,geological ,observations on ,south ,america ,by ,charles ,darwin ,,contents ,,editorial ,,note4 ,,detailed ,,table ,,of ,,contents4 ,,geological ,,observations ,,on ,,south ,,america ,,critical ,,introduction4 ,,chapter ,i4 ,,on ,,the ,,elevation ,,of ,,the ,,eastern ,,coast ,,of ,,south ,,america4 ,,chapter ,,ii4 ,,on ,,the ,,elevation ,,of ,,the ,,western ,,coast ,,of ,,south ,,america4 ,,chapter ,,iii4 ,,on ,,the ,,plains ,,and ,,valleys ,,of ,,chile3--,,saliferous ,,superficial ,,deposits4 ,,chapter ,,iv4 ,,on ,,the ,,formations ,,of ,,the ,,pampas4 ,,chapter ,v4 ,,on ,,the ,,older ,,tertiary ,,formations ,,of ,,patagonia ,,and ,,chile4 ,,chapter ,,vi4 ,,plutonic ,,and ,,metamorphic ,,rocks3--,,cleavage ,,and ,,foliation4 ,,chapter ,,vii4 ,,central ,,chile3--,,structure ,,of ,,the ,,cordillera4 ,,chapter ,,viii4 ,,northern ,,chile4--,,conclusion4 ,,index ,,editorial ,,note4 ,although in some respects more technical in their subjects and style than ,darwin's 8,journal10 the books here reprinted will never lose their value and interest for the originality of the observations they contain4 ,many parts of them are admirably adapted for giving an insight into problems regarding the structure and changes of the earth's surface1 and in fact they form a charming introduction to physical geology and physiography in their application to special domains4 ,the books themselves cannot be obtained for many times the price of the present volume1 and both the general reader1 who desires to know more of ,darwin's work1 and the student of geology1 who naturally wishes to know how a master mind reasoned on most important geological subjects1 will be glad of the opportunity of possessing them in a convenient and cheap form4 ,the three introductions1 which my friend ,professor ,judd has kindly furnished1 give critical and historical information which makes this edition of special value4 ,g4,t4,b4 ,,detailed ,,table ,,of ,,contents4 ,,critical ,,introduction4 ,,chapter ,i4 ,,on ,,the ,,elevation ,,of ,,the ,,eastern ,,coast ,,of ,,south ,,america4 ,upraised shells of ,la ,plata4--,bahia ,blanca1 ,sand-dunes and ,pumice-pebbles4--,step-formed plains of ,patagonia1 with upraised shells4--,terrace-bounded valley of ,santa ,cruz1 formerly a sea-strait4--,upraised shells of ,tierra del ,fuego4--,length and breadth of the elevated area4--,equability of the movements1 as shown by the similar heights of the plains4--,slowness of the elevatory process4--,mode of formation of the step-formed plains4--,summary4- -,great shingle formation of ,patagonia2 its extent1 origin1 and distribution4--,formation of sea-cliffs4 ,,chapter ,,ii4 ,,on ,,the ,,elevation ,,of ,,the ,,western ,,coast ,,of ,,south ,,america4 ,chonos ,archipelago4--,chiloe1 recent and gradual elevation of1 traditions of the inhabitants on this subject4--,concepcion1 earthquake and elevation of4--,,valparaiso1 great elevation of1 upraised shells1 earth or marine origin1 gradual rise of the land within the historical period4--,,coquimbo1 elevation of1 in recent times2 terraces of marine origin1 their inclination1 their escarpments not horizontal4--,guasco1 gravel terraces of4--,copiapo4--,,peru4-- ,upraised shells of ,cobija1 ,iquique1 and ,arica4--,lima1 shell-beds and sea- beach on ,san ,lorenzo4--,human remains1 fossil earthenware1 earthquake debacle1 recent subsidence4--,on the decay of upraised shells4--,general summary4 ,,chapter ,,iii4 ,,on ,,the ,,plains ,,and ,,valleys ,,of ,,chile3--,,saliferous ,,superficial ,,deposits4 ,basin-like plains of ,chile2 their drainage1 their marine origin4--,marks of sea-action on the eastern flanks of the ,cordillera4--,sloping terrace-like fringes of stratified shingle within the valleys of the ,cordillera2 their marine origin4--,boulders in the valley of ,cachapual4--,horizontal elevation of the ,cordillera4--,formation of valleys4--,boulders moved by earthquake- waves4--,saline superficial deposits4--,bed of nitrate of soda at ,iquique4-- ,saline incrustations4--,salt-lakes of ,la ,plata and ,patagonia2 purity of the salt2 its origin4 ,,chapter ,,iv4 ,,on ,,the ,,formations ,,of ,,the ,,pampas4 ,mineralogical constitution4--,microscopical structure4--,buenos ,ayres1 shells embedded in tosca-rock4--,buenos ,ayres to the ,colorado4--,s4 ,ventana4--,bahia ,blanca2 ,m4 ,hermoso1 bones and infusoria of2 ,p4 ,alta1 shells1 bones1 and infusoria of2 co-existence of the recent shells and extinct mammifers4-- ,buenos ,ayres to ,st4 ,fe4--,skeletons of ,mastodon4--,infusoria4--,inferior marine tertiary strata1 their age4--,horse's tooth4 ,,banda ,,oriental4-- ,superficial ,pampean formation4--,inferior tertiary strata1 variation of1 connected with volcanic action2 ,macrauchenia ,patachonica at ,s4 ,julian in ,patagonia1 age of1 subsequent to living mollusca and to the erratic block period4 ,,summary4--,area of ,pampean formation4--,theories of origin4--,source of sediment4--,estuary origin4--,contemporaneous with existing mollusca4-- ,relations to underlying tertiary strata4 ,ancient deposit of estuary origin4--,elevation and successive deposition of the ,pampean formation4-- ,number and state of the remains of mammifers2 their habitation1 food1 extinction1 and range4--,conclusion4--,supplement on the thickness of the ,pampean formation4--,localities in ,pampas at which mammiferous remains have been found4 ,,chapter ,v4 ,,on ,,the ,,older ,,tertiary ,,formations ,,of ,,patagonia ,,and ,,chile4 ,rio ,negro4--,s4 ,josef4--,port ,desire1 white pumiceous mudstone with infusoria4--,port ,s4 ,julian4--,santa ,cruz1 basaltic lava of4--,p4 ,gallegos4-- ,eastern ,tierra del ,fuego2 leaves of extinct beech-trees4--,summary on the ,patagonian tertiary formations4--,tertiary formations of the ,western ,coast4--,chonos and ,chiloe groups1 volcanic rocks of4--,concepcion4--,navidad4-- ,coquimbo4--,summary4--,age of the tertiary formations4--,lines of elevation4-- ,silicified wood4--,comparative ranges of the extinct and living mollusca on the ,west ,coast of ,s4 ,america4--,climate of the tertiary period4--,on the causes of the absence of recent conchiferous deposits on the coasts of ,south ,america4--,on the contemporaneous deposition and preservation of sedimentary formations4 ,,chapter ,,vi4 ,,plutonic ,,and ,,metamorphic ,,rocks3--,,cleavage ,,and ,,foliation4 ,brazil1 ,bahia1 gneiss with disjointed metamorphosed dikes4--,strike of foliation4--,rio de ,janeiro1 gneiss-granite1 embedded fragment in1 decomposition of4--,la ,plata1 metamorphic and old volcanic rocks of4--,s4 ,ventana4--,claystone porphyry formation of ,patagonia2 singular metamorphic rocks2 pseudo-dikes4--,falkland ,islands1 palaeozoic fossils of4--,tierra del ,fuego1 clay-slate formation1 cretaceous fossils of2 cleavage and foliation2 form of land4--,chonos ,archipelago1 mica-schists1 foliation disturbed by granitic axis2 dikes4--,chiloe4--,concepcion1 dikes1 successive formation of4--,central and ,northern ,chile4--,concluding remarks on cleavage and foliation4--,their close analogy and similar origin4--,stratification of metamorphic schists4--,foliation of intrusive rocks4--,relation of cleavage and foliation to the lines of tension during metamorphosis4 ,,chapter ,,vii4 ,,central ,,chile3--,,structure ,,of ,,the ,,cordillera4 ,central ,chile4--,basal formations of the ,cordillera4--,origin of the porphyritic clay-stone conglomerate4--,andesite4--,volcanic rocks4--,section of the ,cordillera by the ,peuquenes or ,portillo ,pass4--,great gypseous formation4--,peuquenes line2 thickness of strata1 fossils of4--,portillo line4--,conglomerate1 orthitic granite1 mica-schist1 volcanic rocks of4-- ,concluding remarks on the denudation and elevation of the ,portillo line4-- ,section by the ,cumbre1 or ,uspallata ,pass4--,porphyries4--,gypseous strata4-- ,section near the ,puente del ,inca2 fossils of4--,great subsidence4--,intrusive porphyries4--,plain of ,uspallata4--,section of the ,uspallata chain4-- ,structure and nature of the strata4--,silicified vertical trees4--,great subsidence4--,granitic rocks of axis4--,concluding remarks on the ,uspallata range2 origin subsequent to that of the main ,cordillera2 two periods of subsidence2 comparison with the ,portillo chain4 ,,chapter ,,viii4 ,,northern ,,chile4--,,conclusion4 ,a ,section from ,illapel to ,combarbala2 gypseous formation with silicified wood4--,panuncillo4--,coquimbo2 mines of ,arqueros2 section up valley2 fossils4--,guasco1 fossils of4--,copiapo1 section up valley2 ,las ,amolanas1 silicified wood4--,conglomerates1 nature of former land1 fossils1 thickness of strata1 great subsidence4--,valley of ,despoblado1 fossils1 tufaceous deposit1 complicated dislocations of4--,relations between ancient orifices of eruption and subsequent axes of injection4--,iquique1 ,peru1 fossils of1 salt-deposits4--,metalliferous veins4--,summary on the porphyritic conglomerate and gypseous formations4--,great subsidence with partial elevations during the cretaceo-oolitic period4--,on the elevation and structure of the ,cordillera4--,recapitulation on the tertiary series4-- ,relation between movements of subsidence and volcanic action4--,pampean formation4--,recent elevatory movements4--,long-continued volcanic action in the ,cordillera4--,conclusion4 ,,geological ,,observations ,,on ,,south ,,america ,,critical ,,introduction4 ,of the remarkable 8trilogy0 constituted by ,darwin's writings which deal with the geology of the 8,beagle10 the member which has perhaps attracted least attention1 up to the present time is that which treats of the geology of ,south ,america4 ,the actual writing of this book appears to have occupied ,darwin a shorter period than either of the other volumes of the series2 his diary records that the work was accomplished within ten months1 namely1 between ,july #ahdd and ,april #ahde2 but the book was not actually issued till late in the year following1 the preface bearing the date 8,september #ahdf40 ,altogether1 as ,darwin informs us in his 8,autobiography10 the geological books 8consumed four and a half years' steady work10 most of the remainder of the ten years that elapsed between the return of the 8,beagle10 and the completion of his geological books being1 it is sad to relate1 8lost through illness60 ,concerning the 8,geological ,observations on ,south ,america10 ,darwin wrote to his friend ,lyell1 as follows3--8,my volume will be about #bdj pages1 dreadfully dull1 yet much condensed4 ,i think whenever you have time to look through it1 you will think the collection of facts on the elevation of the land and on the formation of terraces pretty good40 8,much condensed0 is the verdict that everyone must endorse1 on rising from the perusal of this remarkable book2 but by no means 8dull40 ,the three and a half years from ,april #ahcb to ,september #ahce1 were spent by ,darwin in ,south ,america1 and were devoted to continuous scientific work2 the problems he dealt with were either purely geological or those which constitute the borderland between the geological and biological sciences4 ,it is impossible to read the journal which he kept during this time without being impressed by the conviction that it contains all the germs of thought which afterwards developed into the 8,origin of ,species40 ,but it is equally evident that after his return to ,england1 biological speculations gradually began to exercise a more exclusive sway over ,darwin's mind1 and tended to dispossess geology1 which during the actual period of the voyage certainly engrossed most of his time and attention4 ,the wonderful series of observations made during those three and a half years in ,south ,america could scarcely be done justice to1 in the #bdj pages devoted to their exposition4 ,that he executed the work of preparing the book on ,south ,america in somewhat the manner of a task1 is shown by many references in his letters4 ,writing to ,sir ,joseph ,hooker in #ahde1 he says1 8,i hope this next summer to finish my ,south ,american ,geology1 then to get out a little ,zoology1 and ,,hurrah ,,for ,,my ,,species ,,work60 ,it would seem that the feeling of disappointment1 which ,darwin so often experienced in comparing a book when completed1 with the observations and speculations which had inspired it1 was more keenly felt in the case of his volume on ,south ,america than any other4 ,to one friend he writes1 8,i have of late been slaving extra hard1 to the great discomfiture of wretched digestive organs1 at ,south ,america1 and thank all the fates1 ,i have done three-fourths of it4 ,writing plain ,english grows with me more and more difficult1 and never attainable4 ,as for your pretending that you will read anything so dull as my pure geological descriptions1 lay not such a flattering unction on my soul1 for it is incredible40 ,to another friend he writes1 8,you do not know what you threaten when you propose to read it--it is purely geological4 ,i said to my brother1 #8,you will of course read it1' and his answer was1 #8,upon my life1 ,i would sooner even buy it4'0 ,in spite of these disparaging remarks1 however1 we are strongly inclined to believe that this book1 despised by its author1 and neglected by his contemporaries1 will in the end be admitted to be one of ,darwin's chief titles to fame4 ,it is1 perhaps1 an unfortunate circumstance that the great success which he attained in biology by the publication of the 8,origin of ,species0 has1 to some extent1 overshadowed the fact that ,darwin's claims as a geologist1 are of the very highest order4 ,it is not too much to say that1 had ,darwin not been a geologist1 the 8,origin of ,species0 could never have been written by him4 ,but apart from those geological questions1 which have an important bearing on biological thought and speculation1 such as the proofs of imperfection in the geological record1 the relations of the later tertiary faunas to the recent ones in the same areas1 and the apparent intermingling of types belonging to distant geological epochs1 when we study the palaeontology of remote districts1--there are other purely geological problems1 upon which the contributions made by ,darwin are of the very highest value4 ,i believe that the verdict of the historians of science will be that if ,darwin had not taken a foremost place among the biologists of this century1 his position as a geologist would have been an almost equally commanding one4 ,but in the case of ,darwin's principal geological work--that relating to the origin of the crystalline schists1--geologists were not at the time prepared to receive his revolutionary teachings4 ,the influence of powerful authority was long exercised1 indeed1 to stifle his teaching1 and only now1 when this unfortunate opposition has disappeared1 is the true nature and importance of ,darwin's purely geological work beginning to be recognised4 ,the two first chapters of the 8,geological ,observations on ,south ,america10 deal with the proofs which exist of great1 but frequently interrupted1 movements of elevation during very recent geological times4 ,in connection with this subject1 ,darwin's particular attention was directed to the relations between the great earthquakes of ,south ,america--of some of which he had impressive experience--and the permanent changes of elevation which were taking place4 ,he was much struck by the rapidity with which the evidence of such great earth movements is frequently obliterated2 and especially with the remarkable way in which the action of rain-water1 percolating through deposits on the earth's surface1 removes all traces of shells and other calcareous organisms4 ,it was these considerations which were the parents of the generalisation that a palaeontological record can only be preserved during those periods in which long-continued slow subsidence is going on4 ,this in turn1 led to the still wider and more suggestive conclusion that the geological record as a whole is1 and never can be more than1 a series of more or less isolated fragments4 ,the recognition of this important fact constitutes the keystone to any theory of evolution which seeks to find a basis in the actual study of the types of life that have formerly inhabited our globe4 ,in his third chapter1 ,darwin gives a number of interesting facts1 collected during his visits to the plains and valleys of ,chili1 which bear on the question of the origin of saliferous deposits--the accumulation of salt1 gypsum1 and nitrate of soda4 ,this is a problem that has excited much discussion among geologists1 and which1 in spite of many valuable observations1 still remains to a great extent very obscure4 ,among the important considerations insisted upon by ,darwin is that relating to the absence of marine shells in beds associated with such deposits4 ,he justly argues that if the strata were formed in shallow waters1 and then exposed by upheaval to subaerial action1 all shells and other calcareous organisms would be removed by solution4 ,following ,lyell's method1 ,darwin proceeds from the study of deposits now being accumulated on the earth's surface1 to those which have been formed during the more recent periods of the geological history4 ,his account of the great ,pampean formation1 with its wonderful mammalian remains--,mastodon1 ,toxodon1 ,scelidotherium1 ,macrauchenia1 ,megatherium1 ,megalonyx1 ,mylodon1 and ,glyptodon--this full of interest4 ,his discovery of the remains of a true ,equus afforded a remarkable confirmation of the fact- -already made out in ,north ,america--that species of horse had existed and become extinct in the ,new ,world1 before their introduction by the ,spaniards in the sixteenth century4 ,fully perceiving the importance of the microscope in studying the nature and origin of such deposits as those of the ,pampas1 ,darwin submitted many of his specimens both to ,dr4 ,carpenter in this country1 and to ,professor ,ehrenberg in ,berlin4 ,many very important notes on the microscopic organisms contained in the formation will be found scattered through the chapter4 ,darwin's study of the older tertiary formations1 with their abundant shells1 and their relics of vegetable life buried under great sheets of basalt1 led him to consider carefully the question of climate during these earlier periods4 ,in opposition to prevalent views on this subject1 ,darwin points out that his observations are opposed to the conclusion that a higher temperature prevailed universally over the globe during early geological periods4 ,he argues that 8the causes which gave to the older tertiary productions of the quite temperate zones of ,europe a tropical character1 ,,were ,,of ,a ,,local ,,character ,,and ,,did ,,not ,,affect ,,the ,,whole ,,globe40 ,in this1 as in many similar instances1 we see the beneficial influence of extensive travel in freeing ,darwin's mind from prevailing prejudices4 ,it was this widening of experience which rendered him so especially qualified to deal with the great problem of the origin of species1 and in doing so to emancipate himself from ideas which were received with unquestioning faith by geologists whose studies had been circumscribed within the limits of ,western ,europe4 ,in the ,cordilleras of ,northern and ,central ,chili1 ,darwin1 when studying still older formations1 clearly recognised that they contain an admixture of the forms of life1 which in ,europe are distinctive of the ,cretaceous and ,jurassic periods respectively4 ,he was thus led to conclude that the classification of geological periods1 which fairly well expresses the facts that had been discovered in the areas where the science was first studied1 is no longer capable of being applied when we come to the study of widely distant regions4 ,this important conclusion led up to the further generalisation that each great geological period has exhibited a geographical distribution of the forms of animal and vegetable life1 comparable to that which prevails in the existing fauna and flora4 ,to those who are familiar with the extent to which the doctrine of universal formations has affected geological thought and speculation1 both long before and since the time that ,darwin wrote1 the importance of this new standpoint to which he was able to attain will be sufficiently apparent4 ,like the idea of the extreme imperfection of the ,geological ,record1 the doctrine of ,,local geological formations is found permeating and moulding all the palaeontological reasonings of his great work4 ,in one of ,darwin's letters1 written while he was in ,south ,america1 there is a passage we have already quoted1 in which he expresses his inability to decide between the rival claims upon his attention of 8the old crystalline group of rocks10 and 8the softer fossiliferous beds0 respectively4 ,the sixth chapter of the work before us1 entitled 8,plutonic and ,metamorphic ,rocks--,cleavage and ,foliation10 contains a brief summary of a series of observations and reasonings upon these crystalline rocks1 which are1 we believe1 calculated to effect a revolution in geological science1 and-- though their value and importance have long been overlooked--are likely to entitle ,darwin in the future to a position among geologists1 scarcely1 if at all1 inferior to that which he already occupies among biologists4 ,darwin's studies of the great rock-masses of the ,andes convinced him of the close relations between the granitic or ,plutonic rocks1 and those which were undoubtedly poured forth as lavas4 ,upon his return1 he set to work1 with the aid of ,professor ,miller1 to make a careful study of the minerals composing the granites and those which occur in the lavas1 and he was able to show that in all essential respects they are identical4 ,he was further able to prove that there is a complete gradation between the highly crystalline or granitic rock-masses1 and those containing more or less glassy matter between their crystals1 which constitute ordinary lavas4 ,the importance of this conclusion will be realised when we remember that it was then the common creed of geologists--and still continues to be so on the ,continent--that all highly crystalline rocks are of great geological antiquity1 and that the igneous ejections which have taken place since the beginning of the tertiary periods differ essentially1 in their composition1 their structure1 and their mode of occurrence1 from those which have made their appearance at earlier periods of the world's history4 ,very completely have the conclusions of ,darwin upon these subjects been justified by recent researches4 ,in ,england1 the ,united ,states1 and ,italy1 examples of the gradual passage of rocks of truly granitic structure into ordinary lavas have been described1 and the reality of the transition has been demonstrated by the most careful studies with the microscope4 ,recent researches carried on in ,south ,america by ,professor ,stelzner1 have also shown the existence of a class of highly crystalline rocks--the 8,andengranites0--which combine in themselves many of the characteristics which were once thought to be distinctive of the so-called ,plutonic and volcanic rocks4 ,no one familiar with recent geological literature--even in ,germany and ,france1 where the old views concerning the distinction of igneous products of different ages have been most stoutly maintained--can fail to recognise the fact that the principles contended for by ,darwin bid fair at no distant period to win universal acceptance among geologists all over the globe4 ,still more important are the conclusions at which ,darwin arrived with respect to the origin of the schists and gneisses which cover so large an area in ,south ,america4 ,carefully noting1 by the aid of his compass and clinometer1 at every point which he visited1 the direction and amount of inclination of the parallel divisions in these rocks1 he was led to a very important generalisation-- namely1 that over very wide areas the direction 7strike7 of the planes of cleavage in slates1 and of foliation in schists and gneisses1 remained constant1 though the amount of their inclination 7dip7 often varied within wide limits4 ,further than this it appeared that there was always a close correspondence between the strike of the cleavage and foliation and the direction of the great axes along which elevation had taken place in the district4 ,in ,tierra del ,fuego1 ,darwin found striking evidence that the cleavage intersecting great masses of slate-rocks was quite independent of their original stratification1 and could often1 indeed1 be seen cutting across it at right angles4 ,he was also able to verify ,sedgwick's observation that1 in some slates1 glossy surfaces on the planes of cleavage arise from the development of new minerals1 chlorite1 epidote or mica1 and that in this way a complete graduation from slates to true schists may be traced4 ,darwin further showed that in highly schistose rocks1 the folia bend around and encircle any foreign bodies in the mass1 and that in some cases they exhibit the most tortuous forms and complicated puckerings4 ,he clearly saw that in all cases the forces by which these striking phenomena must have been produced were persistent over wide areas1 and were connected with the great movements by which the rocks had been upheaved and folded4 ,that the distinct folia of quartz1 feldspar1 mica1 and other minerals composing the metamorphic schists could not have been separately deposited as sediment was strongly insisted upon by ,darwin2 and in doing so he opposed the view generally prevalent among geologists at that time4 ,he was thus driven to the conclusion that foliation1 like cleavage1 is not an original1 but a superinduced structure in rock-masses1 and that it is the result of re-crystallisation1 under the controlling influence of great pressure1 of the materials of which the rock was composed4 ,in studying the lavas of ,ascension1 as we have already seen1 ,darwin was led to recognise the circumstance that1 when igneous rocks are subjected to great differential movements during the period of their consolidation1 they acquire a foliated structure1 closely analogous to that of the crystalline schists4 ,like his predecessor in this field of inquiry1 ,mr4 ,poulett ,scrope1 ,charles ,darwin seems to have been greatly impressed by these facts1 and he argued from them that the rocks exhibiting the foliated structure must have been in a state of plasticity1 like that of a cooling mass of lava4 ,at that time the suggestive experiments of ,tresca1 ,daubree1 and others1 showing that solid masses under the influence of enormous pressure become actually plastic1 had not been published4 ,had ,darwin been aware of these facts he would have seen that it was not necessary to assume a state of imperfect solidity in rock-masses in order to account for their having yielded to pressure and tension1 and1 in doing so1 acquiring the new characters which distinguish the crystalline schists4 ,the views put forward by ,darwin on the origin of the crystalline schists found an able advocate in ,mr4 ,daniel ,sharpe1 who in #aheb and #ahed published two papers1 dealing with the geology of the ,scottish ,highlands and of the ,alps respectively1 in which he showed that the principles arrived at by ,darwin when studying the ,south ,american rocks afford a complete explanation of the structure of the two districts in question4 ,but1 on the other hand1 the conclusions of ,darwin and ,sharpe were met with the strongest opposition by ,sir ,roderick ,murchison and ,dr4 ,a4 ,geikie1 who in #ahfa read a paper before the ,geological ,society 8,on the ,coincidence between ,stratification and ,foliation in the ,crystalline ,rocks of the ,scottish ,highlands10 in which they insisted that their observations in ,scotland tended to entirely disprove the conclusions of ,darwin that foliation in rocks is a secondary structure1 and entirely independent of the original stratification of the rock-masses4 ,now it is a most significant circumstance that1 no sooner did the officers of the ,geological ,survey commence the careful and detailed study of the ,scottish ,highlands than they found themselves compelled to make a formal retraction of the views which had been put forward by ,murchison and ,geikie in opposition to the conclusions of ,darwin4 ,the officers of the ,geological ,survey have completely abandoned the view that the foliation of the ,highland rocks has been determined by their original stratification1 and admit that the structure is the result of the profound movements to which the rocks have been subjected4 ,the same conclusions have recently been supported by observations made in many different districts--among which we may especially refer to those of ,dr4 ,h4 ,reusch in ,norway1 and those of ,dr4 ,j4 ,lehmann in ,saxony4 ,at the present time the arguments so clearly stated by ,darwin in the work before us1 have1 after enduring opposition or neglect for a whole generation1 begun to 8triumph all along the line10 and we may look forward confidently to the near future1 when his claim to be regarded as one of the greatest of geological discoverers shall be fully vindicated4 ,,john ,w4 ,,judd4 ,,chapter ,i4 ,,on ,,the ,,elevation ,,of ,,the ,,eastern ,,coast ,,of ,,south ,,america4 ,upraised shells of ,la ,plata4--,bahia ,blanca1 ,sand-dunes and ,pumice-pebbles4--,step-formed plains of ,patagonia1 with upraised ,shells4--,terrace-bounded ,valley of ,santa ,cruz1 formerly a ,sea-strait4--,upraised shells of ,tierra del ,fuego4--,length and breadth of the elevated area4--,equability of the movements1 as shown by the similar heights of the plains4--,slowness of the elevatory process4--,mode of formation of the step-formed plains4--,summary4--,great ,shingle ,formation of ,patagonia2 its extent1 origin1 and distribution4--,formation of sea-cliffs4 ,in the following ,volume1 which treats of the geology of ,south ,america1 and almost exclusively of the parts southward of the ,tropic of ,capricorn1 ,i have arranged the chapters according to the age of the deposits1 occasionally departing from this order1 for the sake of geographical simplicity4 ,the elevation of the land within the recent period1 and the modifications of its surface through the action of the sea 7to which subjects ,i paid particular attention7 will be first discussed2 ,i will then pass on to the tertiary deposits1 and afterwards to the older rocks4 ,only those districts and sections will be described in detail which appear to me to deserve some particular attention2 and ,i will1 at the end of each chapter1 give a summary of the results4 ,we will commence with the proofs of the upheaval of the eastern coast of the continent1 from the ,rio ,plata southward2 and1 in the ,second ,chapter1 follow up the same subject along the shores of ,chile and ,peru4 ,on the northern bank of the great estuary of the ,rio ,plata1 near ,maldonado1 ,i found at the head of a lake1 sometimes brackish but generally containing fresh water1 a bed of muddy clay1 six feet in thickness1 with numerous shells of species still existing in the ,plata1 namely1 the ,azara labiata1 d',orbigny1 fragments of ,mytilus eduliformis1 d',orbigny1 ,paludestrina ,isabellei1 d',orbigny1 and the ,solen ,caribaeus1 ,lam41 which last was embedded vertically in the position in which it had lived4 ,these shells lie at the height of only two feet above the lake1 nor would they have been worth mentioning1 except in connection with analogous facts4 ,at ,monte ,video1 ,i noticed near the town1 and along the base of the mount1 beds of a living ,mytilus1 raised some feet above the surface of the ,plata3 in a similar bed1 at a height from thirteen to sixteen feet1 ,m4 ,isabelle collected eight species1 which1 according to ,m4 d',orbigny1 now live at the mouth of the estuary4 78,voyage dans l',amerique ,merid43 ,part4 ,geolog40 page #ba47 ,at ,colonia del ,sacramiento1 further westward1 ,i observed at the height of about fifteen feet above the river1 there of quite fresh water1 a small bed of the same ,mytilus1 which lives in brackish water at ,monte ,video4 ,near the mouth of ,uruguay1 and for at least thirty-five miles northward1 there are at intervals large sandy tracts1 extending several miles from the banks of the river1 but not raised much above its level1 abounding with small bivalves1 which occur in such numbers that at the ,agraciado they are sifted and burnt for lime4 ,those which ,i examined near the ,a4 ,s4 ,juan were much worn3 they consisted of ,mactra ,isabellei1 d',orbigny1 mingled with few of ,venus sinuosa1 ,lam41 both inhabiting1 as ,i am informed by ,m4 d',orbigny1 brackish water at the mouth of the ,plata1 nearly or quite as salt as the open sea4 ,the loose sand1 in which these shells are packed1 is heaped into low1 straight1 long lines of dunes1 like those left by the sea at the head of many bays4 ,m4 d',orbigny has described an analogous phenomenon on a greater scale1 near ,san ,pedro on the river ,parana1 where he found widely extended beds and hillocks of sand1 with vast numbers of the ,azara labiata1 at the height of nearly #ajj feet 7,english7 above the surface of that river4 7,ibid page #dc47 ,the ,azara inhabits brackish water1 and is not known to be found nearer to ,san ,pedro than ,buenos ,ayres1 distant above a hundred miles in a straight line4 ,nearer ,buenos ,ayres1 on the road from that place to ,san ,isidro1 there are extensive beds1 as ,i am informed by ,sir ,woodbine ,parish1 of the ,azara labiata1 lying at about forty feet above the level of the river1 and distant between two and three miles from it4 78,buenos ,ayres0 etc4 by ,sir ,woodbine ,parish page #afh47 ,these shells are always found on the highest banks in the district3 they are embedded in a stratified earthy mass1 precisely like that of the great ,pampean deposit hereafter to be described4 ,in one collection of these shells1 there were some valves of the ,venus sinuosa1 ,lam41 the same species found with the ,mactra on the banks of the ,uruguay4 ,south of ,buenos ,ayres1 near ,ensenada1 there are other beds of the ,azara1 some of which seem to have been embedded in yellowish1 calcareous1 semi-crystalline matter2 and ,sir ,w4 ,parish has given me from the banks of the ,arroyo del ,tristan1 situated in this same neighbourhood1 at the distance of about a league from the ,plata1 a specimen of a pale- reddish1 calcereo-argillaceous stone 7precisely like parts of the ,pampean deposit the importance of which fact will be referred to in a succeeding chapter71 abounding with shells of an ,azara1 much worn1 but which in general form and appearance closely resemble1 and are probably identical with1 the ,a4 labiata4 ,besides these shells1 cellular1 highly crystalline rock1 formed of the casts of small bivalves1 is found near ,ensenada2 and likewise beds of sea-shells1 which from their appearance appear to have lain on the surface4 ,sir ,w4 ,parish has given me some of these shells1 and ,m4 d',orbigny pronounces them to be3-- #a4 ,buccinanops globulosum1 d',orbigny4 #b4 ,olivancillaria auricularia1 d',orbigny4 #c4 ,venus flexuosa1 ,lam4 #d4 ,cytheraea 7imperfect74 #e4 ,mactra ,isabellei1 d',orbigny4 #f4 ,ostrea pulchella1 d',orbigny4 ,besides these1 ,sir ,w4 ,parish procured 78,buenos ,ayres0 etc4 by ,sir ,w4 ,parish page #afh47 7as named by ,mr4 ,g4,b4 ,sowerby7 the following shells3-- #g4 ,voluta colocynthis4 #h4 ,voluta angulata4 #i4 ,buccinum 7not spec4874 ,all these species 7with1 perhaps1 the exception of the last7 are recent1 and live on the ,south ,american coast4 ,these shell-beds extend from one league to six leagues from the ,plata1 and must lie many feet above its level4 ,i heard1 also1 of beds of shells on the ,somborombon1 and on the ,rio ,salado1 at which latter place1 as ,m4 d',orbigny informs me1 the ,mactra ,isabellei and ,venus sinuosa are found4 ,during the elevation of the ,provinces of ,la ,plata1 the waters of the ancient estuary have but little affected 7with the exception of the sand- hills on the banks of the ,parana and ,uruguay7 the outline of the land4 ,m4 ,parchappe1 however1 has described groups of sand dunes scattered over the wide extent of the ,pampas southward of ,buenos ,ayres 7,d',orbigny 8,voyage ,geolog40 page #dd471 which ,m4 d',orbigny attributes with much probability to the action of the sea1 before the plains were raised above its level4 7,before proceeding to the districts southward of ,la ,plata1 it may be worth while just to state1 that there is some evidence that the coast of ,brazil has participated in a small amount of elevation4 ,mr4 ,burchell informs me1 that he collected at ,santos 7latitude #bd degrees ,s47 oyster-shells1 apparently recent1 some miles from the shore1 and quite above the tidal action4 ,westward of ,rio de ,janeiro1 ,captain ,elliot is asserted 7see ,harlan 8,med4 and ,phys4 ,res40 page #ce and ,dr4 ,meigs in 8,transactions of the ,american ,philosophical ,society071 to have found human bones1 encrusted with sea-shells1 between fifteen and twenty feet above the level of the sea4 ,between ,rio de ,janeiro and ,cape ,frio ,i crossed sandy tracts abounding with sea-shells1 at a distance of a league from the coast2 but whether these tracts have been formed by upheaval1 or through the mere accumulation of drift sand1 ,i am not prepared to assert4 ,at ,bahia 7latitude #ac degrees ,s471 in some parts near the coast1 there are traces of sea-action at the height of about twenty feet above its present level2 there are also1 in many parts1 remnants of beds of sandstone and conglomerate with numerous recent shells1 raised a little above the sea-level4 ,i may add1 that at the head of ,bahia ,bay there is a formation1 about forty feet in thickness1 containing tertiary shells apparently of fresh-water origin1 now washed by the sea and encrusted with ,balini2 this appears to indicate a small amount of subsidence subsequent to its deposition4 ,at ,pernambuco 7latitude #h degrees ,s471 in the alluvial or tertiary cliffs1 surrounding the low land on which the city stands1 ,i looked in vain for organic remains1 or other evidence of changes in level47 ,,southward ,,of ,,the ,,plata4 ,the coast as far as ,bahia ,blanca 7in latitude #ci degrees ,s47 is formed either of a horizontal range of cliffs1 or of immense accumulations of sand-dunes4 ,within ,bahia ,blanca1 a small piece of tableland1 about twenty feet above high-water mark1 called ,punta ,alta1 is formed of strata of cemented gravel and of red earthy mud1 abounding with shells 7with others lying loose on the surface71 and the bones of extinct mammifers4 ,these shells1 twenty in number1 together with a ,balanus and two corals1 are all recent species1 still inhabiting the neighbouring seas4 ,they will be enumerated in the ,fourth ,chapter1 when describing the ,pampean formation2 five of them are identical with the upraised ones from near ,buenos ,ayres4 ,the northern shore of ,bahia ,blanca is1 in main part1 formed of immense sand-dunes1 resting on gravel with recent shells1 and ranging in lines parallel to the shore4 ,these ranges are separated from each other by flat spaces1 composed of stiff impure red clay1 in which1 at the distance of about two miles from the coast1 ,i found by digging a few minute fragments of sea-shells4 ,the sand-dunes extend several miles inland1 and stand on a plain1 which slopes up to a height of between one hundred and two hundred feet4 ,numerous1 small1 well-rounded pebbles of pumice lie scattered both on the plain and sand-hillocks3 at ,monte ,hermoso1 on the flat summit of a cliff1 ,i found many of them at a height of #abj feet 7angular measurement7 above the level of the sea4 ,these pumice pebbles1 no doubt1 were originally brought down from the ,cordillera by the rivers which cross the continent1 in the same way as the river ,negro anciently brought down1 and still brings down1 pumice1 and as the river ,chupat brings down scoriae3 when once delivered at the mouth of a river1 they would naturally have travelled along the coasts1 and been cast up during the elevation of the land1 at different heights4 ,the origin of the argillaceous flats1 which separate the parallel ranges of sand-dunes1 seems due to the tides here having a tendency 7as ,i believe they have on most shoal1 protected coasts7 to throw up a bar parallel to the shore1 and at some distance from it2 this bar gradually becomes larger1 affording a base for the accumulation of sand- dunes1 and the shallow space within then becomes silted up with mud4 ,the repetition of this process1 without any elevation of the land1 would form a level plain traversed by parallel lines of sand-hillocks2 during a slow elevation of the land1 the hillocks would rest on a gently inclined surface1 like that on the northern shore of ,bahia ,blanca4 ,i did not observe any shells in this neighbourhood at a greater height than twenty feet2 and therefore the age of the sea-drifted pebbles of pumice1 now standing at the height of #abj feet1 must remain uncertain4 ,the main plain surrounding ,bahia ,blanca ,i estimated at from two hundred to three hundred feet2 it insensibly rises towards the distant ,sierra ,ventana4 ,there are in this neighbourhood some other and lower plains1 but they do not abut one at the foot of the other1 in the manner hereafter to be described1 so characteristic of ,patagonia4 ,the plain on which the settlement stands is crossed by many low sand-dunes1 abounding with the minute shells of the ,paludestrina australis1 d',orbigny1 which now lives in the bay4 ,this low plain is bounded to the south1 at the ,cabeza del ,buey1 by the cliff-formed margin of a wide plain of the ,pampean formation1 which ,i estimated at sixty feet in height4 ,on the summit of this cliff there is a range of high sand-dunes extending several miles in an east and west line4 ,southward of ,bahia ,blanca1 the river ,colorado flows between two plains1 apparently from thirty to forty feet in height4 ,of these plains1 the southern one slopes up to the foot of the great sandstone plateau of the ,rio ,negro2 and the northern one against an escarpment of the ,pampean deposit2 so that the ,colorado flows in a valley fifty miles in width1 between the upper escarpments4 ,i state this1 because on the low plain at the foot of the northern escarpment1 ,i crossed an immense accumulation of high sand-dunes1 estimated by the ,gauchos at no less than eight miles in breadth4 ,these dunes range westward from the coast1 which is twenty miles distant1 to far inland1 in lines parallel to the valley2 they are separated from each other by argillaceous flats1 precisely like those on the northern shore of ,bahia ,blanca4 ,at present there is no source whence this immense accumulation of sand could proceed2 but if1 as ,i believe1 the upper escarpments once formed the shores of an estuary1 in that case the sandstone formation of the river ,negro would have afforded an inexhaustible supply of sand1 which would naturally have accumulated on the northern shore1 as on every part of the coast open to the south winds between ,bahia ,blanca and ,buenos ,ayres4 ,at ,san ,blas 7#dj degrees #dj ,s47 a little south of the mouth of the ,colorado1 ,m4 d',orbigny found fourteen species of existing shells 7six of them identical with those from ,bahia ,blanca71 embedded in their natural positions4 78,voyage0 etc4 page #ed47 ,from the zone of depth which these shells are known to inhabit1 they must have been uplifted thirty-two feet4 ,he also found1 at from fifteen to twenty feet above this bed1 the remains of an ancient beach4 ,ten miles southward1 but #abj miles to the west1 at ,port ,s4 ,antonio1 the ,officers employed on the ,survey assured me that they saw many old sea- shells strewed on the surface of the ground1 similar to those found on other parts of the coast of ,patagonia4 ,at ,san ,josef1 ninety miles south in nearly the same longitude1 ,i found1 above the gravel1 which caps an old tertiary formation1 an irregular bed and hillock of sand1 several feet in thickness1 abounding with shells of ,patella deaurita1 ,mytilus ,magellanicus1 the latter retaining much of its colour2 ,fusus ,magellanicus 7and a variety of the same71 and a large ,balanus 7probably ,b4 ,tulipa71 all now found on this coast3 ,i estimated this bed at from eighty to one hundred feet above the level of the sea4 ,to the westward of this bay1 there is a plain estimated at between two hundred and three hundred feet in height3 this plain seems1 from many measurements1 to be a continuation of the sandstone platform of the river ,negro4 ,the next place southward1 where ,i landed1 was at ,port ,desire1 #cdj miles distant2 but from the intermediate districts ,i received1 through the kindness of the ,officers of the ,survey1 especially from ,lieutenant ,stokes and ,mr4 ,king1 many specimens and sketches1 quite sufficient to show the general uniformity of the whole line of coast4 ,i may here state1 that the whole of ,patagonia consists of a tertiary formation1 resting on and sometimes surrounding hills of porphyry and quartz3 the surface is worn into many wide valleys and into level step-formed plains1 rising one above another1 all capped by irregular beds of gravel1 chiefly composed of porphyritic rocks4 ,this gravel formation will be separately described at the end of the chapter4 ,my object in giving the following measurements of the plains1 as taken by the ,officers of the ,survey1 is1 as will hereafter be seen1 to show the remarkable equability of the recent elevatory movements4 ,round the southern parts of ,nuevo ,gulf1 as far as the ,river ,chupat 7seventy miles southward of ,san ,josef71 there appear to be several plains1 of which the best defined are here represented4 7,in the following ,diagrams3 #a4 ,baseline is ,level of sea4 #b4 ,scale is #a_/bj of inch to #ajj feet vertical4 #c4 ,height is shown in feet thus3 ,an4 ,m4 always stands for angular or trigonometrical measurement4 ,ba4 ,m4 always stands for barometrical measurement4 ,est4 always stands for estimation by the ,officers of the ,survey4 ,,diagram #a4 ,,section ,,of ,,step-,,formed ,,plains ,,south ,,of ,,nuevo ,,gulf4 ,from ,east 7sea level7 to ,west 7high73 ,terrace #a4 #hj ,est4 ,terrace #b4 #bjj-bbj ,an4 ,m4 ,terrace #c4 #cej ,an4 ,m47 ,the upper plain is here well defined 7called ,table ,hills72 its edge forms a cliff or line of escarpment many miles in length1 projecting over a lower plain4 ,the lowest plain corresponds with that at ,san ,josef with the recent shells on its surface4 ,between this lowest and the uppermost plain1 there is probably more than one step-formed terrace3 several measurements show the existence of the intermediate one of the height given in ,diagram #a4 7,,diagram #b4 ,,section ,,of ,,plains ,,in ,,the ,,bay ,,of ,,st4 ,,george4 ,from ,east 7sea level7 to ,west 7high73 ,terrace #a4 #bej ,an4 ,m4 ,terrace #b4 #ccj ,an4 ,m4 ,terrace #c4 #ehj ,an4 ,m4 ,terraces #d1 #e and #f not measured4 ,terrace #g4 #a1bjj ,est47 ,near the north headland of the great ,bay of ,st4 ,george 7#ajj miles south of the ,chupat71 two well-marked plains of #bej and #ccj feet were measured3 these are said to sweep round a great part of the ,bay4 ,at its south headland1 #abj miles distant from the north headland1 the #bej feet plain was again measured4 ,in the middle of the bay1 a higher plain was found at two neighbouring places 7,tilli ,roads and ,c4 ,marques7 to be #ehj feet in height4 ,above this plain1 towards the interior1 ,mr4 ,stokes informs me that there were several other step-formed plains1 the highest of which was estimated at #a1bjj feet1 and was seen ranging at apparently the same height for #aej miles northward4 ,all these plains have been worn into great valleys and much denuded4 ,the section in ,diagram #c is illustrative of the general structure of the great ,bay of ,st4 ,george4 ,at the south headland of the ,bay of ,st4 ,george 7near ,c4 ,three ,points7 the #bej plain is very extensive4 7,,diagram #c4 ,,section ,,of ,,plains ,,at ,,port ,,desire4 ,from ,east 7sea level7 to ,west 7high73 ,terrace #a4 #ajj ,est4 ,terrace #b4 #bde-bee ,ba4 ,m4 ,shells on surface4 ,terrace #c4 #ccj ,ba4 ,m4 ,shells on surface4 ,terrace #d4 ,not measured47 ,at ,port ,desire 7forty miles southward7 ,i made several measurements with the barometer of a plain1 which extends along the north side of the port and along the open coast1 and which varies from #bde to #bee feet in height3 this plain abuts against the foot of a higher plain of #ccj feet1 which extends also far northward along the coast1 and likewise into the interior4 ,in the distance a higher inland platform was seen1 of which ,i do not know the height4 ,in three separate places1 ,i observed the cliff of the #bde-bee feet plain1 fringed by a terrace or narrow plain estimated at about one hundred feet in height4 ,these plains are represented in the section ,diagram #c4 ,in many places1 even at the distance of three and four miles from the coast1 ,i found on the gravel-capped surface of the #bde-bee feet1 and of the #ccj feet plain1 shells of ,mytilus ,magellanicus1 ,m4 edulis1 ,patella deaurita1 and another ,patella1 too much worn to be identified1 but apparently similar to one found abundantly adhering to the leaves of the kelp4 ,these species are the commonest now living on this coast4 ,the shells all appeared very old2 the blue of the mussels was much faded2 and only traces of colour could be perceived in the ,patellas1 of which the outer surfaces were scaling off4 ,they lay scattered on the smooth surface of the gravel1 but abounded most in certain patches1 especially at the heads of the smaller valleys3 they generally contained sand in their insides2 and ,i presume that they have been washed by alluvial action out of thin sandy layers1 traces of which may sometimes be seen covering the gravel4 ,the several plains have very level surfaces2 but all are scooped out by numerous broad1 winding1 flat-bottomed valleys1 in which1 judging from the bushes1 streams never flow4 ,these remarks on the state of the shells1 and on the nature of the plains1 apply to the following cases1 so need not be repeated4 7,,diagram #d4 ,,section ,,of ,,plains ,,at ,,port ,s4 ,,julian4 ,from ,east 7sea level7 to ,west 7high73 ,terrace #a4 ,shells on surface4 #ij ,est4 ,terrace #b4 #dcj ,an4 ,m4 ,terrace #c4 #efj ,an4 ,m4 ,terrace #d4 #iej ,an4 ,m47 ,southward of ,port ,desire1 the plains have been greatly denuded1 with only small pieces of tableland marking their former extension4 ,but opposite ,bird ,island1 two considerable step-formed plains were measured1 and found respectively to be #cej and #eij feet in height4 ,this latter plain extends along the coast close to ,port ,st4 ,julian 7#aaj miles south of ,port ,desire72 see ,diagram #d4 ,the lowest plain was estimated at ninety feet3 it is remarkable from the usual gravel-bed being deeply worn into hollows1 which are filled up with1 as well as the general surface covered by1 sandy and reddish earthy matter3 in one of the hollows thus filled up1 the skeleton of the ,macrauchenia ,patachonica1 as will hereafter be described1 was embedded4 ,on the surface and in the upper parts of this earthy mass1 there were numerous shells of ,mytilus ,magellanicus and ,m4 edulis1 ,patella deaurita1 and fragments of other species4 ,this plain is tolerably level1 but not extensive2 it forms a promontory seven or eight miles long1 and three or four wide4 ,the upper plains in ,diagram #d were measured by the ,officers of the ,survey2 they were all capped by thick beds of gravel1 and were all more or less denuded2 the #iej plain consists merely of separate1 truncated1 gravel-capped hills1 two of which1 by measurement1 were found to differ only three feet4 ,the #dcj feet plain extends1 apparently with hardly a break1 to near the northern entrance of the ,rio ,santa ,cruz 7fifty miles to the south72 but it was there found to be only #ccj feet in height4 7,,diagram #e4 ,,section ,,of ,,plains ,,at ,,the ,,mouth ,,of ,,the ,,rio ,,santa ,,cruz4 ,from ,east 7sea level7 to ,west 7high73 ,terrace #a4 7sloping7 #cee ,ba4 ,m4 ,shells on surface4 #dfc ,ba4 ,m4 ,terrace #b4 #gaj ,an4 ,m4 ,terrace #c4 #hdj ,an4 ,m47 ,on the southern side of the mouth of the ,santa ,cruz we have ,diagram #e1 which ,i am able to give with more detail than in the foregoing cases4 ,the plain marked #cee feet 7as ascertained by the barometer and by angular measurement7 is a continuation of the above-mentioned #ccj feet plain3 it extends in a ,n4,w4 direction along the southern shores of the estuary4 ,it is capped by gravel1 which in most parts is covered by a thin bed of sandy earth1 and is scooped out by many flat-bottomed valleys4 ,it appears to the eye quite level1 but in proceeding in a ,s4,s4,w4 course1 towards an escarpment distant about six miles1 and likewise ranging across the country in a ,n4,w4 line1 it was found to rise at first insensibly1 and then for the last half-mile1 sensibly1 close up to the base of the escarpment3 at this point it was #dfc feet in height1 showing a rise of #ajh feet in the six miles4 ,on this #cee-dfc feet plain1 ,i found several shells of ,mytilus ,magellanicus and of a ,mytilus1 which ,mr4 ,sowerby informs me is yet unnamed1 though well-known as recent on this coast2 ,patella deaurita2 ,fusus1 ,i believe1 ,magellanicus1 but the specimen has been lost2 and at the distance of four miles from the coast1 at the height of about four hundred feet1 there were fragments of the same ,patella and of a ,voluta 7apparently ,v4 ancilla7 partially embedded in the superficial sandy earth4 ,all these shells had the same ancient appearance with those from the foregoing localities4 ,as the tides along this part of the coast rise at the ,syzygal period forty feet1 and therefore form a well-marked beach-line1 ,i particularly looked out for ridges in crossing this plain1 which1 as we have seen1 rises #ajh feet in about six miles1 but ,i could not see any traces of such4 ,the next highest plain is #gaj feet above the sea2 it is very narrow1 but level1 and is capped with gravel2 it abuts to the foot of the #hdj feet plain4 ,this summit-plain extends as far as the eye can range1 both inland along the southern side of the valley of the ,santa ,cruz1 and southward along the ,atlantic4 ,,the ,,valley ,,of ,,the ,r4 ,,santa ,,cruz4 ,this valley runs in an east and west direction to the ,cordillera1 a distance of about one hundred and sixty miles4 ,it cuts through the great ,patagonian tertiary formation1 including1 in the upper half of the valley1 immense streams of basaltic lava1 which as well as the softer beds1 are capped by gravel2 and this gravel1 high up the river1 is associated with a vast boulder formation4 7,i have described this formation in a paper in the 8,geological ,transactions0 volume #f page #dae47 ,in ascending the valley1 the plain which at the mouth on the southern side is #cee feet high1 is seen to trend towards the corresponding plain on the northern side1 so that their escarpments appear like the shores of a former estuary1 larger than the existing one3 the escarpments1 also1 of the #hdj feet summit-plain 7with a corresponding northern one1 which is met with some way up the valley71 appear like the shores of a still larger estuary4 ,farther up the valley1 the sides are bounded throughout its entire length by level1 gravel-capped terraces1 rising above each other in steps4 ,the width between the upper escarpments is on an average between seven and ten miles2 in one spot1 however1 where cutting through the basaltic lava1 it was only one mile and a half4 ,between the escarpments of the second highest terrace the average width is about four or five miles4 ,the bottom of the valley1 at the distance of #aaj miles from its mouth1 begins sensibly to expand1 and soon forms a considerable plain1 #ddj feet above the level of the sea1 through which the river flows in a gut from twenty to forty feet in depth4 ,i here found1 at a point #adj miles from the ,atlantic1 and seventy miles from the nearest creek of the ,pacific1 at the height of #daj feet1 a very old and worn shell of ,patella deaurita4 ,lower down the valley1 #aje miles from the ,atlantic 7longitude #ga degrees ,w471 and at an elevation of about #cjj feet1 ,i also found1 in the bed of the river1 two much worn and broken shells of the ,voluta ancilla1 still retaining traces of their colours2 and one of the ,patella deaurita4 ,it appeared that these shells had been washed from the banks into the river2 considering the distance from the sea1 the desert and absolutely unfrequented character of the country1 and the very ancient appearance of the shells 7exactly like those found on the plains nearer the coast71 there is1 ,i think1 no cause to suspect that they could have been brought here by ,indians4 ,the plain at the head of the valley is tolerably level1 but water-worn1 and with many sand-dunes on it like those on a sea-coast4 ,at the highest point to which we ascended1 it was sixteen miles wide in a north and south line2 and forty-five miles in length in an east and west line4 ,it is bordered by the escarpments1 one above the other1 of two plains1 which diverge as they approach the ,cordillera1 and consequently resemble1 at two levels1 the shores of great bays facing the mountains2 and these mountains are breached in front of the lower plain by a remarkable gap4 ,the valley1 therefore1 of the ,santa ,cruz consists of a straight broad cut1 about ninety miles in length1 bordered by gravel-capped terraces and plains1 the escarpments of which at both ends diverge or expand1 one over the other1 after the manner of the shores of great bays4 ,bearing in mind this peculiar form of the land--the sand-dunes on the plain at the head of the valley--the gap in the ,cordillera1 in front of it--the presence in two places of very ancient shells of existing species--and lastly1 the circumstance of the #cee-dec feet plain1 with the numerous marine remains on its surface1 sweeping from the ,atlantic coast1 far up the valley1 ,i think we must admit1 that within the recent period1 the course of the ,santa ,cruz formed a sea-strait intersecting the continent4 ,at this period1 the southern part of ,south ,america consisted of an archipelago of islands #cfj miles in a north and south line4 ,we shall presently see1 that two other straits also1 since closed1 then cut through ,tierra del ,fuego2 ,i may add1 that one of them must at that time have expanded at the foot of the ,cordillera into a great bay 7now ,otway ,water7 like that which formerly covered the #ddj feet plain at the head of the ,santa ,cruz4 7,,diagram #f4 ,,north ,,and ,,south ,,section ,,across ,,the ,,terraces ,,bounding ,,the ,,valley ,,of ,,the ,,river ,,santa ,,cruz1 ,,high ,,up ,,its ,,course4 ,the height of each terrace1 above the level of the river 7furthest to nearest to the river7 in feet3 ,a1 north and south3 #a1abb ,b1 north and south3 #hfi ,c1 north and south3 #fci ,d1 north3 not measured4 ,d1 north8 7suggest south73 #ahe ,e3 #bj ,bed of ,river4 ,vertical scale #a_/bj of inch to #ajj feet2 but terrace ,e1 being only twenty feet above the river1 has necessarily been raised4 ,the horizontal distances much contracted2 the distance from the edge of ,a ,north to ,a ,south being on an average from seven to ten miles47 ,i have said that the valley in its whole course is bordered by gravel- capped plains4 ,the section 7,diagram #f71 supposed to be drawn in a north and south line across the valley1 can scarcely be considered as more than illustrative2 for during our hurried ascent it was impossible to measure all the plains at any one place4 ,at a point nearly midway between the ,cordillera and the ,atlantic1 ,i found the plain 7,a north7 #a1abb feet above the river2 all the lower plains on this side were here united into one great broken cliff3 at a point sixteen miles lower down the stream1 ,i found by measurement and estimation that ,b 7north7 was #hfi above the river3 very near to where ,a 7north7 was measured1 ,c 7north7 was #fci above the same level3 the terrace ,d 7north7 was nowhere measured3 the lowest ,e 7north7 was in many places about twenty feet above the river4 ,these plains or terraces were best developed where the valley was widest2 the whole five1 like gigantic steps1 occurred together only at a few points4 ,the lower terraces are less continuous than the higher ones1 and appear to be entirely lost in the upper third of the valley4 ,terrace ,c 7south71 however was traced continuously for a great distance4 ,the terrace ,b 7north71 at a point fifty- five miles from the mouth of the river1 was four miles in width2 higher up the valley this terrace 7or at least the second highest one1 for ,i could not always trace it continuously7 was about eight miles wide4 ,this second plain was generally wider than the lower ones--as indeed follows from the valley from ,a 7north7 to ,a 7south7 being generally nearly double the width of from ,b 7north7 to ,b 7south74 ,low down the valley1 the summit-plain ,a 7south7 is continuous with the #hdj feet plain on the coast1 but it is soon lost or unites with the escarpment of ,b 7south74 ,the corresponding plain ,a 7north71 on the north side of the valley1 appears to range continuously from the ,cordillera to the head of the present estuary of the ,santa ,cruz1 where it trends northward towards ,port ,st4 ,julian4 ,near the ,cordillera the summit-plain on both sides of the valley is between #c1bjj and #c1cjj feet in height2 at #ajj miles from the ,atlantic1 it is #a1daf feet1 and on the coast #hdj feet1 all above the sea-beach2 so that in a distance of #ajj miles the plain rises #egf feet1 and much more rapidly near to the ,cordillera4 ,the lower terraces ,b and ,c also appear to rise as they run up the valley2 thus ,d 7north71 measured at two points twenty-four miles apart1 was found to have risen #ahe feet4 ,from several reasons ,i suspect1 that this gradual inclination of the plains up the valley1 has been chiefly caused by the elevation of the continent in mass1 having been the greater the nearer to the ,cordillera4 ,all the terraces are capped with well-rounded gravel1 which rests either on the denuded and sometimes furrowed surface of the soft tertiary deposits1 or on the basaltic lava4 ,the difference in height between some of the lower steps or terraces seems to be entirely owing to a difference in the thickness of the capping gravel4 ,furrows and inequalities in the gravel1 where such occur1 are filled up and smoothed over with sandy earth4 ,the pebbles1 especially on the higher plains1 are often whitewashed1 and even cemented together by a white aluminous substance1 and ,i occasionally found this to be the case with the gravel on the terrace ,d4 ,i could not perceive any trace of a similar deposition on the pebbles now thrown up by the river1 and therefore ,i do not think that terrace ,d was river-formed4 ,as the terrace ,e generally stands about twenty feet above the bed of the river1 my first impression was to doubt whether even this lowest one could have been so formed2 but it should always be borne in mind1 that the horizontal upheaval of a district1 by increasing the total descent of the streams1 will always tend to increase1 first near the sea-coast and then further and further up the valley1 their corroding and deepening powers3 so that an alluvial plain1 formed almost on a level with a stream1 will1 after an elevation of this kind1 in time be cut through1 and left standing at a height never again to be reached by the water4 ,with respect to the three upper terraces of the ,santa ,cruz1 ,i think there can be no doubt1 that they were modelled by the sea1 when the valley was occupied by a strait1 in the same manner 7hereafter to be discussed7 as the greater step-formed1 shell- strewed plains along the coast of ,patagonia4 ,to return to the shores of the ,atlantic3 the #hdj feet plain1 at the mouth of the ,santa ,cruz1 is seen extending horizontally far to the south2 and ,i am informed by the ,officers of the ,survey1 that bending round the head of ,coy ,inlet 7sixty-five miles southward71 it trends inland4 ,outliers of apparently the same height are seen forty miles farther south1 inland of the river ,gallegos2 and a plain comes down to ,cape ,gregory 7thirty-five miles southward71 in the ,strait of ,magellan1 which was estimated at between eight hundred and one thousand feet in height1 and which1 rising towards the interior1 is capped by the boulder formation4 ,south of the ,strait of ,magellan1 there are large outlying masses of apparently the same great tableland1 extending at intervals along the eastern coast of ,tierra del ,fuego3 at two places here1 #aaj miles a part1 this plain was found to be #iej and #igj feet in height4 ,from ,coy ,inlet1 where the high summit-plain trends inland1 a plain estimated at #cej feet in height1 extends for forty miles to the river ,gallegos4 ,from this point to the ,strait of ,magellan1 and on each side of that ,strait1 the country has been much denuded and is less level4 ,it consists chiefly of the boulder formation1 which rises to a height of between one hundred and fifty and two hundred and fifty feet1 and is often capped by beds of gravel4 ,at ,n4,s4 ,gracia1 on the north side of the ,inner ,narrows of the ,strait of ,magellan1 ,i found on the summit of a cliff1 #afj feet in height1 shells of existing ,patellae and ,mytili1 scattered on the surface and partially embedded in earth4 ,on the eastern coast1 also1 of ,tierra del ,fuego1 in latitude #ec degrees #bj south1 ,i found many ,mytili on some level land1 estimated at #bjj feet in height4 ,anterior to the elevation attested by these shells1 it is evident by the present form of the land1 and by the distribution of the great erratic boulders on the surface1 that two sea-channels connected the ,strait of ,magellan both with ,sebastian ,bay and with ,otway ,water4 78,geological ,transactions0 volume #f page #dai47 ,,concluding ,,remarks ,,on ,,the ,,recent ,,elevation ,,of ,,the ,,south-,,eastern ,,coasts ,,of ,,america1 ,,and ,,on ,,the ,,action ,,of ,,the ,,sea ,,on ,,the ,,land4 ,upraised shells of species1 still existing as the commonest kinds in the adjoining sea1 occur1 as we have seen1 at heights of between a few feet and #daj feet1 at intervals from latitude #cc degrees #dj to #ec degrees #bj south4 ,this is a distance of #a1ahj geographical miles--about equal from ,london to the ,north ,cape of ,sweden4 ,as the boulder formation extends with nearly the same height #aej miles south of #ec degrees #bj1 the most southern point where ,i landed and found upraised shells2 and as the level ,pampas ranges many hundred miles northward of the point1 where ,m4 d',orbigny found at the height of #ajj feet beds of the ,azara1 the space in a north and south line1 which has been uplifted within the recent period1 must have been much above the #a1ahj miles4 ,by the term 8recent10 ,i refer only to that period within which the now living mollusca were called into existence2 for it will be seen in the ,fourth ,chapter1 that both at ,bahia ,blanca and ,p4 ,s4 ,julian1 the mammiferous quadrupeds which co-existed with these shells belong to extinct species4 ,i have said that the upraised shells were found only at intervals on this line of coast1 but this in all probability may be attributed to my not having landed at the intermediate points2 for wherever ,i did land1 with the exception of the river ,negro1 shells were found3 moreover1 the shells are strewed on plains or terraces1 which1 as we shall immediately see1 extend for great distances with a uniform height4 ,i ascended the higher plains only in a few places1 owing to the distance at which their escarpments generally range from the coast1 so that ,i am far from knowing that #daj feet is the maximum of elevation of these upraised remains4 ,the shells are those now most abundant in a living state in the adjoining sea4 7,captain ,king 8,voyages of #8,adventure' and #8,beagle'0 volume #a pages #f and #acc47 ,all of them have an ancient appearance2 but some1 especially the mussels1 although lying fully exposed to the weather1 retain to a considerable extent their colours3 this circumstance appears at first surprising1 but it is now known that the colouring principle of the ,mytilus is so enduring1 that it is preserved when the shell itself is completely disintegrated4 7,see ,mr4 ,lyell 8,proofs of a ,gradual ,rising in ,sweden0 in the 8,philosophical ,transactions0 #ahce page #a4 ,see also ,mr4 ,smith of ,jordan ,hill in the 8,edinburgh ,new ,philosophical ,journal0 volume #be page #cic47 ,most of the shells are broken2 ,i nowhere found two valves united2 the fragments are not rounded1 at least in none of the specimens which ,i brought home4 ,with respect to the breadth of the upraised area in an east and west line1 we know from the shells found at the ,inner ,narrows of the ,strait of ,magellan1 that the entire width of the plain1 although there very narrow1 has been elevated4 ,it is probable that in this southernmost part of the continent1 the movement has extended under the sea far eastward2 for at the ,falkland ,islands1 though ,i could not find any shells1 the bones of whales have been noticed by several competent observers1 lying on the land at a considerable distance from the sea1 and at the height of some hundred feet above it4 78,voyages of the #8,adventure' and #8,beagle'0 volume #b page #bbg4 ,and ,bougainville's 8,voyage0 tome #a page #aab47 ,moreover1 we know that in ,tierra del ,fuego the boulder formation has been uplifted within the recent period1 and a similar formation occurs on the north-western shores 7,byron ,sound7 of these islands4 7,i owe this fact to the kindness of ,captain ,sulivan1 ,r4,n41 a highly competent observer4 ,i mention it more especially1 as in my ,paper 7page #dbg7 on the ,boulder ,formation1 ,i have1 after having examined the northern and middle parts of the eastern island1 said that the formation was here wholly absent47 ,the distance from this point to the ,cordillera of ,tierra del ,fuego1 is #cfj miles1 which we may take as the probable width of the recently upraised area4 ,in the latitude of the ,r4 ,santa ,cruz1 we know from the shells found at the mouth and head1 and in the middle of the valley1 that the entire width 7about #afj miles7 of the surface eastward of the ,cordillera has been upraised4 ,from the slope of the plains1 as shown by the course of the rivers1 for several degrees northward of the ,santa ,cruz1 it is probable that the elevation attested by the shells on the coast has likewise extended to the ,cordillera4 ,when1 however1 we look as far northward as the provinces of ,la ,plata1 this conclusion would be very hazardous2 not only is the distance from ,maldonado 7where ,i found upraised shells7 to the ,cordillera great1 namely1 #gfj miles1 but at the head of the estuary of the ,plata1 a ,n4,n4,e4 and ,s4,s4,w4 range of tertiary volcanic rocks has been observed 7,this volcanic formation will be described in ,chapter ,,iv4 ,it is not improbable that the height of the upraised shells at the head of the estuary of the ,plata1 being greater than at ,bahia ,blanca or at ,san ,blas1 may be owing to the upheaval of these latter places having been connected with the distant line of the ,cordillera1 whilst that of the provinces of ,la ,plata was in connection with the adjoining tertiary volcanic axis471 which may well indicate an axis of elevation quite distinct from that of the ,andes4 ,moreover1 in the centre of the ,pampas in the chain of ,cordova1 severe earthquakes have been felt 7,see ,sir ,w4 ,parish's work on 8,la ,plata0 page #bdb4 ,for a notice of an earthquake which drained a lake near ,cordova1 see also ,temple's 8,travels in ,peru40 ,sir ,w4 ,parish informs me1 that a town between ,salta and ,tucuman 7north of ,cordova7 was formerly utterly overthrown by an earthquake472 whereas at ,mendoza1 at the eastern foot of the ,cordillera1 only gentle oscillations1 transmitted from the shores of the ,pacific1 have ever been experienced4 ,hence the elevation of the ,pampas may be due to several distinct axes of movement2 and we cannot judge1 from the upraised shells round the estuary of the ,plata1 of the breadth of the area uplifted within the recent period4 ,not only has the above specified long range of coast been elevated within the recent period1 but ,i think it may be safely inferred from the similarity in height of the gravel-capped plains at distant points1 that there has been a remarkable degree of equability in the elevatory process4 ,i may premise1 that when ,i measured the plains1 it was simply to ascertain the heights at which shells occurred2 afterwards1 comparing these measurements with some of those made during the ,survey1 ,i was struck with their uniformity1 and accordingly tabulated all those which represented the summit-edges of plains4 ,the extension of the #ccj to #cee feet plain is very striking1 being found over a space of #ejj geographical miles in a north and south line4 ,a table 7,table #a7 of the measurements is given below4 ,the angular measurements and all the estimations 7in feet7 are by the ,officers of the ,survey2 the barometrical ones by myself3-- ,,table #a4 ,gallegos ,river to ,coy ,inlet 7partly angular partly estimation7 #cej ,south ,side of ,santa ,cruz 7angular and barometric7 #cee ,north ,side of ,santa ,cruz 7angular and barometric7 #ccj ,bird ,island1 plain opposite to 7angular7 #cej ,port ,desire1 plain extending far along coast 7barometric7 #ccj ,st4 ,george's ,bay1 north promontory 7angular7 #ccj ,table ,land1 south of ,new ,bay 7angular7 #cej ,a plain1 varying from #bde to #bee feet1 seems to extend with much uniformity from ,port ,desire to the north of ,st4 ,george's ,bay1 a distance of #agj miles2 and some approximate measurements 7in feet71 also given in ,table #b below1 indicate the much greater extension of #ghj miles3-- ,,table #b4 ,coy ,inlet1 south of 7partly angular and partly estimation7 #bjj to #cjj ,port ,desire 7barometric7 #bde to #bee ,c4 ,blanco 7angular7 #bej ,north ,promontory of ,st4 ,george's ,bay 7angular7 #bej ,south of ,new ,bay 7angular7 #bjj to #bbj ,north of ,s4 ,josef 7estimation7 #bjj to #cjj ,plain of ,rio ,negro 7angular7 #bjj to #bbj ,bahia ,blanca 7estimation7 #bjj to #cjj ,the extension1 moreover1 of the #efj to #ehj1 and of the #hj to #ajj feet1 plains is remarkable1 though somewhat less obvious than in the former cases4 ,bearing in mind that ,i have not picked these measurements out of a series1 but have used all those which represented the edges of plains1 ,i think it scarcely possible that these coincidences in height should be accidental4 ,we must therefore conclude that the action1 whatever it may have been1 by which these plains have been modelled into their present forms1 has been singularly uniform4 ,these plains or great terraces1 of which three and four often rise like steps one behind the other1 are formed by the denudation of the old ,patagonian tertiary beds1 and by the deposition on their surfaces of a mass of well-rounded gravel1 varying1 near the coast1 from ten to thirty-five feet in thickness1 but increasing in thickness towards the interior4 ,the gravel is often capped by a thin irregular bed of sandy earth4 ,the plains slope up1 though seldom sensibly to the eye1 from the summit edge of one escarpment to the foot of the next highest one4 ,within a distance of #aej miles1 between ,santa ,cruz to ,port ,desire1 where the plains are particularly well developed1 there are at least seven stages or steps1 one above the other4 ,on the three lower ones1 namely1 those of #ajj feet1 #bej feet1 and #cej feet in height1 existing littoral shells are abundantly strewed1 either on the surface1 or partially embedded in the superficial sandy earth4 ,by whatever action these three lower plains have been modelled1 so undoubtedly have all the higher ones1 up to a height of #iej feet at ,s4 ,julian1 and of #a1bjj feet 7by estimation7 along ,st4 ,george's ,bay4 ,i think it will not be disputed1 considering the presence of the upraised marine shells1 that the sea has been the active power during stages of some kind in the elevatory process4 ,we will now briefly consider this subject3 if we look at the existing coast-line1 the evidence of the great denuding power of the sea is very distinct2 for1 from ,cape ,st4 ,diego1 in latitude #ed degrees #cj to the mouth of the ,rio ,negro1 in latitude #ca degrees 7a length of more than eight hundred miles71 the shore is formed1 with singularly few exceptions1 of bold and naked cliffs3 in many places the cliffs are high2 thus1 south of the ,santa ,cruz1 they are between eight and nine hundred feet in height1 with their horizontal strata abruptly cut off1 showing the immense mass of matter which has been removed4 ,nearly this whole line of coast consists of a series of greater or lesser curves1 the horns of which1 and likewise certain straight projecting portions1 are formed of hard rocks2 hence the concave parts are evidently the effect and the measure of the denuding action on the softer strata4 ,at the foot of all the cliffs1 the sea shoals very gradually far outwards2 and the bottom1 for a space of some miles1 everywhere consists of gravel4 ,i carefully examined the bed of the sea off the ,santa ,cruz1 and found that its inclination was exactly the same1 both in amount and in its peculiar curvature1 with that of the #cee feet plain at this same place4 ,if1 therefore1 the coast1 with the bed of the adjoining sea1 were now suddenly elevated one or two hundred feet1 an inland line of cliffs1 that is an escarpment1 would be formed1 with a gravel-capped plain at its foot gently sloping to the sea1 and having an inclination like that of the existing #cee feet plain4 ,from the denuding tendency of the sea1 this newly formed plain would in time be eaten back into a cliff3 and repetitions of this elevatory and denuding process would produce a series of gravel-capped sloping terraces1 rising one above another1 like those fronting the shores of ,patagonia4 ,the chief difficulty 7for there are other inconsiderable ones7 on this view1 is the fact1--as far as ,i can trust two continuous lines of soundings carefully taken between ,santa ,cruz and the ,falkland ,islands1 and several scattered observations on this and other coasts1--that the pebbles at the bottom of the sea ,,quickly and ,,regularly decrease in size with the increasing depth and distance from the shore1 whereas in the gravel on the sloping plains1 no such decrease in size was perceptible4 ,table #c below gives the average result of many soundings off the ,santa ,cruz3-- ,,table #c4 ,under two miles from the shore1 many of the pebbles were of large size1 mingled with some small ones4 ,column #a4 ,distance in miles from the shore4 ,column #b4 ,depth in fathoms4 ,column #c4 ,size of ,pebbles4 ,i particularly attended to the size of the pebbles on the #cee feet ,santa ,cruz plain1 and ,i noticed that on the summit-edge of the present sea cliffs many were as large as half a man's head2 and in crossing from these cliffs to the foot of the next highest escarpment1 a distance of six miles1 ,i could not observe any increase in their size4 ,we shall presently see that the theory of a slow and almost insensible rise of the land1 will explain all the facts connected with the gravel-capped terraces1 better than the theory of sudden elevations of from one to two hundred feet4 ,m4 d',orbigny has argued1 from the upraised shells at ,san ,blas being embedded in the positions in which they lived1 and from the valves of the ,azara labiata high on the banks of the ,parana being united and unrolled1 that the elevation of ,northern ,patagonia and of ,la ,plata must have been sudden2 for he thinks1 if it had been gradual1 these shells would all have been rolled on successive beach-lines4 ,but in ,,protected bays1 such as in that of ,bahia ,blanca1 wherever the sea is accumulating extensive mud-banks1 or where the winds quietly heap up sand-dunes1 beds of shells might assuredly be preserved buried in the positions in which they had lived1 even whilst the land retained the same level2 any1 the smallest1 amount of elevation would directly aid in their preservation4 ,i saw a multitude of spots in ,bahia ,blanca where this might have been effected2 and at ,maldonado it almost certainly has been effected4 ,in speaking of the elevation of the land having been slow1 ,i do not wish to exclude the small starts which accompany earthquakes1 as on the coast of ,chile2 and by such movements beds of shells might easily be uplifted1 even in positions exposed to a heavy surf1 without undergoing any attrition3 for instance1 in #ahce1 a rocky flat off the island of ,santa ,maria was at one blow upheaved above high-water mark1 and was left covered with gaping and putrefying mussel-shells1 still attached to the bed on which they had lived4 ,if ,m4 d',orbigny had been aware of the many long parallel lines of sand-hillocks1 with infinitely numerous shells of the ,mactra and ,venus1 at a low level near the ,uruguay2 if he had seen at ,bahia ,blanca the immense sand-dunes1 with water-worn pebbles of pumice1 ranging in parallel lines1 one behind the other1 up a height of at least #abj feet2 if he had seen the sand-dunes1 with the countless ,paludestrinas1 on the low plain near the ,fort at this place1 and that long line on the edge of the cliff1 sixty feet higher up2 if he had crossed that long and great belt of parallel sand-dunes1 eight miles in width1 standing at the height of from forty to fifty feet above the ,colorado1 where sand could not now collect1--,i cannot believe he would have thought that the elevation of this great district had been sudden4 ,certainly the sand-dunes 7especially when abounding with shells71 which stand in ranges at so many different levels1 must all have required long time for their accumulation2 and hence ,i do not doubt that the last #ajj feet of elevation of ,la ,plata and ,northern ,patagonia has been exceedingly slow4 ,if we extend this conclusion to ,central and ,southern ,patagonia1 the inclination of the successively rising gravel-capped plains can be explained quite as well1 as by the more obvious view already given of a few comparatively great and sudden elevations2 in either case we must admit long periods of rest1 during which the sea ate deeply into the land4 ,let us suppose the present coast to rise at a nearly equable1 slow rate1 yet sufficiently quick to prevent the waves quite removing each part as soon as brought up2 in this case every portion of the present bed of the sea will successively form a beach-line1 and from being exposed to a like action will be similarly affected4 ,it cannot matter to what height the tides rise1 even if to forty feet as at ,santa ,cruz1 for they will act with equal force and in like manner on each successive line4 ,hence there is no difficulty in the fact of the #cee feet plain at ,santa ,cruz sloping up #ajh feet to the foot of the next highest escarpment1 and yet having no marks of any one particular beach-line on it2 for the whole surface on this view has been a beach4 ,i cannot pretend to follow out the precise action of the tidal-waves during a rise of the land1 slow1 yet sufficiently quick to prevent or check denudation3 but if it be analogous to what takes place on protected parts of the present coast1 where gravel is now accumulating in large quantities1 an inclined surface1 thickly capped by well-rounded pebbles of about the same size1 would be ultimately left4 7,on the eastern side of ,chiloe1 which island we shall see in the next chapter is now rising1 ,i observed that all the beaches and extensive tidal-flats were formed of shingle47 ,on the gravel now accumulating1 the waves1 aided by the wind1 sometimes throw up a thin covering of sand1 together with the common coast-shells4 ,shells thus cast up by gales1 would1 during an elevatory period1 never again be touched by the sea4 ,hence1 on this view of a slow and gradual rising of the land1 interrupted by periods of rest and denudation1 we can understand the pebbles being of about the same size over the entire width of the step-like plains1--the occasional thin covering of sandy earth1--and the presence of broken1 unrolled fragments of those shells1 which now live exclusively near the coast4 ,a ,,summary ,,of ,,results4 ,it may be concluded that the coast on this side of the continent1 for a space of at least #a1ahj miles1 has been elevated to a height of #ajj feet in ,la ,plata1 and of #djj feet in ,southern ,patagonia1 within the period of existing shells1 but not of existing mammifers4 ,that in ,la ,plata the elevation has been very slowly effected3 that in ,patagonia the movement may have been by considerable starts1 but much more probably slow and quiet4 ,in either case1 there have been long intervening periods of comparative rest1 during which the sea corroded deeply1 as it is still corroding1 into the land4 7,i say ,,comparative and not ,,absolute rest1 because the sea acts1 as we have seen1 with great denuding power on this whole line of coast2 and therefore1 during an elevation of the land1 if excessively slow 7and of course during a subsidence of the land71 it is quite possible that lines of cliff might be formed47 ,that the periods of denudation and elevation were contemporaneous and equable over great spaces of coast1 as shown by the equable heights of the plains2 that there have been at least eight periods of denudation1 and that the land1 up to a height of from #iej to #a1bjj feet1 has been similarly modelled and affected3 that the area elevated1 in the southernmost part of the continent1 extended in breadth to the ,cordillera1 and probably seaward to the ,falkland ,islands2 that northward1 in ,la ,plata1 the breadth is unknown1 there having been probably more than one axis of elevation2 and finally1 that1 anterior to the elevation attested by these upraised shells1 the land was divided by a ,strait where the ,river ,santa ,cruz now flows1 and that further southward there were other sea-straits1 since closed4 ,i may add1 that at ,santa ,cruz1 in latitude #ej degrees ,s41 the plains have been uplifted at least #a1djj feet1 since the period when gigantic boulders were transported between sixty and seventy miles from their parent rock1 on floating icebergs4 ,lastly1 considering the great upward movements which this long line of coast has undergone1 and the proximity of its southern half to the volcanic axis of the ,cordillera1 it is highly remarkable that in the many fine sections exposed in the ,pampean1 ,patagonian tertiary1 and ,boulder formations1 ,i nowhere observed the smallest fault or abrupt curvature in the strata4 ,,gravel ,,formation ,,of ,,patagonia4 ,i will here describe in more detail than has been as yet incidentally done1 the nature1 origin1 and extent of the great shingle covering of ,patagonia3 but ,i do not mean to affirm that all of this shingle1 especially that on the higher plains1 belongs to the recent period4 ,a thin bed of sandy earth1 with small pebbles of various porphyries and of quartz1 covering a low plain on the north side of the ,rio ,colorado1 is the extreme northern limit of this formation4 ,these little pebbles have probably been derived from the denudation of a more regular bed of gravel1 capping the old tertiary sandstone plateau of the ,rio ,negro4 ,the gravel-bed near the ,rio ,negro is1 on an average1 about ten or twelve feet in thickness2 and the pebbles are larger than on the northern side of the ,colorado1 being from one or two inches in diameter1 and composed chiefly of rather dark-tinted porphyries4 ,amongst them ,i here first noticed a variety often to be referred to1 namely1 a peculiar gallstone-yellow siliceous porphyry1 frequently1 but not invariably1 containing grains of quartz4 ,the pebbles are embedded in a white1 gritty1 calcareous matrix1 very like mortar1 sometimes merely coating with a whitewash the separate stones1 and sometimes forming the greater part of the mass4 ,in one place ,i saw in the gravel concretionary nodules 7not rounded7 of crystallised gypsum1 some as large as a man's head4 ,i traced this bed for forty-five miles inland1 and was assured that it extended far into the interior4 ,as the surface of the calcareo- argillaceous plain of ,pampean formation1 on the northern side of the wide valley of the ,colorado1 stands at about the same height with the mortar- like cemented gravel capping the sandstone on the southern side1 it is probable1 considering the apparent equability of the subterranean movements along this side of ,america1 that this gravel of the ,rio ,negro and the upper beds of the ,pampean formation northward of the ,colorado1 are of nearly contemporaneous origin1 and that the calcareous matter has been derived from the same source4 ,southward of the ,rio ,negro1 the cliffs along the great bay of ,s4 ,antonio are capped with gravel3 at ,san ,josef1 ,i found that the pebbles closely resembled those on the plain of the ,rio ,negro1 but that they were not cemented by calcareous matter4 ,between ,san ,josef and ,port ,desire1 ,i was assured by the ,officers of the ,survey that the whole face of the country is coated with gravel4 ,at ,port ,desire and over a space of twenty-five miles inland1 on the three step-formed plains and in the valleys1 ,i everywhere passed over gravel which1 where thickest1 was between thirty and forty feet4 ,here1 as in other parts of ,patagonia1 the gravel1 or its sandy covering1 was1 as we have seen1 often strewed with recent marine shells4 ,the sandy covering sometimes fills up furrows in the gravel1 as does the gravel in the underlying tertiary formations4 ,the pebbles are frequently whitewashed and even cemented together by a peculiar1 white1 friable1 aluminous1 fusible substance1 which ,i believe is decomposed feldspar4 ,at ,port ,desire1 the gravel rested sometimes on the basal formation of porphyry1 and sometimes on the upper or the lower denuded tertiary strata4 ,it is remarkable that most of the porphyritic pebbles differ from those varieties of porphyry which occur here abundantly in situ4 ,the peculiar gallstone-yellow variety was common1 but less numerous than at ,port ,s4 ,julian1 where it formed nearly one-third of the mass of the gravel2 the remaining part there consisting of pale grey and greenish porphyries with many crystals of feldspar4 ,at ,port ,s4 ,julian1 ,i ascended one of the flat- topped hills1 the denuded remnant of the highest plain1 and found it1 at the height of #iej feet1 capped with the usual bed of gravel4 ,near the mouth of the ,santa ,cruz1 the bed of gravel on the #cee feet plain is from twenty to about thirty-five feet in thickness4 ,the pebbles vary from minute ones to the size of a hen's egg1 and even to that of half a man's head2 they consist of paler varieties of porphyry than those found further northward1 and there are fewer of the gallstone-yellow kind2 pebbles of compact black clay-slate were here first observed4 ,the gravel1 as we have seen1 covers the step-formed plains at the mouth1 head1 and on the sides of the great valley of the ,santa ,cruz4 ,at a distance of #aaj miles from the coast1 the plain has risen to the height of #a1daf feet above the sea2 and the gravel1 with the associated great boulder formation1 has attained a thickness of #bab feet4 ,the plain1 apparently with its usual gravel covering1 slopes up to the foot of the ,cordillera to the height of between #c1bjj and #c1cjj feet4 ,in ascending the valley1 the gravel gradually becomes entirely altered in character3 high up1 we have pebbles of crystalline feldspathic rocks1 compact clay-slate1 quartzose schists1 and pale-coloured porphyries2 these rocks1 judging both from the gigantic boulders in the surface and from some small pebbles embedded beneath #gjj feet in thickness of the old tertiary strata1 are the prevailing kinds in this part of the ,cordillera2 pebbles of basalt from the neighbouring streams of basaltic lava are also numerous2 there are few or none of the reddish or of the gallstone-yellow porphyries so common near the coast4 ,hence the pebbles on the #cej feet plain at the mouth of the ,santa ,cruz cannot have been derived 7with the exception of those of compact clay- slate1 which1 however1 may equally well have come from the south7 from the ,cordillera in this latitude2 but probably1 in chief part1 from farther north4 ,southward of the ,santa ,cruz1 the gravel may be seen continuously capping the great #hdj feet plain3 at the ,rio ,gallegos1 where this plain is succeeded by a lower one1 there is1 as ,i am informed by ,captain ,sulivan1 an irregular covering of gravel from ten to twelve feet in thickness over the whole country4 ,the district on each side of the ,strait of ,magellan is covered up either with gravel or the boulder formation3 it was interesting to observe the marked difference between the perfectly rounded state of the pebbles in the great shingle formation of ,patagonia1 and the more or less angular fragments in the boulder formation4 ,the pebbles and fragments near the ,strait of ,magellan nearly all belong to rocks known to occur in ,fuegia4 ,i was therefore much surprised in dredging south of the ,strait to find1 in latitude #ed degrees #aj south1 many pebbles of the gallstone-yellow siliceous porphyry2 ,i procured others from a great depth off ,staten ,island1 and others were brought me from the western extremity of the ,falkland ,islands4 7,at my request1 ,mr4 ,kent collected for me a bag of pebbles from the beach of ,white ,rock harbour1 in the northern part of the sound1 between the two ,falkland ,islands4 ,out of these well-rounded pebbles1 varying in size from a walnut to a hen's egg1 with some larger1 thirty-eight evidently belonged to the rocks of these islands2 twenty-six were similar to the pebbles of porphyry found on the ,patagonian plains1 which rocks do not exist in situ in the ,falklands2 one pebble belonged to the peculiar yellow siliceous porphyry2 thirty were of doubtful origin47 ,the distribution of the pebbles of this peculiar porphyry1 which ,i venture to affirm is not found in situ either in ,fuegia1 the ,falkland ,islands1 or on the coast of ,patagonia1 is very remarkable1 for they are found over a space of #hdj miles in a north and south line1 and at the ,falklands1 #cjj miles eastward of the coast of ,patagonia4 ,their occurrence in ,fuegia and the ,falklands may1 however1 perhaps be due to the same ice-agency by which the boulders have been there transported4 ,we have seen that porphyritic pebbles of a small size are first met with on the northern side of the ,rio ,colorado1 the bed becoming well developed near the ,rio ,negro3 from this latter point ,i have every reason to believe that the gravel extends uninterruptedly over the plains and valleys of ,patagonia for at least #fcj nautical miles southward to the ,rio ,gallegos4 ,from the slope of the plains1 from the nature of the pebbles1 from their extension at the ,rio ,negro far into the interior1 and at the ,santa ,cruz close up to the ,cordillera1 ,i think it highly probable that the whole breadth of ,patagonia is thus covered4 ,if so1 the average width of the bed must be about two hundred miles4 ,near the coast the gravel is generally from ten to thirty feet in thickness2 and as in the valley of ,santa ,cruz it attains1 at some distance from the ,cordillera1 a thickness of #bad feet1 we may1 ,i think1 safely assume its average thickness over the whole area of #fcj by #bjj miles1 at fifty feet6 ,the transportal and origin of this vast bed of pebbles is an interesting problem4 ,from the manner in which they cap the step-formed plains1 worn by the sea within the period of existing shells1 their deposition1 at least on the plains up to a height of #djj feet1 must have been a recent geological event4 ,from the form of the continent1 we may feel sure that they have come from the westward1 probably1 in chief part from the ,cordillera1 but1 perhaps1 partly from unknown rocky ridges in the central districts of ,patagonia4 ,that the pebbles have not been transported by rivers1 from the interior towards the coast1 we may conclude from the fewness and smallness of the streams of ,patagonia3 moreover1 in the case of the one great and rapid river of ,santa ,cruz1 we have good evidence that its transporting power is very trifling4 ,this river is from two to three hundred yards in width1 about seventeen feet deep in its middle1 and runs with a singular degree of uniformity five knots an hour1 with no lakes and scarcely any still reaches3 nevertheless1 to give one instance of its small transporting power1 upon careful examination1 pebbles of compact basalt could not be found in the bed of the river at a greater distance than ten miles below the point where the stream rushes over the debris of the great basaltic cliffs forming its shore3 fragments of the ,,cellular varieties have been washed down twice or thrice as far4 ,that the pebbles in ,central and ,northern ,patagonia have not been transported by ice-agency1 as seems to have been the case to a considerable extent farther south1 and likewise in the northern hemisphere1 we may conclude1 from the absence of all angular fragments in the gravel1 and from the complete contrast in many other respects between the shingle and neighbouring boulder formation4 ,looking to the gravel on any one of the step-formed plains1 ,i cannot doubt1 from the several reasons assigned in this chapter1 that it has been spread out and leveled by the long-continued action of the sea1 probably during the slow rise of the land4 ,the smooth and perfectly rounded condition of the innumerable pebbles alone would prove long-continued action4 ,but how the whole mass of shingle on the coast-plains has been transported from the mountains of the interior1 is another and more difficult question4 ,the following considerations1 however1 show that the sea by its ordinary action has considerable power in distributing pebbles4 ,table #c above shows how very uniformly and gradually the pebbles decrease in size with the gradually seaward increasing depth and distance4 7,i may mention1 that at the distance of #aej miles from the ,patagonian shore ,i carefully examined the minute rounded particles in the sand1 and found them to be fusible like the porphyries of the great shingle bed4 ,i could even distinguish particles of the gallstone-yellow porphyry4 ,it was interesting to notice how gradually the particles of white quartz increased1 as we approached the ,falkland ,islands1 which are thus constituted4 ,in the whole line of soundings between these islands and the coast of ,patagonia dead or living organic remains were most rare4 ,on the relations between the depth of water and the nature of the bottom1 see ,martin ,white on 8,soundings in the ,channel0 pages #d1 #f1 #age2 also ,captain ,beechey's 8,voyage to the ,pacific0 chapter #ah47 ,a series of this kind irresistibly leads to the conclusion1 that the sea has the power of sifting and distributing the loose matter on its bottom4 ,according to ,martin ,white1 the bed of the ,british ,channel is disturbed during gales at depths of sixty-three and sixty-seven fathoms1 and at thirty fathoms1 shingle and fragments of shells are often deposited1 afterwards to be carried away again4 78,soundings in the ,channel0 pages #d1 #aff4 ,m4 ,siau states 78,edinburgh ,new ,philosophical ,journal0 volume #ca page #bdf71 that he found the sediment1 at a depth of #ahh metres1 arranged in ripples of different degrees of fineness4 ,there are some excellent discussions on this and allied subjects in ,sir ,h4 ,de la ,beche's 8,theoretical ,researches407 ,groundswells1 which are believed to be caused by distant gales1 seem especially to affect the bottom3 at such times1 according to ,sir ,r4 ,schomburgk1 the sea to a great distance round the ,west ,indian ,islands1 at depths from five to fifteen fathoms1 becomes discoloured1 and even the anchors of vessels have been moved4 78,journal of ,royal ,geographical ,society0 volume #e page #be4 ,it appears from ,mr4 ,scott ,russell's investigations 7see ,mr4 ,murchison's 8,anniversary ,address ,geological ,society0 #ahdc page #dj71 that in waves of translation the motion of the particles of water is nearly as great at the bottom as at the top47 ,there are1 however1 some difficulties in understanding how the sea can transport pebbles lying at the bottom1 for1 from experiments instituted on the power of running water1 it would appear that the currents of the sea have not sufficient velocity to move stones of even moderate size3 moreover1 ,i have repeatedly found in the most exposed situations that the pebbles which lie at the bottom are encrusted with full-grown living corallines1 furnished with the most delicate1 yet unbroken spines3 for instance1 in ten fathoms water off the mouth of the ,santa ,cruz1 many pebbles1 under half an inch in diameter1 were thus coated with ,flustracean zoophytes4 7,a pebble1 one and a half inch square and half an inch thick1 was given me1 dredged up from twenty-seven fathoms depth off the western end of the ,falkland ,islands1 where the sea is remarkably stormy1 and subject to violent tides4 ,this pebble was encrusted on all sides by a delicate living coralline4 ,i have seen many pebbles from depths between forty and seventy fathoms thus encrusted2 one from the latter depth off ,cape ,horn47 ,hence we must conclude that these pebbles are not often violently disturbed3 it should1 however1 be borne in mind that the growth of corallines is rapid4 ,the view1 propounded by ,professor ,playfair1 will1 ,i believe1 explain this apparent difficulty1--namely1 that from the undulations of the sea ,,tending to lift up and down pebbles or other loose bodies at the bottom1 such are liable1 when thus quite or partially raised1 to be moved even by a very small force1 a little onwards4 ,we can thus understand how oceanic or tidal currents of no great strength1 or that recoil movement of the bottom-water near the land1 called by sailors the 8undertow0 7which ,i presume must extend out seaward as far as the ,,breaking waves impel the surface-water towards the beach71 may gain the power during storms of sifting and distributing pebbles even of considerable size1 and yet without so violently disturbing them as to injure the encrusting corallines4 7,i may take this opportunity of remarking on a singular1 but very common character in the form of the bottom1 in the creeks which deeply penetrate the western shores of ,tierra del ,fuego2 namely1 that they are almost invariably much shallower close to the open sea at their mouths than inland4 ,thus1 ,cook1 in entering ,christmas ,sound1 first had soundings in thirty-seven fathoms1 then in fifty1 then in sixty1 and a little farther in no bottom with #agj fathoms4 ,the sealers are so familiar with this fact1 that they always look out for anchorage near the entrances of the creeks4 ,see1 also1 on this subject1 the 8,voyages of the #8,adventure' and #8,beagle'0 volume #a page #cge and 8,appendix0 page #cac4 ,this ,shoalness of the sea- channels near their entrances probably results from the quantity of sediment formed by the wear and tear of the outer rocks exposed to the full force of the open sea4 ,i have no doubt that many lakes1 for instance in ,scotland1 which are very deep within1 and are separated from the sea apparently only by a tract of detritus1 were originally sea-channels with banks of this nature near their mouths1 which have since been upheaved47 ,the sea acts in another and distinct manner in the distribution of pebbles1 namely by the waves on the beach4 ,mr4 ,palmer1 in his excellent memoir on this subject1 has shown that vast masses of shingle travel with surprising quickness along lines of coast1 according to the direction with which the waves break on the beach and that this is determined by the prevailing direction of the winds4 78,philosophical ,transactions0 #ahcd page #egf47 ,this agency must be powerful in mingling together and disseminating pebbles derived from different sources3 we may1 perhaps1 thus understand the wide distribution of the gallstone-yellow porphyry2 and likewise1 perhaps1 the great difference in the nature of the pebbles at the mouth of the ,santa ,cruz from those in the same latitude at the head of the valley4 ,i will not pretend to assign to these several and complicated agencies their shares in the distribution of the ,patagonian shingle3 but from the several considerations given in this chapter1 and ,i may add1 from the frequency of a capping of gravel on tertiary deposits in all parts of the world1 as ,i have myself observed and seen stated in the works of various authors1 ,i cannot doubt that the power of widely dispersing gravel is an ordinary contingent on the action of the sea2 and that even in the case of the great ,patagonian shingle-bed we have no occasion to call in the aid of debacles4 ,i at one time imagined that perhaps an immense accumulation of shingle had originally been collected at the foot of the ,cordillera2 and that this accumulation1 when upraised above the level of the sea1 had been eaten into and partially spread out 7as off the present line of coast72 and that the newly-spread out bed had in its turn been upraised1 eaten into1 and re-spread out2 and so onwards1 until the shingle1 which was first accumulated in great thickness at the foot of the ,cordillera1 had reached in thinner beds its present extension4 ,by whatever means the gravel formation of ,patagonia may have been distributed1 the vastness of its area1 its thickness1 its superficial position1 its recent origin1 and the great degree of similarity in the nature of its pebbles1 all appear to me well deserving the attention of geologists1 in relation to the origin of the widely-spread beds of conglomerate belonging to past epochs4 ,,formation ,,of ,,cliffs4 7,,diagram #g4--,,section ,,of ,,coast-,,cliffs ,,and ,,bottom ,,of ,,sea1 ,,off ,,the ,,island ,,of ,,st4 ,,helena4 ,height in feet above sea level4 ,depths in fathoms4 ,vertical and horizontal scale1 two inches to a nautical mile4 ,the point marked #a1fjj feet is at the foot of ,high ,knoll2 point marked #eaj feet is on the edge of ,ladder ,hill4 ,the strata consist of basaltic streams4 ,a ,section left to right3 ,height at the foot of ,high ,knoll3 #a1fjj at top of strata4 ,height on the edge of ,ladder ,hill3 #eaj at top of strata4 ,bottom at coast rocky only to a depth of five or six fathoms4 #cj fathoms3 bottom mud and sand4 #ajj fathoms sloping more sharply to #bej fathoms47 ,when viewing the sea-worn cliffs of ,patagonia1 in some parts between eight hundred and nine hundred feet in height1 and formed of horizontal tertiary strata1 which must once have extended far seaward--or again1 when viewing the lofty cliffs round many volcanic islands1 in which the gentle inclination of the lava-streams indicates the former extension of the land1 a difficulty often occurred to me1 namely1 how the strata could possibly have been removed by the action of the sea at a considerable depth beneath its surface4 ,the section in ,diagram #g1 which represents the general form of the land on the northern and leeward side of ,st4 ,helena 7taken from ,mr4 ,seale's large model and various measurements71 and of the bottom of the adjoining sea 7taken chiefly from ,captain ,austin's survey and some old charts71 will show the nature of this difficulty4 ,if1 as seems probable1 the basaltic streams were originally prolonged with nearly their present inclination1 they must1 as shown by the dotted line in the section1 once have extended at least to a point1 now covered by the sea to a depth of nearly thirty fathoms3 but ,i have every reason to believe they extended considerably further1 for the inclination of the streams is less near the coast than further inland4 ,it should also be observed1 that other sections on the coast of this island would have given far more striking results1 but ,i had not the exact measurements2 thus1 on the windward side1 the cliffs are about two thousand feet in height and the cut-off lava streams very gently inclined1 and the bottom of the sea has nearly a similar slope all round the island4 ,how1 then1 has all the hard basaltic rock1 which once extended beneath the surface of the sea1 been worn away8 ,according to ,captain ,austin1 the bottom is uneven and rocky only to that very small distance from the beach within which the depth is from five to six fathoms2 outside this line1 to a depth of about one hundred fathoms1 the bottom is smooth1 gently inclined1 and formed of mud and sand2 outside the one hundred fathoms1 it plunges suddenly into unfathomable depths1 as is so very commonly the case on all coasts where sediment is accumulating4 ,at greater depths than the five or six fathoms1 it seems impossible1 under existing circumstances1 that the sea can both have worn away hard rock1 in parts to a thickness of at least #aej feet1 and have deposited a smooth bed of fine sediment4 ,now1 if we had any reason to suppose that ,st4 ,helena had1 during a long period1 gone on slowly subsiding1 every difficulty would be removed3 for looking at the diagram1 and imagining a fresh amount of subsidence1 we can see that the waves would then act on the coast-cliffs with fresh and unimpaired vigour1 whilst the rocky ledge near the beach would be carried down to that depth1 at which sand and mud would be deposited on its bare and uneven surface3 after the formation near the shore of a new rocky shoal1 fresh subsidence would carry it down and allow it to be smoothly covered up4 ,but in the case of the many cliff-bounded islands1 for instance in some of the ,canary ,islands and of ,madeira1 round which the inclination of the strata shows that the land once extended far into the depths of the sea1 where there is no apparent means of hard rock being worn away--are we to suppose that all these islands have slowly subsided8 ,madeira1 ,i may remark1 has1 according to ,mr4 ,smith of ,jordan ,hill1 subsided4 ,are we to extend this conclusion to the high1 cliff- bound1 horizontally stratified shores of ,patagonia1 off which1 though the water is not deep even at the distance of several miles1 yet the smooth bottom of pebbles gradually decreasing in size with the increasing depth1 and derived from a foreign source1 seem to declare that the sea is now a depositing and not a corroding agent8 ,i am much inclined to suspect1 that we shall hereafter find in all such cases1 that the land with the adjoining bed of the sea has in truth subsided3 the time will1 ,i believe1 come1 when geologists will consider it as improbable1 that the land should have retained the same level during a whole geological period1 as that the atmosphere should have remained absolutely calm during an entire season4 ,,chapter ,,ii4 ,,on ,,the ,,elevation ,,of ,,the ,,western ,,coast ,,of ,,south ,,america4 ,chonos ,archipelago4--,chiloe1 recent and gradual elevation of1 traditions of the inhabitants on this subject4--,concepcion1 earthquake and elevation of4--,,valparaiso1 great elevation of1 upraised shells1 earth of marine origin1 gradual rise of the land within the historical period4--,,coquimbo1 elevation of1 in recent times2 terraces of marine origin1 their inclination1 their escarpments not horizontal4--,guasco1 gravel terraces of4--,copiapo4--,,peru4--,upraised shells of ,cobija1 ,iquique1 and ,arica4--,lima1 shell-beds and sea-beach on ,san ,lorenzo1 human remains1 fossil earthenware1 earthquake debacle1 recent subsidence4--,on the decay of upraised shells4--,general summary4 ,commencing at the south and proceeding northward1 the first place at which ,i landed1 was at ,cape ,tres ,montes1 in latitude #df degrees #ce4 ,here1 on the shores of ,christmas ,cove1 ,i observed in several places a beach of pebbles with recent shells1 about twenty feet above high-water mark4 ,southward of ,tres ,montes 7between latitude #dg and #dh degrees71 ,byron remarks1 8,we thought it very strange1 that upon the summits of the highest hills were found beds of shells1 a foot or two thick40 78,narrative of the ,loss of the #8,wager'407 ,in the ,chonos ,archipelago1 the island of ,lemus 7latitude #dd degrees #cj7 was1 according to ,m4 ,coste1 suddenly elevated eight feet1 during the earthquake of #ahbi3 he adds1 8,des roches jadis toujours couvertes par la mer1 restant aujourd'hui constamment decouvertes40 78,comptes ,rendus0 ,october #ahch page #gjf47 ,in other parts of this archipelago1 ,i observed two terraces of gravel1 abutting to the foot of each other3 at ,lowe's ,harbour 7#dc degrees #dh71 under a great mass of the boulder formation1 about three hundred feet in thickness1 ,i found a layer of sand1 with numerous comminuted fragments of sea-shells1 having a fresh aspect1 but too small to be identified4 ,,the ,,island ,,of ,,chiloe4 ,the evidence of recent elevation is here more satisfactory4 ,the bay of ,san ,carlos is in most parts bounded by precipitous cliffs from about ten to forty feet in height1 their bases being separated from the present line of tidal action by a talus1 a few feet in height1 covered with vegetation4 ,in one sheltered creek 7west of ,p4 ,arena71 instead of a loose talus1 there was a bare sloping bank of tertiary mudstone1 perforated1 above the line of the highest tides1 by numerous shells of a ,pholas now common in the harbour4 ,the upper extremities of these shells1 standing upright in their holes with grass growing out of them1 were abraded about a quarter of an inch1 to the same level with the surrounding worn strata4 ,in other parts1 ,i observed 7as at ,pudeto7 a great beach1 formed of comminuted shells1 twenty feet above the present shore4 ,in other parts again1 there were small caves worn into the foot of the low cliffs1 and protected from the waves by the talus with its vegetation3 one such cave1 which ,i examined1 had its mouth about twenty feet1 and its bottom1 which was filled with sand containing fragments of shells and legs of crabs1 from eight to ten feet above high-water mark4 ,from these several facts1 and from the appearance of the upraised shells1 ,i inferred that the elevation had been quite recent2 and on inquiring from ,mr4 ,williams1 the ,portmaster1 he told me he was convinced that the land had risen1 or the sea fallen1 four feet within the last four years4 ,during this period1 there had been one severe earthquake1 but no particular change of level was then observed2 from the habits of the people who all keep boats in the protected creeks1 it is absolutely impossible that a rise of four feet could have taken place suddenly and been unperceived4 ,mr4 ,williams believes that the change has been quite gradual4 ,without the elevatory movement continues at a quick rate1 there can be no doubt that the sea will soon destroy the talus of earth at the foot of the cliffs round the bay1 and will then reach its former lateral extension1 but not of course its former level3 some of the inhabitants assured me that one such talus1 with a footpath on it1 was even already sensibly decreasing in width4 ,i received several accounts of beds of shells1 existing at considerable heights in the inland parts of ,chiloe2 and to one of these1 near ,catiman1 ,i was guided by a countryman4 ,here1 on the south side of the peninsula of ,lacuy1 there was an immense bed of the ,venus costellata and of an oyster1 lying on the summit-edge of a piece of tableland1 #cej feet 7by the barometer7 above the level of the sea4 ,the shells were closely packed together1 embedded in and covered by a very black1 damp1 peaty mould1 two or three feet in thickness1 out of which a forest of great trees was growing4 ,considering the nature and dampness of this peaty soil1 it is surprising that the fine ridges on the outside of the ,venus are perfectly preserved1 though all the shells have a blackened appearance4 ,i did not doubt that the black soil1 which when dry1 cakes hard1 was entirely of terrestrial origin1 but on examining it under the microscope1 ,i found many very minute rounded fragments of shells1 amongst which ,i could distinguish bits of ,serpulae and mussels4 ,the ,venus costellata1 and the ,ostrea 7,o4 edulis1 according to ,captain ,king7 are now the commonest shells in the adjoining bays4 ,in a bed of shells1 a few feet below the #cej feet bed1 ,i found a horn of the little ,cervus humilis1 which now inhabits ,chiloe4 ,the eastern or inland side of ,chiloe1 with its many adjacent islets1 consists of tertiary and boulder deposits1 worn into irregular plains capped by gravel4 ,near ,castro1 and for ten miles southward1 and on the islet of ,lemuy1 ,i found the surface of the ground to a height of between twenty and thirty feet above high-water mark1 and in several places apparently up to fifty feet1 thickly coated by much comminuted shells1 chiefly of the ,venus costellata and ,mytilus ,chiloensis2 the species now most abundant on this line of coast4 ,as the inhabitants carry immense numbers of these shells inland1 the continuity of the bed at the same height was often the only means of recognising its natural origin4 ,near ,castro1 on each side of the creek and rivulet of the ,gamboa1 three distinct terraces are seen3 the lowest was estimated at about one hundred and fifty feet in height1 and the highest at about five hundred feet1 with the country irregularly rising behind it2 obscure traces1 also1 of these same terraces could be seen along other parts of the coast4 ,there can be no doubt that their three escarpments record pauses in the elevation of the island4 ,i may remark that several promontories have the word ,huapi1 which signifies in the ,indian tongue1 island1 appended to them1 such as ,huapilinao1 ,huapilacuy1 ,caucahuapi1 etc42 and these1 according to ,indian traditions1 once existed as islands4 ,in the same manner the term ,pulo in ,sumatra is appended to the names of promontories1 traditionally said to have been islands 7,marsden's 8,sumatra0 page #ca472 in ,sumatra1 as in ,chiloe1 there are upraised recent shells4 ,the ,bay of ,carelmapu1 on the mainland north of ,chiloe1 according to ,aguerros1 was in #afdc a good harbour 78,descripcion ,hist4 de la ,provincia de ,chiloe0 page #gh4 ,from the account given by the old ,spanish writers1 it would appear that several other harbours1 between this point and ,concepcion1 were formerly much deeper than they now are472 it is now quite useless1 except for boats4 ,,valdivia4 ,i did not observe here any distinct proofs of recent elevation2 but in a bed of very soft sandstone1 forming a fringe-like plain1 about sixty feet in height1 round the hills of mica-slate1 there are shells of ,mytilus1 ,crepidula1 ,solen1 ,novaculina1 and ,cytheraea1 too imperfect to be specifically recognised4 ,at ,imperial1 seventy miles north of ,valdivia1 ,aguerros states that there are large beds of shells1 at a considerable distance from the coast1 which are burnt for lime4 7,ibid page #be47 ,the island of ,mocha1 lying a little north of ,imperial1 was uplifted two feet1 during the earthquake of #ahce4 78,voyages of #8,adventure' and #8,beagle'0 volume #b page #dae47 ,,concepcion4 ,i cannot add anything to the excellent account by ,captain ,fitzroy of the elevation of the land at this place1 which accompanied the earthquake of #ahce4 7,ibid volume #b page #dab et seq4 ,in volume #e page #fja of the 8,geological ,transactions0 ,i have given an account of the remarkable volcanic phenomena1 which accompanied this earthquake4 ,these phenomena appear to me to prove that the action1 by which large tracts of land are uplifted1 and by which volcanic eruptions are produced1 is in every respect identical47 ,i will only recall to the recollection of geologists1 that the southern end of the island of ,st4 ,mary was uplifted eight feet1 the central part nine1 and the northern end ten feet2 and the whole island more than the surrounding districts4 ,great beds of mussels1 patellae1 and chitons still adhering to the rocks were upraised above high-water mark2 and some acres of a rocky flat1 which was formerly always covered by the sea1 was left standing dry1 and exhaled an offensive smell1 from the many attached and putrefying shells4 ,it appears from the researches of ,captain ,fitzroy that both the island of ,st4 ,mary and ,concepcion 7which was uplifted only four or five feet7 in the course of some weeks subsided1 and lost part of their first elevation4 ,i will only add as a lesson of caution1 that round the sandy shores of the great ,bay of ,concepcion1 it was most difficult1 owing to the obliterating effects of the great accompanying wave1 to recognise any distinct evidence of this considerable upheaval2 one spot must be excepted1 where there was a detached rock which before the earthquake had always been covered by the sea1 but afterwards was left uncovered4 ,on the island of ,quiriquina 7in the ,bay of ,concepcion71 ,i found1 at an estimated height of four hundred feet1 extensive layers of shells1 mostly comminuted1 but some perfectly preserved and closely packed in black vegetable mould2 they consisted of ,concholepas1 ,fissurella1 ,mytilus1 ,trochus1 and ,balanus4 ,some of these layers of shells rested on a thick bed of bright-red1 dry1 friable earth1 capping the surface of the tertiary sandstone1 and extending1 as ,i observed whilst sailing along the coast1 for #aej miles southward3 at ,valparaiso1 we shall presently see that a similar red earthy mass1 though quite like terrestrial mould1 is really in chief part of recent marine origin4 ,on the flanks of this island of ,quiriquina1 at a less height than the #djj feet1 there were spaces several feet square1 thickly strewed with fragments of similar shells4 ,during a subsequent visit of the 8,beagle0 to ,concepcion1 ,mr4 ,kent1 the assistant-surgeon1 was so kind as to make for me some measurements with the barometer3 he found many marine remains along the shores of the whole bay1 at a height of about twenty feet2 and from the hill of ,sentinella behind ,talcahuano1 at the height of #afj feet1 he collected numerous shells1 packed together close beneath the surface in black earth1 consisting of two species of ,mytilus1 two of ,crepidula1 one of ,concholepas1 of ,fissurella1 ,venus1 ,mactra1 ,turbo1 ,monoceros1 and the ,balanus psittacus4 ,these shells were bleached1 and within some of the ,balani other ,balani were growing1 showing that they must have long lain dead in the sea4 ,the above species ,i compared with living ones from the bay1 and found them identical2 but having since lost the specimens1 ,i cannot give their names3 this is of little importance1 as ,mr4 ,broderip has examined a similar collection1 made during ,captain ,beechey's expedition1 and ascertained that they consisted of ten recent species1 associated with fragments of ,echini1 crabs1 and ,flustrae2 some of these remains were estimated by ,lieutenant ,belcher to lie at the height of nearly a thousand feet above the level of the sea4 78,zoology of ,captain ,beechey's ,voyage0 page #afb47 ,in some places round the bay1 ,mr4 ,kent observed that there were beds formed exclusively of the ,mytilus ,chiloensis3 this species now lives in parts never uncovered by the tides4 ,at considerable heights1 ,mr4 ,kent found only a few shells2 but from the summit of one hill1 #fbe feet high1 he brought me specimens of the ,concholepas1 ,mytilus ,chiloensis1 and a ,turbo4 ,these shells were softer and more brittle than those from the height of #afd feet2 and these latter had obviously a much more ancient appearance than the same species from the height of only twenty feet4 ,,coast ,,north ,,of ,,concepcion4 ,the first point examined was at the mouth of the ,rapel 7#afj miles north of ,concepcion and sixty miles south of ,valparaiso71 where ,i observed a few shells at the height of #ajj feet1 and some barnacles adhering to the rocks three or four feet above the highest tides3 ,m4 ,gay found here recent shells at the distance of two leagues from the shore4 78,annales des ,scienc4 ,nat40 ,avril #ahcc47 ,inland there are some wide1 gravel-capped plains1 intersected by many broad1 flat-bottomed valleys 7now carrying insignificant streamlets71 with their sides cut into successive wall-like escarpments1 rising one above another1 and in many places1 according to ,m4 ,gay1 worn into caves4 ,the one cave 7,c4 del ,obispo7 which ,i examined1 resembled those formed on many sea-coasts1 with its bottom filled with shingle4 ,these inland plains1 instead of sloping towards the coast1 are inclined in an opposite direction towards the ,cordillera1 like the successively rising terraces on the inland or eastern side of ,chiloe3 some points of granite1 which project through the plains near the coast1 no doubt once formed a chain of outlying islands1 on the inland shores of which the plains were accumulated4 ,at ,bucalemu1 a few miles northward of the ,rapel1 ,i observed at the foot1 and on the summit-edge of a plain1 ten miles from the coast1 many recent shells1 mostly comminuted1 but some perfect4 ,there were1 also1 many at the bottom of the great valley of the ,maypu4 ,at ,san ,antonio1 shells are said to be collected and burnt for lime4 ,at the bottom of a great ravine 7,quebrada ,onda1 on the road to ,casa ,blanca71 at the distance of several miles from the coast1 ,i noticed a considerable bed1 composed exclusively of ,mesodesma donaciforme1 ,desh41 lying on a bed of muddy sand3 this shell now lives associated together in great numbers1 on tidal-flats on the coast of ,chile4 ,,valparaiso4 ,during two successive years ,i carefully examined1 part of the time in company with ,mr4 ,alison1 into all the facts connected with the recent elevation of this neighbourhood4 ,in very many parts a beach of broken shells1 about fourteen or fifteen feet above high-water mark1 may be observed2 and at this level the coast-rocks1 where precipitous1 are corroded in a band4 ,at one spot1 ,mr4 ,alison1 by removing some birds' dung1 found at this same level barnacles adhering to the rocks4 ,for several miles southward of the bay1 almost every flat little headland1 between the heights of #fj and #bcj feet 7measured by the barometer71 is smoothly coated by a thick mass of comminuted shells1 of the same species1 and apparently in the same proportional numbers with those existing in the adjoining sea4 ,the ,concholepas is much the most abundant1 and the best preserved shell2 but ,i extracted perfectly preserved specimens of the ,fissurella biradiata1 a ,trochus and ,balanus 7both well-known1 but according to ,mr4 ,sowerby yet unnamed7 and parts of the ,mytilus ,chiloensis4 ,most of these shells1 as well as an encrusting ,nullipora1 partially retain their colour2 but they are brittle1 and often stained red from the underlying brecciated mass of primary rocks2 some are packed together1 either in black or reddish moulds2 some lie loose on the bare rocky surfaces4 ,the total number of these shells is immense2 they are less numerous1 though still far from rare1 up a height of #a1jjj feet above the sea4 ,on the summit of a hill1 measured #eeg feet1 there was a small horizontal band of comminuted shells1 of which ,,many consisted 7and likewise from lesser heights7 of very young and small specimens of the still living ,concholepas1 ,trochus1 ,patellae1 ,crepidulae1 and of ,mytilus ,magellanicus 787 7,mr4 ,cuming informs me that he does not think this species identical with1 though closely resembling1 the true ,m4 ,magellanicus of the southern and eastern coast of ,south ,america2 it lives abundantly on the coast of ,chile473 several of these shells were under a quarter of an inch in their greatest diameter4 ,my attention was called to this circumstance by a native fisherman1 whom ,i took to look at these shell-beds2 and he ridiculed the notion of such small shells having been brought up for food2 nor could some of the species have adhered when alive to other larger shells4 ,on another hill1 some miles distant1 and #fdh feet high1 ,i found shells of the ,concholepas and ,trochus1 perfect1 though very old1 with fragments of ,mytilus ,chiloensis1 all embedded in reddish-brown mould3 ,i also found these same species1 with fragments of an ,echinus and of ,balanus psittacus1 on a hill #a1jjj feet high4 ,above this height1 shells became very rare1 though on a hill #a1cjj feet high 7,measured by the barometer3 the highest point in the range behind ,valparaiso ,i found to be #a1fbf feet above the level of the sea471 ,i collected the ,concholepas1 ,trochus1 ,fissurella1 and a ,patella4 ,at these greater heights the shells are almost invariably embedded in mould1 and sometimes are exposed only by tearing up bushes4 ,these shells obviously had a very much more ancient appearance than those from the lesser heights2 the apices of the ,trochi were often worn down2 the little holes made by burrowing animals were greatly enlarged2 and the ,concholepas was often perforated quite through1 owing to the inner plates of shell having scaled off4 ,many of these shells1 as ,i have said1 were packed in1 and were quite filled with1 blackish or reddish-brown earth1 resting on the granitic detritus4 ,i did not doubt until lately that this mould was of purely terrestrial origin1 when with a microscope examining some of it from the inside of a ,concholepas from the height of about one hundred feet1 ,i found that it was in considerable part composed of minute fragments of the spines1 mouth- bones1 and shells of ,echini1 and of minute fragments1 of chiefly very young ,patellae1 ,mytili1 and other species4 ,i found similar microscopical fragments in earth filling up the central orifices of some large ,fissurellae4 ,this earth when crushed emits a sickly smell1 precisely like that from garden-mould mixed with guano4 ,the earth accidentally preserved within the shells1 from the greater heights1 has the same general appearance1 but it is a little redder2 it emits the same smell when rubbed1 but ,i was unable to detect with certainty any marine remains in it4 ,this earth resembles in general appearance1 as before remarked1 that capping the rocks of ,quiriquina in the ,bay of ,concepcion1 on which beds of sea-shells lay4 ,i have1 also1 shown that the black1 peaty soil1 in which the shells at the height of #cej feet at ,chiloe were packed1 contained many minute fragments of marine animals4 ,these facts appear to me interesting1 as they show that soils1 which would naturally be considered of purely terrestrial nature1 may owe their origin in chief part to the sea4 ,being well aware from what ,i have seen at ,chiloe and in ,tierra del ,fuego1 that vast quantities of shells are carried1 during successive ages1 far inland1 where the inhabitants chiefly subsist on these productions1 ,i am bound to state that at greater heights than #eeg feet1 where the number of very young and small shells proved that they had not been carried up for food1 the only evidence of the shells having been naturally left by the sea1 consists in their invariable and uniform appearance of extreme antiquity--in the distance of some of the places from the coast1 in others being inaccessible from the nearest part of the beach1 and in the absence of fresh water for men to drink--in the shells ,,not ,,lying ,,in ,,heaps1--and1 lastly1 in the close similarity of the soil in which they are embedded1 to that which lower down can be unequivocally shown to be in great part formed from the debris of the sea animals4 7,in the 8,proceedings of the ,geological ,society0 volume #b page #ddf1 ,i have given a brief account of the upraised shells on the coast of ,chile1 and have there stated that the proofs of elevation are not satisfactory above the height of #bcj feet4 ,i had at that time unfortunately overlooked a separate page written during my second visit to ,valparaiso1 describing the shells now in my possession from the #eeg feet hill2 ,i had not then unpacked my collections1 and had not reconsidered the obvious appearance of greater antiquity of the shells from the greater heights1 nor had ,i at that time discovered the marine origin of the earth in which many of the shells are packed4 ,considering these facts1 ,i do not now feel a shadow of doubt that the shells1 at the height of #a1cjj feet1 have been upraised by natural causes into their present position47 ,with respect to the position in which the shells lie1 ,i was repeatedly struck here1 at ,concepcion1 and at other places1 with the frequency of their occurrence on the summits and edges either of separate hills1 or of little flat headlands often terminating precipitously over the sea4 ,the several above-enumerated species of mollusca1 which are found strewed on the surface of the land from a few feet above the level of the sea up to the height of #a1cjj feet1 all now live either on the beach1 or at only a few fathoms' depth3 ,mr4 ,edmondston1 in a letter to ,professor ,e4 ,forbes1 states that in dredging in the ,bay of ,valparaiso1 he found the common species of ,concholepas1 ,fissurella1 ,trochus1 ,monoceros1 ,chitons1 etc41 living in abundance from the beach to a depth of seven fathoms2 and dead shells occurred only a few fathoms deeper4 ,the common ,turritella cingulata was dredged up living at even from ten to fifteen fathoms2 but this is a species which ,i did not find here amongst the upraised shells4 ,considering this fact of the species being all littoral or sub-littoral1 considering their occurrence at various heights1 their vast numbers1 and their generally comminuted state1 there can be little doubt that they were left on successive beach-lines during a gradual elevation of the land4 ,the presence1 however1 of so many whole and perfectly preserved shells appears at first a difficulty on this view1 considering that the coast is exposed to the full force of an open ocean3 but we may suppose1 either that these shells were thrown during gales on flat ledges of rock just above the level of high-water mark1 and that during the elevation of the land they are never again touched by the waves1 or1 that during earthquakes1 such as those of #ahbb1 #ahce1 and #ahcg1 rocky reefs covered with marine-animals were it one blow uplifted above the future reach of the sea4 ,this latter explanation is1 perhaps1 the most probable one with respect to the beds at ,concepcion entirely composed of the ,mytilus ,chiloensis1 a species which lives below the lowest tides2 and likewise with respect to the great beds occurring both north and south of ,valparaiso1 of the ,mesodesma donaciforme1--a shell which1 as ,i am informed by ,mr4 ,cuming1 inhabits sandbanks at the level of the lowest tides4 ,but even in the case of shells having the habits of this ,mytilus and ,mesodesma1 beds of them1 wherever the sea gently throws up sand or mud1 and thus protects its own accumulations1 might be upraised by the slowest movement1 and yet remain undisturbed by the waves of each new beach-line4 ,it is worthy of remark1 that nowhere near ,valparaiso above the height of twenty feet1 or rarely of fifty feet1 ,i saw any lines of erosion on the solid rocks1 or any beds of pebbles2 this1 ,i believe1 may be accounted for by the disintegrating tendency of most of the rocks in this neighbourhood4 ,nor is the land here modelled into terraces3 ,mr4 ,alison1 however1 informs me1 that on both sides of one narrow ravine1 at the height of #cjj feet above the sea1 he found a succession of rather indistinct step-formed beaches1 composed of broken shells1 which together covered a space of about eighty feet vertical4 ,i can add nothing to the accounts already published of the elevation of the land at ,valparaiso1 which accompanied the earthquake of #ahbb 7,dr4 ,meyen 8,reise um ,erde0 ,th4 #a s4 #bba1 found in #ahca seaweed and other bodies still adhering to some rocks which during the shock of #ahbb were lifted above the sea473 but ,i heard it confidently asserted1 that a sentinel on duty1 immediately after the shock1 saw a part of a fort1 which previously was not within the line of his vision1 and this would indicate that the uplifting was not horizontal3 it would even appear from some facts collected by ,mr4 ,alison1 that only the eastern half of the bay was then elevated4 ,through the kindness of this same gentleman1 ,i am able to give an interesting account of the changes of level1 which have supervened here within historical periods3 about the year #afhj a long sea-wall 7or ,prefil7 was built1 of which only a few fragments now remain2 up to the year #ahag1 the sea often broke over it1 and washed the houses on the opposite side of the road 7where the prison now stands72 and even in #ahai1 ,mr4 ,j4 ,martin remembers walking at the foot of this wall1 and being often obliged to climb over it to escape the waves4 ,there now stands 7#ahcd7 on the seaward side of this wall1 and between it and the beach1 in one part a single row of houses1 and in another part two rows with a street between them4 ,this great extension of the beach in so short a time cannot be attributed simply to the accumulation of detritus2 for a resident engineer measured for me the height between the lowest part of the wall visible1 and the present beach-line at spring-tides1 and the difference was eleven feet six inches4 ,the church of ,s4 ,augustin is believed to have been built in #afad1 and there is a tradition that the sea formerly flowed very near it2 by levelling1 its foundations were found to stand nineteen feet six inches above the highest beach-line2 so that we see in a period of #bbj years1 the elevation cannot have been as much as nineteen feet six inches4 ,from the facts given with respect to the sea-wall1 and from the testimony of the elder inhabitants1 it appears certain that the change in level began to be manifest about the year #ahag4 ,the only sudden elevation of which there is any record occurred in #ahbb1 and this seems to have been less than three feet4 ,since that year1 ,i was assured by several competent observers1 that part of an old wreck1 which is firmly embedded near the beach1 has sensibly emerged2 hence here1 as at ,chiloe1 a slow rise of the land appears to be now in progress4 ,it seems highly probable that the rocks which are corroded in a band at the height of fourteen feet above the sea were acted on during the period1 when by tradition the base of ,s4 ,augustin church1 now nineteen feet six inches above the highest water-mark1 was occasionally washed by the waves4 ,,valparaiso ,,to ,,coquimbo4 ,for the first seventy-five miles north of ,valparaiso ,i followed the coast- road1 and throughout this space ,i observed innumerable masses of upraised shells4 ,about ,quintero there are immense accumulations 7worked for lime7 of the ,mesodesma donaciforme1 packed in sandy earth2 they abound chiefly about fifteen feet above high-water1 but shells are here found1 according to ,mr4 ,miers1 to a height of #ejj feet1 and at a distance of three leagues from the coast 78,travels in ,chile0 volume #a pages #cie1 #deh4 ,i received several similar accounts from the inhabitants1 and was assured that there are many shells on the plain of ,casa ,blanca1 between ,valparaiso and ,santiago1 at the height of #hjj feet473 ,i here noticed barnacles adhering to the rocks three or four feet above the highest tides4 ,in the neighbourhood of ,plazilla and ,catapilco1 at heights of between two hundred and three hundred feet1 the number of comminuted shells1 with some perfect ones1 especially of the ,mesodesma1 packed in layers1 was truly immense3 the land at ,plazilla had evidently existed as a bay1 with abrupt rocky masses rising out of it1 precisely like the islets in the broken bays now indenting this coast4 ,on both sides of the rivers ,ligua1 ,longotomo1 ,guachen1 and ,quilimari1 there are plains of gravel about two hundred feet in height1 in many parts absolutely covered with shells4 ,close to ,conchalee1 a gravel-plain is fronted by a lower and similar plain about sixty feet in height1 and this again is separated from the beach by a wide tract of low land3 the surfaces of all three plains or terraces were strewed with vast numbers of the ,concholepas1 ,mesodesma1 an existing ,venus1 and other still existing littoral shells4 ,the two upper terraces closely resemble in miniature the plains of ,patagonia2 and like them are furrowed by dry1 flat-bottomed1 winding valleys4 ,northward of this place ,i turned inward2 and therefore found no more shells3 but the valleys of ,chuapa1 ,illapel1 and ,limari1 are bounded by gravel-capped plains1 often including a lower terrace within4 ,these plains send bay-like arms between and into the surrounding hills2 and they are continuously united with other extensive gravel-capped plains1 separating the coast mountain-ranges from the ,cordillera4 ,,coquimbo4 ,a narrow fringe-like plain1 gently inclined towards the sea1 here extends for eleven miles along the coast1 with arms stretching up between the coast-mountains1 and likewise up the valley of ,coquimbo3 at its southern extremity it is directly connected with the plain of ,limari1 out of which hills abruptly rise like islets1 and other hills project like headlands on a coast4 ,the surface of the fringe-like plain appears level1 but differs insensibly in height1 and greatly in composition1 in different parts4 ,at the mouth of the valley of ,coquimbo1 the surface consists wholly of gravel1 and stands from #cjj to #cej feet above the level of the sea1 being about one hundred feet higher than in other parts4 ,in these other and lower parts the superficial beds consist of calcareous matter1 and rest on ancient tertiary deposits hereafter to be described4 ,the uppermost calcareous layer is cream-coloured1 compact1 smooth-fractured1 sub- stalactiform1 and contains some sand1 earthy matter1 and recent shells4 ,it lies on1 and sends wedge-like veins into1 a much more friable1 calcareous1 tuff-like variety2 and both rest on a mass about twenty feet in thickness1 formed of fragments of recent shells1 with a few whole ones1 and with small pebbles firmly cemented together4 7,in many respects this upper hard1 and the underlying more friable1 varieties1 resemble the great superficial beds at ,king ,george's ,sound in ,australia1 which ,i have described in my 8,geological ,observations on ,volcanic ,islands40 ,there could be little doubt that the upper layers there have been hardened by the action of rain on the friable1 calcareous matter1 and that the whole mass has originated in the decay of minutely comminuted sea-shells and corals47 ,this latter rock is called by the inhabitants losa1 and is used for building3 in many parts it is divided into strata1 which dip at an angle of ten degrees seaward1 and appear as if they had originally been heaped in successive layers 7as may be seen on coral-reefs7 on a steep beach4 ,this stone is remarkable from being in parts entirely formed of empty1 pellucid capsules or cells of calcareous matter1 of the size of small seeds3 a series of specimens unequivocally showed that all these capsules once contained minute rounded fragments of shells which have since been gradually dissolved by water percolating through the mass4 7,i have incidentally described this rock in the above work on ,volcanic ,islands47 ,the shells embedded in the calcareous beds forming the surface of this fringe-like plain1 at the height of from #bjj to #bej feet above the sea1 consist of3-- #a4 ,venus opaca4 #b4 ,mulinia ,byronensis4 #c4 ,pecten purpuratus4 #d4 ,mesodesma donaciforme4 #e4 ,turritella cingulata4 #f4 ,monoceros costatum4 #g4 ,concholepas ,peruviana4 #h4 ,trochus 7common ,valparaiso species74 #i4 ,calyptraea ,byronensis4 ,although these species are all recent1 and are all found in the neighbouring sea1 yet ,i was particularly struck with the difference in the proportional numbers of the several species1 and of those now cast up on the present beach4 ,i found only one specimen of the ,concholepas1 and the ,pecten was very rare1 though both these shells are now the commonest kinds1 with the exception1 perhaps1 of the ,calyptraea radians1 of which ,i did not find one in the calcareous beds4 ,i will not pretend to determine how far this difference in the proportional numbers depends on the age of the deposit1 and how far on the difference in nature between the present sandy beaches and the calcareous bottom1 on which the embedded shells must have lived4 7,,diagram #h4--,,section ,,of ,,plain ,,of ,,coquimbo4 ,a ,section through ,plain ,b-,b and ,ravine ,a4 ,surface of plain #beb feet above sea4 ,a4 ,stratified sand1 with recent shells in same proportions as on the beach1 half filling up a ravine4 ,b4 ,surface of plain1 with scattered shells in nearly same proportions as on the beach4 ,c4 ,upper calcareous bed1 and ,d4 ,lower calcareous sandy bed 7,losa71 both with recent shells1 but not in same proportions as on the beach4 ,e4 ,upper ferrugino-sandy old tertiary stratum1 and ,f4 ,lower old tertiary stratum1 both with all1 or nearly all1 extinct shells47 ,on the bare surface of the calcareous plain1 or in a thin covering of sand1 there were lying1 at a height from #bjj to #beb feet1 many recent shells1 which had a much fresher appearance than the embedded ones3 fragments of the ,concholepas1 and of the common ,mytilus1 still retaining a tinge of its colour1 were numerous1 and altogether there was manifestly a closer approach in proportional numbers to those now lying on the beach4 ,in a mass of stratified1 slightly agglutinated sand1 which in some places covers up the lower half of the seaward escarpment of the plain1 the included shells appeared to be in exactly the same proportional numbers with those on the beach4 ,on one side of a steep-sided ravine1 cutting through the plain behind ,herradura ,bay1 ,i observed a narrow strip of stratified sand1 containing similar shells in similar proportional numbers2 a section of the ravine is represented in ,diagram #h1 which serves also to show the general composition of the plain4 ,i mention this case of the ravine chiefly because without the evidence of the marine shells in the sand1 any one would have supposed that it had been hollowed out by simple alluvial action4 ,the escarpment of the fringe-like plain1 which stretches for eleven miles along the coast1 is in some parts fronted by two or three narrow1 step- formed terraces1 one of which at ,herradura ,bay expands into a small plain4 ,its surface was there formed of gravel1 cemented together by calcareous matter2 and out of it ,i extracted the following recent shells1 which are in a more perfect condition than those from the upper plain3-- #a4 ,calyptraea radians4 #b4 ,turritella cingulata4 #c4 ,oliva ,peruviana4 #d4 ,murex labiosus1 var4 #e4 ,nassa 7identical with a living species74 #f4 ,solen ,dombeiana4 #g4 ,pecten purpuratus4 #h4 ,venus ,chilensis4 #i4 ,amphidesma rugulosum4 ,the small irregular wrinkles of the posterior part of this shell are rather stronger than in the recent specimens of this species from ,coquimbo4 7,g4,b4 ,sowerby47 #aj4 ,balanus 7identical with living species74 ,on the syenitic ridge1 which forms the southern boundary of ,herradura ,bay and ,plain1 ,i found the ,concholepas and ,turritella cingulata 7mostly in fragments71 at the height of #bdb feet above the sea4 ,i could not have told that these shells had not formerly been brought up by man1 if ,i had not found one very small mass of them cemented together in a friable calcareous tuff4 ,i mention this fact more particularly1 because ,i carefully looked1 in many apparently favourable spots1 at lesser heights on the side of this ridge1 and could not find even the smallest fragment of a shell4 ,this is only one instance out of many1 proving that the absence of sea-shells on the surface1 though in many respects inexplicable1 is an argument of very little weight in opposition to other evidence on the recent elevation of the land4 ,the highest point in this neighbourhood at which ,i found upraised shells of existing species was on an inland calcareous plain1 at the height of #beb feet above the sea4 ,it would appear from ,mr4 ,caldcleugh's researches1 that a rise has taken place here within the last century and a half 78,proceedings of the ,geological ,society0 volume #b page #ddf472 and as no sudden change of level has been observed during the not very severe earthquakes1 which have occasionally occurred here1 the rising has probably been slow1 like that now1 or quite lately1 in progress at ,chiloe and at ,valparaiso3 there are three well-known rocks1 called the ,pelicans1 which in #agaj1 according to ,feuillee1 were a fleur d'eau1 but now are said to stand twelve feet above low-water mark3 the spring-tides rise here only five feet4 ,there is another rock1 now nine feet above high-water mark1 which in the time of ,frezier and ,feuillee rose only five or six feet out of water4 ,mr4 ,caldcleugh1 ,i may add1 also shows 7and ,i received similar accounts7 that there has been a considerable decrease in the soundings during the last twelve years in the ,bays of ,coquimbo1 ,concepcion1 ,valparaiso1 and ,guasco2 but as in these cases it is nearly impossible to distinguish between the accumulation of sediment and the upheavement of the bottom1 ,i have not entered into any details4 ,,valley ,,of ,,coquimbo4 7,,figure #i4 ,,east ,,and ,,west ,,section ,,through ,,the ,,terraces ,,at ,,coquimbo1 ,,where ,,they ,,debouch ,,from ,,the ,,valley1 ,,and ,,front ,,the ,,sea4 ,vertical scale #a_/aj of inch to #ajj feet3 horizontal scale much contracted4 ,height of terrace in feet from east 7high7 to west 7low73 ,terrace ,f4 #cfd ,terrace ,e4 #cjb ,terrace ,d4 shown dotted1 height not given4 ,terrace ,c4 #abj ,terrace ,b4 #gj ,terrace ,a4 #be sloping down to level of sea at ,town of ,coquimbo47 ,the narrow coast-plain sends1 as before stated1 an arm1 or more correctly a fringe1 on both sides1 but chiefly on the southern side1 several miles up the valley4 ,these fringes are worn into steps or terraces1 which present a most remarkable appearance1 and have been compared 7though not very correctly7 by ,captain ,basil ,hall1 to the parallel roads of ,glen ,roy in ,scotland3 their origin has been ably discussed by ,mr4 ,lyell4 78,principles of ,geology0 #ast edition volume #c page #aca47 ,the first section which ,i will give 7,figure #i71 is not drawn across the valley1 but in an east and west line at its mouth1 where the step-formed terraces debouch and present their very gently inclined surfaces towards the ,pacific4 ,the bottom plain 7,a7 is about a mile in width1 and rises quite insensibly from the beach to a height of twenty-five feet at the foot of the next plain2 it is sandy1 and abundantly strewed with shells4 ,plain or terrace ,b is of small extent1 and is almost concealed by the houses of the town1 as is likewise the escarpment of terrace ,c4 ,on both sides of a ravine1 two miles south of the town1 there are two little terraces1 one above the other1 evidently corresponding with ,b and ,c2 and on them marine remains of the species already enumerated were plentiful4 ,terrace ,e is very narrow1 but quite distinct and level2 a little southward of the town there were traces of a terrace ,d intermediate between ,e and ,c4 ,terrace ,f is part of the fringe-like plain1 which stretches for the eleven miles along the coast2 it is here composed of shingle1 and is #ajj feet higher than where composed of calcareous matter4 ,this greater height is obviously due to the quantity of shingle1 which at some former period has been brought down the great valley of ,coquimbo4 ,considering the many shells strewed over the terraces ,a1 ,b1 and ,c1 and a few miles southward on the calcareous plain1 which is continuously united with the upper step-like plain ,f1 there cannot1 ,i apprehend1 be any doubt1 that these six terraces have been formed by the action of the sea2 and that their five escarpments mark so many periods of comparative rest in the elevatory movement1 during which the sea wore into the land4 ,the elevation between these periods may have been sudden and on ,,an ,,average not more than seventy-two feet each time1 or it may have been gradual and insensibly slow4 ,from the shells on the three lower terraces1 and on the upper one1 and ,i may add on the three gravel-capped terraces at ,conchalee1 being all littoral and sub-littoral species1 and from the analogical facts given at ,valparaiso1 and lastly from the evidence of a slow rising lately or still in progress here1 it appears to me far more probable that the movement has been slow4 ,the existence of these successive escarpments1 or old cliff- lines1 is in another respect highly instructive1 for they show periods of comparative rest in the elevatory movement1 and of denudation1 which would never even have been suspected from a close examination of many miles of coast southward of ,coquimbo4 7,,figure #aj4 ,,north ,,and ,,south ,,section ,,across ,,the ,,valley ,,of ,,coquimbo4 ,from north ,f 7high7 through ,e81 ,d1 ,c1 ,b1 ,a 7low71 ,b81 ,c1 ,d81 ,e1 ,f 7high74 ,vertical scale #a_/aj of inch to #ajj feet3 horizontal scale much contracted4 ,terraces marked with 8 do not occur on that side of the valley1 and are introduced only to make the diagram more intelligible4 ,a river and bottom- plain of valley ,c1 ,e1 and ,f1 on the south side of valley1 are respectively1 #aig1 #cgg1 and #dbj feet above the level of the sea4 ,,aa4 ,the bottom of the valley1 believed to be #ajj feet above the sea3 it is continuously united with the lowest plain ,a of ,figure #i4 ,b4 ,this terrace higher up the valley expands considerably2 seaward it is soon lost1 its escarpment being united with that of ,c3 it is not developed at all on the south side of the valley4 ,c4 ,this terrace1 like the last1 is considerably expanded higher up the valley4 ,these two terraces apparently correspond with ,b and ,c of ,figure #i4 ,d is not well developed in the line of this section2 but seaward it expands into a plain3 it is not present on the south side of the valley2 but it is met with1 as stated under the former section1 a little south of the town4 ,e is well developed on the south side1 but absent on the north side of the valley3 though not continuously united with ,e of ,figure #i1 it apparently corresponds with it4 ,f4 ,this is the surface-plain1 and is continuously united with that which stretches like a fringe along the coast4 ,in ascending the valley it gradually becomes narrower1 and is at last1 at the distance of about ten miles from the sea1 reduced to a row of flat-topped patches on the sides of the mountains4 ,none of the lower terraces extend so far up the valley47 ,we come now to the terraces on the opposite sides of the east and west valley of ,coquimbo3 the section in ,figure #aj is taken in a north and south line across the valley at a point about three miles from the sea4 ,the valley measured from the edges of the escarpments of the upper plain ,,ff is about a mile in width2 but from the bases of the bounding mountains it is from three to four miles wide4 ,the terraces marked with an interrogative do not exist on that side of the valley1 but are introduced merely to render the diagram more intelligible4 ,these five terraces are formed of shingle and sand2 three of them1 as marked by ,captain ,b4 ,hall 7namely1 ,b1 ,c1 and ,f71 are much more conspicuous than the others4 ,from the marine remains copiously strewed at the mouth of the valley on the lower terraces1 and southward of the town on the upper one1 they are1 as before remarked1 undoubtedly of marine origin2 but within the valley1 and this fact well deserves notice1 at a distance of from only a mile and a half to three or four miles from the sea1 ,i could not find even a fragment of a shell4 ,,on ,,the ,,inclination ,,of ,,the ,,terraces ,,of ,,coquimbo1 ,,and ,,on ,,the ,,upper ,,and ,,basal ,,edges ,,of ,,their ,,escarpments ,,not ,,being ,,horizontal4 ,the surfaces of these terraces slope in a slight degree1 as shown by the sections in ,figures #i and #aj taken conjointly1 both towards the centre of the valley1 and seawards towards its mouth4 ,this double or diagonal inclination1 which is not the same in the several terraces1 is1 as we shall immediately see1 of simple explanation4 ,there are1 however1 some other points which at first appear by no means obvious1--namely1 first1 that each terrace1 taken in its whole breadth from the summit-edge of one escarpment to the base of that above it1 and followed up the valley1 is not horizontal2 nor have the several terraces1 when followed up the valley1 all the same inclination2 thus ,i found the terraces ,c1 ,e1 and ,f1 measured at a point about two miles from the mouth of the valley1 stood severally between fifty-six to seventy-seven feet higher than at the mouth4 ,again1 if we look to any one line of cliff or escarpment1 neither its summit-edge nor its base is horizontal4 ,on the theory of the terraces having been formed during a slow and equable rise of the land1 with as many intervals of rest as there are escarpments1 it appears at first very surprising that horizontal lines of some kind should not have been left on the land4 ,the direction of the diagonal inclination in the different terraces being different1--in some being directed more towards the middle of the valley1 in others more towards its mouth1--naturally follows on the view of each terrace1 being an accumulation of successive beach-lines round bays1 which must have been of different forms and sizes when the land stood at different levels3 for if we look to the actual beach of a narrow creek1 its slope is directed towards the middle2 whereas1 in an open bay1 or slight concavity on a coast1 the slope is towards the mouth1 that is1 almost directly seaward2 hence as a bay alters in form and size1 so will the direction of the inclination of its successive beaches become changed4 7,,figure #aa4 ,,diagram ,,of ,a ,,bay ,,in ,a ,,district ,,which ,,has ,,begun ,,slowly ,,rising7 ,if it were possible to trace any one of the many beach-lines1 composing each sloping terrace1 it would of course be horizontal2 but the only lines of demarcation are the summit and basal edges of the escarpments4 ,now the summit-edge of one of these escarpments marks the furthest line or point to which the sea has cut into a mass of gravel sloping seaward2 and as the sea will generally have greater power at the mouth than at the protected head of the bay1 so will the escarpment at the mouth be cut deeper into the land1 and its summit-edge be higher2 consequently it will not be horizontal4 ,with respect to the basal or lower edges of the escarpments1 from picturing in one's mind ancient bays ,,entirely surrounded at successive periods by cliff-formed shores1 one's first impression is that they at least necessarily must be horizontal1 if the elevation has been horizontal4 ,but here is a fallacy3 for after the sea has1 during a cessation of the elevation1 worn cliffs all round the shores of a bay1 when the movement recommences1 and especially if it recommences slowly1 it might well happen that1 at the exposed mouth of the bay1 the waves might continue for some time wearing into the land1 whilst in the protected and upper parts successive beach-lines might be accumulating in a sloping surface or terrace at the foot of the cliffs which had been lately reached3 hence1 supposing the whole line of escarpment to be finally uplifted above the reach of the sea1 its basal line or foot near the mouth will run at a lower level than in the upper and protected parts of the bay2 consequently this basal line will not be horizontal4 ,and it has already been shown that the summit-edges of each escarpment will generally be higher near the mouth 7from the seaward sloping land being there most exposed and cut into7 than near the head of the bay2 therefore the total height of the escarpments will be greatest near the mouth2 and further up the old bay or valley they will on both sides generally thin out and die away3 ,i have observed this thinning out of the successive escarpment at other places besides ,coquimbo2 and for a long time ,i was quite unable to understand its meaning4 ,the rude diagram in ,figure #aa will perhaps render what ,i mean more intelligible2 it represents a bay in a district which has begun slowly rising4 ,before the movement commenced1 it is supposed that the waves had been enabled to eat into the land and form cliffs1 as far up1 but with gradually diminishing power1 as the points ,,aa3 after the movement had commenced and gone on for a little time1 the sea is supposed still to have retained the power1 at the exposed mouth of the bay1 of cutting down and into the land as it slowly emerged2 but in the upper parts of the bay it is supposed soon to have lost this power1 owing to the more protected situation and to the quantity of detritus brought down by the river2 consequently low land was there accumulated4 ,as this low land was formed during a slow elevatory movement1 its surface will gently slope upwards from the beach on all sides4 ,now1 let us imagine the bay1 not to make the diagram more complicated1 suddenly converted into a valley3 the basal line of the cliffs will of course be horizontal1 as far as the beach is now seen extending in the diagram2 but in the upper part of the valley1 this line will be higher1 the level of the district having been raised whilst the low land was accumulating at the foot of the inland cliffs4 ,if1 instead of the bay in the diagram being suddenly converted into a valley1 we suppose with much more probability it to be upraised slowly1 then the waves in the upper parts of the bay will continue very gradually to fail to reach the cliffs1 which are now in the diagram represented as washed by the sea1 and which1 consequently1 will be left standing higher and higher above its level2 whilst at the still exposed mouth1 it might well happen that the waves might be enabled to cut deeper and deeper1 both down and into the cliffs1 as the land slowly rose4 ,the greater or lesser destroying power of the waves at the mouths of successive bays1 comparatively with this same power in their upper and protected parts1 will vary as the bays become changed in form and size1 and therefore at different levels1 at their mouths and heads1 more or less of the surfaces between the escarpments 7that is1 the accumulated beach-lines or terraces7 will be left undestroyed3 from what has gone before we can see that1 according as the elevatory movements after each cessation recommence more or less slowly1 according to the amount of detritus delivered by the river at the heads of the successive bays1 and according to the degree of protection afforded by their altered forms1 so will a greater or less extent of terrace be accumulated in the upper part1 to which there will be no surface at a corresponding level at the mouth3 hence we can perceive why no one terrace1 taken in its whole breadth and followed up the valley1 is horizontal1 though each separate beach-line must have been so2 and why the inclination of the several terraces1 both transversely1 and longitudinally up the valley1 is not alike4 ,i have entered into this case in some detail1 for ,i was long perplexed 7and others have felt the same difficulty7 in understanding how1 on the idea of an equable elevation with the sea at intervals eating into the land1 it came that neither the terraces nor the upper nor lower edges of the escarpments were horizontal4 ,along lines of coast1 even of great lengths1 such as that of ,patagonia1 if they are nearly uniformly exposed1 the corroding power of the waves will be checked and conquered by the elevatory movement1 as often as it recommences1 at about the same period2 and hence the terraces1 or accumulated beach-lines1 will commence being formed at nearly the same levels3 at each succeeding period of rest1 they will1 also1 be eaten into at nearly the same rate1 and consequently there will be a much closer coincidence in their levels and inclinations1 than in the terraces and escarpments formed round bays with their different parts very differently exposed to the action of the sea4 ,it is only where the waves are enabled1 after a long lapse of time1 slowly to corrode hard rocks1 or to throw up1 owing to the supply of sediment being small and to the surface being steeply inclined1 a narrow beach or mound1 that we can expect1 as at ,glen ,roy in ,scotland 78,philosophical ,transactions0 #ahci page #ci471 a distinct line marking an old sea-level1 and which will be strictly horizontal1 if the subsequent elevatory movements have been so3 for in these cases no discernible effects will be produced1 except during the long intervening periods of rest2 whereas in the case of step-formed coasts1 such as those described in this and the preceding chapter1 the terraces themselves are accumulated during the slow elevatory process1 the accumulation commencing sooner in protected than in exposed situations1 and sooner where there is copious supply of detritus than where there is little2 on the other hand1 the steps or escarpments are formed during the stationary periods1 and are more deeply cut down and into the coast-land in exposed than in protected situations2--the cutting action1 moreover1 being prolonged in the most exposed parts1 both during the beginning and ending1 if slow1 of the upward movement4 ,although in the foregoing discussion ,i have assumed the elevation to have been horizontal1 it may be suspected1 from the considerable seaward slope of the terraces1 both up the valley of ,s4 ,cruz and up that of ,coquimbo1 that the rising has been greater inland than nearer the coast4 ,there is reason to believe 7,mr4 ,place in the 8,quarterly ,journal of ,science0 #ahbd volume #ag page #db471 from the effects produced on the water-course of a mill during the earthquake of #ahbb in ,chile1 that the upheaval one mile inland was nearly double1 namely1 between five and seven feet1 to what it was on the ,pacific4 ,we know1 also1 from the admirable researches of ,m4 ,bravais1 that in ,scandinavia the ancient sea-beaches gently slope from the interior mountain-ranges towards the coast1 and that they are not parallel one to the other 78,voyages de la ,comm4 du ,nord0 etc4 also 8,comptes ,rendus0 ,october #ahdb471 showing that the proportional difference in the amount of elevation on the coast and in the interior1 varied at different periods4 ,,coquimbo ,,to ,,guasco4 ,in this distance of ninety miles1 ,i found in almost every part marine shells up to a height of apparently from two hundred to three hundred feet4 ,the desert plain near ,choros is thus covered2 it is bounded by the escarpment of a higher plain1 consisting of pale-coloured1 earthy1 calcareous stone1 like that of ,coquimbo1 with the same recent shells embedded in it4 ,in the valley of ,chaneral1 a similar bed occurs in which1 differently from that of ,coquimbo1 ,i observed many shells of the ,concholepas3 near ,guasco the same calcareous bed is likewise met with4 ,in the valley of ,guasco1 the step-formed terraces of gravel are displaced in a more striking manner than at any other point4 ,i followed the valley for thirty-seven miles 7as reckoned by the inhabitants7 from the coast to ,ballenar2 in nearly the whole of this distance1 five grand terraces1 running at corresponding heights on both sides of the broad valley1 are more conspicuous than the three best-developed ones at ,coquimbo4 ,they give to the landscape the most singular and formal aspect2 and when the clouds hung low1 hiding the neighbouring mountains1 the valley resembled in the most striking manner that of ,santa ,cruz4 ,the whole thickness of these terraces or plains seems composed of gravel1 rather firmly aggregated together1 with occasional parting seams of clay3 the pebbles on the upper plain are often whitewashed with an aluminous substance1 as in ,patagonia4 ,near the coast ,i observed many sea-shells on the lower plains4 ,at ,freyrina 7twelve miles up the valley71 there are six terraces beside the bottom- surface of the valley3 the two lower ones are here only from two hundred to three hundred yards in width1 but higher up the valley they expand into plains2 the third terrace is generally narrow2 the fourth ,i saw only in one place1 but there it was distinct for the length of a mile2 the fifth is very broad2 the sixth is the summit-plain1 which expands inland into a great basin4 ,not having a barometer with me1 ,i did not ascertain the height of these plains1 but they appeared considerably higher than those at ,coquimbo4 ,their width varies much1 sometimes being very broad1 and sometimes contracting into mere fringes of separate flat-topped projections1 and then quite disappearing3 at the one spot1 where the fourth terrace was visible1 the whole six terraces were cut off for a short space by one single bold escarpment4 ,near ,ballenar 7thirty-seven miles from the mouth of the river71 the valley between the summit-edges of the highest escarpments is several miles in width1 and the five terraces on both sides are broadly developed3 the highest cannot be less than six hundred feet above the bed of the river1 which itself must1 ,i conceive1 be some hundred feet above the sea4 ,a north and south section across the valley in this part is represented in ,figure #ab4 7,,figure #ab4 ,,north ,,and ,,south ,,section ,,across ,,the ,,valley ,,of ,,guasco1 ,,and ,,of ,a ,,plain ,,north ,,of ,,it4 ,from left 7north1 high7 to right 7south1 high7 through plains ,b and ,a and the ,river of ,guasco at the ,town of ,ballenar47 ,on the northern side of the valley the summit-plain of gravel1 ,a1 has two escarpments1 one facing the valley1 and the other a great basin-like plain1 ,b1 which stretches for several leagues northward4 ,this narrow plain1 ,a1 with the double escarpment1 evidently once formed a spit or promontory of gravel1 projecting into and dividing two great bays1 and subsequently was worn on both sides into steep cliffs4 ,whether the several escarpments in this valley were formed during the same stationary periods with those of ,coquimbo1 ,i will not pretend to conjecture2 but if so the intervening and subsequent elevatory movements must have been here much more energetic1 for these plains certainly stand at a much higher level than do those of ,coquimbo4 ,,copiapo4 ,from ,guasco to ,copiapo1 ,i followed the road near the foot of the ,cordillera1 and therefore saw no upraised remains4 ,at the mouth1 however1 of the valley of ,copiapo there is a plain1 estimated by ,meyen 78,reise um die ,erde0 th4 #a s4 #cgb et seq47 between fifty and seventy feet in height1 of which the upper part consists chiefly of gravel1 abounding with recent shells1 chiefly of the ,concholepas1 ,venus ,dombeyi1 and ,calyptraea trochiformis4 ,a little inland1 on a plain estimated by myself at nearly three hundred feet1 the upper stratum was formed of broken shells and sand cemented by white calcareous matter1 and abounding with embedded recent shells1 of which the ,mulinia ,byronensis and ,pecten purpuratus were the most numerous4 ,the lower plain stretches for some miles southward1 and for an unknown distance northward1 but not far up the valley2 its seaward face1 according to ,meyen1 is worn into caves above the level of the present beach4 ,the valley of ,copiapo is much less steeply inclined and less direct in its course than any other valley which ,i saw in ,chile2 and its bottom does not generally consist of gravel3 there are no step-formed terraces in it1 except at one spot near the mouth of the great lateral valley of the ,despoblado where there are only two1 one above the other3 lower down the valley1 in one place ,i observed that the solid rock had been cut into the shape of a beach1 and was smoothed over with shingle4 ,northward of ,copiapo1 in latitude #bf degrees ,s41 the old voyager ,wafer found immense numbers of sea-shells some miles from the coast4 7,burnett's 8,collection of ,voyages0 volume #d page #aic47 ,at ,cobija 7latitude #bb degrees #cd7 ,m4 d',orbigny observed beds of gravel and broken shells1 containing ten species of recent shells2 he also found1 on projecting points of porphyry1 at a height of #cjj feet1 shells of ,concholepas1 ,chiton1 ,calyptraea1 ,fissurella1 and ,patella1 still attached to the spots on which they had lived4 ,m4 d',orbigny argues from this fact1 that the elevation must have been great and sudden 78,voyage1 ,part ,geolog40 page #id4 ,m4 d',orbigny 7page #ih71 in summing up1 says3 8,s'il est certain 7as he believes7 que tous les terrains en pente1 compris entre la mer et les montagnes sont l'ancien rivage de la mer1 on doit supposer1 pour l'ensemble1 un exhaussement que ce ne serait pas moindre de deux cent metres2 il faudrait supposer encore que ce soulevement n'a point ete graduel2444mais qu'il resulterait d'une seule et meme cause fortuite10 etc4 ,now1 on this view1 when the sea was forming the beach at the foot of the mountains1 many shells of ,concholepas1 ,chiton1 ,calyptraea1 ,fissurella1 and ,patella 7which are known to live close to the beach71 were attached to rocks at a depth of #cjj feet1 and at a depth of #fjj feet several of these same shells were accumulating in great numbers in horizontal beds4 ,from what ,i have myself seen in dredging1 ,i believe this to be improbable in the highest degree1 if not impossible2 and ,i think everyone who has read ,professor ,e4 ,forbes's excellent researches on the subject1 will without hesitation agree in this conclusion473 to me it appears far more probable that the movement was gradual1 with small starts as during the earthquakes of #ahbb and #ahce1 by which whole beds of shells attached to the rocks were lifted above the subsequent reach of the waves4 ,m4 d',orbigny also found rolled pebbles extending up the mountain to a height of at least six hundred feet4 ,at ,iquique 7latitude #bj degrees #ab ,s471 in a great accumulation of sand1 at a height estimated between one hundred and fifty and two hundred feet1 ,i observed many large sea-shells which ,i thought could not have been blown up by the wind to that height4 ,mr4 ,j4,h4 ,blake has lately described these shells3 he states that 8inland toward the mountains they form a compact uniform bed1 scarcely a trace of the original shells being discernible2 but as we approach the shore1 the forms become gradually more distinct till we meet with the living shells on the coast40 78,silliman's ,american ,journal of ,science0 volume #dd page #b47 ,this interesting observation1 showing by the gradual decay of the shells how slowly and gradually the coast must have been uplifted1 we shall presently see fully confirmed at ,lima4 ,at ,arica 7latitude #ah degrees #bh71 ,m4 d',orbigny found a great range of sand-dunes1 fourteen leagues in length1 stretching towards ,tacna1 including recent shells and bones of ,cetacea1 and reaching up to a height of #cjj feet above the sea4 78,voyage0 etc4 page #aja47 ,lieutenant ,freyer has given some more precise facts3 he states 7,in a letter to ,mr4 ,lyell 8,geological ,proceedings0 volume #b page #agi47 that the ,morro of ,arica is about four hundred feet high2 it is worn into obscure terraces1 on the bare rock of which he found ,balini and ,milleporae adhering4 ,at the height of between twenty and thirty feet the shells and corals were in a quite fresh state1 but at fifty feet they were much abraded2 there were1 however1 traces of organic remains at greater heights4 ,on the road from ,tacna to ,arequipa1 between ,loquimbo and ,moquegua1 ,mr4 ,m4 ,hamilton found numerous recent sea shells in sand1 at a considerable distance from the sea4 78,edinburgh ,new ,philosophical ,journal0 volume #cj page #aee47 ,,lima4 ,northward of ,arica1 ,i know nothing of the coast for about a space of five degrees of latitude2 but near ,callao1 the port of ,lima1 there is abundant and very curious evidence of the elevation of the land4 ,the island of ,san ,lorenzo is upwards of one thousand feet high2 the basset edges of the strata composing the lower part are worn into three obscure1 narrow1 sloping steps or ledges1 which can be seen only when standing on them3 they probably resemble those described by ,lieutenant ,freyer at ,arica4 ,the surface of the lower ledge1 which extends from a low cliff overhanging the sea to the foot of the next upper escarpment1 is covered by an enormous accumulation of recent shells4 7,m4 ,chevalier1 in the 8,voyage of the #8,bonite'0 observed these shells2 but his specimens were lost4--8,l',institut0 #ahch page #aea47 ,the bed is level1 and in some parts more than two feet in thickness2 ,i traced it over a space of one mile in length1 and heard of it in other places3 the uppermost part is eighty-five feet by the barometer above high-water mark4 ,the shells are packed together1 but not stratified3 they are mingled with earth and stones1 and are generally covered by a few inches of detritus2 they rest on a mass of nearly angular fragments of the underlying sandstone1 sometimes cemented together by common salt4 ,i collected eighteen species of shells of all ages and sizes4 ,several of the univalves had evidently long lain dead at the bottom of the sea1 for their ,,insides were incrusted with ,balani and ,serpulae4 ,all1 according to ,mr4 ,g4,b4 ,sowerby1 are recent species3 they consist of3-- #a4 ,mytilus ,magellanicus3 same as that found at ,valparaiso1 and there stated to be probably distinct from the true ,m4 ,magellanicus of the east coast4 #b4 ,venus costellata1 ,sowerby 8,zoological ,proceedings40 #c4 ,pecten purpuratus1 ,lam4 #d4 ,chama1 probably echinulata1 ,brod4 #e4 ,calyptraea ,byronensis1 ,gray4 #f4 ,calyptraea radians 7,trochus1 ,lam47 #g4 ,fissurella affinis1 ,gray4 #h4 ,fissurella biradiata1 ,trembly4 #i4 ,purpura chocolatta1 ,duclos4 #aj4 ,purpura ,peruviana1 ,gray4 #aa4 ,purpura labiata1 ,gray4 #ab4 ,purpura buxea 7,murex1 ,brod474 #ac4 ,concholepas ,peruviana4 #ad4 ,nassa1 related to reticulata4 #ae4 ,triton rudis1 ,brod4 #af4 ,trochus1 not yet described1 but well-known and very common4 #ag and #ah4 ,balanus1 two species1 both common on the coast4 ,these upraised shells appear to be nearly in the same proportional numbers- -with the exception of the ,crepidulae being more numerous--with those on the existing beach4 ,the state of preservation of the different species differed much2 but most of them were much corroded1 brittle1 and bleached3 the upper and lower surfaces of the ,concholepas had generally quite scaled off3 some of the ,trochi and ,fissurellae still partially retain their colours4 ,it is remarkable that these shells1 taken all together1 have fully as ancient an appearance1 although the extremely arid climate appears highly favourable for their preservation1 as those from #a1cjj feet at ,valparaiso1 and certainly a more ancient appearance than those from five to six hundred feet from ,valparaiso and ,concepcion2 at which places ,i have seen grass and other vegetables actually growing out of the shells4 ,many of the univalves here at ,san ,lorenzo were filled with1 and united together by1 pure salt1 probably left by the evaporation of the sea-spray1 as the land slowly emerged4 7,the underlying sandstone contains true layers of salt2 so that the salt may possibly have come from the beds in the higher parts of the island2 but ,i think more probably from the sea-spray4 ,it is generally asserted that rain never falls on the coast of ,peru2 but this is not quite accurate2 for1 on several days1 during our visit1 the so-called ,peruvian dew fell in sufficient quantity to make the streets muddy1 and it would certainly have washed so deliquescent a substance as salt into the soil4 ,i state this because ,m4 d',orbigny1 in discussing an analogous subject1 supposes that ,i had forgotten that it never rains on this whole line of coast4 ,see ,ulloa's 8,voyage0 volume #b ,english ,translation page #fg for an account of the muddy streets of ,lima1 and on the continuance of the mists during the whole winter4 ,rain1 also1 falls at rare intervals even in the driest districts1 as1 for instance1 during forty days1 in #agbf1 at ,chocope 7#g degrees #df72 this rain entirely ruined 78,ulloa0 etc4 page #ah7 the mud houses of the inhabitants47 ,on the highest parts of the ledge1 small fragments of the shells were mingled with1 and evidently in process of reduction into1 a yellowish-white1 soft1 calcareous powder1 tasting strongly of salt1 and in some places as fine as prepared medicinal chalk4 ,,fossil-,,remains ,,of ,,human ,,art4 ,in the midst of these shells on ,san ,lorenzo1 ,i found light corallines1 the horny ovule-cases of ,mollusca1 roots of seaweed 7,mr4 ,smith of ,jordan ,hill found pieces of seaweed in an upraised pleistocene deposit in ,scotland4 ,see his admirable ,paper in the 8,edinburgh ,new ,philosophical ,journal0 volume #be page #chd471 bones of birds1 the heads of ,indian corn and other vegetable matter1 a piece of woven rushes1 and another of nearly decayed ,,cotton string4 ,i extracted these remains by digging a hole1 on a level spot2 and they had all indisputably been embedded with the shells4 ,i compared the plaited rush1 the ,,cotton string1 and ,indian corn1 at the house of an antiquary1 with similar objects1 taken from the ,huacas or burial-grounds of the ancient ,peruvians1 and they were undistinguishable2 it should be observed that the ,peruvians used string only of cotton4 ,the small quantity of sand or gravel with the shells1 the absence of large stones1 the width and thickness of the bed1 and the time requisite for a ledge to be cut into the sandstone1 all show that these remains were not thrown high up by an earthquake-wave3 on the other hand1 these facts1 together with the number of dead shells1 and of floating objects1 both marine and terrestrial1 both natural and human1 render it almost certain that they were accumulated on a true beach1 since upraised eighty-five feet1 and upraised this much since ,,indian ,,man ,,inhabited ,,peru4 ,the elevation may have been1 either by several small sudden starts1 or quite gradual2 in this latter case the unrolled shells having been thrown up during gales beyond the reach of the waves which afterwards broke on the slowly emerging land4 ,i have made these remarks1 chiefly because ,i was at first surprised at the complete difference in nature1 between this broad1 smooth1 upraised bed of shells1 and the present shingle-beach at the foot of the low sandstone-cliffs2 but a beach formed1 when the sea is cutting into the land1 as is shown now to be the case by the low bare sandstone-cliffs1 ought not to be compared with a beach accumulated on a gently inclined rocky surface1 at a period when the sea 7probably owing to the elevatory movement in process7 was not able to eat into the land4 ,with respect to the mass of nearly angular1 salt- cemented fragments of sandstone1 which lie under the shells1 and which are so unlike the materials of an ordinary sea-beach2 ,i think it probable after having seen the remarkable effects of the earthquake of #ahce 7,i have described this in my 8,journal of ,researches0 page #cjc #bnd edition471 in absolutely shattering as if by gunpowder the ,,surface of the primary rocks near ,concepcion1 that a smooth bare surface of stone was left by the sea covered by the shelly mass1 and that afterwards when upraised1 it was superficially shattered by the severe shocks so often experienced here4 ,the very low land surrounding the town of ,callao1 is to the south joined by an obscure escarpment to a higher plain 7south of ,bella ,vista71 which stretches along the coast for a length of about eight miles4 ,this plain appears to the eye quite level2 but the sea-cliffs show that its height varies 7as far as ,i could estimate7 from seventy to one hundred and twenty feet4 ,it is composed of thin1 sometimes waving1 beds of clay1 often of bright red and yellow colours1 of layers of impure sand1 and in one part with a great stratified mass of granitic pebbles4 ,these beds are capped by a remarkable mass1 varying from two to six feet in thickness1 of reddish loam or mud1 containing many scattered and broken fragments of recent marine shells1 sometimes though rarely single large round pebble1 more frequently short irregular layers of fine gravel1 and very many pieces of red coarse earthenware1 which from their curvatures must once have formed parts of large vessels4 ,the earthenware is of ,indian manufacture2 and ,i found exactly similar pieces accidentally included within the bricks1 of which the neighbouring ancient ,peruvian burial-mounds are built4 ,these fragments abounded in such numbers in certain spots1 that it appeared as if waggon-loads of earthenware had been smashed to pieces4 ,the broken sea- shells and pottery are strewed both on the surface1 and throughout the whole thickness of this upper loamy mass4 ,i found them wherever ,i examined the cliffs1 for a space of between two and three miles1 and for half a mile inland2 and there can be little doubt that this same bed extends with a smooth surface several miles further over the entire plain4 ,besides the little included irregular layers of small pebbles1 there are occasionally very obscure traces of stratification4 ,at one of the highest parts of the cliff1 estimated #abj feet above the sea1 where a little ravine came down1 there were two sections1 at right angles to each other1 of the floor of a shed or building4 ,in both sections or faces1 two rows1 one over the other1 of large round stones could be distinctly seen2 they were packed close together on an artificial layer of sand two inches thick1 which had been placed on the natural clay-beds2 the round stones were covered by three feet in thickness of the loam with broken sea-shells and pottery4 ,hence1 before this widely spread-out bed of loam was deposited1 it is certain that the plain was inhabited2 and it is probable1 from the broken vessels being so much more abundant in certain spots than in others1 and from the underlying clay being fitted for their manufacture1 that the kilns stood here4 ,the smoothness and wide extent of the plain1 the bulk of matter deposited1 and the obscure traces of stratification seem to indicate that the loam was deposited under water2 on the other hand1 the presence of sea-shells1 their broken state1 the pebbles of various sizes1 and the artificial floor of round stones1 almost prove that it must have originated in a rush of water from the sea over the land4 ,the height of the plain1 namely1 #abj feet1 renders it improbable that an earthquake-wave1 vast as some have here been1 could have broken over the surface at its present level2 but when the land stood eighty-five feet lower1 at the period when the shells were thrown up on the ledge at ,s4 ,lorenzo1 and when as we know man inhabited this district1 such an event might well have occurred2 and if we may further suppose1 that the plain was at that time converted into a temporary lake1 as actually occurred1 during the earthquakes of #agac and #agdf1 in the case of the low land round ,callao owing to its being encircled by a high shingle-beach1 all the appearances above described will be perfectly explained4 ,i must add1 that at a lower level near the point where the present low land round ,callao joins the higher plain1 there are appearances of two distinct deposits both apparently formed by debacles3 in the upper one1 a horse's tooth and a dog's jaw were embedded2 so that both must have been formed after the settlement of the ,spaniards3 according to ,acosta1 the earthquake-wave of #aehf rose eighty-four feet4 ,the inhabitants of ,callao do not believe1 as far as ,i could ascertain1 that any change in level is now in progress4 ,the great fragments of brickwork1 which it is asserted can be seen at the bottom of the sea1 and which have been adduced as a proof of a late subsidence1 are1 as ,i am informed by ,mr4 ,gill1 a resident engineer1 loose fragments2 this is probable1 for ,i found on the beach1 and not near the remains of any building1 masses of brickwork1 three and four feet square1 which had been washed into their present places1 and smoothed over with shingle during the earthquake of #agdf4 ,the spit of land1 on which the ruins of ,,old ,callao stand1 is so extremely low and narrow1 that it is improbable in the highest degree that a town should have been founded on it in its present state2 and ,i have lately heard that ,m4 ,tschudi has come to the conclusion1 from a comparison of old with modern charts1 that the coast both south and north of ,callao has subsided4 7,i am indebted for this fact to ,dr4 ,e4 ,dieffenbach4 ,i may add that there is a tradition1 that the islands of ,san ,lorenzo and ,fronton were once joined1 and that the channel between ,san ,lorenzo and the mainland1 now above two miles in width1 was so narrow that cattle used to swim over47 ,i have shown that the island of ,san ,lorenzo has been upraised eighty-five feet since the ,peruvians inhabited this country2 and whatever may have been the amount of recent subsidence1 by so much more must the elevation have exceeded the eighty-five feet4 ,in several places in this neighbourhood1 marks of sea-action have been observed3 ,ulloa gives a detailed account of such appearances at a point five leagues northward of ,callao3 ,mr4 ,cruikshank found near ,lima successive lines of sea-cliffs1 with rounded blocks at their bases1 at a height of #gjj feet above the present level of the sea4 78,observaciones sobre el ,clima del ,lima0 par ,dr4 ,h4 ,unanue page #d4--,ulloa's 8,voyage0 volume #b ,english ,translation page #ig4--;,for ,mr4 ,cruikshank's observations1 see ,mr4 ,lyell's 8,principles of ,geology0 #ast edition volume #c page #acj47 ,,on ,,the ,,decay ,,of ,,upraised ,,sea-,,shells4 ,i have stated that many of the shells on the lower inclined ledge or terrace of ,san ,lorenzo are corroded in a peculiar manner1 and that they have a much more ancient appearance than the same species at considerably greater heights on the coast of ,chile4 ,i have1 also1 stated that these shells in the upper part of the ledge1 at the height of eighty-five feet above the sea1 are falling1 and in some parts are quite changed into a fine1 soft1 saline1 calcareous powder4 ,the finest part of this powder has been analysed for me1 at the request of ,sir ,h4 ,de la ,beche1 by the kindness of ,mr4 ,trenham ,reeks of the ,museum of ,economic ,geology2 it consists of carbonate of lime in abundance1 of sulphate and muriate of lime1 and of muriate and sulphate of soda4 ,the carbonate of lime is obviously derived from the shells2 and common salt is so abundant in parts of the bed1 that1 as before remarked1 the univalves are often filled with it4 ,the sulphate of lime may have been derived1 as has probably the common salt1 from the evaporation of the sea-spray1 during the emergence of the land2 for sulphate of lime is now copiously deposited from the spray on the shores of ,ascension4 7,see 8,volcanic ,islands0 etc4 by the ,author47 ,the other saline bodies may perhaps have been partially thus derived1 but chiefly1 as ,i conclude from the following facts1 through a different means4 ,on most parts of the second ledge or old sea-beach1 at a height of #agj feet1 there is a layer of white powder of variable thickness1 as much in some parts as two inches1 lying on the angular1 salt-cemented fragments of sandstone and under about four inches of earth1 which powder1 from its close resemblance in nature to the upper and most decayed parts of the shelly mass1 ,i can hardly doubt originally existed as a bed of shells1 now much collapsed and quite disintegrated4 ,i could not discover with the microscope a trace of organic structure in it2 but its chemical constituents1 according to ,mr4 ,reeks1 are the same as in the powder extracted from amongst the decaying shells on the lower ledge1 with the marked exception that the carbonate of lime is present in only very small quantity4 ,on the third and highest ledge1 ,i observed some of this powder in a similar position1 and likewise occasionally in small patches at considerably greater heights near the summit of the island4 ,at ,iquique1 where the whole face of the country is covered by a highly saliferous alluvium1 and where the climate is extremely dry1 we have seen that1 according to ,mr4 ,blake1 the shells which are perfect near the beach become1 in ascending1 gradually less and less perfect1 until scarcely a trace of their original structure can be discovered4 ,it is known that carbonate of lime and common salt left in a mass together1 and slightly moistened1 partially decompose each other 7,i am informed by ,dr4 ,kane1 through ,mr4 ,reeks1 that a manufactory was established on this principle in ,france1 but failed from the small quantity of carbonate of soda produced4 ,sprengel 8,gardeners' ,chronicle0 #ahde page #aeg1 states1 that salt and carbonate of lime are liable to mutual decomposition in the soil4 ,sir ,h4 ,de la ,beche informs me1 that calcareous rocks washed by the spray of the sea1 are often corroded in a peculiar manner2 see also on this latter subject 8,gardeners' ,chronicle0 page #fge #ahdd473 now we have at ,san ,lorenzo and at ,iquique1 in the shells and salt packed together1 and occasionally moistened by the so- called ,peruvian dew1 the proper elements for this action4 ,we can thus understand the peculiar corroded appearance of the shells on ,san ,lorenzo1 and the great decrease of quantity in the carbonate of lime in the powder on the upper ledge4 ,there is1 however1 a great difficulty on this view1 for the resultant salts should be carbonate of soda and muriate of lime2 the latter is present1 but not the carbonate of soda4 ,hence ,i am led to the perhaps unauthorised conjecture 7which ,i shall hereafter have to refer to7 that the carbonate of soda1 by some unexplained means1 becomes converted into a sulphate4 ,if the above remarks be just1 we are led to the very unexpected conclusion1 that a dry climate1 by leaving the salt from the sea-spray undissolved1 is much less favourable to the preservation of upraised shells than a humid climate4 ,however this may be1 it is interesting to know the manner in which masses of shells1 gradually upraised above the sea-level1 decay and finally disappear4 ,a ,,summary ,,on ,,the ,,recent ,,elevation ,,of ,,the ,,west ,,coast ,,of ,,south ,,america4 ,we have seen that upraised marine remains occur at intervals1 and in some parts almost continuously1 from latitude #de degrees #ce to #ab degrees ,s41 along the shores of the ,pacific4 ,this is a distance1 in a north and south line1 of #b1jge geographical miles4 ,from ,byron's observations1 the elevation has no doubt extended sixty miles further south2 and from the similarity in the form of the country near ,lima1 it has probably extended many leagues further north4 7,i may take this opportunity of stating that in a ,,ms4 in the ,geological ,society by ,mr4 ,weaver1 it is stated that beds of oysters and other recent shells are found thirty feet above the level of the sea1 in many parts of ,tampico1 in the ,gulf of ,mexico47 ,along this great line of coast1 besides the organic remains1 there are in very many parts1 marks of erosion1 caves1 ancient beaches1 sand-dunes1 and successive terraces of gravel1 all above the present level of the sea4 ,from the steepness of the land on this side of the continent1 shells have rarely been found at greater distances inland than from two to three leagues2 but the marks of sea-action are evident farther from the coast2 for instance1 in the valley of ,guasco1 at a distance of between thirty and forty miles4 ,judging from the upraised shells alone1 the elevation in ,chiloe has been #cej feet1 at ,concepcion certainly #fbe feet2 and by estimation #a1jjj feet2 at ,valparaiso #a1cjj feet2 at ,coquimbo #beb feet2 northward of this place1 sea-shells have not1 ,i believe1 been found above #cjj feet2 and at ,lima they were falling into decay 7hastened probably by the salt7 at #he feet4 ,not only has this amount of elevation taken place within the period of existing ,mollusca and ,cirripedes2 but their proportional numbers in the neighbouring sea have in most cases remained the same4 ,near ,lima1 however1 a small change in this respect between the living and the upraised was observed3 at ,coquimbo this was more evident1 all the shells being existing species1 but with those embedded in the uppermost calcareous plain not approximating so closely in proportional numbers1 as do those that lie loose on its surface at the height of #beb feet1 and still less closely than those which are strewed on the lower plains1 which latter are identical in proportional numbers with those now cast up on the beach4 ,from this circumstance1 and from not finding1 upon careful examination1 near ,coquimbo any shells at a greater height than #beb feet1 ,i believe that the recent elevation there has been much less than at ,valparaiso1 where it has been #a1cjj feet1 and ,i may add1 than at ,concepcion4 ,this considerable inequality in the amount of elevation at ,coquimbo and ,valparaiso1 places only #bjj miles apart1 is not improbable1 considering1 first1 the difference in the force and number of the shocks now yearly affecting different parts of this coast2 and1 secondly1 the fact of single areas1 such as that of the province of ,concepcion1 having been uplifted very unequally during the same earthquake4 ,it would1 in most cases1 be very hazardous to infer an inequality of elevation1 from shells being found on the surface or in superficial beds at different heights2 for we do not know on what their rate of decay depends2 and at ,coquimbo one instance out of many has been given1 of a promontory1 which1 from the occurrence of one very small collection of lime-cemented shells1 has indisputably been elevated #bdb feet1 and yet on which1 not even a fragment of shell could be found on careful examination between this height and the beach1 although many sites appeared very favourable for the preservation of organic remains3 the absence1 also1 of shells on the gravel-terraces a short distance up the valley of ,coquimbo1 though abundant on the corresponding terraces at its mouth1 should be borne in mind4 ,there are other epochs1 besides that of the existence of recent ,mollusca1 by which to judge of the changes of level on this coast4 ,at ,lima1 as we have just seen1 the elevation has been at least eighty-five feet1 within the ,indo-human period2 and since the arrival of the ,spaniards in #aecj1 there has apparently been a sinking of the surface4 ,at ,valparaiso1 in the course of #bbj years1 the rise must have been less than nineteen feet2 but it has been as much as from ten to eleven feet in the seventeen years subsequently to #ahag1 and of this rise only a part can be attributed to the earthquake of #ahbb1 the remainder having been insensible and apparently still1 in #ahcd1 in progress4 ,at ,chiloe the elevation has been gradual1 and about four feet during four years4 ,at ,coquimbo1 also1 it has been gradual1 and in the course of #aej years has amounted to several feet4 ,the sudden small upheavals1 accompanied by earthquakes1 as in #ahbb at ,valparaiso1 in #ahce at ,concepcion1 and in #ahcg in the ,chonos ,archipelago1 are familiar to most geologists1 but the gradual rising of the coast of ,chile has been hardly noticed2 it is1 however1 very important1 as connecting together these two orders of events4 ,the rise of ,lima1 having been eighty-five feet within the period of man1 is the more surprising if we refer to the eastern coast of the continent1 for at ,port ,s4 ,julian1 in ,patagonia1 there is good evidence 7as we shall hereafter see7 that when the land stood ninety feet lower1 the ,macrauchenia1 a mammiferous beast1 was alive2 and at ,bahia ,blanca1 when it stood only a few feet lower than it now does1 many gigantic quadrupeds ranged over the adjoining country4 ,but the coast of ,patagonia is some way distant from the ,cordillera1 and the movement at ,bahia ,blanca is perhaps noways connected with this great range1 but rather with the tertiary volcanic rocks of ,banda ,oriental1 and therefore the elevation at these places may have been infinitely slower than on the coast of ,peru4 ,all such speculations1 however1 must be vague1 for as we know with certainty that the elevation of the whole coast of ,patagonia has been interrupted by many and long pauses1 who will pretend to say that1 in such cases1 many and long periods of subsidence may not also have been intercalated8 ,in many parts of the coast of ,chile and ,peru there are marks of the action of the sea at successive heights on the land1 showing that the elevation has been interrupted by periods of comparative rest in the upward movement1 and of denudation in the action of the sea4 ,these are plainest at ,chiloe1 where1 in a height of about five hundred feet1 there are three escarpments1--at ,coquimbo1 where in a height of #cfd feet1 there are five1-- at ,guasco1 where there are six1 of which five may perhaps correspond with those at ,coquimbo1 but if so1 the subsequent and intervening elevatory movements have been here much more energetic1--at ,lima1 where1 in a height of about #bej feet there are three terraces1 and others1 as it is asserted1 at considerably greater heights4 ,the almost entire absence of ancient marks of sea-action at defined levels along considerable spaces of coast1 as near ,valparaiso and ,concepcion1 is highly instructive1 for as it is improbable that the elevation at these places alone should have been continuous1 we must attribute the absence of such marks to the nature and form of the coast-rocks4 ,seeing over how many hundred miles of the coast of ,patagonia1 and on how many places on the shores of the ,pacific1 the elevatory process has been interrupted by periods of comparative rest1 we may conclude1 conjointly with the evidence drawn from other quarters of the world1 that the elevation of the land is generally an intermittent action4 ,from the quantity of matter removed in the formation of the escarpments1 especially of those of ,patagonia1 it appears that the periods of rest in the movement1 and of denudation of the land1 have generally been very long4 ,in ,patagonia1 we have seen that the elevation has been equable1 and the periods of denudation synchronous over very wide spaces of coast2 on the shores of the ,pacific1 owing to the terraces chiefly occurring in the valleys1 we have not equal means of judging on this point2 and the very different heights of the upraised shells at ,coquimbo1 ,valparaiso1 and ,concepcion seem directly opposed to such a conclusion4 ,whether on this side of the continent the elevation1 between the periods of comparative rest when the escarpments were formed1 has been by small sudden starts1 such as those accompanying recent earthquakes1 or1 as is most probable1 by such starts conjointly with a gradual upward movement1 or by great and sudden upheavals1 ,i have no direct evidence4 ,but as on the eastern coast1 ,i was led to think1 from the analogy of the last hundred feet of elevation in ,la ,plata1 and from the nearly equal size of the pebbles over the entire width of the terraces1 and from the upraised shells being all littoral species1 that the elevation had been gradual2 so do ,i on this western coast1 from the analogy of the movements now in progress1 and from the vast numbers of shells now living exclusively on or close to the beach1 which are strewed over the whole surface of the land up to very considerable heights1 conclude1 that the movement here also has been slow and gradual1 aided probably by small occasional starts4 ,we know at least that at ,coquimbo1 where five escarpments occur in a height of #cfd feet1 the successive elevations1 if they have been sudden1 cannot have been very great4 ,it has1 ,i think1 been shown that the occasional preservation of shells1 unrolled and unbroken1 is not improbable even during a quite gradual rising of the land2 and their preservation1 if the movement has been aided by small starts1 is quite conformable with what actually takes place during recent earthquakes4 ,judging from the present action of the sea1 along the shores of the ,pacific1 on the deposits of its own accumulation1 the present time seems in most places to be one of comparative rest in the elevatory movement1 and of denudation of the land4 ,undoubtedly this is the case along the whole great length of ,patagonia4 ,at ,chiloe1 however1 we have seen that a narrow sloping fringe1 covered with vegetation1 separates the present sea-beach from a line of low cliffs1 which the waves lately reached2 here1 then1 the land is gaining in breadth and height1 and the present period is not one of rest in the elevation and of contingent denudation2 but if the rising be not prolonged at a quick rate1 there is every probability that the sea will soon regain its former horizontal limits4 ,i observed similar low sloping fringes on several parts of the coast1 both northward of ,valparaiso and near ,coquimbo2 but at this latter place1 from the change in form which the coast has undergone since the old escarpments were worn1 it may be doubted whether the sea1 acting for any length of time at its present level1 would eat into the land2 for it now rather tends to throw up great masses of sand4 ,it is from facts such as these that ,i have generally used the term ,,comparative rest1 as applied to the elevation of the land2 the rest or cessation in the movement being comparative both with what has preceded it and followed it1 and with the sea's power of corrosion at each spot and at each level4 ,near ,lima1 the cliff-formed shores of ,san ,lorenzo1 and on the mainland south of ,callao1 show that the sea is gaining on the land2 and as we have here some evidence that its surface has lately subsided or is still sinking1 the periods of comparative rest in the elevation and of contingent denudation1 may probably in many cases include periods of subsidence4 ,it is only1 as was shown in detail when discussing the terraces of ,coquimbo1 when the sea with difficulty and after a long lapse of time has either corroded a narrow ledge into solid rock1 or has heaped up on a steep surface a ,,narrow mound of detritus1 that we can confidently assert that the land at that level and at that period long remained absolutely stationary4 ,in the case of terraces formed of gravel or sand1 although the elevation may have been strictly horizontal1 it may well happen that no one level beach-line may be traceable1 and that neither the terraces themselves nor the summit nor basal edges of their escarpments may be horizontal4 ,finally1 comparing the extent of the elevated area1 as deduced from the upraised recent organic remains1 on the two sides of the continent1 we have seen that on the ,atlantic1 shells have been found at intervals from ,eastern ,tierra del ,fuego for #a1ahj miles northward1 and on the ,pacific for a space of #b1jge miles4 ,for a length of #gge miles1 they occur in the same latitudes on both sides of the continent4 ,without taking this circumstance into consideration1 it is probable from the reasons assigned in the last chapter1 that the entire breadth of the continent in ,central ,patagonia has been uplifted in mass2 but from other reasons there given1 it would be hazardous to extend this conclusion to ,la ,plata4 ,from the continent being narrow in the southern-most parts of ,patagonia1 and from the shells found at the ,inner ,narrows of the ,strait of ,magellan1 and likewise far up the valley of the ,santa ,cruz1 it is probable that the southern part of the western coast1 which was not visited by me1 has been elevated within the period of recent ,mollusca3 if so1 the shores of the ,pacific have been continuously1 recently1 and in a geological sense synchronously upraised1 from ,lima for a length of #b1dhj nautical miles southward1--a distance equal to that from the ,red ,sea to the ,north ,cape of ,scandinavia6 ,,chapter ,,iii4 ,,on ,,the ,,plains ,,and ,,valleys ,,of ,,chile3--,,saliferous ,,superficial ,,deposits4 ,basin-like plains of ,chile2 their drainage1 their marine origin4--,marks of sea-action on the eastern flanks of the ,cordillera4--,sloping terrace-like fringes of stratified shingle within the valleys of the ,cordillera2 their marine origin4--,boulders in the valley of ,cachapual4--,horizontal elevation of the ,cordillera4--,formation of valleys4--,boulders moved by earthquake-waves4--,saline superficial deposits4--,bed of nitrate of soda at ,iquique4--,saline incrustations4--,salt-lakes of ,la ,plata and ,patagonia2 purity of the salt2 its origin4 ,the space between the ,cordillera and the coast of ,chile is on a rude average from eighty to above one hundred miles in width2 it is formed1 either of an almost continuous mass of mountains1 or more commonly of several nearly parallel ranges1 separated by plains2 in the more southern parts of this province the mountains are quite subordinate to the plains2 in the northern part the mountains predominate4 ,the basin-like plains at the foot of the ,cordillera are in several respects remarkable2 that on which the capital of ,chile stands is fifteen miles in width1 in an east and west line1 and of much greater length in a north and south line2 it stands #a1gej feet above the sea2 its surface appears smooth1 but really falls and rises in wide gentle undulations1 the hollows corresponding with the main valleys of the ,cordillera3 the striking manner in which it abruptly comes up to the foot of this great range has been remarked by every author since the time of ,molina4 7,this plain is partially separated into two basins by a range of hills2 the southern half1 according to ,meyen 78,reise um ,erde0 ,th4 #a s4 #bgd71 falls in height1 by an abrupt step1 of between fifteen and twenty feet47 ,near the ,cordillera it is composed of a stratified mass of pebbles of all sizes1 occasionally including rounded boulders3 near its western boundary1 it consists of reddish sandy clay1 containing some pebbles and numerous fragments of pumice1 and sometimes passes into pure sand or into volcanic ashes4 ,at ,podaguel1 on this western side of the plain1 beds of sand are capped by a calcareous tuff1 the uppermost layers being generally hard and substalagmitic1 and the lower ones white and friable1 both together precisely resembling the beds at ,coquimbo1 which contain recent marine shells4 ,abrupt1 but rounded1 hummocks of rock rise out of this plain3 those of ,sta4 ,lucia and ,s4 ,cristoval are formed of greenstone-porphyry almost entirely denuded of its original covering of porphyritic claystone breccia2 on their summits1 many fragments of rock 7some of them kinds not found in situ7 are coated and united together by a white1 friable1 calcareous tuff1 like that found at ,podaguel4 ,when this matter was deposited on the summit of ,s4 ,cristoval1 the water must have stood #idf feet above the surface of the surrounding plain4 7,or #b1fij feet above the sea1 as measured barometrically by ,mr4 ,eck4 ,this tuff appears to the eye nearly pure2 but when placed in acid it leaves a considerable residue of sand and broken crystals1 apparently of feldspar4 ,dr4 ,meyen 78,reise0 ,th4 #a s4 #bfi7 says he found a similar substance on the neighbouring hill of ,dominico 7and ,i found it also on the ,cerro ,blanco71 and he attributes it to the weathering of the stone4 ,in some places which ,i examined1 its bulk put this view of its origin quite out of the question2 and ,i should much doubt whether the decomposition of a porphyry would1 in any case1 leave a crust chiefly composed of carbonate of lime4 ,the white crust1 which is commonly seen on weathered feldspathic rocks1 does not appear to contain any free carbonate of lime47 ,to the south this basin-like plain contracts1 and rising scarcely perceptibly with a smooth surface1 passes through a remarkable level gap in the mountains1 forming a true land-strait1 and called the ,angostura4 ,it then immediately expands into a second basin-formed plain3 this again to the south contracts into another land-strait1 and expands into a third basin1 which1 however1 falls suddenly in level about forty feet4 ,this third basin1 to the south1 likewise contracts into a strait1 and then again opens into the great plain of ,san ,fernando1 stretching so far south that the snowy peaks of the distant ,cordillera are seen rising above its horizon as above the sea4 ,these plains1 near the ,cordillera1 are generally formed of a thick stratified mass of shingle 7,the plain of ,san ,fernando has1 according to ,,mm4 ,meyen and ,gay 8,reise0 etc4 ,th4 #a ss4 #bie and #bih1 near the ,cordillera1 an upper step-formed plain of clay1 on the surface of which they found numerous blocks of rocks1 from two to three feet long1 either lying single or piled in heaps1 but all arranged in nearly straight lines472 in other parts1 of a red sandy clay1 often with an admixture of pumiceous matter4 ,although these basins are connected together like a necklace1 in a north and south line1 by smooth land-straits1 the streams which drain them do not all flow north and south1 but mostly westward1 through breaches worn in the bounding mountains2 and in the case of the second basin1 or that of ,rancagua1 there are two distinct breaches4 ,each basin1 moreover1 is not drained singly2 thus1 to give the most striking instance1 but not the only one1 in proceeding southward over the plain of ,rancagua1 we first find the water flowing northward to and through the northern land-strait2 then1 without crossing any marked ridge or watershed1 we see it flowing south-westward towards the northern one of the two breaches in the western mountainous boundary2 and lastly1 again without any ridge1 it flows towards the southern breach in these same mountains4 ,hence the surface of this one basin-like plain1 appearing to the eye so level1 has been modelled with great nicety1 so that the drainage1 without any conspicuous watersheds1 is directed towards three openings in the encircling mountains4 77,it appears from ,captain ,herbert's account of the ,diluvium of the ,himalaya1 8,gleanings of ,science0 ,calcutta volume #b page #afd1 that precisely similar remarks apply to the drainage of the plains or valleys between those great mountains47 ,the streams flowing from the southern basin-like plains1 after passing through the breaches to the west1 unite and form the river ,rapel1 which enters the ,pacific near ,navidad4 ,i followed the southernmost branch of this river1 and found that the basin or plain of ,san ,fernando is continuously and smoothly united with those plains1 which were described in the ,second ,chapter1 as being worn near the coast into successive cave-eaten escarpments1 and still nearer to the coast1 as being strewed with upraised recent marine remains4 ,i might have given descriptions of numerous other plains of the same general form1 some at the foot of the ,cordillera1 some near the coast1 and some halfway between these points4 ,i will allude only to one other1 namely1 the plain of ,uspallata1 lying on the eastern or opposite side of the ,cordillera1 between that great range and the parallel lower range of ,uspallata4 ,according to ,miers1 its surface is #f1jjj feet above the level of the sea3 it is from ten to fifteen miles in width1 and is said to extend with an unbroken surface for #ahj miles northwards3 it is drained by two rivers passing through breaches in the mountains to the east4 ,on the banks of the ,river ,mendoza it is seen to be composed of a great accumulation of stratified shingle1 estimated at #djj feet in thickness4 ,in general appearance1 and in numerous points of structure1 this plain closely resembles those of ,chile4 ,the origin and manner of formation of the thick beds of gravel1 sandy clay1 volcanic detritus1 and calcareous tuff1 composing these basin-like plains1 is very important2 because1 as we shall presently show1 they send arms or fringes far up the main valleys of the ,cordillera4 ,many of the inhabitants believe that these plains were once occupied by lakes1 suddenly drained2 but ,i conceive that the number of the separate breaches at nearly the same level in the mountains surrounding them quite precludes this idea4 ,had not such distinguished naturalists as ,,mm4 ,meyen and ,gay stated their belief that these deposits were left by great debacles rushing down from the ,cordillera1 ,i should not have noticed a view1 which appears to me from many reasons improbable in the highest degree--namely1 from the vast accumulation of ,,well-,,rounded ,,pebbles--their frequent stratification with layers of sand--the overlying beds of calcareous tuff--this same substance coating and uniting the fragments of rock on the hummocks in the plain of ,santiago--and lastly even from the worn1 rounded1 and much denuded state of these hummocks1 and of the headlands which project from the surrounding mountains4 ,on the other hand1 these several circumstances1 as well as the continuous union of the basins at the foot of the ,cordillera1 with the great plain of the ,rio ,rapel which still retains the marks of sea-action at various levels1 and their general similarity in form and composition with the many plains near the coast1 which are either similarly marked or are strewed with upraised marine remains1 fully convince me that the mountains bounding these basin-plains were breached1 their islet-like projecting rocks worn1 and the loose stratified detritus forming their now level surfaces deposited1 by the sea1 as the land slowly emerged4 ,it is hardly possible to state too strongly the perfect resemblance in outline between these basin-like1 long1 and narrow plains of ,chile 7especially when in the early morning the mists hanging low represented water71 and the creeks and fiords now intersecting the southern and western shores of the continent4 ,we can on this view of the sea1 when the land stood lower1 having long and tranquilly occupied the spaces between the mountain-ranges1 understand how the boundaries of the separate basins were breached in more than one place2 for we see that this is the general character of the inland bays and channels of ,tierra del ,fuego2 we there1 also1 see in the sawing action of the tides1 which flow with great force in the cross channels1 a power sufficient to keep the breaches open as the land emerged4 ,we can further see that the waves would naturally leave the smooth bottom of each great bay or channel1 as it became slowly converted into land1 gently inclined to as many points as there were mouths1 through which the sea finally retreated1 thus forming so many watersheds1 without any marked ridges1 on a nearly level surface4 ,the absence of marine remains in these high inland plains cannot be properly adduced as an objection to their marine origin3 for we may conclude1 from shells not being found in the great shingle beds of ,patagonia1 though copiously strewed on their surfaces1 and from many other analogous facts1 that such deposits are eminently unfavourable for the embedment of such remains2 and with respect to shells not being found strewed on the surface of these basin-like plains1 it was shown in the last chapter that remains thus exposed in time decay and disappear4 7,,figure #ac4 ,,section ,,of ,,the ,,plain ,,at ,,the ,,eastern ,,foot ,,of ,,the ,,chilean ,,cordillera4 ,from ,cordillera 7left7 through ,talus-plain and ,level surface1 #b1gjj feet above sea1 to ,gravel terraces 7right747 ,i observed some appearances on the plains at the eastern and opposite foot of the ,cordillera which are worth notice1 as showing that the sea there long acted at nearly the same level as on the basin-plains of ,chile4 ,the mountains on this eastern side are exceedingly abrupt2 they rise out of a smooth1 talus-like1 very gentle1 slope1 from five to ten miles in width 7as represented in ,figure #ac71 entirely composed of perfectly rounded pebbles1 often white-washed with an aluminous substance like decomposed feldspar4 ,this sloping plain or talus blends into a perfectly flat space a few miles in width1 composed of reddish impure clay1 with small calcareous concretions as in the ,pampean deposit1--of fine white sand with small pebbles in layers1--and of the above-mentioned white aluminous earth1 all interstratified together4 ,this flat space runs as far as ,mendoza1 thirty miles northward1 and stands probably at about the same height1 namely1 #b1gjj feet 7,pentland and ,miers7 above the sea4 ,to the east it is bounded by an escarpment1 eighty feet in height1 running for many miles north and south1 and composed of perfectly round pebbles1 and loose1 white-washed1 or embedded in the aluminous earth3 behind this escarpment there is a second and similar one of gravel4 ,northward of ,mendoza1 these escarpments become broken and quite obliterated2 and it does not appear that they ever enclosed a lake-like area3 ,i conclude1 therefore1 that they were formed by the sea1 when it reached the foot of the ,cordillera1 like the similar escarpments occurring at so many points on the coasts of ,chile and ,patagonia4 ,the talus-like plain slopes up with a smooth surface into the great dry valleys of the ,cordillera4 ,on each hand of the ,portillo valley1 the mountains are formed of red granite1 mica-slate1 and basalt1 which all have suffered a truly astonishing amount of denudation2 the gravel in the valley1 as well as on the talus-like plain in front of it1 is composed of these rocks2 but at the mouth of the valley1 in the middle 7height probably about three thousand five hundred feet above the sea71 a few small isolated hillocks of several varieties of porphyry project1 round which1 on all sides1 smooth and often white-washed pebbles of these same porphyries1 to the exclusion of all others1 extend to a circumscribed distance4 ,now1 it is difficult to conceive any other agency1 except the quiet and long-continued action of the sea on these hillocks1 which could have rounded and whitewashed the fragments of porphyry1 and caused them to radiate from such small and quite insignificant centres1 in the midst of that vast stream of stones which has descended from the main ,cordillera4 ,,sloping ,,terraces ,,of ,,gravel ,,in ,,the ,,valleys ,,of ,,the ,,cordillera4 7,,figure #ad4 ,,ground-,,plan ,,of ,a ,,bifurcating ,,valley ,,in ,,the ,,cordillera1 bordered by smooth1 sloping gravel-fringes 7,,aa71 worn along the course of the river into cliffs47 ,all the main valleys on both flanks of the ,chilean ,cordillera have formerly had1 or still have1 their bottoms filled up to a considerable thickness by a mass of rudely stratified shingle4 ,in ,central ,chile the greater part of this mass has been removed by the torrents2 cliff-bounded fringes1 more or less continuous1 being left at corresponding heights on both sides of the valleys4 ,these fringes1 or as they may be called terraces1 have a smooth surface1 and as the valleys rise1 they gently rise with them3 hence they are easily irrigated1 and afford great facilities for the construction of the roads4 ,from their uniformity1 they give a remarkable character to the scenery of these grand1 wild1 broken valleys4 ,in width1 the fringes vary much1 sometimes being only broad enough for the roads1 and sometimes expanding into narrow plains4 ,their surfaces1 besides gently rising up the valley1 are slightly inclined towards its centre in such a manner as to show that the whole bottom must once have been filled up with a smooth and slightly concave mass1 as still are the dry unfurrowed valleys of ,northern ,chile4 ,where two valleys unite into one1 these terraces are particularly well exhibited1 as is represented in ,figure #ad4 ,the thickness of the gravel forming these fringes1 on a rude average1 may be said to vary from thirty to sixty or eighty feet2 but near the mouths of the valleys it was in several places from two to three hundred feet4 ,the amount of matter removed by the torrents has been immense2 yet in the lower parts of the valleys the terraces have seldom been entirely worn away on either side1 nor has the solid underlying rock been reached3 higher up the valleys1 the terraces have frequently been removed on one or the other side1 and sometimes on both sides2 but in this latter case they reappear after a short interval on the line1 which they would have held had they been unbroken4 ,where the solid rock has been reached1 it has been cut into deep and narrow gorges4 ,still higher up the valleys1 the terraces gradually become more and more broken1 narrower1 and less thick1 until1 at a height of from seven to nine thousand feet1 they become lost1 and blended with the piles of fallen detritus4 ,i carefully examined in many places the state of the gravel1 and almost everywhere found the pebbles equally and perfectly rounded1 occasionally with great blocks of rock1 and generally distinctly stratified1 often with parting seams of sand4 ,the pebbles were sometimes coated with a white aluminous1 and less frequently with a calcareous1 crust4 ,at great heights up the valleys the pebbles become less rounded2 and as the terraces become obliterated1 the whole mass passes into the nature of ordinary detritus4 ,i was repeatedly struck with the great difference between this detritus high up the valleys1 and the gravel of the terraces low down1 namely1 in the greater number of the quite angular fragments in the detritus1--in the unequal degree to which the other fragments have been rounded1--in the quantity of associated earth1--in the absence of stratification1--and in the irregularity of the upper surfaces4 ,this difference was likewise well shown at points low down the valleys1 where precipitous ravines1 cutting through mountains of highly coloured rock1 have thrown down wide1 fan- shaped accumulations of detritus on the terraces3 in such cases1 the line of separation between the detritus and the terrace could be pointed out to within an inch or two2 the detritus consisting entirely of angular and only partially rounded fragments of the adjoining coloured rocks2 the stratified shingle 7as ,i ascertained by close inspection1 especially in one case1 in the valley of the ,river ,mendoza7 containing only a small proportion of these fragments1 and those few well rounded4 ,i particularly attended to the appearance of the terraces where the valleys made abrupt and considerable bends1 but ,i could perceive no difference in their structure3 they followed the bends with their usual nearly equable inclination4 ,i observed1 also1 in several valleys1 that wherever large blocks of any rock became numerous1 either on the surface of the terrace or embedded in it1 this rock soon appeared higher up in situ3 thus ,i have noticed blocks of porphyry1 of andesitic syenite1 of porphyry and of syenite1 alternately becoming numerous1 and in each case succeeded by mountains thus constituted4 ,there is1 however1 one remarkable exception to this rule2 for along the valley of the ,cachapual1 ,m4 ,gay found numerous large blocks of white granite1 which does not occur in the neighbourhood4 ,i observed these blocks1 as well as others of andesitic syenite 7not occurring here in situ71 near the baths of ,cauquenes at a height of between two and three hundred feet above the river1 and therefore quite above the terrace or fringe which borders that river2 some miles up the valleys there were other blocks at about the same height4 ,i also noticed1 at a less height1 just above the terrace1 blocks of porphyries 7apparently not found in the immediately impending mountains71 arranged in rude lines1 as on a sea-beach4 ,all these blocks were rounded1 and though large1 not gigantic1 like the true erratic boulders of ,patagonia and ,fuegia4 ,m4 ,gay states that the granite does not occur in situ within a distance of twenty leagues 78,annales des ,science ,nat4 8 #a series tome #bh4 ,m4 ,gay1 as ,i was informed1 penetrated the ,cordillera by the great oblique valley of ,los ,cupressos1 and not by the most direct line472 ,i suspect1 for several reasons1 that it will ultimately be found at a much less distance1 though certainly not in the immediate neighbourhood4 ,the boulders found by ,,mm4 ,meyen and ,gay on the upper plain of ,san ,fernando 7mentioned in a previous note7 probably belong to this same class of phenomena4 ,these fringes of stratified gravel occur along all the great valleys of the ,cordillera1 as well as along their main branches2 they are strikingly developed in the valleys of the ,maypu1 ,mendoza1 ,aconcagua1 ,cachapual1 and according to ,meyen1 in the ,tinguirica4 78,reise0 etc4 ,th4 #a s4 #cjb47 ,in the valleys1 however1 of ,northern ,chile1 and in some on the eastern flank of the ,cordillera1 as in the ,portillo ,valley1 where streams have never flowed1 or are quite insignificant in volume1 the presence of a mass of stratified gravel can be inferred only from the smooth slightly concave form of the bottom4 ,one naturally seeks for some explanation of so general and striking a phenomenon2 that the matter forming the fringes along the valleys1 or still filling up their entire beds1 has not fallen from the adjoining mountains like common detritus1 is evident from the complete contrast in every respect between the gravel and the piles of detritus1 whether seen high up the valleys on their sides1 or low down in front of the more precipitous ravines2 that the matter has not been deposited by debacles1 even if we could believe in debacles having rushed down ,,every valley1 and all their branches1 eastward and westward from the central pinnacles of the ,cordillera1 we must admit from the following reasons1--from the distinct stratification of the mass1--its smooth upper surface1--the well-rounded and sometimes encrusted state of the pebbles1 so different from the loose debris on the mountains1--and especially from the terraces preserving their uniform inclination round the most abrupt bends4 ,to suppose that as the land now stands1 the rivers deposited the shingle along the course of every valley1 and all their main branches1 appears to me preposterous1 seeing that these same rivers not only are now removing and have removed much of this deposit1 but are everywhere tending to cut deep and narrow gorges in the hard underlying rocks4 ,i have stated that these fringes of gravel1 the origin of which are inexplicable on the notion of debacles or of ordinary alluvial action1 are directly continuous with the similarly-composed basin-like plains at the foot of the ,cordillera1 which1 from the several reasons before assigned1 ,i cannot doubt were modelled by the agency of the sea4 ,now if we suppose that the sea formerly occupied the valleys of the ,chilean ,cordillera1 in precisely the same manner as it now does in the more southern parts of the continent1 where deep winding creeks penetrate into the very heart of1 and in the case of ,obstruction ,sound quite through1 this great range2 and if we suppose that the mountains were upraised in the same slow manner as the eastern and western coasts have been upraised within the recent period1 then the origin and formation of these sloping1 terrace-like fringes of gravel can be simply explained4 ,for every part of the bottom of each valley will1 on this view1 have long stood at the head of a sea creek1 into which the then existing torrents will have delivered fragments of rocks1 where1 by the action of the tides1 they will have been rolled1 sometimes encrusted1 rudely stratified1 and the whole surface levelled by the blending together of the successive beach lines4 7,sloping terraces of precisely similar structure have been described by me 8,philosophical ,transactions0 #ahci page #eh1 in the valleys of ,lochaber in ,scotland1 where1 at higher levels1 the parallel roads of ,glen ,roy show the marks of the long and quiet residence of the sea4 ,i have no doubt that these sloping terraces would have been present in the valleys of most of the ,european ranges1 had not every trace of them1 and all wrecks of sea-action1 been swept away by the glaciers which have since occupied them4 ,i have shown that this is the case with the mountains 78,london and ,edinburgh ,philosophical ,journal0 volume #ba page #ahg7 of ,north ,wales47 ,as the land rose1 the torrents in every valley will have tended to have removed the matter which just before had been arrested on1 or near1 the beach-lines2 the torrents1 also1 having continued to gain in force by the continued elevation increasing their total descent from their sources to the sea4 ,this slow rising of the ,cordillera1 which explains so well the otherwise inexplicable origin and structure of the terraces1 judging from all known analogies1 will probably have been interrupted by many periods of rest2 but we ought not to expect to find any evidence of these periods in the structure of the gravel- terraces3 for1 as the waves at the heads of deep creeks have little erosive power1 so the only effect of the sea having long remained at the same level will be that the upper parts of the creeks will have become filled up at such periods to the level of the water with gravel and sand2 and that afterwards the rivers will have thrown down on the filled-up parts a talus of similar matter1 of which the inclination 7as at the head of a partially filled-up lake7 will have been determined by the supply of detritus1 and the force of the stream4 7,i have attempted to explain this process in a more detailed manner1 in a letter to ,mr4 ,maclaren1 published in the 8,edinburgh ,new ,philosophical ,journal0 volume #ce page #bhh47 ,hence1 after the final conversion of the creeks into valleys1 almost the only difference in the terraces at those points at which the sea stood long1 will be a somewhat more gentle inclination1 with river-worn instead of sea-worn detritus on the surface4 ,i know of only one difficulty on the foregoing view1 namely1 the far- transported blocks of rock high on the sides of the valley of the ,cachapual3 ,i will not attempt any explanation of this phenomenon1 but ,i may state my belief that a mountain-ridge near the ,baths of ,cauquenes has been upraised long subsequently to all the other ranges in the neighbourhood1 and that when this was effected the whole face of the country must have been greatly altered4 ,in the course of ages1 moreover1 in this and other valleys1 events may have occurred like1 but even on a grander scale than1 that described by ,molina1 when a slip during the earthquake of #agfb banked up for ten days the great ,river ,lontue1 which then bursting its barrier 8inundated the whole country10 and doubtless transported many great fragments of rock4 78,compendio de la ,hist40 etc4 etc4 tome #a page #cj4 ,m4 ,brongniart1 in his report on ,m4 ,gay's labours 8,annales des ,sciences0 #ahcc1 considers that the boulders in the ,cachapual belong to the same class with the erratic boulders of ,europe4 ,as the blocks which ,i saw are not gigantic1 and especially as they are not angular1 and as they have not been transported fairly across low spaces or wide valleys1 ,i am unwilling to class them with those which1 both in the northern and southern hemisphere 8,geological ,transactions0 volume #f page #dae1 have been transported by ice4 ,it is to be hoped that when ,m4 ,gay's long-continued and admirable labours in ,chile are published1 more light will be thrown on this subject4 ,however1 the boulders may have been primarily transported2 the final position of those of porphyry1 which have been described as arranged at the foot of the mountain in rude lines1 ,i cannot doubt1 has been due to the action of waves on a beach4 ,the valley of the ,cachapual1 in the part where the boulders occur1 bursts through the high ridge of ,cauquenes1 which runs parallel to1 but at some distance from1 the ,cordillera4 ,this ridge has been subjected to excessive violence2 trachytic lava has burst from it1 and hot springs yet flow at its base4 ,seeing the enormous amount of denudation of solid rock in the upper and much broader parts of this valley where it enters the ,cordillera1 and seeing to what extent the ridge of ,cauquenes now protects the great range1 ,i could not help believing 7as alluded to in the text7 that this ridge with its trachytic eruptions had been thrown up at a much later period than the ,cordillera4 ,if this has been the case1 the boulders1 after having been transported to a low level by the torrents 7which exhibit in every valley proofs of their power of moving great fragments71 may have been raised up to their present height1 with the land on which they rested47 ,finally1 notwithstanding this one case of difficulty1 ,i cannot entertain any doubt1 that these terrace-like fringes1 which are continuously united with the basin-shaped plains at the foot of the ,cordillera1 have been formed by the arrestment of river-borne detritus at successive levels1 in the same manner as we see now taking place at the heads of all those many1 deep1 winding fiords intersecting the southern coasts4 ,to my mind1 this has been one of the most important conclusions to which my observations on the geology of ,south ,america have led me2 for we thus learn that one of the grandest and most symmetrical mountain-chains in the world1 with its several parallel lines1 has been together uplifted in mass between seven and nine thousand feet1 in the same gradual manner as have the eastern and western coasts within the recent period4 7,i do not wish to affirm that all the lines have been uplifted quite equally2 slight differences in the elevation would leave no perceptible effect on the terraces4 ,it may1 however1 be inferred1 perhaps with one exception1 that since the period when the sea occupied these valleys1 the several ranges have not been dislocated by ,,great and ,,abrupt faults or upheavals2 for if such had occurred1 the terraces of gravel at these points would not have been continuous4 ,the one exception is at the lower end of a plain in the ,valle del ,yeso 7a branch of the ,maypu71 where1 at a great height1 the terraces and valley appear to have been broken through by a line of upheaval1 of which the evidence is plain in the adjoining mountains2 this dislocation1 perhaps1 occurred ,,after ,,the ,,elevation of this part of the valley above the level of the sea4 ,the valley here is almost blocked up by a pile about one thousand feet in thickness1 formed1 as far as ,i could judge1 from three sides1 entirely1 or at least in chief part1 of gravel and detritus4 ,on the south side1 the river has cut quite through this mass2 on the northern side1 and on the very summit1 deep ravines1 parallel to the line of the valley1 are worn1 as if the drainage from the valley above had passed by these two lines before following its present course47 ,,formation ,,of ,,valleys4 ,the bulk of solid rock which has been removed in the lower parts of the valleys of the ,cordillera has been enormous4 ,it is only by reflecting on such cases as that of the gravel beds of ,patagonia1 covering so many thousand square leagues of surface1 and which1 if heaped into a ridge1 would form a mountain-range almost equal to the ,cordillera1 that the amount of denudation becomes credible4 ,the valleys within this range often follow anticlinal but rarely synclinal lines2 that is1 the strata on the two sides more often dip from the line of valley than towards it4 ,on the flanks of the range1 the valleys most frequently run neither along anticlinal nor synclinal axes1 but along lines of flexure or faults3 that is1 the strata on both sides dip in the same direction1 but with different1 though often only slightly different1 inclinations4 ,as most of the nearly parallel ridges which together form the ,cordillera run approximately north and south1 the east and west valleys cross them in zig-zag lines1 bursting through the points where the strata have been least inclined4 ,no doubt the greater part of the denudation was affected at the periods when tidal- creeks occupied the valleys1 and when the outer flanks of the mountains were exposed to the full force of an open ocean4 ,i have already alluded to the power of the tidal action in the channels connecting great bays2 and ,i may here mention that one of the surveying vessels in a channel of this kind1 though under sail1 was whirled round and round by the force of the current4 ,we shall hereafter see1 that of the two main ridges forming the ,chilean ,cordillera1 the eastern and loftiest one owes the greater part of its ,,angular upheaval to a period subsequent to the elevation of the western ridge2 and it is likewise probable that many of the other parallel ridges have been angularly upheaved at different periods2 consequently many parts of the surfaces of these mountains must formerly have been exposed to the full force of the waves1 which1 if the ,cordillera were now sunk into the sea1 would be protected by parallel chains of islands4 ,the torrents in the valleys certainly have great power in wearing the rocks2 as could be told by the dull rattling sound of the many fragments night and day hurrying downwards2 and as was attested by the vast size of certain fragments1 which ,i was assured had been carried onwards during floods2 yet we have seen in the lower parts of the valleys1 that the torrents have seldom removed all the sea-checked shingle forming the terraces1 and have had time since the last elevation in mass only to cut in the underlying rocks1 gorges1 deep and narrow1 but quite insignificant in dimensions compared with the entire width and depth of the valleys4 ,along the shores of the ,pacific1 ,i never ceased during my many and long excursions to feel astonished at seeing every valley1 ravine1 and even little inequality of surface1 both in the hard granitic and soft tertiary districts1 retaining the exact outline1 which they had when the sea left their surfaces coated with organic remains4 ,when these remains shall have decayed1 there will be scarcely any difference in appearance between this line of coast-land and most other countries1 which we are accustomed to believe have assumed their present features chiefly through the agency of the weather and fresh-water streams4 ,in the old granitic districts1 no doubt it would be rash to attribute all the modifications of outline exclusively to the sea-action2 for who can say how often this lately submerged coast may not previously have existed as land1 worn by running streams and washed by rain8 ,this source of doubt1 however1 does not apply to the districts superficially formed of the modern tertiary deposits4 ,the valleys worn by the sea1 through the softer formations1 both on the ,atlantic and ,pacific sides of the continent1 are generally broad1 winding1 and flat-bottomed3 the only district of this nature now penetrated by arms of the sea1 is the island of ,chiloe4 ,finally1 the conclusion at which ,i have arrived1 with respect to the relative powers of rain and sea water on the land1 is1 that the latter is far the most efficient agent1 and that its chief tendency is to widen the valleys2 whilst torrents and rivers tend to deepen them1 and to remove the wreck of the sea's destroying action4 ,as the waves have more power1 the more open and exposed the space may be1 so will they always tend to widen more and more the mouths of valleys compared with their upper parts3 hence1 doubtless1 it is1 that most valleys expand at their mouths1--that part1 at which the rivers flowing in them1 generally have the least wearing power4 ,when reflecting on the action of the sea on the land at former levels1 the effect of the great waves1 which generally accompany earthquakes1 must not be overlooked3 few years pass without a severe earthquake occurring on some part of the west coast of ,south ,america2 and the waves thus caused have great power4 ,at ,concepcion1 after the shock of #ahce1 ,i saw large slabs of sandstone1 one of which was six feet long1 three in breadth1 and two in thickness1 thrown high up on the beach2 and from the nature of the marine animals still adhering to it1 it must have been torn up from a considerable depth4 ,on the other hand1 at ,callao1 the recoil-wave of the earthquake of #agdf carried great masses of brickwork1 between three and four feet square1 some way out seaward4 ,during the course of ages1 the effect thus produced at each successive level1 cannot have been small2 and in some of the tertiary deposits on this line of coast1 ,i observed great boulders of granite and other neighbouring rocks1 embedded in fine sedimentary layers1 the transportal of which1 except by the means of earthquake-waves1 always appeared to me inexplicable4 ,,superficial ,,saline ,,deposits4 ,this subject may be here conveniently treated of3 ,i will begin with the most interesting case1 namely1 the superficial saline beds near ,iquique in ,peru4 ,the porphyritic mountains on the coast rise abruptly to a height of between one thousand nine hundred and three thousand feet3 between their summits and an inland plain1 on which the celebrated deposit of nitrate of soda lies1 there is a high undulatory district1 covered by a remarkable superficial saliferous crust1 chiefly composed of common salt1 either in white1 hard1 opaque nodules1 or mingled with sand1 in this latter case forming a compact sandstone4 ,this saliferous superficial crust extends from the edge of the coast-escarpment1 over the whole face of the country2 but never attains1 as ,i am assured by ,mr4 ,bollaert 7long resident here7 any great thickness4 ,although a very slight shower falls only at intervals of many years1 yet small funnel-shaped cavities show that the salt has been in some parts dissolved4 7,it is singular how slowly1 according to the observations of ,m4 ,cordier on the salt-mountain of ,cardona in ,spain 8,ann4 des ,mines1 ,translation of ,geolog4 ,mem40 by ,de la ,beche page #fj1 salt is dissolved1 where the amount of rain is supposed to be as much as #ca4d of an inch in the year4 ,it is calculated that only five feet in thickness is dissolved in the course of a century47 ,in several places ,i saw large patches of sand1 quite moist1 owing to the quantity of muriate of lime 7as ascertained by ,mr4 ,t4 ,reeks7 contained in them4 ,from the compact salt- cemented sand being either red1 purplish1 or yellow1 according to the colour of the rocky strata on which it rested1 ,i imagined that this substance had probably been derived through common alluvial action from the layers of salt which occur interstratified in the surrounding mountains 78,journal of ,researches0 page #ddd first edition473 but from the interesting details given by ,m4 d',orbigny1 and from finding on a fresh examination of this agglomerated sand1 that it is not irregularly cemented1 but consists of thin layers of sand of different tints of colour1 alternating with excessively fine parallel layers of salt1 ,i conclude that it is not of alluvial origin4 ,m4 d',orbigny observed analogous saline beds extending from ,cobija for five degrees of latitude northward1 and at heights varying from six hundred to nine hundred feet 78,voyage0 etc4 page #ajb4 ,m4 d',orbigny found this deposit intersected1 in many places1 by deep ravines1 in which there was no salt4 ,streams must once1 though historically unknown1 have flowed in them2 and ,m4 d',orbigny argues from the presence of undissolved salt over the whole surrounding country1 that the streams must have arisen from rain or snow having fallen1 not in the adjoining country1 but on the now arid ,cordillera4 ,i may remark1 that from having observed ruins of ,indian buildings in absolutely sterile parts of the ,chilian ,cordillera 78,journal0 #bnd edition page #ceg71 ,i am led to believe that the climate1 at a time when ,indian man inhabited this part of the continent1 was in some slight degree more humid than it is at present473 from finding recent sea- shells strewed on these saliferous beds1 and under them1 great well-rounded blocks1 exactly like those on the existing beach1 he believes that the salt1 which is invariably superficial1 has been left by the evaporation of the sea-water4 ,this same conclusion must1 ,i now believe1 be extended to the superficial saliferous beds of ,iquique1 though they stand about three thousand feet above the level of the sea4 ,associated with the salt in the superficial beds1 there are numerous1 thin1 horizontal layers of impure1 dirty-white1 friable1 gypseous and calcareous tuffs4 ,the gypseous beds are very remarkable1 from abounding with1 so as sometimes to be almost composed of1 irregular concretions1 from the size of an egg to that of a man's head1 of very hard1 compact1 heavy gypsum1 in the form of anhydrite4 ,this gypsum contains some foreign particles of stone2 it is stained1 judging from its action with borax1 with iron1 and it exhales a strong aluminous odour4 ,the surfaces of the concretions are marked by sharp1 radiating1 or bifurcating ridges1 as if they had been 7but not really7 corroded3 internally they are penetrated by branching veins 7like those of calcareous spar in the septaria of the ,london clay7 of pure white anhydrite4 ,these veins might naturally have been thought to have been formed by subsequent infiltration1 had not each little embedded fragment of rock been likewise edged in a very remarkable manner by a narrow border of the same white anhydrite3 this shows that the veins must have been formed by a process of segregation1 and not of infiltration4 ,some of the little included and ,,cracked fragments of foreign rock are penetrated by the anhydrite1 and portions have evidently been thus mechanically displaced3 at ,st4 ,helena1 ,i observed that calcareous matter1 deposited by rain water1 also had the power to separate small fragments of rock from the larger masses4 78,volcanic ,islands0 etc4 page #hg47 ,i believe the superficial gypseous deposit is widely extended3 ,i received specimens of it from ,pisagua1 forty miles north of ,iquique1 and likewise from ,arica1 where it coats a layer of pure salt4 ,m4 d',orbigny found at ,cobija a bed of clay1 lying above a mass of upraised recent shells1 which was saturated with sulphate of soda1 and included thin layers of fibrous gypsum4 78,voyage ,geolog40 etc4 page #ie47 ,these widely extended1 superficial1 beds of salt and gypsum1 appear to me an interesting geological phenomenon1 which could be presented only under a very dry climate4 ,the plain or basin1 on the borders of which the famous bed of nitrate of soda lies1 is situated at the distance of about thirty miles from the sea1 being separated from it by the saliferous district just described4 ,it stands at a height of #c1cjj feet2 its surface is level1 and some leagues in width2 it extends forty miles northward1 and has a total length 7as ,i was informed by ,mr4 ,belford ,wilson1 the ,consul-,general at ,lima7 of #dbj miles4 ,in a well near the works1 thirty-six yards in depth1 sand1 earth1 and a little gravel were found3 in another well1 near ,almonte1 fifty yards deep1 the whole consisted1 according to ,mr4 ,blake1 of clay1 including a layer of sand two feet thick1 which rested on fine gravel1 and this on coarse gravel1 with large rounded fragments of rock4 7,see an admirable paper 8,geological and ,miscellaneous ,notices of ,tarapaca0 in 8,silliman's ,american ,journal0 volume #dd page #a47 ,in many parts of this now utterly desert plain1 rushes and large prostrate trees in a hardened state1 apparently ,mimosas1 are found buried1 at a depth from three to six feet2 according to ,mr4 ,blake1 they have all fallen to the south-west4 ,the bed of nitrate of soda is said to extend for forty to fifty leagues along the western margin of the plain1 but is not found in its central parts3 it is from two to three feet in thickness1 and is so hard that it is generally blasted with gunpowder2 it slopes gently upwards from the edge of the plain to between ten and thirty feet above its level4 ,it rests on sand in which1 it is said1 vegetable remains and broken shells have been found2 shells have also been found1 according to ,mr4 ,blake1 both on and in the nitrate of soda4 ,it is covered by a superficial mass of sand1 containing nodules of common salt1 and1 as ,i was assured by a miner1 much soft gypseous matter1 precisely like that in the superficial crust already described3 certainly this crust1 with its characteristic concretions of anhydrite1 comes close down to the edge of the plain4 ,the nitrate of soda varies in purity in different parts1 and often contains nodules of common salt4 ,according to ,mr4 ,blake1 the proportion of nitrate of soda varies from #bj to #ge per cent4 ,an analysis by ,mr4 ,a4 ,hayes1 of an average specimen1 gave3-- ,nitrate of ,soda4444 #fd4ih ,sulphate of ,soda4444 #c4jj ,chloride of ,soda444 #bh4fi ,iodic ,salts444444444 #j4fc ,shells and ,marl44444 #b4fj #ii4ij ,the 8mother-water0 at some of the refineries is very rich in iodic salts1 and is supposed to contain much muriate of lime4 78,literary ,gazette0 #ahda page #dge47 ,in an unrefined specimen brought home by myself1 ,mr4 ,t4 ,reeks has ascertained that the muriate of lime is very abundant4 ,with respect to the origin of this saline mass1 from the manner in which the gently inclined1 compact bed follows for so many miles the sinuous margin of the plain1 there can be no doubt that it was deposited from a sheet of water3 from the fragments of embedded shells1 from the abundant iodic salts1 from the superficial saliferous crust occurring at a higher level and being probably of marine origin1 and from the plain resembling in form those of ,chile and that of ,uspallata1 there can be little doubt that this sheet of water was1 at least originally1 connected with the sea4 7,from an official document1 shown me by ,mr4 ,belford ,wilson1 it appears that the first export of nitrate of soda to ,europe was in ,july #ahcj1 on ,french account1 in a ,british ship3-- ,in year1 the entire export was in ,quintals4 #ahcj4444444444444444444444444444 #ag1cjj #ahca4444444444444444444444444444 #dj1hhe #ahcb4444444444444444444444444444 #ea1djj #ahcc4444444444444444444444444444 #ia1cce #ahcd444444444444444444444444444 #adi1ech ,the ,spanish quintal nearly equals #ajj ,english pounds47 ,,thin1 ,,superficial1 ,,saline ,,incrustations4 ,these saline incrustations are common in many parts of ,america3 ,humboldt met with them on the tableland of ,mexico1 and the ,jesuit ,falkner and other authors state that they occur at intervals over the vast plains extending from the mouth of the ,plata to ,rioja and ,catamarca4 7,azara 8,travels0 volume #a page #ee1 considers that the ,parana is the eastern boundary of the saliferous region2 but ,i heard of 8salitrales0 in the ,province of ,entre ,rios47 ,hence it is that during droughts1 most of the streams in the ,pampas are saline4 ,i nowhere met with these incrustations so abundantly as near ,bahia ,blanca3 square miles of the mud-flats1 which near that place are raised only a few feet above the sea1 just enough to protect them from being overflowed1 appear1 after dry weather1 whiter than the ground after the thickest hoar-frost4 ,after rain the salts disappear1 and every puddle of water becomes highly saline2 as the surface dries1 the capillary action draws the moisture up pieces of broken earth1 dead sticks1 and tufts of grass1 where the salt effloresces4 ,the incrustation1 where thickest1 does not exceed a quarter of an inch4 ,m4 ,parchappe has analysed it 7,m4 d',orbigny 8,voyage0 etc4 ,part4 ,hist4 tome #a page #ffd472 and finds that the specimens collected at the extreme head of the low plain1 near the ,river ,manuello1 consist of #ic per cent of sulphate of soda1 and #g of common salt2 whilst the specimens taken close to the coast contain only #fc per cent of the sulphate1 and #cg of the muriate of soda4 ,this remarkable fact1 together with our knowledge that the whole of this low muddy plain has been covered by the sea within the recent period1 must lead to the suspicion that the common salt1 by some unknown process1 becomes in time changed into the sulphate4 ,friable1 calcareous matter is here abundant1 and the case of the apparent double decomposition of the shells and salt on ,san ,lorenzo1 should not be forgotten4 ,the saline incrustations1 near ,bahia ,blanca1 are not confined to1 though most abundant on1 the low muddy flats2 for ,i noticed some on a calcareous plain between thirty and forty feet above the sea1 and even a little occurs in still higher valleys4 ,low alluvial tracts in the valleys of the ,rivers ,negro and ,colorado are also encrusted1 and in the latter valley such spaces appeared to be occasionally overflowed by the river4 ,i observed saline incrustations in some of the valleys of ,southern ,patagonia4 ,at ,port ,desire a low1 flat1 muddy valley was thickly incrusted by salts1 which on analysis by ,mr4 ,t4 ,reeks1 are found to consist of a mixture of sulphate and muriate of soda1 with carbonate of lime and earthy matter4 ,on the western side of the continent1 the southern coasts are much too humid for this phenomenon2 but in ,northern ,chile ,i again met with similar incrustations4 ,on the hardened mud1 in parts of the broad1 flat-bottomed valley of ,copiapo1 the saline matter encrusts the ground to the thickness of some inches3 specimens1 sent by ,mr4 ,bingley to ,apothecaries' ,hall for analysis1 were said to consist of carbonate and sulphate of soda4 ,much sulphate of soda is found in the desert of ,atacama4 ,in all parts of ,south ,america1 the saline incrustations occur most frequently on low damp surfaces of mud1 where the climate is rather dry2 and these low surfaces have1 in almost every case1 been upraised above the level of the sea1 within the recent period4 ,,salt-,,lakes ,,of ,,patagonia ,,and ,,la ,,plata4 ,salinas1 or natural salt-lakes1 occur in various formations on the eastern side of the continent1--in the argillaceo-calcareous deposit of the ,pampas1 in the sandstone of the ,rio ,negro1 where they are very numerous1 in the pumiceous and other beds of the ,patagonian tertiary formation1 and in small primary districts in the midst of this latter formation4 ,port ,s4 ,julian is the most southerly point 7latitude #di degrees to #ej degrees7 at which salinas are known to occur4 7,according to ,azara 8,travels0 volume #a page #ef1 there are salt-lakes as far north as ,chaco 7latitude #be degrees71 on the banks of the ,vermejo4 ,the salt-lakes of ,siberia appear 7,pallas 8,travels0 ,english ,translation volume #a page #bhd7 to occur in very similar depressions to those of ,patagonia47 ,the depressions1 in which these salt-lakes lie1 are from a few feet to sixty metres1 as asserted by ,m4 d',orbigny1 below the surface of the surrounding plains 78,voyage ,geolog40 page #fc472 and1 according to this same author1 near the ,rio ,negro they all trend1 either in the ,n4,e4 and ,s4,w4 or in ,e4 and ,w4 lines1 coincident with the general slope of the plain4 ,these depressions in the plain generally have one side lower than the others1 but there are no outlets for drainage4 ,under a less dry climate1 an outlet would soon have been formed1 and the salt washed away4 ,the salinas occur at different elevations above the sea2 they are often several leagues in diameter2 they are generally very shallow1 but there is a deep one in a quartz-rock formation near ,c4 ,blanco4 ,in the wet season1 the whole1 or a part1 of the salt is dissolved1 being redeposited during the succeeding dry season4 ,at this period the appearance of the snow-white expanse of salt crystallised in great cubes1 is very striking4 ,in a large salina1 northward of the ,rio ,negro1 the salt at the bottom1 during the whole year1 is between two and three feet in thickness4 ,the salt rests almost always on a thick bed of black muddy sand1 which is fetid1 probably from the decay of the burrowing worms inhabiting it4 7,professor ,ehrenberg examined some of this muddy sand1 but was unable to find in it any infusoria47 ,in a salina1 situated about fifteen miles above the town of ,el ,carmen on the ,rio ,negro1 and three or four miles from the banks of that river1 ,i observed that this black mud rested on gravel with a calcareous matrix1 similar to that spread over the whole surrounding plains3 at ,port ,s4 ,julian the mud1 also1 rested on the gravel3 hence the depressions must have been formed anteriorly to1 or contemporaneously with1 the spreading out of the gravel4 ,i was informed that one small salina occurs in an alluvial plain within the valley of the ,rio ,negro1 and therefore its origin must be subsequent to the excavation of that valley4 ,when ,i visited the salina1 fifteen miles above the town1 the salt was beginning to crystallise1 and on the muddy bottom there were lying many crystals1 generally placed crossways of sulphate of soda 7as ascertained by ,mr4 ,reeks71 and embedded in the mud1 numerous crystals of sulphate of lime1 from one to three inches in length3 ,m4 d',orbigny states that some of these crystals are acicular and more than even nine inches in length 78,voyage ,geolog40 page #fd472 others are macled and of great purity3 those ,i found all contained some sand in their centres4 ,as the black and fetid sand overlies the gravel1 and that overlies the regular tertiary strata1 ,i think there can be no doubt that these remarkable crystals of sulphate of lime have been deposited from the waters of the lake4 ,the inhabitants call the crystals of selenite1 the padre del sal1 and those of the sulphate of soda1 the madre del sal2 they assured me that both are found under the same circumstances in several of the neighbouring salinas2 and that the sulphate of soda is annually dissolved1 and is always crystallised before the common salt on the muddy bottom4 7,this is what might have been expected2 for ,m4 ,ballard asserts 8,acad4 des ,sciences0 ,october #g1 #ahdd1 that sulphate of soda is precipitated from solution more readily from water containing muriate of soda in excess1 than from pure water47 ,the association of gypsum and salt in this case1 as well as in the superficial deposits of ,iquique1 appears to me interesting1 considering how generally these substances are associated in the older stratified formations4 ,mr4 ,reeks has analysed for me some of the salt from the salina near the ,rio ,negro2 he finds it composed entirely of chloride of sodium1 with the exception of #j4bf of sulphate of lime and of #j4bb of earthy matter3 there are no traces of iodic salts4 ,some salt from the salina ,chiquitos1 in the ,pampean formation1 is equally pure4 ,it is a singular fact1 that the salt from these salinas does not serve so well for preserving meat1 as sea-salt from the ,cape de ,verde ,islands2 and a merchant at ,buenos ,ayres told me that he considered it as #ej per cent less valuable4 ,the purity of the ,patagonian salt1 or absence from it of those other saline bodies found in all sea- water1 is the only assignable cause for this inferiority2 a conclusion which is supported by the fact lately ascertained1 that those salts answer best for preserving cheese which contain most of the deliquescent chlorides4 78,horticultural and ,agricultural ,gazette0 #ahde page #ic47 7,it would probably well answer for the merchants of ,buenos ,ayres 7considering the great consumption there of salt for preserving meat7 to import the deliquescent chlorides to mix with the salt from the salinas3 ,i may call attention to the fact1 that at ,iquique1 a large quantity of muriate of lime1 left in the ,,mother-,,water during the refinement of the nitrate of soda1 is annually thrown away47 ,with respect to the origin of the salt in the salinas1 the foregoing analysis seems opposed to the view entertained by ,m4 d',orbigny and others1 and which seems so probable considering the recent elevation of this line of coast1 namely1 that it is due to the evaporation of sea-water and to the drainage from the surrounding strata impregnated with sea-salt4 ,i was informed 7,i know not whether accurately7 that on the northern side of the salina on the ,rio ,negro1 there is a small brine spring which flows at all times of the year3 if this be so1 the salt in this case at least1 probably is of subterranean origin4 ,it at first appears very singular that fresh water can often be procured in wells1 and is sometimes found in small lakes1 quite close to these salinas4 7,sir ,w4 ,parish states 8,buenos ,ayres0 etc4 pages #abb and #agj1 that this is the case near the great salinas westward of the ,s4 ,ventana4 ,i have seen similar statements in an ancient ,,ms4 ,journal lately published by ,s4 ,angelis4 ,at ,iquique1 where the surface is so thickly encrusted with saline matter1 ,i tasted water only slightly brackish1 procured in a well thirty-six yards deep2 but here one feels less surprise at its presence1 as pure water might percolate under ground from the not very distant ,cordillera47 ,i am not aware that this fact bears particularly on the origin of the salt2 but perhaps it is rather opposed to the view of the salt having been washed out of the surrounding superficial strata1 but not to its having been the residue of sea-water1 left in depressions as the land was slowly elevated4 ,,chapter ,,iv4 ,,on ,,the ,,formations ,,of ,,the ,,pampas4 ,mineralogical constitution4--,microscopical structure4--,buenos ,ayres1 shells embedded in tosca-rock4--,buenos ,ayres to the ,colorado4--,san ,ventana4--,bahia ,blanca2 ,m4 ,hermoso1 bones and infusoria of2 ,p4 ,alta1 shells1 bones and infusoria of2 co-existence of the recent shells and extinct mammifers4--,buenos ,ayres to ,santa ,f4--,skeletons of ,mastodon4--,infusoria4--,inferior marine tertiary strata1 their age4--,horse's tooth4--,,banda ,,oriental4--,superficial ,pampean formation4--,inferior tertiary strata1 variation of1 connected with volcanic action2 ,macrauchenia ,patachonica at ,san ,julian in ,patagonia1 age of1 subsequent to living mollusca and to the erratic block period4 ,,summary4--,area of ,pampean formation4--,theories of origin4--,source of sediment4--,estuary origin4--,contemporaneous with existing mollusca4--,relations to underlying tertiary strata4--,ancient deposit of estuary origin4--,elevation and successive deposition of the ,pampean formation4--,number and state of the remains of mammifers2 their habitation1 food1 extinction1 and range4--,conclusion4--,localities in ,pampas at which mammiferous remains have been found4 ,the ,pampean formation is highly interesting from its vast extent1 its disputed origin1 and from the number of extinct gigantic mammifers embedded in it4 ,it has upon the whole a very uniform character3 consisting of a more or less dull reddish1 slightly indurated1 argillaceous earth or mud1 often1 but not always1 including in horizontal lines concretions of marl1 and frequently passing into a compact marly rock4 ,the mud1 wherever ,i examined it1 even close to the concretions1 did not contain any carbonate of lime4 ,the concretions are generally nodular1 sometimes rough externally1 sometimes stalactiformed2 they are of a compact structure1 but often penetrated 7as well as the mud7 by hair-like serpentine cavities1 and occasionally with irregular fissures in their centres1 lined with minute crystals of carbonate of lime2 they are of white1 brown1 or pale pinkish tints1 often marked by black dendritic manganese or iron2 they are either darker or lighter tinted than the surrounding mass2 they contain much carbonate of lime1 but exhale a strong aluminous odour1 and leave1 when dissolved in acids1 a large but varying residue1 of which the greater part consists of sand4 ,these concretions often unite into irregular strata2 and over very large tracts of country1 the entire mass consists of a hard1 but generally cavernous marly rock3 some of the varieties might be called calcareous tuffs4 ,dr4 ,carpenter has kindly examined under the microscope1 sliced and polished specimens of these concretions1 and of the solid marl-rock1 collected in various places between the ,colorado and ,santa ,fe ,bajada4 ,in the greater number1 ,dr4 ,carpenter finds that the whole substance presents a tolerably uniform amorphous character1 but with traces of incipient crystalline metamorphosis2 in other specimens he finds microscopically minute rounded concretions of an amorphous substance 7resembling in size those in oolitic rocks1 but not having a concentric structure71 united by a cement which is often crystalline4 ,in some1 ,dr4 ,carpenter can perceive distinct traces of shells1 corals1 ,polythalamia1 and rarely of spongoid bodies4 ,for the sake of comparison1 ,i sent ,dr4 ,carpenter specimens of the calcareous rock1 formed chiefly of fragments of recent shells1 from ,coquimbo in ,chile3 in one of these specimens1 ,dr4 ,carpenter finds1 besides the larger fragments1 microscopical particles of shells1 and a varying quantity of opaque amorphous matter2 in another specimen from the same bed1 he finds the whole composed of the amorphous matter1 with layers showing indications of an incipient crystalline metamorphosis3 hence these latter specimens1 both in external appearance and in microscopical structure1 closely resemble those of the ,pampas4 ,dr4 ,carpenter informs me that it is well known that chemical precipitation throws down carbonate of lime in the opaque amorphous state2 and he is inclined to believe that the long-continued attrition of a calcareous body in a state of crystalline or semi-crystalline aggregation 7as1 for instance1 in the ordinary shells of ,mollusca1 which1 when sliced1 are transparent7 may yield the same result4 ,from the intimate relations between all the ,coquimbo specimens1 ,i can hardly doubt that the amorphous carbonate of lime in them has resulted from the attrition and decay of the larger fragments of shell3 whether the amorphous matter in the marly rocks of the ,pampas has likewise thus originated1 it would be hazardous to conjecture4 ,for convenience' sake1 ,i will call the marly rock by the name given to it by the inhabitants1 namely1 ,tosca-rock2 and the reddish argillaceous earth1 ,pampean mud4 ,this latter substance1 ,i may mention1 has been examined for me by ,professor ,ehrenberg1 and the result of his examination will be given under the proper localities4 ,i will commence my descriptions at a central spot1 namely1 at ,buenos ,ayres1 and thence proceed first southward to the extreme limit of the deposit1 and afterwards northward4 ,the plain on which ,buenos ,ayres stands is from thirty to forty feet in height4 ,the ,pampean mud is here of a rather pale colour1 and includes small nearly white nodules1 and other irregular strata of an unusually arenaceous variety of tosca-rock4 ,in a well at the depth of seventy feet1 according to ,ignatio ,nunez1 much tosca-rock was met with1 and at several points1 at one hundred feet deep1 beds of sand have been found4 ,i have already given a list of the recent marine and estuary shells found in many parts on the surface near ,buenos ,ayres1 as far as three or four leagues from the ,plata4 ,specimens from near ,ensenada1 given me by ,sir ,w4 ,parish1 where the rock is quarried just beneath the surface of the plain1 consist of broken bivalves1 cemented by and converted into white crystalline carbonate of lime4 ,i have already alluded1 in the first chapter1 to a specimen 7also given me by ,sir ,w4 ,parish7 from the ,a4 del ,tristan1 in which shells1 resembling in every respect the ,azara labiata1 d',orbigny1 as far as their worn condition permits of comparison1 are embedded in a reddish1 softish1 somewhat arenaceous marly rock3 after careful comparison1 with the aid of a microscope and acids1 ,i can perceive no difference between the basis of this rock and the specimens collected by me in many parts of the ,pampas4 ,i have also stated1 on the authority of ,sir ,w4 ,parish1 that northward of ,buenos ,ayres1 on the highest parts of the plain1 about forty feet above the ,plata1 and two or three miles from it1 numerous shells of the ,azara labiata 7and ,i believe of ,venus sinuosa7 occur embedded in a stratified earthy mass1 including small marly concretions1 and said to be precisely like the great ,pampean deposit4 ,hence we may conclude that the mud of the ,pampas continued to be deposited to within the period of this existing estuary shell4 ,although this formation is of such immense extent1 ,i know of no other instance of the presence of shells in it4 ,,buenos ,,ayres ,,to ,,the ,,rio ,,colorado4 ,with the exception of a few metamorphic ridges1 the country between these two points1 a distance of #djj geographical miles1 belongs to the ,pampean formation1 and in the southern part is generally formed of the harder and more calcareous varieties4 ,i will briefly describe my route3 about twenty- five miles ,s4,s4,w4 of the capital1 in a well forty yards in depth1 the upper part1 and1 as ,i was assured1 the entire thickness1 was formed of dark red ,pampean mud without concretions4 ,north of the ,river ,salado1 there are many lakes2 and on the banks of one 7near the ,guardia7 there was a little cliff similarly composed1 but including many nodular and stalactiform concretions3 ,i found here a large piece of tessellated armour1 like that of the ,glyptodon1 and many fragments of bones4 ,the cliffs on the ,salado consist of pale-coloured ,pampean mud1 including and passing into great masses of tosca-rock3 here a skeleton of the ,megatherium and the bones of other extinct quadrupeds 7see the list at the end of this chapter7 were found4 ,large quantities of crystallised gypsum 7of which specimens were given me7 occur in the cliffs of this river2 and likewise 7as ,i was assured by ,mr4 ,lumb7 in the ,pampean mud on the ,river ,chuelo1 seven leagues from ,buenos ,ayres3 ,i mention this because ,m4 d',orbigny lays some stress on the supposed absence of this mineral in the ,pampean formation4 ,southward of the ,salado the country is low and swampy1 with tosca-rock appearing at long intervals at the surface4 ,on the banks1 however1 of the ,tapalguen 7sixty miles south of the ,salado7 there is a large extent of tosca-rock1 some highly compact and even semi-crystalline1 overlying pale ,pampean mud with the usual concretions4 ,thirty miles further south1 the small quartz-ridge of ,tapalguen is fringed on its northern and southern flank1 by little1 narrow1 flat-topped hills of tosca-rock1 which stand higher than the surrounding plain4 ,between this ridge and the ,sierra of ,guitru-gueyu1 a distance of sixty miles1 the country is swampy1 with the tosca-rock appearing only in four or five spots3 this sierra1 precisely like that of ,tapalguen1 is bordered by horizontal1 often cliff-bounded1 little hills of tosca-rock1 higher than the surrounding plain4 ,here1 also1 a new appearance was presented in some extensive and level banks of alluvium or detritus of the neighbouring metamorphic rocks2 but ,i neglected to observe whether it was stratified or not4 ,between ,guitru-gueyu and the ,sierra ,ventana1 ,i crossed a dry plain of tosca-rock higher than the country hitherto passed over1 and with small pieces of denuded tableland of the same formation1 standing still higher4 ,the marly or calcareous beds not only come up nearly horizontally to the northern and southern foot of the great quartzose mountains of the ,sierra ,ventana1 but interfold between the parallel ranges4 ,the superficial beds 7for ,i nowhere obtained sections more than twenty feet deep7 retain1 even close to the mountains1 their usual character3 the uppermost layer1 however1 in one place included pebbles of quartz1 and rested on a mass of detritus of the same rock4 ,at the very foot of the mountains1 there were some few piles of quartz and tosca-rock detritus1 including land-shells2 but at the distance of only half a mile from these lofty1 jagged1 and battered mountains1 ,i could not1 to my great surprise1 find on the boundless surface of the calcareous plain even a single pebble4 ,quartz- pebbles1 however1 of considerable size have at some period been transported to a distance of between forty and fifty miles to the shores of ,bahia ,blanca4 7,schmidtmeyer 8,travels in ,chile0 page #aej1 states that he first noticed on the ,pampas1 very small bits of red granite1 when fifty miles distant from the southern extremity of the mountains of ,cordova1 which project on the plain1 like a reef into the sea47 ,the highest peak of the ,st4 ,ventana is1 by ,captain ,fitzroy's measurement1 #c1cdj feet1 and the calcareous plain at its foot 7from observations taken by some ,spanish officers7 #hdj feet above the sea-level4 78,la ,plata0 etc4 by ,sir ,w4 ,parish page #adf47 ,on the flanks of the mountains1 at a height of three hundred or four hundred feet above the plain1 there were a few small patches of conglomerate and breccia1 firmly cemented by ferruginous matter to the abrupt and battered face of the quartz--traces being thus exhibited of ancient sea-action4 ,the high plain round this range sinks quite insensibly to the eye on all sides1 except to the north1 where its surface is broken into low cliffs4 ,round the ,sierras ,tapalguen1 ,guitru-gueyu1 and between the latter and the ,ventana we have seen 7and shall hereafter see round some hills in ,banda ,oriental71 that the tosca-rock forms low1 flat- topped1 cliff-bounded hills1 higher than the surrounding plains of similar composition4 ,from the horizontal stratification and from the appearance of the broken cliffs1 the greater height of the ,pampean formation round these primary hills ought not to be altogether or in chief part attributed to these several points having been uplifted more energetically than the surrounding country1 but to the argillaceo-calcareous mud having collected round them1 when they existed as islets or submarine rocks1 at a greater height1 than at the bottom of the adjoining open sea2--the cliffs having been subsequently worn during the elevation of the whole country in mass4 ,southward of the ,ventana1 the plain extends farther than the eye can range2 its surface is not very level1 having slight depressions with no drainage exits2 it is generally covered by a few feet in thickness of sandy earth2 and in some places1 according to ,m4 ,parchappe1 by beds of clay two yards thick4 7,m4 d',orbigny 8,voyage0 ,part ,geolog4 pages #dg1 #dh47 ,on the banks of the ,sauce1 four leagues ,s4,e4 of the ,ventana1 there is an imperfect section about two hundred feet in height1 displaying in the upper part tosca-rock and in the lower part red ,pampean mud4 ,at the settlement of ,bahia ,blanca1 the uppermost plain is composed of very compact1 stratified tosca-rock1 containing rounded grains of quartz distinguishable by the naked eye3 the lower plain1 on which the fortress stands1 is described by ,m4 ,parchappe as composed of solid tosca-rock 7,ibid472 but the sections which ,i examined appeared more like a redeposited mass of this rock1 with small pebbles and fragments of quartz4 ,i shall immediately return to the important sections on the shores of ,bahia ,blanca4 ,twenty miles southward of this place1 there is a remarkable ridge extending ,w4 by ,n4 and ,e4 by ,s41 formed of small1 separate1 flat-topped1 steep-sided hills1 rising between one hundred and two hundred feet above the ,pampean plain at its southern base1 which plain is a little lower than that to the north4 ,the uppermost stratum in this ridge consists of pale1 highly calcareous1 compact tosca-rock1 resting 7as seen in one place7 on reddish ,pampean mud1 and this again on a paler kind3 at the foot of the ridge1 there is a well in reddish clay or mud4 ,i have seen no other instance of a chain of hills belonging to the ,pampean formation2 and as the strata show no signs of disturbance1 and as the direction of the ridge is the same with that common to all the metamorphic lines in this whole area1 ,i suspect that the ,pampean sediment has in this instance been accumulated on and over a ridge of hard rocks1 instead of1 as in the case of the above-mentioned ,sierras1 round their submarine flanks4 ,south of this little chain of tosca-rock1 a plain of ,pampean mud declines towards the banks of the ,colorado3 in the middle a well has been dug in red ,pampean mud1 covered by two feet of white1 softish1 highly calcareous tosca-rock1 over which lies sand with small pebbles three feet in thickness--the first appearance of that vast shingle formation described in the ,first ,chapter4 ,in the first section after crossing the ,colorado1 an old tertiary formation1 namely1 the ,rio ,negro sandstone 7to be described in the next chapter71 is met with3 but from the accounts given me by the ,gauchos1 ,i believe that at the mouth of the ,colorado the ,pampean formation extends a little further southwards4 ,,bahia ,,blanca4 ,to return to the shores of this bay4 ,at ,monte ,hermoso there is a good section1 about one hundred feet in height1 of four distinct strata1 appearing to the eye horizontal1 but thickening a little towards the ,n4,w4 ,the uppermost bed1 about twenty feet in thickness1 consists of obliquely laminated1 soft sandstone1 including many pebbles of quartz1 and falling at the surface into loose sand4 ,the second bed1 only six inches thick1 is a hard1 dark-coloured sandstone4 ,the third bed is pale-coloured ,pampean mud2 and the fourth is of the same nature1 but darker coloured1 including in its lower part horizontal layers and lines of concretions of not very compact pinkish tosca-rock4 ,the bottom of the sea1 ,i may remark1 to a distance of several miles from the shore1 and to a depth of between sixty and one hundred feet1 was found by the anchors to be composed of tosca-rock and reddish ,pampean mud4 ,professor ,ehrenberg has examined for me specimens of the two lower beds1 and finds in them three ,polygastrica and six ,phytolitharia4 7,the following list is given in the 8,monatsberichten der konig4 ,akad4 zu ,berlin0 ,april #ahde3-- ,,polygastrica4 ,fragilaria rhabdosoma4 ,gallionella distans4 ,pinnularia8 ,,phytolitharia4 ,lithodontium ,bursa4 ,lithodontium furcatum4 ,lithostylidium exesum4 ,lithostylidium rude4 ,lithostylidium ,serra4 ,spongolithis ,fustis87 ,of these1 only one 7,spongolithis ,fustis87 is a marine form2 five of them are identical with microscopical structures of brackish-water origin1 hereafter to be mentioned1 which form a central point in the ,pampean formation4 ,in these two beds1 especially in the lower one1 bones of extinct mammifers1 some embedded in their proper relative positions and others single1 are very numerous in a small extent of the cliffs4 ,these remains consist of1 first1 the head of ,ctenomys antiquus1 allied to the living ,ctenomys ,braziliensis2 secondly1 a fragment of the remains of a rodent2 thirdly1 molar teeth and other bones of a large rodent1 closely allied to1 but distinct from1 the existing species of ,hydrochoerus1 and therefore probably an inhabitant of fresh water2 fourth and fifthly1 portions of vertebrae1 limbs1 ribs1 and other bones of two rodents2 sixthly1 bones of the extremities of some great megatheroid quadruped4 7,see 8,fossil ,mammalia0 page #aji by ,professor ,owen1 in the 8,zoology of the ,voyage of the #8,beagle'20 and ,catalogue page #cf of ,fossil ,remains in ,museum of ,royal ,college of ,surgeons47 ,the number of the remains of rodents gives to this collection a peculiar character1 compared with those found in any other locality4 ,all these bones are compact and heavy2 many of them are stained red1 with their surfaces polished2 some of the smaller ones are as black as jet4 ,monte ,hermoso is between fifty and sixty miles distant in a ,s4,e4 line from the ,ventana1 with the intermediate country gently rising towards it1 and all consisting of the ,pampean formation4 ,what relation1 then1 do these beds1 at the level of the sea and under it1 bear to those on the flanks of the ,ventana1 at the height of #hdj feet1 and on the flanks of the other neighbouring sierras1 which1 from the reasons already assigned1 do not appear to owe their greater height to unequal elevation8 ,when the tosca- rock was accumulating round the ,ventana1 and when1 with the exception of a few small rugged primary islands1 the whole wide surrounding plains must have been under water1 were the strata at ,monte ,hermoso depositing at the bottom of a great open sea1 between eight hundred and one thousand feet in depth8 ,i much doubt this2 for if so1 the almost perfect carcasses of the several small rodents1 the remains of which are so very numerous in so limited a space1 must have been drifted to this spot from the distance of many hundred miles4 ,it appears to me far more probable1 that during the ,pampean period this whole area had commenced slowly rising 7and in the cliffs1 at several different heights we have proofs of the land having been exposed to sea-action at several levels71 and that tracts of land had thus been formed of ,pampean sediment round the ,ventana and the other primary ranges1 on which the several rodents and other quadrupeds lived1 and that a stream 7in which perhaps the extinct aquatic ,hydrochoerus lived7 drifted their bodies into the adjoining sea1 into which the ,pampean mud continued to be poured from the north4 ,as the land continued to rise1 it appears that this source of sediment was cut off2 and in its place sand and pebbles were borne down by stronger currents1 and conformably deposited over the ,pampean strata4 7,,figure #ae4 ,,section ,,of ,,beds ,,with ,,recent ,,shells ,,and ,,extinct ,,mammifers1 ,,at ,,punta ,,alta ,,in ,,bahia ,,blanca4 7,showing beds from bottom to top3 ,a1 ,b1 ,c1 ,d477 ,punta ,alta is situated about thirty miles higher up on the northern side of this same bay3 it consists of a small plain1 between twenty and thirty feet in height1 cut off on the shore by a line of low cliffs about a mile in length1 represented in ,figure #ae with its vertical scale necessarily exaggerated4 ,the lower bed 7,a7 is more extensive than the upper ones2 it consists of stratified gravel or conglomerate1 cemented by calcareo- arenaceous matter1 and is divided by curvilinear layers of pinkish marl1 of which some are precisely like tosca-rock1 and some more sandy4 ,the beds are curvilinear1 owing to the action of currents1 and dip in different directions2 they include an extraordinary number of bones of gigantic mammifers and many shells4 ,the pebbles are of considerable size1 and are of hard sandstone1 and of quartz1 like that of the ,ventana3 there are also a few well-rounded masses of tosca-rock4 ,the second bed ,b is about fifteen feet in thickness1 but towards both extremities of the cliff 7not included in the diagram7 it either thins out and dies away1 or passes insensibly into an overlying bed of gravel4 ,it consists of red1 tough clayey mud1 with minute linear cavities2 it is marked with faint horizontal shades of colour2 it includes a few pebbles1 and rarely a minute particle of shell3 in one spot1 the dermal armour and a few bones of a ,dasypoid quadruped were embedded in it3 it fills up furrows in the underlying gravel4 ,with the exception of the few pebbles and particles of shells1 this bed resembles the true ,pampean mud2 but it still more closely resembles the clayey flats 7mentioned in the ,first ,chapter7 separating the successively rising parallel ranges of sand-dunes4 ,the bed ,c is of stratified gravel1 like the lowest one2 it fills up furrows in the underlying red mud1 and is sometimes interstratified with it1 and sometimes insensibly passes into it2 as the red mud thins out1 this upper gravel thickens4 ,shells are more numerous in it than in the lower gravel2 but the bones1 though some are still present1 are less numerous4 ,in one part1 however1 where this gravel and the red mud passed into each other1 ,i found several bones and a tolerably perfect head of the ,megatherium4 ,some of the large ,volutas1 though embedded in the gravel-bed ,c1 were filled with the red mud1 including great numbers of the little recent ,paludestrina australis4 ,these three lower beds are covered by an unconformable mantle ,d of stratified sandy earth1 including many pebbles of quartz1 pumice and phonolite1 land and sea-shells4 ,m4 d',orbigny has been so obliging as to name for me the twenty species of ,mollusca embedded in the two gravel beds3 they consist of3-- #a4 ,volutella angulata1 d',orbigny1 8,voyage0 ,mollusq4 and ,pal4 #b4 ,voluta ,braziliana1 ,sol #c4 ,olicancilleria ,braziliensis d',orbigny4 #d4 ,olicancilleria auricularia1 d',orbigny4 #e4 ,olivina puelchana1 d',orbigny4 #f4 ,buccinanops cochlidium1 d',orbigny4 #g4 ,buccinanops globulosum1 d',orbigny4 #h4 ,colombella sertulariarum1 d',orbigny4 #i4 ,trochus ,patagonicus1 and var4 of ditto1 d',orbigny4 #aj4 ,paludestrina ,australis1 d',orbigny4 #aa4 ,fissurella ,patagonica1 d',orbigny4 #ab4 ,crepidula muricata1 ,lam4 #ac4 ,venus purpurata1 ,lam4 #ad4 ,venus rostrata1 ,phillippi4 #ae4 ,mytilus ,darwinianus1 d',orbigny4 #af4 ,nucula semiornata1 d',orbigny4 #ag4 ,cardita ,patagonica1 d',orbigny4 #ah4 ,corbula ,patagonica 7871 d',orbigny4 #ai4 ,pecten tethuelchus1 d',orbigny4 #bj4 ,ostrea puelchana1 d',orbigny4 #ba4 ,a living species of ,balanus4 #bb and #bc4 ,an ,astrae and encrusting ,flustra1 apparently identical with species now living in the bay4 ,all these shells now live on this coast1 and most of them in this same bay4 ,i was also struck with the fact1 that the proportional numbers of the different kinds appeared to be the same with those now cast up on the beach3 in both cases specimens of ,voluta1 ,crepidula1 ,venus1 and ,trochus are the most abundant4 ,four or five of the species are the same with the upraised shells on the ,pampas near ,buenos ,ayres4 ,all the specimens have a very ancient and bleached appearance1 and do not emit1 when heated1 an animal odour3 some of them are changed throughout into a white1 soft1 fibrous substance2 others have the space between the external walls1 either hollow1 or filled up with crystalline carbonate of lime4 7,a ,bulinus1 mentioned in the ,introduction to the 8,fossil ,mammalia0 in the 8,zoology of the ,voyage of the #8,beagle'0 has so much fresher an appearance1 than the marine species1 that ,i suspect it must have fallen amongst the others1 and been collected by mistake47 ,the remains of the extinct mammiferous animals1 from the two gravel beds have been described by ,professor ,owen in the 8,zoology of the ,voyage of the #8,beagle'30 they consist of1 #ast1 one nearly perfect head and three fragments of heads of the ,megatherium ,cuvierii2 #bnd1 a lower jaw of ,megalonyx ,jeffersonii2 #crd1 lower jaw of ,mylodon ,darwinii2 #dth1 fragments of a head of some gigantic ,edental quadruped2 #eth1 an almost entire skeleton of the great ,scelidotherium leptocephalum1 with most of the bones1 including the head1 vertebrae1 ribs1 some of the extremities to the claw- bone1 and even1 as remarked by ,professor ,owen1 the knee-cap1 all nearly in their proper relative positions2 #fth1 fragments of the jaw and a separate tooth of a ,toxodon1 belonging either to ,t4 ,platensis1 or to a second species lately discovered near ,buenos ,ayres2 #gth1 a tooth of ,equus curvidens2 #hth1 tooth of a ,pachyderm1 closely allied to ,palaeotherium1 of which parts of the head have been lately sent from ,buenos ,ayres to the ,british ,museum2 in all probability this pachyderm is identical with the ,macrauchenia ,patagonica from ,port ,s4 ,julian1 hereafter to be referred to4 ,lastly1 and #ithly1 in a cliff of the red clayey bed ,b1 there was a double piece1 about three feet long and two wide1 of the bony armour of a large ,dasypoid quadruped1 with the two sides pressed nearly close together3 as the cliff is now rapidly washing away1 this fossil probably was lately much more perfect2 from between its doubled-up sides1 ,i extracted the middle and ungual phalanges1 united together1 of one of the feet1 and likewise a separate phalanx3 hence one or more of the limbs must have been attached to the dermal case1 when it was embedded4 ,besides these several remains in a distinguishable condition1 there were very many single bones3 the greater number were embedded in a space #bjj yards square4 ,the preponderance of the ,edental quadrupeds is remarkable2 as is1 in contrast with the beds of ,monte ,hermoso1 the absence of ,rodents4 ,most of the bones are now in a soft and friable condition1 and1 like the shells1 do not emit when burnt an animal odour4 ,the decayed state of the bones may be partly owing to their late exposure to the air and tidal-waves4 ,barnacles1 ,serpulae1 and corallines are attached to many of the bones1 but ,i neglected to observe whether these might not have grown on them since being exposed to the present tidal action 7,after having packed up my specimens at ,bahia ,blanca1 this point occurred to me1 and ,i noted it2 but forgot it on my return1 until the remains had been cleaned and oiled3 my attention has been lately called to the subject by some remarks by ,m4 d',orbigny472 but ,i believe that some of the barnacles must have grown on the ,scelidotherium1 soon after being deposited1 and before being ,,wholly covered up by the gravel4 ,besides the remains in the condition here described1 ,i found one single fragment of bone very much rolled1 and as black as jet1 so as perfectly to resemble some of the remains from ,monte ,hermoso4 ,very many of the bones had been broken1 abraded1 and rolled1 before being embedded4 ,others1 even some of those included in the coarsest parts of the the now hard conglomerate1 still retain all their minutest prominences perfectly preserved2 so that ,i conclude that they probably were protected by skin1 flesh1 or ligaments1 whilst being covered up4 ,in the case of the ,scelidotherium1 it is quite certain that the whole skeleton was held together by its ligaments1 when deposited in the gravel in which ,i found it4 ,some cervical vertebrae and a humerus of corresponding size lay so close together1 as did some ribs and the bones of a leg1 that ,i thought that they must originally have belonged to two skeletons1 and not have been washed in single2 but as remains were here very numerous1 ,i will not lay much stress on these two cases4 ,we have just seen that the armour of the ,dasypoid quadruped was certainly embedded together with some of the bones of the feet4 ,professor ,ehrenberg has examined for me specimens of the finer matter from in contact with these mammiferous remains3 he finds in them two ,polygastrica1 decidedly marine forms2 and six ,phytolitharia1 of which one is probably marine1 and the others either of fresh-water or terrestrial origin4 78,monatsberichten der ,akad4 zu ,berlin0 ,april #ahde4 ,the list consists of3-- ,,polygastrica4 ,gallionella sulcata4 ,stauroptera aspera8 fragm4 ,,phytolitharia4 ,lithasteriscus tuberculatus4 ,lithostylidium ,clepsammidium4 ,lithostylidium quadratum4 ,lithostylidium rude4 ,lithostylidium unidentatum4 ,spongolithis acicularis47 ,only one of these eight microscopical bodies is common to the nine from ,monte ,hermoso3 but five of them are in common with those from the ,pampean mud on the banks of the ,parana4 ,the presence of any fresh-water infusoria1 considering the aridity of the surrounding country1 is here remarkable3 the most probable explanation appears to be1 that these microscopical organisms were washed out of the adjoining great ,pampean formation during its denudation1 and afterwards redeposited4 ,we will now see what conclusions may be drawn from the facts above detailed4 ,it is certain that the gravel-beds and intermediate red mud were deposited within the period1 when existing species of ,mollusca held to each other nearly the same relative proportions as they do on the present coast4 ,these beds1 from the number of littoral species1 must have been accumulated in shallow water2 but not1 judging from the stratification of the gravel and the layers of marl1 on a beach4 ,from the manner in which the red clay fills up furrows in the underlying gravel1 and is in some parts itself furrowed by the overlying gravel1 whilst in other parts it either insensibly passes into1 or alternates with1 this upper gravel1 we may infer several local changes in the currents1 perhaps caused by slight changes1 up or down1 in the level of the land4 ,by the elevation of these beds1 to which period the alluvial mantle with pumice-pebbles1 land and sea-shells belongs1 the plain of ,punta ,alta1 from twenty to thirty feet in height1 was formed4 ,in this neighbourhood there are other and higher sea-formed plains and lines of cliffs in the ,pampean formation worn by the denuding action of the waves at different levels4 ,hence we can easily understand the presence of rounded masses of tosca-rock in this lowest plain2 and likewise1 as the cliffs at ,monte ,hermoso with their mammiferous remains stand at a higher level1 the presence of the one much-rolled fragment of bone which was as black as jet3 possibly some few of the other much-rolled bones may have been similarly derived1 though ,i saw only the one fragment1 in the same condition with those from ,monte ,hermoso4 ,m4 d',orbigny has suggested that all these mammiferous remains may have been washed out of the ,pampean formation1 and afterwards redeposited together with the recent shells4 78,voyage0 ,part4 ,geolog4 page #di47 ,undoubtedly it is a marvellous fact that these numerous gigantic quadrupeds1 belonging1 with the exception of the ,equus curvidens1 to seven extinct genera1 and one1 namely1 the ,toxodon1 not falling into any existing family1 should have co-existed with ,mollusca1 all of which are still living species2 but analogous facts have been observed in ,north ,america and in ,europe4 ,in the first place1 it should not be overlooked1 that most of the co-embedded shells have a more ancient and altered appearance than the bones4 ,in the second place1 is it probable that numerous bones not hardened by silex or any other mineral1 could have retained their delicate prominences and surfaces perfect if they had been washed out of one deposit1 and re-embedded in another3--this later deposit being formed of large1 hard pebbles1 arranged by the action of currents or breakers in shallow water into variously curved and inclined layers8 ,the bones which are now in so perfect a state of preservation1 must1 ,i conceive1 have been fresh and sound when embedded1 and probably were protected by skin1 flesh1 or ligaments4 ,the skeleton of the ,scelidotherium indisputably was deposited entire3 shall we say that when held together by its matrix it was washed out of an old gravel-bed 7totally unlike in character to the ,pampean formation71 and re-embedded in another gravel-bed1 composed 7,i speak after careful comparison7 of exactly the same kind of pebbles1 in the same kind of cement8 ,i will lay no stress on the two cases of several ribs and bones of the extremities having ,,apparently been embedded in their proper relative position3 but will any one be so bold as to affirm that it is possible1 that a piece of the thin tessellated armour of a ,dasypoid quadruped1 at least three feet long and two in width1 and now so tender that ,i was unable with the utmost care to extract a fragment more than two or three inches square1 could have been washed out of one bed1 and re-embedded in another1 together with some of the small bones of the feet1 without having been dashed into atoms8 ,we must then wholly reject ,m4 d',orbigny's supposition1 and admit as certain1 that the ,scelidotherium and the large ,dasypoid quadruped1 and as highly probable1 that the ,toxodon1 ,megatherium1 etc41 some of the bones of which are perfectly preserved1 were embedded for the first time1 and in a fresh condition1 in the strata in which they were found entombed4 ,these gigantic quadrupeds1 therefore1 though belonging to extinct genera and families1 coexisted with the twenty above-enumerated ,mollusca1 the barnacle and two corals1 still living on this coast4 ,from the rolled fragment of black bone1 and from the plain of ,punta ,alta being lower than that of ,monte ,hermoso1 ,i conclude that the coarse sub-littoral deposits of ,punta ,alta1 are of subsequent origin to the ,pampean mud of ,monte ,hermoso2 and the beds at this latter place1 as we have seen1 are probably of subsequent origin to the high tosca-plain round the ,sierra ,ventana3 we shall1 however1 return1 at the end of this chapter1 to the consideration of these several stages in the great ,pampean formation4 ,,buenos ,,ayres ,,to ,,st4 ,,fe ,,bajada1 ,,in ,,entre ,,rios4 ,for some distance northward of ,buenos ,ayres1 the escarpment of the ,pampean formation does not approach very near to the ,plata1 and it is concealed by vegetation3 but in sections on the banks of the ,rios ,luxan1 ,areco1 and ,arrecifes1 ,i observed both pale and dark reddish ,pampean mud1 with small1 whitish concretions of tosca2 at all these places mammiferous remains have been found4 ,in the cliffs on the ,parana1 at ,san ,nicolas1 the ,pampean mud contains but little tosca2 here ,m4 d',orbigny found the remains of two rodents 7,ctenomys ,bonariensis and ,kerodon antiquus7 and the jaw of a ,canis3 when on the river ,i could clearly distinguish in this fine line of cliffs1 8horizontal lines of variation both in tint and compactness40 7,i quote these words from my note-book1 as written down on the spot1 on account of the general absence of stratification in the ,pampean formation having been insisted on by ,m4 d',orbigny as a proof of the diluvial origin of this great deposit47 ,the plain northward of this point is very level1 but with some depressions and lakes2 ,i estimated its height at from forty to sixty feet above the ,parana4 ,at the ,a4 ,medio the bright red ,pampean mud contains scarcely any tosca-rock2 whilst at a short distance the stream of the ,pabon1 forms a cascade1 about twenty feet in height1 over a cavernous mass of two varieties of tosca-rock2 of which one is very compact and semi- crystalline1 with seams of crystallised carbonate of lime3 similar compact varieties are met with on the ,salidillo and ,seco4 ,the absolute identity 7,i speak after a comparison of my specimens7 between some of these varieties1 and those from ,tapalguen1 and from the ridge south of ,bahia ,blanca1 a distance of #djj miles of latitude1 is very striking4 ,at ,rosario there is but little tosca-rock3 near this place ,i first noticed at the edge of the river traces of an underlying formation1 which1 twenty- five miles higher up in the estancia of ,gorodona1 consists of a pale yellowish clay1 abounding with concretionary cylinders of a ferruginous sandstone4 ,this bed1 which is probably the equivalent of the older tertiary marine strata1 immediately to be described in ,entre ,rios1 only just rises above the level of the ,parana when low4 ,the rest of the cliff at ,gorodona1 is formed of red ,pampean mud1 with1 in the lower part1 many concretions of tosca1 some stalacti-formed1 and with only a few in the upper part3 at the height of six feet above the river1 two gigantic skeletons of the ,mastodon ,andium were here embedded2 their bones were scattered a few feet apart1 but many of them still held their proper relative positions3 they were much decayed and as soft as cheese1 so that even one of the great molar teeth fell into pieces in my hand4 ,we here see that the ,pampean deposit contains mammiferous remains close to its base4 ,on the banks of the ,carcarana1 a few miles distant1 the lowest bed visible was pale ,pampean mud1 with masses of tosca-rock1 in one of which ,i found a much decayed tooth of the ,mastodon3 above this bed1 there was a thin layer almost composed of small concretions of white tosca1 out of which ,i extracted a well preserved1 but slightly broken tooth of ,toxodon ,platensis3 above this there was an unusual bed of very soft impure sandstone4 ,in this neighbourhood ,i noticed many single embedded bones1 and ,i heard of others having been found in so perfect a state that they were long used as gate-posts3 the ,jesuit ,falkner found here the dermal armour of some gigantic ,edental quadruped4 ,in some of the red mud scraped from a tooth of one of the ,mastodons at ,gorodona1 ,professor ,ehrenberg finds seven ,polygastrica and thirteen ,phytolitharia1 all of them1 ,i believe1 with two exceptions1 already known species4 78,monatsberichten der konig4 ,akad4 zu ,berlin0 ,april #ahde4 ,the list consists of3-- ,,polygastrica4 ,campylodiscus clypeus4 ,coscinodiscus subtilis4 ,coscinodiscus al4 sp4 ,eunotia4 ,gallionella granulata4 ,himantidium gracile4 ,pinnularia borealis47 ,of these twenty1 the preponderating number are of fresh-water origin2 only two species of ,coscinodiscus and a ,spongolithis show the direct influence of the sea2 therefore ,professor ,ehrenberg arrives at the important conclusion that the deposit must have been of brackish-water origin4 ,of the thirteen ,phytolitharia1 nine are met with in the two deposits in ,bahia ,blanca1 where there is evidence from two other species of ,polygastrica that the beds were accumulated in brackish water4 ,the traces of coral1 sponges1 and ,polythalamia1 found by ,dr4 ,carpenter in the tosca-rock 7of which ,i must observe the greater number of specimens were from the upper beds in the southern parts of the formation71 apparently show a more purely marine origin4 ,at ,,st4 ,,fe ,,bajada1 in ,entre ,rios1 the cliffs1 estimated at between sixty and seventy feet in height1 expose an interesting section3 the lower half consists of tertiary strata with marine shells1 and the upper half of the ,pampean formation4 ,the lowest bed is an obliquely laminated1 blackish1 indurated mud1 with distinct traces of vegetable remains4 7,m4 d',orbigny 8,voyage0 ,part4 ,geolog4 page #cg1 has given a detailed description of this section1 but as he does not mention this lowest bed1 it may have been concealed when he was there by the river4 ,there is a considerable discrepancy between his description and mine1 which ,i can only account for by the beds themselves varying considerably in short distances47 ,above this there is a thick bed of yellowish sandy clay1 with much crystallised gypsum and many shells of ,ostreae1 ,pectens1 and ,arcae3 above this there generally comes an arenaceous crystalline limestone1 but there is sometimes interposed a bed1 about twelve feet thick1 of dark green1 soapy clay1 weathering into small angular fragments4 ,the limestone1 where purest1 is white1 highly crystalline1 and full of cavities3 it includes small pebbles of quartz1 broken shells1 teeth of sharks1 and sometimes1 as ,i was informed1 large bones3 it often contains so much sand as to pass into a calcareous sandstone1 and in such parts the great ,ostrea ,patagonica chiefly abounds4 7,captain ,sulivan1 ,r4,n41 has given me a specimen of this shell1 which he found in the cliffs at ,point ,cerrito1 between twenty and thirty miles above the ,bajada47 ,in the upper part1 the limestone alternates with layers of fine white sand4 ,the shells included in these beds have been named for me by ,m4 d',orbigny3 they consist of3-- #a4 ,ostrea ,patagonica1 d',orbigny1 8,voyage0 ,part4 ,pal4 #b4 ,ostrea ,alvarezii1 d',orbigny1 8,voyage0 ,part4 ,pal4 #c4 ,pecten ,paranensis1 d',orbigny1 8,voyage0 ,part4 ,pal4 #d4 ,pecten ,darwinianus1 d',orbigny1 8,voyage0 ,part4 ,pal4 #e4 ,venus ,munsterii1 d',orbigny1 8,voyage0 ,pal4 #f4 ,arca ,bonplandiana1 d',orbigny1 8,voyage0 ,pal4 #g4 ,cardium ,platense1 d',orbigny1 8,voyage0 ,pal4 #h4 ,tellina1 probably nov4 species1 but too imperfect for description4 ,,phytolitharia4 ,lithasteriscus tuberculatus4 ,lithodontium bursa4 ,lithodontium furcatum4 ,lithodontium rostratum4 ,lithostylidium ,amphiodon4 ,lithostylidium ,clepsammidium4 ,lithostylidium ,hamus4 ,lithostylidium polyedrum4 ,lithostylidium quadratum4 ,lithostylidium rude4 ,lithostylidium ,serra4 ,lithostylidium unidentatum4 ,spongolithis ,fustis4 ,these species are all extinct3 the six first were found by ,m4 d',orbigny and myself in the formations of the ,rio ,negro1 ,s4 ,josef1 and other parts of ,patagonia2 and therefore1 as first observed by ,m4 d',orbigny1 these beds certainly belong to the great ,patagonian formation1 which will be described in the ensuing chapter1 and which we shall see must be considered as a very ancient tertiary one4 ,north of the ,bajada1 ,m4 d',orbigny found1 in beds which he considers as lying beneath the strata here described1 remains of a ,toxodon1 which he has named as a distinct species from the ,t4 ,platensis of the ,pampean formation4 ,much silicified wood is found on the banks of the ,parana 7and likewise on the ,uruguay71 and ,i was informed that they come out of these lower beds2 four specimens collected by myself are dicotyledonous4 ,the upper half of the cliff1 to a thickness of about thirty feet1 consists of ,pampean mud1 of which the lower part is pale-coloured1 and the upper part of a brighter red1 with some irregular layers of an arenaceous variety of tosca1 and a few small concretions of the ordinary kind4 ,close above the marine limestone1 there is a thin stratum with a concretionary outline of white hard tosca-rock or marl1 which may be considered either as the uppermost bed of the inferior deposits1 or the lowest of the ,pampean formation2 at one time ,i considered this bed as marking a passage between the two formations3 but ,i have since become convinced that ,i was deceived on this point4 ,in the section on the ,parana1 ,i did not find any mammiferous remains2 but at two miles distance on the ,a4 ,tapas 7a tributary of the ,conchitas71 they were extremely numerous in a low cliff of red ,pampean mud with small concretions1 precisely like the upper bed on the ,parana4 ,most of the bones were solitary and much decayed2 but ,i saw the dermal armour of a gigantic ,edental quadruped1 forming a caldron-like hollow1 four or five feet in diameter1 out of which1 as ,i was informed1 the almost entire skeleton had been lately removed4 ,i found single teeth of the ,mastodon ,andium1 ,toxodon ,platensis1 and ,equus curvidens1 near to each other4 ,as this latter tooth approaches closely to that of the common horse1 ,i paid particular attention to its true embedment1 for ,i did not at that time know that there was a similar tooth hidden in the matrix with the other mammiferous remains from ,punta ,alta4 ,it is an interesting circumstance1 that ,professor ,owen finds that the teeth of this horse approach more closely in their peculiar curvature to a fossil specimen brought by ,mr4 ,lyell from ,north ,america1 than to those of any other species of ,equus4 7,lyell 8,travels in ,north ,america0 volume #a page #afd and 8,proceedings of ,geological ,society0 volume #d page #ci47 ,the underlying marine tertiary strata extend over a wide area3 ,i was assured that they can be traced in ravines in an east and west line across ,entre ,rios to the ,uruguay1 a distance of about #ace miles4 ,in a ,s4,e4 direction ,i heard of their existence at the head of the ,r4 ,nankay2 and at ,p4 ,gorda in ,banda ,oriental1 a distance of #agj miles1 ,i found the same limestone1 containing the same fossil shells1 lying at about the same level above the river as at ,st4 ,fe4 ,in a southerly direction1 these beds sink in height1 for at another ,p4 ,gorda in ,entre ,rios1 the limestone is seen at a much less height2 and there can be little doubt that the yellowish sandy clay1 on a level with the river1 between the ,carcarana and ,s4 ,nicholas1 belongs to this same formation2 as perhaps do the beds of sand at ,buenos ,ayres1 which lie at the bottom of the ,pampean formation1 about sixty feet beneath the surface of the ,plata4 ,the southerly declination of these beds may perhaps be due1 not to unequal elevation1 but to the original form of the bottom of the sea1 sloping from land situated to the north2 for that land existed at no great distance1 we have evidence in the vegetable remains in the lowest bed at ,st4 ,fe2 and in the silicified wood and in the bones of ,toxodon ,paranensis1 found 7according to ,m4 d',orbigny7 in still lower strata4 ,,banda ,,oriental4 ,this province lies on the northern side of the ,plata1 and eastward of the ,uruguay3 it has a gentle undulatory surface1 with a basis of primary rocks2 and is in most parts covered up with an unstratified mass1 of no great thickness1 of reddish ,pampean mud4 ,in the eastern half1 near ,maldonado1 this deposit is more arenaceous than in the ,pampas1 it contains many though small concretions of marl or tosca-rock1 and others of highly ferruginous sandstone2 in one section1 only a few yards in depth1 it rested on stratified sand4 ,near ,monte ,video this deposit in some spots appears to be of greater thickness2 and the remains of the ,glyptodon and other extinct mammifers have been found in it4 ,in the long line of cliffs1 between fifty and sixty feet in height1 called the ,barrancas de ,s4 ,gregorio1 which extend westward of the ,rio ,s4 ,lucia1 the lower half is formed of coarse sand of quartz and feldspar without mica1 like that now cast up on the beach near ,maldonado2 and the upper half of ,pampean mud1 varying in colour and containing honeycombed veins of soft calcareous matter and small concretions of tosca-rock arranged in lines1 and likewise a few pebbles of quartz4 ,this deposit fills up hollows and furrows in the underlying sand2 appearing as if water charged with mud had invaded a sandy beach4 ,these cliffs extend far westward1 and at a distance of sixty miles1 near ,colonia del ,sacramiento1 ,i found the ,pampean deposit resting in some places on this sand1 and in others on the primary rocks3 between the sand and the reddish mud1 there appeared to be interposed1 but the section was not a very good one1 a thin bed of shells of an existing ,mytilus1 still partially retaining their colour4 ,the ,pampean formation in ,banda ,oriental might readily be mistaken for an alluvial deposit3 compared with that of the ,pampas1 it is often more sandy1 and contains small fragments of quartz2 the concretions are much smaller1 and there are no extensive masses of tosca-rock4 ,in the extreme western parts of this province1 between the ,uruguay and a line drawn from ,colonia to the ,r4 ,perdido 7a tributary of the ,r4 ,negro71 the formations are far more complicated4 ,besides primary rocks1 we meet with extensive tracts and many flat-topped1 horizontally stratified1 cliff- bounded1 isolated hills of tertiary strata1 varying extraordinarily in mineralogical nature1 some identical with the old marine beds of ,st4 ,fe ,bajada1 and some with those of the much more recent ,pampean formation4 ,there are1 also1 extensive ,,low tracts of country covered with a deposit containing mammiferous remains1 precisely like that just described in the more eastern parts of the province4 ,although from the smooth and unbroken state of the country1 ,i never obtained a section of this latter deposit close to the foot of the higher tertiary hills1 yet ,i have not the least doubt that it is of quite subsequent origin2 having been deposited after the sea had worn the tertiary strata into the cliff-bounded hills4 ,this later formation1 which is certainly the equivalent of that of the ,pampas1 is well seen in the valleys in the estancia of ,berquelo1 near ,mercedes2 it here consists of reddish earth1 full of rounded grains of quartz1 and with some small concretions of tosca-rock arranged in horizontal lines1 so as perfectly to resemble1 except in containing a little calcareous matter1 the formation in the eastern parts of ,banda ,oriental1 in ,entre ,rios1 and at other places3 in this estancia the skeleton of a great ,edental quadruped was found4 ,in the valley of the ,sarandis1 at the distance of only a few miles1 this deposit has a somewhat different character1 being whiter1 softer1 finer-grained1 and full of little cavities1 and consequently of little specific gravity2 nor does it contain any concretions or calcareous matter3 ,i here procured a head1 which when first discovered must have been quite perfect1 of the ,toxodon ,platensis1 another of a ,mylodon 7,this head was at first considered by ,professor ,owen 7in the 8,zoology of the #8,beagle's' ,voyage07 as belonging to a distinct genus1 namely1 ,glossotherium471 perhaps ,m4 ,darwinii1 and a large piece of dermal armour1 differing from that of the ,glyptodon clavipes4 ,these bones are remarkable from their extraordinarily fresh appearance2 when held over a lamp of spirits of wine1 they give out a strong odour and burn with a small flame2 ,mr4 ,t4 ,reeks has been so kind as to analyse some of the fragments1 and he finds that they contain about #g per cent of animal matter1 and #h per cent of water4 7,liebig 8,chemistry of ,agriculture0 page #aid states that fresh dry bones contain from #cb to #cc per cent of dry gelatine4 ,see also ,dr4 ,daubeny1 in 8,edinburgh ,new ,philosophical ,journal0 volume #cg page #bic47 ,the older tertiary strata1 forming the higher isolated hills and extensive tracts of country1 vary1 as ,i have said1 extraordinarily in composition3 within the distance of a few miles1 ,i sometimes passed over crystalline limestone with agate1 calcareous tuffs1 and marly rocks1 all passing into each other1--red and pale mud with concretions of tosca-rock1 quite like the ,pampean formation1--calcareous conglomerates and sandstones1--bright red sandstones passing either into red conglomerate1 or into white sandstone1--hard siliceous sandstones1 jaspery and chalcedonic rocks1 and numerous other subordinate varieties4 ,i was unable to mark out the relations of all these strata1 and will describe only a few distinct sections3--in the cliffs between ,p4 ,gorda on the ,uruguay and the ,a4 de ,vivoras1 the upper bed is crystalline cellular limestone often passing into calcareous sandstone1 with impressions of some of the same shells as at ,st4 ,fe ,bajada2 at ,p4 ,gorda1 this limestone is interstratified with and rests on1 white sand1 which covers a bed about thirty feet thick of pale-coloured clay1 with many shells of the great ,ostrea ,patagonica 7,in my 8,journal0 page #aga #ast edition1 ,i have hastily and inaccurately stated that the ,pampean mud1 which is found over the eastern part of ,b4 ,oriental1 lies ,,over the limestone at ,p4 ,gorda2 ,i should have said that there was reason to infer that it was a subsequent or superior deposit473 beneath this1 in the vertical cliff1 nearly on a level with the river1 there is a bed of red mud absolutely like the ,pampean deposit1 with numerous often large concretions of perfectly characterised white1 compact tosca-rock4 ,at the mouth of the ,vivoras1 the river flows over a pale cavernous tosca-rock1 quite like that in the ,pampas1 and this ,,appeared to underlie the crystalline limestone2 but the section was not unequivocal like that at ,p4 ,gorda4 ,these beds now form only a narrow and much denuded strip of land2 but they must once have extended much further2 for on the next stream1 south of the ,s4 ,juan1 ,captain ,sulivan1 ,r4,n41 found a little cliff1 only just above the surface of the river1 with numerous shells of the ,venus ,munsterii1 ,d',orbigny1--one of the species occurring at ,st4 ,fe1 and of which there are casts at ,p4 ,gorda3 the line of cliffs of the subsequently deposited true ,pampean mud1 extend from ,colonia to within half a mile of this spot1 and no doubt once covered up this denuded marine stratum4 ,again at ,colonia1 a ,frenchman found1 in digging the foundations of a house1 a great mass of the ,ostrea ,patagonica 7of which ,i saw many fragments71 packed together just beneath the surface1 and directly superimposed on the gneiss4 ,these sections are important3 ,m4 d',orbigny is unwilling to believe that beds of the same nature with the ,pampean formation ever underlie the ancient marine tertiary strata2 and ,i was as much surprised at it as he could have been2 but the vertical cliff at ,p4 ,gorda allowed of no mistake1 and ,i must be permitted to affirm1 that after having examined the country from the ,colorado to ,st4 ,fe ,bajada1 ,i could not be deceived in the mineralogical character of the ,pampean deposit4 ,moreover1 in a precipitous part of the ravine of ,las ,bocas1 a red sandstone is distinctly seen to overlie a thick bed of pale mud1 also quite like the ,pampean formation1 abounding with concretions of true tosca-rock4 ,this sandstone extends over many miles of country3 it is as red as the brightest volcanic scoriae2 it sometimes passes into a coarse red conglomerate composed of the underlying primary rocks2 and often passes into a soft white sandstone with red streaks4 ,at the ,calera de los ,huerfanos1 only a quarter of a mile south of where ,i first met with the red sandstone1 the crystalline white limestone is quarried3 as this bed is the uppermost1 and as it often passes into calcareous sandstone1 interstratified with pure sand2 and as the red sandstone likewise passes into soft white sandstone1 and is also the uppermost bed1 ,i believe that these two beds1 though so different1 are equivalents4 ,a few leagues southward of these two places1 on each side of the low primary range of ,s4 ,juan1 there are some flat-topped1 cliff-bounded1 separate little hills1 very similar to those fringing the primary ranges in the great plain south of ,buenos ,ayres3 they are composed--#ast1 of calcareous tuff with many particles of quartz1 sometimes passing into a coarse conglomerate2 #bnd1 of a stone undistinguishable on the closest inspection from the compacter varieties of tosca-rock2 and #crd1 of semi-crystalline limestone1 including nodules of agate3 these three varieties pass insensibly into each other1 and as they form the uppermost stratum in this district1 ,i believe that they1 also1 are the equivalents of the pure crystalline limestone1 and of the red and white sandstones and conglomerates4 ,between these points and ,mercedes on the ,rio ,negro1 there are scarcely any good sections1 the road passing over limestone1 tosca-rock1 calcareous and bright red sandstones1 and near the source of the ,san ,salvador over a wide extent of jaspery rocks1 with much milky agate1 like that in the limestone near ,san ,juan4 ,in the estancia of ,berquelo1 the separate1 flat-topped1 cliff-bounded hills are rather higher than in the other parts of the country2 they range in a ,n4,e4 and ,s4,w4 direction2 their uppermost beds consist of the same bright red sandstone1 passing sometimes into a conglomerate1 and in the lower part into soft white sandstone1 and even into loose sand3 beneath this sandstone1 ,i saw in two places layers of calcareous and marly rocks1 and in one place red ,pampean-like earth2 at the base of these sections1 there was a hard1 stratified1 white sandstone1 with chalcedonic layers4 ,near ,mercedes1 beds of the same nature and apparently of the same age1 are associated with compact1 white1 crystalline limestone1 including much botryoidal agate1 and singular masses1 like porcelain1 but really composed of a calcareo-siliceous paste4 ,in sinking wells in this district the chalcedonic strata seem to be the lowest4 ,beds1 such as there described1 occur over the whole of this neighbourhood2 but twenty miles further up the ,r4 ,negro1 in the cliffs of ,perika1 which are about fifty feet in height1 the upper bed is a prettily variegated chalcedony1 mingled with a pure white tallowy limestone2 beneath this there is a conglomerate of quartz and granite2 beneath this many sandstones1 some highly calcareous2 and the whole lower two-thirds of the cliff consists of earthy calcareous beds of various degrees of purity1 with one layer of reddish ,pampean-like mud4 ,when examining the agates1 the chalcedonic and jaspery rocks1 some of the limestones1 and even the bright red sandstones1 ,i was forcibly struck with their resemblance to deposits formed in the neighbourhood of volcanic action4 ,i now find that ,m4 ,isabelle1 in his 8,voyage a ,buenos ,ayres10 has described closely similar beds on ,itaquy and ,ibicuy 7which enter the ,uruguay some way north of the ,r4 ,negro7 and these beds include fragments of red decomposed true scoriae hardened by zeolite1 and of black retinite3 we have then here good evidence of volcanic action during our tertiary period4 ,still further north1 near ,s4 ,anna1 where the ,parana makes a remarkable bend1 ,m4 ,bonpland found some singular amygdaloidal rocks1 which perhaps may belong to this same epoch4 7,m4 d',orbigny 8,voyage0 ,part4 ,geolog4 page #bi7 ,i may remark that1 judging from the size and well-rounded condition of the blocks of rock in the above-described conglomerates1 masses of primary formation probably existed at this tertiary period above water3 there is1 also1 according to ,m4 ,isabelle1 much conglomerate further north1 at ,salto4 ,from whatever source and through whatever means the great ,pampean formation originated1 we here have1 ,i must repeat1 unequivocal evidence of a similar action at a period before that of the deposition of the marine tertiary strata with extinct shells1 at ,santa ,fe and ,p4 ,gorda4 ,during also the deposition of these strata1 we have in the intercalated layers of red ,pampean-like mud and tosca-rock1 and in the passage near ,s4 ,juan of the semi-crystalline limestones with agate into tosca undistinguishable from that of the ,pampas1 evidence of the same action1 though continued only at intervals and in a feeble manner4 ,we have further seen that in this district1 at a period not only subsequent to the deposition of the tertiary strata1 but to their upheavement and most extensive denudation1 true ,pampean mud with its usual characters and including mammiferous remains1 was deposited round and between the hills or islets formed of these tertiary strata1 and over the whole eastern and low primary districts of ,banda ,oriental4 ,,earthy ,,mass1 ,,with ,,extinct ,,mammiferous ,,remains1 ,,over ,,the ,,porphyritic ,,gravel ,,at ,s4 ,,julian1 ,,latitude #di ,,degrees #ad ,s41 ,,in ,,patagonia4 7,,figure #af4 ,,section ,,of ,,the ,,lowest ,,plain ,,at ,,port ,s4 ,,julian4 7,section through beds from top to bottom3 ,a1 ,b1 ,c1 ,d1 ,e1 ,f47 ,,aa4 ,superficial bed of reddish earth1 with the remains of the ,macrauchenia1 and with recent sea-shells on the surface4 ,b4 ,gravel of porphyritic rocks4 ,c4 and ,d4 ,pumiceous mudstone4--,ancient tertiary formation4 ,e4 and ,f4 ,sandstone and argillaceous beds4--,ancient tertiary formation47 ,this case1 though not coming strictly under the ,pampean formation1 may be conveniently given here4 ,on the south side of the harbour1 there is a nearly level plain 7mentioned in the ,first ,chapter7 about seven miles long1 and three or four miles wide1 estimated at ninety feet in height1 and bordered by perpendicular cliffs1 of which a section is represented in ,figure #af4 ,the lower old tertiary strata 7to be described in the next chapter7 are covered by the usual gravel bed2 and this by an irregular earthy1 sometimes sandy mass1 seldom more than two or three feet in thickness1 except where it fills up furrows or gullies worn not only through the underlying gravel1 but even through the upper tertiary beds4 ,this earthy mass is of a pale reddish colour1 like the less pure varieties of ,pampean mud in ,banda ,oriental2 it includes small calcareous concretions1 like those of tosca- rock but more arenaceous1 and other concretions of a greenish1 indurated argillaceous substance3 a few pebbles1 also1 from the underlying gravel-bed are also included in it1 and these being occasionally arranged in horizontal lines1 show that the mass is of sub-aqueous origin4 ,on the surface and embedded in the superficial parts1 there are numerous shells1 partially retaining their colours1 of three or four of the now commonest littoral species4 ,near the bottom of one deep furrow 7represented in ,figure #af71 filled up with this earthy deposit1 ,i found a large part of the skeleton of the ,macrauchenia ,patachonica--a gigantic and most extraordinary pachyderm1 allied1 according to ,professor ,owen1 to the ,palaeotherium1 but with affinities to the ,ruminants1 especially to the ,american division of the ,camelidae4 ,several of the vertebrae in a chain1 and nearly all the bones of one of the limbs1 even to the smallest bones of the foot1 were embedded in their proper relative positions3 hence the skeleton was certainly united by its flesh or ligaments1 when enveloped in the mud4 ,this earthy mass1 with its concretions and mammiferous remains1 filling up furrows in the underlying gravel1 certainly presents a very striking resemblance to some of the sections 7for instance1 at ,p4 ,alta in ,b4 ,blanca1 or at the ,barrancas de ,s4 ,gregorio7 in the ,pampean formation2 but ,i must believe that this resemblance is only accidental4 ,i suspect that the mud which at the present day is accumulating in deep and narrow gullies at the head of the harbour1 would1 after elevation1 present a very similar appearance4 ,the southernmost part of the true ,pampean formation1 namely1 on the ,colorado1 lies #efj miles of latitude north of this point4 7,in the succeeding chapter ,i shall have to refer to a great deposit of extinct mammiferous remains1 lately discovered by ,captain ,sulivan1 ,r4,n41 at a point still further south1 namely1 at the ,r4 ,gallegos2 their age must at present remain doubtful47 ,with respect to the age of the ,macrauchenia1 the shells on the surface prove that the mass in which the skeleton was enveloped has been elevated above the sea within the recent period3 ,i did not see any of the shells embedded at a sufficient depth to assure me 7though it be highly probable7 that the whole thickness of the mass was contemporaneous with these ,,individual ,,specimens4 ,that the ,macrauchenia lived subsequently to the spreading out of the gravel on this plain is certain2 and that this gravel1 at the height of ninety feet1 was spread out long after the existence of recent shells1 is scarcely less certain4 ,for1 it was shown in the ,first ,chapter1 that this line of coast has been upheaved with remarkable equability1 and that over a vast space both north and south of ,s4 ,julian1 recent species of shells are strewed on 7or embedded in7 the surface of the #bej feet plain1 and of the #cej feet plain up to a height of #djj feet4 ,these wide step-formed plains have been formed by the denuding action of the coast-waves on the old tertiary strata2 and therefore1 when the surface of the #cej feet plain1 with the shells on it1 first rose above the level of the sea1 the #bej feet plain did not exist1 and its formation1 as well as the spreading out of the gravel on its summit1 must have taken place subsequently4 ,so also the denudation and the gravel-covering of the #ij feet plain must have taken place subsequently to the elevation of the #bej feet plain1 on which recent shells are also strewed4 ,hence there cannot be any doubt that the ,macrauchenia1 which certainly was entombed in a fresh state1 and which must have been alive after the spreading out of the gravel on the #ij feet plain1 existed1 not only subsequently to the upraised shells on the surface of the #bej feet plain1 but also to those on the #cej to #djj feet plain3 these shells1 eight in number 7namely1 three species of ,mytilus1 two of ,patella1 one ,fusus1 ,voluta1 and ,balanus71 are undoubtedly recent species1 and are the commonest kinds now living on this coast4 ,at ,punta ,alta in ,b4 ,blanca1 ,i remarked how marvellous it was1 that the ,toxodon1 a mammifer so unlike to all known genera1 should have co-existed with twenty- three still living marine animals2 and now we find that the ,macrauchenia1 a quadruped only a little less anomalous than the ,toxodon1 also co-existed with eight other still existing ,mollusca3 it should1 moreover1 be borne in mind1 that a tooth of a pachydermatous animal was found with the other remains at ,punta ,alta1 which ,professor ,owen thinks almost certainly belonged to the ,macrauchenia4 ,mr4 ,lyell has arrived at a highly important conclusion with respect to the age of the ,north ,american extinct mammifers 7many of which are closely allied to1 and even identical with1 those of the ,pampean formation71 namely1 that they lived subsequently to the period when erratic boulders were transported by the agency of floating ice in temperate latitudes4 78,geological ,proceedings0 volume #d page #cf47 ,now in the valley of the ,santa ,cruz1 only fifty miles of latitude south of the spot where the ,macrauchenia was entombed1 vast numbers of gigantic1 angular boulders1 which must have been transported from the ,cordillera on icebergs1 lie strewed on the plain1 at the height of #a1djj feet above the level of the sea4 ,in ascending to this level1 several step-formed plains must be crossed1 all of which have necessarily required long time for their formation2 hence the lowest or ninety feet plain1 with its superficial bed containing the remains of the ,macrauchenia1 must have been formed very long subsequently to the period when the #a1djj feet plain was beneath the sea1 and boulders were dropped on it from floating masses of ice4 7,it must not be inferred from these remarks1 that the ice-action ceased in ,south ,america at this comparatively ancient period2 for in ,tierra del ,fuego boulders were probably transported contemporaneously with1 if not subsequently to1 the formation of the ninety feet plain at ,s4 ,julian1 and at other parts of the coast of ,patagonia47 ,mr4 ,lyell's conclusion1 therefore1 is thus far confirmed in the southern hemisphere2 and it is the more important1 as one is naturally tempted to admit so simple an explanation1 that it was the ice-period that caused the extinction of the numerous great mammifers which so lately swarmed over the two ,americas4 ,a ,,summary ,,and ,,concluding ,,remarks ,,on ,,the ,,pampean ,,formation4 ,one of its most striking features is its great extent2 ,i passed continuously over it from the ,colorado to ,st4 ,fe ,bajada1 a distance of #ejj geographical miles2 and ,m4 d',orbigny traced it for #bej miles further north4 ,in the latitude of the ,plata1 ,i examined this formation at intervals over an east and west line of #cjj miles from ,maldonado to the ,r4 ,carcarana2 and ,m4 d',orbigny believes it extends #ajj miles further inland3 from ,mr4 ,caldcleugh's travels1 however1 ,i should have thought that it had extended1 south of the ,cordovese range1 to near ,mendoza1 and ,i may add that ,i heard of great bones having been found high up the ,r4 ,quinto4 ,hence the area of the ,pampean formation1 as remarked by ,m4 d',orbigny1 is probably at least equal to that of ,france1 and perhaps twice or thrice as great4 ,in a basin1 surrounded by gravel-cliff 7at a height of nearly three thousand feet71 south of ,mendoza1 there is1 as described in the ,third ,chapter1 a deposit very like the ,pampean1 interstratified with other matter2 and again at ,s4 ,julian's1 in ,patagonia1 #efj miles south of the ,colorado1 a small irregular bed of a nearly similar nature contains1 as we have just seen1 mammiferous remains4 ,in the provinces of ,moxos and ,chiquitos 7#a1jjj miles northward of the ,pampas71 and in ,bolivia1 at a height of #d1jjj metres1 ,m4 d',orbigny has described similar deposits1 which he believes to have been formed by the same agency contemporaneously with the ,pampean formation4 ,considering the immense distances between these several points1 and their different heights1 it appears to me infinitely more probable1 that this similarity has resulted not from contemporaneousness of origin1 but from the similarity of the rocky framework of the continent3 it is known that in ,brazil an immense area consists of gneissic rocks1 and we shall hereafter see1 over how great a length the plutonic rocks of the ,cordillera1 the overlying purple porphyries1 and the trachytic ejections1 are almost identical in nature4 ,three theories on the origin of the ,pampean formation have been propounded3--,first1 that of a great debacle by ,m4 d',orbigny2 this seems founded chiefly on the absence of stratification1 and on the number of embedded remains of terrestrial quadrupeds4 ,although the ,pampean formation 7like so many argillaceous deposits7 is not divided into distinct and separate strata1 yet we have seen that in one good section it was striped with horizontal zones of colour1 and that in several specified places the upper and lower parts differed1 not only considerably in colour1 but greatly in constitution4 ,in the southern part of the ,pampas the upper mass 7to a certain extent stratified7 generally consists of hard tosca-rock1 and the lower part of red ,pampean mud1 often itself divided into two or more masses1 varying in colour and in the quantity of included calcareous matter4 ,in ,western ,banda ,oriental1 beds of a similar nature1 but of a greater age1 conformably underlie and are intercalated with the regularly stratified tertiary formation4 ,as a general rule1 the marly concretions are arranged in horizontal lines1 sometimes united into irregular strata3 surely1 if the mud had been tumultuously deposited in mass1 the included calcareous matter would have segregated itself irregularly1 and not into nodules arranged in horizontal lines1 one above the other and often far apart3 this arrangement appears to me to prove that mud1 differing slightly in composition1 was successively and quietly deposited4 ,on the theory of a debacle1 a prodigious amount of mud1 without a single pebble1 is supposed to have been borne over the wide surface of the ,pampas1 when under water3 on the other hand1 over the whole of ,patagonia1 the same or another debacle is supposed to have borne nothing but gravel1--the gravel and the fine mud in the neighbourhood of the ,rios ,negro and ,colorado having been borne to an equal distance from the ,cordillera1 or imagined line of disturbance3 assuredly directly opposite effects ought not to be attributed to the same agency4 ,where1 again1 could a mass of fine sediment1 charged with calcareous matter in a fit state for chemical segregation1 and in quantity sufficient to cover an area at least #gej miles long1 and #djj miles broad1 to a depth of from twenty to thirty feet to a hundred feet1 have been accumulated1 ready to be transported by the supposed debacle8 ,to my mind it is little short of demonstration1 that a great lapse of time was necessary for the production and deposition of the enormous amount of mudlike matter forming the ,pampas2 nor should ,i have noticed the theory of a debacle1 had it not been adduced by a naturalist so eminent as ,m4 d',orbigny4 ,a second theory1 first suggested1 ,i believe1 by ,sir ,w4 ,parish1 is that the ,pampean formation was thrown down on low and marshy plains by the rivers of this country before they assumed their present courses4 ,the appearance and composition of the deposit1 the manner in which it slopes up and round the primary ranges1 the nature of the underlying marine beds1 the estuary and sea-shells on the surface1 the overlying sandstone beds at ,m4 ,hermoso1 are all quite opposed to this view4 ,nor do ,i believe that there is a single instance of a skeleton of one of the extinct mammifers having been found in an upright position1 as if it had been mired4 ,the third theory1 of the truth of which ,i cannot entertain the smallest doubt1 is that the ,pampean formation was slowly accumulated at the mouth of the former estuary of the ,plata and in the sea adjoining it4 ,i have come to this conclusion from the reasons assigned against the two foregoing theories1 and from simple geographical considerations4 ,from the numerous shells of the ,azara labiata lying loose on the surface of the plains1 and near ,buenos ,ayres embedded in the tosca-rock1 we know that this formation not only was formerly covered by1 but that the uppermost parts were deposited in1 the brackish water of the ancient ,la ,plata4 ,southward and seaward of ,buenos ,ayres1 the plains were upheaved from under water inhabited by true marine shells4 ,we further know from ,professor ,ehrenberg's examination of the twenty microscopical organisms in the mud round the tooth of the ,mastodon high up the course of the ,parana1 that the bottom- most part of this formation was of brackish-water origin4 ,a similar conclusion must be extended to the beds of like composition1 at the level of the sea and under it1 at ,m4 ,hermoso in ,bahia ,blanca4 ,dr4 ,carpenter finds that the harder varieties of tosca-rock1 collected chiefly to the south1 contain marine spongoid bodies1 minute fragments of shells1 corals1 and ,polythalamia2 these perhaps may have been drifted inwards by the tides1 from the more open parts of the sea4 ,the absence of shells1 throughout this deposit1 with the exception of the uppermost layers near ,buenos ,ayres1 is a remarkable fact3 can it be explained by the brackish condition of the water1 or by the deep mud at the bottom8 ,i have stated that both the reddish mud and the concretions of tosca-rock are often penetrated by minute1 linear cavities1 such as frequently may be observed in fresh-water calcareous deposits3--were they produced by the burrowing of small worms8 ,only on this view of the ,pampean formation having been of estuary origin1 can the extraordinary numbers 7presently to be alluded to7 of the embedded mammiferous remains be explained4 7,it is almost superfluous to give the numerous cases 7for instance1 in ,sumatra2 ,lyell 8,principles0 volume #c page #cbe sixth edition1 of the carcasses of animals having been washed out to sea by swollen rivers2 but ,i may refer to a recent account by ,mr4 ,bettington 8,asiatic ,society0 #ahde ,june #bast1 of oxen1 deer1 and bears being carried into the ,gulf of ,cambray2 see also the account in my 8,journal0 #bnd edition page #acc1 of the numbers of animals drowned in the ,plata during the great1 often recurrent1 droughts47 ,with respect to the first origin of the reddish mud1 ,i will only remark1 that the enormous area of ,brazil consists in chief part of gneissic and other granitic rocks1 which have suffered decomposition1 and been converted into a red1 gritty1 argillaceous mass1 to a greater depth than in any other country which ,i have seen4 ,the mixture of rounded grains1 and even of small fragments and pebbles of quartz1 in the ,pampean mud of ,banda ,oriental1 is evidently due to the neighbouring and underlying primary rocks4 ,the estuary mud was drifted during the ,pampean period in a much more southerly course1 owing probably to the east and west primary ridges south of the ,plata not having been then elevated1 than the mud of the ,plata at present is2 for it was formerly deposited as far south as the ,colorado4 ,the quantity of calcareous matter in this formation1 especially in those large districts where the whole mass passes into tosca-rock1 is very great3 ,i have already remarked on the close resemblance in external and microscopical appearance1 between this tosca-rock and the strata at ,coquimbo1 which have certainly resulted from the decay and attrition of recent shells3 ,i dare not1 however1 extend this conclusion to the calcareous rocks of the ,pampas1 more especially as the underlying tertiary strata in western ,banda ,oriental show that at that period there was a copious emission of carbonate of lime1 in connection with volcanic action4 7,i may add1 that there are nearly similar superficial calcareous beds at ,king ,george's ,sound in ,australia2 and these undoubtedly have been formed by the disintegration of marine remains see 8,volcanic ,islands0 etc4 page #add4 ,there is1 however1 something very remarkable in the frequency of superficial1 thin beds of earthy calcareous matter1 in districts where the surrounding rocks are not calcareous4 ,major ,charters1 in a ,paper read before the ,geographical ,society ,april #ac1 #ahdj and abstracted in the 8,athenaeum0 page #cag1 states that this is the case in parts of ,mexico1 and that he has observed similar appearances in many parts of ,south ,africa4 ,the circumstance of the uppermost stratum round the ragged ,sierra ,ventana1 consisting of calcareous or marly matter1 without any covering of alluvial matter1 strikes me as very singular1 in whatever manner we view the deposition and elevation of the ,pampean formation47 ,the ,pampean formation1 judging from its similar composition1 and from the apparent absolute specific identity of some of its mammiferous remains1 and from the generic resemblance of others1 belongs over its vast area-- throughout ,banda ,oriental1 ,entre ,rios1 and the wide extent of the ,pampas as far south as the ,colorado1--to the same geological epoch4 ,the mammiferous remains occur at all depths from the top to the bottom of the deposit2 and ,i may add that nowhere in the ,pampas is there any appearance of much superficial denudation3 some bones which ,i found near the ,guardia del ,monte were embedded close to the surface2 and this appears to have been the case with many of those discovered in ,banda ,oriental3 on the ,matanzas1 twenty miles south of ,buenos ,ayres1 a ,glyptodon was embedded five feet beneath the surface2 numerous remains were found by ,s4 ,muniz1 near ,luxan1 at an average depth of eighteen feet2 in ,buenos ,ayres a skeleton was disinterred at sixty feet depth1 and on the ,parana ,i have described two skeletons of the ,mastodon only five or six feet above the very base of the deposit4 ,with respect to the age of this formation1 as judged of by the ordinary standard of the existence of ,mollusca1 the only evidence within the limits of the true ,pampas which is at all trustworthy1 is afforded by the still living ,azara labiata being embedded in tosca-rock near ,buenos ,ayres4 ,at ,punta ,alta1 however1 we have seen that several of the extinct mammifers1 most characteristic of the ,pampean formation1 co-existed with twenty species of ,mollusca1 a barnacle and two corals1 all still living on this same coast2-- for when we remember that the shells have a more ancient appearance than the bones2 that many of the bones1 though embedded in a coarse conglomerate1 are perfectly preserved2 that almost all the parts of the skeleton of the ,scelidotherium1 even to the knee-cap1 were lying in their proper relative positions2 and that a large piece of the fragile dermal armour of a ,dasypoid quadruped1 connected with some of the bones of the foot1 had been entombed in a condition allowing the two sides to be doubled together1 it must assuredly be admitted that these mammiferous remains were embedded in a fresh state1 and therefore that the living animals co-existed with the co-embedded shells4 ,moreover1 the ,macrauchenia ,patachonica 7of which1 according to ,professor ,owen1 remains also occur in the ,pampas of ,buenos ,ayres1 and at ,punta ,alta7 has been shown by satisfactory evidence of another kind1 to have lived on the plains of ,patagonia long after the period when the adjoining sea was first tenanted by its present commonest molluscous animals4 ,we must1 therefore1 conclude that the ,pampean formation belongs1 in the ordinary geological sense of the word1 to the ,recent ,period4 7,m4 d',orbigny believes 8,voyage0 ,part4 ,geolog4 page #ha1 that this formation1 though 8tres voisine de la notre1 est neanmoins de beaucoup anterieure a notre creation407 ,at ,st4 ,fe ,bajada1 the ,pampean estuary formation1 with its mammiferous remains1 conformably overlies the marine tertiary strata1 which 7as first shown by ,m4 d',orbigny7 are contemporaneous with those of ,patagonia1 and which1 as we shall hereafter see1 belong to a very ancient tertiary stage4 ,when examining the junction between these two formations1 ,i thought that the concretionary layer of marl marked a passage between the marine and estuary stages4 ,m4 d',orbigny disputes this view 7as given in my 8,journal071 and ,i admit that it is erroneous1 though in some degree excusable1 from their conformability and from both abounding with calcareous matter4 ,it would1 indeed1 have been a great anomaly if there had been a true passage between a deposit contemporaneous with existing species of mollusca1 and one in which all the mollusca appear to be extinct4 ,northward of ,santa ,fe1 ,m4 d',orbigny met with ferruginous sandstones1 marly rocks1 and other beds1 which he considers as a distinct and lower formation2 but the evidence that they are not parts of the same with an altered mineralogical character1 does not appear to me quite satisfactory4 ,in ,western ,banda ,oriental1 while the marine tertiary strata were accumulating1 there were volcanic eruptions1 much silex and lime were precipitated from solution1 coarse conglomerates were formed1 being derived probably from adjoining land1 and layers of red mud and marly rocks1 like those of the ,pampean formation1 were occasionally deposited4 ,the true ,pampean deposit1 with mammiferous remains1 instead of as at ,santa ,fe overlying conformably the tertiary strata1 is here seen at a lower level folding round and between the flat-topped1 cliff-bounded hills1 formed by a upheaval and denudation of these same tertiary strata4 ,the upheaval1 having occurred here earlier than at ,santa ,fe1 may be naturally accounted for by the contemporaneous volcanic action4 ,at the ,barrancas de ,s4 ,gregorio1 the ,pampean deposit1 as we have seen1 overlies and fills up furrows in coarse sand1 precisely like that now accumulating on the shores near the mouth of the ,plata4 ,i can hardly believe that this loose and coarse sand is contemporaneous with the old tertiary and often crystalline strata of the more western parts of the province2 and am induced to suspect that it is of subsequent origin4 ,if that section near ,colonia could be implicitly trusted1 in which1 at a height of only fifteen feet above the ,plata1 a bed of fresh-looking mussels1 of an existing littoral species1 appeared to lie between the sand and the ,pampean mud1 ,i should conclude that ,banda ,oriental must have stood1 when the coarse sand was accumulating1 at only a little below its present level1 and had then subsided1 allowing the estuary ,pampean mud to cover far and wide its surface up to a height of some hundred feet2 and that after this subsidence the province had been uplifted to its present level4 ,in ,western ,banda ,oriental1 we know1 from two unequivocal sections that there is a mass1 absolutely undistinguishable from the true ,pampean deposit1 beneath the old tertiary strata4 ,this inferior mass must be very much more ancient than the upper deposit with its mammiferous remains1 for it lies beneath the tertiary strata in which all the shells are extinct4 ,nevertheless1 the lower and upper masses1 as well as some intermediate layers1 are so similar in mineralogical character1 that ,i cannot doubt that they are all of estuary origin1 and have been derived from the same great source4 ,at first it appeared to me extremely improbable1 that mud of the same nature should have been deposited on nearly the same spot1 during an immense lapse of time1 namely1 from a period equivalent perhaps to the ,eocene of ,europe to that of the ,pampean formation4 ,but as1 at the very commencement of the ,pampean period1 if not at a still earlier period1 the ,sierra ,ventana formed a boundary to the south1--the ,cordillera or the plains in front of them to the west1--the whole province of ,corrientes probably to the north1 for1 according to ,m4 d',orbigny1 it is not covered by the ,pampean deposit1--and ,brazil1 as known by the remains in the caves1 to the north-east2 and as again1 during the older tertiary period1 land already existed in ,western ,banda ,oriental and near ,st4 ,fe ,bajada1 as may be inferred from the vegetable debris1 from the quantities of silicified wood1 and from the remains of a ,toxodon found1 according to ,m4 d',orbigny1 in still lower strata1 we may conclude1 that at this ancient period a great expanse of water was surrounded by the same rocky framework which now bounds the plains of ,pampean formation4 ,this having been the case1 the circumstance of sediment of the same nature having been deposited in the same area during an immense lapse of time1 though highly remarkable1 does not appear incredible4 ,the elevation of the ,pampas1 at least of the southern parts1 has been slow and interrupted by several periods of rest1 as may be inferred from the plains1 cliffs1 and lines of sand-dunes 7with shells and pumice-pebbles7 standing at different heights4 ,i believe1 also1 that the ,pampean mud continued to be deposited1 after parts of this formation had already been elevated1 in the same manner as mud would continue to be deposited in the estuary of the ,plata1 if the mud-banks on its shores were now uplifted and changed into plains3 ,i believe in this from the improbability of so many skeletons and bones having been accumulated at one spot1 where ,m4 ,hermoso now stands1 at a depth of between eight hundred and one thousand feet1 and at a vast distance from any land except small rocky islets1--as must have been the case1 if the high tosca-plain round the ,ventana and adjoining ,sierras1 had not been already uplifted and converted into land1 supporting mammiferous animals4 ,at ,punta ,alta we have good evidence that the gravel- strata1 which certainly belong to the true ,pampean period1 were accumulated after the elevation in that neighbourhood of the main part of the ,pampean deposit1 whence the rounded masses of tosca-rock were derived1 and that rolled fragment of black bone in the same peculiar condition with the remains at ,monte ,hermoso4 ,the number of the mammiferous remains embedded in the ,pampas is1 as ,i have remarked1 wonderful3 it should be borne in mind that they have almost exclusively been found in the cliffs and steep banks of rivers1 and that1 until lately1 they excited no attention amongst the inhabitants3 ,i am firmly convinced that a deep trench could not be cut in any line across the ,pampas1 without intersecting the remains of some quadruped4 ,it is difficult to form an opinion in what part of the ,pampas they are most numerous2 in a limited spot they could not well have been more numerous than they were at ,p4 ,alta2 the number1 however1 lately found by ,senor ,f4 ,muniz1 near ,luxan1 in a central spot in the ,pampas1 is extraordinarily great3 at the end of this chapter ,i will give a list of all the localities at which ,i have heard of remains having been discovered4 ,very frequently the remains consist of almost perfect skeletons2 but there are1 also1 numerous single bones1 as for instance at ,st4 ,fe4 ,their state of preservation varies much1 even when embedded near each other3 ,i saw none others so perfectly preserved as the heads of the ,toxodon and ,mylodon from the white soft earthy bed on the ,sarandis in ,banda ,oriental4 ,it is remarkable that in two limited sections ,i found no less than five teeth separately embedded1 and ,i heard of teeth having been similarly found in other parts3 may we suppose that the skeletons or heads were for a long time gently drifted by currents over the soft muddy bottom1 and that the teeth occasionally1 here and there1 dropped out8 ,it may be naturally asked1 where did these numerous animals live8 ,from the remarkable discoveries of ,,mm4 ,lund and ,clausen1 it appears that some of the species found in the ,pampas inhabited the highlands of ,brazil3 the ,mastodon ,andium is embedded at great heights in the ,cordillera from north of the equator to at least as far south as ,tarija 7,humboldt states that the ,mastodon has been discovered in ,new ,granada3 it has been found in ,quito4 ,when at ,lima1 ,i saw a tooth of a ,mastodon in the possession of ,don ,m4 ,rivero1 found at ,playa ,chica on the ,maranon1 near the ,guallaga4 ,every one has heard of the numerous remains of ,mastodon in ,bolivia472 and as there is no higher land1 there can be little doubt that this ,mastodon must have lived on the plains and valleys of that great range4 ,these countries1 however1 appear too far distant for the habitation of the individuals entombed in the ,pampas3 we must probably look to nearer points1 for instance to the province of ,corrientes1 which1 as already remarked1 is said not to be covered by the ,pampean formation1 and may therefore1 at the period of its deposition1 have existed as dry land4 ,i have already given my reasons for believing that the animals embedded at ,m4 ,hermoso and at ,p4 ,alta in ,bahia ,blanca1 lived on adjoining land1 formed of parts of the already elevated ,pampean deposit4 ,with respect to the food of these many great extinct quadrupeds1 ,i will not repeat the facts given in my 8,journal0 7second edition page #he71 showing that there is no correlation between the luxuriance of the vegetation of a country and the size of its mammiferous inhabitants4 ,i do not doubt that large animals could now exist1 as far as the amount1 not kind1 of vegetation is concerned1 on the sterile plains of ,bahia ,blanca and of the ,r4 ,negro1 as well as on the equally1 if not more sterile plains of ,southern ,africa4 ,the climate1 however1 may perhaps have somewhat deteriorated since the mammifers embedded at ,bahia ,blanca lived there2 for we must not infer1 from the continued existence of the same shells on the present coasts1 that there has been no change in climate2 for several of these shells now range northward along the shores of ,brazil1 where the most luxuriant vegetation flourishes under a tropical temperature4 ,with respect to the extinction1 which at first fills the mind with astonishment1 of the many great and small mammifers of this period1 ,i may also refer to the work above cited 7second edition page #agc71 in which ,i have endeavoured to show1 that however unable we may be to explain the precise cause1 we ought not properly to feel more surprised at a species becoming extinct than at one being rare2 and yet we are accustomed to view the rarity of any particular species as an ordinary event1 not requiring any extraordinary agency4 ,the several mammifers embedded in the ,pampean formation1 which mostly belong to extinct genera1 and some even to extinct families or orders1 and which differ nearly1 if not quite1 as much as do the ,eocene mammifers of ,europe from living quadrupeds having existed contemporaneously with mollusca1 all still inhabiting the adjoining sea1 is certainly a most striking fact4 ,it is1 however1 far from being an isolated one2 for1 during the late tertiary deposits of ,britain1 an elephant1 rhinoceros1 and hippopotamus co-existed with many recent land and fresh-water shells2 and in ,north ,america1 we have the best evidence that a mastodon1 elephant1 megatherium1 megalonyx1 mylodon1 an extinct horse and ox1 likewise co- existed with numerous land1 fresh-water1 and marine recent shells4 7,many original observations1 and a summary on this subject1 are given in ,mr4 ,lyell's paper in the 8,geological ,proceedings0 volume #d page #c and in his 8,travels in ,north ,america0 volume #a page #afd and volume #b page #fj4 ,for the ,european analogous cases see ,mr4 ,lyell's 8,principles of ,geology0 #fth edition volume #a page #cg47 ,the enumeration of these extinct ,north ,american animals naturally leads me to refer to the former closer relation of the mammiferous inhabitants of the two ,americas1 which ,i have discussed in my 8,journal10 and likewise to the vast extent of country over which some of them ranged3 thus the same species of the ,megatherium1 ,megalonyx1 ,equus 7as far as the state of their remains permits of identification71 extended from the ,southern ,united ,states of ,north ,america to ,bahia ,blanca1 in latitude #ci degrees ,s41 on the coast of ,patagonia4 ,the fact of these animals having inhabited tropical and temperate regions1 does not appear to me any great difficulty1 seeing that at the ,cape of ,good ,hope several quadrupeds1 such as the elephant and hippopotamus1 range from the equator to latitude #ce degrees south4 ,the case of the ,mastodon ,andium is one of more difficulty1 for it is found from latitude #cf degrees ,s41 over1 as ,i have reason to believe1 nearly the whole of ,brazil1 and up the ,cordillera to regions which1 according to ,m4 d',orbigny1 border on perpetual snow1 and which are almost destitute of vegetation3 undoubtedly the climate of the ,cordillera must have been different when the mastodon inhabited it2 but we should not forget the case of the ,siberian mammoth and rhinoceros1 as showing how severe a climate the larger pachydermata can endure2 nor overlook the fact of the guanaco ranging at the present day over the hot low deserts of ,peru1 the lofty pinnacles of the ,cordillera1 and the damp forest-clad land of ,southern ,tierra del ,fuego2 the puma1 also1 is found from the equator to the ,strait of ,magellan1 and ,i have seen its footsteps only a little below the limits of perpetual snow in the ,cordillera of ,chile4 ,at the period1 so recent in a geological sense1 when these extinct mammifers existed1 the two ,americas must have swarmed with quadrupeds1 many of them of gigantic size2 for1 besides those more particularly referred to in this chapter1 we must include in this same period those wonderfully numerous remains1 some few of them specifically1 and others generically related to those of the ,pampas1 discovered by ,,mm4 ,lund and ,clausen in the caves of ,brazil4 ,finally1 the facts here given show how cautious we ought to be in judging of the antiquity of a formation from even a great amount of difference between the extinct and living species in any one class of animals2--we ought even to be cautious in accepting the general proposition1 that change in organic forms and lapse of time are at all1 necessarily1 correlatives4 ,,localities ,,within ,,the ,,region ,,of ,,the ,,pampas ,,where ,,great ,,bones ,,have ,,been ,,found4 ,the following list1 which includes every account which ,i have hitherto met with of the discovery of fossil mammiferous remains in the ,pampas1 may be hereafter useful to a geologist investigating this region1 and it tends to show their extraordinary abundance4 ,i heard of and saw many fossils1 the original position of which ,i could not ascertain2 and ,i received many statements too vague to be here inserted4 ,beginning to the south3--we have the two stations in ,bahia ,blanca1 described in this chapter1 where at ,p4 ,alta1 the ,megatherium1 ,megalonyx1 ,scelidotherium1 ,mylodon1 ,holophractus 7or an allied genus71 ,toxodon1 ,macrauchenia1 and an ,equus were collected2 and at ,m4 ,hermoso a ,ctenomys1 ,hydrochaerus1 some other rodents and the bones of a great megatheroid quadruped4 ,close north-east of the ,s4 ,tapalguen1 we have the ,rios #8,huesos' 7i4e4 8bones071 which probably takes its name from large fossil bones4 ,near ,villa ,nuevo1 and at ,las ,averias1 not far from the ,salado1 three nearly perfect skeletons1 one of the ,megatherium1 one of the ,glyptodon clavipes1 and one of some great ,dasypoid quadruped1 were found by the agent of ,sir ,w4 ,parish 7see his work 8,buenos ,ayres0 etc4 page #aga74 ,i have seen the tooth of a ,mastodon from the ,salado2 a little northward of this river1 on the borders of a lake near the ,g4 del ,monte1 ,i saw many bones1 and one large piece of dermal armour2 higher up the ,salado1 there is a place called ,monte 8,huesos40 ,on the ,matanzas1 about twenty miles south of ,buenos ,ayres1 the skeleton 7vide page #agh of 8,buenos ,ayres0 etc4 by ,sir ,w4 ,parish7 of a ,glyptodon was found about five feet beneath the surface2 here also 7see ,catalogue of ,royal ,college of ,surgeons7 remains of ,glyptodon clavipes1 ,g4 ornatus1 and ,g4 reticulatus were found4 ,signor ,angelis1 in a letter which ,i have seen1 refers to some great remains found in ,buenos ,ayres1 at a depth of twenty varas from the surface4 ,seven leagues north of this city the same author found the skeletons of ,mylodon robustus and ,glyptodon ornatus4 ,from this neighbourhood he has lately sent to the ,british ,museum the following fossils3--,remains of three or four individuals of ,megatherium2 of three species of ,glyptodon2 of three individuals of the ,mastodon ,andium2 of ,macrauchenia2 of a second species of ,toxodon1 different from ,t4 ,platensis2 and lastly1 of the ,machairodus1 a wonderful large carnivorous animal4 ,m4 d',orbigny has lately received from the ,recolate 8,voyage0 ,pal4 page #add71 near ,buenos ,ayres1 a tooth of ,toxodon ,platensis4 ,proceeding northward1 along the west bank of the ,parana1 we come to the ,rio ,luxan1 where two skeletons of the ,megatherium have been found2 and lately1 within eight leagues of the town of ,luxan1 ,dr4 ,f4 ,x4 ,muniz has collected 78,british ,packet0 ,buenos ,ayres ,september #be1 #ahda71 from an average depth of eighteen feet1 very numerous remains1 of no less than1 as he believes1 nine distinct species of mammifers4 ,at ,areco1 large bones have been found1 which are believed1 by the inhabitants1 to have been changed from small bones1 by the water of the river6 ,at ,arrecifes1 the ,glyptodon1 sent to the ,college of ,surgeons1 was found2 and ,i have seen two teeth of a ,mastodon from this quarter4 ,at ,s4 ,nicolas1 ,m4 d',orbigny found remains of a ,canis1 ,ctenomys1 and ,kerodon2 and ,m4 ,isabelle 78,voyage0 page #ccb7 refers to a gigantic ,armadillo found there4 ,at ,s4 ,carlos1 ,i heard of great bones4 ,a little below the mouth of the ,carcarana1 the two skeletons of ,mastodon were found2 on the banks of this river1 near ,s4 ,miguel1 ,i found teeth of the ,mastodon and ,toxodon2 and 8,falkner0 7page #ee7 describes the osseous armour of some great animal2 ,i heard of many other bones in this neighbourhood4 ,i have seen1 ,i may add1 in the possession of ,mr4 ,caldcleugh1 the tooth of a ,mastodon ,andium1 said to have been found in ,paraguay2 ,i may here also refer to a statement in this gentleman's travels 7volume #a page #dh71 of a great skeleton having been found in the province of ,bolivia in ,brazil1 on the ,r4 de las ,contas4 ,the furthest point westward in the ,pampas1 at which ,i have ,,heard of fossil bones1 was high up on the banks of ,r4 ,quinto4 ,in ,entre ,rios1 besides the remains of the ,mastodon1 ,toxodon1 ,equus1 and a great ,dasypoid quadruped near ,st4 ,fe ,bajada1 ,i received an account of bones having been found a little ,s4,e4 of ,p4 ,gorda 7on the ,parana71 and of an entire skeleton at ,matanzas1 on the ,arroyo del ,animal4 ,in ,banda ,oriental1 besides the remains of the ,toxodon1 ,mylodon1 and two skeletons of great animals with osseous armour 7distinct from that of the ,glyptodon71 found on the ,arroyos ,sarandis and ,berquelo1 ,m4 ,isabelle 78,voyage0 page #cbb7 says1 many bones have been found near the ,r4 ,negro1 and on the ,r4 ,arapey1 an affluent of the ,paraguay1 in latitude #cj degrees #dj minutes south4 ,i heard of bones near the source of the ,a4 ,vivoras4 ,i saw the remains of a ,dasypoid quadruped from the ,arroyo ,seco1 close to ,m4 ,video2 and ,m4 d',orbigny refers 78,voyage0 ,geolog4 page #bd71 to another found on the ,pedernal1 an affluent of the ,st4 ,lucia2 and ,signor ,angelis1 in a letter1 states that a third skeleton of this family has been found1 near ,canelones4 ,i saw a tooth of the ,mastodon from ,talas1 another affluent of the ,st4 ,lucia4 ,the most eastern point at which ,i heard of great bones having been found1 was at ,solis ,grande1 between ,m4 ,video and ,maldonado4 ,,chapter ,v4 ,,on ,,the ,,older ,,tertiary ,,formations ,,of ,,patagonia ,,and ,,chile4 ,rio ,negro4--,s4 ,josef4--,port ,desire1 white pumiceous mudstone with ,infusoria4--,port ,s4 ,julian4--,santa ,cruz1 basaltic lava of4--,p4 ,gallegos4--,eastern ,tierra del ,fuego2 leaves of extinct beech-trees4--,summary on the ,patagonian tertiary formations4--,tertiary formations of the ,western ,coast4--,chonos and ,chiloe groups1 volcanic rocks of4--,concepcion4--,navidad4--,coquimbo4 --,summary4--,age of the tertiary formations4--,lines of elevation4--,silicified wood4--,comparative ranges of the extinct and living mollusca on the ,west ,coast of--,s4 ,america4--,climate of the tertiary period4--,on the causes of the absence of recent conchiferous deposits on the coast of ,s4 ,america4--,on the contemporaneous deposition and preservation of sedimentary formations4 ,,rio ,,negro4 ,i can add little to the details given by ,m4 d',orbigny on the sandstone formation of this district4 78,voyage0 ,part ,geolog4 pages #eg-fe47 ,the cliffs to the south of the river are about two hundred feet in height1 and are composed of sandstone of various tints and degrees of hardness4 ,one layer1 which thinned out at both ends1 consisted of earthy matter1 of a pale reddish colour1 with some gypsum1 and very like 7,i speak after comparison of the specimens brought home7 ,pampean mud3 above this was a layer of compact marly rock with dendritic manganese4 ,many blocks of a conglomerate of pumice-pebbles embedded in hard sandstone were strewed at the foot of the cliff1 and had evidently fallen from above4 ,a few miles ,n4,e4 of the town1 ,i found1 low down in the sandstone1 a bed1 a few inches in thickness1 of a white1 friable1 harsh-feeling sediment1 which adheres to the tongue1 is of easy fusibility1 and of little specific gravity2 examined under the microscope1 it is seen to be pumiceous tuff1 formed of broken transparent crystals4 ,in the cliffs south of the river1 there is1 also1 a thin layer of nearly similar nature1 but finer grained1 and not so white2 it might easily have been mistaken for a calcareous tuff1 but it contains no lime3 this substance precisely resembles a most widely extended and thick formation in ,southern ,patagonia1 hereafter to be described1 and which is remarkable for being partially formed of infusoria4 ,these beds1 conjointly with the conglomerate of pumice1 are interesting1 as showing the nature of the volcanic action in the ,cordillera during this old tertiary period4 ,in a bed at the base of the southern cliffs1 ,m4 d',orbigny found two extinct fresh-water shells1 namely1 a ,unio and ,chilina4 ,this bed rested on one with bones of an extinct rodent1 namely1 the ,megamys ,patagoniensis2 and this again on another with extinct marine shells4 ,the species found by ,m4 d',orbigny in different parts of this formation consist of3-- #a4 ,ostrea ,patagonica1 d',orbigny1 8,voyage1 ,pal40 7also at ,st4 ,fe1 and whole coast of ,patagonia74 #b4 ,ostrea ,ferrarisi1 d',orbigny1 8,voyage1 ,pal40 #c4 ,ostrea ,alvarezii1 d',orbigny1 8,voyage1 ,pal40 7also at ,st4 ,fe1 and ,s4 ,josef74 #d4 ,pecten ,patagoniensis1 d',orbigny1 8,voyage1 ,pal40 #e4 ,venus ,munsterii1 d',orbigny1 8,voyage1 ,pal40 7also at ,st4 ,fe74 #f4 ,arca ,bonplandiana1 d',orbigny1 8,voyage1 ,pal40 7also at ,st4 ,fe74 ,according to ,m4 d',orbigny1 the sandstone extends westward along the coast as far as ,port ,s4 ,antonio1 and up the ,r4 ,negro far into the interior3 northward ,i traced it to the southern side of the ,rio ,colorado1 where it forms a low denuded plain4 ,this formation1 though contemporaneous with that of the rest of ,patagonia1 is quite different in mineralogical composition1 being connected with it only by the one thin white layer3 this difference may be reasonably attributed to the sediment brought down in ancient times by the ,rio ,negro2 by which agency1 also1 we can understand the presence of the fresh-water shells1 and of the bones of land animals4 ,judging from the identity of four of the above shells1 this formation is contemporaneous 7as remarked by ,m4 d',orbigny7 with that under the ,pampean deposit in ,entre ,rios and in ,banda ,oriental4 ,the gravel capping the sandstone plain1 with its calcareous cement and nodules of gypsum1 is probably1 from the reasons given in the ,first ,chapter1 contemporaneous with the uppermost beds of the ,pampean formation on the upper plain north of the ,colorado4 ,,san ,,josef4 ,my examination here was very short3 the cliffs are about a hundred feet high2 the lower third consists of yellowish-brown1 soft1 slightly calcareous1 muddy sandstone1 parts of which when struck emit a fetid smell4 ,in this bed the great ,ostraea ,patagonica1 often marked with dendritic manganese and small coral-lines1 were extraordinarily numerous4 ,i found here the following shells3-- #a4 ,ostrea ,patagonica1 d',orbigny1 8,voyage1 ,pal40 7also at ,st4 ,fe and whole coast of ,patagonia74 #b4 ,ostrea ,alvarezii1 d',orbigny1 8,voyage1 ,pal40 7also at ,st4 ,fe and ,r4 ,negro74 #c4 ,pecten ,paranensis1 d',orbigny1 8,voyage1 ,pal40 7also at ,st4 ,fe1 ,s4 ,julian1 and ,port ,desire74 #d4 ,pecten ,darwinianus1 d',orbigny1 8,voyage1 ,pal40 7also at ,st4 ,fe74 #e4 ,pecten actinodes1 ,g4,b4 ,sowerby4 #f4 ,terebratula ,patagonica1 ,g4,b4 ,sowerby 7also ,s4 ,julian74 #g4 ,casts of a ,turritella4 ,the four first of these species occur at ,st4 ,fe in ,entre ,rios1 and the two first in the sandstone of the ,rio ,negro4 ,above this fossiliferous mass1 there is a stratum of very fine-grained1 pale brown mudstone1 including numerous laminae of selenite4 ,all the strata appear horizontal1 but when followed by the eye for a long distance1 they are seen to have a small easterly dip4 ,on the surface we have the porphyritic gravel1 and on it sand with recent shells4 ,,nuevo ,,gulf4 ,from specimens and notes given me by ,lieutenant ,stokes1 it appears that the lower bed consists of soft muddy sandstone1 like that of ,s4 ,josef1 with many imperfect shells1 including the ,pecten ,paranensis1 d',orbigny1 casts of a ,turritella and ,scutella4 ,on this there are two strata of the pale brown mudstone1 also like that of ,s4 ,josef1 separated by a darker-coloured1 more argillaceous variety1 including the ,ostrea ,patagonica4 ,professor ,ehrenberg has examined this mudstone for me3 he finds in it three already known microscopic organisms1 enveloped in a fine-grained pumiceous tuff1 which ,i shall have immediately to describe in detail4 ,specimens brought to me from the uppermost bed1 north of the ,rio ,chupat1 consist of this same substance1 but of a whiter colour4 ,tertiary strata1 such as here described1 appear to extend along the whole coast between ,rio ,chupat and ,port ,desire1 except where interrupted by the underlying claystone porphyry1 and by some metamorphic rocks2 these hard rocks1 ,i may add1 are found at intervals over a space of about five degrees of latitude1 from ,point ,union to a point between ,port ,s4 ,julian and ,s4 ,cruz1 and will be described in the ensuing chapter4 ,many gigantic specimens of the ,ostraea ,patagonica were collected in the ,gulf of ,st4 ,george4 ,,port ,,desire4 ,a good section of the lowest fossiliferous mass1 about forty feet in thickness1 resting on claystone porphyry1 is exhibited a few miles south of the harbour4 ,the shells sufficiently perfect to be recognised consist of3-- #a4 ,ostrea ,patagonica1 d',orbigny1 7also at ,st4 ,fe1 and whole coast of ,patagonia74 #b4 ,pecten ,paranensis1 d',orbigny1 8,voyage1 ,pal40 7also at ,st4 ,fe1 ,s4 ,josef1 ,s4 ,julian74 #c4 ,pecten centralis1 ,g4,b4 ,sowerby 7also at ,s4 ,julian and ,s4 ,cruz74 #d4 ,cucullaea alta1 ,g4,b4 ,sowerby 7also at ,s4 ,cruz74 #e4 ,nucula ornata1 ,g4,b4 ,sowerby4 #f4 ,turritella ,patagonica1 ,g4,b4 ,sowerby4 ,the fossiliferous strata1 when not denuded1 are conformably covered by a considerable thickness of the fine-grained pumiceous mudstone1 divided into two masses3 the lower half is very fine-grained1 slightly unctuous1 and so compact as to break with a semi-conchoidal fracture1 though yielding to the nail2 it includes laminae of selenite3 the upper half precisely resembles the one layer at the ,rio ,negro1 and with the exception of being whiter1 the upper beds at ,san ,josef and ,nuevo ,gulf4 ,in neither mass is there any trace to the naked eye of organic forms4 ,taking the entire deposit1 it is generally quite white1 or yellowish1 or feebly tinted with green2 it is either almost friable under the finger1 or as hard as chalk2 it is of easy fusibility1 of little specific gravity1 is not harsh to the touch1 adheres to the tongue1 and when breathed on exhales a strong aluminous odour2 it sometimes contains a very little calcareous matter1 and traces 7besides the included laminae7 of gypsum4 ,under the microscope1 according to ,professor ,ehrenberg1 it consists of minute1 triturated1 cellular1 glassy fragments of pumice1 with some broken crystals4 78,monatsberichten de konig4 ,akad4 zu ,berlin0 vom ,april #ahde47 ,in the minute glassy fragments1 ,professor ,ehrenberg recognises organic structures1 which have been affected by volcanic heat3 in the specimens from this place1 and from ,port ,s4 ,julian1 he finds sixteen ,polygastrica and twelve ,phytolitharia4 ,of these organisms1 seven are new forms1 the others being previously known3 all are of marine1 and chiefly of oceanic1 origin4 ,this deposit to the naked eye resembles the crust which often appears on weathered surfaces of feldspathic rocks2 it likewise resembles those beds of earthy feldspathic matter1 sometimes interstratified with porphyritic rocks1 as is the case in this very district with the underlying purple claystone porphyry4 ,from examining specimens under a common microscope1 and comparing them with other specimens undoubtedly of volcanic origin1 ,i had come to the same conclusion with ,professor ,ehrenberg1 namely1 that this great deposit1 in its first origin1 is of volcanic nature4 ,,port ,s4 ,,julian4 7,,figure #ag4 ,,section ,,of ,,the ,,strata ,,exhibited ,,in ,,the ,,cliffs ,,of ,,the ,,ninety ,,feet ,,plain ,,at ,,port ,s4 ,,julian4 7,section through beds from top to bottom3 ,a1 ,b1 ,c1 ,d1 ,e1 ,f477 ,on the south side of the harbour1 ,figure #ag gives the nature of the beds seen in the cliffs of the ninety feet plain4 ,beginning at the top3-- #ast1 the earthy mass 7,,aa71 including the remains of the ,macrauchenia1 with recent shells on the surface4 ,second1 the porphyritic shingle 7,b71 which in its lower part is interstratified 7owing1 ,i believe1 to redisposition during denudation7 with the white pumiceous mudstone4 ,third1 this white mudstone1 about twenty feet in thickness1 and divided into two varieties 7,c and ,d71 both closely resembling the lower1 fine- grained1 more unctuous and compact kind at ,port ,desire2 and1 as at that place1 including much selenite4 ,fourth1 a fossiliferous mass1 divided into three main beds1 of which the uppermost is thin1 and consists of ferruginous sandstone1 with many shells of the great oyster and ,pecten ,paranensis2 the middle bed 7,e7 is a yellowish earthy sandstone abounding with ,scutellae2 and the lowest bed 7,f7 is an indurated1 greenish1 sandy clay1 including large concretions of calcareous sandstone1 many shells of the great oyster1 and in parts almost made up of fragments of ,balanidae4 ,out of these three beds1 ,i procured the following twelve species1 of which the two first were exceedingly numerous in individuals1 as were the ,terebratulae and ,turritellae in certain layers3-- #a4 ,ostrea ,patagonica1 d',orbigny1 8,voyage1 ,pal40 7also at ,st4 ,fe1 and whole coast of ,patagonia74 #b4 ,pecten ,paranensis1 d',orbigny1 8,voyage1 ,pal40 7,st4 ,fe1 ,s4 ,josef1 ,port ,desire74 #c4 ,pecten centralis1 ,g4,b4 ,sowerby 7also at ,port ,desire and ,s4 ,cruz74 #d4 ,pecten geminatus1 ,g4,b4 ,sowerby4 #e4 ,terebratula ,patagonica1 ,g4,b4 ,sowerby 7also ,s4 ,josef74 #f4 ,struthiolaria ornata1 ,g4,b4 ,sowerby 7also ,s4 ,cruz74 #g4 ,fusus ,patagonicus1 ,g4,b4 ,sowerby4 #h4 ,fusus ,noachinus1 ,g4,b4 ,sowerby4 #i4 ,scalaria rugulosa1 ,g4,b4 ,sowerby4 #aj4 ,turritella ambulacrum1 ,g4,b4 ,sowerby 7also ,s4 ,cruz74 #aa4 ,pyrula1 cast of1 like ,p4 ventricosa of ,sowerby1 ,tank ,cat4 #ab4 ,balanus varians1 ,g4,b4 ,sowerby4 #ac4 ,scutella1 differing from the species from ,nuevo ,gulf4 ,at the head of the inner harbour of ,port ,s4 ,julian1 the fossiliferous mass is not displayed1 and the sea-cliffs from the water's edge to a height of between one and two hundred feet are formed of the white pumiceous mudstone1 which here includes innumerable1 far-extended1 sometimes horizontal1 sometimes inclined or vertical laminae of transparent gypsum1 often about an inch in thickness4 ,further inland1 with the exception of the superficial gravel1 the whole thickness of the truncated hills1 which represent a formerly continuous plain #iej feet in height1 appears to be formed of this white mudstone3 here and there1 however1 at various heights1 thin earthy layers1 containing the great oyster1 ,pecten ,paranensis and ,turritella ambulacrum1 are interstratified2 thus showing that the whole mass belongs to the same epoch4 ,i nowhere found even a fragment of a shell actually in the white deposit1 and only a single cast of a ,turritella4 ,out of the eighteen microscopic organisms discovered by ,ehrenberg in the specimens from this place1 ten are common to the same deposit at ,port ,desire4 ,i may add that specimens of this white mudstone1 with the same identical characters were brought me from two points1--one twenty miles north of ,s4 ,julian1 where a wide gravel-capped plain1 #cej feet in height1 is thus composed2 and the other forty miles south of ,s4 ,julian1 where1 on the old charts1 the cliffs are marked as 8,chalk ,hills40 ,,santa ,,cruz4 ,the gravel-capped cliffs at the mouth of the river are #cee feet in height3 the lower part1 to a thickness of fifty or sixty feet1 consists of a more or less hardened1 darkish1 muddy1 or argillaceous sandstone 7like the lowest bed of ,port ,desire71 containing very many shells1 some silicified and some converted into yellow calcareous spar4 ,the great oyster is here numerous in layers2 the ,trigonocelia and ,turritella are also very numerous3 it is remarkable that the ,pecten ,paranensis1 so common in all other parts of the coast1 is here absent3 the shells consist of3-- #a4 ,ostrea ,patagonica1 d',orbigny2 8,voyage ,pal40 7also at ,st4 ,fe and whole coast of ,patagonia74 #b4 ,pecten centralis1 ,g4,b4 ,sowerby 7also ,p4 ,desire and ,s4 ,julian74 #c4 ,venus meridionalis of ,g4,b4 ,sowerby4 #d4 ,crassatella ,lyellii1 ,g4,b4 ,sowerby4 #e4 ,cardium puelchum1 ,g4,b4 ,sowerby4 #f4 ,cardita ,patagonica1 ,g4,b4 ,sowerby4 #g4 ,mactra rugata1 ,g4,b4 ,sowerby4 #h4 ,mactra ,darwinii1 ,g4,b4 ,sowerby4 #i4 ,cucullaea alta1 ,g4,b4 ,sowerby 7also ,p4 ,desire74 #aj4 ,trigonocelia insolita1 ,g4,b4 ,sowerby4 #aa4 ,nucula 787 glabra1 ,g4,b4 ,sowerby4 #ab4 ,crepidula gregaria1 ,g4,b4 ,sowerby4 #ac4 ,voluta alta1 ,g4,b4 ,sowerby4 #ad4 ,trochus collaris1 ,g4,b4 ,sowerby4 #ae4 ,natica solida 7871 ,g4,b4 ,sowerby #af4 ,struthiolaria ornata1 ,g4,b4 ,sowerby 7also ,p4 ,desire74 #ag4 ,turritella ambulacrum1 ,g4,b4 ,sowerby 7also ,p4 ,s4 ,julian74 ,imperfect fragments of the genera ,byssoarca1 ,artemis1 and ,fusus4 ,the upper part of the cliff is generally divided into three great strata1 differing slightly in composition1 but essentially resembling the pumiceous mudstone of the places farther north2 the deposit1 however1 here is more arenaceous1 of greater specific gravity1 and not so white3 it is interlaced with numerous thin veins1 partially or quite filled with transverse fibres of gypsum2 these fibres were too short to reach across the vein1 have their extremities curved or bent3 in the same veins with the gypsum1 and likewise in separate veins as well as in little nests1 there is much powdery sulphate of magnesia 7as ascertained by ,mr4 ,reeks7 in an uncompressed form3 ,i believe that this salt has not heretofore been found in veins4 ,of the three beds1 the central one is the most compact1 and more like ordinary sandstone3 it includes numerous flattened spherical concretions1 often united like a necklace1 composed of hard calcareous sandstone1 containing a few shells3 some of these concretions were four feet in diameter1 and in a horizontal line nine feet apart1 showing that the calcareous matter must have been drawn to the centres of attraction1 from a distance of four feet and a half on both sides4 ,in the upper and lower finer-grained strata1 there were other concretions of a grey colour1 containing calcareous matter1 and so fine-grained and compact1 as almost to resemble porcelain- rock3 ,i have seen exactly similar concretions in a volcanic tufaceous bed in ,chiloe4 ,although in this upper fine-grained strata1 organic remains were very rare1 yet ,i noticed a few of the great oyster2 and in one included soft ferruginous layer1 there were some specimens of the ,cucullaea alta 7found at ,port ,desire in the lower fossiliferous mass7 and of the ,mactra rugata1 which latter shell has been partially converted into gypsum4 7,,figure #ah4 ,,section ,,of ,,the ,,plains ,,of ,,patagonia1 ,,on ,,the ,,banks ,,of ,,the ,s4 ,,cruz4 7,section through strata 7from top to bottom773 ,surface of plain with erratic boulders2 #a1adf feet above the sea4 a4 ,gravel and boulders1 #bab feet thick4 b4 ,basaltic lava1 #cbb feet thick4 c1 d and e4 ,sedimentary layers1 bed of small pebbles and talus respectively1 total #eib feet thick4 ,river of ,s4 ,cruz2 here #bhj feet above sea47 ,in ascending the valley of the ,s4 ,cruz1 the upper strata of the coast- cliffs are prolonged1 with nearly the same characters1 for fifty miles3 at about this point1 they begin in the most gradual and scarcely perceptible manner1 to be banded with white lines2 and after ascending ten miles farther1 we meet with distinct thin layers of whitish1 greenish1 and yellowish fine-grained1 fusible sediments4 ,at eighty miles from the coast1 in a cliff thus composed1 there were a few layers of ferruginous sandstone1 and of an argillaceous sandstone with concretions of marl like those in the ,pampas4 7,at this spot1 for a space of three-quarters of a mile along the north side of the river1 and for a width of half a mile1 there has been a great slip1 which has formed hills between sixty and seventy feet in height1 and has tilted the strata into highly inclined and even vertical positions4 ,the strata generally dipped at an angle of #de degrees towards the cliff from which they had slided4 ,i have observed in slips1 both on a small and large scale1 that this inward dip is very general4 ,is it due to the hydrostatic pressure of water percolating with difficulty through the strata acting with greater force at the base of the mass than against the upper part87 ,at one hundred miles from the coast1 that is at a central point between the ,atlantic and the ,cordillera1 we have the section in ,figure #ah4 ,the upper half of the sedimentary mass1 under the basaltic lava1 consists of innumerable zones of perfectly white bright green1 yellowish and brownish1 fine-grained1 sometimes incoherent1 sedimentary matter4 ,the white1 pumiceous1 trachytic tuff-like varieties are of rather greater specific gravity than the pumiceous mudstone on the coast to the north2 some of the layers1 especially the browner ones1 are coarser1 so that the broken crystals are distinguishable with a weak lens4 ,the layers vary in character in short distances4 ,with the exception of a few of the ,ostrea ,patagonica1 which appeared to have rolled down from the cliff above1 no organic remains were found4 ,the chief difference between these layers taken as a whole1 and the upper beds both at the mouth of the river and on the coast northward1 seems to lie in the occasional presence of more colouring matter1 and in the supply having been intermittent2 these characters1 as we have seen1 very gradually disappear in descending the valley1 and this fact may perhaps be accounted for by the currents of a more open sea having blended together the sediment from a distant and intermittent source4 ,the coloured layers in the foregoing section rest on a mass1 apparently of great thickness 7but much hidden by the talus71 of soft sandstone1 almost composed of minute pebbles1 from one-tenth to two-tenths of an inch in diameter1 of the rocks 7with the entire exception of the basaltic lava7 composing the great boulders on the surface of the plain1 and probably composing the neighbouring ,cordillera4 ,five miles higher up the valley1 and again thirty miles higher up 7that is twenty miles from the nearest range of the ,cordillera71 the lower plain included within the upper escarpments1 is formed1 as seen on the banks of the river1 of a nearly similar but finer-grained1 more earthy1 laminated sandstone1 alternating with argillaceous beds1 and containing numerous moderately sized pebbles of the same rocks1 and some shells of the great ,ostrea ,patagonica4 7,i found at both places1 but not in situ1 quantities of coniferous and ordinary dicotyledonous silicified wood1 which was examined for me by ,mr4 ,r4 ,brown47 ,as most of these shells had been rolled before being here embedded1 their presence does not prove that the sandstone belongs to the great ,patagonian tertiary formation1 for they might have been redeposited in it1 when the valley existed as a sea-strait2 but as amongst the pebbles there were none of basalt1 although the cliffs on both sides of the valley are composed of this rock1 ,i believe that the sandstone does belong to this formation4 ,at the highest point to which we ascended1 twenty miles distant from the nearest slope of the ,cordillera1 ,i could see the horizontally zoned white beds1 stretching under the black basaltic lava1 close up to the mountains2 so that the valley of the ,s4 ,cruz gives a fair idea of the constitution of the whole width of ,patagonia4 ,,basaltic ,,lava ,,of ,,the ,s4 ,,cruz4 ,this formation is first met with sixty-seven miles from the mouth of the river2 thence it extends uninterruptedly1 generally but not exclusively on the northern side of the valley1 close up to the ,cordillera4 ,the basalt is generally black and fine-grained1 but sometimes grey and laminated2 it contains some olivine1 and high up the valley much glassy feldspar1 where1 also1 it is often amygdaloidal2 it is never highly vesicular1 except on the sides of rents and on the upper and lower1 spherically laminated surfaces4 ,it is often columnar2 and in one place ,i saw magnificent columns1 each face twelve feet in width1 with their interstices filled up with calcareous tuff4 ,the streams rest conformably on the white sedimentary beds1 but ,i nowhere saw the actual junction2 nor did ,i anywhere see the white beds actually superimposed on the lava2 but some way up the valley at the foot of the uppermost escarpments1 they must be thus superimposed4 ,moreover1 at the lowest point down the valley1 where the streams thin out and terminate in irregular projections1 the spaces or intervals between these projections are filled up to the level of the now denuded and gravel-capped surfaces of the plains1 with the white-zoned sedimentary beds2 proving that this matter continued to be deposited after the streams had flowed4 ,hence we may conclude that the basalt is contemporaneous with the upper parts of the great tertiary formation4 ,the lava where first met with is #acj feet in thickness3 it there consists of two1 three1 or perhaps more streams1 divided from each other by vesicular spheroids like those on the surface4 ,from the streams having1 as it appears1 extended to different distances1 the terminal points are of unequal heights4 ,generally the surface of the basalt is smooth them in one part high up the valley1 it was so uneven and hummocky1 that until ,i afterwards saw the streams extending continuously on both sides of the valley up to a height of about three thousand feet close to the ,cordillera1 ,i thought that the craters of eruption were probably close at hand4 ,this hummocky surface ,i believe to have been caused by the crossing and heaping up of different streams4 ,in one place1 there were several rounded ridges about twenty feet in height1 some of them as broad as high1 and some broader1 which certainly had been formed whilst the lava was fluid1 for in transverse sections each ridge was seen to be concentrically laminated1 and to be composed of imperfect columns radiating from common centres1 like the spokes of wheels4 ,the basaltic mass where first met with is1 as ,i have said1 #acj feet in thickness1 and1 thirty-five miles higher up the valley1 it increases to #cbb feet4 ,in the first fourteen and a half miles of this distance1 the upper surface of the lava1 judging from three measurements taken above the level of the river 7of which the apparently very uniform inclination has been calculated from its total height at a point #ace miles from the mouth71 slopes towards the ,atlantic at an angle of only #j degrees #g minutes twenty seconds3 this must be considered only as an approximate measurement1 but it cannot be far wrong4 ,taking the whole thirty-five miles1 the upper surface slopes at an angle of #j degrees #aj minutes #ec seconds2 but this result is of no value in showing the inclination of any one stream1 for halfway between the two points of measurement1 the surface suddenly rises between one hundred and two hundred feet1 apparently caused by some of the uppermost streams having extended thus far and no farther4 ,from the measurement made at these two points1 thirty-five miles apart1 the mean inclination of the sedimentary beds1 over which the lava has flowed1 is ,,now 7after elevation from under the sea7 only #j degrees #g minutes #eb seconds3 for the sake of comparison1 it may be mentioned that the bottom of the present sea in a line from the mouth of the ,s4 ,cruz to the ,falkland ,islands1 from a depth of seventeen fathoms to a depth of eighty-five fathoms1 declines at an angle of #j degrees #a minute #bb seconds2 between the beach and the depth of seventeen fathoms1 the slope is greater4 ,from a point about half-way up the valley1 the basaltic mass rises more abruptly towards the foot of the ,cordillera1 namely1 from a height of #a1bjd feet1 to about #c1jjj feet above the sea4 ,this great deluge of lava is worthy1 in its dimensions1 of the great continent to which it belongs4 ,the aggregate streams have flowed from the ,cordillera to a distance 7unparalleled1 ,i believe1 in any case yet known7 of about one hundred geographical miles4 ,near their furthest extremity their total thickness is #acj feet1 which increase thirty-five miles farther inland1 as we have just seen1 to #cbb feet4 ,the least inclination given by ,m4 ,e4 de ,beaumont of the upper surface of a lava-stream1 namely #j degrees #cj minutes1 is that of the great subaerial eruption in #aghc from ,skaptar ,jukul in ,iceland2 and ,m4 ,e4 de ,beaumont shows that it must have flowed down a mean inclination of less than #j degrees #bj minutes4 78,memoires pour servir0 etc4 pages #agh and #bag47 ,but we now see that under the pressure of the sea1 successive streams have flowed over a smooth bottom with a mean inclination of not more than #j degrees #g minutes #eb seconds2 and that the upper surface of the terminal portion 7over a space of fourteen and a half miles7 has an inclination of not more than #j degrees #g minutes #bj seconds4 ,if the elevation of ,patagonia has been greater nearer the ,cordillera than near the ,atlantic 7as is probable71 then these angles are now all too large4 ,i must repeat1 that although the foregoing measurements1 which were all carefully taken with the barometer1 may not be absolutely correct1 they cannot be widely erroneous4 ,southward of the ,s4 ,cruz1 the cliffs of the #hdj feet plain extend to ,coy ,inlet1 and owing to the naked patches of the white sediment1 they are said on the charts to be 8like the coast of ,kent40 ,at ,coy ,inlet the high plain trends inland1 leaving flat-topped outliers4 ,at ,port ,gallegos 7latitude #ea degrees #ce minutes1 and ninety miles south of ,s4 ,cruz71 ,i am informed by ,captain ,sulivan1 ,r4,n41 that there is a gravel-capped plain from two to three hundred feet in height1 formed of numerous strata1 some fine-grained and pale-coloured1 like the upper beds at the mouth of the ,s4 ,cruz1 others rather dark and coarser1 so as to resemble gritstones or tuffs2 these latter include rather large fragments of apparently decomposed volcanic rocks2 there are1 also1 included layers of gravel4 ,this formation is highly remarkable1 from abounding with mammiferous remains1 which have not as yet been examined by ,professor ,owen1 but which include some large1 but mostly small1 species of ,pachydermata1 ,edentata1 and ,rodentia4 ,from the appearance of the pale-coloured1 fine-grained beds1 ,i was inclined to believe that they corresponded with the upper beds of the ,s4 ,cruz2 but ,professor ,ehrenberg1 who has examined some of the specimens1 informs me that the included microscopical organisms are wholly different1 being fresh and brackish-water forms4 ,hence the two to three hundred feet plain at ,port ,gallegos is of unknown age1 but probably of subsequent origin to the great ,patagonian tertiary formation4 ,,eastern ,,tierra ,,del ,,fuego4 ,judging from the height1 the general appearance1 and the white colour of the patches visible on the hill sides1 the uppermost plain1 both on the north and western side of the ,strait of ,magellan1 and along the eastern coast of ,tierra del ,fuego as far south as near ,port ,st4 ,polycarp1 probably belongs to the great ,patagonian tertiary formation1 ,these higher table- ranges are fringed by low1 irregular1 extensive plains1 belonging to the boulder formation 7,described in the 8,geological ,transactions0 volume #f page #dae471 and composed of coarse unstratified masses1 sometimes associated 7as north of ,c4 ,virgin's7 with fine1 laminated1 muddy sandstones4 ,the cliffs in ,sebastian ,bay are #bjj feet in height1 and are composed of fine sandstones1 often in curvilinear layers1 including hard concretions of calcareous sandstone1 and layers of gravel4 ,in these beds there are fragments of wood1 legs of crabs1 barnacles encrusted with corallines still partially retaining their colour1 imperfect fragments of a ,pholas distinct from any known species1 and of a ,venus1 approaching very closely to1 but slightly different in form from1 the ,v4 lenticularis1 a species living on the coast of ,chile4 ,leaves of trees are numerous between the laminae of the muddy sandstone2 they belong1 as ,i am informed by ,dr4 ,j4,d4 ,hooker1 to three species of deciduous beech1 different from the two species which compose the great proportion of trees in this forest-clad land4 78,botany of the ,antarctic ,voyage0 page #bab47 ,from these facts it is difficult to conjecture1 whether we here see the basal part of the great ,patagonian formation1 or some later deposit4 ,a ,,summary ,,on ,,the ,,patagonian ,,tertiary ,,formation4 ,four out of the seven fossil shells1 from ,st4 ,fe in ,entre ,rios1 were found by ,m4 d',orbigny in the sandstone of the ,rio ,negro1 and by me at ,san ,josef4 ,three out of the six from ,san ,josef are identical with those from ,port ,desire and ,s4 ,julian1 which two places have together fifteen species1 out of which three are common to both4 ,santa ,cruz has seventeen species1 out of which five are common to ,port ,desire and ,s4 ,julian4 ,considering the difference in latitude between these several places1 and the small number of species altogether collected1 namely thirty-six1 ,i conceive the above proportional number of species in common1 is sufficient to show that the lower fossiliferous mass belongs nearly1 ,i do not say absolutely1 to the same epoch4 ,what this epoch may be1 compared with the ,european tertiary stages1 ,m4 d',orbigny will not pretend to determine4 ,the thirty-six species 7including those collected by myself and by ,m4 d',orbigny7 are all extinct1 or at least unknown2 but it should be borne in mind1 that the present coast consists of shingle1 and that no one1 ,i believe1 has dredged here for shells2 hence it is not improbable that some of the species may hereafter be found living4 ,some few of the species are closely related with existing ones2 this is especially the case1 according to ,m4 d',orbigny and ,mr4 ,sowerby1 with the ,fusus ,patagonicus2 and1 according to ,mr4 ,sowerby1 with the ,pyrula1 the ,venus meridionalis1 the ,crepidula gregaria1 and the ,turritella ambulacrum1 and ,t4 ,patagonica4 ,at least three of the genera1 namely1 ,cucullaea1 ,crassatella1 and 7as determined by ,mr4 ,sowerby7 ,struthiolaria1 are not found in this quarter of the world2 and ,trigonocelia is extinct4 ,the evidence taken altogether indicates that this great tertiary formation is of considerable antiquity2 but when treating of the ,chilean beds1 ,i shall have to refer again to this subject4 ,the white pumiceous mudstone1 with its abundant gypsum1 belongs to the same general epoch with the underlying fossiliferous mass1 as may be inferred from the shells included in the intercalated layers at ,nuevo ,gulf1 ,s4 ,julian1 and ,s4 ,cruz4 ,out of the twenty-seven marine microscopic structures found by ,professor ,ehrenberg in the specimens from ,s4 ,julian and ,port ,desire1 ten are common to these two places3 the three found at ,nuevo ,gulf are distinct4 ,i have minutely described this deposit1 from its remarkable characters and its wide extension4 ,from ,coy ,inlet to ,port ,desire1 a distance of #bcj miles1 it is certainly continuous2 and ,i have reason to believe that it likewise extends to the ,rio ,chupat1 ,nuevo ,gulf1 and ,san ,josef1 a distance of #egj miles3 we have1 also1 seen that a single layer occurs at the ,rio ,negro4 ,at ,port ,s4 ,julian it is from eight to nine hundred feet in thickness2 and at ,s4 ,cruz it extends1 with a slightly altered character1 up to the ,cordillera4 ,from its microscopic structure1 and from its analogy with other formations in volcanic districts1 it must be considered as originally of volcanic origin3 it may have been formed by the long-continued attrition of vast quantities of pumice1 or judging from the manner in which the mass becomes1 in ascending the valley of ,s4 ,cruz1 divided into variously coloured layers1 from the long-continued eruption of clouds of fine ashes4 ,in either case1 we must conclude1 that the southern volcanic orifices of the ,cordillera1 now in a dormant state1 were at about this period over a wide space1 and for a great length of time1 in action4 ,we have evidence of this fact1 in the latitude of the ,rio ,negro1 in the sandstone-conglomerate with pumice1 and demonstrative proof of it1 at ,s4 ,cruz1 in the vast deluges of basaltic lava3 at this same tertiary period1 also1 there is distinct evidence of volcanic action in ,western ,banda ,oriental4 ,the ,patagonian tertiary formation extends continuously1 judging from fossils alone1 from ,s4 ,cruz to near the ,rio ,colorado1 a distance of above six hundred miles1 and reappears over a wide area in ,entre ,rios and ,banda ,oriental1 making a total distance of #a1ajj miles2 but this formation undoubtedly extends 7though no fossils were collected7 far south of the ,s4 ,cruz1 and1 according to ,m4 d',orbigny1 #abj miles north of ,st4 ,fe4 ,at ,s4 ,cruz we have seen that it extends across the continent2 being on the coast about eight hundred feet in thickness 7and rather more at ,s4 ,julian71 and rising with the contemporaneous lava-streams to a height of about three thousand feet at the base of the ,cordillera4 ,it rests1 wherever any underlying formation can be seen1 on plutonic and metamorphic rocks4 ,including the newer ,pampean deposit1 and those strata in ,eastern ,tierra del ,fuego of doubtful age1 as well as the boulder formation1 we have a line of more than twenty-seven degrees of latitude1 equal to that from the ,straits of ,gibraltar to the south of ,iceland1 continuously composed of tertiary formations4 ,throughout this great space the land has been upraised1 without the strata having been in a single instance1 as far as my means of observation went1 unequally tilted or dislocated by a fault4 ,,tertiary ,,formations ,,on ,,the ,,west ,,coast4 ,,chonos ,,archipelago4 ,the numerous islands of this group1 with the exception of ,lemus1 ,ypun1 consist of metamorphic schists2 these two islands are formed of softish grey and brown1 fusible1 often laminated sandstones1 containing a few pebbles1 fragments of black lignite1 and numerous mammillated concretions of hard calcareous sandstone4 ,out of these concretions at ,ypun 7latitude #dj degrees #cj minutes ,s471 ,i extracted the four following extinct species of shells3-- #a4 ,turritella suturalis1 ,g4,b4 ,sowerby 7also ,navidad74 #b4 ,sigaretus subglobosus1 ,g4,b4 ,sowerby 7also ,navidad74 #c4 ,cytheraea 787 sulculosa 7871 ,g4,b4 ,sowerby 7also ,chiloe and ,huafo874 #d4 ,voluta1 fragments of4 ,in the northern parts of this group there are some cliffs of gravel and of the boulder formation4 ,in the southern part 7at ,p4 ,andres in ,tres ,montes71 there is a volcanic formation1 probably of tertiary origin4 ,the lavas attain a thickness of from two to three hundred feet2 they are extremely variable in colour and nature1 being compact1 or brecciated1 or cellular1 or amygdaloidal with zeolite1 agate and bole1 or porphyritic with glassy albitic feldspar4 ,there is also much imperfect rubbly pitchstone1 with the interstices charged with powdery carbonate of lime apparently of contemporaneous origin4 ,these lavas are conformably associated with strata of breccia and of brown tuff containing lignite4 ,the whole mass has been broken up and tilted at an angle of #de degrees1 by a series of great volcanic dikes1 one of which was thirty yards in breadth4 ,this volcanic formation resembles one1 presently to be described1 in ,chiloe4 ,,huafo4 ,this island lies between the ,chonos and ,chiloe groups3 it is about eight hundred feet high1 and perhaps has a nucleus of metamorphic rocks4 ,the strata which ,i examined consisted of fine-grained muddy sandstones1 with fragments of lignite and concretions of calcareous sandstone4 ,i collected the following extinct shells1 of which the ,turritella was in great numbers3-- #a4 ,bulla cosmophila1 ,g4,b4 ,sowerby4 #b4 ,pleurotoma subaequalis1 ,g4,b4 ,sowerby4 #c4 ,fusus cleryanus1 d',orbigny1 8,voyage ,pal40 7also at ,coquimbo74 #d4 ,triton leucostomoides1 ,g4,b4 ,sowerby4 #e4 ,turritella ,chilensis1 ,g4,b4 ,sowerby 7also ,mocha74 #f4 ,venus1 probably a distinct species1 but very imperfect4 #g4 ,cytheraea 787 sulculosa 7871 probably a distinct species1 but very imperfect4 #h4 ,dentalium majus1 ,g4,b4 ,sowerby4 ,,chiloe4 ,this fine island is about one hundred miles in length4 ,the entire southern part1 and the whole western coast1 consists of mica-schist1 which likewise is seen in the ravines of the interior4 ,the central mountains rise to a height of #c1jjj feet1 and are said to be partly formed of granite and greenstone3 there are two small volcanic districts4 ,the eastern coast1 and large parts of the northern extremity of the island are composed of gravel1 the boulder formation1 and underlying horizontal strata4 ,the latter are well displayed for twenty miles north and south of ,castro2 they vary in character from common sandstone to fine-grained1 laminated mudstones3 all the specimens which ,i examined are easily fusible1 and some of the beds might be called volcanic grit-stones4 ,these latter strata are perhaps related to a mass of columnar trachyte which occurs behind ,castro4 ,the sandstone occasionally includes pebbles1 and many fragments and layers of lignite2 of the latter1 some are apparently formed of wood and others of leaves3 one layer on the ,n4,w4 side of ,lemuy is nearly two feet in thickness4 ,there is also much silicified wood1 both common dicotyledonous and coniferous3 a section of one specimen in the direction of the medullary rays has1 as ,i am informed by ,mr4 ,r4 ,brown1 the discs in a double row placed alternately1 and not opposite as in the true ,araucaria4 ,i found marine remains only in one spot1 in some concretions of hard calcareous sandstone3 in several other districts ,i have observed that organic remains were exclusively confined to such concretions2 are we to account for this fact1 by the supposition that the shells lived only at these points1 or is it not more probable that their remains were preserved only where concretions were formed8 ,the shells here are in a bad state1 they consist of3-- #a4 ,tellinides 787 oblonga1 ,g4,b4 ,sowerby 7a solenella in ,m4 d',orbigny's opinion74 #b4 ,natica striolata1 ,g4,b4 ,sowerby4 #c4 ,natica 787 pumila1 ,g4,b4 ,sowerby4 #d4 ,cytheraea 787 sulculosa1 ,g4,b4 ,sowerby 7also ,ypun and ,huafo874 ,at the northern extremity of the island1 near ,s4 ,carlos1 there is a large volcanic formation1 between five and seven hundred feet in thickness4 ,the commonest lava is blackish-grey or brown1 either vesicular1 or amygdaloidal with calcareous spar and bole3 most even of the darkest varieties fuse into a pale-coloured glass4 ,the next commonest variety is a rubbly1 rarely well characterised pitchstone 7fusing into a white glass7 which passes in the most irregular manner into stony grey lavas4 ,this pitchstone1 as well as some purple claystone porphyry1 certainly flowed in the form of streams4 ,these various lavas often pass1 at a considerable depth from the surface1 in the most abrupt and singular manner into wacke4 ,great masses of the solid rock are brecciated1 and it was generally impossible to discover whether the recementing process had been an igneous or aqueous action4 7,in a cliff of the hardest fragmentary mass1 ,i found several tortuous1 vertical veins1 varying in thickness from a few tenths of an inch to one inch and a half1 of a substance which ,i have not seen described4 ,it is glossy1 and of a brown colour2 it is thinly laminated1 with the laminae transparent and elastic2 it is a little harder than calcareous spar2 it is infusible under the blowpipe1 sometimes decrepitates1 gives out water1 curls up1 blackens1 and becomes magnetic4 ,borax easily dissolves a considerable quantity of it1 and gives a glass tinged with green4 ,i have no idea what its true nature is4 ,on first seeing it1 ,i mistook it for lignite67 ,the beds are obscurely separated from each other2 they are sometimes parted by seams of tuff and layers of pebbles4 ,in one place they rested on1 and in another place were capped by1 tuffs and girt-stones1 apparently of submarine origin4 ,the neighbouring peninsula of ,lacuy is almost wholly formed of tufaceous deposits1 connected probably in their origin with the volcanic hills just described4 ,the tuffs are pale-coloured1 alternating with laminated mudstones and sandstones 7all easily fusible71 and passing sometimes into fine-grained white beds strikingly resembling the great upper infusorial deposit of ,patagonia1 and sometimes into brecciolas with pieces of pumice in the last stage of decay2 these again pass into ordinary coarse breccias and conglomerates of hard rocks4 ,within very short distances1 some of the finer tuffs often passed into each other in a peculiar manner1 namely1 by irregular polygonal concretions of one variety increasing so much and so suddenly in size1 that the second variety1 instead of any longer forming the entire mass1 was left merely in thin veins between the concretions4 ,in a straight line of cliffs1 at ,point ,tenuy1 ,i examined the following remarkable section 7,figure #ai73-- 7,,figure #ai47 ,on the left hand1 the lower part 7,,aa7 consists of regular1 alternating strata of brown tuffs and greenish laminated mudstone1 gently inclined to the right1 and conformably covered by a mass 7,b left7 of a white1 tufaceous and brecciolated deposit4 ,on the right hand1 the whole cliff 7,,bb right7 consists of the same white tufaceous matter1 which on this side presents scarcely a trace of stratification1 but to the left becomes very gradually and rather indistinctly divided into strata quite conformable with the underlying beds 7,,aa73 moreover1 a few hundred yards further to the left1 where the surface has been less denuded1 the tufaceous strata 7,b left7 are conformably covered by another set of strata1 like the underlying ones 7,,aa7 of this section4 ,in the middle of the diagram1 the beds 7,,aa7 are seen to be abruptly cut off1 and to abut against the tufaceous non-stratified mass2 but the line of junction has been accidentally not represented steep enough1 for ,i particularly noticed that before the beds had been tilted to the right1 this line must have been nearly vertical4 ,it appears that a current of water cut for itself a deep and steep submarine channel1 and at the same time or afterwards filled it up with the tufaceous and brecciolated matter1 and spread the same over the surrounding submarine beds2 the matter becoming stratified in these more distant and less troubled parts1 and being moreover subsequently covered up by other strata 7like ,,aa7 not shown in the diagram4 ,it is singular that three of the beds 7of ,,aa7 are prolonged in their proper direction1 as represented1 beyond the line of junction into the white tufaceous matter3 the prolonged portions of two of the beds are rounded2 in the third1 the terminal fragment has been pushed upwards3 how these beds could have been left thus prolonged1 ,i will not pretend to explain4 ,in another section on the opposite side of a promontory1 there was at the foot of this same line of junction1 that is at the bottom of the old submarine channel1 a pile of fragments of the strata 7,,aa71 with their interstices filled up with white tufaceous matter3 this is exactly what might have been anticipated under such circumstances4 7,,figure #bj4 ,,ground ,,plan ,,showing ,,the ,,relation ,,between ,,veins ,,and ,,concretionary ,,zones ,,in ,a ,,mass ,,of ,,tuff47 ,the various tufaceous and other beds at this northern end of ,chiloe probably belong to about the same age with those near ,castro1 and they contain1 as there1 many fragments of black lignite and of silicified and pyritous wood1 often embedded close together4 ,they also contain many and singular concretions3 some are of hard calcareous sandstone1 in which it would appear that broken volcanic crystals and scales of mica have been better preserved 7as in the case of the organic remains near ,castro7 than in the surrounding mass4 ,other concretions in the white brecciola are of a hard1 ferruginous1 yet fusible1 nature2 they are as round as cannon-balls1 and vary from two or three inches to two feet in diameter2 their insides generally consist either of fine1 scarcely coherent volcanic sand 7,the frequent tendency in iron to form hollow concretions or shell containing incoherent matter is singular2 ,d',aubuisson 78,traite de ,geogn40 tome #a page #cah7 remarks on this circumstance471 or of an argillaceous tuff2 in this latter case1 the external crust was quite thin and hard4 ,some of these spherical balls were encircled in the line of their equators1 by a necklace-like row of smaller concretions4 ,again there were other concretions1 irregularly formed1 and composed of a hard1 compact1 ash- coloured stone1 with an almost porcelainous fracture1 adhesive to the tongue1 and without any calcareous matter4 ,these beds are1 also1 interlaced by many veins1 containing gypsum1 ferruginous matter1 calcareous spar1 and agate4 ,it was here seen with remarkable distinctness1 how intimately concretionary action and the production of fissures and veins are related together4 ,figure #bj is an accurate representation of a horizontal space of tuff1 about four feet long by two and a half in width3 the double lines represent the fissures partially filled with oxide of iron and agate3 the curvilinear lines show the course of the innumerable1 concentric1 concretionary zones of different shades of colour and of coarseness in the particles of tuff4 ,the symmetry and complexity of the arrangement gave the surface an elegant appearance4 ,it may be seen how obviously the fissures determine 7or have been determined by7 the shape1 sometimes of the whole concretion1 and sometimes only of its central parts4 ,the fissures also determine the curvatures of the long undulating zones of concretionary action4 ,from the varying composition of the veins and concretions1 the amount of chemical action which the mass has undergone is surprisingly great2 and it would likewise appear from the difference in size in the particles of the concretionary zones1 that the mass1 also1 has been subjected to internal mechanical movements4 ,in the peninsula of ,lacuy1 the strata over a width of four miles have been upheaved by three distinct1 and some other indistinct1 lines of elevation1 ranging within a point of north and south4 ,one line1 about two hundred feet in height1 is regularly anticlinal1 with the strata dipping away on both sides1 at an angle of #ae degrees1 from a central 8valley of elevation10 about three hundred yards in width4 ,a second narrow steep ridge1 only sixty feet high1 is uniclinal1 the strata throughout dipping westward2 those on both flanks being inclined at an angle of from ten to fifteen degrees2 whilst those on the ridge dip in the same direction at an angle of between thirty and forty degrees4 ,this ridge1 traced northwards1 dies away2 and the beds at its terminal point1 instead of dipping westward1 are inclined #ab degrees to the north4 ,this case interested me1 as being the first in which ,i found in ,south ,america1 formations perhaps of tertiary origin1 broken by lines of elevation4 ,,valdivia3 ,,island ,,of ,,mocha4 ,the formations of ,chiloe seem to extend with nearly the same character to ,valdivia1 and for some leagues northward of it3 the underlying rocks are micaceous schists1 and are covered up with sandstone and other sedimentary beds1 including1 as ,i was assured1 in many places layers of lignite4 ,i did not land on ,mocha 7latitude #ch degrees #bj minutes71 but ,mr4 ,stokes brought me specimens of the grey1 fine-grained1 slightly calcareous sandstone1 precisely like that of ,huafo1 containing lignite and numerous ,turritellae4 ,the island is flat topped1 #a1bdj feet in height1 and appears like an outlier of the sedimentary beds on the mainland4 ,the few shells collected consist of3-- #a4 ,turritella ,chilensis1 ,g4,b4 ,sowerby 7also at ,huafo74 #b4 ,fusus1 very imperfect1 somewhat resembling ,f4 subreflexus of ,navidad1 but probably different4 #c4 ,venus1 fragments of4 ,,concepcion4 ,sailing northward from ,valdivia1 the coast-cliffs are seen1 first to assume near the ,r4 ,tolten1 and thence for #aej miles northward1 to be continued with the same mineralogical characters1 immediately to be described at ,concepcion4 ,i heard in many places of beds of lignite1 some of it fine and glossy1 and likewise of silicified wood2 near the ,tolten the cliffs are low1 but they soon rise in height2 and the horizontal strata are prolonged1 with a nearly level surface1 until coming to a more lofty tract between points ,rumena and ,lavapie4 ,here the beds have been broken up by at least eight or nine parallel lines of elevation1 ranging ,e4 or ,e4,n4,e4 and ,w4 or ,w4,s4,w4 ,these lines can be followed with the eye many miles into the interior2 they are all uniclinal1 the strata in each dipping to a point between ,s4 and ,s4,s4,e4 with an inclination in the central lines of about forty degrees1 and in the outer ones of under twenty degrees4 ,this band of symmetrically troubled country is about eight miles in width4 ,the island of ,quiriquina1 in the ,bay of ,concepcion1 is formed of various soft and often ferruginous sandstones1 with bands of pebbles1 and with the lower strata sometimes passing into a conglomerate resting on the underlying metamorphic schists4 ,these beds include subordinate layers of greenish impure clay1 soft micaceous and calcareous sandstones1 and reddish friable earthy matter with white specks like decomposed crystals of feldspar2 they include1 also1 hard concretions1 fragments of shells1 lignite1 and silicified wood4 ,in the upper part they pass into white1 soft sediments and brecciolas1 very like those described at ,chiloe2 as indeed is the whole formation4 ,at ,lirguen and other places on the eastern side of the bay1 there are good sections of the lower sandstones1 which are generally ferruginous1 but which vary in character1 and even pass into an argillaceous nature2 they contain hard concretions1 fragments of lignite1 silicified wood1 and pebbles 7of the same rocks with the pebbles in the sandstones of ,quiriquina71 and they alternate with numerous1 often very thin layers of imperfect coal1 generally of little specific gravity4 ,the main bed here is three feet thick2 and only the coal of this one bed has a glossy fracture4 ,another irregular1 curvilinear bed of brown1 compact lignite1 is remarkable for being included in a mass of coarse gravel4 ,these imperfect coals1 when placed in a heap1 ignite spontaneously4 ,the cliffs on this side of the bay1 as well as on the island of ,quiriquina1 are capped with red friable earth1 which1 as stated in the ,second ,chapter1 is of recent formation4 ,the stratification in this neighbourhood is generally horizontal2 but near ,lirguen the beds dip ,n4,w4 at an angle of #bc degrees2 near ,concepcion they are also inclined3 at the northern end of ,quiriquina they have been tilted at an angle of #cj degrees1 and at the southern end at angles varying from #ae degrees to #dj degrees3 these dislocations must have taken place under the sea4 ,a collection of shells1 from the island of ,quiriquina1 has been described by ,m4 d',orbigny3 they are all extinct1 and from their generic character1 ,m4 d',orbigny inferred that they were of tertiary origin3 they consist of3-- #a4 ,scalaria ,chilensis1 d',orbigny1 8,voyage1 ,part ,pal40 #b4 ,natica ,araucana1 d',orbigny1 8,voyage1 ,part ,pal40 #c4 ,natica australis1 d',orbigny1 8,voyage1 ,part ,pal40 #d4 ,fusus difficilis1 d',orbigny1 8,voyage1 ,part ,pal40 #e4 ,pyrula longirostra1 d',orbigny1 8,voyage1 ,part ,pal40 #f4 ,pleurotoma ,araucana1 d',orbigny1 8,voyage1 ,part ,pal40 #g4 ,cardium auca1 d',orbigny1 8,voyage1 ,part ,pal40 #h4 ,cardium acuticostatum1 d',orbigny1 8,voyage1 ,part ,pal40 #i4 ,venus auca1 d',orbigny1 8,voyage1 ,part ,pal40 #aj4 ,mactra cecileana1 d',orbigny1 8,voyage1 ,part ,pal40 #aa4 ,mactra ,araucana1 d',orbigny1 8,voyage1 ,part ,pal40 #ab4 ,arca ,araucana1 d',orbigny1 8,voyage1 ,part ,pal40 #ac4 ,nucula ,largillierti1 d',orbigny1 8,voyage1 ,part ,pal40 #ad4 ,trigonia ,hanetiana1 d',orbigny1 8,voyage1 ,part ,pal40 ,during a second visit of the 8,beagle0 to ,concepcion1 ,mr4 ,kent collected for me some silicified wood and shells out of the concretions in the sandstone from ,tome1 situated a short distance north of ,lirguen4 ,they consist of3-- #a4 ,natica australis1 d',orbigny1 8,voyage1 ,part ,pal40 #b4 ,mactra ,araucana1 d',orbigny1 8,voyage1 ,part ,pal40 #c4 ,trigonia ,hanetiana1 d',orbigny1 8,voyage1 ,part ,pal40 #d4 ,pecten1 fragments of1 probably two species1 but too imperfect for description4 #e4 ,baculites vagina1 ,e4 ,forbes4 #f4 ,nautilus d',orbignyanus1 ,e4 ,forbes4 ,besides these shells1 ,captain ,belcher found here an ,ammonite1 nearly three feet in diameter1 and so heavy that he could not bring it away2 fragments are deposited at ,haslar ,hospital3 he also found the silicified vertebrae of some very large animal4 78,zoology of ,captain ,beechey's ,voyage0 page #afc47 ,from the identity in mineralogical nature of the rocks1 and from ,captain ,belcher's minute description of the coast between ,lirguen and ,tome1 the fossiliferous concretions at this latter place certainly belong to the same formation with the beds examined by myself at ,lirguen2 and these again are undoubtedly the same with the strata of ,quiriquina2 moreover2 the three first of the shells from ,tome1 though associated in the same concretions with the ,baculite1 are identical with the species from ,quiriquina4 ,hence all the sandstone and lignitiferous beds in this neighbourhood certainly belong to the same formation4 ,although the generic character of the ,quiriquina fossils naturally led ,m4 d',orbigny to conceive that they were of tertiary origin1 yet as we now find them associated with the ,baculites vagina and with an ,ammonite1 we must1 in the opinion of ,m4 d',orbigny1 and if we are guided by the analogy of the northern hemisphere1 rank them in the ,cretaceous system4 ,moreover1 the ,baculites vagina1 which is in a tolerable state of preservation1 appears to ,professor ,e4 ,forbes certainly to be identical with a species1 so named by him1 from ,pondicherry in ,india2 where it is associated with numerous decidedly cretaceous species1 which approach most nearly to ,lower ,greensand or ,neocomian forms3 this fact1 considering the vast distance between ,chile and ,india1 is truly surprising4 ,again1 the ,nautilus d',orbignyanus1 as far as its imperfect state allows of comparison1 resembles1 as ,i am informed by ,professor ,forbes1 both in its general form and in that of its chambers1 two species from the ,upper ,greensand4 ,it may be added that every one of the above-named genera from ,quiriquina1 which have an apparently tertiary character1 are found in the ,pondicherry strata4 ,there are1 however1 some difficulties on this view of the formations at ,concepcion being cretaceous1 which ,i shall afterwards allude to2 and ,i will here only state that the ,cardium auca is found also at ,coquimbo1 the beds at which place1 there can be no doubt1 are tertiary4 ,,navidad4 7,i was guided to this locality by the ,report on ,m4 ,gay's 8,geological ,researches0 in the 8,annales des ,scienc4 ,nat40 #ast series tome #bh47 ,the ,concepcion formation extends some distance northward1 but how far ,i know not2 for the next point at which ,i landed was at ,navidad1 #afj miles north of ,concepcion1 and #fj miles south of ,valparaiso4 ,the cliffs here are about eight hundred feet in height3 they consist1 wherever ,i could examine them1 of fine-grained1 yellowish1 earthy sandstones1 with ferruginous veins1 and with concretions of hard calcareous sandstone4 ,in one part1 there were many pebbles of the common metamorphic porphyries of the ,cordillera3 and near the base of the cliff1 ,i observed a single rounded boulder of greenstone1 nearly a yard in diameter4 ,i traced this sandstone formation beneath the superficial covering of gravel1 for some distance inland3 the strata are slightly inclined from the sea towards the ,cordillera1 which apparently has been caused by their having been accumulated against or round outlying masses of granite1 of which some points project near the coast4 ,the sandstone contains fragments of wood1 either in the state of lignite or partially silicified1 sharks' teeth1 and shells in great abundance1 both high up and low down the sea-cliffs4 ,pectunculus and ,oliva were most numerous in individuals1 and next to them ,turritella and ,fusus4 ,i collected in a short time1 though suffering from illness1 the following thirty-one species1 all of which are extinct1 and several of the genera do not now range 7as we shall hereafter show7 nearly so far south3-- #a4 ,gastridium cepa1 ,g4,b4 ,sowerby4 #b4 ,monoceros1 fragments of1 considered by ,m4 d',orbigny as a new species4 #c4 ,voluta alta1 ,g4,b4 ,sowerby 7considered by ,m4 d',orbigny as distinct from the ,v4 alta of ,santa ,cruz74 #d4 ,voluta triplicata1 ,g4,b4 ,sowerby4 #e4 ,oliva dimidiata1 ,g4,b4 ,sowerby4 #f4 ,pleurotoma discors1 ,g4,b4 ,sowerby4 #g4 ,pleurotoma turbinelloides1 ,g4,b4 ,sowerby4 #h4 ,fusus subreflexus1 ,g4,b4 ,sowerby4 #i4 ,fusus pyruliformis1 ,g4,b4 ,sowerby4 #aj4 ,fusus1 allied to ,f4 regularis 7considered by ,m4 d',orbigny as a distinct species74 #aa4 ,turritella suturalis1 ,g4,b4 ,sowerby4 #ab4 ,turritella ,patagonica1 ,g4,b4 ,sowerby 7fragments of74 #ac4 ,trochus laevis1 ,g4,b4 ,sowerby4 #ad4 ,trochus collaris1 ,g4,b4 ,sowerby 7considered by ,m4 d',orbigny as the young of the ,t4 laevis74 #ae4 ,cassis monilifer1 ,g4,b4 ,sowerby4 #af4 ,pyrula distans1 ,g4,b4 ,sowerby4 #ag4 ,triton verruculosus1 ,g4,b4 ,sowerby4 #ah4 ,sigaretus subglobosus1 ,g4,b4 ,sowerby4 #ai4 ,natica solida1 ,g4,b4 ,sowerby4 7,it is doubtful whether the ,natica solida of ,s4 ,cruz is the same species with this47 #bj4 ,terebra undulifera1 ,g4,b4 ,sowerby4 #ba4 ,terebra costellata1 ,g4,b4 ,sowerby4 #bb4 ,bulla 7fragments of74 #bc4 ,dentalium giganteum1 do4 #bd4 ,dentalium sulcosum1 do4 #be4 ,corbis 787 laevigata1 do4 #bf4 ,cardium multiradiatum1 do4 #bg4 ,venus meridionalis1 do4 #bh4 ,pectunculus dispar1 787 ,desh4 7considered by ,m4 d',orbigny as a distinct species74 #bi1 #cj4 ,cytheraea and ,mactra1 fragments of 7considered by ,m4 d',orbigny as new species74 #ca4 ,pecten1 fragments of4 ,,coquimbo4 7,,figure #ba4 ,,section ,,of ,,the ,,tertiary ,,formation ,,at ,,coquimbo4 ,from ,level of ,sea to ,surface of plain1 #beb feet above sea1 through levels ,f1 ,e1 ,d and ,c3 ,f4--,lower sandstone1 with concretions and silicified bones1 with fossil shells1 all1 or nearly all1 extinct4 ,e4--,upper ferruginous sandstone1 with numerous ,balani1 with fossil shells1 all1 or nearly all1 extinct4 ,c and ,d4--,calcareous beds with recent shells4 ,a4--,stratified sand in a ravine1 also with recent shells47 ,for more than two hundred miles northward of ,navidad1 the coast consists of plutonic and metamorphic rocks1 with the exception of some quite insignificant superficial beds of recent origin4 ,at ,tonguay1 twenty-five miles south of ,coquimbo1 tertiary beds recommence4 ,i have already minutely described in the ,second ,chapter1 the step-formed plains of ,coquimbo1 and the upper calcareous beds 7from twenty to thirty feet in thickness7 containing shells of recent species1 but in different proportions from those on the beach4 ,there remains to be described only the underlying ancient tertiary beds1 represented in ,figure #ba by the letters ,f and ,e3-- ,i obtained good sections of bed ,f only in ,herradura ,bay3 it consists of soft whitish sandstone1 with ferruginous veins1 some pebbles of granite1 and concretionary layers of hard calcareous sandstone4 ,these concretions are remarkable from the great number of large silicified bones1 apparently of cetaceous animals1 which they contain2 and likewise of a shark's teeth1 closely resembling those of the ,carcharias megalodon4 ,shells of the following species1 of which the gigantic ,oyster and ,perna are the most conspicuous1 are numerously embedded in the concretions3-- #a4 ,bulla ambigua1 d',orbigny 8,voyage0 ,pal4 #b4 ,monoceros ,blainvillii1 d',orbigny 8,voyage0 ,pal4 #c4 ,cardium auca1 d',orbigny 8,voyage0 ,pal4 #d4 ,panopaea ,coquimbensis1 d',orbigny 8,voyage0 ,pal4 #e4 ,perna ,gaudichaudi1 d',orbigny 8,voyage0 ,pal4 #f4 ,artemis ponderosa2 ,mr4 ,sowerby can find no distinguishing character between this fossil and the recent ,a4 ponderosa2 it is certainly an ,artemis1 as shown by the pallial impression4 #g4 ,ostrea ,patagonica 7872 ,mr4 ,sowerby can point out no distinguishing character between this species and that so eminently characteristic of the great ,patagonian formation2 but he will not pretend to affirm that they are identical4 #h4 ,fragments of a ,venus and ,natica4 ,the cliffs on one side of ,herradura ,bay are capped by a mass of stratified shingle1 containing a little calcareous matter1 and ,i did not doubt that it belonged to the same recent formation with the gravel on the surrounding plains1 also cemented by calcareous matter1 until to my surprise1 ,i found in the midst of it1 a single thin layer almost entirely composed of the above gigantic oyster4 ,at a little distance inland1 ,i obtained several sections of the bed ,e1 which1 though different in appearance from the lower bed ,f1 belongs to the same formation3 it consists of a highly ferruginous sandy mass1 almost composed1 like the lowest bed at ,port ,s4 ,julian1 of fragments of ,balanidae2 it includes some pebbles1 and layers of yellowish-brown mudstone4 ,the embedded shells consist of3-- #a4 ,monoceros ,blainvillii1 d',orbigny 8,voyage0 ,pal4 #b4 ,monoceros ambiguus1 ,g4,b4 ,sowerby4 #c4 ,anomia alternans1 ,g4,b4 ,sowerby4 #d4 ,pecten rudis1 ,g4,b4 ,sowerby4 #e4 ,perna ,gaudichaudi1 d',orbigny 8,voyage0 ,pal4 #f4 ,ostrea ,patagonica 7871 d',orbigny 8,voyage0 ,pal4 #g4 ,ostrea1 small species1 in imperfect state2 it appeared to me like a small kind now living in1 but very rare in the bay4 #h4 ,mytilus ,chiloensis2 ,mr4 ,sowerby can find no distinguishing character between this fossil1 as far as its not very perfect condition allows of comparison1 and the recent species4 #i4 ,balanus ,coquimbensis1 ,g4,b4 ,sowerby4 #aj4 ,balanus psittacus8 ,king4 ,this appears to ,mr4 ,sowerby and myself identical with a very large and common species now living on the coast4 ,the uppermost layers of this ferrugino-sandy mass are conformably covered by1 and impregnated to the depth of several inches with1 the calcareous matter of the bed ,d called losa3 hence ,i at one time imagined that there was a gradual passage between them2 but as all the species are recent in the bed ,d1 whilst the most characteristic shells of the uppermost layers of ,e are the extinct ,perna1 ,pecten1 and ,monoceros1 ,i agree with ,m4 d',orbigny1 that this view is erroneous1 and that there is only a mineralogical passage between them1 and no gradual transition in the nature of their organic remains4 ,besides the fourteen species enumerated from these two lower beds1 ,m4 d',orbigny has described ten other species given to him from this locality2 namely3-- #a4 ,fusus ,cleryanus1 d',orbigny 8,voyage0 ,pal4 #b4 ,fusus petitianus1 d',orbigny 8,voyage0 ,pal4 #c4 ,venus hanetiana1 d',orbigny 8,voyage0 ,pal4 #d4 ,venus incerta 787 d',orbigny 8,voyage0 ,pal4 #e4 ,venus ,cleryana1 d',orbigny 8,voyage0 ,pal4 #f4 ,venus petitiana1 d',orbigny 8,voyage0 ,pal4 #g4 ,venus ,chilensis1 d',orbigny 8,voyage0 ,pal4 #h4 ,solecurtus hanetianus1 d',orbigny 8,voyage0 ,pal4 #i4 ,mactra auca1 d',orbigny 8,voyage0 ,pal4 #aj4 ,oliva serena1 d',orbigny 8,voyage0 ,pal4 ,of these twenty-four shells1 all are extinct1 except1 according to ,mr4 ,sowerby1 the ,artemis ponderosa1 ,mytilus ,chiloensis1 and probably the great ,balanus4 ,,coquimbo ,,to ,,copiapo4 ,a few miles north of ,coquimbo1 ,i met with the ferruginous1 balaniferous mass ,e with many silicified bones2 ,i was informed that these silicified bones occur also at ,tonguay1 south of ,coquimbo3 their number is certainly remarkable1 and they seem to take the place of the silicified wood1 so common on the coast-formations of ,southern ,chile4 ,in the valley of ,chaneral1 ,i again saw this same formation1 capped with the recent calcareous beds4 ,i here left the coast1 and did not see any more of the tertiary formations1 until descending to the sea at ,copiapo3 here in one place ,i found variously coloured layers of sand and soft sandstone1 with seams of gypsum1 and in another place1 a comminuted shelly mass1 with layers of rotten-stone and seams of gypsum1 including many of the extinct gigantic oyster3 beds with these oysters are said to occur at ,english ,harbour1 a few miles north of ,copiapo4 ,,coast ,,of ,,peru4 ,with the exception of deposits containing recent shells and of quite insignificant dimensions1 no tertiary formations have been observed on this coast1 for a space of twenty-two degrees of latitude north of ,copiapo1 until coming to ,payta1 where there is said to be a considerable calcareous deposit3 a few fossils have been described by ,m4 d',orbigny from this place1 namely3-- #a4 ,rostellaria ,gaudichaudi1 d',orbigny 8,voyage0 ,pal4 #b4 ,pectunculus ,paytensis1 d',orbigny 8,voyage0 ,pal4 #c4 ,venus petitiana1 d',orbigny 8,voyage0 ,pal4 #d4 ,ostrea ,patagonica8 ,this great oyster 7of which specimens have been given me7 cannot be distinguished by ,mr4 ,sowerby from some of the varieties from ,patagonia2 though it would be hazardous to assert it is the same with that species1 or with that from ,coquimbo4 ,,concluding ,,remarks4 ,the formations described in this chapter1 have1 in the case of ,chiloe and probably in that of ,concepcion and ,navidad1 apparently been accumulated in troughs formed by submarine ridges extending parallel to the ancient shores of the continent2 in the case of the islands of ,mocha and ,huafo it is highly probable1 and in that of ,ypun and ,lemus almost certain1 that they were accumulated round isolated rocky centres or nuclei1 in the same manner as mud and sand are now collecting round the outlying islets and reefs in the ,west ,indian ,archipelago4 ,hence1 ,i may remark1 it does not follow that the outlying tertiary masses of ,mocha and ,huafo were ever continuously united at the same level with the formations on the mainland1 though they may have been of contemporaneous origin1 and been subsequently upraised to the same height4 ,in the more northern parts of ,chile1 the tertiary strata seem to have been separately accumulated in bays1 now forming the mouths of valleys4 ,the relation between these several deposits on the shores of the ,pacific1 is not nearly so clear as in the case of the tertiary formations on the ,atlantic4 ,judging from the form and height of the land 7evidence which ,i feel sure is here much more trustworthy than it can ever be in such broken continents as that of ,europe71 from the identity of mineralogical composition1 from the presence of fragments of lignite and of silicified wood1 and from the intercalated layers of imperfect coal1 ,i must believe that the coast-formations from ,central ,chiloe to ,concepcion1 a distance of #djj miles1 are of the same age3 from nearly similar reasons1 ,i suspect that the beds of ,mocha1 ,huafo1 and ,ypun1 belong also to the same period4 ,the commonest shell in ,mocha and ,huafo is the same species of ,turritella2 and ,i believe the same ,cytheraea is found on the islands of ,huafo1 ,chiloe1 and ,ypun2 but with these trifling exceptions1 the few organic remains found at these places are distinct4 ,the numerous shells from ,navidad1 with the exception of two1 namely1 the ,sigaretus and ,turritella found at ,ypun1 are likewise distinct from those found in any other part of this coast4 ,coquimbo has ,cardium auca in common with ,concepcion1 and ,fusus ,cleryanus with ,huafo2 ,i may add1 that ,coquimbo has ,venus petitiana1 and a gigantic oyster 7said by ,m4 d',orbigny also to be found a little south of ,concepcion7 in common with ,payta1 though this latter place is situated twenty-two degrees northward of latitude #bg degrees1 to which point the ,coquimbo formation extends4 ,from these facts1 and from the generic resemblance of the fossils from the different localities1 ,i cannot avoid the suspicion that they all belong to nearly the same epoch1 which epoch1 as we shall immediately see1 must be a very ancient tertiary one4 ,but as the ,baculite1 especially considering its apparent identity with the ,cretaceous ,pondicherry species1 and the presence of an ,ammonite1 and the resemblance of the ,nautilus to two upper greensand species1 together afford very strong evidence that the formation of ,concepcion is a ,secondary one2 ,i will1 in my remarks on the fossils from the other localities1 put on one side those from ,concepcion and from ,eastern ,chiloe1 which1 whatever their age may be1 appear to me to belong to one group4 ,i must1 however1 again call attention to the fact that the ,cardium auca is found both at ,concepcion and in the undoubtedly tertiary strata of ,coquimbo3 nor should the possibility be overlooked1 that as ,trigonia1 though known in the northern hemisphere only as a ,secondary genus1 has living representatives in the ,australian seas1 so a ,baculite1 ,ammonite1 and ,trigonia may have survived in this remote part of the southern ocean to a somewhat later period than to the north of the equator4 ,before passing in review the fossils from the other localities1 there are two points1 with respect to the formations between ,concepcion and ,chiloe1 which deserve some notice4 ,first1 that though the strata are generally horizontal1 they have been upheaved in ,chiloe in a set of parallel anticlinal and uniclinal lines ranging north and south1--in the district near ,p4 ,rumena by eight or nine far-extended1 most symmetrical1 uniclinal lines ranging nearly east and west1--and in the neighbourhood of ,concepcion by less regular single lines1 directed both ,n4,e4 and ,s4,w41 and ,n4,w4 and ,s4,e4 ,this fact is of some interest1 as showing that within a period which cannot be considered as very ancient in relation to the history of the continent1 the strata between the ,cordillera and the ,pacific have been broken up in the same variously directed manner as have the old plutonic and metamorphic rocks in this same district4 ,the second point is1 that the sandstone between ,concepcion and ,southern ,chiloe is everywhere lignitiferous1 and includes much silicified wood2 whereas the formations in ,northern ,chile do not include beds of lignite or coal1 and in place of the fragments of silicified wood there are silicified bones4 ,now1 at the present day1 from ,cape ,horn to near ,concepcion1 the land is entirely concealed by forests1 which thin out at ,concepcion1 and in ,central and ,northern ,chile entirely disappear4 ,this coincidence in the distribution of the fossil wood and the living forests may be quite accidental2 but ,i incline to take a different view of it2 for1 as the difference in climate1 on which the presence of forests depends1 is here obviously in chief part due to the form of the land1 and as the ,cordillera undoubtedly existed when the lignitiferous beds were accumulating1 ,i conceive it is not improbable that the climate1 during the lignitiferous period1 varied on different parts of the coast in a somewhat similar manner as it now does4 ,looking to an earlier epoch1 when the strata of the ,cordillera were depositing1 there were islands which even in the latitude of ,northern ,chile1 where now all is irreclaimably desert1 supported large coniferous forests4 ,,table #d4 ,column #a4 ,genera1 with living and tertiary species on the west coast of ,south ,america4 7,m4 d',orbigny states that the genus ,natica is not found on the coast of ,chile2 but ,mr4 ,cuming found it at ,valparaiso4 ,scalaria was found at ,valparaiso2 ,arca1 at ,iquique1 in latitude #bj1 by ,mr4 ,cuming2 ,arca1 also1 was found by ,captain ,king1 at ,juan ,fernandez1 in latitude #cc degrees #cj,s47 ,column #b4 ,latitudes1 in which found fossil on the coasts of ,chile and ,peru4 7,in degrees and minutes47 ,column #c4 ,southernmost latitude1 in which found living on the west coast of ,south ,america4 7,in degrees and minutes47 ,bulla 3 #cj to #dc #cj 3 #ab near ,lima4 ,cassis 3 #cd 3 #a #cg4 ,pyrula 3 #cd 7and #cf #cj at ,concepcion7 3 #e ,payta4 ,fusus 3 #cj and #dc #cj 3 #bc ,mexillones2 reappears at the ,st4 of ,magellan4 ,pleurotoma 3 #cd to #dc #cj 3 #b #ah ,st4 ,elena4 ,terebra 3 #cd 3 #e ,payta4 ,sigaretus 3 #cd to #dd #cj 3 #ab ,lima4 ,anomia 3 #cj 3 #g #dh4 ,perna 3 #cj 3 #a #bc ,xixappa4 ,cardium 3 #cj to #cd 7and #cf #cj at ,concepcion7 3 #e ,payta4 ,artemis 3 #cj 3 #e ,payta4 ,voluta 3 #cd to #dd #cj 3 ,mr4 ,cuming does not know of any species living on the west coast1 between the equator and latitude #dc south2 from this latitude a species is found as far south as ,tierra del ,fuego4 ,seventy-nine species of fossil shells1 in a tolerably recognisable condition1 from the coast of ,chile and ,peru1 are described in this volume1 and in the ,palaeontological part of ,m4 d',orbigny's 8,voyage03 if we put on one side the twenty species exclusively found at ,concepcion and ,chiloe1 fifty-nine species from ,navidad and the other specified localities remain4 ,of these fifty-nine species only an ,artemis1 a ,mytilus and ,balanus1 all from ,coquimbo1 are 7in the opinion of ,mr4 ,sowerby1 but not in that of ,m4 d',orbigny7 identical with living shells2 and it would certainly require a better series of specimens to render this conclusion certain4 ,only the ,turritella ,chilensis from ,huafo and ,mocha1 the ,t4 ,patagonica and ,venus meridionalis from ,navidad1 come very near to recent ,south ,american shells1 namely1 the two ,turritellas to ,t4 cingulata1 and the ,venus to ,v4 exalbida3 some few other species come rather less near2 and some few resemble forms in the older ,european tertiary deposits3 none of the species resemble secondary forms4 ,hence ,i conceive there can be no doubt that these formations are tertiary1--a point necessary to consider1 after the case of ,concepcion4 ,the fifty-nine species belong to thirty-two genera2 of these1 ,gastridium is extinct1 and three or four of the genera 7viz4 ,panopaea1 ,rostellaria1 ,corbis 7871 and ,i believe ,solecurtus7 are not now found on the west coast of ,south ,america4 ,fifteen of the genera have on this coast living representatives in about the same latitudes with the fossil species2 but twelve genera now range very differently to what they formerly did4 ,the idea of ,table #d1 in which the difference between the extension in latitude of the fossil and existing species is shown1 is taken from ,m4 d',orbigny's work2 but the range of the living shells is given on the authority of ,mr4 ,cuming1 whose long-continued researches on the conchology of ,south ,america are well-known4 ,when we consider that very few1 if any1 of the fifty-nine fossil shells are identical with1 or make any close approach to1 living species2 when we consider that some of the genera do not now exist on the west coast of ,south ,america1 and that no less than twelve genera out of the thirty-two formerly ranged very differently from the existing species of the same genera1 we must admit that these deposits are of considerable antiquity1 and that they probably verge on the commencement of the tertiary era4 ,may we not venture to believe1 that they are of nearly contemporaneous origin with the ,eocene formations of the northern hemisphere8 ,comparing the fossil remains from the coast of ,chile 7leaving out1 as before1 ,concepcion and ,chiloe7 with those from ,patagonia1 we may conclude1 from their generic resemblance1 and from the small number of the species which from either coast approach closely to living forms1 that the formations of both belong to nearly the same epoch2 and this is the opinion of ,m4 ,d',orbigny4 ,had not a single fossil shell been common to the two coasts1 it could not have been argued that the formations belonged to different ages2 for ,messrs4 ,cuming and ,hinds have found1 on the comparison of nearly two thousand living species from the opposite sides of ,south ,america1 only one in common1 namely1 the ,purpura lapillus from both sides of the ,isthmus of ,panama3 even the shells collected by myself amongst the ,chonos ,islands and on the coast of ,patagonia1 are dissimilar1 and we must descend to the apex of the continent1 to ,tierra del ,fuego1 to find these two great conchological provinces united into one4 ,hence it is remarkable that four or five of the fossil shells from ,navidad1 namely1 ,voluta alta1 ,turritella ,patagonica1 ,trochus collaris1 ,venus meridionalis1 perhaps ,natica solida1 and perhaps the large oyster from ,coquimbo1 are considered by ,mr4 ,sowerby as identical with species from ,santa ,cruz and ,p4 ,desire4 ,m4 d',orbigny1 however1 admits the perfect identity only of the ,trochus4 ,,on ,,the ,,temperature ,,of ,,the ,,tertiary ,,period4 ,as the number of the fossil species and genera from the western and eastern coasts is considerable1 it will be interesting to consider the probable nature of the climate under which they lived4 ,we will first take the case of ,navidad1 in latitude #cd degrees1 where thirty-one species were collected1 and which1 as we shall presently see1 must have inhabited shallow water1 and therefore will necessarily well exhibit the effects of temperature4 ,referring to ,table #d we find that the existing species of the genera ,cassis1 ,pyrula1 ,pleurotoma1 ,terebra1 and ,sigaretus1 which are generally 7though by no means invariably7 characteristic of warmer latitudes1 do not at the present day range nearly so far south on this line of coast as the fossil species formerly did4 ,including ,coquimbo1 we have ,perna in the same predicament4 ,the first impression from this fact is1 that the climate must formerly have been warmer than it now is2 but we must be very cautious in admitting this1 for ,cardium1 ,bulla1 and ,fusus 7and1 if we include ,coquimbo1 ,anomia and ,artemis7 likewise formerly ranged farther south than they now do2 and as these genera are far from being characteristic of hot climates1 their former greater southern range may well have been owing to causes quite distinct from climate3 ,voluta1 again1 though generally so tropical a genus1 is at present confined on the west coast to colder or more southern latitudes than it was during the tertiary period4 ,the ,trochus collaris1 moreover1 and1 as we have just seen according to ,mr4 ,sowerby1 two or three other species1 formerly ranged from ,navidad as far south as ,santa ,cruz in latitude #ej degrees4 ,if1 instead of comparing the fossils of ,navidad1 as we have hitherto done1 with the shells now living on the west coast of ,south ,america1 we compare them with those found in other parts of the world1 under nearly similar latitudes2 for instance1 in the southern parts of the ,mediterranean or of ,australia1 there is no evidence that the sea off ,navidad was formerly hotter than what might have been expected from its latitude1 even if it was somewhat warmer than it now is when cooled by the great southern polar current4 ,several of the most tropical genera have no representative fossils at ,navidad2 and there are only single species of ,cassis1 ,pyrula1 and ,sigaretus1 two of ,pleurotoma and two of ,terebra1 but none of these species are of conspicuous size4 ,in ,patagonia1 there is even still less evidence in the character of the fossils1 of the climate having been formerly warmer4 7,it may be worth while to mention that the shells living at the present day on this eastern side of ,south ,america1 in latitude #dj degrees1 have perhaps a more tropical character than those in corresponding latitudes on the shores of ,europe3 for at ,bahia ,blanca and ,s4 ,blas1 there are two fine species of ,voluta and four of ,oliva47 ,as from the various reasons already assigned1 there can be little doubt that the formations of ,patagonia and at least of ,navidad and ,coquimbo in ,chile1 are the equivalents of an ancient stage in the tertiary formations of the northern hemisphere1 the conclusion that the climate of the southern seas at this period was not hotter than what might have been expected from the latitude of each place1 appears to me highly important2 for we must believe1 in accordance with the views of ,mr4 ,lyell1 that the causes which gave to the older tertiary productions of the quite temperate zones of ,europe a tropical character1 ,,were ,,of ,a ,,local ,,character ,,and ,,did ,,not ,,affect ,,the ,,entire ,,globe4 ,on the other hand1 ,i have endeavoured to show1 in the 8,geological ,transactions10 that1 at a much later period1 ,europe and ,north and ,south ,america were nearly contemporaneously subjected to ice- action1 and consequently to a colder1 or at least more equable1 climate than that now characteristic of the same latitudes4 ,,on ,,the ,,absence ,,of ,,extensive ,,modern ,,conchiferous ,,deposits ,,in ,,south ,,america2 ,,and ,,on ,,the ,,contemporaneousness ,,of ,,the ,,older ,,tertiary ,,deposits ,,at ,,distant ,,points ,,being ,,due ,,to ,,contemporaneous ,,movements ,,of ,,subsidence4 ,knowing from the researches of ,professor ,e4 ,forbes1 that molluscous animals chiefly abound within a depth of #ajj fathoms and under1 and bearing in mind how many thousand miles of both coasts of ,south ,america have been upraised within the recent period by a slow1 long-continued1 intermittent movement1--seeing the diversity in nature of the shores and the number of shells now living on them1--seeing also that the sea off ,patagonia and off many parts of ,chile1 was during the tertiary period highly favourable to the accumulation of sediment1--the absence of extensive deposits including recent shells over these vast spaces of coast is highly remarkable4 ,the conchiferous calcareous beds at ,coquimbo1 and at a few isolated points northward1 offer the most marked exception to this statement2 for these beds are from twenty to thirty feet in thickness1 and they stretch for some miles along shore1 attaining1 however1 only a very trifling breadth4 ,at ,valdivia there is some sandstone with imperfect casts of shells1 which ,,possibly may belong to the recent period3 parts of the boulder formation and the shingle-beds on the lower plains of ,patagonia probably belong to this same period1 but neither are fossiliferous3 it also so happens that the great ,pampean formation does not include1 with the exception of the ,azara1 any mollusca4 ,there cannot be the smallest doubt that the upraised shells along the shores of the ,atlantic and ,pacific1 whether lying on the bare surface1 or embedded in mould or in sand-hillocks1 will in the course of ages be destroyed by alluvial action3 this probably will be the case even with the calcareous beds of ,coquimbo1 so liable to dissolution by rain-water4 ,if we take into consideration the probability of oscillations of level and the consequent action of the tidal-waves at different heights1 their destruction will appear almost certain4 ,looking to an epoch as far distant in futurity as we now are from the past ,miocene period1 there seems to me scarcely a chance1 under existing conditions1 of the numerous shells now living in those zones of depths most fertile in life1 and found exclusively on the western and south-eastern coasts of ,south ,america1 being preserved to this imaginary distant epoch4 ,a whole conchological series will in time be swept away1 with no memorials of their existence preserved in the earth's crust4 ,can any light be thrown on this remarkable absence of recent conchiferous deposits on these coasts1 on which1 at an ancient tertiary epoch1 strata abounding with organic remains were extensively accumulated8 ,i think there can1 namely1 by considering the conditions necessary for the preservation of a formation to a distant age4 ,looking to the enormous amount of denudation which on all sides of us has been effected1--as evidenced by the lofty cliffs cutting off on so many coasts horizontal and once far-extended strata of no great antiquity 7as in the case of ,patagonia71--as evidenced by the level surface of the ground on both sides of great faults and dislocations1--by inland lines of escarpments1 by outliers1 and numberless other facts1 and by that argument of high generality advanced by ,mr4 ,lyell1 namely1 that every ,,sedimentary formation1 whatever its thickness may be1 and over however many hundred square miles it may extend1 is the result and the measure of an equal amount of wear and tear of pre-existing formations2 considering these facts1 we must conclude that1 as an ordinary rule1 a formation to resist such vast destroying powers1 and to last to a distant epoch1 must be of wide extent1 and either in itself1 or together with superincumbent strata1 be of great thickness4 ,in this discussion1 we are considering only formations containing the remains of marine animals1 which1 as before mentioned1 live1 with some exceptions within 7most of them much within7 depths of #ajj fathoms4 ,how1 then1 can a thick and widely extended formation be accumulated1 which shall include such organic remains8 ,first1 let us take the case of the bed of the sea long remaining at a stationary level3 under these circumstances it is evident that ,,conchiferous strata can accumulate only to the same thickness with the depth at which the shells can live2 on gently inclined coasts alone can they accumulate to any considerable width2 and from the want of superincumbent pressure1 it is probable that the sedimentary matter will seldom be much consolidated3 such formations have no very good chance1 when in the course of time they are upraised1 of long resisting the powers of denudation4 ,the chance will be less if the submarine surface1 instead of having remained stationary1 shall have gone on slowly rising during the deposition of the strata1 for in this case their total thickness must be less1 and each part1 before being consolidated or thickly covered up by superincumbent matter1 will have had successively to pass through the ordeal of the beach2 and on most coasts1 the waves on the beach tend to wear down and disperse every object exposed to their action4 ,now1 both on the south-eastern and western shores of ,south ,america1 we have had clear proofs that the land has been slowly rising1 and in the long lines of lofty cliffs1 we have seen that the tendency of the sea is almost everywhere to eat into the land4 ,considering these facts1 it ceases1 ,i think1 to be surprising1 that extensive recent conchiferous deposits are entirely absent on the southern and western shores of ,america4 ,let us take the one remaining case1 of the bed of the sea slowly subsiding during a length of time1 whilst sediment has gone on being deposited4 ,it is evident that strata might thus accumulate to any thickness1 each stratum being deposited in shallow water1 and consequently abounding with those shells which cannot live at great depths3 the pressure1 also1 ,i may observe1 of each fresh bed would aid in consolidating all the lower ones4 ,even on a rather steep coast1 though such must ever be unfavourable to widely extended deposits1 the formations would always tend to increase in breadth from the water encroaching on the land4 ,hence we may admit that periods of slow subsidence will commonly be most favourable to the accumulation of ,,conchiferous deposits1 of sufficient thickness1 extension1 and hardness1 to resist the average powers of denudation4 ,we have seen that at an ancient tertiary epoch1 fossiliferous deposits were extensively deposited on the coasts of ,south ,america2 and it is a very interesting fact1 that there is evidence that these ancient tertiary beds were deposited during a period of subsidence4 ,thus1 at ,navidad1 the strata are about eight hundred feet in thickness1 and the fossil shells are abundant both at the level of the sea and some way up the cliffs2 having sent a list of these fossils to ,professor ,e4 ,forbes1 he thinks they must have lived in water between one and ten fathoms in depth3 hence the bottom of the sea on which these shells once lived must have subsided at least #gjj feet to allow of the superincumbent matter being deposited4 ,i must here remark1 that1 as all these and the following fossil shells are extinct species1 ,professor ,forbes necessarily judges of the depths at which they lived only from their generic character1 and from the analogical distribution of shells in the northern hemisphere2 but there is no just cause from this to doubt the general results4 ,at ,huafo the strata are about the same thickness1 namely1 #hjj feet1 and ,professor ,forbes thinks the fossils found there cannot have lived at a greater depth than fifty fathoms1 or #cjj feet4 ,these two points1 namely1 ,navidad and ,huafo1 are #egj miles apart1 but nearly halfway between them lies ,mocha1 an island #a1bjj feet in height1 apparently formed of tertiary strata up to its level summit1 and with many shells1 including the same ,turritella with that found at ,huafo1 embedded close to the level of the sea4 ,in ,patagonia1 shells are numerous at ,santa ,cruz1 at the foot of the #cej feet plain1 which has certainly been formed by the denudation of the #hdj feet plain1 and therefore was originally covered by strata that number of feet in thickness1 and these shells1 according to ,professor ,forbes1 probably lived at a depth of between seven and fifteen fathoms3 at ,port ,s4 ,julian1 sixty miles to the north1 shells are numerous at the foot of the ninety feet plain 7formed by the denudation of the #iej feet plain71 and likewise occasionally at the height of several hundred feet in the upper strata2 these shells must have lived in water somewhere between five and fifty fathoms in depth4 ,although in other parts of ,patagonia ,i have no direct evidence of shoal-water shells having been buried under a great thickness of superincumbent submarine strata1 yet it should be borne in mind that the lower fossiliferous strata with several of the same species of ,mollusca1 the upper tufaceous beds1 and the high summit-plain1 stretch for a considerable distance southward1 and for hundreds of miles northward2 seeing this uniformity of structure1 ,i conceive it may be fairly concluded that the subsidence by which the shells at ,santa ,cruz and ,s4 ,julian were carried down and covered up1 was not confined to these two points1 but was co-extensive with a considerable portion of the ,patagonian tertiary formation4 ,in a succeeding chapter it will be seen1 that we are led to a similar conclusion with respect to the secondary fossiliferous strata of the ,cordillera1 namely1 that they also were deposited during a long- continued and great period of subsidence4 ,from the foregoing reasoning1 and from the facts just given1 ,i think we must admit the probability of the following proposition3 namely1 that when the bed of the sea is either stationary or rising1 circumstances are far less favourable1 than when the level is sinking1 to the accumulation of ,,conchiferous deposits of sufficient thickness and extension to resist1 when upheaved1 the average vast amount of denudation4 ,this result appears to me1 in several respects1 very interesting3 every one is at first inclined to believe that at innumerable points1 wherever there is a supply of sediment1 fossiliferous strata are now forming1 which at some future distant epoch will be upheaved and preserved2 but on the views above given1 we must conclude that this is far from being the case2 on the contrary1 we require 7#ast71 a long-continued supply of sediment2 7#bnd71 an extensive shallow area2 and 7#crd71 that this area shall slowly subside to a great depth1 so as to admit the accumulation of a widely extended thick mass of superincumbent strata4 ,in how few parts of the world1 probably1 do these conditions at the present day concur6 ,we can thus1 also1 understand the general want of that close sequence in fossiliferous formations which we might theoretically have anticipated2 for1 without we suppose a subsiding movement to go on at the same spot during an enormous period1 from one geological era to another1 and during the whole of this period sediment to accumulate at the proper rate1 so that the depth should not become too great for the continued existence of molluscous animals1 it is scarcely possible that there should be a perfect sequence at the same spot in the fossil shells of the two geological formations4 7,professor ,h4,d4 ,rogers1 in his excellent address to the ,association of ,american ,geologists 78,silliman's ,journal0 volume #dg page #bgg7 makes the following remark3 8,i question if we are at all aware how ,,completely the whole history of all departed time lies indelibly recorded with the amplest minuteness of detail in the successive sediments of the globe1 how effectually1 in other words1 every period of time ,,has ,,written ,,its ,,own ,,history1 carefully preserving every created form and every trace of action40 ,i think the correctness of such remarks is more than doubtful1 even if we except 7as ,i suppose he would7 all those numerous organic forms which contain no hard parts47 ,so far from a very long-continued subsidence being probable1 many facts lead to the belief that the earth's surface oscillates up and down2 and we have seen that during the elevatory movements there is but a small chance of ,,durable fossiliferous deposits accumulating4 ,lastly1 these same considerations appear to throw some light on the fact that certain periods appear to have been favourable to the deposition1 or at least to the preservation1 of contemporaneous formations at very distant points4 ,we have seen that in ,south ,america an enormous area has been rising within the recent period2 and in other quarters of the globe immense spaces appear to have risen contemporaneously4 ,from my examination of the coral- reefs of the great oceans1 ,i have been led to conclude that the bed of the sea has gone on slowly sinking within the present era1 over truly vast areas3 this1 indeed1 is in itself probable1 from the simple fact of the rising areas having been so large4 ,in ,south ,america we have distinct evidence that at nearly the same tertiary period1 the bed of the sea off parts of the coast of ,chile and off ,patagonia was sinking1 though these regions are very remote from each other4 ,if1 then1 it holds good1 as a general rule1 that in the same quarter of the globe the earth's crust tends to sink and rise contemporaneously over vast spaces1 we can at once see1 that we have at distant points1 at the same period1 those very conditions which appear to be requisite for the accumulation of fossiliferous masses of sufficient extension1 thickness1 and hardness1 to resist denudation1 and consequently to last unto an epoch distant in futurity4 7,professor ,forbes has some admirable remarks on this subject1 in his 8,report on the ,shells of the ,aegean ,sea40 ,in a letter to ,mr4 ,maclaren 78,edinburgh ,new ,philosophical ,journal0 ,january #ahdc71 ,i partially entered into this discussion1 and endeavoured to show that it was highly improbable1 that upraised atolls or barrier-reefs1 though of great thickness1 should1 owing to their small extension or breadth1 be preserved to a distant future period47 ,,chapter ,,vi4 ,,plutonic ,,and ,,metamorphic ,,rocks3--,,cleavage ,,and ,,foliation4 ,brazil1 ,bahia1 gneiss with disjointed metamorphosed dikes4--,strike of foliation4--,rio de ,janeiro1 gneiss-granite1 embedded fragment in1 decomposition of4--,la ,plata1 metamorphic and old volcanic rocks of4--,s4 ,ventana4--,claystone porphyry formation of ,patagonia2 singular metamorphic rocks2 pseudo-dikes4--,falkland ,islands1 ,palaeozoic fossils of4--,tierra del ,fuego1 clay-slate formation1 cretaceous fossils of2 cleavage and foliation2 form of land4--,chonos ,archipelago1 mica-schists1 foliation disturbed by granitic axis2 dikes4--,chiloe4--,concepcion1 dikes1 successive formation of4--,central and ,northern ,chile4--,concluding remarks on cleavage and foliation4--,their close analogy and similar origin4--,stratification of metamorphic schists4--,foliation of intrusive rocks4--,relation of cleavage and foliation to the lines of tension during metamorphosis4 ,the metamorphic and plutonic formations of the several districts visited by the 8,beagle0 will be here chiefly treated of1 but only such cases as appear to me new1 or of some special interest1 will be described in detail2 at the end of the chapter ,i will sum up all the facts on cleavage and foliation1-- to which ,i particularly attended4 ,,bahia1 ,,brazil3 latitude #ac degrees south4 ,the prevailing rock is gneiss1 often passing1 by the disappearance of the quartz and mica1 and by the feldspar losing its red colour1 into a brilliantly grey primitive greenstone4 ,not unfrequently quartz and hornblende are arranged in layers in almost amorphous feldspar4 ,there is some fine-grained syenitic granite1 orbicularly marked by ferruginous lines1 and weathering into vertical1 cylindrical holes1 almost touching each other4 ,in the gneiss1 concretions of granular feldspar and others of garnets with mica occur4 ,the gneiss is traversed by numerous dikes composed of black1 finely crystallised1 hornblendic rock1 containing a little glassy feldspar and sometimes mica1 and varying in thickness from mere threads to ten feet3 these threads1 which are often curvilinear1 could sometimes be traced running into the larger dikes4 ,one of these dikes was remarkable from having been in two or three places laterally disjointed1 with unbroken gneiss interposed between the broken ends1 and in one part with a portion of the gneiss driven1 apparently whilst in a softened state1 into its side or wall4 ,in several neighbouring places1 the gneiss included angular1 well- defined1 sometimes bent1 masses of hornblende rock1 quite like1 except in being more perfectly crystallised1 that forming the dikes1 and1 at least in one instance1 containing 7as determined by ,professor ,miller7 augite as well as hornblende4 ,in one or two cases these angular masses1 though now quite separate from each other by the solid gneiss1 had1 from their exact correspondence in size and shape1 evidently once been united2 hence ,i cannot doubt that most or all of the fragments have been derived from the breaking up of the dikes1 of which we see the first stage in the above- mentioned laterally disjointed one4 ,the gneiss close to the fragments generally contained many large crystals of hornblende1 which are entirely absent or rare in other parts3 its folia or laminae were gently bent round the fragments1 in the same manner as they sometimes are round concretions4 ,hence the gneiss has certainly been softened1 its composition modified1 and its folia arranged1 subsequently to the breaking up of the dikes1 these latter also having been at the same time bent and softened4 7,professor ,hitchcock 8,geology of ,massachusetts0 volume #b page #fgc1 gives a closely similar case of a greenstone dike in syenite47 ,i must here take the opportunity of premising1 that by the term ,,cleavage ,i imply those planes of division which render a rock1 appearing to the eye quite or nearly homogeneous1 fissile4 ,by the term ,,foliation1 ,i refer to the layers or plates of different mineralogical nature of which most metamorphic schists are composed2 there are1 also1 often included in such masses1 alternating1 homogeneous1 fissile layers or folia1 and in this case the rock is both foliated and has a cleavage4 ,by ,,stratification1 as applied to these formations1 ,i mean those alternate1 parallel1 large masses of different composition1 which are themselves frequently either foliated or fissile1--such as the alternating so-called strata of mica-slate1 gneiss1 glossy clay-slate1 and marble4 ,the folia of the gneiss within a few miles round ,bahia generally strike irregularly1 and are often curvilinear1 dipping in all directions at various angles3 but where best defined1 they extended most frequently in a ,n4,e4 by ,n4 7or ,east #ej degrees ,n47 and ,s4,w4 by ,s4 line1 corresponding nearly with the coast-line northwards of the bay4 ,i may add that ,mr4 ,gardner found in several parts of the province of ,ceara1 which lies between four and five hundred miles north of ,bahia1 gneiss with the folia extending ,e4 #de degrees ,n42 and in ,guyana according to ,sir ,r4 ,schomburgk1 the same rock strikes ,e4 #eg degrees ,n4 ,again1 ,humboldt describes the gneiss-granite over an immense area in ,venezuela and even in ,colombia1 as striking ,e4 #ej degrees ,n41 and dipping to the ,n4,w4 at an angle of fifty degrees4 7,gardner 8,geological ,section of the ,british ,association0 #ahdj4 ,for ,sir ,r4 ,schomburgk's observations see 8,geographical ,journal0 #ahdb page #aij4 ,see also ,humboldt's discussion on ,loxodrism in the 8,personal ,narrative407 ,hence all the observations hitherto made tend to show that the gneissic rocks over the whole of this part of the continent have their folia extending generally within almost a point of the compass of the same direction4 7,i landed at only one place north of ,bahia1 namely1 at ,pernambuco4 ,i found there only soft1 horizontally stratified matter1 formed from disintegrated granitic rocks1 and some yellowish impure limestone1 probably of a tertiary epoch4 ,i have described a most singular natural bar of hard sandstone1 which protects the harbour1 in the #aith volume #ahda page #beh of the 8,london and ,edinburgh ,philosophical ,magazine40 ,,abrolhos ,,islets1 ,latitude #ah degrees ,s4 off the coast of ,brazil4 ,although not strictly in place1 ,i do not know where ,i can more conveniently describe this little group of small islands4 ,the lowest bed is a sandstone with ferruginous veins2 it weathers into an extraordinary honeycombed mass2 above it there is a dark-coloured argillaceous shale2 above this a coarser sandstone--making a total thickness of about sixty feet2 and lastly1 above these sedimentary beds1 there is a fine conformable mass of greenstone1 in some parts having a columnar structure4 ,all the strata1 as well as the surface of the land1 dip at an angle of about #ab degrees to ,n4 by ,w4 ,some of the islets are composed entirely of the sedimentary1 others of the trappean rocks1 generally1 however1 with the sandstone1 cropping out on the southern shores47 ,,rio ,,de ,,janeiro4 ,this whole district is almost exclusively formed of gneiss1 abounding with garnets1 and porphyritic with large crystals1 even three and four inches in length1 of orthoclase feldspar3 in these crystals mica and garnets are often enclosed4 ,at the western base of the ,corcovado1 there is some ferruginous carious quartz-rock2 and in the ,tijeuka range1 much fine- grained granite4 ,i observed boulders of greenstone in several places2 and on the islet of ,villegagnon1 and likewise on the coast some miles northward1 two large trappean dikes4 ,the porphyritic gneiss1 or gneiss- granite as it has been called by ,humboldt1 is only so far foliated that the constituent minerals are arranged with a certain degree of regularity1 and may be said to have a 8,,grain10 but they are not separated into distinct folia or laminae4 ,there are1 however1 several other varieties of gneiss regularly foliated1 and alternating with each other in so-called strata4 ,the stratification and foliation of the ordinary gneisses1 and the foliation or 8grain0 of the gneiss-granite1 are parallel to each other1 and generally strike within a point of ,n4,e4 and ,s4,w4 dipping at a high angle 7between #ej and #fj degrees7 generally to ,s4,e43 so that here again we meet with the strike so prevalent over the more northern parts of this continent4 ,the mountains of gneiss-granite are to a remarkable degree abruptly conical1 which seems caused by the rock tending to exfoliate in thick1 conically concentric layers3 these peaks resemble in shape those of phonolite and other injected rocks on volcanic islands2 nor is the grain or foliation 7as we shall afterwards see7 any difficulty on the idea of the gneiss-granite having been an intrusive rather than a metamorphic formation4 ,the lines of mountains1 but not always each separate hill1 range nearly in the same direction with the foliation and so-called stratification1 but rather more easterly4 7,,figure #bb4 ,,fragment ,,of ,,gneiss ,,embedded ,,in ,,another ,,variety ,,of ,,the ,,same ,,rock47 ,on a bare gently inclined surface of the porphyritic gneiss in ,botofogo ,bay1 ,i observed the appearance represented in ,figure #bb4 ,a fragment seven yards long and two in width1 with angular and distinctly defined edges1 composed of a peculiar variety of gneiss with dark layers of mica and garnets1 is surrounded on all sides by the ordinary gneiss- granite2 both having been dislocated by a granitic vein4 ,the folia in the fragment and in the surrounding rock strike in the same ,n4,n4,e4 and ,s4,s4,w4 line2 but in the fragment they are vertical1 whereas in the gneiss-granite they dip at a small angle1 as shown by the arrows1 to ,s4,s4,e4 ,this fragment1 considering its great size1 its solitary position1 and its foliated structure parallel to that of the surrounding rock1 is1 as far as ,i know1 a unique case3 and ,i will not attempt any explanation of its origin4 ,the numerous travellers in this country1 have all been greatly surprised at the depth to which the gneiss and other granitic rocks1 as well as the talcose slates of the interior1 have been decomposed4 7,spix and ,martius have collected in an ,appendix to their 8,travels10 the largest body of facts on this subject4 ,see also some remarks by ,m4 ,lund in his communications to the ,academy at ,copenhagen2 and others by ,m4 ,gaudichaud in ,freycinet 8,voyage407 ,near ,rio1 every mineral except the quartz has been completely softened1 in some places to a depth little less than one hundred feet4 7,dr4 ,benza describes granitic rock1 8,madras ,journal of ,literature0 etc4 ,october #ahc8 page #bdf71 in the ,neelgherries1 decomposed to a depth of forty feet47 ,the minerals retain their positions in folia ranging in the usual direction2 and fractured quartz veins may be traced from the solid rock1 running for some distance into the softened1 mottled1 highly coloured1 argillaceous mass4 ,it is said that these decomposed rocks abound with gems of various kinds1 often in a fractured state1 owing1 as some have supposed1 to the collapse of geodes1 and that they contain gold and diamonds4 ,at ,rio1 it appeared to me that the gneiss had been softened before the excavation 7no doubt by the sea7 of the existing1 broad1 flat-bottomed valleys2 for the depth of decomposition did not appear at all conformable with the present undulations of the surface4 ,the porphyritic gneiss1 where now exposed to the air1 seems to withstand decomposition remarkably well2 and ,i could see no signs of any tendency to the production of argillaceous masses like those here described4 ,i was also struck with the fact1 that where a bare surface of this rock sloped into one of the quiet bays1 there were no marks of erosion at the level of the water1 and the parts both beneath and above it preserved a uniform curve4 ,at ,bahia1 the gneiss rocks are similarly decomposed1 with the upper parts insensibly losing their foliation1 and passing1 without any distinct line of separation1 into a bright red argillaceous earth1 including partially rounded fragments of quartz and granite4 ,from this circumstance1 and from the rocks appearing to have suffered decomposition before the excavation of the valleys1 ,i suspect that here1 as at ,rio1 the decomposition took place under the sea4 ,the subject appeared to me a curious one1 and would probably well repay careful examination by an able mineralogist4 ,,the ,,northern ,,provinces ,,of ,,la ,,plata4 ,according to some observations communicated to me by ,mr4 ,fox1 the coast from ,rio de ,janeiro to the mouth of the ,plata seems everywhere to be granitic1 with a few trappean dikes4 ,at ,port ,alegre1 near the boundary of ,brazil1 there are porphyries and diorites4 7,m4 ,isabelle 8,voyage a ,buenos ,ayres0 page #dgi47 ,at the mouth of the ,plata1 ,i examined the country for twenty-five miles west1 and for about seventy miles north of ,maldonado3 near this town1 there is some common gneiss1 and much1 in all parts of the country1 of a coarse-grained mixture of quartz and reddish feldspar1 often1 however1 assuming a little dark-green imperfect hornblende1 and then immediately becoming foliated4 ,the abrupt hillocks thus composed1 as well as the highly inclined folia of the common varieties of gneiss1 strike ,n4,n4,e4 or a little more easterly1 and ,s4,s4,w4 ,clay-slate is occasionally met with1 and near the ,l4 del ,potrero1 there is white marble1 rendered fissile from the presence of hornblende1 mica1 and asbestus2 the cleavage of these rocks and their stratification1 that is the alternating masses thus composed1 strike ,n4,n4,e4 and ,s4,s4,w4 like the foliated gneisses1 and have an almost vertical dip4 ,the ,sierra ,larga1 a low range five miles west of ,maldonado1 consists of quartzite1 often ferruginous1 having an arenaceous feel1 and divided into excessively thin1 almost vertical laminae or folia by microscopically minute scales1 apparently of mica1 and striking in the usual ,n4,n4,e4 and ,s4,s4,w4 direction4 ,the range itself is formed of one principal line with some subordinate ones2 and it extends with remarkable uniformity far northward 7it is said even to the confines of ,brazil71 in the same line with the vertically ribboned quartz rock of which it is composed4 ,the ,s4 de ,las ,animas is the highest range in the country2 ,i estimated it at #a1jjj feet2 it runs north and south1 and is formed of feldspathic porphyry2 near its base there is a ,n4,n4,w4 and ,s4,s4,e4 ridge of a conglomerate in a highly porphyritic basis4 ,northward of ,maldonado1 and south of ,las ,minas1 there is an ,e4 and ,w4 hilly band of country1 some miles in width1 formed of siliceous clay-slate1 with some quartz1 rock1 and limestone1 having a tortuous irregular cleavage1 generally ranging east and west4 ,e4 and ,s4,e4 of ,las ,minas there is a confused district of imperfect gneiss and laminated quartz1 with the hills ranging in various directions1 but with each separate hill generally running in the same line with the folia of the rocks of which it is composed3 this confusion appears to have been caused by the intersection of the ,e4 and ,w4 and ,n4,n4,e4 and ,s4,s4,w4 strikes4 ,northward of ,las ,minas1 the more regular northerly ranges predominate3 from this place to near ,polanco1 we meet with the coarse-grained mixture of quartz and feldspar1 often with the imperfect hornblende1 and then becoming foliated in a ,n4 and ,s4 line--with imperfect clay-slate1 including laminae of red crystallised feldspar--with white or black marble1 sometimes containing asbestus and crystals of gypsum--with quartz-rock--with syenite--and lastly1 with much granite4 ,the marble and granite alternate repeatedly in apparently vertical masses3 some miles northward of the ,polanco1 a wide district is said to be entirely composed of marble4 ,it is remarkable1 how rare mica is in the whole range of country north and westward of ,maldonado4 ,throughout this district1 the cleavage of the clay-slate and marble--the foliation of the gneiss and the quartz--the stratification or alternating masses of these several rocks--and the range of the hills1 all coincide in direction2 and although the country is only hilly1 the planes of division are almost everywhere very highly inclined or vertical4 ,some ancient submarine volcanic rocks are worth mentioning1 from their rarity on this eastern side of the continent4 ,in the valley of the ,tapas 7fifty or sixty miles ,n4 of ,maldonado7 there is a tract three or four miles in length1 composed of various trappean rocks with glassy feldspar--of apparently metamorphosed grit-stones--of purplish amygdaloids with large kernels of carbonate of lime 7,near the ,pan de ,azucar there is some greenish porphyry1 in one place amygdaloidal with agate47--and much of a harshish rock with glassy feldspar intermediate in character between claystone porphyry and trachyte4 ,this latter rock was in one spot remarkable from being full of drusy cavities1 lined with quartz crystals1 and arranged in planes1 dipping at an angle of #ej degrees to the east1 and striking parallel to the foliation of an adjoining hill composed of the common mixture of quartz1 feldspar1 and imperfect hornblende3 this fact perhaps indicates that these volcanic rocks have been metamorphosed1 and their constituent parts rearranged1 at the same time and according to the same laws1 with the granitic and metamorphic formations of this whole region4 ,in the valley of the ,marmaraya1 a few miles south of the ,tapas1 a band of trappean and amygdaloidal rock is interposed between a hill of granite and an extensive surrounding formation of red conglomerate1 which 7like that at the foot of the ,s4 ,animas7 has its basis porphyritic with crystals of feldspar1 and which hence has certainly suffered metamorphosis4 ,,monte ,,video4 ,the rocks here consist of several varieties of gneiss1 with the feldspar often yellowish1 granular and imperfectly crystallised1 alternating with1 and passing insensibly into1 beds1 from a few yards to nearly a mile in thickness1 of fine or coarse grained1 dark-green hornblendic slate2 this again often passing into chloritic schist4 ,these passages seem chiefly due to changes in the mica1 and its replacement by other minerals4 ,at ,rat ,island ,i examined a mass of chloritic schist1 only a few yards square1 irregularly surrounded on all sides by the gneiss1 and intricately penetrated by many curvilinear veins of quartz1 which gradually ,,blend into the gneiss3 the cleavage of the chloritic schist and the foliation of the gneiss were exactly parallel4 ,eastward of the city there is much fine- grained1 dark-coloured gneiss1 almost assuming the character of hornblende- slate1 which alternates in thin laminae with laminae of quartz1 the whole mass being transversely intersected by numerous large veins of quartz3 ,i particularly observed that these veins were absolutely continuous with the alternating laminae of quartz4 ,in this case and at ,rat ,island1 the passage of the gneiss into imperfect hornblendic or into chloritic slate1 seemed to be connected with the segregation of the veins of quartz4 7,mr4 ,greenough page #gh 8,critical ,examination0 etc41 observes that quartz in mica-slate sometimes appears in beds and sometimes in veins4 ,von ,buch also in his 8,travels in ,norway0 page #bcf1 remarks on alternating laminae of quartz and hornblende-slate replacing mica-schist47 ,the ,mount1 a hill believed to be #dej feet in height1 from which the place takes its name1 is much the highest land in this neighbourhood3 it consists of hornblendic slate1 which 7except on the eastern and disturbed base7 has an east and west nearly vertical cleavage2 the longer axis of the hill also ranges in this same line4 ,near the summit the hornblende-slate gradually becomes more and more coarsely crystallised1 and less plainly laminated1 until it passes into a heavy1 sonorous greenstone1 with a slaty conchoidal fracture2 the laminae on the north and south sides near the summit dip inwards1 as if this upper part had expanded or bulged outwards4 ,this greenstone must1 ,i conceive1 be considered as metamorphosed hornblende- slate4 ,the ,cerrito1 the next highest1 but much less elevated point1 is almost similarly composed4 ,in the more western parts of the province1 besides gneiss1 there is quartz-rock1 syenite1 and granite2 and at ,colla1 ,i heard of marble4 ,near ,m4 ,video1 the space which ,i more accurately examined was about fifteen miles in an east and west line1 and here ,i found the foliation of the gneiss and the cleavage of the slates generally well developed1 and extending parallel to the alternating strata composed of the gneiss1 hornblendic and chloritic schists4 ,these planes of division all range within one point of east and west1 frequently east by south and west by north2 their dip is generally almost vertical1 and scarcely anywhere under #de degrees3 this fact1 considering how slightly undulatory the surface of the country is1 deserves attention4 ,westward of ,m4 ,video1 towards the ,uruguay1 wherever the gneiss is exposed1 the highly inclined folia are seen striking in the same direction2 ,i must except one spot where the strike was ,n4,w4 by ,w4 ,the little ,sierra de ,s4 ,juan1 formed of gneiss and laminated quartz1 must also be excepted1 for it ranges between ,n4 to ,n4,e4 and ,s4 to ,s4,w4 and seems to belong to the same system with the hills in the ,maldonado district4 ,finally1 we have seen that1 for many miles northward of ,maldonado and for twenty-five miles westward of it1 as far as the ,s4 de las ,animas1 the foliation1 cleavage1 so-called stratification and lines of hills1 all range ,n4,n4,e4 and ,s4,s4,w41 which is nearly coincident with the adjoining coast of the ,atlantic4 ,westward of the ,s4 de las ,animas1 as far as even the ,uruguay1 the foliation1 cleavage1 and stratification 7but not lines of hills1 for there are no defined ones7 all range about ,e4 by ,s4 and ,w4 by ,n41 which is nearly coincident with the direction of the northern shore of the ,plata2 in the confused country near ,las ,minas1 where these two great systems appear to intersect each other1 the cleavage1 foliation1 and stratification run in various directions1 but generally coincide with the line of each separate hill4 ,,southern ,,la ,,plata4 ,the first ridge1 south of the ,plata1 which projects through the ,pampean formation1 is the ,sierra ,tapalguen and ,vulcan1 situated #bjj miles southward of the district just described4 ,this ridge is only a few hundred feet in height1 and runs from ,c4 ,corrientes in a ,w4,n4,w4 line for at least #aej miles into the interior3 at ,tapalguen1 it is composed of unstratified granular quartz1 remarkable from forming tabular masses and small plains1 surrounded by precipitous cliffs3 other parts of the range are said to consist of granite3 and marble is found at the ,s4 ,tinta4 ,it appears from ,m4 ,parchappe's observations1 that at ,tandil there is a range of quartzose gneiss1 very like the rocks of the ,s4 ,larga near ,maldonado1 running in the same ,n4,n4,e4 and ,s4,s4,w4 direction2 so that the framework of the country here is very similar to that on the northern shore of the ,plata4 7,m4 d',orbigny's 8,voyage0 ,part4 ,geolog4 page #df4 ,i have given a short account of the peculiar forms of the quartz hills of ,tapalguen1 so unusual in a metamorphic formation1 in my 8,journal of ,researches0 #bnd edition page #aaf47 ,the ,sierra ,guitru-gueyu is situated sixty miles south of the ,s4 ,tapalguen3 it consists of numerous parallel1 sometimes blended together ridges1 about twenty-three miles in width1 and five hundred feet in height above the plain1 and extending in a ,n4,w4 and ,s4,e4 direction4 ,skirting round the extreme ,s4,e4 termination1 ,i ascended only a few points1 which were composed of a fine-grained gneiss1 almost composed of feldspar with a little mica1 and passing in the upper parts of the hills into a rather compact purplish clay-slate4 ,the cleavage was nearly vertical1 striking in a ,n4,w4 by ,w4 and ,s4,e4 by ,e4 line1 nearly1 though not quite1 coincident with the direction of the parallel ridges4 ,the ,sierra ,ventana lies close south of that of ,guitru-gueyu2 it is remarkable from attaining a height1 very unusual on this side of the continent1 of #c1cdj feet4 ,it consists up to its summit1 of quartz1 generally pure and white1 but sometimes reddish1 and divided into thick laminae or strata3 in one part there is a little glossy clay-slate with a tortuous cleavage4 ,the thick layers of quartz strike in a ,w4 #cj degrees ,n4 line1 dipping southerly at an angle of #de degrees and upwards4 ,the principal line of mountains1 with some quite subordinate parallel ridges1 range about ,w4 #de degrees ,n43 but at their ,s4,e4 termination1 only ,w4 #be degrees ,n4 ,this ,sierra is said to extend between twenty and thirty leagues into the interior4 ,,patagonia4 ,with the exception perhaps of the hill of ,s4 ,antonio 7#fjj feet high7 in the ,gulf of ,s4 ,matias1 which has never been visited by a geologist1 crystalline rocks are not met with on the coast of ,patagonia for a space of #chj miles south of the ,s4 ,ventana4 ,at this point 7latitude #dc degrees #ej minutes71 at ,points ,union and ,tombo1 plutonic rocks are said to appear1 and are found1 at rather wide intervals1 beneath the ,patagonian tertiary formation for a space of about three hundred miles southward1 to near ,bird ,island1 in latitude #dh degrees #ef minutes4 ,judging from specimens kindly collected for me by ,mr4 ,stokes1 the prevailing rock at ,ports ,st4 ,elena1 ,camerones1 ,malaspina1 and as far south as the ,paps of ,pineda1 is a purplish-pink or brownish claystone porphyry1 sometimes laminated1 sometimes slightly vesicular1 with crystals of opaque feldspar and with a few grains of quartz2 hence these porphyries resemble those immediately to be described at ,port ,desire1 and likewise a series which ,i have seen from ,p4 ,alegre on the southern confines of ,brazil4 ,this porphyritic formation further resembles in a singularly close manner the lowest stratified formation of the ,cordillera of ,chile1 which1 as we shall hereafter see1 has a vast range1 and attains a great thickness4 ,at the bottom of the ,gulf of ,st4 ,george1 only tertiary deposits appear to be present4 ,at ,cape ,blanco1 there is quartz rock1 very like that of the ,falkland ,islands1 and some hard1 blue siliceous clay-slate4 ,at ,port ,desire there is an extensive formation of the claystone porphyry1 stretching at least twenty-five miles into the interior3 it has been denuded and deeply worn into gullies before being covered up by the tertiary deposits1 through which it here and there projects in hills2 those north of the bay being #ddj feet in height4 ,the strata have in several places been tilted at small angles1 generally either to ,n4,n4,w4 or ,s4,s4,e4 ,by gradual passages and alternations1 the porphyries change incessantly in nature4 ,i will describe only some of the principal mineralogical changes1 which are highly instructive1 and which ,i carefully examined4 ,the prevailing rock has a compact purplish base1 with crystals of earthy or opaque feldspar1 and often with grains of quartz4 ,there are other varieties1 with an almost truly trachytic base1 full of little angular vesicles and crystals of glassy feldspar2 and there are beds of black perfect pitchstone1 as well as of a concretionary imperfect variety4 ,on a casual inspection1 the whole series would be thought to be of the same plutonic or volcanic nature with the trachytic varieties and pitchstone2 but this is far from being the case1 as much of the porphyry is certainly of metamorphic origin4 ,besides the true porphyries1 there are many beds of earthy1 quite white or yellowish1 friable1 easily fusible matter1 resembling chalk1 which under the microscope is seen to consist of minute broken crystals1 and which1 as remarked in a former chapter1 singularly resembles the upper tufaceous beds of the ,patagonian tertiary formation4 ,this earthy substance often becomes coarser1 and contains minute rounded fragments of porphyries and rounded grains of quartz1 and in one case so many of the latter as to resemble a common sandstone4 ,these beds are sometimes marked with true lines of aqueous deposition1 separating particles of different degrees of coarseness2 in other cases there are parallel ferruginous lines not of true deposition1 as shown by the arrangement of the particles1 though singularly resembling them4 ,the more indurated varieties often include many small and some larger angular cavities1 which appear due to the removal of earthy matter3 some varieties contain mica4 ,all these earthy and generally white stones insensibly pass into more indurated sonorous varieties1 breaking with a conchoidal fracture1 yet of small specific gravity2 many of these latter varieties assume a pale purple tint1 being singularly banded and veined with different shades1 and often become plainly porphyritic with crystals of feldspar4 ,the formation of these crystals could be most clearly traced by minute angular and often partially hollow patches of earthy matter1 first assuming a ,,fibrous ,,structure1 then passing into opaque imperfectly shaped crystals1 and lastly1 into perfect glassy crystals4 ,when these crystals have appeared1 and when the basis has become compact1 the rock in many places could not be distinguished from a true claystone porphyry without a trace of mechanical structure4 ,in some parts1 these earthy or tufaceous beds pass into jaspery and into beautifully mottled and banded porcelain rocks1 which break into splinters1 translucent at their edges1 hard enough to scratch glass1 and fusible into white transparent beads3 grains of quartz included in the porcelainous varieties can be seen melting into the surrounding paste4 ,in other parts1 the earthy or tufaceous beds either insensibly pass into1 or alternate with1 breccias composed of large and small fragments of various purplish porphyries1 with the matrix generally porphyritic3 these breccias1 though their subaqueous origin is in many places shown both by the arrangement of their smaller particles and by an oblique or current lamination1 also pass into porphyries1 in which every trace of mechanical origin and stratification has been obliterated4 ,some highly porphyritic though coarse-grained masses1 evidently of sedimentary origin1 and divided into thin layers1 differing from each other chiefly in the number of embedded grains of quartz1 interested me much from the peculiar manner in which here and there some of the layers terminated in abrupt points1 quite unlike those produced by a layer of sediment naturally thinning out1 and apparently the result of a subsequent process of metamorphic aggregation4 ,in another common variety of a finer texture1 the aggregating process had gone further1 for the whole mass consisted of quite short1 parallel1 often slightly curved layers or patches1 of whitish or reddish finely granulo-crystalline feldspathic matter1 generally terminating at both ends in blunt points2 these layers or patches further tended to pass into wedge or almond-shaped little masses1 and these finally into true crystals of feldspar1 with their centres often slightly drusy4 ,the series was so perfect that ,i could not doubt that these large crystals1 which had their longer axes placed parallel to each other1 had primarily originated in the metamorphosis and aggregation of alternating layers of tuff2 and hence their parallel position must be attributed 7unexpected though the conclusion may be71 not to laws of chemical action1 but to the original planes of deposition4 ,i am tempted briefly to describe three other singular allied varieties of rock2 the first without examination would have passed for a stratified porphyritic breccia1 but all the included angular fragments consisted of a border of pinkish crystalline feldspathic matter1 surrounding a dark translucent siliceous centre1 in which grains of quartz not quite blended into the paste could be distinguished3 this uniformity in the nature of the fragments shows that they are not of mechanical1 but of concretionary origin1 having resulted perhaps from the self-breaking up and aggregation of layers of indurated tuff containing numerous grains of quartz1--into which1 indeed1 the whole mass in one part passed4 ,the second variety is a reddish non-porphyritic claystone1 quite full of spherical cavities1 about half an inch in diameter1 each lined with a collapsed crust formed of crystals of quartz4 ,the third variety also consists of a pale purple non-porphyritic claystone1 almost wholly formed of concretionary balls1 obscurely arranged in layers1 of a less compact and paler coloured claystone2 each ball being on one side partly hollow and lined with crystals of quartz4 ,,pseudo-,,dikes4 ,some miles up the harbour1 in a line of cliffs formed of slightly metamorphosed tufaceous and porphyritic claystone beds1 ,i observed three vertical dikes1 so closely resembling in general appearance ordinary volcanic dikes1 that ,i did not doubt1 until closely examining their composition1 that they had been injected from below4 ,the first is straight1 with parallel sides1 and about four feet wide2 it consists of whitish1 indurated tufaceous matter1 precisely like some of the beds intersected by it4 ,the second dike is more remarkable2 it is slightly tortuous1 about eighteen inches thick1 and can be traced for a considerable distance along the beach2 it is of a purplish-red or brown colour1 and is formed chiefly of ,,rounded grains of quartz1 with broken crystals of earthy feldspar1 scales of black mica1 and minute fragments of claystone porphyry1 all firmly united together in a hard sparing base4 ,the structure of this dike shows obviously that it is of mechanical and sedimentary origin2 yet it thinned out upwards1 and did not cut through the uppermost strata in the cliffs4 ,this fact at first appears to indicate that the matter could not have been washed in from above 7,upfilled fissures are known to occur both in volcanic and in ordinary sedimentary formations4 ,at the ,galapagos ,archipelago 8,volcanic ,islands0 etc41 there are some striking examples of pseudo-dikes composed of hard tuff472 but if we reflect on the suction which would result from a deep-seated fissure being formed1 we may admit that if the fissure were in any part open to the surface1 mud and water might well be drawn into it along its whole course4 ,the third dike consisted of a hard1 rough1 white rock1 almost composed of broken crystals of glassy feldspar1 with numerous scales of black mica1 cemented in a scanty base2 there was little in the appearance of this rock1 to preclude the idea of its having been a true injected feldspathic dike4 ,the matter composing these three pseudo-dikes1 especially the second one1 appears to have suffered1 like the surrounding strata1 a certain degree of metamorphic action2 and this has much aided the deceptive appearance4 ,at ,bahia1 in ,brazil1 we have seen that a true injected hornblendic dike1 not only has suffered metamorphosis1 but has been dislocated and even diffused in the surrounding gneiss1 under the form of separate crystals and of fragments4 ,,falkland ,,islands4 ,i have described these islands in a paper published in the third volume of the 8,geological ,journal40 ,the mountain-ridges consist of quartz1 and the lower country of clay-slate and sandstone1 the latter containing ,palaeozoic fossils4 ,these fossils have been separately described by ,messrs4 ,morris and ,sharpe3 some of them resemble ,silurian1 and others ,devonian forms4 ,in the eastern part of the group the several parallel ridges of quartz extend in a west and east line2 but further westward the line becomes ,w4,n4,w4 and ,e4,s4,e41 and even still more northerly4 ,the cleavage-planes of the clay- slate are highly inclined1 generally at an angle of above #ej degrees1 and often vertical2 they strike almost invariably in the same direction with the quartz ranges4 ,the outline of the indented shores of the two main islands1 and the relative positions of the smaller islets1 accord with the strike both of the main axes of elevation and of the cleavage of the clay- slate4 ,,tierra ,,del ,,fuego4 ,my notes on the geology of this country are copious1 but as they are unimportant1 and as fossils were found only in one district1 a brief sketch will be here sufficient4 ,the east coast from the ,s4 of ,magellan 7where the boulder formation is largely developed7 to ,st4 ,polycarp's ,bay is formed of horizontal tertiary strata1 bounded some way towards the interior by a broad mountainous band of clay-slate4 ,this great clay-slate formation extends from ,st4 ,le ,maire westward for #adj miles1 along both sides of the ,beagle ,channel to near its bifurcation4 ,south of this channel1 it forms all ,navarin ,island1 and the eastern half of ,hoste ,island and of ,hardy ,peninsula2 north of the ,beagle ,channel it extends in a north-west line on both sides of ,admiralty ,sound to ,brunswick ,peninsula in the ,st4 of ,magellan1 and ,i have reason to believe1 stretches far up the eastern side of the ,cordillera4 ,the western and broken side of ,tierra del ,fuego towards the ,pacific is formed of metamorphic schists1 granite and various trappean rocks3 the line of separation between the crystalline and clay-slate formations can generally be distinguished1 as remarked by ,captain ,king1 by the parallelism in the clay-slate districts of the shores and channels1 ranging in a line between ,w4 #bj degrees to #dj degrees ,n4 and ,e4 #bj degrees to #dj degrees ,s44 78,geographical ,journal0 volume #a page #aee47 ,the clay-slate is generally fissile1 sometimes siliceous or ferruginous1 with veins of quartz and calcareous spar2 it often assumes1 especially on the loftier mountains1 an altered feldspathic character1 passing into feldspathic porphyry3 occasionally it is associated with breccia and grauwacke4 ,at ,good ,success ,bay1 there is a little intercalated black crystalline limestone4 ,at ,port ,famine much of the clay-slate is calcareous1 and passes either into a mudstone or into grauwacke1 including odd-shaped concretions of dark argillaceous limestone4 ,here alone1 on the shore a few miles north of ,port ,famine1 and on the summit of ,mount ,tarn 7#b1fjj feet high71 ,i found organic remains2 they consist of3-- #a4 ,ancyloceras simplex1 d',orbigny 8,pal ,franc0 ,mount ,tarn4 #b4 ,fusus 7in imperfect state71 d',orbigny 8,pal ,franc0 ,mount ,tarn4 #c4 ,natica1 d',orbigny 8,pal ,franc0 ,mount ,tarn4 #d4 ,pentacrimus1 d',orbigny 8,pal ,franc0 ,mount ,tarn4 #e4 ,lucina excentrica1 ,g4,b4 ,sowerby1 ,port ,famine4 #f4 ,venus 7in imperfect state71 ,g4,b4 ,sowerby1 ,port ,famine4 #g4 ,turbinolia 7871 ,g4,b4 ,sowerby1 ,port ,famine4 #h4 ,hamites elatior1 ,g4,b4 ,sowerby1 ,port ,famine4 ,m4 d',orbigny states that ,,mm4 ,hombron and ,grange found in this neighbourhood an ,ancyloceras1 perhaps ,a4 simplex1 an ,ammonite1 a ,plicatula and ,modiola4 78,voyage0 ,part ,geolog4 page #bdb47 ,m4 d',orbigny believes from the general character of these fossils1 and from the ,ancyloceras being identical 7as far as its imperfect condition allows of comparison7 with the ,a4 simplex of ,europe1 that the formation belongs to an early stage of the ,cretaceous system4 ,professor ,e4 ,forbes1 judging only from my specimens1 concurs in the probability of this conclusion4 ,the ,hamites elatior of the above list1 of which a description has been given by ,mr4 ,sowerby1 and which is remarkable from its large size1 has not been seen either by ,m4 d',orbigny or ,professor ,e4 ,forbes1 as1 since my return to ,england1 the specimens have been lost4 ,the great clay-slate formation of ,tierra del ,fuego being cretaceous1 is certainly a very interesting fact1--whether we consider the appearance of the country1 which1 without the evidence afforded by the fossils1 would form the analogy of most known districts1 probably have been considered as belonging to the ,palaeozoic series1--or whether we view it as showing that the age of this terminal portion of the great axis of ,south ,america1 is the same 7as will hereafter be seen7 with the ,cordillera of ,chile and ,peru4 ,the clay-slate in many parts of ,tierra del ,fuego1 is broken by dikes and by great masses of greenstone1 often highly hornblendic 7,in a greenstone-dike in the ,magdalen ,channel1 the feldspar cleaved with the angle of albite4 ,this dike was crossed1 as well as the surrounding slate1 by a large vein of quartz1 a circumstance of unusual occurrence473 almost all the small islets within the clay-slate districts are thus composed4 ,the slate near the dikes generally becomes paler-coloured1 harder1 less fissile1 of a feldspathic nature1 and passes into a porphyry or greenstone3 in one case1 however1 it became more fissile1 of a red colour1 and contained minute scales of mica1 which were absent in the unaltered rock4 ,on the east side of ,ponsonby ,sound some dikes composed of a pale sonorous feldspathic rock1 porphyritic with a little feldspar1 were remarkable from their number1--there being within the space of a mile at least one hundred1--from their nearly equalling in bulk the intermediate slate1--and more especially from the excessive fineness 7like the finest inlaid carpentry7 and perfect parallelism of their junctions with the almost vertical laminae of clay-slate4 ,i was unable to persuade myself that these great parallel masses had been injected1 until ,i found one dike which abruptly thinned out to half its thickness1 and had one of its walls jagged1 with fragments of the slate embedded in it4 ,in ,southern ,tierra del ,fuego1 the clay-slate towards its ,s4,w4 boundary1 becomes much altered and feldspathic4 ,thus on ,wollaston ,island slate and grauwacke can be distinctly traced passing into feldspathic rocks and greenstones1 including iron pyrites and epidote1 but still retaining traces of cleavage with the usual strike and dip4 ,one such metamorphosed mass was traversed by large vein-like masses of a beautiful mixture 7as ascertained by ,professor ,miller7 of green epidote1 garnets1 and white calcareous spar4 ,on the northern point of this same island1 there were various ancient submarine volcanic rocks1 consisting of amygdaloids with dark bole and agate1--of basalt with decomposed olivine--of compact lava with glassy feldspar1--and of a coarse conglomerate of red scoriae1 parts being amygdaloidal with carbonate of lime4 ,the southern part of ,wollaston ,island and the whole of ,hermite and ,horn ,islands1 seem formed of cones of greenstone2 the outlying islets of ,il ,defenso and ,d4 ,raminez are said to consist of porphyritic lava4 7,determined by ,professor ,jameson4 ,weddell's 8,voyage0 page #afi47 ,in crossing ,hardy ,peninsula1 the slate still retaining traces of its usual cleavage1 passes into columnar feldspathic rocks1 which are succeeded by an irregular tract of trappean and basaltic rocks1 containing glassy feldspar and much iron pyrites3 there is1 also1 some harsh red claystone porphyry1 and an almost true trachyte1 with needles of hornblende1 and in one spot a curious slaty rock divided into quadrangular columns1 having a base almost like trachyte1 with drusy cavities lined by crystals1 too imperfect1 according to ,professor ,miller1 to be measured1 but resembling ,zeagonite4 7,see ,mr4 ,brooke's ,paper in the 8,london ,philosophical ,magazine0 volume #aj4 ,this mineral occurs in an ancient volcanic rock near ,rome47 ,in the midst of these singular rocks1 no doubt of ancient submarine volcanic origin1 a high hill of feldspathic clay-slate projected1 retaining its usual cleavage4 ,near this point1 there was a small hillock1 having the aspect of granite1 but formed of white albite1 brilliant crystals of hornblende 7both ascertained by the reflecting goniometer7 and mica2 but with no quartz4 ,no recent volcanic district has been observed in any part of ,tierra del ,fuego4 ,five miles west of the bifurcation of the ,beagle ,channel1 the slate- formation1 instead of becoming1 as in the more southern parts of ,tierra del ,fuego1 feldspathic1 and associated with trappean or old volcanic rocks1 passes by alternations into a great underlying mass of fine gneiss and glossy clay-slate1 which at no great distance is succeeded by a grand formation of mica-slate containing garnets4 ,the folia of these metamorphic schists strike parallel to the cleavage-planes of the clay-slate1 which have a very uniform direction over the whole of this part of the country3 the folia1 however1 are undulatory and tortuous1 whilst the cleavage- laminae of the slate are straight4 ,these schists compose the chief mountain-chain of ,southern ,tierra del ,fuego1 ranging along the north side of the northern arm of the ,beagle ,channel1 in a short ,w4,n4,w4 and ,e4,s4,e4 line1 with two points 7,mounts ,sarmiento and ,darwin7 rising to heights of #f1hjj and #f1ijj feet4 ,on the south-western side of this northern arm of the ,beagle ,channel1 the clay-slate is seen with its ,,strata dipping from the great chain1 so that the metamorphic schists here form a ridge bordered on each side by clay-slate4 ,further north1 however1 to the west of this great range1 there is no clay-slate1 but only gneiss1 mica1 and hornblendic slates1 resting on great barren hills of true granite1 and forming a tract about sixty miles in width4 ,again1 westward of these rocks1 the outermost islands are of trappean formation1 which1 from information obtained during the voyages of the 8,adventure0 and 8,beagle10 seem1 together with granite1 chiefly to prevail along the western coast as far north as the entrance of the ,st4 of ,magellan 7,see the ,paper by ,captain ,king in the 8,geographical ,journal02 also a ,letter to ,dr4 ,fitton in 8,geological ,proceedings0 volume #a page #bi2 also some observations by ,captain ,fitzroy 8,voyages0 volume #a page #cge4 ,i am indebted also to ,mr4 ,lyell for a series of specimens collected by ,lieutenant ,graves473 a little more inland1 on the eastern side of ,clarence ,island and ,s4 ,desolation1 granite1 greenstone1 mica-slate1 and gneiss appear to predominate4 ,i am tempted to believe1 that where the clay-slate has been metamorphosed at great depths beneath the surface1 gneiss1 mica- slate1 and other allied rocks have been formed1 but where the action has taken place nearer the surface1 feldspathic porphyries1 greenstones1 etc41 have resulted1 often accompanied by submarine volcanic eruptions4 ,only one other rock1 met with in both arms of the ,beagle ,channel1 deserves any notice1 namely a granulo-crystalline mixture of white albite1 black hornblende 7ascertained by measurement of the crystals1 and confirmed by ,professor ,miller71 and more or less of brown mica1 but without any quartz4 ,this rock occurs in large masses1 closely resembling in external form granite or syenite3 in the southern arm of the ,channel1 one such mass underlies the mica-slate1 on which clay-slate was superimposed3 this peculiar plutonic rock which1 as we have seen1 occurs also in ,hardy ,peninsula1 is interesting1 from its perfect similarity with that 7hereafter often to be referred to under the name of andesite7 forming the great injected axes of the ,cordillera of ,chile4 ,the stratification of the clay-slate is generally very obscure1 whereas the cleavage is remarkably well defined3 to begin with the extreme eastern parts of ,tierra del ,fuego2 the cleavage-planes near the ,st4 of ,le ,maire strike either ,w4 and ,e4 or ,w4,s4,w4 and ,e4,n4,e41 and are highly inclined2 the form of the land1 including ,staten ,island1 indicates that the axes of elevation have run in this same line1 though ,i was unable to distinguish the planes of stratification4 ,proceeding westward1 ,i accurately examined the cleavage of the clay-slate on the northern1 eastern1 and western sides 7thirty-five miles apart7 of ,navarin ,island1 and everywhere found the laminae ranging with extreme regularity1 ,w4,n4,w4 and ,e4,s4,e41 seldom varying more than one point of the compass from this direction4 7,the clay-slate in this island was in many places crossed by parallel smooth joints4 ,out of five cases1 the angle of intersection between the strike of these joints and that of the cleavage-laminae was in two cases #de degrees and in two others #gi degrees47 ,both on the east and west coasts1 ,i crossed at right angles the cleavage-planes for a space of about eight miles1 and found them dipping at an angle of between #de degrees and #ij degrees1 generally to ,s4,s4,w41 sometimes to ,n4,n4,e41 and often quite vertically4 ,the ,s4,s4,w4 dip was occasionally succeeded abruptly by a ,n4,n4,e4 dip1 and this by a vertical cleavage1 or again by the ,s4,s4,w4 dip2 as in a lofty cliff on the eastern end of the island the laminae of slate were seen to be folded into very large steep curves1 ranging in the usual ,w4,n4,w4 line1 ,i suspect that the varying and opposite dips may possibly be accounted for by the cleavage- laminae1 though to the eye appearing straight1 being parts of large abrupt curves1 with their summits cut off and worn down4 ,in several places ,i was particularly struck with the fact1 that the fine laminae of the clay-slate1 where cutting straight through the bands of stratification1 and therefore indisputably true cleavage-planes1 differed slightly in their greyish and greenish tints of colour1 in compactness1 and in some of the laminae having a rather more jaspery appearance than others4 ,i have not seen this fact recorded1 and it appears to me important1 for it shows that the same cause which has produced the highly fissile structure1 has altered in a slight degree the mineralogical character of the rock in the same planes4 ,the bands of stratification1 just alluded to1 can be distinguished in many places1 especially in ,navarin ,island1 but only on the weathered surfaces of the slate2 they consist of slightly undulatory zones of different shades of colour and of thicknesses1 and resemble the marks 7more closely than anything else to which ,i can compare them7 left on the inside of a vessel by the draining away of some dirty slightly agitated liquid3 no difference in composition1 corresponding with these zones1 could be seen in freshly fractured surfaces4 ,in the more level parts of ,navarin ,island1 these bands of stratification were nearly horizontal2 but on the flanks of the mountains they were inclined from them1 but in no instance that ,i saw at a very high angle4 ,there can1 ,i think1 be no doubt that these zones1 which appear only on the weathered surfaces1 are the last vestiges of the original planes of stratification1 now almost obliterated by the highly fissile and altered structure which the mass has assumed4 ,the clay-slate cleaves in the same ,w4,n4,w4 and ,e4,s4,e4 direction1 as on ,navarin ,island1 on both sides of the ,beagle ,channel1 on the eastern side of ,hoste ,island1 on the ,n4,e4 side of ,hardy ,peninsula1 and on the northern point of ,wollaston ,island2 although in these two latter localities the cleavage has been much obscured by the metamorphosed and feldspathic condition of the slate4 ,within the area of these several islands1 including ,navarin ,island1 the direction of the stratification and of the mountain- chains is very obscure2 though the mountains in several places appeared to range in the same ,w4,n4,w4 line with the cleavage3 the outline of the coast1 however1 does not correspond with this line4 ,near the bifurcation of the ,beagle ,channel1 where the underlying metamorphic schists are first seen1 they are foliated 7with some irregularities71 in this same ,w4,n4,w4 line1 and parallel1 as before stated1 to the main mountain-axis of this part of the country4 ,westward of this main range1 the metamorphic schists are foliated1 though less plainly1 in the same direction1 which is likewise common to the zone of old erupted trappean rocks1 forming the outermost islets4 ,hence the area1 over which the cleavage of the slate and the foliation of the metamorphic schists extends with an average ,w4,n4,w4 and ,e4,s4,e4 strike1 is about forty miles in a north and south line1 and ninety miles in an east and west line4 ,further northward1 near ,port ,famine1 the stratification of the clay-slate and of the associated rocks1 is well defined1 and there alone the cleavage and strata-planes are parallel4 ,a little north of this port there is an anticlinal axis ranging ,n4,w4 7or a little more westerly7 and ,s4,e43 south of the port1 as far as ,admiralty ,sound and ,gabriel ,channel1 the outline of the land clearly indicates the existence of several lines of elevation in this same ,n4,w4 direction1 which1 ,i may add1 is so uniform in the western half of the ,st4 of ,magellan1 that1 as ,captain ,king has remarked1 8a parallel ruler placed on the map upon the projecting points of the south shore1 and extended across the strait1 will also touch the headlands on the opposite coast40 78,geographical ,journal0 volume #a page #agj47 ,it would appear1 from ,captain ,king's observations1 that over all this area the cleavage extends in the same line4 ,deep-water channels1 however1 in all parts of ,tierra del ,fuego have burst through the trammels both of stratification and cleavage2 most of them may have been formed during the elevation of the land by long- continued erosion1 but others1 for instance the ,beagle ,channel1 which stretches like a narrow canal for #abj miles obliquely through the mountains1 can hardly have thus originated4 ,finally1 we have seen that in the extreme eastern point of ,tierra del ,fuego1 the cleavage and coast-lines extend ,w4 and ,e4 and even ,w4,s4,w4 and ,e4,n4,e43 over a large area westward1 the cleavage1 the main range of mountains1 and some subordinate ranges1 but not the outlines of the coast1 strike ,w4,n4,w41 and ,e4,s4,e43 in the central and western parts of the ,st4 of ,magellan1 the stratification1 the mountain-ranges1 the outlines of the coast1 and the cleavage all strike nearly ,n4,w4 and ,s4,e4 ,north of the strait1 the outline of the coast1 and the mountains on the mainland1 run nearly north and south4 ,hence we see1 at this southern point of the continent1 how gradually the ,cordillera bend1 from their north and south course of so many thousand miles in length1 into an ,e4 and even ,e4,n4,e4 direction4 ,,west ,,coast1 ,,from ,,the ,,southern ,,chonos ,,islands ,,to ,,northern ,,chile4 ,the first place at which we landed north of the ,st4 of ,magellan was near ,cape ,tres ,montes1 in latitude #dg degrees ,s4 ,between this point and the ,northern ,chonos ,islands1 a distance of #bjj miles1 the 8,beagle0 visited several points1 and specimens were collected for me from the intermediate spaces by ,lieutenant ,stokes4 ,the predominant rock is mica-slate1 with thick folia of quartz1 very frequently alternating with and passing into a chloritic1 or into a black1 glossy1 often striated1 slightly anthracitic schist1 which soils paper1 and becomes white under a great heat1 and then fuses4 ,thin layers of feldspar1 swelling at intervals into well crystallised kernels1 are sometimes included in these black schists2 and ,i observed one mass of the ordinary black variety insensibly lose its fissile structure1 and pass into a singular mixture of chlorite1 epidote1 feldspar1 and mica4 ,great veins of quartz are numerous in the mica-schists2 wherever these occur the folia are much convoluted4 ,in the southern part of the ,peninsula of ,tres ,montes1 a compact altered feldspathic rock with crystals of feldspar and grains of quartz is the commonest variety2 this rock exhibits occasionally traces of an original brecciated structure1 and often presents 7like the altered state of ,tierra del ,fuego7 traces of cleavage- planes1 which strike in the same direction with the folia of mica-schist further northward4 7,the peculiar1 abruptly conical form of the hills in this neighbourhood1 would have led any one at first to have supposed that they had been formed of injected or intrusive rocks4 ,at ,inchemo ,island1 a similar rock gradually becomes granulo-crystalline and acquires scales of mica2 and this variety at ,s4 ,estevan becomes highly laminated1 and though still exhibiting some rounded grains of quartz1 passes into the black1 glossy1 slightly anthracitic schist1 which1 as we have seen1 repeatedly alternates with and passes into the micaceous and chloritic schists4 ,hence all the rocks on this line of coast belong to one series1 and insensibly vary from an altered feldspathic clay-slate into largely foliated1 true mica-schist4 ,the cleavage of the homogeneous schists1 the foliation of those composed of more or less distinct minerals in layers1 and the planes of alternation of the different varieties or so-called stratification1 are all parallel1 and preserve over this #bjj miles of coast a remarkable degree of uniformity in direction4 ,at the northern end of the group1 at ,low's ,harbour1 the well- defined folia of mica-schist everywhere ranged within eight degrees 7or less than one point of the compass7 of ,n4 #ai degrees ,w4 and ,s4 #ai degrees ,e42 and even the point of dip varied very little1 being always directed to the west and generally at an angle of forty degrees2 ,i should mention that ,i had here good opportunities of observation1 for ,i followed the naked rock on the beach1 transversely to the strike1 for a distance of four miles and a half1 and all the way attended to the dip4 ,along the outer islands for #ajj miles south of ,low's ,harbour1 ,lieutenant ,stokes1 during his boat- survey1 kindly observed for me the strike of the foliation1 and he assures me that it was invariably northerly1 and the dip with one single exception to the west4 ,further south at ,vallenar ,bay1 the strike was almost universally ,n4 #be degrees ,w4 and the dip1 generally at an angle of about #dj degrees to ,w4 #be degrees ,s41 but in some places almost vertical4 ,still farther south1 in the neighbourhood of the harbours of ,anna ,pink1 ,s4 ,estevan and ,s4 ,andres1 and 7judging from a distance7 along the southern part of ,tres ,montes1 the foliation and cleavage extended in a line between ,n4 #aa degrees to #bb degrees ,w4 and ,s4 #aa degrees to #bb degrees ,e42 and the planes dipped generally westerly1 but often easterly1 at angles varying from a gentle inclination to vertical4 ,at ,a4 ,pink's ,harbour1 where the schists generally dipped easterly1 wherever the angle became very high1 the strike changed from ,n4 #aa degrees ,w4 to even as much as ,n4 #de degrees ,w43 in an analogous manner at ,vallenar ,bay1 where the dip was westerly 7viz4 on an average directed to ,w4 #be degrees ,s471 as soon as the angle became very high1 the planes struck in a line more than #be degrees west of north4 ,the average result from all the observations on this #bjj miles of coast1 is a strike of ,n4 #ai degrees ,w4 and ,s4 #ai degrees ,e43 considering that in each specified place my examination extended over an area of several miles1 and that ,lieutenant ,stokes' observations apply to a length of #ajj miles1 ,i think this remarkable uniformity is pretty well established4 ,the prevalence1 throughout the northern half of this line of coast1 of a dip in one direction1 that is to the west1 instead of being sometimes west and sometimes east1 is1 judging from what ,i have elsewhere seen1 an unusual circumstance4 ,in ,brazil1 ,la ,plata1 the ,falkland ,islands1 and ,tierra del ,fuego1 there is generally an obvious relation between the axis of elevation1 the outline of the coast1 and the strike of the cleavage or foliation3 in the ,chonos ,archipelago1 however1 neither the minor details of the coast-line1 nor the chain of the ,cordillera1 nor the subordinate transverse mountain-axes1 accord with the strike of the foliation and cleavage3 the seaward face of the numerous islands composing this ,archipelago1 and apparently the line of the ,cordillera1 range ,n4 #aa degrees ,e41 whereas1 as we have just seen1 the average strike of the foliation is ,n4 #ai degrees ,w4 ,there is one interesting exception to the uniformity in the strike of the foliation4 ,at the northern point of ,tres ,montes 7latitude #de degrees #eb minutes7 a bold chain of granite1 between two and three thousand feet in height1 runs from the coast far into the interior1 in an ,e4,s4,e4 line1 or more strictly ,e4 #bh degrees ,s4 and ,w4 #bh degrees ,n4 7,in the distance1 other mountains could be seen apparently ranging ,n4,n4,e4 and ,s4,s4,w4 at right angles to this one4 ,i may add1 that not far from ,vallenar ,bay there is a fine range1 apparently of granite1 which has burst through the mica-slate in a ,n4,e4 by ,e4 and ,s4,w4 by ,s4 line47 ,in a bay1 at the northern foot of this range1 there are a few islets of mica-slate1 with the folia in some parts horizontal1 but mostly inclined at an average angle of #bj degrees to the north4 ,on the northern steep flank of the range1 there are a few patches 7some quite isolated1 and not larger than half a-crown67 of the mica-schist1 foliated with the same northerly dip4 ,on the broad summit1 as far as the southern crest1 there is much mica-slate1 in some places even #djj feet in thickness1 with the folia all dipping north1 at angles varying from #e degrees to #bj degrees1 but sometimes mounting up to #cj degrees4 ,the southern flank consists of bare granite4 ,the mica-slate is penetrated by small veins of granite1 branching from the main body4 7,the granite within these veins1 as well as generally at the junction with the mica-slate1 is more quartzose than elsewhere4 ,the granite1 ,i may add1 is traversed by dikes running for a very great length in the line of the mountains2 they are composed of a somewhat laminated eurite1 containing crystals of feldspar1 hornblende1 and octagons of quartz47 ,leaving out of view the prevalent strike of the folia in other parts of this ,archipelago1 it might have been expected that they would have dipped ,n4 #bh degrees ,e41 that is directly from the ridge1 and1 considering its abruptness1 at a high inclination2 but the real dip1 as we have just seen1 both at the foot and on the northern flank1 and over the entire summit1 is at a small angle1 and directed nearly due north4 ,from these considerations it occurred to me1 that perhaps we here had the novel and curious case of already inclined laminae obliquely tilted at a subsequent period by the granitic axis4 ,mr4 ,hopkins1 so well known from his mathematical investigations1 has most kindly calculated the problem3 the proposition sent was1--,take a district composed of laminae1 dipping at an angle of #dj degrees to ,w4 #ai degrees ,s41 and let an axis of elevation traverse it in an ,e4 #bh degrees ,s4 line1 what will the position of the laminae be on the northern flank after a tilt1 we will first suppose1 of #de degrees8 ,mr4 ,hopkins informs me1 that the angle of the dip will be #bh degrees #ca minutes1 and its direction to north #cj degrees #cc minutes west4 7,on the south side of the axis 7where1 however1 ,i did not see any mica-slate7 the dip of the folia would be at an angle of #gg degrees #ee minutes1 directed to west #ce degrees #cc minutes south4 ,hence the two points of dip on the opposite sides of the range1 instead of being as in ordinary cases directly opposed to each other at an angle of #ahj degrees1 would here be only #hf degrees #ej minutes apart47 ,by varying the supposed angle of the tilt1 our previously inclined folia can be thrown into any angle between #bf degrees1 which is the least possible angle1 and #ij degrees2 but if a small inclination be thus given to them1 their point of dip will depart far from the north1 and therefore not accord with the actual position of the folia of mica-schist on our granitic range4 ,hence it appears very difficult1 without varying considerably the elements of the problem1 thus to explain the anomalous strike and dip of the foliated mica- schist1 especially in those parts1 namely1 at the base of the range1 where the folia are almost horizontal4 ,mr4 ,hopkins1 however1 adds1 that great irregularities and lateral thrusts might be expected in every great line of elevation1 and that these would account for considerable deviations from the calculated results3 considering that the granitic axis1 as shown by the veins1 has indisputably been injected after the perfect formation of the mica-slate1 and considering the uniformity of the strike of the folia throughout the rest of the ,archipelago1 ,i cannot but still think that their anomalous position at this one point is someway directly and mechanically related to the intrusion of this ,w4,n4,w4 and ,e4,s4,e4 mountain-chain of granite4 ,dikes are frequent in the metamorphic schists of the ,chonos ,islands1 and seem feebly to represent that great band of trappean and ancient volcanic rocks on the south-western coast of ,tierra del ,fuego4 ,at ,s4 ,andres ,i observed in the space of half-a-mile1 seven broad1 parallel dikes1 composed of three varieties of trap1 running in a ,n4,w4 and ,s4,e4 line1 parallel to the neighbouring mountain-ranges of altered clay-slate2 but they must be of long subsequent origin to these mountains2 for they intersected the volcanic formation described in the last chapter4 ,north of ,tres ,montes1 ,i noticed three dikes differing from each other in composition1 one of them having a euritic base including large octagons of quartz2 these dikes1 as well as several of porphyritic greenstone at ,vallenar ,bay1 extended ,n4,e4 and ,s4,w41 nearly at right angles to the foliation of the schists1 but in the line of their joints4 ,at ,low's ,harbour1 however1 a set of great parallel dikes1 one ninety yards and another sixty yards in width1 have been guided by the foliation of the mica-schist1 and hence are inclined westward at an angle of #de degrees3 these dikes are formed of various porphyritic traps1 some of which are remarkable from containing numerous rounded grains of quartz4 ,a porphyritic trap of this latter kind1 passed in one of the dikes into a most curious hornstone1 perfectly white1 with a waxy fracture and pellucid edges1 fusible1 and containing many grains of quartz and specks of iron pyrites4 ,in the ninety-yard dike several large1 apparently now quite isolated1 fragments of mica-slate were embedded3 but as their foliation was exactly parallel to that of the surrounding solid rock1 no doubt these new separate fragments originally formed wedge-shaped depending portions of a continuous vault or crust1 once extending over the dike1 but since worn down and denuded4 ,,chiloe1 ,,valdivia1 ,,concepcion4 ,in ,chiloe1 a great formation of mica-schist strikingly resembles that of the ,chonos ,islands4 ,for a space of eleven miles on the ,s4,e4 coast1 the folia were very distinct1 though slightly convoluted1 and ranged within a point of ,n4,n4,w4 and ,s4,s4,e41 dipping either ,e4,n4,e4 or more commonly ,w4,s4,w41 at an average angle of #bb degrees 7in one spot1 however1 at #fj degrees71 and therefore decidedly at a lesser inclination than amongst the ,chonos ,islands4 ,on the west and north-western shores1 the foliation was often obscure1 though1 where best defined1 it ranged within a point of ,n4 by ,w4 and ,s4 by ,e41 dipping either easterly or westerly1 at varying and generally very small angles4 ,hence1 from the southern part of ,tres ,montes to the northern end of ,chiloe1 a distance of #cjj miles1 we have closely allied rocks with their folia striking on an average in the same direction1 namely between ,n4 #aa degrees and #bb degrees ,w4 ,again1 at ,valdivia1 we meet with the same mica-schist1 exhibiting nearly the same mineralogical passages as in the ,chonos ,archipelago1 often1 however1 becoming more ferruginous1 and containing so much feldspar as to pass into gneiss4 ,the folia were generally well defined2 but nowhere else in ,south ,america did ,i see them varying so much in direction3 this seemed chiefly caused by their forming parts1 as ,i could sometimes distinctly trace1 of large flat curves3 nevertheless1 both near the settlement and towards the interior1 a ,n4,w4 and ,s4,e4 strike seemed more frequent than any other direction2 the angle of the dip was generally small4 ,at ,concepcion1 a highly glossy clay-slate had its cleavage often slightly curvilinear1 and inclined1 seldom at a high angle1 towards various points of the compass3 but here1 as at ,valdivia1 a ,n4,w4 and ,s4,e4 strike seemed to be the most frequent one4 77,,figure #bc47 ,i observed in some parts that the tops of the laminae of the clay-slate 7b in ,figure #bc7 under the superficial detritus and soil 7a7 were bent1 sometimes without being broken1 as represented in ,figure #bc1 which is copied from one given by ,sir ,h4 ,de la ,beche 7page #db 8,geological ,manual07 of an exactly similar phenomenon in ,devonshire4 ,mr4 ,r4,a4,c4 ,austen1 also1 in his excellent paper on ,s4,e4 ,devon 78,geological ,transactions0 volume #f page #dcg71 has described this phenomenon2 he attributes it to the action of frosts1 but at the same time doubts whether the frosts of the present day penetrate to a sufficient depth4 ,as it is known that earthquakes particularly affect the surface of the ground1 it occurred to me that this appearance might perhaps be due1 at least at ,concepcion1 to their frequent occurrence2 the superficial layers of detritus being either jerked in one direction1 or1 where the surface was inclined1 pushed a little downwards during each strong vibration4 ,in ,north ,wales ,i have seen a somewhat analogous but less regular appearance1 though on a greater scale 78,london ,philosophical ,magazine0 volume #ba page #ahd71 and produced by a quite different cause1 namely1 by the stranding of great icebergs2 this latter appearance has also been observed in ,n4 ,america47 ,in certain spots large quartz veins were numerous1 and near them1 the cleavage1 as was the case with the foliation of the schists in the ,chonos ,archipelago1 became extremely tortuous4 ,at the northern end of ,quiriquina ,island1 in the ,bay of ,concepcion1 at least eight rudely parallel dikes1 which have been guided to a certain extent by the cleavage of the slate1 occur within the space of a quarter of a mile4 ,they vary much in composition1 resembling in many respects the dikes at ,low's ,harbour3 the greater number consist of feldspathic porphyries1 sometimes containing grains of quartz3 one1 however1 was black and brilliant1 like an augitic rock1 but really formed of feldspar2 others of a feldspathic nature were perfectly white1 with either an earthy or crystalline fracture1 and including grains and regular octagons of quartz2 these white varieties passed into ordinary greenstones4 ,although1 both here and at ,low's ,harbour1 the nature of the rock varied considerably in the same dike1 yet ,i cannot but think that at these two places and in other parts of the ,chonos group1 where the dikes1 though close to each other and running parallel1 are of different composition1 that they must have been formed at different periods4 ,in the case of ,quiriquina this is a rather interesting conclusion1 for these eight parallel dikes cut through the metamorphic schists in a ,n4,w4 and ,s4,e4 line1 and since their injection the overlying cretaceous or tertiary strata have been tilted 7whilst still under the sea7 from a ,n4,w4 by ,n4 and ,s4,e4 by ,s4 line2 and again1 during the great earthquake of ,february #ahce1 the ground in this neighbourhood was fissured in ,n4,w4 and ,s4,e4 lines2 and from the manner in which buildings were thrown down1 it was evident that the surface undulated in this same direction4 78,geological ,transactions0 volume #f pages #fjb and #fag4 8,journal of ,researches0 #bnd edition page #cjg47 ,,central ,,and ,,northern ,,chile4 ,northward of ,concepcion1 as far as ,copiapo1 the shores of the ,pacific consist1 with the exception of some small tertiary basins1 of gneiss1 mica- schist1 altered clay-slate1 granite1 greenstone and syenite3 hence the coast from ,tres ,montes to ,copiapo1 a distance of #a1bjj miles1 and ,i have reason to believe for a much greater space1 is almost similarly constituted4 ,near ,valparaiso the prevailing rock is gneiss1 generally including much hornblende3 concretionary balls formed of feldspar1 hornblende and mica1 from two or three feet in diameter1 are in very many places conformably enfolded by the foliated gneiss3 veins of quartz and feldspar1 including black schorl and well-crystallised epidote1 are numerous4 ,epidote likewise occurs in the gneiss in thin layers1 parallel to the foliation of the mass4 ,one large vein of a coarse granitic character was remarkable from in one part quite changing its character1 and insensibly passing into a blackish porphyry1 including acicular crystals of glassy feldspar and of hornblende3 ,i have never seen any other such case4 7,humboldt 8,personal ,narrative0 volume #d page #fj1 has described with much surprise1 concretionary balls1 with concentric divisions1 composed of partially vitreous feldspar1 hornblende1 and garnets1 included within great veins of gneiss1 which cut across the mica-slate near ,venezuela47 ,i shall in the few following remarks on the rocks of ,chile allude exclusively to their foliation and cleavage4 ,in the gneiss round ,valparaiso the strike of the foliation is very variable1 but ,i think about ,n4 by ,w4 and ,s4 by ,e4 is the commonest direction2 this likewise holds good with the cleavage of the altered feldspathic clay-slates1 occasionally met with on the coast for ninety miles north of ,valparaiso4 ,some feldspathic slate1 alternating with strata of claystone porphyry in the ,bell of ,quillota and at ,jajuel1 and therefore1 perhaps1 belonging to a later period than the metamorphic schists on the coast1 cleaved in this same direction4 ,in the ,eastern ,cordillera1 in the ,portillo ,pass1 there is a grand mass of mica- slate1 foliated in a north and south line1 and with a high westerly dip3 in the ,uspallata range1 clay-slate and grauwacke have a highly inclined1 nearly north and south cleavage1 though in some parts the strike is irregular3 in the main or ,cumbre range1 the direction of the cleavage in the feldspathic clay-slate is ,n4,w4 and ,s4,e4 ,between ,coquimbo and ,guasco there are two considerable formations of mica- slate1 in one of which the rock passed sometimes into common clay-slate and sometimes into a glossy black variety1 very like that in the ,chonos ,archipelago4 ,the folia and cleavage of these rocks ranged between ,n4 and ,n4,w4 by ,n4 and ,s4 and ,s4,w4 by ,s44 ,near the ,port of ,guasco several varieties of altered clay-slate have a quite irregular cleavage4 ,between ,guasco and ,copiapo1 there are some siliceous and talcaceous slates cleaving in a north and south line1 with an easterly dip of between #fj and #gj degrees3 high up1 also1 the main valley of ,copiapo1 there is mica-slate with a high easterly dip4 ,in the whole space between ,valparaiso and ,copiapo an easterly dip is much more common than an opposite or westerly one4 ,,concluding ,,remarks ,,on ,,cleavage ,,and ,,foliation4 ,in this southern part of the southern hemisphere1 we have seen that the cleavage-laminae range over wide areas with remarkable uniformity1 cutting straight through the planes of stratification1 but yet being parallel in strike to the main axes of elevation1 and generally to the outlines of the coast4 7,in my paper on the ,falkland ,islands 8,geological ,journal0 volume #c page #bfg1 ,i have given a curious case on the authority of ,captain ,sulivan1 ,r4,n41 of much folded beds of clay-slate1 in some of which the cleavage is perpendicular to the horizon1 and in others it is perpendicular to each curvature or fold of the bed3 this appears a new case47 ,the dip1 however1 is as variable1 both in angle and in direction 7that is1 sometimes being inclined to the one side and sometimes to the directly opposite side71 as the strike is uniform4 ,in all these respects there is a close agreement with the facts given by ,professor ,sedgwick in his celebrated memoir in the 8,geological ,transactions10 and by ,sir ,r4,i4 ,murchison in his various excellent discussions on this subject4 ,the ,falkland ,islands1 and more especially ,tierra del ,fuego1 offer striking instances of the lines of cleavage1 the principle axes of elevation1 and the outlines of the coast1 gradually changing together their courses4 ,the direction which prevails throughout ,tierra del ,fuego and the ,falkland ,islands1 namely1 from west with some northing to east with some southing1 is also common to the several ridges in ,northern ,patagonia and in the western parts of ,banda ,oriental3 in this latter province1 in the ,sierra ,tapalguen1 and in the ,western ,falkland ,island1 the ,w4 by ,n41 or ,w4,n4,w4 and ,e4,s4,e41 ridges1 are crossed at right angles by others ranging ,n4,n4,e4 and ,s4,s4,w4 ,the fact of the cleavage-laminae in the clay-slate of ,tierra del ,fuego1 where seen cutting straight through the planes of stratification1 and where consequently there could be no doubt about their nature1 differing slightly in colour1 texture1 and hardness1 appears to me very interesting4 ,in a thick mass of laminated1 feldspathic and altered clay-slate1 interposed between two great strata of porphyritic conglomerate in ,central ,chile1 and where there could be but little doubt about the bedding1 ,i observed similar slight differences in composition1 and likewise some distinct thin layers of epidote1 parallel to the highly inclined cleavage of the mass4 ,again1 ,i incidentally noticed in ,north ,wales1 where glaciers had passed over the truncated edges of the highly inclined laminae of clay-slate1 that the surface1 though smooth1 was worn into small parallel undulations1 caused by the competent laminae being of slightly different degrees of hardness4 78,london ,philosophical ,magazine0 volume #ba page #ahb47 ,with reference to the slates of ,north ,wales1 ,professor ,sedgwick describes the planes of cleavage1 as 8coated over with chlorite and semi-crystalline matter1 which not only merely define the planes in question1 but strike in parallel flakes through the whole mass of the rock40 78,geological ,transactions0 volume #c page #dga47 ,in some of those glossy and hard varieties of clay-slate1 which may often be seen passing into mica-schist1 it has appeared to me that the cleavage- planes were formed of excessively thin1 generally slighted convoluted1 folia1 composed of microscopically minute scales of mica4 ,from these several facts1 and more especially from the case of the clay-slate in ,tierra del ,fuego1 it must1 ,i think1 be concluded1 that the same power which has impressed on the slate its fissile structure or cleavage has tended to modify its mineralogical character in parallel planes4 ,let us now turn to the foliation of the metamorphic schists1 a subject which has been much less attended to4 ,as in the case of cleavage-laminae1 the folia preserve over very large areas a uniform strike3 thus ,humboldt found for a distance of #cjj miles in ,venezuela1 and indeed over a much larger space1 gneiss1 granite1 mica1 and clay-slate1 striking very uniformly ,n4,e4 and ,s4,w41 and dipping at an angle of between #fj and #gj degrees to ,n4,w4 78,personal ,narrative0 volume #f page #ei et seq472 it would even appear from the facts given in this chapter1 that the metamorphic rocks throughout the north-eastern part of ,south ,america are generally foliated within two points of ,n4,e4 and ,s4,w4 ,over the eastern parts of ,banda ,oriental1 the foliation strikes with a high inclination1 very uniformly ,n4,n4,e4 to ,s4,s4,w41 and over the western parts1 in a ,w4 by ,n4 and ,e4 by ,s4 line4 ,for a space of #cjj miles on the shores of the ,chonos and ,chiloe ,islands1 we have seen that the foliation seldom deviates more than a point of the compass from a ,n4 #ai degrees ,w4 and ,s4 #ai degrees ,e4 strike4 ,as in the case of cleavage1 the angle of the dip in foliated rocks is generally high but variable1 and alternates from one side of the line of strike to the other side1 sometimes being vertical3 in the ,northern ,chonos ,islands1 however1 the folia are inclined almost always to the west2 in nearly the same manner1 the cleavage-laminae in ,southern ,tierra del ,fuego certainly dip much more frequently to ,s4,s4,w4 than to the opposite point4 ,in ,eastern ,banda ,oriental1 in parts of ,brazil1 and in some other districts1 the foliation runs in the same direction with the mountain-ranges and adjoining coast-lines3 amongst the ,chonos ,islands1 however1 this coincidence fails1 and ,i have given my reasons for suspecting that one granitic axis has burst through and tilted the already inclined folia of mica-schist3 in the case of cleavage1 the coincidence between its strike and that of the main stratification seems sometimes to fail4 7,cases are given by ,mr4 ,jukes in his 8,geology of ,newfoundland0 page #acj47 ,foliation and cleavage resemble each other in the planes winding round concretions1 and in becoming tortuous where veins of quartz abound4 7,i have seen in ,brazil and ,chile concretions thus enfolded by foliated gneiss2 and ,macculloch 8,highlands0 volume #a page #fd1 has described a similar case4 ,for analogous cases in clay-slate1 see ,professor ,henslow's ,memoir in 8,cambridge ,philosophical ,transactions0 volume #a page #cgi1 and ,macculloch's 8,classification of ,rocks0 page #cea4 ,with respect to both foliation and cleavage becoming tortuous where quartz-veins abound1 ,i have seen instances near ,monte ,video1 at ,concepcion1 and in the ,chonos ,islands4 ,see also ,mr4 ,greenough's 8,critical ,examination0 page #gh47 ,on the flanks of the mountains both in ,tierra del ,fuego and in other countries1 ,i have observed that the cleavage-planes frequently dip at a high angle inwards2 and this was long ago observed by ,von ,buch to be the case in ,norway3 this fact is perhaps analogous to the folded1 fan-like or radiating structure in the metamorphic schists of the ,alps1 in which the folia in the central crests are vertical and on the two flanks inclined inwards4 7,studer in 8,edinburgh ,new ,philosophical ,journal0 volume #bc page #add47 ,where masses of fissile and foliated rocks alternate together1 the cleavage and foliation1 in all cases which ,i have seen1 are parallel4 ,where in one district the rocks are fissile1 and in another adjoining district they are foliated1 the planes of cleavage and foliation are likewise generally parallel3 this is the case with the feldspathic homogeneous slates in the southern part of the ,chonos group1 compared with the fine foliated mica-schists of the northern part2 so again the clay- slate of the whole eastern side of ,tierra del ,fuego cleaves in exactly the same line with the foliated gneiss and mica-slate of the western coast2 other analogous instances might have been adduced4 7,i have given a case in ,australia4 ,see my 8,volcanic ,islands407 ,with respect to the origin of the folia of quartz1 mica1 feldspar1 and other minerals composing the metamorphic schists1 ,professor ,sedgwick1 ,mr4 ,lyell1 and most authors believe1 that the constituent parts of each layer were separately deposited as sediment1 and then metamorphosed4 ,this view1 in the majority of cases1 ,i believe to be quite untenable4 ,in those not uncommon instances1 where a mass of clay-slate1 in approaching granite1 gradually passes into gneiss1 we clearly see that folia of distinct minerals can originate through the metamorphosis of a homogeneous fissile rock4 7,i have described in 8,volcanic ,islands0 a good instance of such a passage at the ,cape of ,good ,hope47 ,the deposition1 it may be remarked1 of numberless alternations of pure quartz1 and of the elements of mica or feldspar does not appear a probable event4 7,see some excellent remarks on this subject1 in ,d',aubuisson's 8,traite de ,geog40 tome #a page #big4 ,also some remarks by ,mr4 ,dana in 8,silliman's ,american ,journal0 volume #de page #ajh47 ,in those districts in which the metamorphic schists are foliated in planes parallel to the cleavage of the rocks in an adjoining district1 are we to believe that the folia are due to sedimentary layers1 whilst the cleavage- laminae1 though parallel1 have no relation whatever to such planes of deposition8 ,on this view1 how can we reconcile the vastness of the areas over which the strike of the foliation is uniform1 with what we see in disturbed districts composed of true strata3 and especially1 how can we understand the high and even vertical dip throughout many wide districts1 which are not mountainous1 and throughout some1 as in ,western ,banda ,oriental1 which are not even hilly8 ,are we to admit that in the northern part of the ,chonos ,archipelago1 mica-slate was first accumulated in parallel horizontal folia to a thickness of about four geographical miles1 and then upturned at an angle of forty degrees2 whilst1 in the southern part of this same ,archipelago1 the cleavage-laminae of closely allied rocks1 which none would imagine had ever been horizontal1 dip at nearly the same angle1 to nearly the same point8 ,seeing1 then1 that foliated schists indisputably are sometimes produced by the metamorphosis of homogeneous fissile rocks2 seeing that foliation and cleavage are so closely analogous in the several above-enumerated respects2 seeing that some fissile and almost homogeneous rocks show incipient mineralogical changes along the planes of their cleavage1 and that other rocks with a fissile structure alternate with1 and pass into varieties with a foliated structure1 ,i cannot doubt that in most cases foliation and cleavage are parts of the same process3 in cleavage there being only an incipient separation of the constituent minerals2 in foliation a much more complete separation and crystallisation4 ,the fact often referred to in this chapter1 of the foliation and the so- called strata in the metamorphic series1--that is1 the alternating masses of different varieties of gneiss1 mica-schist1 and hornblende-slate1 etc41--being parallel to each other1 at first appears quite opposed to the view1 that the folia have no relation to the planes of original deposition4 ,where the so-called beds are not very thick and of widely different mineralogical composition from each other1 ,i do not think that there is any difficulty in supposing that they have originated in an analogous manner with the separate folia4 ,we should bear in mind what thick strata1 in ordinary sedimentary masses1 have obviously been formed by a concretionary process4 ,in a pile of volcanic rocks on the ,island of ,ascension1 there are strata1 differing quite as much in appearance as the ordinary varieties of the metamorphic schists1 which undoubtedly have been produced1 not by successive flowings of lava1 but by internal molecular changes4 ,near ,monte ,video1 where the stratification1 as it would be called1 of the metamorphic series is1 in most parts1 particularly well developed1 being as usual1 parallel to the foliation1 we have seen that a mass of chloritic schist1 netted with quartz-veins1 is entangled in gneiss1 in such a manner as to show that it had certainly originated in some process of segregation3 again1 in another spot1 the gneiss tended to pass into hornblendic schist by alternating with layers of quartz2 but these layers of quartz almost certainly had never been separately deposited1 for they were absolutely continuous with the numerous intersecting veins of quartz4 ,i have never had an opportunity of tracing for any distance1 along the line both of strike and of dip1 the so-called beds in the metamorphic schists1 but ,i strongly suspect that they would not be found to extend with the same character1 very far in the line either of their dip or strike4 ,hence ,i am led to believe1 that most of the so-called beds are of the nature of complex folia1 and have not been separately deposited4 ,of course1 this view cannot be extended to ,,thick masses included in the metamorphic series1 which are of totally different composition from the adjoining schists1 and which are far extended1 as is sometimes the case with quartz and marble2 these must generally be of the nature of true strata4 7,macculloch 8,classification of ,rocks0 page #cfd1 states that primary limestones are often found in irregular masses or great nodules1 8which can scarcely be said to possess a stratified shape607 ,such strata1 however1 will almost always strike in the same direction with the folia1 owing to the axes of elevation being in most countries parallel to the strike of the foliation2 but they will generally dip at a different angle from that of the foliation2 and the angle of the foliation in itself almost always varies much3 hence1 in crossing a metamorphosed schistose district1 it would require especial attention to discriminate between true strata of deposition and complex foliated masses4 ,the mere presence of true strata in the midst of a set of metamorphic schists1 is no argument that the foliation is of sedimentary origin1 without it be further shown in each case1 that the folia not only strike1 but dip throughout in parallel planes with those of the true stratification4 ,as in some cases it appears that where a fissile rock has been exposed to partial metamorphic action1 for instance from the irruption of granite1 the foliation has supervened on the already existing cleavage-planes2 so perhaps in some instances1 the foliation of a rock may have been determined by the original planes of deposition or of oblique current-laminae3 ,i have1 however1 myself1 never seen such a case1 and ,i must maintain that in most extensive metamorphic areas1 the foliation is the extreme result of that process1 of which cleavage is the first effect4 ,that foliation may arise without any previous structural arrangement in the mass1 we may infer from injected1 and therefore once liquified1 rocks1 both of volcanic and plutonic origin1 sometimes having a 8grain0 7as expressed by ,professor ,sedgwick71 and sometimes being composed of distinct folia or laminae of different compositions4 ,in my work on 8,volcanic ,islands10 ,i have given several instances of this structure in volcanic rocks1 and it is not uncommonly seen in plutonic masses--thus1 in the ,cordillera of ,chile1 there are gigantic mountain-like masses of red granite1 which have been injected whilst liquified1 and which1 nevertheless1 display in parts a decidedly laminar structure4 7,as remarked in a former part of this chapter1 ,i suspect that the boldly conical mountains of gneiss-granite1 near ,rio de ,janeiro1 in which the constituent minerals are arranged in parallel planes1 are of intrusive origin4 ,we must not1 however1 forget the lesson of caution taught by the curious claystone porphyries of ,port ,desire1 in which we have seen that the breaking up and aggregation of a thinly stratified tufaceous mass1 has yielded a rock semi-porphyritic with crystals of feldspar1 arranged in the planes of original deposition47 ,finally1 we have seen that the planes of cleavage and of foliation1 that is1 of the incipient process and of the final result1 generally strike parallel to the principal axes of elevation1 and to the outline of the land3 the strike of the axes of elevation 7that is1 of the lines of fissures with the strata on their edges upturned71 according to the reasoning of ,mr4 ,hopkins1 is determined by the form of the area undergoing changes of level1 and the consequent direction of the lines of tension and fissure4 ,now1 in that remarkable pile of volcanic rocks at ,ascension1 which has several times been alluded to 7and in some other cases71 ,i have endeavoured to show1 that the lamination of the several varieties1 and their alternations1 have been caused by the moving mass1 just before its final consolidation1 having been subjected 7as in a glacier7 to planes of different tension2 this difference in the tension affecting the crystalline and concretionary processes4 7,in 8,volcanic ,islands407 ,one of the varieties of rock thus produced at ,ascension1 at first sight1 singularly resembles a fine-grained gneiss2 it consists of quite straight and parallel zones of excessive tenuity1 of more or less coloured crystallised feldspar1 of distinct crystals of quartz1 diopside1 and oxide of iron4 ,these considerations1 notwithstanding the experiments made by ,mr4 ,fox1 showing the influence of electrical currents in producing a structure like that of cleavage1 and notwithstanding the apparently inexplicable variation1 both in the inclination of the cleavage-laminae and in their dipping first to one side and then to the other side of the line of strike1 lead me to suspect that the planes of cleavage and foliation are intimately connected with the planes of different tension1 to which the area was long subjected1 ,,after the main fissures or axes of upheavement had been formed1 but ,,before the final consolidation of the mass and the total cessation of all molecular movement4 ,,chapter ,,vii4 ,,central ,,chile3--,,structure ,,of ,,the ,,cordillera4 ,central ,chile4--,basal formations of the ,cordillera4--,origin of the porphyritic clay-stone conglomerate4--,andesite4--,volcanic rocks4--,section of the ,cordillera by the ,peuquenes are ,portillo ,pass4--,great gypseous formation4--,peuquenes line2 thickness of strata1 fossils of4--,portillo line4--,conglomerate1 orthitic granite1 mica-schist1 volcanic rocks of4--,concluding remarks on the denudation and elevation of the ,portillo line4--,section by the ,cumbre1 or ,uspallata ,pass4--,porphyries4--,gypseous strata4--,section near the ,puente del ,inca2 fossils of4--,great subsidence4--,intrusive porphyries4--,plain of ,uspallata4--,section of the ,uspallata chain4--,structure and nature of the strata4--,silicified vertical trees4--,great subsidence4--,granitic rocks of axis4--,concluding remarks on the ,uspallata range2 origin subsequent to that of the main ,cordillera2 two periods of subsidence2 comparison with the ,portillo chain4-- ,the district between the ,cordillera and the ,pacific1 on a rude average1 is from about eighty to one hundred miles in width4 ,it is crossed by many chains of mountains1 of which the principal ones1 in the latitude of ,valparaiso and southward of it1 range nearly north and south2 but in the more northern parts of the province1 they run in almost every possible direction4 ,near the ,pacific1 the mountain-ranges are generally formed of syenite or granite1 and or of an allied euritic porphyry2 in the low country1 besides these granitic rocks and greenstone1 and much gneiss1 there are1 especially northward of ,valparaiso1 some considerable districts of true clay-slate with quartz veins1 passing into a feldspathic and porphyritic slate2 there is also some grauwacke and quartzose and jaspery rocks1 the latter occasionally assuming the character of the basis of claystone porphyry3 trap-dikes are numerous4 ,nearer the ,cordillera the ranges 7such as those of ,s4 ,fernando1 the ,prado 7,meyen 8,reise um ,erde0 th4 #a s4 #bce471 and ,aconcagua7 are formed partly of granitic rocks1 and partly of purple porphyritic conglomerates1 claystone porphyry1 greenstone porphyry1 and other rocks1 such as we shall immediately see1 form the basal strata of the main ,cordillera4 ,in the more northern parts of ,chile1 this porphyritic series extends over large tracts of country far from the ,cordillera2 and even in ,central ,chile such occasionally occur in outlying positions4 ,i will describe the ,campana of ,quillota1 which stands only fifteen miles from the ,pacific1 as an instance of one of these outlying masses4 ,this hill is conspicuous from rising to the height of #f1djj feet3 its summit shows a nucleus1 uncovered for a height of #hjj feet1 of fine greenstone1 including epidote and octahedral magnetic iron ore2 its flanks are formed of great strata of porphyritic claystone conglomerate associated with various true porphyries and amygdaloids1 alternating with thick masses of a highly feldspathic1 sometimes porphyritic1 pale-coloured slaty rock1 with its cleavage-laminae dipping inwards at a high angle4 ,at the base of the hill there are syenites1 a granular mixture of quartz and feldspar1 and harsh quartzose rocks1 all belonging to the basal metamorphic series4 ,i may observe that at the foot of several hills of this class1 where the porphyries are first seen 7as near ,s4 ,fernando1 the ,prado1 ,las ,vacas1 etc471 similar harsh quartzose rocks and granular mixtures of quartz and feldspar occur1 as if the more fusible constituent parts of the granitic series had been drawn off to form the overlying porphyries4 ,in ,central ,chile1 the flanks of the main ,cordillera1 into which ,i penetrated by four different valleys1 generally consist of distinctly stratified rocks4 ,the strata are inclined at angles varying from sometimes even under ten1 to twenty degrees1 very rarely exceeding forty degrees3 in some1 however1 of the quite small1 exterior1 spur-like ridges1 the inclination was not unfrequently greater4 ,the dip of the strata in the main outer lines was usually outwards or from the ,cordillera1 but in ,northern ,chile frequently inwards1--that is1 their basset-edges fronted the ,pacific4 ,dikes occur in extraordinary numbers4 ,in the great1 central1 loftiest ridges1 the strata1 as we shall presently see1 are almost always highly inclined and often vertical4 ,before giving a detailed account of my two sections across the ,cordillera1 it will1 ,i think1 be convenient to describe the basal strata as seen1 often to a thickness of four or five thousand feet1 on the flanks of the outer lines4 ,,basal ,,strata ,,of ,,the ,,cordillera4 ,the prevailing rock is a purplish or greenish1 porphyritic claystone conglomerate4 ,the embedded fragments vary in size from mere particles to blocks as much as six or eight inches 7rarely more7 in diameter2 in many places1 where the fragments were minute1 the signs of aqueous deposition were unequivocally distinct2 where they were large1 such evidence could rarely be detected4 ,the basis is generally porphyritic with perfect crystals of feldspar1 and resembles that of a true injected claystone porphyry3 often1 however1 it has a mechanical or sedimentary aspect1 and sometimes 7as at ,jajuel7 is jaspery4 ,the included fragments are either angular1 or partially or quite rounded 7,some of the rounded fragments in the porphyritic conglomerate near the ,baths of ,cauquenes1 were marked with radii and concentric zones of different shades of colour3 any one who did not know that pebbles1 for instance flint pebbles from the chalk1 are sometimes zoned concentrically with their worn and rounded surfaces1 might have been led to infer1 that these balls of porphyry were not true pebbles1 but had originated in concretionary action472 in some parts the rounded1 in others the angular fragments prevail1 and usually both kinds are mixed together3 hence the word ,,breccia ought strictly to be appended to the term ,,porphyritic ,,conglomerate4 ,the fragments consist of many varieties of claystone porphyry1 usually of nearly the same colour with the surrounding basis1 namely1 purplish-reddish1 brownish1 mottled or bright green2 occasionally fragments of a laminated1 pale-coloured1 feldspathic rock1 like altered clay-slate are included2 as are sometimes grains of quartz1 but only in one instance in ,central ,chile 7namely1 at the mines of ,jajuel7 a few pebbles of quartz4 ,i nowhere observed mica in this formation1 and rarely hornblende2 where the latter mineral did occur1 ,i was generally in doubt whether the mass really belonged to this formation1 or was of intrusive origin4 ,calcareous spar occasionally occurs in small cavities2 and nests and layers of epidote are common4 ,in some few places in the finer-grained varieties 7for instance1 at ,quillota71 there were short1 interrupted layers of earthy feldspar1 which could be traced1 exactly as at ,port ,desire1 passing into large crystals of feldspar3 ,i doubt1 however1 whether in this instance the layers had ever been separately deposited as tufaceous sediment4 ,all the varieties of porphyritic conglomerates and breccias pass into each other1 and by innumerable gradations into porphyries no longer retaining the least trace of mechanical origin3 the transition appears to have been effected much more easily in the finer-grained1 than in the coarser-grained varieties4 ,in one instance1 near ,cauquenes1 ,i noticed that a porphyritic conglomerate assumed a spheroidal structure1 and tended to become columnar4 ,besides the porphyritic conglomerates and the perfectly characterised porphyries1 of metamorphic origin1 there are other porphyries1 which1 though differing not at all or only slightly in composition1 certainly have had a different origin3 these consist of pink or purple claystone porphyries1 sometimes including grains of quartz1--of greenstone porphyry1 and of other dusky rocks1 all generally porphyritic with fine1 large1 tabular1 opaque crystals1 often placed crosswise1 of feldspar cleaving like albite 7judging from several measurements71 and often amygdaloidal with silex1 agate1 carbonate of lime1 green and brown bole4 7,this bole is a very common mineral in the amygdaloidal rocks2 it is generally of a greenish- brown colour1 with a radiating structure2 externally it is black with an almost metallic lustre1 but often coated by a bright green film4 ,it is soft and can be scratched by a quill2 under the blowpipe swells greatly and becomes scaly1 then fuses easily into a black magnetic bead4 ,this substance is evidently similar to that which often occurs in submarine volcanic rocks4 ,an examination of some very curious specimens of a fine porphyry 7from ,jajuel7 leads me to suspect that some of these amygdaloidal balls1 instead of having been deposited in pre-existing air-vesicles1 are of concretionary origin2 for in these specimens1 some of the pea-shaped little masses 7often externally marked with minute pits7 are formed of a mixture of green earth with stony matter1 like the basis of the porphyry1 including minute imperfect crystals of feldspar2 and these pea-shaped little masses are themselves amygdaloidal with minute spheres of the green earth1 each enveloped by a film of white1 apparently feldspathic1 earthy matter3 so that the porphyry is doubly amygdaloidal4 ,it should not1 however1 be overlooked1 that all the strata here have undergone metamorphic action1 which may have caused crystals of feldspar to appear1 and other changes to be effected1 in the originally simple amygdaloidal balls4 ,mr4 ,j4,d4 ,dana1 in an excellent paper on ,trap-rocks 8,edinburgh ,new ,philosophical ,journal0 volume #da page #aih1 has argued with great force1 that all amygdaloidal minerals have been deposited by aqueous infiltration4 ,i may take this opportunity of alluding to a curious case1 described in my work on 8,volcanic ,islands10 of an amygdaloid with many of its cells only half filled up with a mesotypic mineral4 ,m4 ,rose has described an amygdaloid1 brought by ,dr4 ,meyen 8,reise um ,erde0 ,th4 #a4 s4 #caf1 from ,chile1 as consisting of crystallised quartz1 with crystals of stilbite within1 and lined externally by green earth47 ,these several porphyritic and amygdaloidal varieties never show any signs of passing into masses of sedimentary origin3 they occur both in great and small intrusive masses1 and likewise in strata alternating with those of the porphyritic conglomerate1 and with the planes of junction often quite distinct1 yet not seldom blended together4 ,in some of these intrusive masses1 the porphyries exhibit1 more or less plainly1 a brecciated structure1 like that often seen in volcanic masses4 ,these brecciated porphyries could generally be distinguished at once from the metamorphosed1 porphyritic breccia- conglomerates1 by all the fragments being angular and being formed of the same variety1 and by the absence of every trace of aqueous deposition4 ,one of the porphyries above specified1 namely1 the greenstone porphyry with large tabular crystals of albite1 is particularly abundant1 and in some parts of the ,cordillera 7as near ,st4 ,jago7 seemed more common even than the purplish porphyritic conglomerate4 ,numerous dikes likewise consist of this greenstone porphyry2 others are formed of various fine-grained trappean rocks2 but very few of claystone porphyry3 ,i saw no true basaltic dikes4 ,in several places in the lower part of the series1 but not everywhere1 thick masses of a highly feldspathic1 often porphyritic1 slaty rock occur interstratified with the porphyritic conglomerate2 ,i believe in one or two cases blackish limestone has been found in a similar position4 ,the feldspathic rock is of a pale grey or greenish colour2 it is easily fusible2 where porphyritic1 the crystals of feldspar are generally small and vitreous3 it is distinctly laminated1 and sometimes includes parallel layers of epidote 7,this mineral is extremely common in all the formations of ,chile2 in the gneiss near ,valparaiso and in the granitic veins crossing it1 in the injected greenstone crowning the ,c4 of ,quillota1 in some granitic porphyries1 in the porphyritic conglomerate1 and in the feldspathic clay-slates472 the lamination appears to be distinct from stratification4 ,occasionally this rock is somewhat curious2 and at one spot1 namely1 at the ,c4 of ,quillota1 it had a brecciated structure4 ,near the mines of ,jajuel1 in a thick stratum of this feldspathic1 porphyritic slate1 there was a layer of hard1 blackish1 siliceous1 infusible1 compact clay-slate1 such as ,i saw nowhere else2 at the same place ,i was able to follow for a considerable distance the junction between the slate and the conformably underlying porphyritic conglomerate1 and they certainly passed gradually into each other4 ,wherever these slaty feldspathic rocks abound1 greenstone seems common2 at the ,c4 of ,quillota a bed of well-crystallised greenstone lay conformably in the midst of the feldspathic slate1 with the upper and lower junctions passing insensibly into it4 ,from this point1 and from the frequently porphyritic condition of the slate1 ,i should perhaps have considered this rock as an erupted one 7like certain laminated feldspathic lavas in the trachytic series71 had ,i not seen in ,tierra del ,fuego how readily true clay-slate becomes feldspathic and porphyritic1 and had ,i not seen at ,jajuel the included layer of black1 siliceous clay-slate1 which no one could have thought of igneous origin4 ,the gentle passage of the feldspathic slate1 at ,jajuel1 into the porphyritic conglomerate1 which is certainly of aqueous origin1 should also be taken in account4 ,the alternating strata of porphyries and porphyritic conglomerate1 and with the occasionally included beds of feldspathic slate1 together make a grand formation2 in several places within the ,cordillera1 ,i estimated its thickness at from six to seven thousand feet4 ,it extends for many hundred miles1 forming the western flank of the ,chilean ,cordillera2 and even at ,iquique in ,peru1 #hej miles north of the southernmost point examined by me in ,chile1 the coast-escarpment which rises to a height of between two and three thousand feet is thus composed4 ,in several parts of ,northern ,chile this formation extends much further towards the ,pacific1 over the granitic and metamorphic lower rocks1 than it does in ,central ,chile2 but the main ,cordillera may be considered as its central line1 and its breadth in an east and west direction is never great4 ,at first the origin of this thick1 massive1 long but narrow formation1 appeared to me very anomalous3 whence were derived1 and how were dispersed the innumerable fragments1 often of large size1 sometimes angular and sometimes rounded1 and almost invariably composed of porphyritic rocks8 ,seeing that the interstratified porphyries are never vesicular and often not even amygdaloidal1 we must conclude that the pile was formed in deep water2 how then came so many fragments to be well rounded and so many to remain angular1 sometimes the two kinds being equally mingled1 sometimes one and sometimes the other preponderating8 ,that the claystone1 greenstone1 and other porphyries and amygdaloids1 which lie ,,conformably between the beds of conglomerate1 are ancient submarine lavas1 ,i think there can be no doubt2 and ,i believe we must look to the craters whence these streams were erupted1 as the source of the breccia- conglomerate2 after the great explosion1 we may fairly imagine that the water in the heated and scarcely quiescent crater would remain for a considerable time sufficiently agitated to triturate and round the loose fragments1 few or many in number1 would be shot forth at the next eruption1 associated with few or many angular fragments1 according to the strength of the explosion4 7,this certainly seems to have taken place in some recent volcanic archipelagos1 as at the ,galapagos1 where numerous craters are exclusively formed of tuff and fragments of lava47 ,the porphyritic conglomerate being purple or reddish1 even when alternating with dusty- coloured or bright green porphyries and amygdaloids1 is probably an analogous circumstance to the scoriae of the blackish basalts being often bright red4 ,the ancient submarine orifices whence the porphyries and their fragments were ejected having been arranged in a band1 like most still active volcanoes1 accounts for the thickness1 the narrowness1 and linear extension of this formation4 ,this whole great pile of rock has suffered much metamorphic action1 as is very obvious in the gradual formation and appearance of the crystals of albitic feldspar and of epidote--in the bending together of the fragments-- in the appearance of a laminated structure in the feldspathic slate--and1 lastly1 in the disappearance of the planes of stratification1 which could sometimes be seen on the same mountain quite distinct in the upper part1 less and less plain on the flanks1 and quite obliterated at the base4 ,partly owing to this metamorphic action1 and partly to the close relationship in origin1 ,i have seen fragments of porphyries--taken from a metamorphosed conglomerate--from a neighbouring stream of lava--from the nucleus or centre 7as it appeared to me7 of the whole submarine volcano-- and lastly from an intrusive mass of quite subsequent origin1 all of which were absolutely undistinguishable in external characters4 ,one other rock1 of plutonic origin1 and highly important in the history of the ,cordillera1 from having been injected in most of the great axes of elevation1 and from having apparently been instrumental in metamorphosing the superincumbent strata1 may be conveniently described in this preliminary discussion4 ,it has been called by some authors ,,andesite3 it mainly consists of well-crystallised white albite 7as determined with the goniometer in numerous specimens both by ,professor ,miller and myself71 of less perfectly crystallised green hornblende1 often associated with much mica1 with chlorite and epidote1 and occasionally with a few grains of quartz3 in one instance in ,northern ,chile1 ,i found crystals of orthitic or potash feldspar1 mingled with those of albite4 7,i here1 and elsewhere1 call by this name1 those feldspathic minerals which cleave like albite3 but it now appears 78,edinburgh ,new ,philosophical ,journal0 volume #bd page #aha7 that ,abich has analysed a mineral from the ,cordillera1 associated with hornblende and quartz 7probably the same rock with that here under discussion71 which cleaves like albite1 but which is a new and distinct kind1 called by him ,,andesine4 ,it is allied to leucite1 with the greater proportion of its potash replaced by lime and soda4 ,this mineral seems scarcely distinguishable from albite1 except by analysis47 ,where the mica and quartz are abundant1 the rock cannot be distinguished from granite2 and it may be called andesitic granite4 ,where these two minerals are quite absent1 and when1 as often then happens1 the crystals of albite are imperfect and blend together1 the rock may be called andesitic porphyry1 which bears nearly the same relation to andesitic granite that euritic porphyry does to common granite4 ,these andesitic rocks form mountain masses of a white colour1 which1 in their general outline and appearance--in their joints--in their occasionally including dark-coloured1 angular fragments1 apparently of some pre-existing rock--and in the great dikes branching from them into the superincumbent strata1 manifest a close and striking resemblance to masses of common granite and syenite3 ,i never1 however1 saw in these andesitic rocks1 those granitic veins of segregation which are so common in true granites4 ,we have seen that andesite occurs in three places in ,tierra del ,fuego2 in ,chile1 from ,s4 ,fernando to ,copiapo1 a distance of #dej miles1 ,i found it under most of the axes of elevation2 in a collection of specimens from the ,cordillera of ,lima in ,peru1 ,i immediately recognised it2 and ,erman states that it occurs in ,eastern ,kamtschatka4 78,geographical ,journal0 volume #i page #eaj47 ,from its wide range1 and from the important part it has played in the history of the ,cordillera1 ,i think this rock has well deserved its distinct name of ,andesite4 ,the few still active volcanoes in ,chile are confined to the central and loftiest ranges of the ,cordillera2 and volcanic matter1 such as appears to have been of subaerial eruption1 is everywhere rare4 ,according to ,meyen1 there is a hill of pumice high up the valley of the ,maypu1 and likewise a trachytic formation at ,colina1 a village situated north of ,st4 ,jago4 78,reise um ,erde0 ,th4 #a ss4 #cch and #cfb47 ,close to this latter city1 there are two hills formed of a pale feldspathic porphyry1 remarkable from being doubly columnar1 great cylindrical columns being subdivided into smaller four- or five-sided ones2 and a third hillock 7,cerro ,blanco7 is formed of a fragmentary mass of rock1 which ,i believed to be of volcanic origin1 intermediate in character between the above feldspathic porphyry and common trachyte1 and containing needles of hornblende and granular oxide of iron4 ,near the ,baths of ,cauquenes1 between two short parallel lines of elevation1 where they are intersected by the valley1 there is a small1 though distinct volcanic district2 the rock is a dark grey 7andesitic7 trachyte1 which fuses into a greenish-grey bead1 and is formed of long crystals of fractured glassy albite 7judging from one measurement7 mingled with well- formed crystals1 often twin1 of augite4 ,the whole mass is vesicular1 but the surface is darker coloured and much more vesicular than any other part4 ,this trachyte forms a cliff-bounded1 horizontal1 narrow strip on the steep southern side of the valley1 at the height of four or five hundred feet above the river-bed2 judging from an apparently corresponding line of cliff on the northern side1 the valley must once have been filled up to this height by a field of lava4 ,on the summit of a lofty mountain some leagues higher up this same valley of the ,cachapual1 ,i found columnar pitchstone porphyritic with feldspar2 ,i do not suppose this rock to be of volcanic origin1 and only mention it here1 from its being intersected by masses and dikes of a ,,vesicular rock1 approaching in character to trachyte2 in no other part of ,chile did ,i observe vesicular or amygdaloidal dikes1 though these are so common in ordinary volcanic districts4 ,,passage ,,of ,,the ,,andes ,,by ,,the ,,portillo ,,or ,,pequenes ,,pass4 ,although ,i crossed the ,cordillera only once by this pass1 and only once by that of the ,cumbre or ,uspallata 7presently to be described71 riding slowly and halting occasionally to ascend the mountains1 there are many circumstances favourable to obtaining a more faithful sketch of their structure than would at first be thought possible from so short an examination4 ,the mountains are steep and absolutely bare of vegetation2 the atmosphere is resplendently clear2 the stratification distinct2 and the rocks brightly and variously coloured3 some of the natural sections might be truly compared for distinctness to those coloured ones in geological works4 ,considering how little is known of the structure of this gigantic range1 to which ,i particularly attended1 most travellers having collected only specimens of the rocks1 ,i think my sketch-sections1 though necessarily imperfect1 possess some interest4 ,section #a_/a in ,plate #a which ,i will now describe in detail1 is on a horizontal scale of a third of an inch to a nautical mile1 and on a vertical scale of one inch to a mile 7or #f1jjj feet74 ,the width of the range 7excluding a few outlying hillocks71 from the plain on which ,st4 ,jago the capital of ,chile stands1 to the ,pampas1 is sixty miles1 as far as ,i can judge from the maps1 which differ from each other and are all ,,exceedingly imperfect4 ,the ,st4 ,jago plain at the mouth of the ,maypu1 ,i estimate from adjoining known points at #b1cjj feet1 and the ,pampas at #c1ejj feet1 both above the level of the sea4 ,the height of the ,pequenes line1 according to ,dr4 ,gillies1 is #ac1baj feet 78,journal of ,natural and ,geographical ,science0 ,august #ahcj472 and that of the ,portillo line 7both in the gaps where the road crosses them7 is #ad1cde feet2 the lowest part of the intermediate valley of ,tenuyan is #g1ecj feet--all above the level of the sea4 ,the ,cordillera here1 and indeed ,i believe throughout ,chile1 consist of several parallel1 anticlinal and uniclinal mountain-lines1 ranging north1 or north with a little westing1 and south4 ,some exterior and much lower ridges often vary considerably from this course1 projecting like oblique spurs from the main ranges3 in the district towards the ,pacific1 the mountains1 as before remarked1 extend in various directions1 even east and west4 ,in the main exterior lines1 the strata1 as also before remarked1 are seldom inclined at a high angle2 but in the central lofty ridges they are almost always highly inclined1 broken by many great faults1 and often vertical4 ,as far as ,i could judge1 few of the ranges are of great length3 and in the central parts of the ,cordillera1 ,i was frequently able to follow with my eye a ridge gradually becoming higher and higher1 as the stratification increased in inclination1 from one end where its height was trifling and its strata gently inclined to the other end where vertical strata formed snow-clad pinnacles4 ,even outside the main ,cordillera1 near the baths of ,cauquenes1 ,i observed one such case1 where a north and south ridge had its strata in the valley inclined at #cg degrees1 and less than a mile south of it at #fg degrees3 another parallel and similarly inclined ridge rose at the distance of about five miles1 into a lofty mountain with absolutely vertical strata4 ,within the ,cordillera1 the height of the ridges and the inclination of the strata often became doubled and trebled in much shorter distances than five miles2 this peculiar form of upheaval probably indicates that the stratified crust was thin1 and hence yielded to the underlying intrusive masses unequally1 at certain points on the lines of fissure4 ,the valleys1 by which the ,cordillera are drained1 follow the anticlinal or rarely synclinal troughs1 which deviate most from the usual north and south course2 or still more commonly those lines of faults or of unequal curvature 7that is1 lines with the strata on both hands dipping in the same direction1 but at a somewhat different angle7 which deviate most from a northerly course4 ,occasionally the torrents run for some distance in the north and south valleys1 and then recover their eastern or western course by bursting through the ranges at those points where the strata have been least inclined and the height consequently is less4 ,hence the valleys1 along which the roads run1 are generally zigzag2 and1 in drawing an east and west section1 it is necessary to contract greatly that which is actually seen on the road4 ,commencing at the western end of ,section #a_/a where the ,r4 ,maypu debouches on the plain of ,st4 ,jago1 we immediately enter on the porphyritic conglomerate formation1 and in the midst of it find some hummocks ,a of granite and syenite1 which probably 7for ,i neglected to collect specimens7 belong to the andesitic class4 ,these are succeeded by some rugged hills ,b of dark-green1 crystalline1 feldspathic and in some parts slaty rocks1 which ,i believe belong to the altered clay-slate formation4 ,from this point1 great mountains of purplish and greenish1 generally thinly stratified1 highly porphyritic conglomerates1 including many strata of amygdaloidal and greenstone porphyries1 extend up the valley to the junction of the rivers ,yeso and ,volcan4 ,as the valley here runs in a very southerly course1 the width of the porphyritic conglomerate formation is quite conjectural2 and from the same cause1 ,i was unable to make out much about the stratification4 ,in most of the exterior mountains the dip was gentle and directed inwards2 and at only one spot ,i observed an inclination as high as #ej degrees4 ,near the junction of the ,r4 ,colorado with the main stream1 there is a hill of whitish1 brecciated1 partially decomposed feldspathic porphyry1 having a volcanic aspect but not being really of that nature3 at ,tolla1 however1 in this valley1 ,dr4 ,meyen met with a hill of pumice containing mica4 78,reise um ,erde0 ,th4#a ss4 #cch1 #cda47 ,at the junction of the ,yeso and ,volcan ,d there is an extensive mass1 in white conical hillocks1 of andesite1 containing some mica1 and passing either into andesitic granite1 or into a spotted1 semi-granular mixture of albitic 787 feldspar and hornblende3 in the midst of this formation ,dr4 ,meyen found true trachyte4 ,the andesite is covered by strata of dark-coloured1 crystalline1 obscurely porphyritic rocks1 and above them by the ordinary porphyritic conglomerates1--the strata all dipping away at a small angle from the underlying mass4 ,the surrounding lofty mountains appear to be entirely composed of the porphyritic conglomerate1 and ,i estimated its thickness here at between six and seven thousand feet4 ,beyond the junction of the ,yeso and ,volcan1 the porphyritic strata appear to dip towards the hillocks of andesite at an angle of #dj degrees2 but at some distant points on the same ridge they are bent up and vertical4 ,following the valley of the ,yeso1 trending ,n4,e4 7and therefore still unfavourable for our transverse section71 the same porphyritic conglomerate formation is prolonged to near the ,cuestadel ,indio1 situated at the western end of the basin 7like a drained lake7 of ,yeso4 ,some way before arriving at this point1 distant lofty pinnacles capped by coloured strata belonging to the great gypseous formation could first be seen4 ,from the summit of the ,cuesta1 looking southward1 there is a magnificent sectional view of a mountain-mass1 at least #b1jjj feet in thickness ,e1 of fine andesite granite 7containing much black mica1 a little chlorite and quartz71 which sends great white dikes far into the superincumbent1 dark-coloured1 porphyritic conglomerates4 ,at the line of junction the two formations are wonderfully interlaced together3 in the lower part of the porphyritic conglomerate1 the stratification has been quite obliterated1 whilst in the upper part it is very distinct1 the beds composing the crests of the surrounding mountains being inclined at angles of between #gj and #hj degrees1 and some being even vertical4 ,on the northern side of the valley1 there is a great corresponding mass of andesitic granite1 which is encased by porphyritic conglomerate1 dipping both on the western and eastern sides1 at about #hj degrees to west1 but on the eastern side with the tips of the strata bent in such a manner1 as to render it probable that the whole mass has been on that side thrown over and inverted4 ,in the valley basin of the ,yeso1 which ,i estimated at #g1jjj feet above the level of the sea1 we first reach at ,f the gypseous formation4 ,its thickness is very great4 ,it consists in most parts of snow-white1 hard1 compact gypsum1 which breaks with a saccharine fracture1 having translucent edges2 under the blowpipe gives out much vapour2 it frequently includes nests and exceedingly thin layers of crystallised1 blackish carbonate of lime4 ,large1 irregularly shaped concretions 7externally still exhibiting lines of aqueous deposition7 of blackish-grey1 but sometimes white1 coarsely and brilliantly crystallised1 hard anhydrite1 abound within the common gypsum4 ,hillocks1 formed of the hardest and purest varieties of the white gypsum1 stand up above the surrounding parts1 and have their surfaces cracked and marked1 just like newly baked bread4 ,there is much pale brown1 soft argillaceous gypsum2 and there were some intercalated green beds which ,i had not time to reach4 ,i saw only one fragment of selenite or transparent gypsum1 and that perhaps may have come from some subsequently formed vein4 ,from the mineralogical characters here given1 it is probable that these gypseous beds have undergone some metamorphic action4 ,the strata are much hidden by detritus1 but they appeared in most parts to be highly inclined2 and in an adjoining lofty pinnacle they could be distinctly seen bending up1 and becoming vertical1 conformably with the underlying porphyritic conglomerate4 ,in very many parts of the great mountain-face ,f1 composed of thin gypseous beds1 there were innumerable masses1 irregularly shaped and not like dikes1 yet with well-defined edges1 of an imperfectly granular1 pale greenish1 or yellowish-white rock1 essentially composed of feldspar1 with a little chlorite or hornblende1 epidote1 iron-pyrites1 and ferruginous powder3 ,i believe that these curious trappean masses have been injected from the not far distant mountain-mass ,e of andesite whilst still fluid1 and that owing to the softness of the gypseous strata they have not acquired the ordinary forms of dikes4 ,subsequently to the injection of these feldspathic rocks1 a great dislocation has taken place2 and the much shattered gypseous strata here overlie a hillock ,g1 composed of vertical strata of impure limestone and of black highly calcareous shale including threads of gypsum3 these rocks1 as we shall presently see1 belong to the upper parts of the gypseous series1 and hence must here have been thrown down by a vast fault4 ,proceeding up the valley-basin of the ,yeso1 and taking our section sometimes on one hand and sometimes on the other1 we come to a great hill of stratified porphyritic conglomerate ,h dipping at #de degrees to the west2 and a few hundred yards farther on1 we have a bed between three or four hundred feet thick of gypsum ,i dipping eastward at a very high angle3 here then we have a fault and anticlinal axis4 ,on the opposite side of the valley1 a vertical mass of red conglomerate1 conformably underlying the gypsum1 appears gradually to lose its stratification and passes into a mountain of porphyry4 ,the gypsum ,i is covered by a bed ,k1 at least #a1jjj feet in thickness1 of a purplish-red1 compact1 heavy1 fine-grained sandstone or mudstone1 which fuses easily into a white enamel1 and is seen under a lens to contain triturated crystals4 ,this is succeeded by a bed ,l1 #a1jjj feet thick 7,i believe ,i understate the thickness7 of gypsum1 exactly like the beds before described2 and this again is capped by another great bed ,m of purplish-red sandstone4 ,all these strata dip eastward2 but the inclination becomes less and less1 as we leave the first and almost vertical bed ,i of gypsum4 ,leaving the basin-plain of ,yeso1 the road rapidly ascends1 passing by mountains composed of the gypseous and associated beds1 with their stratification greatly disturbed and therefore not easily intelligible3 hence this part of the section has been left uncoloured4 ,shortly before reaching the great ,pequenes ridge1 the lowest stratum visible ,n is a red sandstone or mudstone1 capped by a vast thickness of black1 compact1 calcareous1 shaly rock ,o1 which has been thrown into four lofty1 though small ridges3 looking northward1 the strata in these ridges are seen gradually to rise in inclination1 becoming in some distant pinnacles absolutely vertical4 ,the ridge of ,pequenes1 which divides the waters flowing into the ,pacific and ,atlantic ,oceans1 extends in a nearly ,n4,n4,w4 and ,s4,s4,e4 line2 its strata dip eastward at an angle of between #cj and #de degrees1 but in the higher peaks bending up and becoming almost vertical4 ,where the road crosses this range1 the height is #ac1baj feet above the sea-level1 and ,i estimated the neighbouring pinnacles at from fourteen to fifteen thousand feet4 ,the lowest stratum visible in this ridge is a red stratified sandstone ,p2 on it are superimposed two great masses ,q and ,s of black1 hard1 compact1 even having a conchoidal fracture1 calcareous1 more or less laminated shale1 passing into limestone3 this rock contains organic remains1 presently to be enumerated4 ,the compacter varieties fuse easily in a white glass2 and this ,i may add is a very general character with all the sedimentary beds in the ,cordillera3 although this rock when broken is generally quite black1 it everywhere weathers into an ash-grey tint4 ,between these two great masses ,q and ,s1 a bed ,r of gypsum is interposed1 about three hundred feet in thickness1 and having the same characters as heretofore described4 ,i estimated the total thickness of these three beds ,q1 ,r1 ,s at nearly three thousand feet2 and to this must be added1 as will be immediately seen1 a great overlying mass of red sandstone4 ,in descending the eastern slope of this great central range1 the strata1 which in the upper part dip eastward at about an angle of #dj degrees1 become more and more curved1 till they are nearly vertical2 and a little further onwards there is seen on the further side of a ravine1 a thick mass of strata of bright red sandstone ,t1 with their upper extremities slightly curved1 showing that they were once conformably prolonged over the beds ,s3 on the southern and opposite side of the road1 this red sandstone and the underlying black shaly rocks stand vertical1 and in actual juxtaposition4 ,continuing to descend1 we come to a synclinal valley filled with rubbish1 beyond which we have the red sandstone ,t#b corresponding with ,t1 and now dipping1 as is seen both north and south of the road1 at #de degrees to the west2 and under it1 the beds ,s#b1 ,r#b1 ,q#b1 and ,i believe ,p#b in corresponding order and of similar composition1 with those on the western flank of the ,pequenes range1 but dipping westward4 ,close to the synclinal valley the dip of these strata is #de degrees1 but at the eastern or farther end of the series it increases to #fj degrees4 ,here the great gypseous formation abruptly terminates1 and is succeeded eastward by a pile of more modern strata4 ,considering how violently these central ranges have been dislocated1 and how very numerous dikes are in the exterior and lower parts of the ,cordillera1 it is remarkable that ,i did not here notice a single dike4 ,the prevailing rock in this neighbourhood is the black1 calcareous1 compact shale1 whilst in the valley-basin of the ,yeso the purplish red sandstone or mudstone predominates1--both being associated with gypseous strata of exactly the same nature4 ,it would be very difficult to ascertain the relative superposition of these several masses1 for we shall afterwards see in the ,cumbre ,pass that the gypseous and intercalated beds are lens-shaped1 and that they thin out1 even where very thick1 and disappear in short horizontal distances3 it is quite possible that the black shales and red sandstones may be contemporaneous1 but it is more probable that the former compose the uppermost parts of the series4 ,the fossils above alluded to in the black calcareous shales are few in number1 and are in an imperfect condition2 they consist1 as named for me by ,m4 d',orbigny1 of3-- #a4 ,ammonite1 indeterminable1 near to ,a4 recticostatus1 d',orbigny1 8,pal4 ,franc40 7,neocomian formation74 #b4 ,gryphaea1 near to ,g4 ,couloni 7,neocomian formations of ,france and ,neufchatel74 #c4 ,natica1 indeterminable4 #d4 ,cyprina rostrata1 d',orbigny1 8,pal4 ,franc40 7,neocomian formation74 #e4 ,rostellaria angulosa 7871 d',orbigny1 8,pal4 de l',amer4 ,mer40 #f4 ,terebratula 7874 ,some of the fragments of ,ammonites were as thick as a man's arm3 the ,gryphaea is much the most abundant shell4 ,these fossils ,m4 d',orbigny considers as belonging to the ,neocomian stage of the ,cretaceous system4 ,dr4 ,meyen1 who ascended the valley of the ,rio ,volcan1 a branch of the ,yeso1 found a nearly similar1 but apparently more calcareous formation1 with much gypsum1 and no doubt the equivalent of that here described 78,reise um ,erde0 etc4 ,th4 #a s4 #cee473 the beds were vertical1 and were prolonged up to the limits of perpetual snow2 at the height of #i1jjj feet above the sea1 they abounded with fossils1 consisting1 according to ,von ,buch 78,descript4 ,phys4 des ,iles ,canaries0 page #dga471 of3-- #a4 ,exogyra 7,gryphaea7 ,couloni1 absolutely identical with specimens from the ,jura and ,south of ,france4 #b4 ,trigonia costata1 identical with those found in the upper ,jurassic beds at ,hildesheim4 #c4 ,pecten striatus1 identical with those found in the upper ,jurassic beds at ,hildesheim4 #d4 ,cucullaea1 corresponding in form to ,c4 longirostris1 so frequent in the upper ,jurassic beds of ,westphalia4 #e4 ,ammonites resembling ,a4 biplex4 ,von ,buch concludes that this formation is intermediate between the limestone of the ,jura and the chalk1 and that it is analogous with the uppermost ,jurassic beds forming the plains of ,switzerland4 ,hence ,m4 ,d',orbigny and ,von ,buch1 under different terms1 compare these fossils to those from the same late stage in the secondary formations of ,europe4 ,some of the fossils which ,i collected were found a good way down the western slope of the main ridge1 and hence must originally have been covered up by a great thickness of the black shaly rock1 independently of the now denuded1 thick1 overlying masses of red sandstone4 ,i neglected at the time to estimate how many hundred or rather thousand feet thick the superincumbent strata must have been3 and ,i will not now attempt to do so4 ,this1 however1 would have been a highly interesting point1 as indicative of a great amount of subsidence1 of which we shall hereafter find in other parts of the ,cordillera analogous evidence during this same period4 ,the altitude of the ,peuquenes ,range1 considering its not great antiquity1 is very remarkable2 many of the fossils were embedded at the height of #ac1baj feet1 and the same beds are prolonged up to at least from fourteen to fifteen thousand feet above the level of the sea4 ,,the ,,portillo ,,or ,,eastern ,,chain4 ,the valley of ,tenuyan1 separating the ,peuquenes and ,portillo lines1 is1 as estimated by ,dr4 ,gillies and myself1 about twenty miles in width2 the lowest part1 where the road crosses the river1 being #g1ejj feet above the sea-level4 ,the pass on the ,portillo line is #ad1cfe feet high 7#a1ajj feet higher than that on the ,peuquenes71 and the neighbouring pinnacles must1 ,i conceive1 rise to nearly #af1jjj feet above the sea4 ,the river draining the intermediate valley of ,tenuyan1 passes through the ,portillo line4 ,to return to our section3--shortly after leaving the lower beds ,p#b of the gypseous formation1 we come to grand masses of a coarse1 red conglomerate ,v1 totally unlike any strata hitherto seen in the ,cordillera4 ,this conglomerate is distinctly stratified1 some of the beds being well defined by the greater size of the pebbles3 the cement is calcareous and sometimes crystalline1 though the mass shows no signs of having been metamorphosed4 ,the included pebbles are either perfectly or only partially rounded3 they consist of purplish sandstones1 of various porphyries1 of brownish limestone1 of black calcareous1 compact shale precisely like that in situ in the ,peuquenes range1 and ,,containing ,,some ,,of ,,the ,,same ,,fossil ,,shells2 also very many pebbles of quartz1 some of micaceous schist1 and numerous1 broken1 rounded crystals of a reddish orthitic or potash feldspar 7as determined by ,professor ,miller71 and these from their size must have been derived from a coarse-grained rock1 probably granite4 ,from this feldspar being orthitic1 and even from its external appearance1 ,i venture positively to affirm that it has not been derived from the rocks of the western ranges2 but1 on the other hand1 it may well have come1 together with the quartz and metamorphic schists1 from the eastern or ,portillo line1 for this line mainly consists of coarse orthitic granite4 ,the pebbles of the fossiliferous slate and of the purple sandstone1 certainly have been derived from the ,peuquenes or western ranges4 ,the road crosses the valley of ,tenuyan in a nearly east and west line1 and for several miles we have on both hands the conglomerate1 everywhere dipping west and forming separate great mountains4 ,the strata1 where first met with1 after leaving the gypseous formation1 are inclined westward at an angle of only #bj degrees1 which further on increases to about #de degrees4 ,the gypseous strata1 as we have seen1 are also inclined westward3 hence1 when looking from the eastern side of the valley towards the ,peuquenes range1 a most deceptive appearance is presented1 as if the newer beds of conglomerate dipped directly under the much older beds of the gypseous formation4 ,in the middle of the valley1 a bold mountain of unstratified lilac-coloured porphyry 7with crystals of hornblende7 projects2 and further on1 a little south of the road1 there is another mountain1 with its strata inclined at a small angle eastwards1 which in its general aspect and colour1 resembles the porphyritic conglomerate formation1 so rare on this side of the ,peuquenes line and so grandly developed throughout the western ranges4 ,the conglomerate is of great thickness3 ,i do not suppose that the strata forming the separate mountain-masses ,v1,v1,v have ever been prolonged over each other1 but that one mass has been broken up by several1 distinct1 parallel1 uniclinal lines of elevation4 ,judging therefore of the thickness of the conglomerate1 as seen in the separate mountain-masses1 ,i estimated it at least from one thousand five hundred to two thousand feet4 ,the lower beds rest conformably on some singularly coloured1 soft strata ,w1 which ,i could not reach to examine2 and these again rest conformably on a thick mass of micaceous1 thinly laminated1 siliceous sandstone ,x1 associated with a little black clay-slate4 ,these lower beds are traversed by several dikes of decomposing porphyry4 ,the laminated sandstone is directly superimposed on the vast masses of granite ,y1,y which mainly compose the ,portillo range4 ,the line of junction between this latter rock1 which is of a bright red colour1 and the whitish sandstone was beautifully distinct2 the sandstone being penetrated by numerous1 great1 tortuous dikes branching from the granite1 and having been converted into a granular quartz rock 7singularly like that of the ,falkland ,islands71 containing specks of an ochrey powder1 and black crystalline atoms1 apparently of imperfect mica4 ,the quartzose strata in one spot were folded into a regular dome4 ,the granite which composes the magnificent bare pinnacles and the steep western flank of the ,portillo chain1 is of a brick-red colour1 coarsely crystallised1 and composed of orthitic or potash feldspar1 quartz1 and imperfect mica in small quantity1 sometimes passing into chlorite4 ,these minerals occasionally assume a laminar or foliated arrangement4 ,the fact of the feldspar being orthitic in this range1 is very remarkable1 considering how rare1 or rather1 as ,i believe1 entirely absent1 this mineral is throughout the western ranges1 in which soda-feldspar1 or at least a variety cleaving like albite1 is so extremely abundant4 ,in one spot on the western flank1 and on the eastern flank near ,los ,manantiales and near the crest1 ,i noticed some great masses of a whitish granite1 parts of it fine- grained1 and parts containing large crystals of feldspar2 ,i neglected to collect specimens1 so ,i do not know whether this feldspar is also orthitic1 though ,i am inclined to think so from its general appearance4 ,i saw also some syenite and one mass which resembled andesite1 but of which ,i likewise neglected to collect specimens4 ,from the manner in which the whitish granites formed separate mountain-masses in the midst of the brick-red variety1 and from one such mass near the crest being traversed by numerous veins of flesh-coloured and greenish eurite 7into which ,i occasionally observed the brick-red granite insensibly passing71 ,i conclude that the white granites probably belong to an older formation1 almost overwhelmed and penetrated by the red granite4 ,on the crest ,i saw also1 at a short distance1 some coloured stratified beds1 apparently like those ,w at the western base1 but was prevented examining them by a snowstorm3 ,mr4 ,caldcleugh1 however1 collected here specimens of ribboned jasper1 magnesian limestone1 and other minerals4 78,travels0 etc4 volume #a page #cjh47 ,a little way down the eastern slope a few fragments of quartz and mica-slate are met with2 but the great formation of this latter rock ,z1 which covers up much of the eastern flank and base of the ,portillo range1 cannot be conveniently examined until much lower down at a place called ,mal ,paso4 ,the mica-schist here consists of thick layers of quartz1 with intervening folia of finely-scaly mica1 often passing into a substance like black glossy clay-slate3 in one spot1 the layers of the quartz having disappeared1 the whole mass became converted into glossy clay-slate4 ,where the folia were best defined1 they were inclined at a high angle westward1 that is1 towards the range4 ,the line of junction between the dark mica-slate and the coarse red granite was most clearly distinguishable from a vast distance3 the granite sent many small veins into the mica-slate1 and included some angular fragments of it4 ,as the sandstone on the western base has been converted by the red granite into a granular quartz-rock1 so this great formation of mica-schist may possibly have been metamorphosed at the same time and by the same means2 but ,i think it more probable1 considering its more perfect metamorphic character and its well-pronounced foliation1 that it belongs to an anterior epoch1 connected with the white granites3 ,i am the more inclined to this view1 from having found at the foot of the range the mica-schist surrounding a hummock ,y#b1 exclusively composed of white granite4 ,near ,los ,arenales1 the mountains on all sides are composed of the mica-slate2 and looking backwards from this point up to the bare gigantic peaks above1 the view was eminently interesting4 ,the colours of the red granite and the black mica-slate are so distinct1 that with a bright light these rocks could be readily distinguished even from the ,pampas1 at a level of at least #i1jjj feet below4 ,the red granite1 from being divided by parallel joints1 has weathered into sharp pinnacles1 on some of which1 even on some of the loftiest1 little caps of mica-schist could be clearly seen3 here and there isolated patches of this rock adhered to the mountain-flanks1 and these often corresponded in height and position on the opposite sides of the immense valleys4 ,lower down the schist prevailed more and more1 with only a few quite small points of granite projecting through4 ,looking at the entire eastern face of the ,portillo range1 the red colour far exceeds in area the black2 yet it was scarcely possible to doubt that the granite had once been almost wholly encased by the mica-schist4 ,at ,los ,arenales1 low down on the eastern flank1 the mica-slate is traversed by several closely adjoining1 broad dikes1 parallel to each other and to the foliation of the schist4 ,the dikes are formed of three different varieties of rock1 of which a pale brown feldspathic porphyry with grains of quartz was much the most abundant4 ,these dikes with their granules of quartz1 as well as the mica-schist itself1 strikingly resemble the rocks of the ,chonos ,archipelago4 ,at a height of about twelve hundred feet above the dikes1 and perhaps connected with them1 there is a range of cliffs formed of successive lava-streams ,,aa1 between three and four hundred feet in thickness1 and in places finely columnar4 ,the lava consists of dark- greyish1 harsh rocks1 intermediate in character between trachyte and basalt1 containing glassy feldspar1 olivine1 and a little mica1 and sometimes amygdaloidal with zeolite3 the basis is either quite compact1 or crenulated with air-vesicles arranged in laminae4 ,the streams are separated from each other by beds of fragmentary brown scoriae1 firmly cemented together1 and including a few well-rounded pebbles of lava4 ,from their general appearance1 ,i suspect that these lava-streams flowed at an ancient period under the pressure of the sea1 when the ,atlantic covered the ,pampas and washed the eastern foot of the ,cordillera4 7,this conclusion might1 perhaps1 even have been anticipated1 from the general rarity of volcanic action1 except near the sea or large bodies of water4 ,conformably with this rule1 at the present day1 there are no active volcanoes on this eastern side of the ,cordillera2 nor are severe earthquakes experienced here47 ,on the opposite and northern side of the valley there is another line of lava- cliffs at a corresponding height2 the valley between being of considerable breadth1 and as nearly as ,i could estimate #a1ejj feet in depth4 ,this field of lava is confined on both sides by the mountains of mica-schist1 and slopes down rapidly but irregularly to the edge of the ,pampas1 where1 having a thickness of about two hundred feet1 it terminates against a little range of claystone porphyry4 ,the valley in this lower part expands into a bay-like1 gentle slope1 bordered by the cliffs of lava1 which must certainly once have extended across this wide expanse4 ,the inclination of the streams from ,los ,arenales to the mouth of the valley is so great1 that at the time 7though ignorant of ,m4 ,elie de ,beaumont's researches on the extremely small slope over which lava can flow1 and yet retain a compact structure and considerable thickness7 ,i concluded that they must subsequently to their flowing have been upheaved and tilted from the mountains2 of this conclusion ,i can now entertain not the smallest doubt4 ,at the mouth of the valley1 within the cliffs of the above lava-field1 there are remnants1 in the form of separate small hillocks and of lines of low cliffs1 of a considerable deposit of compact white tuff 7quarried for filtering-stones71 composed of broken pumice1 volcanic crystals1 scales of mica1 and fragments of lava4 ,this mass has suffered much denudation2 and the hard mica-schist has been deeply worn1 since the period of its deposition2 and this period must have been subsequent to the denudation of the basaltic lava-streams1 as attested by their encircling cliffs standing at a higher level4 ,at the present day1 under the existing arid climate1 ages might roll past without a square yard of rock of any kind being denuded1 except perhaps in the rarely moistened drainage-channel of the valley4 ,must we then look back to that ancient period1 when the waves of the sea beat against the eastern foot of the ,cordillera1 for a power sufficient to denude extensively1 though superficially1 this tufaceous deposit1 soft although it be8 ,there remains only to mention some little water-worn hillocks ,,bb1 a few hundred feet in height1 and mere mole-hills compared with the gigantic mountains behind them1 which rise out of the sloping1 shingle-covered margin of the ,pampas4 ,the first little range is composed of a brecciated purple porphyritic claystone1 with obscurely marked strata dipping at #gj degrees to the ,s4,w42 the other ranges consist of--a pale-coloured feldspathic porphyry1--a purple claystone porphyry with grains of quartz1-- and a rock almost exclusively composed of brick-red crystals of feldspar4 ,these outermost small lines of elevation extend in a ,n4,w4 by ,w4 and ,s4,e4 by ,s4 direction4 ,,concluding ,,remarks ,,on ,,the ,,portillo ,,range4 ,when on the ,pampas and looking southward1 and whilst travelling northward1 ,i could see for very many leagues the red granite and dark mica-schist forming the crest and eastern flank of the ,portillo line4 ,this great range1 according to ,dr4 ,gillies1 can be traced with little interruption for #adj miles southward to the ,r4 ,diamante1 where it unites with the western ranges3 northward1 according to this same author1 it terminates where the ,r4 ,mendoza debouches from the mountains2 but a little further north in the eastern part of the ,cumbre section1 there are1 as we shall hereafter see1 some mountain-masses of a brick-red porphyry1 the last injected amidst many other porphyries1 and having so close an analogy with the coarse red granite of the ,portillo line1 that ,i am tempted to believe that they belong to the same axis of injection2 if so1 the ,portillo line is at least #bjj miles in length4 ,its height1 even in the lowest gap in the road1 is #ad1cfe feet1 and some of the pinnacles apparently attain an elevation of about #af1jjj feet above the sea4 ,the geological history of this grand chain appears to me eminently interesting4 ,we may safely conclude1 that at a former period the valley of ,tenuyan existed as an arm of the sea1 about twenty-miles in width1 bordered on one hand by a ridge or chain of islets of the black calcareous shales and purple sandstones of the gypseous formation2 and on the other hand1 by a ridge or chain of islets composed of mica-slate1 white granite1 and perhaps to a partial extent of red granite4 ,these two chains1 whilst thus bordering the old sea-channel1 must have been exposed for a vast lapse of time to alluvial and littoral action1 during which the rocks were shattered1 the fragments rounded1 and the strata of conglomerate accumulated to a thickness of at least fifteen hundred or two thousand feet4 ,the red orthitic granite now forms1 as we have seen1 the main part of the ,portillo chain3 it is injected in dikes not only into the mica-schist and white granites1 but into the laminated sandstone1 which it has metamorphosed1 and which it has thrown off1 together with the conformably overlying coloured beds and stratified conglomerate1 at an angle of forty-five degrees4 ,to have thrown off so vast a pile of strata at this angle1 is a proof that the main part of the red granite 7whether or not portions1 as perhaps is probable1 previously existed7 was injected in a liquified state after the accumulation both of the laminated sandstone and of the conglomerate2 this conglomerate1 we know1 was accumulated1 not only after the deposition of the fossiliferous strata of the ,peuquenes line1 but after their elevation and long-continued denudation3 and these fossiliferous strata belong to the early part of the ,cretaceous system4 ,late1 therefore1 in a geological sense1 as must be the age of the main part of the red granite1 ,i can conceive nothing more impressive than the eastern view of this great range1 as forcing the mind to grapple with the idea of the thousands of thousands of years requisite for the denudation of the strata which originally encased it1--for that the fluidified granite was once encased1 its mineralogical composition and structure1 and the bold conical shape of the mountain-masses1 yield sufficient evidence4 ,of the encasing strata we see the last vestiges in the coloured beds on the crest1 in the little caps of mica-schist on some of the loftiest pinnacles1 and in the isolated patches of this same rock at corresponding heights on the now bare and steep flanks4 ,the lava-streams at the eastern foot of the ,portillo are interesting1 not so much from the great denudation which they have suffered at a comparatively late period as from the evidence they afford by their inclination taken conjointly with their thickness and compactness1 that after the great range had assumed its present general outline1 it continued to rise as an axis of elevation4 ,the plains extending from the base of the ,cordillera to the ,atlantic show that the continent has been upraised in mass to a height of #c1ejj feet1 and probably to a much greater height1 for the smooth shingle-covered margin of the ,pampas is prolonged in a gentle unbroken slope far up many of the great valleys4 ,nor let it be assumed that the ,peuquenes and ,portillo ranges have undergone only movements of elevation2 for we shall hereafter see1 that the bottom of the sea subsided several thousand feet during the deposition of strata1 occupying the same relative place in the ,cordillera1 with those of the ,peuquenes ridge2 moreover1 we shall see from the unequivocal evidence of buried upright trees1 that at a somewhat later period1 during the formation of the ,uspallata chain1 which corresponds geographically with that of the ,portillo1 there was another subsidence of many thousand feet3 here1 indeed1 in the valley of ,tenuyan1 the accumulation of the coarse stratified conglomerate to a thickness of fifteen hundred or two thousand feet1 offers strong presumptive evidence of subsidence2 for all existing analogies lead to the belief that large pebbles can be transported only in shallow water1 liable to be affected by currents and movements of undulation--and if so1 the shallow bed of the sea on which the pebbles were first deposited must necessarily have sunk to allow of the accumulation of the superincumbent strata4 ,what a history of changes of level1 and of wear and tear1 all since the age of the latter secondary formations of ,europe1 does the structure of this one great mountain-chain reveal6 ,,passage ,,of ,,the ,,andes ,,by ,,the ,,cumbre ,,or ,,uspallata ,,pass4 ,this ,pass crosses the ,andes about sixty miles north of that just described3 the section given in ,plate #a1 ,section #a_/b1 is on the same scale as before1 namely1 at one-third of an inch to a mile in distance1 and one inch to a mile 7or #f1jjj feet7 in height4 ,like the last section1 it is a mere sketch1 and cannot pretend to accuracy1 though made under favourable circumstances4 ,we will commence as before1 with the western half1 of which the main range bears the name of the ,cumbre 7that is the ,ridge71 and corresponds to the ,peuquenes line in the former section2 as does the ,uspallata range1 though on a much smaller scale1 to that of the ,portillo4 ,near the point where the river ,aconcagua debouches on the basin plain of the same name1 at a height of about two thousand three hundred feet above the sea1 we meet with the usual purple and greenish porphyritic claystone conglomerate4 ,beds of this nature1 alternating with numerous compact and amygdaloidal porphyries1 which have flowed as submarine lavas1 and associated with great mountain- masses of various1 injected1 non-stratified porphyries1 are prolonged the whole distance up to the ,cumbre or central ridge4 ,one of the commonest stratified porphyries is of a green colour1 highly amygdaloidal with the various minerals described in the preliminary discussion1 and including fine tabular crystals of albite4 ,the mountain-range north 7often with a little westing7 and south4 ,the stratification1 wherever ,i could clearly distinguish it1 was inclined westward or towards the ,pacific1 and1 except near the ,cumbre1 seldom at angles above #be degrees4 ,only at one spot on this western side1 on a lofty pinnacle not far from the ,cumbre1 ,i saw strata apparently belonging to the gypseous formation1 and conformably capping a pile of stratified porphyries4 ,hence1 both in composition and in stratification1 the structure of the mountains on this western side of the divortium aquarum1 is far more simple than in the corresponding part of the ,peuquenes section4 ,in the porphyritic claystone conglomerate1 the mechanical structure and the planes of stratification have generally been much obscured and even quite obliterated towards the base of the series1 whilst in the upper parts1 near the summits of the mountains1 both are distinctly displayed4 ,in these upper portions the porphyries are generally lighter coloured4 ,in three places ,x1 ,y1 ,z masses of andesite are exposed3 at ,y1 this rock contained some quartz1 but the greater part consisted of andesitic porphyry1 with only a few well-developed crystals of albite1 and forming a great white mass1 having the external aspect of granite1 capped by much dark unstratified porphyry4 ,in many parts of the mountains1 there are dikes of a green colour1 and other white ones1 which latter probably spring from underlying masses of andesite4 ,the ,cumbre1 where the road crosses it1 is1 according to ,mr4 ,pentland1 #ab1ded feet above the sea2 and the neighbouring peaks1 composed of dark purple and whitish porphyries1 some obscurely stratified with a westerly dip1 and others without a trace of stratification1 must exceed #ac1jjj feet in height4 ,descending the eastern slope of the ,cumbre1 the structure becomes very complicated1 and generally differs on the two sides of the east and west line of road and section4 ,first we come to a great mass ,a of nearly vertical1 singularly contorted strata1 composed of highly compact red sandstones1 and of often calcareous conglomerates1 and penetrated by green1 yellow1 and reddish dikes2 but ,i shall presently have an opportunity of describing in some detail an analogous pile of strata4 ,these vertical beds are abruptly succeeded by others ,b1 of apparently nearly the same nature but more metamorphosed1 alternating with porphyries and limestones2 these dip for a short space westward1 but there has been here an extraordinary dislocation1 which1 on the north side of the road1 appears to have determined the excavation of the north and south valley of the ,r4 de las ,cuevas4 ,on this northern side of the road1 the strata ,b are prolonged till they come in close contact with a jagged lofty mountain ,d of dark- coloured1 unstratified1 intrusive porphyry1 where the beds have been more highly inclined and still more metamorphosed4 ,this mountain of porphyry seems to form a short axis of elevation1 for south of the road in its line there is a hill ,c of porphyritic conglomerate with absolutely vertical strata4 ,we now come to the gypseous formation3 ,i will first describe the structure of the several mountains1 and then give in one section a detailed account of the nature of the rocks4 ,on the north side of the road1 which here runs in an east and west valley1 the mountain of porphyry ,d is succeeded by a hill ,e formed of the upper gypseous strata tilted1 at an angle of between #gj and #hj degrees to the west1 by a uniclinal axis of elevation which does not run parallel to the other neighbouring ranges1 and which is of short length2 for on the south side of the valley its prolongation is marked only by a small flexure in a pile of strata inclined by a quite separate axis4 ,a little further on the north and south valley of ,horcones enters at right angles our line of section2 its western side is bounded by a hill of gypseous strata ,f dipping westward at about #de degrees1 and its eastern side by a mountain of similar strata ,g inclined westward at #gj degrees1 and superimposed by an oblique fault on another mass of the same strata ,h1 also inclined westward1 but at an angle of about #cj degrees3 the complicated relation of these three masses ,f1 ,g1 ,h is explained by the structure of a great mountain-range lying some way to the north1 in which a regular anticlinal axis 7represented in the section by dotted lines7 is seen1 with the strata on its eastern side again bending up and forming a distinct uniclinal axis1 of which the beds marked ,h form the lower part4 ,this great uniclinal line is intersected1 near the ,puente del ,inca1 by the valley along which the road runs1 and the strata composing it will be immediately described4 ,on the south side of the road1 in the space corresponding with the mountains ,e1 ,f1 and ,g1 the strata everywhere dip westward generally at an angle of #cj degrees1 occasionally mounting up to #de degrees1 but not in an unbroken line1 for there are several vertical faults1 forming separate uniclinal masses1 all dipping in the same direction1--a form of elevation common in the ,cordillera4 ,we thus see that within a narrow space1 the gypseous strata have been upheaved and crushed together by a great uniclinal1 anticlinal1 and one lesser uniclinal line ,e of elevation2 and that between these three lines and the ,cumbre1 in the sandstones1 conglomerates and porphyritic formation1 there have been at least two or three other great elevatory axes4 ,the uniclinal axis ,i intersected near the ,puente del ,inca 7of which the strata at ,h form a part7 ranges ,n4 by ,w4 and ,s4 by ,e41 forming a chain of mountains1 apparently little inferior in height to the ,cumbre3 the strata1 as we have seen1 dip at an average angle of #cj degrees to the west4 7,at this place1 there are some hot and cold springs1 the warmest having a temperature1 according to ,lieutenant ,brand 8,travels10 page #bdj1 of #ia degrees2 they emit much gas4 ,according to ,mr4 ,brande1 of the ,royal ,institution1 ten cubical inches contain forty-five grains of solid matter1 consisting chiefly of salt1 gypsum1 carbonate of lime1 and oxide of iron4 ,the water is charged with carbonic acid and sulphuretted hydrogen4 ,these springs deposit much tufa in the form of spherical balls4 ,they burst forth1 as do those of ,cauquenes1 and probably those of ,villa ,vicencio1 on a line of elevation47 ,the flanks of the mountains are here quite bare and steep1 affording an excellent section2 so that ,i was able to inspect the strata to a thickness of about #d1jjj feet1 and could clearly distinguish their general nature for #a1jjj feet higher1 making a total thickness of #e1jjj feet1 to which must be added about #a1jjj feet of the inferior strata seen a little lower down the valley1 ,i will describe this one section in detail1 beginning at the bottom4 #ast4 ,the lowest mass is the altered clay-slate described in the preliminary discussion1 and which in this line of section was here first met with4 ,lower down the valley1 at the ,r4 de las ,vacas1 ,i had a better opportunity of examining it2 it is there in some parts well characterised1 having a distinct1 nearly vertical1 tortuous cleavage1 ranging ,n4,w4 and ,s4,e41 and intersected by quartz veins3 in most parts1 however1 it is crystalline and feldspathic1 and passes into a true greenstone often including grains of quartz4 ,the clay-slate1 in its upper half1 is frequently brecciated1 the embedded angular fragments being of nearly the same nature with the paste4 #bnd4 ,several strata of purplish porphyritic conglomerate1 of no very great thickness1 rest conformably upon the feldspathic slate4 ,a thick bed of fine1 purple1 claystone porphyry1 obscurely brecciated 7but not of metamorphosed sedimentary origin71 and capped by porphyritic conglomerate1 was the lowest bed actually examined in this section at the ,puente del ,inca4 #crd4 ,a stratum1 eighty feet thick1 of hard and very compact impure whitish limestone1 weathering bright red1 with included layers brecciated and re- cemented4 ,obscure marks of shell are distinguishable in it4 #dth4 ,a red1 quartzose1 fine-grained conglomerate1 with grains of quartz1 and with patches of white earthy feldspar1 apparently due to some process of concretionary crystalline action2 this bed is more compact and metamorphosed than any of the overlying conglomerates4 #eth4 ,a whitish cherty limestone1 with nodules of bluish argillaceous limestone4 #fth4 ,a white conglomerate1 with many particles of quartz1 almost blending into the paste4 #gth4 ,highly siliceous1 fine-grained white sandstone4 #hth and #ith4 ,red and white beds not examined4 #ajth4 ,yellow1 fine-grained1 thinly stratified1 magnesian 7judging from its slow dissolution in acids7 limestone3 it includes some white quartz pebbles1 and little cavities1 lined with calcareous spar1 some retaining the form of shells4 #aath4 ,a bed between twenty and thirty feet thick1 quite conformable with the underlying ones1 composed of a hard basis1 tinged lilac-grey porphyritic with ,,numerous crystals of whitish feldspar1 with black mica and little spots of soft ferruginous matter3 evidently a submarine lava4 #abth4 ,yellow magnesian limestone1 as before1 part-stained purple4 #acth4 ,a most singular rock2 basis purplish grey1 obscurely crystalline1 easily fusible into a dark green glass1 not hard1 thickly speckled with crystals more or less perfect of white carbonate of lime1 of red hydrous oxide of iron1 of a white and transparent mineral like analcime1 and of a green opaque mineral like soap-stone2 the basis is moreover amygdaloidal with many spherical balls of white crystallised carbonate of lime1 of which some are coated with the red oxide of iron4 ,i have no doubt1 from the examination of a superincumbent stratum 7#ai71 that this is a submarine lava2 though in ,northern ,chile1 some of the metamorphosed sedimentary beds are almost as crystalline1 and of as varied composition4 #adth4 ,red sandstone1 passing in the upper part into a coarse1 hard1 red conglomerate1 #cjj feet thick1 having a calcareous cement1 and including grains of quartz and broken crystals of feldspar2 basis infusible2 the pebbles consist of dull purplish porphyries1 with some of quartz1 from the size of a nut to a man's head4 ,this is the coarsest conglomerate in this part of the ,cordillera3 in the middle there was a white layer not examined4 #aeth4 ,grand thick bed1 of a very hard1 yellowish-white rock1 with a crystalline feldspathic base1 including large crystals of white feldspar1 many little cavities mostly full of soft ferruginous matter1 and numerous hexagonal plates of black mica4 ,the upper part of this great bed is slightly cellular2 the lower part compact3 the thickness varied a little in different parts4 ,manifestly a submarine lava2 and is allied to bed #aa4 #afth and #agth4 ,dull purplish1 calcareous1 fine-grained1 compact sandstones1 which pass into coarse white conglomerates with numerous particles of quartz4 #ahth4 ,several alternations of red conglomerate1 purplish sandstone1 and submarine lava1 like that singular rock forming bed #ac4 #aith4 ,a very heavy1 compact1 greenish-black stone1 with a fine-grained obviously crystalline basis1 containing a few specks of white calcareous spar1 many specks of the crystallised hydrous red oxide of iron1 and some specks of a green mineral2 there are veins and nests filled with epidote3 certainly a submarine lava4 #bjth4 ,many thin strata of compact1 fine-grained1 pale purple sandstone4 #bast4 ,gypsum in a nearly pure state1 about three hundred feet in thickness3 this bed1 in its concretions of anhydrite and layers of small blackish crystals of carbonate of lime1 exactly resembles the great gypseous beds in the ,peuquenes range4 #bbnd4 ,pale purple and reddish sandstone1 as in bed #bj3 about three hundred feet in thickness4 #bcrd4 ,a thick mass composed of layers1 often as thin as paper and convoluted1 of pure gypsum with others very impure1 of a purplish colour4 #bdth4 ,pure gypsum1 thick mass4 #beth4 ,red sandstones1 of great thickness4 #bfth4 ,pure gypsum1 of great thickness4 #bgth4 ,alternating layers of pure and impure gypsum1 of great thickness4 ,i was not able to ascend to these few last great strata1 which compose the neighbouring loftiest pinnacles4 ,the thickness1 from the lowest to the uppermost bed of gypsum1 cannot be less than #b1jjj feet3 the beds beneath ,i estimated at #c1jjj feet1 and this does not include either the lower parts of the porphyritic conglomerate1 or the altered clay-slate2 ,i conceive the total thickness must be about six thousand feet4 ,i distinctly observed that not only the gypsum1 but the alternating sandstones and conglomerates were lens-shaped1 and repeatedly thinned out and replaced each other3 thus in the distance of about a mile1 a bed #cjj feet thick of sandstone between two beds of gypsum1 thinned out to nothing and disappeared4 ,the lower part of this section differs remarkably1--in the much greater diversity of its mineralogical composition1--in the abundance of calcareous matter1--in the greater coarseness of some of the conglomerates1--and in the numerous particles and well-rounded pebbles1 sometimes of large size1 of quartz1-- from any other section hitherto described in ,chile4 ,from these peculiarities and from the lens-form of the strata1 it is probable that this great pile of strata was accumulated on a shallow and very uneven bottom1 near some pre-existing land formed of various porphyries and quartz-rock4 ,the formation of porphyritic claystone conglomerate does not in this section attain nearly its ordinary thickness2 this may be ,,partly attributed to the metamorphic action having been here much less energetic than usual1 though the lower beds have been affected to a certain degree4 ,if it had been as energetic as in most other parts of ,chile1 many of the beds of sandstone and conglomerate1 containing rounded masses of porphyry1 would doubtless have been converted into porphyritic conglomerate2 and these would have alternated with1 and even blended into1 crystalline and porphyritic strata without a trace of mechanical structure1--namely1 into those which1 in the present state of the section1 we see are unquestionably submarine lavas4 ,the beds of gypsum1 together with the red alternating sandstones and conglomerates1 present so perfect and curious a resemblance with those seen in our former section in the basin-valley of ,yeso1 that ,i cannot doubt the identity of the two formations3 ,i may add1 that a little westward of the ,p4 del ,inca1 a mass of gypsum passed into a fine-grained1 hard1 brown sandstone1 which contained some layers of black1 calcareous1 compact1 shaly rock1 precisely like that seen in such vast masses on the ,peuquenes range4 ,near the ,puente del ,inca1 numerous fragments of limestone1 containing some fossil remains1 were scattered on the ground3 these fragments so perfectly resemble the limestone of bed ,no4 #c1 in which ,i saw impressions of shells1 that ,i have no doubt they have fallen from it4 ,the yellow magnesian limestone of bed ,no4 #aj1 which also includes traces of shells1 has a different appearance4 ,these fossils 7as named by ,m4 d',orbigny7 consist of3-- ,gryphaea1 near to ,g4 ,couloni 7,neocomian formation74 ,arca1 perhaps ,a4 ,gabrielis1 d',orbigny1 8,pal4 ,franc40 7,neocomian formation74 ,mr4 ,pentland made a collection of shells from this same spot1 and ,von ,buch considers them as consisting of3-- ,trigonia1 resembling in form ,t4 costata4 ,pholadomya1 like one found by ,m4 ,dufresnoy near ,alencon4 ,isocardi excentrica1 ,voltz41 identical with that from the ,jura4 78,description ,phys4 des ,iles ,can40 page #dgb47 ,two of these shells1 namely1 the ,gryphaea and ,trigonia1 appear to be identical with species collected by ,meyen and myself on the ,peuquenes range2 and in the opinion of ,von ,buch and ,m4 d',orbigny1 the two formations belong to the same age4 ,i must here add1 that ,professor ,e4 ,forbes1 who has examined my specimens from this place and from the ,peuquenes range1 has likewise a strong impression that they indicate the ,cretaceous period1 and probably an early epoch in it3 so that all the palaeontologists who have seen these fossils nearly coincide in opinion regarding their age4 ,the limestone1 however1 with these fossils here lies at the very base of the formation1 just above the porphyritic conglomerate1 and certainly several thousand feet lower in the series1 than the equivalent1 fossiliferous1 black1 shaly rocks high up on the ,peuquenes range4 ,it is well worthy of remark that these shells1 or at least those of which ,i saw impressions in the limestone 7bed ,no4 #c71 must have been covered up1 on the ,,least computation1 by #d1jjj feet of strata3 now we know from ,professor ,e4 ,forbes's researches1 that the sea at greater depths than #fjj feet becomes exceedingly barren of organic beings1--a result quite in accordance with what little ,i have seen of deep-sea soundings4 ,hence1 after this limestone with its shells was deposited1 the bottom of the sea where the main line of the ,cordillera now stands1 must have subsided some thousand feet to allow of the deposition of the superincumbent submarine strata4 ,without supposing a movement of this kind1 it would1 moreover1 be impossible to understand the accumulation of the several lower strata of ,,coarse1 well-rounded conglomerates1 which it is scarcely possible to believe were spread out in profoundly deep water1 and which1 especially those containing pebbles of quartz1 could hardly have been rounded in submarine craters and afterwards ejected from them1 as ,i believe to have been the case with much of the porphyritic conglomerate formation4 ,i may add that1 in ,professor ,forbes's opinion1 the above-enumerated species of mollusca probably did not live at a much greater depth than twenty fathoms1 that is only #abj feet4 ,to return to our section down the valley2 standing on the great ,n4 by ,w4 and ,s4 by ,e4 uniclinal axis of the ,puente del ,inca1 of which a section has just been given1 and looking north-east1 greater tabular masses of gypseous formation 7,,kk7 could be seen in the distance1 very slightly inclined towards the east4 ,lower down the valley1 the mountains are almost exclusively composed of porphyries1 many of them of intrusive origin and non-stratified1 others stratified1 but with the stratification seldom distinguishable except in the upper parts4 ,disregarding local disturbances1 the beds are either horizontal or inclined at a small angle eastwards3 hence1 when standing on the plain of ,uspallata and looking to the west or backwards1 the ,cordillera appear composed of huge1 square1 nearly horizontal1 tabular masses3 so wide a space1 with such lofty mountains so equably elevated1 is rarely met with within the ,cordillera4 ,in this line of section1 the interval between the ,puente del ,inca and the neighbourhood of the ,cumbre1 includes all the chief axes of dislocation4 ,the altered clay-slate formation1 already described1 is seen in several parts of the valley as far down as ,las ,vacas1 underlying the porphyritic conglomerate4 ,at the ,casa de ,pujios ,l1 there is a hummock of 7andesitic87 granite2 and the stratification of the surrounding mountains here changes from ,w4 by ,s4 to ,s4,w4 ,again1 near the ,r4 ,vacas there is a larger formation of 7andesitic87 granite ,m1 which sends a meshwork of veins into the superincumbent clay-slate1 and which locally throws off the strata1 on one side to ,n4,w4 and on the other to ,s4,e4 but not at a high angle3 at the junction1 the clay-slate is altered into fine-grained greenstone4 ,this granitic axis is intersected by a green dike1 which ,i mention1 because ,i do not remember having elsewhere seen dikes in this lowest and latest intrusive rock4 ,from the ,r4 ,vacas to the plain of ,uspallata1 the valley runs ,n4,e41 so that ,i have had to contract my section2 it runs exclusively through porphyritic rocks4 ,as far as the ,pass of ,jaula1 the claystone conglomerate formation1 in most parts highly porphyritic1 and crossed by numerous dikes of greenstone porphyry1 attains a great thickness3 there is also much intrusive porphyry4 ,from the ,jaula to the plain1 the stratification has been in most places obliterated1 except near the tops of some of the mountains2 and the metamorphic action has been extremely great4 ,in this space1 the number and bulk of the intrusive masses of differently coloured porphyries1 injected one into another and intersected by dikes1 is truly extraordinary4 ,i saw one mountain of whitish porphyry1 from which two huge dikes1 thinning out1 branched ,,downwards into an adjoining blackish porphyry4 ,another hill of white porphyry1 which had burst through dark- coloured strata1 was itself injected by a purple1 brecciated1 and recemented porphyry1 both being crossed by a green dike1 and both having been upheaved and injected by a granitic dome4 ,one brick-red porphyry1 which above the ,jaula forms an isolated mass in the midst of the porphyritic conglomerate formation1 and lower down the valley a magnificent group of peaked mountains1 differs remarkably from all the other porphyries4 ,it consists of a red feldspathic base1 including some rather large crystals of red feldspar1 numerous large angular grains of quartz1 and little bits of a soft green mineral answering in most of its characters to soapstone4 ,the crystals of red feldspar resemble in external appearance those of orthite1 though1 from being partially decomposed1 ,i was unable to measure them2 and they certainly are quite unlike the variety1 so abundantly met with in almost all the other rocks of this line of section1 and which1 wherever ,i tried it1 cleaved like albite4 ,this brick-red porphyry appears to have burst through all the other porphyries1 and numerous red dikes traversing the neighbouring mountains have proceeded from it3 in some few places1 however1 it was intersected by white dikes4 ,from this posteriority of intrusive origin1--from the close general resemblance between this red porphyry and the red granite of the ,portillo line1 the only difference being that the feldspar here is less perfectly granular1 and that soapstone replaces the mica1 which is there imperfect and passes into chlorite1--and from the ,portillo line a little southward of this point appearing to blend 7according to ,dr4 ,gillies7 into the western ranges1--,i am strongly urged to believe 7as formerly remarked7 that the grand mountain-masses composed of this brick-red porphyry belong to the same axis of injection with the granite of the ,portillo line2 if so1 the injection of this porphyry probably took place1 as long subsequently to the several axes of elevation in the gypseous formation near the ,cumbre1 as the injection of the ,portillo granite has been shown to have been subsequent to the elevation of the gypseous strata composing the ,peuquenes range2 and this interval1 we have seen1 must have been a very long one4 ,the ,plain of ,uspallata has been briefly described in ,chapter #c2 it resembles the basin-plains of ,chile2 it is ten or fifteen miles wide1 and is said to extend for #ahj miles northward2 its surface is nearly six thousand feet above the sea2 it is composed1 to a thickness of some hundred feet of loosely aggregated1 stratified shingle1 which is prolonged with a gently sloping surface up the valleys in the mountains on both sides4 ,one section in this plain ,z is interesting1 from the unusual circumstance of alternating layers of almost loose red and white sand with lines of pebbles 7from the size of a nut to that of an apple71 and beds of gravel1 being inclined at an angle of #de degrees1 and in some spots even at a higher angle4 7,i find that ,mr4 ,smith of ,jordan ,hill has described 78,edinburgh ,new ,philosophical ,journal0 volume #be page #cib7 beds of sand and gravel1 near ,edinburgh1 tilted at an angle of #fj degrees1 and dislocated by miniature faults47 ,these beds are dislocated by small faults3 and are capped by a thick mass of horizontally stratified gravel1 evidently of subaqueous origin4 ,having been accustomed to observe the irregularities of beds accumulated under currents1 ,i feel sure that the inclination here has not been thus produced4 ,the pebbles consist chiefly of the brick-red porphyry just described and of white granite1 both probably derived from the ranges to the west1 and of altered clay-slate and of certain porphyries1 apparently belonging to the rocks of the ,uspallata chain4 ,this plain corresponds geographically with the valley of ,tenuyan between the ,portillo and ,peuquenes ranges2 but in that valley the shingle1 which likewise has been derived both from the eastern and western ranges1 has been cemented into a hard conglomerate1 and has been throughout tilted at a considerable inclination2 the gravel there apparently attains a much greater thickness1 and is probably of higher antiquity4 ,,the ,,uspallata ,,range4 ,the road by the ,villa ,vicencio ,pass does not strike directly across the range1 but runs for some leagues northward along its western base3 and ,i must briefly describe the rocks here seen1 before continuing with the coloured east and west section4 ,at the mouth of the valley of ,canota1 and at several points northwards1 there is an extensive formation of a glossy and harsh1 and of a feldspathic clay-slate1 including strata of grauwacke1 and having a tortuous1 nearly vertical cleavage1 traversed by numerous metalliferous veins and others of quartz4 ,the clay-slate is in many parts capped by a thick mass of fragments of the same rock1 firmly recemented2 and both together have been injected and broken up by very numerous hillocks1 ranging north and south1 of lilac1 white1 dark and salmon- coloured porphyries3 one steep1 now denuded1 hillock of porphyry had its face as distinctly impressed with the angles of a fragmentary mass of the slate1 with some of the points still remaining embedded1 as sealing-wax could be by a seal4 ,at the mouth of this same valley of ,canota1 in a fine escarpment having the strata dipping from #ej to #fj degrees to the ,n4,e4 7,nearly opposite to this escarpment1 there is another corresponding one1 with the strata dipping not to the exactly opposite point1 or ,s4,w41 but to ,s4,s4,w43 consequently the two escarpments trend towards each other1 and some miles southward they become actually united3 this is a form of elevation which ,i have not elsewhere seen471 the clay-slate formation is seen to be covered by--7#ast7 a purple1 claystone porphyry resting unconformably in some parts on the solid slate1 and in others on a thick fragmentary mass2 7#bnd71 a conformable stratum of compact blackish rock1 having a spheroidal structure1 full of minute acicular crystals of glassy feldspar1 with red spots of oxide of iron2 7#crd71 a great stratum of purplish-red claystone porphyry1 abounding with crystals of opaque feldspar1 and laminated with thin1 parallel1 often short1 layers1 and likewise with great irregular patches of white1 earthy1 semi-crystalline feldspar2 this rock 7which ,i noticed in other neighbouring places7 perfectly resembles a curious variety described at ,port ,desire1 and occasionally occurs in the great porphyritic conglomerate formation of ,chile2 7#dth71 a thin stratum of greenish white1 indurated tuff1 fusible and containing broken crystals and particles of porphyries2 7#eth71 a grand mass1 imperfectly columnar and divided into three parallel and closely joined strata1 of cream-coloured claystone porphyry2 7#fth71 a thick stratum of lilac-coloured porphyry1 which ,i could see was capped by another bed of the cream-coloured variety2 ,i was unable to examine the still higher parts of the escarpment4 ,these conformably stratified porphyries1 though none are either vesicular are amygdaloidal1 have evidently flowed as submarine lavas3 some of them are separated from each other by seams of indurated tuff1 which1 however1 are quite insignificant in thickness compared with the porphyries4 ,this whole pile resembles1 but not very closely1 some of the less brecciated parts of the great porphyritic conglomerate formation of ,chile2 but it does not probably belong to the same age1 as the porphyries here rest unconformably on the altered feldspathic clay-slate1 whereas the porphyritic conglomerate formation alternates with and rests conformably on it4 ,these porphyries1 moreover1 with the exception of the one blackish stratum1 and of the one indurated1 white tufaceous bed1 differ from the beds composing the ,uspallata range in the line of the ,villa ,vicencio ,pass4 ,i will now give1 first1 a sketch of the structure of the range1 as represented in the section1 and will then describe its composition and interesting history4 ,at its western foot1 a hillock ,n is seen to rise out of the plain1 with its strata dipping at #gj degrees to the west1 fronted by strata ,o inclined at #de degrees to the east1 thus forming a little north and south anticlinal axis4 ,some other little hillocks of similar composition1 with their strata highly inclined1 range ,n4,e4 and ,s4,w41 obliquely to the main ,uspallata line4 ,the cause of these dislocations1 which1 though on a small scale1 have been violent and complicated1 is seen to lie in hummocks of lilac1 purple and red porphyries1 which have been injected in a liquified state through and into the underlying clay-slate formation4 ,several dykes were exposed here1 but in no other part1 that ,i saw of this range4 ,as the strata consist of black1 white1 greenish and brown-coloured rocks1 and as the intrusive porphyries are so brightly tinted1 a most extraordinary view was presented1 like a coloured geological drawing4 ,on the gently inclined main western slope ,,pp1 above the little anticlinal ridges just mentioned1 the strata dip at an average angle of #be degrees to the west2 the inclination in some places being only #ai degrees1 in some few others as much as #de degrees4 ,the masses having these different inclinations1 are separated from each other by parallel vertical faults as represented at ,pa1 often giving rise to separate1 parallel1 uniclinal ridges4 ,the summit of the main range is broad and undulatory1 with the stratification undulatory and irregular3 in a few places granitic and porphyritic masses ,q protrude1 which1 from the small effect they have locally produced in deranging the strata1 probably form the upper points of a regular1 great underlying dome4 ,these denuded granitic points1 ,i estimated at about nine thousand feet in height above the sea4 ,on the eastern slope1 the strata in the upper part are regularly inclined at about #be degrees to the east1 so that the summit of this chain1 neglecting small irregularities1 forms a broad anticlinal axis4 ,lower down1 however1 near ,los ,hornillos ,r1 there is a well-marked synclinal axis1 beyond which the strata are inclined at nearly the same angle1 namely from #bj to #cj degrees1 inwards or westward4 ,owing to the amount of denudation which this chain has suffered1 the outline of the gently inclined eastern flank scarcely offers the slightest indication of this synclinal axis4 ,the stratified beds1 which we have hitherto followed across the range1 a little further down are seen to lie1 ,i believe unconformably1 on a broad mountainous band of clay-slate and grauwacke4 ,the strata and laminae of this latter formation1 on the extreme eastern flank1 are generally nearly vertical2 further inwards they become inclined from #de to #hj degrees to the west3 near ,villa ,vicencio ,s there is apparently an anticlinal axis1 but the structure of this outer part of the clay-slate formation is so obscure1 that ,i have not marked the planes of stratification in the section4 ,on the margin of the ,pampas1 some low1 much dislocated spurs of this same formation1 project in a north- easterly line1 in the same oblique manner as do the ridges on the western foot1 and as is so frequently the case with those at the base of the main ,cordillera4 ,i will now describe the nature of the beds1 beginning at the base on the eastern side4 ,first1 for the clay-slate formation3 the slate is generally hard and bluish1 with the laminae coated by minute micaceous scales2 it alternates many times with a coarse-grained1 greenish grauwacke1 containing rounded fragments of quartz and bits of slate in a slightly calcareous basis4 ,the slate in the upper part generally becomes purplish1 and the cleavage so irregular that the whole consists of mere splinters4 ,transverse veins of quartz are numerous4 ,at the ,calera1 some leagues distant1 there is a dark crystalline limestone1 apparently included in this formation4 ,with the exception of the grauwacke being here more abundant1 and the clay-slate less altered1 this formation closely resembles that unconformably underlying the porphyries at the western foot of this same range2 and likewise that alternating with the porphyritic conglomerate in the main ,cordillera4 ,this formation is a considerable one1 and extends several leagues southward to near ,mendoza3 the mountains composed of it rise to a height of about two thousand feet above the edge of the ,pampas1 or about seven thousand feet above the sea4 7,i infer this from the height of ,v4 ,vicencio1 which was ascertained by ,mr4 ,miers to be #e1cbh feet above the sea47 ,secondly3 the most usual bed on the clay-slate is a coarse1 white1 slightly calcareous conglomerate1 of no great thickness1 including broken crystals of feldspar1 grains of quartz1 and numerous pebbles of brecciated claystone porphyry1 but without any pebbles of the underlying clay-slate4 ,i nowhere saw the actual junction between this bed and the clay-slate1 though ,i spent a whole day in endeavouring to discover their relations4 ,in some places ,i distinctly saw the white conglomerate and overlying beds inclined at from #be to #cj degrees to the west1 and at the bottom of the same mountain1 the clay-slate and grauwacke inclined to the same point1 but at an angle from #gj to #hj degrees3 in one instance1 the clay-slate dipped not only at a different angle1 but to a different point from the overlying formation4 ,in these cases the two formations certainly appeared quite unconformable3 moreover1 ,i found in the clay-slate one great1 vertical1 dike-like fissure1 filled up with an indurated whitish tuff1 quite similar to some of the upper beds presently to be described2 and this shows that the clay-slate must have been consolidated and dislocated before their deposition4 ,on the other hand1 the stratification of the slate and grauwacke1 in some cases gradually and entirely disappeared in approaching the overlying white conglomerate2 in other cases the stratification of the two formations became strictly conformable2 and again in other cases1 there was some tolerably well characterised clay-slate lying above the conglomerate4 7,the coarse1 mechanical structure of many grauwackes has always appeared to me a difficulty2 for the texture of the associated clay-slate and the nature of the embedded organic remains where present1 indicate that the whole has been a deep-water deposit4 ,whence have the sometimes included angular fragments of clay-slate1 and the rounded masses of quartz and other rocks1 been derived8 ,many deep-water limestones1 it is well known1 have been brecciated1 and then firmly recemented47 ,the most probable conclusion appears to be1 that after the clay-slate formation had been dislocated and tilted1 but whilst under the sea1 a fresh and more recent deposition of clay-slate took place1 on which the white conglomerate was conformably deposited1 with here and there a thin intercalated bed of clay-slate4 ,on this view the white conglomerates and the presently to be described tuffs and lavas are really unconformable to the main part of the clay-slate2 and this1 as we have seen1 certainly is the case with the clay-stone lavas in the valley of ,canota1 at the western and opposite base of the range4 ,thirdly3 on the white conglomerate1 strata several hundred feet in thickness are superimposed1 varying much in nature in short distances3 the commonest variety is a white1 much indurated tuff1 sometimes slightly calcareous1 with ferruginous spots and water-lines1 often passing into whitish or purplish compact1 fine-grained grit or sandstones2 other varieties become semi-porcellanic1 and tinted faint green or blue2 others pass into an indurated shale3 most of these varieties are easily fusible4 ,fourthly3 a bed1 about one hundred feet thick of a compact1 partially columnar1 pale-grey1 feldspathic lava1 stained with iron1 including very numerous crystals of opaque feldspar1 and with some crystallised and disseminated calcareous matter4 ,the tufaceous stratum on which this feldspathic lava rests is much hardened1 stained purple1 and has a spherico-concretionary structure2 it here contains a good many pebbles of claystone porphyry4 ,fifthly3 thin beds1 #djj feet in thickness1 varying much in nature1 consisting of white and ferruginous tuffs1 in some parts having a concretionary structure1 in others containing rounded grains and a few pebbles of quartz2 also passing into hard gritstones and into greenish mudstones3 there is1 also1 much of a bluish-grey and green semi-porcellanic stone4 ,sixthly3 a volcanic stratum1 #bej feet in thickness1 of so varying a nature that ,i do not believe a score of specimens would show all the varieties2 much is highly amygdaloidal1 much compact2 there are greenish1 blackish1 purplish1 and grey varieties1 rarely including crystals of green augite and minute acicular ones of feldspar1 but often crystals and amygdaloidal masses of white1 red1 and black carbonate of lime4 ,some of the blackish varieties of this rock have a conchoidal fracture and resemble basalt2 others have an irregular fracture4 ,some of the grey and purplish varieties are thickly speckled with green earth and with white crystalline carbonate of lime2 others are largely amygdaloidal with green earth and calcareous spar4 ,again1 other earthy varieties1 of greenish1 purplish and grey tints1 contain much iron1 and are almost half composed of amygdaloidal balls of dark brown bole1 of a whitish indurated feldspathic matter1 of bright green earth1 of agate1 and of black and white crystallised carbonate of lime4 ,all these varieties are easily fusible4 ,viewed from a distance1 the line of junction with the underlying semi-porcellanic strata was distinct2 but when examined closely1 it was impossible to point out within a foot where the lava ended and where the sedimentary mass began3 the rock at the time of junction was in most places hard1 of a bright green colour1 and abounded with irregular amygdaloidal masses of ferruginous and pure calcareous spar1 and of agate4 ,seventhly3 strata1 eighty feet in thickness1 of various indurated tuffs1 as before2 many of the varieties have a fine basis including rather coarse extraneous particles2 some of them are compact and semi-porcellanic1 and include vegetable impressions4 ,eighthly3 a bed1 about fifty feet thick1 of greenish-grey1 compact1 feldspathic lava1 with numerous small crystals of opaque feldspar1 black augite1 and oxide of iron4 ,the junction with the bed on which it rested1 was ill defined2 balls and masses of the feldspathic rock being enclosed in much altered tuff4 ,ninthly3 indurated tuffs1 as before4 ,tenthly3 a conformable layer1 less than two feet in thickness1 of pitchstone1 generally brecciated1 and traversed by veins of agate and of carbonate of lime3 parts are composed of apparently concretionary fragments of a more perfect variety1 arranged in horizontal lines in a less perfectly characterised variety4 ,i have much difficulty in believing that this thin layer of pitchstone flowed as lava4 ,eleventhly3 sedimentary and tufaceous beds as before1 passing into sandstone1 including some conglomerate3 the pebbles in the latter are of claystone porphyry1 well rounded1 and some as large as cricket-balls4 ,twelfthly3 a bed of compact1 sonorous1 feldspathic lava1 like that of bed ,no4 #h1 divided by numerous joints into large angular blocks4 ,thirteenthly3 sedimentary beds as before4 ,fourteenthly3 a thick bed of greenish or greyish black1 compact basalt 7fusing into a black enamel71 with small crystals1 occasionally distinguishable1 of feldspar and augite3 the junction with the underlying sedimentary bed1 differently from that in most of the foregoing streams1 here was quite distinct3--the lava and tufaceous matter preserving their perfect characters within two inches of each other4 ,this rock closely resembles certain parts of that varied and singular lava-stream ,no4 #f2 it likewise resembles1 as we shall immediately see1 many of the great upper beds on the western flank and on the summit of this range4 ,the pile of strata here described attains a great thickness2 and above the last-mentioned volcanic stratum1 there were several other great tufaceous beds alternating with submarine lavas1 which ,i had not time to examine2 but a corresponding series1 several thousand feet in thickness1 is well exhibited on the crest and western flank of the range4 ,most of the lava- streams on the western side are of a jet-black colour and basaltic nature2 they are either compact and fine-grained1 including minute crystals of augite and feldspar1 or they are coarse-grained and abound with rather large coppery-brown crystals of an augitic mineral4 7,very easily fusible into a jet-black bead1 attracted by the magnet3 the crystals are too much tarnished to be measured by the goniometer47 ,another variety was of a dull- red colour1 having a claystone brecciated basis1 including specks of oxide of iron and of calcareous spar1 and amygdaloidal with green earth3 there were apparently several other varieties4 ,these submarine lavas often exhibit a spheroidal1 and sometimes an imperfect columnar structure3 their upper junctions are much more clearly defined than their lower junctions2 but the latter are not so much blended into the underlying sedimentary beds as is the case in the eastern flank4 ,on the crest and western flank of the range1 the streams1 viewed as a whole1 are mostly basaltic2 whilst those on the eastern side1 which stand lower in the series1 are1 as we have seen1 mostly feldspathic4 ,the sedimentary strata alternating with the lavas on the crest and western side1 are of an almost infinitely varying nature2 but a large proportion of them closely resemble those already described on the eastern flank3 there are white and brown1 indurated1 easily fusible tuffs1--some passing into pale blue and green semi-porcellanic rocks1--others into brownish and purplish sandstones and gritstones1 often including grains of quartz1-- others into mudstone containing broken crystals and particles of rock1 and occasionally single large pebbles4 ,there was one stratum of a bright red1 coarse1 volcanic gritstone2 another of conglomerate2 another of a black1 indurated1 carbonaceous shale marked with imperfect vegetable impressions2 this latter bed1 which was thin1 rested on a submarine lava1 and followed all the considerable inequalities of its upper surface4 ,mr4 ,miers states that coal has been found in this range4 ,lastly1 there was a bed 7like ,no4 #aj on the eastern flank7 evidently of sedimentary origin1 and remarkable from closely approaching in character to an imperfect pitchstone1 and from including extremely thin layers of perfect pitchstone1 as well as nodules and irregular fragments 7but not resembling extraneous fragments7 of this same rock arranged in horizontal lines3 ,i conceive that this bed1 which is only a few feet in thickness1 must have assumed its present state through metamorphic and concretionary action4 ,most of these sedimentary strata are much indurated1 and no doubt have been partially metamorphosed3 many of them are extraordinarily heavy and compact2 others have agate and crystalline carbonate of lime disseminated throughout them4 ,some of the beds exhibit a singular concretionary arrangement1 with the curves determined by the lines of fissure4 ,there are many veins of agate and calcareous spar1 and innumerable ones of iron and other metals1 which have blackened and curiously affected the strata to considerable distances on both sides4 ,many of these tufaceous beds resemble1 with the exception of being more indurated1 the upper beds of the ,great ,patagonian tertiary formation1 especially those variously coloured layers high up the ,river ,santa ,cruz1 and in a remarkable degree the tufaceous formation at the northern end of ,chiloe4 ,i was so much struck with this resemblance1 that ,i particularly looked out for silicified wood1 and found it under the following extraordinary circumstances4 ,high up on this western flank1 at a height estimated at #g1jjj feet above the sea1 in a broken escarpment of thin strata1 composed of compact green gritstone passing into a fine mudstone1 and alternating with layers of coarser1 brownish1 very heavy mudstone1 including broken crystals and particles of rock almost blended together1 ,i counted the stumps of fifty-two trees4 7,for the information of any future traveller1 ,i will describe the spot in detail4 ,proceeding eastward from the ,agua del ,zorro1 and afterwards leaving on the north side of the road a rancho attached to some old goldmines1 you pass through a gully with low but steep rocks on each hand3 the road then bends1 and the ascent becomes steeper4 ,a few hundred yards farther on1 a stone's throw on the south side of the road1 the white calcareous stumps may be seen4 ,the spot is about half a mile east of the ,agua del ,zorro47 ,they projected between two and five feet above the ground1 and stood at exactly right angles to the strata1 which were here inclined at an angle of about #be degrees to the west4 ,eleven of these trees were silicified and well preserved2 ,mr4 ,r4 ,brown has been so kind as to examine the wood when sliced and polished2 he says it is coniferous1 partaking of the characters of the ,araucarian tribe1 with some curious points of affinity with the ,yew4 ,the bark round the trunks must have been circularly furrowed with irregular lines1 for the mudstone round them is thus plainly marked4 ,one cast consisted of dark argillaceous limestone2 and forty of them of coarsely crystallised carbonate of lime1 with cavities lined by quartz crystals3 these latter white calcareous columns do not retain any internal structure1 but their external form plainly shows their origin4 ,all the stumps have nearly the same diameter1 varying from one foot to eighteen inches2 some of them stand within a yard of each other2 they are grouped in a clump within a space of about sixty yards across1 with a few scattered round at the distance of #aej yards4 ,they all stand at about the same level4 ,the longest stump stood seven feet out of the ground3 the roots1 if they are still preserved1 are buried and concealed4 ,no one layer of the mudstone appeared much darker than the others1 as if it had formerly existed as soil1 nor could this be expected1 for the same agents which replaced with silex and lime the wood of the trees1 would naturally have removed all vegetable matter from the soil4 ,besides the fifty-two upright trees1 there were a few fragments1 like broken branches1 horizontally embedded4 ,the surrounding strata are crossed by veins of carbonate of lime1 agate1 and oxide of iron2 and a poor gold vein has been worked not far from the trees4 ,the green and brown mudstone beds including the trees1 are conformably covered by much indurated1 compact1 white or ferruginous tuffs1 which pass upwards into a fine-grained1 purplish sedimentary rock3 these strata1 which1 together1 are from four to five hundred feet in thickness1 rest on a thick bed of submarine lava1 and are conformably covered by another great mass of fine-grained basalt1 which ,i estimated at #a1jjj feet in thickness1 and which probably has been formed by more than one stream4 7,this rock is quite black1 and fuses into a black bead1 attracted strongly by the magnet2 it breaks with a conchoidal fracture2 the included crystals of augite are distinguishable by the naked eye1 but are not perfect enough to be measured3 there are many minute acicular crystals of glassy feldspar47 ,above this mass ,i could clearly distinguish five conformable alternations1 each several hundred feet in thickness1 of stratified sedimentary rocks and lavas1 such as have been previously described4 ,certainly the upright trees have been buried under several thousand feet in thickness of matter1 accumulated under the sea4 ,as the trees obviously must once have grown on dry land1 what an enormous amount of subsidence is thus indicated6 ,nevertheless1 had it not been for the trees there was no appearance which would have led any one even to have conjectured that these strata had subsided4 ,as the land1 moreover1 on which the trees grew1 is formed of subaqueous deposits1 of nearly if not quite equal thickness with the superincumbent strata1 and as these deposits are regularly stratified and fine-grained1 not like the matter thrown up on a sea-beach1 a previous upward movement1 aided no doubt by the great accumulation of lavas and sediment1 is also indicated4 7,at first ,i imagined1 that the strata with the trees might have been accumulated in a lake3 but this seems highly improbable2 for1 first1 a very deep lake was necessary to receive the matter below the trees1 then it must have been drained for their growth1 and afterwards re-formed and made profoundly deep1 so as to receive a subsequent accumulation of matter ,,several ,,thousand feet in thickness4 ,and all this must have taken place necessarily before the formation of the ,uspallata range1 and therefore on the margin of the wide level expanse of the ,pampas6 ,hence ,i conclude1 that it is infinitely more probable that the strata were accumulated under the sea3 the vast amount of denudation1 moreover1 which this range has suffered1 as shown by the wide valleys1 by the exposure of the very trees and by other appearances1 could have been effected1 ,i conceive1 only by the long-continued action of the sea2 and this shows that the range was either upheaved from under the sea1 or subsequently let down into it4 ,from the natural manner in which the stumps 7fifty-two in number7 are ,,grouped ,,in ,a ,,clump1 and from their all standing vertically to the strata1 it is superfluous to speculate on the chance of the trees having been drifted from adjoining land1 and deposited upright3 ,i may1 however1 mention that the late ,dr4 ,malcolmson assured me1 that he once met in the ,indian ,ocean1 fifty miles from land1 several cocoa-nut trees floating upright1 owing to their roots being loaded with earth47 ,in nearly the middle of the range1 there are some hills ,q1 before alluded to1 formed of a kind of granite externally resembling andesite1 and consisting of a white1 imperfectly granular1 feldspathic basis1 including some perfect crystals apparently of albite 7but ,i was unable to measure them71 much black mica1 epidote in veins1 and very little or no quartz4 ,numerous small veins branch from this rock into the surrounding strata2 and it is a singular fact that these veins1 though composed of the same kind of feldspar and small scales of mica as in the solid rock1 abound with innumerable minute ,,rounded grains of quartz3 in the veins or dikes also1 branching from the great granitic axis in the peninsula of ,tres ,montes1 ,i observed that quartz was more abundant in them than in the main rock3 ,i have heard of other analogous cases3 can we account for this fact1 by the long-continued vicinity of quartz when cooling1 and by its having been thus more easily sucked into fissures than the other constituent minerals of granite8 7,see a paper by ,m4 ,elie de ,beaumont1 8,soc4 ,philomath40 ,may #ahci 8,l',institut40 #ahci page #afa47 ,the strata encasing the flanks of these granitic or andesite masses1 and forming a thick cap on one of their summits1 appear originally to have been of the same tufaceous nature with the beds already described1 but they are now changed into porcellanic1 jaspery1 and crystalline rocks1 and into others of a white colour with a harsh texture1 and having a siliceous aspect1 though really of a feldspathic nature and fusible4 ,both the granitic intrusive masses and the encasing strata are penetrated by innumerable metallic veins1 mostly ferruginous and auriferous1 but some containing copper-pyrites and a few silver3 near the veins1 the rocks are blackened as if blasted by gunpowder4 ,the strata are only slightly dislocated close round these hills1 and hence1 perhaps1 it may be inferred that the granitic masses form only the projecting points of a broad continuous axis-dome1 which has given to the upper parts of this range its anticlinal structure4 ,,concluding ,,remarks ,,on ,,the ,,uspallata ,,range4 ,i will not attempt to estimate the total thickness of the pile of strata forming this range1 but it must amount to many thousand feet4 ,the sedimentary and tufaceous beds have throughout a general similarity1 though with infinite variations4 ,the submarine lavas in the lower part of the series are mostly feldspathic1 whilst in the upper part1 on the summit and western flank1 they are mostly basaltic4 ,we are thus reminded of the relative position in most recent volcanic districts of the trachytic and basaltic lavas1--the latter from their greater weight having sunk to a lower level in the earth's crust1 and having consequently been erupted at a later period over the lighter and upper lavas of the trachytic series4 7,see on this subject1 8,volcanic ,islands0 etc4 by the ,author47 ,both the basaltic and feldspathic submarine streams are very compact2 none being vesicular1 and only a few amygdaloidal3 the effects which some of them1 especially those low in the series1 have produced on the tufaceous beds over which they have flowed is highly curious4 ,independently of this local metamorphic action1 all the strata undoubtedly display an indurated and altered character2 and all the rocks of this range--the lavas1 the alternating sediments1 the intrusive granite and porphyries1 and the underlying clay- slate--are intersected by metalliferous veins4 ,the lava-strata can often be seen extending for great distances1 conformably with the under and overlying beds2 and it was obvious that they thickened towards the west4 ,hence the points of eruption must have been situated westward of the present range1 in the direction of the main ,cordillera3 as1 however1 the flanks of the ,cordillera are entirely composed of various porphyries1 chiefly claystone and greenstone1 some intrusive1 and others belonging to the porphyritic conglomerate formation1 but all quite unlike these submarine lava-streams1 we must in all probability look to the plain of ,uspallata for the now deeply buried points of eruption4 ,comparing our section of the ,uspallata range with that of the ,cumbre1 we see1 with the exception of the underlying clay-slate1 and perhaps of the intrusive rocks of the axes1 a striking dissimilarity in the strata composing them4 ,the great porphyritic conglomerate formation has not extended as far as this range2 nor have we here any of the gypseous strata1 the magnesian and other limestones1 the red sandstones1 the siliceous beds with pebbles of quartz1 and comparatively little of the conglomerates1 all of which form such vast masses over the basal series in the main ,cordillera4 ,on the other hand1 in the ,cordillera1 we do not find those endless varieties of indurated tuffs1 with their numerous veins and concretionary arrangement1 and those grit and mud stones1 and singular semi-porcellanic rocks1 so abundant in the ,uspallata range4 ,the submarine lavas1 also1 differ considerably2 the feldspathic streams of the ,cordillera contain much mica1 which is absent in those of the ,uspallata range3 in this latter range we have seen on how grand a scale1 basaltic lava has been poured forth1 of which there is not a trace in the ,cordillera4 ,this dissimilarity is the more striking1 considering that these two parallel chains are separated by a plain only between ten and fifteen miles in width2 and that the ,uspallata lavas1 as well as no doubt the alternating tufaceous beds1 have proceeded from the west1 from points apparently between the two ranges4 ,to imagine that these two piles of strata were contemporaneously deposited in two closely adjoining1 very deep1 submarine areas1 separated from each other by a lofty ridge1 where a plain now extends1 would be a gratuitous hypothesis4 ,and had they been contemporaneously deposited1 without any such dividing ridge1 surely some of the gypseous and other sedimentary matter forming such immensely thick masses in the ,cordillera1 would have extended this short distance eastwards2 and surely some of the ,uspallata tuffs and basalts also accumulated to so great a thickness1 would have extended a little westward4 ,hence ,i conclude1 that it is far from probable that these two series are not contemporaneous2 but that the strata of one of the chains were deposited1 and even the chain itself uplifted1 before the formation of the other3--which chain1 then1 is the oldest8 ,considering that in the ,uspallata range the lowest strata on the western flank lie unconformably on the clay- slate1 as probably is the case with those on the eastern flank1 whereas in the ,cordillera all the overlying strata lie conformably on this formation3--considering that in the ,uspallata range some of the beds1 both low down and high up in the series1 are marked with vegetable impressions1 showing the continued existence of neighbouring land2--considering the close general resemblance between the deposits of this range and those of tertiary origin in several parts of the continent2--and lastly1 even considering the lesser height and outlying position of the ,uspallata range1--,i conclude that the strata composing it are in all probability of subsequent origin1 and that they were accumulated at a period when a deep sea studded with submarine volcanoes washed the eastern base of the already partially elevated ,cordillera4 ,this conclusion is of much importance1 for we have seen that in the ,cordillera1 during the deposition of the ,neocomian strata1 the bed of the sea must have subsided many thousand feet3 we now learn that at a later period an adjoining area first received a great accumulation of strata1 and was upheaved into land on which coniferous trees grew1 and that this area then subsided several thousand feet to receive the superincumbent submarine strata1 afterwards being broken up1 denuded1 and elevated in mass to its present height4 ,i am strengthened in this conclusion of there having been two distinct1 great periods of subsidence1 by reflecting on the thick mass of coarse stratified conglomerate in the valley of ,tenuyan1 between the ,peuquenes and ,portillo lines2 for the accumulation of this mass seems to me1 as previously remarked1 almost necessarily to have required a prolonged subsidence2 and this subsidence1 from the pebbles in the conglomerate having been to a great extent derived from the gypseous or ,neocomian strata of the ,peuquenes line1 we know must have been quite distinct from1 and subsequent to1 that sinking movement which probably accompanied the deposition of the ,peuquenes strata1 and which certainly accompanied the deposition of the equivalent beds near the ,puente del ,inca1 in this line of section4 ,the ,uspallata chain corresponds in geographical position1 though on a small scale1 with the ,portillo line2 and its clay-slate formation is probably the equivalent of the mica-schist of the ,portillo1 there metamorphosed by the old white granites and syenites4 ,the coloured beds under the conglomerate in the valley of ,tenuyan1 of which traces are seen on the crest of the ,portillo1 and even the conglomerate itself1 may perhaps be synchronous with the tufaceous beds and submarine lavas of the ,uspallata range2 an open sea and volcanic action in the latter case1 and a confined channel between two bordering chains of islets in the former case1 having been sufficient to account for the mineralogical dissimilarity of the two series4 ,from this correspondence between the ,uspallata and ,portillo ranges1 perhaps in age and certainly in geographical position1 one is tempted to consider the one range as the prolongation of the other2 but their axes are formed of totally different intrusive rocks2 and we have traced the apparent continuation of the red granite of the ,portillo in the red porphyries diverging into the main ,cordillera4 ,whether the axis of the ,uspallata range was injected before1 or as perhaps is more probable1 after that of the ,portillo line1 ,i will not pretend to decide2 but it is well to remember that the highly inclined lava-streams on the eastern flank of the ,portillo line1 prove that its angular upheavement was not a single and sudden event2 and therefore that the anticlinal elevation of the ,uspallata range may have been contemporaneous with some of the later angular movements by which the gigantic ,portillo range gained its present height above the adjoining plain4 ,,chapter ,,viii4 ,,northern ,,chile4 ,,conclusion4 ,section from ,illapel to ,combarbala2 gypseous formation with silicified wood4--,panuncillo4--,coquimbo2 mines of ,arqueros2 section up valley2 fossils4--,guasco1 fossils of4--,copiapo1 section up valley2 ,las ,amolanas1 silicified wood4--,conglomerates1 nature of former land1 fossils1 thickness of strata1 great subsidence4--,valley of ,despoblado1 fossils1 tufaceous deposit1 complicated dislocations of4--,relations between ancient orifices of eruption and subsequent axes of injection4--,iquique1 ,peru1 fossils of1 salt-deposits4--,metalliferous veins4--,summary on the porphyritic conglomerate and gypseous formations4--,great subsidence with partial elevations during the cretaceo-oolitic period4--,on the elevation and structure of the ,cordillera4--,recapitulation on the tertiary series4--,relation between movements of subsidence and volcanic action4--,pampean formation4--,recent elevatory movements4--,long-continued volcanic action in the ,cordillera4--,conclusion4 ,,valparaiso ,,to ,,coquimbo4 ,i have already described the general nature of the rocks in the low country north of ,valparaiso1 consisting of granites1 syenites1 greenstones1 and altered feldspathic clay-slate4 ,near ,coquimbo there is much hornblendic rock and various dusky-coloured porphyries4 ,i will describe only one section in this district1 namely1 from near ,illapel in a ,n4,e4 line to the mines of ,los ,hornos1 and thence in a north by east direction to ,combarbala1 at the foot of the main ,cordillera4 ,near ,illapel1 after passing for some distance over granite1 andesite1 and andesitic porphyry1 we come to a greenish stratified feldspathic rock1 which ,i believe is altered clay-slate1 conformably capped by porphyries and porphyritic conglomerate of great thickness1 dipping at an average angle of #bj degrees to ,n4,e4 by ,n4 ,the uppermost beds consist of conglomerates and sandstone only a little metamorphosed1 and conformably covered by a gypseous formation of very great thickness1 but much denuded4 ,this gypseous formation1 where first met with1 lies in a broad valley or basin1 a little southward of the mines of ,los ,hornos3 the lower half alone contains gypsum1 not in great masses as in the ,cordillera1 but in innumerable thin layers1 seldom more than an inch or two in thickness4 ,the gypsum is either opaque or transparent1 and is associated with carbonate of lime4 ,the layers alternate with numerous varying ones of a calcareous clay-shale 7with strong aluminous odour1 adhering to the tongue1 easily fusible into a pale green glass71 more or less indurated1 either earthy and cream-coloured1 or greenish and hard4 ,the more indurated varieties have a compact1 homogeneous1 almost crystalline fracture1 and contain granules of crystallised oxide of iron4 ,some of the varieties almost resemble honestones4 ,there is also a little black1 hardly fusible1 siliceo- calcareous clay-slate1 like some of the varieties alternating with gypsum on the ,peuquenes range4 ,the upper half of this gypseous formation is mainly formed of the same calcareous clay-shale rock1 but without any gypsum1 and varying extremely in nature3 it passes from a soft1 coarse1 earthy1 ferruginous state1 including particles of quartz1 into compact claystones with crystallised oxide of iron1--into porcellanic layers1 alternating with seams of calcareous matter1--and into green porcelain-jasper1 excessively hard1 but easily fusible4 ,strata of this nature alternate with much black and brown siliceo-calcareous slate1 remarkable from the wonderful number of huge embedded logs of silicified wood4 ,this wood1 according to ,mr4 ,r4 ,brown1 is 7judging from several specimens7 all coniferous4 ,some of the layers of the black siliceous slate contained irregular angular fragments of imperfect pitchstone1 which ,i believe1 as in the ,uspallata range1 has originated in a metamorphic process4 ,there was one bed of a marly tufaceous nature1 and of little specific gravity4 ,veins of agate and calcareous spar are numerous4 ,the whole of this gypseous formation1 especially the upper half1 has been injected1 metamorphosed1 and locally contorted by numerous hillocks of intrusive porphyries crowded together in an extraordinary manner4 ,these hillocks consist of purple claystone and of various other porphyries1 and of much white feldspathic greenstone passing into andesite2 this latter variety included in one case crystals of orthitic and albitic feldspar touching each other1 and others of hornblende1 chlorite1 and epidote4 ,the strata surrounding these intrusive hillocks at the mines of ,los ,hornos1 are intersected by many veins of copper-pyrites1 associated with much micaceous iron-ore1 and by some of gold3 in the neighbourhood of these veins the rocks are blackened and much altered4 ,the gypsum near the intrusive masses is always opaque4 ,one of these hillocks of porphyry was capped by some stratified porphyritic conglomerate1 which must have been brought up from below1 through the whole immense thickness of the overlying gypseous formation4 ,the lower beds of the gypseous formation resemble the corresponding and probably contemporaneous strata of the main ,cordillera2 whilst the upper beds in several respects resemble those of the ,uspallata chain1 and possibly may be contemporaneous with them2 for ,i have endeavoured to show that the ,uspallata beds were accumulated subsequently to the gypseous or ,neocomian formations of the ,cordillera4 ,this pile of strata dips at an angle of about #bj degrees to ,n4,e4 by ,n41 close up to the foot of the ,cuesta de ,los ,hornos1 a crooked range of mountains formed of intrusive rocks of the same nature with the above described hillocks4 ,only in one or two places1 on this south-eastern side of the range1 ,i noticed a narrow fringe of the upper gypseous strata brushed up and inclined south-eastward from it4 ,on its north-eastern flank1 and likewise on a few of the summits1 the stratified porphyritic conglomerate is inclined ,n4,e43 so that1 if we disregard the very narrow anticlinal fringe of gypseous strata at its ,s4,e4 foot1 this range forms a second uniclinal axis of elevation4 ,proceeding in a north-by-east direction to the village of ,combarbala1 we come to a third escarpment of the porphyritic conglomerate1 dipping eastwards1 and forming the outer range of the main ,cordillera4 ,the lower beds were here more jaspery than usual1 and they included some white cherty strata and red sandstones1 alternating with purple claystone porphyry4 ,higher up in the ,cordillera there appeared to be a line of andesitic rocks2 and beyond them1 a fourth escarpment of the porphyritic conglomerate1 again dipping eastwards or inwards4 ,the overlying gypseous strata1 if they ever existed here1 have been entirely removed4 ,,copper ,,mines ,,of ,,panuncillo4 ,from ,combarbala to ,coquimbo1 ,i traversed the country in a zigzag direction1 crossing and recrossing the porphyritic conglomerate and finding in the granitic districts an unusual number of mountain-masses composed of various intrusive1 porphyritic rocks1 many of them andesitic4 ,one common variety was greenish-black1 with large crystals of blackish albite4 ,at ,panuncillo a short ,n4,n4,w4 and ,s4,s4,e4 ridge1 with a nucleus formed of greenstone and of a slate-coloured porphyry including crystals of glassy feldspar1 deserves notice1 from the very singular nature of the almost vertical strata composing it4 ,these consist chiefly of a finer and coarser granular mixture1 not very compact1 of white carbonate of lime1 of protoxide of iron and of yellowish garnets 7ascertained by ,professor ,miller71 each grain being an almost perfect crystal4 ,some of the varieties consist exclusively of granules of the calcareous spar2 and some contain grains of copper ore1 and1 ,i believe1 of quartz4 ,these strata alternate with a bluish1 compact1 fusible1 feldspathic rock4 ,much of the above granular mixture has1 also1 a pseudo-brecciated structure1 in which fragments are obscurely arranged in planes parallel to those of the stratification1 and are conspicuous on the weathered surfaces4 ,the fragments are angular or rounded1 small or large1 and consist of bluish or reddish compact feldspathic matter1 in which a few acicular crystals of feldspar can sometimes be seen4 ,the fragments often blend at their edges into the surrounding granular mass1 and seem due to a kind of concretionary action4 ,these singular rocks are traversed by many copper veins1 and appear to rest conformably on the granular mixture 7in parts as fine-grained as a sandstone7 of quartz1 mica1 hornblende1 and feldspar2 and this on fine- grained1 common gneiss2 and this on a laminated mass1 composed of pinkish ,,orthitic feldspar1 including a few specks of hornblende2 and lastly1 this on granite1 which together with andesitic rocks1 form the surrounding district4 ,,coquimbo3 ,,mining ,,district ,,of ,,arqueros4 ,at ,coquimbo the porphyritic conglomerate formation approaches nearer to the ,pacific than in any other part of ,chile visited by me1 being separated from the coast by a tract only a few miles broad of the usual plutonic rocks1 with the addition of a porphyry having a red euritic base4 ,in proceeding to the mines of ,arqueros1 the strata of porphyritic conglomerate are at first nearly horizontal1 an unusual circumstance1 and afterwards they dip gently to ,s4,s4,e4 ,after having ascended to a considerable height1 we come to an undulatory district in which the famous silver mines are situated2 my examination was chiefly confined to those of ,s4 ,rosa4 ,most of the rocks in this district are stratified1 dipping in various directions1 and many of them are of so singular a nature1 that at the risk of being tedious ,i must briefly describe them4 ,the commonest variety is a dull-red1 compact1 finely brecciated stone1 containing much iron and innumerable white crystallised particles of carbonate of lime1 and minute extraneous fragments4 ,another variety is almost equally common near ,s4 ,rosa2 it has a bright green1 scanty basis1 including distinct crystals and patches of white carbonate of lime1 and grains of red1 semi-micaceous oxide of iron2 in parts the basis becomes dark green1 and assumes an obscure crystalline arrangement1 and occasionally in parts it becomes soft and slightly translucent like soapstone4 ,these red and green rocks are often quite distinct1 and often pass into each other2 the passage being sometimes affected by a fine brecciated structure1 particles of the red and green matter being mingled together4 ,some of the varieties appear gradually to become porphyritic with feldspar2 and all of them are easily fusible into pale or dark-coloured beads1 strongly attracted by the magnet4 ,i should perhaps have mistaken several of these stratified rocks for submarine lavas1 like some of those described at the ,puente del ,inca1 had ,i not examined1 a few leagues eastward of this point1 a fine series of analogous but less metamorphosed1 sedimentary beds belonging to the gypseous formation1 and probably derived from a volcanic source4 ,this formation is intersected by numerous metalliferous veins1 running1 though irregularly1 ,n4,w4 and ,s4,e41 and generally at right angles to the many dikes4 ,the veins consist of native silver1 of muriate of silver1 an amalgam of silver1 cobalt1 antimony1 and arsenic1 generally embedded in sulphate of barytes4 7,see the ,report on ,m4 ,domeyko's account of those mines1 in the 8,comptes ,rendus0 tome #ad page #efj47 ,i was assured by ,mr4 ,lambert1 that native copper without a trace of silver has been found in the same vein with native silver without a trace of copper4 ,at the mines of ,aristeas1 the silver veins are said to be unproductive as soon as they pass into the green strata1 whereas at ,s4 ,rosa1 only two or three miles distant1 the reverse happens2 and at the time of my visit1 the miners were working through a red stratum1 in the hope of the vein becoming productive in the underlying green sedimentary mass4 ,i have a specimen of one of these green rocks1 with the usual granules of white calcareous spar and red oxide of iron1 abounding with disseminated particles of glittering native and muriate of silver1 yet taken at the distance of one yard from any vein1--a circumstance1 as ,i was assured1 of very rare occurrence4 ,a ,,section ,,eastward1 ,,up ,,the ,,valley ,,of ,,coquimbo4 ,after passing for a few miles over the coast granitic series1 we come to the porphyritic conglomerate1 with its usual characters1 and with some of the beds distinctly displaying their mechanical origin4 ,the strata1 where first met with1 are1 as before stated1 only slightly inclined2 but near the ,hacienda of ,pluclaro1 we come to an anticlinal axis1 with the beds much dislocated and shifted by a great fault1 of which not a trace is externally seen in the outline of the hill4 ,i believe that this anticlinal axis can be traced northwards1 into the district of ,arqueros1 where a conspicuous hill called ,cerro ,blanco1 formed of a harsh1 cream-coloured euritic rock1 including a few crystals of reddish feldspar1 and associated with some purplish claystone porphyry1 seems to fall on a line of elevation4 ,in descending from the ,arqueros district1 ,i crossed on the northern border of the valley1 strata inclined eastward from the ,pluclaro axis3 on the porphyritic conglomerate there rested a mass1 some hundred feet thick1 of brown argillaceous limestone1 in parts crystalline1 and in parts almost composed of ,hippurites ,chilensis1 d',orbigny2 above this came a black calcareous shale1 and on it a red conglomerate4 ,in the brown limestone1 with the ,hippurites1 there was an impression of a ,pecten and a coral1 and great numbers of a large ,gryphaea1 very like1 and1 according to ,professor ,e4 ,forbes1 probably identical with ,g4 ,orientalis1 ,forbes ,,ms41--a cretaceous species 7probably upper greensand7 from ,verdachellum1 in ,southern ,india4 ,these fossils seem to occupy nearly the same position with those at the ,puente del ,inca1--namely1 at the top of the porphyritic conglomerate1 and at the base of the gypseous formation4 ,a little above the ,hacienda of ,pluclaro1 ,i made a detour on the northern side of the valley1 to examine the superincumbent gypseous strata1 which ,i estimated at #f1jjj feet in thickness4 ,the uppermost beds of the porphyritic conglomerate1 on which the gypseous strata conformably rest1 are variously coloured1 with one very singular and beautiful stratum composed of purple pebbles of various kinds of porphyry1 embedded in white calcareous spar1 including cavities lined with bright-green crystallised epidote4 ,the whole pile of strata belonging to both formations is inclined1 apparently from the above-mentioned axis of ,pluclaro1 at an angle of between #bj and #cj degrees to the east4 ,i will here give a section of the principal beds met with in crossing the entire thickness of the gypseous strata4 ,firstly3 above the porphyritic conglomerate formation1 there is a fine- grained1 red1 crystalline sandstone4 ,secondly3 a thick mass of smooth-grained1 calcareo-aluminous1 shaly rock1 often marked with dendritic manganese1 and having1 where most compact1 the external appearance of honestone4 ,it is easily fusible4 ,i shall for the future1 for convenience' sake1 call this variety pseudo-honestone4 ,some of the varieties are quite black when freshly broken1 but all weather into a yellowish-ash coloured1 soft1 earthy substance1 precisely as is the case with the compact shaly rocks of the ,peuquenes range4 ,this stratum is of the same general nature with many of the beds near ,los ,hornos in the ,illapel section4 ,in this second bed1 or in the underlying red sandstone 7for the surface was partially concealed by detritus71 there was a thick mass of gypsum1 having the same mineralogical characters with the great beds described in our sections across the ,cordillera4 ,thirdly3 a thick stratum of fine-grained1 red1 sedimentary matter1 easily fusible into a white glass1 like the basis of claystone porphyry2 but in parts jaspery1 in parts brecciated1 and including crystalline specks of carbonate of lime4 ,in some of the jaspery layers1 and in some of the black siliceous slaty bands1 there were irregular seams of imperfect pitchstone1 undoubtedly of metamorphic origin1 and other seams of brown1 crystalline limestone4 ,here1 also1 were masses1 externally resembling ill-preserved silicified wood4 ,fourthly and fifthly3 calcareous pseudo-honestone2 and a thick stratum concealed by detritus4 ,sixthly3 a thinly stratified mass of bright green1 compact1 smooth-grained1 calcareo-argillaceous stone1 easily fusible1 and emitting a strong aluminous odour3 the whole has a highly angulo-concretionary structure2 and it resembles1 to a certain extent1 some of the upper tufaceo-infusorial deposits of the ,patagonian tertiary formation4 ,it is in its nature allied to our pseudo-honestone1 and it includes well characterised layers of that variety2 and other layers of a pale green1 harder1 and brecciated variety2 and others of red sedimentary matter1 like that of bed ,three4 ,some pebbles of porphyries are embedded in the upper part4 ,seventhly3 red sedimentary matter or sandstone like that of bed ,one1 several hundred feet in thickness1 and including jaspery layers1 often having a finely brecciated structure4 ,eighthly3 white1 much indurated1 almost crystalline tuff1 several hundred feet in thickness1 including rounded grains of quartz and particles of green matter like that of bed ,six4 ,parts pass into a very pale green1 semi- porcellanic stone4 ,ninthly3 red or brown coarse conglomerate1 three or four hundred feet thick1 formed chiefly of pebbles of porphyries1 with volcanic particles1 in an arenaceous1 non-calcareous1 fusible basis3 the upper two feet are arenaceous without any pebbles4 ,tenthly3 the last and uppermost stratum here exhibited1 is a compact1 slate-coloured porphyry1 with numerous elongated crystals of glassy feldspar1 from one hundred and fifty to two hundred feet in thickness2 it lies strictly conformably on the underlying conglomerate1 and is undoubtedly a submarine lava4 ,this great pile of strata has been broken up in several places by intrusive hillocks of purple claystone porphyry1 and by dikes of porphyritic greenstone3 it is said that a few poor metalliferous veins have been discovered here4 ,from the fusible nature and general appearance of the finer-grained strata1 they probably owe their origin 7like the allied beds of the ,uspallata range1 and of the ,upper ,patagonian tertiary formations71 to gentle volcanic eruptions1 and to the abrasion of volcanic rocks4 ,comparing these beds with those in the mining district of ,arqueros1 we see at both places rocks easily fusible1 of the same peculiar bright green and red colours1 containing calcareous matter1 often having a finely brecciated structure1 often passing into each other1 and often alternating together3 hence ,i cannot doubt that the only difference between them1 lies in the ,arqueros beds having been more metamorphosed 7in conformity with their more dislocated and injected condition71 and consequently in the calcareous matter1 oxide of iron and green colouring matter1 having been segregated under a more crystalline form4 ,the strata are inclined1 as before stated1 from #bj to #cj degrees eastward1 towards an irregular north and south chain of andesitic porphyry and of porphyritic greenstone1 where they are abruptly cut off4 ,in the valley of ,coquimbo1 near to the ,h4 of ,gualliguaca1 similar plutonic rocks are met with1 apparently a southern prolongation of the above chain2 and eastward of it we have an escarpment of the porphyritic conglomerate1 with the strata inclined at a small angle eastward1 which makes the third escarpment1 including that nearest the coast4 ,proceeding up the valley we come to another north and south line of granite1 andesite1 and blackish porphyry1 which seem to lie in an irregular trough of the porphyritic conglomerate4 ,again1 on the south side of the ,r4 ,claro1 there are some irregular granitic hills1 which have thrown off the strata of porphyritic conglomerate to the ,n4,w4 by ,w42 but the stratification here has been much disturbed4 ,i did not proceed any farther up the valley1 and this point is about two-thirds of the distance between the ,pacific and the main ,cordillera4 ,i will describe only one other section1 namely1 on the north side of the ,r4 ,claro1 which is interesting from containing fossils3 the strata are much dislocated by faults and dikes1 and are inclined to the north1 towards a mountain of andesite and porphyry1 into which they appear to become almost blended4 ,as the beds approach this mountain1 their inclination increases up to an angle of #gj degrees1 and in the upper part1 the rocks become highly metamorphosed4 ,the lowest bed visible in this section1 is a purplish hard sandstone4 ,secondly1 a bed two or three hundred feet thick1 of a white siliceous sandstone1 with a calcareous cement1 containing seams of slaty sandstone1 and of hard yellowish-brown 7dolomitic87 limestone2 numerous1 well-rounded1 little pebbles of quartz are included in the sandstone4 ,thirdly1 a dark coloured limestone with some quartz pebbles1 from fifty to sixty feet in thickness1 containing numerous silicified shells1 presently to be enumerated4 ,fourthly1 very compact1 calcareous1 jaspery sandstone1 passing into 7fifthly7 a great bed1 several hundred feet thick1 of conglomerate1 composed of pebbles of white1 red1 and purple porphyries1 of sandstone and quartz1 cemented by calcareous matter4 ,i observed that some of the finer parts of this conglomerate were much indurated within a foot of a dike eight feet in width1 and were rendered of a paler colour with the calcareous matter segregated into white crystallised particles2 some parts were stained green from the colouring matter of the dike4 ,sixthly1 a thick mass1 obscurely stratified1 of a red sedimentary stone or sandstone1 full of crystalline calcareous matter1 imperfect crystals of oxide of iron1 and ,i believe of feldspar1 and therefore closely resembling some of the highly metamorphosed beds at ,arqueros3 this bed was capped by1 and appeared to pass in its upper part into1 rocks similarly coloured1 containing calcareous matter1 and abounding with minute crystals1 mostly elongated and glassy1 of reddish albite4 ,seventhly1 a conformable stratum of fine reddish porphyry with large crystals of 7albitic87 feldspar2 probably a submarine lava4 ,eighthly1 another conformable bed of green porphyry1 with specks of green earth and cream-coloured crystals of feldspar4 ,i believe that there are other superincumbent crystalline strata and submarine lavas1 but ,i had not time to examine them4 ,the upper beds in this section probably correspond with parts of the great gypseous formation2 and the lower beds of red sandstone conglomerate and fossiliferous limestone no doubt are the equivalents of the ,hippurite stratum1 seen in descending from ,arqueros to ,pluclaro1 which there lies conformably upon the porphyritic conglomerate formation4 ,the fossils found in the third bed1 consist of3-- ,pecten ,dufreynoyi1 d',orbigny1 8,voyage1 ,part ,pal40 ,this species1 which occurs here in vast numbers1 according to ,m4 ,d',orbigny1 resembles certain cretaceous forms4 ,ostrea hemispherica1 d',orbigny1 8,voyage0 etc4 ,also resembles1 according to the same author1 cretaceous forms4 ,terebratula aenigma1 d',orbigny1 8,voyage0 etc4 7,pl4 #bb ,figures #aj-ab47 ,is allied1 according to ,m4 d',orbigny1 to ,t4 concinna from the ,forest ,marble4 ,a series of this species1 collected in several localities hereafter to be referred to1 has been laid before ,professor ,forbes2 and he informs me that many of the specimens are almost undistinguishable from our oolitic ,t4 tetraedra1 and that the varieties amongst them are such as are found in that variable species4 ,generally speaking1 the ,american specimens of ,t4 aenigma may be distinguished from the ,british ,t4 tetraedra1 by the surface having the ribs sharp and well-defined to the beak1 whilst in the ,british species they become obsolete and smoothed down2 but this difference is not constant4 ,professor ,forbes adds1 that1 possibly1 internal characters may exist1 which would distinguish the ,american species from its ,european allies4 ,spirifer linguiferoides1 ,e4 ,forbes4 ,professor ,forbes states that this species is very near to ,s4 linguifera of ,phillips 7a carboniferous limestone fossil71 but probably distinct4 ,m4 d',orbigny considers it as perhaps indicating the ,jurassic period4 ,ammonites1 imperfect impression of4 ,m4 ,domeyko has sent to ,france a collection of fossils1 which1 ,i presume1 from the description given1 must have come from the neighbourhood of ,arqueros2 they consist of3-- ,pecten ,dufreynoyi1 d',orbigny1 8,voyage0 ,part ,pal4 ,ostrea hemispherica1 d',orbigny1 8,voyage0 ,part ,pal4 ,turritella ,andii1 d',orbigny1 8,voyage0 ,part ,pal4 7,pleurotomaria ,humboldtii of ,von ,buch74 ,hippurites ,chilensis1 d',orbigny1 8,voyage0 ,part ,pal4 ,the specimens of this ,hippurite1 as well as those ,i collected in my descent from ,arqueros1 are very imperfect2 but in ,m4 d',orbigny's opinion they resemble1 as does the ,turritella ,andii1 cretaceous 7upper greensand7 forms4 ,nautilus ,domeykus1 d',orbigny1 8,voyage0 ,part ,pal4 ,terebratula aenigma1 d',orbigny1 8,voyage0 ,part ,pal4 ,terebratula ignaciana1 d',orbigny1 8,voyage0 ,part ,pal4 ,this latter species was found by ,m4 ,domeyko in the same block of limestone with the ,t4 aenigma4 ,according to ,m4 d',orbigny1 it comes near to ,t4 ornithocephala from the ,lias4 ,a series of this species collected at ,guasco1 has been examined by ,professor ,e4 ,forbes1 and he states that it is difficult to distinguish between some of the specimens and the ,t4 hastata from the mountain limestone2 and that it is equally difficult to draw a line between them and some ,marlstone ,terebratulae4 ,without a knowledge of the internal structure1 it is impossible at present to decide on their identity with analogous ,european forms4 ,the remarks given on the several foregoing shells1 show that1 in ,m4 d',orbigny's opinion1 the ,pecten1 ,ostrea1 ,turritella1 and ,hippurite indicate the cretaceous period2 and the ,gryphaea appears to ,professor ,forbes to be identical with a species1 associated in ,southern ,india with unquestionably cretaceous forms4 ,on the other hand1 the two ,terebratulae and the ,spirifer point1 in the opinion both of ,m4 d',orbigny and ,professor ,forbes1 to the oolitic series4 ,hence ,m4 d',orbigny1 not having himself examined this country1 has concluded that there are here two distinct formations2 but the ,spirifer and ,t4 aenigma were certainly included in the same bed with the ,pecten and ,ostrea1 whence ,i extracted them2 and the geologist ,m4 ,domeyko sent home the two ,terebratulae with the other-named shells1 from the same locality1 without specifying that they came from different beds4 ,again1 as we shall presently see1 in a collection of shells given me from ,guasco1 the same species1 and others presenting analogous differences1 are mingled together1 and are in the same condition2 and lastly1 in three places in the valley of ,copiapo1 ,i found some of these same species similarly grouped4 ,hence there cannot be any doubt1 highly curious though the fact be1 that these several fossils1 namely1 the ,hippurites1 ,gryphaea1 ,ostrea1 ,pecten1 ,turritella1 ,nautilus1 two ,terebratulae1 and ,spirifer all belong to the same formation1 which would appear to form a passage between the oolitic and cretaceous systems of ,europe4 ,although aware how unusual the term must sound1 ,i shall1 for convenience' sake1 call this formation cretaceo- oolitic4 ,comparing the sections in this valley of ,coquimbo with those in the ,cordillera described in the last chapter1 and bearing in mind the character of the beds in the intermediate district of ,los ,hornos1 there is certainly a close general mineralogical resemblance between them1 both in the underlying porphyritic conglomerate1 and in the overlying gypseous formation4 ,considering this resemblance1 and that the fossils from the ,puente del ,inca at the base of the gypseous formation1 and throughout the greater part of its entire thickness on the ,peuquenes range1 indicate the ,neocomian period1--that is1 the dawn of the cretaceous system1 or1 as some have believed1 a passage between this latter and the oolitic series--,i conclude that probably the gypseous and associated beds in all the sections hitherto described1 belong to the same great formation1 which ,i have denominated--cretaceo-oolitic4 ,i may add1 before leaving ,coquimbo1 that ,m4 ,gay found in the neighbouring ,cordillera1 at the height of #ad1jjj feet above the sea1 a fossiliferous formation1 including a ,trigonia and ,pholadomya 7,d',orbigny 8,voyage0 ,part ,geolog4 page #bdb472--;both of which genera occur at the ,puente del ,inca4 ,,coquimbo ,,to ,,guasco4 ,the rocks near the coast1 and some way inland1 do not differ from those described northwards of ,valparaiso3 we have much greenstone1 syenite1 feldspathic and jaspery slate1 and grauwackes having a basis like that of claystone2 there are some large tracts of granite1 in which the constituent minerals are sometimes arranged in folia1 thus composing an imperfect gneiss4 ,there are two large districts of mica-schists1 passing into glossy clay-slate1 and resembling the great formation in the ,chonos ,archipelago4 ,in the valley of ,guasco1 an escarpment of porphyritic conglomerate is first seen high up the valley1 about two leagues eastward of the town of ,ballenar4 ,i heard of a great gypseous formation in the ,cordillera2 and a collection of shells made there was given me4 ,these shells are all in the same condition1 and appear to have come from the same bed3 they consist of3-- ,turritella ,andii1 d',orbigny1 8,voyage0 ,part ,pal4 ,pecten ,dufreynoyi1 d',orbigny1 8,voyage0 ,part ,pal4 ,terebatula ignaciana1 d',orbigny1 8,voyage0 ,part ,pal4 ,the relations of these species have been given under the head of ,coquimbo4 ,terebratula aenigma1 d',orbigny1 8,voyage0 ,part ,pal4 ,this shell ,m4 d',orbigny does not consider identical with his ,t4 aenigma1 but near to ,t4 obsoleta4 ,professor ,forbes thinks that it is certainly a variety of ,t4 aenigma3 we shall meet with this variety again at ,copiapo4 ,spirifer ,chilensis1 ,e4 ,forbes4 ,professor ,forbes remarks that this fossil resembles several carboniferous limestone ,spirifers2 and that it is also related to some liassic species1 as ,s4 ,wolcotii4 ,if these shells had been examined independently of the other collections1 they would probably have been considered1 from the characters of the two ,terebratulae1 and from the ,spirifer1 as oolitic2 but considering that the first species1 and according to ,professor ,forbes1 the four first1 are identical with those from ,coquimbo1 the two formations no doubt are the same1 and may1 as ,i have said1 be provisionally called cretaceo-oolitic4 ,,valley ,,of ,,copiapo4 ,the journey from ,guasco to ,copiapo1 owing to the utterly desert nature of the country1 was necessarily so hurried1 that ,i do not consider my notes worth giving4 ,in the valley of ,copiapo some of the sections are very interesting4 ,from the sea to the town of ,copiapo1 a distance estimated at thirty miles1 the mountains are composed of greenstone1 granite1 andesite1 and blackish porphyry1 together with some dusky-green feldspathic rocks1 which ,i believe to be altered clay-slate3 these mountains are crossed by many brown-coloured dikes1 running north and south4 ,above the town1 the main valley runs in a south-east and even more southerly course towards the ,cordillera1 where it is divided into three great ravines1 by the northern one of which1 called ,jolquera1 ,i penetrated for a short distance4 ,the section1 ,section #a_/c in ,plate #a1 gives an eye-sketch of the structure and composition of the mountains on both sides of this valley3 a straight east and west line from the town to the ,cordillera is perhaps not more than thirty miles1 but along the valley the distance is much greater4 ,wherever the valley trended very southerly1 ,i have endeavoured to contract the section into its true proportion4 ,this valley1 ,i may add1 rises much more gently than any other valley which ,i saw in ,chile4 ,to commence with our section1 for a short distance above the town we have hills of the granitic series1 together with some of that rock ,a1 which ,i suspect to be altered clay-slate1 but which ,professor ,g4 ,rose1 judging from specimens collected by ,meyen at ,p4 ,negro1 states is serpentine passing into greenstone4 ,we then come suddenly to the great gypseous formation ,b1 without having passed over1 differently from1 in all the sections hitherto described1 any of the porphyritic conglomerate4 ,the strata are at first either horizontal or gently inclined westward2 then highly inclined in various directions1 and contorted by underlying masses of intrusive rocks2 and lastly1 they have a regular eastward dip1 and form a tolerably well pronounced north and south line of hills4 ,this formation consists of thin strata1 with innumerable alternations1 of black1 calcareous slate-rock1 of calcareo-aluminous stones like those at ,coquimbo1 which ,i have called pseudo-honestones of green jaspery layers1 and of pale-purplish1 calcareous1 soft rotten-stone1 including seams and veins of gypsum4 ,these strata are conformably overlaid by a great thickness of thinly stratified1 compact limestone with included crystals of carbonate of lime4 ,at a place called ,tierra ,amarilla1 at the foot of a mountain thus composed there is a broad vein1 or perhaps stratum1 of a beautiful and curious crystallised mixture1 composed1 according to ,professor ,g4 ,rose1 of sulphate of iron under two forms1 and of the sulphates of copper and alumina 7,meyen's 8,reise0 etc4 ,th4 #a1 s4 #cid473 the section is so obscure that ,i could not make out whether this vein or stratum occurred in the gypseous formation1 or more probably in some underlying masses ,a1 which ,i believe are altered clay-slate4 ,,second ,,axis ,,of ,,elevation4 ,after the gypseous masses ,b1 we come to a line of hills of unstratified porphyry ,c1 which on their eastern side blend into strata of great thickness of porphyritic conglomerate1 dipping eastward4 ,this latter formation1 however1 here has not been nearly so much metamorphosed as in most parts of ,central ,chile2 it is composed of beds of true purple claystone porphyry1 repeatedly alternating with thick beds of purplish-red conglomerate with the well-rounded1 large pebbles of various porphyries1 not blended together4 ,,third ,,axis ,,of ,,elevation4 ,near the ravine of ,los ,hornitos1 there is a well-marked line of elevation1 extending for many miles in a ,n4,n4,e4 and ,s4,s4,w4 direction1 with the strata dipping in most parts 7as in the second axis7 only in one direction1 namely1 eastward at an average angle of between #cj and #dj degrees4 ,close to the mouth of the valley1 however1 there is1 as represented in the section1 a steep and high mountain ,d1 composed of various green and brown intrusive porphyries enveloped with strata1 apparently belonging to the upper parts of the porphyritic conglomerate1 and dipping both eastward and westward4 ,i will describe the section seen on the eastern side of this mountain ,d1 beginning at the base with the lowest bed visible in the porphyritic conglomerate1 and proceeding upwards through the gypseous formation4 ,bed #a consists of reddish and brownish porphyry varying in character1 and in many parts highly amygdaloidal with carbonate of lime1 and with bright green and brown bole4 ,its upper surface is throughout clearly defined1 but the lower surface is in most parts indistinct1 and towards the summit of the mountain ,d quite blended into the intrusive porphyries4 ,bed #b1 a pale lilac1 hard but not heavy stone1 slightly laminated1 including small extraneous fragments1 and imperfect as well as some perfect and glassy crystals of feldspar2 from one hundred and fifty to two hundred feet in thickness4 ,when examining it in situ1 ,i thought it was certainly a true porphyry1 but my specimens now lead me to suspect that it possibly may be a metamorphosed tuff4 ,from its colour it could be traced for a long distance1 overlying in one part1 quite conformably to the porphyry of bed #a1 and in another not distant part1 a very thick mass of conglomerate1 composed of pebbles of a porphyry chiefly like that of bed #a3 this fact shows how the nature of the bottom formerly varied in short horizontal distances4 ,bed #c1 white1 much indurated tuff1 containing minute pebbles1 broken crystals1 and scales of mica1 varies much in thickness4 ,this bed is remarkable from containing many globular and pear-shaped1 externally rusty balls1 from the size of an apple to a man's head1 of very tough1 slate-coloured porphyry1 with imperfect crystals of feldspar3 in shape these balls do not resemble pebbles1 ,,and ,i ,,believe ,,that ,,they ,,are ,,subaqueous ,,volcanic ,,bombs2 they differ from ,,subaerial bombs only in not being vesicular4 ,bed #d2 a dull purplish-red1 hard conglomerate1 with crystallised particles and veins of carbonate of lime1 from three hundred to four hundred feet in thickness4 ,the pebbles are of claystone porphyries of many varieties2 they are tolerably well rounded1 and vary in size from a large apple to a man's head4 ,this bed includes three layers of coarse1 black1 calcareous1 somewhat slaty rock3 the upper part passes into a compact red sandstone4 ,in a formation so highly variable in mineralogical nature1 any division not founded on fossil remains1 must be extremely arbitrary3 nevertheless1 the beds below the last conglomerate may1 in accordance with all the sections hitherto described1 be considered as belonging to the porphyritic conglomerate1 and those above it to the gypseous formation1 marked ,e in the section4 ,the part of the valley in which the following beds are seen is near ,potrero ,seco4 ,bed #e1 compact1 fine-grained1 pale greenish-grey1 non- calcareous1 indurated mudstone1 easily fusible into a pale green and white glass4 ,bed #f1 purplish1 coarse-grained1 hard sandstone1 with broken crystals of feldspar and crystallised particles of carbonate of lime2 it possesses a slightly nodular structure4 ,bed #g1 blackish-grey1 much indurated1 calcareous mudstone1 with extraneous particles of unequal size2 the whole being in parts finely brecciated4 ,in this mass there is a stratum1 twenty feet in thickness1 of impure gypsum4 ,bed #h1 a greenish mudstone1 with several layers of gypsum4 ,bed #i1 a highly indurated1 easily fusible1 white tuff1 thickly mottled with ferruginous matter1 and including some white semi-porcellanic layers1 which are interlaced with ferruginous veins4 ,this stone closely resembles some of the commonest varieties in the ,uspallata chain4 ,bed #aj1 a thick bed of rather bright green1 indurated mudstone or tuff1 with a concretionary nodular structure so strongly developed that the whole mass consists of balls4 ,i will not attempt to estimate the thickness of the strata in the gypseous formation hitherto described1 but it must certainly be very many hundred feet4 ,bed #aa is at least #hjj feet in thickness3 it consists of thin layers of whitish1 greenish1 or more commonly brown1 fine-grained1 indurated tuffs1 which crumble into angular fragments3 some of the layers are semi-porcellanic1 many of them highly ferruginous1 and some are almost composed of carbonate of lime and iron with drusy cavities lined with quartzf-crystals4 ,bed #ab1 dull purplish or greenish or dark-grey1 very compact and much indurated mudstone3 estimated at #a1ejj feet in thickness3 in some parts this rock assumes the character of an imperfect coarse clay-slate2 but viewed under a lens1 the basis always has a mottled appearance1 with the edges of the minute component particles blending together4 ,parts are calcareous1 and there are numerous veins of highly crystalline carbonate of lime charged with iron4 ,the mass has a nodular structure1 and is divided by only a few planes of stratification3 there are1 however1 two layers1 each about eighteen inches thick1 of a dark brown1 finer-grained stone1 having a conchoidal1 semi-porcellanic fracture1 which can be followed with the eye for some miles across the country4 ,i believe this last great bed is covered by other nearly similar alternations2 but the section is here obscured by a tilt from the next porphyritic chain1 presently to be described4 ,i have given this section in detail1 as being illustrative of the general character of the mountains in this neighbourhood2 but it must not be supposed that any one stratum long preserves the same character4 ,at a distance of between only two and three miles the green mudstones and white indurated tuffs are to a great extent replaced by red sandstone and black calcareous shaly rocks1 alternating together4 ,the white indurated tuff1 bed #aa1 here contains little or no gypsum1 whereas on the northern and opposite side of the valley1 it is of much greater thickness and abounds with layers of gypsum1 some of them alternating with thin seams of crystalline carbonate of lime4 ,the uppermost1 dark-coloured1 hard mudstone1 bed #ab1 is in this neighbourhood the most constant stratum4 ,the whole series differs to a considerable extent1 especially in its upper part1 from that met with at ,,bb1 in the lower part of the valley2 nevertheless1 ,i do not doubt that they are equivalents4 ,,fourth ,,axis ,,of ,,elevation 7,,valley ,,of ,,copiapo74 ,this axis is formed of a chain of mountains ,f1 of which the central masses 7near ,la ,punta7 consist of andesite containing green hornblende and coppery mica1 and the outer masses of greenish and black porphyries1 together with some fine lilac-coloured claystone porphyry2 all these porphyries being injected and broken up by small hummocks of andesite4 ,the central great mass of this latter rock1 is covered on the eastern side by a black1 fine-grained1 highly micaceous slate1 which1 together with the succeeding mountains of porphyry1 are traversed by numerous white dikes1 branching from the andesite1 and some of them extending in straight lines1 to a distance of at least two miles4 ,the mountains of porphyry eastward of the micaceous schist soon1 but gradually1 assume 7as observed in so many other cases7 a stratified structure1 and can then be recognised as a part of the porphyritic conglomerate formation4 ,these strata ,g are inclined at a high angle to the ,s4,e41 and form a mass from fifteen hundred to two thousand feet in thickness4 ,the gypseous masses to the west already described1 dip directly towards this axis1 with the strata only in a few places 7one of which is represented in the section7 thrown from it3 hence this fourth axis is mainly uniclinal towards the ,s4,e41 and just like our third axis1 only locally anticlinal4 ,the above strata of porphyritic conglomerate ,g with their south-eastward dip1 come abruptly up against beds of the gypseous formation ,h1 which are gently1 but irregularly1 inclined westward3 so that there is here a synclinal axis and great fault4 ,further up the valley1 here running nearly north and south1 the gypseous formation is prolonged for some distance2 but the stratification is unintelligible1 the whole being broken up by faults1 dikes1 and metalliferous veins4 ,the strata consist chiefly of red calcareous sandstones1 with numerous veins in the place of layers1 of gypsum2 the sandstone is associated with some black calcareous slate-rock1 and with green pseudo-honestones1 passing into porcelain-jasper4 ,still further up the valley1 near ,las ,amolanas ,i1 the gypseous strata become more regular1 dipping at an angle of between #cj and #dj degrees to ,w4,s4,w41 and conformably overlying1 near the mouth of the ravine of ,jolquera1 strata ,k of porphyritic conglomerate4 ,the whole series has been tilted by a partially concealed axis ,l1 of granite1 andesite1 and a granitic mixture of white feldspar1 quartz1 and oxide of iron4 ,,fifth ,,axis ,,of ,,elevation 7,,valley ,,of ,,copiapo1 ,,near ,,los ,,amolanas74 ,i will describe in some detail the beds ,i seen here1 which1 as just stated1 dip to ,w4,s4,w41 at an angle of from #cj to #dj degrees4 ,i had not time to examine the underlying porphyritic conglomerate1 of which the lowest beds1 as seen at the mouth of the ,jolquera1 are highly compact1 with crystals of red oxide of iron2 and ,i am not prepared to say whether they are chiefly of volcanic or metamorphic origin4 ,on these beds there rests a coarse purplish conglomerate1 very little metamorphosed1 composed of pebbles of porphyry1 but remarkable from containing one pebble of granite2--of which fact no instance has occurred in the sections hitherto described4 ,above this conglomerate1 there is a black siliceous claystone1 and above it numerous alternations of dark-purplish and green porphyries1 which may be considered as the uppermost limit of the porphyritic conglomerate formation4 ,above these porphyries comes a coarse1 arenaceous conglomerate1 the lower half white and the upper half of a pink colour1 composed chiefly of pebbles of various porphyries1 but with some of red sandstone and jaspery rocks4 ,in some of the more arenaceous parts of the conglomerate1 there was an oblique or current lamination2 a circumstance which ,i did not elsewhere observe4 ,above this conglomerate1 there is a vast thickness of thinly stratified1 pale-yellowish1 siliceous sandstone1 passing into a granular quartz-rock1 used for grindstones 7hence the name of the place ,las ,amolanas71 and certainly belonging to the gypseous formation1 as does probably the immediately underlying conglomerate4 ,in this yellowish sandstone there are layers of white and pale-red siliceous conglomerate2 other layers with small1 well-rounded pebbles of white quartz1 like the bed at the ,r4 ,claro at ,coquimbo2 others of a greenish1 fine-grained1 less siliceous stone1 somewhat resembling the pseudo-honestones lower down the valley2 and lastly1 others of a black calcareous shale-rock4 ,in one of the layers of conglomerate1 there was embedded a fragment of mica-slate1 of which this is the first instance2 hence perhaps1 it is from a formation of mica-slate1 that the numerous small pebbles of quartz1 both here and at ,coquimbo1 have been derived4 ,not only does the siliceous sandstone include layers of the black1 thinly stratified1 not fissile1 calcareous shale-rock1 but in one place the whole mass1 especially the upper part1 was1 in a marvellously short horizontal distance1 after frequent alternations1 replaced by it4 ,when this occurred1 a mountain-mass1 several thousand feet in thickness was thus composed2 the black calcareous shale-rock1 however1 always included some layers of the pale-yellowish siliceous sandstone1 of the red conglomerate1 and of the greenish jaspery and pseudo-honestone varieties4 ,it likewise included three or four widely separated layers of a brown limestone1 abounding with shells immediately to be described4 ,this pile of strata was in parts traversed by many veins of gypsum4 ,the calcareous shale-rock1 though when freshly broken quite black1 weathers into an ash- colour3 in which respect and in general appearance1 it perfectly resembles those great fossiliferous beds of the ,peuquenes range1 alternating with gypsum and red sandstone1 described in the last chapter4 ,the shells out of the layers of brown limestone1 included in the black calcareous shale-rock1 which latter1 as just stated1 replaces the white siliceous sandstone1 consist of3-- ,pecten ,dufreynoyi1 d',orbigny1 8,voyage0 ,part ,pal4 ,turritella ,andii1 d',orbigny1 8,voyage0 ,part ,pal4 ,astarte ,darwinii1 ,e4 ,forbes4 ,gryphaea ,darwinii1 ,e4 ,forbes4 ,an intermediate form between ,g4 gigantea and ,g4 incurva4 ,gryphaea nov4 spec481 ,e4 ,forbes4 ,perna ,americana1 ,e4 ,forbes4 ,avicula1 nov4 spec4 ,considered by ,mr4 ,g4,b4 ,sowerby as the ,a4 echinata1 by ,m4 d',orbigny as certainly a new and distinct species1 having a ,jurassic aspect4 ,the specimen has been unfortunately lost4 ,terebratula aenigma1 d',orbigny1 7var4 of do4 ,e4 ,forbes47 ,this is the same variety1 with that from ,guasco1 considered by ,m4 ,d',orbigny to be a distinct species from his ,t4 aenigma1 and related to ,t4 obsoleta4 ,plagiostoma and ,ammonites1 fragments of4 ,the lower layers of the limestone contained thousands of the ,gryphaea2 and the upper ones as many of the ,turritella1 with the ,gryphaea 7nov4 species7 and ,serpulae adhering to them2 in all the layers1 the ,terebratula and fragments of the ,pecten were included4 ,it was evident1 from the manner in which species were grouped together1 that they had lived where now embedded4 ,before making any further remarks1 ,i may state1 that higher up this same valley we shall again meet with a similar association of shells2 and in the great ,despoblado ,valley1 which branches off near the town from that of ,copiapo1 the ,pecten ,dufreynoyi1 some ,gryphites 7,i believe ,g4 ,darwinii71 and the ,,true ,terebratula aenigma of d',orbigny were found together in an equivalent formation1 as will be hereafter seen4 ,a specimen also1 ,i may add1 of the true ,t4 aenigma1 was given me from the neighbourhood of the famous silver mines of ,chanuncillo1 a little south of the valley of the ,copiapo1 and these mines1 from their position1 ,i have no doubt1 lie within the great gypseous formation3 the rocks close to one of the silver veins1 judging from fragments shown me1 resemble those singular metamorphosed deposits from the mining district of ,arqueros near ,coquimbo4 ,i will reiterate the evidence on the association of these several shells in the several localities4 ,,coquimbo4 ,in the same bed1 ,rio ,claro3 ,pecten ,dufreynoyi4 ,ostrea hemispherica4 ,terebratula aenigma4 ,spirifer linguiferoides4 ,same bed1 near ,arqueros3 ,hippurites ,chilensis4 ,gryphaea orientalis4 ,collected by ,m4 ,domeyko from the same locality1 apparently near ,arqueros3 ,terebratula aenigma and ,terebratula ignaciana1 in same block of limestone3 ,pecten ,dufreynoyi4 ,ostrea hemispherica4 ,hippurites ,chilensis4 ,turritella ,andii4 ,nautilus ,domeykus4 ,,guasco4 ,in a collection from the ,cordillera1 given me3 the specimens all in the same condition3 ,pecten ,dufreynoyi4 ,turritella ,andii4 ,terebratula ignaciana4 ,terebratula aenigma1 var4 ,spirifer ,chilensis4 ,,copiapo4 ,mingled together in alternating beds in the main valley of ,copiapo near ,las ,amolanas1 and likewise higher up the valley3 ,pecten ,dufreynoyi4 ,turritella ,andii4 ,terebratula aenigma1 var4 as at ,guasco4 ,astarte ,darwinii4 ,gryphaea ,darwinii4 ,gryphaea nov4 species8 ,perna ,americana4 ,avicula1 nov4 species4 ,main valley of ,copiapo1 apparently same formation with that of ,amolanas3 ,terebratula aenigma 7true74 ,in the same bed1 high up the great lateral valley of the ,despoblado1 in the ravine of ,maricongo3 ,terebratula aenigma 7true74 ,pecten ,dufreynoyi4 ,gryphaea ,darwinii8 ,considering this table1 ,i think it is impossible to doubt that all these fossils belong to the same formation4 ,if1 however1 the species from ,las ,amolanas1 in the ,valley of ,copiapo1 had1 as in the case of those from ,guasco1 been separately examined1 they would probably have been ranked as oolitic2 for1 although no ,spirifers were found here1 all the other species1 with the exception of the ,pecten1 ,turritella1 and ,astarte1 have a more ancient aspect than cretaceous forms4 ,on the other hand1 taking into account the evidence derived from the cretaceous character of these three shells1 and of the ,hippurites1 ,gryphaea orientalis1 and ,ostrea1 from ,coquimbo1 we are driven back to the provisional name already used of cretaceo-oolitic4 ,from geological evidence1 ,i believe this formation to be the equivalent of the ,neocomian beds of the ,cordillera of ,central ,chile4 ,to return to our section near ,las ,amolanas3--,above the yellow siliceous sandstone1 or the equivalent calcareous slate-rock1 with its bands of fossil-shells1 according as the one or other prevails1 there is a pile of strata1 which cannot be less than from two to three thousand feet in thickness1 in main part composed of a coarse1 bright red conglomerate1 with many intercalated beds of red sandstone1 and some of green and other coloured porcelain-jaspery layers4 ,the included pebbles are well-rounded1 varying from the size of an egg to that of a cricket-ball1 with a few larger2 and they consist chiefly of porphyries4 ,the basis of the conglomerate1 as well as some of the alternating thin beds1 are formed of a red1 rather harsh1 easily fusible sandstone1 with crystalline calcareous particles4 ,this whole great pile is remarkable from the thousands of huge1 embedded1 silicified trunks of trees1 one of which was eight feet long1 and another eighteen feet in circumference3 how marvellous it is1 that every vessel in so thick a mass of wood should have been converted into silex6 ,i brought home many specimens1 and all of them1 according to ,mr4 ,r4 ,brown1 present a coniferous structure4 ,above this great conglomerate1 we have from two to three hundred feet in thickness of red sandstone2 and above this1 a stratum of black calcareous slate-rock1 like that which alternates with and replaces the underlying yellowish-white1 siliceous sandstone4 ,close to the junction between this upper black slate-rock and the upper red sandstone1 ,i found the ,gryphaea ,darwinii1 the ,turritella ,andii1 and vast numbers of a bivalve1 too imperfect to be recognised4 ,hence we see that1 as far as the evidence of these two shells serves--and the ,turritella is an eminently characteristic species--the whole thickness of this vast pile of strata belongs to the same age4 ,again1 above the last-mentioned upper red sandstone1 there were several alternations of the black1 calcareous slate-rock2 but ,i was unable to ascend to them4 ,all these uppermost strata1 like the lower ones1 vary extremely in character in short horizontal distances4 ,the gypseous formation1 as here seen1 has a coarser1 more mechanical texture1 and contains much more siliceous matter than the corresponding beds lower down the valley4 ,its total thickness1 together with the upper beds of the porphyritic conglomerate1 ,i estimated at least at #h1jjj feet2 and only a small portion of the porphyritic conglomerate1 which on the eastern flank of the fourth axis of elevation appeared to be from fifteen hundred to two thousand feet thick1 is here included4 ,as corroborative of the great thickness of the gypseous formation1 ,i may mention that in the ,despoblado ,valley 7which branches from the main valley a little above the town of ,copiapo7 ,i found a corresponding pile of red and white sandstones1 and of dark1 calcareous1 semi-jaspery mudstones1 rising from a nearly level surface and thrown into an absolutely vertical position2 so that1 by pacing1 ,i ascertained their thickness to be nearly two thousand seven hundred feet2 taking this as a standard of comparison1 ,i estimated the thickness of the strata ,,above the porphyritic conglomerate at #g1jjj feet4 ,the fossils before enumerated1 from the limestone-layers in the whitish siliceous sandstone1 are now covered1 on the least computation1 by strata from #e1jjj to #f1jjj feet in thickness4 ,professor ,e4 ,forbes thinks that these shells probably lived at a depth of from about #cj to #dj fathoms1 that is from #ahj to #bdj feet2 anyhow1 it is impossible that they could have lived at the depth of from #e1jjj to #f1jjj feet4 ,hence in this case1 as in that of the ,puente del ,inca1 we may safely conclude that the bottom of the sea on which the shells lived1 subsided1 so as to receive the superincumbent submarine strata3 and this subsidence must have taken place during the existence of these shells2 for1 as ,i have shown1 some of them occur high up as well as low down in the series4 ,that the bottom of the sea subsided1 is in harmony with the presence of the layers of coarse1 well- rounded pebbles included throughout this whole pile of strata1 as well as of the great upper mass of conglomerate from #b1jjj to #c1jjj feet thick2 for coarse gravel could hardly have been formed or spread out at the profound depths indicated by the thickness of the strata4 ,the subsidence1 also1 must have been slow to have allowed of this often-recurrent spreading out of the pebbles4 ,moreover1 we shall presently see that the surfaces of some of the streams of porphyritic lava beneath the gypseous formation1 are so highly amygdaloidal that it is scarcely possible to believe that they flowed under the vast pressure of a deep ocean4 ,the conclusion of a great subsidence during the existence of these cretaceo-oolitic fossils1 may1 ,i believe1 be extended to the district of ,coquimbo1 although owing to the fossiliferous beds there not being directly covered by the upper gypseous strata1 which in the section north of the valley are about #f1jjj feet in thickness1 ,i did not there insist on this conclusion4 ,the pebbles in the above conglomerates1 both in the upper and lower beds1 are all well rounded1 and1 though chiefly composed of various porphyries1 there are some of red sandstone and of a jaspery stone1 both like the rocks intercalated in layers in this same gypseous formation2 there was one pebble of mica-slate and some of quartz1 together with many particles of quartz4 ,in these respects there is a wide difference between the gypseous conglomerates and those of the porphyritic-conglomerate formation1 in which latter1 angular and rounded fragments1 almost exclusively composed of porphyries1 are mingled together1 and which1 as already often remarked1 probably were ejected from craters deep under the sea4 ,from these facts ,i conclude1 that during the formation of the conglomerates1 land existed in the neighbourhood1 on the shores of which the innumerable pebbles were rounded and thence dispersed1 and on which the coniferous forests flourished--for it is improbable that so many thousand logs of wood should have drifted from any great distance4 ,this land1 probably islands1 must have been mainly formed of porphyries1 with some mica-slate1 whence the quartz was derived1 and with some red sandstone and jaspery rocks4 ,this latter fact is important1 as it shows that in this district1 even previously to the deposition of the lower gypseous or cretaceo-oolitic beds1 strata of an analogous nature had elsewhere1 no doubt in the more central ranges of the ,cordillera1 been elevated2 thus recalling to our minds the relations of the ,cumbre and ,uspallata chains4 ,having already referred to the great lateral valley of the ,despoblado1 ,i may mention that above the #b1gjj feet of red and white sandstone and dark mudstone1 there is a vast mass of coarse1 hard1 red conglomerate1 some thousand feet in thickness1 which contains much silicified wood1 and evidently corresponds with the great upper conglomerate at ,las ,amolanas3 here1 however1 the conglomerate consists almost exclusively of pebbles of granite1 and of disintegrated crystals of reddish feldspar and quartz firmly recemented together4 ,in this case1 we may conclude that the land whence the pebbles were derived1 and on which the now silicified trees once flourished1 was formed of granite4 ,the mountains near ,las ,amolanas1 composed of the cretaceo-oolitic strata1 are interlaced with dikes like a spider's web1 to an extent which ,i have never seen equalled1 except in the denuded interior of a volcanic crater3 north and south lines1 however1 predominate4 ,these dikes are composed of green1 white1 and blackish rocks1 all porphyritic with feldspar1 and often with large crystals of hornblende4 ,the white varieties approach closely in character to andesite1 which composes as we have seen1 the injected axes of so many of the lines of elevation4 ,some of the green varieties are finely laminated1 parallel to the walls of the dikes4 ,,sixth ,,axis ,,of ,,elevation 7,,valley ,,of ,,copiapo74 ,this axis consists of a broad mountainous mass ,o of andesite1 composed of albite1 brown mica1 and chlorite1 passing into andesitic granite1 with quartz3 on its western side it has thrown off1 at a considerable angle1 a thick mass of stratified porphyries1 including much epidote ,,nn1 and remarkable only from being divided into very thin beds1 as highly amygdaloidal on their surfaces as subaerial lava-streams are often vesicular4 ,this porphyritic formation is conformably covered1 as seen some way up the ravine of ,jolquera1 by a mere remnant of the lower part of the cretaceo-oolitic formation ,,mm1 which in one part encases1 as represented in the coloured section1 the foot of the andesitic axis ,l1 of the already described fifth line1 and in another part entirely conceals it3 in this latter case1 the gypseous or cretaceo-oolitic strata falsely appeared to dip under the porphyritic conglomerate of the fifth axis4 ,the lowest bed of the gypseous formation1 as seen here ,m1 is of yellowish siliceous sandstone1 precisely like that of ,amolanas1 interlaced in parts with veins of gypsum1 and including layers of the black1 calcareous1 non-fissile slate-rock3 the ,turritella ,andii1 ,pecten ,dufreynoyi1 ,terebratula aenigma1 var41 and some ,gryphites were embedded in these layers4 ,the sandstone varies in thickness from only twenty to eighty feet2 and this variation is caused by the inequalities in the upper surface of an underlying stream of purple claystone porphyry4 ,hence the above fossils here lie at the very base of the gypseous or cretaceo-oolitic formation1 and hence they were probably once covered up by strata about seven thousand feet in thickness3 it is1 however1 possible1 though from the nature of all the other sections in this district not probable1 that the porphyritic claystone lava may in this case have invaded a higher level in the series4 ,above the sandstone there is a considerable mass of much indurated1 purplish-black1 calcareous claystone1 allied in nature to the often-mentioned black calcareous slate- rock4 ,eastward of the broad andesitic axis of this sixth line1 and penetrated by many dikes from it1 there is a great formation ,p of mica-schist1 with its usual variations1 and passing in one part into a ferruginous quartz-rock4 ,the folia are curved and highly inclined1 generally dipping eastward4 ,it is probable that this mica-schist is an old formation1 connected with the granitic rocks and metamorphic schists near the coast2 and that the one fragment of mica-slate1 and the pebbles of quartz low down in the gypseous formation at ,las ,amolanas1 have been derived from it4 ,the mica-schist is succeeded by stratified porphyritic conglomerate ,q of great thickness1 dipping eastward with a high inclination3 ,i have included this latter mountain-mass in the same anticlinal axis with the porphyritic streams ,,nn2 but ,i am far from sure that the two masses may not have been independently upheaved4 ,,seventh ,,axis ,,of ,,elevation4 ,proceeding up the ravine1 we come to another mass ,r of andesite2 and beyond this1 we again have a very thick1 stratified porphyritic formation ,s1 dipping at a small angle eastward1 and forming the basal part of the main ,cordillera4 ,i did not ascend the ravine any higher2 but here1 near ,castano1 ,i examined several sections1 of which ,i will not give the details1 only observing1 that the porphyritic beds1 or submarine lavas1 preponderate greatly in bulk over the alternating sedimentary layers1 which have been but little metamorphosed3 these latter consist of fine-grained red tuffs and of whitish volcanic grit-stones1 together with much of a singular1 compact rock1 having an almost crystalline basis1 finely brecciated with red and green fragments1 and occasionally including a few large pebbles4 ,the porphyritic lavas are highly amygdaloidal1 both on their upper and lower surfaces2 they consist chiefly of claystone porphyry1 but with one common variety1 like some of the streams at the ,puente del ,inca1 having a grey mottled basis1 abounding with crystals of red hydrous oxide of iron1 green ones apparently of epidote1 and a few glassy ones of feldspar4 ,this pile of strata differs considerably from the basal strata of the ,cordillera in ,central ,chile1 and may possibly belong to the upper and gypseous series3 ,i saw1 however1 in the bed of the valley1 one fragment of porphyritic breccia-conglomerate1 exactly like those great masses met with in the more southern parts of ,chile4 ,finally1 ,i must observe1 that though ,i have described between the town of ,copiapo and the western flank of the main ,cordillera seven or eight axes of elevation1 extending nearly north and south1 it must not be supposed that they all run continuously for great distances4 ,as was stated to be the case in our sections across the ,cordillera of ,central ,chile1 so here most of the lines of elevation1 with the exception of the first1 third1 and fifth1 are very short4 ,the stratification is everywhere disturbed and intricate2 nowhere have ,i seen more numerous faults and dikes4 ,the whole district1 from the sea to the ,cordillera1 is more or less metalliferous2 and ,i heard of gold1 silver1 copper1 lead1 mercury1 and iron veins4 ,the metamorphic action1 even in the lower strata1 has certainly been far less here than in ,central ,chile4 ,,valley ,,of ,,the ,,despoblado4 ,this great barren valley1 which has already been alluded to1 enters the main valley of ,copiapo a little above the town3 it runs at first northerly1 then ,n4,e41 and more easterly into the ,cordillera2 ,i followed its dreary course to the foot of the first main ridge4 ,i will not give a detailed section1 because it would be essentially similar to that already given1 and because the stratification is exceedingly complicated4 ,after leaving the plutonic hills near the town1 ,i met first1 as in the main valley1 with the gypseous formation1 having the same diversified character as before1 and soon afterwards with masses of porphyritic conglomerate1 about one thousand feet in thickness4 ,in the lower part of this formation there were very thick beds composed of fragments of claystone porphyries1 both angular and rounded1 with the smaller ones partially blended together and the basis rendered porphyritic2 these beds separated distinct streams1 from sixty to eighty feet in thickness1 of claystone lavas4 ,near ,paipote1 also1 there was much true porphyritic breccia-conglomerate3 nevertheless1 few of these masses were metamorphosed to the same degree with the corresponding formation in ,central ,chile4 ,i did not meet in this valley with any true andesite1 but only with imperfect andesitic porphyry1 including large crystals of hornblende3 numerous as have been the varieties of intrusive porphyries already mentioned1 there were here mountains composed of a new kind1 having a compact1 smooth1 cream-coloured basis1 including only a few crystals of feldspar1 and mottled with dendritic spots of oxide of iron4 ,there were also some mountains of a porphyry with a brick-red basis1 containing irregular1 often lens-shaped1 patches of compact feldspar1 and crystals of feldspar1 which latter to my surprise ,i find to be orthite4 ,at the foot of the first ridge of the main ,cordillera1 in the ravine of ,maricongo1 and at an elevation which1 from the extreme coldness and appearance of the vegetation1 ,i estimated at about ten thousand feet1 ,i found beds of white sandstone and of limestone including the ,pecten ,dufreynoyi1 ,terebratula aenigma1 and some ,gryphites4 ,this ridge throws the water on the one hand into the ,pacific1 and on the other1 as ,i was informed1 into a great gravel-covered1 basin-like plain1 including a salt- lake1 and without any drainage-exit4 ,in crossing the ,cordillera by this ,pass1 it is said that three principal ridges must be traversed1 instead of two1 or only one as in ,central ,chile4 ,the crest of this first main ridge and the surrounding mountains1 with the exception of a few lofty pinnacles1 are capped by a great thickness of a horizontally stratified1 tufaceous deposit4 ,the lowest bed is of a pale purple colour1 hard1 fine-grained1 and full of broken crystals of feldspar and scales of mica4 ,the middle bed is coarser1 and less hard1 and hence weathers into very sharp pinnacles2 it includes very small fragments of granite1 and innumerable ones of all sizes of grey vesicular trachyte1 some of which were distinctly rounded4 ,the uppermost bed is about two hundred feet in thickness1 of a darker colour and apparently hard3 but ,i had not time to ascend to it4 ,these three horizontal beds may be seen for the distance of many leagues1 especially westward or in the direction of the ,pacific1 capping the summits of the mountains1 and standing on the opposite sides of the immense valleys at exactly corresponding heights4 ,if united they would form a plain1 inclined very slightly towards the ,pacific2 the beds become thinner in this direction1 and the tuff 7judging from one point to which ,i ascended1 some way down the valley7 finer-grained and of less specific gravity1 though still compact and sonorous under the hammer4 ,the gently inclined1 almost horizontal stratification1 the presence of some rounded pebbles1 and the compactness of the lowest bed1 though rendering it probable1 would not have convinced me that this mass had been of subaqueous origin1 for it is known that volcanic ashes falling on land and moistened by rain often become hard and stratified2 but beds thus originating1 and owing their consolidation to atmospheric moisture1 would have covered almost equally every neighbouring summit1 high and low1 and would not have left those above a certain exact level absolutely bare2 this circumstance seems to me to prove that the volcanic ejections were arrested at their present1 widely extended1 equable level1 and there consolidated by some other means than simple atmospheric moisture2 and this no doubt must have been a sheet of water4 ,a lake at this great height1 and without a barrier on any one side1 is out of the question2 consequently we must conclude that the tufaceous matter was anciently deposited beneath the sea4 ,it was certainly deposited before the excavation of the valleys1 or at least before their final enlargement 7,i have endeavoured to show in my 8,journal0 etc4 7#bnd edition7 page #cee1 that this arid valley was left by the retreating sea1 as the land slowly rose1 in the state in which we now see it472 and ,i may add1 that ,mr4 ,lambert1 a gentleman well acquainted with this country1 informs me1 that in ascending the ravine of ,santandres 7which branches off from the ,despoblado7 he met with streams of lava and much erupted matter capping all the hills of granite and porphyry1 with the exception of some projecting points2 he also remarked that the valleys had been excavated subsequently to these eruptions4 ,this volcanic formation1 which ,i am informed by ,mr4 ,lambert extends far northward1 is of interest1 as typifying what has taken place on a grander scale on the corresponding western side of the ,cordillera of ,peru4 ,under another point of view1 however1 it possesses a far higher interest1 as confirming that conclusion drawn from the structure of the fringes of stratified shingle which are prolonged from the plains at the foot of the ,cordillera far up the valleys1--namely1 that this great range has been elevated in mass to a height of between eight and nine thousand feet 7,i may here mention that on the south side of the main valley of ,copiapo1 near ,potrero ,seco1 the mountains are capped by a thick mass of horizontally stratified shingle1 at a height which ,i estimated at between fifteen hundred and two thousand feet above the bed of the valley4 ,this shingle1 ,i believe1 forms the edge of a wide plain1 which stretches southwards between two mountain ranges472 and now1 judging from this tufaceous deposit1 we may conclude that the horizontal elevation has been in the district of ,copiapo about ten thousand feet4 7,,figure #bd47 ,in the valley of the ,despoblado1 the stratification1 as before remarked has been much disturbed1 and in some points to a greater degree than ,i have anywhere else seen4 ,i will give two cases3 a very thick mass of thinly stratified red sandstone1 including beds of conglomerate1 has been crushed together 7as represented in ,figure #bd7 into a yoke or urn-formed trough1 so that the strata on both sides have been folded inwards3 on the right hand the properly underlying porphyritic claystone conglomerate is seen overlying the sandstone1 but it soon becomes vertical1 and then is inclined towards the trough1 so that the beds radiate like the spokes of a wheel3 on the left hand1 the inverted porphyritic conglomerate also assumes a dip towards the trough1 not gradually1 as on the right hand1 but by means of a vertical fault and synclinal break2 and a little still further on towards the left1 there is a second great oblique fault 7both shown by the arrow- lines71 with the strata dipping to a directly opposite point2 these mountains are intersected by infinitely numerous dikes1 some of which can be seen to rise from hummocks of greenstone1 and can be traced for thousands of feet4 ,in the second case1 two low ridges trend together and unite at the head of a little wedge-shaped valley3 throughout the right- hand ridge1 the strata dip at #de degrees to the east2 in the left-hand ridge1 we have the very same strata and at first with exactly the same dip2 but in following this ridge up the valley1 the strata are seen very regularly to become more and more inclined until they stand vertical1 they then gradually fall over 7the basset edges forming symmetrical serpentine lines along the crest71 till at the very head of the valley they are reversed at an angle of #de degrees3 so that at this point the beds have been turned through an angle of #ace degrees2 and here there is a kind of anticlinal axis1 with the strata on both sides dipping to opposite points at an angle of #de degrees1 but those on the left hand upside down4 ,,on ,,the ,,eruptive ,,sources ,,of ,,the ,,porphyritic ,,claystone ,,and ,,greenstone ,,lavas4 ,in ,central ,chile1 from the extreme metamorphic action1 it is in most parts difficult to distinguish between the streams of porphyritic lava and the porphyritic breccia-conglomerate1 but here1 at ,copiapo1 they are generally perfectly distinct1 and in the ,despoblado1 ,i saw for the first time1 two great strata of purple claystone porphyry1 after having been for a considerable space closely united together1 one above the other1 become separated by a mass of fragmentary matter1 and then both thin out2--the lower one more rapidly than the upper and greater stream4 ,considering the number and thickness of the streams of porphyritic lava1 and the great thickness of the beds of breccia-conglomerate1 there can be little doubt that the sources of eruption must originally have been numerous3 nevertheless1 it is now most difficult even to conjecture the precise point of any one of the ancient submarine craters4 ,i have repeatedly observed mountains of porphyries1 more or less distinctly stratified towards their summits or on their flanks1 without a trace of stratification in their central and basal parts3 in most cases1 ,i believe this is simply due either to the obliterating effects of metamorphic action1 or to such parts having been mainly formed of intrusive porphyries1 or to both causes conjoined2 in some instances1 however1 it appeared to me very probable that the great central unstratified masses of porphyry were the now partially denuded nuclei of the old submarine volcanoes1 and that the stratified parts marked the points whence the streams flowed4 ,in one case alone1 and it was in this ,valley of the ,despoblado1 ,i was able actually to trace a thick stratum of purplish porphyry1 which for a space of some miles conformably overlay the usual alternating beds of breccia-conglomerates and claystone lavas1 until it became united with1 and blended into1 a mountainous mass of various unstratified porphyries4 ,the difficulty of tracing the streams of porphyries to their ancient and doubtless numerous eruptive sources1 may be partly explained by the very general disturbance which the ,cordillera in most parts has suffered2 but ,i strongly suspect that there is a more specific cause1 namely1 ,,that ,,the ,,original ,,points ,,of ,,eruption ,,tend ,,to ,,become ,,the ,,points ,,of ,,injection4 ,this in itself does not seem improbable2 for where the earth's crust has once yielded1 it would be liable to yield again1 though the liquified intrusive matter might not be any longer enabled to reach the submarine surface and flow as lava4 ,i have been led to this conclusion1 from having so frequently observed that1 where part of an unstratified mountain-mass resembled in mineralogical character the adjoining streams or strata1 there were several other kinds of intrusive porphyries and andesitic rocks injected into the same point4 ,as these intrusive mountain-masses form most of the axes-lines in the ,cordillera1 whether anticlinal1 uniclinal1 or synclinal1 and as the main valleys have generally been hollowed out along these lines1 the intrusive masses have generally suffered much denudation4 ,hence they are apt to stand in some degree isolated1 and to be situated at the points where the valleys abruptly bend1 or where the main tributaries enter4 ,on this view of there being a tendency in the old points of eruption to become the points of subsequent injection and disturbance1 and consequently of denudation1 it ceases to be surprising that the streams of lava in the porphyritic claystone conglomerate formation1 and in other analogous cases1 should most rarely be traceable to their actual sources4 ,,iquique1 ,,southern ,,peru4 ,differently from what we have seen throughout ,chile1 the coast here is formed not by the granitic series1 but by an escarpment of the porphyritic conglomerate formation1 between two and three thousand feet in height4 7,the lowest point1 where the road crosses the coast-escarpment1 is #a1ijj feet by the barometer above the level of the sea47 ,i had time only for a very short examination2 the chief part of the escarpment appears to be composed of various reddish and purple1 sometimes laminated1 porphyries1 resembling those of ,chile2 and ,i saw some of the porphyritic breccia-conglomerate2 the stratification appeared but little inclined4 ,the uppermost part1 judging from the rocks near the famous silver mine of ,huantajaya1 consists of laminated1 impure1 argillaceous1 purplish-grey limestone1 associated1 ,i believe1 with some purple sandstone4 7,mr4 ,bollaert has described 8,geological ,proceedings0 volume #b page #eih1 a singular mass of stratified detritus1 gravel1 and sand1 eighty-one yards in thickness1 overlying the limestone1 and abounding with loose masses of silver ore4 ,the miners believe that they can attribute these masses to their proper veins47 ,in the limestone shells are found3 the three following species were given me3-- ,lucina ,americana1 ,e4 ,forbes4 ,terebratula inca1 ,e4 ,forbes4 ,terebratula aenigma1 ,d',orbigny4 ,this latter species we have seen associated with the fossils of which lists have been given in this chapter1 in two places in the valley of ,coquimbo1 and in the ravine of ,maricongo at ,copiapo4 ,considering this fact1 and the superposition of these beds on the porphyritic conglomerate formation2 and1 as we shall immediately see1 from their containing much gypsum1 and from their otherwise close general resemblance in mineralogical nature with the strata described in the valley of ,copiapo1 ,i have little doubt that these fossiliferous beds of ,iquique belong to the great cretaceo-oolitic formation of ,northern ,chile4 ,iquique is situated seven degrees latitude north of ,copiapo2 and ,i may here mention1 that an ,ammonites1 nov4 species1 and an ,astarte1 nov4 species1 were given me from the ,cerro ,pasco1 about ten degrees of latitude north of ,iquique1 and ,m4 ,d',orbigny thinks that they probably indicate a ,neocomian formation4 ,again1 fifteen degrees of latitude northward1 in ,colombia1 there is a grand fossiliferous deposit1 now well known from the labours of ,von ,buch1 ,lea1 d',orbigny1 and ,forbes1 which belongs to the earlier stages of the cretaceous system4 ,hence1 bearing in mind the character of the few fossils from ,tierra del ,fuego1 there is some evidence that a great portion of the stratified deposits of the whole vast range of the ,south ,american ,cordillera belongs to about the same geological epoch4 ,proceeding from the coast escarpment inwards1 ,i crossed1 in a space of about thirty miles1 an elevated undulatory district1 with the beds dipping in various directions4 ,the rocks are of many kinds1--white laminated1 sometimes siliceous sandstone1--purple and red sandstone1 sometimes so highly calcareous as to have a crystalline fracture1--argillaceous limestone1--black calcareous slate-rock1 like that so often described at ,copiapo and other places1--thinly laminated1 fine-grained1 greenish1 indurated1 sedimentary1 fusible rocks1 approaching in character to the so- called pseudo-honestone of ,chile1 including thin contemporaneous veins of gypsum1--and lastly1 much calcareous1 laminated porcelain jasper1 of a green colour1 with red spots1 and of extremely easy fusibility3 ,i noticed one conformable stratum of a freckled-brown1 feldspathic lava4 ,i may here mention that ,i heard of great beds of gypsum in the ,cordillera4 ,the only novel point in this formation1 is the presence of innumerable thin layers of rock-salt1 alternating with the laminated and hard1 but sometimes earthy1 yellowish1 or bright red and ferruginous sandstones4 ,the thickest layer of salt was only two inches1 and it thinned out at both ends4 ,on one of these saliferous masses ,i noticed a stratum about twelve feet thick1 of dark-brown1 hard brecciated1 easily fusible rock1 containing grains of quartz and of black oxide of iron1 together with numerous imperfect fragments of shells4 ,the problem of the origin of salt is so obscure1 that every fact1 even geographical position1 is worth recording4 7,it is well known that stratified salt is found in several places on the shores of ,peru4 ,the island of ,san ,lorenzo1 off ,lima1 is composed of a pile of thin strata1 about eight hundred feet in thickness1 composed of yellowish and purplish1 hard siliceous1 or earthy sandstones1 alternating with thin layers of shale1 which in places passes into a greenish1 semi-porcellanic1 fusible rock4 ,there are some thin beds of reddish mudstone1 and soft ferruginous rotten-stones1 with layers of gypsum4 ,in nearly all these varieties1 especially in the softer sandstones1 there are numerous thin seams of rock-salt3 ,i was informed that one layer has been found two inches in thickness4 ,the manner in which the minutest fissures of the dislocated beds have been penetrated by the salt1 apparently by subsequent infiltration1 is very curious4 ,on the south side of the island1 layers of coal and of impure limestone have been discovered4 ,hence we here have salt1 gypsum1 and coal associated together4 ,the strata include veins of quartz1 carbonate of lime1 and iron pyrites2 they have been dislocated by an injected mass of greenish-brown feldspathic trap4 ,not only is salt abundant on the extreme western limits of the district between the ,cordillera and the ,pacific1 but1 according to ,helms1 it is found in the outlying low hills on the eastern flank of the ,cordillera4 ,these facts appear to me opposed to the theory1 that rock-salt is due to the sinking of water1 charged with salt1 in mediterranean spaces of the ocean4 ,the general character of the geology of these countries would rather lead to the opinion1 that its origin is in some way connected with volcanic heat at the bottom of the sea3 see on this subject ,sir ,r4 ,murchison 8,anniversary ,address to the ,geological ,society0 #ahdc page #fe47 ,with the exception of these saliferous beds1 most of the rocks as already remarked1 present a striking general resemblance with the upper parts of the gypseous or cretaceo-oolitic formation of ,chile4 ,,metalliferous ,,veins4 ,i have only a few remarks to make on this subject3 in nine mining districts1 some of them of considerable extent1 which ,i visited in ,,central ,chile1 ,i found the ,,principal veins running from between ,n4 and ,n4,w4 to ,s4 and ,s4,e4 7,these mining districts are ,yaquil near ,nancagua1 where the direction of the chief veins1 to which only in all cases ,i refer1 is north and south2 in the ,uspallata range1 the prevailing line is ,n4,n4,w4 and ,s4,s4,e42 in the ,c4 de ,prado1 it is ,n4,n4,w4 and ,s4,s4,e42 near ,illapel1 it is ,n4 by ,w4 and ,s4 by ,e42 at ,los ,hornos the direction varies from between ,n4 and ,n4,w4 to ,s4 and ,s4,e42 at the ,c4 de los ,hornos 7further northward71 it is ,n4,n4,w4 and ,s4,s4,e42 at ,panuncillo1 it is ,n4,n4,w4 and ,s4,s4,e42 and1 lastly1 at ,arqueros1 the direction is ,n4,w4 and ,s4,e473 in some other places1 however1 their courses appeared quite irregular1 as is said to be generally the case in the whole valley of ,copiapo3 at ,tambillos1 south of ,coquimbo1 ,i saw one large copper vein extending east and west4 ,it is worthy of notice1 that the foliation of the gneiss and mica-slate1 where such rocks occur1 certainly tend to run like the metalliferous veins1 though often irregularly1 in a direction a little westward of north4 ,at ,yaquil1 ,i observed that the principal auriferous veins ran nearly parallel to the grain or imperfect cleavage of the surrounding ,,granitic rocks4 ,with respect to the distribution of the different metals1 copper1 gold1 and iron are generally associated together1 and are most frequently found 7but with many exceptions1 as we shall presently see7 in the rocks of the lower series1 between the ,cordillera and the ,pacific1 namely1 in granite1 syenite1 altered feldspathic clay-slate1 gneiss1 and as near ,guasco mica-schist4 ,the copper-ores consist of sulphurets1 oxides1 and carbonates1 sometimes with laminae of native metal3 ,i was assured that in some cases 7as at ,panuncillo ,s4,e4 of ,coquimbo71 the upper part of the same vein contains oxides1 and the lower part sulphurets of copper4 7,the same fact has been observed by ,mr4 ,taylor in ,cuba3 8,london ,philosophical ,journal0 volume #aa page #ba47 ,gold occurs in its native form2 it is believed that1 in many cases1 the upper part of the vein is the most productive part3 this fact probably is connected with the abundance of this metal in the stratified detritus of ,chile1 which must have been chiefly derived from the degradation of the upper portions of the rocks4 ,these superficial beds of well-rounded gravel and sand1 containing gold1 appeared to me to have been formed under the sea close to the beach1 during the slow elevation of the land3 ,schmidtmeyer remarks that in ,chile gold is sought for in shelving banks at the height of some feet on the sides of the streams1 and not in their beds1 as would have been the case had this metal been deposited by common alluvial action4 78,travels in ,chile0 page #bi47 ,very frequently the copper-ores1 including some gold1 are associated with abundant micaceous specular iron4 ,gold is often found in iron-pyrites3 at two gold mines at ,yaquil 7near ,nancagua71 ,i was informed by the proprietor that in one the gold was always associated with copper-pyrites1 and in the other with iron-pyrites3 in this latter case1 it is said that if the vein ceases to contain iron-pyrites1 it is yet worth while to continue the search1 but if the iron-pyrites1 when it reappears1 is not auriferous1 it is better at once to give up working the vein4 ,although ,i believe copper and gold are most frequently found in the lower granitic and metamorphic schistose series1 yet these metals occur both in the porphyritic conglomerate formation 7as on the flanks of the ,bell of ,quillota and at ,jajuel71 and in the superincumbent strata4 ,at ,jajuel ,i was informed that the copper-ore1 with some gold1 is found only in the greenstones and altered feldspathic clay-slate1 which alternate with the purple porphyritic conglomerate4 ,several gold veins and some of copper- ore are worked in several parts of the ,uspallata range1 both in the metamorphosed strata1 which have been shown to have been of probably subsequent origin to the ,neocomian or gypseous formation of the main ,cordillera1 and in the intrusive andesitic rocks of that range4 ,at ,los ,hornos 7,n4,e4 of ,illapel71 likewise1 there are numerous veins of copper- pyrites and of gold1 both in the strata of the gypseous formation and in the injected hills of andesite and various porphyries4 ,silver1 in the form of a chloride1 sulphuret1 or an amalgam1 or in its native state1 and associated with lead and other metals1 and at ,arqueros with pure native copper1 occurs chiefly in the upper great gypseous or cretaceo-oolitic formation which forms probably the richest mass in ,chile4 ,we may instance the mining districts of ,arqueros near ,coquimbo1 and of nearly the whole valley of ,copiapo1 and of ,iquique 7where the principal veins run ,n4,e4 by ,e4 and ,s4,w4 by ,w471 in ,peru4 ,hence comes ,molina's remark1 that silver is born in the cold and solitary deserts of the ,upper ,cordillera4 ,there are1 however1 exceptions to this rule3 at ,paral 7,s4,e4 of ,coquimbo7 silver is found in the porphyritic conglomerate formation2 as ,i suspect is likewise the case at ,s4 ,pedro de ,nolasko in the ,peuquenes ,pass4 ,rich argentiferous lead is found in the clay-slate of the ,uspallata range2 and ,i saw an old silver-mine in a hill of syenite at the foot of the ,bell of ,quillota3 ,i was also assured that silver has been found in the andesitic and porphyritic region between the town of ,copiapo and the ,pacific4 ,i have stated in a previous part of this chapter1 that in two neighbouring mines at ,arqueros the veins in one were productive when they traversed the singular green sedimentary beds1 and unproductive when crossing the reddish beds2 whereas at the other mine exactly the reverse takes place2 ,i have also described the singular and rare case of numerous particles of native silver and of the chloride being disseminated in the green rock at the distance of a yard from the vein4 ,mercury occurs with silver both at ,arqueros and at ,copiapo3 at the base of ,c4 de los ,hornos 7,s4,e4 of ,coquimbo1 a different place from ,los ,hornos1 before mentioned7 ,i saw in a syenitic rock numerous quartzose veins1 containing a little cinnabar in nests3 there were here other parallel veins of copper and of a ferrugino-auriferous ore4 ,i believe tin has never been found in ,chile4 ,from information given me by ,mr4 ,nixon of ,yaquil 7,at the ,durazno mine1 the gold is associated with copper-pyrites1 and the veins contain large prisms of plumbago4 ,crystallised carbonate of lime is one of the commonest minerals in the matrix of the ,chilean veins471 and by others1 it appears that in ,chile those veins are generally most permanently productive1 which1 consisting of various minerals 7sometimes differing but slightly from the surrounding rocks71 include parallel strings ,,rich in metals2 such a vein is called a veta real4 ,more commonly the mines are worked only where one1 two1 or more thin veins or strings running in a different direction1 intersect a ,,poor 8veta real30 it is unanimously believed that at such points of intersection 7cruceros71 the quantity of metal is much greater than that contained in other parts of the intersecting veins4 ,in some cruceros or points of intersection1 the metals extend even beyond the walls of the main1 broad1 stony vein4 ,it is said that the greater the angle of intersection1 the greater the produce2 and that nearly parallel strings attract each other2 in the ,uspallata range1 ,i observed that numerous thin auri-ferruginous veins repeatedly ran into knots1 and then branched out again4 ,i have already described the remarkable manner in which rocks of the ,uspallata range are indurated and blackened 7as if by a blast of gunpowder7 to a considerable distance from the metallic veins4 ,finally1 ,i may observe1 that the presence of metallic veins seems obviously connected with the presence of intrusive rocks1 and with the degree of metamorphic action which the different districts of ,chile have undergone4 7,sir ,r4 ,murchison and his fellow travellers have given some striking facts on this subject in their account of the ,ural ,mountains 78,geological ,proceedings0 volume #c page #gdh47 ,such metamorphosed areas are generally accompanied by numerous dikes and injected masses of andesite and various porphyries3 ,i have in several places traced the metalliferous veins from the intrusive masses into the encasing strata4 ,knowing that the porphyritic conglomerate formation consists of alternate streams of submarine lavas and of the debris of anciently erupted rocks1 and that the strata of the upper gypseous formation sometimes include submarine lavas1 and are composed of tuffs1 mudstones1 and mineral substances1 probably due to volcanic exhalations1--the richness of these strata is highly remarkable when compared with the erupted beds1 often of submarine origin1 but ,,not ,,metamorphosed1 which compose the numerous islands in the ,pacific1 ,indian1 and ,atlantic ,oceans2 for in these islands metals are entirely absent1 and their nature even unknown to the aborigines4 ,a ,,summary ,,of ,,the ,,geological ,,history ,,of ,,the ,,chilean ,,cordillera1 ,,and ,,of ,,the ,,southern ,,parts ,,of ,,south ,,america4 ,we have seen that the shores of the ,pacific1 for a space of #a1bjj miles from ,tres ,montes to ,copiapo1 and ,i believe for a very much greater distance1 are composed1 with the exception of the tertiary basins1 of metamorphic schists1 plutonic rocks1 and more or less altered clay-slate4 ,on the floor of the ocean thus constituted1 vast streams of various purplish claystone and greenstone porphyries were poured forth1 together with great alternating piles of angular and rounded fragments of similar rocks ejected from the submarine craters4 ,from the compactness of the streams and fragments1 it is probable that1 with the exception of some districts in ,northern ,chile1 the eruptions took place in profoundly deep water4 ,the orifices of eruption appear to have been studded over a breadth1 with some outliers1 of from fifty to one hundred miles3 and closely enough together1 both north and south1 and east and west1 for the ejected matter to form a continuous mass1 which in ,central ,chile is more than a mile in thickness4 ,i traced this mould-like mass1 for only #dej miles2 but judging from what ,i saw at ,iquique1 from specimens1 and from published accounts1 it appears to have a manifold greater length4 ,in the basal parts of the series1 and especially towards the flanks of the range1 mud1 since converted into a feldspathic slaty rock1 and sometimes into greenstone1 was occasionally deposited between the beds of erupted matter3 with this exception the uniformity of the porphyritic rocks is very remarkable4 ,at the period when the claystone and greenstone porphyries nearly or quite ceased being erupted1 that great pile of strata which1 from often abounding with gypsum1 ,i have generally called the gypseous formation was deposited1 and feldspathic lavas1 together with other singular volcanic rocks1 were occasionally poured forth3 ,i am far from pretending that any distinct line of demarcation can be drawn between this formation and the underlying porphyries and porphyritic conglomerate1 but in a mass of such great thickness1 and between beds of such widely different mineralogical nature1 some division was necessary4 ,at about the commencement of the gypseous period1 the bottom of the sea here seems first to have been peopled by shells1 not many in kind1 but abounding in individuals4 ,at the ,p4 del ,inca the fossils are embedded near the base of the formation2 in the ,peuquenes range1 at different levels1 halfway up1 and even higher in the series2 hence1 in these sections1 the whole pile of strata belongs to the same period3 the same remark is applicable to the beds at ,copiapo1 which attain a thickness of between seven and eight thousand feet4 ,the fossil shells in the ,cordillera of ,central ,chile1 in the opinion of all the palaeontologists who have examined them1 belong to the earlier stages of the cretaceous system2 whilst in ,northern ,chile there is a most singular mixture of cretaceous and oolitic forms3 from the geological relations1 however1 of these two districts1 ,i cannot but think that they all belong to nearly the same epoch1 which ,i have provisionally called cretaceo-oolitic4 ,the strata in this formation1 composed of black calcareous shaly-rocks of red and white1 and sometimes siliceous sandstone1 of coarse conglomerates1 limestones1 tuffs1 dark mudstones1 and those singular fine-grained rocks which ,i have called pseudo-honestones1 vast beds of gypsum1 and many other jaspery and scarcely describable varieties1 vary and replace each other in short horizontal distances1 to an extent1 ,i believe1 unequalled even in any tertiary basin4 ,most of these substances are easily fusible1 and have apparently been derived either from volcanoes still in quiet action1 or from the attrition of volcanic products4 ,if we picture to ourselves the bottom of the sea1 rendered uneven in an extreme degree1 with numerous craters1 some few occasionally in eruption1 but the greater number in the state of solfataras1 discharging calcareous1 siliceous1 ferruginous matters1 and gypsum or sulphuric acid to an amount surpassing1 perhaps1 even the existing sulphureous volcanoes of ,java 7,von ,buch's 8,description ,physique des ,iles ,canaries0 page #dbh471 we shall probably understand the circumstances under which this singular pile of varying strata was accumulated4 ,the shells appear to have lived at the quiescent periods when only limestone or calcareo-argillaceous matter was depositing4 ,from ,dr4 ,gillies' account1 this gypseous or cretaceo-oolitic formation extends as far south as the ,pass of ,planchon1 and ,i followed it northward at intervals for #ejj miles3 judging from the character of the beds with the ,terebratula aenigma1 at ,iquique1 it extends from four to five hundred miles further3 and perhaps even for ten degrees of latitude north of ,iquique to the ,cerro ,pasco1 not far from ,lima3 again1 we know that a cretaceous formation1 abounding with fossils1 is largely developed north of the equator1 in ,colombia3 in ,tierra del ,fuego1 at about this same period1 a wide district of clay-slate was deposited1 which in its mineralogical characters and external features1 might be compared to the ,silurian regions of ,north ,wales4 ,the gypseous formation1 like that of the porphyritic breccia- conglomerate on which it rests1 is of inconsiderable breadth2 though of greater breadth in ,northern than in ,central ,chile4 ,as the fossil shells in this formation are covered1 in the ,peuquenes ridge1 by a great thickness of strata2 at the ,puente del ,inca1 by at least five thousand feet2 at ,coquimbo1 though the superposition there is less plainly seen1 by about six thousand feet2 and at ,copiapo1 certainly by five or six thousand1 and probably by seven thousand feet 7the same species there recurring in the upper and lower parts of the series71 we may feel confident that the bottom of the sea subsided during this cretaceo-oolitic period1 so as to allow of the accumulation of the superincumbent submarine strata4 ,this conclusion is confirmed by1 or perhaps rather explains1 the presence of the many beds at many levels of coarse conglomerate1 the well- rounded pebbles in which we cannot believe were transported in very deep water4 ,even the underlying porphyries at ,copiapo4 with their highly amygdaloidal surfaces1 do not appear to have flowed under great pressure4 ,the great sinking movement thus plainly indicated1 must have extended in a north and south line for at least four hundred miles1 and probably was co- extensive with the gypseous formation4 ,the beds of conglomerate just referred to1 and the extraordinarily numerous silicified trunks of fir-trees at ,los ,hornos1 perhaps at ,coquimbo and at two distant points in the valley of ,copiapo1 indicate that land existed at this period in the neighbourhood4 ,this land1 or islands1 in the northern part of the district of ,copiapo1 must have been almost exclusively composed1 judging from the nature of the pebbles of granite3 in the southern parts of ,copiapo1 it must have been mainly formed of claystone porphyries1 with some mica-schist1 and with much sandstone and jaspery rocks exactly like the rocks in the gypseous formation1 and no doubt belonging to its basal series4 ,in several other places also1 during the accumulation of the gypseous formation1 its basal parts and the underlying porphyritic conglomerate must likewise have been already partially upheaved and exposed to wear and tear2 near the ,puente del ,inca and at ,coquimbo1 there must have existed masses of mica-schist or some such rock1 whence were derived the many small pebbles of opaque quartz4 ,it follows from these facts1 that in some parts of the ,cordillera the upper beds of the gypseous formation must lie unconformably on the lower beds2 and the whole gypseous formation1 in parts1 unconformably on the porphyritic conglomerate2 although ,i saw no such cases1 yet in many places the gypseous formation is entirely absent2 and this1 although no doubt generally caused by quite subsequent denudation1 may in others be due to the underlying porphyritic conglomerate having been locally upheaved before the deposition of the gypseous strata1 and thus having become the source of the pebbles of porphyry embedded in them4 ,in the porphyritic conglomerate formation1 in its lower and middle parts1 there is very rarely any evidence1 with the exception of the small quartz pebbles at ,jajuel near ,aconcagua1 and of the single pebble of granite at ,copiapo1 of the existence of neighbouring land3 in the upper parts1 however1 and especially in the district of ,copiapo1 the number of thoroughly well-rounded pebbles of compact porphyries make me believe1 that1 as during the prolonged accumulation of the gypseous formation the lower beds had already been locally upheaved and exposed to wear and tear1 so it was with the porphyritic conglomerate4 ,hence in following thus far the geological history of the ,cordillera1 it may be inferred that the bed of a deep and open1 or nearly open1 ocean was filled up by porphyritic eruptions1 aided probably by some general and some local elevations1 to that comparatively shallow level at which the cretaceo- oolitic shells first lived4 ,at this period1 the submarine craters yielded at intervals a prodigious supply of gypsum and other mineral exhalations1 and occasionally1 in certain places poured forth lavas1 chiefly of a feldspathic nature3 at this period1 islands clothed with fir-trees and composed of porphyries1 primary rocks1 and the lower gypseous strata had already been locally upheaved1 and exposed to the action of the waves2--the general movement1 however1 at this time having been over a very wide area1 one of slow subsidence1 prolonged till the bed of the sea sank several thousand feet4 ,in ,central ,chile1 after the deposition of a great thickness of the gypseous strata1 and after their upheaval1 by which the ,cumbre and adjoining ranges were formed1 a vast pile of tufaceous matter and submarine lava was accumulated1 where the ,uspallata chain now stands2 also after the deposition and upheaval of the equivalent gypseous strata of the ,peuquenes range1 the great thick mass of conglomerate in the valley of ,tenuyan was accumulated3 during the deposition of the ,uspallata strata1 we know absolutely1 from the buried vertical trees1 that there was a subsidence of some thousand feet2 and we may infer from the nature of the conglomerate in the valley of ,tenuyan1 that a similar and perhaps contemporaneous movement there took place4 ,we have1 then1 evidence of a second great period of subsidence2 and1 as in the case of the subsidence which accompanied the accumulation of the cretaceo-oolitic strata1 so this latter subsidence appears to have been complicated by alternate or local elevatory movement-- for the vertical trees1 buried in the midst of the ,uspallata strata1 must have grown on dry land1 formed by the upheaval of the lower submarine beds4 ,presently ,i shall have to recapitulate the facts1 showing that at a still later period1 namely1 at nearly the commencement of the old tertiary deposits of ,patagonia and of ,chile1 the continent stood at nearly its present level1 and then1 for the third time1 slowly subsided to the amount of several hundred feet1 and was afterwards slowly re-uplifted to its present level4 ,the highest peaks of the ,cordillera appear to consist of active or more commonly dormant volcanoes1--such as ,tupungato1 ,maypu1 and ,aconcagua1 which latter stands #bc1jjj feet above the level of the sea1 and many others4 ,the next highest peaks are formed of the gypseous and porphyritic strata1 thrown into vertical or highly inclined positions4 ,besides the elevation thus gained by angular displacements1 ,i infer1 without any hesitation--from the stratified gravel-fringes which gently slope up the valleys of the ,cordillera from the gravel-capped plains at their base1 which latter are connected with the plains1 still covered with recent shells on the coast-- that this great range has been upheaved in mass by a slow movement1 to an amount of at least #h1jjj feet4 ,in the ,despoblado ,valley1 north of ,copiapo1 the horizontal elevation1 judging from the compact1 stratified tufaceous deposit1 capping the distant mountains at corresponding heights1 was about ten thousand feet4 ,it is very possible1 or rather probable1 that this elevation in mass may not have been strictly horizontal1 but more energetic under the ,cordillera1 than towards the coast on either side2 nevertheless1 movements of this kind may be conveniently distinguished from those by which strata have been abruptly broken and upturned4 ,when viewing the ,cordillera1 before having read ,mr4 ,hopkins's profound 8,researches on ,physical ,geology10 the conviction was impressed on me1 that the angular dislocations1 however violent1 were quite subordinate in importance to the great upward movement in mass1 and that they had been caused by the edges of the wide fissures1 which necessarily resulted from the tension of the elevated area1 having yielded to the inward rush of fluidified rock1 and having thus been upturned4 ,the ridges formed by the angularly upheaved strata are seldom of great length3 in the central parts of the ,cordillera they are generally parallel to each other1 and run in north and south lines2 but towards the flanks they often extend more or less obliquely4 ,the angular displacement has been much more violent in the central than in the exterior ,,main lines2 but it has likewise been violent in some of the ,,minor lines on the extreme flanks4 ,the violence has been very unequal on the same short lines2 the crust having apparently tended to yield on certain points along the lines of fissures4 ,these points1 ,i have endeavoured to show1 were probably first foci of eruption1 and afterwards of injected masses of porphyry and andesite4 7,sir ,r4 ,murchison and his companions state 8,geological ,proceedings0 volume #c page #gdg1 that no true granite appears in the higher ,ural ,mountains2 but that syenitic greenstone--a rock closely analogous to our andesite--is far the most abundant of the intrusive masses47 ,the close similarity of the andesitic granites and porphyries1 throughout ,chile1 ,tierra del ,fuego1 and even in ,peru1 is very remarkable4 ,the prevalence of feldspar cleaving like albite1 is common not only to the andesites1 but 7as ,i infer from the high authority of ,professor ,g4 ,rose1 as well as from my own measurements7 to the various claystone and greenstone porphyries1 and to the trachytic lavas of the ,cordillera4 ,the andesitic rocks have in most cases been the last injected ones1 and they probably form a continuous dome under this great range3 they stand in intimate relationship with the modern lavas2 and they seem to have been the immediate agent in metamorphosing the porphyritic conglomerate formation1 and often likewise the gypseous strata1 to the extraordinary extent to which they have suffered4 ,with respect to the age at which the several parallel ridges composing the ,cordillera were upthrown1 ,i have little evidence4 ,many of them may have been contemporaneously elevated and injected in the same manner as in volcanic archipelagoes lavas are contemporaneously ejected on the parallel lines of fissure4 78,volcanic ,islands0 etc47 ,but the pebbles apparently derived from the wear and tear of the porphyritic conglomerate formation1 which are occasionally present in the upper parts of this same formation1 and are often present in the gypseous formation1 together with the pebbles from the basal parts of the latter formation in its upper strata1 render it almost certain that portions1 we may infer ridges1 of these two formations were successively upheaved4 ,in the case of the gigantic ,portillo range1 we may feel almost certain that a preexisting granitic line was upraised 7not by a single blow1 as shown by the highly inclined basaltic streams in the valley on its eastern flank7 at a period long subsequent to the upheavement of the parallel ,peuquenes range4 7,i have endeavoured to show in my 8,journal0 #bnd edition page #cba1 that the singular fact of the river1 which drains the valley between these two ranges1 passing through the ,portillo and higher line1 is explained by its slow and subsequent elevation4 ,there are many analogous cases in the drainage of rivers3 see 8,edinburgh ,new ,philosophical ,journal0 volume #bh pages #cc and #dd47 ,again1 subsequently to the upheavement of the ,cumbre chain1 that of ,uspallata was formed and elevated2 and afterwards1 ,i may add1 in the plain of ,uspallata1 beds of sand and gravel were violently upthrown4 ,the manner in which the various kinds of porphyries and andesites have been injected one into the other1 and in which the infinitely numerous dikes of various composition intersect each other1 plainly show that the stratified crust has been stretched and yielded many times over the same points4 ,with respect to the age of the axes of elevation between the ,pacific and the ,cordillera1 ,i know little3 but there are some lines which must--namely1 those running north and south in ,chiloe1 those eight or nine east and west1 parallel1 far-extended1 most symmetrical uniclinal lines at ,p4 ,rumena1 and the short ,n4,w4-,s4,e4 and ,n4,e4- ,s4,w4 lines at ,concepcion--have been upheaved long after the formation of the ,cordillera4 ,even during the earthquake of #ahce1 when the linear north and south islet of ,st4 ,mary was uplifted several feet above the surrounding area1 we perhaps see one feeble step in the formation of a subordinate mountain-axis4 ,in some cases1 moreover1 for instance1 near the baths of ,cauquenes1 ,i was forcibly struck with the small size of the breaches cut through the exterior mountain-ranges1 compared with the size of the same valleys higher up where entering the ,cordillera2 and this circumstance appeared to me scarcely explicable1 except on the idea of the exterior lines having been subsequently upthrown1 and therefore having been exposed to a less amount of denudation4 ,from the manner in which the fringes of gravel are prolonged in unbroken slopes up the valleys of the ,cordillera1 ,i infer that most of the greater dislocations took place during the earlier parts of the great elevation in mass3 ,i have1 however1 elsewhere given a case1 and ,m4 de ,tschudi has given another1 of a ridge thrown up in ,peru across the bed of a river1 and consequently after the final elevation of the country above the level of the sea4 78,reise in ,peru0 ,band #b s4#h3 ,author's 8,journal0 #bnd edition page #cei47 ,ascending to the older tertiary formations1 ,i will not again recapitulate the remarks already given at the end of the ,fifth ,chapter1--on their great extent1 especially along the shores of the ,atlantic--on their antiquity1 perhaps corresponding with that of the eocene deposits of ,europe1--on the almost entire dissimilarity1 though the formations are apparently contemporaneous1 of the fossils from the eastern and western coasts1 as is likewise the case1 even in a still more marked degree1 with the shells now living in these opposite though approximate seas1--on the climate of this period not having been more tropical than what might have been expected from the latitudes of the places under which the deposits occur2 a circumstance rendered well worthy of notice1 from the contrast with what is known to have been the case during the older tertiary periods of ,europe1 and likewise from the fact of the southern hemisphere having suffered at a much later period1 apparently at the same time with the northern hemisphere1 a colder or more equable temperature1 as shown by the zones formerly affected by ice-action4 ,nor will ,i recapitulate the proofs of the bottom of the sea1 both on the eastern and western coast1 having subsided seven or eight hundred feet during this tertiary period2 the movement having apparently been co-extensive1 or nearly co-extensive1 with the deposits of this age4 ,nor will ,i again give the facts and reasoning on which the proposition was founded1 that when the bed of the sea is either stationary or rising1 circumstances are far less favourable than when its level is sinking1 to the accumulation of conchiferous deposits of sufficient thickness1 extension1 and hardness to resist1 when upheaved1 the ordinary vast amount of denudation4 ,we have seen that the highly remarkable fact of the absence of any ,,extensive formations containing recent shells1 either on the eastern or western coasts of the continent1--though these coasts now abound with living mollusca1--though they are1 and apparently have always been1 as favourable for the deposition of sediment as they were when the tertiary formations were copiously deposited1--and though they have been upheaved to an amount quite sufficient to bring up strata from the depths the most fertile for animal life--can be explained in accordance with the above proposition4 ,as a deduction1 it was also attempted to be shown1 first1 that the want of close sequence in the fossils of successive formations1 and of successive stages in the same formation1 would follow from the improbability of the same area continuing slowly to subside from one whole period to another1 or even during a single entire period2 and secondly1 that certain epochs having been favourable at distant points1 in the same quarter of the world for the synchronous accumulation of fossiliferous strata1 would follow from movements of subsidence having apparently1 like those of elevation1 contemporaneously affected very large areas4 ,there is another point which deserves some notice1 namely1 the analogy between the upper parts of the ,patagonian tertiary formation1 as well as of the upper possibly contemporaneous beds at ,chiloe and ,concepcion1 with the great gypseous formation of ,cordillera2 for in both formations1 the rocks1 in their fusible nature1 in their containing gypsum1 and in many other characters1 show a connection1 either intimate or remote1 with volcanic action2 and as the strata in both were accumulated during subsidence1 it appears at first natural to connect this sinking movement with a state of high activity in the neighbouring volcanoes4 ,during the cretaceo-oolitic period this certainly appears to have been the case at the ,puente del ,inca1 judging from the number of intercalated lava-streams in the lower #c1jjj feet of strata2 but generally1 the volcanic orifices seem at this time to have existed as submarine solfataras1 and were certainly quiescent compared with their state during the accumulation of the porphyritic conglomerate formation4 ,during the deposition of the tertiary strata we know that at ,s4 ,cruz1 deluges of basaltic lava were poured forth2 but as these lie in the upper part of the series1 it is possible that the subsidence may at that time have ceased3 at ,chiloe1 ,i was unable to ascertain to what part of the series the pile of lavas belonged4 ,the ,uspallata tuffs and great streams of submarine lavas1 were probably intermediate in age between the cretaceo- oolitic and older tertiary formations1 and we know from the buried trees that there was a great subsidence during their accumulation2 but even in this case1 the subsidence may not have been strictly contemporaneous with the great volcanic eruptions1 for we must believe in at least one intercalated period of elevation1 during which the ground was upraised on which the now buried trees grew4 ,i have been led to make these remarks1 and to throw some doubt on the strict contemporaneousness of high volcanic activity and movements of subsidence1 from the conviction impressed on my mind by the study of coral formations1 that these two actions do not generally go on synchronously2--on the contrary1 that in volcanic districts1 subsidence ceases as soon as the orifices burst forth into renewed action1 and only recommences when they again have become dormant4 78,the ,structure and ,distribution of ,coral ,reefs407 ,at a later period1 the ,pampean mud1 of estuary origin1 was deposited over a wide area1--in one district conformably on the underlying old tertiary strata1 and in another district unconformably on them1 after their upheaval and denudation4 ,during and before the accumulation1 however1 of these old tertiary strata1 and1 therefore1 at a very remote period1 sediment1 strikingly resembling that of the ,pampas1 was deposited2 showing during how long a time in this case the same agencies were at work in the same area4 ,the deposition of the ,pampean estuary mud was accompanied1 at least in the southern parts of the ,pampas1 by an elevatory movement1 so that the ,m4 ,hermoso beds probably were accumulated after the upheaval of those round the ,s4 ,ventana2 and those at ,p4 ,alta after the upheaval of the ,m4 ,hermoso strata2 but there is some reason to suspect that one period of subsidence intervened1 during which mud was deposited over the coarse sand of the ,barrancas de ,s4 ,gregorio1 and on the higher parts of ,banda ,oriental4 ,the mammiferous animals characteristic of this formation1 many of which differ as much from the present inhabitants of ,south ,america1 as do the eocene mammals of ,europe from the present ones of that quarter of the globe1 certainly co-existed at ,b4 ,blanca with twenty species of mollusca1 one balanus1 and two corals1 all now living in the adjoining sea3 this is likewise the case in ,patagonia with the ,macrauchenia1 which co-existed with eight shells1 still the commonest kinds on that coast4 ,i will not repeat what ,i have elsewhere said1 on the place of habitation1 food1 wide range1 and extinction of the numerous gigantic mammifers1 which at this late period inhabited the two ,americas4 ,the nature and grouping of the shells embedded in the old tertiary formations of ,patagonia and ,chile show us1 that the continent at that period must have stood only a few fathoms below its present level1 and that afterwards it subsided over a wide area1 seven or eight hundred feet4 ,the manner in which it has since been rebrought up to its actual level1 was described in detail in the ,first and ,second ,chapters4 ,it was there shown that recent shells are found on the shores of the ,atlantic1 from ,tierra del ,fuego northward for a space of at least #a1ahj nautical miles1 and at the height of about #ajj feet in ,la ,plata1 and of #djj feet in ,patagonia4 ,the elevatory movements on this side of the continent have been slow2 and the coast of ,patagonia1 up to the height in one part of #iej feet and in another of #a1bjj feet1 is modelled into eight great1 step-like1 gravel-capped plains1 extending for hundreds of miles with the same heights2 this fact shows that the periods of denudation 7which1 judging from the amount of matter removed1 must have been long continued7 and of elevation were synchronous over surprisingly great lengths of coasts4 ,on the shores of the ,pacific1 upraised shells of recent species1 generally1 though not always1 in the same proportional numbers as in the adjoining sea1 have actually been found over a north and south space of #b1jge miles1 and there is reason to believe that they occur over a space of #b1dhj miles4 ,the elevation on this western side of the continent has not been equable2 at ,valparaiso1 within the period during which upraised shells have remained undecayed on the surface1 it has been #a1cjj feet1 whilst at ,coquimbo1 #bjj miles northward1 it has been within this same period only #beb feet4 ,at ,lima1 the land has been uplifted at least #hj feet since ,indian man inhabited that district2 but the level within historical times apparently has subsided4 ,at ,coquimbo1 in a height of #cfd feet1 the elevation has been interrupted by five periods of comparative rest4 ,at several places the land has been lately1 or still is1 rising both insensibly and by sudden starts of a few feet during earthquake-shocks2 this shows that these two kinds of upward movement are intimately connected together4 ,for a space of #gge miles1 upraised recent shells are found on the two opposite sides of the continent2 and in the southern half of this space1 it may be safely inferred from the slope of the land up to the ,cordillera1 and from the shells found in the central part of ,tierra del ,fuego1 and high up the ,river ,santa ,cruz1 that the entire breadth of the continent has been uplifted4 ,from the general occurrence on both coasts of successive lines of escarpments1 of sand-dunes and marks of erosion1 we must conclude that the elevatory movement has been normally interrupted by periods1 when the land either was stationary1 or when it rose at so slow a rate as not to resist the average denuding power of the waves1 or when it subsided4 ,in the case of the present high sea-cliffs of ,patagonia and in other analogous instances1 we have seen that the difficulty in understanding how strata can be removed at those depths under the sea1 at which the currents and oscillations of the water are depositing a smooth surface of mud1 sand1 and sifted pebbles1 leads to the suspicion that the formation or denudation of such cliffs has been accompanied by a sinking movement4 ,in ,south ,america1 everything has taken place on a grand scale1 and all geological phenomena are still in active operation4 ,we know how violent at the present day the earthquakes are1 we have seen how great an area is now rising1 and the plains of tertiary origin are of vast dimensions2 an almost straight line can be drawn from ,tierra del ,fuego for #a1fjj miles northward1 and probably for a much greater distance1 which shall intersect no formation older than the ,patagonian deposits2 so equable has been the upheaval of the beds1 that throughout this long line1 not a fault in the stratification or abrupt dislocation was anywhere observable4 ,looking to the basal1 metamorphic1 and plutonic rocks of the continent1 the areas formed of them are likewise vast2 and their planes of cleavage and foliation strike over surprisingly great spaces in uniform directions4 ,the ,cordillera1 with its pinnacles here and there rising upwards of twenty thousand feet above the level of the sea1 ranges in an unbroken line from ,tierra del ,fuego1 apparently to the ,arctic circle4 ,this grand range has suffered both the most violent dislocations1 and slow1 though grand1 upward and downward movements in mass2 ,i know not whether the spectacle of its immense valleys1 with mountain-masses of once liquified and intrusive rocks now bared and intersected1 or whether the view of those plains1 composed of shingle and sediment hence derived1 which stretch to the borders of the ,atlantic ,ocean1 is best adapted to excite our astonishment at the amount of wear and tear which these mountains have undergone4 ,the ,cordillera from ,tierra del ,fuego to ,mexico1 is penetrated by volcanic orifices1 and those now in action are connected in great trains4 ,the intimate relation between their recent eruptions and the slow elevation of the continent in mass1 appears to me highly important1 for no explanation of the one phenomenon can be considered as satisfactory which is not applicable to the other4 7,on the ,connection of certain ,volcanic ,phenomena in ,south ,america3 8,geological ,transactions0 volume #e page #fji47 ,the permanence of the volcanic action on this chain of mountains is1 also1 a striking fact2 first1 we have the deluges of submarine lavas alternating with the porphyritic conglomerate strata1 then occasionally feldspathic streams and abundant mineral exhalations during the gypseous or cretaceo- oolitic period3 then the eruptions of the ,uspallata range1 and at an ancient but unknown period1 when the sea came up to the eastern foot of the ,cordillera1 streams of basaltic lava at the foot of the ,portillo range2 then the old tertiary eruptions2 and lastly1 there are here and there amongst the mountains1 much worn and apparently very ancient volcanic formations without any craters2 there are1 also1 craters quite extinct1 and others in the condition of solfataras1 and others occasionally or habitually in fierce action4 ,hence it would appear that the ,cordillera has been1 probably with some quiescent periods1 a source of volcanic matter from an epoch anterior to our cretaceo-oolitic formation to the present day2 and now the earthquakes1 daily recurrent on some part of the western coast1 give little hope that the subterranean energy is expended4 ,recurring to the evidence by which it was shown that some at least of the parallel ridges1 which together compose the ,cordillera1 were successively and slowly upthrown at widely different periods2 and that the whole range certainly once1 and almost certainly twice1 subsided some thousand feet1 and being then brought up by a slow movement in mass1 again1 during the old tertiary formations1 subsided several hundred feet1 and again was brought up to its present level by a slow and often interrupted movement2 we see how opposed is this complicated history of changes slowly effected1 to the views of those geologists who believe that this great mountain-chain was formed in late times by a single blow4 ,i have endeavoured elsewhere to show1 that the excessively disturbed condition of the strata in the ,cordillera1 so far from indicating single periods of extreme violence1 presents insuperable difficulties1 except on the admission that the masses of once liquified rocks of the axes were repeatedly injected with intervals sufficiently long for their successive cooling and consolidation4 78,geological ,transactions0 volume #e page #fbf47 ,finally1 if we look to the analogies drawn from the changes now in progress in the earth's crust1 whether to the manner in which volcanic matter is erupted1 or to the manner in which the land is historically known to have risen and sunk3 or again1 if we look to the vast amount of denudation which every part of the ,cordillera has obviously suffered1 the changes through which it has been brought into its present condition1 will appear neither to have been too slowly effected1 nor to have been too complicated4 ,,note4 ,as1 both in ,france and ,england1 translations of a passage in ,professor ,ehrenberg's ,memoir1 often referred to in the ,fourth ,chapter of this volume1 have appeared1 implying that ,professor ,ehrenberg believes1 from the character of the infusoria1 that the ,pampean formation was deposited by a sea-debacle rushing over the land1 ,i may state1 on the authority of a letter to me1 that these translations are incorrect4 ,the following is the passage in question3-- 8,durch ,beachtung der mikroscopischen ,formen hat sich nun feststellen lassen1 das die ,mastodonten-,lager am ,la ,plata und die ,knochen-,lager am ,monte ,hermoso1 who wie die der ,riesen-,gurtelthiere in den ,dunenhugeln bei ,bahia ,blanca1 beides in ,patagonien1 unveranderte brakische ,susswasserbildungen sind1 die einst wohl sammtlich zum obersten ,fluthgebiethe des ,meeres im tieferen ,festlande gehorten40--8,monatsberichten der konigl4 ,akad4 etc40 zu ,berlin vom ,april #ahde4 ,,index4 ,abich1 on a new variety of feldspar4 ,abrolhos islands4 ,absence of recent formations on the ,s4 ,american coasts4 ,aguerros on elevation of ,imperial4 ,albite1 constituent mineral in andesite4 --in rocks of ,tierra del ,fuego4 --in porphyries4 --crystals of1 with orthite4 ,alison1 ,mr41 on elevation of ,valparaiso4 ,alumina1 sulphate of4 ,ammonites from ,concepcion4 ,amolanas1 ,las4 ,amygdaloid1 curious varieties of4 ,amygdaloids of the ,uspallata range4 --of ,copiapo4 ,andesite of ,chile4 --in the valley of ,maypu4 --of the ,cumbre pass4 --of the ,uspallata range4 --of ,los ,hornos4 --of ,copiapo4 ,anhydrite1 concretions of4 ,araucaria1 silicified wood of4 ,arica1 elevation of4 ,arqueros1 mines of4 ,ascension1 gypsum deposited on4 --laminated volcanic rocks of4 ,augite in fragments1 in gneiss4 --with albite1 in lava4 ,austin1 ,mr4 ,r4,a4,c41 on bent cleavage lamina4 ,austin1 ,captain1 on sea-bottom4 ,australia1 foliated rocks of4 ,azara labiata1 beds of1 at ,san ,pedro4 ,baculites vagina4 ,bahia ,blanca1 elevation of4 --formations near4 --character of living shells of4 ,bahia 7,brazil71 elevation near4 --crystalline rocks of4 ,ballard1 ,m41 on the precipitation of sulphate of soda4 ,banda ,oriental1 tertiary formations of4 --crystalline rocks of4 ,barnacles above sea-level4 --adhering to upraised shells4 ,basalt of ,s4 ,cruz4 --streams of1 in the ,portillo range4 --in the ,uspallata range4 ,basin chains of ,chile4 ,beagle ,channel4 ,beaumont1 ,elie de1 on inclination of lava-streams4 --on viscid quartz-rocks4 ,beech-tree1 leaves of fossil4 ,beechey1 ,captain1 on sea-bottom4 ,belcher1 ,lieutenant1 on elevated shells from ,concepcion4 ,bella ,vista1 plain of4 ,benza1 ,dr41 on decomposed granite4 ,bettington1 ,mr41 on quadrupeds transported by rivers4 ,blake1 ,mr41 on the decay of elevated shells near ,iquique4 --on nitrate of soda4 ,bole4 ,bollaert1 ,mr41 on mines of ,iquique4 ,bones1 silicified4 --fossil1 fresh condition of4 ,bottom of sea off ,patagonia4 ,bougainville1 on elevation of the ,falkland islands4 ,boulder formation of ,s4 ,cruz4 --of ,falkland islands4 --anterior to certain extinct quadrupeds4 --of ,tierra del ,fuego4 ,boulders in the ,cordillera4 --transported by earthquake-waves4 --in fine-grained tertiary deposits4 ,brande1 ,mr41 on a mineral spring4 ,bravais1 ,m41 on elevation of ,scandinavia4 ,brazil1 elevation of4 --crystalline rocks of4 ,broderip1 ,mr41 on elevated shells from ,concepcion4 ,brown1 ,mr4 ,r41 on silicified wood of ,uspallata range4 ,brown1 on silicified wood4 ,bucalema1 elevated shells near4 ,buch1 ,von1 on cleavage4 --on cretaceous fossils of the ,cordillera4 --on the sulphureous volcanoes of ,java4 ,buenos ,ayres4 ,burchell1 ,mr41 on elevated shells of ,brazil4 ,byron1 on elevated shells4 ,cachapual1 boulders in valley of4 ,caldcleugh1 ,mr41 on elevation of ,coquimbo4 --on rocks of the ,portillo range4 ,callao1 elevation near4 --old town of4 ,cape of ,good ,hope1 metamorphic rocks of4 ,carcharias megalodon4 ,carpenter1 ,dr41 on microscopic organisms4 ,castro 7,chiloe71 beds near4 ,cauquenes ,baths1 boulders near4 --pebbles in porphyry near4 --volcanic formation near4 --stratification near4 ,caves above sea-level4 ,cervus pumilus1 fossil-horns of4 ,chevalier1 ,m41 on elevation near ,lima4 ,chile1 structure of country between the ,cordillera and the ,pacific4 --tertiary formations of4 --crystalline rocks in4 --central1 geology of4 --northern1 geology of4 ,chiloe1 gravel on coast4 --elevation of4 --tertiary formation of4 --crystalline rocks of4 ,chlorite-schist1 near ,m4 ,video4 ,chonos archipelago1 tertiary formations of4 --crystalline rocks of4 ,chupat1 ,rio1 scoriae transported by4 ,claro1 ,rio1 fossiliferous beds of4 ,clay-shale of ,los ,hornos4 ,clay-slate1 formation of1 ,tierra del ,fuego4 --of ,concepcion4 --feldspathic1 of ,chile4 -- --of the ,uspallata range4 --black siliceous1 band of1 in porphyritic formations of ,chile4 ,claystone porphyry1 formation of1 in ,chile4 --origin of4 --eruptive sources of4 ,cleavage1 definition of4 --at ,bahia4 --,rio de ,janeiro4 --,maldonado4 --,monte ,video4 --,s4 ,guitru-gueyu4 --,falkland ,i4 --,tierra del ,fuego4 --,chonos ,i4 --,chiloe4 --,concepcion4 --,chile4 --discussion on4 ,cleavage-laminae superficially bent4 ,cliffs1 formation of4 ,climate1 late changes in4 --of ,chile during tertiary period4 ,coal of ,concepcion4 --,s4 ,lorenzo4 ,coast-denudation of ,st4 ,helena4 ,cobija1 elevation of4 ,colombia1 cretaceous formation of4 ,colonia del ,sacramiento1 elevation of4 --,pampean formation near ,colorado1 ,rio1 gravel of4 --sand-dunes of4 --,pampean formation near4 ,combarbala4 ,concepcion1 elevation of4 --deposits of4 --crystalline rocks of4 ,conchalee1 gravel-terraces of4 ,concretions of gypsum1 at ,iquique4 --in sandstone at ,s4 ,cruz4 --in tufaceous tuff of ,chiloe4 --in gneiss4 --in claystone-porphyry at ,port ,desire4 --in gneiss at ,valparaiso4 --in metamorphic rocks4 --of anhydrite4 --relations of1 to veins4 ,conglomerate claystone of ,chile4 --of ,tenuyan4 --of the ,cumbre ,pass4 --of ,rio ,claro4 --of ,copiapo4 ,cook1 ,captain1 on form of sea-bottom4 ,copiapo1 elevation of4 --tertiary formations of4 --secondary formations of4 ,copper1 sulphate of4 --native1 at ,arqueros4 --mines of1 at ,panuncillo4 --veins1 distribution of4 ,coquimbo1 elevation and terraces of4 --tertiary formations of4 --secondary formations of4 ,corallines living on pebbles4 ,cordillera1 valleys bordered by gravel fringes4 --basal strata of4 --fossils of4 --elevation of4 --gypseous formations of4 --claystone-porphyries of4 --andesitic rocks of4 --volcanoes of4 ,coste1 ,m41 on elevation of ,lemus4 ,coy inlet1 tertiary formation of4 ,crassatella ,lyellii4 ,cruickshanks1 ,mr41 on elevation near ,lima4 ,crystals of feldspar1 gradual formation of1 at ,port ,desire4 ,cumbre1 ,pass of1 in ,cordillera4 ,cuming1 ,mr41 on habits of the ,mesodesma4 --on range of living shells on west coast4 ,dana1 ,mr41 on foliated rocks4 --on amygdaloids4 ,darwin1 ,mount4 ,d',aubuisson1 on concretions4 --on foliated rocks4 ,decay1 gradual1 of upraised shells4 ,decomposition of granite rocks4 ,de la ,beche1 ,sir ,h41 his theoretical researches in geology4 --on the action of salt on calcareous rocks4 --on bent cleavage-laminae4 ,denudation on coast of ,patagonia4 --great powers of4 --of the ,portillo range4 ,deposits1 saline4 ,despoblado1 valley of4 ,detritus1 nature of1 in ,cordillera4 ,devonshire1 bent cleavage in4 ,dikes1 in gneiss of ,brazil4 --near ,rio de ,janeiro4 --pseudo1 at ,port ,desire4 --in ,tierra del ,fuego4 --in ,chonos archipelago1 containing quartz4 --near ,concepcion1 with quartz4 --granitic-porphyritic1 at ,valparaiso4 --rarely vesicular in ,cordillera4 --absent in the central ridges of the ,portillo pass4 --of the ,portillo range1 with grains of quartz4 --intersecting each other often4 --numerous at ,copiapo4 ,domeyko1 ,m41 on the silver mines of ,coquimbo4 on the fossils of ,coquimbo4 ,d',orbigny1 ,m4 ,a41 on upraised shells of ,monte ,video4 --on elevated shells at ,st4 ,pedro4 --on elevated shells near ,b4 ,ayres4 --on elevation of ,s4 ,blas4 --on the sudden elevation of ,la ,plata4 --on elevated shells near ,cobija4 --on elevated shells near ,arica4 --on the climate of ,peru4 --on salt deposits of ,cobija4 --on crystals of gypsum in salt-lakes4 --on absence of gypsum in the ,pampean formation4 --on fossil remains from ,bahia ,blanca4 --on fossil remains from the banks of the ,parana4 --on the geology of ,st4 ,fe4 --on the age of ,pampean formation4 --on the ,mastodon ,andium4 --on the geology of the ,rio ,negro4 --on the character of the ,patagonian fossils4 --on fossils from ,concepcion4 -- --from ,coquimbo4 -- --from ,payta4 --on fossil tertiary shells of ,chile4 --on cretaceous fossils of ,tierra del ,fuego4 -- --from the ,cordillera of ,chile4 ,earth1 marine origin of4 ,earthenware1 fossil4 ,earthquake1 effect of1 at ,s4 ,maria4 --elevation during1 at ,lemus4 --of #ahbb1 at ,valparaiso4 --effects of1 in shattering surface4 --fissures made by4 --probable effects on cleavage4 ,earthquakes in ,pampas4 ,earthquake-waves1 power of1 in throwing up shells4 --effects of1 near ,lima4 --power of1 in transporting boulders4 ,edmonston1 ,mr41 on depths at which shells live at ,valparaiso4 ,ehrenberg1 ,professor1 on infusoria in the ,pampean formation4 --on infusoria in the ,patagonian formation4 ,elevation of ,la ,plata4 --,brazil4 --,bahia ,blanca4 --,san ,blas4 --,patagonia4 --,tierra del ,fuego4 --,falkland islands4 --,pampas4 --,chonos archipelago4 --,chiloe4 --,chile4 --,valparaiso4 --,coquimbo4 --,guasco4 --,iquique4 --,cobija4 --,lima4 --sudden1 at ,s4 ,maria4 -- --at ,lemus4 --insensible1 at ,chiloe4 -- --at ,valparaiso4 -- --at ,coquimbo4 --axes of1 at ,chiloe4 -- --at ,p4 ,rumena4 --at ,concepcion4 --unfavourable for the accumulation of permanent deposits4 --lines of1 parallel to cleavage and foliation4 --lines of1 oblique to foliation4 --areas of1 causing lines of elevation and cleavage4 --lines of1 in the ,cordillera4 --slow1 in the ,portillo range4 --two periods of1 in ,cordillera of ,central ,chile4 --of the ,uspallata range4 --two periods of1 in ,cumbre ,pass4 --horizontal1 in the ,cordillera of ,copiapo4 --axes of1 coincident with volcanic orifices4 --of the ,cordillera1 summary on4 ,elliott1 ,captain1 on human remains4 ,ensenada1 elevated shells of4 ,entre ,rios1 geology of4 ,equus curvidens4 ,epidote in ,tierra del ,fuego4 --in gneiss4 --frequent in ,chile4 --in the ,uspallata range4 --in porphyry of ,coquimbo4 ,erman1 ,m41 on andesite4 ,escarpments1 recent1 of ,patagonia4 ,extinction of fossil mammifers4 ,falkland islands1 elevation of4 --pebbles on coast4 --geology of4 ,falkner1 on saline incrustations4 ,faults1 great1 in ,cordillera4 ,feldspar1 earthy1 metamorphosis of1 at ,port ,desire4 --albitic4 --crystals of1 with albite4 --orthitic1 in conglomerate of ,tenuyan4 --in granite of ,portillo range4 --in porphyries in the ,cumbre ,pass4 ,feuillee on sea-level at ,coquimbo4 ,fissures1 relations of1 to concretions4 --upfilled1 at ,port ,desire4 --in clay-slate4 ,fitton1 ,dr41 on the geology of ,tierra del ,fuego4 ,fitzroy1 ,captain1 on the elevation of the ,falkland islands4 --on the elevation of ,concepcion4 ,foliation1 definition of4 --of rocks at ,bahia4 --,rio de ,janeiro4 --,maldonado4 --,monte ,video4 --,s4 ,guitru-gueyu4 --,falkland ,i4 --,tierra del ,fuego4 --,chonos archipelago4 --,chiloe4 --,concepcion4 --,chile4 --discussion on4 ,forbes1 ,professor ,e41 on cretaceous fossils of ,concepcion4 --on cretaceous fossils and subsidence in ,cumbre ,pass4 --on fossils from ,guasco4 -- --from ,coquimbo4 -- --from ,copiapo4 --on depths at which shells live4 ,formation1 ,pampean4 -- --area of4 -- --estuary origin4 --tertiary of ,entre ,rios4 --of ,banda ,oriental4 --volcanic1 in ,banda ,oriental4 --of ,patagonia4 --summary on4 --tertiary of ,tierra del ,fuego4 -- --of the ,chonos archipelago4 -- --of ,chiloe4 -- --of ,chile4 -- --of ,concepcion4 -- --of ,navidad4 -- --of ,coquimbo4 -- --of ,peru4 -- --subsidence during4 --volcanic1 of ,tres ,montes4 -- --of ,chiloe4 -- --old1 near ,maldonado4 -- --with laminar structure4 -- --ancient1 in ,tierra del ,fuego4 --recent1 absent on ,s4 ,american coast4 --metamorphic1 of claystone-porphyry of ,patagonia4 --foliation of4 --plutonic1 with laminar structure4 --palaeozoic1 of the ,falkland ,i4 --claystone1 at ,concepcion4 --,jurassic1 of ,cordillera4 --,neocomian1 of the ,portillo ,pass4 --volcanic1 of ,cumbre ,pass4 --gypseous1 of ,los ,hornos4 -- --of ,coquimbo4 -- --of ,guasco4 -- --of ,copiapo4 -- --of ,iquique4 --cretaceo-oolitic1 of ,coquimbo4 -- --of ,guasco4 -- --of ,copiapo4 -- --of ,iquique4 ,fossils1 ,neocomian1 of ,portillo ,pass4 -- --of ,cumbre ,pass4 --secondary1 of ,coquimbo4 -- --of ,guasco4 -- --of ,copiapo4 -- --of ,iquique4 --palaeozoic1 from the ,falklands4 ,fragments of hornblende-rock in gneiss4 --of gneiss in gneiss4 ,freyer1 ,lieutenant1 on elevated shells of ,arica4 ,frezier on sea-level at ,coquimbo4 ,galapagos archipelago1 pseudo-dikes of4 ,gallegos1 ,port1 tertiary formation of4 ,garnets in gneiss4 --in mica-slate4 --at ,panuncillo4 ,gardichaud1 ,m41 on granites of ,brazil4 ,gay1 ,m41 on elevated shells4 --on boulders in the ,cordillera4 --on fossils from ,cordillera of ,coquimbo4 ,gill1 ,mr41 on brickwork transported by an earthquake-wave4 ,gillies1 ,dr41 on heights in the ,cordillera4 --on extension of the ,portillo range4 ,glen ,roy1 parallel roads of4 --sloping terraces of4 ,gneiss1 near ,bahia4 --of ,rio de ,janeiro4 --decomposition of4 ,gold1 distribution of4 ,gorodona1 formations near4 ,granite1 axis of oblique1 to foliation4 --andesitic4 --of ,portillo range4 --veins of1 quartzose4 --pebble of1 in porphyritic conglomerate4 --conglomerate4 ,grauwacke of ,uspallata range4 ,gravel at bottom of sea4 --formation of1 in ,patagonia4 --means of transportation of4 --strata of1 inclined4 ,gravel-terraces in ,cordillera4 ,greenough1 ,mr41 on quartz veins4 ,greenstone1 resulting from metamorphose hornblende-rock4 --of ,tierra del ,fuego4 --on the summit of the ,campana of ,quillota4 --porphyry4 --relation of1 to clay-slate4 ,gryphaea orientalis4 ,guasco1 elevation of4 --secondary formation of4 ,guitru-gueyu1 ,sierra4 ,guyana1 gneissic rocks of4 ,gypsum1 nodules of1 in gravel at ,rio ,negro4 --deposited from sea-water4 --deposits of1 at ,iquique4 --crystals of1 in salt lakes4 --in ,pampean formation4 --in tertiary formation of ,patagonia4 --great formation of1 in the ,portillo ,pass4 -- --in the ,cumbre ,pass4 -- --near ,los ,hornos4 -- --at ,coquimbo4 -- --at ,copiapo4 -- --near ,iquique4 --of ,san ,lorenzo4 ,hall1 ,captain1 on terraces at ,coquimbo4 ,hamilton1 ,mr41 on elevation near ,tacna4 ,harlan1 ,dr41 on human remains4 ,hayes1 ,mr4 ,a41 on nitrate of soda4 ,henslow1 ,professor1 on concretions4 ,herbert1 ,captain1 on valleys in the ,himalaya4 ,herradura ,bay1 elevated shells of4 --tertiary formations of4 ,himalaya1 valleys in4 ,hippurites ,chilensis4 ,hitchcock1 ,professor1 on dikes4 ,honestones1 pseudo1 of ,coquimbo4 --of ,copiapo4 ,hooker1 ,dr4 ,j4,d41 on fossil beech-leaves4 ,hopkins1 ,mr41 on axes of elevation oblique to foliation4 --on origin of lines of elevation4 ,hornblende-rock1 fragments of1 in gneiss4 ,hornblende-schist1 near ,m4 ,video4 ,hornos1 ,los1 section near4 ,hornstone1 dike of4 ,horse1 fossil tooth of4 ,huafo island4 --subsidence at4 ,huantajaya1 mines of4 ,humboldt1 on saline incrustations4 --on foliations of gneiss4 --on concretions in gneiss4 ,icebergs1 action on cleavage4 ,illapel1 section near4 ,imperial1 beds of shells near4 ,incrustations1 saline4 ,infusoria in ,pampean formation4 --in ,patagonian formation4 ,iodine1 salts of4 ,iquique1 elevation of4 --saliferous deposits of4 --cretaceo-oolitic formation of4 ,iron1 oxide of1 in lavas4 --in sedimentary beds4 --tendency in1 to produce hollow concretions4 --sulphate of4 ,isabelle1 ,m41 on volcanic rocks of ,banda ,oriental4 ,joints in clay-slate4 ,jukes1 ,mr41 on cleavage in ,newfoundland4 ,kamtschatka1 andesite of4 ,kane1 ,dr41 on the production of carbonate of soda4 ,king ,george's sound1 calcareous beds of4 ,lakes1 origin of4 --fresh-water1 near salt lakes4 ,lava1 basaltic1 of ,s4 ,cruz4 --claystone-porphyry1 at ,chiloe4 -- --ancient submarine4 --basaltic1 of the ,portillo range4 --feldspathic1 of the ,cumbre ,pass4 --submarine1 of the ,uspallata range4 --basaltic1 of the ,uspallata range4 --submarine1 of ,coquimbo4 --of ,copiapo4 ,lemus island4 ,lemuy islet4 ,lignite of ,chiloe4 --of ,concepcion4 ,lima1 elevation of4 ,lime1 muriate of4 ,limestone of ,cumbre ,pass4 --of ,coquimbo4 --of ,copiapo4 ,lund and ,clausen on remains of caves in ,brazil4 ,lund1 ,m41 on granites of ,brazil4 ,lyell1 ,m41 on upraised shells retaining their colours4 --on terraces at ,coquimbo4 --on elevation near ,lima4 --on fossil horse's tooth4 --on the boulder-formation being anterior to the extinction of ,north ,american mammifers4 --on quadrupeds washed down by floods4 --on age of ,american fossil mammifers4 --on changes of climate4 --on denudation4 --on foliation4 ,mac,culloch1 ,dr41 on concretions4 --on beds of marble4 ,maclaren1 ,mr41 letter to1 on coral-formations4 ,macrauchenia ,patachonica4 ,madeira1 subsidence of4 ,magellan1 ,strait1 elevation near1 of4 ,magnesia1 sulphate of1 in veins4 ,malcolmson1 ,dr41 on trees carried out to sea4 ,maldonado1 elevation of4 --,pampean formation of4 --crystalline rocks of4 ,mammalia1 fossil1 of ,bahia ,blanca4 -- --near ,st4 ,fe4 -- --of ,banda ,oriental4 -- --of ,st4 ,julian4 -- --at ,port ,gallegos4 --washed down by floods4 --number of remains of1 and range of1 in ,pampas4 ,man1 skeletons of 7,brazil74 --remains of1 near ,lima4 --,indian1 antiquity of4 ,marble1 beds of4 ,maricongo1 ravine of4 ,marsden1 on elevation of ,sumatra4 ,mastodon ,andium1 remains of4 --range of4 ,maypu1 ,rio1 mouth of1 with upraised shells4 --gravel fringes of4 --debouchement from the ,cordillera4 ,megalonyx1 range of4 ,megatherium1 range of4 ,miers1 ,mr41 on elevated shells4 --on the height of the ,uspallata plain4 ,minas1 ,las4 ,mocha ,island1 elevation of4 --tertiary form of4 --subsidence at4 ,molina1 on a great flood4 ,monte ,hermoso1 elevation of4 --fossils of4 ,monte ,video1 elevation of4 --,pampean formation of4 --crystalline rocks of4 ,morris and ,sharpe1 ,messrs41 on the palaeozoic fossils of the ,falklands4 ,mud1 ,pampean4 --long deposited on the same area4 ,murchison1 ,sir ,r41 on cleavage4 --on waves transporting gravel4 --on origin of salt formations4 --on the relations of metalliferous veins and intrusive rocks4 --on the absence of granite in the ,ural4 ,nautilus d',orbignyanus4 ,navidad1 tertiary formations of1 subsidence of4 ,negro1 ,rio1 pumice of pebbles of4 --gravel of4 --salt lakes of4 --tertiary strata of4 ,north ,america1 fossil remains of4 ,north ,wales1 sloping terraces absent in4 --bent cleavage of4 ,neuvo ,gulf1 plains of4 --tertiary formation of4 ,owen1 ,professor1 on fossil mammiferous remains4 ,palmer1 ,mr41 on transportation of gravel4 ,pampas1 elevation of4 --earthquakes of4 --formation of4 --localities in which fossil mammifers have been found4 ,panuncillo1 mines of4 ,parana1 ,rio1 on saline incrustations4 --,pampean formations near4 --on the ,s4 ,tandil4 ,parish1 ,sir ,w41 on elevated shells near ,buenos ,ayres4 --on earthquakes in the ,pampas4 --on fresh-water near salt lakes4 --on origin of ,pampean formation4 ,patagonia1 elevation and plains of4 --denudation of4 --gravel-formation of4 --sea-cliffs of4 --subsidence during tertiary period4 --crystalline rocks of4 ,payta1 tertiary formations of4 ,pebbles of pumice4 --decrease in size on the coast of ,patagonia4 --means of transportation4 --encrusted with living corallines4 --distribution of1 at the eastern foot of ,cordillera4 --dispersal of1 in the ,pampas4 --zoned with colour4 ,pentland1 ,mr41 on heights in the ,cordillera4 --on fossils of the ,cordillera4 ,pernambuco4 ,peru1 tertiary formations of4 ,peuquenes1 ,pass of1 in the ,cordillera4 --ridge of4 ,pholas1 elevated shells of4 ,pitchstone of ,chiloe4 --of ,port ,desire4 --near ,cauquenes4 --layers of1 in the ,uspallata range4 --of ,los ,hornos4 --of ,coquimbo4 ,plains of ,patagonia4 --of ,chiloe4 --of ,chile4 --of ,uspallata4 --on eastern foot of ,cordillera4 --of ,iquique4 ,plata1 ,la1 elevation of4 --tertiary formation of4 --crystalline rocks of4 ,playfair1 ,professor1 on the transportation of gravel4 ,pluclaro1 axis of4 ,pondicherry1 fossils of4 ,porcelain rocks of ,port ,desire4 --of the ,uspallata range4 ,porphyry1 pebbles of1 strewed over ,patagonia4 ,porphyry1 claystone1 of ,chiloe1 -- --of ,patagonia4 -- --of ,chile4 --greenstone1 of ,chile4 --doubly columnar4 --claystone1 rare1 on the eastern side of the ,portillo ,pass4 --brick-red and orthitic1 of ,cumbre ,pass4 --intrusive1 repeatedly injected4 --claystone of the ,uspallata range4 -- --of ,copiapo4 -- --eruptive sources of4 ,port ,desire1 elevation and plains of4 --tertiary formation of4 --porphyries of4 ,portillo ,pass in the ,cordillera4 ,portillo chain4 --compared with that of the ,uspallata4 ,prefil or sea-wall of ,valparaiso4 ,puente del ,inca1 section of4 ,pumice1 pebbles of4 --conglomerate of ,r4 ,negro4 --hills of1 in the ,cordillera4 ,punta ,alta1 elevation of4 --beds of4 ,quartz-rock of the ,s4 ,ventana4 --,c4 ,blanco4 --,falkland islands4 --,portillo range4 --viscidity of4 --veins of1 near ,monte ,video4 -- --in dike of greenstone4 --grains of1 in mica slate4 -- --in dikes4 --veins of1 relations to cleavage4 ,quillota1 ,campana of4 ,quintero1 elevation of4 ,quiriquina1 elevation of4 --deposits of4 ,rancagua1 plain of4 ,rapel1 ,r4 elevation near4 ,reeks1 ,mr4 ,t41 his analysis of decomposed shells4 --his analysis of salts4 ,remains1 human4 ,rio de ,janeiro1 elevation near4 --crystalline rocks of4 ,rivers1 small power of transporting pebbles4 --small power of1 in forming valleys4 --drainage of1 in the ,cordillera4 ,roads1 parallel1 of ,glen ,roy4 ,rocks1 volcanic1 of ,banda ,oriental4 --,tres ,montes4 --,chiloe4 --,tierra del ,fuego4 --with laminar structure4 ,rodents1 fossil1 remains of4 ,rogers1 ,professor1 address to ,association of ,american ,geologists4 ,rose1 ,professor ,g41 on sulphate of iron at ,copiapo4 ,s4 ,blas1 elevation of4 ,s4 ,cruz1 elevation and plains of4 --valley of4 --nature of gravel in valley of4 --boulder formation of4 --tertiary formation of4 --subsidence at4 ,s4 ,fe ,bajada1 formations of4 ,s4 ,george's bay1 plains of4 ,s4 ,helena island1 sea-cliffs1 and subsidence of4 ,s4 ,josef1 elevation of4 --tertiary formation of4 ,s4 ,juan1 elevation near4 ,s4 ,julian1 elevation and plains of4 --salt lake of4 --earthy deposit with mammiferous remains4 --tertiary formations of4 --subsidence at4 ,s4 ,lorenzo1 elevation of4 --old salt formation of4 ,s4 ,mary1 island of1 elevation of4 ,s4 ,pedro1 elevation of4 ,salado1 ,r41 elevated shells of4 --,pampean formation of4 ,salines4 ,salt1 with upraised shell4 --lakes of4 --purity of1 in salt lakes4 --deliquescent1 necessary for the preservation of meat4 --ancient formation of1 at ,iquique4 -- --at ,s4 ,lorenzo4 --strata of1 origin of4 ,salts1 superficial deposits of4 ,sand-dunes of the ,uruguay4 --of the ,pampas4 --near ,bahia ,blanca4 --of the ,colorado4 --of ,s4 ,cruz4 --of ,arica4 ,sarmiento1 ,mount4 ,schmidtmeyer on auriferous detritus4 ,schomburghk1 ,sir ,r41 on sea-bottom4 --on the rocks of ,guyana4 ,scotland1 sloping terraces of4 ,sea1 nature of bottom of1 off ,patagonia4 --power of1 in forming valleys4 ,sea cliffs1 formation of4 ,seale1 ,mr41 model of ,st4 ,helena4 ,sebastian ,bay1 tertiary formation of4 ,sedgwick1 ,professor1 on cleavage4 ,serpentine of ,copiapo4 ,serpulae1 on upraised rocks4 ,shale-rock1 of the ,portillo ,pass4 --of ,copiapo4 ,shells1 upraised state of1 in ,patagonia4 --elevated1 too small for human food4 --transported far inland1 for food4 --upraised1 proportional numbers varying4 -- --gradual decay of4 -- --absent on high plains of ,chile4 -- --near ,bahia ,blanca4 --preserved in concretions4 --living and fossil range of1 on west coast4 --living1 different on the east and west coast4 ,shingle of ,patagonia4 ,siau1 ,m41 on sea-bottom4 ,silver mines of ,arqueros4 --of ,chanuncillo4 --of ,iquique4 --distribution of4 ,slip1 great1 at ,s4 ,cruz4 ,smith1 ,mr41 of ,jordan ,hill1 on upraised shells retaining their colours4 --on ,madeira4 --on elevated seaweed4 --on inclined gravel beds4 ,soda1 nitrate of4 --sulphate of1 near ,bahia ,blanca4 --carbonate of4 ,soundings off ,patagonia4 --in ,tierra del ,fuego4 ,spirifers4 ,spix and ,martius on ,brazil4 ,sprengel on the production of carbonate of soda4 ,springs1 mineral1 in the ,cumbre ,pass4 ,stratification of sandstone in metamorphic rocks4 --of clay-slate in ,tierra del ,fuego4 --of the ,cordillera of ,central ,chile4 --little disturbed in ,cumbre ,pass4 --disturbance of1 near ,copiapo4 ,streams of lava at ,s4 ,cruz1 inclination of4 --in the ,portillo range4 ,string of cotton with fossil-shells4 ,struthiolaria ornata4 ,studer1 ,m41 on metamorphic rocks4 ,subsidence during formation of sea-cliffs4 --near ,lima4 --probable1 during ,pampean formation4 --necessary for the accumulation of permanent deposits4 --during the tertiary formations of ,chile and ,patagonia4 --probable during the ,neocomian formation of the ,portillo ,pass4 --probable during the formation of conglomerate of ,tenuyan4 --during the ,neocomian formation of the ,cumbre ,pass4 --of the ,uspallata range4 --great1 at ,copiapo4 -- --during the formation of the ,cordillera4 ,sulphur1 volcanic exhalations of4 ,sumatra1 promontories of4 ,a ,summary on the recent elevatory movements4 --on the ,pampean formation4 --on the tertiary formations of ,patagonia and ,chile4 --on the ,chilean ,cordillera4 --on the cretaceo-oolitic formation4 --on the subsidences of the ,cordillera4 --on the elevation of the ,cordillera4 ,tacna1 elevation of4 ,tampico1 elevated shells near4 ,tandil1 crystalline rocks of4 ,tapalguen1 ,pampean formation of4 --crystalline rocks of4 ,taylor1 ,mr41 on copper veins of ,cuba4 ,temperature of ,chile during the tertiary period4 ,tension1 lines of1 origin of1 axes of elevation and of cleavage4 ,tenuy ,point1 singular section of4 ,tenuyan1 valley of4 ,terraces of the valley of ,s4 ,cruz4 --of equable heights throughout ,patagonia4 --of ,patagonia1 formation of4 --of ,chiloe4 --at ,conchalee4 --of ,coquimbo4 --not horizontal at ,coquimbo4 --of ,guasco4 --of ,s4 ,lorenzo4 --of gravel within the ,cordillera4 ,theories on the origin of the ,pampean formation4 ,tierra ,amarilla4 ,tierra del ,fuego1 form of sea-bottom4 --tertiary formations of4 --clay-slate formation of4 --cretaceous formation of4 --crystalline rocks of4 --cleavage of clay-slate4 ,tosca rock4 ,trachyte of ,chiloe4 --of ,port ,desire4 --in the ,cordillera4 ,traditions of promontories having been islands4 --on changes of level near ,lima4 ,trees buried in plain of ,iquique4 --silicified1 vertical1 of the ,uspallata range4 ,tres ,montes1 elevation of4 --volcanic rocks of4 ,trigonocelia insolita4 ,tristan ,arroyo1 elevated shells of4 ,tschudi1 ,mr41 on subsidence near ,lima4 ,tuff1 calcareous1 at ,coquimbo4 --on basin-plain near ,st4 ,jago4 --structure of1 in ,pampas4 --origin of1 in ,pampas4 --pumiceous1 of ,r4 ,negro4 --,nuevo ,gulf4 --,port ,desire4 --,s4 ,cruz4 --,patagonia1 summary on ,chiloe4 --formation of1 in ,portillo chain4 --great deposit of1 at ,copiapo4 ,tuffs1 volcanic1 metamorphic1 of ,uspallata4 --of ,coquimbo4 ,ulloa1 on rain in ,peru4 --on elevation near ,lima4 ,uruguay1 ,rio1 elevation of country near4 ,uspallata1 plain of4 --pass of4 --range of4 --concluding remarks on4 ,valdivia1 tertiary beds of4 --mica-slate of4 ,valley of ,s4 ,cruz1 structure of4 --,coquimbo4 --,guasco1 structure of4 --,copiapo1 structure of4 --,s4 ,cruz1 tertiary formations of4 --,coquimbo1 geology of4 --,guasco1 secondary formations of4 --,copiapo1 secondary formations of4 --,despoblado4 ,valleys in the ,cordillera bordered by gravel fringes4 --formation of4 --in the ,cordillera4 ,valparaiso1 elevation of4 --gneiss of4 ,vein of quartz near ,monte ,video4 --in mica-slate4 --relations of1 to cleavage4 --in a trap dike4 --of granite1 quartzose4 --remarkable1 in gneiss1 near ,valparaiso4 ,veins1 relations of1 to concretions4 --metalliferous1 of the ,uspallata range4 --metalliferous1 discussion on4 ,venezuela1 gneissic rocks of4 ,ventana1 ,sierra1 ,pampean formation near4 --quartz-rock of4 ,villa ,vincencio ,pass4 ,volcan1 ,rio1 mouth of4 --fossils of4 ,volcanoes of the ,cordillera4 --absent1 except near bodies of water4 --ancient submarine1 in ,cordillera4 --action of1 in relation to changes of level4 --long action of1 in the ,cordillera4 ,wafer on elevated shells4 ,waves caused by earthquakes1 power of1 in transporting boulders4 --power of1 in throwing up shells4 ,weaver1 ,mr41 on elevated shells4 ,white1 ,martin41 on sea-bottom4 ,wood1 silicified1 of ,entre ,rios4 --,s4 ,cruz4 --,chiloe4 --,uspallata range4 --,los ,hornos4 --,copiapo4 ,yeso1 ,rio1 and plain of4 ,ypun ,island1 tertiary formation of4 ,zeagonite4