beds 7,sables inferieurs into beds 7,sables inferieurs page #age changed inferieurs et argiles into inferieurs et argiles page #age changed ,upper ,marine or ,fontainbleau into ,upper ,marine or ,fontainebleau page #agg changed ,m4 de ,koninck of ,liege into ,m4 ,de ,koninck of ,liege page #agh changed or ,caddice-fly into or ,caddis-fly page #ahe changed lake of the ,lemagne into lake of the ,limagne page #ahg changed ,bagshot and ,brocklesham division into ,bagshot and ,bracklesham division page #aij changed ,nome of them into ,none of them page #aib changed genera ,emys and ,trionix4 into genera ,emys and ,trionyx4 page #aib changed ,sables ,moyens4 divide into ,sables ,moyens1 divide page #aic changed of the ,english ,eocenestrata1 into of the ,english ,eocene strata1 page #aig changed ,headen ,hill1 on into ,headon ,hill1 on page #aig changed ,egerton has recognised into ,egerton has recognized page #aih changed brown and blueish gray into brown and blueish grey page #bjj changed beds ,nos4 #a1 #b4 are into beds ,nos4 #a1 #b41 are page #bjh changed places for mill-stones4 into places for millstones4 page #bjh changed of ,d',orbigny before into of d',orbigny before page #bjh changed sea-cliffs at ,stevensklint into sea-cliffs at ,stevens ,klint page #baj changed and ,ostrea1 vesicularis4 into and ,ostrea vesicularis4 page #bae changed bivalves 7figs4 #bjc4 #bje1 into bivalves 7figs4 #bjc1 #bje1 page #baf changed the ,dammura of into the ,dammara of page #baf changed afterwards recognised by into afterwards recognized by page #baf changed of the ,radack achipelago1 into of the ,radack archipelago1 page #bag changed observations of ,ferdinand ,roemer2 into observations of ,ferdinand ,roemer2 page #bbd changed the marl-stones are into the marlstones are page #bbd changed ,wealden 7see ,nos4 #e into ,wealden 7see ,nos4 #e4 page #bbe changed purely fresh-water origin4 into purely freshwater origin4 page #bbg changed ,auvergne 7see above1 p4 #ahc47 into ,auvergne 7see above1 p4 #ahc474 page #bbh changed genera ,trioynx and ,emys1 into genera ,trionyx and ,emys1 page #bbi changed ,see ,flinder's ,voyage4 into ,see ,flinders' ,voyage4 footnote #bcc-;,a changed ,author's ,annivers4 ,address1 into ,author's ,anniv4 ,address1 footnote #bcg-;,c changed those from the ,gualt into those from the ,gault page #bdb changed eological ,map of into ,geological ,map of page #bdb 7fig4 #beb7 changed 7fig4 #bed471 where into 7fig4 #bec471 where page #bdd changed in the north into in the ,north page #bde changed ,in the wood-cut into ,in the woodcut page #bdf changed ,south ,downs at ,beachy head4 into ,south ,downs at ,beachy ,head4 page #bdf changed fail to recognise in into fail to recognize in page #bdf changed voll4 ii4 p4 #ih4 into vol4 ii4 p4 #ih4 footnote #bdh-;,a changed of clay aud limestone1 into of clay and limestone1 page #beh changed ,coral rag1 into ,coral rag4 page #bfa 7fig4 #bgc7 changed in their orginal into in their original page #bfd changed says ,mr ,lycett1 into says ,mr4 ,lycett1 page #bff changed such as ,pleiosaur1 into such as ,plesiosaur1 page #bfg changed obtained by ,dr ,buckland into obtained by ,dr4 ,buckland page #bfh changed that the ,thuia1 into that the ,thuja1 page #bgj changed ,buckland's ,bridgw4 ,treat4 into ,buckland's ,bridgew4 ,treat4 page #bga 7fig4 #bid7 changed lower shales are wel into lower shales are well page #bga changed the ,oolitic system generally into the ,oolitic system generally4 page #bgb changed #a_/c nat size4 into #a_/c nat4 size4 page #bgc 7fig4 #cja7 changed 7,g4 arcuata1 ,lam7 into 7,g4 arcuata1 ,lam47 page #bgd 7fig4 #cjd7 changed their own predacious race into their own predaceous race page #bgh changed both of ,icthyosaur and ,plesiosaur into both of ,ichthyosaur and ,plesiosaur page #bgh changed for swimming 7see fig4 #cac47 into for swimming 7see fig4 #cac474 page #bgi changed ,sir ,h4 de la ,beche1 into ,sir ,h4 ,de la ,beche1 page #bha changed of the ,haute ,saone1 into of the ,haute-,saone1 page #bhc changed in ,germany-,keupar into in ,germany-,keuper page #bhf changed ,buckland1 ,bridg4 ,treat41 into ,buckland1 ,bridgew4 ,treat41 footnote #bhf-;,a changed calcaire coquillier into calcaire coquillier4 page #bhg changed ,wuerttemberg1 and is into ,wuertemberg1 and is page #bhg changed genera ,sauricthys and ,gyrolepis into genera ,saurichthys and ,gyrolepis page #bhg changed near ,strazburg1 on into near ,strasburg1 on page #bhh changed the gres bigarre1 or into the gres bigarre1 or page #bhh changed vol4 v4 p4 #cdg into vol4 v4 p4 #cdg4 footnote #bij-;,b changed in the gray1 and into in the grey1 and page #bid changed with ornithicnites on into with ornithichnites on page #cjj changed and botroidal character4 into and botryoidal character4 page #cjb changed the icthyolites which into the ichthyolites which page #cjd changed ,pygopteris mandibularis into ,pygopterus mandibularis page #cje 7fig4 #cdf7 changed ,gutbier are ,asterophillites into ,gutbier are ,asterophyllites page #cjg changed ,lepidodendra1 ,calamites1 ,asterophillites1 into ,lepidodendra1 ,calamites1 ,asterophyllites1 page #cjh changed same bands of into some bands of page #cji changed sometimes called fire-stone1 into sometimes called firestone1 page #cji changed ,geol4 ,soc ,proceedings1 into ,geol4 ,soc4 ,proceedings1 footnote #cag-;,b changed f4 #d4 feet oal into f4 #d4 feet coal4 page #cba 7fig4 #cgb7 changed at an angle of #h deg41 into at an angle of #h deg44 page #cbd changed genus called ,michroconchus into genus called ,microconchus page #cbd changed of ,sigillaria1 ,lepidodrendon1 into of ,sigillaria1 ,lepidodendron1 page #cbd changed frequently recognised4 ,thus1 into frequently recognized4 ,thus1 page #cbd changed be recognised at still into be recognized at still page #cbd changed ,clay iron-stone4--,bands and nodules of clay iron-stone into ,clay-iron-stone4--,bands and nodules of clay-iron-stone page #cbf changed ,dome-shaped out-crop of into ,dome-shaped outcrop of page #cbg changed ornithichnites 7see p4 #big474 into ornithichnites 7see p4 #cbg474 page #cbh changed ,the out-crop of into ,the outcrop of page #cbh changed olifiant gas4 ,the into olefiant gas4 ,the page #ccc changed ,american ,journ4 of ,sci1 into ,american ,journ4 of ,sci41 footnote #ccd-;,a changed a neucleus of granite1 into a nucleus of granite1 page #cdc changed ,scale of ,holoptychus nobilissimus1 into ,scale of ,holoptychius nobilissimus1 page #cdd 7fig4 #cie7 changed peculiar lamelli-branchiate into peculiar lamellibranchiate page #cdg changed south from ,st4 ,petersburgh4 into south from ,st4 ,petersburg4 page #cdh changed of the ,astraea4 into of the ,astrea4 page #cdi changed lowest or mud-stone beds1 into lowest or mudstone beds1 page #ceb changed showing siphuncle4 ,ludlow into showing siphuncle4 ,ludlow4 page #ced 7fig4 #dag7 changed the ,welch mountains afford4 into the ,welsh mountains afford4 page #cei changed ,kleyn ,spawen beds1 into ,kleyn ,spauwen beds1 page #cfb changed belong to neighboring into belong to neighbouring page #cfb changed with gypsum--,wirtemberg1 into with gypsum--,wuertemberg1 page #cfd changed ,crinoidians abundant into ,crinoideans abundant page #cfe changed like chelonians1 ,ptericthys1 into like chelonians1 ,pterichthys1 page #cfe changed were recognised as into were recognized as page #cff changed ,their igneons origin into ,their igneous origin page #cff changed recognised by a peculiar into recognized by a peculiar page #cgj changed ,one half ,i scoriaceous1 into ,one half is scoriaceous1 page #cgc changed others are ,andesitic1 into others are andesitic1 page #cgc changed tom4 #h4 p4 #bb4 #ahce4 into tom4 #h4 p4 #bb4 #ahce47 page #cge changed ,a green porphyritic rocks into ,a green porphyritic rock page #cgf changed ,saussurite1 a mineral into saussurite1 a mineral page #cgf changed oxyde of iron4 into oxide of iron4 page #cgf changed of talc4 ,burat's into of talc4 7,burat's page #cgf changed ,sub-marine lava and into ,submarine lava and page #cgh changes much as #bj per cent of into much as #bj per cent4 of page #chb changed of ,hutt4 ,theory1 s4 #bec4 into of ,hutt4 ,theory1 p4 #bec4 footnote #chc-;,b changed ,giants' ,causeway1 in ,ireland4 into ,giant's ,causeway1 in ,ireland4 page #chd changed bottom of a shallow sea into bottom of a shallow sea4 page #chh changed to larva and into to lava and page #chh changed ,,porm1 ,,structure1 ,,and into ,,form1 ,,structure1 ,,and page #cij changed ,baranco de las ,angustias4 into ,barranco de las ,angustias4 page #cia changed lie uncomformably to into lie unconformably to page #cih changed trap-dikes of ,etna1 into trap dikes of ,etna1 page #dja changed the accompanying wood-cut into the accompanying woodcut page #djd changed in once instance into in one instance page #djd changed ,punto del ,nasone on ,somma into ,punta del ,nasone on ,somma page #dje 7fig4 #dfg7 changed we recognise the ordinary into we recognize the ordinary page #dah changed near ,st4 ,andrew's into near ,st4 ,andrews page #dbb changed crystals of mesotyge into crystals of mesotype page #dca changed ,h4 de la ,beche during into ,h4 ,de la ,beche during page #dcb changed ,geol4 ,trans1 #b;d into ,geol4 ,trans41 #b;d footnote #dce-;,e changed silex1 thay have into silex1 they have page #dci changed except when mineralogicaly into except when mineralogically page #ddj changed ,bontigny's experiments have into ,boutigny's experiments have page #dda changed mineral camposition-,test into mineral composition-,test page #ddi changed ,granite of ,dartmore altering into ,granite of ,dartmoor altering page #ddi changed are many vareties into are many varieties page #dej changed the gritz quartzose into the grits quartzose page #def changed ay at smome into may at some page #dfb changed and their synonymes4 into and their synonymies4 page #dfe changed ,these aeriform fluids1 into ,these aeriform fluids1 page #dgf changed fumeroles have been into fumaroles have been page #dgf changed its being nonfossiliferous1 into its being non-fossiliferous1 page #dgi changed have become matamorphic into have become metamorphic page #dhd changed ,,mm4 ,studer1 and ,hugi1 into ,,mm4 ,studer and ,hugi1 page #dhd changed hornblende-schist1 chlorine-schist1 into hornblende-schist1 chlorite-schist1 page #dhe changed enlarged or reopened4 into enlarged or re-opened4 page #dhh changed vein of ,andreasburg into vein of ,andreasberg page #did changed greenstone1 or toad-stone1 into greenstone1 or toadstone1 page #dig changed can be recognised in into can be recognized in page #dih changed ,h4 de la ,beche during into ,h4 ,de la ,beche during page #dii changed ,lithodomi in beaches into lithodomi in beaches1 page #ejb changed ,barrarde1 ,m41 on trilobites1 #ceh4 into ,barrande1 ,m41 on trilobites1 #ceh4 page #ejb changed ,argile plastiqne1 or into ,argile plastique1 or page #ejb changed or inland into on inland page #ejb changed on cornish lodes1 into on ,cornish lodes1 page #ejc changed on ,sewalik hills1 into on ,sewalik hills1 page #ejc changed ,caryophillia cespitosa1 bed into ,caryophyllia caespitosa1 bed page #ejc changed ,cystidiae in ,silurian rocks1 #ceh4 into ,cystideae in ,silurian rocks1 #ceh4 page #ejd changed ,decken1 ,prof4 von1 on reptiles in ,saarbrueck coalfield1 #ccf4 into ,dechen1 ,prof4 von1 on reptiles in ,saarbrueck coal-field1 #ccf4 page #eje changed ,france1 #agf-aif4 into ,france1 #agf-aia4 page #eje changed ,doue1 ,m4 ,b4 de1 on into ,doue1 ,m4 ,b4 de1 on page #eje changed ,desroyers1 ,m41 on into ,desnoyers1 ,m41 on page #eje changed on ,icthyosaurus1 #bgf4 into on ,ichthyosaurus1 #bgf4 page #eje changed hill of ,gergovla1 into hill of ,gergovia1 page #eje changed on ,cystidiae1 #ceh4 into on ,cystideae1 #ceh4 page #eje changed ,glenroy1 parallel into ,glen ,roy1 parallel page #ejf changed sienitic1 #ddj4 into syenitic1 #ddj4 page #ejf changed vesiculosus in ,lym-fiord1 #cc4 into vesiculosus in ,lym-,fiord1 #cc4 page #ejf changed ,hamilton4 ,sir ,w41 into ,hamilton1 ,sir ,w41 page #ejg changed ,hooghley river1 analysis into ,hooghly river1 analysis page #ejg changed ,icthyolites of ,old into ,ichthyolites of ,old page #ejg changed ,icthyosaurus communis1 figure into ,ichthyosaurus communis1 figure page #ejg changed period1 ,volcanic rocks1 into period4 ,volcanic rocks1 page #ejg changed ,kentish chalk1 sandgalls into ,kentish chalk1 sand-galls page #ejg changed ,limestone1 fosslliferous1 into ,limestone1 fossiliferous1 page #ejh changed ,lochabar1 parallel roads into ,lochaber1 parallel roads page #ejh changed in cannel coal into in ,cannel coal page #ejh changed enlarged and reopened1 #dib4 into enlarged and re-opened1 #dib4 page #ejh changed teeth of4 figured1 into teeth of1 figured1 page #ejh changed ,mammifer in trlas into ,mammifer in trias page #ejh changed on ,stonefield slate1 #bff4 into on ,stonesfield slate1 #bff4 page #ejh changed ,mososaurus in ,st4 ,peter's into ,mosasaurus in ,st4 ,peter's page #eji changed ,oeynhansen1 ,m4 von1 on into ,oeynhausen1 ,m4 von1 on page #eji changed ,saarbruck coal field1 into ,saarbrueck coal field1 page #eaj changed sandpipes near1 into sand-pipes near1 page #eji changed ,st4 ,andrew's1 trap into ,st4 ,andrews1 trap page #eaj changed ,plutonic rocks1 #g-ddf4 into ,plutonic rocks1 #g4 #ddf4 page #eaj changed ,rose1 ,frof4 ,g41 into ,rose1 ,prof4 ,g41 page #eaj changed of ,colebrook ,dale1 into of ,coalbrook ,dale1 page #eaj changed sandpipes in1 #hc4 into sand-pipes in1 #hc4 page #eaj changed ,sandpipes near ,maestricht into ,sand-pipes near ,maestricht page #eaj changed or sandgalls1 term into or sand-galls1 term page #eaj changed ,seacliffs1 inland1 #ga4 into ,sea cliffs1 inland1 #ga4 page #eaj changed ,sedgewick1 ,prof41 cited1 into ,sedgwick1 ,prof41 cited1 page #eaj changed ,sedgewick1 ,prof41 on into ,sedgwick1 ,prof41 on page #eaa changed ,sewalik ,hills1 freshwater into ,sewalik ,hills1 freshwater page #eaa changed ,skapter ,jokul1 eruption into ,skaptar ,jokul1 eruption page #eaa changed ,sub-,apennine strata1 #aje4 #aff4 into ,subapennine strata1 #aje1 #aff4 page #eaa changed on sand galls1 #hb4 into on sand-galls1 #hb4 page #eab added ,header ,w4 in index page #eab changed ,wenlok formation1 #ced4 into ,wenlock formation1 #ced4 page #eab changed ,whin-,sil1 intrusion of into ,whin-,sill1 intrusion of page #eab changed on ,cystidae1 #ceh4 into on ,cystideae1 #ceh4 page #eab changed in ',lavengro4' because into in ',lavengro' because ,advertisements changed ,vols4 ,i-,,viii4 ,with into ,vols4 ,i4-,,viii4 ,with ,advertiesements changed early religous schools into early religious schools ,advertisements changed its organisation more into its organization more ,advertisements changed with unfagging tread into with unflagging tread ,advertisements changed of time and money into of time and money4 ,advertisements changed ,a ,,condensed ,,hand-,,book ,,of ,,all ,,england into ,a ,,condensed ,,handbook ,,of ,,all ,,england ,advertisements changed ,leicester1 ,bucks ,nottinghamshire4 into ,leicester1 ,bucks1 ,nottinghamshire4 ,advertisements changed ,warwick1 ,glocester1 ,worcester1 into ,warwick1 ,gloucester1 ,worcester1 ,advertisements