,the ,student's ,elements of ,geology ,by ,,sir ,,charles ,,lyell1 ,,bart41 ,f4,r4,s4 ,,author ,,of 8,,the ,,principles ,,of ,,geology10 8,,the ,,antiquity ,,of ,,man10 ,,etc4 ,thecosmilia annularis ,,with ,,more ,,than #fjj ,,illustrations ,,on ,,wood4 ,,new ,,york ,,harper ,,brothers1 ,,publishers #ahgh ,tertiary or ,cainozoic1 ,secondary or ,mesozoic1 ,primary or ,paleozoic ,,contents4 ,,preface ,chapter ,i--,,on ,,the ,,different ,,classes ,,of ,,rocks4 ,geology defined4 -- ,successive ,formation of the ,earth's ,crust4 -- ,classification of ,rocks according to their ,origin and ,age4 -- ,aqueous ,rocks4 -- ,their ,stratification and imbedded ,fossils4 -- ,volcanic ,rocks1 with and without ,cones and ,craters4 -- ,plutonic ,rocks1 and their ,relation to the ,volcanic4 -- ,metamorphic ,rocks1 and their probable ,origin4 -- ,the term ,primitive1 why erroneously applied to the ,crystalline ,formations4 -- ,leading ,division of the ,work4 ,chapter ,,ii--,,aqueous ,,rocks--,,their ,,composition ,,and ,,forms ,,of ,,stratification4 ,mineral ,composition of ,strata4 -- ,siliceous ,rocks4 -- ,argillaceous4 -- ,calcareous4 -- ,gypsum4 -- ,forms of ,stratification4 -- ,original ,horizontality4 -- ,thinning out4 -- ,diagonal ,arrangement4 -- ,ripple-mark4 ,chapter ,,iii--,,arrangement ,,of ,,fossils ,,in ,,strata--,,fresh-,,water ,,and ,,marine4 ,successive ,deposition indicated by ,fossils4 -- ,limestones formed of ,corals and ,shells4 -- ,proofs of gradual ,increase of ,strata derived from ,fossils4 -- ,serpula attached to ,spatangus4 -- ,wood bored by ,teredina4 -- ,tripoli formed of ,infusoria4 -- ,chalk derived principally from ,organic ,bodies4 -- ,distinction of ,fresh-water from ,marine ,formations4 -- ,genera of ,fresh-water and ,land ,shells4 -- ,rules for recognising ,marine ,testacea4 -- ,gyrogonite and ,chara4 -- ,fresh-water ,fishes4 -- ,alternation of ,marine and ,fresh-water ,deposits4 -- ,lym-,fiord4 ,chapter ,,iv--,,consolidation ,,of ,,strata ,,and ,,petrifaction ,,of ,,fossils4 ,chemical and ,mechanical ,deposits4 -- ,cementing together of ,particles4 -- ,hardening by ,exposure to ,air4 -- ,concretionary ,nodules4 -- ,consolidating ,effects of ,pressure4 -- ,mineralization of ,organic ,remains4 -- ,impressions and ,casts3 how formed4 -- ,fossil ,wood4 -- ,goppert's ,experiments4 -- ,precipitation of ,stony ,matter most rapid where ,putrefaction is going on4 -- ,sources of ,lime and ,silex in ,solution4 ,chapter ,v--,,elevation ,,of ,,strata ,,above ,,the ,,sea4--,,horizontal ,,and ,,inclined ,,stratification4 ,why the ,position of ,marine ,strata1 above the ,level of the ,sea1 should be referred to the rising up of the ,land1 not to the going down of the ,sea4 -- ,strata of ,deep-sea and ,shallow-water ,origin alternate4 -- ,also ,marine and ,fresh-water ,beds and old ,land ,surfaces4 -- ,vertical1 inclined1 and folded ,strata4 -- ,anticlinal and ,synclinal ,curves4 -- ,theories to explain ,lateral ,movements4 -- ,creeps in ,coal-mines4 -- ,dip and ,strike4 -- ,structure of the ,jura4 -- ,various ,forms of ,outcrop4 -- ,synclinal ,strata forming ,ridges4 -- ,connection of ,fracture and ,flexure of ,rocks4 -- ,inverted ,strata4 -- ,faults described4 -- ,superficial ,signs of the same obliterated by ,denudation4 -- ,great ,faults the ,result of repeated ,movements4 -- ,arrangement and ,direction of parallel ,folds of ,strata4 -- ,unconformability4 -- ,overlapping ,strata4 ,chapter ,,vi--,,denudation4 ,denudation defined4 -- ,its ,amount more than equal to the entire ,mass of ,stratified ,deposits in the ,earth's ,crust4 -- subarial ,denudation4 -- ,action of the ,wind4 -- ,action of ,running ,water4 -- ,alluvium defined4 -- ,different ,ages of ,alluvium4 -- ,denuding ,power of ,rivers affected by ,rise or ,fall of ,land4 -- ,littoral ,denudation4 -- ,inland ,sea-,cliffs4 -- ,escarpments4 -- ,submarine ,denudation4 -- ,dogger-bank4 -- ,newfoundland ,bank4 -- ,denuding ,power of the ,ocean during ,emergence of ,land4 ,chapter ,,vii--,,joint ,,action ,,of ,,denudation1 ,,upheaval1 ,,and ,,subsidence ,,in ,,remodelling ,,the ,,earth',s ,,crust4 ,how we obtain an ,insight at the ,surface1 of the ,arrangement of ,rocks at great ,depths4 -- ,why the ,height of the successive ,strata in a given ,region is so disproportionate to their ,thickness4 -- ,computation of the average annual ,amount of subarial ,denudation4 -- ,antagonism of ,volcanic ,force to the ,levelling ,power of running ,water4 -- ,how far the ,transfer of ,sediment from the ,land to a neighbouring ,sea-bottom may affect ,subterranean ,movements4 -- ,permanence of ,continental and ,oceanic ,areas4 ,chapter ,,viii--,,chronological ,,classification ,,of ,,rocks4 ,aqueous1 ,plutonic1 volcanic1 and metamorphic ,rocks considered chronologically4 -- ,terms ,primary1 ,secondary1 and ,tertiary2 ,palozoic1 ,mesozoic1 and ,cainozoic explained4 -- ,on the different ,ages of the aqueous ,rocks4 -- ,three principal ,tests of relative ,age3 ,superposition1 ,mineral ,character1 and ,fossils4 -- ,change of ,mineral ,character and ,fossils in the same continuous ,formation4 -- ,proofs that distinct ,species of ,animals and ,plants have lived at successive ,periods4 -- ,distinct ,provinces of indigenous ,species4 -- ,great ,extent of single ,provinces4 -- ,similar ,laws prevailed at successive ,geological ,periods4 -- ,relative ,importance of mineral and palontological ,characters4 -- ,test of ,age by included ,fragments4 -- ,frequent ,absence of ,strata of intervening ,periods4 -- ,tabular ,views of fossiliferous ,strata4 ,chapter ,,ix--,,classification ,,of ,,tertiary ,,formations4 ,order of ,succession of ,sedimentary ,formations4 -- ,frequent ,unconformability of ,strata4 -- ,imperfection of the ,record4 -- ,defectiveness of the ,monuments greater in ,proportion to their ,antiquity4 -- ,reasons for studying the newer ,groups first4 -- ,nomenclature of ,formations4 -- ,detached ,tertiary ,formations scattered over ,europe4 -- ,value of the ,shell-bearing ,mollusca in ,classification4 -- ,classification of ,tertiary ,strata4 -- ,eocene1 ,miocene1 and ,pliocene ,terms explained4 ,chapter ,x--,,recent ,,and ,,post-,,pliocene ,,periods4 ,recent and ,post-pliocene ,periods4 -- ,terms defined4 -- ,formations of the ,recent ,period4 -- ,modern littoral ,deposits containing ,works of ,art near ,naples4 -- ,danish ,peat and ,shell-mounds4 -- ,swiss ,lake-dwellings4 -- ,periods of ,stone1 ,bronze1 and ,iron4 -- ,post-pliocene ,formations4 -- ,coexistence of ,man with extinct ,mammalia4 -- ,reindeer ,period of ,south of ,france4 -- ,alluvial ,deposits of ,paleolithic ,age4 -- ,higher and ,lower-level ,valley-gravels4 -- ,loess or ,inundation-mud of the ,nile1 ,rhine1 etc4 -- ,origin of ,caverns4 -- ,remains of ,man and extinct ,quadrupeds in ,cavern ,deposits4 -- ,cave of ,kirkdale4 -- ,australian ,cave-breccias4 -- ,geographical ,relationship of the ,provinces of living ,vertebrata and those of extinct ,post-pliocene ,species4 -- ,extinct struthious ,birds of ,new ,zealand4 -- ,climate of the ,post-pliocene ,period4 -- ,comparative ,longevity of ,species in the ,mammalia and ,testacea4 -- ,teeth of ,recent and ,post-pliocene ,mammalia4 ,chapter ,,xi--,,post-,,pliocene ,,period1 continued4--,,glacial ,,conditions4 ,geographical ,distribution1 ,form1 and ,characters of ,glacial ,drift4 -- ,fundamental ,rocks1 polished1 grooved1 and scratched4 -- ,abrading and striating ,action of ,glaciers4 -- ,moraines1 ,erratic ,blocks1 and 8,roches ,moutonnees04 -- ,alpine ,blocks on the ,jura4 -- ,continental ,ice of ,greenland4 -- ,ancient ,centres of the ,dispersion of ,erratics4 -- ,transportation of ,drift by floating ,icebergs4 -- ,bed of the ,sea furrowed and polished by the running aground of floating ,ice-islands4 ,chapter ,,xii--,,post-,,pliocene ,,period1 continued4--,,glacial ,,conditions1 concluded4 ,glaciation of ,scandinavia and ,russia4 -- ,glaciation of ,scotland4 -- ,mammoth in ,scotch ,till4 -- ,marine ,shells in ,scotch ,glacial ,drift4 -- ,their ,arctic ,character4 -- ,rarity of ,organic ,remains in ,glacial ,deposits4 -- ,contorted ,strata in ,drift4 -- ,glaciation of ,wales1 ,england1 and ,ireland4 -- ,marine ,shells of ,moel ,tryfaen4 -- ,erratics near ,chichester4 -- ,glacial ,formations of ,north ,america4 -- ,many ,species of ,testacea and ,quadrupeds survived the ,glacial ,cold4 -- ,connection of the ,predominance of ,lakes with ,glacial ,action4 -- ,action of ,ice in preventing the silting up of ,lake-basins4 -- ,absence of ,lakes in the ,caucasus4 -- ,equatorial ,lakes of ,africa4 ,chapter ,,xiii--,,pliocene ,,period4 ,glacial ,formations of ,pliocene ,age4 -- ,bridlington ,beds4 -- ,glacial ,drifts of ,ireland4 -- ,drift of ,norfolk ,cliffs4 -- ,cromer ,forest-bed4 -- ,aldeby and ,chillesford ,beds4 -- ,norwich ,crag4 -- ,older ,pliocene ,strata4 -- ,red ,crag of ,suffolk4 -- ,coprolitic ,bed of ,red ,crag4 -- ,white or ,coralline ,crag4 -- ,relative ,age1 ,origin1 and ,climate of the ,crag ,deposits4 -- ,antwerp ,crag4 -- ,newer ,pliocene ,strata of ,sicily4 -- ,newer ,pliocene ,strata of the ,upper ,val d',arno4 -- ,older ,pliocene of ,italy4 -- ,subapennine ,strata4 -- ,older ,pliocene ,flora of ,italy4 ,chapter ,,xiv--,,miocene ,,period4--,,upper ,,miocene4 ,upper ,miocene ,strata of ,france4 -- ,faluns of ,touraine4 -- ,tropical ,climate implied by ,testacea4 -- ,proportion of recent ,species of ,shells4 -- faluns more ancient than the ,suffolk ,crag4 -- ,upper ,miocene of ,bordeaux and the ,south of ,france4 -- ,upper ,miocene of ,oeningen1 in ,switzerland4 -- ,plants of the ,upper ,fresh-water ,molasse4 -- ,fossil ,fruit and ,flowers as well as ,leaves4 -- ,insects of the ,upper ,molasse4 -- ,middle or ,marine ,molasse of ,switzerland4 -- ,upper ,miocene ,beds of the ,bolderberg1 in ,belgium4 -- ,vienna ,basin4 -- ,upper ,miocene of ,italy and ,greece4 -- ,upper ,miocene of ,india2 ,siwalik ,hills4 -- ,older ,pliocene and ,miocene of the ,united ,states4 ,chapter ,,xv--,,lower ,,miocene4 ,lower ,miocene ,strata of ,france4 -- ,line between ,miocene and ,eocene4 -- ,lacustrine ,strata of ,auvergne4 -- ,fossil ,mammalia of the ,limagne d',auvergne4 -- ,lower ,molasse of ,switzerland4 -- ,dense ,conglomerates and ,proofs of ,subsidence4 -- ,flora of the ,lower ,molasse4 -- ,american ,character of the ,flora4 -- ,theory of a ,miocene ,atlantis4 -- ,lower ,miocene of ,belgium4 -- ,rupelian ,clay of ,hermsdorf near ,berlin4 -- ,mayence ,basin4 -- ,lower ,miocene of ,croatia4 -- ,oligocene ,strata of ,beyrich4 -- ,lower ,miocene of ,italy4 -- ,lower ,miocene of ,england4 -- ,hempstead ,beds4 -- ,bovey ,tracey ,lignites in ,devonshire4 -- ,isle of ,mull ,leaf-,beds4 -- ,arctic ,miocene ,flora4 -- ,disco ,island4 -- ,lower ,miocene of ,united ,states4 -- ,fossils of ,nebraska4 ,chapter ,,xvi--,,eocene ,,formations4 ,eocene ,areas of ,north of ,europe4 -- ,table of ,english and ,french ,eocene ,strata4 -- ,upper ,eocene of ,england4 -- ,bembridge ,beds4 -- ,osborne or ,st4 ,helen's ,beds4 -- ,headon ,series4 -- ,fossils of the ,barton ,sands and ,clays4 -- ,middle ,eocene of ,england4 -- ,shells1 ,nummulites1 ,fish and ,reptiles of the ,bracklesham ,beds and ,bagshot ,sands4 -- ,plants of ,alum ,bay and ,bournemouth4 -- ,lower ,eocene of ,england4 -- ,london ,clay ,fossils4 -- ,woolwich and ,reading ,beds formerly called 8,plastic ,clay04 -- ,fluviatile ,beds underlying ,deep-sea ,strata4 -- ,thanet ,sands4 -- ,upper ,eocene ,strata of ,france4 -- ,gypseous ,series of ,montmartre and ,extinct ,quadrupeds4 -- ,fossil ,footprints in ,paris ,gypsum4 -- ,imperfection of the ,record4 -- ,calcaire ,silicieux4 -- ,gres de ,beauchamp4 -- ,calcaire ,grossier4 -- ,miliolite ,limestone4 -- ,soissonnais ,sands4 -- ,lower ,eocene of ,france4 -- ,nummulitic ,formations of ,europe1 ,africa1 and ,asia4 -- ,eocene ,strata in the ,united ,states4 -- ,gigantic ,cetacean4 ,chapter ,,xvii--,,upper ,,cretaceous ,,group4 ,lapse of ,time between ,cretaceous and ,eocene ,periods4 -- ,table of successive ,cretaceous ,formations4 -- ,maestricht ,beds4 -- ,pisolitic ,limestone of ,france4 -- ,chalk of ,faxoe4 -- ,geographical ,extent and ,origin of the ,white ,chalk4 -- ,chalky ,matter now forming in the ,bed of the ,atlantic4 -- ,marked ,difference between the ,cretaceous and existing ,fauna4 -- ,chalk-flints4 -- ,pot-stones of ,horstead4 -- ,vitreous ,sponges in the ,chalk4 -- ,isolated ,blocks of ,foreign ,rocks in the ,white ,chalk supposed to be ice-borne4 -- ,distinctness of ,mineral ,character in contemporaneous ,rocks of the ,cretaceous ,epoch4 -- ,fossils of the ,white ,chalk4 -- ,lower ,white ,chalk without ,flints4 -- ,chalk ,marl and its ,fossils4 -- ,chloritic ,series or ,upper ,greensand4 -- ,coprolite ,bed near ,cambridge4 -- ,fossils of the ,chloritic ,series4 -- ,gault4 -- ,connection between ,upper and ,lower ,cretaceous ,strata4 -- ,blackdown ,beds4 -- ,flora of the ,upper ,cretaceous ,period4 -- ,hippurite ,limestone4 -- ,cretaceous ,rocks in the ,united ,states4 ,chapter ,,xviii--,,lower ,,cretaceous ,,or ,,neocomian ,,formation4 ,classification of marine and fresh-water ,strata4 -- ,upper ,neocomian4 -- ,folkestone and ,hythe ,beds4 -- ,atherfield ,clay4 -- ,similarity of ,conditions causing ,reappearance of ,species after short ,intervals4 -- ,upper ,speeton ,clay4 -- ,middle ,neocomian4 -- ,tealby ,series4 -- ,middle ,speeton ,clay4 -- ,lower ,neocomian4 -- ,lower ,speeton ,clay4 -- ,wealden ,formation4 -- ,fresh-water ,character of the ,wealden4 -- ,weald ,clay4 -- ,hastings ,sands4 -- ,punfield ,beds of ,purbeck1 ,dorsetshire4 -- ,fossil ,shells and ,fish of the ,wealden4 -- ,area of the ,wealden4 -- ,flora of the ,wealden4 ,chapter ,,xix--,,jurassic ,,group4--,,purbeck ,,beds ,,and ,,oolite4 ,the ,purbeck ,beds a ,member of the ,jurassic ,group4 -- ,subdivisions of that ,group4 -- ,physical ,geography of the ,oolite in ,england and ,france4 -- ,upper ,oolite4 -- ,purbeck ,beds4 -- ,new ,genera of fossil ,mammalia in the ,middle ,purbeck of ,dorsetshire4 -- ,dirt-bed or ancient ,soil4 -- ,fossils of the ,purbeck ,beds4 -- ,portland ,stone and ,fossils4 -- ,kimmeridge ,clay4 -- ,lithographic ,stone of ,solenhofen4 -- ,archopteryx4 -- ,middle ,oolite4 -- ,coral ,rag4 -- ,nerina ,limestone4 -- ,oxford ,clay1 ,ammonites and ,belemnites4 -- ,kelloway ,rock4 -- ,lower1 or ,bath1 ,oolite4 -- ,great ,plants of the ,oolite4 -- ,oolite and ,bradford ,clay4 -- ,stonesfield ,slate4 -- ,fossil ,mammalia4 -- ,fuller's ,earth4 -- ,inferior ,oolite and ,fossils4 -- ,northamptonshire ,slates4 -- ,yorkshire ,oolitic ,coal-field4 -- ,brora ,coal4 -- ,palontological ,relations of the several ,subdivisions of the ,oolitic group4 ,chapter ,,xx--,,jurassic ,,group1 ,,continued4--,,lias4 ,mineral ,character of ,lias4 -- ,numerous successive ,zones in the ,lias1 marked by distinct ,fossils1 without ,unconformity in the ,stratification1 or ,change in the ,mineral ,character of the ,deposits4 -- ,gryphite ,limestone4 -- ,shells of the ,lias4 -- ,fish of the ,lias4 -- ,reptiles of the ,lias4 -- ,ichthyosaur and ,plesiosaur4 -- ,marine ,reptile of the ,galapagos ,islands4 -- ,sudden ,destruction and ,burial of ,fossil ,animals in ,lias4 -- ,fluvio-marine ,beds in ,gloucestershire1 and ,insect ,limestone4 -- ,fossil ,plants4 -- ,the origin of the ,oolite and ,lias1 and of alternating ,calcareous and ,argillaceous ,formations4 ,chapter ,,xxi--,,trias1 ,,or ,,new ,,red ,,sandstone ,,group4 ,beds of ,passage between the ,lias and ,trias1 ,rhtic ,beds4 -- ,triassic ,mammifer4 -- ,triple ,division of the ,trias4 -- ,keuper1 or ,upper ,trias of ,england4 -- ,reptiles of the ,upper ,trias4 -- ,foot-prints in the ,bunter formation in ,england4 -- ,dolomitic ,conglomerate of ,bristol4 -- ,origin of ,red ,sandstone and ,rock-salt4 -- ,precipitation of ,salt from inland ,lakes and ,lagoons4 -- ,trias of ,germany4 -- ,keuper4 -- ,st4 ,cassian and ,hallstadt ,beds4 -- ,peculiarity of their ,fauna4 -- ,muschelkalk and its ,fossils4 -- ,trias of the ,united ,states4 -- ,fossil ,foot-prints of ,birds and ,reptiles in the ,valley of the ,connecticut4 -- ,triassic ,mammifer of ,north ,carolina4 -- ,triassic ,coal-field of ,richmond1 ,virginia4 -- ,low ,grade of early ,mammals favourable to the ,theory of ,progressive ,development4 ,chapter ,,xxii--,,permian ,,or ,,magnesian ,,limestone ,,group4 ,line of ,separation between ,mesozoic and ,palozoic ,rocks4 -- ,distinctness of ,triassic and ,permian ,fossils4 -- ,term ,permian4 -- ,thickness of calcareous and sedimentary ,rocks in ,north of ,england4 -- ,upper1 ,middle1 and ,lower ,permian4 -- ,marine ,shells and ,corals of the ,english ,magnesian ,limestone4 -- ,reptiles and ,fish of ,permian ,marl-slate4 -- ,foot-prints of ,reptiles4 -- ,angular ,breccias in ,lower ,permian4 -- ,permian ,rocks of the ,continent4 -- ,zechstein and ,rothliegendes of ,thuringia4 -- ,permian ,flora4 -- ,its generic ,affinity to the ,carboniferous4 ,chapter ,,xxiii--,,the ,,coal ,,or ,,carboniferous ,,group4 ,principal ,subdivisions of the ,carboniferous ,group4 -- ,different ,thickness of the sedimentary and calcareous ,members in ,scotland and the ,south of ,england4 -- ,coal-measures4 -- ,terrestrial ,nature of the ,growth of ,coal4 -- ,erect fossil ,trees4 -- ,uniting of many ,coal-seams into one thick ,bed4 -- ,purity of the ,coal explained4 -- ,conversion of ,coal into ,anthracite4 -- ,origin of ,clay-ironstone4 -- ,marine and brackish-water ,strata in ,coal4 -- ,fossil ,insects4 -- ,batrachian ,reptiles4 -- ,labyrinthodont ,foot-prints in ,coal-measures4 -- ,nova ,scotia ,coal-measures with successive ,growths of erect fossil ,trees4 -- ,similarity of ,american and ,european ,coal4 -- ,air-breathers of the ,american ,coal4 -- ,changes of ,condition of ,land and ,sea indicated by the ,carboniferous ,strata of ,nova ,scotia4 ,chapter ,,xxiv--,,flora ,,and ,,fauna ,,of ,,the ,,carboniferous ,,period4 ,vegetation of the ,coal ,period4 -- ,ferns1 ,lycopodiace1 ,equisetace1 ,sigillari1 ,stigmari1 ,conifer4 -- ,angiosperms4 -- ,climate of the ,coal ,period4 -- ,mountain ,limestone4 -- ,marine ,fauna of the ,carboniferous ,period4 -- ,corals4 -- ,bryozoa1 ,crinoidea4 -- ,mollusca4 -- ,great ,number of fossil ,fish4 -- ,foraminifera4 ,chapter ,,xxv--,,devonian ,,or ,,old ,,red ,,sandstone ,,group4 ,classification of the ,old ,red ,sandstone in ,scotland and in ,devonshire4 -- ,upper ,old ,red ,sandstone in ,scotland1 with ,fish and ,plants4 -- ,middle ,old ,red ,sandstone4 -- ,classification of the ,ichthyolites of the ,old ,red1 and their ,relation to ,living ,types4 -- ,lower ,old ,red ,sandstone1 with ,cephalaspis and ,pterygotus4 -- ,marine or ,devonian ,type of ,old ,red ,sandstone4 -- ,table of ,devonian ,series4 -- ,upper ,devonian ,rocks and ,fossils4 -- ,middle4 -- ,lower4 -- ,eifel ,limestone of ,germany4 -- ,devonian of ,russia4 -- ,devonian ,strata of the ,united ,states and ,canada4 -- ,devonian ,plants and ,insects of ,canada4 ,chapter ,,xxvi--,,silurian ,,group4 ,classification of the ,silurian ,rocks4 -- ,ludlow ,formation and ,fossils4 -- ,bone-bed of the ,upper ,ludlow4 -- ,lower ,ludlow ,shales with ,pentamerus4 -- ,oldest known ,remains of fossil ,fish4 -- ,table of the progressive ,discovery of ,vertebrata in older ,rocks4 -- ,wenlock ,formation1 ,corals1 ,cystideans and ,trilobites4 -- ,llandovery ,group or ,beds of ,passage4 -- ,lower ,silurian ,rocks4 -- ,caradoc and ,bala ,beds4 -- ,brachiopoda4 -- ,trilobites4 -- ,cystide4 -- ,graptolites4 -- ,llandeilo ,flags4 -- ,arenig or ,stiper-stones ,group4 -- ,foreign ,silurian ,equivalents in ,europe4 -- ,silurian ,strata of the ,united ,states4 -- ,canadian ,equivalents4 -- ,amount of specific ,agreement of ,fossils with those of ,europe4 ,chapter ,,xxvii--,,cambrian ,,and ,,laurentian ,,groups4 ,classification of the ,cambrian ,group1 and its ,equivalent in ,bohemia4 -- ,upper ,cambrian ,rocks4 -- ,tremadoc ,slates and their ,fossils4 -- ,lingula ,flags4 -- ,lower ,cambrian ,rocks4 -- ,menevian ,beds4 -- ,longmynd ,group4 -- ,harlech ,grits with large ,trilobites4 -- ,llanberis ,slates4 -- ,cambrian ,rocks of ,bohemia4 -- ,primordial ,zone of ,barrande4 -- ,metamorphosis of ,trilobites4 -- ,cambrian ,rocks of ,sweden and ,norway4 -- ,cambrian ,rocks of the ,united ,states and ,canada4 -- ,potsdam ,sandstone4 -- ,huronian ,series4 -- ,laurentian ,group1 upper and lower4 -- ,eozoon ,canadense1 oldest known ,fossil4 -- ,fundamental ,gneiss of ,scotland4 ,chapter ,,xxviii--,,volcanic ,,rocks4 ,external ,form1 ,structure1 and ,origin of ,volcanic ,mountains4 -- ,cones and ,craters4 -- ,hypothesis of 8,elevation ,craters0 considered4 -- ,trap ,rocks4 -- ,name whence derived4 -- ,minerals most abundant in ,volcanic ,rocks4 -- ,table of the ,analysis of ,minerals in the ,volcanic and ,hypogene ,rocks4 -- ,similar ,minerals in ,meteorites4 -- ,theory of ,isomorphism4 -- ,basaltic ,rocks4 -- ,trachytic ,rocks4 -- ,special ,forms of ,structure4 -- ,the columnar and globular ,forms4 -- ,trap ,dikes and ,veins4 -- ,alteration of ,rocks by volcanic ,dikes4 -- ,conversion of ,chalk into ,marble4 -- ,intrusion of ,trap between ,strata4 -- ,relation of trappean ,rocks to the ,products of active ,volcanoes4 ,chapter ,,xxix--,,on ,,the ,,ages ,,of ,,volcanic ,,rocks4 ,tests of relative ,age of ,volcanic ,rocks4 -- ,why ancient and modern ,rocks cannot be identical4 -- ,tests by ,superposition and intrusion4 -- ,test by ,alteration of ,rocks in ,contact4 -- ,test by ,organic ,remains4 -- ,test of ,age by ,mineral ,character4 -- ,test by ,included ,fragments4 -- ,recent and ,post-pliocene volcanic ,rocks4 -- ,vesuvius1 ,auvergne1 ,puy de ,come1 and ,puy de ,pariou4 -- ,newer ,pliocene volcanic ,rocks4 -- ,cyclopean ,isles1 ,etna1 ,dikes of ,palagonia1 ,madeira4 -- ,older ,pliocene volcanic ,rocks4 -- ,italy4 -- ,pliocene ,volcanoes of the ,eifel4 -- ,trass4 ,chapter ,,xxx--,,age ,,of ,,volcanic ,,rocks--,,continued4 ,volcanic ,rocks of the ,upper ,miocene ,period4 -- ,madeira4 -- ,grand ,canary4 -- ,azores4 -- ,lower ,miocene ,volcanic ,rocks4 -- ,isle of ,mull4 -- ,staffa and ,antrim4 -- ,the ,eifel4 -- ,upper and ,lower ,miocene ,volcanic ,rocks of ,auvergne4 -- ,hill of ,gergovia4 -- ,eocene ,volcanic ,rocks of ,monte ,bolca4 -- ,trap of ,cretaceous ,period4 -- ,oolitic ,period4 -- ,triassic ,period4 -- ,permian ,period4 -- ,carboniferous ,period4 -- ,erect ,trees buried in ,volcanic ,ash in the ,island of ,arran4 -- ,old ,red ,sandstone ,period4 -- ,silurian ,period4 -- ,cambrian ,period4 -- ,laurentian ,volcanic ,rocks4 ,chapter ,,xxxi--,,plutonic ,,rocks4 ,general ,aspect of ,plutonic ,rocks4 -- ,granite and its ,varieties4 -- ,decomposing into ,spherical ,masses4 -- ,rude columnar ,structure4 -- ,graphic ,granite4 -- ,mutual ,penetration of ,crystals of ,quartz and ,feldspar4 -- ,glass ,cavities in ,quartz of ,granite4 -- ,porphyritic1 talcose1 and syenitic ,granite4 -- ,schorlrock and ,eurite4 -- ,syenite4 -- ,connection of the ,granites and ,syenites with the ,volcanic ,rocks4 -- ,analogy in ,composition of ,trachyte and ,granite4 -- ,granite ,veins in ,glen ,tilt1 ,cape of ,good ,hope1 and ,cornwall4 -- ,metalliferous ,veins in ,strata near their ,junction with ,granite4 -- ,quartz ,veins4 -- ,exposure of ,plutonic ,rocks at the surface due to ,denudation4 ,chapter ,,xxxii--,,on ,,the ,,different ,,ages ,,of ,,the ,,plutonic ,,rocks4 ,difficulty in ascertaining the precise ,age of a ,plutonic ,rock4 -- ,test of ,age by ,relative ,position4 -- ,test by ,intrusion and ,alteration4 -- ,test by ,mineral ,composition4 -- ,test by included ,fragments4 -- ,recent and ,pliocene ,plutonic ,rocks1 why invisible4 -- ,miocene ,syenite of the ,isle of ,skye4 -- ,eocene ,plutonic ,rocks in the ,andes4 -- ,granite altering ,cretaceous ,rocks4 -- ,granite altering ,lias in the ,alps and in ,skye4 -- ,granite of ,dartmoor altering ,carboniferous ,strata4 -- ,granite of the ,old ,red ,sandstone ,period4 -- ,syenite altering ,silurian ,strata in ,norway4 -- ,blending of the same with ,gneiss4 -- ,most ancient ,plutonic ,rocks4 -- ,granite protruded in a solid ,form4 ,chapter ,,xxxiii--,,metamorphic ,,rocks4 ,general ,character of ,metamorphic ,rocks4 -- ,gneiss4 -- ,hornblende-schist4 -- ,serpentine4 -- ,mica-schist4 -- ,clay-slate4 -- ,quartzite4 -- ,chlorite-schist4 -- ,metamorphic ,limestone4 -- ,origin of the metamorphic ,strata4 -- ,their ,stratification4 -- ,fossiliferous ,strata near intrusive ,masses of ,granite converted into ,rocks identical with different ,members of the metamorphic ,series4 -- ,arguments hence derived as to the ,nature of ,plutonic ,action4 -- ,hydrothermal ,action1 or the ,influence of ,steam and ,gases in producing ,metamorphism4 -- ,objections to the metamorphic ,theory considered4 ,chapter ,,xxxiv--,,metamorphic ,,rocks--continued4 ,definition of slaty ,cleavage and ,joints4 -- ,supposed ,causes of these ,structures4 -- ,crystalline ,theory of ,cleavage4 -- ,mechanical ,theory of ,cleavage4 -- ,condensation and ,elongation of slate ,rocks by lateral ,pressure4 -- ,lamination of some volcanic ,rocks due to ,motion4 -- ,whether the ,foliation of the crystalline ,schists be usually parallel with the original ,planes of ,stratification4 -- ,examples in ,norway and ,scotland4 -- ,causes of ,irregularity in the ,planes of ,foliation4 ,chapter ,,xxxv--,,on ,,the ,,different ,,ages ,,of ,,the ,,metamorphic ,,rocks4 ,difficulty of ascertaining the ,age of metamorphic ,strata4 -- ,metamorphic ,strata of ,eocene date in the ,alps of ,switzerland and ,savoy4 -- ,limestone and ,shale of ,carrara4 -- ,metamorphic ,strata of older date than the ,silurian and ,cambrian ,rocks4 -- ,order of ,succession in metamorphic ,rocks4 -- ,uniformity of mineral ,character4 -- ,supposed ,azoic ,period4 -- ,connection between the ,absence of ,organic ,remains and the ,scarcity of calcareous ,matter in metamorphic ,rocks4 ,chapter ,,xxxvi--,,mineral ,,veins4 ,different ,kinds of mineral ,veins4 -- ,ordinary metalliferous ,veins or ,lodes4 -- ,their frequent ,coincidence with ,faults4 -- ,proofs that they originated in ,fissures in solid ,rock4 -- ,veins shifting other ,veins4 -- ,polishing of their ,walls or 8,slicken sides04 -- ,shells and ,pebbles in ,lodes4 -- ,evidence of the successive ,enlargement and ,reopening of veins4 -- ,examples in ,cornwall and in ,auvergne4 -- ,dimensions of ,veins4 -- ,why some alternately swell out and contract4 -- ,filling of ,lodes by ,sublimation from below4 -- ,supposed relative ,age of the precious ,metals4 -- ,copper and lead ,veins in ,ireland older than ,cornish ,tin4 -- ,lead ,vein in ,lias1 ,glamorganshire4 -- ,gold in ,russia1 ,california1 and ,australia4 -- ,connection of hot ,springs and mineral ,veins4 ,,index ,,preface4 ,,the ,,last or sixth ,,edition of my 8,elements of ,geology0 was already out of print before the end of #ahfh1 in which year ,i brought out the tenth edition of my 8,principles of ,geology40 ,in writing the last-mentioned work ,i had been called upon to pass in review almost all the leading points of speculation and controversy to which the rapid advance of the science had given rise1 and when ,i proposed to bring out a new edition of the 8,elements0 ,i was strongly urged by my friends not to repeat these theoretical discussions1 but to confine myself in the new treatise to those parts of the 8,elements0 which were most indispensable to a beginner4 ,this was to revert1 to a certain extent1 to the original plan of the first edition2 but ,i found1 after omitting a great number of subjects1 that the necessity of bringing up to the day those which remained1 and adverting1 however briefly1 to new discoveries1 made it most difficult to confine the proposed abridgment within moderate limits4 ,some chapters had to be entirely recast1 some additional illustrations to be introduced1 and figures of some organic remains to be replaced by new ones from specimens more perfect than those which had been at my command on former occasions4 ,by these changes the work assumed a form so different from the sixth edition of the 8,elements10 that ,i resolved to give it a new title and call it the 8,student's ,elements of ,geology40 ,in executing this task ,i have found it very difficult to meet the requirements of those who are entirely ignorant of the science4 ,it is only the adept who has already overcome the first steps as an observer1 and is familiar with many of the technical terms1 who can profit by a brief and concise manual4 ,beginners wish for a short and cheap book in which they may find a full explanation of the leading facts and principles of ,geology4 ,their wants1 ,i fear1 somewhat resemble those of the old woman in ,new ,england1 who asked a bookseller to supply her with 8the cheapest ,bible in the largest possible print40 ,but notwithstanding the difficulty of reconciling brevity with the copiousness of illustration demanded by those who have not yet mastered the rudiments of the science1 ,i have endeavoured to abridge the work in the manner above hinted at1 so as to place it within the reach of many to whom it was before inaccessible4 ,,charles ,,lyell4 #gc ,,harley ,,street1 ,,london1 ,december1 #ahgj4 ,,chapter ,i4 ,,on ,,the ,,different ,,classes ,,of ,,rocks4 ,geology defined4 -- ,successive ,formation of the ,earth's ,crust4 -- ,classification of ,rocks according to their ,origin and ,age4 -- ,aqueous ,rocks4 -- ,their ,stratification and imbedded ,fossils4 -- ,volcanic ,rocks1 with and without ,cones and ,craters4 -- ,plutonic ,rocks1 and their ,relation to the ,volcanic4 -- ,metamorphic ,rocks1 and their probable ,origin4 -- ,the term ,primitive1 why erroneously applied to the ,crystalline ,formations4 -- ,leading ,division of the ,work4 ,of what materials is the earth composed1 and in what manner are these materials arranged8 ,these are the first inquiries with which ,geology is occupied1 a science which derives its name from the ,greek ge1 the earth1 and logos1 a discourse4 ,previously to experience we might have imagined that investigations of this kind would relate exclusively to the mineral kingdom1 and to the various rocks1 soils1 and metals1 which occur upon the surface of the earth1 or at various depths beneath it4 ,but1 in pursuing such researches1 we soon find ourselves led on to consider the successive changes which have taken place in the former state of the earth's surface and interior1 and the causes which have given rise to these changes2 and1 what is still more singular and unexpected1 we soon become engaged in researches into the history of the animate creation1 or of the various tribes of animals and plants which have1 at different periods of the past1 inhabited the globe4 ,all are aware that the solid parts of the earth consist of distinct substances1 such as clay1 chalk1 sand1 limestone1 coal1 slate1 granite1 and the like2 but previously to observation it is commonly imagined that all these had remained from the first in the state in which we now see them--that they were created in their present form1 and in their present position4 ,the geologist soon comes to a different conclusion1 discovering proofs that the external parts of the earth were not all produced in the beginning of things in the state in which we now behold them1 nor in an instant of time4 ,on the contrary1 he can show that they have acquired their actual configuration and condition gradually1 under a great variety of circumstances1 and at successive periods1 during each of which distinct races of living beings have flourished on the land and in the waters1 the remains of these creatures still lying buried in the crust of the earth4 ,by the 8earth's crust10 is meant that small portion of the exterior of our planet which is accessible to human observation4 ,it comprises not merely all of which the structure is laid open in mountain precipices1 or in cliffs overhanging a river or the sea1 or whatever the miner may reveal in artificial excavations2 but the whole of that outer covering of the planet on which we are enabled to reason by observations made at or near the surface4 ,these reasonings may extend to a depth of several miles1 perhaps ten miles2 and even then it may be said1 that such a thickness is no more than #a_/djj part of the distance from the surface to the centre4 ,the remark is just3 but although the dimensions of such a crust are1 in truth1 insignificant when compared to the entire globe1 yet they are vast1 and of magnificent extent in relation to man1 and to the organic beings which people our globe4 ,referring to this standard of magnitude1 the geologist may admire the ample limits of his domain1 and admit1 at the same time1 that not only the exterior of the planet1 but the entire earth1 is but an atom in the midst of the countless worlds surveyed by the astronomer4 ,the materials of this crust are not thrown together confusedly2 but distinct mineral masses1 called rocks1 are found to occupy definite spaces1 and to exhibit a certain order of arrangement4 ,the term rock is applied indifferently by geologists to all these substances1 whether they be soft or stony1 for clay and sand are included in the term1 and some have even brought peat under this denomination4 ,our old writers endeavoured to avoid offering such violence to our language1 by speaking of the component materials of the earth as consisting of rocks and soils4 ,but there is often so insensible a passage from a soft and incoherent state to that of stone1 that geologists of all countries have found it indispensable to have one technical term to include both1 and in this sense we find roche applied in ,french1 rocca in ,italian1 and felsart in ,german4 ,the beginner1 however1 must constantly bear in mind that the term rock by no means implies that a mineral mass is in an indurated or stony condition4 ,the most natural and convenient mode of classifying the various rocks which compose the earth's crust1 is to refer1 in the first place1 to their origin1 and in the second to their relative age4 ,i shall therefore begin by endeavouring briefly to explain to the student how all rocks may be divided into four great classes by reference to their different origin1 or1 in other words1 by reference to the different circumstances and causes by which they have been produced4 ,the first two divisions1 which will at once be understood as natural1 are the aqueous and volcanic1 or the products of watery and those of igneous action at or near the surface4 ,aqueous ,rocks4--,the aqueous rocks1 sometimes called the sedimentary1 or fossiliferous1 cover a larger part of the earth's surface than any others4 ,they consist chiefly of mechanical deposits 7pebbles1 sand1 and mud71 but are partly of chemical and some of them of organic origin1 especially the limestones4 ,these rocks are stratified1 or divided into distinct layers1 or strata4 ,the term stratum means simply a bed1 or any thing spread out or strewed over a given surface2 and we infer that these strata have been generally spread out by the action of water1 from what we daily see taking place near the mouths of rivers1 or on the land during temporary inundations4 ,for1 whenever a running stream charged with mud or sand1 has its velocity checked1 as when it enters a lake or sea1 or overflows a plain1 the sediment1 previously held in suspension by the motion of the water1 sinks1 by its own gravity to the bottom4 ,in this manner layers of mud and sand are thrown down one upon another4 ,if we drain a lake which has been fed by a small stream1 we frequently find at the bottom a series of deposits1 disposed with considerable regularity1 one above the other2 the uppermost1 perhaps1 may be a stratum of peat1 next below a more dense and solid variety of the same material2 still lower a bed of shell-marl1 alternating with peat or sand1 and then other beds of marl1 divided by layers of clay4 ,now1 if a second pit be sunk through the same continuous lacustrine formation at some distance from the first1 nearly the same series of beds is commonly met with1 yet with slight variations2 some1 for example1 of the layers of sand1 clay1 or marl1 may be wanting1 one or more of them having thinned out and given place to others1 or sometimes one of the masses first examined is observed to increase in thickness to the exclusion of other beds4 ,the term formation1 which ,i have used in the above explanation1 expresses in geology any assemblage of rocks which have some character in common1 whether of origin1 age1 or composition4 ,thus we speak of stratified and unstratified1 fresh-water and marine1 aqueous and volcanic1 ancient and modern1 metalliferous and non-metalliferous formations4 ,in the estuaries of large rivers1 such as the ,ganges and the ,mississippi1 we may observe1 at low water1 phenomena analogous to those of the drained lakes above mentioned1 but on a grander scale1 and extending over areas several hundred miles in length and breadth4 ,when the periodical inundations subside1 the river hollows out a channel to the depth of many yards through horizontal beds of clay and sand1 the ends of which are seen exposed in perpendicular cliffs4 ,these beds vary in their mineral composition1 or colour1 or in the fineness or coarseness of their particles1 and some of them are occasionally characterised by containing drift-wood4 ,at the junction of the river and the sea1 especially in lagoons nearly separated by sand-bars from the ocean1 deposits are often formed in which brackish and salt-water shells are included4 ,in ,egypt1 where the ,nile is always adding to its delta by filling up part of the ,mediterranean with mud1 the newly deposited sediment is stratified1 the thin layer thrown down in one season differing slightly in colour from that of a previous year1 and being separable from it1 as has been observed in excavations at ,cairo and other places4#a ,when beds of sand1 clay1 and marl1 containing shells and vegetable matter1 are found arranged in a similar manner in the interior of the earth1 we ascribe to them a similar origin2 and the more we examine their characters in minute detail1 the more exact do we find the resemblance4 ,thus1 for example1 at various heights and depths in the earth1 and often far from seas1 lakes1 and rivers1 we meet with layers of rounded pebbles composed of flint1 limestone1 granite1 or other rocks1 resembling the shingles of a sea-beach or the gravel in a torrent's bed4 ,such layers of pebbles frequently alternate with others formed of sand or fine sediment1 just as we may see in the channel of a river descending from hills bordering a coast1 where the current sweeps down at one season coarse sand and gravel1 while at another1 when the waters are low and less rapid1 fine mud and sand alone are carried seaward4#b ,if a stratified arrangement1 and the rounded form of pebbles1 are alone sufficient to lead us to the conclusion that certain rocks originated under water1 this opinion is farther confirmed by the distinct and independent evidence of fossils1 so abundantly included in the earth's crust4 ,by a fossil is meant any body1 or the traces of the existence of any body1 whether animal or vegetable1 which has been buried in the earth by natural causes4 ,now the remains of animals1 especially of aquatic species1 are found almost everywhere imbedded in stratified rocks1 and sometimes1 in the case of limestone1 they are in such abundance as to constitute the entire mass of the rock itself4 ,shells and corals are the most frequent1 and with them are often associated the bones and teeth of fishes1 fragments of wood1 impressions of leaves1 and other organic substances4 ,fossil shells1 of forms such as now abound in the sea1 are met with far inland1 both near the surface1 and at great depths below it4 ,they occur at all heights above the level of the ocean1 having been observed at elevations of more than #hjjj feet in the ,pyrenees1 #aj1jjj in the ,alps1 #ac1jjj in the ,andes1 and above #ah1jjj feet in the ,himalaya4#c ,these shells belong mostly to marine testacea1 but in some places exclusively to forms characteristic of lakes and rivers4 ,hence it is concluded that some ancient strata were deposited at the bottom of the sea1 and others in lakes and estuaries4 ,we have now pointed out one great class of rocks1 which1 however they may vary in mineral composition1 colour1 grain1 or other characters1 external and internal1 may nevertheless be grouped together as having a common origin4 ,they have all been formed under water1 in the same manner as modern accumulations of sand1 mud1 shingle1 banks of shells1 reefs of coral1 and the like1 and are all characterised by stratification or fossils1 or by both4 ,volcanic ,rocks4--,the division of rocks which we may next consider are the volcanic1 or those which have been produced at or near the surface whether in ancient or modern times1 not by water1 but by the action of fire or subterranean heat4 ,these rocks are for the most part unstratified1 and are devoid of fossils4 ,they are more partially distributed than aqueous formations1 at least in respect to horizontal extension4 ,among those parts of ,europe where they exhibit characters not to be mistaken1 ,i may mention not only ,sicily and the country round ,naples1 but ,auvergne1 ,velay1 and ,vivarais1 now the departments of ,puy de ,dome1 ,haute ,loire1 and ,ardche1 towards the centre and south of ,france1 in which are several hundred conical hills having the forms of modern volcanoes1 with craters more or less perfect on many of their summits4 ,these cones are composed moreover of lava1 sand1 and ashes1 similar to those of active volcanoes4 ,streams of lava may sometimes be traced from the cones into the adjoining valleys1 where they have choked up the ancient channels of rivers with solid rock1 in the same manner as some modern flows of lava in ,iceland have been known to do1 the rivers either flowing beneath or cutting out a narrow passage on one side of the lava4 ,although none of these ,french volcanoes have been in activity within the period of history or tradition1 their forms are often very perfect4 ,some1 however1 have been compared to the mere skeletons of volcanoes1 the rains and torrents having washed their sides1 and removed all the loose sand and scori1 leaving only the harder and more solid materials4 ,by this erosion1 and by earthquakes1 their internal structure has occasionally been laid open to view1 in fissures and ravines2 and we then behold not only many successive beds and masses of porous lava1 sand1 and scori1 but also perpendicular walls1 or dikes1 as they are called1 of volcanic rock1 which have burst through the other materials4 ,such dikes are also observed in the structure of ,vesuvius1 ,etna1 and other active volcanoes4 ,they have been formed by the pouring of melted matter1 whether from above or below1 into open fissures1 and they commonly traverse deposits of volcanic tuff1 a substance produced by the showering down from the air1 or incumbent waters1 of sand and cinders1 first shot up from the interior of the earth by the explosions of volcanic gases4 ,besides the parts of ,france above alluded to1 there are other countries1 as the north of ,spain1 the south of ,sicily1 the ,tuscan territory of ,italy1 the lower ,rhenish provinces1 and ,hungary1 where spent volcanoes may be seen1 still preserving in many cases a conical form1 and having craters and often lava-streams connected with them4 ,there are also other rocks in ,england1 ,scotland1 ,ireland1 and almost every country in ,europe1 which we infer to be of igneous origin1 although they do not form hills with cones and craters4 ,thus1 for example1 we feel assured that the rock of ,staffa1 and that of the ,giant's ,causeway1 called basalt1 is volcanic1 because it agrees in its columnar structure and mineral composition with streams of lava which we know to have flowed from the craters of volcanoes4 ,we find also similar basaltic and other igneous rocks associated with beds of tuff in various parts of the ,british ,isles1 and forming dikes1 such as have been spoken of2 and some of the strata through which these dikes cut are occasionally altered at the point of contact1 as if they had been exposed to the intense heat of melted matter4 ,the absence of cones and craters1 and long narrow streams of superficial lava1 in ,england and many other countries1 is principally to be attributed to the eruptions having been submarine1 just as a considerable proportion of volcanoes in our own times burst out beneath the sea4 ,but this question must be enlarged upon more fully in the chapters on ,igneous ,rocks1 in which it will also be shown1 that as different sedimentary formations1 containing each their characteristic fossils1 have been deposited at successive periods1 so also volcanic sand and scori have been thrown out1 and lavas have flowed over the land or bed of the sea1 at many different epochs1 or have been injected into fissures2 so that the igneous as well as the aqueous rocks may be classed as a chronological series of monuments1 throwing light on a succession of events in the history of the earth4 ,plutonic ,rocks 7,granite1 etc74--,we have now pointed out the existence of two distinct orders of mineral masses1 the aqueous and the volcanic3 but if we examine a large portion of a continent1 especially if it contain within it a lofty mountain range1 we rarely fail to discover two other classes of rocks1 very distinct from either of those above alluded to1 and which we can neither assimilate to deposits such as are now accumulated in lakes or seas1 nor to those generated by ordinary volcanic action4 ,the members of both these divisions of rocks agree in being highly crystalline and destitute of organic remains4 ,the rocks of one division have been called ,plutonic1 comprehending all the granites and certain porphyries1 which are nearly allied in some of their characters to volcanic formations4 ,the members of the other class are stratified and often slaty1 and have been called by some the crystalline schists1 in which group are included gneiss1 micaceous-schist 7or mica-slate71 hornblende-schist1 statuary marble1 the finer kinds of roofing slate1 and other rocks afterwards to be described4 ,as it is admitted that nothing strictly analogous to these crystalline productions can now be seen in the progress of formation on the earth's surface1 it will naturally be asked1 on what data we can find a place for them in a system of classification founded on the origin of rocks4 ,i cannot1 in reply to this question1 pretend to give the student1 in a few words1 an intelligible account of the long chain of facts and reasonings from which geologists have been led to infer the nature of the rocks in question4 ,the result1 however1 may be briefly stated4 ,all the various kinds of granites which constitute the ,plutonic family are supposed to be of igneous or aqueo-igneous origin1 and to have been formed under great pressure1 at a considerable depth in the earth1 or sometimes1 perhaps1 under a certain weight of incumbent ocean4 ,like the lava of volcanoes1 they have been melted1 and afterwards cooled and crystallised1 but with extreme slowness1 and under conditions very different from those of bodies cooling in the open air4 ,hence they differ from the volcanic rocks1 not only by their more crystalline texture1 but also by the absence of tuffs and breccias1 which are the products of eruptions at the earth's surface1 or beneath seas of inconsiderable depth4 ,they differ also by the absence of pores or cellular cavities1 to which the expansion of the entangled gases gives rise in ordinary lava4 ,metamorphic1 or ,stratified ,crystalline ,rocks4--,the fourth and last great division of rocks are the crystalline strata and slates1 or schists1 called gneiss1 mica-schist1 clay-slate1 chlorite-schist1 marble1 and the like1 the origin of which is more doubtful than that of the other three classes4 ,they contain no pebbles1 or sand1 or scori1 or angular pieces of imbedded stone1 and no traces of organic bodies1 and they are often as crystalline as granite1 yet are divided into beds1 corresponding in form and arrangement to those of sedimentary formations1 and are therefore said to be stratified4 ,the beds sometimes consist of an alternation of substances varying in colour1 composition1 and thickness1 precisely as we see in stratified fossiliferous deposits4 ,according to the ,huttonian theory1 which ,i adopt as the most probable1 and which will be afterwards more fully explained1 the materials of these strata were originally deposited from water in the usual form of sediment1 but they were subsequently so altered by subterranean heat1 as to assume a new texture4 ,it is demonstrable1 in some cases at least1 that such a complete conversion has actually taken place1 fossiliferous strata having exchanged an earthy for a highly crystalline texture for a distance of a quarter of a mile from their contact with granite4 ,in some cases1 dark limestones1 replete with shells and corals1 have been turned into white statuary marble2 and hard clays1 containing vegetable or other remains1 into slates called mica-schist or hornblende-schist1 every vestige of the organic bodies having been obliterated4 ,although we are in a great degree ignorant of the precise nature of the influence exerted in these cases1 yet it evidently bears some analogy to that which volcanic heat and gases are known to produce2 and the action may be conveniently called ,plutonic1 because it appears to have been developed in those regions where ,plutonic rocks are generated1 and under similar circumstances of pressure and depth in the earth4 ,intensely heated water or steam permeating stratified masses under great pressure have no doubt played their part in producing the crystalline texture and other changes1 and it is clear that the transforming influence has often pervaded entire mountain masses of strata4 ,in accordance with the hypothesis above alluded to1 ,i proposed in the first edition of the ,principles of ,geology 7#ahcc7 the term 8,metamorphic0 for the altered strata1 a term derived from meta1 trans1 and morphe1 forma4 ,hence there are four great classes of rocks considered in reference to their origin--the aqueous1 the volcanic1 the ,plutonic1 and the metamorphic4 ,in the course of this work it will be shown that portions of each of these four distinct classes have originated at many successive periods4 ,they have all been produced contemporaneously1 and may even now be in the progress of formation on a large scale4 ,it is not true1 as was formerly supposed1 that all granites1 together with the crystalline or metamorphic strata1 were first formed1 and therefore entitled to be called 8primitive10 and that the aqueous and volcanic rocks were afterwards superimposed1 and should1 therefore1 rank as secondary in the order of time4 ,this idea was adopted in the infancy of the science1 when all formations1 whether stratified or unstratified1 earthy or crystalline1 with or without fossils1 were alike regarded as of aqueous origin4 ,at that period it was naturally argued that the foundation must be older than the superstructure2 but it was afterwards discovered that this opinion was by no means in every instance a legitimate deduction from facts2 for the inferior parts of the earth's crust have often been modified1 and even entirely changed1 by the influence of volcanic and other subterranean causes1 while superimposed formations have not been in the slightest degree altered4 ,in other words1 the destroying and renovating processes have given birth to new rocks below1 while those above1 whether crystalline or fossiliferous1 have remained in their ancient condition4 ,even in cities1 such as ,venice and ,amsterdam1 it cannot be laid down as universally true that the upper parts of each edifice1 whether of brick or marble1 are more modern than the foundations on which they rest1 for these often consist of wooden piles1 which may have rotted and been replaced one after the other1 without the least injury to the buildings above2 meanwhile1 these may have required scarcely any repair1 and may have been constantly inhabited4 ,so it is with the habitable surface of our globe1 in its relation to large masses of rock immediately below2 it may continue the same for ages1 while subjacent materials1 at a great depth1 are passing from a solid to a fluid state1 and then reconsolidating1 so as to acquire a new texture4 ,as all the crystalline rocks may1 in some respects1 be viewed as belonging to one great family1 whether they be stratified or unstratified1 metamorphic or ,plutonic1 it will often be convenient to speak of them by one common name4 ,it being now ascertained1 as above stated1 that they are of very different ages1 sometimes newer than the strata called secondary1 the terms primitive and primary which were formerly used for the whole must be abandoned1 as they would imply a manifest contradiction4 ,it is indispensable1 therefore1 to find a new name1 one which must not be of chronological import1 and must express1 on the one hand1 some peculiarity equally attributable to granite and gneiss 7to the ,plutonic as well as the altered rocks71 and1 on the other1 must have reference to characters in which those rocks differ1 both from the volcanic and from the unaltered sedimentary strata4 ,i proposed in the ,principles of ,geology 7first edition1 vol4 iii7 the term 8hypogene0 for this purpose1 derived from upo1 under1 and ginomai1 to be1 or to be born2 a word implying the theory that granite1 gneiss1 and the other crystalline formations are alike netherformed rocks1 or rocks which have not assumed their present form and structure at the surface4 ,they occupy the lowest place in the order of superposition4 ,even in regions such as the ,alps1 where some masses of granite and gneiss can be shown to be of comparatively modern date1 belonging1 for example1 to the period hereafter to be described as tertiary1 they are still underlying rocks4 ,they never repose on the volcanic or trappean formations1 nor on strata containing organic remains4 ,they are hypogene1 as 8being under0 all the rest4 ,from what has now been said1 the reader will understand that each of the four great classes of rocks may be studied under two distinct points of view2 first1 they may be studied simply as mineral masses deriving their origin from particular causes1 and having a certain composition1 form1 and position in the earth's crust1 or other characters both positive and negative1 such as the presence or absence of organic remains4 ,in the second place1 the rocks of each class may be viewed as a grand chronological series of monuments1 attesting a succession of events in the former history of the globe and its living inhabitants4 ,i shall accordingly proceed to treat of each family of rocks2 first1 in reference to those characters which are not chronological1 and then in particular relation to the several periods when they were formed4 #a ,see ,principles of ,geology1 by the ,author1 ,index1 8,nile10 8,rivers10 etc4 #b ,see p4 #dd1 ,fig4 #g4 #c ,col4 ,r4 ,j4 ,strachey found oolitic fossils #ah1djj feet high in the ,himalaya4 ,,chapter ,,ii4 ,,aqueous ,,rocks4--,,their ,,composition ,,and ,,forms ,,of ,,stratification4 ,mineral ,composition of ,strata4 -- ,siliceous ,rocks4 -- ,argillaceous4 -- ,calcareous4 -- ,gypsum4 -- ,forms of ,stratification4 -- ,original ,horizontality4 -- ,thinning out4 -- ,diagonal ,arrangement4 -- ,ripple-mark4 ,in pursuance of the arrangement explained in the last chapter1 we shall begin by examining the aqueous or sedimentary rocks1 which are for the most part distinctly stratified1 and contain fossils4 ,we may first study them with reference to their mineral composition1 external appearance1 position1 mode of origin1 organic contents1 and other characters which belong to them as aqueous formations1 independently of their age1 and we may afterwards consider them chronologically or with reference to the successive geological periods when they originated4 ,i have already given an outline of the data which led to the belief that the stratified and fossiliferous rocks were originally deposited under water2 but1 before entering into a more detailed investigation1 it will be desirable to say something of the ordinary materials of which such strata are composed4 ,these may be said to belong principally to three divisions1 the siliceous1 the argillaceous1 and the calcareous1 which are formed respectively of flint1 clay1 and carbonate of lime4 ,of these1 the siliceous are chiefly made up of sand or flinty grains2 the argillaceous1 or clayey1 of a mixture of siliceous matter with a certain proportion1 about a fourth in weight1 of aluminous earth2 and1 lastly1 the calcareous rocks1 or limestones1 of carbonic acid and lime4 ,siliceous and ,arenaceous ,rocks4--,to speak first of the sandy division3 beds of loose sand are frequently met with1 of which the grains consist entirely of silex1 which term comprehends all purely siliceous minerals1 as quartz and common flint4 ,quartz is silex in its purest form4 ,flint usually contains some admixture of alumina and oxide of iron4 ,the siliceous grains in sand are usually rounded1 as if by the action of running water4 ,sandstone is an aggregate of such grains1 which often cohere together without any visible cement1 but more commonly are bound together by a slight quantity of siliceous or calcareous matter1 or by oxide of iron or clay4 ,pure siliceous rocks may be known by not effervescing when a drop of nitric1 sulphuric or other acid is applied to them1 or by the grains not being readily scratched or broken by ordinary pressure4 ,in nature there is every intermediate gradation1 from perfectly loose sand to the hardest sandstone4 ,in micaceous sandstones mica is very abundant2 and the thin silvery plates into which that mineral divides are often arranged in layers parallel to the planes of stratification1 giving a slaty or laminated texture to the rock4 ,when sandstone is coarse-grained1 it is usually called grit4 ,if the grains are rounded1 and large enough to be called pebbles1 it becomes a conglomerate or pudding-stone1 which may consist of pieces of one or of many different kinds of rock4 ,a conglomerate1 therefore1 is simply gravel bound together by cement4 ,argillaceous ,rocks4--,clay1 strictly speaking1 is a mixture of silex or flint with a large proportion1 usually about one fourth1 of alumina1 or argil2 but in common language1 any earth which possesses sufficient ductility1 when kneaded up with water1 to be fashioned like paste by the hand1 or by the potter's lathe1 is called a clay2 and such clays vary greatly in their composition1 and are1 in general1 nothing more than mud derived from the decomposition or wearing down of rocks4 ,the purest clay found in nature is porcelain clay1 or kaolin1 which results from the decomposition of a rock composed of feldspar and quartz1 and it is almost always mixed with quartz4 ,the kaolin of ,china consists of #gaae parts of silex1 #aehf of alumine1 #aib of lime1 and #fgc of water2#a but other porcelain clays differ materially1 that of ,cornwall being composed1 according to ,boase1 of nearly equal parts of silica and alumine1 with #a per cent of magnesia4#b ,shale has also the property1 like clay1 of becoming plastic in water3 it is a more solid form of clay1 or argillaceous matter1 condensed by pressure4 ,it always divides into lamin more or less regular4 ,one general character of all argillaceous rocks is to give out a peculiar1 earthy odour when breathed upon1 which is a test of the presence of alumine1 although it does not belong to pure alumine1 but1 apparently1 to the combination of that substance with oxide of iron4#c ,calcareous ,rocks4--,this division comprehends those rocks which1 like chalk1 are composed chiefly of lime and carbonic acid4 ,shells and corals are also formed of the same elements1 with the addition of animal matter4 ,to obtain pure lime it is necessary to calcine these calcareous substances1 that is to say1 to expose them to heat of sufficient intensity to drive off the carbonic acid1 and other volatile matter4 ,white chalk is sometimes pure carbonate of lime2 and this rock1 although usually in a soft and earthy state1 is occasionally sufficiently solid to be used for building1 and even passes into a compact stone1 or a stone of which the separate parts are so minute as not to be distinguishable from each other by the naked eye4 ,many limestones are made up entirely of minute fragments of shells and coral1 or of calcareous sand cemented together4 ,these last might be called 8calcareous sandstones20 but that term is more properly applied to a rock in which the grains are partly calcareous and partly siliceous1 or to quartzose sandstones1 having a cement of carbonate of lime4 ,the variety of limestone called oolite is composed of numerous small egg-like grains1 resembling the roe of a fish1 each of which has usually a small fragment of sand as a nucleus1 around which concentric layers of calcareous matter have accumulated4 ,any limestone which is sufficiently hard to take a fine polish is called marble4 ,many of these are fossiliferous2 but statuary marble1 which is also called saccharoid limestone1 as having a texture resembling that of loaf-sugar1 is devoid of fossils1 and is in many cases a member of the metamorphic series4 ,siliceous limestone is an intimate mixture of carbonate of lime and flint1 and is harder in proportion as the flinty matter predominates4 ,the presence of carbonate of lime in a rock may be ascertained by applying to the surface a small drop of diluted sulphuric1 nitric1 or muriatic acid1 or strong vinegar2 for the lime1 having a greater chemical affinity for any one of these acids than for the carbonic1 unites immediately with them to form new compounds1 thereby becoming a sulphate1 nitrate or muriate of lime4 ,the carbonic acid1 when thus liberated from its union with the lime1 escapes in a gaseous form1 and froths up or effervesces as it makes its way in small bubbles through the drop of liquid4 ,this effervescence is brisk or feeble in proportion as the limestone is pure or impure1 or1 in other words1 according to the quantity of foreign matter mixed with the carbonate of lime4 ,without the aid of this test1 the most experienced eye cannot always detect the presence of carbonate of lime in rocks4 ,the above-mentioned three classes of rocks1 the siliceous1 argillaceous1 and calcareous1 pass continually into each other1 and rarely occur in a perfectly separate and pure form4 ,thus it is an exception to the general rule to meet with a limestone as pure as ordinary white chalk1 or with clay as aluminous as that used in ,cornwall for porcelain1 or with sand so entirely composed of siliceous grains as the white sand of ,alum ,bay1 in the ,isle of ,wight1 employed in the manufacture of glass1 or sandstone so pure as the grit of ,fontainebleau1 used for pavement in ,france4 ,more commonly we find sand and clay1 or clay and marl1 intermixed in the same mass4 ,when the sand and clay are each in considerable quantity1 the mixture is called loam4 ,if there is much calcareous matter in clay it is called marl2 but this term has unfortunately been used so vaguely1 as often to be very ambiguous4 ,it has been applied to substances in which there is no lime2 as1 to that red loam usually called red marl in certain parts of ,england4 ,agriculturists were in the habit of calling any soil a marl which1 like true marl1 fell to pieces readily on exposure to the air4 ,hence arose the confusion of using this name for soils which1 consisting of loam1 were easily worked by the plough1 though devoid of lime4 ,marl slate bears the same relation to marl which shale bears to clay1 being a calcareous shale4 ,it is very abundant in some countries1 as in the ,swiss ,alps4 ,argillaceous or marly limestone is also of common occurrence4 ,there are few other kinds of rock which enter so largely into the composition of sedimentary strata as to make it necessary to dwell here on their characters4 ,i may1 however1 mention two others--magnesian limestone or dolomite1 and gypsum4 ,magnesian limestone is composed of carbonate of lime and carbonate of magnesia2 the proportion of the latter amounting in some cases to nearly one half4 ,it effervesces much more slowly and feebly with acids than common limestone4 ,in ,england this rock is generally of a yellowish colour2 but it varies greatly in mineralogical character1 passing from an earthy state to a white compact stone of great hardness4 ,dolomite1 so common in many parts of ,germany and ,france1 is also a variety of magnesian limestone1 usually of a granular texture4 ,gypsum is a rock composed of sulphuric acid1 lime1 and water4 ,it is usually a soft whitish-yellow rock1 with a texture resembling that of loaf-sugar1 but sometimes it is entirely composed of lenticular crystals4 ,it is insoluble in acids1 and does not effervesce like chalk and dolomite1 because it does not contain carbonic acid gas1 or fixed air1 the lime being already combined with sulphuric acid1 for which it has a stronger affinity than for any other4 ,anhydrous gypsum is a rare variety1 into which water does not enter as a component part4 ,gypseous marl is a mixture of gypsum and marl4 ,alabaster is a granular and compact variety of gypsum found in masses large enough to be used in sculpture and architecture4 ,it is sometimes a pure snow-white substance1 as that of ,volterra in ,tuscany1 well known as being carved for works of art in ,florence and ,leghorn4 ,it is a softer stone than marble1 and more easily wrought4 ,forms of ,stratification4--,a series of strata sometimes consists of one of the above rocks1 sometimes of two or more in alternating beds4 ,thus1 in the coal districts of ,england1 for example1 we often pass through several beds of sandstone1 some of finer1 others of coarser grain1 some white1 others of a dark colour1 and below these1 layers of shale and sandstone or beds of shale1 divisible into leaf-like lamin1 and containing beautiful impressions of plants4 ,then again we meet with beds of pure and impure coal1 alternating with shales and sandstones1 and underneath the whole1 perhaps1 are calcareous strata1 or beds of limestone1 filled with corals and marine shells1 each bed distinguishable from another by certain fossils1 or by the abundance of particular species of shells or zoophytes4 ,this alternation of different kinds of rock produces the most distinct stratification2 and we often find beds of limestone and marl1 conglomerate and sandstone1 sand and clay1 recurring again and again1 in nearly regular order1 throughout a series of many hundred strata4 ,the causes which may produce these phenomena are various1 and have been fully discussed in my treatise on the modern changes of the earth's surface4#d ,it is there seen that rivers flowing into lakes and seas are charged with sediment1 varying in quantity1 composition1 colour1 and grain according to the seasons2 the waters are sometimes flooded and rapid1 at other periods low and feeble2 different tributaries1 also1 draining peculiar countries and soils1 and therefore charged with peculiar sediment1 are swollen at distinct periods4 ,it was also shown that the waves of the sea and currents undermine the cliffs during wintry storms1 and sweep away the materials into the deep1 after which a season of tranquillity succeeds1 when nothing but the finest mud is spread by the movements of the ocean over the same submarine area4 ,it is not the object of the present work to give a description of these operations1 repeated as they are1 year after year1 and century after century2 but ,i may suggest an explanation of the manner in which some micaceous sandstones have originated1 namely1 those in which we see innumerable thin layers of mica dividing layers of fine quartzose sand4 ,i observed the same arrangement of materials in recent mud deposited in the estuary of ,laroche ,st4 ,bernard in ,brittany1 at the mouth of the ,loire4 ,the surrounding rocks are of gneiss1 which1 by its waste1 supplies the mud3 when this dries at low water1 it is found to consist of brown laminated clay1 divided by thin seams of mica4 ,the separation of the mica in this case1 or in that of micaceous sandstones1 may be thus understood4 ,if we take a handful of quartzose sand1 mixed with mica1 and throw it into a clear running stream1 we see the materials immediately sorted by the water1 the grains of quartz falling almost directly to the bottom1 while the plates of mica take a much longer time to reach the bottom1 and are carried farther down the stream4 ,at the first instant the water is turbid1 but immediately after the flat surfaces of the plates of mica are seen all alone1 reflecting a silvery light1 as they descend slowly1 to form a distinct micaceous lamina4 ,the mica is the heavier mineral of the two2 but it remains a longer time suspended in the fluid1 owing to its greater extent of surface4 ,it is easy1 therefore1 to perceive that where such mud is acted upon by a river or tidal current1 the thin plates of mica will be carried farther1 and not deposited in the same places as the grains of quartz2 and since the force and velocity of the stream varies from time to time1 layers of mica or of sand will be thrown down successively on the same area4 ,original ,horizontality4--,it is said generally that the upper and under surfaces of strata1 or the 8planes of stratification10 are parallel4 ,although this is not strictly true1 they make an approach to parallelism1 for the same reason that sediment is usually deposited at first in nearly horizontal layers4 ,such an arrangement can by no means be attributed to an original evenness or horizontality in the bed of the sea3 for it is ascertained that in those places where no matter has been recently deposited1 the bottom of the ocean is often as uneven as that of the dry land1 having in like manner its hills1 valleys1 and ravines4 ,yet if the sea should go down1 or be removed from near the mouth of a large river where a delta has been forming1 we should see extensive plains of mud and sand laid dry1 which1 to the eye1 would appear perfectly level1 although1 in reality1 they would slope gently from the land towards the sea4 ,this tendency in newly-formed strata to assume a horizontal position arises principally from the motion of the water1 which forces along particles of sand or mud at the bottom1 and causes them to settle in hollows or depressions where they are less exposed to the force of a current than when they are resting on elevated points4 ,the velocity of the current and the motion of the superficial waves diminish from the surface downward1 and are least in those depressions where the water is deepest4 ,a good illustration of the principle here alluded to may be sometimes seen in the neighbourhood of a volcano1 when a section1 whether natural or artificial1 has laid open to view a succession of various-coloured layers of sand and ashes1 which have fallen in showers upon uneven ground4 ,thus let ,a ,b 7,fig4 #a7 be two ridges1 with an intervening valley4 ,these original inequalities of the surface have been gradually effaced by beds of sand and ashes c1 d1 e1 the surface at e being quite level4 ,it will be seen that1 although the materials of the first layers have accommodated themselves in a great degree to the shape of the ground ,a ,b1 yet each bed is thickest at the bottom4 ,at first a great many particles would be carried by their own gravity down the steep sides of ,a and ,b1 and others would afterwards be blown by the wind as they fell off the ridges1 and would settle in the hollow1 which would thus become more and more effaced as the strata accumulated from c to e4 ,now1 water in motion can exert this levelling power on similar materials more easily than air1 for almost all stones lose in water more than a third of the weight which they have in air1 the specific gravity of rocks being in general as #b when compared to that of water1 which is estimated at #a4 ,but the buoyancy of sand or mud would be still greater in the sea1 as the density of salt-water exceeds that of fresh4 ,fig4 #b4 ,section of strata of sandtone1 grit1 and congolmerate4 ,yet1 however uniform and horizontal may be the surface of new deposits in general1 there are still many disturbing causes1 such as eddies in the water1 and currents moving first in one and then in another direction1 which frequently cause irregularities4 ,we may sometimes follow a bed of limestone1 shale1 or sandstone1 for a distance of many hundred yards continuously2 but we generally find at length that each individual stratum thins out1 and allows the beds which were previously above and below it to meet4 ,if the materials are coarse1 as in grits and conglomerates1 the same beds can rarely be traced many yards without varying in size1 and often coming to an end abruptly4 7,see ,fig4 #b47 ,fig4 #c3 ,section of sand at ,sandy ,hill1 near ,biggleswade1 ,bedfordshire4 ,diagonal or ,cross ,stratification4--,there is also another phenomenon of frequent occurrence4 ,we find a series of larger strata1 each of which is composed of a number of minor layers placed obliquely to the general planes of stratification4 ,to this diagonal arrangement the name of 8false or cross bedding0 has been given4 ,thus in the section 7,fig4 #c7 we see seven or eight large beds of loose sand1 yellow and brown1 and the lines a1 b1 c mark some of the principal planes of stratification1 which are nearly horizontal4 ,but the greater part of the subordinate lamin do not conform to these planes1 but have often a steep slope1 the inclination being sometimes towards opposite points of the compass4 ,when the sand is loose and incoherent1 as in the case here represented1 the deviation from parallelism of the slanting lamin cannot possibly be accounted for by any rearrangement of the particles acquired during the consolidation of the rock4 ,in what manner1 then1 can such irregularities be due to original deposition8 ,we must suppose that at the bottom of the sea1 as well as in the beds of rivers1 the motions of waves1 currents1 and eddies often cause mud1 sand1 and gravel to be thrown down in heaps on particular spots1 instead of being spread out uniformly over a wide area4 ,sometimes1 when banks are thus formed1 currents may cut passages through them1 just as a river forms its bed4 ,fig4 #d;,fig4 #e ,suppose the bank ,a 7,fig4 #d7 to be thus formed with a steep sloping side1 and1 the water being in a tranquil state1 the layer of sediment ,no4 #a is thrown down upon it1 conforming nearly to its surface4 ,afterwards the other layers1 #b1 #c1 #d1 may be deposited in succession1 so that the bank ,b ,c ,d is formed4 ,if the current then increases in velocity1 it may cut away the upper portion of this mass down to the dotted line e1 and deposit the materials thus removed farther on1 so as to form the layers #e1 #f1 #g1 #h4 ,we have now the bank ,b1 ,c1 ,d1 ,e 7,fig4 #e71 of which the surface is almost level1 and on which the nearly horizontal layers1 #i1 #aj1 #aa1 may then accumulate4 ,it was shown in ,fig4 #c that the diagonal layers of successive strata may sometimes have an opposite slope4 ,this is well seen in some cliffs of loose sand on the ,suffolk coast4 ,a portion of one of these is represented in ,fig4 #f1 where the layers1 of which there are about six in the thickness of an inch1 are composed of quartzose grains4 ,this arrangement may have been due to the altered direction of the tides and currents in the same place4 ,fig4 #f3 ,cliff between ,mismer and ,dunwich4 ,fig4 #g3 ,section from ,monte ,calvo to the sea by the valley of the ,magnan1 near ,nice4 ,the description above given of the slanting position of the minor layers constituting a single stratum is in certain cases applicable on a much grander scale to masses several hundred feet thick1 and many miles in extent4 ,a fine example may be seen at the base of the ,maritime ,alps near ,nice4 ,the mountains here terminate abruptly in the sea1 so that a depth of one hundred fathoms is often found within a stone's throw of the beach1 and sometimes a depth of #cjjj feet within half a mile4 ,but at certain points1 strata of sand1 marl1 or conglomerate intervene between the shore and the mountains1 as in the section 7,fig4 #g71 where a vast succession of slanting beds of gravel and sand may be traced from the sea to ,monte ,calvo1 a distance of no less than nine miles in a straight line4 ,the dip of these beds is remarkably uniform1 being always southward or towards the ,mediterranean1 at an angle of about #be4 ,they are exposed to view in nearly vertical precipices1 varying from #bjj to #fjj feet in height1 which bound the valley through which the river ,magnan flows4 ,although1 in a general view1 the strata appear to be parallel and uniform1 they are nevertheless found1 when examined closely1 to be wedge-shaped1 and to thin out when followed for a few hundred feet or yards1 so that we may suppose them to have been thrown down originally upon the side of a steep bank where a river or ,alpine torrent discharged itself into a deep and tranquil sea1 and formed a delta1 which advanced gradually from the base of ,monte ,calvo to a distance of nine miles from the original shore4 ,if subsequently this part of the ,alps and bed of the sea were raised #gjj feet1 the delta may have emerged1 a deep channel may then have been cut through it by the river1 and the coast may at the same time have acquired its present configuration4 ,it is well known that the torrents and streams which now descend from the ,alpine declivities to the shore1 bring down annually1 when the snow melts1 vast quantities of shingle and sand1 and then1 as they subside1 fine mud1 while in summer they are nearly or entirely dry2 so that it may be safely assumed that deposits like those of the valley of the ,magnan1 consisting of coarse gravel alternating with fine sediment1 are still in progress at many points1 as1 for instance1 at the mouth of the ,var4 ,they must advance upon the ,mediterranean in the form of great shoals terminating in a steep talus2 such being the original mode of accumulation of all coarse materials conveyed into deep water1 especially where they are composed in great part of pebbles1 which cannot be transported to indefinite distances by currents of moderate velocity4 ,by inattention to facts and inferences of this kind1 a very exaggerated estimate has sometimes been made of the supposed depth of the ancient ocean4 ,there can be no doubt1 for example1 that the strata a1 ,fig4 #g1 or those nearest to ,monte ,calvo1 are older than those indicated by b1 and these again were formed before c2 but the vertical depth of gravel and sand in any one place cannot be proved to amount even to #ajjj feet1 although it may perhaps be much greater1 yet probably never exceeding at any point #cjjj or #djjj feet4 ,but were we to assume that all the strata were once horizontal1 and that their present dip or inclination was due to subsequent movements1 we should then be forced to conclude that a sea several miles deep had been filled up with alternate layers of mud and pebbles thrown down one upon another4 ,in the locality now under consideration1 situated a few miles to the west of ,nice1 there are many geological data1 the details of which cannot be given in this place1 all leading to the opinion that1 when the deposit of the ,magnan was formed1 the shape and outline of the ,alpine declivities and the shore greatly resembled what we now behold at many points in the neighbourhood4 ,that the beds a1 b1 c1 d are of comparatively modern date is proved by this fact1 that in seams of loamy marl intervening between the pebbly beds are fossil shells1 half of which belong to species now living in the ,mediterranean4 ,fig4 #h3 ,slab of ripple-marked 7,new ,red7 sandstone from ,cheshire4 ,ripple-mark4--,the ripple-mark1 so common on the surface of sandstones of all ages 7see ,fig4 #h71 and which is so often seen on the sea-shore at low tide1 seems to originate in the drifting of materials along the bottom of the water1 in a manner very similar to that which may explain the inclined layers above described4 ,this ripple is not entirely confined to the beach between high and low water mark1 but is also produced on sands which are constantly covered by water4 ,similar undulating ridges and furrows may also be sometimes seen on the surface of drift snow and blown sand4 ,the ripple-mark is usually an indication of a sea-beach1 or of water from six to ten feet deep1 for the agitation caused by waves even during storms extends to a very slight depth4 ,to this rule1 however1 there are some exceptions1 and recent ripple-marks have been observed at the depth of #fj or #gj feet4 ,it has also been ascertained that currents or large bodies of water in motion may disturb mud and sand at the depth of #cjj or even #dej feet4#e ,beach ripple1 however1 may usually be distinguished from current ripple by frequent changes in its direction4 ,in a slab of sandstone1 not more than an inch thick1 the furrows or ridges of an ancient ripple may often be seen in several successive lamin to run towards different points of the compass4 #a ,w4 ,phillips1 ,mineralogy1 p4#cc4 #b ,phil4 ,mag41 vol4 x1 #ahcg4 #c ,see ,w4 ,phillips's ,mineralogy1 8,alumine40 #d ,consult ,index to ,principles of ,geology1 8,stratification10 8,currents10 8,deltas10 8,water10 etc4 #e ,darwin1 ,volcanic ,islands1 p4 #acd4 ,,chapter ,,iii4 ,,arrangement ,,of ,,fossils ,,in ,,strata4--,,fresh-,,water ,,and ,,marine ,,fossils4 ,successive ,deposition indicated by ,fossils4 -- ,limestones formed of ,corals and ,shells4 -- ,proofs of gradual ,increase of ,strata derived from ,fossils4 -- ,serpula attached to ,spatangus4 -- ,wood bored by ,teredina4 -- ,tripoli formed of ,infusoria4 -- ,chalk derived principally from ,organic ,bodies4 -- ,distinction of ,fresh-water from ,marine ,formations4 -- ,genera of ,fresh-water and ,land ,shells4 -- ,rules for recognising ,marine ,testacea4 -- ,gyrogonite and ,chara4 -- ,fresh-water ,fishes4 -- ,alternation of ,marine and ,fresh-water ,deposits4 -- ,lym-,fiord4 ,having in the last chapter considered the forms of stratification so far as they are determined by the arrangement of inorganic matter1 we may now turn our attention to the manner in which organic remains are distributed through stratified deposits4 ,we should often be unable to detect any signs of stratification or of successive deposition1 if particular kinds of fossils did not occur here and there at certain depths in the mass4 ,at one level1 for example1 univalve shells of some one or more species predominate2 at another1 bivalve shells2 and at a third1 corals2 while in some formations we find layers of vegetable matter1 commonly derived from land plants1 separating strata4 ,it may appear inconceivable to a beginner how mountains1 several thousand feet thick1 can have become full of fossils from top to bottom2 but the difficulty is removed1 when he reflects on the origin of stratification1 as explained in the last chapter1 and allows sufficient time for the accumulation of sediment4 ,he must never lose sight of the fact that1 during the process of deposition1 each separate layer was once the uppermost1 and immediately in contact with the water in which aquatic animals lived4 ,each stratum1 in fact1 however far it may now lie beneath the surface1 was once in the state of shingle1 or loose sand or soft mud at the bottom of the sea1 in which shells and other bodies easily became enveloped4 ,rate of ,deposition indicated by ,fossils4--,by attending to the nature of these remains1 we are often enabled to determine whether the deposition was slow or rapid1 whether it took place in a deep or shallow sea1 near the shore or far from land1 and whether the water was salt1 brackish1 or fresh4 ,some limestones consist almost exclusively of corals1 and in many cases it is evident that the present position of each fossil zoophyte has been determined by the manner in which it grew originally4 ,the axis of the coral1 for example1 if its natural growth is erect1 still remains at right angles to the plane of stratification4 ,if the stratum be now horizontal1 the round spherical heads of certain species continue uppermost1 and their points of attachment are directed downward4 ,this arrangement is sometimes repeated throughout a great succession of strata4 ,from what we know of the growth of similar zoophytes in modern reefs1 we infer that the rate of increase was extremely slow1 and some of the fossils must have flourished for ages like forest-trees1 before they attained so large a size4 ,during these ages1 the water must have been clear and transparent1 for such corals cannot live in turbid water4 ,fossil ,gryph1 covered both on the outside and inside with fossil serpul4 ,in like manner1 when we see thousands of full-grown shells dispersed everywhere throughout a long series of strata1 we cannot doubt that time was required for the multiplication of successive generations2 and the evidence of slow accumulation is rendered more striking from the proofs1 so often discovered1 of fossil bodies having lain for a time on the floor of the ocean after death before they were imbedded in sediment4 ,nothing1 for example1 is more common than to see fossil oysters in clay1 with ,serpul1 or barnacles 7acorn-shells71 or corals1 and other creatures1 attached to the inside of the valves1 so that the mollusk was certainly not buried in argillaceous mud the moment it died4 ,there must have been an interval during which it was still surrounded with clear water1 when the creatures whose remains now adhere to it grew from an embryonic to a mature state4 ,attached shells which are merely external1 like some of the ,serpul 7a7 in ,fig4 #i1 may often have grown upon an oyster or other shell while the animal within was still living2 but if they are found on the inside1 it could only happen after the death of the inhabitant of the shell which affords the support4 ,thus1 in ,fig4 #i1 it will be seen that two ,serpul have grown on the interior1 one of them exactly on the place where the adductor muscle of the ,grypha 7a kind of oyster7 was fixed4 ,fig4 #aj3 ,serpula attached to a fossil4 ,fig4 #aa3 ,recent ,spatangus with spines removed from one side4 ,some fossil shells1 even if simply attached to the outside of others1 bear full testimony to the conclusion above alluded to1 namely1 that an interval elapsed between the death of the creature to whose shell they adhere1 and the burial of the same in mud or sand4 ,the sea-urchins1 or ,echini1 so abundant in white chalk1 afford a good illustration4 ,it is well known that these animals1 when living1 are invariably covered with spines supported by rows of tubercles4 ,these last are only seen after the death of the sea-urchin1 when the spines have dropped off4 ,in ,fig4 #aa a living species of ,spatangus1 common on our coast1 is represented with one half of its shell stripped of the spines4 ,in ,fig4 #aj a fossil of a similar and allied genus from the white chalk of ,england shows the naked surface which the individuals of this family exhibit when denuded of their bristles4 ,the full-grown ,serpula1 therefore1 which now adheres externally1 could not have begun to grow till the ,micraster had died1 and the spines became detached4 ,fig4 #ab3 ,ananchytes from the chalk4 ,now the series of events here attested by a single fossil may be carried a step farther4 ,thus1 for example1 we often meet with a sea-urchin 7,ananchytes7 in the chalk 7see ,fig4 #ab7 which has fixed to it the lower valve of a ,crania1 a genus of bivalve mollusca4 ,the upper valve 7b1 ,fig4 #ab7 is almost invariably wanting1 though occasionally found in a perfect state of preservation in white chalk at some distance4 ,in this case1 we see clearly that the sea-urchin first lived from youth to age1 then died and lost its spines1 which were carried away4 ,then the young ,crania adhered to the bared shell1 grew and perished in its turn2 after which the upper valve was separated from the lower before the ,ananchytes became enveloped in chalky mud4 ,fig4 #ac3 ,fossil wood bored by ,teredina4 ,fig4 #ad3 ,recent wood bored by ,teredo4 ,it may be well to mention one more illustration of the manner in which single fossils may sometimes throw light on a former state of things1 both in the bed of the ocean and on some adjoining land4 ,we meet with many fragments of wood bored by ship-worms at various depths in the clay on which ,london is built4 ,entire branches and stems of trees1 several feet in length1 are sometimes found drilled all over by the holes of these borers1 the tubes and shells of the mollusk still remaining in the cylindrical hollows4 ,in ,fig4 #ad1 e1 a representation is given of a piece of recent wood pierced by the ,teredo navalis1 or common ship-worm1 which destroys wooden piles and ships4 ,when the cylindrical tube d has been extracted from the wood1 the valves are seen at the larger or anterior extremity1 as shown at c4 ,in like manner1 a piece of fossil wood 7a1 ,fig4 #ac7 has been perforated by a kindred but extinct genus1 the ,teredina of ,lamarck4 ,the calcareous tube of this mollusk was united and1 as it were1 soldered on to the valves of the shell 7b71 which therefore cannot be detached from the tube1 like the valves of the recent ,teredo4 ,the wood in this fossil specimen is now converted into a stony mass1 a mixture of clay and lime2 but it must once have been buoyant and floating in the sea1 when the ,teredin lived upon1 and perforated it4 ,again1 before the infant colony settled upon the drift wood1 part of a tree must have been floated down to the sea by a river1 uprooted1 perhaps1 by a flood1 or torn off and cast into the waves by the wind3 and thus our thoughts are carried back to a prior period1 when the tree grew for years on dry land1 enjoying a fit soil and climate4 ,strata of ,organic ,origin4--,it has been already remarked that there are rocks in the interior of continents1 at various depths in the earth1 and at great heights above the sea1 almost entirely made up of the remains of zoophytes and testacea4 ,such masses may be compared to modern oyster-beds and coral-reefs2 and1 like them1 the rate of increase must have been extremely gradual4 ,but there are a variety of stone deposits in the earth's crust1 now proved to have been derived from plants and animals of which the organic origin was not suspected until of late years1 even by naturalists4 ,great surprise was therefore created some years since by the discovery of ,professor ,ehrenberg1 of ,berlin1 that a certain kind of siliceous stone1 called tripoli1 was entirely composed of millions of the remains of organic beings1 which were formerly referred to microscopic ,infusoria1 but which are now admitted to be plants4 ,they abound in rivulets1 lakes1 and ponds in ,england and other countries1 and are termed ,diatomace by those naturalists who believe in their vegetable origin4 ,the subject alluded to has long been well-known in the arts1 under the name of infusorial earth or mountain meal1 and is used in the form of powder for polishing stones and metals4 ,it has been procured1 among other places1 from the mud of a lake at ,dolgelly1 in ,north ,wales1 and from ,bilin1 in ,bohemia1 in which latter place a single stratum1 extending over a wide area1 is no less than fourteen feet thick4 ,this stone1 when examined with a powerful microscope1 is found to consist of the siliceous plates or frustules of the above-figured ,diatomace1 united together without any visible cement4 ,it is difficult to convey an idea of their extreme minuteness2 but ,ehrenberg estimates that in the ,bilin tripoli there are #da1jjj millions of individuals of the ,gaillonella distans 7see ,fig4 #af7 in every cubic inch 7which weighs about #bbj grains71 or about #ahg millions in a single grain4 ,at every stroke1 therefore1 that we make with this polishing powder1 several millions1 perhaps tens of millions1 of perfect fossils are crushed to atoms4 ,figs #ae and #af3 ,gaillonella2 ,fig4 #ag3 ,bacillaria parodoxa ,a well-known substance1 called bog-iron ore1 often met with in peat-mosses1 has often been shown by ,ehrenberg to consist of innumerable articulated threads1 of a yellow ochre colour1 composed of silica1 argillaceous matter1 and peroxide of iron4 ,these threads are the cases of a minute microscopic body1 called ,gaillonella ferruginea 7,fig4 #ae71 associated with the siliceous frustules of other fresh-water alg4 ,layers of this iron ore occurring in ,scotch peat bogs are often called 8the pan10 and are sometimes of economical value4 ,it is clear much time must have been required for the accumulation of strata to which countless generations of ,diatomace have contributed their remains2 and these discoveries lead us naturally to suspect that other deposits1 of which the materials have been supposed to be inorganic1 may in reality be composed chiefly of microscopic organic bodies4 ,that this is the case with the white chalk1 has often been imagined1 and is now proved to be the fact4 ,it has1 moreover1 been lately discovered that the chambers into which these ,foraminifera are divided are actually often filled with thousands of well-preserved organic bodies1 which abound in every minute grain of chalk1 and are especially apparent in the white coating of flints1 often accompanied by innumerable needle-shaped spicul of sponges 7see ,chapter ,,xvii74 8,the dust we tread upon was once alive60--,,byron4 ,how faint an idea does this exclamation of the poet convey of the real wonders of nature6 for here we discover proofs that the calcareous and siliceous dust of which hills are composed has not only been once alive1 but almost every particle1 albeit invisible to the naked eye1 still retains the organic structure which1 at periods of time incalculably remote1 was impressed upon it by the powers of life4 ,fresh-water and ,marine ,fossils4--,strata1 whether deposited in salt or fresh water1 have the same forms2 but the imbedded fossils are very different in the two cases1 because the aquatic animals which frequent lakes and rivers are distinct from those inhabiting the sea4 ,in the northern part of the ,isle of ,wight formations of marl and limestone1 more than #ej feet thick occur1 in which the shells are of extinct species4 ,yet we recognise their fresh-water origin1 because they are of the same genera as those now abounding in ponds1 lakes1 and rivers1 either in our own country or in warmer latitudes4 ,in many parts of ,france--in ,auvergne1 for example--strata occur of limestone1 marl1 and sandstone hundreds of feet thick1 which contain exclusively fresh-water and land shells1 together with the remains of terrestrial quadrupeds4 ,the number of land-shells scattered through some of these fresh-water deposits is exceedingly great2 and there are districts in ,germany where the rocks scarcely contain any other fossils except snail-shells 7helices72 as1 for instance1 the limestone on the left bank of the ,rhine1 between ,mayence and ,worms1 at ,oppenheim1 ,findheim1 ,budenheim1 and other places4 ,in order to account for this phenomenon1 the geologist has only to examine the small deltas of torrents which enter the ,swiss lakes when the waters are low1 such as the newly-formed plain where the ,kander enters the ,lake of ,thun4 ,he there sees sand and mud strewn over with innumerable dead land-shells1 which have been brought down from the valleys in the ,alps in the preceding spring1 during the melting of the snows4 ,again1 if we search the sands on the borders of the ,rhine1 in the lower part of its course1 we find countless land-shells mixed with others of species belonging to lakes1 stagnant pools1 and marshes4 ,these individuals have been washed away from the alluvial plains of the great river and its tributaries1 some from mountainous regions1 others from the low country4 ,although fresh-water formations are often of great thickness1 yet they are usually very limited in area when compared to marine deposits1 just as lakes and estuaries are of small dimensions in comparison with seas4 ,the absence of many fossil forms usually met with in marine strata1 affords a useful negative indication of the fresh-water origin of a formation4 ,for example1 there are no sea-urchins1 no corals1 no chambered shells1 such as the nautilus1 nor microscopic ,foraminifera in lacustrine or fluviatile deposits4 ,in distinguishing the latter from formations accumulated in the sea1 we are chiefly guided by the forms of the mollusca4 ,in a fresh-water deposit1 the number of individual shells is often as great as in a marine stratum1 if not greater2 but there is a smaller variety of species and genera4 ,this might be anticipated from the fact that the genera and species of recent fresh-water and land shells are few when contrasted with the marine4 ,thus1 the genera of true mollusca according to ,woodward's system1 excluding those altogether extinct and those without shells1 amount to #ddf in number1 of which the terrestrial and fresh-water genera scarcely form more than a fifth4#a ,fig4 #ah3 ,cyrena obovata4 ,fig4 #ai3 ,cyrena fluminatis4 ,fig4 #bj3 ,anodonta ,cordierii4 ,fig4 #ba3 ,anodonta latimarginata4 ,fig4 #bb3 ,unio littoralis4 ,almost all bivalve shells1 or those of acephalous mollusca1 are marine1 about sixteen only out of #adj genera being fresh-water4 ,among these last1 the four most common forms1 both recent and fossil1 are ,cyclas1 ,cyrena1 ,unio1 and ,anodonta 7see ,figures72 the two first and two last of which are so nearly allied as to pass into each other4 ,fig4 #bc3 ,grypha incurva4 ,lamarck divided the bivalve mollusca into the ,dimyary1 or those having two large muscular impressions in each valve1 as a b in the ,cyclas1 ,fig4 #ah1 and ,unio1 ,fig4 #bb1 and the ,monomyary1 such as the oyster and scallop1 in which there is only one of these impressions1 as is seen in ,fig4 #bc4 ,now1 as none of these last1 or the unimuscular bivalves1 are fresh-water1#b we may at once presume a deposit containing any of them to be marine4 ,fig4 #bd3 ,planorbis enomphalus4 ,fig4 #be3 ,limna longiscala4 ,fig4 #bf3 ,pauldina lenta4 ,fig4 #bg3 ,succinea amphibia4 ,fig4 #bh3 ,ancylus velletia4 ,fig4 #bi3 ,valvata piscinalis4 ,fig4 #cj3 ,physa hypnorum4 ,fig4 #ca3 ,auricula4 ,fig4 #cb3 ,melania inquinata4 ,fig4 #cc3 ,physa columnaris4 ,fig4 #cd3 ,melanopsis buccinoidea4 ,fig4 #ce3 ,neritina globulud4 ,fig4 #cf3 ,nerita granulosa4 ,the univalve shells most characteristic of fresh-water deposits are1 ,planorbis1 ,limna1 and ,paludina4 7,see ,figures47 ,but to these are occasionally added ,physa1 ,succinea1 ,ancylus1 ,valvata1 ,melanopsis1 ,melania1 ,potamides1 and ,neritina 7see ,figures71 the four last being usually found in estuaries4 ,fig4 #cg3 ,potamides cinctus4 ,some naturalists include ,neritina 7,fig4 #ce7 and the marine ,nerita 7,fig4 #cf7 in the same genus1 it being scarcely possible to distinguish the two by good generic characters4 ,but1 as a general rule1 the fluviatile species are smaller1 smoother1 and more globular than the marine2 and they have never1 like the ,nerit1 the inner margin of the outer lip toothed or crenulated4 7,see ,fig4 #cf47 ,the ,potamides inhabit the mouths of rivers in warm latitudes1 and are distinguishable from the marine ,cerithia by their orbicular and multispiral opercula4 ,the genus ,auricula 7,fig4 #ca7 is amphibious1 frequenting swamps and marshes within the influence of the tide4 ,the terrestrial shells are all univalves4 ,the most important genera among these1 both in a recent and fossil state1 are ,helix 7,fig4 #ch71 ,cyclostoma 7,fig4 #ci71 ,pupa 7,fig4 #dj71 ,clausilia 7,fig4 #da71 ,bulimus 7,fig4 #db71 ,glandina and ,achatina4 ,fig4 #ch3 ,helix ,turomensis4 ,fig4 #ci3 ,cyclostoma elegans4 ,fig4 #dj3 ,pupa tridens4 ,fig4 #da3 ,clausilia bidens4 ,fig4 #db3 ,bulimus lubricus4 ,ampullaria 7,fig4 #dc7 is another genus of shells inhabiting rivers and ponds in hot countries4 ,many fossil species formerly referred to this genus1 and which have been met with chiefly in marine formations1 are now considered by conchologists to belong to ,natica and other marine genera4 ,fig4 #dc3 ,ampullaria glauca4 ,all univalve shells of land and fresh-water species1 with the exception of ,melanopsis 7,fig4 #cd71 and ,achatina1 which has a slight indentation1 have entire mouths2 and this circumstance may often serve as a convenient rule for distinguishing fresh-water from marine strata2 since1 if any univalves occur of which the mouths are not entire1 we may presume that the formation is marine4 ,the aperture is said to be entire in such shells as the fresh-water ,ampullaria and the land-shells 7,figs #ch-db71 when its outline is not interrupted by an indentation or notch1 such as that seen at b in ,ancillaria 7,fig4 #de72 or is not prolonged into a canal1 as that seen at a in ,pleurotoma 7,fig4 #dd74 ,fig4 #dd3 ,pleurotoma exorta4 ,fig4 #de3 ,ancillaria subulata4 ,the mouths of a large proportion of the marine univalves have these notches or canals1 and almost all species are carnivorous2 whereas nearly all testacea having entire mouths are plant-eaters1 whether the species be marine1 fresh-water1 or terrestrial4 ,there is1 however1 one genus which affords an occasional exception to one of the above rules4 ,the ,potamides 7,fig4 #cg71 a subgenus of ,cerithium1 although provided with a short canal1 comprises some species which inhabit salt1 others brackish1 and others fresh-water1 and they are said to be all plant-eaters4 ,among the fossils very common in fresh-water deposits are the shells of ,cypris1 a minute bivalve crustaceous animal4#c ,many minute living species of this genus swarm in lakes and stagnant pools in ,great ,britain2 but their shells are not1 if considered separately1 conclusive as to the fresh-water origin of a deposit1 because the majority of species in another kindred genus of the same order1 the ,cytherina of ,lamarck1 inhabit salt-water2 and1 although the animal differs slightly1 the shell is scarcely distinguishable from that of the ,cypris4 ,fresh-water ,fossil ,plants4--,the seed-vessels and stems of ,chara1 a genus of aquatic plants1 are very frequent in fresh-water strata4 ,these seed-vessels were called1 before their true nature was known1 gyrogonites1 and were supposed to be foraminiferous shells4 7,see ,fig4 #df1 a47 ,the ,char inhabit the bottom of lakes and ponds1 and flourish mostly where the water is charged with carbonate of lime4 ,their seed-vessels are covered with a very tough integument1 capable of resisting decomposition2 to which circumstance we may attribute their abundance in a fossil state4 ,the annexed figure 7,fig4 #dg7 represents a branch of one of many new species found by ,professor ,amici in the lakes of ,northern ,italy4 ,the seed-vessel in this plant is more globular than in the ,british ,char17 and therefore more nearly resembles in form the extinct fossil species found in ,england1 ,france1 and other countries4 ,the stems1 as well as the seed-vessels1 of these plants occur both in modern shell-marl and in ancient fresh-water formations4 ,they are generally composed of a large central tube surrounded by smaller ones2 the whole stem being divided at certain intervals by transverse partitions or joints4 7,see b1 ,fig4 #df47 ,fig4 #df3 ,chara medicaginula4 ,fig4 #dg3 ,chara elastica4 ,it is not uncommon to meet with layers of vegetable matter1 impressions of leaves1 and branches of trees1 in strata containing fresh-water shells2 and we also find occasionally the teeth and bones of land quadrupeds1 of species now unknown4 ,the manner in which such remains are occasionally carried by rivers into lakes1 especially during floods1 has been fully treated of in the 8,principles of ,geology40 ,fresh-water and ,marine ,fish4--,the remains of fish are occasionally useful in determining the fresh-water origin of strata4 ,certain genera1 such as carp1 perch1 pike1 and loach 7,cyprinus1 ,perca1 ,esox1 and ,cobitis71 as also ,lebias1 being peculiar to fresh-water4 ,other genera contain some fresh-water and some marine species1 as ,cottus1 ,mugil1 and ,anguilla1 or eel4 ,the rest are either common to rivers and the sea1 as the salmon2 or are exclusively characteristic of salt-water4 ,the above observations respecting fossil fishes are applicable only to the more modern or tertiary deposits2 for in the more ancient rocks the forms depart so widely from those of existing fishes1 that it is very difficult1 at least in the present state of science1 to derive any positive information from ichthyolites respecting the element in which strata were deposited4 ,the alternation of marine and fresh-water formations1 both on a small and large scale1 are facts well ascertained in geology4 ,when it occurs on a small scale1 it may have arisen from the alternate occupation of certain spaces by river-water and the sea2 for in the flood season the river forces back the ocean and freshens it over a large area1 depositing at the same time its sediment2 after which the salt-water again returns1 and1 on resuming its former place1 brings with it sand1 mud1 and marine shells4 ,there are also lagoons at the mouth of many rivers1 as the ,nile and ,mississippi1 which are divided off by bars of sand from the sea1 and which are filled with salt and fresh water by turns4 ,they often communicate exclusively with the river for months1 years1 or even centuries2 and then a breach being made in the bar of sand1 they are for long periods filled with salt-water4 ,lym-,fiord4--,the ,lym-,fiord in ,jutland offers an excellent illustration of analogous changes2 for1 in the course of the last thousand years1 the western extremity of this long frith1 which is #abj miles in length1 including its windings1 has been four times fresh and four times salt1 a bar of sand between it and the ocean having been often formed and removed4 ,the last irruption of salt water happened in #ahbd1 when the ,north ,sea entered1 killing all the fresh-water shells1 fish1 and plants2 and from that time to the present1 the sea-weed ,fucus vesiculosus1 together with oysters and other marine mollusca1 have succeeded the ,cyclas1 ,lymna1 ,paludina1 and ,char4#d ,but changes like these in the ,lym-,fiord1 and those before mentioned as occurring at the mouths of great rivers1 will only account for some cases of marine deposits of partial extent resting on fresh-water strata4 ,when we find1 as in the south-east of ,england 7,chapter ,,xviii71 a great series of fresh-water beds1 #ajjj feet in thickness1 resting upon marine formations and again covered by other rocks1 such as the ,cretaceous1 more than #ajjj feet thick1 and of deep-sea origin1 we shall find it necessary to seek for a different explanation of the phenomena4 #a ,see ,woodward's ,manual of ,mollusca1 #ahef4 #b ,the fresh-water ,mulleria1 when young1 forms a single exception to the rule1 as it then has two muscular impressions1 but it has only one in the adult state4 #c ,for figures of fossil species of ,purbeck1 see ,chapter ,,xix #d ,see ,principles1 ,index1 8,lym-,fiord40 ,,chapter ,,iv4 ,,consolidation ,,of ,,strata ,,and ,,petrifaction ,,of ,,fossils4 ,chemical and ,mechanical ,deposits4 -- ,cementing together of ,particles4 -- ,hardening by ,exposure to ,air4 -- ,concretionary ,nodules4 -- ,consolidating ,effects of ,pressure4 -- ,mineralization of ,organic ,remains4 -- ,impressions and ,casts3 how formed4 -- ,fossil ,wood4 -- ,goppert's ,experiments4 -- ,precipitation of ,stony ,matter most rapid where ,putrefaction is going on4 -- ,sources of ,lime and ,silex in ,solution4 ,having spoken in the preceding chapters of the characters of sedimentary formations1 both as dependent on the deposition of inorganic matter and the distribution of fossils1 ,i may next treat of the consolidation of stratified rocks1 and the petrifaction of imbedded organic remains4 ,chemical and ,mechanical ,deposits4-- ,a distinction has been made by geologists between deposits of a mechanical1 and those of a chemical1 origin4 ,by the name mechanical are designated beds of mud1 sand1 or pebbles produced by the action of running water1 also accumulations of stones and scori thrown out by a volcano1 which have fallen into their present place by the force of gravitation4 ,but the matter which forms a chemical deposit has not been mechanically suspended in water1 but in a state of solution until separated by chemical action4 ,in this manner carbonate of lime is occasionally precipitated upon the bottom of lakes in a solid form1 as may be well seen in many parts of ,italy1 where mineral springs abound1 and where the calcareous stone1 called travertin1 is deposited4 ,in these springs the lime is usually held in solution by an excess of carbonic acid1 or by heat if it be a hot spring1 until the water1 on issuing from the earth1 cools or loses part of its acid4 ,the calcareous matter then falls down in a solid state1 incrusting shells1 fragments of wood and leaves1 and binding them together4 ,that similar travertin is formed at some points in the bed of the sea where calcareous springs issue cannot be doubted1 but as a general rule the quantity of lime1 according to ,bischoff1 spread through the waters of the ocean is very small1 the free carbonic acid gas in the same waters being five times as much as is necessary to keep the lime in a fluid state4 ,carbonate of lime1 therefore1 can rarely be precipitated at the bottom of the sea by chemical action alone1 but must be produced by vital agency as in the case of coral reefs4 ,in such reefs1 large masses of limestone are formed by the stony skeletons of zoophytes2 and these1 together with shells1 become cemented together by carbonate of lime1 part of which is probably furnished to the sea-water by the decomposition of dead corals4 ,even shells1 of which the animals are still living on these reefs1 are very commonly found to be incrusted over with a hard coating of limestone4 ,if sand and pebbles are carried by a river into the sea1 and these are bound together immediately by carbonate of lime1 the deposit may be described as of a mixed origin1 partly chemical1 and partly mechanical4 ,now1 the remarks already made in ,chapter ,,ii1 on the original horizontality of strata are strictly applicable to mechanical deposits1 and only partially to those of a mixed nature4 ,such as are purely chemical may be formed on a very steep slope1 or may even incrust the vertical walls of a fissure1 and be of equal thickness throughout2 but such deposits are of small extent1 and for the most part confined to vein-stones4 ,consolidation of ,strata4--,it is chiefly in the case of calcareous rocks that solidification takes place at the time of deposition4 ,but there are many deposits in which a cementing process comes into operation long afterwards4 ,we may sometimes observe1 where the water of ferruginous or calcareous springs has flowed through a bed of sand or gravel1 that iron or carbonate of lime has been deposited in the interstices between the grains or pebbles1 so that in certain places the whole has been bound together into a stone1 the same set of strata remaining in other parts loose and incoherent4 ,proofs of a similar cementing action are seen in a rock at ,kelloway1 in ,wiltshire4 ,a peculiar band of sandy strata belonging to the group called ,oolite by geologists may be traced through several counties1 the sand being for the most part loose and unconsolidated1 but becoming stony near ,kelloway4 ,in this district there are numerous fossil shells which have decomposed1 having for the most part left only their casts4 ,the calcareous matter hence derived has evidently served1 at some former period1 as a cement to the siliceous grains of sand1 and thus a solid sandstone has been produced4 ,if we take fragments of many other argillaceous grits1 retaining the casts of shells1 and plunge them into dilute muriatic or other acid1 we see them immediately changed into common sand and mud2 the cement of lime1 derived from the shells1 having been dissolved by the acid4 ,traces of impressions and casts are often extremely faint4 ,in some loose sands of recent date we meet with shells in so advanced a stage of decomposition as to crumble into powder when touched4 ,it is clear that water percolating such strata may soon remove the calcareous matter of the shell2 and unless circumstances cause the carbonate of lime to be again deposited1 the grains of sand will not be cemented together2 in which case no memorial of the fossil will remain4 ,in what manner silex and carbonate of lime may become widely diffused in small quantities through the waters which permeate the earth's crust will be spoken of presently1 when the petrifaction of fossil bodies is considered2 but ,i may remark here that such waters are always passing in the case of thermal springs from hotter to colder parts of the interior of the earth2 and1 as often as the temperature of the solvent is lowered1 mineral matter has a tendency to separate from it and solidify4 ,thus a stony cement is often supplied to sand1 pebbles1 or any fragmentary mixture4 ,in some conglomerates1 like the pudding-stone of ,hertfordshire 7a ,lower ,eocene deposit71 pebbles of flint and grains of sand are united by a siliceous cement so firmly1 that if a block be fractured1 the rent passes as readily through the pebbles as through the cement4 ,it is probable that many strata became solid at the time when they emerged from the waters in which they were deposited1 and when they first formed a part of the dry land4 ,a well-known fact seems to confirm this idea3 by far the greater number of the stones used for building and road-making are much softer when first taken from the quarry than after they have been long exposed to the air2 and these1 when once dried1 may afterwards be immersed for any length of time in water without becoming soft again4 ,hence it is found desirable to shape the stones which are to be used in architecture while they are yet soft and wet1 and while they contain their 8quarry-water10 as it is called2 also to break up stone intended for roads when soft1 and then leave it to dry in the air for months that it may harden4 ,such induration may perhaps be accounted for by supposing the water1 which penetrates the minutest pores of rocks1 to deposit1 on evaporation1 carbonate of lime1 iron1 silex1 and other minerals previously held in solution1 and thereby to fill up the pores partially4 ,these particles1 on crystallising1 would not only be themselves deprived of freedom of motion1 but would also bind together other portions of the rock which before were loosely aggregated4 ,on the same principle wet sand and mud become as hard as stone when frozen2 because one ingredient of the mass1 namely1 the water1 has crystallised1 so as to hold firmly together all the separate particles of which the loose mud and sand were composed4 ,dr4 ,mac,culloch mentions a sandstone in ,skye1 which may be moulded like dough when first found2 and some simple minerals1 which are rigid and as hard as glass in our cabinets1 are often flexible and soft in their native beds3 this is the case with asbestos1 sahlite1 tremolite1 and chalcedony1 and it is reported also to happen in the case of the beryl4#a ,the marl recently deposited at the bottom of ,lake ,superior1 in ,north ,america1 is soft1 and often filled with fresh-water shells2 but if a piece be taken up and dried1 it becomes so hard that it can only be broken by a smart blow of the hammer4 ,if the lake1 therefore1 was drained1 such a deposit would be found to consist of strata of marlstone1 like that observed in many ancient ,european formations1 and1 like them1 containing fresh-water shells4 ,fig4 #dh3 ,calcareous nodules in ,lias4 ,concretionary ,structure4--,it is probable that some of the heterogeneous materials which rivers transport to the sea may at once set under water1 like the artificial mixture called pozzolana1 which consists of fine volcanic sand charged with about twenty per cent of oxide of iron1 and the addition of a small quantity of lime4 ,this substance hardens1 and becomes a solid stone in water1 and was used by the ,romans in constructing the foundations of buildings in the sea4 ,consolidation in such cases is brought about by the action of chemical affinity on finely comminuted matter previously suspended in water4 ,after deposition similar particles seem often to exert a mutual attraction on each other1 and congregate together in particular spots1 forming lumps1 nodules1 and concretions4 ,thus in many argillaceous deposits there are calcareous balls1 or spherical concretions1 ranged in layers parallel to the general stratification2 an arrangement which took place after the shale or marl had been thrown down in successive lamin2 for these lamin are often traceable through the concretions1 remaining parallel to those of the surrounding unconsolidated rock4 7,see ,fig4 #dh47 ,such nodules of limestone have often a shell or other foreign body in the centre4 ,among the most remarkable examples of concretionary structure are those described by ,professor ,sedgwick as abounding in the magnesian limestone of the north of ,england4 ,the spherical balls are of various sizes1 from that of a pea to a diameter of several feet1 and they have both a concentric and radiated structure1 while at the same time the lamin of original deposition pass uninterruptedly through them4 ,in some cliffs this limestone resembles a great irregular pile of cannon-balls4 ,some of the globular masses have their centre in one stratum1 while a portion of their exterior passes through to the stratum above or below4 ,thus the larger spheroid in the section 7,fig4 #di7 passes from the stratum b upward into a4 ,in this instance we must suppose the deposition of a series of minor layers1 first forming the stratum b1 and afterwards the incumbent stratum a2 then a movement of the particles took place1 and the carbonates of lime and magnesia separated from the more impure and mixed matter forming the still unconsolidated parts of the stratum4 ,crystallisation1 beginning at the centre1 must have gone on forming concentric coats around the original nucleus without interfering with the laminated structure of the rock4 ,fig4 #di3 ,spheroidal concretions in magnesian limestone4 ,fig4 #ej3 ,section through strata of grit4 ,when the particles of rocks have been thus rearranged by chemical forces1 it is sometimes difficult or impossible to ascertain whether certain lines of division are due to original deposition or to the subsequent aggregation of several particles4 ,thus suppose three strata of grit1 ,a1 ,b1 ,c1 are charged unequally with calcareous matter1 and that ,b is the most calcareous4 ,if consolidation takes place in ,b1 the concretionary action may spread upward into a part of ,a1 where the carbonate of lime is more abundant than in the rest2 so that a mass1 d e f1 forming a portion of the superior stratum1 becomes united with ,b into one solid mass of stone4 ,the original line of division1 d e1 being thus effaced1 the line d f would generally be considered as the surface of the bed ,b1 though not strictly a true plane of stratification4 ,pressure and ,heat4--,when sand and mud sink to the bottom of a deep sea1 the particles are not pressed down by the enormous weight of the incumbent ocean2 for the water1 which becomes mingled with the sand and mud1 resists pressure with a force equal to that of the column of fluid above4 ,the same happens in regard to organic remains which are filled with water under great pressure as they sink1 otherwise they would be immediately crushed to pieces and flattened4 ,nevertheless1 if the materials of a stratum remain in a yielding state1 and do not set or solidify1 they will be gradually squeezed down by the weight of other materials successively heaped upon them1 just as soft clay or loose sand on which a house is built may give way4 ,by such downward pressure particles of clay1 sand1 and marl may become packed into a smaller space1 and be made to cohere together permanently4 ,analogous effects of condensation may arise when the solid parts of the earth's crust are forced in various directions by those mechanical movements hereafter to be described1 by which strata have been bent1 broken1 and raised above the level of the sea4 ,rocks of more yielding materials must often have been forced against others previously consolidated1 and may thus by compression have acquired a new structure4 ,a recent discovery may help us to comprehend how fine sediment derived from the detritus of rocks may be solidified by mere pressure4 ,the graphite or 8black lead0 of commerce having become very scarce1 ,mr4 ,brockedon contrived a method by which the dust of the purer portions of the mineral found in ,borrowdale might be recomposed into a mass as dense and compact as native graphite4 ,the powder of graphite is first carefully prepared and freed from air1 and placed under a powerful press on a strong steel die1 with air-tight fittings4 ,it is then struck several blows1 each of a power of #ajjj tons2 after which operation the powder is so perfectly solidified that it can be cut for pencils1 and exhibits when broken the same texture as native graphite4 ,but the action of heat at various depths in the earth is probably the most powerful of all causes in hardening sedimentary strata4 ,to this subject ,i shall refer again when treating of the metamorphic rocks1 and of the slaty and jointed structure4 ,mineralisation of ,organic ,remains4--,the changes which fossil organic bodies have undergone since they were first imbedded in rocks1 throw much light on the consolidation of strata4 ,fossil shells in some modern deposits have been scarcely altered in the course of centuries1 having simply lost a part of their animal matter4 ,but in other cases the shell has disappeared1 and left an impression only of its exterior1 or1 secondly1 a cast of its interior form1 or1 thirdly1 a cast of the shell itself1 the original matter of which has been removed4 ,these different forms of fossilisation may easily be understood if we examine the mud recently thrown out from a pond or canal in which there are shells4 ,if the mud be argillaceous1 it acquires consistency on drying1 and on breaking open a portion of it we find that each shell has left impressions of its external form4 ,if we then remove the shell itself1 we find within a solid nucleus of clay1 having the form of the interior of the shell4 ,this form is often very different from that of the outer shell4 ,thus a cast such as a1 ,fig4 #ea1 commonly called a fossil screw1 would never be suspected by an inexperienced conchologist to be the internal shape of the fossil univalve1 b1 ,fig4 #ea4 ,nor should we have imagined at first sight that the shell a and the cast b1 ,fig4 #eb1 belong to one and the same fossil4 ,the reader will observe1 in the last-mentioned figure 7b1 ,fig4 #eb71 that an empty space shaded dark1 which the shell itself once occupied1 now intervenes between the enveloping stone and the cast of the smooth interior of the whorls4 ,in such cases the shell has been dissolved and the component particles removed by water percolating the rock4 ,if the nucleus were taken out1 a hollow mould would remain1 on which the external form of the shell with its tubercles and stri1 as seen in a1 ,fig4 #eb1 would be seen embossed4 ,now if the space alluded to between the nucleus and the impression1 instead of being left empty1 has been filled up with calcareous spar1 flint1 pyrites1 or other mineral1 we then obtain from the mould an exact cast both of the external and internal form of the original shell4 ,in this manner silicified casts of shells have been formed2 and if the mud or sand of the nucleus happen to be incoherent1 or soluble in acid1 we can then procure in flint an empty shell1 which in shape is the exact counterpart of the original4 ,this cast may be compared to a bronze statue1 representing merely the superficial form1 and not the internal organisation2 but there is another description of petrifaction by no means uncommon1 and of a much more wonderful kind1 which may be compared to certain anatomical models in wax1 where not only the outward forms and features1 but the nerves1 blood-vessels1 and other internal organs are also shown4 ,thus we find corals1 originally calcareous1 in which not only the general shape1 but also the minute and complicated internal organisation is retained in flint4 ,fig4 #ea3 ,phasianella ,heddingtonensis4 ,fig4 #eb3 ,pleurotomaria ,anglica4 ,fig4 #ec3 ,section of a tree from the coal-measures4 ,such a process of petrifaction is still more remarkably exhibited in fossil wood1 in which we often perceive not only the rings of annual growth1 but all the minute vessels and medullary rays4 ,many of the minute cells and fibres of plants1 and even those spiral vessels which in the living vegetable can only be discovered by the microscope1 are preserved4 ,among many instances1 ,i may mention a fossil tree1 seventy-two feet in length1 found at ,gosforth1 near ,newcastle1 in sandstone strata associated with coal4 ,by cutting a transverse slice so thin as to transmit light1 and magnifying it about fifty-five times1 the texture1 as seen in ,fig4 #ec1 is exhibited4 ,a texture equally minute and complicated has been observed in the wood of large trunks of fossil trees found in the ,craigleith quarry near ,edinburgh1 where the stone was not in the slightest degree siliceous1 but consisted chiefly of carbonate of lime1 with oxide of iron1 alumina1 and carbon4 ,the parallel rows of vessels here seen are the rings of annual growth1 but in one part they are imperfectly preserved1 the wood having probably decayed before the mineralising matter had penetrated to that portion of the tree4 ,in attempting to explain the process of petrifaction in such cases1 we may first assume that strata are very generally permeated by water charged with minute portions of calcareous1 siliceous1 and other earths in solution4 ,in what manner they become so impregnated will be afterwards considered4 ,if an organic substance is exposed in the open air to the action of the sun and rain1 it will in time putrefy1 or be dissolved into its component elements1 consisting usually of oxygen1 hydrogen1 nitrogen1 and carbon4 ,these will readily be absorbed by the atmosphere or be washed away by rain1 so that all vestiges of the dead animal or plant disappear4 ,but if the same substances be submerged in water1 they decompose more gradually2 and if buried in earth1 still more slowly2 as in the familiar example of wooden piles or other buried timber4 ,now1 if as fast as each particle is set free by putrefaction in a fluid or gaseous state1 a particle equally minute of carbonate of lime1 flint1 or other mineral1 is at hand ready to be precipitated1 we may imagine this inorganic matter to take the place just before left unoccupied by the organic molecule4 ,in this manner a cast of the interior of certain vessels may first be taken1 and afterwards the more solid walls of the same may decay and suffer a like transmutation4 ,yet when the whole is lapidified1 it may not form one homogeneous mass of stone or metal4 ,some of the original ligneous1 osseous1 or other organic elements may remain mingled in certain parts1 or the lapidifying substance itself may be differently coloured at different times1 or so crystallised as to reflect light differently1 and thus the texture of the original body may be faithfully exhibited4 ,the student may perhaps ask whether1 on chemical principles1 we have any ground to expect that mineral matter will be thrown down precisely in those spots where organic decomposition is in progress8 ,the following curious experiments may serve to illustrate this point3 ,professor ,goppert of ,breslau1 with a view of imitating the natural process of petrifaction1 steeped a variety of animal and vegetable substances in waters1 some holding siliceous1 others calcareous1 others metallic matter in solution4 ,he found that in the period of a few weeks1 or sometimes even days1 the organic bodies thus immersed were mineralised to a certain extent4 ,thus1 for example1 thin vertical slices of deal1 taken from the ,scotch fir 7,pinus sylvestris71 were immersed in a moderately strong solution of sulphate of iron4 ,when they had been thoroughly soaked in the liquid for several days they were dried and exposed to a red-heat until the vegetable matter was burnt up and nothing remained but an oxide of iron1 which was found to have taken the form of the deal so exactly that casts even of the dotted vessels peculiar to this family of plants were distinctly visible under the microscope4 ,the late ,dr4 ,turner observes1 that when mineral matter is in a 8nascent state10 that is to say1 just liberated from a previous state of chemical combination1 it is most ready to unite with other matter1 and form a new chemical compound4 ,probably the particles or atoms just set free are of extreme minuteness1 and therefore move more freely1 and are more ready to obey any impulse of chemical affinity4 ,whatever be the cause1 it clearly follows1 as before stated1 that where organic matter newly imbedded in sediment is decomposing1 there will chemical changes take place most actively4 ,an analysis was lately made of the water which was flowing off from the rich mud deposited by the ,hooghly ,river in the ,delta of the ,ganges after the annual inundation4 ,this water was found to be highly charged with carbonic acid holding lime in solution4#b ,now if newly-deposited mud is thus proved to be permeated by mineral matter in a state of solution1 it is not difficult to perceive that decomposing organic bodies1 naturally imbedded in sediment1 may as readily become petrified as the substances artificially immersed by ,professor ,goppert in various fluid mixtures4 ,it is well known that the waters of all springs are more or less charged with earthy1 alkaline1 or metallic ingredients derived from the rocks and mineral veins through which they percolate4 ,silex is especially abundant in hot springs1 and carbonate of lime is almost always present in greater or less quantity4 ,the materials for the petrifaction of organic remains are1 therefore1 usually at hand in a state of chemical solution wherever organic remains are imbedded in new strata4 #a ,dr4 ,mac,culloch1 ,syst4 of ,geol41 vol4 i1 p4 #abc4 #b ,piddington1 ,asiat4 ,research41 vol4 xviii1 p4 #bbf4 ,,chapter ,v4 ,,elevation ,,of ,,strata ,,above ,,the ,,sea4--,,horizontal ,,and ,,inclined ,,stratification4 ,why the ,position of ,marine ,strata1 above the ,level of the ,sea1 should be referred to the rising up of the ,land1 not to the going down of the ,sea4 -- ,strata of ,deep-sea and ,shallow-water ,origin alternate4 -- ,also ,marine and ,fresh-water ,beds and old ,land ,surfaces4 -- ,vertical1 inclined1 and folded ,strata4 -- ,anticlinal and ,synclinal ,curves4 -- ,theories to explain ,lateral ,movements4 -- ,creeps in ,coal-mines4 -- ,dip and ,strike4 -- ,structure of the ,jura4 -- ,various ,forms of ,outcrop4 -- ,synclinal ,strata forming ,ridges4 -- ,connection of ,fracture and ,flexure of ,rocks4 -- ,inverted ,strata4 -- ,faults described4 -- ,superficial ,signs of the same obliterated by ,denudation4 -- ,great ,faults the ,result of repeated ,movements4 -- ,arrangement and ,direction of parallel ,folds of ,strata4 -- ,unconformability4 -- ,overlapping ,strata4 ,land has been raised1 not the ,sea lowered4--,it has been already stated that the aqueous rocks containing marine fossils extend over wide continental tracts1 and are seen in mountain chains rising to great heights above the level of the sea 7p4 #bi74 ,hence it follows1 that what is now dry land was once under water4 ,but if we admit this conclusion1 we must imagine1 either that there has been a general lowering of the waters of the ocean1 or that the solid rocks1 once covered by water1 have been raised up bodily out of the sea1 and have thus become dry land4 ,the earlier geologists1 finding themselves reduced to this alternative1 embraced the former opinion1 assuming that the ocean was originally universal1 and had gradually sunk down to its actual level1 so that the present islands and continents were left dry4 ,it seemed to them far easier to conceive that the water had gone down1 than that solid land had risen upward into its present position4 ,it was1 however1 impossible to invent any satisfactory hypothesis to explain the disappearance of so enormous a body of water throughout the globe1 it being necessary to infer that the ocean had once stood at whatever height marine shells might be detected4 ,it moreover appeared clear1 as the science of geology advanced1 that certain spaces on the globe had been alternately sea1 then land1 then estuary1 then sea again1 and1 lastly1 once more habitable land1 having remained in each of these states for considerable periods4 ,in order to account for such phenomena without admitting any movement of the land itself1 we are required to imagine several retreats and returns of the ocean2 and even then our theory applies merely to cases where the marine strata composing the dry land are horizontal1 leaving unexplained those more common instances where strata are inclined1 curved1 or placed on their edges1 and evidently not in the position in which they were first deposited4 ,geologists1 therefore1 were at last compelled to have recourse to the doctrine that the solid land has been repeatedly moved upward or downward1 so as permanently to change its position relatively to the sea4 ,there are several distinct grounds for preferring this conclusion4 ,first1 it will account equally for the position of those elevated masses of marine origin in which the stratification remains horizontal1 and for those in which the strata are disturbed1 broken1 inclined1 or vertical4 ,secondly1 it is consistent with human experience that land should rise gradually in some places and be depressed in others4 ,such changes have actually occurred in our own days1 and are now in progress1 having been accompanied in some cases by violent convulsions1 while in others they have proceeded so insensibly as to have been ascertainable only by the most careful scientific observations1 made at considerable intervals of time4 ,on the other hand1 there is no evidence from human experience of a rising or lowering of the sea's level in any region1 and the ocean cannot be raised or depressed in one place without its level being changed all over the globe4 ,these preliminary remarks will prepare the reader to understand the great theoretical interest attached to all facts connected with the position of strata1 whether horizontal or inclined1 curved or vertical4 ,now the first and most simple appearance is where strata of marine origin occur above the level of the sea in horizontal position4 ,such are the strata which we meet with in the south of ,sicily1 filled with shells for the most part of the same species as those now living in the ,mediterranean4 ,some of these rocks rise to the height of more than #bjjj feet above the sea4 ,other mountain masses might be mentioned1 composed of horizontal strata of high antiquity1 which contain fossil remains of animals wholly dissimilar from any now known to exist4 ,in the south of ,sweden1 for example1 near ,lake ,wener1 the beds of some of the oldest fossiliferous deposits1 called ,silurian and ,cambrian by geologists1 occur in as level a position as if they had recently formed part of the delta of a great river1 and been left dry on the retiring of the annual floods4 ,aqueous rocks of equal antiquity extend for hundreds of miles over the lake-district of ,north ,america1 and exhibit in like manner a stratification nearly undisturbed4 ,the ,table ,mountain at the ,cape of ,good ,hope is another example of highly elevated yet perfectly horizontal strata1 no less than #cejj feet in thickness1 and consisting of sandstone of very ancient date4 ,instead of imagining that such fossiliferous rocks were always at their present level1 and that the sea was once high enough to cover them1 we suppose them to have constituted the ancient bed of the ocean1 and to have been afterwards uplifted to their present height4 ,this idea1 however startling it may at first appear1 is quite in accordance1 as before stated1 with the analogy of changes now going on in certain regions of the globe4 ,thus1 in parts of ,sweden1 and the shores and islands of the ,gulf of ,bothnia1 proofs have been obtained that the land is experiencing1 and has experienced for centuries1 a slow upheaving movement4#a ,it appears from the observations of ,mr4 ,darwin and others1 that very extensive regions of the continent of ,south ,america have been undergoing slow and gradual upheaval1 by which the level plains of ,patagonia1 covered with recent marine shells1 and the ,pampas of ,buenos ,ayres1 have been raised above the level of the sea4 ,on the other hand1 the gradual sinking of the west coast of ,greenland1 for the space of more than #fjj miles from north to south1 during the last four centuries1 has been established by the observations of a ,danish naturalist1 ,dr4 ,pingel4 ,and while these proofs of continental elevation and subsidence1 by slow and insensible movements1 have been recently brought to light1 the evidence has been daily strengthened of continued changes of level effected by violent convulsions in countries where earthquakes are frequent4 ,there the rocks are rent from time to time1 and heaved up or thrown down several feet at once1 and disturbed in such a manner as to show how entirely the original position of strata may be modified in the course of centuries4 ,mr4 ,darwin has also inferred that1 in those seas where circular coral islands and barrier reefs abound1 there is a slow and continued sinking of the submarine mountains on which the masses of coral are based2 while there are other areas of the ,south ,sea where the land is on the rise1 and where coral has been upheaved far above the sea-level4 ,alternations of ,marine and ,fresh-water ,strata4--,it has been shown in the third chapter that there is such a differencebetween land1 fresh-water1 and marine fossils as to enable the geologist to determine whether particular groups of strata were formed at the bottom of the ocean or in estuaries1 rivers1 or lakes4 ,if surprise was at first created by the discovery of marine corals and shells at the height of several miles above the sea-level1 the imagination was afterwards not less startled by observing that in the successive strata composing the earth's crust1 especially if their total thickness amounted to thousands of feet1 they comprised in some parts formations of shallow-sea as well as of deep-sea origin2 also beds of brackish or even of purely fresh-water formation1 as well as vegetable matter or coal accumulated on ancient land4 ,in these cases we as frequently find fresh-water beds below a marine set or shallow-water under those of deep-sea origin as the reverse4 ,thus1 if we bore an artesian well below ,london1 we pass through a marine clay1 and there reach1 at the depth of several hundred feet1 a shallow-water and fluviatile sand1 beneath which comes the white chalk originally formed in a deep sea4 ,or if we bore vertically through the chalk of the ,north ,downs1 we come1 after traversing marine chalky strata1 upon a fresh-water formation many hundreds of feet thick1 called the ,wealden1 such as is seen in ,kent and ,surrey1 which is known in its turn to rest on purely marine beds4 ,in like manner1 in various parts of ,great ,britain we sink vertical shafts through marine deposits of great thickness1 and come upon coal which was formed by the growth of plants on an ancient land-surface sometimes hundreds of square miles in extent4 ,vertical1 ,inclined1 and ,curved ,strata4--,it has been stated that marine strata of different ages are sometimes found at a considerable height above the sea1 yet retaining their original horizontality2 but this state of things is quite exceptional4 ,as a general rule1 strata are inclined or bent in such a manner as to imply that their original position has been altered4 ,fig4 #ed3 ,vertical conglomerate and sandstone4 ,the most unequivocal evidence of such a change is afforded by their standing up vertically1 showing their edges1 which is by no means a rare phenomenon1 especially in mountainous countries4 ,thus we find in ,scotland1 on the southern skirts of the ,grampians1 beds of pudding-stone alternating with thin layers of fine sand1 all placed vertically to the horizon4 ,when ,saussure first observed certain conglomerates in a similar position in the ,swiss ,alps1 he remarked that the pebbles1 being for the most part of an oval shape1 had their longer axes parallel to the planes of stratification 7see ,fig4 #ed on preceding page74 ,from this he inferred that such strata must1 at first1 have been horizontal1 each oval pebble having settled at the bottom of the water1 with its flatter side parallel to the horizon1 for the same reason that an egg will not stand on either end if unsupported4 ,some few1 indeed1 of the rounded stones in a conglomerate occasionally afford an exception to the above rule1 for the same reason that in a river's bed1 or on a shingle beach1 some pebbles rest on their ends or edges2 these having been shoved against or between other stones by a wave or current1 so as to assume this position4 ,anticlinal and ,synclinal ,curves4--,vertical strata1 when they can be traced continuously upward or downward for some depth1 are almost invariably seen to be parts of great curves1 which may have a diameter of a few yards1 or of several miles4 ,i shall first describe two curves of considerable regularity1 which occur in ,forfarshire1 extending over a country twenty miles in breadth1 from the foot of the ,grampians to the sea near ,arbroath4 ,fig4 #ee3 ,section of ,forfarshire1 from ,n4,w4 to ,s4,e4 ,the mass of strata here shown may be #bjjj feet in thickness1 consisting of red and white sandstone1 and various coloured shales1 the beds being distinguishable into four principal groups1 namely1 ,no4 #a1 red marl or shale2 ,no4 #b1 red sandstone1 used for building2 ,no4 #c1 conglomerate2 and ,no4 #d1 grey paving-stone1 and tile-stone1 with green and reddish shale1 containing peculiar organic remains4 ,a glance at the section will show that each of the formations #b1 #c1 #d are repeated thrice at the surface1 twice with a southerly1 and once with a northerly inclination or dip1 and the beds in ,no4 #a1 which are nearly horizontal1 are still brought up twice by a slight curvature to the surface1 once on each side of ,a4 ,beginning at the north-west extremity1 the tile-stones and conglomerates1 ,no4 #d and ,no4 #c1 are vertical1 and they generally form a ridge parallel to the southern skirts of the ,grampians4 ,the superior strata1 ,nos4 #b and #a1 become less and less inclined on descending to the valley of ,strathmore1 where the strata1 having a concave bend1 are said by geologists to lie in a 8trough0 or8basin40 ,through the centre of this valley runs an imaginary line ,a1 called technically a 8synclinal line10 where the beds1 which are tilted in opposite directions1 may be supposed to meet4 ,it is most important for the observer to mark such lines1 for he will perceive by the diagram that1 in travelling from the north to the centre of the basin1 he is always passing from older to newer beds2 whereas1 after crossing the line ,a1 and pursuing his course in the same southerly direction1 he is continually leaving the newer1 and advancing upon older strata4 ,all the deposits which he had before examined begin then to recur in reversed order1 until he arrives at the central axis of the ,sidlaw hills1 where the strata are seen to form an arch1 or saddle1 having an anticlinal line1 ,b1 in the centre4 ,on passing this line1 and continuing towards the ,s4,e41 the formations #d1 #c1 and #b1 are again repeated1 in the same relative order of superposition1 but with a southerly dip4 ,at ,whiteness 7see ,fig4 #ee7 it will be seen that the inclined strata are covered by a newer deposit1 a1 in horizontal beds4 ,these are composed of red conglomerate and sand1 and are newer than any of the groups1 #a1 #b1 #c1 #d1 before described1 and rest unconformably upon strata of the sandstone group1 ,no4 #b4 ,an example of curved strata1 in which the bends or convolutions of the rock are sharper and far more numerous within an equal space1 has been well described by ,sir ,james ,hall4#b ,it occurs near ,st4 ,abb's ,head1 on the east coast of ,scotland1 where the rocks consist principally of a bluish slate1 having frequently a ripple-marked surface4 ,the undulations of the beds reach from the top to the bottom of cliffs from #bjj to #cjj feet in height1 and there are sixteen distinct bendings in the course of about six miles1 the curvatures being alternately concave and convex upward4 ,folding by ,lateral ,movement4--,an experiment was made by ,sir ,james ,hall1 with a view of illustrating the manner in which such strata1 assuming them to have been originally horizontal1 may have been forced into their present position4 ,a set of layers of clay were placed under a weight1 and their opposite ends pressed towards each other with such force as to cause them to approach more nearly together4 ,on the removal of the weight1 the layers of clay were found to be curved and folded1 so as to bear a miniature resemblance to the strata in the cliffs4 ,we must1 however1 bear in mind that in the natural section or sea-cliff we only see the foldings imperfectly1 one part being invisible beneath the sea1 and the other1 or upper portion1 being supposed to have been carried away by denudation1 or that action of water which will be explained in the next chapter4 ,the dark lines in the plan 7,fig4 #eg7 represent what is actually seen of the strata in the line of cliff alluded to2 the fainter lines1 that portion which is concealed beneath the sea-level1 as also that which is supposed to have once existed above the present surface4 ,fig4 #ef3 ,curved strata of slate near ,st4 ,abb's ,head1 ,berwickshire4 ,fig4 #eg ,we may still more easily illustrate the effects which a lateral thrust might produce on flexible strata1 by placing several pieces of differently coloured cloths upon a table1 and when they are spread out horizontally1 cover them with a book4 ,then apply other books to each end1 and force them towards each other4 ,the folding of the cloths 7see ,fig4 #eh7 will imitate those of the bent strata2 the incumbent book being slightly lifted up1 and no longer touching the two volumes on which it rested before1 because it is supported by the tops of the anticlinal ridges formed by the curved cloths4 ,in like manner there can be no doubt that the squeezed strata1 although laterally condensed and more closely packed1 are yet elongated and made to rise upward1 in a direction perpendicular to the pressure4 ,fig4 #eh ,whether the analogous flexures in stratified rocks have really been due to similar sideway movements is a question which we can not decide by reference to our own observation4 ,our inability to explain the nature of the process is1 perhaps1 not simply owing to the inaccessibility of the subterranean regions where the mechanical force is exerted1 but to the extreme slowness of the movement4 ,the changes may sometimes be due to variation in the temperature of mountain masses of rock causing them1 while still solid1 to expand or contract2 or melting them1 and then again cooling them and allowing them to crystallise4 ,if such be the case1 we have scarcely more reason to expect to witness the operation of the process within the limited periods of our scientific observation than to see the swelling of the roots of a tree1 by which1 in the course of years1 a wall of solid masonry may be lifted up1 rent or thrown down4 ,in both instances the force may be irresistible1 but though adequate1 it need not be visible by us1 provided the time required for its development be very great4 ,the lateral pressure arising from the unequal expansion of rocks by heat may cause one mass lying in the same horizontal plane gradually to occupy a larger space1 so as to press upon another rock1 which1 if flexible1 may be squeezed into a bent and folded form4 ,it will also appear1 when the volcanic and granitic rocks are described1 that some of them have1 when melted in the interior of the earth's crust1 been injected forcibly into fissures1 and after the solidification of such intruded matter1 other sets of rents1 crossing the first1 have been formed and in their turn filled by melted rock4 ,such repeated injections imply a stretching1 and often upheaval1 of the whole mass4 ,we also know1 especially by the study of regions liable to earthquakes1 that there are causes at work in the interior of the earth capable of producing a sinking in of the ground1 sometimes very local1 but often extending over a wide area4 ,the continuance of such a downward movement1 especially if partial and confined to linear areas1 may produce regular folds in the strata4 ,creeps in ,coal-mines4--,the 8creeps10 as they are called in coal-mines1 afford an excellent illustration of this fact4--,first1 it may be stated generally1 that the excavation of coal at a considerable depth causes the mass of overlying strata to sink down bodily1 even when props are left to support the roof of the mine4 8,in ,yorkshire10 says ,mr4 ,buddle1 8three distinct subsidences were perceptible at the surface1 after the clearing out of three seams of coal below1 and innumerable vertical cracks were caused in the incumbent mass of sandstone and shale which thus settled down40#c ,the exact amount of depression in these cases can only be accurately measured where water accumulates on the surface1 or a railway traverses a coal-field4 ,when a bed of coal is worked out1 pillars or rectangular masses of coal are left at intervals as props to support the roof1 and protect the colliers4 ,thus in ,fig4 #ei1 representing a section at ,wallsend1 ,newcastle1 the galleries which have been excavated are represented by the white spaces a1 b1 while the adjoining dark portions are parts of the original coal seam left as props1 beds of sandy clay or shale constituting the floor of the mine4 ,when the props have been reduced in size1 they are pressed down by the weight of overlying rocks 7no less than #fcj feet thick7 upon the shale below1 which is thereby squeezed and forced up into the open spaces4 ,now it might have been expected that1 instead of the floor rising up1 the ceiling would sink down1 and this effect1 called a 8thrust10 does1 in fact1 take place where the pavement is more solid than the roof4 ,but it usually happens1 in coal-mines1 that the roof is composed of hard shale1 or occasionally of sandstone1 more unyielding than the foundation1 which often consists of clay4 ,even where the argillaceous substrata are hard at first1 they soon become softened and reduced to a plastic state when exposed to the contact of air and water in the floor of a mine4 ,fig4 #ei3 ,section of carboniferous strata at ,wallsend showing #8creeps'4 ,the first symptom of a 8creep10 says ,mr4 ,buddle1 is a slight curvature at the bottom of each gallery1 as at a1 ,fig4 #ei3 then the pavement1 continuing to rise1 begins to open with a longitudinal crack1 as at b2 then the points of the fractured ridge reach the roof1 as at c2 and1 lastly1 the upraised beds close up the whole gallery1 and the broken portions of the ridge are reunited and flattened at the top1 exhibiting the flexure seen at d4 ,meanwhile the coal in the props has become crushed and cracked by pressure4 ,it is also found that below the creeps a1 b1 c1 d1 an inferior stratum1 called the 8metal coal10 which is #c feet thick1 has been fractured at the points e1 f1 g1 h1 and has risen1 so as to prove that the upward movement1 caused by the working out of the 8main coal10 has been propagated through a thickness of #ed feet of argillaceous beds1 which intervene between the two coal-seams4 ,this same displacement has also been traced downward more than #aej feet below the metal coal1 but it grows continually less and less until it becomes imperceptible4 ,no part of the process above described is more deserving of our notice than the slowness with which the change in the arrangement of the beds is brought about4 ,days1 months1 or even years1 will sometimes elapse between the first bending of the pavement and the time of its reaching the roof4 ,where the movement has been most rapid1 the curvature of the beds is most regular1 and the reunion of the fractured ends most complete2 whereas the signs of displacement or violence are greatest in those creeps which have required months or years for their entire accomplishment4 ,hence we may conclude that similar changes may have been wrought on a larger scale in the earth's crust by partial and gradual subsidences1 especially where the ground has been undermined throughout long periods of time2 and we must be on our guard against inferring sudden violence1 simply because the distortion of the beds is excessive4 ,engineers are familiar with the fact that when they raise the level of a railway by heaping stone or gravel on a foundation of marsh1 quicksand1 or other yielding formation1 the new mound often sinks for a time as fast as they attempt to elevate it2 when they have persevered so as to overcome this difficulty1 they frequently find that some of the adjoining flexible ground has risen up in one or more parallel arches or folds1 showing that the vertical pressure of the sinking materials has given rise to a lateral folding movement4 ,in like manner1 in the interior of the earth1 the solid parts of the earth's crust may sometimes1 as before mentioned1 be made to expand by heat1 or may be pressed by the force of steam against flexible strata loaded with a great weight of incumbent rocks4 ,in this case the yielding mass1 squeezed1 but unable to overcome the resistance which it meets with in a vertical direction1 may be gradually relieved by lateral folding4 ,fig4 #fj ,dip and ,strike4--,in describing the manner in which strata depart from their original horizontality1 some technical terms1 such as 8dip0 and 8strike10 8anticlinal0 and 8synclinal0 line or axis1 are used by geologists4 ,i shall now proceed to explain some of these to the student4 ,if a stratum or bed of rock1 instead of being quite level1 be inclined to one side1 it is said to dip2 the point of the compass to which it is inclined is called the point of dip1 and the degree of deviation from a level or horizontal line is called the amount of dip1 or the angle of dip4 ,thus1 in the annexed diagram 7,fig4 #fj71 a series of strata are inclined1 and they dip to the north at an angle of forty-five degrees4 ,the strike1 or line of bearing1 is the prolongation or extension of the strata in a direction at right angles to the dip2 and hence it is sometimes called the direction of the strata4 ,thus1 in the above instance of strata dipping to the north1 their strike must necessarily be east and west4 ,we have borrowed the word from the ,german geologists1 streichen signifying to extend1 to have a certain direction4 ,dip and strike may be aptly illustrated by a row of houses running east and west1 the long ridge of the roof representing the strike of the stratum of slates1 which dip on one side to the north1 and on the other to the south4 ,a stratum which is horizontal1 or quite level in all directions1 has neither dip nor strike4 ,it is always important for the geologist1 who is endeavouring to comprehend the structure of a country1 to learn how the beds dip in every part of the district2 but it requires some practice to avoid being occasionally deceived1 both as to the point of dip and the amount of it4 ,fig4 #fa3 ,apparent horizontality of inclined strata4 ,if the upper surface of a hard stony stratum be uncovered1 whether artificially in a quarry1 or by waves at the foot of a cliff1 it is easy to determine towards what point of the compass the slope is steepest1 or in what direction water would flow if poured upon it4 ,this is the true dip4 ,but the edges of highly inclined strata may give rise to perfectly horizontal lines in the face of a vertical cliff1 if the observer see the strata in the line of the strike1 the dip being inward from the face of the cliff4 ,if1 however1 we come to a break in the cliff1 which exhibits a section exactly at right angles to the line of the strike1 we are then able to ascertain the true dip4 ,in the drawing 7,fig4 #fa71 we may suppose a headland1 one side of which faces to the north1 where the beds would appear perfectly horizontal to a person in the boat2 while in the other side facing the west1 the true dip would be seen by the person on shore to be at an angle of #dj4 ,if1 therefore1 our observations are confined to a vertical precipice facing in one direction1 we must endeavour to find a ledge or portion of the plane of one of the beds projecting beyond the others1 in order to ascertain the true dip4 ,fig4 #fb3 ,two hands used to determine the inclination of strata4 ,if not provided with a clinometer1 a most useful instrument1 when it is of consequence to determine with precision the inclination of the strata1 the observer may measure the angle within a few degrees by standing exactly opposite to a cliff where the true dip is exhibited1 holding the hands immediately before the eyes1 and placing the fingers of one in a perpendicular1 and of the other in a horizontal position1 as in ,fig4 #fb4 ,it is thus easy to discover whether the lines of the inclined beds bisect the angle of #ij1 formed by the meeting of the hands1 so as to give an angle of #de1 or whether it would divide the space into two equal or unequal portions4 ,you have only to change hands to get the line of dip on the upper side of the horizontal hand4 ,fig4 #fc3 ,section illustrating the structure of the ,swiss ,jura4 ,it has been already seen1 in describing the curved strata on the east coast of ,scotland1 in ,forfarshire and ,berwickshire1 that a series of concave and convex bendings are occasionally repeated several times4 ,these usually form part of a series of parallel waves of strata1 which are prolonged in the same direction1 throughout a considerable extent of country4 ,thus1 for example1 in the ,swiss ,jura1 that lofty chain of mountains has been proved to consist of many parallel ridges1 with intervening longitudinal valleys1 as in ,fig4 #fc1 the ridges being formed by curved fossiliferous strata1 of which the nature and dip are occasionally displayed in deep transverse gorges1 called 8cluses10 caused by fractures at right angles to the direction of the chain4#d ,now let us suppose these ridges and parallel valleys to run north and south1 we should then say that the strike of the beds is north and south1 and the dip east and west4 ,lines drawn along the summits of the ridges1 ,a1 ,b1 would be anticlinal lines1 and one following the bottom of the adjoining valleys a synclinal line4 ,fig4 #fd3 ,ground-plan of the denuded ridge ,c1 ,fig4 #fc4 ,fig4 #fe3 ,transverse section4 ,outcrop of ,strata4--,it will be observed that some of these ridges1 ,a1 ,b1 are unbroken on the summit1 whereas one of them1 ,c1 has been fractured along the line of strike1 and a portion of it carried away by denudation1 so that the ridges of the beds in the formations a1 b1 c come out to the day1 or1 as the miners say1 crop out1 on the sides of a valley4 ,the ground-plan of such a denuded ridge as ,c1 as given in a geological map1 may be expressed by the diagram1 ,fig4 #fd1 and the cross-section of the same by ,fig4 #fe4 ,the line ,d ,e1 ,fig4 #fd1 is the anticlinal line1 on each side of which the dip is in opposite directions1 as expressed by the arrows4 ,the emergence of strata at the surface is called by miners their outcrop1 or basset4 ,if1 instead of being folded into parallel ridges1 the beds form a boss or dome-shaped protuberance1 and if we suppose the summit of the dome carried off1 the ground-plan would exhibit the edges of the strata forming a succession of circles1 or ellipses1 round a common centre4 ,these circles are the lines of strike1 and the dip being always at right angles is inclined in the course of the circuit to every point of the compass1 constituting what is termed a qu-quversal dip--that is1 turning every way4 ,there are endless variations in the figures described by the basset-edges of the strata1 according to the different inclination of the beds1 and the mode in which they happen to have been denuded4 ,one of the simplest rules1 with which every geologist should be acquainted1 relates to the ,v-like form of the beds as they crop out in an ordinary valley4 ,first1 if the strata be horizontal1 the ,v-like form will be also on a level1 and the newest strata will appear at the greatest heights4 ,fig4 #ff3 ,slope of valley #dj1 dip of strata #bj4 ,fig4 #fg3 ,slope of valley #bj1 dip of strata #ej4 ,fig4 #fh3 ,slope of valley #bj1 dip of strata #bj1 in opposite directions4 ,secondly1 if the beds be inclined and intersected by a valley sloping in the same direction1 and the dip of the beds be less steep than the slope of the valley1 then the ,v's1 as they are often termed by miners1 will point upward 7see ,fig4 #ff71 those formed by the newer beds appearing in a superior position1 and extending highest up the valley1 as ,a is seen above ,b4 ,thirdly1 if the dip of the beds be steeper than the slope of the valley1 then the ,v's will point downward 7see ,fig4 #fg71 and those formed of the older beds will now appear uppermost1 as ,b appears above ,a4 ,fourthly1 in every case where the strata dip in a contrary direction to the slope of the valley1 whatever be the angle of inclination1 the newer beds will appear the highest1 as in the first and second cases4 ,this is shown by the drawing 7,fig4 #fh71 which exhibits strata rising at an angle of #bj1 and crossed by a valley1 which declines in an opposite direction at #bj4 ,these rules may often be of great practical utility2 for the different degrees of dip occurring in the two cases represented in ,figs4 #ff and #fg may occasionally be encountered in following the same line of flexure at points a few miles distant from each other4 ,a miner unacquainted with the rule1 who had first explored the valley ,fig4 #ff1 may have sunk a vertical shaft below the coal-seam ,a1 until he reached the inferior bed1 ,b4 ,he might then pass to the valley1 ,fig4 #fg1 and discovering there also the outcrop of two coal-seams1 might begin his workings in the uppermost in the expectation of coming down to the other bed ,a1 which would be observed cropping out lower down the valley4 ,but a glance at the section will demonstrate the futility of such hopes4#e ,section of carboniferous rocks of ,lancashire4 ,section of carboniferous rocks of ,lancashire4 7,e4 ,hull4#f7 ,synclinal ,strata forming ,ridges4--,although in many cases an anticlinal axis forms a ridge1 and a synclinal axis a valley1 as in ,a ,b1 ,fig4 #fc1 yet this can by no means be laid down as a general rule1 as the beds very often slope inward from either side of a mountain1 as at a1 b1 ,fig4 #fi1 while in the intervening valley1 c1 they slope upward1 forming an arch4 ,it would be natural to expect the fracture of solid rocks to take place chiefly where the bending of the strata has been sharpest1 and such rending may produce ravines giving access to running water and exposing the surface to atmospheric waste4 ,the entire absence1 however1 of such cracks at points where the strain must have been greatest1 as at a1 ,fig4 #fc1 is often very remarkable1 and not always easy of explanation4 ,we must imagine that many strata of limestone1 chert1 and other rocks which are now brittle1 were pliant when bent into their present position4 ,they may have owed their flexibility in part to the fluid matter which they contained in their minute pores1 as before described p4 #fb and in part to the permeation of sea-water while they were yet submerged4 ,fig4 #gj3 ,strata of chert1 grit1 and marl1 near ,st4 ,jean de ,luz4 ,at the western extremity of the ,pyrenees1 great curvatures of the strata are seen in the sea-cliffs1 where the rocks consist of marl1 grit1 and chert4 ,at certain points1 as at a1 ,fig4 #gj1 some of the bendings of the flinty chert are so sharp that specimens might be broken off well fitted to serve as ridge-tiles on the roof of a house4 ,although this chert could not have been brittle as now1 when first folded into this shape1 it presents1 nevertheless1 here and there1 at the points of greatest flexure1 small cracks1 which show that it was solid1 and not wholly incapable of breaking at the period of its displacement4 ,the numerous rents alluded to are not empty1 but filled with chalcedony and quartz4 ,fig4 #ga3 ,bent and undulating gypseous marl4 ,between ,san ,caterina and ,castrogiovanni1 in ,sicily1 bent and undulating gypseous marls occur1 with here and there thin beds of solid gypsum interstratified4 ,sometimes these solid layers have been broken into detached fragments1 still preserving their sharp edges 7g1 g1 ,fig4 #ga71 while the continuity of the more pliable and ductile marls1 m1 m1 has not been interrupted4 ,fig4 #gb3 ,folded strata4 ,we have already explained1 ,fig4 #fi1 that stratified rocks have usually their strata bent into parallel folds forming anticlinal and synclinal axes1 a group of several of these folds having often been subjected to a common movement1 and having acquired a uniform strike or direction4 ,in some disturbed regions these folds have been doubled back upon themselves in such a manner that it is often difficult for an experienced geologist to determine correctly the relative age of the beds by superposition4 ,thus1 if we meet with the strata seen in the section1 ,fig4 #gb1 we should naturally suppose that there were twelve distinct beds1 or sets of beds1 ,no4 #a being the newest1 and ,no4 #ab the oldest of the series4 ,but this section may perhaps exhibit merely six beds1 which have been folded in the manner seen in ,fig4 #gc1 so that each of them is twice repeated1 the position of one half being reversed1 and part of ,no4 #a1 originally the uppermost1 having now become the lowest of the series4 ,fig4 #gc ,these phenomena are observable on a magnificent scale in certain regions in ,switzerland1 in precipices often more than #bjjj feet in perpendicular height1 and there are flexures not inferior in dimensions in the ,pyrenees4 ,the upper part of the curves seen in this diagram1 ,fig4 #gc1 and expressed in fainter lines1 has been removed by what is called denudation1 to be afterwards explained4 ,fractures of the ,strata and ,faults4--,numerous rents may often be seen in rocks which appear to have been simply broken1 the fractured parts still remaining in contact2 but we often find a fissure1 several inches or yards wide1 intervening between the disunited portions4 ,these fissures are usually filled with fine earth and sand1 or with angular fragments of stone1 evidently derived from the fracture of the contiguous rocks4 ,the face of each wall of the fissure is often beautifully polished1 as if glazed1 striated1 or scored with parallel furrows and ridges1 such as would be produced by the continued rubbing together of surfaces of unequal hardness4 ,these polished surfaces are called by miners 8slickensides40 ,it is supposed that the lines of the stri indicate the direction in which the rocks were moved4 ,during one of the minor earthquakes in ,chili1 in #ahdj1 the brick walls of a building were rent vertically in several places1 and made to vibrate for several minutes during each shock1 after which they remained uninjured1 and without any opening1 although the line of each crack was still visible4 ,when all movement had ceased1 there were seen on the floor of the house1 at the bottom of each rent1 small heaps of fine brick-dust1 evidently produced by trituration4 ,it is not uncommon to find the mass of rock on one side of a fissure thrown up above or down below the mass with which it was once in contact on the other side4 8,this mode of displacement is called a fault1 shift1 slip1 or throw40 8,the miner10 says ,playfair1 describing a fault1 8is often perplexed1 in his subterranean journey1 by a derangement in the strata1 which changes at once all those lines and bearings which had hitherto directed his course4 ,when his mine reaches a certain plane1 which is sometimes perpendicular1 as in ,a ,b1 ,fig4 #gd1 sometimes oblique to the horizon 7as in ,c ,d1 ibid471 he finds the beds of rock broken asunder1 those on the one side of the plane having changed their place1 by sliding in a particular direction along the face of the others4 ,in this motion they have sometimes preserved their parallelism1 as in ,fig4 #gd1 so that the strata on each side of faults ,a ,b1 ,c ,d1 continue parallel to one another2 in other cases1 the strata on each side are inclined1 as in a1 b1 c1 d 7,fig4 #ge71 though their identity is still to be recognised by their possessing the same thickness and the same internal characters40#g ,fig4 #gd3 ,faults4 ,fig4 #ge3 ,e ,f1 fault or fissure filled with rubbish1 on each side of which the shifted strata are not parallel4 ,in ,coalbrook ,dale1 says ,mr4 ,prestwich#h1 deposits of sandstone1 shale1 and coal1 several thousand feet thick1 and occupying an area of many miles1 have been shivered into fragments1 and the broken remnants have been placed in very discordant positions1 often at levels differing several hundred feet from each other4 ,the sides of the faults1 when perpendicular1 are commonly several yards apart1 and are sometimes as much as #ej yards asunder1 the interval being filled with broken dbris of the strata4 ,in following the course of the same fault it is sometimes found to produce in different places very unequal changes of level1 the amount of shift being in one place #cjj1 and in another #gjj feet1 which arises from the union of two or more faults4 ,in other words1 the disjointed strata have in certain districts been subjected to renewed movements1 which they have not suffered elsewhere4 ,we may occasionally see exact counterparts of these slips1 on a small scale1 in pits of loose sand and gravel1 many of which have doubtless been caused by the drying and shrinking of argillaceous and other beds1 slight subsidences having taken place from failure of support4 ,sometimes1 however1 even these small slips may have been produced during earthquakes2 for land has been moved1 and its level1 relatively to the sea1 considerably altered1 within the period when much of the alluvial sand and gravel now covering the surface of continents was deposited4 ,i have already stated that a geologist must be on his guard1 in a region of disturbed strata1 against inferring repeated alternations of rocks1 when1 in fact1 the same strata1 once continuous1 have been bent round so as to recur in the same section1 and with the same dip4 ,a similar mistake has often been occasioned by a series of faults4 ,fig4 #gf3 ,apparent alternations of strata caused by vertical faults4 ,if1 for example1 the dark line ,a ,h 7,fig4 #gf7 represent the surface of a country on which the strata a1 b1 c frequently crop out1 an observer who is proceeding from ,h to ,a might at first imagine that at every step he was approaching new strata1 whereas the repetition of the same beds has been caused by vertical faults1 or downthrows4 ,thus1 suppose the original mass1 ,a1 ,b1 ,c1 ,d1 to have been a set of uniformly inclined strata1 and that the different masses under ,e ,f1 ,f ,g1 and ,g ,d sank down successively1 so as to leave vacant the spaces marked in the diagram by dotted lines1 and to occupy those marked by the continuous lines1 then let denudation take place along the line ,a ,h1 so that the protruding masses indicated by the fainter lines are swept away--a miner1 who has not discovered the faults1 finding the mass a1 which we will suppose to be a bed of coal four times repeated1 might hope to find four beds1 workable to an indefinite depth1 but first1 on arriving at the fault ,g1 he is stopped suddenly in his workings1 for he comes partly upon the shale b1 and partly on the sandstone c2 the same result awaits him at the fault ,f1 and on reaching ,e he is again stopped by a wall composed of the rock d4 ,the very different levels at which the separated parts of the same strata are found on the different sides of the fissure1 in some faults1 is truly astonishing4 ,one of the most celebrated in ,england is that called the 8ninety-fathom dike10 in the coal-field of ,newcastle4 ,this name has been given to it1 because the same beds are ninety fathoms 7#edj feet7 lower on the northern than they are on the southern side4 ,the fissure has been filled by a body of sand1 which is now in the state of sandstone1 and is called the dike1 which is sometimes very narrow1 but in other places more than twenty yards wide4#i ,the walls of the fissure are scored by grooves1 such as would have been produced if the broken ends of the rock had been rubbed along the plane of the fault4#aj ,in the ,tynedale and ,craven faults1 in the north of ,england1 the vertical displacement is still greater1 and the fracture has extended in a horizontal direction for a distance of thirty miles or more4 ,great ,faults the ,result of ,repeated ,movements4--,it must not1 however1 be supposed that faults generally consist of single linear rents2 there are usually a number of faults springing off from the main one1 and sometimes a long strip of country seems broken up into fragments by sets of parallel and connecting transverse faults4 ,oftentimes a great line of fault has been repeated1 or the movements have been continued through successive periods1 so that1 newer deposits having covered the old line of displacement1 the strata both newer and older have given way along the old line of fracture4 ,some geologists have considered it necessary to imagine that the upward or downward movement in these cases was accomplished at a single stroke1 and not by a series of sudden but interrupted movements4 ,they appear to have derived this idea from a notion that the grooved walls have merely been rubbed in one direction1 which is far from being a constant phenomenon4 ,not only are some sets of stri not parallel to others1 but the clay and rubbish between the walls1 when squeezed or rubbed1 have been streaked in different directions1 the grooves which the harder minerals have impressed on the softer being frequently curved and irregular4 ,fig4 #gg3 ,faults and denuded coal-strata1 ,ashby de la ,zouch4 ,the usual absence of protruding masses of rock forming precipices or ridges along the lines of great faults has already been alluded to in explaining ,fig4 #gf1 p4 #hi1 and the same remarkable fact is well exemplified in every coal-field which has been extensively worked4 ,it is in such districts that the former relation of the beds which have been shifted is determinable with great accuracy4 ,thus in the coal-field of ,ashby de la ,zouch1 in ,leicestershire 7see ,fig4 #gg71 a fault occurs1 on one side of which the coal-beds a1 b1 c1 d must once have risen to the height of #ejj feet above the corresponding beds on the other side4 ,but the uplifted strata do not stand up #ejj feet above the general surface2 on the contrary1 the outline of the country1 as expressed by the line z z1 is uniformly undulating1 without any break1 and the mass indicated by the dotted outline must have been washed away4#aa ,the student may refer to ,mr4 ,hull's measurement of faults1 observed in the ,lancashire coal-field1 where the vertical displacement has amounted to thousands of feet1 and yet where all the superficial inequalities which must have resulted from such movements have been obliterated by subsequent denudation4 ,in the same memoir proofs are afforded of there having been two periods of vertical movement in the same fault--one1 for example1 before1 and another after1 the ,triassic epoch4#ab ,the shifting of the beds by faults is often intimately connected with those same foldings which constitute the anticlinal and synclinal axes before alluded to1 and there is no doubt that the subterranean causes of both forms of disturbance are to a great extent the same4 ,a fault in ,virginia1 believed to imply a displacement of several thousand feet1 has been traced for more than eighty miles in the same direction as the foldings of the ,appalachian chain4#ac ,an hypothesis which attributes such a change of position to a succession of movements1 is far preferable to any theory which assumes each fault to have been accomplished by a single upcast or downthrow of several thousand feet4 ,for we know that there are operations now in progress1 at great depths in the interior of the earth1 by which both large and small tracts of ground are made to rise above and sink below their former level1 some slowly and insensibly1 others suddenly and by starts1 a few feet or yards at a time2 whereas there are no grounds for believing that1 during the last #cjjj years at least1 any regions have been either upheaved or depressed1 at a single stroke1 to the amount of several hundred1 much less several thousand feet4 ,it is certainly not easy to understand how in the subterranean regions one mass of solid rock should have been folded up by a continued series of movements1 while another mass in contact1 or only separated by a line of fissure1 has remained stationary or has perhaps subsided4 ,but every volcano1 by the intermittent action of the steam1 gases1 and lava evolved during an eruption1 helps us to form some idea of the manner in which such operations take place4 ,for eruptions are repeated at uncertain intervals throughout the whole or a large part of a geological period1 some of the surrounding and contiguous districts remaining quite undisturbed4 ,and in most of the instances with which we are best acquainted the emission of lava1 scoria1 and steam is accompanied by the uplifting of the solid crust4 ,thus in ,vesuvius1 ,etna1 the ,madeiras1 the ,canary ,islands1 and the ,azores there is evidence of marine deposits of recent and tertiary date having been elevated to the height of a thousand feet1 and sometimes more1 since the commencement of the volcanic explosions4 ,there is1 moreover1 a general tendency in contemporaneous volcanic vents to affect a linear arrangement1 extending in some instances1 as in the ,andes or the ,indian ,archipelago1 to distances equalling half the circumference of the globe4 ,where volcanic heat1 therefore1 operates at such a depth as not to obtain vent at the surface1 in the form of an eruption1 it may nevertheless be conceived to give rise to upheavals1 foldings1 and faults in certain linear tracts4 ,and marine denudation1 to be treated of in the next chapter1 will help us to understand why that which should be the protruding portion of the faulted rocks is missing at the surface4 ,arrangement and ,direction of ,parallel ,folds of ,strata4--,the possible causes of the folding of strata by lateral movements have been considered in a former part of this chapter4 ,no ,european chain of mountains affords so remarkable an illustration of the persistency of such flexures for a great distance as the ,appalachians before alluded to1 and none has been studied and described by many good observers with more accuracy4 ,the chain extends from north to south1 or rather ,n4,n4,e4 to ,s4,s4,w41 for nearly #aejj miles1 with a breadth of #ej miles1 throughout which the ,palozoic strata have been so bent as to form a series of parallel anticlinal and synclinal ridges and troughs1 comprising usually three or four principal and many smaller plications1 some of them forming broad and gentle arches1 others narrower and steeper ones1 while some1 where the bending has been greatest1 have the position of their beds inverted1 as before shown in ,fig4 #gc1 p4 #hg4 ,the strike of the parallel ridges1 after continuing in a straight line for many hundred miles1 is then found to vary for a more limited distance as much as #cj1 the folds wheeling round together in the new direction and continuing to be parallel1 as if they had all obeyed the same movement4 ,the date of the movements by which the great flexures were brought about must1 of course1 be subsequent to the formation of the uppermost part of the coal or the newest of the bent rocks1 but the disturbance must have ceased before the ,triassic strata were deposited on the denuded edges of the folded beds4 ,the manner in which the numerous parallel folds1 all simultaneously formed1 assume a new direction common to the whole of them1 and sometimes varying at an angle of #cj from the normal strike of the chain1 shows what deviation from an otherwise uniform strike of the beds may be experienced when the geographical area through which they are traced is on so vast a scale4 ,the disturbances in the case here adverted to occurred between the ,carboniferous period and that of the ,trias1 and this interval is so vast that they may have occupied a great lapse of time1 during which their parallelism was always preserved4 ,but1 as a rule1 wherever after a long geological interval the recurrence of lateral movements gives rise to a new set of folds1 the strike of these last is different4 ,thus1 for example1 ,mr4 ,hull has pointed out that three principal lines of disturbance1 all later than the ,carboniferous period1 have affected the stratified rocks of ,lancashire4 ,the first of these1 having an ,e4,n4,e4 direction1 took place at the close of the ,carboniferous period4 ,the next1 running north and south1 at the close of the ,permian1 and the third1 having a ,n4,n4,w4 direction1 at the close of the ,jurassic period4#ad ,fig4 #gh3 ,unconformable junction of old red sandstone and ,silurian schist at the ,siccar ,point1 near ,st4 ,abb's ,head1 ,berwickshire4 ,unconformability of ,strata4-- ,strata are said to be unconformable when one series is so placed over another that the planes of the superior repose on the edges of the inferior 7see ,fig4 #gh74 ,in this case it is evident that a period had elapsed between the production of the two sets of strata1 and that1 during this interval1 the older series had been tilted and disturbed4 ,afterwards the upper series was thrown down in horizontal strata upon it4 ,if these superior beds1 d1 d1 ,fig4 #gh1 are also inclined1 it is plain that the lower strata a1 a1 have been twice displaced2 first1 before the deposition of the newer beds1 d1 d1 and a second time when these same strata were upraised out of the sea1 and thrown slightly out of the horizontal position4 ,fig4 #gi3 ,junction of unconformable strata near ,mons1 in ,belgium4 ,it often happens that in the interval between the deposition of two sets of unconformable strata1 the inferior rock has not only been denuded1 but drilled by perforating shells4 ,thus1 for example1 at ,autreppe and ,gusigny1 near ,mons1 beds of an ancient 7primary or palozoic7 limestone1 highly inclined1 and often bent1 are covered with horizontal strata of greenish and whitish marls of the ,cretaceous formation4 ,the lowest1 and therefore the oldest1 bed of the horizontal series is usually the sand and conglomerate1 a1 in which are rounded fragments of stone1 from an inch to two feet in diameter4 ,these fragments have often adhering shells attached to them1 and have been bored by perforating mollusca4 ,the solid surface of the inferior limestone has also been bored1 so as to exhibit cylindrical and pear-shaped cavities1 as at c1 the work of saxicavous mollusca2 and many rents1 as at b1 which descend several feet or yards into the limestone1 have been filled with sand and shells1 similar to those in the stratum a4 ,overlapping ,strata4--,strata are said to overlap when an upper bed extends beyond the limits of a lower one4 ,this may be produced in various ways2 as1 for example1 when alterations of physical geography cause the arms of a river or channels of discharge to vary1 so that sediment brought down is deposited over a wider area than before1 or when the sea-bottom has been raised up and again depressed without disturbing the horizontal position of the strata4 ,in this case the newer strata may rest for the most part conformably on the older1 but1 extending farther1 pass over their edges4 ,every intermediate state between unconformable and over-lapping beds may occur1 because there may be every gradation between a slight derangement of position1 and a considerable disturbance and denudation of the older formation before the newer beds come on4 #a ,see 8,principles of ,geology10 #ahfg1 p4 #cad4 #b ,edin4 ,trans41 vol4 vii1 pl4 #c4 #c ,proceedings of ,geol4 ,soc41 vol4 iii1 p4 #adh4 #d ,thurmann1 8,essai sur les ,soulvemens ,jurassiques de ,porrentruy10 ,paris1 #ahcb4 #e ,i am indebted to the kindness of ,t4 ,sopwith1 ,esq41 for three models which ,i have copied in the above diagrams2 but the beginner may find it by no means easy to understand such copies1 although1 if he were to examine and handle the originals1 turning them about in different ways1 he would at once comprehend their meaning1 as well as the import of others far more complicated1 which the same engineer has constructed to illustrate faults4 #f ,edward ,hull1 ,quart4 ,geol4 ,journ41 vol4 xxiv1 p4 #cbd1 #ahfh4 #g ,playfair1 ,illust4 of ,hutt4 ,theory1 #db4 #h ,geol4 ,trans41 second series4 vol4 v1 p4 #deb4 #i ,conybeare and ,phillips ,outlines1 etc41 p4 #cgf4 #aj ,phillips1 ,geology1 ,lardner's ,cyclop41 p4 #da4 #aa ,see ,mammatt's ,geological ,facts1 etc41 p4 #ij and plate4 #ab ,hull1 ,quart4 ,geol4 ,journ41 vol4 xxiv1 p4 #cah1 #ahfh4 #ac ,h4 ,d4 ,rogers1 ,geol4 of ,pennsylvania1 p4 #hig4 #ad ,edward ,hull1 ,quart4 ,geol4 ,journ41 vol4 xxiv1 p4 #cbc4 ,,chapter ,,vi4 ,,denudation ,denudation defined4 -- ,its ,amount more than equal to the entire ,mass of ,stratified ,deposits in the ,earth's ,crust4 -- ,subarial ,denudation4 -- ,action of the ,wind4 -- ,action of ,running ,water4 -- ,alluvium defined4 -- ,different ,ages of ,alluvium4 -- ,denuding ,power of ,rivers affected by ,rise or ,fall of ,land4 -- ,littoral ,denudation4 -- ,inland ,sea-,cliffs4 -- ,escarpments4 -- ,submarine ,denudation4 -- ,dogger-bank4 -- ,newfoundland ,bank4 -- ,denuding ,power of the ,ocean during ,emergence of ,land4 ,denudation1 which has been occasionally spoken of in the preceding chapters1 is the removal of solid matter by water in motion1 whether of rivers or of the waves and currents of the sea1 and the consequent laying bare of some inferior rock4 ,this operation has exerted an influence on the structure of the earth's crust as universal and important as sedimentary deposition itself2 for denudation is the necessary antecedent of the production of all new strata of mechanical origin4 ,the formation of every new deposit by the transport of sediment and pebbles necessarily implies that there has been1 somewhere else1 a grinding down of rock into rounded fragments1 sand1 or mud1 equal in quantity to the new strata4 ,all deposition1 therefore1 except in the case of a shower of volcanic ashes1 and the outflow of lava1 and the growth of certain organic formations1 is the sign of superficial waste going on contemporaneously1 and to an equal amount1 elsewhere4 ,the gain at one point is no more than sufficient to balance the loss at some other4 ,here a lake has grown shallower1 there a ravine has been deepened4 ,here the depth of the sea has been augmented by the removal of a sandbank during a storm1 there its bottom has been raised and shallowed by the accumulation in its bed of the same sand transported from the bank4 ,when we see a stone building1 we know that somewhere1 far or near1 a quarry has been opened4 ,the courses of stone in the building may be compared to successive strata1 the quarry to a ravine or valley which has suffered denudation4 ,as the strata1 like the courses of hewn stone1 have been laid one upon another gradually1 so the excavation both of the valley and quarry have been gradual4 ,to pursue the comparison still farther1 the superficial heaps of mud1 sand1 and gravel1 usually called alluvium1 may be likened to the rubbish of a quarry which has been rejected as useless by the workmen1 or has fallen upon the road between the quarry and the building1 so as to lie scattered at random over the ground4 ,but we occasionally find in a conglomerate large rounded pebbles of an older conglomerate1 which had previously been derived from a variety of different rocks4 ,in such cases we are reminded that1 the same materials having been used over and over again1 it is not enough to affirm that the entire mass of stratified deposits in the earth's crust affords a monument and measure of the denudation which has taken place1 for in truth the quantity of matter now extant in the form of stratified rock represents but a fraction of the material removed by water and redeposited in past ages4 ,subarial ,denudation4--,denudation may be divided into subarial1 or the action of wind1 rain1 and rivers2 and submarine1 or that effected by the waves of the sea1 and its tides and currents4 ,with the operation of the first of these we are best acquainted1 and it may be well to give it our first attention4 ,action of the ,wind4--,in desert regions where no rain falls1 or where1 as in parts of the ,sahara1 the soil is so salt as to be without any covering of vegetation1 clouds of dust and sand attest the power of the wind to cause the shifting of the unconsolidated or disintegrated rock4 ,in examining volcanic countries ,i have been much struck with the great superficial changes brought about by this power in the course of centuries4 ,the highest peak of ,madeira is about #fjej feet above the sea1 and consists of the skeleton of a volcanic cone now #bej feet high1 the beds of which once dipped from a centre in all directions at an angle of more than #cj4 ,the summit is formed of a dike of basalt with much olivine1 fifteen feet wide1 apparently the remains of a column of lava which once rose to the crater4 ,nearly all the scori of the upper part of the cone have been swept away1 those portions only remaining which were hardened by the contact or proximity of the dike4 ,while ,i was myself on this peak on ,january #be1 #ahed1 ,i saw the wind1 though it was not stormy weather1 removing sand and dust derived from the decomposing scori4 ,there had been frost in the night1 and some ice was still seen in the crevices of the rock4 ,on the highest platform of the ,grand ,canary1 at an elevation of #fjjj feet1 there is a cylindrical column of hard lava1 from which the softer matter has been carried away2 and other similar remnants of the dikes of cones of eruption attest the denuding power of the wind at points where running water could never have exerted any influence4 ,the waste effected by wind aided by frost and snow1 may not be trifling1 even in a single winter1 and when multiplied by centuries may become indefinitely great4 ,fig4 #hj3 ,section through several eroded formations4 ,action of ,running ,water4--,there are different classes of phenomena which attest in a most striking manner the vast spaces left vacant by the erosive power of water4 ,i may allude1 first1 to those valleys on both sides of which the same strata are seen following each other in the same order1 and having the same mineral composition and fossil contents4 ,we may observe1 for example1 several formations1 as ,nos4 #a1 #b1 #c1 #d1 in the diagram 7,fig4 #hj73 ,no4 #a1 conglomerate1 ,no4 #b1 clay1 ,no4 #c1 grit1 and ,no4 #d1 limestone1 each repeated in a series of hills separated by valleys varying in depth4 ,when we examine the subordinate parts of these four formations1 we find1 in like manner1 distinct beds in each1 corresponding1 on the opposite sides of the valleys1 both in composition and order of position4 ,no one can doubt that the strata were originally continuous1 and that some cause has swept away the portions which once connected the whole series4 ,a torrent on the side of a mountain produces similar interruptions2 and when we make artificial cuts in lowering roads1 we expose1 in like manner1 corresponding beds on either side4 ,but in nature1 these appearances occur in mountains several thousand feet high1 and separated by intervals of many miles or leagues in extent4 ,in the 8,memoirs of the ,geological ,survey of ,great ,britain0 7vol4 i71 ,professor ,ramsay has shown that the missing beds1 removed from the summit of the ,mendips1 must have been nearly a mile in thickness2 and he has pointed out considerable areas in ,south ,wales and some of the adjacent counties of ,england1 where a series of primary 7or palozoic7 strata1 no less than #aa1jjj feet in thickness1 have been stripped off4 ,all these materials have of course been transported to new regions1 and have entered into the composition of more modern formations4 ,on the other hand1 it is shown by observations in the same 8,survey10 that the ,palozoic strata are from #bj1jjj to #cj1jjj feet thick4 ,it is clear that such rocks1 formed of mud and sand1 now for the most part consolidated1 are the monuments of denuding operations1 which took place on a grand scale at a very remote period in the earth's history4 ,for1 whatever has been given to one area must always have been borrowed from another2 a truth which1 obvious as it may seem when thus stated1 must be repeatedly impressed on the student's mind1 because in many geological speculations it is taken for granted that the external crust of the earth has been always growing thicker in consequence of the accumulation1 period after period1 of sedimentary matter1 as if the new strata were not always produced at the expense of pre-existing rocks1 stratified or unstratified4 ,by duly reflecting on the fact that all deposits of mechanical origin imply the transportation from some other region1 whether contiguous or remote1 of an equal amount of solid matter1 we perceive that the stony exterior of the planet must always have grown thinner in one place1 whenever1 by accessions of new strata1 it was acquiring thickness in another4 ,it is well known that generally at the mouths of large rivers1 deltas are forming and the land is encroaching upon the sea2 these deltas are monuments of recent denudation and deposition2 and it is obvious that if the mud1 sand1 and gravel were taken from them and restored to the continents they would fill up a large part of the gullies and valleys which are due to the excavating and transporting power of torrents and rivers4 ,alluvium4--,between the superficial covering of vegetable mould and the subjacent rock there usually intervenes in every district a deposit of loose gravel1 sand1 and mud1 to which when it occurs in valleys the name of alluvium has been popularly applied4 ,the term is derived from alluvio1 an inundation1 or alluo1 to wash1 because the pebbles and sand commonly resemble those of a river's bed or the mud and gravel washed over low lands by a flood4 ,in the course of those changes in physical geography which may take place during the gradual emergence of the bottom of the sea and its conversion into dry land1 any spot may either have been a sunken reef1 or a bay1 or estuary1 or sea-shore1 or the bed of a river4 ,the drainage1 moreover1 may have been deranged again and again by earthquakes1 during which temporary lakes are caused by landslips1 and partial deluges occasioned by the bursting of the barriers of such lakes4 ,for this reason it would be unreasonable to hope that we should ever be able to account for all the alluvial phenomena of each particular country1 seeing that the causes of their origin are so various4 ,besides1 the last operations of water have a tendency to disturb and confound together all pre-existing alluviums4 ,hence we are always in danger of regarding as the work of a single era1 and the effect of one cause1 what has in reality been the result of a variety of distinct agents1 during a long succession of geological epochs4 ,much useful instruction may therefore be gained from the exploration of a country like ,auvergne1 where the superficial gravel of very different eras happens to have been preserved and kept separate by sheets of lava1 which were poured out one after the other at periods when the denudation1 and probably the upheaval1 of rocks were in progress4 ,that region had already acquired in some degree its present configuration before any volcanoes were in activity1 and before any igneous matter was superimposed upon the granitic and fossiliferous formations4 ,the pebbles therefore in the older gravels are exclusively constituted of granite and other aboriginal rocks2 and afterwards1 when volcanic vents burst forth into eruption1 those earlier alluviums were covered by streams of lava1 which protected them from intermixture with gravel of subsequent date4 ,in the course of ages1 a new system of valleys was excavated1 so that the rivers ran at lower levels than those at which the first alluviums and sheets of lava were formed4 ,when1 therefore1 fresh eruptions gave rise to new lava1 the melted matter was poured out over lower grounds2 and the gravel of these plains differed from the first or upland alluvium1 by containing in it rounded fragments of various volcanic rocks1 and often fossil bones belonging to species of land animals different from those which had previously flourished in the same country and been buried in older gravels4 ,fig4 #ha3 ,lavas of ,auvergne resting on alluviums of different ages4 ,the annexed drawing 7,fig4 #ha7 will explain the different heights at which beds of lava and gravel1 each distinct from the other in composition and age1 are observed1 some on the flat tops of hills1 #gjj or #hjj feet high1 others on the slope of the same hills1 and the newest of all in the channel of the existing river where there is usually gravel alone1 although in some cases a narrow strip of solid lava shares the bottom of the valley with the river4 ,the proportion of extinct species of quadrupeds is more numerous in the fossil remains of the gravel ,no4 #a than in that indicated as ,no4 #b2 and in ,no4 #c they agree more closely1 sometimes entirely1 with those of the existing fauna4 ,the usual absence or rarity of organic remains in beds of loose gravel and sand is partly owing to the friction which originally ground down the rocks into small fragments1 and partly to the porous nature of alluvium1 which allows the free percolation through it of rain-water1 and promotes the decomposition and removal of fossil remains4 ,the loose transported matter on the surface of a large part of the land now existing in the temperate and arctic regions of the northern hemisphere1 must be regarded as being in a somewhat exceptional state1 in consequence of the important part which ice has played in comparatively modern geological times4 ,this subject will be more specially alluded to when we describe1 in the eleventh chapter1 the deposits called 8glacial40 ,denuding ,power of ,rivers affected by ,rise or ,fall of ,land4--,it has long been a matter of common observation that most rivers are now cutting their channels through alluvial deposits of greater depth and extent than could ever have been formed by the present streams4 ,from this fact it has been inferred that rivers in general have grown smaller1 or become less liable to be flooded than formerly4 ,it may be true that in the history of almost every country the rivers have been both larger and smaller than they are at the present moment4 ,for the rainfall in particular regions varies according to climate and physical geography1 and is especially governed by the elevation of the land above the sea1 or its distance from it and other conditions equally fluctuating in the course of time4 ,but the phenomenon alluded to may sometimes be accounted for by oscillations in the level of the land1 experienced since the existing valleys originated1 even where no marked diminution in the quantity of rain and in the size of the rivers has occurred4 ,we know that many large areas of land are rising and others sinking1 and unless it could be assumed that both the upward and downward movements are everywhere uniform1 many of the existing hydrographical basins ought to have the appearance of having been temporary lakes first filled with fluviatile strata and then partially re-excavated4 ,suppose1 for example1 part of a continent1 comprising within it a large hydrographical basin like that of the ,mississippi1 to subside several inches or feet in a century1 as the west coast of ,greenland1 extending #fjj miles north and south1 has been sinking for three or four centuries1 between the latitudes #fj and #fi ,n4#a ,it will rarely happen that the rate of subsidence will be everywhere equal1 and in many cases the amount of depression in the interior will regularly exceed that of the region nearer the sea4 ,whenever this happens1 the fall of the waters flowing from the upland country will be diminished1 and each tributary stream will have less power to carry its sand and sediment into the main river1 and the main river less power to convey its annual burden of transported matter to the sea4 ,all the rivers1 therefore1 will proceed to fill up partially their ancient channels1 and1 during frequent inundations1 will raise their alluvial plains by new deposits4 ,if then the same area of land be again upheaved to its former height1 the fall1 and consequently the velocity1 of every river will begin to augment4 ,each of them will be less given to overflow its alluvial plain2 and their power of carrying earthy matter seaward1 and of scouring out and deepening their channels1 will be sustained till1 after a lapse of many thousand years1 each of them has eroded a new channel or valley through a fluviatile formation of comparatively modern date4 ,the surface of what was once the river-plain at the period of greatest depression1 will then remain fringing the valley-sides in the form of a terrace apparently flat1 but in reality sloping down with the general inclination of the river4 ,everywhere this terrace will present cliffs of gravel and sand1 facing the river4 ,that such a series of movements has actually taken place in the main valley of the ,mississippi and in its tributary valleys during oscillations of level1 ,i have endeavoured to show in my description of that country2#b and the fresh-water shells of existing species and bones of land quadrupeds1 partly of extinct races1 preserved in the terraces of fluviatile origin1 attest the exclusion of the sea during the whole process of filling up and partial re-excavation4 ,littoral ,denudation4--,part of the action of the waves between high and low watermark must be included in subarial denudation1 more especially as the undermining of cliffs by the waves is facilitated by land-springs1 and these often lead to the sliding down of great masses of land into the sea4 ,along our coasts we find numerous submerged forests1 only visible at low water1 having the trunks of the trees erect and their roots attached to them and still spreading through the ancient soil as when they were living4 ,they occur in too many places1 and sometimes at too great a depth1 to be explained by a mere change in the level of the tides1 although as the coasts waste away and alter in shape1 the height to which the tides rise and fall is always varying1 and the level of high tide at any given point may1 in the course of many ages1 differ by several feet or even fathoms4 ,it is this fluctuation in the height of the tides1 and the erosion and destruction of the sea-coast by the waves1 that makes it exceedingly difficult for us in a few centuries1 or even perhaps in a few thousand years1 to determine whether there is a change by subterranean movement in the relative level of sea and land4 ,we often behold1 as on the coasts of ,devonshire and ,pembrokeshire1 facts which appear to lead to opposite conclusions4 ,in one place a raised beach with marine littoral shells1 and in another immediately adjoining a submerged forest4 ,these phenomena indicate oscillations of level1 and as the movements are very gradual1 they must give repeated opportunities to the breakers to denude the land which is thus again and again exposed to their fury1 although it is evident that the submergence is sometimes effected in such a manner as to allow the trees which border the coast not to be carried away4 ,inland ,sea-cliffs4--,in countries where hard limestone rocks abound1 inland cliffs have often retained faithfully for ages the characters which they acquired when they constituted the boundary of land and sea4 ,thus1 in the ,morea1 no less than three or even four ranges of cliffs are well-preserved1 rising one above the other at different distances from the actual shore1 the summit of the highest and oldest occasionally attaining #ajjj feet in elevation4 ,a consolidated beach with marine shells is usually found at the base of each cliff1 and a line of littoral caverns4 ,these ranges of cliff probably imply pauses in the process of upheaval when the waves and currents had time to undermine and clear away considerable masses of rock4 ,but the beginner should be warned not to expect to find evidence of the former sojourn of the sea on all those lands which we are nevertheless sure have been submerged at periods comparatively modern2 for notwithstanding the enduring nature of the marks left by littoral action on some rocks1 especially limestones1 we can by no means detect sea-beaches and inland cliffs everywhere4 ,on the contrary1 they are1 upon the whole1 extremely partial1 and are often entirely wanting in districts composed of argillaceous and sandy formations1 which must1 nevertheless1 have been upheaved at the same time1 and by the same intermittent movements1 as the adjoining harder rocks4 ,escarpments4--,besides the inland cliffs above alluded to which mark the ancient limits of the sea1 there are other abrupt terminations of rocks of various kinds which resemble sea-cliffs1 but which have in reality been due to subarial denudation4 ,these have been called 8escarpments10 a term which it is useful to confine to the outcrop of particular formations having a scarped outline1 as distinct from cliffs due to marine action4 ,i formerly supposed that the steep line of cliff-like slopes seen along the outcrop of the chalk1 when we follow the edge of the ,north or ,south ,downs1 was due to marine action2 but ,professor ,ramsay has shown#c that the present outline of the physical geography is more in favour of the idea of the escarpments having been due to gradual waste since the rocks were exposed in the atmosphere to the action of rain and rivers4 ,mr4 ,whittaker has given a good summary of the grounds for ascribing these apparent sea-cliffs to waste in the open air4 #a4 ,there is an absence of all signs of ancient sea-beaches or littoral deposits at the base of the escarpment4 #b4 ,great inequality is observed in the level of the base line4 #c4 ,the escarpments do not intersect1 like sea-cliffs1 a series of distinct rocks1 but are always confined to the boundary-line of the same formation4 #d4 ,there are sometimes different contiguous and parallel escarpments--those1 for example1 of the greensand and chalk--which are so near each other1 and occasionally so similar in altitude1 that we cannot imagine any existing archipelago if converted into dry land to present a like outline4 ,the above theory is by no means inconsistent with the opinion that the limits of the outcrop of the chalk and greensand which the escarpments now follow1 were originally determined by marine denudation4 ,when the south-east of ,england last emerged from beneath the level of the sea1 it was acted upon1 no doubt1 by the tide1 waves1 and currents1 and the chalk would form from the first a mass projecting above the more destructible clay called ,gault4 ,still the present escarpments so much resembling sea-cliffs have no doubt1 for reasons above stated1 derived their most characteristic features subsequently to emergence from subarial waste by rain and rivers4 ,submarine ,denudation4--,when we attempt to estimate the amount of submarine denudation1 we become sensible of the disadvantage under which we labour from our habitual incapacity of observing the action of marine currents on the bed of the sea4 ,we know that the agitation of the waves1 even during storms1 diminishes at a rapid rate1 so as to become very insignificant at the depth of a few fathoms1 and is quite imperceptible at the depth of about sixteen fathoms2 but when large bodies of water are transferred by a current from one part of the ocean to another1 they are known to maintain at great depths such a velocity as must enable them to remove the finer1 and sometimes even the coarser1 materials of the rocks over which they flow4 ,as the ,mississippi when more than #aej feet deep can keep open its channel and even carry down gravel and sand to its delta1 the surface velocity being not more than two or three miles an hour1 so a gigantic current1 like the ,gulf ,stream1 equal in volume to many hundred ,mississippis1 and having in parts a surface velocity of more than three miles1 may act as a propelling and abrading power at still greater depths4 ,but the efficacy of the sea as a denuding agent1 geologically considered1 is not dependent on the power of currents to preserve at great depths a velocity sufficient to remove sand and mud1 because1 even where the deposition or removal of sediment is not in progress1 the depth of water does not remain constant throughout geological time4 ,every page of the geological record proves to us that the relative levels of land and sea1 and the position of the ocean and of continents and islands1 has been always varying1 and we may feel sure that some portions of the submarine area are now rising and others sinking4 ,the force of tidal and other currents and of the waves during storms is sufficient to prevent the emergence of many lands1 even though they may be undergoing continual upheaval4 ,it is not an uncommon error to imagine that the waste of sea-cliffs affords the measure of the amount of marine denudation of which it probably constitutes an insignificant portion4 ,dogger-bank4--,that great shoal called the ,dogger-bank1 about sixty miles east of the coast of ,northumberland1 and occupying an area about as large as ,wales1 has nowhere a depth of more than ninety feet1 and in its shallower parts is less than forty feet under water4 ,it might contribute towards the safety of the navigation of our seas to form an artificial island1 and to erect a light-house on this bank2 but no engineer would be rash enough to attempt it1 as he would feel sure that the ocean in the first heavy gale would sweep it away as readily as it does every temporary shoal that accumulates from time to time around a sunk vessel on the same bank4#d ,no observed geographical changes in historical times entitle us to assume that where upheaval may be in progress it proceeds at a rapid rate4 ,three or four feet rather than as many yards in a century may probably be as much as we can reckon upon in our speculations2 and if such be the case1 the continuance of the upward movement might easily be counteracted by the denuding force of such currents aided by such waves as1 during a gale1 are known to prevail in the ,german ,ocean4 ,what parts of the bed of the ocean are stationary at present1 and what areas may be rising or sinking1 is a matter of which we are very ignorant1 as the taking of accurate soundings is but of recent date4 ,newfoundland ,bank4--,the great bank of ,newfoundland may be compared in size to the whole of ,england4 ,this part of the bottom of the ,atlantic is surrounded on three sides by a rapidly deepening ocean1 the bank itself being from twenty to fifty fathoms 7or from #abj to #cjj feet7 under water4 ,we are unable to determine by the comparison of different charts made at distant periods1 whether it is undergoing any change of level1 but if it be gradually rising we cannot anticipate on that account that it will become land1 because the breakers in an open sea would exercise a prodigious force even on solid rock brought up to within a few yards of the surface4 ,we know1 for example1 that when a new volcanic island rose in the ,mediterranean in #ahca1 the waves were capable in a few years of reducing it to a sunken rock4 ,in the same way currents which flow over the ,newfoundland bank a great part of the year at the rate of two miles an hour1 and are known to retain a considerable velocity to near the bottom1 may carry away all loose sand and mud1 and make the emergence of the shoal impossible1 in spite of the accessions of mud1 sand1 and boulders derived occasionally from melting icebergs which1 coming from the northern glaciers1 are frequently stranded on various parts of the bank4 ,they must often leave at the bottom large erratic blocks which the marine currents may be incapable of moving1 but the same rocky fragments may be made to sink by the undermining of beds consisting of finer matter on which the blocks and gravel repose4 ,in this way gravel and boulders may continue to overspread a submarine bottom after the latter has been lowered for hundreds of feet1 the surface never having been able to emerge and become land4 ,it is by no means improbable that the annual removal of an average thickness of half an inch of rock might counteract the ordinary upheaval which large submarine areas are undergoing2 and the real enigma which the geologist has to solve is not the extensive denudation of the white chalk or of our tertiary sands and clays1 but the fact that such incoherent materials have ever succeeded in lifting up their heads above water in an open sea4 ,why were they not swept away during storms into some adjoining abysses1 the highest parts of each shoal being always planed off down to the depth of a few fathoms8 ,the hardness and toughness of some rocks already exposed to windward and acting as breakwaters may perhaps have assisted2 nor must we forget the protection afforded by a dense and unbroken covering of barnacles1 limpets1 and other creatures which flourish most between high and low water and shelter some newly risen coasts from the waves4 #a ,principles of ,geology #gth ed41 p4 #ejf2 #ajth ed41 vol4 ii1 p4 #aif4 #b ,second ,visit to the ,united ,states1 vol4 i1 chap4 xxxiv4 #c ,physical ,geography and ,geology of ,great ,britain1 p4 #gh1 #ahfd4 #d ,principles1 #ajth ed41 vol4 i1 p4 #efi4 ,,chapter ,,vii4 ,,joint ,,action ,,of ,,denudation1 ,,upheaval1 ,,and ,,subsidence ,,in ,,remodelling ,,the ,,earth',s ,,crust4 ,how we obtain an ,insight at the ,surface1 of the ,arrangement of ,rocks at great ,depths4 -- ,why the ,height of the successive ,strata in a given ,region is so disproportionate to their ,thickness4 -- ,computation of the average annual ,amount of subarial ,denudation4 -- ,antagonism of ,volcanic ,force to the ,levelling ,power of running ,water4 -- ,how far the ,transfer of ,sediment from the ,land to a neighbouring ,sea-bottom may affect ,subterranean ,movements4 -- ,permanence of ,continental and ,oceanic ,areas4 ,how we obtain an ,insight at the ,surface1 of the ,arrangement of ,rocks at ,great ,depths4-- ,the reader has been already informed that1 in the structure of the earth's crust1 we often find proofs of the direct superposition of marine to fresh-water strata1 and also evidence of the alternation of deep-sea and shallow-water formations4 ,in order to explain how such a series of rocks could be made to form our present continents and islands1 we have not only to assume that there have been alternate upward and downward movements of great vertical extent1 but that the upheaval in the areas which we at present inhabit has1 in later geological times1 sufficiently predominated over subsidence to cause these portions of the earth's crust to be land instead of sea4 ,the sinking down of a delta beneath the sea-level may cause strata of fluviatile or even terrestrial origin1 such as peat with trees proper to marshes1 to be covered by deposits of deep-sea origin4 ,there is also no end to the thickness of mud and sand which may accumulate in shallow water1 provided that fresh sediment is brought down from the wasting land at a rate corresponding to that of the sinking of the bed of the sea4 ,the latter1 again1 may sometimes sink so fast that the earthy matter1 being intercepted in some new landward depression1 may never reach its former resting-place1 where1 the water becoming clear may favour the growth of shells and corals1 and calcareous rocks of organic origin may thus be superimposed on mechanical deposits4 ,the succession of strata here alluded to would be consistent with the occurrence of gradual downward and upward movements of the land and bed of the sea without any disturbance of the horizontality of the several formations4 ,but the arrangement of rocks composing the earth's crust differs materially from that which would result from a mere series of vertical movements4 ,had the volcanic forces been confined to such movements1 and had the stratified rocks been first formed beneath the sea and then raised above it1 without any lateral compression1 the geologist would never have obtained an insight into the monuments of various ages1 some of extremely remote antiquity4 ,what we have said in ,chapter ,v of dip and strike1 of the folding and inversion of strata1 of anticlinal and synclinal flexures1 and in ,chapter ,,vi of denudation at different periods1 whether subarial or submarine1 must be understood before the student can comprehend what may at first seem to him an anomaly1 but which it is his business particularly to understand4 ,i allude to the small height above the level of the sea attained by strata often many miles in thickness1 and about the chronological succession of which1 in one and the same region1 there is no doubt whatever4 ,had stratified rocks in general remained horizontal1 the waves of the sea would have been enabled during oscillations of level to plane off entirely the uppermost beds as they rose or sank during the emergence or submergence of the land4 ,but the occurrence of a series of formations of widely different ages1 all remaining horizontal and in conformable stratification1 is exceptional1 and for this reason the total annihilation of the uppermost strata has rarely taken place4 ,we owe1 indeed1 to the side way movements of lateral compression those anticlinal and synclinal curves of the beds already described 7,fig4 #ee71 which1 together with denudation1 subarial and submarine1 enable us to investigate the structure of the earth's crust many miles below those points which the miner can reach4 ,i have already shown in ,fig4 #ef1 how1 at ,st4 ,abb's ,head1 a series of strata of indefinite thickness may become vertical1 and then denuded1 so that the edges of the beds alone shall be exposed to view1 the altitude of the upheaved ridges being reduced to a moderate height above the sea-level2 and it may be observed that although the incumbent strata of ,old ,red ,sandstone are in that place nearly horizontal1 yet these same newer beds will in other places be found so folded as to present vertical strata1 the edges of which are abruptly cut off1 as in #b1 #c1 #d on the right-hand side of the diagram1 ,fig4 #ee4 ,why the ,height of the ,successive ,strata in a given ,region is so ,disproportionate to their ,thickness4--,we cannot too distinctly bear in mind how dependent we are on the joint action of the volcanic and aqueous forces1 the one in disturbing the original position of rocks1 and the other in destroying large portions of them1 for our power of consulting the different pages and volumes of those stony records of which the crust of the globe is composed4 ,why1 it may be asked1 if the ancient bed of the sea has been in many regions uplifted to the height of two or three miles1 and sometimes twice that altitude1 and if it can be proved that some single formations are of themselves two or three miles thick1 do we so often find several important groups resting one upon the other1 yet attaining only the height of a few hundred feet above the level of the sea8 ,the ,american geologists1 after carefully studying the ,allegheny or ,appalachian mountains1 have ascertained that the older fossiliferous rocks of that chain 7from the ,silurian to the ,carboniferous inclusive7 are not less than #db1jjj feet thick1 and if they were now superimposed on each other in the order in which they were thrown down1 they ought to equal in height the ,himalayas with the ,alps piled upon them4 ,yet they rarely reach an altitude of #ejjj feet1 and their loftiest peaks are no more than #gjjj feet high4 ,the ,carboniferous strata forming the highest member of the series1 and containing beds of coal1 can be shown to be of shallow-water origin1 or even sometimes to have originated in swamps in the open air4 ,but what is more surprising1 the lowest part of this great ,palozoic series1 instead of having been thrown down at the bottom of an abyss more than #dj1jjj feet deep1 consists of sediment 7the ,potsdam sandstone71 evidently spread out on the bottom of a shallow sea1 on which ripple-marked sands were occasionally formed4 ,this vast thickness of #dj1jjj feet is not obtained by adding together the maximum density attained by each formation in distant parts of the chain1 but by measuring the successive groups as they are exposed in a very limited area1 and where the denuded edges of the vertical strata forming the parallel folds alluded to at page #hg 8crop out0 at the surface4 ,our attention has been called by ,mr4 ,james ,hall1 ,palontologist of ,new ,york1 to the fact that these ,palozoic rocks of the ,appalachian chain1 which are of such enormous density1 where they are almost entirely of mechanical origin1 thin out gradually as they are traced to the westward1 where evidently the contemporaneous seas allowed organic rocks to be formed by corals1 echinoderms1 and encrinites in clearer water1 and where1 although the same successive periods are represented1 the total mass of strata from the ,silurian to the ,carboniferous1 instead of being #dj1jjj is only #djjj feet thick4 ,a like phenomenon is exhibited in every mountainous country1 as1 for example1 in the ,european ,alps2 but we need not go farther than the north of ,england for its illustration4 ,thus in ,lancashire and central ,england the thickness of the ,carboniferous formation1 including the ,millstone ,grit and ,yoredale beds1 is computed to be more than #ah1jjj feet2 to this we may add the ,mountain ,limestone1 at least #bjjj feet in thickness1 and the overlying ,permian and ,triassic formations1 #cjjj or #djjj feet thick4 ,how then does it happen that the loftiest hills of ,yorkshire and ,lancashire1 instead of being #bd1jjj feet high1 never rise above #cjjj feet8 ,for here1 as before pointed out in the ,alleghenies1 all the great thicknesses are sometimes found in close approximation and in a region only a few miles in diameter4 ,it is true that these same sets of strata do not preserve their full force when followed for indefinite distances4 ,thus the #ah1jjj feet of ,carboniferous grits and shales in ,lancashire1 before alluded to1 gradually thin out1 as ,mr4 ,hull has shown1 as they extend southward1 by attenuation or original deficiency of sediment1 and not in consequence of subsequent denudation1 so that when we have followed them for about #ajj miles into ,leicestershire1 they have dwindled away to a thickness of only #cjjj feet4 ,in the same region the ,carboniferous limestone attains so unusual a thickness--namely1 more than #djjj feet--as to appear to compensate in some measure for the deficiency of contemporaneous sedimentary rock4#a ,it is admitted that when two formations are unconformable their fossil remains almost always differ considerably4 ,the break in the continuity of the organic forms seems connected with a great lapse of time1 and the same interval has allowed extensive disturbance of the strata1 and removal of parts of them by denudation1 to take place4 ,the more we extend our investigations the more numerous do the proofs of these breaks become1 and they extend to the most ancient rocks yet discovered4 ,the oldest examples yet brought to light in the ,british ,isles are on the borders of ,rosshire and ,sutherlandshire1 and have been well described by ,sir ,roderick ,murchison1 by whom their chronological relations were admirably worked out1 and proved to be very different from those which previous observers had imagined them to be4 ,i had an opportunity in the autumn of #ahfi of verifying the splendid section given in ,fig4 #hb by climbing in a few hours from the banks of ,loch ,assynt to the summit of the mountain called ,queenaig1 #bfgc feet high4 ,the formations #a1 #b1 #c1 the ,laurentian1 ,cambrian1 and ,silurian1 to be explained in ,chapters ,,xxv and ,,xxvi1 not only occur in succession in this one mountain1 but their unconformable junctions are distinctly exposed to view4 ,fig4 #hb3 ,unconformable ,palozoic stata1 ,sutherlandshire 7,murchison74 ,to begin with the oldest set of rocks1 ,no4 #a2 they consist chiefly of hornblendic gneiss1 and in the neighbouring ,hebrides form whole islands1 attaining a thickness of thousands of feet1 although they have suffered such contortions and denudation that they seldom rise more than a few hundred feet above the sea-level4 ,in discordant stratification upon the edges of this gneiss reposes ,no4 #b1 a group of conglomerate and purple sandstone referable to the ,cambrian 7or ,longmynd7 formation1 which can elsewhere be shown to be characterised by its peculiar organic remains4 ,on this again rests ,no4 #c1 a lower member of the important group called ,silurian1 an outlier of which1 #c1 caps the summit of ,queenaig1 attesting the removal by denudation of rocks of the same age1 which once extended from the great mass #c to #c4 ,although this rock now consists of solid quartz1 it is clear that in its original state it was formed of fine sand1 perforated by numerous lob-worms or annelids1 which left their burrows in the shape of tubular hollows ,fig4 #efc of ,arenicolites71 hundreds1 nay thousands1 of which ,i saw as ,i ascended the mountain4 ,fig4 #hc3 ,diagrammatic section of the same groups near ,queenaig 7,murchison74 ,in ,queenaig we only behold this single quartzose member of the ,silurian series1 but in the neighbouring country 7see ,fig4 #hc7 it is seen to the eastward to be followed by limestones1 #c;a1 and schists1 #c;b1 presenting numerous folds1 and becoming more and more metamorphic and crystalline1 until at length1 although very different in age and strike1 they much resemble in appearance the group ,no4 #a4 ,it is very seldom that in the same country one continuous formation1 such as the ,silurian1 is1 as in this case1 more fossiliferous and less altered by volcanic heat in its older than in its newer strata1 and still more rare to find an underlying and unconformable group like the ,cambrian retaining its original condition of a conglomerate and sandstone more perfectly than the overlying formation4 ,here also we may remark in regard to the origin of these ,cambrian rocks that they were evidently produced at the expense of the underlying ,laurentian1 for the rounded pebbles occurring in them are identical in composition and texture with that crystalline gneiss which constitutes the contorted beds of the inferior formation ,no4 #a4 ,when the reader has studied the chapter on metamorphism1 and has become aware how much modification by heat1 pressure1 and chemical action is required before the conversion of sedimentary into crystalline strata can be brought about1 he will appreciate the insight which we thus gain into the date of the changes which had already been effected in the ,laurentian rocks long before the ,cambrian pebbles of quartz and gneiss were derived from them4 ,the ,laurentian is estimated by ,sir ,william ,logan to amount in ,canada to #cj1jjj feet in thickness4 ,as to the ,cambrian1 it is supposed by ,sir ,roderick ,murchison that the fragment left in ,sutherlandshire is about #cejj feet thick1 and in ,wales and the borders of ,shropshire this formation may equal #aj1jjj feet1 while the ,silurian strata ,no4 #c1 difficult as it may be to measure them in their various foldings to the eastward1 where they have been invaded by intrusive masses of granite1 are supposed many times to surpass the ,cambrian in volume and density4 ,but although we are dealing here with stratified rocks1 each of which would be several miles in thickness1 if they were fully represented1 the whole of them do not attain the elevation of a single mile above the level of the sea4 ,computation of the ,average ,annual ,amount of ,subarial ,denudation4--,the geology of the district above alluded to may assist our imagination in conceiving the extent to which groups of ancient rocks1 each of which may in their turn have formed continents and oceanic basins1 have been disturbed1 folded1 and denuded even in the course of a few out of many of those geological periods to which our imperfect records relate4 ,it is not easy for us to overestimate the effects which causes in every day action must produce when the multiplying power of time is taken into account4 ,attempts were made by ,manfredi in #agcf1 and afterwards by ,playfair in #ahjb1 to calculate the time which it would require to enable the rivers to deliver over the whole of the land into the basin of the ocean4 ,the data were at first too imperfect and vague to allow them even to approximate to safe conclusions4 ,but in our own time similar investigations have been renewed with more prospect of success1 the amount brought down by many large rivers to the sea having been more accurately ascertained4 ,mr4 ,alfred ,tylor1 in #ahej1 inferred that the quantity of detritus now being distributed over the sea-bottom would1 at the end of #aj1jjj years1 cause an elevation of the sea-level to the extent of at least three inches4#b ,subsequently ,mr4 ,croll1 in #ahfg1 and again1 with more exactness1 in #ahfh1 deduced from the latest measurement of the sediment transported by ,european and ,american rivers the rate of subarial denudation to which the surface of large continents is exposed1 taking especially the hydrographical basin of the ,mississippi as affording the best available measure of the average waste of the land4 ,the conclusion arrived at in his able memoir1#c was that the whole terrestrial surface is denuded at the rate of one foot in #fjjj years and this opinion was simultaneously enforced by his fellow-labourer1 ,mr4 ,geikie1 who1 being jointly engaged in the same line of inquiry1 published a luminous essay on the subject in #ahfh4 ,the student1 by referring to my 8,principles of ,geology10#d may see that ,messrs4 ,humphrey and ,abbot1 during their survey of the ,mississippi1 attempted to make accurate measurements of the proportion of sediment carried down annually to the sea by that river1 including not only the mud held in suspension1 but also the sand and gravel forced along the bottom4 ,it is evident that when we know the dimensions of the area which is drained1 and the annual quantity of earthy matter taken from it and borne into the sea1 we can affirm how much on an average has been removed from the general surface in one year1 and there seems no danger of our overrating the mean rate of waste by selecting the ,mississippi as our example1 for that river drains a country equal to more than half the continent of ,europe1 extends through twenty degrees of latitude1 and therefore through regions enjoying a great variety of climate1 and some of its tributaries descend from mountains of great height4 ,the ,mississippi is also more likely to afford us a fair test of ordinary denudation1 because1 unlike the ,st4 ,lawrence and its tributaries1 there are no great lakes in which the fluviatile sediment is thrown down and arrested in its way to the sea4 ,in striking a general average we have to remember that there are large deserts in which there is scarcely any rainfall1 and tracts which are as rainless as parts of ,peru1 and these must not be neglected as counterbalancing others1 in the tropics1 where the quantity of rain is in excess4 ,if then1 argues ,mr4 ,geikie1 we assume that the ,mississippi is lowering the surface of the great basin which it drains at the rate of one foot in #fjjj years1 #aj feet in #fj1jjj years1 #ajj feet in #fjj1jjj years1 and #ajjj feet in #f1jjj1jjj years1 it would not require more than about #d1ejj1jjj years to wear away the whole of the ,north ,american continent if its mean height is correctly estimated by ,humboldt at #gdh feet4 ,and if the mean height of all the land now above the sea throughout the globe is #ajjj feet1 as some geographers believe1 it would only require six million years to subject a mass of rock equal in volume to the whole of the land to the action of subarial denudation4 ,it may be objected that the annual waste is partial1 and not equally derived from the general surface of the country1 inasmuch as plains1 water-sheds1 and level ground at all heights remain comparatively unaltered2 but this1 as ,mr4 ,geikie has well pointed out1 does not affect our estimate of the sum total of denudation4 ,the amount remains the same1 and if we allow too little for the loss from the surface of table-lands we only increase the proportion of the loss sustained by the sides and bottoms of the valleys1 and vice versa4#e ,antagonism of ,volcanic ,force to the ,levelling ,power of ,running ,water4--,in all these estimates it is assumed that the entire quantity of land above the sea-level remains on an average undiminished in spite of annual waste4 ,were it otherwise the subarial denudation would be continually lessened by the diminution of the height and dimensions of the land exposed to waste4 ,unfortunately we have as yet no accurate data enabling us to measure the action of that force by which the inequalities of the surface of the earth's crust may be restored1 and the height of the continents and depth of the seas made to continue unimpaired4 ,i stated in #ahcj in the 8,principles of ,geology10#f that running water and volcanic action are two antagonistic forces2 the one labouring continually to reduce the whole of the land to the level of the sea1 the other to restore and maintain the inequalities of the crust on which the very existence of islands and continents depends4 ,i stated1 however1 that when we endeavour to form some idea of the relation of these destroying and renovating forces1 we must always bear in mind that it is not simply by upheaval that subterranean movements can counteract the levelling force of running water4 ,for whereas the transportation of sediment from the land to the ocean would raise the general sea-level1 the subsidence of the sea-bottom1 by increasing its capacity1 would check this rise and prevent the submergence of the land4 ,i have1 indeed1 endeavoured to show that unless we assume that there is1 on the whole1 more subsidence than upheaval1 we must suppose the diameter of the planet to be always increasing1 by that quantity of volcanic matter which is annually poured out in the shape of lava or ashes1 whether on the land or in the bed of the sea1 and which is derived from the interior of the earth4 ,the abstraction of this matter causes1 no doubt1 subterranean vacuities and a corresponding giving way of the surface2 if it were not so1 the average density of parts of the interior would be always lessening and the size of the planet increasing4#g ,our inability to estimate the amount or direction of the movements due to volcanic power by no means renders its efficacy as a land-preserving force in past times a mere matter of conjecture4 ,the student will see in ,chapter ,,xxiv that we have proofs of ,carboniferous forests hundreds of miles in extent which grew on the lowlands or deltas near the sea1 and which subsided and gave place to other forests1 until in some regions fluviatile and shallow-water strata with occasional seams of coal were piled one over the other1 till they attained a thickness of many thousand feet4 ,such accumulations1 observed in ,great ,britain and ,america on opposite sides of the ,atlantic1 imply the long-continued existence of land vegetation1 and of rivers draining a former continent placed where there is now deep sea4 ,it will be also seen in ,chapter ,,xxv that we have evidence of a rich terrestrial flora1 the ,devonian1 even more ancient than the ,carboniferous2 while on the other hand1 the later ,triassic1 ,oolitic1 ,cretaceous1 and successive ,tertiary periods have all supplied us with fossil plants1 insects1 or terrestrial mammalia2 showing that1 in spite of great oscillations of level and continued changes in the position of land and sea1 the volcanic forces have maintained a due proportion of dry land4 ,we may appeal also to fresh-water formations1 such as the ,purbeck and ,wealden1 to prove that in the ,oolitic and ,neocomian eras there were rivers draining ancient lands in ,europe in times when we know that other spaces1 now above water1 were submerged4 ,how far the ,transfer of ,sediment from the ,land to a ,neighbouring ,sea-bottom may affect ,subterranean ,movements4--,little as we understand at present the laws which govern the distribution of volcanic heat in the interior and crust of the globe1 by which mountain chains1 high table-lands1 and the abysses of the ocean are formed1 it seems clear that this heat is the prime mover on which all the grander features in the external configuration of the planet depend4 ,it has been suggested that the stripping off by denudation of dense masses from one part of a continent and the delivery of the same into the bed of the ocean must have a decided effect in causing changes of temperature in the earth's crust below1 or1 in other words1 in causing the subterranean isothermals to shift their position4 ,if this be so1 one part of the crust may be made to rise1 and another to sink1 by the expansion and contraction of the rocks1 of which the temperature is altered4 ,i cannot1 at present1 discuss this subject1 of which ,i have treated more fully elsewhere1#h but may state here that ,i believe this transfer of sediment to play a very subordinate part in modifying those movements on which the configuration of the earth's crust depends4 ,in order that strata of shallow-water origin should be able to attain a thickness of several thousand feet1 and so come to exert a considerable downward pressure1 there must have been first some independent and antecedent causes at work which have given rise to the incipient shallow receptacle in which the sediment began to accumulate4 ,the same causes there continuing to depress the sea-bottom1 room would be made for fresh accessions of sediment1 and it would only be by a long repetition of the depositing process that the new matter could acquire weight enough to affect the temperature of the rocks far below1 so as to increase or diminish their volume4 ,permanence of ,continental and ,oceanic ,areas4--,if the thickness of more than #dj1jjj feet of sedimentary strata before alluded to in the ,appalachians proves a preponderance of downward movements in ,palozoic times in a district now forming the eastern border of ,north ,america1 it also proves1 as before hinted1 the continued existence and waste of some neighbouring continent1 probably formed of ,laurentian rocks1 and situated where the ,atlantic now prevails4 ,such an hypothesis would be in perfect harmony with the conclusions forced upon us by the study of the present configuration of our continents1 and the relation of their height to the depth of the oceanic basins2 also to the considerable elevation and extent sometimes reached by drift containing shells of recent species1 and still more by the fact of sedimentary strata1 several thousand feet thick1 as those of central ,sicily1 or such as flank the ,alps and ,apennines1 containing fossil ,mollusca sometimes almost wholly identical with species still living4 ,i have remarked elsewhere#i that upward and downward movements of #ajjj feet or more would turn much land into sea and sea into land in the continental areas and their borders1 whereas oscillations of equal magnitude would have no corresponding effect in the bed of the ocean generally1 believed as it is to have a mean depth of #ae1jjj feet1 and which1 whether this estimate be correct or not1 is certainly of great profundity4 ,subarial denudation would not of itself lessen the area of the land1 but would tend to fill up with sediment seas of moderate depth adjoining the coast4 ,the coarser matter falls to the bottom near the shore in the first still water which it reaches1 and whenever the sea-bottom on which this matter has been thrown is slightly elevated1 it becomes land1 and an upheaval of a thousand feet causes it to attain the mean elevation of continents in general4 ,suppose1 therefore1 we had ascertained that the triturating power of subarial denudation might in a given time--in three1 or six1 or a greater number of millions of years--pulverise a volume of rock equal in dimensions to all the present land1 we might yet find1 could we revisit the earth at the end of such a period1 that the continents occupied very much the same position which they held before2 we should find the rivers employed in carrying down to the sea the very same mud1 sand1 and pebbles with which they had been charged in our own time1 the superficial alluvial matter as well as a great thickness of sedimentary strata would inclose shells1 all or a great part of which we should recognise as specifically identical with those already known to us as living4 ,every geologist is aware that great as have been the geographical changes in the northern hemisphere since the commencement of the ,glacial ,period1 there having been submergence and re-emergence of land to the extent of #ajjj feet vertically1 and in the temperate latitudes great vicissitudes of climate1 the marine mollusca have not changed1 and the same drift which had been carried down to the sea at the beginning of the period is now undergoing a second transportation in the same direction4 ,as when we have measured a fraction of time in an hour-glass we have only to reverse the position of our chronometer and we make the same sand measure over again the duration of a second equal period1 so when the volcanic force has remoulded the form of a continent and the adjoining sea-bottom1 the same materials are made to do duty a second time4 ,it is true that at each oscillation of level the solid rocks composing the original continent suffer some fresh denudation1 and do not remain unimpaired like the wooden and glass framework of the hour-glass1 still the wear and tear suffered by the larger area exposed to subarial denudation consists either of loose drift or of sedimentary strata1 which were thrown down in seas near the land1 and subsequently upraised1 the same continents and oceanic basins remaining in existence all the while4 ,from all that we know of the extreme slowness of the upward and downward movements which bring about even slight geographical changes1 we may infer that it would require a long succession of geological periods to cause the submarine and supramarine areas to change places1 even if the ascending movements in the one region and the descending in the other were continuously in one direction4 ,but we have only to appeal to the structure of the ,alps1 where there are so many shallow and deep water formations of various ages crowded into a limited area1 to convince ourselves that mountain chains are the result of great oscillations of level4 ,high land is not produced simply by uniform upheaval1 but by a predominance of elevatory over subsiding movements4 ,where the ocean is extremely deep it is because the sinking of the bottom has been in excess1 in spite of interruptions by upheaval4 ,yet persistent as may be the leading features of land and sea on the globe1 they are not immutable4 ,some of the finest mud is doubtless carried to indefinite distances from the coast by marine currents1 and we are taught by deep-sea dredgings that in clear water at depths equalling the height of the ,alps organic beings may flourish1 and their spoils slowly accumulate on the bottom4 ,we also occasionally obtain evidence that submarine volcanoes are pouring out ashes and streams of lava in mid-ocean as well as on land 7see ,principles1 vol4 ii1 p4 #fd71 and that wherever mountains like ,etna1 ,vesuvius1 and the ,canary ,islands are now the site of eruptions1 there are signs of accompanying upheaval1 by which beds of ashes full of recent marine shells have been uplifted many hundred feet4 ,we need not be surprised1 therefore1 if we learn from geology that the continents and oceans were not always placed where they now are1 although the imagination may well be overpowered when it endeavours to contemplate the quantity of time required for such revolutions4 ,we shall have gained a great step if we can approximate to the number of millions of years in which the average aqueous denudation going on upon the land would convey seaward a quantity of matter equal to the average volume of our continents1 and this might give us a gauge of the minimum of volcanic force necessary to counteract such levelling power of running water2 but to discover a relation between these great agencies and the rate at which species of organic beings vary1 is at present wholly beyond the reach of our computation1 though perhaps it may not prove eventually to transcend the powers of man4 #a ,hull1 ,quart4 ,geol4 ,journ41 vol4 xxiv1 p4 #cbb1 #ahfh4 #b ,tylor1 ,phil4 ,mag41 #dth series1 p4 #bfh1 #ahej4 #c ,croll1 ,phil4 ,mag41 #ahfh1 p4 #cha4 #d ,vol4 i1 p4 #ddb1 #ahfg4 #e ,trans4 ,geol4 ,soc4 ,glasgow1 vol4 iii1 p4 #afi4 #f #ast ed41 chap4 x1 p4 #afg1 #ahcj2 see also #ajth ed41 vol4 i1 chap4 xv1 p4 #cbg1 #ahfg4 #g ,principles1 vol4 ii1 p4 #bcg2 also #ast ed41 p4 #ddg1 #ahcj4 #h ,principles1 vol4 ii1 p4 #bbi1 #ahfh4 #i ,principles1 vol4 i1 p4 #bfe1 #ahfg4 ,,chapter ,,viii4 ,,chronological ,,classification ,,of ,,rocks4 ,aqueous1 ,plutonic1 volcanic1 and metamorphic ,rocks considered chronologically4 -- ,terms ,primary1 ,secondary1 and ,tertiary2 ,palozoic1 ,mesozoic1 and ,cainozoic explained4 -- ,on the different ,ages of the aqueous ,rocks4 -- ,three principal ,tests of relative ,age3 ,superposition1 ,mineral ,character1 and ,fossils4 -- ,change of ,mineral ,character and ,fossils in the same continuous ,formation4 -- ,proofs that distinct ,species of ,animals and ,plants have lived at successive ,periods4 -- ,distinct ,provinces of indigenous ,species4 -- ,great ,extent of single ,provinces4 -- ,similar ,laws prevailed at successive ,geological ,periods4 -- ,relative ,importance of mineral and palontological ,characters4 -- ,test of ,age by included ,fragments4 -- ,frequent ,absence of ,strata of intervening ,periods4 -- ,tabular ,views of fossiliferous ,strata4 ,chronology of ,rocks4-- ,in the first chapter it was stated that the four great classes of rocks1 the aqueous1 the volcanic1 the ,plutonic1 and the metamorphic1 would each be considered not only in reference to their mineral characters1 and mode of origin1 but also to their relative age4 ,in regard to the aqueous rocks1 we have already seen that they are stratified1 that some are calcareous1 others argillaceous or siliceous1 some made up of sand1 others of pebbles2 that some contain fresh-water1 others marine fossils1 and so forth2 but the student has still to learn which rocks1 exhibiting some or all of these characters1 have originated at one period of the earth's history1 and which at another4 ,to determine this point in reference to the fossiliferous formations is more easy than in any other class1 and it is therefore the most convenient and natural method to begin by establishing a chronology for these strata1 and then to refer as far as possible to the same divisions1 the several groups of ,plutonic1 volcanic1 and metamorphic rocks4 ,such a system of classification is not only recommended by its greater clearness and facility of application1 but is also best fitted to strike the imagination by bringing into one view the contemporaneous revolutions of the inorganic and organic creations of former times4 ,for the sedimentary formations are most readily distinguished by the different species of fossil animals and plants which they inclose1 and of which one assemblage after another has flourished and then disappeared from the earth in succession4 ,in the present work1 therefore1 the four great classes of rocks1 the aqueous1 ,plutonic1 volcanic1 and metamorphic1 will form four parallel1 or nearly parallel1 columns in one chronological table4 ,they will be considered as four sets of monuments relating to four contemporaneous1 or nearly contemporaneous1 series of events4 ,i shall endeavour1 in a subsequent chapter on the ,plutonic rocks1 to explain the manner in which certain masses belonging to each of the four classes of rocks may have originated simultaneously at every geological period1 and how the earth's crust may have been continually remodelled1 above and below1 by aqueous and igneous causes1 from times indefinitely remote4 ,in the same manner as aqueous and fossiliferous strata are now formed in certain seas or lakes1 while in other places volcanic rocks break out at the surface1 and are connected with reservoirs of melted matter at vast depths in the bowels of the earth1 so1 at every era of the past1 fossiliferous deposits and superficial igneous rocks were in progress contemporaneously with others of subterranean and ,plutonic origin1 and some sedimentary strata were exposed to heat1 and made to assume a crystalline or metamorphic structure4 ,it can by no means be taken for granted1 that during all these changes the solid crust of the earth has been increasing in thickness4 ,it has been shown1 that so far as aqueous action is concerned1 the gain by fresh deposits1 and the loss by denudation1 must at each period have been equal 7see above1 ,chap4 ,,vi1 p4 #if72 and in like manner1 in the inferior portion of the earth's crust1 the acquisition of new crystalline rocks1 at each successive era1 may merely have counterbalanced the loss sustained by the melting of materials previously consolidated4 ,as to the relative antiquity of the crystalline foundations of the earth's crust1 when compared to the fossiliferous and volcanic rocks which they support1 ,i have already stated1 in the first chapter1 that to pronounce an opinion on this matter is as difficult as at once to decide which of the two1 whether the foundations or superstructure of an ancient city built on wooden piles may be the oldest4 ,we have seen that1 to answer this question1 we must first be prepared to say whether the work of decay and restoration had gone on most rapidly above or below2 whether the average duration of the piles has exceeded that of the buildings1 or the contrary4 ,so also in regard to the relative age of the superior and inferior portions of the earth's crust2 we cannot hazard even a conjecture on this point1 until we know whether1 upon an average1 the power of water above1 or that of heat below1 is most efficacious in giving new forms to solid matter4 ,the early geologists gave to all the crystalline and non-fossiliferous rocks the name of ,primitive or ,primary1 under the idea that they were formed anterior to the appearance of life upon the earth1 while the aqueous or fossiliferous strata were termed ,secondary1 and alluviums or other superficial deposits1 ,tertiary4 ,the meaning of these terms1 has1 however1 been gradually modified with advancing knowledge1 and they are now used to designate three great chronological divisions under which all geological formations can be classed1 each of them being characterised by the presence of distinctive groups of organic remains rather than by any mechanical peculiarities of the strata themselves4 ,if1 therefore1 we retain the term 8primary10 it must not be held to designate a set of crystalline rocks some of which have been proved to be even of ,tertiary age1 but must be applied to all rocks older than the secondary formations4 ,some geologists1 to avoid misapprehension1 have introduced the term ,palozoic for primary1 from palaion1 8ancient10 and zoon1 8an organic being10 still retaining the terms secondary and tertiary2 ,mr4 ,phillips1 for the sake of uniformity1 has proposed ,mesozoic1 for secondary1 from mesos1 8middle10 etc42 and ,cainozoic1 for tertiary1 from kainos1 8recent10 etc42 but the terms primary1 secondary1 and tertiary have the claim of priority in their favour1 and are of corresponding value4 ,it may perhaps be suggested that some metamorphic strata1 and some granites1 may be anterior in date to the oldest of the primary fossiliferous rocks4 ,this opinion is doubtless true1 and will be discussed in future chapters2 but ,i may here observe1 that when we arrange the four classes of rocks in four parallel columns in one table of chronology1 it is by no means assumed that these columns are all of equal length2 one may begin at an earlier period than the rest1 and another may come down to a later point of time1 and we may not be yet acquainted with the most ancient of the primary fossiliferous beds1 or with the newest of the hypogene4 ,for reasons already stated1 ,i proceed first to treat of the aqueous or fossiliferous formations considered in chronological order or in relation to the different periods at which they have been deposited4 ,there are three principal tests by which we determine the age of a given set of strata2 first1 superposition2 secondly1 mineral character2 and1 thirdly1 organic remains4 ,some aid can occasionally be derived from a fourth kind of proof1 namely1 the fact of one deposit including in it fragments of a pre-existing rock1 by which the relative ages of the two may1 even in the absence of all other evidence1 be determined4 ,superposition4--,the first and principal test of the age of one aqueous deposit1 as compared to another1 is relative position4 ,it has been already stated1 that1 where strata are horizontal1 the bed which lies uppermost is the newest of the whole1 and that which lies at the bottom the most ancient4 ,so1 of a series of sedimentary formations1 they are like volumes of history1 in which each writer has recorded the annals of his own times1 and then laid down the book1 with the last written page uppermost1 upon the volume in which the events of the era immediately preceding were commemorated4 ,in this manner a lofty pile of chronicles is at length accumulated2 and they are so arranged as to indicate1 by their position alone1 the order in which the events recorded in them have occurred4 ,in regard to the crust of the earth1 however1 there are some regions where1 as the student has already been informed1 the beds have been disturbed1 and sometimes extensively thrown over and turned upside down4 7,see p4 #gc1 p4 #hg47 ,but an experienced geologist can rarely be deceived by these exceptional cases4 ,when he finds that the strata are fractured1 curved1 inclined1 or vertical1 he knows that the original order of superposition must be doubtful1 and he then endeavours to find sections in some neighbouring district where the strata are horizontal1 or only slightly inclined4 ,here1 the true order of sequence of the entire series of deposits being ascertained1 a key is furnished for settling the chronology of those strata where the displacement is extreme4 ,mineral ,character4--,the same rocks may often be observed to retain for miles1 or even hundreds of miles1 the same mineral peculiarities1 if we follow the planes of stratification1 or trace the beds1 if they be undisturbed1 in a horizontal direction4 ,but if we pursue them vertically1 or in any direction transverse to the planes of stratification1 this uniformity ceases almost immediately4 ,in that case we can scarcely ever penetrate a stratified mass for a few hundred yards without beholding a succession of extremely dissimilar rocks1 some of fine1 others of coarse grain1 some of mechanical1 others of chemical origin2 some calcareous1 others argillaceous1 and others siliceous4 ,these phenomena lead to the conclusion that rivers and currents have dispersed the same sediment over wide areas at one period1 but at successive periods have been charged1 in the same region1 with very different kinds of matter4 ,the first observers were so astonished at the vast spaces over which they were able to follow the same homogeneous rocks in a horizontal direction1 that they came hastily to the opinion1 that the whole globe had been environed by a succession of distinct aqueous formations1 disposed round the nucleus of the planet1 like the concentric coats of an onion4 ,but1 although1 in fact1 some formations may be continuous over districts as large as half of ,europe1 or even more1 yet most of them either terminate wholly within narrower limits1 or soon change their lithological character4 ,sometimes they thin out gradually1 as if the supply of sediment had failed in that direction1 or they come abruptly to an end1 as if we had arrived at the borders of the ancient sea or lake which served as their receptacle4 ,it no less frequently happens that they vary in mineral aspect and composition1 as we pursue them horizontally4 ,for example1 we trace a limestone for a hundred miles1 until it becomes more arenaceous1 and finally passes into sand1 or sandstone4 ,we may then follow this sandstone1 already proved by its continuity to be of the same age1 throughout another district a hundred miles or more in length4 ,organic ,remains4--,this character must be used as a criterion of the age of a formation1 or of the contemporaneous origin of two deposits in distant places1 under very much the same restrictions as the test of mineral composition4 ,first1 the same fossils may be traced over wide regions1 if we examine strata in the direction of their planes1 although by no means for indefinite distances4 ,secondly1 while the same fossils prevail in a particular set of strata for hundreds of miles in a horizontal direction1 we seldom meet with the same remains for many fathoms1 and very rarely for several hundred yards1 in a vertical line1 or a line transverse to the strata4 ,this fact has now been verified in almost all parts of the globe1 and has led to a conviction that at successive periods of the past1 the same area of land and water has been inhabited by species of animals and plants even more distinct than those which now people the antipodes1 or which now co-exist in the arctic1 temperate1 and tropical zones4 ,it appears that from the remotest periods there has been ever a coming in of new organic forms1 and an extinction of those which pre-existed on the earth2 some species having endured for a longer1 others for a shorter1 time2 while none have ever reappeared after once dying out4 ,the law which has governed the succession of species1 whether we adopt or reject the theory of transmutation1 seems to be expressed in the verse of the poet3-- ,natura il fece1 e poi ruppe la stampa4 ,,ariosto4 ,nature made him1 and then broke the die4 ,and this circumstance it is1 which confers on fossils their highest value as chronological tests1 giving to each of them1 in the eyes of the geologist1 that authority which belongs to contemporary medals in history4 ,the same cannot be said of each peculiar variety of rock2 for some of these1 as red marl and red sandstone1 for example1 may occur at once at the top1 bottom1 and middle of the entire sedimentary series2 exhibiting in each position so perfect an identity of mineral aspect as to be undistinguishable4 ,such exact repetitions1 however1 of the same mixtures of sediment have not often been produced1 at distant periods1 in precisely the same parts of the globe2 and even where this has happened1 we are seldom in any danger of confounding together the monuments of remote eras1 when we have studied their imbedded fossils and their relative position4 ,zoological ,provinces4--,it was remarked that the same species of organic remains cannot be traced horizontally1 or in the direction of the planes of stratifications for indefinite distances4 ,this might have been expected from analogy2 for when we inquire into the present distribution of living beings1 we find that the habitable surface of the sea and land may be divided into a considerable number of distinct provinces1 each peopled by a peculiar assemblage of animals and plants4 ,in the 8,principles of ,geology10 ,i have endeavoured to point out the extent and probable origin of these separate divisions2 and it was shown that climate is only one of many causes on which they depend1 and that difference of longitude as well as latitude is generally accompanied by a dissimilarity of indigenous species4 ,as different seas1 therefore1 and lakes are inhabited1 at the same period1 by different aquatic animals and plants1 and as the lands adjoining these may be peopled by distinct terrestrial species1 it follows that distinct fossils will be imbedded in contemporaneous deposits4 ,if it were otherwise--if the same species abounded in every climate1 or in every part of the globe where1 so far as we can discover1 a corresponding temperature and other conditions favourable to their existence are found--the identification of mineral masses of the same age1 by means of their included organic contents1 would be a matter of still greater certainty4 ,nevertheless1 the extent of some single zoological provinces1 especially those of marine animals1 is very great2 and our geological researches have proved that the same laws prevailed at remote periods2 for the fossils are often identical throughout wide spaces1 and in detached deposits1 consisting of rocks varying entirely in their mineral nature4 ,the doctrine here laid down will be more readily understood1 if we reflect on what is now going on in the ,mediterranean4 ,that entire sea may be considered as one zoological province2 for although certain species of testacea and zoophytes may be very local1 and each region has probably some species peculiar to it1 still a considerable number are common to the whole ,mediterranean4 ,if1 therefore1 at some future period1 the bed of this inland sea should be converted into land1 the geologist might be enabled1 by reference to organic remains1 to prove the contemporaneous origin of various mineral masses scattered over a space equal in area to half of ,europe4 ,deposits1 for example1 are well known to be now in progress in this sea in the deltas of the ,po1 ,rhone1 ,nile1 and other rivers1 which differ as greatly from each other in the nature of their sediment as does the composition of the mountains which their drain4 ,there are also other quarters of the ,mediterranean1 as off the coast of ,campania1 or near the base of ,etna1 in ,sicily1 or in the ,grecian ,archipelago1 where another class of rocks is now forming2 where showers of volcanic ashes occasionally fall into the sea1 and streams of lava overflow its bottom2 and where1 in the intervals between volcanic eruptions1 beds of sand and clay are frequently derived from the waste of cliffs1 or the turbid waters of rivers4 ,limestones1 moreover1 such as the ,italian travertins1 are here and there precipitated from the waters of mineral springs1 some of which rise up from the bottom of the sea4 ,in all these detached formations1 so diversified in their lithological characters1 the remains of the same shells1 corals1 crustacea1 and fish are becoming inclosed2 or1 at least1 a sufficient number must be common to the different localities to enable the zoologist to refer them all to one contemporaneous assemblage of species4 ,there are1 however1 certain combinations of geographical circumstances which cause distinct provinces of animals and plants to be separated from each other by very narrow limits2 and hence it must happen that strata will be sometimes formed in contiguous regions1 differing widely both in mineral contents and organic remains4 ,thus1 for example1 the testacea1 zoophytes1 and fish of the ,red ,sea are1 as a group1 extremely distinct from those inhabiting the adjoining parts of the ,mediterranean1 although the two seas are separated only by the narrow isthmus of ,suez4 ,calcareous formations have accumulated on a great scale in the ,red ,sea in modern times1 and fossil shells of existing species are well preserved therein2 and we know that at the mouth of the ,nile large deposits of mud are amassed1 including the remains of ,mediterranean species4 ,it follows1 therefore1 that if at some future period the bed of the ,red ,sea should be laid dry1 the geologist might experience great difficulties in endeavouring to ascertain the relative age of these formations1 which1 although dissimilar both in organic and mineral characters1 were of synchronous origin4 ,but1 on the other hand1 we must not forget that the north-western shores of the ,arabian ,gulf1 the plains of ,egypt1 and the ,isthmus of ,suez1 are all parts of one province of terrestrial species4 ,small streams1 therefore1 occasional land- floods1 and those winds which drift clouds of sand along the deserts1 might carry down into the ,red ,sea the same shells of fluviatile and land testacea which the ,nile is sweeping into its delta1 together with some remains of terrestrial plants and the bones of quadrupeds1 whereby the groups of strata before alluded to might1 notwithstanding the discrepancy of their mineral composition and marine organic fossils1 be shown to have belonged to the same epoch4 ,yet1 while rivers may thus carry down the same fluviatile and terrestrial spoils into two or more seas inhabited by different marine species1 it will much more frequently happen that the coexistence of terrestrial species of distinct zoological and botanical provinces will be proved by the identity of the marine beings which inhabited the intervening space4 ,thus1 for example1 the land quadrupeds and shells of the valley of the ,mississippi1 of central ,america1 and of the ,west ,india islands differ very considerably1 yet their remains are all washed down by rivers flowing from these three zoological provinces into the ,gulf of ,mexico4 ,in some parts of the globe1 at the present period1 the line of demarkation between distinct provinces of animals and plants is not very strongly marked1 especially where the change is determined by temperature1 as it is in seas extending from the temperate to the tropical zone1 or from the temperate to the arctic regions4 ,here a gradual passage takes place from one set of species to another4 ,in like manner the geologist1 in studying particular formations of remote periods1 has sometimes been able to trace the gradation from one ancient province to another1 by observing carefully the fossils of all the intermediate places4 ,his success in thus acquiring a knowledge of the zoological or botanical geography of very distant eras has been mainly owing to this circumstance1 that the mineral character has no tendency to be affected by climate4 ,a large river may convey yellow or red mud into some part of the ocean1 where it may be dispersed by a current over an area several hundred leagues in length1 so as to pass from the tropics into the temperate zone4 ,if the bottom of the sea be afterwards upraised1 the organic remains imbedded in such yellow or red strata may indicate the different animals or plants which once inhabited at the same time the temperate and equatorial regions4 ,it may be true1 as a general rule1 that groups of the same species of animals and plants may extend over wider areas than deposits of homogeneous composition2 and if so1 palontological characters will be of more importance in geological classification than the test of mineral composition2 but it is idle to discuss the relative value of these tests1 as the aid of both is indispensable1 and it fortunately happens1 that where the one criterion fails1 we can often avail ourselves of the other4 ,test by included ,fragments of older ,rocks4--,it was stated1 that proof may sometimes be obtained of the relative date of two formations by fragments of an older rock being included in a newer one4 ,this evidence may sometimes be of great use1 where a geologist is at a loss to determine the relative age of two formations from want of clear sections exhibiting their true order of position1 or because the strata of each group are vertical4 ,in such cases we sometimes discover that the more modern rock has been in part derived from the degradation of the older4 ,thus1 for example1 we may find chalk in one part of a country1 and in another strata of clay1 sand1 and pebbles4 ,if some of these pebbles consist of that peculiar flint1 of which layers more or less continuous are characteristic of the chalk1 and which include fossil shells1 sponges1 and foraminifera of cretaceous species1 we may confidently infer that the chalk was the oldest of the two formations4 ,chronological ,groups4--,the number of groups into which the fossiliferous strata may be separated are more or less numerous1 according to the views of classification which different geologists entertain2 but when we have adopted a certain system of arrangement1 we immediately find that a few only of the entire series of groups occur one upon the other in any single section or district4 ,the thinning out of individual strata was before described 7p4 #db74;,but let the diagram 7,fig4 #hd7 represent seven fossiliferous groups1 instead of as many strata4 ,it will then be seen that in the middle all the superimposed formations are present2 but in consequence of some of them thinning out1 ,no4 #b and ,no4 #e are absent at one extremity of the section1 and ,no4 #d at the other4 ,fig4 #hd3 ,seven fossiliferous groups4 ,in another diagram 7,fig4 #he71 a real section of the geological formations in the neighbourhood of ,bristol and the ,mendip ,hills is presented to the reader1 as laid down on a true scale by ,professor ,ramsay1 where the newer groups #a1 #b1 #c1 #d rest unconformably on the formations #e1 #f1 #g and #h4 ,at the southern end of the line of section we meet with the beds ,no4 #c 7the ,new ,red ,sandstone7 resting immediately on ,nos4 #g and #h1 while farther north as at ,dundry ,hill in ,somersetshire1 we behold eight groups superimposed one upon the other1 comprising all the strata from the inferior ,oolite1 ,no4 #a1 to the coal and carboniferous limestone4 ,the limited horizontal extension of the groups #a and #b is owing to denudation1 as these formations end abruptly1 and have left outlying patches to attest the fact of their having originally covered a much wider area4 ,section ,south of ,bristol4 ,in order1 therefore1 to establish a chronological succession of fossiliferous groups1 a geologist must begin with a single section in which several sets of strata lie one upon the other4 ,he must then trace these formations1 by attention to their mineral character and fossils1 continuously1 as far as possible1 from the starting-point4 ,as often as he meets with new groups1 he must ascertain by superposition their age relatively to those first examined1 and thus learn how to intercalate them in a tabular arrangement of the whole4 ,by this means the ,german1 ,french1 and ,english geologists have determined the succession of strata throughout a great part of ,europe1 and have adopted pretty generally the following groups1 almost all of which have their representatives in the ,british ,islands4 ,abridged ,general ,table of ,fossiliferous ,strata4 ,,tabular ,,view ,,of ,,the ,,fossiliferous ,,strata1 ,,showing ,,the ,,order ,,of ,,superposition ,,or ,,chronological ,,succession ,,of ,,the ,,principal ,,groups ,,described ,,in ,,this ,,work4 ,,post-,,tertiary ,,examples ,,post-,,tertiary ,,examples ,,post- ,,tertiary #a4 ,,recent ,shells and mammals1 all of living species4 ,british ,clyde marine strata1 with canoes 7p4 #adf74 ,foreign ,danish kitchen middens 7p4 #adf74 ,lacustrine mud1 with remains of ,swiss lake-dwellings 7p4 #adh74 ,marine strata inclosing ,temple of ,serapis1 at ,puzzuoli 7p4 #adf74 #b4 ,,post- ,,pliocene4 ,shells1 recent mammalia in part extinct4 ,british ,loam of ,brixham cave1 with flint implements and bones of extinct and living quadrupeds 7p4 #aeg7 ,drift near ,salisbury1 with bones of mammoth1 ,spermophilus1 and stone implements 7p4 #afa74 ,glacial drift of ,scotland1 with marine shells and remains of mammoth 7p4 #agf4 ,erratics of ,pagham and ,selsey ,bill 7p4 #ahb74 ,glacial drift of ,wales1 with marine fossil shells1 about #adjj feet high1 on ,moel ,tryfaen 7p4 #aha74 ,foreign ,dordogne caves of the reindeer period 7p4 #aej74 ,older valley-gravels of ,amiens1 with flint implements and bones of extinct mammalia 7p4 #aeb74 ,loess of ,rhine 7p4 #aed74 ,ancient ,nile-mud forming river-terraces 7p4 #aed74 ,loam and breccia of ,liege caverns1 with human remains 7pp4 #aef1 #aeg74 ,australian cave breccias1 with bones of extinct marsupials 7p4 #aeh74 ,glacial drift of ,northern ,europe 7p4 #aff1 p4 #agd74 ,,tertiary ,,or ,,cainozoic ,,pliocene #c4 ,,newer ,,pliocene4 ,the shells almost all of living species4 ,british ,bridlington beds1 marine ,arctic fauna 7p4 #ahi74 ,glacial boulder formation of ,norfolk cliffs 7p4 #aij74 ,forest-bed of ,norfolk cliffs1 with bones of ,elephas meridionalis1 etc4 7p4 #aia74 ,chillesford and ,aldeby beds1 with marine shells1 chiefly ,arctic 7p4 #aib74 ,norwich crag 7p4 #aic74 ,foreign ,eastern base of ,mount ,etna1 with marine shells 7p4 #bjd74 ,sicilian calcareous and tufaceous strata 7p4 #bje1 #bjf74 ,lacustrine strata of ,upper ,val d',arno 7p4 #bjg74 ,madeira leaf-bed and land-shells 7p4 #ecb74 #d4 ,,older ,,pliocene4 ,extinct species of shells forming a large minority4 ,british ,red crag of ,suffolk1 marine shells1 some of northern forms 7p4 #aid1 #aie74 ,white or coralline crag of ,suffolk 7p4 #aig74 ,foreign ,antwerp crag 7p4 #bjd74 ,subapennine marls and sands 7p4 #bjh74 ,,examples ,,miocene #e4 ,,upper ,,miocene4 ,majority of the shells extinct4 ,british ,wanting4 ,foreign ,faluns of ,touraine 7p4 #baa74 ,faluns1 proper1 of ,bordeaux 7p4 #bad74 ,fresh-water strata of ,gers 7p4 #bae74 ,swiss ,oeningen beds1 rich in plants and insects 7pp4 #bae-bc74 ,marine ,molasse1 ,switzerland 7p4 #bbc74 ,bolderberg beds of ,belgium 7p4 #bbd74 ,vienna basin 7p4 #bbd74 ,beds of the ,superga1 near ,turin 7p4 #bbf74 ,deposit at ,pikerm1 near ,athens 7p4 #bbf74 ,strata of the ,siwlik hills1 ,india 7p4 #bbf74 ,marine strata of the ,atlantic border in the ,united ,states 7p4 #bbg74 ,volcanic tuff and limestone of ,madeira1 the ,canaries1 and the ,azores 774 #f4 ,,lower ,,miocene4 ,nearly all the shells extinct4 ,british ,hempstead beds1 marine and fresh-water strata 7p4 #bdd74 ,lignites and clays of ,bovey ,tracey 7p4 #bde74 ,isle of ,mull leaf-bed1 volcanic tuff 7p4 #bdg74 ,foreign ,calcaire de la ,beauce1 etc4 7p4 #bcj74 ,grs de ,fontainebleau 7p4 #bcj74 ,lacustrine strata of the ,limagne d',auvergne1 and the ,cantal 7p4 #bcc74 ,mayence basin 7p4 #bdb74 ,radaboj beds of ,croatia 7p4 #bdb74 ,brown coal of ,germany 7p4 #bdd74 ,lower ,molasse of ,switzerland1 fresh-water and brackish 7p4 #bce-i74 ,rupelmonde1 ,kleynspawen1 and ,tongrian beds of ,belgium 7p4 #bda1 #bdb74 ,nebraska beds1 ,united ,states 7p4 #bdh74 ,lower ,miocene beds of ,italy 7p4 #bdd74 ,miocene flora of ,north ,greenland 7p4 #bci74 ,,eocene #g4 ,,upper ,,eocene4 ,british ,bembridge fluvio-marine strata 7p4 #beb74 ,osborne or ,st4 ,helen's series 7p4 #bee74 ,headon series1 with marine and fresh-water shells 7p4 #bee74 ,barton sands and clays 7p4 #beh74 ,foreign ,gypsum of ,montmartre1 fresh-water with ,palotherium 7p4 #bgj74 ,calcaire silicieux1 or ,travertin infrieur 7p4 #bgc71 ,grs de ,beauchamp1 or ,sables moyens 7p4 #bgc74 #h4 ,,middle ,,eocene4 ,british ,bracklesham beds and ,bagshot sands 7p4 #bei74 ,white clays of ,alum ,bay and ,bournemouth 7p4 #bfb74 ,foreign ,calcaire grossier1 miliolitic limestone 7p4 #bgd74 ,soissonnais sands1 or ,lits coquilliers1 with ,nummulites planulata 7p4 #bge74 ,claiborne beds of the ,united ,states1 with ,orbitoides and ,zeuglodon 7p4 #bgi74 ,nummulitic formation of ,europe1 ,asia1 etc4 7p4 #bgg74 #i4 ,,lower ,,eocene4 ,british ,london clay proper 7p4 #bfc74 ,woolwich and ,reading series1 fluvio-marine 7p4 #bfg74 ,thanet sands 7p4 #bfi74 ,foreign ,argile de ,londres1 near ,dunkirk 7p4 #beb74 ,argile plastique 7p4 #bgf74 ,sables de ,bracheux 7p4 #bgf74 ,,secondary ,,or ,,mesozoic4 ,,cretaceous #aj4 ,,upper ,,cretaceous4 ,british ,upper white chalk1 with flints 7p4 #bij74 ,lower white chalk1 without flints 7p4 #bih74 ,chalk marl 7p4 #bih74 ,chloritic series 7or ,upper ,greensand71 fire-stone of ,surrey 7p4 #bih74 ,gault 7p4 #cjj74 ,blackdown beds 7p4 #cja74 ,,examples ,,cretaceous #aj4 ,,upper ,,cretaceous4 ,foreign ,maetricht beds and ,faxoe chalk 7p4 #bcc74 ,pisolitic limestone of ,france 7p4 #bhe74 ,white chalk of ,france1 ,sweden1 and ,russia 7p4 #bhf1 #bhg74 ,planer-kalk of ,saxony 7p4 #bic74 ,sands and clays of ,aix-la-,chapelle 7p4 #cjb74 ,hippurite limestone of ,south of ,france 7p4 #cje74 ,new ,jersey1 ,u4,s41 sands and marls 7p4 #cjg74 #aa4 ,,lower ,,cretaceous or ,,neocomian4 ,british ,sands of ,folkestone1 ,sandgate1 and ,hythe 7p4 #cjh74 ,atherfield clay1 with ,perna mulleti 7p4 #cji74 ,punfield marine beds1 with ,vicarya lujana 7p4 #cah74 ,speeton clay of ,flamborough ,head and ,tealby 7p4 #caa74 ,weald clay of ,surrey1 ,kent1 and ,sussex1 fresh-water1 with ,cypris 7p4 #cac-e74 ,hastings sands 7p4 #caf-h74 ,foreign ,neocomian of ,neufchatel1 and ,hils conglomerate of ,north ,germany 7p4 #cab74 ,wealden beds of ,hanover 7p4 #cai74 ,,oolite #ab4 ,,upper ,,oolite4 ,british ,upper ,purbeck beds1 fresh-water 7p4 #cbc74 ,middle ,purbeck1 with numerous marsupial quadrupeds1 etc4 7p4 #cbd74 ,lower ,purbeck1 fresh-water1 with intercalated dirt-bed 7p4 #ccj74 ,portland stone and sand4 7p4 #ccd74 ,kimmeridge clay 7p4 #cce74 ,foreign ,marnes gryphes virgules of ,argonne 7p4 #ccf74 ,lithographic-stone of ,solenhofen1 with ,archopteryx 7p4 #ccg74 #ac4 ,,middle ,,oolite4 ,british ,coral rag of ,berkshire1 ,wilts1 and ,yorkshire 7p4 #cci74 ,oxford clay1 with belemnites and ,ammonite 7p4 #cdj74 ,kelloway rock of ,wilts and ,yorkshire 7p4 #cda74 ,foreign ,nerinan limestone of the ,jura 7p4 #cci74 #ad4 ,,lower ,,oolite4 ,british ,cornbrash and forest marble 7p4 #cda74 ,great or ,bath oolite of ,bradford 7p4 #cdb74 ,stonesfield slate1 with marsupials and ,araucaria 7p4 #cde74 ,fuller's earth of ,bath 7p4 #cdh74 ,inferior oolite 7p4 #cdi74 ,,lias #ae4 ,,lias4 ,upper ,lias1 argillaceous1 with ,ammonites striatulus 7p4 #cec74 ,shale and limestone1 with ,ammonites bifrons 7p4 #cec74 ,middle ,lias or ,marlstone series1 with zones containing characteristic ,ammonites 7p4 #cec74 ,lower ,lias1 also with zones characterised by peculiar ,ammonites 7p4 #cef74 ,,trias #af4 ,,upper ,,trias4 ,british ,rhtic1 ,penarth or ,avicula contorta beds 7beds of passage7 7p4 #cff74 ,keuper or ,upper ,new ,red sandstone1 etc4 7p4 #cfi74 ,red shales of ,cheshire and ,lancashire1 with rock-salt 7p4 #cga74 ,dolomite conglomerate of ,bristol 7p4 #cgc74 ,foreign ,keuper beds of ,germany 7p4 #cge74 ,st4 ,cassian or ,hallstadt beds1 with rich marine fauna 7p4 #cgf74 ,coal-field of ,richmond1 ,virginia 7p4 #chb74 ,chatham coal-field1 ,north ,carolina 7p4 #chc74 #ag4 ,,middle ,,trias4 ,british ,wanting4 ,foreign ,muschelkalk of ,germany 7p4 #cgh74 #ah4 ,,lower ,,trias4 ,british ,bunter or ,lower ,new ,red sandstone of ,lancashire and ,cheshire 7p4 #cgb74 ,foreign ,bunter-sandstein of ,germany 7p4 #chj74 ,red sandstone of ,connecticut ,valley1 with footprints of birds and reptiles 7p4 #cha74 ,,primary ,,or ,,pal,,ozoic ,,examples ,,permian #ai4 ,,permian4 ,british ,upper ,permian of ,st4 ,bees' ,head1 ,cumberland 7p4 #chf74 ,middle ,permian1 magnesian limestone1 and marl-slate of ,durham and ,yorkshire1 with ,protosaurus 7p4 #chg74 ,lower ,permian sandstones and breccias of ,penrith and ,dumfriesshire1 intercalated 7p4 #cij74 ,foreign ,dark-coloured shales of ,thuringia 7p4 #cib74 ,zechstein or ,dolomitic limestone 7p4 #cib74 ,mergel-schiefer or ,kupfer-schiefer 7p4 #cib74 ,rothliegendes of ,thuringia1 with ,psaronius 7p4 #cib74 ,magnesian limestones1 etc41 of ,russia 7p4 #cic74 ,,carboniferous #bj4 ,,upper ,,carboniferous4 ,british ,coal-measures of ,south ,wales1 with underclays inclosing ,stigmaria 7p4 #cig74 ,coal-measures of north and central ,england 7p4 #cie74 ,millstone grit 7p4 #cie74 ,yoredale series of ,yorkshire 7p4 #cie74 ,coal-field of ,kilkenny with ,labyrinthodont 7p4 #djg74 ,foreign ,coal-field of ,saarbruck1 with ,archegosaurus 7p4 #djf74 ,carboniferous strata of ,south ,joggins1 ,nova ,scotia 7p4 #dji74 ,pennsylvania coal-field 7p4 #djc74 #ba4 ,,lower ,,carboniferous4 ,british ,mountain limestone of ,wales and ,south of ,england 7p4 #dcj74 ,same in ,ireland 7p4 #dcgdcg74 ,carboniferous limestone of ,scotland alternating with coal-bearing sandstones 7p4 #cif74 ,erect trees in volcanic ash in the ,island of ,arran 7p4 #edf74 ,foreign ,mountain limestone of ,belgium 7p4 #dcf74 ,,devonian or ,,old ,,red ,,sandstone #bb4 ,,upper ,,devonian4 ,british ,yellow sandstone of ,dura ,den1 with ,holoptychius1 etc4 7p4 #ddj72 and of ,ireland with ,anodon ,jukesii 7p4 #dda74 ,sandstones of ,forfarshire and ,perthshire1 with ,holoptychius1 etc4 7p4 #ddb74 ,pilton group of ,north ,devon 7p4 #ddi74 ,petherwyn group of ,cornwall1 with ,clymenia and ,cypridina 7p4 #dea74 ,foreign ,clymenien-kalk and ,cypridinen-schiefer of ,germany 7p4 #dej7 #bc4 ,,middle ,,devonian4 ,british ,bituminous schists of ,gamrie1 ,caithness1 etc41 with numerous fish 7p4 #ddc74 ,ilfracombe beds with peculiar trilobites and corals 7p4 #dej74 ,limestones of ,torquay1 with broad-winged ,spirifers 7p4 #dea74 ,foreign ,eifel limestone1 with underlying schists containing ,calceola 7p4 #dec74 ,devonian strata of ,russia 7p4 #ded74 #bd4 ,,lower ,,devonian4 ,british ,arbroath paving-stones1 with ,cephalaspis and ,pterygotus 7p4 #ddf74 ,lower sandstones of ,forfarshire1 with ,pterygotus 7p4 #ddf74 ,sandstones and slates of the ,foreland and ,linton 7p4 #ded74 ,foreign ,oriskany sandstone of ,western ,canada and ,new ,york 7p4 #def74 ,sandstones of ,gaspe1 with ,cephalaspis 7p4 #dee 74 ,,examples ,,silurian #be4 ,,upper ,,silurian ,british ,upper ,ludlow formation1 ,downton sandstone1 with bone-bed 7p4 #dei74 ,lower ,ludlow formation1 with oldest known fish remains 7p4 #dfa74 ,wenlock limestone and shale 7p4 #dfe74 ,woolhope limestone and grit 7p4 #dfg74 ,tarannon shales 7p4 #dfh74 ,beds of passage between ,upper and ,lower ,silurian3 ,upper ,llandovery1 or ,may-hill sandstone1 with ,pentamerus oblongus1 etc4 7p4 #dfh74 ,lower ,llandovery slates 7p4 #dfi74 ,foreign ,niagara limestone1 with ,calymene1 ,homalonotus1 etc4 7p4 #dgi74 ,clinton group of ,america1 with ,pentamerus oblongus1 etc4 7p4 #dgi74 ,silurian strata of ,russia1 with ,pentamerus 7p4 #dgg74 #bf4 ,,lower ,,silurian4 ,british ,bala and ,caradoc beds 7p4 #dgj74 ,llandeilo flags 7p4 #dgc74 ,arenig or ,stiper-stones group 7,lower ,llandeilo of ,murchison7 7p4 #dge74 ,foreign ,ungulite or ,obolus grit of ,russia 7p4 #dgg74 ,trenton limestone1 and other ,lower ,silurian groups of ,north ,america 7p4 #dgi74 ,lower ,silurian of ,sweden 7p4 #dgg74 ,,cambrian #bg4 ,,upper ,,cambrian4 ,british ,tremadoc slates 7p4 #dhc74 ,lingula flags1 with ,lingula ,davisii 7p4 #dhd74 ,foreign 8,primordial0 zone of ,bohemia in part1 with trilobites of the genera ,paradoxides1 etc4 7p4 #dhg74 ,alum schists of ,sweden and ,norway 7p4 #dhi74 ,potsdam sandstone1 with ,dikelocephalus and ,obolella 7p4 #dhi74 #bh4 ,,lower ,,cambrian4 ,british ,menevian beds of ,wales1 with ,paradoxides ,davidis1 etc4 7p4 #dhd74 ,longmynd group1 comprising the ,harlech grits and ,llanberis slates 7p4 #dhe74 ,foreign ,lower portion of ,barrande's 8,primordial0 zone in ,bohemia 7p4 #dhf74 ,fucoid sandstones of ,sweden 7p4 #dhi74 ,huronian series of ,canada8 7p4 #dij74 ,,laurentian #bi4 ,,upper ,,laurentian4 ,british ,fundamental gneiss of the ,hebrides8 7p4 #dic74 ,hypersthene rocks of ,skye8 7p4 #dia74 ,foreign ,labradorite series north of the river ,st4 ,lawrence in ,canada 7p4 #dia74 ,adirondack mountains of ,new ,york 7p4 #dia74 #cj4 ,,lower ,,laurentian4 ,british ,wanting8 ,foreign ,beds of gneiss and quartzite1 with interstratified limestones1 in one of which1 #ajjj feet thick1 occurs a foraminifer1 ,eozoon ,canadense1 the oldest known fossil 7p4 #dia74 ,,chapter ,,ix4 ,,classification ,,of ,,tertiary ,,formations4 ,order of ,succession of ,sedimentary ,formations4 -- ,frequent ,unconformability of ,strata4 -- ,imperfection of the ,record4 -- ,defectiveness of the ,monuments greater in ,proportion to their ,antiquity4 -- ,reasons for studying the newer ,groups first4 -- ,nomenclature of ,formations4 -- ,detached ,tertiary ,formations scattered over ,europe4 -- ,value of the ,shell-bearing ,mollusca in ,classification4 -- ,classification of ,tertiary ,strata4 -- ,eocene1 ,miocene1 and ,pliocene ,terms explained4 ,by reference to the tables given at the end of the last chapter the reader will see that when the fossiliferous rocks are arranged chronologically1 we have first to consider the ,post-tertiary and then the ,tertiary or ,cainozoic formations1 and afterwards to pass on to those of older date4 ,fig4 #hf3 ,order of ,superposition of ,deposits ,order of ,superposition4--,the diagram 7,fig4 #hf7 will show the order of superposition of these deposits1 assuming them all to be visible in one continuous section4 ,in nature1 as before hinted 7p4 #ajg71 we have never an opportunity of seeing the whole of them so displayed in a single region2 first1 because sedimentary deposition is confined1 during any one geological period1 to limited areas2 and secondly1 because strata1 after they have been formed1 are liable to be utterly annihilated over wide areas by denudation4 ,but wherever certain members of the series are present1 they overlie one another in the order indicated in the diagram1 though not always in the exact manner there represented1 because some of them repose occasionally in unconformable stratification on others4 ,this mode of superposition has been already explained 7p4 #id1 p4 #aaa71 where ,i pointed out that the discordance which implies a considerable lapse of time between two formations in juxtaposition is almost invariably accompanied by a great dissimilarity in the species of organic remains4 ,frequent ,unconformability of ,strata4--,where the widest gaps appear in the sequence of the fossil forms1 as between the ,permian and ,triassic rocks1 or between the ,cretaceous and ,eocene1 examples of such unconformability are very frequent4 ,but they are also met with in some part or other of the world at the junction of almost all the other principal formations1 and sometimes the subordinate divisions of any one of the leading groups may be found lying unconformably on another subordinate member of the same--the ,upper1 for example1 on the ,lower ,silurian1 or the superior division of the ,old ,red ,sandstone on a lower member of the same1 and so forth4 ,instances of such irregularities in the mode of succession of the strata are the more intelligible the more we extend our survey of the fossiliferous formations1 for we are continually bringing to light deposits of intermediate date1 which have to be intercalated between those previously known1 and which reveal to us a long series of events1 of which antecedently to such discoveries we had no knowledge4 ,but while unconformability invariably bears testimony to a lapse of unrepresented time1 the conformability of two sets of strata in contact by no means implies that the newer formation immediately succeeded the older one4 ,it simply implies that the ancient rocks were subjected to no movements of such a nature as to tilt1 bend1 or break them before the more modern formation was superimposed4 ,it does not show that the earth's crust was motionless in the region in question1 for there may have been a gradual sinking or rising1 extending uniformly over a large surface1 and yet1 during such movement1 the stratified rocks may have retained their original horizontality of position4 ,there may have been a conversion of a wide area from sea into land and from land into sea1 and during these changes of level some strata may have been slowly removed by aqueous action1 and after this new strata may be superimposed1 differing perhaps in date by thousands of years or centuries1 and yet resting conformably on the older set4 ,there may even be a blending of the materials constituting the older deposit with those of the newer1 so as to give rise to a passage in the mineral character of the one rock into the other as if there had been no break or interruption in the depositing process4 ,imperfection of the ,record4--,although by the frequent discovery of new sets of intermediate strata the transition from one type of organic remains to another is becoming less and less abrupt1 yet the entire series of records appears to the geologists now living far more fragmentary and defective than it seemed to their predecessors half a century ago4 ,the earlier inquirers1 as often as they encountered a break in the regular sequence of formations1 connected it theoretically with a sudden and violent catastrophe1 which had put an end to the regular course of events that had been going on uninterruptedly for ages1 annihilating at the same time all or nearly all the organic beings which had previously flourished1 after which1 order being re-established1 a new series of events was initiated4 ,in proportion as our faith in these views grows weaker1 and the phenomena of the organic or inorganic world presented to us by geology seem explicable on the hypothesis of gradual and insensible changes1 varied only by occasional convulsions1 on a scale comparable to that witnessed in historical times2 and in proportion as it is thought possible that former fluctuations in the organic world may be due to the indefinite modifiability of species without the necessity of assuming new and independent acts of creation1 the number and magnitude of the gaps which still remain1 or the extreme imperfection of the record1 become more and more striking1 and what we possess of the ancient annals of the earth's history appears as nothing when contrasted with that which has been lost4 ,when we examine a large area such as ,europe1 the average as well as the extreme height above the sea attained by the older formations is usually found to exceed that reached by the more modern ones1 the primary or palaeozoic rising higher than the secondary1 and these in their turn than the tertiary2 while in reference to the three divisions of the tertiary1 the lowest or ,eocene group attains a higher summit-level than the ,miocene1 and these again a greater height than the ,pliocene formations4 ,lastly1 the post-tertiary deposits1 such1 at least1 as are of marine origin1 are most commonly restricted to much more moderate elevations above the sea-level than the tertiary strata4 ,it is also observed that strata1 in proportion as they are of newer date1 bear the nearest resemblance in mineral character to those which are now in the progress of formation in seas or lakes1 the newest of all consisting principally of soft mud or loose sand1 in some places full of shells1 corals1 or other organic bodies1 animal or vegetable1 in others wholly devoid of such remains4 ,the farther we recede from the present time1 and the higher the antiquity of the formations which we examine1 the greater are the changes which the sedimentary deposits have undergone4 ,time1 as ,i have explained in ,chapters ,v1 ,,vi1 and ,,vii1 has multiplied the effects of condensation by pressure and cementation1 and the modification produced by heat1 fracture1 contortion1 upheaval1 and denudation4 ,the organic remains also have sometimes been obliterated entirely1 or the mineral matter of which they were composed has been removed and replaced by other substances4 ,why newer ,groups should be studied first4--,we likewise observe that the older the rocks the more widely do their organic remains depart from the types of the living creation4 ,first1 we find in the newer tertiary rocks a few species which no longer exist1 mixed with many living ones1 and then1 as we go farther back1 many genera and families at present unknown make their appearance1 until we come to strata in which the fossil relics of existing species are nowhere to be detected1 except a few of the lowest forms of invertebrate1 while some orders of animals and plants wholly unrepresented in the living world begin to be conspicuous4 ,when we study1 therefore1 the geological records of the earth and its inhabitants1 we find1 as in human history1 the defectiveness and obscurity of the monuments always increasing the remoter the era to which we refer1 and the difficulty of determining the true chronological relations of rocks is more and more enhanced1 especially when we are comparing those which were formed simultaneously in very distant regions of the globe4 ,hence we advance with securer steps when we begin with the study of the geological records of later times1 proceeding from the newer to the older1 or from the more to the less known4 ,in thus inverting what might at first seem to be the more natural order of historical research1 we must bear in mind that each of the periods above enumerated1 even the shortest1 such as the ,post-tertiary1 or the ,pliocene1 ,miocene1 or ,eocene1 embrace a succession of events of vast extent1 so that to give a satisfactory account of what we already know of any one of them would require many volumes4 ,when1 therefore1 we approach one of the newer groups before endeavouring to decipher the monuments of an older one1 it is like endeavouring to master the history of our own country and that of some contemporary nations1 before we enter upon ,roman ,history1 or like investigating the annals of ,ancient ,italy and ,greece before we approach those of ,egypt and ,assyria4 ,nomenclature4--,the origin of the terms ,primary and ,secondary1 and the synonymous terms ,palaeozoic1 and ,mesozoic1 were explained in ,chapter ,,viii1 p4 #abc4 ,the ,tertiary or ,cainozoic strata 7see p4 #abc7 were so called because they were all posterior in date to the ,secondary series1 of which last the ,chalk of ,cretaceous1 ,no4 #i1 ,fig4 #hf1 constitutes the newest group4 ,the whole of them were at first confounded with the superficial alluviums of ,europe2 and it was long before their real extent and thickness1 and the various ages to which they belong1 were fully recognised4 ,they were observed to occur in patches1 some of fresh-water1 others of marine origin1 their geographical area being usually small as compared to the secondary formations1 and their position often suggesting the idea of their having been deposited in different bays1 lakes1 estuaries1 or inland seas1 after a large portion of the space now occupied by ,europe had already been converted into dry land4 ,the first deposits of this class1 of which the characters were accurately determined1 were those occurring in the neighbourhood of ,paris1 described in #ahaj by ,,mm4 ,cuvier and ,brongniart4 ,they were ascertained to consist of successive sets of strata1 some of marine1 others of fresh-water origin1 lying one upon the other4 ,the fossil shells and corals were perceived to be almost all of unknown species1 and to have in general a near affinity to those now inhabiting warmer seas4 ,the bones and skeletons of land animals1 some of them of large size1 and belonging to more than forty distinct species1 were examined by ,cuvier1 and declared by him not to agree specifically1 nor most of them even generically1 with any hitherto observed in the living creation4 ,strata were soon afterwards brought to light in the vicinity of ,london1 and in ,hampshire1 which1 although dissimilar in mineral composition1 were justly inferred by ,mr4 ,t4 ,webster to be of the same age as those of ,paris1 because the greater number of the fossil shells were specifically identical4 ,for the same reason1 rocks found on the ,gironde1 in the ,south of ,france1 and at certain points in the ,north of ,italy1 were suspected to be of contemporaneous origin4 ,another important discovery was soon afterwards made by ,brocchi in ,italy1 who investigated the argillaceous and sandy deposits1 replete with shells1 which form a low range of hills1 flanking the ,apennines on both sides1 from the plains of the ,po to ,calabria4 ,these lower hills were called by him the ,subapennines1 and were formed of strata chiefly marine1 and newer than those of ,paris and ,london4 ,another tertiary group occurring in the neighbourhood of ,bordeaux and ,dax1 in the ,south of ,france1 was examined by ,m4 de ,basterot in #ahbe1 who described and figured several hundred species of shells1 which differed for the most part both from the ,parisian series and those of the ,subapennine hills4 ,it was soon1 therefore1 suspected that this fauna might belong to a period intermediate between that of the ,parisian and ,subapennine strata1 and it was not long before the evidence of superposition was brought to bear in support of this opinion2 for other strata1 contemporaneous with those of ,bordeaux1 were observed in one district 7the ,valley of the ,loire71 to overlie the ,parisian formation1 and in another 7in ,piedmont7 to underlie the ,subapennine beds4 ,the first example of these was pointed out in #ahbi by ,m4 ,desnoyers1 who ascertained that the sand and marl of marine origin called faluns1 near ,tours1 in the basin of the ,loire1 full of sea-shells and corals1 rested upon a lacustrine formation1 which constitutes the uppermost subdivision of the ,parisian group1 extending continuously throughout a great table-land intervening between the basin of the ,seine and that of the ,loire4 ,the other example occurs in ,italy1 where strata containing many fossils similar to those of ,bordeaux were observed by ,bonelli and others in the environs of ,turin1 subjacent to strata belonging to the ,subapennine group of ,brocchi4 ,value of ,testacean ,fossils in ,classification4--,it will be observed that in the foregoing allusions to organic remains1 the testacea or the shell-bearing mollusca are selected as the most useful and convenient class for the purposes of general classification4 ,in the first place1 they are more universally distributed through strata of every age than any other organic bodies4 ,those families of fossils which are of rare and casual occurrence are absolutely of no avail in establishing a chronological arrangement4 ,if we have plants alone in one group of strata and the bones of mammalia in another1 we can draw no conclusion respecting the affinity or discordance of the organic beings of the two epochs compared2 and the same may be said if we have plants and vertebrated animals in one series and only shells in another4 ,although corals are more abundant1 in a fossil state1 than plants1 reptiles1 or fish1 they are still rare when contrasted with shells1 because they are more dependent for their well-being on the constant clearness of the water1 and are1 therefore1 less likely to be included in rocks which endure in consequence of their thickness and the copiousness of sediment which prevailed when they originated4 ,the utility of the testacea is1 moreover1 enhanced by the circumstance that some forms are proper to the sea1 others to the land1 and others to fresh water4 ,rivers scarcely ever fail to carry down into their deltas some land-shells1 together with species which are at once fluviatile and lacustrine4 ,by this means we learn what terrestrial1 fresh-water1 and marine species coexisted at particular eras of the past3 and having thus identified strata formed in seas with others which originated contemporaneously in inland lakes1 we are then enabled to advance a step farther1 and show that certain quadrupeds or aquatic plants1 found fossil in lacustrine formations1 inhabited the globe at the same period when certain fish1 reptiles1 and zoophytes lived in the ocean4 ,among other characters of the molluscous animals1 which render them extremely valuable in settling chronological questions in geology1 may be mentioned1 first1 the wide geographical range of many species2 and1 secondly1 what is probably a consequence of the former1 the great duration of species in this class1 for they appear to have surpassed in longevity the greater number of the mammalia and fish4 ,had each species inhabited a very limited space1 it could never1 when imbedded in strata1 have enabled the geologist to identify deposits at distant points2 or had they each lasted but for a brief period1 they could have thrown no light on the connection of rocks placed far from each other in the chronological1 or1 as it is often termed1 vertical series4 ,classification of ,tertiary ,strata4--,many authors have divided the ,european ,tertiary strata into three groups--lower1 middle1 and upper2 the lower comprising the oldest formations of ,paris and ,london before mentioned2 the middle those of ,bordeaux and ,touraine2 and the upper all those newer than the middle group4 ,in the first edition of the ,principles of ,geology1 ,i divided the whole of the ,tertiary formations into four groups1 characterised by the percentage of recent shells which they contained4 ,the lower tertiary strata of ,london and ,paris were thought by ,m4 ,deshayes to contain only #c per cent of recent species1 and were termed ,eocene4 ,the middle tertiary of the ,loire and ,gironde had1 according to the specific determinations of the same conchologist1 #ag per cent1 and formed the ,miocene division4 ,the ,subapennine beds contained #ce to #ej per cent1 and were termed ,older ,pliocene1 while still more recent beds in ,sicily1 which had from #ij to #ie per cent of species identical with those now living1 were called ,newer ,pliocene4 ,the first of the above terms1 ,eocene1 is derived from eos1 dawn1 and cainos1 recent1 because the fossil shells of this period contain an extremely small proportion of living species1 which may be looked upon as indicating the dawn of the existing state of the testaceous fauna1 no recent species having been detected in the older or secondary rocks4 ,the term ,miocene 7from meion1 less1 and cainos1 recent7 is intended to express a minor proportion of recent species 7of testacea71 the term ,pliocene 7from pleion1 more1 and cainos1 recent7 a comparative plurality of the same4 ,it may assist the memory of students to remind them1 that the ,miocene contain a minor proportion1 and ,pliocene a comparative plurality of recent species2 and that the greater number of recent species always implies the more modern origin of the strata4 ,it has sometimes been objected to this nomenclature that certain species of infusoria found in the chalk are still existing1 and1 on the other hand1 the ,miocene and ,older ,pliocene deposits often contain the remains of mammalia1 reptiles1 and fish1 exclusively of extinct species4 ,but the reader must bear in mind that the terms ,eocene1 ,miocene1 and ,pliocene were originally invented with reference purely to conchological data1 and in that sense have always been and are still used by me4 ,since the year #ahcj the number of known shells1 both recent and fossil1 has largely increased1 and their identification has been more accurately determined4 ,hence some modifications have been required in the classifications founded on less perfect materials4 ,the ,eocene1 ,miocene1 and ,pliocene periods have been made to comprehend certain sets of strata of which the fossils do not always conform strictly in the proportion of recent to extinct species with the definitions first given by me1 or which are implied in the etymology of those terms4 ,,chapter ,x4 ,,recent ,,and ,,post-,,pliocene ,,periods4 ,recent and ,post-pliocene ,periods4 -- ,terms defined4 -- ,formations of the ,recent ,period4 -- ,modern littoral ,deposits containing ,works of ,art near ,naples4 -- ,danish ,peat and ,shell-mounds4 -- ,swiss ,lake-dwellings4 -- ,periods of ,stone1 ,bronze1 and ,iron4 -- ,post-pliocene ,formations4 -- ,coexistence of ,man with extinct ,mammalia4 -- ,reindeer ,period of ,south of ,france4 -- ,alluvial ,deposits of ,paleolithic ,age4 -- ,higher and ,lower-level ,valley-gravels4 -- ,loess or ,inundation-mud of the ,nile1 ,rhine1 etc4 -- ,origin of ,caverns4 -- ,remains of ,man and extinct ,quadrupeds in ,cavern ,deposits4 -- ,cave of ,kirkdale4 -- ,australian ,cave-breccias4 -- ,geographical ,relationship of the ,provinces of living ,vertebrata and those of extinct ,post-pliocene ,species4 -- ,extinct struthious ,birds of ,new ,zealand4 -- ,climate of the ,post-pliocene ,period4 -- ,comparative ,longevity of ,species in the ,mammalia and ,testacea4 -- ,teeth of ,recent and ,post-pliocene ,mammalia4 ,we have seen in the last chapter that the uppermost or newest strata are called ,post-tertiary1 as being more modern than the ,tertiary4 ,it will also be observed that the ,post-tertiary formations are divided into two subordinate groups3 the ,recent1 and ,post-pliocene4 ,in the former1 or the ,recent1 the mammalia as well as the shells are identical with species now living3 whereas in the ,post-pliocene1 the shells being all of living forms1 a part1 and often a considerable part1 of the mammalia belonged to extinct species4 ,to this nomenclature it may be objected that the term ,post-pliocene should in strictness include all geological monuments posterior in date to the ,pliocene2 but when ,i have occasion to speak of the whole collectively1 ,i shall call them ,post-tertiary1 and reserve the term ,post-pliocene for the older ,post-tertiary formations1 while the ,upper or newer ones will be called 8,recent40 ,cases will occur where it may be scarcely possible to draw the boundary line between the ,recent and ,post-pliocene deposits2 and we must expect these difficulties to increase rather than diminish with every advance in our knowledge1 and in proportion as gaps are filled up in the series of records4 ,,recent ,,period ,it was stated in the sixth chapter1 when ,i treated of denudation1 that the dry land1 or that part of the earth's surface which is not covered by the waters of lakes or seas1 is generally wasting away by the incessant action of rain and rivers1 and in some cases by the undermining and removing power of waves and tides on the sea-coast4 ,but the rate of waste is very unequal1 since the level and gently sloping lands1 where they are protected by a continuous covering of vegetation1 escape nearly all wear and tear1 so that they may remain for ages in a stationary condition1 while the removal of matter is constantly widening and deepening the intervening ravines and valleys4 ,the materials1 both fine and coarse1 carried down annually by rivers from the higher regions to the lower1 and deposited in successive strata in the basins of seas and lakes1 must be of enormous volume4 ,we are always liable to underrate their magnitude1 because the accumulation of strata is going on out of sight4 ,there are1 however1 causes at work which1 in the course of centuries1 tend to render visible these modern formations1 whether of marine or lacustrine origin4 ,for a large portion of the earth's crust is always undergoing a change of level1 some areas rising and others sinking at the rate of a few inches1 or a few feet1 perhaps sometimes yards1 in a century2 so that spaces which were once subaqueous are gradually converted into land1 and others which were high and dry become submerged4 ,in consequence of such movements we find in certain regions1 as in ,cashmere1 for example1 where the mountains are often shaken by earthquakes1 deposits which were formed in lakes in the historical period1 but through which rivers have now cut deep and wide channels4 ,in lacustrine strata thus intersected1 works of art and fresh-water shells are seen4 ,in other districts on the borders of the sea1 usually at very moderate elevations above its level1 raised beaches occur1 or marine littoral deposits1 such as those in which1 on the borders of the ,bay of ,bai1 near ,naples1 the well-known temple of ,serapis was imbedded4 ,in that case the date of the monument buried in the marine strata is ascertainable1 but in many other instances the exact age of the remains of human workmanship is uncertain1 as in the estuary of the ,clyde at ,glasgow1 where many canoes have been exhumed1 with other works of art1 all assignable to some part of the ,recent ,period4 ,danish ,peat and ,shell-mounds or ,kitchen-middens4--,sometimes we obtain evidence1 without the aid of a change of level1 of events which took place in pre-historic times4 ,the combined labours1 for example1 of the antiquary1 zoologist1 and botanist have brought to light many monuments of the early inhabitants buried in peat-mosses in ,denmark4 ,their geological age is determined by the fact that1 not only the contemporaneous fresh-water and land shells1 but all the quadrupeds1 found in the peat1 agree specifically with those now inhabiting the same districts1 or which are known to have been indigenous in ,denmark within the memory of man4 ,in the lower beds of peat 7a deposit varying from #bj to #cj feet in thickness71 weapons of stone accompany trunks of the ,scotch fir1 ,pinus sylvestris4 ,this peat may be referred to that part of the stone period for which ,sir ,john ,lubbock proposed the name of 8,neolithic0#a in contradistinction to a still older era1 termed by him 8,paleolithic10 and which will be described in the sequel4 ,in the higher portions of the same ,danish bogs1 bronze implements are associated with trunks and acorns of the common oak4 ,it appears that the pine has never been a native of ,denmark in historical times1 and it seems to have given place to the oak about the time when articles and instruments of bronze superseded those of stone4 ,it also appears that1 at a still later period1 the oak itself became scarce1 and was nearly supplanted by the beech1 a tree which now flourishes luxuriantly in ,denmark4 ,again1 at the still later epoch when the beech-tree abounded1 tools of iron were introduced1 and were gradually substituted for those of bronze4 ,on the coasts of the ,danish islands in the ,baltic1 certain mounds1 called in those countries 8,kjkken-mdding10 or 8kitchen-middens10 occur1 consisting chiefly of the castaway shells of the oyster1 cockle1 periwinkle1 and other eatable kinds of molluscs4 ,the mounds are from three to ten feet high1 and from #ajj to #ajjj feet in their longest diameter4 ,they greatly resemble heaps of shells formed by the ,red ,indians of ,north ,america along the eastern shores of the ,united ,states4 ,in the old refuse-heaps1 recently studied by the ,danish antiquaries and naturalists with great skill and diligence1 no implements of metal have ever been detected4 ,all the knives1 hatchets1 and other tools1 are of stone1 horn1 bone1 or wood4 ,with them are often intermixed fragments of rude pottery1 charcoal and cinders1 and the bones of quadrupeds on which the rude people fed4 ,these bones belong to wild species still living in ,europe1 though some of them1 like the beaver1 have long been extirpated in ,denmark4 ,the only animal which they seem to have domesticated was the dog4 ,as there is an entire absence of metallic tools1 these refuse-heaps are referred to the ,neolithic division of the age of stone1 which immediately preceded in ,denmark the age of bronze4 ,it appears that a race more advanced in civilisation1 armed with weapons of that mixed metal1 invaded ,scandinavia1 and ousted the aborigines4 ,lacustrine ,habitations of ,switzerland4--,in ,switzerland a different class of monuments1 illustrating the successive ages of stone1 bronze1 and iron1 has been of late years investigated with great success1 and especially since #ahed1 in which year ,dr4 ,f4 ,keller explored near the shore at ,meilen1 in the bottom of the lake of ,zurich1 the ruins of an old village1 originally built on numerous wooden piles1 driven1 at some unknown period1 into the muddy bed of the lake4 ,since then a great many other localities1 more than a hundred and fifty in all1 have been detected of similar pile-dwellings1 situated near the borders of the ,swiss lakes1 at points where the depth of water does not exceed #ae feet4#b ,the superficial mud in such cases is filled with various articles1 many hundreds of them being often dredged up from a very limited area4 ,thousands of piles1 decayed at their upper extremities1 are often met with still firmly fixed in the mud4 ,as the ages of stone1 bronze1 and iron merely indicate successive stages of civilisation1 they may all have coexisted at once in different parts of the globe1 and even in contiguous regions1 among nations having little intercourse with each other4 ,to make out1 therefore1 a distinct chronological series of monuments is only possible when our observations are confined to a limited district1 such as ,switzerland4 ,the relative antiquity of the pile-dwellings1 which belong respectively to the ages of stone and bronze1 is clearly illustrated by the associations of the tools with certain groups of animal remains4 ,where the tools are of stone1 the castaway bones which served for the food of the ancient people are those of deer1 the wild boar1 and wild ox1 which abounded when society was in the hunter state4 ,but the bones of the later or bronze epoch were chiefly those of the domestic ox1 goat1 and pig1 indicating progress in civilisation4 ,some villages of the stone age are of later date than others1 and exhibit signs of an improved state of the arts4 ,among their relics are discovered carbonised grains of wheat and barley1 and pieces of bread1 proving that the cultivation of cereals had begun4 ,in the same settlements1 also1 cloth1 made of woven flax and straw1 has been detected4 ,the pottery of the bronze age in ,switzerland is of a finer texture1 and more elegant in form1 than that of the age of stone4 ,at ,nidau1 on the lake of ,bienne1 articles of iron have also been discovered1 so that this settlement was evidently not abandoned till that metal had come into use4 ,at ,la ,thne1 in the northern angle of the lake of ,neufchtel1 a great many articles of iron have been obtained1 which in form and ornamentation are entirely different both from those of the bronze period and from those used by the ,romans4 ,gaulish and ,celtic coins have also been found there by ,,mm4 ,schwab and ,desor4 ,they agree in character with remains1 including many iron swords1 which have been found at ,tiefenau1 near ,berne1 in ground supposed to have been a battle-field2 and their date appears to have been anterior to the great ,roman invasion of ,northern ,europe1 though perhaps not long before that event4#c ,coins1 which sometimes occur in deposits of the age of iron1 have never yet been found in formations of the ages of bronze or stone4 ,the period of bronze must have been one of foreign commerce1 as tin1 which enters into this metallic mixture in the proportion of about ten per cent to the copper1 was obtained by the ancients chiefly from ,cornwall4#d ,very few human bones of the bronze period have been met with in the ,danish peat1 or in the ,swiss lake-dwellings1 and this scarcity is generally attributed by archologists to the custom of burning the dead1 which prevailed in the age of bronze4 ,,post-,,pliocene ,,period ,from the foregoing observations we may infer that the ages of iron and bronze in ,northern and ,central ,europe were preceded by a stone age1 the ,neolithic1 referable to that division of the post-tertiary epoch which ,i have called ,recent1 when the mammalia as well as the other organic remains accompanying the stone implements were of living species4 ,but memorials have of late been brought to light of a still older age of stone1 for which1 as above stated1 the name ,paleolithic has been proposed1 when man was contemporary in ,europe with the elephant and rhinoceros1 and various other animals1 of which many of the most conspicuous have long since died out4 ,reindeer ,period in ,south of ,france4--,in the larger number of the caves of ,europe1 as for example in those of ,england1 ,belgium1 ,germany1 and many parts of ,france1 the animal remains agree specifically with the fauna of this oldest division of the age of stone1 or that to which belongs the drift of ,amiens and ,abbeville presently to be mentioned1 containing flint implements of a very antique type4 ,but there are some caves in the departments of ,dordogne1 ,aude1 and other parts of the south of ,france1 which are believed by ,m4 ,lartet to be of intermediate date between the ,paleolithic and ,neolithic periods4 ,to this intermediate era ,m4 ,lartet gave1 in #ahfc1 the name of the 8reindeer period10 because vast quantities of the bones and horns of that deer have been met with in the ,french caverns4 ,in some cases separate plates of molars of the mammoth1 and several teeth of the great ,irish deer1 ,cervus megaceros1 and of the cave-lion1 ,felis spela1 have been found mixed up with cut and carved bones of reindeer4 ,on one of these sculptured bones in the cave of ,perigord1 a rude representation of the mammoth1 with its long curved tusks and covering of wool1 occurs1 which is regarded by ,m4 ,lartet as placing beyond all doubt the fact that the early inhabitants of these caves must have seen this species of elephant still living in ,france4 ,the presence of the marmot1 as well as the reindeer and some other northern animals1 in these caverns seems to imply a colder climate than that of the ,swiss lake-dwellings1 in which no remains of reindeer have as yet been discovered4 ,the absence of this last in the old lacustrine habitations of ,switzerland is the more significant1 because in a cave in the neighbourhood of the lake of ,geneva1 namely1 that of ,mont ,saleve1 bones of the reindeer occur with flint implements similar to those of the caverns of ,dordogne and ,perigord4 ,the state of the arts1 as exemplified by the instruments found in these caverns of the reindeer period1 is somewhat more advanced than that which characterises the tools of the ,amiens drift1 but is nevertheless more rude than that of the ,swiss lake-dwellings4 ,no metallic articles occur1 and the stone hatchets are not ground after the fashion of celts2 the needles of bone are shaped in a workmanlike style1 having their eyes drilled with consummate skill4 ,the formations above alluded to1 which are as yet but imperfectly known1 may be classed as belonging to the close of the ,paleolithic era1 of the monuments of which ,i am now about to treat4 ,alluvial ,deposits of the ,paleolithic ,age4--,the alluvial and marine deposits of the ,paleolithic age1 the earliest to which any vestiges of man have yet been traced back1 belong to a time when the physical geography of ,europe differed in a marked degree from that now prevailing4 ,in the ,neolithic period1 the valleys and rivers coincided almost entirely with those by which the present drainage of the land is effected1 and the peat-mosses were the same as those now growing4 ,the situation of the shell-mounds and lake-dwellings above alluded to is such as to imply that the topography of the districts where they are observed has not subsequently undergone any material alteration4 ,whereas we no sooner examine the ,post-pliocene formations1 in which the remains of so many extinct mammalia are found1 than we at once perceive a more decided discrepancy between the former and present outline of the surface4 ,since those deposits originated1 changes of considerable magnitude have been effected in the depth and width of many valleys1 as also in the direction of the superficial and subterranean drainage1 and1 as is manifest near the sea-coast1 in the relative position of land and water4 ,in ,fig4 #hg an ideal section is given1 illustrating the different position which the ,recent and ,post-pliocene alluvial deposits occupy in many ,european valleys4 ,fig4 #hg3 ,recent and ,post-pliocene alluvial deposits4 ,the peat1 ,no4 #a1 has been formed in a low part of the modern alluvial plain1 in parts of which gravel ,no4 #b of the recent period is seen4 ,over this gravel the loam or fine sediment #b has in many places been deposited by the river during floods which covered nearly the whole alluvial plain4 ,no4 #c represents an older alluvium1 composed of sand and gravel1 formed before the valley had been excavated to its present depth4 ,it contains the remains of fluviatile shells of living species associated with the bones of mammalia1 in part of recent1 and in part of extinct species4 ,among the latter1 the mammoth 7,e4 primigenius7 and the ,siberian rhinoceros 7,r4 tichorhinus7 are the most common in ,europe4 ,no4 #c is a remnant of the loam or brick-earth by which ,no4 #c was overspread4 ,no4 #d is a still older and more elevated terrace1 similar in its composition and organic remains to ,no4 #c1 and covered in like manner with its inundation-mud1 #d4 ,sometimes the valley-gravels of older date are entirely missing1 or there is only one1 and occasionally there are more than two1 marking as many successive stages in the excavation of the valley4 ,they usually occur at heights varying from #aj to #ajj feet1 sometimes on the right and sometimes on the left side of the existing river-plain1 but rarely in great strength on exactly opposite sides of the valley4 ,among the genera of extinct quadrupeds most frequently met with in ,england1 ,france1 ,germany1 and other parts of ,europe1 are the elephant1 rhinoceros1 hippopotamus1 horse1 great ,irish deer1 bear1 tiger1 and hyna4 ,in the peat1 ,no4 #a 7,fig4 #hg71 and in the more modern gravel and silt 7,no4 #b71 works of art of the ages of iron and bronze1 and of the later or ,neolithic stone period1 already described1 are met with4 ,in the more ancient or ,paleolithic gravels1 #c and #d1 there have been found of late years in several valleys in ,france and ,england--as1 for example1 in those of the ,seine and ,somme1 and of the ,thames and ,ouse1 near ,bedford--stone implements of a rude type1 showing that man coexisted in those districts with the mammoth and other extinct quadrupeds of the genera above enumerated4 ,in #ahdg1 ,m4 ,boucher de ,perthes observed in an ancient alluvium at ,abbeville1 in ,picardy1 the bones of extinct mammalia associated in such a manner with flint implements of a rude type as to lead him to infer that both the organic remains and the works of art were referable to one and the same period4 ,this inference was soon after confirmed by ,mr4 ,prestwich1 who found in #ahei a flint tool in situ in the same stratum at ,amiens that contained the remains of extinct mammalia4 ,the flint implements found at ,abbeville and ,amiens are most of them considered to be hatchets and spear-heads1 and are different from those commonly called 8celts40 ,these celts1 so often found in the recent formations1 have a more regular oblong shape1 the result of grinding1 by which also a sharp edge has been given to them4 ,the ,abbeville tools found in gravel at different levels1 as in ,nos4 #c and #d1 ,fig4 #hg1 in which bones of the elephant1 rhinoceros1 and other extinct mammalia occur1 are always unground1 having evidently been brought into their present form simply by the chipping off of fragments of flint by repeated blows1 such as could be given by a stone hammer4 ,some of them are oval1 others of a spear-headed form1 no two exactly alike1 and yet the greater number of each kind are obviously fashioned after the same general pattern4 ,their outer surface is often white1 the original black flint having been discoloured and bleached by exposure to the air1 or by the action of acids1 as they lay in the gravel4 ,they are most commonly stained of the same ochreous colour as the flints of the gravel in which they are imbedded4 ,occasionally their antiquity is indicated not only by their colour but by superficial incrustations of carbonate of lime1 or by dendrites formed of oxide of iron and manganese4 ,the edges also of most of them are worn1 sometimes by having been used as tools1 or sometimes by having been rolled in the old river's bed4 ,they are met with not only in the lower-level gravels1 as in ,no4 #c1 ,fig4 #hg1 but also in ,no4 #d1 or the higher gravels1 as at ,st4 ,acheul1 in the suburbs of ,amiens1 where the old alluvium lies at an elevation of about #ajj feet above the level of the river ,somme4 ,at both levels fluviatile and land-shells are met with in the loam as well as in the gravel1 but there are no marine shells associated1 except at ,abbeville1 in the lowest part of the gravel1 near the sea1 and a few feet only above the present high-water mark4 ,here with fossil shells of living species are mingled the bones of ,elephas primigenius and ,e4 antiquus1 ,rhinoceros tichorhinus1 ,hippopotamus1 ,felis spela1 ,hyna spela1 reindeer1 and many others1 the bones accompanying the flint implements in such a manner as to show that both were buried in the old alluvium at the same period4 ,nearly the entire skeleton of a rhinoceros was found at one point1 namely1 in the ,menchecourt drift at ,abbeville1 the bones being in such juxtaposition as to show that the cartilage must have held them together at the time of their inhumation4 ,the general absence here and elsewhere of human bones from gravel and sand in which flint tools are discovered1 may in some degree be due to the present limited extent of our researches4 ,but it may also be presumed that when a hunter population1 always scanty in numbers1 ranged over this region1 they were too wary to allow themselves to be overtaken by the floods which swept away many herbivorous animals from the low river-plains where they may have been pasturing or sleeping4 ,beasts of prey prowling about the same alluvial flats in search of food may also have been surprised more readily than the human tenant of the same region1 to whom the signs of a coming tempest were better known4 ,inundation-mud of ,rivers4--,brick-earth4--,fluviatile ,loam1 or ,loess4--,as a general rule1 the fluviatile alluvia of different ages 7,nos4 #b1 #c1 #d1 ,fig4 #hg7 are severally made up of coarse materials in their lower portions1 and of fine silt or loam in their upper parts4 ,for rivers are constantly shifting their position in the valley-plain1 encroaching gradually on one bank1 near which there is deep water1 and deserting the other or opposite side1 where the channel is growing shallower1 being destined eventually to be converted into land4 ,where the current runs strongest1 coarse gravel is swept along1 and where its velocity is slackened1 first sand1 and then only the finest mud1 is thrown down4 ,a thin film of this fine sediment is spread1 during floods1 over a wide area1 on one1 or sometimes on both sides1 of the main stream1 often reaching as far as the base of the bluffs or higher grounds which bound the valley4 ,of such a description are the well-known annual deposits of the ,nile1 to which ,egypt owes its fertility4 ,so thin are they1 that the aggregate amount accumulated in a century is said rarely to exceed five inches1 although in the course of thousands of years it has attained a vast thickness1 the bottom not having been reached by borings extending to a depth of #fj feet towards the central parts of the valley4 ,everywhere it consists of the same homogeneous mud1 destitute of stratification--the only signs of successive accumulation being where the ,nile has silted up its channel1 or where the blown sands of the ,libyan desert have invaded the plain1 and give rise to alternate layers of sand and mud4 ,in ,european river-loams we occasionally observe isolated pebbles and angular pieces of stone which have been floated by ice to the places where they now occur2 but no such coarse materials are met with in the plains of ,egypt4 ,in some parts of the valley of the ,rhine the accumulation of similar loam1 called in ,germany 8loess10 has taken place on an enormous scale4 ,its colour is yellowish-grey1 and very homogeneous2 and ,professor ,bischoff has ascertained1 by analysis1 that it agrees in composition with the mud of the ,nile4 ,although for the most part unstratified1 it betrays in some places marks of stratification1 especially where it contains calcareous concretions1 or in its lower part where it rests on subjacent gravel and sand which alternate with each other near the junction4 ,about a sixth part of the whole mass is composed of carbonate of lime1 and there is usually an intermixture of fine quartzose and micaceous sand4 ,although this loam of the ,rhine is unsolidified1 it usually terminates where it has been undermined by running water in a vertical cliff1 from the face of which shells of terrestrial1 fresh-water and amphibious mollusks project in relief4 ,these shells do not imply the permanent sojourn of a body of fresh water on the spot1 for the most aquatic of them1 the ,succinea1 inhabits marshes and wet grassy meadows4 ,the ,succinea elongata 7or ,s4 oblongata71 ,fig4 #hh1 is very characteristic both of the loess of the ,rhine and of some other ,european river-loams4 ,fig4 #hh3 ,succinea elongata2 ,fig4 #hi3 ,pupa muscorum 7,linn472 ,fig4 #ij3 ,helix hispida 7,linn47 7plebia74 ,among the land-shells of the ,rhenish loess1 ,helix hispida1 ,fig4 #ij1 and ,pupa muscorum1 ,fig4 #hi1 are very common4 ,both the terrestrial and aquatic shells are of most fragile and delicate structure1 and yet they are almost invariably perfect and uninjured4 ,they must have been broken to pieces had they been swept along by a violent inundation4 ,even the colour of some of the land-shells1 as that of ,helix nemoralis1 is occasionally preserved4 ,in parts of the valley of the ,rhine1 between ,bingen and ,basle1 the fluviatile loam or loess now under consideration is several hundred feet thick1 and contains here and there throughout that thickness land and amphibious shells4 ,as it is seen in masses fringing both sides of the great plain1 and as occasionally remnants of it occur in the centre of the valley1 forming hills several hundred feet in height1 it seems necessary to suppose1 first1 a time when it slowly accumulated2 and secondly1 a later period1 when large portions of it were removed1 or when the original valley1 which had been partially filled up with it1 was re-excavated4 ,such changes may have been brought about by a great movement of oscillation1 consisting first of a general depression of the land1 and then of a gradual re-elevation of the same4 ,the amount of continental depression which first took place in the interior1 must be imagined to have exceeded that of the region near the sea1 in which case the higher part of the great valley would have its alluvial plain gradually raised by an accumulation of sediment1 which would only cease when the subsidence of the land was at an end4 ,if the direction of the movement was then reversed1 and1 during the re-elevation of the continent1 the inland region nearest the mountains should rise more rapidly than that near the coast1 the river would acquire a denuding power sufficient to enable it to sweep away gradually nearly all the loam and gravel with which parts of its basin had been filled up4 ,terraces and hillocks of mud and sand would then alone remain to attest the various levels at which the river had thrown down and afterwards removed alluvial matter4 ,cavern ,deposits containing ,human ,remains and ,bones of ,extinct ,animals4--,in ,england1 and in almost all countries where limestone rocks abound1 caverns are found1 usually consisting of cavities of large dimensions1 connected together by low1 narrow1 and sometimes torturous galleries or tunnels4 ,these subterranean vaults are usually filled in part with mud1 pebbles1 and breccia1 in which bones occur belonging to the same assemblage of animals as those characterising the ,post-pliocene alluvia above described4 ,some of these bones are referable to extinct and others to living species1 and they are occasionally intermingled1 as in the valley-gravels1 with implements of one or other of the great divisions of the stone age1 and these are not unfrequently accompanied by human bones1 which are much more common in cavern deposits than in valley-alluvium4 ,each suite of caverns1 and the passages by which they communicate the one with the other1 afford memorials to the geologist of successive phases through which they must have passed4 ,first1 there was a period when the carbonate of lime was carried out gradually by springs2 secondly1 an era when engulfed rivers or occasional floods swept organic and inorganic debris into the subterranean hollows previously formed2 and thirdly1 there were such changes in the configuration of the region as caused the engulfed rivers to be turned into new channels1 and springs to be dried up1 after which the cave-mud1 breccia1 gravel1 and fossil bones would bear the same kind of relation to the existing drainage of the country as the older valley-drifts with their extinct mammalian remains and works of art bear to the present rivers and alluvial plains4 ,the quarrying away of large masses of ,carboniferous and ,devonian limestone1 near ,liege1 in ,belgium1 has afforded the geologist magnificent sections of some of these caverns1 and the former communication of cavities in the interior of the rocks with the old surface of the country by means of vertical or oblique fissures1 has been demonstrated in places where it would not otherwise have been suspected1 so completely have the upper extremities of these fissures been concealed by superficial drift1 while their lower ends1 which extended into the roofs of the caves1 are masked by stalactitic incrustations4 ,the origin of the stalactite is thus explained by the eminent chemist ,liebig4 ,mould or humus1 being acted on by moisture and air1 evolves carbonic acid1 which is dissolved by rain4 ,the rain-water1 thus impregnated1 permeates the porous limestone1 dissolves a portion of it1 and afterwards1 when the excess of carbonic acid evaporates in the caverns1 parts with the calcareous matter1 and forms stalactite4 ,even while caverns are still liable to be occasionally flooded such calcareous incrustations accumulate1 but it is generally when they are no longer in the line of drainage that a solid floor of hard stalagmite is formed on the bottom4 ,the late ,dr4 ,schmerling examined forty caves near ,liege1 and found in all of them the remains of the same fauna1 comprising the mammoth1 tichorhine rhinoceros1 cave-bear1 cave-hyna1 cave-lion1 and many others1 some of extinct and some of living species1 and in all of them flint implements4 ,in four or five caves only parts of human skeletons were met with1 comprising sometimes skulls with a few other bones1 sometimes nearly every part of the skeleton except the skull4 ,in one of the caves1 that of ,engihoul1 where ,schmerling had found the remains of at least three human individuals1 they were mingled in such a manner with bones of extinct mammalia1 as to leave no doubt on his mind 7in #ahcc7 of man having co-existed with them4 ,in #ahfj1 ,professor ,malaise1 of ,liege1 explored with me this same cave of ,engihoul1 and beneath a hard floor of stalagmite we found mud full of bones of extinct and recent animals1 such as ,schmerling had described1 and my companion1 persevering in his researches after ,i had returned to ,england1 extracted from the same deposit two human lower jaw-bones retaining their teeth4 ,the skulls from these ,belgian caverns display no marked deviation from the normal ,european type of the present day4 ,the careful investigations carried on by ,dr4 ,falconer1 ,mr4 ,pengelly1 and others1 in the ,brixham cave near ,torquay1 in #aheh1 demonstrated that flint knives were there imbedded in such a manner in loam underlying a floor of stalagmite as to prove that man had been an inhabitant of that region when the cave-bear and other members of the ancient post-pliocene fauna were also in existence4 ,the absence of gnawed bones had led ,dr4 ,schmerling to infer that none of the ,belgian caves which he explored had served as the dens of wild beasts2 but there are many caves in ,germany and ,england which have certainly been so inhabited1 especially by the extinct hyna and bear4 ,a fine example of a hyna's den was afforded by the cave of ,kirkdale1 so well described by the late ,dr4 ,buckland in his ,reliqui ,diluvian4 ,in that cave1 above twenty-five miles north-north-east of ,york1 the remains of about #cjj hynas1 belonging to individuals of every age1 were detected4 ,the species 7,hyna spela7 has been considered by palontologists as extinct2 it was larger than the fierce ,hyna crocuta of ,south ,africa1 which it closely resembled1 and of which it is regarded by ,mr4 ,boyd ,dawkins as a variety4 ,dr4 ,buckland1 after carefully examining the spot1 proved that the hynas must have lived there2 a fact attested by the quantity of their dung1 which1 as in the case of the living hyna1 is of nearly the same composition as bone1 and almost as durable4 ,in the cave were found the remains of the ox1 young elephant1 hippopotamus1 rhinoceros1 horse1 bear1 wolf1 hare1 water-rat1 and several birds4 ,all the bones have the appearance of having been broken and gnawed by the teeth of the hynas2 and they occur confusedly mixed in loam or mud1 or dispersed through a crust of stalagmite which covers it4 ,in these and many other cases it is supposed that portions of herbivorous quadrupeds have been dragged into caverns by beasts of prey1 and have served as their food--an opinion quite consistent with the known habits of the living hyna4 ,australian ,cave-breccias4--,ossiferous breccias are not confined to ,europe1 but occur in all parts of the globe2 and those discovered in fissures and caverns in ,australia correspond closely in character with what has been called the bony breccia of the ,mediterranean1 in which the fragments of bone and rock are firmly bound together by a red ochreous cement4 ,fig4 #ia3 ,part of a lower jaw of ,macropus atlas4 ,some of these caves were examined by the late ,sir ,t4 ,mitchell in the ,wellington ,valley1 about #baj miles west of ,sidney1 on the river ,bell1 one of the principal sources of the ,macquarie1 and on the ,macquarie itself4 ,the caverns often branch off in different directions through the rock1 widening and contracting their dimensions1 and the roofs and floors are covered with stalactite4 ,the bones are often broken1 but do not seem to be water-worn4 ,in some places they lie imbedded in loose earth1 but they are usually included in a breccia4 ,the remains belong to marsupial animals4 ,among the most abundant are those of the kangaroo1 of which there are four species1 while others belong to the genera ,phascolomys1 the wombat2 ,dasyurus71 the ursine opossum2 ,phalangista1 the vulpine opossum2 and ,hypsiprymnus1 the kangaroo-rat4 ,fig4 #ib3 ,lower jaw of largest living species of kangaroo4 ,in the fossils above enumerated1 several species are larger than the largest living ones of the same genera now known in ,australia4 ,fig4 #ia of the right side of a lower jaw of a kangaroo 7,macropus atlas1 ,owen7 will at once be seen to exceed in magnitude the corresponding part of the largest living kangaroo1 which is represented in ,fig4 #ib4 ,in both these specimens part of the substance of the jaw has been broken open1 so as to show the permanent false molar 7a1 ,fig4 #ia71 concealed in the socket4 ,from the fact of this molar not having been cut1 we learn that the individual was young1 and had not shed its first teeth4 ,the reader will observe that all these extinct quadrupeds of ,australia belong to the marsupial family1 or1 in other words1 that they are referable to the same peculiar type of organisation which now distinguishes the ,australian mammalia from those of other parts of the globe4 ,this fact is one of many pointing to a general law deducible from the fossil vertebrate and invertebrate animals of times immediately antecedent to our own1 namely1 that the present geographical distribution of organic forms dates back to a period anterior to the origin of existing species2 in other words1 the limitation of particular genera or families of quadrupeds1 mollusca1 etc41 to certain existing provinces of land and sea1 began before the larger part of the species now contemporary with man had been introduced into the earth4 ,professor ,owen1 in his excellent 8,history of ,british ,fossil ,mammals10 has called attention to this law1 remarking that the fossil quadrupeds of ,europe and ,asia differ from those of ,australia or ,south ,america4 ,we do not find1 for example1 in the ,europo-,asiatic province fossil kangaroos1 or armadillos1 but the elephant1 rhinoceros1 horse1 bear1 hyna1 beaver1 hare1 mole1 and others1 which still characterise the same continent4 ,in like manner1 in the ,pampas of ,south ,america the skeletons of ,megatherium1 ,megalonyx1 ,glyptodon1 ,mylodon1 ,toxodon1 ,macrauchenia1 and other extinct forms1 are analogous to the living sloth1 armadillo1 cavy1 capybara1 and llama4 ,the fossil quadrumana1 also associated with some of these forms in the ,brazilian caves1 belong to the ,platyrrhine family of monkeys1 now peculiar to ,south ,america4 ,that the extinct fauna of ,buenos ,ayres and ,brazil was very modern has been shown by its relation to deposits of marine shells1 agreeing with those now inhabiting the ,atlantic4 ,the law of geographical relationship above alluded to1 between the living vertebrata of every great zoological province and the fossils of the period immediately antecedent1 even where the fossil species are extinct1 is by no means confined to the mammalia4 ,new ,zealand1 when first examined by ,europeans1 was found to contain no indigenous land quadrupeds1 no kangaroos1 or opossums1 like ,australia2 but a wingless bird abounded there1 the smallest living representative of the ostrich family1 called the ,kiwi by the natives 7,apteryx74 ,in the fossils of the ,post-pliocene period in this same island1 there is the like absence of kangaroos1 opossums1 wombats1 and the rest2 but in their place a prodigious number of well-preserved specimens of gigantic birds of the struthious order1 called by ,owen ,dinornis and ,palapteryx1 which are entombed in superficial deposits4 ,these genera comprehended many species1 some of which were four1 some seven1 others nine1 and others eleven feet in height6 ,it seems doubtful whether any contemporary mammalia shared the land with this population of gigantic feathered bipeds4 ,mr4 ,darwin1 when describing the recent and fossil mammalia of ,south ,america1 has dwelt much on the wonderful relationship of the extinct to the living types in that part of the world1 inferring from such geographical phenomena that the existing species are all related to the extinct ones which preceded them by a bond of common descent4 ,climate of the ,post-pliocene ,period4--,the evidence as to the climate of ,europe during this epoch is somewhat conflicting4 ,the fluviatile and land-shells are all of existing species1 but their geographical range has not always been the same as at present4 ,some1 for example1 which then lived in ,britain are now only found in ,norway and ,finland1 probably implying that the ,post-pliocene climate of ,britain was colder1 especially in the winter4 ,so also the reindeer and the musk-ox 7,ovibos moschatus71 now inhabitants of the ,arctic regions1 occur fossil in the valleys of the ,thames and ,avon1 and also in ,france and ,germany1 accompanied in most places by the mammoth and the woolly rhinoceros4 ,at ,grays in ,essex1 on the other hand1 another species both of elephant and rhinoceros occurs1 together with a hippopotamus and the ,cyrena fluminalis1 a shell now extinct in ,europe but still an inhabitant of the ,nile and some ,asiatic rivers4 ,with it occurs the ,unio littoralis1 now living in the ,seine and ,loire4 ,in the valley of the ,somme flint tools have been found associated with ,hippopotamus major and ,cyrena fluminalis in the lower-level ,post-pliocene gravels2 while in the higher-level 7and more ancient7 gravels similar tools are more abundant1 and are associated with the bones of the mammoth and other ,post-pliocene quadrupeds indicative of a colder climate4 ,it is possible that we may here have evidence of summer and winter migrations rather than of a general change of temperature4 ,instead of imagining that the hippopotamus lived all the year round with the musk-ox and lemming1 we may rather suppose that the apparently conflicting evidence may be due to the place of our observations being near the boundary line of a northern and southern fauna1 either of which may have advanced or receded during comparatively slight and temporary fluctuations of climate4 ,there may then have been a continuous land communication between ,england and the ,north of ,siberia1 as well as in an opposite direction with ,africa1 then united to ,southern ,europe4 ,in drift at ,fisherton1 near ,salisbury1 thirty feet above the river ,wiley1 the ,greenland lemming and a new species of the ,arctic genus ,spermophilus have been found1 along with the mammoth1 reindeer1 cave-hyna1 and other mammalia suited to a cold climate4 ,a flint implement was taken out from beneath the bones of the mammoth4 ,in a higher and older deposit in the vicinity1 flint tools like those of ,amiens have been discovered4 ,nearly all the known ,post-pliocene quadrupeds have now been found accompanying flint knives or hatchets in such a way as to imply their coexistence with man2 and we have thus the concurrent testimony of several classes of geological facts to the vast antiquity of the human race4 ,in the first place1 the disappearance of a great variety of species of wild animals from every part of a wide continent must have required a vast period for its accomplishment2 yet this took place while man existed upon the earth1 and was completed before that early period when the ,danish shell-mounds were formed or the oldest of the ,swiss lake-dwellings constructed4 ,secondly1 the deepening and widening of valleys1 indicated by the position of the river gravels at various heights1 implies an amount of change of which that which has occurred during the historical period forms a scarcely perceptible part4 ,thirdly1 the change in the course of rivers which once flowed through caves now removed from any line of drainage1 and the formation of solid floors of stalagmite1 must have required a great lapse of time4 ,lastly1 ages must have been required to change the climate of wide regions to such an extent as completely to alter the geographical distribution of many mammalia as well as land and fresh-water shells4 ,the #cjjj or #djjj years of the historical period does not furnish us with any appreciable measure for calculating the number of centuries which would suffice for such a series of changes1 which are by no means of a local character1 but have operated over a considerable part of ,europe4 ,relative ,longevity of ,species in the ,mammalia and ,testacea4--,i called attention in #ahcje to the fact1 which had not at that time attracted notice1 that the association in the ,post-pliocene deposits of shells1 exclusively of living species1 with many extinct quadrupeds betokened a longevity of species in the testacea far exceeding that in the mammalia4 ,subsequent researches seem to show that this greater duration of the same specific forms in the class mollusca is dependent on a still more general law1 namely1 that the lower the grade of animals1 or the greater the simplicity of their structure1 the more persistent are they in general in their specific characters throughout vast periods of time4 ,not only have the invertebrata1 as shown by geological data1 altered at a less rapid rate than the vertebrata1 but if we take one of the classes of the former1 as for example the mollusca1 we find those of more simple structure to have varied at a slower rate than those of a higher and more complex organisation2 the ,brachiopoda1 for example1 more slowly than the lamellibranchiate bivalves1 while the latter have been more persistent than the univalves1 whether gasteropoda or cephalopoda4 ,in like manner the specific identity of the characters of the foraminifera1 which are among the lowest types of the invertebrata1 has outlasted that of the mollusca in an equally decided manner4 ,teeth of ,post-pliocene ,mammalia4--,to those who have never studied comparative anatomy1 it may seem scarcely credible that a single bone taken from any part of the skeleton may enable a skilful osteologist to distinguish1 in many cases1 the genus1 and sometimes the species1 of quadrupeds to which it belonged4 ,although few geologists can aspire to such knowledge1 which must be the result of long practice and study1 they will nevertheless derive great advantage from learning1 what is comparatively an easy task1 to distinguish the principal divisions of the mammalia by the forms and characters of their teeth4 ,fig4 #ic3 ,elephas primigenius 7or ,mammoth7 molar of upper jaw1 right side4 ,post-pliocene2 ,fig4 #id3 ,elephas antiquus1 ,falconer4 ,penultimate molar4 ,post-pliocene and ,pliocene4 ,figures #ic through #aje represent the teeth of some of the more common species and genera found in alluvial and cavern deposits4 ,figs4 #ie to #ajj3 ,teeth of extinct mammalia4 ,figs4 #aja to #aje3 ,teeth of extinct mammalia4 ,on comparing the grinding surfaces of the corresponding molars of the three species of elephants1 ,figs4 #ic1 #id1 #ie it will be seen that the folds of enamel are most numerous in the mammoth1 fewer and wider1 or more open1 in ,e4 antiquus2 and most open and fewest in ,e4 meridionalis4 ,it will be also seen that the enamel in the molar of the ,rhinoceros tichorhinus 7,fig4 #ig71 is much thicker than in that of the ,rhinoceros leptorhinus 7,fig4 #if74 #a ,sir ,john ,lubbock1 ,pre-historic ,times1 p4 #c1 #ahfe4 #b ,bulletin de la ,sociti ,vaudoise des ,sci4 ,nat41 tome vi1 ,lausanne #ahfj2 and ,antiquity of ,man1 by the author1 chap4 ii4 #c ,sir ,j4 ,lubbock's ,lecture1 ,royal ,institution1 ,feb4 #bgth1 #ahfc4 #d ,diodorus1 v1 #ba1 #bb and ,sir ,h4 ,james ,note on ,block of ,tin dredged up in ,falmouth ,harbour4 ,royal ,institution of ,cornwall1 #ahfc4 #e ,principles of ,geology1 #ast ed41 vol4 iii1 p4 #adj4 ,,chapter ,,xi4 ,,post-,,pliocene ,,period1 continued--,,glacial ,,conditions4#a ,geographical ,distribution1 ,form1 and ,characters of ,glacial ,drift4 -- ,fundamental ,rocks1 polished1 grooved1 and scratched4 -- ,abrading and striating ,action of ,glaciers4 -- ,moraines1 ,erratic ,blocks1 and 8,roches ,moutonnees40 ,alpine ,blocks on the ,jura4 -- ,continental ,ice of ,greenland4 -- ,ancient ,centres of the ,dispersion of ,erratics4 -- ,transportation of ,drift by floating ,icebergs4 -- ,bed of the ,sea furrowed and polished by the running aground of floating ,ice-islands4 ,character and ,distribution of ,glacial ,drift4--,in speaking of the loose transported matter commonly found on the surface of the land in all parts of the globe1 ,i alluded to the exceptional character of what has been called the boulder formation in the temperate and ,arctic latitudes of the northern hemisphere4 ,the peculiarity of its form in ,europe north of the #ejth1 and in ,north ,america north of the #djth parallel of latitude1 is now universally attributed to the action of ice1 and the difference of opinion respecting it is now chiefly restricted to the question whether land-ice or floating icebergs have played the chief part in its distribution4 ,it is wanting in the warmer and equatorial regions1 and reappears when we examine the lands which lie south of the #djth and #ejth parallels in the southern hemisphere1 as1 for example1 in ,patagonia1 ,tierra del ,fuego1 and ,new ,zealand4 ,it consists of sand and clay1 sometimes stratified1 but often wholly devoid of stratification for a depth of #ej1 #ajj1 or even a greater number of feet4 ,to this unstratified form of the deposit the name of till has long been applied in ,scotland4 ,it generally contains a mixture of angular and rounded fragments of rock1 some of large size1 having occasionally one or more of their sides flattened and smoothed1 or even highly polished4 ,the smoothed surfaces usually exhibit many scratches parallel to each other1 one set of which often crosses an older set4 ,the till is almost everywhere wholly devoid of organic remains1 except those washed into it from older formations1 though in some places it contains marine shells1 usually of northern or ,arctic species1 and frequently in a fragmentary state4 ,the bulk of the till has usually been derived from the grinding down into mud of rocks in the immediate neighbourhood1 so that it is red in a region of ,red ,sandstone1 as in ,strathmore in ,forfarshire2 grey or black in a district of coal and bituminous shale1 as around ,edinburgh2 and white in a chalk country1 as in parts of ,norfolk and ,denmark4 ,the stony fragments dispersed irregularly through the till usually belong1 especially in mountainous countries1 to rocks found in some part of the same hydrographical basin2 but there are regions where the whole of the boulder clay has come from a distance1 and huge blocks1 or 8erratics10 as they have been called1 many feet in diameter1 have not unfrequently travelled hundreds of miles from their point of departure1 or from the parent rocks from which they have evidently been detached4 ,these are commonly angular1 and have often one or more of their sides polished and furrowed4 ,the rock on which the boulder formation reposes1 if it consists of granite1 gneiss1 marble1 or other hard stone1 capable of permanently retaining any superficial markings which may have been imprinted upon it1 is usually smoothed or polished1 like the erratics above described1 and exhibits parallel stri and furrows having a determinate direction4 ,this direction1 both in ,europe and ,north ,america1 agrees generally in a marked manner with the course taken by the erratic blocks in the same district4 ,the boulder clay1 when it was first studied1 seemed in many of its characters so singular and anomalous1 that geologists despaired of ever being able to interpret the phenomena by reference to causes now in action4 ,in those exceptional cases where marine shells of the same date as the boulder clay were found1 nearly all of them were recognised as living species--a fact conspiring with the superficial position of the drift to indicate a comparatively modern origin4 ,the term 8diluvium0 was for a time the most popular name of the boulder formation1 because it was referred by many to the deluge of ,noah1 while others retained the name as expressive of their opinion that a series of diluvial waves raised by hurricanes and storms1 or by earthquakes1 or by the sudden upheaval of land from the bed of the sea1 had swept over the continents1 carrying with them vast masses of mud and heavy stones1 and forcing these stones over rocky surfaces so as to polish and imprint upon them long furrows and stri4 ,but geologists were not long in seeing that the boulder formation was characteristic of high latitudes1 and that on the whole the size and number of erratic blocks increases as we travel towards the ,arctic regions4 ,they could not fail to be struck with the contrast which the countries bordering the ,baltic presented when compared with those surrounding the ,mediterranean4 ,the multitude of travelled blocks and striated rocks in the one region1 and the absence of such appearances in the other1 were too obvious to be overlooked4 ,even the great development of the boulder formation1 with large erratics so far south as the ,alps1 offered an exception to the general rule favourable to the hypothesis that there was some intimate connection between it and accumulations of snow and ice4 ,fig4 #ajf3 ,limestone1 polished1 furrowed1 and scratched by the glacier of ,rosenlau in ,switzerland4 ,transporting and abrading ,power of ,glaciers4--,i have described elsewhere 78,principles0 vol4 i1 chap4 xvi1 #ahfg7 the manner in which the snow of the ,alpine heights is prevented from accumulating indefinitely in thickness by the constant descent of a large portion of it by gravitation4 ,becoming converted into ice it forms what are termed glaciers1 which glide down the principal valleys4 ,on their surface are seen mounds of rubbish or large heaps of sand and mud1 with angular fragments of rock which fall from the steep slopes or precipices bounding the glaciers4 ,when a glacier1 thus laden1 descends so far as to reach a region about #cejj feet above the level of the sea1 the warmth of the air is such that it melts rapidly in summer1 and all the mud1 sand1 and pieces of rock are slowly deposited at its lower end1 forming a confused heap of unstratified rubbish called a moraine1 and resembling the till before described 7p4 #aff74 ,besides the blocks thus carried down on the top of the glacier1 many fall through fissures in the ice to the bottom1 where some of them become firmly frozen into the mass1 and are pushed along the base of the glacier1 abrading1 polishing1 and grooving the rocky floor below1 as a diamond cuts glass1 or as emery-powder polishes steel4 ,the stri which are made1 and the deep grooves which are scooped out by this action1 are rectilinear and parallel to an extent never seen in those produced on loose stones or rocks1 where shingle is hurried along by a torrent1 or by the waves on a sea-beach4 ,in addition to these polished1 striated1 and grooved surfaces of rock1 another mark of the former action of a glacier is the 8roche moutonnee40 ,projecting eminences of rock so called have been smoothed and worn into the shape of flattened domes by the glacier as it passed over them4 ,they have been traced in the ,alps to great heights above the present glaciers1 and to great horizontal distances beyond them4 ,alpine ,blocks on the ,jura4--,the moraines1 erratics1 polished surfaces1 domes1 and stri1 above described1 are observed in the great valley of ,switzerland1 fifty miles broad2 and almost everywhere on the ,jura1 a chain which lies to the north of this valley4 ,the average height of the ,jura is about one-third that of the ,alps1 and it is now entirely destitute of glaciers2 yet it presents almost everywhere similar moraines1 and the same polished and grooved surfaces4 ,the erratics1 moreover1 which cover it1 present a phenomenon which has astonished and perplexed the geologist for more than half a century4 ,no conclusion can be more incontestable than that these angular blocks of granite1 gneiss1 and other crystalline formations came from the ,alps1 and that they have been brought for a distance of fifty miles and upward across one of the widest and deepest valleys in the world2 so that they are now lodged on a chain composed of limestone and other formations1 altogether distinct from those of the ,alps4 ,their great size and angularity1 after a journey of so many leagues1 has justly excited wonder2 for hundreds of them are as large as cottages2 and one in particular1 composed of gneiss1 celebrated under the name of ,pierre ,bot1 rests on the side of a hill about #ijj feet above the lake of ,neufchtel1 and is no less than #dj feet in diameter4 ,in the year #ahba1 ,m4 ,venetz first announced his opinion that the ,alpine glaciers must formerly have extended far beyond their present limits1 and the proofs appealed to by him in confirmation of this doctrine were acknowledged by all subsequent observers1 and greatly strengthened by new observations and arguments4 ,m4 ,charpentier supposed that when the glaciers extended continuously from the ,alps to the ,jura1 the former mountains were #bjjj or #cjjj feet higher than at present4 ,other writers1 on the contrary1 conjectured that the whole country had been submerged1 and the moraines and erratic blocks transported on floating icebergs2 but a careful study of the distribution of the travelled masses1 and the total absence of marine shells from the old glacial drift of ,switzerland1 have entirely disproved this last hypothesis4 ,in addition to the many evidences of the action of ice in the northern parts of ,europe which we have already mentioned1 there occur here and there in some of these countries1 what are wanting in ,switzerland1 deposits of marine fossil shells1 which exhibit so arctic a character that they must have led the geologist to infer the former prevalence of a much colder climate1 even had he not encountered so many accompanying signs of ice-action4 ,the same marine shells demonstrate the submergence of large areas in ,scandinavia and the ,british ,isles1 during the glacial cold4 ,a characteristic feature of the deposits under consideration in all these countries is the occurrence of large erratic blocks1 and sometimes of moraine matter1 in situations remote from lofty mountains1 and separated from the nearest points where the parent rocks appear at the surface by great intervening valleys1 or arms of the sea4 ,we also often observe stri and furrows1 as in ,norway1 ,sweden1 and ,scotland1 which deviate from the direction which they ought to follow if they had been connected with the present line of drainage1 and they1 therefore1 imply the prevalence of a very distinct condition of things at the time when the cold was most intense4 ,the actual state of ,north ,greenland seems to afford the best explanation of such abnormal glacial markings4 ,greenland ,continental ,ice4--,greenland is a vast unexplored continent1 buried under one continuous and colossal mass of ice that is always moving seaward1 a very small part of it in an easterly direction1 and all the rest westward1 or towards ,baffin's ,bay4 ,all the minor ridges and valleys are levelled and concealed under a general covering of snow1 but here and there some steep mountains protrude abruptly from the icy slope1 and a few superficial lines of stones or moraines are visible at certain seasons1 when no snow has fallen for many months1 and when evaporation1 promoted by the wind and sun1 has caused much of the upper snow to disappear4 ,the height of this continent is unknown1 but it must be very great1 as the most elevated lands of the outskirts1 which are described as comparatively low1 attain altitudes of #djjj to #fjjj feet4 ,the icy slope gradually lowers itself towards the outskirts1 and then terminates abruptly in a mass about #bjjj feet in thickness1 the great discharge of ice taking place through certain large friths1 which1 at their upper ends1 are usually about four miles across4 ,down these friths the ice is protruded in huge masses1 several miles wide1 which continue their course--grating along the rocky bottom like ordinary glaciers long after they have reached the salt water4 ,when at last they arrive at parts of ,baffin's ,bay deep enough to buoy up icebergs from #ajjj to #aejj feet in vertical thickness1 broken masses of them float off1 carrying with them on their surface not only fine mud and sand but large stones4 ,these fragments of rock are often polished and scored on one or more sides1 and as the ice melts1 they drop down to the bottom of the sea1 where large quantities of mud are deposited1 and this muddy bottom is inhabited by many mollusca4 ,although the direction of the ice-streams in ,greenland may coincide in the main with that which separate glaciers would take if there were no more ice than there is now in the ,swiss ,alps1 yet the striation of the surface of the rocks on an ice-clad continent would1 on the whole1 vary considerably in its minor details from that which would be imprinted on rocks constituting a region of separate glaciers4 ,for where there is a universal covering of ice there will be a general outward movement from the higher and more central regions towards the circumference and lower country1 and this movement will be1 to a certain extent1 independent of the minor inequalities of hill and valley1 when these are all reduced to one level by the snow4 ,the moving ice may sometimes cross even at right angles deep narrow ravines1 or the crests of buried ridges1 on which last it may afterwards seem strange to detect glacial stri and polishing after the liquefaction of the snow and ice has taken place4 ,rink mentions that in ,north ,greenland powerful springs of clayey water escape in winter from under the ice1 where it descends to 8the outskirts10 and where1 as already stated1 it is often #bjjj feet thick--a fact showing how much grinding action is going on upon the surface of the subjacent rocks4 ,i also learn from ,dr4 ,torell that there are large areas in the outskirts1 now no longer covered with permanent snow or glaciers1 which exhibit on their surface unmistakable signs of ancient ice-action1 so that1 vast as is the power now exerted by ice in ,greenland1 it must once have operated on a still grander scale4 ,the land1 though now very elevated1 may perhaps have been formerly much higher4 ,it is well-known that the south coast of ,greenland1 from latitude #fj to about #gj ,n41 has for the last four centuries been sinking at the rate of several feet in a century4 ,by this means a surface of rock1 well scored and polished by ice1 is now slowly subsiding beneath the sea1 and is becoming strewed over1 as the icebergs melt1 with impalpable mud and smoothed and scratched stones4 ,it is not precisely known how far north this downward movement extends4 ,drift carried by ,icebergs4--,an account was given so long ago as the year #ahbb1 by ,scoresby1 of icebergs seen by him in the ,arctic seas drifting along in latitudes #fi and #gj ,n41 which rose above the surface from #ajj to #bjj feet1 and some of which measured a mile in circumference4 ,many of them were loaded with beds of earth and rock1 of such thickness that the weight was conjectured to be from #ej1jjj to #ajj1jjj tons4 ,a similar transportation of rocks is known to be in progress in the southern hemisphere1 where boulders included in ice are far more frequent than in the north4 ,one of these icebergs was encountered in #ahci1 in mid-ocean1 in the antarctic regions1 many hundred miles from any known land1 sailing northward1 with a large erratic block firmly frozen into it4 ,many of them1 carefully measured by the officers of the ,french exploring expedition of the ,astrolabe1 were between #ajj and #bbe feet high above water1 and from two to five miles in length4 ,captain d',urville ascertained one of them which he saw floating in the ,southern ,ocean to be #ac miles long and #ajj feet high1 with walls perfectly vertical4 ,the submerged portions of such islands must1 according to the weight of ice relatively to sea-water1 be from six to eight times more considerable than the part which is visible1 so that when they are once fairly set in motion1 the mechanical force which they might exert against any obstacle standing in their way would be prodigious4 ,we learn1 therefore1 from a study both of the arctic and antarctic regions1 that a great extent of land may be entirely covered throughout the whole year by snow and ice1 from the summits of the loftiest mountains to the sea-coast1 and may yet send down angular erratics to the ocean4 ,we may also conclude that such land will become in the course of ages almost everywhere scored and polished like the rocks which underlie a glacier4 ,the discharge of ice into the surrounding sea will take place principally through the main valleys1 although these are hidden from our sight4 ,erratic blocks and moraine matter will be dispersed somewhat irregularly after reaching the sea1 for not only will prevailing winds and marine currents govern the distribution of the drift1 but the shape of the submerged area will have its influence2 inasmuch as floating ice1 laden with stones1 will pass freely through deep water1 while it will run a ground where there are reefs and shallows4 ,some icebergs in ,baffin's ,bay have been seen stranded on a bottom #ajjj or even #aejj feet deep4 ,in the course of ages such a sea-bed may become densely covered with transported matter1 from which some of the adjoining greater depths may be free4 ,if1 as in ,west ,greenland1 the land is slowly sinking1 a large extent of the bottom of the ocean will consist of rock polished and striated by land-ice1 and then overspread by mud and boulders detached from melting bergs4 ,the mud1 sand1 and boulders thus let fall in still water must be exactly like the moraines of terrestrial glaciers1 devoid of stratification and organic remains4 ,but occasionally1 on the outer side of such packs of stranded bergs1 the waves and currents may cause the detached earthy and stony materials to be sorted according to size and weight before they reach the bottom1 and to acquire a stratified arrangement4 ,i have already alluded 7p4 #agb7 to the large quantity of ice1 containing great blocks of stone1 which is sometimes seen floating far from land1 in the southern or ,antarctic seas4 ,after the emergence1 therefore1 of such a submarine area1 the superficial detritus will have no necessary relation to the hills1 valleys1 and river-plains over which it will be scattered4 ,many a water-shed may intervene between the starting-point of each erratic or pebble and its final resting-place1 and the only means of discovering the country from which it took its departure will consist in a careful comparison of its mineral or fossil contents with those of the parent rocks4 #a ,as to the former excess of cold1 whether brought about by modifications in the height and distribution of the land or by altered astronomical conditions1 see ,principles1 vol4 i1 7#ajth ed41 #ahfg71 chaps4 xii and xiii1 8,vicissitudes of ,climate40 ,,chapter ,,xii4 ,,post-,,pliocene ,,period1 continued4--,,glacial ,,conditions1 concluded4 ,glaciation of ,scandinavia and ,russia4 -- ,glaciation of ,scotland4 -- ,mammoth in ,scotch ,till4 -- ,marine ,shells in ,scotch ,glacial ,drift4 -- ,their ,arctic ,character4 -- ,rarity of ,organic ,remains in ,glacial ,deposits4 -- ,contorted ,strata in ,drift4 -- ,glaciation of ,wales1 ,england1 and ,ireland4 -- ,marine ,shells of ,moel ,tryfaen4 -- ,erratics near ,chichester4 -- ,glacial ,formations of ,north ,america4 -- ,many ,species of ,testacea and ,quadrupeds survived the ,glacial ,cold4 -- ,connection of the ,predominance of ,lakes with ,glacial ,action4 -- ,action of ,ice in preventing the silting up of ,lake-basins4 -- ,absence of ,lakes in the ,caucasus4 -- ,equatorial ,lakes of ,africa4 ,glaciation of ,scandinavia and ,russia4--,in large tracts of ,norway and ,sweden1 where there have been no glaciers in historical times1 the signs of ice-action have been traced as high as #fjjj feet above the level of the sea4 ,these signs consist chiefly of polished and furrowed rock-surfaces1 of moraines and erratic blocks4 ,the direction of the erratics1 like that of the furrows1 has usually been conformable to the course of the principal valleys2 but the lines of both sometimes radiate outward in all directions from the highest land1 in a manner which is only explicable by the hypothesis above alluded to of a general envelope of continental ice1 like that of ,greenland 7page #agj74 ,some of the far-transported blocks have been carried from the central parts of ,scandinavia towards the ,polar regions2 others southward to ,denmark2 some south-westward1 to the coast of ,norfolk in ,england2 others south-eastward1 to ,germany1 ,poland1 and ,russia4 ,in the immediate neighbourhood of ,upsala1 in ,sweden1 ,i had observed1 in #ahcd1 a ridge of stratified sand and gravel1 in the midst of which occurs a layer of marl1 evidently formed originally at the bottom of the ,baltic1 by the slow growth of the mussel1 cockle1 and other marine shells of living species1 intermixed with some proper to fresh water4 ,the marine shells are all of dwarfish size1 like those now inhabiting the brackish waters of the ,baltic2 and the marl1 in which many of them are imbedded1 is now raised more than #ajj feet above the level of the ,gulf of ,bothnia4 ,upon the top of this ridge repose several huge erratics1 consisting of gneiss for the most part unrounded1 from nine to sixteen feet in diameter1 and which must have been brought into their present position since the time when the neighbouring gulf was already characterised by its peculiar fauna4 ,here1 therefore1 we have proof that the transport of erratics continued to take place1 not merely when the sea was inhabited by the existing testacea1 but when the north of ,europe had already assumed that remarkable feature of its physical geography which separates the ,baltic from the ,north ,sea1 and causes the ,gulf of ,bothnia to have only one-fourth of the saltness belonging to the ocean4 ,in ,denmark1 also1 recent shells have been found in stratified beds1 closely associated with the boulder clay4 ,glaciation of ,scotland4--,mr4 ,t4 ,f4 ,jamieson1 in #aheh1 adduced a great body of facts to prove that the ,grampians once sent down glaciers from the central regions in all directions towards the sea4 8,the glacial grooves10 he observed1 8radiate outward from the central heights towards all points of the compass1 though they do not always strictly conform to the actual shape and contour of the minor valleys and ridges40 ,these facts and other characteristics of the ,scotch drift lead us to the inference that when the glacial cold first set in1 ,scotland stood higher above the sea than at present1 and was covered for the most part with snow and ice1 as ,greenland is now4 ,this sheet of land-ice sliding down to lower levels1 ground down and polished the subjacent rocks1 sweeping off nearly all superficial deposits of older date1 and leaving only till and boulders in their place4 ,to this continental state succeeded a period of depression and partial submergence4 ,the sea advanced over the lower lands1 and ,scotland was converted into an archipelago1 some marine sand with shells being spread over the bottom of the sea4 ,on this sand a great mass of boulder clay usually quite devoid of fossils was accumulated4 ,lastly1 the land re-emerged from the water1 and1 reaching a level somewhat above its present height1 became connected with the continent of ,europe1 glaciers being formed once more in the higher regions1 though the ice probably never regained its former extension4#a ,after all these changes1 there were some minor oscillations in the level of the land1 on which1 although they have had important geographical consequences1 separating ,ireland from ,england1 for example1 and ,england from the ,continent1 we need not here enlarge4 ,mammoth in ,scotch ,till4--,almost all remains of the terrestrial fauna of the ,continent which preceded the period of submergence have been lost2 but a few patches of estuarine and fresh-water formations escaped denudation by submergence4 ,to these belong the peaty clay from which several mammoths' tusks and horns of reindeer were obtained at ,kilmaurs1 in ,ayrshire as long ago as #ahaf4 ,mr4 ,bryce in #ahfe ascertained that the fresh-water formation containing these fossils rests on carboniferous sandstone1 and is covered1 first by a bed of marine sand with arctic shells1 and then with a great mass of till with glaciated boulders4#b ,still more recent explorations in the neighbourhood of ,kilmaurs have shown that the fresh-water formation contains the seed of the pond-weed ,potamogeton and the aquatic ,ranunculus2 and ,mr4 ,young of the ,glasgow ,museum washed the mud adhering to the reindeer horns of ,kilmaurs and that which filled the cracks of the associated elephants' tusks1 and detected in these fossils 7which had been in the ,glasgow ,museum for half a century7 abundance of the same seeds4 ,all doubts1 therefore1 as to the true position of the remains of the mammoth1 a fossil so rare in ,scotland1 have been set at rest1 and it serves to prove that part of the ancient continent sank beneath the sea at a period of great cold1 as the shells of the overlying sand attest4 ,the incumbent till or boulder clay is about #dj feet thick1 but it often attains much greater thickness in the same part of ,scotland4 ,figs4 #ajg-aab3 ,northern shells common in the drift of the ,clyde1 in ,scotland4 ,marine ,shells of ,scotch ,drift4--,the greatest height to which marine shells have yet been traced in this boulder clay is at ,airdie1 in ,lanarkshire1 ten miles east of ,glasgow1 #ebd feet above the level of the sea4 ,at that spot they were found imbedded in stratified clays with till above and below them4 ,there appears no doubt that the overlying deposit was true glacial till1 as some boulders of granite were observed in it1 which must have come from distances of sixty miles at the least4 ,fig4 #aac3 ,leda truncata2 ,fig4 #aad3 ,tellina calcarea1 ,chem4 ,the shells figured in ,figs4 #ajg to #aab are only a few out of a large assemblage of living species1 which1 taken as a whole1 bear testimony to conditions far more arctic than those now prevailing in the ,scottish seas4 ,but a group of marine shells1 indicating a still greater excess of cold1 has been brought to light since #ahfj by the ,reverend ,thomas ,brown1 from glacial drift or clay on the borders of the estuaries of the ,forth and ,tay4 ,this clay occurs at ,elie1 in ,fife1 and at ,errol1 in ,perthshire2 and has already afforded about #ce shells1 all of living species1 and now inhabitants of arctic regions1 such as ,leda truncata1 ,tellina proxima 7see ,figs4 #aac and #aad71 ,pecten ,grnlandicus1 ,crenella lvigata1 ,crenella nigra1 and others1 some of them first brought by ,captain ,sir ,e4 ,parry from the coast of ,melville ,island1 latitude #gf ,n4 ,these were all identified in #ahfc by ,dr4 ,torell1 who had just returned from a survey of the seas around ,spitzbergen1 where he had collected no less than #aej species of mollusca1 living chiefly on a bottom of fine mud derived from the moraines of melting glaciers which there protrude into the sea4 ,he informed me that the fossil fauna of this ,scotch glacial deposit exhibits not only the species but also the peculiar varieties of mollusca now characteristic of very high latitudes4 ,their large size implies that they formerly enjoyed a colder1 or1 what was to them a more genial climate1 than that now prevailing in the latitude where the fossils occur4 ,marine shells have also been found in the glacial drift of ,caithness and ,aberdeenshire at heights of #bej feet1 and in ,banff of #cej feet1 and stratified drift continuous with the above ascends to heights of #ejj feet4 ,already #ge species are enumerated from ,caithness1 and the same number from ,aberdeenshire and ,banff1 and in both cases all but six are arctic species4 ,i formerly suggested that the absence of all signs of organic life in the ,scotch drift might be connected with the severity of the cold1 and also in some places with the depth of the sea during the period of extreme submergence2 but my faith in such an hypothesis has been shaken by modern investigations1 an exuberance of life having been observed both in arctic and antarctic seas of great depth1 and where floating ice abounds4 ,the difficulty1 moreover1 of accounting for the entire dearth of marine shells in till is removed when once we have adopted the theory of this boulder clay being the product of land-ice4 ,for glaciers coming down from a continental ice-sheet like that which covers ,greenland may fill friths many hundred feet below the sea-level1 and even invade parts of a bay a thousand feet deep1 before they find water enough to float off their terminal portions in the form of icebergs4 ,in such a case till without marine shells may first accumulate1 and then1 if the climate becomes warmer and the ice melts1 a marine deposit may be superimposed on the till without any change of level being required4 ,another curious phenomenon bearing on this subject was styled by the late ,hugh ,miller the 8striated pavements0 of the boulder clay4 ,where portions of the till have been removed by the sea on the shores of the ,forth1 or in the interior by railway cuttings1 the boulders imbedded in what remains of the drift are seen to have been all subjected to a process of abrasion and striation1 the stri and furrows being parallel and persistent across them all1 exactly as if a glacier or iceberg had passed over them and scored them in a manner similar to that so often undergone by the solid rocks below the glacial drift4 ,it is possible1 as ,mr4 ,geikie conjectures1 that this second striation of the boulders may be referable to floating ice4#c ,contorted ,strata in ,drift4--,in ,scotland the till is often covered with stratified gravel1 sand1 and clay1 the beds of which are sometimes horizontal and sometimes contorted for a thickness of several feet4 ,such contortions are not uncommon in ,forfarshire1 where ,i observed them1 among other places1 in a vertical cutting made in #ahdj near the left bank of the ,south ,esk1 east of the bridge of ,cortachie4 ,the convolutions of the beds of fine and coarse sand1 gravel1 and loam1 extend through a thickness of no less than #be feet vertical1 or from b to c1 ,fig4 #aae1 the horizontal stratification being resumed very abruptly at a short distance1 as to the right of f1 g4 ,the overlying coarse gravel and sand1 a1 is in some places horizontal1 in others it exhibits cross bedding1 and does not partake of the disturbances which the strata b1 c1 have undergone4 ,the underlying till is exposed for a depth of about #bj feet2 and we may infer from sections in the neighbourhood that it is considerably thicker4 ,fig4 #ae3 ,section of contorted drift overlying till1 seen on left bank of ,south ,esk1 near ,cortachie1 in #ahdj4 ,in some cases ,i have seen fragments of stratified clays and sands1 bent in like manner1 in the middle of a great mass of till4 ,mr4 ,trimmer has suggested1 in explanation of such phenomena1 the intercalation in the glacial period of large irregular masses of snow or ice between layers of sand and gravel4 ,some of the cliffs near ,behring's ,straits1 in which the remains of elephants occur1 consist of ice mixed with mud and stones2 and ,middendorf describes the occurrence in ,siberia of masses of ice1 found at various depths from the surface after digging through drift4 ,whenever the intercalation of snow and ice with drift1 whether stratified or unstratified1 has taken place1 the melting of the ice will cause such a failure of support as may give rise to flexures1 and sometimes to the most complicated foldings4 ,but in many cases the strata may have been bent and deranged by the mechanical pressure of an advancing glacier1 or by the sideway thrust of huge islands of ice running aground against sandbanks2 in which case1 the position of the beds forming the foundation of the banks may not be at all disturbed by the shock4 ,there are indeed many signs in ,scotland of the action of floating ice1 as might have been expected where proofs of submergence in the ,glacial ,period are not wanting4 ,among these are the occurrence of large erratic blocks1 frequently in clusters at or near the tops of hills or ridges1 places which may have formed islets or shallows in the sea where floating ice would mostly ground and discharge its cargo on melting4 ,glaciers or land-ice would1 on the contrary1 chiefly discharge their cargoes at the bottom of valleys4 ,traces of an earlier and independent glaciation have also been observed in some regions where the striation1 apparently produced by ice proceeding from the north-west1 is not explicable by the radiation of land-ice from a central mountainous region4#d ,glaciation of ,wales and ,england4--,the mountains of ,north ,wales were recognised1 in #ahdb1 by ,dr4 ,buckland1 as having been an independent centre of the dispersion of erratics--great glaciers1 long since extinct1 having radiated from the ,snowdonian heights in ,carnarvonshire1 through seven principal valleys towards as many points of the compass1 carrying with them large stony fragments1 and grooving the subjacent rocks in as many directions4 ,besides this evidence of land-glaciers1 ,mr4 ,trimmer had previously1 in #ahca1 detected the signs of a great submergence in ,wales in the ,post-pliocene period4 ,he had observed stratified drift1 from which he obtained about a dozen species of marine shells1 near the summit of ,moel ,tryfaen1 a hill #adjj feet high1 on the south side of the ,menai ,straits4 ,i had an opportunity of examining in the summer of #ahfc1 together with the ,reverend ,w4 ,s4 ,symonds1 a long and deep cutting made through this drift by the ,alexandra ,mining ,company in search of slates4 ,at the top of the hill above-mentioned we saw a stratified mass of incoherent sand and gravel #ce feet thick1 from which no less than #ed species of mollusca1 besides three characteristic arctic varieties--in all #eg forms--have been obtained by ,mr4 ,darbishire4 ,they belong without exception to species still living in ,british or more northern seas2 eleven of them being exclusively arctic1 four common to the arctic and ,british seas1 and a large proportion of the remainder having a northward range1 or1 if found at all in the southern seas of ,britain1 being comparatively less abundant4 ,in the lowest beds of the drift were large heavy boulders of far-transported rocks1 glacially polished and scratched on more than one side4 ,underneath the whole we saw the edges of vertical slates exposed to view1 which here1 like the rocks in other parts of ,wales1 both at greater and less elevations1 exhibit beneath the drift unequivocal marks of prolonged glaciation4 ,the whole deposit has much the appearance of an accumulation in shallow water or on a beach1 and it probably acquired its thickness during the gradual subsidence of the coast--an hypothesis which would require us to ascribe to it a high antiquity1 since we must allow time1 first for its sinking1 and then for its re-elevation4 ,the height reached by these fossil shells on ,moel ,tryfaen is no less than #acjj feet--a most important fact when we consider how very few instances we have on record beyond the limits of ,wales1 whether in ,europe or ,north ,america1 of marine shells having been found in glacial drift at half the height above indicated4 ,a marine molluscous fauna1 however1 agreeing in character with that of ,moel ,tryfaen1 and comprising as many species1 has been found in drift at ,macclesfield and other places in central ,england1 sometimes reaching an elevation of #abjj feet4 ,professor ,ramsay#e estimated the probable amount of submergence during some part of the glacial period at about #bcjj feet2 for he was unable to distinguish the superficial sands and gravel which reached that high elevation from the drift which1 at ,moel ,tryfaen and at lower points1 contains shells of living species4 ,the evidence of the marine origin of the highest drift is no doubt inconclusive in the absence of shells1 so great is the resemblance of the gravel and sand of a sea beach and of a river's bed1 when organic remains are wanting2 but1 on the other hand1 when we consider the general rarity of shells in drift which we know to be of marine origin1 we cannot suppose that1 in the shelly sands of ,moel ,tryfaen1 we have hit upon the exact uppermost limit of marine deposition1 or1 in other words1 a precise measure of the submergence of the land beneath the sea since the glacial period4 ,we are gradually obtaining proofs of the larger part of ,england1 north of a line drawn from the mouth of the ,thames to the ,bristol ,channel1 having been under the sea and traversed by floating ice since the commencement of the glacial epoch4 ,among recent observations illustrative of this point1 ,i may allude to the discovery1 by ,mr4 ,j4 ,f4 ,bateman1 near ,blackpool1 in ,lancashire1 fifty miles from the sea1 and at the height of #efh feet above its level1 of till containing rounded and angular stones and marine shells1 such as ,turritella communis1 ,purpura lapillus1 ,cardium edule1 and others1 among which ,trophon clathratum 7,fusus ,bamffius71 though still surviving in ,north ,british seas1 indicates a cold climate4 ,erratics near ,chichester4--,the most southern memorials of ice-action and of a ,post-pliocene fauna in ,great ,britain is on the coast of the county of ,sussex1 about #be miles west of ,brighton1 and #ae south of ,chichester4 ,a marine deposit exposed between high and low tide occurs on both sides of the promontory called ,selsea ,bill1 in which ,mr4 ,godwin-,austen found thirty-eight species of shells1 and the number has since been raised to seventy4 ,this assemblage is interesting because on the whole1 while all the species are recent1 they have a somewhat more southern aspect than those of the present ,british ,channel4 ,it is true that about forty of them range from ,british to high northern latitudes2 but several of them1 as1 for example1 ,lutraria rugosa and ,pecten polymorphous1 which are abundant1 are not known at present to range farther north than the coast of ,portugal1 and seem to indicate a warmer temperature than now prevails on the coast where we find them fossil4 ,what renders this curious is the fact that the sandy loam in which they occur is overlaid by yellow clayey gravel with large erratic blocks which must have been drifted into their present position by ice when the climate had become much colder4 ,these transported fragments of granite1 syenite1 and greenstone1 as well as of ,devonian and ,silurian rocks1 may have come from the coast of ,normandy and ,brittany1 and are many of them of such large size that we must suppose them to have been drifted into their present site by coast-ice4 ,i measured one of granite1 at ,pagham1 #ba feet in circumference4 ,in the gravel of this drift with erratics are a few littoral shells of living species1 indicating an ancient coast-line4 ,glacial ,formations of ,north ,america4--,in the western hemisphere1 both in ,canada and as far south as the #djth and even #chth parallel of latitude in the ,united ,states1 we meet with a repetition of all the peculiarities which distinguish the ,european boulder formation4 ,fragments of rock have travelled for great distances1 especially from north to south3 the surface of the subjacent rock is smoothed1 striated1 and fluted2 unstratified mud or till containing boulders is associated with strata of loam1 sand1 and clay1 usually devoid of fossils4 ,where shells are present1 they are of species still living in northern seas1 and not a few of them identical with those belonging to ,european drift1 including most of those already given in ,figs4 #ajg to #aab1 p4 #agf4 ,the fauna also of the glacial epoch in ,north ,america is less rich in species than that now inhabiting the adjacent sea1 whether in the ,gulf of ,st4 ,lawrence1 or off the shores of ,maine1 or in the ,bay of ,massachusetts4 ,the extension on the ,american continent of the range of erratics during the ,post-pliocene period to lower latitudes than they reached in ,europe1 agrees well with the present southward deflection of the isothermal lines1 or rather the lines of equal winter temperature4 ,it seems that formerly1 as now1 a more extreme climate and a more abundant supply of ice prevailed on the western side of the ,atlantic4 ,another resemblance between the distribution of the drift fossils in ,europe and ,north ,america has yet to be pointed out4 ,in ,canada and the ,united ,states1 as in ,europe1 the marine shells are generally confined to very moderate elevations above the sea 7between #ajj and #gjj feet71 while the erratic blocks and the grooved and polished surfaces of rock extend to elevations of several thousand feet4 ,i have already mentioned that in ,europe several quadrupeds of living1 as well as extinct1 species were common to pre-glacial and post-glacial times4 ,in like manner there is reason to suppose that in ,north ,america much of the ancient mammalian fauna1 together with nearly all the invertebrata1 lived through the ages of intense cold4 ,that in the ,united ,states the ,mastodon giganteus was very abundant after the drift period1 is evident from the fact that entire skeletons of this animal are met with in bogs and lacustrine deposits occupying hollows in the glacial drift4 ,they sometimes occur in the bottom even of small ponds recently drained by the agriculturist for the sake of the shell-marl4 ,in #ahde no less than six skeletons of the same species of ,mastodon were found in ,warren county1 ,new ,jersey1 six feet below the surface1 by a farmer who was digging out the rich mud from a small pond which he had drained4 ,five of these skeletons were lying together1 and a large part of the bones crumbled to pieces as soon as they were exposed to the air4 ,it would be rash1 however1 to infer from such data that these quadrupeds were mired in modern times1 unless we use that term strictly in a geological sense4 ,i have shown that there is a fluviatile deposit in the valley of the ,niagara1 containing shells of the genera ,melania1 ,lymnea1 ,planorbis1 ,velvata1 ,cyclaz1 ,unio1 ,helix1 etc41 all of recent species1 from which the bones of the great ,mastodon have been taken in a very perfect state4 ,yet the whole excavation of the ravine1 for many miles below the ,falls1 has been slowly effected since that fluviatile deposit was thrown down4 ,other extinct animals accompany the ,mastodon giganteus in the post-glacial deposits of the ,united ,states1 and this1 taken with the fact that so few of the mollusca1 even of the commencement of the cold period1 differ from species now living is important1 as refuting the hypothesis1 for which some have contended1 that the intensity of the glacial cold annihilated all the species in temperate and arctic latitudes4 ,connection of the ,predominance of ,lakes with ,glacial ,action4--,it was first pointed out by ,professor ,ramsay in #ahfb1 that lakes are exceedingly numerous in those countries where erratics1 striated blocks1 and other signs of ice-action abound2 and that they are comparatively rare in tropical and sub-tropical regions4 ,generally in countries where the winter cold is intense1 such as ,canada1 ,scandinavia1 and ,finland1 even the plains and lowlands are thickly strewn with innumerable ponds and small lakes1 together with some others of a larger size2 while in more temperate regions1 such as ,great ,britain1 ,central and ,southern ,europe1 the ,united ,states1 and ,new ,zealand1 lake districts occur in all such mountainous tracts as can be proved to have been glaciated in times comparatively modern or since the geographical configuration of the surface bore a considerable resemblance to that now prevailing4 ,in the same countries1 beyond the glaciated regions1 lakes abruptly cease1 and in warmer and tropical countries are either entirely absent1 or consist1 as in equatorial ,africa1 of large sheets of water unaccompanied so far as we yet know by numerous smaller ponds and tarns4 ,the southern limits of the lake districts of the ,northern ,hemisphere are found at about #dj ,n4 latitude on the ,american continent1 and about #ej in ,europe1 or where the ,alps intervene four degrees farther south4 ,a large proportion of the smaller lakes are dammed up by barriers of unstratified drift1 having the exact character of the moraines of glaciers1 and are termed by geologists 8morainic10 but some of them are true rock-basins1 and would hold water even if all the loose drift now resting on their margins were removed4 ,in a paper read before the ,geological ,society of ,london in #ahfb1 ,professor ,ramsay maintained that the first formation of most existing lakes took place during the glacial epoch1 and was due1 not to elevation or subsidence1 but to actual erosion of their basins by glaciers4 ,m4 ,mortillet in the same year advanced the theory that after the ,alpine lake-basins had been filled up with loose fluviatile deposits1 they were re-excavated by the great glaciers which passed down the valleys at the time of the greatest cold1 a doctrine which would attribute to moving ice almost as great a capacity of erosion as that which assumed that the original basins were scooped out of solid rock by glaciers4 ,it is impossible to deny that the mere geographical distribution of lakes points to the intimate connection of their origin with the abundance of ice during a former excess of cold1 but how far the erosive action of moving ice has been the sole or even the principal cause of lake-basins1 is a question still open to discussion4 ,the lakes of ,switzerland and the north of ,italy are some of them twenty and thirty miles in length1 and so deep that their bottoms are in some cases from #ajjj to #bjjj feet beneath the level of the sea4 ,it is admitted on all hands that they were once filled with ice1 and as the existing glaciers polish and grind down1 as before stated1 the surface of the rocks1 we are prepared to find that every lake-basin in countries once covered by ice should bear the marks of superficial glaciation1 and also that the ice during its advance and retreat should have left behind it much transported matter as well as some evidence of its having enlarged the pre-existing cavity4 ,but much more than this is demanded by the advocates of glacial erosion4 ,they suggest that as the old extinct glaciers were several thousand feet thick1 they were able in some places gradually to scoop out of the solid rock cavities twenty or thirty miles in length1 and as in the case of ,lago ,maggiore from a thousand to two thousand six hundred feet below the previous level of the river-channel1 and also that the ice had the power to remove from the cavity formed by its grinding action all the materials of the missing rocks4 ,a constant supply1 it is argued1 of fine mud issues from the termination of every glacier in the stream which is produced by the melting of the ice1 and this result of friction is exhibited both during winter and summer1 affording evidence of the continual deepening and widening of the valleys through which glaciers pass4 ,as the fine mud is carried away by a river from the deep pool which is formed from the base of every cataract1 so it seems to be imagined that lake-basins may be gradually emptied of the mud formed by abrasion during the glacial period4 ,i am by no means disposed to object to this theory on the ground of the insufficiency of the time during which the extreme cold endured1 but we must carefully consider whether that same time is not so vast as to make it probable that other forces1 besides the motion of glaciers1 must have cooperated in converting some parts of the ancient valley courses into lake-basins4 ,they who have formed the most exalted conceptions of the erosive energy of moving ice do not deny that during the period termed 8,glacial0 there have been movements of the earth's crust sufficient to produce oscillations of level in ,europe amounting to #ajjj feet or more in both directions4 ,m4 ,charpentier1 indeed1 attributed some of the principal changes of climate in ,switzerland1 during the glacial period1 to a depression of the central ,alps to the extent of #cjjj feet1 and ,swiss geologists have long been accustomed to attribute their lake basins1 in part1 to those convulsions by which the shape and course of the valleys may have been modified4 ,our experience1 in the lifetime of the present generation1 of the changes of level witnessed in ,new ,zealand during great earthquakes is entirely opposed to the notion that the movements1 whether upward or downward1 are uniform in amount or direction throughout areas of indefinite extent4 ,on the contrary1 the land has been permanently raised in one region several feet or yards1 and the rise has been found gradually to die out1 so as to be imperceptible at a distance of twenty miles1 and in some areas is even exchanged for a simultaneous downward movement of several feet4 ,but1 it is asked1 if such inequality of movement can have contributed towards the production of lake basins1 does it not leave unexplained the comparative rarity of lakes in tropical and subtropical countries4 ,in reply to this question it may be observed that in our endeavour to estimate the effects of subterranean movements in modifying the superficial geography of a country we must remember that each convulsion effects a very slight change4 ,if it interferes with the drainage1 whether by raising the lower or sinking the higher portion of a hydrographical basin1 the upheaval or depression will only amount to a few feet at a time1 and there may be an interval of years or centuries before any further movement takes place in the same region4 ,in the mean time an incipient lake if produced may be filled up with sediment1 and the recently-formed barrier will then be cut through by the river1 whereas in a country where glacial conditions prevail no such obliteration of the temporary lake-basin would take place2 for however deep it became by repeated sinking of the upper or rising of the lower extremity1 being always filled with ice it might remain1 throughout the greater part of its extent1 free from sediment or drift until the ice melted at the close of the glacial period4 ,one of the most serious objections to the exclusive origin by ice-erosion of wide and deep lake-basins arises from their capricious distribution1 as for example in ,piedmont1 both to the eastward and westward of ,turin1 where great lakes are wanting1#f although some of the largest extinct glaciers descending from ,mont ,blanc and ,monte ,rosa came down from the ,alps1 leaving their gigantic moraines in the low country4 ,here1 therefore1 we might have expected to find lakes of the first magnitude rivalling the contiguous ,lago ,maggiore in importance4 ,a still more striking illustration of the same absence of lakes where large glaciers abound is afforded by the ,caucasus1 a chain more than #cjj miles long1 and the loftiest peaks of which attain heights from #af1jjj to #ah1jjj feet4 ,this greatest altitude is reached by ,elbruz1 a mountain in lat4 #dc ,n4 three degrees south of ,mont ,blanc1 but on the other hand #cjjj feet higher4 ,the present ,caucasian glaciers are equal or superior in dimensions to those of ,switzerland1 and like them give rise occasionally to temporary lakes by obstructing the course of rivers1 and causing great floods when the icy barriers give way4 ,mr4 ,freshfield1 a careful observer1 writing in #ahfi1 says3#g 8,a total absence of lakes on both sides of the chains is the most marked feature4 ,not only are there no great subalpine sheets of water1 like ,como or ,geneva1 but mountain tarns1 such as the ,dauben ,see on the ,gemmi1 or the ,klonthal ,see near ,glarus1 are equally wanting40 ,the same author states on the authority of the eminent ,swiss geologist1 ,mons4 ,e4 ,favre1 who also explored the ,caucasus in #ahfh1 that moraines of great height and huge erratics of granite and other rocks 8justify the assertion that the present glaciers of the ,caucasus1 like those of the ,alps1 are only the shadows of their former selves40 ,it seems safe to assume that the chain of lakes1 of which the ,albert ,nyanza forms one in equatorial ,africa1 was due to causes other than glacial4 ,yet if we could imagine a glacial period to visit that region filling the lakes with ice and scoring the rocks which form their sides and bottoms1 we should be unable to decide how much the capacity of the basins had been enlarged and the surface modified by glacial erosion4 ,the same may be true of the ,lago ,maggiore and ,lake ,superior1 although the present basins of both of them afford abundant superficial markings due to ice-action4 ,but to whatever combination of causes we attribute the great ,alpine lakes one thing is clear1 namely1 that they are1 geologically speaking1 of modern origin4 ,every one must admit that the upper valley of the ,rhone has been chiefly caused by fluviatile denudation1 and it is obvious that the quantity of matter removed from that valley previous to the glacial period would have been amply sufficient to fill up with sediment the basin of the ,lake of ,geneva1 supposing it to have been in existence1 even if its capacity had been many times greater than it is now4#h ,on the whole1 it appears to me1 in accordance with the views of ,professor ,ramsay1 ,m4 ,mortillet1 ,mr4 ,geikie1 and others1 that the abrading action of ice has formed some mountain tarns and many morainic lakes2 but when it is a question of the origin of larger and deeper lakes1 like those of ,switzerland or the north of ,italy1 or inland fresh-water seas1 like those of ,canada1 it will probably be found that ice has played a subordinate part in comparison with those movements by which changes of level in the earth's crust are gradually brought about4 #a ,jamieson1 ,quart4 ,geol4 ,journ41 #ahfj1 vol4 xvi1 p4 #cgj4 #b ,bryce1 ,quart4 ,geol4 ,journ41 vol4 xxi1 p4 #bag1 #ahfe4 #c ,geikie1 ,trans4 ,geol4 ,soc4 ,glasgow1 vol4 i1 part ii1 p4 #fh1 #ahfc4 #d ,milne ,home1 ,trans4 ,royal ,soc4 ,edinburgh1 vol4 xxv1 #ahfh-i4 #e ,quart4 ,geol4 ,journ41 #aheb1 vol4 viii1 p4 #cgb4 #f ,antiquity of ,man1 p4 #cac4 #g ,travels in ,central ,caucasus1 #ahfi1 p4 #deb4 #h ,see ,principles1 vol4 i1 p4 #dbj1 #ajth ed41 #ahfg4 ,,tertiary ,,or ,,cainozoic ,,period ,,chapter ,,xiii4 ,,pliocene ,,period ,glacial ,formations of ,pliocene ,age4 -- ,bridlington ,beds4 -- ,glacial ,drifts of ,ireland4 -- ,drift of ,norfolk ,cliffs4 -- ,cromer ,forest-bed4 -- ,aldeby and ,chillesford ,beds4 -- ,norwich ,crag4 -- ,older ,pliocene ,strata4 -- ,red ,crag of ,suffolk4 -- ,coprolitic ,bed of ,red ,crag4 -- ,white or ,coralline ,crag4 -- ,relative ,age1 ,origin1 and ,climate of the ,crag ,deposits4 -- ,antwerp ,crag4 -- ,newer ,pliocene ,strata of ,sicily4 -- ,newer ,pliocene ,strata of the ,upper ,val d',arno4 -- ,older ,pliocene of ,italy4 -- ,subapennine ,strata4 -- ,older ,pliocene ,flora of ,italy4 ,it will be seen in the description given in the last chapter of the ,post-pliocene formations of the ,british ,isles that they comprise a large proportion of those commonly termed glacial1 characterised by shells which1 although referable to living species1 usually indicate a colder climate than that now belonging to the latitudes where they occur fossil4 ,but in parts of ,england1 more especially in ,yorkshire1 ,norfolk1 and ,suffolk1 there are superficial formations of clay with glaciated boulders1 and of sand and pebbles1 containing occasional1 though rare1 patches of shells1 in which the marine fauna begins to depart from that now inhabiting the neighbouring sea1 and comprises some species of mollusca not yet known as living1 as well as extinct varieties of others1 entitling us to class them as ,newer ,pliocene1 although belonging to the close of that period and chronologically on the verge of the later or ,post-pliocene epoch4 ,bridlington ,drift4--,to this era belongs the well-known locality of ,bridlington1 near the mouth of the ,humber1 in ,yorkshire1 where about seventy species or well-marked varieties of shells have been found on the coast1 near the sea-level1 in a bed of sand several feet thick resting on glacial clay with much chalk dbris1 and covered by a deposit of purple clay with glaciated boulders4 ,more than a third of the species in this drift are now inhabitants of arctic regions1 none of them extending southward to the ,british seas2 which is the more remarkable as ,bridlington is situated in lat4 #ed north4 ,fifteen species are ,british and ,arctic1 a very few belong to those species which range south of our ,british seas4 ,five species or well-marked varieties are not known living1 namely1 the variety of ,astarte borealis 7called ,a4 ,withami72 ,a4 mutabilis2 the sinistral form of ,tritonium carinatum1 ,cardita analis1 and ,tellina obliqua1 ,fig4 #abj1 p4 #aid4 ,mr4 ,searles ,wood also inclines to consider ,nucula ,cobboldi1 ,fig4 #aai1 p4 #aid1 now absent from the ,european seas and the ,atlantic1 as specifically distinct from a closely-allied shell now living in the seas surrounding ,vancouver's ,island1 which some conchologists regard as a variety4 ,tellina obliqua also approaches very near to a shell now living in ,japan4 ,glacial ,drift of ,ireland4--,marine drift containing the last-mentioned ,nucula and other glacial shells reaches a height of from #ajjj to #abjj feet in the county of ,wexford1 south of ,dublin4 ,more than eighty species have already been obtained from this formation1 of which two1 ,conovulus pyramidalis and ,nassa monensis1 are not known as living2 while ,turritella incrassata and ,cypra lucida no longer inhabit the ,british seas1 but occur in the ,mediterranean4 ,the great elevation of these shells1 and the still greater height to which the surface of the rocks in the mountainous regions of ,ireland have been smoothed and striated by ice-action1 has led geologists to the opinion that that island1 like the greater part of ,england and ,scotland1 after having been united with the continent of ,europe1 from whence it received the plants and animals now inhabiting it1 was in great part submerged4 ,the conversion of this and other parts of ,great ,britain into an archipelago was followed by a re-elevation of land and a second continental period4 ,after all these changes the final separation of ,ireland from ,great ,britain took place1 and this event has been supposed to have preceded the opening of the straits of ,dover4#a ,fig4 #aaf3 ,tellina balthica ,drift of ,norfolk ,cliffs4--,there are deposits of boulder clay and till in the ,norfolk cliffs principally made up of the waste of white chalk and flints which1 in the opinion of ,mr4 ,searles ,wood1 jun41 and others1 are older than the ,bridlington drift1 and contain a larger proportion of shells common to the ,norwich and ,red ,crag1 including a certain number of extinct forms1 but also abounding in ,tellina balthica 7,t4 solidula1 ,fig4 #aaf71 which is found fossil at ,bridlington1 and living in our ,british seas1 but wanting in all the formations1 even the newest1 afterwards to be described as ,crag4 ,as the greater part of these drifts are barren of organic remains1 their classification is at present a matter of great uncertainty4 ,they can nowhere be so advantageously studied as on the coast between ,happisburgh and ,cromer4 ,here we may see vertical cliffs1 sometimes #cjj feet and more in height1 exposed for a distance of fifty miles1 at the base of which the chalk with flints crops out in nearly horizontal strata4 ,beds of gravel and sand repose on this undisturbed chalk4 ,they are often strangely contorted1 and envelop huge masses or erratics of chalk with layers of vertical flint4 ,i measured one of these fragments in #ahci at ,sherringham1 and found it to be eighty feet in its longest diameter4 ,it has been since entirely removed by the waves of the sea4 ,in the floor of the chalk beneath it the layers of flint were horizontal4 ,such erratics have evidently been moved bodily from their original site1 probably by the same glacial action which has polished and striated some of the accompanying granitic and other boulders1 occasionally six feet in diameter1 which are imbedded in the drift4 ,cromer ,forest-bed4--,intervening between these glacial formations and the subjacent chalk lies what has been called the ,cromer ,forest-bed4 ,this buried forest has been traced from ,cromer to near ,kessingland1 a distance of more than forty miles1 being exposed at certain seasons between high and low water mark4 ,it is the remains of an old land and estuarine deposit1 containing the submerged stumps of trees standing erect with their roots in the ancient soil4 ,associated with the stumps and overlying them1 are lignite beds with fresh-water shells of recent species1 and laminated clay without fossils4 ,through the lignite and forest-bed are scattered cones of the ,scotch and spruce firs with the seeds of recent plants1 and the bones of at least twenty species of terrestrial mammalia4 ,among these are two species of elephant1 ,e4 meridionalis1 ,nesti1 and ,e4 antiquus1 the former found in the ,newer ,pliocene beds of the ,val d',arno1 near ,florence4 ,in the same bed occur ,hippopotamus major1 ,rhinoceros etruscus1 both of them also ,val d',arno species1 many species of deer considered by ,mr4 ,boyd ,dawkins to be characteristic of warmer countries1 and also a horse1 beaver1 and field-mouse4 ,half of these mammalia are extinct1 and the rest still survive in ,europe4 ,the vegetation taken alone does not imply a temperature higher than that now prevailing in the ,british ,isles4 ,there must have been a subsidence of the forest to the amount of #djj or #ejj feet1 and a re-elevation of the same to an equal extent in order to allow the ancient surface of the chalk or covering of soil1 on which the forest grew1 to be first covered with several hundred feet of drift1 and then upheaved so that the trees should reach their present level4 ,although the relative antiquity of the forest-bed to the overlying glacial till is clear1 there is some difference of opinion as to its relation to the crag presently to be described4 ,fig4 #aag3 ,natica helicoides ,chillesford and ,aldeby ,beds4--,it is in the counties of ,norfolk1 ,suffolk1 and ,essex1 that we obtain our most valuable information respecting the ,british ,pliocene strata1 whether newer or older4 ,they have obtained in those counties the provincial name of 8,crag10 applied particularly to masses of shelly sand which have long been used in agriculture to fertilise soils deficient in calcareous matter4 ,at ,chillesford1 between ,woodbridge and ,aldborough in ,suffolk1 and ,aldeby1 near ,beccles1 in the same county1 there occur stratified deposits1 apparently older than any of the preceding drifts of ,yorkshire1 ,norfolk1 and ,suffolk4 ,they are composed at ,chillesford of yellow sands and clays1 with much mica1 forming horizontal beds about twenty feet thick4 ,messrs4 ,prestwich and ,searles ,wood1 senior1 who first described these beds1 point out that the shells indicate on the whole a colder climate than the ,red ,crag2 two-thirds of them being characteristic of high latitudes4 ,among these are ,cardium ,grnlandicum1 ,leda limatula1 ,tritonium carinatum1 and ,scalaria ,grnlandica4 ,in the upper part of the laminated clays a skeleton of a whale was found associated with casts of the characteristic shells1 ,nucula ,cobboldi and ,tellina obliqua1 already referred to as no longer inhabiting our seas1 and as being extinct varieties if not species4 ,the same shells occur in a perfect state in the lower part of the formation4 ,natica helicoides 7,fig4 #aag7 is an example of a species formerly known only as fossil1 but which has now been found living in our seas4 ,at ,aldeby1 where beds occur decidedly similar in mineral character as well as fossil remains1 ,messrs4 ,crowfoot and ,dowson have now obtained sixty-six species of mollusca1 comprising the ,chillesford species and some others4 ,of these about nine-tenths are recent4 ,they are in a perfect state1 clearly indicating a cold climate2 as two-thirds of them are now met with in arctic regions4 ,as a rule1 the lamellibranchiate molluscs have both valves united1 and many of them1 such as ,mya arenaria1 stand with the siphonal end upward1 as when in a living state4 ,tellina balthica1 before mentioned 7,fig4 #aaf7 as so characteristic of the glacial beds1 including the drift of ,bridlington1 has not yet been found in deposits of ,chillesford and ,aldeby age1 whether at ,sudbourn1 ,east ,bavent1 ,horstead1 ,coltishall1 ,burgh1 or in the highest beds overlying the ,norwich ,crag proper at ,bramerton and ,thorpe4 ,fig4 #aah3 i,mastodon arvernensis1_/i third milk molar1 left side1 upper jaw3 grinding surface4 ,norwich ,crag1 ,postwick1 also found in ,red ,crag1 see p4 #aig4 ,norwich or ,fluvio-marine ,crag4--,the beds above alluded to ought1 perhaps1 to be regarded as beds of passage between the glacial formations and those called from a provincial name 8,crag10 the newest member of which has been commonly called the 8,norwich ,crag40 ,it is chiefly seen in the neighbourhood of ,norwich1 and consists of beds of incoherent sand1 loam1 and gravel1 which are exposed to view on both banks of the ,yare1 as at ,bramerton and ,thorpe4 ,as they contain a mixture of marine1 land1 and fresh-water shells1 with bones of fish and mammalia1 it is clear that these beds have been accumulated at the bottom of a sea near the mouth of a river4 ,they form patches rarely exceeding twenty feet in thickness1 resting on white chalk4 ,at their junction with the chalk there invariably intervenes a bed called the 8,stone-bed10 composed of unrolled chalk-flints1 commonly of large size1 mingled with the remains of a land fauna comprising ,mastodon arvernensis1 ,elephas meridionalis1 and an extinct species of deer4 ,the mastodon1 which is a species characteristic of the ,pliocene strata of ,italy and ,france1 is the most abundant fossil1 and one not found in the ,cromer forest before mentioned4 ,when these flints1 probably long exposed in the atmosphere1 became submerged1 they were covered with barnacles1 and the surface of the chalk became perforated by the ,pholas crispata1 each fossil shell still remaining at the bottom of its cylindrical cavity1 now filled up with loose sand from the incumbent crag4 ,this species of ,pholas still exists1 and drills the rocks between high and low water on the ,british coast4 ,the name of 8,fluvio-marine0 has often been given to this formation1 as no less than twenty species of land and fresh-water shells have been found in it4 ,they are all of living species2 at least only one univalve1 ,paludina lenta1 has any1 and that a very doubtful1 claim to be regarded as extinct4 ,fig4 #aai3 ,nucula ,cobboldi2 ,fig4 #abj3 ,tellina obliqua4 ,of the marine shells1 #abd in number1 about #ah per cent are extinct1 according to the latest estimate given me by ,mr4 ,searles ,wood2 but1 for reasons presently to be mentioned1 this percentage must be only regarded as provisional4 ,it must also be borne in mind that the proportion of recent shells would be augmented if the uppermost beds at ,bramerton1 near ,norwich1 which belong to the most modern or ,chillesford division of the ,crag1 had been included1 as they were formerly1 by ,mr4 ,woodward and myself1 in the ,norwich series4 ,arctic shells1 which formed so large a proportion in the ,chillesford and ,aldeby beds1 are more rare in the ,norwich ,crag1 though many northern species--such as ,rhynchonella psittacea1 ,scalaria ,grnlandica1 ,astarte borealis1 ,panopa ,norvegia1 and others--still occur4 ,the ,nucula ,cobboldi and ,tellina obliqua1 ,figs4 #aai and #abj1 before mentioned1 p4 #aid1 are frequent in these beds1 as are also ,littorina littorea1 ,cardium edule1 and ,turritella communis1 of our seas1 proving the littoral origin of the beds4 ,,older ,,pliocene ,,strata4 ,red ,crag4--,among the ,english ,pliocene beds the next in antiquity is the ,red ,crag1 which often rests immediately on the ,london ,clay1 as in the county of ,essex1 illustrated in ,fig4 #aba4 ,fig4 #aba3 ,red ,crag1 ,london clay and chalk4 ,it is chiefly in the county of ,suffolk that it is found1 rarely exceeding twenty feet in thickness1 and sometimes overlying another ,pliocene deposit1 the ,coralline ,crag1 to be mentioned in the sequel4 ,it has yielded--exclusive of #be species regarded by ,mr4 ,wood as derivative--#bef species of mollusca1 of which #fe1 or #be per cent1 are extinct4 ,thus1 apart from its order of superposition1 its greater antiquity than the ,norwich and glacial beds1 already described1 is proved by the greater departure from the fauna of our seas4 ,it may also be observed that in most of the deposits of this ,red ,crag1 the northern forms of the ,norwich ,crag1 and of such glacial formations as ,bridlington1 are less numerous1 while those having a more southern aspect begin to make their appearance4 ,both the quartzose sand1 of which it chiefly consists1 and the included shells1 are most commonly distinguished by a deep ferruginous or ochreous colour1 whence its name4 ,the shells are often rolled1 sometimes comminuted1 and the beds have much the appearance of having been shifting sand-banks1 like those now forming on the ,dogger-bank1 in the sea1 sixty miles east of the coast of ,northumberland4 ,cross stratification is almost always present1 the planes of the strata being sometimes directed towards one point of the compass1 sometimes to the opposite1 in beds immediately overlying4 ,that such a structure is not deceptive or due to any subsequent concretionary rearrangement of particles1 or to mere bands of colour produced by the iron1 is proved by each bed being made up of flat pieces of shell which lie parallel to the planes of the smaller strata4 ,it has long been suspected that the different patches of ,red ,crag are not all of the same age1 although their chronological relation cannot be decided by superposition4 ,separate masses are characterised by shells specifically distinct or greatly varying in relative abundance1 in a manner implying that the deposits containing them were separated by intervals of time4 ,at ,butley1 ,tunstall1 ,sudbourn1 and in the ,red ,crag of ,chillesford1 the mollusca appear to assume their most modern aspect when the climate was colder than when the earliest deposits of the same period were formed4 ,at ,butley1 ,nucula ,cobboldi1 so common in the ,norwich and certain glacial beds1 is found1 and ,purpura tetragona 7,fig4 #abb7 is very abundant4 ,on the other hand1 at ,walton-on-the-,naze1 in ,essex1 we seem to have an exhibition of the oldest phase of the ,red ,crag2 and a warmer climate seems indicated1 not only by the absence of many northern forms1 but also by the abundance of some now living in the ,british seas and the ,mediterranean4 ,voluta ,lamberti 7see ,figs4 #abc and #abd71 an extinct form1 which seems to have flourished chiefly in the antecedent ,coralline ,crag period1 is still represented here by individuals of every age4 ,fig4 #abb3 ,purpura tetragona4 ,the reversed whelk 7,fig4 #abe7 is common at ,walton1 where the dextral form of that shell is unknown4 ,here also we find most frequently specimens of lamellibranchiate molluscs1 with both the valves united1 showing that they belonged to this sea of the ,upper ,crag1 and were not washed in from an older bed1 such as the ,coralline1 in which case the ligament would not have held together the valves in strata so often showing signs of the boisterous action of the waves4 ,no less than forty species of lamellibranchiate molluscs1 with double valves1 have been collected by ,mr4 ,bell from the various localities of the ,red ,crag4 ,fig4 #abc3 ,voluta ,lamberti2 ,fig4 #abd3 ,voluta ,lamberti2 ,fig4 #abe3 ,trophon antiquum4 ,at and near the base of the ,red ,crag is a loose bed of brown nodules1 first noticed by ,professor ,henslow as containing a large percentage of earthy phosphates4 ,this bed of coprolites 7as it is called1 because they were originally supposed to be the fces of animals7 does not always occur at one level1 but is generally in largest quantity at the junction of the ,crag and the underlying formation4 ,in thickness it usually varies from six to eighteen inches1 and in some rare cases amounts to many feet4 ,it has been much used in agriculture for manure1 as not only the nodules1 but many of the separate bones associated with them1 are largely impregnated with phosphate of lime1 of which there is sometimes as much as sixty per cent4 ,they are not unfrequently covered with barnacles1 showing that they were not formed as concretions in the stratum where they now lie buried1 but had been previously consolidated4 ,the phosphatic nodules often collect fossil crabs and fishes from the ,london ,clay1 together with the teeth of gigantic sharks4 ,in the same bed have been found many ear-bones of whales1 and the teeth of ,mastodon arvernensis1 ,rhinoceros ,schleiermacheri1 ,tapirus priscus1 and ,hipparion 7a quadruped of the horse family71 and antlers of a stag1 ,cervus anoceros4 ,organic remains also of the older chalk and ,lias are met with1 showing how great was the denudation of previous formations during the ,pliocene period4 ,as the older ,white ,crag1 presently to be mentioned1 contains similar phosphatic nodules near its base1 those of the ,red ,crag may be partly derived from this source4 ,white or ,coralline ,crag4--,the lower or ,coralline ,crag is of very limited extent1 ranging over an area about twenty miles in length1 and three or four in breadth1 between the rivers ,stour and ,alde1 in ,suffolk4 ,it is generally calcareous and marly--often a mass of comminuted shells1 and the remains of bryozoa#b 7or polyzoa71 passing occasionally into a soft building-stone4 ,at ,sudbourn and ,gedgrave1 near ,orford1 this building-stone has been largely quarried4 ,at some places in the neighbourhood the softer mass is divided by thin flags of hard limestone1 and bryozoa placed in the upright position in which they grew4 ,from the abundance of these coralloid mollusca the lowest or ,white ,crag obtained its popular name1 but true corals1 as now defined1 or zoantharia1 are very rare in this formation4 ,the ,coralline ,crag rarely1 if ever1 attains a thickness of thirty feet in any one section4 ,mr4 ,prestwich imagines that if the beds found at different localities were united in the probable order of their succession1 they might exceed eighty feet in thickness1 but ,mr4 ,searles ,wood does not believe in the possibility of establishing such a chronological succession by aid of the organic remains1 and questions whether proof could be obtained of more than forty feet4 ,i was unable to come to any satisfactory opinion on the subject1 although at ,orford1 especially at ,gedgrave1 in the neighbourhood of that place1 ,i saw many sections in pits1 where this crag is cut through4 ,these pits are so unconnected1 and of such limited extent1 that no continuous section of any length can be obtained1 so that speculations as to the thickness of the whole deposit must be very vague4 ,at the base of the formation at ,sutton a bed of phosphatic nodules1 very similar to that before alluded to in the ,red ,crag1 with remains of mammalia1 has been met with4 ,fig4 #abf3 ,section near ,woodbridge1 in ,suffolk4 ,whenever the ,red and ,coralline ,crag occur in the same district1 the ,red ,crag lies uppermost2 and in some cases1 as in the section represented in ,fig4 #abf1 which ,i had an opportunity of seeing exposed to view in #ahci1 it is clear that the older deposit1 or ,coralline ,crag1 b1 had suffered denudation1 before the newer formation1 a1 was thrown down upon it4 ,at ,d there was not only seen a distinct cliff1 eight or ten feet high1 of ,coralline ,crag1 running in a direction ,n4,e4 and ,s4,w41 against which the ,red ,crag abuts with its horizontal layers1 but this cliff occasionally overhangs4 ,the rock composing it is drilled everywhere by ,pholades1 the holes which they perforated having been afterwards filled with sand1 and covered over when the newer beds were thrown down4 ,the older formation is shown by its fossils to have accumulated in a deeper sea1 and contains none of those littoral forms such as the limpet1 ,patella1 found in the ,red ,crag4 ,so great an amount of denudation could scarcely take place1 in such incoherent materials1 without some of the fossils of the inferior beds becoming mixed up with the overlying crag1 so that considerable difficulty must be occasionally experienced by the palontologist in deciding which species belong severally to each group4 ,fig4 #abg3 ,fascicularia aurantium1 from the inferior or ,coralline ,crag1 ,suffolk4 ,fig4 #abh3 ,astarte ,omalii1 species common to ,upper and ,lower ,crag4 ,mr4 ,searles ,wood estimates the total number of marine testaceous mollusca of the ,coralline ,crag at #cej1 of which #aaj are not known as living1 being in the proportion of thirty-one per cent extinct4 ,no less than #acj species of bryozoa have been found in the ,coralline ,crag1 and some belong to genera unknown in the living creation1 and of a very peculiar structure2 as1 for example1 that represented in ,fig4 #abg1 which is one of several species having a globular form4 ,among the testacea the genus ,astarte 7see ,fig4 #abh7 is largely represented1 no less than fourteen species being known1 and many of these being rich in individuals4 ,there is an absence of genera peculiar to hot climates1 such as ,conus1 ,oliva1 ,fasciolaria1 ,crassatella1 and others4 ,the absence also of large cowries 7,cyprea71 those found belonging exclusively to the section ,trivia1 is remarkable4 ,the large volute1 called ,voluta ,lamberti 7,fig4 #abc1 p4 #aif71 may seem an exception2 but it differs in form from the volutes of the torrid zone1 and1 like the living ,voluta ,magellanica1 must have been fitted for an extra-tropical climate4 ,fig4 #abi3 ,lingula ,dumortieri4 ,fig4 #acj3 ,pyrula reticulata4 ,fig4 #aca3 ,temnechinus excavatus4 ,the occurrence of a species of ,lingula at ,sutton 7see ,fig4 #abi7 is worthy of remark1 as these ,brachiopoda seem now confined to more equatorial latitudes2 and the same may be said still more decidedly of a species of ,pyrula1 supposed by ,mr4 ,wood to be identical with ,p4 reticulata 7,fig4 #acj71 now living in the ,indian ,ocean4 ,a genus also of echinoderms1 called by ,professor ,forbes ,temnechinus 7,fig4 #aca71 occurs in the ,red and ,coralline ,crag of ,suffolk1 and until lately was unknown in a living state1 but it has been brought to light as an existing form by the deep-sea dredgings1 both of the ,united ,states survey1 off ,florida1 at a depth of from #ahj to #dhj feet1 and more recently 7#ahfi71 in the ,british seas1 during the explorations of the 8,porcupine40 ,climate of the ,crag ,deposits4--,one of the most interesting conclusions deduced from a careful comparison of the shells of the ,british ,pliocene strata and the fauna of our present seas has been pointed out by ,professor ,e4 ,forbes4 ,it appears that1 during the ,glacial period1 a period intermediate1 as we have seen1 between that of the ,crag and our own time1 many shells1 previously established in the temperate zone1 retreated southward to avoid an uncongenial climate1 and they have been found fossil in the ,newer ,pliocene strata of ,sicily1 ,southern ,italy1 and the ,grecian ,archipelago1 where they may have enjoyed1 during the era of floating icebergs1 a climate resembling that now prevailing in higher ,european latitudes4#c ,the ,professor gave a list of fifty shells which inhabited the ,british seas while the ,coralline and ,red ,crag were forming1 and which1 though now living in our seas1 were wanting1 as far as was then known1 in the glacial deposits4 ,some few of these species have subsequently been found in the glacial drift1 but the general conclusion of ,forbes remains unshaken4 ,the transport of blocks by ice1 when the ,red ,crag was being deposited1 appears to me evident from the large size of some huge1 irregular1 quite unrounded chalk flints1 retaining their white coating1 and #b feet long by #ah inches broad1 in beds worked for phosphatic nodules at ,foxhall1 four miles south-east of ,ipswich4 ,these must have been tranquilly drifted to the spot by floating ice4 ,mr4 ,prestwich also mentions the occurrence of a large block of porphyry in the base of the ,coralline ,crag at ,sutton1 which would imply that the ice-action had begun in our seas even in this older period4 ,the cold seems to have gone on increasing from the time of the ,coralline to that of the ,norwich ,crag1 and became more and more severe1 not perhaps without some oscillations of temperature1 until it reached its maximum in what has been called the ,glacial period1 or at the close of the ,newer ,pliocene1 and in the ,post-pliocene periods4 ,relation of the ,fauna of the ,crag to that of the recent ,seas4--,by far the greater number of the recent marine species occurring in the several ,crag formations are still inhabitants of the ,british seas2 but even these differ considerably in their relative abundance1 some of the commonest of the ,crag shells being now extremely scarce--as1 for example1 ,buccinum ,dalei--while others1 rarely met with in a fossil state1 are now very common1 as ,murex erinaceus and ,cardium echinatum4 ,some of the species also1 the identity of which with the living would not be disputed by any conchologist1 are nevertheless distinguishable as varieties1 whether by slight deviations in form or a difference in average dimensions4 ,since ,mr4 ,searles ,wood first described the marine testacea of the ,crags1 the additions made to that fossil fauna have not been considerable1 whereas we have made in the same period immense progress in our knowledge of the living testacea of the ,british and arctic seas1 and of the ,mediterranean4 ,by this means the naturalist has been enabled to identify with existing species many forms previously supposed to be extinct4 ,in the forthcoming supplement to the invaluable monograph communicated by ,mr4 ,wood to the ,palontographical ,society1 in which he has completed his figures and descriptions of the ,british crag shells of every age1 list will be found of all the fossil shells1 of which a summary is given in the table1 p4 #bjb4 ,to begin with the uppermost or ,chillesford beds1 it will be seen that about #i per cent only are extinct1 or not known as living1 whereas in the ,norwich1 which succeeds in the descending order1 seventeen in a hundred are extinct4 ,formerly1 when the ,norwich or ,fluvio-marine ,crag was spoken of1 both these formations were included under the same head1 for both at ,bramerton and ,thorpe1 the chief localities where the ,norwich ,crag was studied1 an overlying deposit occurs referable to the ,chillesford age4 ,if now the two were fused together as of old1 their shells would1 according to ,mr4 ,wood1 yield a percentage of fifteen in a hundred of species extinct or not known as living4 ,,number ,,of ,,known ,,species ,,of ,,marine ,,testacea ,,in ,,the ,,crag4 ,,chillesford ,,and ,,aldeby ,,beds ,total number ,not known as living ,percentage of ,shells not known as living ,bivalves #fa #d #ie ,univalves #cc #e ,brachiopods #j #j ,,norwich ,,or ,,fluvio-,,marine ,,crag ,bivalves #fa #aj #age ,univalves #fd #ab ,brachiopods #a #j ,,red ,,crag 7,exclusive to many derivative shells7 ,bivalves #abh #ca #bej ,univalves #abg #cc ,brachiopods #a #a ,,coralline ,,crag ,bivalves #afa #dg #cae ,univalves #ahd #fj ,brachiopods #e #c ,to come next to the ,red ,crag1 the reader will observe that a percentage of #be is given of shells unknown as living1 and this increases to #ca in the antecedent ,coralline ,crag4 ,but the gap between these two stages of our ,pliocene deposits is really wider than these numbers would indicate1 for several reasons4 ,in the first place1 the ,coralline ,crag is more strictly the product of a single period1 the ,red ,crag1 as we have seen1 consisting of separate and independent patches1 slightly varying in age1 of which the newest is probably not much anterior to the ,norwich ,crag4 ,secondly1 there was a great change of conditions1 both as to the depth of the sea and climate1 between the periods of the ,coralline and ,red ,crag1 causing the fauna in each to differ far more widely than would appear from the above numerical results4 ,the value of the analysis given in the above table of the shells of the ,red and ,coralline ,crags is in no small degree enhanced by the fact that they were all either collected by ,mr4 ,wood himself1 or obtained by him direct from their discoverers1 so that he was enabled in each case to test their authenticity1 and as far as possible to avoid those errors which arise from confounding together shells belonging to the sea of a newer deposit1 and those washed into it from a formation of older date4 ,the danger of this confusion may be conceived when we remember that the number of species rejected from the ,red ,crag as derivative by ,mr4 ,wood is no less than #be4 ,some geologists have held that on the same grounds it is necessary to exclude as spurious some of the species found in the ,norwich ,crag proper2 but ,mr4 ,wood does not entertain this view1 believing that the spurious shells which have sometimes found their way into the lists of this crag have been introduced by want of care from strata of ,red ,crag4 ,there can be no doubt1 on the other hand1 that conchologists have occasionally rejected from the ,red and ,norwich ,crags1 as derivative1 shells which really belonged to the seas of those periods1 because they were extinct or unknown as living1 which in their eyes afforded sufficient ground for suspecting them to be intruders4 ,the derivative origin of a species may sometimes be indicated by the extreme scarcity of the individuals1 their colour1 and worn condition2 whereas an opposite conclusion may be arrived at by the integrity of the shells1 especially when they are of delicate and tender structure1 or their abundance1 and1 in the case of the lamellibranchiata1 by their being held together by the ligament1 which often happens when the shells have been so broken that little more than the hinges of the two valves are preserved4 ,as to the univalves1 ,i have seen from a pit of ,red ,crag1 near ,woodbridge1 a large individual of the extinct ,voluta ,lamberti1 seven inches in length1 of which the lip1 then perfect1 had in former stages of its growth been frequently broken1 and as often repaired4 ,it had evidently lived in the sea of the ,red ,crag1 where it had been exposed to rough usage1 and sustained injuries like those which the reversed whelk1 ,trophon antiquum1 so characteristic of the same formation1 often exhibits4 ,additional proofs1 however1 have lately been obtained by ,mr4 ,searles ,wood that this shell had not died out in the era of the ,red ,crag by the discovery of the same fossil near ,southwold1 in beds of the later ,norwich ,crag4 ,antwerp ,crag4--,strata of the same age as the ,red and ,coralline ,crag of ,suffolk have been long known in the country round ,antwerp1 and on the banks of the ,scheldt1 below that city2 and the lowest division1 or ,black ,crag1 there found1 is shown by the shells to be somewhat more ancient than any of our ,british series1 and probably forms the first links of a downward passage from the strata of the ,pliocene to those of the ,upper ,miocene period4 ,fig4 #acb3 ,murex vaginatus ,newer ,pliocene ,strata of ,sicily4--,at several points north of ,catania1 on the eastern sea-coast of ,sicily--as at ,aci-,castello1 for example1 ,trezza1 and ,nizzeti--marine strata1 associated with volcanic tuffs and basaltic lavas1 are seen1 which belong to a period when the first igneous eruptions of ,mount ,etna were taking place in a shallow bay of the ,mediterranean4 ,they contain numerous fossil shells1 and out of #adb species that have been collected all but eleven are identical with species now living4 ,some few of these eleven shells may possibly still linger in the depths of the ,mediterranean1 like ,murex vaginatus1 see ,fig4 #acb4 ,the last-mentioned shell had already become rare when the associated marine and volcanic strata above alluded to were formed4 ,on the whole1 the modern character of the testaceous fauna under consideration is expressed not only by the small proportion of extinct species1 but by the relative number of individuals by which most of the other species are represented1 for the proportion agrees with that observed in the present fauna of the ,mediterranean4 ,the rarity of individuals in the extinct species is such as to imply that they were already on the point of dying out1 having flourished chiefly in the earlier ,pliocene times1 when the ,subapennine strata were in progress4 ,yet since the accumulation of these ,newer ,pliocene sands and clays1 the whole cone of ,etna1 #aa1jjj feet in height and about #ij miles in circumference at its base1 has been slowly built up2 an operation requiring many tens of thousands of years for its accomplishment1 and to estimate the magnitude of which it is necessary to study in detail the internal structure of the mountain1 and to see the proofs of its double axis1 or the evidence of the lavas of the present great centre of eruption having gradually overwhelmed and enveloped a more ancient cone1 situated #c miles to the east of the present one4#d ,it appears that while ,etna was increasing in bulk by a series of eruptions1 its whole mass1 comprising the foundations of subaqueous origin above alluded to1 was undergoing a slow upheaval1 by which those marine strata were raised to the height of #abjj feet above the sea1 as seen at ,catera1 and perhaps to greater heights1 for we cannot trace their extension westward1 owing to the dense and continuous covering of modern lava under which they are buried4 ,during the gradual rise of these ,newer ,pliocene formations 7consisting of clays1 sands1 and basalts7 other strata of ,post-pliocene date1 marine as well as fluviatile1 accumulated round the base of the mountain1 and these1 in their turn1 partook of the upward movement1 so that several inland cliffs and terraces at low levels1 due partly to the action of the sea and partly to the river ,simeto1 originated in succession4 ,fossil remains of the elephant1 and other extinct quadrupeds1 have been found in these ,post-,pliocene strata1 associated with recent shells4 ,there is probably no part of ,europe where the ,newer ,pliocene formations enter so largely into the structure of the earth's crust1 or rise to such heights above the level of the sea1 as ,sicily4 ,they cover nearly half the island1 and near its centre1 at ,castrogiovanni1 reach an elevation of #cjjj feet4 ,they consist principally of two divisions1 the upper calcareous and the lower argillaceous1 both of which may be seen at ,syracuse1 ,girgenti1 and ,castrogiovanni4 ,according to ,philippi1 to whom we are indebted for the best account of the tertiary shells of this island1 thirty-five species out of one hundred and twenty-four obtained from the beds in central ,sicily are extinct4 ,a geologist1 accustomed to see nearly all the ,newer ,pliocene formations in the north of ,europe occupying low grounds and very incoherent in texture1 is naturally surprised to behold formations of the same age so solid and stony1 of such thickness1 and attaining so great an elevation above the level of the sea4 ,the upper or calcareous member of this group in ,sicily consists in some places of a yellowish-white stone1 like the ,calcaire ,grossier of ,paris2 in others1 of a rock nearly as compact as marble4 ,its aggregate thickness amounts sometimes to #gjj or #hjj feet4 ,it usually occurs in regular horizontal beds1 and is occasionally intersected by deep valleys1 such as those of ,sortino and ,pentalica1 in which are numerous caverns4 ,the fossils are in every stage of preservation1 from shells retaining portions of their animal matter and colour to others which are mere casts4 ,the limestone passes downward into a sandstone and conglomerate1 below which is clay and blue marl1 from which perfect shells and corals may be disengaged4 ,the clay sometimes alternates with yellow sand4 ,south of the plain of ,catania is a region in which the tertiary beds are intermixed with volcanic matter1 which has been for the most part the product of submarine eruptions4 ,it appears that1 while the clay1 sand1 and yellow limestone before mentioned were in course of deposition at the bottom of the sea1 volcanoes burst out beneath the waters1 like that of ,graham ,island1 in #ahca1 and these explosions recurred again and again at distant intervals of time4 ,volcanic ashes and sand were showered down and spread by the waves and currents so as to form strata of tuff1 which are found intercalated between beds of limestone and clay containing marine shells1 the thickness of the whole mass exceeding #bjjj feet4 ,the fissures through which the lava rose may be seen in many places1 forming what are called dikes4 ,fig4 #acc3 ,pecten jacobus ,no shell is more conspicuous in these ,sicilian strata than the great scallop1 ,pecten jacobus 7,fig4 #acc71 now so common in the neighbouring seas4 ,the more we reflect on the preponderating number of this and other recent shells1 the more we are surprised at the great thickness1 solidity1 and height above the sea of the rocky masses in which they are entombed1 and the vast amount of geographical change which has taken place since their origin4 ,it must be remembered that1 before they began to emerge1 the uppermost strata of the whole must have been deposited under water4 ,in order1 therefore1 to form a just conception of their antiquity1 we must first examine singly the innumerable minute parts of which the whole is made up1 the successive beds of shells1 corals1 volcanic ashes1 conglomerates1 and sheets of lava2 and we must afterwards contemplate the time required for the gradual upheaval of the rocks1 and the excavation of the valleys4 ,the historical period seems scarcely to form an appreciable unit in this computation1 for we find ancient ,greek temples1 like those of ,girgenti 7,agrigentum71 built of the modern limestone of which we are speaking1 and resting on a hill composed of the same2 the site having remained to all appearances unaltered since the ,greeks first colonised the island4 ,it follows1 from the modern geological date of these rocks1 that the fauna and flora of a large part of ,sicily are of higher antiquity than the country itself4 ,the greater part of the island has been raised above the sea since the epoch of existing species1 and the animals and plants now inhabiting it must have migrated from adjacent countries1 with whose productions the species are now identical4 ,the average duration of species would seem to be so great that they are destined to outlive many important changes in the configuration of the earth's surface1 and hence the necessity for those innumerable contrivances by which they are enabled to extend their range to new lands as they are formed1 and to escape from those which sink beneath the sea4 ,newer ,pliocene ,strata of the ,upper ,val ,d'arno4--,when we ascend the ,arno for about ten miles above ,florence1 we arrive at a deep narrow valley called the ,upper ,val d',arno1 which appears once to have been a lake1 at a time when the valley below ,florence was an arm of the sea4 ,the horizontal lacustrine strata of this upper basin are twelve miles long and two broad4 ,the depression which they fill has been excavated out of ,eocene and ,cretaceous rocks1 which form everywhere the sides of the valley in highly inclined stratification4 ,the thickness of the more modern and unconformable beds is about #gej feet1 of which the upper #bjj feet consist of ,newer ,pliocene strata1 while the lower are ,older ,pliocene4 ,the newer series are made up of sands and a conglomerate called 8sansino40 ,among the imbedded fossil mammalia are ,mastodon arvernensis1 ,elephas meridionalis1 ,rhinoceros etruscus1 ,hippopotamus major1 and remains of the genera bear1 hyna1 and felis1 nearly all of which occur in the ,cromer forest-bed 7see ,chap4 #ac1 p4 #aia74 ,in the same upper strata are found1 according to ,m4 ,gaudin1 the leaves and cones of ,glyptostrobus europus1 a plant closely allied to ,g4 heterophyllus1 now inhabiting the north of ,china and ,japan4 ,this conifer had a wide range in time1 having been traced back to the ,lower ,miocene strata of ,switzerland1 and being common at ningen in the ,upper ,miocene1 as we shall see in the sequel 7p4 #bah74 ,older ,pliocene of ,italy4--,subapennine ,strata4--,the ,apennines1 it is well-known1 are composed chiefly of ,secondary or ,mesozoic rocks1 forming a chain which branches off from the ,ligurian ,alps and passes down the middle of the ,italian peninsula4 ,at the foot of these mountains1 on the side both of the ,adriatic and the ,mediterranean1 are found a series of tertiary strata1 which form1 for the most part1 a line of low hills occupying the space between the older chain and the sea4 ,brocchi was the first ,italian geologist who described this newer group in detail1 giving it the name of the ,subapennine4 ,though chiefly composed of ,older ,pliocene strata1 it belongs1 nevertheless1 in part1 both to older and newer members of the tertiary series4 ,the strata1 for example1 of the ,superga1 near ,turin1 are ,miocene2 those of ,asti and ,parma ,older ,pliocene1 as is the blue marl of ,sienna2 while the shells of the incumbent yellow sand of the same territory approach more nearly to the recent fauna of the ,mediterranean1 and may be ,newer ,pliocene4 ,we have seen that most of the fossil shells of the ,older ,pliocene strata of ,suffolk which are of recent species are identical with testacea now living in ,british seas1 yet some of them belong to ,mediterranean species1 and a few even of the genera are those of warmer climates4 ,we might therefore expect1 in studying the fossils of corresponding age in countries bordering the ,mediterranean1 to find among them some species and genera of warmer latitudes4 ,accordingly1 in the marls belonging to this period at ,asti1 ,parma1 ,sienna1 and parts of the ,tuscan and ,roman territories1 we observe the genera ,conus1 ,cypra1 ,strombus1 ,pyrula1 ,mitra1 ,fasciolaria1 ,sigaretus1 ,delphinula1 ,ancillaria1 ,oliva1 ,terebellum1 ,terebra1 ,perna1 ,plicatula1 and ,corbis1 some characteristic of tropical seas1 others represented by species more numerous or of larger size than those now proper to the ,mediterranean4 ,older ,pliocene ,flora of ,italy4--,i have already alluded to the ,newer ,pliocene deposits of the ,upper ,val d',arno above ,florence1 and stated that below those sands and conglomerates1 containing the remains of the ,elephas meridionalis and other associated quadrupeds1 lie an older horizontal and conformable series of beds1 which may be classed as ,older ,pliocene4 ,they consist of blue clays with some subordinate layers of lignite1 and exhibit a richer flora than the overlying ,newer ,pliocene beds1 and one receding farther from the existing vegetation of ,europe4 ,they also comprise more species common to the antecedent ,miocene period4 ,among the genera of flowering plants1 ,m4 ,gaudin enumerates pine1 oak1 evergreen oak1 plum1 plane1 alder1 elm1 fig1 laurel1 maple1 walnut1 birch1 buckthorn1 hickory1 sumach1 sarsaparilla1 sassafras1 cinnamon1 ,glyptostrobus1 ,taxodium1 ,sequoia1 ,persea1 ,oreodaphne 7,fig4 #acd71 ,cassia1 and ,psoralea1 and some others4 ,this assemblage of plants indicates a warm climate1 but not so subtropical an one as that of the ,upper ,miocene period1 which will presently be considered4 ,fig4 #acd3 ,creodaphne ,heerii4 ,fig4 #ace3 ,liquidambar europum1 var4 trilobatum ,fig4 #acd3 ,creodaphne ,heerii4 ,leaf#e ,fig4 #ace3 ,liquidambar europum1 var4 trilobatum1 ,a4 ,br4 7sometimes four-lobed1 and more commonly five-lobed74 a4 ,leaf4 b4 ,part of same4 c4 ,fruit4 d4 ,seed ningen4 ,m4 ,gaudin1 jointly with the ,marquis ,strozzi1 has thrown much light on the botany of beds of the same age in another part of ,tuscany1 at a place called ,montajone1 between the rivers ,elsa and ,evola1 where1 among other plants1 is found the ,oreodaphne ,heerii1 ,gaud4 7see ,fig4 #acd71 which is probably only a variety of ,oreodaphne foetens1 or the laurel called the ,til in ,madeira1 where1 as in the ,canaries1 it constitutes a large portion of the native woods1 but cannot now endure the climate of ,europe4 ,in the fossil specimens the same glands or protuberances are preserved#f 7see ,fig4 #acd7 as those which are seen in the axils of the primary veins of the leaves in the recent ,til4 ,another plant also indicating a warmer climate is the ,liquidambar europum1 ,brong4 7see ,fig4 #ace71 a species nearly allied to ,l4 styracifluum1 ,l41 which flourishes in most places in the ,southern ,states of ,north ,america1 on the borders of the ,gulf of ,mexico4 #a ,see ,antiquity of ,man1 chap4 xiv4 #b ,ehrenberg proposed in #ahca the term ,bryozoum1 or 8,moss-animal10 for the molluscous or ascidian form of polyp1 characterised by having two openings to the digestive sack1 as in ,eschara1 ,flustra1 ,retepora1 and other zoophytes popularly included in the corals1 but now classed by naturalists as mollusca4 ,the term ,polyzoum1 synonymous with ,bryozoum1 was1 it seems1 proposed in #ahcj1 or the year before1 by ,mr4 ,j4 ,o4 ,thompson4 #c ,e4 ,forbes ,mem4 ,geol4 ,survey of ,gt4 ,brit41 vol4 i1 p4 #chf4 #d ,see a ,memoir on the ,lavas and ,mode of ,origin of ,mount ,etna by the ,author in ,phil4 ,trans41 #aheh4 #e ,feuilles fossiles de la ,toscane4 #f ,contributions la ,flore fossile ,italienne4 ,gaudin and ,strozzi4 ,plate #aa1 ,fig4 #c4 ,gaudin1 p4 #bb4 ,,chapter ,,xiv4 ,,miocene ,,period--,,upper ,,miocene4 ,upper ,miocene ,strata of ,france--,faluns of ,touraine4 -- ,tropical ,climate implied by ,testacea4 -- ,proportion of recent ,species of ,shells4 -- faluns more ancient than the ,suffolk ,crag4 -- ,upper ,miocene of ,bordeaux and the ,south of ,france4 -- ,upper ,miocene of ningen1 in ,switzerland4 -- ,plants of the ,upper ,fresh-water ,molasse4 -- ,fossil ,fruit and ,flowers as well as ,leaves4 -- ,insects of the ,upper ,molasse4 -- ,middle or ,marine ,molasse of ,switzerland4 -- ,upper ,miocene ,beds of the ,bolderberg1 in ,belgium4 -- ,vienna ,basin4 -- ,upper ,miocene of ,italy and ,greece4 -- ,upper ,miocene of ,india2 ,siwalik ,hills4 -- ,older ,pliocene and ,miocene of the ,united ,states4 ,upper ,miocene ,strata of ,france--,faluns of ,touraine4--,the strata which we meet with next in the descending order are those called by many geologists 8,middle ,tertiary10 for which in #ahcc ,i proposed the name of ,miocene1 selecting the 8faluns0 of the valley of the ,loire1 in ,france1 as my example or type4 ,i shall now call these falunian deposits ,upper ,miocene1 to distinguish them from others to which the name of ,lower ,miocene will be given4 ,no ,british strata have a distinct claim to be regarded as ,upper ,miocene1 and as the ,lower ,miocene are also but feebly represented in the ,british ,isles1 we must refer to foreign examples in illustration of this important period in the earth's history4 ,the term 8faluns0 is given provincially by ,french agriculturists to shelly sand and marl spread over the land in ,touraine1 just as similar shelly deposits were formerly much used in ,suffolk to fertilise the soil1 before the coprolitic or phosphatic nodules came into use4 ,isolated masses of such faluns occur from near the mouth of the ,loire1 in the neighbourhood of ,nantes1 to as far inland as a district south of ,tours4 ,they are also found at ,pontlevoy1 on the ,cher1 about seventy miles above the junction of that river with the ,loire1 and thirty miles south-east of ,tours4 ,deposits of the same age also appear under new mineral conditions near the towns of ,dinan and ,rennes1 in ,brittany4 ,i have visited all the localities above enumerated1 and found the beds on the ,loire to consist principally of sand and marl1 in which are shells and corals1 some entire1 some rolled1 and others in minute fragments4 ,in certain districts1 as at ,dou1 in the ,department of ,maine and ,loire1 ten miles south-west of ,saumur1 they form a soft building-stone1 chiefly composed of an aggregate of broken shells1 bryozoa1 corals1 and echinoderms1 united by a calcareous cement2 the whole mass being very like the ,coralline ,crag near ,aldborough1 and ,sudbourn in ,suffolk4 ,the scattered patches of faluns are of slight thickness1 rarely exceeding fifty feet2 and between the district called ,sologne and the sea they repose on a great variety of older rocks2 being seen to rest successively upon gneiss1 clay-slate1 various secondary formations1 including the chalk2 and1 lastly1 upon the upper fresh-water limestone of the ,parisian tertiary series1 which1 as before mentioned 7p4 #adb71 stretches continuously from the basin of the ,seine to that of the ,loire4 ,fig4 #acf3 ,dinotherium giganteum4 ,at some points1 as at ,louans1 south of ,tours1 the shells are stained of a ferruginous colour1 not unlike that of the ,red ,crag of ,suffolk4 ,the species are1 for the most part1 marine1 but a few of them belong to land and fluviatile genera4 ,among the former1 ,helix turonensis7 7,fig4 #ch7 is the most abundant4 ,remains of terrestrial quadrupeds are here and there intermixed1 belonging to the genera ,dinotherium 7,fig4 #acf71 ,mastodon1 ,rhinoceros1 ,hippopotamus1 ,chropotamus1 ,dichobune1 ,deer1 and others1 and these are accompanied by cetacea1 such as the ,lamantin1 ,morse1 ,sea-calf1 and ,dolphin1 all of extinct species4 ,the fossil testacea of the faluns of the ,loire imply1 according to the late ,edward ,forbes1 that the beds were formed partly on the shore itself at the level of low water1 and partly at very moderate depths1 not exceeding ten fathoms below that level4 ,the molluscan fauna is1 on the whole1 much more littoral than that of the ,pliocene ,red and ,coralline ,crag of ,suffolk1 and implies a shallower sea4 ,it is1 moreover1 contrasted with the ,suffolk ,crag by the indications it affords of an extra-,european climate4 ,thus it contains seven species of ,cypra1 some larger than any existing cowry of the ,mediterranean1 several species of ,oliva1 ,ancillaria1 ,mitra1 ,terebra1 ,pyrula1 ,fasciolaria1 and ,conus4 ,of the cones there are no less than eight species1 some very large1 whereas the only ,european cone now living is of diminutive size4 ,the genus ,nerita1 and many others1 are also represented by individuals of a type now characteristic of equatorial seas1 and wholly unlike any ,mediterranean forms4 ,these proofs of a more elevated temperature seem to imply the higher antiquity of the faluns as compared with the ,suffolk ,crag1 and are in perfect accordance with the fact of the smaller proportion of testacea of recent species found in the faluns4 ,out of #bij species of shells1 collected by myself in #ahdj at ,pontlevoy1 ,louans1 ,bosse1 and other villages twenty miles south of ,tours1 and at ,savign1 about fifteen miles north-west of that place1 seventy-two only could be identified with recent species1 which is in the proportion of twenty-five per cent4 ,a large number of the #bij species are common to all the localities1 those peculiar to each not being more numerous than we might expect to find in different bays of the same sea4 ,the total number of species of testaceous mollusca from the faluns in my possession is #cjb1 of which forty-five only1 or fourteen per cent1 were found by ,mr4 ,wood to be common to the ,suffolk ,crag4 ,the number of corals1 including bryozoa and zoantharia1 obtained by me at ,dou and other localities before adverted to1 amounts to forty-three1 as determined by ,mr4 ,lonsdale1 of which seven 7one of them a zoantharian7 agree specifically with those of the ,suffolk ,crag4 ,some of the genera occurring fossil in ,touraine1 as the corals ,astrea and ,dendrophyllia1 and the bryozoan ,lunulites1 have not been found in ,european seas north of the ,mediterranean2 nevertheless1 the zoantharia of the faluns do not seem to indicate1 on the whole1 so warm a climate as would be inferred from the shells4 ,it was stated that1 on comparing about #cjj species of ,touraine shells with about #dej from the ,suffolk ,crag1 forty-five only were found to be common to both1 which is in the proportion of only fifteen per cent4 ,the same small amount of agreement is found in the corals also4 ,i formerly endeavoured to reconcile this marked difference in species with the supposed co-existence of the two faunas1 by imagining them to have severally belonged to distinct zoological provinces or two seas1 the one opening to the north and the other to the south1 with a barrier of land between them1 like the ,isthmus of ,suez1 now separating the ,red ,sea and the ,mediterranean4 ,but ,i now abandon that idea for several reasons2 among others1 because ,i succeeded in #ahda in tracing the ,crag fauna southward in ,normandy to within seventy miles of the ,falunian type1 near ,dinan1 yet found that both assemblages of fossils retained their distinctive characters1 showing no signs of any blending of species or transition of climate4 ,the principal grounds1 however1 for referring the ,english ,crag to the older ,pliocene and the ,french faluns to the ,upper ,miocene epochs1 consist in the predominance of fossil shells in the ,british strata identifiable with species not only still living1 but which are now inhabitants of neighbouring seas1 while the accompanying extinct species are of genera such as characterise ,europe4 ,in the faluns1 on the contrary1 the recent species are in a decided minority2 and most of them are now inhabitants of the ,mediterranean1 the coast of ,africa1 and the ,indian ,ocean2 in a word1 less northern in character1 and pointing to the prevalence of a warmer climate4 ,they indicate a state of things receding farther from the present condition of ,central ,europe in physical geography and climate1 and doubtless1 therefore1 receding farther from our era in time4 ,fig4 #acg3 ,voluta ,lamberti4 ,among the conspicuous fossils common to the faluns of the ,loire and the ,suffolk ,crag is a variety of the ,voluta ,lamberti1 a shell already alluded to 7,fig4 #abc74 ,the specimens of this shell which ,i have myself collected in ,touraine1 or have seen in museums1 are thicker and heavier than ,british individuals of the same species1 and shorter in proportion to their width1 and have the folds on the columella less oblique1 as represented in ,fig4 #acg4 ,upper ,miocene of ,bordeaux and the ,south of ,france4--,a great extent of country between the ,pyrenees and the ,gironde is overspread by tertiary deposits of various ages1 and chiefly of ,miocene date4 ,some of these1 near ,bordeaux1 coincide in age with the faluns of ,touraine1 already mentioned1 but many of the species of shells are peculiar to the south4 ,the succession of beds in the basin of the ,gironde implies several oscillations of level by which the same wide area was alternately converted into sea and land and into brackish-water lagoons1 and finally into fresh-water ponds and lakes4 ,among the fresh-water strata of this age near the base of the ,pyrenees are marls1 limestones and sands1 in which the eminent comparative anatomist1 ,m4 ,lartet1 has obtained a great number of fossil mammalia common to the faluns of the ,loire and the ,upper ,miocene beds of ,switzerland1 such as ,dinotherium giganteum and ,mastodon angustidens2 also the bones of quadrumana1 or of the ape and monkey tribe1 which were discovered in #ahcg1 the first of that order of quadrupeds detected in ,europe4 ,they were found near ,auch1 in the ,department of ,gers1 in latitude #dc #ci ,n4 ,about forty miles west of ,toulouse4 ,they were referred by ,,mm4 ,lartet and ,blainville to a genus closely allied to the ,gibbon1 to which they gave the name of ,pliopithecus4 ,subsequently1 in #ahef1 ,m4 ,lartet described another species of the same family of long-armed apes 7,hylobates71 which he obtained from strata of the same age at ,saint-,gaudens1 in the ,haute ,garonne4 ,the fossil remains of this animal consisted of a portion of a lower jaw with teeth and the shaft of a humerus4 ,it is supposed to have been a tree-climbing frugivorous ape1 equalling man in stature4 ,as the trunks of oaks are common in the lignite beds in which it lay1 it has received the generic name of ,dryopithecus4 ,the angle formed by the ascending ramus of the jaw and the alveolar border is less open1 and therefore more like the human subject1 than in the ,chimpanzee1 and what is still more remarkable1 the fossil1 a young but adult individual1 had all its milk teeth replaced by the second set1 while its last true molar 7or wisdom-tooth7 was still undeveloped1 or only existed as a germ in the jaw-bone4 ,in the mode1 therefore1 of the succession of its teeth 7which1 as in all the old-,world apes1 exactly agree in number with those in man7 it differed from the ,gorilla and ,chimpanzee1 and corresponded with the human species4 ,upper ,miocene ,beds of ningen1 in ,switzerland4--,the faluns of the ,loire first served1 as already stated 7p4 #baa71 as the type of the ,miocene formations in ,europe4 ,they yielded a plentiful harvest of marine fossil shells and corals1 but were entirely barren of plants and insects4 ,in ,switzerland1 on the other hand1 deposits of the same age have been discovered1 remarkable for their botanical and entomological treasures4 ,we are indebted to ,professor ,heer1 of ,zurich1 for the description1 restoration1 and classification of several hundred species and varieties of these fossil plants1 the whole of which he has illustrated by excellent figures in his 8,flora ,tertiaria ,helveti40 ,this great work1 and those of ,adolphe ,brongniart1 ,unger1 ,goppert and others1 show that this class of fossils is beginning to play the same important part in the classification of the tertiary strata containing lignite or brown coal as an older flora has long played in enabling us to understand the ancient coal or carboniferous formation4 ,no small skepticism has always prevailed among botanists as to whether the leaves alone and the wood of plants could ever afford sufficient data for determining even genera and families in the vegetable kingdom4 ,in truth1 before such remains could be rendered available a new science had to be created4 ,it was necessary to study the outlines1 nervation1 and microscopic structure of the leaves1 with a degree of care which had never been called for in the classification of living plants1 where the flower and fruit afforded characters so much more definite and satisfactory4 ,as geologists1 we cannot be too grateful to those who1 instead of despairing when so difficult a task was presented to them1 or being discouraged when men of the highest scientific attainments treated the fossil leaves as worthless1 entered with full faith and enthusiasm into this new and unexplored field4 ,that they should frequently have fallen into errors was unavoidable1 but it is remarkable1 especially if we inquire into the history of ,professor ,heer's researches1 how often early conjectures as to the genus and family founded on the leaves alone were afterwards confirmed when fuller information was obtained4 ,as examples to be found on comparing ,heer's earlier and later works1 ,i may instance the chestnut1 elm1 maple1 cinnamon1 magnolia1 buckbean or ,menyanthes1 vine1 buckthorn 7,rhamnus71 ,andromeda and ,myrica1 and among the conifers ,sequoia and ,taxodium4 ,in all these cases the plants were first recognised by their leaves1 and the accuracy of the determination was afterwards confirmed when the fruit1 and in some instances both fruit and flower1 were found attached to the same stem as the leaves4 ,but let us suppose that no fruit1 seed1 or flower had ever been met with in a fossil state1 we should still have been indebted to the persevering labours of botanical palontologists for one of the grandest scientific discoveries for which the present century is remarkable--namely1 the proofs now established of the prevalence of a mild climate and a rich arborescent flora in the arctic regions in that ,miocene epoch on the history of which we are now entering4 ,it may be useful if ,i endeavour to give the reader in a few words some idea of the nature of the evidence of these important conclusions1 to show how far they may be safely based on fossil leaves alone4 ,when we begin by studying the fossils of the ,newer ,pliocene deposits1 such as those of the ,upper ,val d',arno1 before alluded to1 we perceive that the fossil foliage agrees almost entirely with the trees and shrubs of a modern ,european forest4 ,in the plants of the ,older ,pliocene strata of the same region we observe a larger proportion of species and genera which1 although they may agree with well-known ,asiatic or other foreign types1 are at present wanting in ,italy4 ,if we then examine the ,miocene formations of the same country1 exotic forms become more abundant1 especially the palms1 whether they belong to the ,european or ,american fan-palms1 ,chamrops and ,sabal1 or to the more tropical family of the date-palms or ,phnicites1 which last are conspicuous in the ,lower ,miocene beds of ,central ,europe4 ,although we have not found the fruit or flower of these palms in a fossil state1 the leaves are so characteristic that no one doubts the family to which they belong1 or hesitates to accept them as indications of a warm and sub-tropical climate4 ,when the ,miocene formations are traced to the northward of the #ejth degree of latitude1 the fossil palms fail us1 but the greater proportion of the leaves1 whether identical with those of existing ,european trees or of forms now unknown in ,europe1 which had accompanied the ,miocene palms1 still continue to characterise rocks of the same age1 until we meet with them not only in ,iceland1 but in ,greenland1 in latitude #gj ,n41 and in ,spitzbergen1 latitude #gh #ef1 or within about #aa degrees of the pole1 and under circumstances which clearly show them to have been indigenous in those regions1 and not to have been drifted from the south 7see p4 #bdj74 ,not only1 therefore1 has the botanist afforded the geologist much palontological assistance in identifying distinct tertiary formations in distant places by his power of accurately discriminating the forms1 veining1 and microscopic structure of leaves or wood1 but1 independently of that exact knowledge derivable from the organs of fructification1 we are indebted to him for one of the most novel1 unexpected results of modern scientific inquiry4 ,the ,miocene formations of ,switzerland have been called ,molasse1 a term derived from the ,french mol1 and applied to a soft1 incoherent1 greenish sandstone1 occupying the country between the ,alps and the ,jura4 ,this molasse comprises three divisions1 of which the middle one is marine1 and being closely related by its shells to the faluns of ,touraine1 may be classed as ,upper ,miocene4 ,the two others are fresh-water1 the upper of which may be also grouped with the faluns1 while the lower must be referred to the ,lower ,miocene1 as defined in the next chapter4 ,upper ,fresh-water ,molasse4--,this formation is best seen at ningen1 in the valley of the ,rhine1 between ,constance and ,schaffhausen1 a locality celebrated for having produced in the year #agjj the supposed human skeleton called by ,scheuchzer 8homo diluvii testis10 a fossil afterwards demonstrated by ,cuvier to be a reptile1 or aquatic salamander1 of larger dimensions than even its great living representative1 the salamander of ,japan4 ,the ningen strata consist of a series of marls and limestones1 many of them thinly laminated1 and which appear to have slowly accumulated in a lake probably fed by springs holding carbonate of lime in solution4 ,the elliptical area over which this fresh-water formation has been traced extends1 according to ,sir ,roderick ,murchison1 for a distance of ten miles east and west from ,berlingen1 on the right bank of the river to ,wangen1 and to ningen1 near ,stein1 on the left bank4 ,the organic remains have been chiefly derived from two quarries1 the lower of which is about #eej feet above the level of the ,lake of ,constance1 while the upper quarry is #aej feet higher4 ,in this last1 a section thirty feet deep displays a great succession of beds1 most of them splitting into slabs and some into very thin lamin4 ,twenty-one beds are enumerated by ,professor ,heer1 the uppermost a bluish-grey marl seven feet thick1 with organic remains1 resting on a limestone with fossil plants1 including leaves of poplar1 cinnamon1 and pond-weed 7,potamogeton71 together with some insects2 while in the bed ,no4 #d1 below1 is a bituminous rock1 in which the ,mastodon tapiroides1 a characteristic ,upper ,miocene quadruped1 has been met with4 ,the #eth bed1 two or three inches thick1 contains fossil fish1 e4g41 ,leuciscus 7roach71 and the larv of dragon-flies1 with plants such as the elm 7,ulmus71 and the aquatic ,chara4 ,below this are other plant-beds2 and then1 in ,no4 #i1 the stone in which the great salamander 7,andrias ,scheuchzeri7 and some fish were found4 ,below this other strata occur with fish1 tortoises1 the great salamander before alluded to1 fresh-water mussels1 and plants4 ,in ,no4 #af the fossil fox of ningen1 ,galecynus ningensis1 ,owen1 was obtained by ,sir ,r4 ,murchison4 ,to this succeed other beds with mammalia 7,lagomys71 reptiles1 7,emys71 fish1 and plants1 such as walnut1 maple1 and poplar4 ,in the #aith bed are numerous fish1 insects1 and plants1 below which are marls of a blue indigo colour4 ,in the lower quarry eleven beds are mentioned1 in which1 as in the upper1 both land and fresh-water plants and many insects occur4 ,in the #fth1 reckoning from the top1 many plants have been obtained1 such as ,liquidambar1 ,daphnogene1 ,podogonium1 and ,ulmus1 together with tortoises1 besides the bones and teeth of a ruminant quadruped1 named by ,h4 von ,meyer ,palomeryx eminens4 ,no4 #i is called the insect-bed1 a layer only a few inches thick1 which1 when exposed to the frost1 splits into leaves as thin as paper4 ,in these thin lamin plants such as ,liquidambar1 ,daphnogene1 and ,glyptostrobus1 occur1 with innumerable insects in a wonderful state of preservation1 usually found singly4 ,below this is an indigo-blue marl1 like that at the bottom of the higher quarry1 resting on yellow marl ascertained to be at least thirty feet thick4 ,fig4 #ach3 ,cinnamomum polymorphum4 ,all the above fossil-bearing strata were evidently formed with extreme slowness4 ,although the fossiliferous beds are1 in the aggregate1 no more than a few yards in thickness1 and have only been examined in the small area comprised in the two quarries just alluded to1 they give us an insight into the state of animal and vegetable life in part of the ,upper ,miocene period1 such as no other region in the world has elsewhere supplied4 ,in the year #ahei1 ,professor ,heer had already determined no less than #dge species of plants and more than #hjj insects from these ningen beds4 ,he supposes that a river entering a lake floated into it some of the leaves and land insects1 together with the carcasses of quadrupeds1 among others a great ,mastodon4 ,occasionally1 during tempests1 twigs and even boughs of trees with their leaves were torn off and carried for some distance so as to reach the lake4 ,springs1 containing carbonate of lime1 seem at some points to have supplied calcareous matter in solution1 giving origin locally to a kind of travertin1 in which organic bodies sinking to the bottom became hermetically sealed up4 ,the lamin1 says ,heer1 which immediately succeed each other were not all formed at the same season1 for it can be shown that1 when some of them originated1 certain plants were in flower1 whereas1 when the next of these layers was produced1 the same plants had ripened their fruit4 ,this inference is confirmed by independent proofs derived from insects4 ,the principal insect-bed is rarely two inches thick1 and is composed1 says ,heer1 of about #bej leaf-like lamin1 some of which were deposited in the spring1 when the ,cinnamomum polymorphum 7,fig4 #ach7 was in flower1 others in summer1 when winged ants were numerous1 and when the poplar and willow had matured their seed2 others1 again1 in autumn1 when the same ,cinnamomum polymorphum 7,fig4 #ach7 was in fruit1 as well as the liquidambar1 oak1 clematis1 and many other plants4 ,the ancient lake seems to have had a belt of poplars and willows round its borders1 countless leaves of which were imbedded in mud1 and together with them1 at some points1 a species of reed1 ,arundo1 which was very common4 ,one of the most characteristic shrubs is a papilionaceous and leguminous plant of an extinct genus1 called by ,heer ,podogonium1 of which two species are known4 ,entire twigs have been found with flowers1 and always without leaves1 as the flowers evidently came out1 as in the poplar and willow tribe1 before any leaves made their appearance4 ,other specimens have been obtained with ripe fruits accompanied by leaves1 which resemble those of the tamarind1 to which it was evidently allied1 being of the family ,csalpine1 now proper to warmer regions4 ,fig4 #ach3 ,acer trilobatum4 ,the ,upper ,miocene flora of ningen is peculiarly important1 in consequence of the number of genera of which not merely the leaves1 but1 as in the case of the ,podogonium just mentioned1 the fruit also and even the flower are known4 ,thus there are nineteen species of maple1 ten of which have already been found with fruit4 ,although in no one region of the globe do so many maples now flourish1 we need not suspect ,professor ,heer of having made too many species in this genus when we consider the manner in which he has dealt with one of them1 ,acer trilobatum1 ,figs4 #aci and #adj4 ,of this plant the number of marked varieties figured and named is very great1 and no less than three of them had been considered as distinct species by other botanists1 while six of the others might have laid claim1 with nearly equal propriety1 to a like distinction4 ,the common form1 called ,acer trilobatum1 ,fig4 #aci1 may be taken as a normal representative of the ningen fossil1 and ,fig4 #adj1 as one of the most divergent varieties1 having almost four lobes in the leaf instead of three4 ,fig4 #adj3 ,acer trilobatum4 ,among the conspicuous genera which abounded in the ,miocene period in ,europe is the plane-tree1 ,platanus1 the fossil species being considered by ,heer to come nearer to the ,american ,p4 occidentalis than to ,p4 orientalis of ,greece and ,asia ,minor4 ,in some of the fossil specimens the male flowers are preserved4 ,among other points of resemblance with the living plane-trees1 as we see them in the parks and squares of ,london1 fossil fragments of the trunk are met with1 having pieces of their bark peeling off4 ,platanus aceroides4 ,the vine of ningen1 ,vitis teutonica1 ,ad4 ,brong1 is of a ,north ,american type4 ,both the leaves and seeds have been found at ningen1 and bunches of compressed grapes of the same species have been met with in the brown coal of ,wetteravia in ,germany4 ,no less than eight species of smilax1 a monocotyledonous genus1 occur at ningen and in other ,upper ,miocene localities1 the flowers of some of them1 as well as the leaves1 being preserved2 as in the case of the very common fossil1 ,s4 sagittifera1 ,fig4 #adb1 a4 ,leaves of plants supposed to belong to the order ,proteace have been obtained partly from ningen and partly from the lacustrine formation of the same age at ,locle in the ,jura4 ,they have been referred to the genera ,banksia1 ,grevillea1 ,hakea1 and ,persoonia4 ,of ,hakea there is the impression of a supposed seed-vessel1 with its characteristic thick stalk and seeds1 but as the fruit is without structure1 and has not yet been found attached to the same stem as the leaf1 the proof is incomplete4 ,fig4 #adb3 ,smilax sagittifera4 ,to whatever family the foliage hitherto regarded as proteaceous by many able palontologists may eventually be shown to belong1 we must be careful not to question their affinity to that order of plants on those geographical considerations which have influenced some botanists4 ,the nearest living ,proteace now feel the in ,abyssinia in lat4 #bj ,n41 but the greatest number are confined to the ,cape and ,australia4 ,the ancestors1 however1 of the ningen fossils ought not to be looked for in such distant regions1 but from that ,european land which in ,lower ,miocene times bore trees with similar foliage1 and these had doubtless an ,eocene source1 for cones admitted by all botanists to be proteaceous have been met with in one division of that older ,tertiary group 7see ,fig4 #bjf74 ,the source of these last1 again1 must not be sought in the antipodes1 for in the white chalk of ,aix-la-,chapelle leaves like those of ,grevillea and other proteaceous genera have been found in abundance1 and1 as we shall see 7p4 #cjd7 in a most perfect state of preservation4 ,all geologists agree that the distribution of the ,cretaceous land and sea had scarcely any connection with the present geography of the globe4 ,fig4 #adc3 ,fruit of the fossil and recent species of ,hakea1 a genus of ,proteace4 ,in the same beds with the supposed ,proteace there occurs at ,locle a fan-palm of the ,american type ,sabal 7for genus see ,fig4 #aea71 a genus which ranges throughout the low country near the sea from the ,carolinas to ,florida and ,louisiana4 ,among the ,conifer of ,upper ,miocene age is found a deciduous cypress nearly allied to the ,taxodium distichum of ,north ,america1 and a ,glyptostrobus 7,fig4 #add71 very like the ,japanese ,g4 heterophyllus1 now common in our shrubberies4 ,fig4 #add3 ,glyptostrobus ,europus4 ,before the appearance of ,heer's work on the ,miocene ,flora of ,switzerland1 ,unger and ,goppert had already pointed out the large proportion of living ,north ,american genera which distinguished the vegetation of the ,miocene period in ,central ,europe4 ,next in number1 says ,heer1 to these ,american forms at ningen the ,european genera preponderate1 the ,asiatic ranking in the third1 the ,african in the fourth1 and the ,australian in the fifth degree4 ,the ,american forms are more numerous than in the ,italian ,pliocene flora1 and the whole vegetation indicates a warmer climate than the ,pliocene1 though not so high a temperature as that of the older or ,lower ,miocene period4 ,the conclusions drawn from the insects are for the most part in perfect harmony with those derived from the plants1 but they have a somewhat less tropical and less ,american aspect1 the ,south ,european types being more numerous4 ,on the whole1 the insect fauna is richer than that now inhabiting any part of ,europe4 ,no less than #hdd species are reckoned by ,heer from the ningen beds alone1 the number of specimens which he has examined being #ejhj4 ,the entire list of ,swiss species from the ,upper and ,lower ,miocene together amount to #acbb4 ,almost all the living families of ,coleoptera are represented1 but1 as we might have anticipated from the preponderance of arborescent and ligneous plants1 the wood-eating beetles play the most conspicuous part1 the ,buprestid and other long-horned beetles being particularly abundant4 ,the patterns and some remains of the colours both of ,coleoptera and ,hemiptera are preserved at ningen1 as1 for example in ,harpactor 7,fig4 #ade71 in which the antenn1 one of the eyes1 and the legs and wings are retained4 ,the characters1 indeed1 of many of the insects are so well defined as to incline us to believe that if this class of the invertebrata were not so rare and local1 they might be more useful than even the plants and shells in settling chronological points in geology4 ,middle or ,marine ,molasse 7,upper ,miocene7 of ,switzerland4--,it was before stated that the ,miocene formation of ,switzerland consisted of1 first1 the upper fresh-water molasse1 comprising the lacustrine marls of ningen2 secondly1 the marine molasse1 corresponding in age to the faluns of ,touraine2 and thirdly1 the lower fresh-water molasse4 ,some of the beds of the marine or middle series reach a height of #bdgj feet above the sea4 ,a large number of the shells are common to the faluns of ,touraine1 the ,vienna basin1 and other ,upper ,miocene localities4 ,the terrestrial plants play a subordinate part in the fossiliferous beds1 yet more than ninety of them are enumerated by ,heer as belonging to this falunian division1 and of these more than half are common to subjacent ,lower ,miocene beds1 while a proportion of about forty-five in one hundred are common to the overlying ningen flora4 ,twenty-six of the ninety-two species are peculiar4 ,fig4 #ade3 ,harpactor maculipes4 ,fig4 #adf3 ,olica ,dufresnii4 ,upper ,miocene of the ,bolderberg1 in ,belgium4--,in a small hill or ridge called the ,bolderberg1 which ,i visited in #ahea1 situated near ,hasselt1 about forty miles ,e4,n4,e4 of ,brussels1 strata of sand and gravel occur1 to which ,m4 ,dumont first called attention as appearing to constitute a northern representative of the faluns of ,touraine4 ,on the whole1 they are very distinct in their fossils from the two upper divisions of the ,antwerp ,crag before mentioned 7p4 #bjd71 and contain shells of the genera ,oliva1 ,conus1 ,ancillaria1 ,pleurotoma1 and ,cancellaria in abundance4 ,the most common shell is an ,olive 7,fig4 #adf71 called by ,nyst ,oliva ,dufresnii2 and constituting1 as ,m4 ,bosquet observes1 a smaller and shorter variety of the ,bordeaux species4 ,so far as the shells of the ,bolderberg are known1 the proportion of recent species agrees with that in the faluns of ,touraine1 and the climate must have been warmer than that of the ,coralline ,crag of ,england4 ,upper ,miocene ,beds of the ,vienna ,basin4--,in ,south ,germany the general resemblance of the shells of the ,vienna tertiary basin with those of the faluns of ,touraine has long been acknowledged4 ,in the late ,dr4 ,hrnes's excellent work on the fossil mollusca of that formation1 we see accurate figures of many shells1 clearly of the same species as those found in the falunian sands of ,touraine4 ,according to ,professor ,suess1 the most ancient and purely marine of the ,miocene strata in this basin consist of sands1 conglomerates1 limestones1 and clays1 and they are inclined inward1 or from the borders of the trough towards the centre1 their outcropping edges rising much higher than the newer beds1 whether ,miocene or ,pliocene1 which overlie them1 and which occupy a smaller area at an inferior elevation above the sea4 ,m4 ,hornes has described no less than #ejj species of gasteropods1 of which he identifies one-fifth with living species of the ,mediterranean1 ,indian1 or ,african seas1 but the proportion of existing species among the lamellibranchiate bivalves exceeds this average4 ,among many univalves agreeing with those of ,africa on the eastern side of the ,atlantic are ,cypra sanguinolenta1 ,buccinum lyratum1 and ,oliva flammulata4 ,in the lowest marine beds of the ,vienna basin the remains of several mammalia have been found1 and among them a species of ,dinotherium1 a ,mastodon of the ,trilophodon family1 a ,rhinoceros 7allied to ,r4 megarhinus1 ,christol71 also an animal of the hog tribe1 ,listriodon1 von ,meyer1 and a carnivorous animal of the canine family4 ,the ,helix turonensis 7,fig4 #ch71 the most common land shell of the ,french faluns1 accompanies the above land animals4 ,in a higher member of the ,vienna ,miocene series are found ,dinotherium giganteum 7,fig4 #acf71 ,mastodon longirostris1 ,rhinoceros ,schleiermacheri1 ,acerotherium incisivum1 and ,hippotherium gracile1 all of them equally characteristic of an ,upper ,miocene deposit occurring at ,eppelsheim1 in ,hesse ,darmstadt2 a locality also remarkable as having furnished in latitude #di #ej ,n4 the bone of a large ape of the ,gibbon kind1 the most northerly example yet discovered of a quadrumanous animal4 ,fig4 #adg3 ,amphistegina ,hauerina4 ,m4 ,alcide d',orbigny has shown that the foraminifera of the ,vienna basin differ alike from the ,eocene and ,pliocene species1 and agree with those of the faluns1 so far as the latter are known4 ,among the ,vienna foraminifera1 the genus ,amphistegina 7,fig4 #adg7 is very characteristic1 and is supposed by d',archiac to take the same place among the ,rhizopods of the ,upper ,miocene era which the ,nummulites occupy in the ,eocene period4 ,the flora of the ,vienna basin exhibits some species which have a general range through the whole ,miocene period1 such as ,cinnamomum polymorphum 7,fig4 #ach71 and ,c4 ,scheuchzeri1 also ,planera ,richardi1 ,mich41 ,liquidambar europum 7,fig4 #ace7 ,juglans bilinica1 ,cassia ambigua1 and ,c4 lignitum4 ,among the plants common to the ,upper ,miocene beds of ningen1 in ,switzerland1 are ,platanus aceroides 7,fig4 #ada71 ,myrica vindobonensis1 and others4 ,upper ,miocene ,strata of ,italy4--,we are indebted to ,signor ,michelotti for a valuable work on the ,miocene shells of ,northern ,italy4 ,those found in the hill called the ,superga1 near ,turin1 have long been known to correspond in age with the faluns of ,touraine1 and they contain so many species common to the ,upper ,miocene strata of ,bordeaux as to lead to the conclusion that there was a free communication between the northern part of the ,mediterranean and the ,bay of ,biscay in the ,upper ,miocene period4 ,upper ,miocene ,formations of ,greece4--,at ,pikerm1 near ,athens1 ,,mm4 ,wagner and ,roth have described a deposit in which they found the remains of the genera ,mastodon1 ,dinotherium1 ,hipparion1 two species of ,giraffe1 ,antelope1 and others1 some living and some extinct4 ,with them were also associated fossil bones of the ,semnopithecus1 showing that here1 as in the south of ,france1 the quadrumana were characteristic of this period4 ,the whole fauna attests the former extension of a vast expanse of grassy plains where we have now the broken and mountainous country of ,greece2 plains1 which were probably united with ,asia ,minor1 spreading over the area where the deep gean ,sea and its numerous islands are now situated4 ,we are indebted to ,m4 ,gaudry1 who visited ,pikerm1 for a treatise on these fossil bones1 showing how many data they contribute to the theory of a transition from the mammalia of the ,upper ,miocene through the ,pliocene and ,post-pliocene forms to those of living genera and species4 ,upper ,miocene of ,india4 ,siwlik ,hills4--,the ,siwlik ,hills lie at the southern foot of the ,himalayan chain1 rising to the height of #bjjj and #cjjj feet4 ,between the ,jumna and the ,ganges they consist of inclined strata of sandstone1 shingle1 clay1 and marl4 ,we are indebted to the indefatigable researches of ,dr4 ,falconer and ,sir ,proby ,cautley1 continued for fifteen years1 for the discovery in these marls and sandstones of a great variety of fossil mammalia and reptiles1 together with many fresh-water shells4 ,out of fifteen species of shells of the genera ,paludina1 ,melania1 ,ampullaria1 and ,unio1 all are extinct or unknown species with the exception of four1 which are still inhabitants of ,indian rivers4 ,such a proportion of living to extinct mollusca agrees well with the usual character of an ,upper ,miocene or ,falunian fauna1 as observed in ,touraine1 or in the basin of ,vienna and elsewhere4 ,the genera of mammalia point in the same direction4 ,one of them1 of the genus ,chalicotherium 7or ,anisodon of ,lartet71 is a pachyderm intermediate between the ,rhinoceros and ,anoplothere1 and characteristic of the ,upper ,miocene strata of ,eppelsheim1 and of the south of ,france4 ,with it occurs also an extinct form of ,hippopotamus1 called ,hexaprotodon1 and a species of ,hippotherium and pig1 also two species of ,mastodon1 two of elephant1 and three other elephantine proboscidians2 none of them agreeing with any fossil forms of ,europe1 and being intermediate between the genera ,elephas and ,mastodon1 constituting the sub-genus ,stegodon of ,falconer4 ,with these are associated a monkey1 allied to the ,semnopithecus entellus1 now living in the ,himalaya1 and many ruminants4 ,among these last1 besides the giraffe1 camel1 antelope1 stag1 and others1 we find a remarkable new type1 the ,sivatherium1 like a gigantic four-horned deer4 ,there are also new forms of carnivora1 both feline and canine1 the ,machairodus among the former1 also hynas1 and a subursine form called the ,hynarctos1 and a genus allied to the otter 7,enhydriodon71 of formidable size4 ,the giraffe1 camel1 and a large ostrich may be cited as proofs that there were formerly extensive plains where now a steep chain of hills1 with deep ravines1 runs for many hundred miles east and west4 ,among the accompanying reptiles are several crocodiles1 some of huge dimensions1 and one not distinguishable1 says ,dr4 ,falconer1 from a species now living in the ,ganges 7,c4 ,gangeticus72 and there is still another saurian which the same anatomist has identified with a species now inhabiting ,india4 ,there was also an extinct species of tortoise of gigantic proportions 7,colossochelys ,atlas71 the curved shell of which was twelve feet three inches long and eight feet in diameter1 the entire length of the animal being estimated at eighteen feet1 and its probable height seven feet4 ,numerous fossils of the ,siwlik type have also been found in ,perim ,island1 in the ,gulf of ,cambay1 and among these a species of ,dinotherium1 a genus so characteristic of the ,upper ,miocene period in ,europe4 ,older ,pliocene and ,miocene ,formations in the ,united ,states4--,between the ,alleghany ,mountains1 formed of older rocks1 and the ,atlantic1 there intervenes1 in the ,united ,states1 a low region occupied principally by beds of marl1 clay1 and sand1 consisting of the cretaceous and tertiary formations1 and chiefly of the latter4 ,the general elevation of this plain bordering the ,atlantic does not exceed #ajj feet1 although it is sometimes several hundred feet high4 ,its width in the middle and southern states is very commonly from #ajj to #aej miles4 ,it consists1 in the ,south1 as in ,georgia1 ,alabama1 and ,south ,carolina1 almost exclusively of ,eocene deposits2 but in ,north ,carolina1 ,maryland1 ,virginia1 ,delaware1 more modern strata predominate1 of the age of the ,english ,crag and faluns of ,touraine4#a ,fig4 #adh3 ,fulgur canaliculatus4 ,fig4 #adi3 ,fusus quadricostatus4 ,in the ,virginian sands1 we find in great abundance a species of ,astarte 7,a4 undulata1 ,conrad71 which resembles closely1 and may possibly be a variety of1 one of the commonest fossils of the ,suffolk ,crag 7,a4 ,omalii72 the other shells also1 of the genera ,natica1 ,fissurella1 ,artemis1 ,lucina1 ,chama1 ,pectunculus1 and ,pecten1 are analagous to shells both of the ,english ,crag and ,french faluns1 although the species are almost all distinct4 ,out of #adg of these ,american fossils ,i could only find thirteen species common to ,europe1 and these occur partly in the ,suffolk ,crag1 and partly in the faluns of ,touraine2 but it is an important characteristic of the ,american group1 that it not only contains many peculiar extinct forms1 such as ,fusus quadricostatus1 ,say 7see ,fig4 #adi71 and ,venus tridacnoides1 abundant in these same formations1 but also some shells which1 like ,fulgur carica of ,say and ,f4 canaliculatus 7see ,fig4 #adh71 ,calyptra costata1 ,venus mercenaria1 ,lam41 ,modiola glandula1 ,totten1 and ,pecten magellanicus1 ,lam41 are recent species1 yet of forms now confined to the western side of the ,atlantic--a fact implying that some traces of the beginning of the present geographical distribution of mollusca date back to a period as remote as that of the ,miocene strata4 ,fig4 #aej3 ,astrangia lineata4 ,of ten species of corals which ,i procured on the banks of the ,james ,river1 one agrees generically with a coral now living on the coast of the ,united ,states4 ,mr4 ,lonsdale regarded these corals as indicating a temperature exceeding that of the ,mediterranean1 and the shells would lead to similar conclusions4 ,those occurring on the ,james ,river are in the #cgth degree of ,n4 latitude1 while the ,french faluns are in the #dgth2 yet the forms of the ,american fossils would scarcely imply so warm a climate as must have prevailed in ,france when the ,miocene strata of ,touraine originated4 ,among the remains of fish in these post-eocene strata of the ,united ,states are several large teeth of the shark family1 not distinguishable specifically from fossils of the faluns of ,touraine4 #a ,proceedings of the ,geol4 ,soc41 vol4 iv1 pt4 iii1 #ahde1 p4 #edg4 ,,chapter ,,xv4 ,,lower ,,miocene 7,,oligocene ,,of ,,beyrich74 ,lower ,miocene ,strata of ,france4 -- ,line between ,miocene and ,eocene4 -- ,lacustrine ,strata of ,auvergne4 -- ,fossil mammalia of the ,limagne d',auvergne4 -- ,lower ,molasse of ,switzerland4 -- ,dense ,conglomerates and ,proofs of ,subsidence4 -- ,flora of the ,lower ,molasse4 -- ,american ,character of the ,flora4 -- ,theory of a ,miocene ,atlantis4 -- ,lower ,miocene of ,belgium4 -- ,rupelian ,clay of ,hermsdorf near ,berlin4 -- ,mayence ,basin4 -- ,lower ,miocene of ,croatia4 -- ,oligocene ,strata of ,beyrich4 -- ,lower ,miocene of ,italy4 -- ,lower ,miocene of ,england4 -- ,hempstead ,beds4 -- ,bovey ,tracey ,lignites in ,devonshire4 -- ,isle of ,mull ,leaf-,beds4 -- ,arctic ,miocene ,flora4 -- ,disco ,island4 -- ,lower ,miocene of ,united ,states4 -- ,fossils of ,nebraska4 ,line between ,miocene and ,eocene ,formations4--,the marine faluns of the valley of the ,loire have been already described as resting in some places on a fresh-water tertiary limestone1 fragments of which have been broken off and rolled on the shores and in the bed of the ,miocene sea4 ,such pebbles are frequent at ,pontlevoy on the ,cher1 with hollows drilled in them in which the perforating marine shells of the ,falunian period still remain4 ,such a mode of superposition implies an interval of time between the origin of the fresh-water limestone and its submergence beneath the waters of the ,upper ,miocene sea4 ,the limestone in question forms a part of the formation called the ,calcaire de la ,beauce1 which constitutes a large table-land between the basins of the ,loire and the ,seine4 ,it is associated with marls and other deposits1 such as may have been formed in marshes and shallow lakes in the newest part of a great delta4 ,beds of flint1 continuous or in nodules1 accumulated in these lakes1 and aquatic plants called ,charae1 left their stems and seed-vessels imbedded both in the marl and flint1 together with fresh-water and land shells4 ,some of the siliceous rocks of this formation are used extensively for mill-stones4 ,the flat summits or platforms of the hills round ,paris1 and large areas in the forest of ,fontainebleau1 as well as the ,plateau de la ,beauce1 already alluded to1 are chiefly composed of these fresh-water strata4 ,next to these in the descending order are marine sands and sandstone1 commonly called the ,gres de ,fontainebleau1 from which a considerable number of shells1 very distinct from those of the faluns1 have been obtained at ,etampes1 south of ,paris1 and at ,montmartre and other hills in ,paris itself1 or in its suburbs4 ,at the bottom of these sands a green clay occurs1 containing a small oyster1 ,ostrea cyathula1 ,lam41 which1 although of slight thickness1 is spread over a wide area4 ,this clay rests immediately on the ,paris gypsum1 or that series of beds of gypsum and gypseous marl from which ,cuvier first obtained several species of ,palotherium and other extinct mammalia4#a ,at this junction of the clay and the gypsum the majority of ,french geologists have always drawn the line between the ,middle and ,lower ,tertiary1 or between the ,miocene and ,eocene formations1 regarding the ,fontainebleau sands and the ,ostrea cyathula clay as the base of the ,miocene1 and the gypsum1 with its mammalia1 as the top of the ,eocene group4 ,i formerly dissented from this division1 but ,i now find that ,i must admit it to be the only one which will agree with the distribution of the ,miocene mammalia1 while even the mollusca of the ,fontainebleau sands1 which were formerly supposed to present at preponderance of affinities to an ,eocene fauna1 have since been shown to agree more closely with the fossils of certain deposits always regarded as ,middle ,tertiary at ,mayence and in ,belgium4 ,in fact1 we are now arriving at that stage of progress when the line1 wherever it be drawn between ,miocene and ,eocene1 will be an arbitrary one1 or one of mere convenience1 as ,i shall have an opportunity of showing when the ,upper ,eocene formations in the ,isle of ,wight are described in the sixteenth chapter4 ,lower ,miocene of ,central ,france4--,lacustrine strata1 belonging1 for the most part1 to the same ,miocene system as the ,calcaire de la ,beauce1 are again met with farther south in ,auvergne1 ,cantal1 and ,vlay4 ,they appear to be the monuments of ancient lakes1 which1 like some of those now existing in ,switzerland1 once occupied the depressions in a mountainous region1 and have been each fed by one or more rivers and torrents4 ,the country where they occur is almost entirely composed of granite and different varieties of granitic schist1 with here and there a few patches of ,secondary strata1 much dislocated1 and which have suffered great denudation4 ,there are also some vast piles of volcanic matter1 the greater part of which is newer than the fresh-water strata1 and is sometimes seen to rest upon them1 while a small part has evidently been of contemporaneous origin4 ,of these igneous rocks ,i shall treat more particularly in the sequel4 ,the study of these regions possesses a peculiar interest very distinct in kind from that derivable from the investigation either of the ,parisian or ,english ,tertiary areas4 ,for we are presented in ,auvergne with the evidence of a series of events of astonishing magnitude and grandeur1 by which the original form and features of the country have been greatly changed1 yet never so far obliterated but that they may still1 in part at least1 be restored in imagination4 ,great lakes have disappeared--lofty mountains have been formed1 by the reiterated emission of lava1 preceded and followed by showers of sand and scori--deep valleys have been subsequently furrowed out through masses of lacustrine and volcanic origin--at a still later date1 new cones have been thrown up in these valleys--new lakes have been formed by the damming up of rivers--and more than one assemblage of quadrupeds1 birds1 and plants1 ,eocene1 ,miocene1 and ,pliocene1 have followed in succession2 yet the region has preserved from first to last its geographical identity2 and we can still recall to our thoughts its external condition and physical structure before these wonderful vicissitudes began1 or while a part only of the whole had been completed4 ,there was first a period when the spacious lakes1 of which we still may trace the boundaries1 lay at the foot of mountains of moderate elevation1 unbroken by the bold peaks and precipices of ,mont ,dor1 and unadorned by the picturesque outline of the ,puy de ,dome1 or of the volcanic cones and craters now covering the granitic platform4 ,during this earlier scene of repose deltas were slowly formed2 beds of marl and sand1 several hundred feet thick1 deposited2 siliceous and calcareous rocks precipitated from the waters of mineral springs2 shells and insects imbedded1 together with the remains of the crocodile and tortoise1 the eggs and bones of water-birds1 and the skeletons of quadrupeds1 most of them of genera and species characteristic of the ,miocene period4 ,to this tranquil condition of the surface succeeded the era of volcanic eruptions1 when the lakes were drained1 and when the fertility of the mountainous district was probably enhanced by the igneous matter ejected from below1 and poured down upon the more sterile granite4 ,during these eruptions1 which appear to have taken place towards the close of the ,miocene epoch1 and which continued during the ,pliocene1 various assemblages of quadrupeds successively inhabited the district1 among which are found the genera mastodon1 rhinoceros1 elephant1 tapir1 hippopotamus1 together with the ox1 various kinds of deer1 the bear1 hyna1 and many beasts of prey which ranged the forest or pastured on the plain1 and were occasionally overtaken by a fall of burning cinders1 or buried in flows of mud1 such as accompany volcanic eruptions4 ,lastly1 these quadrupeds became extinct1 and gave place in their turn to the species now existing4 ,there are no signs1 during the whole time required for this series of events1 of the sea having intervened1 nor of any denudation which may not have been accomplished by currents in the different lakes1 or by rivers and floods accompanying repeated earthquakes1 or subterranean movements1 during which the levels of the district have in some places been materially modified1 and perhaps the whole upraised relatively to the surrounding parts of ,france4 ,auvergne4--,the most northern of the fresh-water groups is situated in the valley-plain of the ,allier1 which lies within the department of the ,puy de ,dome1 being the tract which went formerly by the name of the ,limagne d',auvergne4 ,the average breadth of this tract is about twenty miles2 and it is for the most part composed of nearly horizontal strata of sand1 sandstone1 calcareous marl1 clay1 and limestone1 none of which observe a fixed and invariable order of superposition4 ,the ancient borders of the lake wherein the fresh-water strata were accumulated may generally be traced with precision1 the granite and other ancient rocks rising up boldly from the level country4 ,the actual junction1 however1 of the lacustrine beds and the granite is rarely seen1 as a small valley usually intervenes between them4 ,the fresh-water strata may sometimes be seen to retain their horizontality within a very slight distance of the border-rocks1 while in some places they are inclined1 and in few instances vertical4 ,the principal divisions into which the lacustrine series may be separated are the following3--first1 ,sandstone1 grit1 and conglomerate1 including red marl and red sandstone2 secondly1 ,green and white foliated marls2 thirdly1 ,limestone1 or travertin1 often oolitic in structure2 fourthly1 ,gypseous marls4 ,the relations of these different groups cannot be learnt by the study of any one section2 and the geologist who sets out with the expectation of finding a fixed order of succession may perhaps complain that the different parts of the basin give contradictory results4 ,the arenaceous division1 the marls1 and the limestone may all be seen in some places to alternate with each other2 yet it can by no means be affirmed that there is no order of arrangement4 ,the sands1 sandstone1 and conglomerate constitute in general a littoral group2 the foliated white and green marl1 a contemporaneous central deposit more than #gjj feet thick1 and thinly foliated1 a character which often arises from the innumerable thin shells or carapace valves shed by the small crustacean called ,cypris in the ancient lakes of ,auvergne2 and lastly the limestone is for the most part subordinate to the newer portions of both the above formations4 ,it seems that1 when the ancient lake of the ,limagne first began to be filled with sediment1 no volcanic action had yet produced lava and scori on any part of the surface of ,auvergne4 ,no pebbles1 therefore1 of lava were transported into the lake--no fragments of volcanic rocks imbedded in the conglomerate4 ,but at a later period1 when a considerable thickness of sandstone and marl had accumulated1 eruptions broke out1 and lava and tuff were deposited1 at some spots1 alternately with the lacustrine strata4 ,it is not improbable that cold and thermal springs1 holding different mineral ingredients in solution1 became more numerous during the successive convulsions attending this development of volcanic agency1 and thus deposits of carbonate and sulphate of lime1 silex1 and other minerals were produced4 ,hence these minerals predominate in the uppermost strata4 ,the subterranean movements may then have continued until they altered the relative levels of the country1 and caused the waters of the lakes to be drained off1 and the further accumulation of regular fresh-water strata to cease4 ,lower ,miocene ,mammalia of the ,limagne4--,it is scarcely possible to determine the age of the oldest part of the fresh-water series of the ,limagne1 large masses both of the sandy and marly strata being devoid of fossils4 ,some of the lowest beds may be of ,upper ,eocene date1 although1 according to ,m4 ,pomel1 only one bone of a ,palotherium has been discovered in ,auvergne4 ,but in ,vlay1 in strata containing some species of fossil mammalia common to the ,limagne1 no less than four species of ,palothere have been found by ,m4 ,aymard1 and one of these is generally supposed to be identical with ,palotherium magnum1 an undoubted ,upper ,eocene fossil1 of the ,paris gypsum1 the other three being peculiar4 ,not a few of the other mammalia of the ,limagne belong undoubtedly to genera and species elsewhere proper to the ,lower ,miocene4 ,thus1 for example1 the ,cainotherium of ,bravard1 a genus not far removed from the ,anoplotherium1 is represented by several species1 one of which1 as ,i learn from ,mr4 ,waterhouse1 agrees with ,microtherium ,renggeri of the ,mayence basin4 ,in like manner1 the ,amphitragulus elegans of ,pomel1 an ,auvergne fossil1 is identified by ,waterhouse with ,dorcatherium nanum of ,kaup1 a ,rhenish species from ,weissenau1 near ,mayence4 ,a small species1 also1 of rodent1 of the genus ,titanomys of ,h4 von ,meyer1 is common to the ,lower ,miocene of ,mayence and the ,limagne d',auvergne1 and there are many other points of agreement which the discordance of nomenclature tends to conceal4 ,a remarkable carnivorous genus1 the ,hynodon of ,laizer1 is represented by more than one species4 ,the same genus has also been found in the ,upper ,eocene marls of ,hordwell ,cliff1 ,hampshire1 just below the level of the ,bembridge ,limestone1 and therefore a formation older than the ,gypsum of ,paris4 ,several species of opossum 7,didelphis7 are met with in the same strata of the ,limagne4 ,the total number of mammalia enumerated by ,m4 ,pomel as appertaining to the ,lower ,miocene fauna of the ,limagne and ,velay falls little short of a hundred1 and with them are associated some large crocodiles and tortoises1 and some ,ophidian and ,batrachian reptiles4 ,lower ,molasse of ,switzerland4--,the two upper divisions of the ,swiss ,molasse--the one fresh-water1 the other marine--have already been described in the preceding chapter4 ,i shall now proceed to treat of the third division1 which is of ,lower ,miocene age4 ,nearly the whole of this ,lower ,molasse is fresh-water1 yet some of the inferior beds contain a mixture of marine and fluviatile shells1 the ,cerithium margaritaceum1 a well-known ,lower ,miocene fossil1 being one of the marine species4 ,notwithstanding1 therefore1 that some of these ,lower ,miocene strata consist of old shingle-beds several thousand feet in thickness1 as in the ,rigi1 near ,lucerne1 and in the ,speer1 near ,wesen1 mountains #ejjj and #gjjj feet above the sea1 the deposition of the whole series must have begun at or below the sea-level4 ,the conglomerates1 as might be expected1 are often very unequal in thickness1 in closely adjoining districts1 since in a littoral formation accumulations of pebbles would swell out in certain places where rivers entered the sea1 and would thin out to comparatively small dimensions where no streams or only small ones came down to the coast4 ,for ages1 in spite of a gradual depression of the land and adjacent sea-bottom1 the rivers continued to cover the sinking area with their deltas2 until finally1 the subsidence being in excess1 the sea of the ,middle ,molasse gained upon the land1 and marine beds were thrown down over the dense mass of fresh-water and brackish-water deposit1 called the ,lower ,molasse1 which had previously accumulated4 ,flora of the ,lower ,molasse4--,in part of the ,swiss ,molasse1 which belongs exclusively to the ,lower ,miocene period1 the number of plants has been estimated at more than #ejj species1 somewhat exceeding those which were before enumerated as occurring in the two upper divisions4 ,the ,swiss ,lower ,miocene may best be studied on the northern borders of the ,lake of ,geneva1 between ,lausanne and ,vevay1 where the contiguous villages of ,monod and ,rivaz are situated4 ,the strata there1 which ,i have myself examined1 consist of alternations of conglomerate1 sandstone1 and finely laminated marls with fossil plants4 ,a small stream falls in a succession of cascades over the harder beds of pudding-stone1 which resist1 while the sandstone and plant-bearing shales and marls give way4 ,from the latter no less than #aic species of plants have been obtained by the exertions of ,,mm4 ,heer and ,gaudin1 and they are considered to afford a true type of the vegetation of the ,lower ,miocene formations of ,switzerland--a vegetation departing farther in its character from that now flourishing in ,europe than any of the higher members of the series before alluded to1 and yet displaying so much affinity to the flora of ningen as to make it natural for the botanist to refer the whole to one and the same ,miocene period4 ,there are1 indeed1 no less than #ha species of these ,older ,miocene plants which pass up into the flora of ningen4 ,this fact is important as bearing on the propriety of classing the ,lower ,molasse of ,switzerland as belonging to the ,miocene rather than to the latter part of the ,eocene period4 ,there are1 indeed1 so many types among the fossils1 both specific and generic1 which have a wide range through the whole of the ,molasse1 that a unity of character is thereby stamped on the whole flora1 in spite of the contrast between the plants of the uppermost and lowest formations1 or between ,oeningen and ,monod4 ,the proofs of a warmer climate1 and the excess of arborescent over herbaceous plants1 and of evergreen trees over deciduous species1 are characters common to the whole flora1 but which are intensified as we descend to the inferior deposits4 ,nearly all the plants at ,monod are contained in three layers of marl separated by two of soft sandstone4 ,the thickness of the marls is ten feet1 and vegetable matter predominates so much in some layers as to form an imperfect lignite4 ,one bed is filled with large leaves of a species of fig 7,ficus populina71 and of a hornbeam 7,carpinus grandis71 the strength of the wind having probably been great when they were blown into the lake2 whereas another contiguous layer contains almost exclusively smaller leaves1 indicating1 apparently1 a diminished strength in the wind4 ,some of the upper beds at ,monod abound in leaves of ,proteace1 ,cyperace1 and ferns1 while in some of the lower ones ,sequoia1 ,cinnamomum1 and ,sparganium are common4 ,in one bed of sandstone the trunk of a large palm-tree was found unaccompanied by other fossils1 and near ,vevay1 in the same series of ,lower ,miocene strata1 the leaves of a palm of the genus ,sabal 7,fig4 #aea71 a genus now proper to ,america1 were obtained4 ,fig4 #aea3 ,sabal major ,among other genera of the same class is a ,flabellaria occurring near ,lausanne1 and a magnificent ,phnicites allied to the date palm4 ,when these plants flourished the climate must have been much hotter than now4 ,the ,alps were no doubt much lower1 and the palms now found fossil in strata elevated #bjjj feet above the sea grew nearly at the sea-level1 as is demonstrated by the brackish-water character of some of the beds into which they were carried by winds or rivers from the adjoining coast4 ,in the same plant-bearing deposits of the ,lower ,molasse in ,switzerland leaves have been found which have been ascribed to the order ,proteace already spoken of as well represented in the ningen beds 7see p4 #bba74 ,the ,proteas and other plants of this family now flourish at the ,cape of ,good ,hope2 while the ,banksias1 and a set of genera distinct from those of ,africa1 grow most luxuriantly in the southern and temperate parts of ,australia4 ,they were probably inhabitants1 says ,heer1 of dry hilly ground1 and the stiff leathery character of their leaves must have been favourable to their preservation1 allowing them to float on a river for great distances without being injured1 and then to sink1 when water-logged1 to the bottom4 ,it has been objected that the fruit of the ,proteace is of so tough and enduring a texture that it ought to have been more commonly met with2 but in the first place we must not forget the numerous cones found in the ,eocene strata of ,sheppey1 which all admit to be proteaceous and to belong to at least two species 7see p4 #bbb74 ,secondly1 besides the fruit of ,hakea before mentioned 7p4 #bba71 ,heer found associated with fossil leaves1 having the exact form and nervation of ,banksia1 fruit precisely such as may have come from a cone of that plant1 and lately he has received another similar fruit from the ,lower ,miocene strata of ,lucerne4 ,they may have fallen out of a decayed cone in the same way as often happens to the seeds of the spruce fir1 ,pinus abies1 found scattered over the ground in our woods4 ,it is a known fact that among the living ,proteace the cones are very firmly attached to the branches1 so that the seeds drop out without the cone itself falling to the ground1 and this may perhaps be the reason why1 in some instances in which fossil seeds have been found1 no traces of the cone have been observed4 ,fig4 #aeb3 ,fruit of fossil ,banksia and leaf of ,banksia4 ,fig4 #aec3 ,sequoia ,langsdorfii4 ,among the ,conifer the ,sequoia here figured is common at ,rivaz1 and is one of the most universal plants in the ,lowest ,miocene of ,switzerland1 while it also characterises the ,miocene ,brown ,coals of ,germany and certain beds of the ,val d',arno1 which ,i have called ,older ,pliocene1 p4 #bjh4 ,fig4 #aed3 ,lastra stiriaca4 ,among the ferns met with in profusion at ,monod is the ,lastra stiriaca1 ,unger1 which has a wide range in the ,miocene period from strata of the age of ningen to the lowest part of the ,swiss ,molasse4 ,in some specimens1 as shown in ,fig4 #aed1 the fructification is distinctly seen4 ,among the laurels several species of ,cinnamomum are very conspicuous4 ,besides the ,c4 polymorphum1 before figured1 p4 #bai1 another species also ranges from the ,lower to the ,upper ,molasse of ,switzerland1 and is very characteristic of different deposits of ,brown ,coal in ,germany4 ,it has been called ,cinnamomum ,rossmssleri by ,heer 7see ,fig4 #aee74 ,the leaves are easily recognised as having two side veins1 which run up uninterruptedly to their point4 ,fig4 #aee3 ,cinnamomum ,rossmssleri4 ,american ,character of the ,flora4--,if we consider not merely the number of species but those plants which constitute the mass of the ,lower ,miocene vegetation1 we find the ,european part of the fossil flora very much less prominent than in the ningen beds1 while the foreground is occupied by ,american forms1 by evergreen oaks1 maples1 poplars1 planes1 ,liquidambar1 ,robinia1 ,sequoia1 ,taxodium1 and ternate-leaved pines4 ,there is also a much greater fusion of the characters now belonging to distinct botanical provinces than in the ,upper ,miocene flora1 and we shall find this fusion still more strikingly exemplified as we go back to the antecedent ,eocene and ,cretaceous periods4 ,professor ,heer has advocated the doctrine1 first advanced by ,unger to explain the large number of ,american genera in the ,miocene flora of ,europe1 that the present basin of the ,atlantic was occupied by land over which the ,miocene flora could pass freely4 ,but other able botanists have shown that it is far more probable that the ,american plants came from the east and not from the west1 and instead of reaching ,europe by the shortest route over an imaginary ,atlantis1 migrated in an opposite direction1 crossing the whole of ,asia4 ,arctic ,miocene ,flora4--,but when we indulge in speculations as to the geographical origin of the ,miocene plants of ,central ,europe1 we must take into account the discoveries recently made of a rich terrestrial flora having flourished in the ,arctic ,regions in the ,miocene period from which many species may have migrated from a common centre so as to reach the present continents of ,europe1 ,asia1 and ,america4 ,professor ,heer has examined the various collections of fossil plants that have been obtained in ,north ,greenland 7lat4 #gj71 ,iceland1 ,spitzbergen1 and other parts of the ,arctic regions1 and has determined that they are of ,miocene age and indicate a temperate climate4#b ,including the collections recently brought from ,greenland by ,mr4 ,whymper1 the ,arctic ,miocene flora now comprises #aid species1 and that of ,greenland #acg species1 of which #df1 or exactly one-third1 are identical with plants found in the ,miocene beds of ,central ,europe4 ,considerably more than half the number are trees1 which is the more remarkable since1 at the present day1 trees do not exist in any part of ,greenland even #aj degrees farther south4 ,more than thirty species of ,conifer have been found1 including several ,sequoias 7allied to the gigantic ,wellingtonia of ,california71 with species of ,thujopsis and ,salisburia now peculiar to ,japan4 ,there are also beeches1 oaks1 planes1 poplars1 maples1 walnuts1 limes1 and even a magnolia1 two cones of which have recently been obtained1 proving that this splendid evergreen not only lived but ripened its fruit within the ,arctic circle4 ,many of the limes1 planes1 and oaks were large-leaved species1 and both flowers and fruit1 besides immense quantities of leaves1 are in many cases preserved4 ,among the shrubs were many evergreens1 as ,andromeda1 and two extinct genera1 ,daphnogene and ,m',clintockia1 with fine leathery leaves1 together with hazel1 blackthorn1 holly1 logwood1 and hawthorn4 ,a species of ,zamia 7,zamites7 grew in the swamps1 with ,potamogeton1 ,sparganium1 and ,menyanthes1 while ivy and vines twined around the forest trees and broad-leaved ferns grew beneath their shade4 ,even in ,spitzbergen1 as far north as latitude #gh #ef1 no less than ninety-five species of fossil plants have been obtained1 including ,taxodium of two species1 hazel1 poplar1 alder1 beech1 plane-tree1 and lime4 ,such a vigorous growth of trees within #ab degrees of the pole1 where now a dwarf willow and a few herbaceous plants form the only vegetation1 and where the ground is covered with almost perpetual snow and ice1 is truly remarkable4 ,the identity of so many of the fossils with ,miocene species of ,central ,europe and ,italy not only proves that the climate of ,greenland was much warmer than it is now1 but also renders it probable that a much more uniform climate prevailed over the entire northern hemisphere4 ,this is also indicated by the whole character of the ,upper ,miocene flora of ,central ,europe1 which does not necessitate a mean temperature very much greater than exists at present1 if we suppose such absence of winter cold as is proper to insular climates4 ,professor ,heer believes that the mean temperature of ,north ,greenland must have been at least #cj degrees higher than at present1 while an addition of #aj degrees to the mean temperature of ,central ,europe would probably be as much as was required4 ,the chief locality where this wonderful flora is preserved is at ,atanekerdluk in ,north ,greenland 7lat4 #gj71 on a hill at an elevation of about #abjj feet above the sea4 ,there is here a considerable succession of sedimentary strata pierced by volcanic rocks4 ,fossil plants occur in all the beds1 and the erect trunks as thick as a man's body which are sometimes found1 together with the abundance of specimens of flowers and fruit in good preservation1 sufficiently prove that the plants grew where they are now found4 ,at ,disco island and other localities on the same part of the coast1 good coal is abundant1 interstratified with beds of sandstone1 in some of which fossil plants have also been found1 similar to those at ,atanekerdluk4 ,fig4 #aef3 ,leda 7,nucula7 ,deshayesiana4 ,lower ,miocene1 ,belgium4--,the ,upper ,miocene ,bolderberg beds1 mentioned in p4 #bbd1 rest on a ,lower ,miocene formation called the ,rupelian of ,dumont4 ,this formation is best seen at the villages of ,rupelmonde and ,boom1 ten miles south of ,antwerp1 on the banks of the ,scheldt and near the junction with it of a small stream called the ,rupel4 ,a stiff clay abounding in fossils is extensively worked at the above localities for making tiles4 ,it attains a thickness of about #ajj feet1 and though very different in age1 much resembles in mineral character the 8,london clay10 containing1 like it1 septaria or concretions of argillaceous limestone traversed by cracks in the interior1 which are filled with calc-spar4 ,the shells1 referable to about forty species1 have been described by ,,mm4 ,nyst and ,de ,koninck4 ,among them ,leda 7or ,nucula7 ,deshayesiana 7see ,fig4 #aef7 is by far the most abundant2 a fossil unknown as yet in the ,english tertiary strata1 but when young much resembling ,leda amygdaloides of the ,london ,clay proper 7see ,fig4 #bac74 ,among other characteristic shells are ,pecten ,hninghausii1 and a species of ,cassidaria1 and several of the genus ,pleurotoma4 ,not a few of these testacea agree with ,english ,eocene species1 such as ,acton simulatus1 ,sowb1 ,cancellaria evulsa1 ,brander1 ,corbula pisum 7,fig4 #aeg71 and ,nautilus 7,aturia7 ziczac4 ,they are accompanied by many teeth of sharks1 as ,lamna contortidens1 ,ag41 ,oxyrhinaxiphodon1 ,ag41 ,carcharodon angustidens 7see ,fig4 #aif71 ,ag41 and other fish1 some of them common to the ,middle ,eocene strata4 ,kleyn ,spawen beds4--,the succession of the ,lower ,miocene strata of ,belgium can be best studied in the environs of ,kleyn ,spawen1 a village situated about seven miles west of ,maestricht1 in the old province of ,limburg in ,belgium4 ,in that region1 about #bjj species of testacea1 marine and fresh-water1 have been obtained1 with many foraminifera and remains of fish4 ,in none of the ,belgian ,lower ,miocene strata could ,i find any nummulites2 and ,m4 d',archiac had previously observed that these foraminifera characterise his 8,lower ,tertiary ,series10 as contrasted with the ,middle1 and they therefore serve as a good test of age between ,eocene and ,miocene1 at least in ,belgium and the ,north of ,france4#c ,between the ,bolderberg beds and the ,rupelian clay there is a great gap in ,belgium1 which seems1 according to ,m4 ,beyrich1 to be filled up in the ,north of ,germany by what he calls the ,sternberg beds1 and which1 had ,dumont found them in ,belgium1 he might probably have termed ,upper ,rupelian4 ,lower ,miocene of ,germany4--,rupelian ,clay of ,hermsdorf1 near ,berlin4--,professor ,beyrich has described a mass of clay1 used for making tiles1 within seven miles of the gates of ,berlin1 near the village of ,hermsdorf1 rising up from beneath the sands with which that country is chiefly overspread4 ,this clay is more than forty feet thick1 of a dark bluish-grey colour1 and1 like that of ,rupelmonde1 contains septaria4 ,among other shells1 the ,leda ,deshayesiana1 before mentioned 7,fig4 #aef71 abounds1 together with many species of ,pleurotoma1 ,voluta1 etc41 a certain proportion of the fossils being identical in species with those of ,rupelmonde4 ,mayence ,basin4--,an elaborate description has been published by ,dr4 ,f4 ,sandberger of the ,mayence tertiary area1 which occupies a tract from five to twelve miles in breadth1 extending for a great distance along the left bank of the ,rhine from ,mayence to the neighbourhood of ,manheim1 and which is also found to the east1 north1 and south-west of ,frankfort4 ,m4 ,de ,koninck1 of ,liege1 first pointed out to me that the purely marine portion of the deposit contained many species of shells common to the ,kleyn ,spawen beds1 and to the clay of ,rupelmonde1 near ,antwerp4 ,among these he mentioned ,cassidaria depressa1 ,tritonium argutum1 ,brander 7,t4 flandricum1 ,de ,koninck71 ,tornatella simulata1 ,aporrhais ,sowbyi1 ,leda ,deshayesiana 7,fig4 #aef71 ,corbula pisum1 7,fig4 #aeh7 and others4 ,lower ,miocene ,beds of ,croatia4--,the ,brown ,coal of ,radaboj1 near ,angram in ,croatia1 not far from the borders of ,styria1 is covered1 says ,von ,buch1 by beds containing the marine shells of the ,vienna basin1 or1 in other words1 by ,upper ,miocene or ,falunian strata4 ,they appear to correspond in age to the ,mayence basin1 or to the ,rupelian strata of ,belgium4 ,they have yielded more than #bjj species of fossil plants1 described by the late ,professor ,unger4 ,these plants are well preserved in a hard marlstone1 and contain several palms2 among them the ,sabal1 ,fig4 #aea1 p4 #bcg1 and another genus allied to the date-palm ,phnicites spectabilis4 ,the only abundant plant among the ,radaboj fossils which is characteristic of the ,upper ,miocene period is the ,populus mutabilis1 whereas no less than fifty of the ,radaboj species are common to the more ancient flora of the ,lower ,molasse of ,switzerland4 ,fig4 #aeg3 ,vanessa ,pluto4 ,the insect fauna is very rich1 and1 like the plants1 indicates a more tropical climate than do the fossils of ningen presently to be mentioned4 ,there are ten species of ,termites1 or white ants1 some of gigantic size1 and large dragon-flies with speckled wings1 like those of the ,southern ,states in ,north ,america2 there are also grasshoppers of considerable size1 and even the ,lepidoptera are not unrepresented4 ,in one instance1 the pattern of a butterfly's wing has escaped obliteration in the marl-stone of ,radaboj2 and when we reflect on the remoteness of the time from which it has been faithfully transmitted to us1 this fact may inspire the reader with some confidence as to the reliable nature of the characters which other insects of a more durable texture1 such as the beetles1 may afford for specific determination4 ,the ,vanessa above figured retains1 says ,heer1 some of its colours1 and corresponds with ,v4 ,hadena of ,india4 ,professor ,beyrich has made known to us the existence of a long succession of marine strata in ,north ,germany1 which lead by an almost gradual transition from beds of ,upper ,miocene age to others of the age of the base of the ,lower ,miocene4 ,although some of the ,german lignites called ,brown ,coal belong to the upper parts of this series1 the most important of them are of ,lower ,miocene date1 as1 for example1 those of the ,siebengebirge1 near ,bonn1 which are associated with volcanic rocks4 ,professor ,beyrich confines the term 8,miocene0 to those strata which agree in age with the faluns of ,touraine1 and he has proposed the term 8,oligocene0 for those older formations called ,lower ,miocene in this work4 ,lower ,miocene of ,italy4--,in the hills of which the ,superga forms a part there is a great series of ,tertiary strata which pass downward into the ,lower ,miocene4 ,even in the ,superga itself there are some fossil plants which1 according to ,heer1 have never been found in ,switzerland so high as the marine ,molasse1 such as ,banksia longifolia1 and ,carpinus grandis4 ,in several parts of the ,ligurian ,apennines1 as at ,dgo and ,carcare1 the ,lower ,miocene appears1 containing some nummulites1 and at ,cadibona1 north of ,savona1 fresh-water strata of the same age occur1 with dense beds of lignite inclosing remains of the ,anthracotherium magnum and ,a4 minimum1 besides other mammalia enumerated by ,gastaldi4 ,in these beds a great number of the ,lower ,miocene plants of ,switzerland have been discovered4 ,lower ,miocene of ,england--,hempstead ,beds4--,we have already stated that the ,upper ,miocene formation is nowhere represented in the ,british ,isles2 but strata referable to the ,lower ,miocene period are found both in ,england1 ,scotland1 and ,ireland4 ,in the ,hampshire basin these occupy a very small superficial area1 having been discovered by the late ,edward ,forbes at ,hempstead near ,yarmouth1 in the northern part of the ,isle of ,wight1 where they are #agj feet thick1 and rich in characteristic marine shells4 ,they overlie the uppermost of an extensive series of ,eocene deposits of marine1 brackish1 and fresh-water formations1 which rest on the ,chalk and terminate upward in strata corresponding in age to the ,paris gypsum1 and containing the same extinct genera of quadrupeds1 ,palotherium1 ,anoplotherium1 and others which ,cuvier first described4 ,the following is the succession of these ,lower ,miocene strata1 most of them exposed in a cliff east of ,yarmouth3 #a4 ,the uppermost or ,corbula beds1 consisting of marine sands and clays1 contain ,voluta ,rathieri1 a characteristic ,lower ,miocene shell2 ,corbula pisum 7,fig4 #aeh71 a species common to the ,upper ,eocene clay of ,barton2 ,cyrena semistriata 7,fig4 #aei71 several ,cerithia1 and other shells peculiar to this series4 ,fig4 #aeh3 ,corbula pisum4 ,fig4 #aei3 ,cyrena semistriata4 ,fig4 #afj3 ,cerithium plicatum4 ,fig4 #afa3 ,cerithium elegans4 ,fig4 #afb3 ,rissoa ,chastelii4 ,fig4 #afc3 ,paludina lenta4 #b4 ,next are fresh-water and estuary marls and carbonaceous clays in the brackish-water portion of which are found abundantly ,cerithium plicatum1 ,lam4 7,fig4 #afj71 ,cerithium elegans 7,fig4 #afa71 and ,cerithium tricinctum2 also ,rissoa ,chastelii 7,fig4 #afb71 a very common ,kleyn ,spawen shell1 and which occurs in each of the four subdivisions of the ,hempstead series down to its base1 where it passes into the ,bembridge beds4 ,in the fresh-water portion of the same beds ,paludina lenta 7,fig4 #afc7 occurs2 a shell identified by some conchologists with a species now living1 ,p4 unicolor2 also several species of ,lymneus1 ,planorbis1 and ,unio4 #c4 ,the next series1 or middle fresh-water and estuary marls1 are distinguished by the presence of ,melania fasciata1 ,paludina lenta1 and clays with ,cypris2 the lowest bed contains ,cyrena semistriata 7,fig4 #aei71 mingled with ,cerithia and a panopa4 #d4 ,the lower fresh-water and estuary marls contain ,melania costata1 ,sowerby1 ,melanopsis1 etc4 ,the bottom bed is carbonaceous1 and called the 8,black band10 in which ,rissoa ,chastelii 7,fig4 #afb71 before alluded to1 is common4 ,this bed contains a mixture of ,hempstead shells with those of the underlying ,upper ,eocene or ,bembridge series4 ,the mammalia1 among which is ,hyopotamus bovinus1 differ1 so far as they are known1 from those of the ,bembridge beds4 ,among the plants1 ,professor ,heer has recognised four species common to the lignite of ,bovey ,tracey1 a ,lower ,miocene formation presently to be described3 namely1 ,sequoia ,couttsi1 ,heer2 ,andromeda reticulata1 ,ettings42 ,nelumbium 7,nympha7 doris1 ,heer2 and ,carpolithes ,websteri1 ,brong4#d ,the seed-vessels of ,chara medicaginula1 ,brong1 and ,c4 helicteres are characteristic of the ,hempstead beds generally4 ,the ,hyopotamus belongs to the hog tribe1 or the same family as the ,anthracotherium1 of which seven species1 varying in size from the hippopotamus to the wild boar1 have been found in ,italy and other part of ,europe associated with the lignites of the ,lower ,miocene period4 ,lignites and ,clays of ,bovey ,tracey1 ,devonshire4--,surrounded by the granite and other rocks of the ,dartmoor hills in ,devonshire1 is a formation of clay1 sand1 and lignite1 long known to geologists as the ,bovey ,coal formation1 respecting the age of which1 until the year #ahfa1 opinions were very unsettled4 ,this deposit is situated at ,bovey ,tracey1 a village distant eleven miles from ,exeter in a south-west1 and about as far from ,torquay in a north-west direction4 ,the strata extend over a plain nine miles long1 and they consist of the materials of decomposed and worn-down granite and vegetable matter1 and have evidently filled up an ancient hollow or lake-like expansion of the valleys of the ,bovey and ,teign4 ,the lignite is of bad quality for economical purposes1 as there is a great admixture in it of iron pyrites1 and it emits a sulphurous odour1 but it has been successfully applied to the baking of pottery1 for which some of the fine clays are well adapted4 ,mr4 ,pengelly has confirmed ,sir ,h4 ,de la ,beche's opinion that much of the upper portion of this old lacustrine formation has been removed by denudation4#e ,at the surface is a dense covering of clay and gravel with angular stones probably of the ,post-pliocene period1 for in the clay are three species of willow and the dwarf birch1 ,betula nana1 indicating a climate colder than that of ,devonshire at the present day4 ,below this are ,lower ,miocene strata about #cjj feet in thickness1 in the upper part of which are twenty-six beds of lignite1 clay1 and sand1 and at their base a ferruginous quartzose sand1 varying in thickness from two to twenty-seven feet4 ,below this sand are forty-five beds of alternating lignite and clay4 ,no shells or bones of mammalia1 and no insect1 with the exception of one fragment of a beetle 7,buprestis72 in a word1 no organic remains1 except plants1 have as yet been found4 ,these plants occur in fourteen of the beds--namely1 in two of the clays1 and the rest in the lignites4 ,one of the beds is a perfect mat of the debris of a coniferous tree1 called by ,heer ,sequoia ,couttsi1 intermixed with leaves of ferns4 ,the same ,sequoia 7before mentioned as a ,hempstead fossil1 p4 #bdf7 is spread through all parts of the formation1 its cones1 and seeds1 and branches of every age being preserved4 ,it is a species supplying a link between ,sequoia ,langsdorfii 7see ,fig4 #aec1 p4 #bch7 and ,s4 ,sternbergi1 the widely spread fossil representatives of the two living trees ,s4 sempervirens and ,s4 gigantea 7or ,wellingtonia71 both now confined to ,california4 ,another bed is full of the large rhizomes of ferns1 while two others are rich in dicotyledonous leaves4 ,in all1 ,professor ,heer enumerates forty-nine species of plants1 twenty of which are common to the ,miocene beds of the ,continent1 a majority of them being characteristic of the ,lower ,miocene4 ,the new species1 also of ,bovey1 are allied to plants of the older ,miocene deposits of ,switzerland1 ,germany1 and other ,continental countries4 ,the grape-stones of two species of vine occur in the clays1 and leaves of the fig and seeds of a water-lily4 ,the oak and laurel have supplied many leaves4 ,of the triple-nerved laurels several are referred to ,cinnamomum4 ,there are leaves also of a palm of which the genus is not determined4 ,leaves also of proteaceous forms1 like some of the ,continental fossils before mentioned1 occur1 and ferns like the well-known ,lastra stiriaca 7,fig4 #aed1 p4 #bch71 displaying at ,bovey1 as in ,switzerland1 its fructification4 ,the croziers of some of the young ferns are very perfect1 and were at first mistaken by collectors for shells of the genus ,planorbis4 ,on the whole1 the vegetation of ,bovey implies the existence of a sub-tropical climate in ,devonshire1 in the ,lower ,miocene period4 ,scotland3 ,isle of ,mull4--,in the sea-cliffs forming the headland of ,ardtun1 on the west coast of ,mull1 in the ,hebrides1 several bands of tertiary strata containing leaves of dicotyledonous plants were discovered in #ahea by the ,duke of ,argyll4#f ,from his description it appears that there are three leaf-beds1 varying in thickness from #a to #e feet1 which are interstratified with volcanic tuff and trap1 the whole mass being about #acj feet in thickness4 ,a sheet of basalt #dj feet thick covers the whole2 and another columnar bed of the same rock1 ten feet thick1 is exposed at the bottom of the cliff4 ,one of the leaf-beds consists of a compressed mass of leaves unaccompanied by any stems1 as if they had been blown into a marsh where a species of ,equisetum grew1 of which the remains are plentifully imbedded in clay4 ,it is supposed by the ,duke of ,argyll that this formation was accumulated in a shallow lake or marsh in the neighbourhood of a volcano1 which emitted showers of ashes and streams of lava4 ,the tufaceous envelope of the fossils may have fallen into the lake from the air as volcanic dust1 or have been washed down into it as mud from the adjoining land4 ,even without the aid of organic remains we might have decided that the deposit was newer than the chalk1 for chalk-flints containing cretaceous fossils were detected by the duke in the principal mass of volcanic ashes or tuff4#g ,the late ,edward ,forbes observed that some of the plants of this formation resembled those of ,croatia1 described by ,unger1 and his opinion has been confirmed by ,professor ,heer1 who found that the conifer most prevalent was the ,sequoia ,langsdorfii 7,fig4 #aec1 p4 #bch71 also ,corylus grossedentata1 a ,lower ,miocene species of ,switzerland and of ,menat in ,auvergne4 ,there is likewise a plane-tree1 the leaves of which seem to agree with those of ,platanus aceroides 7,fig4 #ada71 and a fern which is as yet peculiar to ,mull1 ,filicites hebridica1 ,forbes4 ,these interesting discoveries in ,mull led geologists to suspect that the basalt of ,antrim1 in ,ireland1 and of the celebrated ,giant's ,causeway1 might be of the same age4 ,the volcanic rocks that overlie the chalk1 and some of the strata associated with and interstratified between masses of basalt1 contain leaves of dicotyledonous plants1 somewhat imperfect1 but resembling the beech1 oak1 and plane1 and also some conifer of the genera pine and ,sequoia4 ,the general dearth of strata in the ,british ,isles1 intermediate in age between the formation of the ,eocene and ,pliocene periods1 may arise1 says ,professor ,forbes1 from the extent of dry land which prevailed in that vast interval of time4 ,if land predominated1 the only monuments we are likely ever to find of ,miocene date are those of lacustrine and volcanic origin1 such as the ,bovey ,coal in ,devonshire1 the ,ardtun beds in ,mull1 or the lignites and associated basalts in ,antrim4 ,lower ,miocene1 ,united states3 ,nebraska4--,in the territory of ,nebraska1 on the ,upper ,missouri1 near the ,platte ,river1 lat4 #db ,n41 a tertiary formation occurs1 consisting of white limestone1 marls1 and siliceous clay1 described by ,dr4 ,d4 ,dale ,owen1#h in which many bones of extinct quadrupeds1 and of chelonians of land or fresh-water forms1 are met with4 ,among these1 ,dr4 ,leidy describes a gigantic quadruped1 called by him ,titanotherium1 nearly allied to the ,palotherium1 but larger than any of the species found in the ,paris gypsum4 ,with these are several species of the genus ,oreodon1 ,leidy1 uniting the characters of pachyderms and ruminants also2 ,eucrotaphus1 another new genus of the same mixed character2 two species of rhinoceros of the sub-genus ,acerotherium1 a ,lower ,miocene form of ,europe before mentioned2 two species of ,archotherium1 a pachyderm allied to ,chropotamus and ,hyracotherium2 also ,pbrotherium1 an extinct ruminant allied to ,dorcatherium1 ,kaup2 also ,agriochoerus1 of ,leidy1 a ruminant allied to ,merycopotamus of ,falconer and ,cautley2 and1 lastly1 a large carnivorous animal of the genus ,machairodus1 the most ancient example of which in ,europe occurs in the ,lower ,miocene strata of ,auvergne1 but of which some species are found in ,pliocene deposits4 ,the turtles are referred to the genus ,testudo1 but have some affinity to ,emys4 ,on the whole1 the ,nebraska formation is probably newer than the ,paris gypsum1 and referable to the ,lower ,miocene period1 as above defined4 #a ,bulletin1 #ahef1 ,journ41 vol4 xii1 p4 #gfh4 #b ,heer 8,miocene baltische ,flora0 and 8,fossil-flora von ,alaska0 #ahfi4 #c ,d',archiac ,monogr41 pp4 #gi1 #ajj4 #d ,pengelly1 preface to ,the ,lignite ,formation of ,bovey ,tracey1 p4 xvii1 ,london1 #ahfc4 #e ,philos4 ,trans41 #ahfc4 ,paper by ,w4 ,pengelly1 ,f4,r4,s41 and ,dr4 ,oswald ,heer4 #f ,quart4 ,geol4 ,journal1 #ahea1 p4 #ai4 #g ,quart4 ,geol4 ,journal1 #ahea1 p4 #ij4 #h ,david ,dale ,owen1 ,geol4 ,survey of ,wisconsin1 etc41 ,philad41 #aheb4 ,,chapter ,,xvi4 ,,eocene ,,formations4 ,eocene ,areas of ,north of ,europe4 -- ,table of ,english and ,french ,eocene ,strata4 -- ,upper ,eocene of ,england4 -- ,bembridge ,beds4 -- ,osborne or ,st4 ,helen's ,beds4 -- ,headon ,series4 -- ,fossils of the ,barton ,sands and ,clays4 -- ,middle ,eocene of ,england4 -- ,shells1 ,nummulites1 ,fish and ,reptiles of the ,bracklesham ,beds and ,bagshot ,sands4 -- ,plants of ,alum ,bay and ,bournemouth4 -- ,lower ,eocene of ,england4 -- ,london ,clay ,fossils4 -- ,woolwich and ,reading ,beds formerly called 8,plastic ,clay40 ,fluviatile ,beds underlying ,deep-sea ,strata4 -- ,thanet ,sands4 -- ,upper ,eocene ,strata of ,france4 -- ,gypseous ,series of ,montmartre and ,extinct ,quadrupeds4 -- ,fossil ,footprints in ,paris ,gypsum4 -- ,imperfection of the ,record4 -- ,calcaire ,silicieux4 -- ,gres de ,beauchamp4 -- ,calcaire ,grossier4 -- ,miliolite ,limestone4 -- ,soissonnais ,sands4 -- ,lower ,eocene of ,france4 -- ,nummulitic ,formations of ,europe1 ,africa1 and ,asia4 -- ,eocene ,strata in the ,united ,states4 -- ,gigantic ,cetacean4 ,eocene ,areas of the ,north of ,europe4--,the strata next in order in the descending series are those which ,i term ,eocene4 ,fig4 #afd3 ,map of the principal ,eocene areas of ,north-western ,europe4 ,in the map 7,fig4 #afd7 the position of several ,eocene areas in the north of ,europe is pointed out4 ,when this map was constructed ,i classed as the newer part of the ,eocene those ,tertiary strata which have been described in the last chapter as ,lower ,miocene1 and to which ,m4 ,beyrich has given the name of ,oligocene4 ,none of these occur in the ,london ,basin1 and they occupy in that of ,hampshire1 as we have seen at p4 #bdd1 too insignificant a superficial area to be noticed in a map on this scale4 ,they fill a larger space in the ,paris ,basin between the ,seine and the ,loire1 and constitute also part of the northern limits of the area of the ,netherlands which are shaded in the map4 ,it is in the northern part of the ,isle of ,wight that we have the uppermost beds of the true ,eocene best exhibited--namely1 those which correspond in their fossils with the celebrated gypsum of the ,paris basin before alluded to1 p4 #bca 7see ,table1 p4 #beb74 ,that gypsum has been selected by almost all ,continental geologists as affording the best line of demarkation between the ,middle and ,lower ,tertiary1 or1 in other words1 between the ,lower ,miocene and ,eocene formations4 ,in reference to the ,table ,i may observe1 that the correlation of the ,french and ,english subdivisions here laid down is often a matter of great doubt and difficulty1 notwithstanding their geographical proximity4 ,this arises from various circumstances1 partly from the former prevalence of marine conditions in one basin simultaneously with fluviatile or lacustrine in the other1 and sometimes from the existence of land in one area causing a break or absence of all records during a period when deposits may have been in progress in the other basin4 ,as bearing on this subject1 it may be stated that we have unquestionable evidence of oscillations of level shown by the superposition of salt or brackish-water strata to fluviatile beds2 and those of deep-sea origin to strata formed in shallow water4 ,even if the upward and downward movements were uniform in amount and direction1 which is very improbable1 their effect in producing the conversion of sea into land or land into sea would be different1 according to the previous shape and varying elevation of the land and bottom of the sea4 ,lastly1 denudation1 marine and subarial1 has frequently caused the absence of deposits in one basin of corresponding age to those in the other1 and this destructive agency has been more than ordinarily effective on account of the loose and unconsolidated nature of the sands and clays4 ,,table ,,of ,,english ,,and ,,french ,,eocene ,,strata4 ,,upper ,,eocene ,english subdivisions ,french equivalents ,a4#a4 ,bembridge series1 ,isle of ,wight1 p4 #beb4 ,a4#a4 ,gypseous series of ,montmartre1 p4 #bgj4 ,a4#b4 ,osborne or ,st4 ,helen's series1 ,isle of ,wight1 p4 #bee4 ,a4#b and #c4 ,calcaire siliceux1 or ,travertin ,infrieur1 p4 #bgc4 ,a4#c4 ,headon series1 ,isle of ,wight1 p4 #bee4 ,a4#d4 ,barton series4 ,sands and clays of ,barton ,cliff1 ,hants1 p4 #beh4 ,a4#d4 ,grs de ,beauchamp1 or ,sables ,moyens1 p4 #bgc4 ,,middle ,,eocene ,b4#a4 ,bracklesham series1 p4 #bei4 ,b4#a4 ,calcaire ,grossier p4 #bgd ,b4#b4 ,alum ,bay and ,bournemouth beds1 p4 #bei4 ,b4#b4 ,wanting in ,france8 ,b4#b4 ,wanting in ,england8 ,b4#b4 ,soissonnais ,sands1 or ,lits ,coquilliers1 p4 #bge ,,lower ,,eocene ,c4#a4 ,london ,clay1 p4 #bfc4 ,c4#a4 ,argile de ,londres1 ,cassel1 near ,dunkirk4 ,c4#b4 ,woolwich and ,reading series1 p4 #bfg4 ,c4#b4 ,argile plastique and lignite1 p4 #bgf ,c4#c4 ,thanet sands1 p4 #bfi4 ,c4#c4 ,sables de ,bracheux1 p4 #bgf ,,upper ,,eocene1 ,,england4 ,bembridge ,series1 ,a4#a4--,these beds are about #abj feet thick1 and1 as stated in p4 #bde1 lie immediately under the ,hempstead beds1 near ,yarmouth1 in the ,isle of ,wight1 being conformable with those ,lower ,miocene strata4 ,they consist of marls1 clays1 and limestones of fresh-water1 brackish1 and marine origin4 ,some of the most abundant shells1 as ,cyrena semistriata var41 and ,paludina lenta1 ,fig4 #afc1 are common to this and to the overlying ,hempstead series2 but the majority of the species are distinct4 ,the following are the subdivisions described by the late ,professor ,forbes3 a4 ,upper marls1 distinguished by the abundance of ,melania turritissima1 ,forbes 7,fig4 #afe74 b4 ,lower marls1 characterised by ,cerithium mutabile1 ,cyrena pulchra1 etc41 and by the remains of ,trionyx 7see ,fig4 #aff74 c4 ,green marls1 often abounding in a peculiar species of oyster1 and accompanied by ,cerithium1 ,mytilus1 ,arca1 nucula1 etc4 d4 ,bembridge limestones1 compact cream-coloured limestones alternating with shales and marls1 in all of which land-shells are common1 especially at ,sconce1 near ,yarmouth1 as described by ,mr4 ,f4 ,edwards4 ,the ,bulimus ellipticus1 ,fig4 #afg1 and ,helix occlusa1 ,fig4 #afh1 are among its best known land-shells4 ,paludina orbicularis1 ,fig4 #afi1 is also of frequent occurrence4 ,one of the bands is filled with a little globular ,paludina4 ,among the fresh-water pulmonifera1 ,lymnea longiscata 7,fig4 #aga7 and ,planorbis discus 7,fig4 #agj7 are the most generally distributed3 the latter represents or takes the place of the ,planorbis euomphalus 7see ,fig4 #age7 of the more ancient ,headon series4 ,chara tuberculata 7,fig4 #agb7 is the characteristic ,bembridge gyrogonite or seed-vessel4 ,fig4 #afe3 ,melania turritissima1 ,fig4 #aff3 ,fragment of ,carapace of ,trionyx1 ,fig4 #afg3 ,bulimus ellipticus1 ,fig4 #afh3 ,helix occlusa1 ,fig4 #afi3 ,paludina orbicularis1 ,fig4 #agj3 ,planorbis discus1 ,fig4 #aga3 ,lymnea longiscata1 ,fig4 #agb3 ,chara tuberculata4 ,fig4 #agc3 ,lower molar tooth4 ,from this formation on the shores of ,whitecliff ,bay1 ,dr4 ,mantell obtained a fine specimen of a fan palm1 ,flabellaria ,lamanonis1 ,brong41 a plant first obtained from beds of corresponding age in the suburbs of ,paris4 ,the well-known building-stone of ,binstead1 near ,ryde1 a limestone with numerous hollows caused by ,cyren which have disappeared and left the moulds of their shells1 belongs to this subdivision of the ,bembridge series4 ,in the same ,binstead stone ,mr4 ,pratt and the ,reverend ,darwin ,fox first discovered the remains of mammalia characteristic of the gypseous series of ,paris1 as ,palotherium magnum 7,fig4 #agd71 ,p4 medium1 ,p4 minus1 ,p4 minimum1 ,p4 curtum1 ,p4 crassum2 also ,anoplotherium commune 7,fig4 #agc71 ,a4 secundarium1 ,dichobune cervinum1 and ,chropotamus ,cuvieri4 ,the ,palothere above alluded to resembled the living tapir in the form of the head1 and in having a short proboscis1 but its molar teeth were more like those of the rhinoceros4 ,palotherium magnum was of the size of a horse1 three or four feet high4 ,the woodcut1 ,fig4 #agd1 is one of the restorations which ,cuvier attempted of the outline of the living animal1 derived from the study of the entire skeleton4 ,as the vertical range of particular species of quadrupeds1 so far as our knowledge extends1 is far more limited than that of the testacea1 the occurrence of so many species at ,binstead1 agreeing with fossils of the ,paris gypsum1 strengthens the evidence derived from shells and plants of the synchronism of the two formations4 ,fig4 #agd3 ,palotherium magnum4 ,osborne or ,st4 ,helen's ,series1 ,a4#b4--,this group is of fresh and brackish-water origin1 and very variable in mineral character and thickness4 ,near ,ryde1 it supplies a freestone much used for building1 and called by ,professor ,forbes the ,nettlestone grit4 ,in one part ripple-marked flagstones occur1 and rocks with fucoidal markings4 ,the ,osborne beds are distinguished by peculiar species of ,paludina1 ,melania1 and ,melanopsis1 as also of ,cypris and the seeds of ,chara4 ,fig4 #age3 ,planorbis euomphalus1 ,fig4 #agf3 ,helix labyrinthica4 ,headon ,series ,a4#c4--,these beds are seen both in ,whitecliff ,bay1 ,headon ,hill1 and ,alum ,bay1 or at the east and west extremities of the ,isle of ,wight4 ,the upper and lower portions are fresh-water1 and the middle of mixed origin1 sometimes brackish and marine4 ,everywhere ,planorbis euomphalus1 ,fig4 #age1 characterises the fresh-water deposits1 just as the allied form1 ,p4 discus1 ,fig4 #agj1 does the ,bembridge limestone4 ,the brackish-water beds contain ,potamomya plana1 ,cerithium mutabile1 and ,potamides cinctus 7,fig4 #cg71 and the marine beds ,venus 7or ,cytherea7 incrassata1 a species common to the ,limburg beds and ,grs de ,fontainebleau1 or the ,lower ,miocene series4 ,the prevalence of salt-water remains is most conspicuous in some of the central parts of the formation4 ,fig4 #agg3 ,neritina concava4 ,among the shells which are widely distributed through the ,headon series are ,neritina concava 7,fig4 #agg71 ,lymnea caudata 7,fig4 #agh71 and ,cerithium concavum 7,fig4 #agi74 ,helix labyrinthica1 ,say 7,fig4 #agf71 a land-shell now inhabiting the ,united ,states1 was discovered in this series by ,mr4 ,searles ,wood in ,hordwell ,cliff4 ,it is also met with in ,headon ,hill1 in the same beds4 ,at ,sconce1 in the ,isle of ,wight1 it occurs in the ,bembridge series1 and affords a rare example of an ,eocene fossil of a species still living1 though1 as usual in such cases1 having no local connection with the actual geographical range of the species4 ,the lower and middle portion of the ,headon series is also met with in ,hordwell ,cliff 7or ,hordle1 as it is often spelt71 near ,lymington1 ,hants4 ,among the shells which abound in this cliff are ,paludina lenta and various species of ,lymnea1 ,planorbis1 ,melania1 ,cyclas1 ,unio1 ,potamomya1 ,dreissena1 etc4 ,fig4 #agh3 ,lymnea caudata1 ,fig4 #agi3 ,cerithium concavum4 ,among the chelonians we find a species of ,emys1 and no less than six species of ,trionyx2 among the saurians an alligator and a crocodile2 among the ophidians two species of land-snakes 7,paleryx1 ,owen72 and among the fish ,sir ,p4 ,egerton and ,mr4 ,wood have found the jaws1 teeth1 and hard shining scales of the genus ,lepidosteus1 or bony pike of the ,american rivers4 ,this same genus of fresh-water ganoids has also been met with in the ,hempstead beds in the ,isle of ,wight4 ,the bones of several birds have been obtained from ,hordwell1 and the remains of quadrupeds of the genera ,palotherium 7,p4 minus71 ,anoplotherium1 ,anthracotherium1 ,dichodon1 ,dichobune1 ,spalacodon1 and ,hynodon4 ,the latter offers1 ,i believe1 the oldest known example of a true carnivorous animal in the series of ,british fossils1 although ,i attach very little theoretical importance to the fact1 because herbivorous species are those most easily met with in a fossil state in all save cavern deposits4 ,in another point of view1 however1 this fauna deserves notice4 ,its geological position is considerably lower than that of the ,bembridge or ,montmartre beds1 from which it differs almost as much in species as it does from the still more ancient fauna of the ,lower ,eocene beds to be mentioned in the sequel4 ,it therefore teaches us what a grand succession of distinct assemblages of mammalia flourished on the earth during the ,eocene period4 ,many of the marine shells of the brackish-water beds of the above series1 both in the ,isle of ,wight and ,hordwell ,cliff1 are common to the underlying ,barton ,clay3 and1 on the other hand1 there are some fresh-water shells1 such as ,cyrena obovata1 which are common to the ,bembridge beds1 notwithstanding the intervention of the ,st4 ,helen's series4 ,the white and green marls of the ,headon series1 and some of the accompanying limestones1 often resemble the ,eocene strata of ,france in mineral character and colour in so striking a manner as to suggest the idea that the sediment was derived from the same region or produced contemporaneously under very similar geographical circumstances4 ,at ,brockenhurst1 near ,lyndhurst1 in the ,new ,forest1 marine strata have recently been found containing fifty-nine shells1 of which many have been described by ,mr4 ,edwards4 ,these beds rest on the ,lower ,headon1 and are considered as the equivalent of the middle part of the ,headon series1 many of the shells being common to the brackish-water or ,middle ,headon beds of ,colwell and ,whitecliff ,bays1 such as ,cancellaria muricata1 ,sowerby1 ,fusus labiatus1 ,sowerby1 etc4 ,in these beds at ,brockenhurst1 corals1 ably described by ,dr4 ,duncan1 have recently been found in abundance and perfection2 see ,fig4 #ahj1 ,solenastra cellulosa4 ,fig4 #ahj3 ,solenastra cellulosa4 ,baron von ,knen#a has pointed out that no less than forty-six out of the fifty-nine ,brockenhurst shells1 or a proportion of #gh per cent1 agree with species occurring in ,dumont's ,lower ,tongrian formation in ,belgium4 ,this being the case1 we might fairly expect that if we had a marine equivalent of the ,bembridge series or of the contemporaneous ,paris gypsum1 we should find it to contain a still greater number of shells common to the ,tongrian beds of ,belgium1 but the exact correlation of these fresh-water groups of ,france1 ,belgium1 and ,britain has not yet been fully made out4 ,it is possible that the ,tongrian of ,dumont may be newer than the ,bembridge series1 and therefore referable to the ,lower ,miocene4 ,if ever the whole series should be complete1 we must be prepared to find the marine equivalent of the ,bembridge beds1 or the uppermost ,eocene1 passing by imperceptible shades into the inferior beds of the overlying ,miocene strata4 ,among the fossils found in the ,middle ,headon are ,cytherea incrassata and ,cerithium plicatum 7,fig4 #afj74 ,these shells1 especially the latter1 are very characteristic of the ,lower ,miocene1 and their occurrence in the ,headon series has been cited as an objection to the line proposed to be drawn between ,miocene and ,eocene4 ,but if we were to attach importance to such occasional passages1 we should soon find that no lines of division could be drawn anywhere1 for in the present state of our knowledge of the ,tertiary series there will always be species common to beds above and below our boundary-lines4 ,fig4 #aha3 ,chama squamosa4 ,barton ,series 7,sands and ,clays71 ,a4#d ,table--,both in the ,isle of ,wight1 and in ,hordwell ,cliff1 ,hants1 the ,headon beds1 above-mentioned1 rest on white sands usually devoid of fossils1 and used in the ,isle of ,wight for making glass4 ,in one of these sands ,dr4 ,wright found ,chama squamosa1 a ,barton ,clay shell1 in great plenty1 and certain impressions of marine shells have been found in sands supposed to be of the same age in ,whitecliff ,bay4 ,these sands have been called ,upper ,bagshot in the maps of our ,government ,survey1 but this identification of a fossiliferous series in the ,isle of ,wight with an unfossiliferous formation in the ,london ,basin can scarcely be depended upon4 ,the ,barton ,clay1 which immediately underlies these sands1 is seen vertical in ,alum ,bay1 ,isle of ,wight1 and nearly horizontal in the cliffs of the mainland near ,lymington4 ,this clay1 together with the ,bracklesham beds1 presently to be described1 has been termed ,middle ,bagshot by the ,survey4 ,in ,barton ,cliff1 where it attains a thickness of about #cjj feet1 it is rich in marine fossils4 ,it was formerly confounded with the ,london ,clay1 an older ,eocene deposit of very similar mineral character1 to be mentioned 7p4 #bfc71 which contains many shells in common1 but not more than one-fourth of the whole4 ,in other words1 there are known at present #bdg species in the ,london ,clay and #cba in that of ,barton1 and only #gj common to the two formations4 ,fifty-six of these have been found in the intermediate ,bracklesham beds1 and the reappearance of the other #ad may imply a return of similar conditions1 whether of temperature or depth or of a muddy argillaceous bottom1 common to the two periods of the ,london and ,barton ,clays4 ,according to ,m4 ,hebert1 the most characteristic ,barton ,clay fossils correspond to those of the ,gres de ,beauchamp1 or ,sables ,moyens1 of the ,paris ,basin1 but it also contains many common to the older ,calcaire ,grossier4 ,,shells ,,of ,,the ,,barton ,,clay4 ,certain foraminifera called ,nummulites begin1 when we study the ,tertiary formations in a descending order1 to make their first appearance in these beds4 ,a small species called ,nummulites variolaria1 ,fig4 #aij1 is found both on the ,hampshire coast and in beds of the same age in ,whitecliff ,bay1 in the ,isle of ,wight4 ,several marine shells1 such as ,corbula pisum 7,fig4 #aeh71 are common to the ,barton beds and the ,hempstead or ,lower ,miocene series1 and a still greater number1 as before stated1 are common to the ,headon series4 ,fig4 #ahb3 ,mitra scabra1 ,fig4 #ahc3 ,voluta ambigua1 ,fig4 #ahd3 ,typhis pungens1 ,fig4 #ahe3 ,voluta athleta1 ,fig4 #ahf3 ,terebellum fusiforme1 ,fig4 #ahg3 ,terebellum sopita1 ,fig4 #ahh3 ,cardita sulcata1 ,fig4 #ahi3 ,crassatella sulcata1 ,fig4 #aij3 ,nummulites variolaria4 ,,middle ,,eocene1 ,,england4 ,bracklesham ,beds and ,bagshot ,sands1 ,b4#a1 ,table--,beneath the ,barton ,clay we find in the north of the ,isle of ,wight1 both in ,alum and ,whitecliff ,bays1 a great series of various coloured sands and clays for the most part unfossiliferous1 and probably of estuarine origin4 ,as some of these beds contain ,cardita planicosta 7,fig4 #aia7 they have been identified with the marine beds much richer in fossils seen in the coast section in ,bracklesham ,bay near ,chichester in ,sussex1 where the strata consist chiefly of green clayey sands with some lignite4 ,among the ,bracklesham fossils besides the ,cardita1 the huge ,cerithium giganteum is seen1 so conspicuous in the ,calcaire ,grossier of ,paris1 where it is sometimes two feet in length4 ,the ,nummulites lvigata 7see ,fig4 #aib71 so characteristic of the lower beds of the ,calcaire ,grossier in ,france1 where it sometimes forms stony layers1 as near ,compigne1 is very common in these beds1 together with ,n4 scabra and ,n4 variolaria4 ,out of #aic species of testacea procured from the ,bagshot and ,bracklesham beds in ,england1 #abf occur in the ,calcaire ,grossier in ,france4 ,it was clearly1 therefore1 coeval with that part of the ,parisian series more nearly than with any other4 ,fig4 #aia3 ,cardita 7,venericardia7 planicosta1 ,fig4 #aib3 ,nummulites 7,nummularia7 lavigata4 ,according to tables compiled from the best authorities by ,mr4 ,etheridge1 the number of mollusca now known from the ,bracklesham beds in ,great ,britain is #cic1 of which no less than #bdj are peculiar to this subdivision of the ,british ,eocene series1 while #gj are common to the ,older ,london ,clay1 and #adj to the ,newer ,barton ,clay4 ,the volutes and cowries of this formation1 as well as the lunulites and corals1 favour the idea of a warm climate having prevailed1 which is borne out by the discovery of a serpent1 ,palophis typhus 7see ,fig4 #aic71 exceeding1 according to ,professor ,owen1 twenty feet in length1 and allied in its osteology to the ,boa1 ,python1 ,coluber1 and ,hydrus4 ,the compressed form and diminutive size of certain caudal vertebr indicate so much analogy with ,hydrus as to induce ,professor ,owen to pronounce this extinct ophidian to have been marine4#b ,among the companions of the sea-snake of ,bracklesham was an extinct crocodile 7,gavialis ,dixoni1 ,owen71 and numerous fish1 such as now frequent the seas of warm latitudes1 as the ,ostracion of the family ,balistid1 of which a dorsal spine is figured 7see ,fig4 #aid71 and gigantic rays of the genus ,myliobates 7see ,fig4 #aie74 ,fig4 #aic3 ,palophis typhoeus1 ,owen2 an ,eocene sea-serpent1 ,fig4 #aid3 ,defensive spine of ,ostracion4 ,fig4 #aie3 ,dental plates of ,myliobates ,edwardsi4 ,the teeth of sharks also1 of the genera ,carcharodon1 ,otodus1 ,lamna1 ,galeocerdo1 and others1 are abundant4 7,see ,figs4 #aif1 #aig1 #aih1 #aii47 ,fig4 #aif3 ,carcharodon angustidens1 ,fig4 #aig3 ,otodus obliquus1 ,fig4 #aih3 ,lamna elegans1 ,fig4 #aii3 ,galcocerdo latidens4 ,,marine ,,shells ,,of ,,bracklesham ,,beds4 ,alum ,bay and ,bournemouth ,beds4 7,lower ,bagshot of ,english ,survey71 ,b4#b1 ,table--,to that great series of sands and clays which intervene between the equivalents of the ,bracklesham ,beds and the ,london ,clay or ,lower ,eocene1 our ,government ,survey has given the name of the ,lower ,bagshot sands1 for they are supposed to agree in age with the inferior unfossiliferous sands of the country round ,bagshot in the ,london ,basin4 ,this part of the series is finely exposed in the vertical beds of ,alum bay1 in the ,isle of ,wight1 and east and west of ,bournemouth1 on the south coast of ,hampshire4 ,in some of the close and white compact clays of this locality1 there are not only dicotyledonous leaves1 but numerous fronds of ferns allied to ,gleichenia which are well preserved with their fruit4 ,fig4 #bjj3 ,pleurotoma attenuata1 ,fig4 #bja3 ,voluta ,selseensis1 ,fig4 #bjb3 ,turritella multisulcata1 ,fig4 #bjc3 ,lucina serrata1 ,fig4 #bjd3 ,conus deperditus4 ,none of the beds are of great horizontal extent1 and there is much cross-stratification in the sands1 and in some places black carbonaceous seams and lignite4 ,in the midst of these leaf-beds in ,studland ,bay1 ,purbeck shells of the genus ,unio attest the fresh-water origin of the white clay4 ,no less than forty species of plants are mentioned by ,,mm4 de la ,harpe and ,gaudin from this formation in ,hampshire1 among which the ,proteace 7,dryandra1 etc47 and the fig tribe are abundant1 as well as the cinnamon and several other laurine1 with some papilionaceous plants4 ,on the whole1 they remind the botanist of the types of subtropical ,india and ,australia4#c ,heer has mentioned several species which are common to this ,alum ,bay flora and that of ,monte ,bolca1 near ,verona1 so celebrated for its fossil fish1 and where the strata contain nummulites and other ,middle ,eocene fossils4 ,he has particularly alluded to ,aralia primigenia 7of which genus a fruit has since been found by ,mr4 ,mitchell at ,bournemouth71 ,daphnogene ,veronensis1 and ,ficus granadilla1 as among the species common to and characteristic of the ,isle of ,wight and ,italian ,eocene beds2 and he observes that in the flora of this period these forms of a temperate climate which constitute a marked feature in the ,european ,miocene formations1 such as the willow1 poplar1 birch1 alder1 elm1 hornbeam1 oak1 fir1 and pine1 are wanting4 ,the ,american types are also absent1 or much more feebly represented than in the ,miocene period1 although fine specimens of the fan-palm 7,sabal7 have been found in these ,eocene clays at ,studland4 ,the number of exotic forms which are common to the ,eocene and ,miocene strata of ,europe1 like those to be alluded to in the sequel which are common to the ,eocene and ,cretaceous fauna1 demonstrate the remoteness of the times in which the geographical distribution of living plants originated4 ,a great majority of the ,eocene genera have disappeared from our temperate climates1 but not the whole of them2 and they must all have exerted some influence on the assemblages of species which succeeded them4 ,many of these last occurring in the ,upper ,miocene are indeed so closely allied to the flora now surviving as to make it questionable1 even in the opinion of naturalists opposed to the doctrine of transmutation1 whether they are not genealogically related the one to the other4 ,,lower ,,eocene ,,formations1 ,,england4 ,london ,clay1 ,c4#a1 ,table--,this formation underlies the preceding1 and sometimes attains a thickness of #ejj feet4 ,it consists of tenacious brown and bluish-grey clay1 with layers of concretions called septaria1 which abound chiefly in the brown clay1 and are obtained in sufficient numbers from sea-cliffs near ,harwich1 and from shoals off the coast of ,essex and the ,isle of ,sheppey1 to be used for making ,roman cement4 ,the total number of ,british fossil mollusca known at present 7,january1 #ahgj7 in this formation are #bed1 of which #aff are peculiar1 or not found in other ,eocene beds in this country4 ,the principal localities of fossils in the ,london clay are ,highgate ,hill1 near ,london1 the ,island of ,sheppey at the mouth of the ,thames1 and ,bognor on the ,sussex coast4 ,out of #acc fossil shells1 ,mr4 ,prestwich found only #bj to be common to the ,calcaire ,grossier 7from which #fjj species have been obtained71 while #cc are common to the 8,lits ,coquilliers0 7p4 #bge71 in which #bjj species are known in ,france4 ,in the ,island of ,sheppey near the mouth of the ,thames1 the thickness of the ,london ,clay is estimated by ,mr4 ,prestwich to be more than #ejj feet1 and it is in the uppermost #ej feet that a great number of fossil fruits were obtained1 being chiefly found on the beach when the sea has washed away the clay of the rapidly wasting cliffs4 ,fig4 #bje3 ,nipadites ellipticus4 ,mr4 ,bowerbank1 in a valuable publication on these fossil fruits and seeds1 has described no less than thirteen fruits of palms of the recent type ,nipa1 now only found in the ,molucca and ,philippine ,islands1 and in ,bengal 7see ,fig4 #bje74 ,in the delta of the ,ganges1 ,dr4 ,hooker observed the large nuts of ,nipa fruticans floating in such numbers in the various arms of that great river1 as to obstruct the paddle-wheels of steamboats4 ,these plants are allied to the cocoanut tribe on the one side1 and on the other to the ,pandanus1 or screw-pine4 ,there are also met with three species of ,anona1 or custard-apple2 and cucurbitaceous fruits 7of the gourd and melon family71 and fruits of various species of ,acacia4 ,besides fir-cones or fruit of true ,conifer there are cones of ,proteace in abundance1 and the celebrated botanist the late ,robert ,brown pointed out the affinity of these to the ,new ,holland types ,petrophila and ,isopogon4 ,of the first there are about fifty1 and of the second thirty described species now living in ,australia4 ,ettingshausen remarked in #ahea that five of the fossil species from ,sheppey1 named by ,bowerbank#d were specimens of the same fruit 7see ,fig4 #bjf71 in different states of preservation2 and ,mr4 ,carruthers1 having examined the original specimens now in the ,british ,museum1 tells me that all these cones from ,sheppey may be reduced to two species1 which have an undoubted affinity to the two existing ,australian genera above mentioned1 although their perfect identity in structure cannot be made out4 ,fig4 #bjf3 ,eocene ,proteaceous ,fruit 7,petrophiloides ,richardsoni4 ,the contiguity of land may be inferred not only from these vegetable productions1 but also from the teeth and bones of crocodiles and turtles1 since these creatures1 as ,dean ,conybeare remarked1 must have resorted to some shore to lay their eggs4 ,of turtles there were numerous species referred to extinct genera4 ,these are1 for the most part1 not equal in size to the largest living tropical turtles4 ,a sea-snake1 which must have been thirteen feet long1 of the genus ,palophis before mentioned 7p4 #bfa7 has also been described by ,professor ,owen from ,sheppey1 of a different species from that of ,bracklesham1 and called ,p4 toliapicus4 ,a true crocodile1 also1 ,crocodilus toliapicus1 and another saurian more nearly allied to the gavial1 accompany the above fossils2 also the relics of several birds and quadrupeds4 ,one of these last belongs to the new genus ,hyracotherium of ,owen1 of the hog tribe1 allied to ,chropotamus1 another is a ,lophiodon2 a third a pachyderm called ,coryphodon eocnus by ,owen1 larger than any existing tapir4 ,all these animals seem to have inhabited the banks of the great river which floated down the ,sheppey fruits4 ,they imply the existence of a mammiferous fauna antecedent to the period when nummulites flourished in ,europe and ,asia1 and therefore before the ,alps1 ,pyrenees1 and other mountain-chains now forming the backbones of great continents1 were raised from the deep2 nay1 even before a part of the constituent rocky masses now entering into the central ridges of these chains had been deposited in the sea4 ,the marine shells of the ,london ,clay confirm the inference derivable from the plants and reptiles in favour of a high temperature4 ,thus many species of ,conus and ,voluta occur1 a large ,cypra1 ,c4 oviformis1 a very large ,rostellaria 7,fig4 #bji71 a species of ,cancellaria1 six species of ,nautilus 7,fig4 #baa71 besides other ,cephalopoda of extinct genera1 one of the most remarkable of which is the ,belosepia 7,fig4 #bab74 ,among many characteristic bivalve shells are ,leda amygdaloides 7,fig4 #bac7 and ,cryptodon angulatum 7,fig4 #bad71 and among the ,radiata a star-fish1 ,astropecten 7,fig4 #bae47 ,fig4 #bjg3 ,voluta nodosa1 ,fig4 #bjh3 ,phorus extensus1 ,fig4 #bji3 ,rostellaria 7,hippocrenes7 ampla1 ,fig4 #baj3 ,nautilus centralis1 ,fig4 #baa3 ,aturia ziczac1 ,fig4 #bab3 ,belosepia sepioidea1 ,fig4 #bac3 ,leda amygdaloides1 ,fig4 #bad3 ,cyptodon 7,axinus7 angulatum1 ,fig4 #bae3 ,astropecten crispatus4 ,these fossils are accompanied by a sword-fish 7,tetrapterus priscus1 ,agassiz71 about eight feet long1 and a saw-fish 7,pristis bisulcatus1 ,agassiz71 about ten feet in length2 genera now foreign to the ,british seas4 ,on the whole1 about eighty species of fish have been described by ,m4 ,agassiz from these beds of ,sheppey1 and they indicate1 in his opinion1 a warm climate4 ,in the lower part of the ,london clay at ,kyson1 a few miles east of ,woodbridge1 the remains of mammalia have been detected4 ,some of these have been referred by ,professor ,owen to an opossum1 and others to the genus ,hyracotherium4 ,the teeth of this last-mentioned pachyderm were at first1 in #ahdj1 supposed to belong to a monkey1 an opinion afterwards abandoned by ,owen when more ample materials for comparison were obtained4 ,woolwich and ,reading ,series1 ,c4#b1 ,table--,this formation was formerly called the ,plastic ,clay1 as it agrees with a similar clay used in pottery which occupies the same position in the ,french series1 and it has been used for the like purposes in ,england4#e ,no formations can be more dissimilar1 on the whole1 in mineral character than the ,eocene deposits of ,england and ,paris2 those of our own island being almost exclusively of mechanical origin--accumulations of mud1 sand1 and pebbles2 while in the neighbourhood of ,paris we find a great succession of strata composed of limestones1 some of them siliceous1 and of crystalline gypsum and siliceous sandstone1 and sometimes of pure flint used for millstones4 ,hence it is often impossible1 as before stated1 to institute an exact comparison between the various members of the ,english and ,french series1 and to settle their respective ages4 ,but in regard to the division which we have now under consideration1 whether we study it in the basins of ,london1 ,hampshire1 or ,paris1 we recognise as a general rule the same mineral character1 the beds consisting over a large area of mottled clays and sand1 with lignite1 and with some strata of well-rolled flint pebbles1 derived from the chalk1 varying in size1 but occasionally several inches in diameter4 ,these strata may be seen in the ,isle of ,wight in contact with the chalk1 or in the ,london basin1 at ,reading1 ,blackheath1 and ,woolwich4 ,in some of the lowest of them1 banks of oysters are observed1 consisting of ,ostrea bellovacina1 so common in ,france in the same relative position4 ,in these beds at ,bromley1 ,dr4 ,buckland found a large pebble to which five full-grown oysters were affixed1 in such a manner as to show that they had commenced their first growth upon it1 and remained attached to it through life4 ,fig4 #baf3 ,cyrena cuneiformis1 ,fig4 #bag3 ,melania 7,melanatria7 inquinata4 ,in several places1 as at ,woolwich on the ,thames1 at ,newhaven in ,sussex1 and elsewhere1 a mixture of marine and fresh-water testacea distinguishes this member of the series4 ,among the latter1 ,cyrena cuneiformis 7see ,fig4 #baf7 and ,melania inquinata 7see ,fig4 #bag7 are very common1 as in beds of corresponding age in ,france4 ,they clearly indicate points where rivers entered the ,eocene sea4 ,usually there is a mixture of brackish1 fresh-water1 and marine shells1 and sometimes1 as at ,woolwich1 proofs of the river and the sea having successively prevailed on the same spot4 ,at ,new ,charlton1 in the suburbs of ,woolwich1 ,mr4 de la ,condamine discovered in #ahdi1 and pointed out to me1 a layer of sand associated with well-rounded flint pebbles in which numerous individuals of the ,cyrena tellinella were seen standing endwise with both their valves united1 the siphonal extremity of each shell being uppermost1 as would happen if the mollusks had died in their natural position4 ,i have described#f a bank of sandy mud1 in the delta of the ,alabama ,river at ,mobile1 on the borders of the ,gulf of ,mexico1 where in #ahdf ,i dug out at low tide specimens of living species of ,cyrena and of a ,gnathodon1 which were similarly placed with their shells erect1 or in a posture which enables the animal to protrude its siphon upward1 and draw in or reject water at pleasure4 ,the water at ,mobile is usually fresh1 but sometimes brackish4 ,at ,woolwich a body of river-water must have flowed permanently into the sea where the ,cyren lived1 and they may have been killed suddenly by an influx of pure salt-water1 which invaded the spot when the river was low1 or when a subsidence of land took place4 ,traced in one direction1 or eastward towards ,herne ,bay1 the ,woolwich beds assume more and more of a marine character2 while in an opposite1 or south-western direction1 they become1 as near ,chelsea and other places1 more fresh-water1 and contain ,unio1 ,paludina1 and layers of lignite1 so that the land drained by the ancient river seems clearly to have been to the south-west of the present site of the metropolis4 ,fluviatile ,beds underlying ,deep-sea ,strata4--,before the minds of geologists had become familiar with the theory of the gradual sinking of land1 and its conversion into sea at different periods1 and the consequent change from shallow to deep water1 the fluviatile and littoral character of this inferior group appeared strange and anomalous4 ,after passing through hundreds of feet of ,london clay1 proved by its fossils to have been deposited in deep salt-water1 we arrive at beds of fluviatile origin1 and associated with them masses of shingle1 attaining at ,blackheath1 near ,london1 a thickness of #ej feet4 ,these shingle banks are probably of marine origin1 but they indicate the proximity of land1 and the existence of a shore where the flints of the chalk were rolled into sand and pebbles1 and spread over a wide space4 ,we have1 therefore1 first1 as before stated 7p4 #bfh71 evidence of oscillations of level during the accumulation of the ,woolwich series1 then of a great submergence1 which allowed a marine deposit #ejj thick to be laid over the antecedent beds of fresh and brackish water origin4 ,thanet ,sands1 ,c4#c1 ,table--,the ,woolwich or plastic clay above described may often be seen in the ,hampshire basin in actual contact with the chalk1 constituting in such places the lowest member of the ,british ,eocene series4 ,but at other points another formation of marine origin1 characterised by a somewhat different assemblage of organic remains1 has been shown by ,mr4 ,prestwich to intervene between the chalk and the ,woolwich series4 ,for these beds he has proposed the name of 8,thanet ,sands10 because they are well seen in the ,isle of ,thanet1 in the northern part of ,kent1 and on the sea-coast between ,herne ,bay and the ,reculvers1 where they consist of sands with a few concretionary masses of sandstone1 and contain1 among other fossils1 ,pholadomya cuneata1 ,cyprina morrisii1 ,corbula longirostris1 ,scalaria ,bowerbankii1 etc4 ,the greatest thickness of these beds is #ij feet4 ,,upper ,,eocene ,,formations ,,of ,,france4 ,the tertiary formations in the neighbourhood of ,paris consist of a series of marine and fresh-water strata1 alternating with each other1 and filling up a depression in the chalk4 ,the area which they occupy has been called the ,paris ,basin1 and is about #ahj miles in its greatest length from north to south1 and about #ij miles in breadth from east to west4 ,,mm4 ,cuvier and ,brongniart attempted1 in #ahaj1 to distinguish five different groups1 comprising three fresh-water and two marine1 which were supposed to imply that the waters of the ocean1 and of rivers and lakes1 had been by turns admitted into and excluded from the same area4 ,investigations since made in the ,hampshire and ,london basins have rather tended to confirm these views1 at least so far as to show that since the commencement of the ,eocene period there have been great movements of the bed of the sea1 and of the adjoining lands1 and that the superposition of deep-sea to shallow-water deposits 7the ,london ,clay1 for example1 to the ,woolwich beds7 can only be explained by referring to such movements4 ,it appears1 notwithstanding1 from the researches of ,m4 ,constant ,prevost1 that some of the minor alternations and intermixtures of fresh-water and marine deposits1 in the ,paris basin1 may be accounted for without such changes of level1 by imagining both to have been simultaneously in progress1 in the same bay of the same sea1 or a gulf into which many rivers entered4 ,gypseous ,series of ,montmartre1 ,a4#a1 ,table--,to enlarge on the numerous subdivisions of the ,parisian strata would lead me beyond my present limits2 ,i shall therefore give some examples only of the most important formations4 ,beneath the ,grs de ,fontainebleau1 belonging to the ,lower ,miocene period1 as before stated1 we find1 in the neighbourhood of ,paris1 a series of white and green marls1 with subordinate beds of gypsum4 ,these are most largely developed in the central parts of the ,paris basin1 and1 among other places1 in the hill of ,montmartre1 where its fossils were first studied by ,cuvier4 ,the gypsum quarried there for the manufacture of plaster of ,paris occurs as a granular crystalline rock1 and1 together with the associated marls1 contains land and fluviatile shells1 together with the bones and skeletons of birds and quadrupeds4 ,several land-plants are also met with1 among which are fine specimens of the fan-palm or palmetto tribe 7,flabellaria74 ,the remains also of fresh-water fish1 and of crocodiles and other reptiles1 occur in the gypsum4 ,the skeletons of mammalia are usually isolated1 often entire1 the most delicate extremities being preserved2 as if the carcasses1 clothed with their flesh and skin1 had been floated down soon after death1 and while they were still swollen by the gases generated by their first decomposition4 ,the few accompanying shells are of those light kinds which frequently float on the surface of rivers1 together with wood4 ,in this formation the relics of about fifty species of quadrupeds1 including the genera ,palotherium 7see ,fig4 #agd71 ,anoplotherium 7see ,fig4 #bah71 and others1 have been found1 all extinct1 and nearly four-fifths of them belonging to the ,perissodactyle or odd-toed division of the order ,pachydermata1 which now contains only four living genera1 namely1 rhinoceros1 tapir1 horse1 and hyrax4 ,with them a few carnivorous animals are associated1 among which are the ,hynodon dasyuroides1 a species of dog1 ,canis ,parisiensis1 and a weasel1 ,cynodon ,parisiensis4 ,of the ,rodentia are found a squirrel2 of the ,cheiroptera1 a bat2 while the ,marsupalia 7an order now confined to ,america1 ,australia1 and some contiguous islands7 are represented by an opossum4 ,of birds1 about ten species have been ascertained1 the skeletons of some of which are entire4 ,none of them are referable to existing species4#g ,the same remark1 according to ,,mm4 ,cuvier and ,agassiz1 applies both to the reptiles and fish4 ,among the last are crocodiles and tortoises of the genera ,emys and ,trionyx4 ,fig4 #bah3 ,xiphodon gracile1 or ,anoplotherium gracile4 ,the tribe of land quadrupeds most abundant in this formation is such as now inhabits alluvial plains and marshes1 and the banks of rivers and lakes1 a class most exposed to suffer by river inundations4 ,among these were several species of ,palotherium1 a genus before alluded to4 ,these were associated with the ,anoplotherium1 a tribe intermediate between pachyderms and ruminants4 ,one of the three divisions of this family was called by ,cuvier ,xiphodon4 ,their forms were slender and elegant1 and one1 named ,xiphodon gracile 7,fig4 #bah71 was about the size of the chamois2 and ,cuvier inferred from the skeleton that it was as light1 graceful1 and agile as the gazelle4 ,fossil ,footprints4--,there are three superimposed masses of gypsum in the neighbourhood of ,paris1 separated by intervening deposits of laminated marl4 ,in the uppermost of the three1 in the valley of ,montmorency1 ,m4 ,desnoyers discovered in #ahei many footprints of animals occurring at no less than six different levels4#h ,the gypsum to which they belong varies from thirty to fifty feet in thickness1 and is that which has yielded to the naturalist the largest number of bones and skeletons of mammalia1 birds1 and reptiles4 ,i visited the quarries1 soon after the discovery was made known1 with ,m4 ,desnoyers1 who also showed me large slabs in the ,museum at ,paris1 where1 on the upper planes of stratification1 the indented foot-marks were seen1 while corresponding casts in relief appeared on the lower surfaces of the strata of gypsum which were immediately superimposed4 ,a thin film of marl1 which before it was dried and condensed by pressure must have represented a much thicker layer of soft mud1 intervened between the beds of solid gypsum4 ,on this mud the animals had trodden1 and made impressions which had penetrated to the gypseous mass below1 then evidently unconsolidated4 ,tracks of the ,anoplotherium with its bisulcate hoof1 and the trilobed footprints of ,palotherium1 were seen of different sizes1 corresponding to those of several species of these genera which ,cuvier had reconstructed1 while in the same beds were foot-marks of carnivorous mammalia4 ,the tracks also of fluviatile1 lacustrine1 and terrestrial tortoises 7,emys1 ,trionyx1 etc47 were discovered1 also those of crocodiles1 iguanas1 geckos1 and great batrachians1 and the footprints of a huge bird1 apparently a wader1 of the size of the gastornis1 to be mentioned in the sequel4 ,there were likewise the impressions of the feet of other creatures1 some of them clearly distinguishable from any of the fifty extinct types of mammalia of which the bones have been found in the ,paris gypsum4 ,the whole assemblage1 says ,desnoyers1 indicate the shores of a lake1 or several small lakes communicating with each other1 on the borders of which many species of pachyderms wandered1 and beasts of prey which occasionally devoured them4 ,the tooth-marks of these last had been detected by palontologists long before on the bones and skulls of ,paleotheres entombed in the gypsum4 ,imperfection of the ,record4--,these foot-marks have revealed to us new and unexpected proofs that the air-breathing fauna of the ,upper ,eocene period in ,europe far surpassed in the number and variety of its species the largest estimate which had previously been formed of it4 ,we may now feel sure that the mammalia1 reptiles1 and birds which have left portions of their skeletons as memorials of their existence in the solid gypsum constituted but a part of the then living creation4 ,similar inferences may be drawn from the study of the whole succession of geological records4 ,in each district the monuments of periods embracing thousands1 and probably in some instances hundreds of thousands of years1 are totally wanting4 ,even in the volumes which are extant the greater number of the pages are missing in any given region1 and where they are found they contain but few and casual entries of the physical events or living beings of the times to which they relate4 ,it may also be remarked that the subordinate formations met with in two neighbouring countries1 such as ,france and ,england 7the minor ,tertiary groups above enumerated71 commonly classed as equivalents and referred to corresponding periods1 may nevertheless have been by no means strictly coincident in date4 ,though called contemporaneous1 it is probable that they were often separated by intervals of many thousands of years4 ,we may compare them to double stars1 which appear single to the naked eye because seen from a vast distance in space1 and which really belong to one and the same stellar system1 though occupying places in space extremely remote if estimated by our ordinary standard of terrestrial measurements4 ,calcaire silicieux1 or ,travertin infrieur1 ,a4#b and #c1 ,table--,this compact siliceous limestone extends over a wide area4 ,it resembles a precipitate from the waters of mineral springs1 and is often traversed by small empty sinuous cavities4 ,it is1 for the most part1 devoid of organic remains1 but in some places contains fresh-water and land species1 and never any marine fossils4 ,the calcaire siliceux and the calcaire grossier usually occupy distinct parts of the ,paris basin1 the one attaining its fullest development in those places where the other is of slight thickness4 ,they are described by some writers as alternating with each other towards the centre of the basin1 as at ,sergy and ,osny4 ,the gypsum1 with its associated marls before described1 is in greatest force towards the centre of the basin1 where the calcaire grossier and calcaire silicieux are less fully developed4 ,grs de ,beauchamp1 or ,sables ,moyens1 ,a4#d1 ,table--,in some parts of the ,paris basin1 sands and marls1 called the ,grs de ,beauchamp1 or ,sables moyens1 divide the gypseous beds from the calcaire grossier proper4 ,these sands1 in which a small nummulite 7,n4 variolaria7 is very abundant1 contain more than #cjj species of marine shells1 many of them peculiar1 but others common to the next division4 ,,middle ,,eocene ,,formations ,,of ,,france4 ,calcaire ,grossier1 upper and middle1 ,b4#a1 ,table--,the upper division of this group consists in great part of beds of compact1 fragile limestone1 with some intercalated green marls4 ,the shells in some parts are a mixture of ,cerithium1 ,cyclostoma1 and ,corbula2 in others ,limnea1 ,cerithium1 ,paludina1 etc4 ,in the latter1 the bones of reptiles and mammalia1 ,palotherium and ,lophiodon1 have been found4 ,the middle division1 or calcaire grossier proper1 consists of a coarse limestone1 often passing into sand4 ,it contains the greater number of the fossil shells which characterise the ,paris basin4 ,no less than #djj distinct species have been procured from a single spot near ,grignon1 where they are imbedded in a calcareous sand1 chiefly formed of comminuted shells1 in which1 nevertheless1 individuals in a perfect state of preservation1 both of marine1 terrestrial1 and fresh-water species1 are mingled together4 ,some of the marine shells may have lived on the spot2 but the ,cyclostoma and ,limnea1 being land and fresh-water shells1 must have been brought thither by rivers and currents1 and the quantity of triturated shells implies considerable movement in the waters4 ,nothing is more striking in this assemblage of fossil testacea than the great proportion of species referable to the genus ,cerithium 7see p4 #bde74 ,there occur no less than #acg species of this genus in the ,paris basin1 and almost all of them in the calcaire grossier4 ,most of the living ,cerithia inhabit the sea near the mouths of rivers1 where the waters are brackish2 so that their abundance in the marine strata now under consideration is in harmony with the hypothesis that the ,paris basin formed a gulf into which several rivers flowed4 ,in some parts of the calcaire grossier round ,paris1 certain beds occur of a stone used in building1 and called by the ,french geologists 8,miliolite limestone40 ,it is almost entirely made up of millions of microscopic shells1 of the size of minute grains of sand1 which all belong to the class ,foraminifera4 ,examples of some of these are given in ,figs4 #bai to #bba4 ,as this miliolitic stone never occurs in the ,faluns1 or ,upper ,miocene strata of ,brittany and ,touraine1 it often furnishes the geologist with a useful criterion for distinguishing the detached ,eocene and ,upper ,miocene formations scattered over those and other adjoining provinces4 ,the discovery of the remains of ,palotherium and other mammalia in some of the upper beds of the calcaire grossier shows that these land animals began to exist before the deposition of the overlying gypseous series had commenced4 ,fig4 #bai3 ,calcarina rarispina1 ,fig4 #bbj3 ,spirolina stenostoma1 ,fig4 #bba3 ,triloculina inflata4 ,lower ,calcaire grossier1 or ,glauconie grossiere1 ,b4#a1 ,table--,the lower part of the calcaire grossier1 which often contains much green earth1 is characterised at ,auvers1 near ,pontoise1 to the north of ,paris1 and still more in the environs of ,compigne1 by the abundance of nummulites1 consisting chiefly of ,n4 lvigata1 ,n4 scabra1 and ,n4 ,lamarcki1 which constitute a large proportion of some of the stony strata1 though these same foraminifera are wanting in beds of similar age in the immediate environs of ,paris4 ,fig4 #bbb3 ,nerita conoidea4 ,soissonnais sands1 or ,lits coquilliers1 ,b4#b1 ,table--,below the preceding formation1 shelly sands are seen1 of considerable thickness1 especially at ,cuisse-,lamotte1 near ,compigne1 and other localities in the ,soissonnais1 about fifty miles ,n4,e4 of ,paris1 from which about #cjj species of shells have been obtained1 many of them common to the calcaire grossier and the ,bracklesham beds of ,england1 and many peculiar4 ,the ,nummulites planulata is very abundant1 and the most characteristic shell is the ,nerita conoidea1 ,lam41 a fossil which has a very wide geographical range2 for1 as ,m4 d',archiac remarks1 it accompanies the nummulitic formation from ,europe to ,india1 having been found in ,cutch1 near the mouths of the ,indus1 associated with ,nummulites scabra4 ,no less than #cc shells of this group are said to be identical with shells of the ,london clay proper1 yet1 after visiting ,cuisse-,lamotte and other localities of the 8,sables infrieurs0 of ,archiac1 ,i agree with ,mr4 ,prestwich1 that the latter are probably newer than the ,london clay1 and perhaps older than the ,bracklesham beds of ,england4 ,the ,london clay seems to be unrepresented in the ,paris basin1 unless partially so1 by these sands4#i ,,lower ,,eocene ,,formations ,,of ,,france4 ,argile ,plastique1 ,c4#b1 ,table--,at the base of the tertiary system in ,france are extensive deposits of sands1 with occasional beds of clay used for pottery1 and called 8argile plastique40 ,fossil oysters 7,ostrea bellovacina7 abound in some places1 and in others there is a mixture of fluviatile shells1 such as ,cyrena cuneiformis 7,fig4 #baf71 ,melania inquinata 7,fig4 #baf71 and others1 frequently met with in beds occupying the same position in the ,london ,basin4 ,layers of lignite also accompany the inferior clays and sands4 ,immediately upon the chalk at the bottom of all the tertiary strata in ,france there generally is a conglomerate or breccia of rolled and angular chalk-flints1 cemented by siliceous sand4 ,these beds appear to be of littoral origin1 and imply the previous emergence of the chalk1 and its waste by denudation4 ,in the year #ahee1 the tibia and femur of a large bird equalling at least the ostrich in size were found at ,meudon1 near ,paris1 at the base of the ,plastic clay4 ,this bird1 to which the name of ,gastornis ,parisiensis has been assigned1 appears1 from the ,memoirs of ,,mm4 ,hbert1 ,lartet1 and ,owen1 to belong to an extinct genus4 ,professor ,owen refers it to the class of wading land birds rather than to an aquatic species4#aj ,that a formation so much explored for economical purposes as the ,argile plastique around ,paris1 and the clays and sands of corresponding age near ,london1 should never have afforded any vestige of a feathered biped previously to the year #ahee1 shows what diligent search and what skill in osteological interpretation are required before the existence of birds of remote ages can be established4 ,sables de ,bracheux1 ,c4#c1 ,table--,the marine sands called the ,sables de ,bracheux 7a place near ,beauvais71 are considered by ,m4 ,hbert to be older than the ,lignites and ,plastic clay1 and to coincide in age with the ,thanet ,sands of ,england4 ,at ,la ,fre1 in the ,department of ,aisne1 in a deposit of this age1 a fossil skull has been found of a quadruped called by ,blainville ,arctocyon primvus1 and supposed by him to be related both to the bear and to the ,kinkajou 7,cercoleptes74 ,this creature appears to be the oldest known tertiary mammifer4 ,nummulitic ,formations of ,europe1 ,asia1 etc4--,of all the rocks of the ,eocene period1 no formations are of such great geographical importance as the ,upper and ,middle ,eocene1 as above defined1 assuming that the older tertiary formation1 commonly called nummulitic1 is correctly ascribed to this group4 ,it appears that of more than fifty species of these foraminifera described by ,d',archiac1 one or two species only are found in other tertiary formations whether of older or newer date4 ,nummulites intermedia1 a ,middle ,eocene form1 ascends into the ,lower ,miocene1 but it seems doubtful whether any species descends to the level of the ,london clay1 still less to the ,argile plastique or ,woolwich beds4 ,separate groups of strata are often characterised by distinct species of nummulite2 thus the beds between the lower ,miocene and the lower ,eocene may be divided into three sections1 distinguished by three different species of nummulites1 ,n4 variolaria in the upper1 ,n4 lvigata in the middle1 and ,n4 planulata in the lower beds4 ,the nummulitic limestone of the ,swiss ,alps rises to more than #aj1jjj feet above the level of the sea1 and attains here and in other mountain chains a thickness of several thousand feet4 ,it may be said to play a far more conspicuous part than any other tertiary group in the solid framework of the earth's crust1 whether in ,europe1 ,asia1 or ,africa4 ,it occurs in ,algeria and ,morocco1 and has been traced from ,egypt1 where it was largely quarried of old for the building of the ,pyramids1 into ,asia ,minor1 and across ,persia by ,bagdad to the mouths of the ,indus4 ,it has been observed not only in ,cutch1 but in the mountain ranges which separate ,scinde from ,persia1 and which form the passes leading to ,caboul2 and it has been followed still farther eastward into ,india1 as far as eastern ,bengal and the frontiers of ,china4 ,dr4 ,t4 ,thompson found nummulites at an elevation of no less than #af1ejj feet above the level of the sea1 in ,western ,thibet4 ,one of the species1 which ,i myself found very abundant on the flanks of the ,pyrenees1 in a compact crystalline marble 7,fig4 #bbc7 is called by ,m4 d',archiac ,nummulites ,puschi4 ,the same is also very common in rocks of the same age in the ,carpathians4 ,in many distant countries1 in ,cutch1 for example1 some of the same shells1 such as ,nerita conoidea 7,fig4 #bbb71 accompany the nummulites1 as in ,france4 ,the opinion of many observers1 that the ,nummulitic formation belongs partly to the cretaceous era1 seems chiefly to have arisen from confounding an allied genus1 ,orbitoides1 with the true ,nummulite4 ,fig4 #bbc3 ,nummulites ,puschi4 ,when we have once arrived at the conviction that the nummulitic formation occupies a middle and upper place in the ,eocene series1 we are struck with the comparatively modern date to which some of the greatest revolutions in the physical geography of ,europe1 ,asia1 and ,northern ,africa must be referred4 ,all the mountain-chains1 such as the ,alps1 ,pyrenees1 ,carpathians1 and ,himalayas1 into the composition of whose central and loftiest parts the nummulitic strata enter bodily1 could have had no existence till after the ,middle ,eocene period4 ,during that period the sea prevailed where these chains now rise1 for nummulites and their accompanying testacea were unquestionably inhabitants of salt water4 ,before these events1 comprising the conversion of a wide area from a sea to a continent1 ,england had been peopled1 as ,i before pointed out 7p4 #bfg71 by various quadrupeds1 by herbivorous pachyderms1 by insectivorous bats1 and by opossums4 ,almost all the volcanoes which preserve any remains of their original form1 or from the craters of which lava streams can be traced1 are more modern than the ,eocene fauna now under consideration2 and besides these superficial monuments of the action of heat1 ,plutonic influences have worked vast changes in the texture of rocks within the same period4 ,some members of the nummulitic and overlying tertiary strata called flysch have actually been converted in the central ,alps into crystalline rocks1 and transformed into marble1 quartz-rock1 micha-schist1 and gneiss4#aa ,eocene ,strata in the ,united ,states4--,in ,north ,america the ,eocene formations occupy a large area bordering the ,atlantic1 which increases in breadth and importance as it is traced southward from ,delaware and ,maryland to ,georgia and ,alabama4 ,they also occur in ,louisiana and other ,states both east and west of the valley of the ,mississippi4 ,at ,claiborne1 in ,alabama1 no less than #djj species of marine shells1 with many echinoderms and teeth of fish1 characterise one member of this system4 ,among the shells1 the ,cardita planicosta1 before mentioned 7,fig4 #aia71 is in abundance2 and this fossil and some others identical with ,european species1 or very nearly allied to them1 make it highly probable that the ,claiborne beds agree in age with the central or ,bracklesham group of ,england1 and with the calcaire grossiere of ,paris4#ab ,higher in the series is a remarkable calcareous rock1 formerly called 8the nummulite limestone10 from the great number of discoid bodies resembling nummulites which it contains1 fossils now referred by ,a4 d',orbigny to the genus ,orbitoides1 which has been demonstrated by ,dr4 ,carpenter to belong to the foraminifera4#ac ,that naturalist1 moreover1 is of opinion that the ,orbitoides alluded to 7,o4 ,mantelli7 is of the same species as one found in ,cutch1 in the ,middle ,eocene or nummulitic formation of ,india4 ,above the orbitoidal limestone is a white limestone1 sometimes soft and argillaceous1 but in parts very compact and calcareous4 ,it contains several peculiar corals1 and a large ,nautilus allied to ,n4 ziczac2 also in its upper bed a gigantic cetacean1 called ,zeuglodon by ,owen4#ad ,the colossal bones of this cetacean are so plentiful in the interior of ,clarke ,county1 ,alabama1 as to be characteristic of the formation4 ,the vertebral column of one skeleton found by ,dr4 ,buckley at a spot visited by me1 extended to the length of nearly seventy feet1 and not far off part of another backbone nearly fifty feet long was dug up4 ,i obtained evidence1 during a short excursion1 of so many localities of this fossil animal within a distance of ten miles1 as to lead me to conclude that they must have belonged to at least forty distinct individuals4 ,professor ,owen first pointed out that this huge animal was not reptilian1 since each tooth was furnished with double roots 7,fig4 #bbd71 implanted in corresponding double sockets2 and his opinion of the cetacean nature of the fossil was afterwards confirmed by ,dr4 ,wyman and ,dr4 ,r4 ,w4 ,gibbes4 ,that it was an extinct mammal of the whale tribe has since been placed beyond all doubt by discovery of the entire skull of another fossil species of the same family1 having the double occipital condyles only met with in mammals1 and the convoluted tympanic bones which are characteristic of cetaceans4 ,fig4 #bbd3 ,zeuglodon cetoides1 ,fig #bbe3 ,basilosaurus4 #a ,quart4 ,geol4 ,journal1 vol4 xx1 p4 #ig1 #ahfd4 #b ,palont4 ,soc4 ,monograph1 ,rept41 pt4 ii1 p4 #fa4 #c ,heer1 ,climat et ,vgtation du ,pays ,tertiaire1 p4 #agb4 #d ,bowerbank1 ,fossil ,fruits and ,seeds of ,london ,clay1 ,plates ix and x4 #e ,prestwich1 ,quart4 ,geol4 ,journ41 vol4 x4 #f ,second ,visit to the ,united ,states1 vol4 ii1 p4 #ajd4 #g ,cuvier1 ,oss4 ,foss41 tome iii1 p4 #bee4 #h ,sur des ,empreintes de ,pas d',animaux par ,m4 ,j4 ,desnoyers4 ,compte rendu de l',institut1 #ahei4 #i ,d',archiac1 ,bulletin1 tome x2 and ,prestwich1 ,quart4 ,geol4 ,journ41 #ahdg1 p4 #cgg4 #aj ,quart4 ,geol4 ,journ41 vol4 xii1 p4 #bjd1 #ahef4 #aa ,murchison1 ,quart4 ,journ4 of ,geol4 ,soc41 vol4 v1 and ,lyell1 vol4 vi1 #ahej4 ,anniversary ,address4 #ab ,see paper by the ,author1 ,quart4 ,journ4 of ,geol4 ,soc41 vol4 iv1 p4 #ab2 and ,second ,visit to the ,united ,states1 vol4 ii1 p4 #ei4 #ac ,quart4 ,journ4 of ,geol4 ,soc41 vol4 vi1 p4 #cb4 #ad ,see ,memoir by ,r4 ,w4 ,gibbes1 ,journ4 of ,acad4 ,nat4 ,sci4 ,philad41 vol4 i1 #ahdg4 ,,chapter ,,xvii4 ,,upper ,,cretaceous ,,group4 ,lapse of ,time between ,cretaceous and ,eocene ,periods4 -- ,table of successive ,cretaceous ,formations4 -- ,maestricht ,beds4 -- ,pisolitic ,limestone of ,france4 -- ,chalk of ,faxoe4 -- ,geographical ,extent and ,origin of the ,white ,chalk4 -- ,chalky ,matter now forming in the ,bed of the ,atlantic4 -- ,marked ,difference between the ,cretaceous and existing ,fauna4 -- ,chalk-flints4 -- ,pot-stones of ,horstead4 -- ,vitreous ,sponges in the ,chalk4 -- ,isolated ,blocks of ,foreign ,rocks in the ,white ,chalk supposed to be ice-borne4 -- ,distinctness of ,mineral ,character in contemporaneous ,rocks of the ,cretaceous ,epoch4 -- ,fossils of the ,white ,chalk4 -- ,lower ,white ,chalk without ,flints4 -- ,chalk ,marl and its ,fossils4 -- ,chloritic ,series or ,upper ,greensand4 -- ,coprolite ,bed near ,cambridge4 -- ,fossils of the ,chloritic ,series4 -- ,gault4 -- ,connection between ,upper and ,lower ,cretaceous ,strata4 -- ,blackdown ,beds4 -- ,flora of the ,upper ,cretaceous ,period4 -- ,hippurite ,limestone4 -- ,cretaceous ,rocks in the ,united ,states4 ,we have treated in the preceding chapters of the ,tertiary or ,cainozoic strata1 and have next to speak of the ,secondary or ,mesozoic formations4 ,the uppermost of these last is commonly called the chalk or the cretaceous formation1 from creta1 the latin name for that remarkable white earthy limestone1 which constitutes an upper member of the group in those parts of ,europe where it was first studied4 ,the marked discordance in the fossils of the tertiary1 as compared with the cretaceous formations1 has long induced many geologists to suspect that an indefinite series of ages elapsed between the respective periods of their origin4 ,measured1 indeed1 by such a standard1 that is to say1 by the amount of change in the ,fauna and ,flora of the earth effected in the interval1 the time between the ,cretaceous and ,eocene may have been as great as that between the ,eocene and ,recent periods1 to the history of which the last seven chapters have been devoted4 ,several deposits have been met with here and there1 in the course of the last half century1 of an age intermediate between the white chalk and the plastic clays and sands of the ,paris and ,london districts1 monuments which have the same kind of interest to a geologist which certain medieval records excite when we study the history of nations4 ,for both of them throw light on ages of darkness1 preceded and followed by others of which the annals are comparatively well-known to us4 ,but these newly-discovered records do not fill up the wide gap1 some of them being closely allied to the ,eocene1 and others to the ,cretaceous type1 while none appear as yet to possess so distinct and characteristic a fauna as may entitle them to hold an independent place in the great chronological series4 ,among the formations alluded to1 the ,thanet ,sands of ,prestwich have been sufficiently described in the last chapter1 and classed as ,lower ,eocene4 ,to the same tertiary series belong the ,belgian formations1 called by ,professor ,dumont1 ,landenian4 ,on the other hand1 the ,maestricht and ,faxoe limestones are very closely connected with the chalk1 to which also the ,pisolitic limestone of ,france is referable4 ,classification of the ,cretaceous ,rocks4--,the cretaceous group has generally been divided into an ,upper and a ,lower series1 the ,upper called familiarly the chalk1 and the ,lower the greensand2 the one deriving its name from the predominance of white earthy limestone and marl1 of which it consists in a great part of ,france and ,england1 the other or lower series from the plentiful mixture of green or chloritic grains contained in some of the sands and cherts of which it largely consists in the same countries4 ,but these mineral characters often fail1 even when we attempt to follow out the same continuous subdivisions throughout a small portion of the north of ,europe1 and are worse than valueless when we desire to apply them to more distant regions4 ,it is only by aid of the organic remains which characterise the successive marine subdivisions of the formation that we are able to recognise in remote countries1 such as the south of ,europe or ,north ,america1 the formations which were there contemporaneously in progress4 ,to the ,english student of geology it will be sufficient to begin by enumerating those groups which characterise the series in this country and others immediately contiguous1 alluding but slightly to those of more distant regions4 ,in the table 7p4 #bhc7 it will be seen that ,i have used the term ,neocomian for that commonly called 8,lower ,greensand20 as this latter term is peculiarly objectionable1 since the green grains are an exception to the rule in many of the members of this group even in districts where it was first studied and named4 ,,upper ,,cretaceous ,,or ,,chalk ,,period4 ,maestricht ,beds and ,faxoe ,limestone4 ,upper ,white ,chalk1 with flints4 ,lower ,white ,chalk1 without flints4 ,chalk ,marl4 ,chloritic series 7or ,upper ,greensand74 ,gault4 ,,lower ,,cretaceous ,,or ,,neocomian4 ,marine ,fresh-water ,marine3 ,upper ,neocomian1 see p4#cjh ,marine3 ,middle ,neocomian1 see p4#cab ,marine3 ,lower ,neocomian1 see p4#cab ,wealden ,beds 7upper part74 ,belemnitella mucronata4 ,belemnitella mucronata1 ,maestricht1 ,faxoe1 and ,white ,chalk4 a_/ ,entire specimen1 showing vascular impression on outer surface1 and characteristic slit4 b4 ,section of same1 showing place of phragmocone4#a ,maestricht ,beds4--,on the banks of the ,meuse1 at ,maestricht1 reposing on ordinary white chalk with flints1 we find an upper calcareous formation about #ajj feet thick1 the fossils of which are1 on the whole1 very peculiar1 and all distinct from tertiary species4 ,some few are of species common to the inferior white chalk1 among which may be mentioned ,belemnitella mucronata 7,fig4 #bbf7 and ,pecten quadricostatus1 a shell regarded by many as a mere variety of ,p4 quinquecostatus 7see ,fig4 #bgj74 ,besides the ,belemnite there are other genera1 such as ,baculites and ,hamites1 never found in strata newer than the cretaceous1 but frequently met with in these ,maestricht beds4 ,on the other hand1 ,voluta1 ,fasciolaria1 and other genera of univalve shells1 usually met with only in tertiary strata1 occur4 ,the upper part of the rock1 about #bj feet thick1 as seen in ,st4 ,peter's ,mount1 in the suburbs of ,maestricht1 abounds in corals and ,bryozoa1 often detachable from the matrix2 and these beds are succeeded by a soft yellowish limestone #ej feet thick1 extensively quarried from time immemorial for building4 ,the stone below is whiter1 and contains occasional nodules of grey chert or chalcedony4 ,m4 ,bosquet1 with whom ,i examined this formation 7,august1 #ahej71 pointed out to me a layer of chalk from two to four inches thick1 containing green earth and numerous encrinital stems1 which forms the line of demarkation between the strata containing the fossils peculiar to ,maestricht and the white chalk below4 ,the latter is distinguished by regular layers of black flint in nodules1 and by several shells1 such as ,terebratula carnea 7see ,fig4 #bdf71 wholly wanting in beds higher than the green band4 ,some of the organic remains1 however1 for which ,st4 ,peter's ,mount is celebrated1 occur both above and below that parting layer1 and1 among others1 the great marine reptile called ,mosasaurus 7see ,fig4 #bbg71 a saurian supposed to have been #bd feet in length1 of which the entire skull and a great part of the skeleton have been found4 ,such remains are chiefly met with in the soft freestone1 the principal member of the ,maestricht beds4 ,among the fossils common to the ,maestricht and white chalk may be instanced the echinoderm1 ,fig4 #bbh4 ,mosasaurus ,camperi4 ,hemipneustes radiatus4 ,i saw proofs of the previous denudation of the white chalk exhibited in the lower bed of the ,maestricht formation in ,belgium1 about #cj miles ,s4,w4 of ,maestricht1 at the village of ,jendrain1 where the base of the newer deposit consisted chiefly of a layer of well-rolled1 black chalk-flint pebbles1 in the midst of which perfect specimens of ,thecidea papillata and ,belemnitella mucronata are imbedded4 ,to a geologist accustomed in ,england to regard rolled pebbles of chalk-flint as a common and distinctive feature of tertiary beds of different ages1 it is a new and surprising phenomenon to behold strata made up of such materials1 and yet to feel no doubt that they were accumulated in a sea in which the belemnite and other cretaceous mollusca flourished4 ,pisolitic ,limestone of ,france4--,geologists were for many years at variance respecting the chronological relations of this rock1 which is met with in the neighbourhood of ,paris1 and at places north1 south1 east1 and west of that metropolis1 as between ,vertus and ,laversines1 ,meudon and ,montereau4 ,by many able palontologists the species of fossils1 more than fifty in number1 were declared to be more ,eocene in their appearance than ,cretaceous4 ,but ,m4 ,hbert found in this formation at ,montereau1 near ,paris1 the ,pecten quadricostatus1 a well-known ,cretaceous species1 together with some other fossils common to the ,maestricht chalk and to the ,baculite limestone of the ,cotentin1 in ,normandy4 ,he therefore1 as well as ,m4 ,alcide d',orbigny1 who had carefully studied the fossils1 came to the opinion that it was an upper member of the ,cretaceous group4 ,it is usually in the form of a coarse yellowish or whitish limestone1 and the total thickness of the series of beds already known is about #ajj feet4 ,its geographical range1 according to ,m4 ,hbert1 is not less than #de leagues from east to west1 and #ce from north to south4 ,within these limits it occurs in small patches only1 resting unconformably on the white chalk4 ,the ,nautilus ,danicus1 ,fig4 #bcj1 and two or three other species found in this rock1 are frequent in that of ,faxoe1 in ,denmark1 but as yet no ,ammonites1 ,hamites1 ,scaphites1 ,turrilites1 ,baculites1 or ,hippurites have been met with4 ,the proportion of peculiar species1 many of them of tertiary aspect1 is confessedly large2 and great aqueous erosion suffered by the white chalk1 before the pisolitic limestone was formed1 affords an additional indication of the two deposits being widely separated in time4 ,the pisolitic formation1 therefore1 may eventually prove to be somewhat more intermediate in date between the secondary and tertiary epochs than the ,maestricht rock4 ,chalk of ,faxoe4-- ,in the island of ,seeland1 in ,denmark1 the newest member of the chalk series1 seen in the sea-cliffs at ,stevensklint resting on white chalk with flints1 is a yellow limestone1 a portion of which1 at ,faxoe1 where it is used as a building stone1 is composed of corals1 even more conspicuously than is usually observed in recent coral reefs4 ,it has been quarried to the depth of more than #dj feet1 but its thickness is unknown4 ,the imbedded shells are chiefly casts1 many of them of univalve mollusca1 which are usually very rare in the white chalk of ,europe4 ,thus1 there are two species of ,cypra1 one of ,oliva1 two of ,mitra1 four of the genus ,cerithium1 six of ,fusus1 two of ,trochus1 one of ,patella1 one of ,emarginula1 etc42 on the whole1 more than thirty univalves1 spiral or patelliform4 ,at the same time1 some of the accompanying bivalve shells1 echinoderms1 and zoophytes1 are specifically identical with fossils of the true ,cretaceous series4 ,among the cephalopoda of ,faxoe may be mentioned ,baculites ,faujasii 7,fig4 #bbi71 and ,belemnitella mucronata 7,fig4 #bbf71 shells of the white chalk4 ,the ,nautilus ,danicus 7see ,fig4 #bcj7 is characteristic of this formation2 and it also occurs in ,france in the calcaire pisolitique of ,laversin 7,department of ,oise74 ,the claws and entire skull of a small crab1 ,brachyurus rugosus 7,schlott471 are scattered through the ,faxoe stone1 reminding us of similar crustaceans inclosed in the rocks of modern coral reefs4 ,some small portions of this coralline formation consist of white earthy chalk4 ,fig4 #bbi3 ,portion of ,baculites ,faujasii1 ,fig4 #bcj3 ,nautilus ,danicus4 ,composition1 ,extent and ,origin of the ,white ,chalk4--,the highest beds of chalk in ,england and ,france consist of a pure1 white1 calcareous mass1 usually too soft for a building-stone1 but sometimes passing into a more solid state4 ,it consists1 almost purely1 of carbonate of lime2 the stratification is often obscure1 except where rendered distinct by interstratified layers of flint1 a few inches thick1 occasionally in continuous beds1 but oftener in nodules1 and recurring at intervals generally from two to four feet distant from each other4 ,this upper chalk is usually succeeded1 in the descending order1 by a great mass of white chalk without flints1 below which comes the chalk marl1 in which there is a slight admixture of argillaceous matter4 ,the united thickness of the three divisions in the south of ,england equals1 in some places1 #ajjj feet4 ,the section in ,fig4 #bca will show the manner in which the white chalk extends from ,england into ,france1 covered by the tertiary strata described in former chapters1 and reposing on lower cretaceous beds4 ,the area over which the white chalk preserves a nearly homogeneous aspect is so vast1 that the earlier geologists despaired of discovering any analogous deposits of recent date4 ,pure chalk1 of nearly uniform aspect and composition1 is met with in a north-west and south-east direction1 from the north of ,ireland to the ,crimea1 a distance of about #aadj geographical miles1 and in an opposite direction it extends from the south of ,sweden to the south of ,bordeaux1 a distance of about #hdj geographical miles4 ,in ,southern ,russia1 according to ,sir ,r4 ,murchison1 it is sometimes #fjj feet thick1 and retains the same mineral character as in ,france and ,england1 with the same fossils1 including ,inoceramus ,cuvieri1 ,belemnitella mucronata1 and ,ostrea vesicularis 7,fig4 #bea74 ,diagrammatic section from ,hertfordshire1 in ,england1 to ,sens1 in ,france4 ,great light has recently been thrown upon the origin of the unconsolidated white chalk by the deep soundings made in the ,north ,atlantic1 previous to laying down1 in #aheh1 the electric telegraph between ,ireland and ,newfoundland4 ,at depths sometimes exceeding two miles1 the mud forming the floor of the ocean was found1 by ,professor ,huxley1 to be almost entirely composed 7more than nineteen-twentieths of the whole7 of minute ,rhizopods1 or foraminiferous shells of the genus ,globigerina1 especially the species ,globigerina bulloides 7see ,fig4 #bcb47 the organic bodies next in quantity were the siliceous shells called ,polycystine1 and next to them the siliceous skeletons of plants called ,diatomace 7,figs4 #bcc1 #bcd1 #bce71 and occasionally some siliceous spicul of sponges 7,fig4 #bcf7 were intermixed4 ,these were connected by a mass of living gelatinous matter to which he has given the name of ,bathybius1 and which contains abundance of very minute bodies termed ,coccoliths and ,coccospheres1 which have also been detected fossil in chalk4 ,sir ,leopold ,mac,clintock and ,dr4 ,wallich have ascertained that #ie per cent of the mud of a large part of the ,north ,atlantic consists of ,globigerina shells4 ,but ,captain ,bullock1 ,r4,n41 lately brought up from the enormous depth of #af1hfj feet a white1 viscid1 chalky mud1 wholly devoid of ,globigerin4 ,this mud was perfectly homogeneous in composition1 and contained no organic remains visible to the naked eye4 ,mr4 ,etheridge1 however1 has ascertained by microscopical examination that it is made up of ,coccoliths1 ,discoliths1 and other minute fossils like those of the ,chalk classed by ,huxley as ,bathybius1 when this term is used in its widest sense4 ,this mud1 more than three miles deep1 was dredged up in latitude #bj #ai ,n41 longitude #d #cf ,e41 or about midway between ,madeira and the ,cape of ,good ,hope4 ,fig4 #bcb3 ,globigerina bulloides1 ,calcareous ,rhizopod4 ,fig4 #bcc3 ,actinocyclus1 ,fig4 #bcd3 ,pinnularia1 ,fig4 #bce3 ,eunotia bidens1 ,siliceous ,diatomace4 ,fig4 #bcf3 ,spicula of sponge1 ,siliceous sponge4 ,the recent deep-sea dredgings in the ,atlantic conducted by ,dr4 ,wyville ,thomson1 ,dr4 ,carpenter1 ,mr4 ,gwyn ,jeffreys1 and others1 have shown that on the same white mud there sometimes flourish ,mollusca1 ,crustacea1 and ,echinoderms1 besides abundance of siliceous sponges1 forming1 on the whole1 a marine fauna bearing a striking resemblance in its general character to that of the ancient chalk4 ,popular ,error as to the ,geological ,continuity of the ,cretaceous ,period4--,we must be careful1 however1 not to overrate the points of resemblance which the deep-sea investigations have placed in a strong light4 ,they have been supposed by some naturalists to warrant a conclusion expressed in these words3 8,we are still living in the ,cretaceous epoch20 a doctrine which has led to much popular delusion as to the bearing of the new facts on geological reasoning and classification4 ,the reader should be reminded that in geology we have been in the habit of founding our great chronological divisions1 not on foraminifera and sponges1 nor even on echinoderms and corals1 but on the remains of the most highly organised beings available to us1 such as the mollusca2 these being met with1 as explained 7p4 #adb71 in stratified rocks of almost every age4 ,in dealing with the mollusca1 it is those of the highest or most specialised organisation1 which afford us the best characters in proportion as their vertical range is the most limited4 ,thus the ,cephalopoda are the most valuable1 as having a more restricted range in time than the ,gasteropoda2 and these1 again1 are more characteristic of the particular stratigraphical subdivisions than are the ,lamellibranchiate ,bivalves1 while these last1 again1 are more serviceable in classification than the ,brachiopoda1 a still lower class of shell-fish1 which are the most enduring of all4 ,when told that the new dredgings prove that 8we are still living in the ,chalk ,period10 we naturally ask whether some cuttle-fish has been found with a ,belemnite forming part of its internal framework2 or have ,ammonites1 ,baculites1 ,hamites1 ,turrilites1 with four or five other ,cephalopodous genera characteristic of the chalk and unknown as tertiary1 been met with in the abysses of the ocean8 ,or1 in the absence of these long-extinct forms1 has a single spiral univalve1 or species of ,cretaceous ,gasteropod1 been found living8 ,or1 to descend still lower in the scale1 has some characteristic ,cretaceous genus of ,lamellibranchiate ,bivalve1 such as the ,inoceramus1 or ,hippurite1 foreign to the ,tertiary seas1 been proved to have survived down to our time8 ,or1 of the numerous genera of lamellibranchiates common to the ,cretaceous and ,recent seas1 has one species been found living8 ,the answer to all these questions is--not one has been found4 ,even of the humblest shell-fish1 the ,brachiopods1 no new species common to the ,cretaceous and recent seas has yet been met with4 ,it has been very generally admitted by conchologists that out of a hundred species of this tribe occurring fossil in the ,upper ,chalk--one1 and one only1 ,terebratulina striata1 is still living1 being thought to be identical with ,terebratula caput-serpentis4 ,although this identity is still questioned by some naturalists of authority1 it would certainly not surprise us if another lamp-shell of equal antiquity should be met with in the deep sea4 ,had it been declared that we are living in the ,eocene epoch1 the idea would not be so extravagant1 for the great reptiles of the ,upper ,chalk1 the ,mosasaurus1 ,pliosaurus1 and ,pterodactyle1 and many others1 as well as so many genera of chambered univalves1 had already disappeared from the earth1 and the marine fauna had made a greater approach to our own by nearly the entire difference which separates it from the fauna of the ,cretaceous seas4 ,the ,eocene nummulitic limestone of ,egypt is a rock mainly composed1 like the more ancient white chalk1 of globigerine mud2 and if the reader will refer to what we have said of the extent to which the nummulitic marine strata1 formed originally at the bottom of the sea1 now enter into the frame-work of mountain chains of the principal continents1 he will at once perceive that the present ,atlantic1 ,pacific1 and ,indian ,oceans are geographical terms1 which must be wholly without meaning when applied to the ,eocene1 and still more to the ,cretaceous ,period2 so that to talk of the chalk having been uninterruptedly forming in the ,atlantic from the ,cretaceous ,period to our own1 is as inadmissible in a geographical as in a geological sense4 ,chalk-flints4--,the origin of the layers of flint1 whether in the form of nodules1 or continuous sheets1 or in veins or cracks not parallel to the stratification1 has always been more difficult to explain than that of the white chalk4 ,but here1 again1 the late deep-sea soundings have suggested a possible source of such mineral matter4 ,during the cruise of the 8,bulldog10 already alluded to1 it was ascertained that while the calcareous ,globigerin had almost exclusive possession of certain tracts of the sea-bottom1 they were wholly wanting in others1 as between ,greenland and ,labrador4 ,according to ,dr4 ,wallich1 they may flourish in those spaces where they derive nutriment from organic and other matter1 brought from the south by the warm waters of the ,gulf ,stream1 and they may be absent where the effects of that great current are not felt4 ,now1 in several of the spaces where the calcareous ,rhizopods are wanting1 certain microscopic plants1 called ,diatomace1 above mentioned 7,figs4 #bcc-bce71 the solid parts of which are siliceous1 monopolise the ground at a depth of nearly #djj fathoms1 or #bdjj feet4 ,the large quantities of silex in solution required for the formation of these plants may probably arise from the disintegration of feldspathic rocks1 which are universally distributed4 ,as more than half of their bulk is formed of siliceous earth1 they may afford an endless supply of silica to all the great rivers which flow into the ocean4 ,we may imagine that1 after a lapse of many years or centuries1 changes took place in the direction of the marine currents1 favouring at one time a supply in the same area of siliceous1 and at another of calcareous matter in excess1 giving rise in the one case to a preponderance of ,globigerin1 and in the other of ,diatomace4 ,these last1 and certain sponges1 may by their decomposition have furnished the silex1 which1 separating from the chalky mud1 collected round organic bodies1 or formed nodules1 or filled shrinkage cracks4 ,pot-stones4--,a more difficult enigma is presented by the occurrence of certain huge flints1 or pot-stones1 as they are called in ,norfolk1 occurring singly1 or arranged in nearly continuous columns at right angles to the ordinary and horizontal layers of small flints4 ,i visited in the year #ahbe an extensive range of quarries then open on the river ,bure1 near ,horstead1 about six miles from ,norwich1 which afforded a continuous section1 a quarter of a mile in length1 of white chalk1 exposed to the depth of about twenty-six feet1 and covered by a bed of gravel4 ,the pot-stones1 many of them pear-shaped1 were usually about three feet in height and one foot in their transverse diameter1 placed in vertical rows1 like pillars1 at irregular distances from each other1 but usually from twenty to thirty feet apart1 though sometimes nearer together1 as in ,figure #bcg4 ,these rows did not terminate downward in any instance which ,i could examine1 nor upward1 except at the point where they were cut off abruptly by the bed of gravel4 ,on breaking open the pot-stones1 ,i found an internal cylindrical nucleus of pure chalk1 much harder than the ordinary surrounding chalk1 and not crumbling to pieces like it1 when exposed to the winter's frost4 ,at the distance of half a mile1 the vertical piles of pot-stones were much farther apart from each other4 ,dr4 ,buckland has described very similar phenomena as characterising the white chalk on the north coast of ,antrim1 in ,ireland4#b ,view of a chalk-pit at ,horstead1 near ,norwich1 showing the position of the pot-stones4 ,vitreous ,sponges of the ,chalk4--,these pear-shaped masses of flint often resemble in shape and size the large sponges called ,neptune's ,cups 7,spongia patera1 ,hardw471 which grow in the seas of ,sumatra2 and if we could suppose a series of such gigantic sponges to be separated from each other1 like trees in a forest1 and the individuals of each successive generation to grow on the exact spot where the parent sponge died and was enveloped in calcareous mud1 so that they should become piled one above the other in a vertical column1 their growth keeping pace with the accumulation of the enveloping calcareous mud1 a counterpart of the phenomena of the ,horstead pot-stones might be obtained4 ,fig4 #bch3 ,ventriculites radiatus4 ,white chalk4 ,professor ,wyville ,thomson1 describing the modern soundings in #ahfi off the north coast of ,scotland1 speaks of the ooze or chalk mud brought from a depth of about #cjjj feet1 and states that at one haul they obtained forty specimens of vitreous sponges buried in the mud4 ,he suggests that the ,ventriculites of the chalk were nearly allied to these sponges1 and that when the silica of their spicules was removed1 and was dissolved out of the calcareous matrix1 it set into flint4 ,boulders and ,groups of ,pebbles in ,chalk4--,the occurrence here and there1 in the white chalk of the south of ,england1 of isolated pebbles of quartz and green schist has justly excited much wonder4 ,it was at first supposed that they had been dropped from the roots of some floating tree1 by which means stones are carried to some of the small coral islands of the ,pacific4 ,but the discovery in #aheg of a group of stones in the white chalk near ,croydon1 the largest of which was syenite and weighed about forty pounds1 accompanied by pebbles and fine sand like that of a beach1 has been shown by ,mr4 ,godwin ,austen to be inexplicable except by the agency of floating ice4 ,if we consider that icebergs now reach #dj degrees north latitude in the ,atlantic1 and several degrees nearer the equator in the southern hemisphere1 we can the more easily believe that even during the ,cretaceous epoch1 assuming that the climate was milder1 fragments of coast ice may have floated occasionally as far as the south of ,england4 ,distinctness of ,mineral ,character in ,contemporaneous ,rocks of the ,cretaceous ,period4--,but we must not imagine that because pebbles are so rare in the white chalk of ,england and ,france there are no proofs of sand1 shingle1 and clay having been accumulated contemporaneously even in ,european seas4 ,the siliceous sandstone called 8upper quader0 by the ,germans overlies white argillaceous chalk or 8plner-kalk10 a deposit resembling in composition and organic remains the chalk marl of the ,english series4 ,this sandstone contains as many fossil shells common to our white chalk as could be expected in a sea-bottom formed of such different materials4 ,it sometimes attains a thickness of #fjj feet1 and1 by its jointed structure and vertical precipices1 plays a conspicuous part in the picturesque scenery of ,saxon ,switzerland1 near ,dresden4 ,it demonstrates that in the ,cretaceous sea1 as in our own1 distinct mineral deposits were simultaneously in progress4 ,the quartzose sandstone alluded to1 derived from the detritus of the neighbouring granite1 is absolutely devoid of carbonate of lime1 yet it was formed at the distance only of four hundred miles from a sea-bottom now constituting part of ,france1 where the purely calcareous white chalk was forming4 ,in the ,north ,american continent1 on the other hand1 where the ,upper ,cretaceous formations are so widely developed1 true white chalk1 in the ordinary sense of that term1 does not exist4 ,fig4 #bci3 ,ananchytes ovatus4 ,white chalk1 upper and lower4 ,fossils of the ,white ,chalk4--,among the fossils of the white chalk1 echinoderms are very numerous2 and some of the genera1 like ,ananchytes 7see ,fig4 #bci71 are exclusively cretaceous4 ,among the ,crinoidea1 the ,marsupites 7,fig4 #bdb7 is a characteristic genus4 ,among the mollusca1 the cephalopoda are represented by ,ammonites1 ,baculites 7,fig4 #bbi71 and ,belemnites 7,fig4 #bbf74 ,although there are eight or more species of ,ammonites and six of them peculiar to it1 this genus is much less fully represented than in each of the other subdivisions of the ,upper ,cretaceous group4 ,among the brachiopoda in the white chalk1 the ,terebratul are very abundant 7see ,figs4 #bdc-bdg74 ,with these are associated some forms of oyster 7see ,fig4 #bea71 and other bivalves 7,figs4 #bdi1 #bej74 ,fig4 #bdj3 ,micraster cor-angumum4 ,white chalk4 ,fig4 #bda3 ,galerites albogalerus4 ,white chalk4 ,fig4 #bdb3 ,marsupites ,milleri4 ,white chalk4 ,fig4 #bdc3 ,terebratulina striata4 ,upper white chalk4 ,fig4 #bdd3 ,rhynchonella octoplicata4 ,upper white chalk4 ,fig4 #bde3 ,magas pumila4 ,upper white chalk4 ,fig4 #bdf3 ,terebratula carnea4 ,upper white chalk4 ,fig4 #bdg3 ,terebratula biplicata4 ,upper cretaceous4 ,fig4 #bdh3 ,crania ,parisiensis4 ,inferior or attached valve4 ,upper white chalk4 ,fig4 #bdi3 ,peten ,beaveri4 ,lower white chalk and chalk marl4 ,fig4 #bej3 ,lima spinosa4 ,upper white chalk4 ,among the bivalve mollusca1 no form marks the ,cretaceous era in ,europe1 ,america1 and ,india in a more striking manner than the extinct genus ,inoceramus 7,catillus of ,lam42 see ,fig4 #beb71 the shells of which are distinguished by a fibrous texture1 and are often met with in fragments1 having probably been extremely friable4 ,of the singular family called ,rudistes by ,lamarck1 hereafter to be mentioned as extremely characteristic of the chalk of southern ,europe1 a single representative only 7,fig4 #bec7 has been discovered in the white chalk of ,england4 ,fig4 #bea3 ,ostrea vesicularis4 ,upper chalk and upper greensand4 ,fig4 #beb3 ,inoceramus ,lamarckii4 ,white chalk4 ,radiolites ,mortoni1 ,mantell4 ,houghton1 ,sussex4 ,white chalk4 ,diameter one-seventh nat4 size4 ,fig4 #bec4 ,two individuals deprived of their upper valves1 adhering together4 ,fig4 #bed4 ,same seen from above4 ,fig4 #bee4 ,transverse section of part of the wall of the shell1 magnified to show the structure4 ,fig4 #bef4 ,vertical section of the same4 ,on the side where the shell is thinnest1 there is one external furrow and corresponding internal ridge1 a1 b1 figs4 #bee1 #bef2 but they are usually less prominent than in these figures4 ,the upper or opercular valve is wanting4 ,the general absence of univalve mollusca in the white chalk is very marked4 ,of bryozoa there is an abundance1 such as ,eschara and ,escharina 7,figs4 #beg1 #beh74 ,these and other organic bodies1 especially sponges1 such as ,ventriculites 7,fig4 #bch71 are dispersed indifferently through the soft chalk and hard flint1 and some of the flinty nodules owe their irregular forms to inclosed sponges1 such as ,fig4 #bei1 a1 where the hollows in the exterior are caused by the branches of a sponge 7,fig4 #bei1 b71 seen on breaking open the flint4 ,fig4 #beg3 ,eschara disticha4 ,white chalk4 ,fig4 #beh3 ,escharina oceani4 ,white chalk4 ,fig4 #bei3 ,a branching sponge in a flint1 from the white chalk4 ,the remains of fishes of the ,upper ,cretaceous formations consist chiefly of teeth belonging to the shark family4 ,some of the genera are common to the ,tertiary formations1 and some are distinct4 ,to the latter belongs the genus ,ptychodus 7,fig4 #bfj71 which is allied to the living ,port ,jackson shark1 ,cestracion ,phillippi1 the anterior teeth of which 7see ,fig4 #bfa1 a7 are sharp and cutting1 while the posterior or palatal teeth 7b7 are flat 7,fig4 #bfj74 ,but we meet with no bones of land-animals1 nor any terrestrial or fluviatile shells1 nor any plants1 except sea-weeds1 and here and there a piece of drift-wood4 ,all the appearances concur in leading us to conclude that the white chalk was the product of an open sea of considerable depth4 ,fig4 #bfj3 ,palatal tooth of ,ptychodus decurrens4 ,lower white chalk4 ,the existence of turtles and oviparous saurians1 and of a ,pterodactyl or winged lizard1 found in the white chalk of ,maidstone1 implies1 no doubt1 some neighbouring land2 but a few small islets in mid-ocean1 like ,ascension1 formerly so much frequented by migratory droves of turtle1 might perhaps have afforded the required retreat where these creatures laid their eggs in the sand1 or from which the flying species may have been blown out to sea4 ,of the vegetation of such islands we have scarcely any indication1 but it consisted partly of cycadaceous plants2 for a fragment of one of these was found by ,captain ,ibbetson in the ,chalk ,marl of the ,isle of ,wight1 and is referred by ,a4 ,brongniart to ,clathraria ,lyellii1 ,mantell1 a species common to the antecedent ,wealden period4 ,the fossil plants1 however1 of beds corresponding in age to the white chalk at ,aix-la-,chapelle1 presently to be described1 like the sandy beds of ,saxony1 before alluded to 7p4 #bic71 afford such evidence of land as to prove how vague must be any efforts of ours to restore the geography of that period4 ,fig4 #bfa3 ,cestracion ,phillipi2 recent4 ,the ,pterodactyl of the ,kentish chalk1 above alluded to1 was of gigantic dimensions1 measuring #af feet #f inches from tip to tip of its outstretched wings4 ,some of its elongated bones were at first mistaken by able anatomists for those of birds2 of which class no osseous remains have as yet been derived from the white chalk1 although they have been found 7as will be seen on page #bii7 in the ,chloritic sand4 ,the collector of fossils from the white chalk was formerly puzzled by meeting with certain bodies which they call larch-cones1 which were afterwards recognised by ,dr4 ,buckland to be the excrement of fish 7see ,fig4 #bfb74 ,they are composed in great part of phosphate of lime4 ,fig4 #bfb3 ,coprolites of fish1 from the chalk4 ,fig4 #bfc3 ,baculites anceps4 ,lower chalk4 ,fig4 #bfd3 ,ammonites ,rhotomagensis4 ,chalk marl4 ,lower ,white ,chalk4--,the ,lower ,white ,chalk1 which is several hundred feet thick1 without flints1 has yielded #be species of ,ammonites1 of which half are peculiar to it4 ,the genera ,baculite1 ,hamite1 ,scaphite1 ,turrilite1 ,nautilus1 ,belemnite1 and ,belemnitella1 are also represented4 ,chalk ,marl4--,the lower chalk without flints passes gradually downward1 in the south of ,england1 into an argillaceous limestone1 8the chalk marl10 already alluded to4 ,it contains #cb species of ,ammonites1 seven of which are peculiar to it1 while eleven pass up into the overlying lower white chalk4 ,a4 ,rhotomagensis is characteristic of this formation4 ,among the ,british cephalopods of other genera may be mentioned ,scaphites qualis 7,fig4 #bff7 and ,turrilites costatus 7,fig4 #bfe74 ,chloritic ,series 7or ,upper ,greensand74--,according to the old nomenclature1 this subdivision of the chalk was called ,upper ,greensand1 in order to distinguish it from those members of the ,neocomian or ,lower ,cretaceous series below the ,gault to which the name of ,greensand had been applied4 ,besides the reasons before given 7p4 #bhb7 for abandoning this nomenclature1 it is objectionable in this instance as leading the uninitiated to suppose that the divisions thus named ,upper and ,lower ,greensand are of co-ordinate value1 instead of which the chloritic sand is quite a subordinate member of the ,upper ,cretaceous group1 and the term ,greensand has very commonly been used for the whole of the ,lower ,cretaceous rocks1 which are almost comparable in importance to the entire ,upper ,cretaceous series4 ,the higher portion of the ,chloritic series in some districts has been called chloritic marl1 from its consisting of a chalky marl with chloritic grains4 ,in parts of ,surrey1 where calcareous matter is largely intermixed with sand1 it forms a stone called malm-rock or firestone4 ,in the cliffs of the southern coast of the ,isle of ,wight it contains bands of calcareous limestone with nodules of chert4 ,fig4 #bfe3 ,turrilites costatus4 ,lower chalk and chalk marl4 ,fig4 #bff3 ,scaphites qualis4 ,chloritic marl and sand1 ,dorsetshire4 ,coprolite ,bed4--,the so-called coprolite bed1 found near ,farnham1 in ,surrey1 and near ,cambridge1 contains nodules of phosphate of lime in such abundance as to be largely worked for the manufacture of artificial manure4 ,it belongs to the upper part of the ,chloritic series1 and is doubtless chiefly of animal origin1 and may perhaps be partly coprolitic1 derived from the excrement of fish and reptiles4 ,the late ,mr4 ,barrett discovered in it1 near ,cambridge1 in #aheh1 the remains of a bird1 which was rather larger than the common pigeon1 and probably of the order ,natatores1 and which1 like most of the ,gull tribe1 had well-developed wings4 ,portions of the metacarpus1 metatarsus1 tibia1 and femur have been detected1 and the determinations of ,mr4 ,barrett have been confirmed by ,professor ,owen4 ,this phosphatic bed in the suburbs of ,cambridge must have been formed partly by the denudation of pre-existing rocks1 mostly of ,cretaceous age4 ,the fossil shells and bones of animals washed out of these denuded strata1 now forming a layer only a few feet thick1 have yielded a rich harvest to the collector4 ,a large ,rudist of the genus ,radiolite1 no less than two feet in height1 may be seen in the ,cambridge ,museum1 obtained from this bed4 ,the number of reptilian remains1 all apparently of ,cretaceous age1 is truly surprising2 more than ten species of ,pterodactyl1 five or six of ,ichthyosaurus1 one of ,pliosaurus1 one of ,dinosaurus1 eight of ,chelonians1 besides other forms1 having been recognised4 ,the chloritic sand is regarded by many geologists as a littoral deposit of the ,chalk ,ocean1 and therefore contemporaneous with part of the chalk marl1 and even1 perhaps1 with some part of the white chalk4 ,for1 as the land went on sinking1 and the cretaceous sea widened its area1 white mud and chloritic sand were always forming somewhere1 but the line of sea-shore was perpetually shifting its position4 ,hence1 though both sand and mud originated simultaneously1 the one near the land1 the other far from it1 the sands in every locality where a shore became submerged might constitute the underlying deposit4 ,fig4 #bfg3 ,ostrea columba4 ,chloritic sand4 ,fig4 #bfh3 ,ostrea carinata4 ,chalk marl and chloritic sand4 ,among the characteristic mollusca of the chloritic sand may be mentioned ,terebrirostra lyra 7,fig4 #bfi71 ,plagiostoma ,hoperi 7,fig4 #bga71 ,pecten quinque-costatus 7,fig4 #bgj71 and ,ostrea columba 7,fig4 #bfg74 ,fig4 #bfi3 ,terebrirostra lyra4 ,chloritic sand4 ,fig4 #bgj3 ,pecten #e-;costatus4 ,white chalk and chloritic sand4 ,fig4 #bga3 ,plagiostoma ,hoperi4 ,white chalk and chloritic sand4 ,the ,cephalopoda are abundant1 among which #dj species of ,ammonites are now known1 #aj being peculiar to this subdivision1 and the rest common to the beds immediately above or below4 ,gault4--,the lowest member of the ,upper ,cretaceous group1 usually about #ajj feet thick in the ,s4,e4 of ,england1 is provincially termed ,gault4 ,it consists of a dark blue marl1 sometimes intermixed with green sand4 ,many peculiar forms of cephalopoda1 such as the ,hamite 7,fig4 #bgb71 and ,scaphite1 with other fossils1 characterise this formation1 which1 small as is its thickness1 can be traced by its organic remains to distant parts of ,europe1 as1 for example1 to the ,alps4 ,fig4 #bgb3 ,ancyloceras spinigerum4 ,near ,folkestone4 ,twenty-one species of ,british ,ammonites are recorded as found in the ,gault1 of which only eight are peculiar to it1 ten being common to the overlying ,chloritic series4 ,connection between ,upper and ,lower ,cretaceous ,strata4--,blackdown ,beds4--,the break between the ,upper and ,lower ,cretaceous formations will be appreciated when it is stated that1 although the ,neocomian contains #ca species of ,ammonite1 and the ,gault1 as we have seen1 #ba1 there are only three of those common to both divisions4 ,nevertheless1 we may expect the discovery in ,england1 and still more when we extend our survey to the ,continent1 of beds of passage intermediate between the ,upper and ,lower ,cretaceous4 ,even now the ,blackdown beds in ,devonshire1 which rest immediately on ,triassic strata1 and which evidently belong to some part of the ,cretaceous series1 have been referred by some geologists to the ,upper group1 by others to the ,lower or ,neocomian4 ,they resemble the ,folkestone beds of the latter series in mineral character1 and #ei out of #aef of their fossil mollusca are common to them2 but they have also #af species common to the ,gault1 and #bj to the overlying ,chloritic series2 and what is very important1 out of seven ,ammonites six are found also in the ,gault and ,chloritic series1 only one being peculiar to the ,blackdown beds4 ,professor ,ramsay has remarked that there is a stratigraphical break2 for in ,kent1 ,surrey1 and ,sussex1 at those few points where there are exposures of junctions of the ,gault and ,neocomian1 the surface of the latter has been much eroded or denuded1 while to the westward of the great chalk escarpment the unconformability of the two groups is equally striking4 ,at ,blackdown this unconformability is still more marked1 for though distant only #ajj miles from ,kent and ,surrey1 no formation intervenes between these beds and the ,trias2 all intermediate groups1 such as the ,lower ,neocomian and ,oolite1 having either not been deposited or destroyed by denudation4 ,flora of the ,upper ,cretaceous ,period4--,as the ,upper ,cretaceous rocks of ,europe are1 for the most part1 of purely marine origin1 and formed in deep water usually far from the nearest shore1 land-plants of this period1 as we might naturally have anticipated1 are very rarely met with4 ,in the neighbourhood of ,aix-la-,chapelle1 however1 an important exception occurs1 for there certain white sands and laminated clays1 #djj feet in thickness1 contain the remains of terrestrial plants in a beautiful state of preservation4 ,these beds are the equivalents of the white chalk and chalk marl of ,england1 or ,senonien of d',orbigny1 although the white siliceous sands of the lower beds1 and the green grains in the upper part of the formation1 cause it to differ in mineral character from our white chalk4 ,beds of fine clay1 with fossil plants1 and with seams of lignite1 and even perfect coal1 are intercalated4 ,floating wood1 containing perforating shells1 such as ,pholas and ,gastrochoena1 occur4 ,there are likewise a few beds of a yellowish-brown limestone1 with marine shells1 which enable us to prove that the lowest and highest plant-beds belong to one group4 ,among these shells are ,pecten quadricostatus1 and several others which are common to the upper and lower part of the series1 and ,trigonia limbata1 ,d',orbigny1 a shell of the white chalk4 ,on the whole1 the organic remains and the geological position of the strata prove distinctly that in the neighbourhood of ,aix-la-,chapelle a gulf of the ancient ,cretaceous sea was bounded by land composed of ,devonian rocks4 ,these rocks consisted of quartzose and schistose beds1 the first of which supplied white sand and the other argillaceous mud to a river which entered the sea at this point1 carrying down in its turbid waters much drift-wood and the leaves of plants4 ,occasionally1 when the force of the river abated1 marine shells of the genera ,trigonia1 ,turritella1 ,pecten1 etc41 established themselves in the same area1 and plants allied to ,zostera and ,fucus grew on the bottom4 ,the fossil plants of this member of the upper chalk at ,aix have been diligently collected and studied by ,dr4 ,debey1 and as they afford the only example yet known of a terrestrial flora older than the ,eocene1 in which the great divisions of the vegetable kingdom are represented in nearly the same proportions as in our own times1 they deserve particular attention4 ,dr4 ,debey estimates the number of species as amounting to more than two hundred1 of which sixty-seven are cryptogamous1 chiefly ferns1 twenty species of which can be well determined1 most of them being in fructification4 ,the scars on the bark of one or two are supposed to indicate tree-ferns4 ,of thirteen genera three are still existing1 namely1 ,gleichenia1 now inhabiting the ,cape of ,good ,hope1 and ,new ,holland2 ,lygodium1 now spread extensively through tropical regions1 but having some species which live in ,japan and ,north ,america2 and ,asplenium1 a cosmopolite form4 ,among the phnogamous plants1 the ,conifers are abundant1 the most common belonging to a genus called ,cycadopteris by ,debey1 and hardly separable from ,sequoia 7or ,wellingtonia71 of which both the cones and branches are preserved4 ,when ,i visited ,aix1 ,i found the silicified wood of this plant very plentifully dispersed through the white sands in the pits near that city4 ,in one silicified trunk #bjj rings of annual growth could be counted4 ,species of ,araucaria like those of ,australia are also found4 ,cycads are extremely rare1 and of ,monocotyledons there are but few4 ,no palms have been recognised with certainty1 but the genus ,pandanus1 or screw pine1 has been distinctly made out4 ,the number of the ,dicotyledonous ,angiosperms is the most striking feature in so ancient a flora4#c ,among them we find the familiar forms of the ,oak1 ,fig1 and ,walnut 7,quercus1 ,ficus1 and ,juglans71 of the last both the nuts and leaves2 also several genera of the ,myrtace4 ,but the predominant order is the ,proteace1 of which there are between sixty and seventy supposed species1 many of extinct genera1 but some referred to the following living forms--,dryandra1 ,grevillea1 ,hakea1 ,banksia1 ,persoonia--all now belonging to ,australia1 and ,leucospermum1 species of which form small bushes at the ,cape4 ,brongniart4 ,lindley4 ,cryptogamic4 #a4 ,cryptogamous amphigens1 or cellular cryptogamic4 ,thallogens4 ,lichens1 sea-weeds1 fungi4 #b4 ,cryptogamous acrogens4 ,acrogens4 ,mosses1 equisetums1 ferns1 lycopodiums1--,lepidodendra4 ,phnerogamic4 #c4 ,dicotyledonous gymnosperms4 ,gymnogens4 ,conifers and ,cycads4 #d4 ,dicot4 angiosperms4 ,exogens4 ,composit1 leguminos1 crucifer1 healths1 etc4 ,all native ,european trees except conifers4 #e4 ,monocotyledons4 ,endogens4 ,palms1 lilies1 aloes1 rushes1 grasses1 etc4 ,the epidermis of the leaves of many of these ,aix plants1 especially of the ,proteace1 is so perfectly preserved in an envelope of fine clay1 that under the microscope the stomata1 or polygonal cellules1 can be detected1 and their peculiar arrangement is identical with that known to characterise some living ,proteace 7,grevillea1 for example74 ,although this peculiarity of the structure of stomata is also found in plants of widely distant orders1 it is1 on the whole1 but rarely met with1 and being thus observed to characterise a foliage previously suspected to be proteaceous1 it adds to the probability that the botanical evidence had been correctly interpreted4 ,an occasional admixture at ,aix-la-,chapelle of ,fucoids and ,zosterites attests1 like the shells1 the presence of salt-water4 ,of insects1 ,dr4 ,debey has obtained about ten species of the families ,curculionid and ,carabid4 ,the resemblance of the flora of ,aix-la-,chapelle to the tertiary and living floras in the proportional number of dicotyledonous angiosperms as compared to the gymnogens1 is a subject of no small theoretical interest1 because we can now affirm that these ,aix plants flourished before the rich reptilian fauna of the secondary rocks had ceased to exist4 ,the ,ichthyosaurus1 ,pterodactyl1 and ,mosasaurus were of coeval date with the oak1 the walnut1 and the fig4 ,speculations have often been hazarded respecting a connection between the rarity of ,exogens in the older rocks and a peculiar state of the atmosphere4 ,a denser air1 it was suggested1 had in earlier times been alike adverse to the well-being of the higher order of flowering plants1 and of the quick-breathing animals1 such as mammalia and birds1 while it was favourable to a cryptogamic and gymnospermous flora1 and to a predominance of reptile life4 ,but we now learn that there is no incompatibility in the co-existence of a vegetation like that of the present globe1 and some of the most remarkable forms of the extinct reptiles of the age of gymnosperms4 ,if the passage seem at present to be somewhat sudden from the flora of the ,lower or ,neocomian to that of the ,upper ,cretaceous period1 the abruptness of the change will probably disappear when we are better acquainted with the fossil vegetation of the uppermost beds of the ,neocomian and that of the lowest strata of the ,gault or true ,cretaceous series4 ,hippurite limestone4--,difference between the ,chalk of the ,north and ,south of ,europe4--,by the aid of the three tests1 superposition1 mineral character1 and fossils1 the geologist has been enabled to refer to the same ,cretaceous period certain rocks in the north and south of ,europe1 which differ greatly both in their fossil contents and in their mineral composition and structure4 ,fig4 #bgc3 ,map4 ,if we attempt to trace the cretaceous deposits from ,england and ,france to the countries bordering the ,mediterranean1 we perceive1 in the first place1 that in the neighbourhood of ,london and ,paris they form one great continuous mass1 the ,straits of ,dover being a trifling interruption1 a mere valley with chalk cliffs on both sides4 ,we then observe that the main body of the chalk which surrounds ,paris stretches from ,tours to near ,poitiers 7see ,fig4 #bgc1 in which the shaded part represents chalk74 ,between ,poitiers and ,la ,rochelle1 the space marked ,a on the map separates two regions of chalk4 ,this space is occupied by the ,oolite and certain other formations older than the ,chalk and ,neocomian1 and has been supposed by ,m4 ,e4 de ,beaumont to have formed an island in the ,cretaceous sea4 ,south of this space we again meet with rocks which we at once recognise to be cretaceous1 partly from the chalky matrix and partly from the fossils being very similar to those of the white chalk of the north3 especially certain species of the genera ,spatangus1 ,ananchytes1 ,cidarites1 ,nucula1 ,ostrea1 ,grypha 7,exogyra71 ,pecten1 ,plagiostoma 7,lima71 ,trigonia1 ,catillus 7,inoceramus71 and ,terebratula4#d ,but ,ammonites1 as ,m4 d',archiac observes1 of which so many species are met with in the chalk of the north of ,france1 are scarcely ever found in the southern region2 while the genera ,hamite1 ,turrilite1 and ,scaphite1 and perhaps ,belemnite1 are entirely wanting4 ,fig4 #bgd3 ,radiolites4 ,white chalk of ,france4 ,fig4 #bge3 ,radiolites foliaceus4 ,white chalk of ,france4 ,fig4 #bgf3 ,hippurites organisans4 ,upper chalk3--chalk marl of ,pyrenees8 ,fig4 #bgf3 ,hippurites organisans4 ,upper chalk3--chalk marl of ,pyrenees8#e ,on the other hand1 certain forms are common in the south which are rare or wholly unknown in the north of ,france4 ,among these may be mentioned many ,hippurites1 ,sphrulites1 and other members of that great family of mollusca called ,rudistes by ,lamarck1 to which nothing analogous has been discovered in the living creation1 but which is quite characteristic of rocks of the ,cretaceous era in the south of ,france1 ,spain1 ,sicily1 ,greece1 and other countries bordering the ,mediterranean4 ,the species called ,hippurites organisans 7,fig4 #bgf7 is more abundant than any other in the south of ,europe2 and the geologist should make himself well acquainted with the cast of the interior1 d1 which is often the only part preserved in many compact marbles of the ,upper ,cretaceous period4 ,the flutings on the interior of the ,hippurite1 which are represented on the cast by smooth1 rounded longitudinal ribs1 and in some individuals attain a great size and length1 are wholly unlike the markings on the exterior of the shell4 ,cretaceous ,rocks in the ,united ,states4--,if we pass to the ,american continent1 we find in the ,state of ,new ,jersey a series of sandy and argillaceous beds wholly unlike in mineral character to our ,upper ,cretaceous system2 which we can1 nevertheless1 recognise as referable1 palontologically1 to the same division4 ,that they were about the same age generally as the ,european chalk and ,neocomian1 was the conclusion to which ,dr4 ,morton and ,mr4 ,conrad came after their investigation of the fossils in #ahcd4 ,the strata consist chiefly of green sand and green marl1 with an overlying coralline limestone of a pale yellow colour1 and the fossils1 on the whole1 agree most nearly with those of the ,upper ,european series1 from the ,maestricht beds to the ,gault inclusive4 ,i collected sixty shells from the ,new ,jersey deposits in #ahda1 five of which were identical with ,european species--,ostrea larva1 ,o4 vesicularis1 ,grypha costata1 ,pecten quinque-costatus1 ,belemnitella mucronata4 ,as some of these have the greatest vertical range in ,europe1 they might be expected more than any others to recur in distant parts of the globe4 ,even where the species were different1 the generic forms1 such as the ,baculite and certain sections of ,ammonites1 as also the ,inoceramus 7see ,fig4 #beb7 and other bivalves1 have a decidedly cretaceous aspect4 ,fifteen out of the sixty shells above alluded to were regarded by ,professor ,forbes as good geographical representatives of well-known cretaceous fossils of ,europe4 ,the correspondence1 therefore1 is not small1 when we reflect that the part of the ,united ,states where these strata occur is between #cjjj and #djjj miles distant from the chalk of ,central and ,northern ,europe1 and that there is a difference of ten degrees in the latitude of the places compared on opposite sides of the ,atlantic4 ,fish of the genera ,lamna1 ,galeus1 and ,carcharodon are common to ,new ,jersey and the ,european cretaceous rocks4 ,so also is the genus ,mosasaurus among reptiles4 ,it appears from the labours of ,dr4 ,newberry and others1 that the ,cretaceous strata of the ,united ,states east and west of the ,appalachians are characterised by a flora decidedly analogous to that of ,aix-la-,chapelle above-mentioned1 and therefore having considerable resemblance to the vegetation of the ,tertiary and ,recent ,periods4 #a ,for particulars of structure see p4 #cah4 #b ,geol4 ,trans41 #ast ,series1 vol4 iv1 p4 #dac4 #c ,in this and subsequent remarks on fossil plants ,i shall often use ,dr4 ,lindley's terms1 as most familiar in this country2 but as those of ,m4 ,a4 ,brongniart are much cited1 it may be useful to geologists to give a table explaining the corresponding names of groups so much spoken of in palontology4 #d ,d',archiac1 ,sur la form4 ,crtace du ,s4-,o4 de la ,france ,mm4 de la ,soc4 ,gol4 de ,france1 tome ii4 #e ,d',orbigny's ,palontologie franais1 pl4 #ecc4 ,,chapter ,,xviii4 ,,lower ,,cretaceous ,,or ,,neocomian ,,formation4 ,classification of marine and fresh-water ,strata4 -- ,upper ,neocomian4 -- ,folkestone and ,hythe ,beds4 -- ,atherfield ,clay4 -- ,similarity of ,conditions causing ,reappearance of ,species after short ,intervals4 -- ,upper ,speeton ,clay4 -- ,middle ,neocomian4 -- ,tealby ,series4 -- ,middle ,speeton ,clay4 -- ,lower ,neocomian4 -- ,lower ,speeton ,clay4 -- ,wealden ,formation4 -- ,fresh-water ,character of the ,wealden4 -- ,weald ,clay4 -- ,hastings ,sands4 -- ,punfield ,beds of ,purbeck1 ,dorsetshire4 -- ,fossil ,shells and ,fish of the ,wealden4 -- ,area of the ,wealden4 -- ,flora of the ,wealden4 ,we now come to the ,lower ,cretaceous ,formation which was formerly called ,lower ,greensand1 and for which it will be useful for reasons before explained 7p4 #bhb7 to use the term 8,neocomian40 ,,lower ,,cretaceous ,,or ,,neocomian ,,group4 ,marine ,fresh-water ,upper ,neocomian--,greensand of ,folkestone1 ,sandgate1 and ,hythe1 ,atherfield clay1 upper part of ,speeton clay4 ,middle ,neocomian--,punfield ,marine bed1 ,tealby beds1 middle part of ,speeton clay4 ,lower ,neocomian--,lower part of ,speeton clay4 ,part of ,wealden beds of ,kent1 ,surrey1 ,sussex1 ,hants1 and ,dorset4 ,in ,western ,france1 the ,alps1 the ,carpathians1 ,northern ,italy1 and the ,apennines1 an extensive series of rocks has been described by ,continental geologists under the name of ,tithonian4 ,these beds1 which are without any marine equivalent in this country1 appear completely to bridge over the interval between the ,neocomian and the ,oolites4 ,they may1 perhaps1 as suggested by ,mr4 ,judd1 be of the same age as part of the ,wealden series4 ,,upper ,,neocomian4 ,folkstone and ,hythe ,beds4--,the sands which crop out beneath the ,gault in ,wiltshire1 ,surrey1 and ,sussex are sometimes in the uppermost part pure white1 at others of a yellow and ferruginous colour1 and some of the beds contain much green matter4 ,at ,folkestone they contain layers of calcareous matter and chert1 and at ,hythe1 in the neighbourhood1 as also at ,maidstone and other parts of ,kent1 the limestone called ,kentish ,rag is intercalated4 ,this somewhat clayey and calcareous stone forms strata two feet thick1 alternating with quartzose sand4 ,the total thickness of these ,folkestone and ,hythe beds is less than #cjj feet1 and they are seen to rest immediately on a grey clay1 to which we shall presently allude as the ,atherfield clay4 ,among the fossils of the ,folkestone and ,hythe beds we may mention ,nautilus plicatus 7,fig4 #bgg71 ,ancyloceras 7,scaphites7 gigas 7,fig4 #bgh71 which has been aptly described as an ,ammonite more or less uncoiled2 ,trigonia caudata 7,fig4 #bhj71 ,gervillia anceps 7,fig4 #bgi71 a bivalve genus allied to ,avicula1 and ,terebratula sella 7,fig4 #bha74 ,in ferruginous beds of the same age in ,wiltshire is found a remarkable shell called ,diceras ,lonsdalii 7,fig4 #bhb71 which abounds in the ,upper and ,middle ,neocomian of ,southern ,europe4 ,this genus is closely allied to ,chama1 and the cast of the interior has been compared to the horns of a goat4 ,fig4 #bgg3 ,nautilus licatus4 ,fig4 #bgh3 ,ancyloceras gigas4 ,fig4 #bgi3 ,gervillia anceps4 ,fig4 #bhj3 ,trigonia caudata4 ,atherfield ,clay4--,we mentioned before that the ,folkstone and ,hythe series rest on a grey clay4 ,this clay is only of slight thickness in ,kent and ,surrey1 but acquires great dimensions at ,atherfield1 in the ,isle of ,wight4 ,the difference1 indeed1 in mineral character and thickness of the ,upper ,neocomian formation near ,folkestone1 and the corresponding beds in the south of the ,isle of ,wight1 about #ajj miles distant1 is truly remarkable4 ,in the latter place we find no limestone answering to the ,kentish ,rag1 and the entire thickness from the bottom of the ,atherfield clay to the top of the ,neocomian1 instead of being less than #cjj feet as in ,kent1 is given by the late ,professor ,e4 ,forbes as #hdc feet1 which he divides into sixty-three strata1 forming three groups4 ,the uppermost of these consists of ferruginous sands1 the second of sands and clay1 and the third or lowest of a brown clay1 abounding in fossils4 ,fig4 #bha3 ,terebratula sella4 ,fig4 #bhb3 ,diceras ,lonsdalii4 a4 ,the bivavle shell1 b4 ,cast of one of the valves enlarged4 ,pebbles of quartzose sandstone1 jasper1 and flinty slate1 together with grains of chlorite and mica1 and1 as ,mr4 ,godwin-,austen has shown1 fragments and water-worn fossils of the oolitic rocks1 speak plainly of the nature of the pre-existing formations1 by the wearing down of which the ,neocomian beds were formed4 ,the land1 consisting of such rocks1 was doubtless submerged before the origin of the white chalk1 a deposit which was formed in a more open sea1 and in clearer waters4 ,fig4 #bhc3 ,perna mulleti4 ,among the shells of the ,atherfield clay the biggest and most abundant shell is the large ,perna ,mulleti1 of which a reduced figure is given in ,fig4 #bhc4 ,similarity of ,conditions causing ,reappearance of ,species4--,some species of mollusca and other fossils range through the whole series1 while others are confined to particular subdivisions1 and ,forbes laid down a law which has since been found of very general application in regard to estimating the chronological relations of consecutive strata4 ,whenever similar conditions1 he says1 are repeated1 the same species reappear1 provided too great a lapse of time has not intervened2 whereas if the length of the interval has been geologically great1 the same genera will reappear represented by distinct species4 ,changes of depth1 or of the mineral nature of the sea-bottom1 the presence or absence of lime or of peroxide of iron1 the occurrence of a muddy1 or a sandy1 or a gravelly bottom1 are marked by the banishment of certain species and the predominance of others4 ,but these differences of conditions being mineral1 chemical1 and local in their nature1 have no necessary connection with the extinction1 throughout a large area1 of certain animals or plants4 ,when the forms proper to loose sand or soft clay1 or to perfectly clear water1 or to a sea of moderate or great depth1 recur with all the same species1 we may infer that the interval of time has been1 geologically speaking1 small1 however dense the mass of matter accumulated4 ,but if1 the genera remaining the same1 the species are changed1 we have entered upon a new period2 and no similarity of climate1 or of geographical and local conditions1 can then recall the old species which a long series of destructive causes in the animate and inanimate world has gradually annihilated4 ,fig4 #bhd3 ,ammonites ,deshayesii4 ,speeton ,clay1 ,upper ,division4--,on the coast1 beneath the white chalk of ,flamborough ,head1 in ,yorkshire1 an argillaceous formation crops out1 called the ,speeton clay1 several hundred feet in thickness1 the palontological relations of which have been ably worked out by ,mr4 ,john ,w4 ,judd1#a and he has shown that it is separable into three divisions1 the uppermost of which1 #aej feet thick1 and containing #hg species of mollusca1 decidedly belongs to the ,atherfield clay and associated strata of ,hythe and ,folkestone1 already described4 ,it is characterised by the ,perna ,mulleti 7,fig4 #bhc7 and ,terebratula sella 7,fig4 #bha71 and by ,ammonites ,deshayesii 7,fig4 #bhd71 a well-known ,hythe fossil4 ,fine skeletons of reptiles of the genera ,pliosaurus and ,teleosaurus have been obtained from this clay4 ,at the base of this upper division of the ,speeton clay there occurs a layer of large ,septaria1 formerly worked for the manufacture of cement4 ,this bed is crowded with fossils1 especially ,ammonites1 one species of which1 three feet in diameter1 was observed by ,mr4 ,judd4 ,,middle ,,neocomian4 ,tealby ,series4--,at ,tealby1 a village in the ,lincolnshire ,wolds1 there crop out beneath the white chalk some non-fossiliferous ferruginous sands about twenty-feet thick1 beneath which are beds of clay and limestone1 about fifty feet thick1 with an interesting suite of fossils1 among which are ,pecten cinctus 7,fig4 #bhe71 from #i to #ab inches in diameter1 ,ancyloceras ,duvallei 7,fig4 #bhf71 and some forty other shells1 many of them common to the ,middle ,speeton clay1 about to be mentioned4 ,mr4 ,judd remarks that as ,ammonites clypeiformis and ,terebratula hippopus characterise the ,middle ,neocomian of the ,continent1 it is to this stage that the ,tealby series containing the same fossils may be assigned4#b ,fig4 #bhe3 ,pecten cinctus4 ,fig4 #bhf3 ,ancyloceras 7,crioceras7 ,duvallei4 ,the middle division of the ,speeton clay1 occurring at ,speeton below the cement-bed1 before alluded to1 is #aej feet thick1 and contains about #ci species of mollusca1 half of which are common to the overlying clay4 ,among the peculiar shells1 ,pecten cinctus 7,fig4 #bhe7 and ,ancyloceras 7,crioceras7 ,duvallei 7,fig4 #bhf7 occur4 ,,lower ,,neocomian4 ,in the lower division of the ,speeton clay1 #bjj feet thick1 #df species of mollusca have been found1 and three divisions1 each characterised by its peculiar ammonite1 have been noticed by ,mr4 ,judd4 ,the central zone is marked by ,ammonites ,noricus 7see ,fig4 #bhg74 ,on the ,continent these beds are well-known by their corresponding fossils1 the ,hils clay and conglomerate of the north of ,germany agreeing with the ,middle and ,lower ,speeton1 the latter of which1 with the same mineral characters and fossils as in ,yorkshire1 is also found in the little island of ,heligoland4 ,yellow limestone1 which ,i have myself seen near ,neuchatel1 in ,switzerland1 represents the ,lower ,neocomian at ,speeton4 ,fig4 #bhg3 ,ammonites ,noricus4 ,,wealden ,,formation4 ,beneath the ,atherfield clay or ,upper ,neocomian of the ,s4,e4 of ,england1 a fresh-water formation is found1 called the ,wealden1 which1 although it occupies a small horizontal area in ,europe1 as compared to the ,white ,chalk and the marine ,neocomian beds1 is nevertheless of great geological interest1 since the imbedded remains give us some insight into the nature of the terrestrial fauna and flora of the ,lower ,cretaceous epoch4 ,the name of ,wealden was given to this group because it was first studied in parts of ,kent1 ,surrey1 and ,sussex1 called the ,weald2 and we are indebted to ,dr4 ,mantell for having shown1 in #ahbb1 in his 8,geology of ,sussex10 that the whole group was of fluviatile origin4 ,in proof of this he called attention to the entire absence of ,ammonites1 ,belemnites1 ,brachiopoda1 ,echinodermata1 ,corals1 and other marine fossils1 so characteristic of the ,cretaceous rocks above1 and of the ,oolitic strata below1 and to the presence in the ,weald of ,paludin1 ,melani1 ,cyren1 and various fluviatile shells1 as well as the bones of terrestrial reptiles and the trunks and leaves of land-plants4 ,the evidence of so unexpected a fact as that of a dense mass of purely fresh-water origin underlying a deep-sea deposit 7a phenomenon with which we have since become familiar7 was received1 at first1 with no small doubt and incredulity4 ,but the relative position of the beds is unequivocal2 the ,weald ,clay being distinctly seen to pass beneath the ,atherfield ,clay in various parts of ,surrey1 ,kent1 and ,sussex1 and to reappear in the ,isle of ,wight at the base of the ,cretaceous series1 being1 no doubt1 continuous far beneath the surface1 as indicated by the dotted lines in ,fig4 #bhh4 ,they are also found occupying the same relative position below the chalk in the peninsula of ,purbeck1 ,dorsetshire1 where1 as we shall see in the sequel1 they repose on strata referable to the ,upper ,oolite4 ,weald ,clay4--,the ,upper division1 or ,weald ,clay1 is1 in great part1 of fresh-water origin1 but in its highest portion contains beds of oysters and other marine shells which indicate fluvio-marine conditions4 ,the uppermost beds are not only conformable1 as ,dr4 ,fitton observes1 to the inferior strata of the overlying ,neocomian1 but of similar mineral composition4 ,to explain this1 we may suppose that1 as the delta of a great river was tranquilly subsiding1 so as to allow the sea to encroach upon the space previously occupied by fresh-water1 the river still continued to carry down the same sediment into the sea4 ,in confirmation of this view it may be stated that the remains of the ,iguanodon ,mantelli1 a gigantic terrestrial reptile1 very characteristic of the ,wealden1 has been discovered near ,maidstone1 in the overlying ,kentish ,rag1 or marine limestone of the ,upper ,neocomian4 ,hence we may infer that some of the saurians which inhabited the country of the great river continued to live when part of the district had become submerged beneath the sea4 ,thus1 in our own times1 we may suppose the bones of large alligators to be frequently entombed in recent fresh-water strata in the delta of the ,ganges4 ,but if part of that delta should sink down so as to be covered by the sea1 marine formations might begin to accumulate in the same space where fresh-water beds had previously been formed2 and yet the ,ganges might still pour down its turbid waters in the same direction1 and carry seaward the carcasses of the same species of alligator1 in which case their bones might be included in marine as well as in subjacent fresh-water strata4 ,fig4 #bhh ,the ,iguanodon1 first discovered by ,dr4 ,mantell1 was an herbivorous reptile1 of which the teeth1 though bearing a great analogy1 in their general form and crenated edges 7see ,figs4 #bhi a and b71 to the modern ,iguanas which now frequent the tropical woods of ,america and the ,west ,indies1 exhibit many important differences4 ,it appears that they have often been worn by the process of mastication2 whereas the existing herbivorous reptiles clip and gnaw off the vegetable productions on which they feed1 but do not chew them4 ,their teeth frequently present an appearance of having been chipped off1 but never1 like the fossil teeth of the ,iguanodon1 have a flat ground surface 7see ,fig4 #bij1 b7 resembling the grinders of herbivorous mammalia4 ,dr4 ,mantell computes that the teeth and bones of this species which passed under his examination during twenty years must have belonged to no less than seventy-one distinct individuals1 varying in age and magnitude from the reptile just burst from the egg1 to one of which the femur measured twenty-four inches in circumference4 ,yet1 notwithstanding that the teeth were more numerous than any other bones1 it is remarkable that it was not until the relics of all these individuals had been found1 that a solitary example of part of a jaw-bone was obtained4 ,soon afterwards remains both of the upper and lower jaw were met with in the ,hastings beds in ,tilgate ,forest1 near ,cuckfield4 ,in the same sands at ,hastings1 ,mr4 ,beckles found large tridactyle impressions which it is conjectured were made by the hind feet of this animal1 on which it is ascertained that there were only three well-developed toes4 ,fig4 #bhi a1 b3 ,tooth of ,iguanodon ,mantelli4 ,fig4 #bij3 a4 ,partially worn tooth of young individual of the same2 ib4_/i ,crown of tooth in adult worn down4 ,fig4 #bia3 ,cypris spinigera4 ,occasionally bands of limestone1 called ,sussex ,marble1 occur in the ,weald ,clay1 almost entirely composed of a species of ,paludina1 closely resembling the common ,p4 vivipara of ,english rivers4 ,shells of the ,cypris1 a genus of ,crustaceans mentioned 7p4 #eg7 as abounding in lakes and ponds1 are also plentifully scattered through the clays of the ,wealden1 sometimes producing1 like plates of mica1 a thin lamination 7see ,fig4 #bib74 ,fig4 #bib3 ,weald clay with ,cyprides4 ,hastings ,sands4--,this lower division of the ,wealden consists of sand1 sandstone1 calciferous grit1 clay1 and shale2 the argillaceous strata1 notwithstanding the name1 predominating somewhat over the arenaceous1 as will be seen by reference to the following table1 drawn up by ,messrs4 ,drew and ,foster1 of the ,geological ,survey of ,great ,britain3 ,names of ,subordinate ,formations4 ,mineral ,composition of the ,strata4 ,thickness in feet4 ,hastings ,sand ,tunbridge ,wells ,sand ,sandstone and loam #aej ,wadhurst ,clay ,blue and brown shale and clay1 with a little calc-grit #ajj ,ashdown ,sand ,hard sand1 with some beds of calc-grit #afj ,ashburnham ,beds ,mottled white and red clay1 with some sandstone #ccj ,the picturesque scenery of the 8,high ,rocks0 and other places in the neighbourhood of ,tunbridge ,wells is caused by the steep natural cliffs1 to which a hard bed of white sand1 occurring in the upper part of the ,tunbridge ,wells ,sand1 mentioned in the above table1 gives rise4 ,this bed of 8rock-sand0 varies in thickness from #be to #dh feet4 ,large masses of it1 which were by no means hard or capable of making a good building-stone1 form1 nevertheless1 projecting rocks with perpendicular faces1 and resist the degrading action of the river because1 says ,mr4 ,drew1 they present a solid mass without planes of division4 ,the calcareous sandstone and grit of ,tilgate ,forest1 near ,cuckfield1 in which the remains of the ,iguanodon and ,hylosaurus were first found by ,dr4 ,mantell1 constitute an upper member of the ,tunbridge ,wells ,sand1 while the 8sand-rock0 of the ,hastings cliffs1 about #ajj feet thick1 is one of the lower members of the same4 ,the reptiles1 which are very abundant in this division1 consist partly of saurians1 referred by ,owen and ,mantell to eight genera1 among which1 besides those already enumerated1 we find the ,megalosaurus and ,plesiosaurus4 ,the ,pterodactyl also1 a flying reptile1 is met with in the same strata1 and many remains of ,chelonians of the genera ,trionyx and ,emys1 now confined to tropical regions4 ,the fishes of the ,wealden are chiefly referable to the ,ganoid and ,placoid orders4 ,among them the teeth and scales of ,lepidotus are most widely diffused 7see ,fig4 #bic1 next page74 ,these ganoids were allied to the ,lepidosteus1 or ,gar-pike1 of the ,american rivers4 ,the whole body was covered with large rhomboidal scales1 very thick1 and having the exposed part coated with enamel4 ,most of the species of this genus are supposed to have been either river-fish1 or inhabitants of the sea at the mouth of estuaries4 ,fig4 #bic3 ,lepidotus ,mantelli1 a4 ,palate and teeth1 b4 ,side view of teeth1 c4 ,scale4 ,fig4 #bid3 ,unio ,valdensis4 ,fig4 #bie3 ,under side of slab of sandstone about one yard in diameter4 ,at different heights in the ,hastings ,sands1 we find again and again slabs of sandstone with a strong ripple-mark1 and between these slabs beds of clay many yards thick4 ,in some places1 as at ,stammerham1 ,horsham1 near there1 are indications of this clay having been exposed so as to dry and crack before the next layer was thrown down upon it4 ,the open cracks in the clay have served as moulds1 of which casts have been taken in relief1 and which are1 therefore1 seen on the lower surface of the sandstone 7see ,fig4 #bie74 ,near the same place a reddish sandstone occurs in which are innumerable traces of a fossil vegetable1 apparently ,sphenopteris1 the stems and branches of which are disposed as if the plants were standing erect on the spot where they originally grew1 the sand having been gently deposited upon and around them2 and similar appearances have been remarked in other places in this formation4#c ,in the same division also of the ,wealden1 at ,cuckfield1 is a bed of gravel or conglomerate1 consisting of water-worn pebbles of quartz and jasper1 with rolled bones of reptiles4 ,these must have been drifted by a current1 probably in water of no great depth4 ,fig4 #bif3 ,sphenopteris gracilis4 ,from such facts we may infer that1 notwithstanding the great thickness of this division of the ,wealden1 the whole of it was a deposit in water of a moderate depth1 and often extremely shallow4 ,this idea may seem startling at first1 yet such would be the natural consequence of a gradual and continuous sinking of the ground in an estuary or bay1 into which a great river discharged its turbid waters4 ,by each foot of subsidence1 the fundamental rock would be depressed one foot farther from the surface2 but the bay would not be deepened1 if newly-deposited mud and sand should raise the bottom one foot4 ,on the contrary1 such new strata of sand and mud might be frequently laid dry at low water1 or overgrown for a season by a vegetation proper to marshes4 ,punfield ,beds1 ,brackish and ,marine4--,the shells of the ,wealden beds belong to the genera ,melanopsis1 ,melania1 ,paludina1 ,cyrena1 ,cyclas1 ,unio 7see ,fig4 #bid71 and others1 which inhabit rivers or lakes2 but one band has been found at ,punfield1 in ,dorsetshire1 indicating a brackish state of the water1 where the genera ,corbula1 ,mytilus1 and ,ostrea occur2 and in some places this bed becomes purely marine1 containing some well-known ,neocomian fossils1 among which ,ammonites ,deshayesii 7,fig4 #bhd7 may be mentioned4 ,others are peculiar as ,british1 but very characteristic of the ,upper and ,middle ,neocomian of ,spain1 and among these the ,vicarya ,lujani 7,fig4 #big71 a shell allied to ,nerinea1 is conspicuous4 ,by reference to table 7p4 #cjh7 it will be seen that the ,wealden beds are given as the fresh-water equivalents of the ,marine ,neocomian4 ,the highest part of them in ,england may1 for reasons just given1 be regarded as ,upper ,neocomian1 while some of the inferior portions may correspond in age to the ,middle and ,lower divisions of that group4 ,in favour of this latter view1 ,m4 ,marcou mentions that a fish called ,asteracanthus granulosus1 occurring in the ,tilgate beds1 is characteristic of the lowest beds of the ,neocomian of the ,jura1 and it is well known that ,corbula alata1 common in the ,ashburnham beds1 is found also at the base of the ,neocomian of the ,continent4 ,fig4 #big3 ,vicarya ,lujani4 ,fig4 #big3 ,vicarya ,lujani1 ,de ,verneuil4#d ,wealden1 ,punfield4 ,area of the ,wealden4--,in regard to the geographical extent of the ,wealden1 it cannot be accurately laid down1 because so much of it is concealed beneath the newer marine formations4 ,it has been traced about #cbj ,english miles from west to east1 from the coast of ,dorsetshire to near ,boulogne1 in ,france2 and nearly #bjj miles from north-west to south-east1 from ,surrey and ,hampshire to ,vassy1 in ,france4 ,if the formation be continuous throughout this space1 which is very doubtful1 it does not follow that the whole was contemporaneous2 because1 in all likelihood1 the physical geography of the region underwent frequent changes throughout the whole period1 and the estuary may have altered its form1 and even shifted its place4 ,dr4 ,dunker1 of ,cassel1 and ,h4 von ,meyer1 in an excellent monograph on the ,wealdens of ,hanover and ,westphalia1 have shown that they correspond so closely1 not only in their fossils1 but also in their mineral characters1 with the ,english series1 that we can scarcely hesitate to refer the whole to one great delta4 ,even then1 the magnitude of the deposit may not exceed that of many modern rivers4 ,thus1 the delta of the ,quorra or ,niger1 in ,africa1 stretches into the interior for more than #agj miles1 and occupies1 it is supposed1 a space of more than #cjj miles along the coast1 thus forming a surface of more than #be1jjj square miles1 or equal to about one-half of ,england4#e ,besides1 we know not1 in such cases1 how far the fluviatile sediment and organic remains of the river and the land may be carried out from the coast1 and spread over the bed of the sea4 ,i have shown1 when treating of the ,mississippi1 that a more ancient delta1 including species of shells such as now inhabit ,louisiana1 has been upraised1 and made to occupy a wide geographical area1 while a newer delta is forming2#f and the possibility of such movements and their effects must not be lost sight of when we speculate on the origin of the ,wealden4 ,it may be asked where the continent was placed1 from the ruins of which the ,wealden strata were derived1 and by the drainage of which a great river was fed4 ,if the ,wealden was gradually going downward #ajjj feet or more perpendicularly1 a large body of fresh-water would not continue to be poured into the sea at the same point4 ,the adjoining land1 if it participated in the movement1 could not escape being submerged4 ,but we may suppose such land to have been stationary1 or even undergoing contemporaneous slow upheaval4 ,there may have been an ascending movement in one region1 and a descending one in a contiguous parallel zone of country4 ,but even if that were the case1 it is clear that finally an extensive depression took place in that part of ,europe where the deep sea of the ,cretaceous period was afterwards brought in4 ,thickness of the ,wealden4--,in the ,weald area itself1 between the ,north and ,south ,downs1 fresh-water beds to the thickness of #afjj feet are known1 the base not being reached4 ,probably the thickness of the whole ,wealden series1 as seen in ,swanage ,bay1 cannot be estimated as less than #bjjj feet4 ,wealden ,flora4--,the flora of the ,wealden is characterised by a great abundance of ,conifer1 ,cycade1 and ,ferns1 and by the absence of leaves and fruits of ,dicotyledonous ,angiosperms4 ,the discovery in #ahee1 in the ,hastings beds of the ,isle of ,wight1 of ,gyrogonites1 or spore-vessels of the ,chara1 was the first example of that genus of plants1 so common in the tertiary strata1 being found in a ,secondary or ,mesozoic rock4 #a ,judd1 ,speeton clay1 ,quart4 ,geol4 ,journ41 vol4 xxiv1 #ahfh1 p4 #bah4 #b ,judd1 ,quart4 ,geol4 ,journ41 #ahfg1 vol4 xxiii1 p4 #bdi4 #c ,mantell1 ,geol4 of ,s4,e4 of ,england1 p4 #bdd4 #d ,foss4 de ,utrillas4 #e ,fitton1 ,geol4 of ,hastings1 p4 #eh1 who cites ,lander's ,travels4 #f ,see p4 #ajb and ,second ,visit to the ,united ,states1 vol4 ii1 chap4 xxxiv4 ,,chapter ,,xix4 ,,jurassic ,,group4--,,purbeck ,,beds ,,and ,,oolite4 ,the ,purbeck ,beds a ,member of the ,jurassic ,group4 -- ,subdivisions of that ,group4 -- ,physical ,geography of the ,oolite in ,england and ,france4 -- ,upper ,oolite4 -- ,purbeck ,beds4 -- ,new ,genera of fossil ,mammalia in the ,middle ,purbeck of ,dorsetshire4 -- ,dirt-bed or ancient ,soil4 -- ,fossils of the ,purbeck ,beds4 -- ,portland ,stone and ,fossils4 -- ,kimmeridge ,clay4 -- ,lithographic ,stone of ,solenhofen4 -- ,archopteryx4 -- ,middle ,oolite4 -- ,coral ,rag4 -- ,nerina ,limestone4 -- ,oxford ,clay1 ,ammonites and ,belemnites4 -- ,kelloway ,rock4 -- ,lower1 or ,bath1 ,oolite4 -- ,great ,plants of the ,oolite4 -- ,oolite and ,bradford ,clay4 -- ,stonesfield ,slate4 -- ,fossil ,mammalia4 -- ,fuller's ,earth4 -- ,inferior ,oolite and ,fossils4 -- ,northamptonshire ,slates4 -- ,yorkshire ,oolitic ,coal-field4 -- ,brora ,coal4 -- ,palontological ,relations of the several ,subdivisions of the ,oolitic group4 ,classification of the ,oolite4--,immediately below the ,hastings ,sands we find in ,dorsetshire another remarkable fresh-water formation1 called the ,purbeck1 because it was first studied in the sea-cliffs of the peninsula of ,purbeck in that county4 ,these beds are for the most part of fresh-water origin1 but the organic remains of some few intercalated beds are marine1 and show that the ,purbeck series has a closer affinity to the ,oolitic group1 of which it may be considered as the newest or uppermost member4 ,in ,england generally1 and in the greater part of ,europe1 both the ,wealden and ,purbeck beds are wanting1 and the marine cretaceous group is followed immediately1 in the descending order1 by another series called the ,jurassic4 ,in this term1 the formations commonly designated as 8the ,oolite and ,lias0 are included1 both being found in the ,jura ,mountains4 ,the ,oolite was so named because in the countries where it was first examined the limestones belonging to it had an ,oolitic structure 7see p4 #cg74 ,these rocks occupy in ,england a zone nearly thirty miles in average breadth1 which extends across the island1 from ,yorkshire in the north-east1 to ,dorsetshire in the south-west4 ,their mineral characters are not uniform throughout this region2 but the following are the names of the principal subdivisions observed in the central and south-eastern parts of ,england4 ,,oolite ,upper a4 ,purbeck beds4 b4 ,portland stone and sand4 c4 ,kimmeridge clay4 ,middle d4 ,coral rag4 e4 ,oxford clay1 and ,kelloway rock4 ,lower f4 ,cornbrash and ,forest marble4 g4 ,great ,oolite and ,stonesfield slate4 h4 ,fuller's earth4 i4 ,inferior ,oolite4 ,the ,upper ,oolitic system of the above table has usually the ,kimmeridge clay for its base2 the ,middle ,oolitic system1 the ,oxford clay4 ,the ,lower system reposes on the ,lias1 an argillo-calcareous formation1 which some include in the ,lower ,oolite1 but which will be treated of separately in the next chapter4 ,many of these subdivisions are distinguished by peculiar organic remains2 and1 though varying in thickness1 may be traced in certain directions for great distances1 especially if we compare the part of ,england to which the above-mentioned type refers with the north-east of ,france and the ,jura ,mountains adjoining4 ,in that country1 distant above #djj geographical miles1 the analogy to the accepted ,english type1 notwithstanding the thinness or occasional absence of the clays1 is more perfect than in ,yorkshire or ,normandy4 ,physical ,geography4--,the alternation1 on a grand scale1 of distinct formations of clay and limestone has caused the oolitic and liassic series to give rise to some marked features in the physical outline of parts of ,england and ,france4 ,wide valleys can usually be traced throughout the long bands of country where the argillaceous strata crop out2 and between these valleys the limestones are observed1 forming ranges of hills or more elevated grounds4 ,these ranges terminate abruptly on the side on which the several clays rise up from beneath the calcareous strata4 ,fig4 #bih3 ,configuration of surface4 ,fig4 #bih will give the reader an idea of the configuration of the surface now alluded to1 such as may be seen in passing from ,london to ,cheltenham1 or in other parallel lines1 from east to west1 in the southern part of ,england4 ,it has been necessary1 however1 in this drawing1 greatly to exaggerate the inclination of the beds1 and the height of the several formations1 as compared to their horizontal extent4 ,it will be remarked1 that the lines of steep slope1 or escarpment1 face towards the west in the great calcareous eminences formed by the chalk and the ,upper1 ,middle1 and ,lower ,oolites2 and at the base of which we have respectively the ,gault1 ,kimmeridge clay1 ,oxford clay1 and ,lias4 ,this last forms1 generally1 a broad vale at the foot of the escarpment of inferior ,oolite1 but where it acquires considerable thickness1 and contains solid beds of marlstone1 it occupies the lower part of the escarpment4 ,the external outline of the country which the geologist observes in travelling eastward from ,paris to ,metz1 is precisely analogous1 and is caused by a similar succession of rocks intervening between the tertiary strata and the ,lias2 with this difference1 however1 that the escarpments of ,chalk1 ,upper1 ,middle1 and ,lower ,oolites face towards the east instead of the west4 ,it is evident1 therefore1 that the denuding causes 7see p4 #aje7 have acted similarly over an area several hundred miles in diameter1 removing the softer clays more extensively than the limestones1 and causing these last to form steep slopes or escarpments wherever the harder calcareous rock was based upon a more yielding and destructible formation4 ,,upper ,,oolite4 ,purbeck ,beds4--,these strata1 which we class as the uppermost member of the ,oolite1 are of limited geographical extent in ,europe1 as already stated1 but they acquire importance when we consider the succession of three distinct sets of fossil remains which they contain4 ,such repeated changes in organic life must have reference to the history of a vast lapse of ages4 ,the ,purbeck beds are finely exposed to view in ,durdlestone ,bay1 near ,swanage1 ,dorsetshire1 and at ,lulworth ,cove and the neighbouring bays between ,weymouth and ,swanage4 ,at ,meup's ,bay1 in particular1 ,professor ,e4 ,forbes examined minutely1 in #ahej1 the organic remains of this group1 displayed in a continuous sea-cliff section1 and it appears from his researches that the ,upper1 ,middle1 and ,lower ,purbecks are each marked by peculiar species of organic remains1 these again being different1 so far as a comparison has yet been instituted1 from the fossils of the overlying ,hastings ,sands and ,weald ,clay4 ,upper ,purbeck4--,the highest of the three divisions is purely fresh-water1 the strata1 about fifty feet in thickness1 containing shells of the genera ,paludina1 ,physa1 ,limna1 ,planorbis1 ,valvata1 ,cyclas1 and ,unio1 with ,cyprides and fish4 ,all the species seem peculiar1 and among these the ,cyprides are very abundant and characteristic 7see ,fig4 #bii1 a1 b1 c47 ,the stone called 8,purbeck ,marble10 formerly much used in ornamental architecture in the old ,english cathedrals of the southern counties1 is exclusively procured from this division4 ,fig4 #bii3 ,cyprides from the ,upper ,purbecks4 ,middle ,purbeck4--,next in succession is the ,middle ,purbeck1 about thirty feet thick1 the uppermost part of which consists of fresh-water limestone1 with cyprides1 turtles1 and fish1 of different species from those in the preceding strata4 ,below the limestone are brackish-water beds full of ,cyrena1 and traversed by bands abounding in ,corbula and ,melania4 ,these are based on a purely marine deposit1 with ,pecten1 ,modiola1 ,avicula1 and ,thracia4 ,below this1 again1 come limestones and shales1 partly of brackish and partly of fresh-water origin1 in which many fish1 especially species of ,lepidotus and ,microdon radiatus1 are found1 and a crocodilian reptile named ,macrorhynchus4 ,among the mollusks1 a remarkable ribbed ,melania1 of the section ,chilina1 occurs4 ,fig4 #cjj3 ,ostrea distorta4 ,fig4 #cja3 ,hemicidaris ,purbeckensis4 ,immediately below is a great and conspicuous stratum1 twelve feet thick1 formed of a vast accumulation of shells of ,ostrea distorta 7,fig4 #cjj71 long familiar to geologists under the local name of 8,cinder-bed40 ,in the uppermost part of this bed ,professor ,forbes discovered the first echinoderm 7,fig4 #cja7 as yet known in the ,purbeck series1 a species of ,hemicidaris1 a genus characteristic of the ,oolitic period1 and scarcely1 if at all1 distinguishable from a previously known ,oolitic fossil4 ,it was accompanied by a species of ,perna4 ,below the ,cinder-bed fresh-water strata are again seen1 filled in many places with species of ,cypris 7,fig4 #cjb1 a1 b1 c71 and with ,valvata1 ,paludina1 ,planorbis1 ,limna1 ,physa 7,fig4 #cjc71 and ,cyclas1 all different from any occurring higher in the series4 ,it will be seen that ,cypris fasciculata 7,fig4 #cjb1 b7 has tubercles at the end only of each valve1 a character by which it can be immediately recognised4 ,in fact1 these minute crustaceans1 almost as frequent in some of the shales as plates of mica in a micaceous sandstone1 enable geologists at once to identify the ,middle ,purbeck in places far from the ,dorsetshire cliffs1 as1 for example1 in the ,vale of ,wardour in ,wiltshire4 ,thick beds of chert occur in the ,middle ,purbeck filled with mollusca and cyprides of the genera already enumerated1 in a beautiful state of preservation1 often converted into chalcedony4 ,among these ,professor ,forbes met with gyrogonites 7the spore-vessels of ,chara71 plants never until #ahea discovered in rocks older than the ,eocene4 ,about twenty feet below the 8,cinder-bed0 is a stratum two or three inches thick1 in which fossil mammalia presently to be mentioned occur1 and beneath this a thin band of greenish shales1 with marine shells and impressions of leaves like those of a large ,zostera1 forming the base of the ,middle ,purbeck4 ,fig4 #cjb3 ,cyprides from the ,middle ,purbecks4 ,fig4 #cjc3 ,physa ,bristovii ,fossil ,mammalia of the ,middle ,purbeck4--,in #aheb1a after alluding to the discovery of numerous insects and air-breathing mollusca in the ,purbeck strata1 ,i remarked that1 although no mammalia had then been found1 8it was too soon to infer their non-existence on mere negative evidence40 ,only two years after this remark was in print1 ,mr4 ,w4 ,r4 ,brodie found in the ,middle ,purbeck1 about twenty feet below the 8,cinder-bed0 above alluded to1 in ,durdlestone ,bay1 portions of several small jaws with teeth1 which ,professor ,owen recognised as belonging to a small mammifer of the insectivorous class1 more closely allied in its dentition to the ,amphitherium 7or ,thylacotherium7 than to any existing type4 ,four years later 7in #ahef7 the remains of several other species of warm-blooded quadrupeds were exhumed by ,mr4 ,s4 ,h4 ,beckles1 ,f4,r4,s41 from the same thin bed of marl near the base of the ,middle ,purbeck4 ,in this marly stratum many reptiles1 several insects1 and some fresh-water shells of the genera ,paludina1 ,planorbis1 and ,cyclas1 were found4 ,mr4 ,beckles had determined thoroughly to explore the thin layer of calcareous mud from which in the suburbs of ,swanage the bones of the ,spalacotherium had already been obtained1 and in three weeks he brought to light from an area forty feet long and ten wide1 and from a layer the average thickness of which was only five inches1 portions of the skeletons of six new species of mammalia1 as interpreted by ,dr4 ,falconer1 who first examined them4 ,before these interesting inquiries were brought to a close1 the joint labours of ,professor ,owen and ,dr4 ,falconer had made it clear that twelve or more species of mammalia characterised this portion of the ,middle ,purbeck1 most of them insectivorous or predaceous1 varying in size from that of a mole to that of the common polecat1 ,mustela putorius4 ,while the majority had the character of insectivorous marsupials1 ,dr4 ,falconer selected one as differing widely from the rest1 and pointed out that in certain characters it was allied to the living ,kangaroo-rat1 or ,hypsiprymnus1 ten species of which now inhabit the prairies and scrub-jungle of ,australia1 feeding on plants1 and gnawing scratched-up roots4 ,a striking peculiarity of their dentition1 one in which they differ from all other quadrupeds1 consists in their having a single large pre-molar1 the enamel of which is furrowed with vertical grooves1 usually seven in number4 ,the largest pre-molar 7see ,fig4 #cje7 in the fossil genus exhibits in like manner seven parallel grooves1 producing by their termination a similar serrated edge in the crown2 but their direction is diagonal--a distinction1 says ,dr4 ,falconer1 which is 8trivial1 not typical40 ,as these oblique furrows form so marked a character of the majority of the teeth1 ,dr4 ,falconer gave to the fossil the generic name of ,plagiaulax4 ,the shape and relative size of the incisor1 a1 ,fig4 #cjf1 exhibit a no less striking similarity to ,hypsiprymnus4 ,nevertheless1 the more sudden upward curve of this incisor1 as well as other characters of the jaw1 indicate a great deviation in the form of ,plagiaulax from that of the living kangaroo-rats4 ,fig4 #cjd3 ,pre-molar of the recent ,australian ,hypsiprymnus ,gaimardi1 showing #g grooves at right angles to the length of the jaw4 ,fig4 #cje3 ,third and largest pre-molar 7lower jaw7 of ,plagiaulax ,becklesii1 showing #g diagonal grooves4 ,fig4 #cjf3 ,plagiaulax ,becklessi4 ,right ramus of lower jaw4 ,there are two fossil specimens of lower jaws of this genus evidently referable to two distinct species extremely unequal in size and otherwise distinguishable4 ,the ,plagiaulax ,becklesii 7,fig4 #cjf7 was about as big as the ,english squirrel or the flying phalanger of ,australia 7,petaurus ,australis1 ,waterhouse74 ,the smaller fossil1 having only half the linear dimensions of the other1 was probably only one-twelfth of its bulk4 ,it is of peculiar geological interest1 because1 as shown by ,dr4 ,falconer1 its two back molars bear a decided resemblance to those of the ,triassic ,microlestes 7,fig4 #chi71 the most ancient of known mammalia1 of which an account will be given in ,chapter ,,xxi4 ,up to #aheg all the mammalian remains discovered in secondary rocks had consisted solely of single branches of the lower jaw1 but in that year ,mr4 ,beckles obtained the upper portion of a skull1 and on the same slab the lower jaw of another quadruped with eight molars1 a large canine1 and a broad and thick incisor4 ,it has been named ,triconodon from its bicuspid teeth1 and is supposed to have been a small insectivorous marsupial1 about the size of a hedgehog4 ,other jaws have since been found indicating a larger species of the same genus4 ,professor ,owen has proposed the name of ,galestes for the largest of the mammalia discovered in #aheh in ,purbeck1 equalling the polecat 7,mustela putorius7 in size4 ,it is supposed to have been predaceous and marsupial4 ,between forty and fifty pieces or sides of lower jaws with teeth have been found in oolitic strata in ,purbeck2 only five upper maxillaries1 together with one portion of a separate cranium1 occur at ,stonesfield1 and it is remarkable that with these there were no examples in ,purbeck of an entire skeleton1 nor of any considerable number of bones in juxtaposition4 ,in several portions of the matrix there were detached bones1 often much decomposed1 and fragments of others apparently mammalian2 but if all of them were restored1 they would scarcely suffice to complete the five skeletons to which the five upper maxillaries above alluded to belonged4 ,as the average number of pieces in each mammalian skeleton is about #bej1 there must be many thousands of missing bones2 and when we endeavour to account for their absence1 we are almost tempted to indulge in speculations like those once suggested to me by ,dr4 ,buckland1 when he tried to solve the enigma in reference to ,stonesfield2 8,the corpses10 he said1 8of drowned animals1 when they float in a river1 distended by gases during putrefaction1 have often their lower jaw hanging loose1 and sometimes it has dropped off4 ,the rest of the body may then be drifted elsewhere1 and sometimes may be swallowed entire by a predaceous reptile or fish1 such as an ichthyosaur or a shark40 ,as all the above-mentioned ,purbeck marsupials1 belonging to eight or nine genera and to about fourteen species1 insectivorous1 predaceous1 and herbivorous1 have been obtained from an area less than #ejj square yards in extent1 and from a single stratum no more than a few inches thick1 we may safely conclude that the whole lived together in the same region1 and in all likelihood they constituted a mere fraction of the mammalia which inhabited the lands drained by one river and its tributaries4 ,they afford the first positive proof as yet obtained of the co-existence of a varied fauna of the highest class of vertebrata with that ample development of reptile life which marks all the periods from the ,trias to the ,lower ,cretaceous inclusive1 and with a gymnospermous flora1 or that state of the vegetable kingdom when cycads and conifers predominated over all kinds of plants1 except the ferns1 so far1 at least1 as our present imperfect knowledge of fossil botany entitles us to speak4 ,the following table will enable the reader to see at a glance how conspicuous a part1 numerically considered1 the mammalian species of the ,middle ,purbeck now play when compared with those of other formations more ancient than the ,paris gypsum1 and1 at the same time1 it will help him to appreciate the enormous hiatus in the history of fossil mammalia which at present occurs between the ,eocene and ,purbeck periods1 and between the latter and the ,stonesfield ,oolite1 and between this again and the ,trias4 ,number and ,distribution of all the known ,species of ,fossil ,mammalia from ,strata older than the ,paris ,gypsum1 or than the ,bembridge ,series of the ,isle of ,wight4 ,,tertiary ,headon ,series and beds between the ,paris ,gypsum and the ,grs de ,beauchamp #ad #aj ,english #d ,french ,barton ,clay and ,sables de ,beauchamp #j ,bagshot ,beds1 ,calcaire ,grossier1 and ,upper ,soissonnais of ,cuisse-,lamotte #bj #af ,french #a ,english #c ,u4 ,states#b ,london ,clay1 including the ,kyson ,sand #g ,english ,plastic ,clay and ,lignite #i #g ,french #b ,english ,sables de ,bracheux #a ,french ,thanet ,sands and ,lower ,landenian of ,belgium #j ,,secondary ,maestricht ,chalk #j ,white ,chalk #j ,chalk ,marl #j ,chloritic ,series 7,upper ,greensand7 #j ,gault #j ,neocomian 7,lower ,greensand7 #j ,wealden #j ,upper ,purbeck ,oolite #j ,middle ,purbeck ,oolite #ad ,swanage ,lower ,purbeck ,oolite #j ,portland ,oolite #j ,kimmeridge ,clay #j ,coral ,rag #j ,oxford ,clay #j ,great ,oolite #d ,stonesfield ,inferior ,oolite #j ,lias #j ,upper ,trias #d ,wurtemberg ,somersetshire ,n4 ,carolina ,middle ,trias #j ,lower ,trias #j ,,primary ,permian #j ,carboniferous #j ,devonian #j ,silurian #j ,cambrian #j ,laurentian #j ,the ,sables de ,bracheux1 enumerated in the ,tertiary division of the table1 supposed by ,mr4 ,prestwich to be somewhat newer than the ,thanet ,sands1 and by ,m4 ,hbert to be of about that age1 have yielded at ,la ,fere the ,arctocyon 7,palocyon7 primvus1 the oldest known tertiary mammal4 ,it is worthy of notice1 that in the ,hastings ,sands there are certain layers of clay and sandstone in which numerous footprints of quadrupeds have been found by ,mr4 ,beckles1 and traced by him in the same set of rocks through ,sussex and the ,isle of ,wight4 ,they appear to belong to three or four species of reptiles1 and no one of them to any warm-blooded quadruped4 ,they ought1 therefore1 to serve as a warning to us1 when we fail in like manner to detect mammalian footprints in older rocks 7such as the ,new ,red ,sandstone71 to refrain from inferring that quadrupeds1 other than reptilian1 did not exist or pre-exist4 ,but the most instructive lesson read to us by the ,purbeck strata consists in this3 ,they are all1 with the exception of a few intercalated brackish and marine layers1 of fresh-water origin2 they are #afj feet in thickness1 have been well searched by skillful collectors1 and by the late ,edward ,forbes in particular1 who studied them for months consecutively4 ,they have been numbered1 and the contents of each stratum recorded separately1 by the officers of the ,geological ,survey of ,great ,britain4 ,they have been divided into three distinct groups by ,forbes1 each characterised by the same genera of pulmoniferous mollusca and cyprides1 these genera being represented in each group by different species2 they have yielded insects of many orders1 and the fruits of several plants2 and lastly1 they contain 8dirt-beds10 or old terrestrial surfaces and vegetable soils at different levels1 in some of which erect trunks and stumps of cycads and conifers1 with their roots still attached to them1 are preserved4 ,yet when the geologist inquires if any land-animals of a higher grade than reptiles lived during any one of these three periods1 the rocks are all silent1 save one thin layer a few inches in thickness2 and this single page of the earth's history has suddenly revealed to us in a few weeks the memorials of so many species of fossil mammalia1 that they already outnumber those of many a subdivision of the tertiary series1 and far surpass those of all the other secondary rocks put together6 ,lower ,purbeck4--,beneath the thin marine band mentioned at p4 #cbd as the base of the ,middle ,purbeck1 some purely fresh-water marls occur1 containing species of ,cypris 7,fig4 #cjg a1 c71 ,valvata1 and ,limna1 different from those of the ,middle ,purbeck4 ,this is the beginning of the inferior division1 which is about #hj feet thick4 ,below the marls are seen1 at ,meup's ,bay1 more than thirty feet of brackish-water strata1 abounding in a species of ,serpula1 allied to1 if not identical with1 ,serpula coacervites1 found in beds of the same age in ,hanover4 ,there are also shells of the genus ,rissoa 7of the subgenus ,hydrobia71 and a little ,cardium of the subgenus ,protocardium1 in these marine beds1 together with ,cypris4 ,some of the cypris-bearing shales are strangely contorted and broken up1 at the west end of the ,isle of ,purbeck4 ,the great dirt-bed or vegetable soil containing the roots and stools of ,cycade1 which ,i shall presently describe1 underlies these marls1 and rests upon the lowest fresh-water limestone1 a rock about eight feet thick1 containing ,cyclas1 ,valvata1 and ,limna1 of the same species as those of the uppermost part of the ,lower ,purbeck1 or above the dirt-bed4 ,the fresh-water limestone in its turn rests upon the top beds of the ,portland stone1 which1 although it contains purely marine remains1 often consists of a rock undistinguishable in mineral character from the ,lowest ,purbeck limestone4 ,fig4 #cjg3 ,cyprides from the ,lower ,purbeck4 ,fig4 #cjh3 ,mantellia nidiformis4 ,dirt-bed or ancient ,surface-soil4--,the most remarkable of all the varied succession of beds enumerated in the above list is that called by the quarrymen 8the dirt10 or 8black dirt10 which was evidently an ancient vegetable soil4 ,it is from #ab to #ah inches thick1 is of a dark brown or black colour1 and contains a large proportion of earthy lignite4 ,through it are dispersed rounded and sub-angular fragments of stone1 from #c to #i inches in diameter1 in such numbers that it almost deserves the name of gravel4 ,i also saw in #ahff1 in ,portland1 a smaller dirt-bed six feet below the principal one1 six inches thick1 consisting of brown earth with upright ,cycads of the same species1 ,mantellia nidiformis1 as those found in the upper bed1 but no ,conifer4 ,the weight of the incumbent strata squeezing down the compressible dirt-bed has caused the ,cycads to assume that form which has led the quarrymen to call them 8petrified birds' nests10 which suggested to ,brongniart the specific name of nidiformis4 ,i am indebted to ,mr4 ,carruthers for ,figure #cjh of one of these ,purbeck specimens1 in which the original cylindrical figure has been less distorted than usual by pressure4 ,many silicified trunks of coniferous trees1 and the remains of plants allied to ,zamia and ,cycas1 are buried in this dirt-bed1 and must have become fossil on the spots where they grew4 ,the stumps of the trees stand erect for a height of from one to three feet1 and even in one instance to six feet1 with their roots attached to the soil at about the same distances from one another as the trees in a modern forest4 ,the carbonaceous matter is most abundant immediately around the stumps1 and round the remains of fossil ,cycade4 ,besides the upright stumps above mentioned1 the dirt-bed contains the stems of silicified trees laid prostrate4 ,these are partly sunk into the black earth1 and partly enveloped by a calcareous slate which covers the dirt-bed4 ,the fragments of the prostrate trees are rarely more than three or four feet in length2 but by joining many of them together1 trunks have been restored1 having a length from the root to the branches of from #bj to #bc feet1 the stems being undivided for #ag or #bj feet1 and then forked4 ,the diameter of these near the root is about one foot2 but ,i measured one myself1 in #ahff1 which was #c feet in diameter1 said by the quarrymen to be unusually large4 ,root-shaped cavities were observed by ,professor ,henslow to descend from the bottom of the dirt-bed into the subjacent fresh-water stone1 which1 though now solid1 must have been in a soft and penetrable state when the trees grew4 ,the thin layers of calcareous slate 7,fig4 #cji7 were evidently deposited tranquilly1 and would have been horizontal but for the protrusion of the stumps of the trees1 around the top of each of which they form hemispherical concretions4 ,fig4 #cji3 ,section in ,isle of ,portland1 ,dorset4 ,the dirt-bed is by no means confined to the island of ,portland1 where it has been most carefully studied1 but is seen in the same relative position in the cliffs east of ,lulworth ,cove1 in ,dorsetshire1 where1 as the strata have been disturbed1 and are now inclined at an angle of #de1 the stumps of the trees are also inclined at the same angle in an opposite direction--a beautiful illustration of a change in the position of beds originally horizontal 7see ,fig4 #caj74 ,fig4 #caj3 ,section of cliff east of ,lulworth ,cove4 ,from the facts above described we may infer1 first1 that those beds of the ,upper ,oolite1 called 8the ,portland10 which are full of marine shells1 were overspread with fluviatile mud1 which became dry land1 and covered by a forest1 throughout a portion of the space now occupied by the south of ,england1 the climate being such as to permit the growth of the ,zamia and ,cycas4 ,secondly4 ,this land at length sank down and was submerged with its forests beneath a body of fresh-water1 from which sediment was thrown down enveloping fluviatile shells4 ,thirdly4 ,the regular and uniform preservation of this thin bed of black earth over a distance of many miles1 shows that the change from dry land to the state of a fresh-water lake or estuary1 was not accompanied by any violent denudation1 or rush of water1 since the loose black earth1 together with the trees which lay prostrate on its surface1 must inevitably have been swept away had any such violent catastrophe taken place4 ,the forest of the dirt-bed1 as before hinted1 was not everywhere the first vegetation which grew in this region4 ,besides the lower bed containing upright ,cycade1 before mentioned1 another has sometimes been found above it1 which implies oscillations in the level of the same ground1 and its alternate occupation by land and water more than once4 ,subdivisions of the ,purbeck4--,it will be observed that the division of the ,purbecks into upper1 middle1 and lower1 was made by ,professor ,forbes strictly on the principle of the entire distinctness of the species of organic remains which they include4 ,the lines of demarkation are not lines of disturbance1 nor indicated by any striking physical characters or mineral changes4 ,the features which attract the eye in the ,purbecks1 such as the dirt-beds1 the dislocated strata at ,lulworth1 and the ,cinder-bed1 do not indicate any breaks in the distribution of organised beings4 8,the causes which led to a complete change of life three times during the deposition of the fresh-water and brackish strata must10 says this naturalist1 8be sought for1 not simply in either a rapid or a sudden change of their area into land or sea1 but in the great lapse of time which intervened between the epochs of deposition at certain periods during their formation40 ,each dirt-bed may1 no doubt1 be the memorial of many thousand years or centuries1 because we find that two or three feet of vegetable soil is the only monument which many a tropical forest has left of its existence ever since the ground on which it now stands was first covered with its shade4 ,yet1 even if we imagine the fossil soils of the ,lower ,purbeck to represent as many ages1 we need not be surprised to find that they do not constitute lines of separation between strata characterised by different zoological types4 ,the preservation of a layer of vegetable soil1 when in the act of being submerged1 must be regarded as a rare exception to a general rule4 ,it is of so perishable a nature1 that it must usually be carried away by the denuding waves or currents of the sea1 or by a river2 and many ,purbeck dirt-beds were probably formed in succession and annihilated1 besides those few which now remain4 ,the plants of the ,purbeck beds1 so far as our knowledge extends at present1 consist chiefly of ,ferns1 ,conifer1 and ,cycade 7,fig4 #cjh71 without any angiosperms2 the whole more allied to the ,oolitic than to the ,cretaceous vegetation4 ,the same affinity is indicated by the vertebrate and invertebrate animals4 ,mr4 ,brodie has found the remains of beetles and several insects of the homopterous and trichopterous orders1 some of which now live on plants1 while others are of such forms as hover over the surface of our present rivers4 ,portland ,oolite and ,sand 7b1 ,table p4 #cba74--,the ,portland ,oolite has already been mentioned as forming in ,dorsetshire the foundation on which the fresh-water limestone of the ,lower ,purbeck reposes 7see p4 #cca74 ,it supplies the well-known building-stone of which ,st4 ,paul's and so many of the principal edifices of ,london are constructed4 ,about fifty species of mollusca occur in this formation1 among which are some ammonites of large size4 ,the cast of a spiral univalve called by the quarrymen the 8,portland screw0 7a1 ,figure #caa71 is common2 the shell of the same 7b7 being rarely met with4 ,also ,trigonia gibbosa 7,fig4 #cac7 and ,cardium dissimile 7,fig4 #cad74 ,this upper member rests on a dense bed of sand1 called the ,portland ,sand1 containing similar marine fossils1 below which is the ,kimmeridge ,clay4 ,in ,england these ,upper ,oolite formations are almost wholly confined to the southern counties4 ,but some fragments of them occur beneath the ,neocomian or ,speeton ,clay on the coast of ,yorkshire1 containing many more fossils common to the ,portlandian of the ,continent than does the same formation in ,dorsetshire4 ,corals are rare in this formation1 although one species is found plentifully at ,tisbury1 ,wiltshire1 in the ,portland ,sand1 converted into flint and chert1 the original calcareous matter being replaced by silex 7,fig4 #cab74 ,fig4 #caa3 ,cerithium ,portlandicum4 ,fig4 #cab3 ,isastra oblonga4 ,fig4 #cac3 ,trigonia gibbosa4 ,kimmeridge ,clay4--,the ,kimmeridge ,clay consists1 in great part1 of a bituminous shale1 sometimes forming an impure coal1 several hundred feet in thickness4 ,in some places in ,wiltshire it much resembles peat2 and the bituminous matter may have been1 in part at least1 derived from the decomposition of vegetables4 ,but as impressions of plants are rare in these shales1 which contain ammonites1 oysters1 and other marine shells1 with skeletons of fish and saurians1 the bitumen may perhaps be of animal origin4 ,some of the saurians 7,pliosaurus7 in ,dorsetshire are among the most gigantic of their kind4 ,fig4 #cad3 ,cardium dissimile4 ,fig4 #cae3 ,ostrea expansa4 ,fig4 #caf3 ,cardium striatulum4 ,fig4 #cag3 ,ostrea deltoidea4 ,fig4 #cah3 ,grypha 7,exogyra7 virgula4 ,among the fossils1 amounting to nearly #ajj species1 may be mentioned ,cardium striatulum 7,fig4 #caf7 and ,ostrea deltoidea 7,fig4 #cag71 the latter found in the ,kimmeridge ,clay throughout ,england and the north of ,france1 and also in ,scotland1 near ,brora4 ,the ,grypha virgula 7,fig4 #cah71 also met with in the ,kimmeridge ,clay near ,oxford1 is so abundant in the ,upper ,oolite of parts of ,france as to have caused the deposit to be termed 8marnes gryphes virgules40 ,near ,clermont1 in ,argonne1 a few leagues from ,st4 ,menehould1 where these indurated marls crop out from beneath the ,gault1 ,i have seen them1 on decomposing1 leave the surface of every ploughed field literally strewed over with this fossil oyster4 ,fig4 #cai3 ,trigonellites latus4 ,the ,trigonellites latus 7,aptychus of some authors7 7,fig4 #cai7 is also widely dispersed through this clay4 ,the real nature of the shell1 of which there are many species in oolitic rocks1 is still a matter of conjecture4 ,some are of opinion that the two plates have been the gizzard of a cephalopod2 others1 that it may have formed a bivalve operculum of the same4 ,solenhofen ,stone4--,the celebrated lithographic stone of ,solenhofen in ,bavaria1 appears to be of intermediate age between the ,kimmeridge clay and the ,coral ,rag1 presently to be described4 ,it affords a remarkable example of the variety of fossils which may be preserved under favourable circumstances1 and what delicate impressions of the tender parts of certain animals and plants may be retained where the sediment is of extreme fineness4 ,although the number of testacea in this slate is small1 and the plants few1 and those all marine1 count ,munster had determined no less than #bcg species of fossils when ,i saw his collection in #ahcc2 and among them no less than seven species of flying reptiles or pterodactyls 7see ,fig4 #cbj71 six saurians1 three tortoises1 sixty species of fish1 forty-six of crustacea1 and twenty-six of insects4 ,these insects1 among which is a libellula1 or dragon-fly1 must have been blown out to sea1 probably from the same land to which the pterodactyls1 and other contemporaneous air-breathers1 resorted4 ,fig4 #cbj3 ,skeleton of ,pterodactylus crassirostris4 ,in the same slate of ,solenhofen a fine example was met with in #ahfb of the skeleton of a bird almost entire1 and retaining even its feathers so perfect that the vanes as well as the shaft are preserved4 ,the head was at first supposed to be wanting1 but ,mr4 ,evans detected on the slab what seems to be the impression of the cranium and beak1 much resembling in size and shape that of the jay or woodcock4 ,this valuable specimen is now in the ,british ,museum1 and has been called by ,professor ,owen ,archopteryx macrura4 ,although anatomists agree that it is a true bird1 yet they also find that in the length of the bones of the tail1 and some other minor points of its anatomy1 it approaches more nearly to reptiles than any known living bird4 ,in the living representatives of the class ,aves1 the tail-feathers are attached to a coccygian bone1 consisting of several vertebr united together1 whereas in the ,archopteryx the tail is composed of twenty vertebr1 each of which supports a pair of quill-feathers4 ,the first five only of the vertebr1 as seen in ,a1 have transverse processes1 the fifteen remaining ones become gradually longer and more tapering4 ,the feathers diverge outward from them at an angle of #de4 ,fig4 #cba3 ,tail and feather of ,archopteryx1 from ,solenhofen1 and tail of living bird for comparison4 ,professor ,huxley in his late memoirs on the order of reptiles called ,dinosaurians1 which are largely represented in all the formations1 from the ,neocomian to the ,trias inclusive1 has shown that they present in their structure many remarkable affinities to birds4 ,but a reptile about two feet long1 called ,compsognathus1 lately found in the ,stonesfield slate1 makes a much greater approximation to the class ,aves than any ,dinosaur1 and therefore forms a closer link between the classes ,aves and ,reptilia than does the ,archopteryx4 ,it appears doubtful whether any species of ,british fossil1 whether of the vertebrate or invertebrate class1 is common to the ,oolite and ,chalk4 ,but there is no similar break or discordance as we proceed downward1 and pass from one to another of the several leading members of the ,jurassic group1 the ,upper1 ,middle1 and ,lower ,oolite1 and the ,lias1 there being often a considerable proportion of the mollusca1 sometimes as much as a fourth1 common to such divisions as the ,upper and ,middle ,oolite4 ,,middle ,,oolite4 ,coral ,rag4--,one of the limestones of the ,middle ,oolite has been called the 8,coral ,rag10 because it consists1 in part1 of continuous beds of petrified corals1 most of them retaining the position in which they grew at the bottom of the sea4 ,in their forms they more frequently resemble the reef-building polyparia of the ,pacific than do the corals of any other member of the ,oolite4 ,they belong chiefly to the genera ,thecosmilia 7,fig4 #cbb71 ,protoseris1 and ,thamnastra1 and sometimes form masses of coral fifteen feet thick4 ,fig4 #cbb3 ,thecosmilia annularis4 ,fig4 #cbc3 ,thamnastra4 ,fig4 #cbd3 ,ostrea gregaria4 ,fig4 #cbe3 ,nerina ,goodhallii4 ,in ,fig4 #cbc of a ,thamnastra from this formation1 it will be seen that the cup-shaped cavities are deepest on the right-hand side1 and that they grow more and more shallow1 until those on the left side are nearly filled up4 ,the last-mentioned stars are supposed to represent a perfected condition1 and the others an immature state4 ,these coralline strata extend through the calcareous hills of the north-west of ,berkshire1 and north of ,wilts1 and again recur in ,yorkshire1 near ,scarborough4 ,the ,ostrea gregarea 7,fig4 #cbd7 is very characteristic of the formation in ,england and on the ,continent4 ,one of the limestones of the ,jura1 referred to the age of the ,english ,coral ,rag1 has been called 8,nerinan limestone0 7,calcaire ,nrines7 by ,m4 ,thirria2 ,nerina being an extinct genus of univalve shells 7,fig4 #cbe7 much resembling the ,cerithium in external form4 ,the section shows the curious and continuous ridges on the columnella and whorls4 ,oxford ,clay4--,the coralline limestone1 or 8,coral ,rag10 above described1 and the accompanying sandy beds1 called 8calcareous grits10 of the ,middle ,oolite1 rest on a thick bed of clay1 called the 8,oxford ,clay10 sometimes not less than #fjj feet thick4 ,in this there are no corals1 but great abundance of cephalopoda1 of the genera ,ammonite and ,belemnite 7,figs4 #cbf and #cbg74 ,in some of the finely laminated clays ammonites are very perfect1 although somewhat compressed1 and are frequently found with the lateral lobe extended on each side of the opening of the mouth into a horn-like projection 7,figure #cbg74 ,these were discovered in the cuttings of the ,great ,western ,railway1 near ,chippenham1 in #ahda1 and have been described by ,mr4 ,pratt 7,an4 ,nat4 ,hist41 ,nov41 #ahda74 ,fig4 #cbf3 ,belemnites hastatus4 ,fig4 #cbg3 ,ammonites ,jason4 ,similar elongated processes have been also observed to extend from the shells of some ,belemnites discovered by ,dr4 ,mantell in the same clay 7see ,figure #cbh71 who1 by the aid of this and other specimens1 has been able to throw much light on the structure of singular extinct forms of cuttle-fish4#c ,kelloway ,rock4--,the arenaceous limestone which passes under this name is generally grouped as a member of the ,oxford clay1 in which it forms1 in the south-west of ,england1 lenticular masses1 #h or #aj feet thick1 containing at ,kelloway1 in ,wiltshire1 numerous casts of ammonites and other shells4 ,but in ,yorkshire this calcareo-arenaceous formation thickens to about #cj feet1 and constitutes the lower part of the ,middle ,oolite1 extending inland from ,scarborough in a southerly direction4 ,the number of mollusca which it contains is1 according to ,mr4 ,etheridge1 #adc1 of which only #cd1 or #bc per cent1 are common to the ,oxford clay proper4 ,of the #eb ,cephalopoda1 #ae 7namely #ac species of ammonite1 the ,ancyloceras ,calloviense and one ,belemnite7 are common to the ,oxford ,clay1 giving a proportion of nearly #cj per cent4 ,fig4 #cbh3 ,belemnites ,puzosianus4 ,,lower ,,oolite4 ,cornbrash and ,forest ,marble4--,the upper division of this series1 which is more extensive than the preceding or ,middle ,oolite1 is called in ,england the ,cornbrash1 as being a brashy1 easily broken rock1 good for corn land4 ,it consists of clays and calcareous sandstones1 which pass downward into the ,forest ,marble1 an argillaceous limestone1 abounding in marine fossils4 ,in some places1 as at ,bradford1 this limestone is replaced by a mass of clay4 ,the sandstones of the ,forest ,marble of ,wiltshire are often ripple-marked and filled with fragments of broken shells and pieces of drift-wood1 having evidently been formed on a coast4 ,rippled slabs of fissile oolite are used for roofing1 and have been traced over a broad band of country from ,bradford in ,wilts1 to ,tetbury in ,gloucestershire4 ,these calcareous tile-stones are separated from each other by thin seams of clay1 which have been deposited upon them1 and have taken their form1 preserving the undulating ridges and furrows of the sand in such complete integrity1 that the impressions of small footsteps1 apparently of crustaceans1 which walked over the soft wet sands1 are still visible4 ,in the same stone the claws of crabs1 fragments of echini1 and other signs of a neighbouring beach1 are observed4#d ,great 7or ,bath7 ,oolite4--,although the name of ,coral ,rag has been appropriated1 as we have seen1 to a member of the ,middle ,oolite before described1 some portions of the ,lower ,oolite are equally entitled in many places to be called coralline limestones4 ,thus the ,great ,oolite near ,bath contains various corals1 among which the ,eunomia radiata 7,fig4 #cbi7 is very conspicuous1 single individuals forming masses several feet in diameter2 and having probably required1 like the large existing brain-coral 7,meandrina7 of the tropics1 many centuries before their growth was completed4 ,fig4 #cbi3 ,eunomia radiata4 ,different species of crinoids1 or stone-lilies1 are also common in the same rocks with corals2 and1 like them1 must have enjoyed a firm bottom1 where their base of attachment remained undisturbed for years 7c1 ,fig4 #ccj74 ,such fossils1 therefore1 are almost confined to the limestones2 but an exception occurs at ,bradford1 near ,bath1 where they are enveloped in clay sometimes #fj feet thick4 ,in this case1 however1 it appears that the solid upper surface of the 8,great ,oolite0 had supported1 for a time1 a thick submarine forest of these beautiful zoophytes1 until the clear and still water was invaded by a current charged with mud1 which threw down the stone-lilies1 and broke most of their stems short off near the point of attachment4 ,the stumps still remain in their original position2 but the numerous articulations1 once composing the stem1 arms1 and body of the encrinite1 were scattered at random through the argillaceous deposit in which some now lie prostrate4 ,these appearances are represented in the section b1 ,fig4 #ccj1 where the darker strata represent the ,bradford clay1 which is however a formation of such local development that in many places it cannot easily be separated from the clays of the overlying 8forest-marble0 and underlying 8fuller's earth40 ,the upper surface of the calcareous stone below is completely incrusted over with a continuous pavement1 formed by the stony roots or attachments of the ,crinoidea2 and besides this evidence of the length of time they had lived on the spot1 we find great numbers of single joints1 or circular plates of the stem and body of the encrinite1 covered over with serpul4 ,now these serpul could only have begun to grow after the death of some of the stone-lilies1 parts of whose skeletons had been strewed over the floor of the ocean before the irruption of argillaceous mud4 ,in some instances we find that1 after the parasitic serpul were full grown1 they had become incrusted over with a bryozoan1 called ,diastopora diluviana 7see b1 ,fig4 #cca72 and many generations of these molluscoids had succeeded each other in the pure water before they became fossil4 ,fig4 #ccj3 ,apiocrinites rotundus1 or ,pear ,eucrinite4 ,fig4 #cca3 a4 ,aingle plate of body of ,apiocrinus1 overgrown with serpul and bryozoa2 b4 ,portion of same magnified1 showing the bryozoan ,diastopora diluviana covering one of the serpul4 ,we may1 therefore1 perceive distinctly that1 as the pines and cycadeous plants of the ancient 8dirt-bed10 or fossil forest1 of the ,lower ,purbeck were killed by submergence under fresh water1 and soon buried beneath muddy sediment1 so an invasion of argillaceous matter put a sudden stop to the growth of the ,bradford ,encrinites1 and led to their preservation in marine strata4 ,such differences in the fossils as distinguish the calcareous and argillaceous deposits from each other1 would be described by naturalists as arising out of a difference in the stations of species2 but besides these1 there are variations in the fossils of the higher1 middle1 and lower part of the oolitic series1 which must be ascribed to that great law of change in organic life by which distinct assemblages of species have been adapted1 at successive geological periods1 to the varying conditions of the habitable surface4 ,in a single district it is difficult to decide how far the limitation of species to certain minor formations has been due to the local influence of stations1 or how far it has been caused by time or the law of variation above alluded to4 ,but we recognise the reality of the last-mentioned influence1 when we contrast the whole oolitic series of ,england with that of parts of the ,jura1 ,alps1 and other distant regions1 where1 although there is scarcely any lithological resemblance1 yet some of the same fossils remain peculiar in each country to the ,upper1 ,middle1 and ,lower ,oolite formations respectively4 ,mr4 ,thurmann has shown how remarkably this fact holds true in the ,bernese ,jura1 although the argillaceous divisions1 so conspicuous in ,england1 are feebly represented there1 and some entirely wanting4 ,the calcareous portion of the ,great ,oolite consists of several shelly limestones1 one of which1 called the ,bath ,oolite1 is much celebrated as a building-stone4 ,in parts of ,gloucestershire1 especially near ,minchinhampton1 the ,great ,oolite1 says ,mr4 ,lycett1 8must have been deposited in a shallow sea1 where strong currents prevailed1 for there are frequent changes in the mineral character of the deposit1 and some beds exhibit false stratification4 ,in others1 heaps of broken shells are mingled with pebbles of rocks foreign to the neighbourhood1 and with fragments of abraded madrepores1 dicotyledonous wood1 and crabs' claws4 ,the shelly strata1 also1 have occasionally suffered denudation1 and the removed portions have been replaced by clay40 ,in such shallow-water beds shells of the genera ,patella1 ,nerita1 ,rimula1 ,cylindrites are common 7see ,figs4 #ccd to #ccg72 while cephalopods are rare1 and instead of ammonites and belemnites1 numerous genera of carnivorous trachelipods appear4 ,out of #bbd species of univalves obtained from the ,minchinhampton beds1 ,mr4 ,lycett found no less than #ej to be carnivorous4 ,they belong principally to the genera ,buccinum1 ,pleurotoma1 ,rostellaria1 ,murex1 ,purpuroidea 7,fig4 #ccc71 and ,fusus1 and exhibit a proportion of zoophagous species not very different from that which obtains in seas of the ,recent period4 ,these zoological results are curious and unexpected1 since it was imagined that we might look in vain for the carnivorous trachelipods in rocks of such high antiquity as the ,great ,oolite1 and it was a received doctrine that they did not begin to appear in considerable numbers till the ,eocene period1 when those two great families of cephalopoda1 the ammonites and belemnites1 and a great number of other representatives of the same class of chambered shells1 had become extinct4 ,fig4 #ccb3 ,terebratula digona4 ,fig4 #ccc3 ,purpuroidea nodulata4 ,fig4 #ccd3 ,cylindrites acutus4 ,fig4 #cce3 ,patella rugosa4 ,fig4 #ccf3 ,nerita costulata4 ,fig4 #ccg3 ,rimula 7,emarginula7 clathrata4 ,stonesfield ,slate3 ,mammalia4--,the slate of ,stonesfield has been shown by ,mr4 ,lonsdale to lie at the base of the ,great ,oolite4#e ,it is a slightly oolitic shelly limestone1 forming large lenticular masses imbedded in sand only six feet thick1 but very rich in organic remains4 ,it contains some pebbles of a rock very similar to itself1 and which may be portions of the deposit1 broken up on a shore at low water or during storms1 and redeposited4 ,the remains of belemnites1 trigoni1 and other marine shells1 with fragments of wood1 are common1 and impressions of ferns1 cycade1 and other plants4 ,several insects1 also1 and1 among the rest1 the elytra or wing-covers of beetles1 are perfectly preserved 7see ,fig4 #cch71 some of them approaching nearly to the genus ,buprestis4 ,the remains1 also1 of many genera of reptiles1 such as ,plesiosaur1 ,crocodile1 and ,pterodactyl1 have been discovered in the same limestone4 ,fig4 #cch3 ,elytron of ,buprestis8 ,but the remarkable fossils for which the ,stonesfield slate is most celebrated are those referred to the mammiferous class4 ,the student should be reminded that in all the rocks described in the preceding chapters as older than the ,eocene1 no bones of any land-quadruped1 or of any cetacean1 had been discovered until the ,spalacotherium of the ,purbeck beds came to light in #ahed4 ,yet we have seen that terrestrial plants were not wanting in the ,upper ,cretaceous formation 7see p4 #cjb71 and that in the ,wealden there was evidence of fresh-water sediment on a large scale1 containing various plants1 and even ancient vegetable soils4 ,we had also in the same ,wealden many land-reptiles and winged insects1 which render the absence of terrestrial quadrupeds the more striking4 ,the want1 however1 of any bones of whales1 seals1 dolphins1 and other aquatic mammalia1 whether in the chalk or in the upper or middle oolite1 is certainly still more remarkable4 ,these observations are made to prepare the reader to appreciate more justly the interest felt by every geologist in the discovery in the ,stonesfield slate of no less than ten specimens of lower jaws of mammiferous quadrupeds1 belonging to four different species and to three distinct genera1 for which the names of ,amphitherium1 ,phascolotherium1 and ,stereognathus have been adopted4 ,fig4 #cci3 ,tupaia ,tana4 ,right ramus of lower jaw4 ,it is now generally admitted that these or really the remains of mammalia 7although it was at first suggested that they might be reptiles71 and the only question open to controversy is limited to this point1 whether the fossil mammalia found in the ,lower ,oolite of ,oxfordshire ought to be referred to the marsupial quadrupeds1 or to the ordinary placental series4 ,cuvier had long ago pointed out a peculiarity in the form of the angular process 7c1 ,figs4 #cdb and #cdc7 of the lower jaw1 as a character of the genus ,didelphys2 and ,professor ,owen has since confirmed the doctrine of its generality in the entire marsupial series4 ,in all these pouched quadrupeds this process is turned inward1 as at c1 d1 ,fig4 #cdb1 in the ,brazilian opossum1 whereas in the placental series1 as at c1 ,figs4 #cdj and #cda1 there is an almost entire absence of such inflection4 ,the ,tupaia ,tana of ,sumatra has been selected by ,mr4 ,waterhouse for this illustration1 because the jaws of that small insectivorous quadruped bear a great resemblance to those of the ,stonesfield ,amphitherium4 ,by clearing away the matrix from the specimen of ,amphitherium ,prevostii here represented 7,fig4 #cdd71 ,professor ,owen ascertained that the angular process 7c7 bent inward in a slighter degree than in any of the known marsupialia2 in short1 the inflection does not exceed that of the mole or hedgehog4 ,this fact made him doubt whether the ,amphitherium might not be an insectivorous placental1 although it offered some points of approximation in its osteology to the marsupials1 especially to the ,myrmecobius1 a small insectivorous quadruped of ,australia1 which has nine molars on each side of the lower jaw1 besides a canine and three incisors4#f ,another species of ,amphitherium has been found at ,stonesfield 7,fig4 #cde71 which differs from the former 7,fig4 #cdd7 principally in being larger4 ,fig4 #cdj3 ,part of lower jaw of ,tupaia ,tana4 ,fig4 #cda3 ,side view of same4 ,fig4 #cdb3 ,part of lower jaw of ,didelphys ,azar4 ,fig4 #cdc3 ,side view of same4 ,fig4 #cdd3 ,amphitherium ,prevostii4 ,fig4 #cdd3 ,amphitherium ,prevostii4 ,fig4 #cde3 ,amphitherium ,broderipii4 ,fig4 #cdf3 ,phascolotherium ,bucklandii4 ,the second mammiferous genus discovered in the same slates was named originally by ,mr4 ,broderip ,didelphys ,bucklandi 7see ,fig4 #cdf71 and has since been called ,phascolotherium by ,owen4 ,it manifests a much stronger likeness to the marsupials in the general form of the jaw1 and in the extent and position of its inflected angle1 while the agreement with the living genus ,didelphys in the number of the pre-molar and molar teeth is complete4#g ,in #ahed the remains of another mammifer1 small in size1 but larger than any of those previously known1 was brought to light4 ,the generic name of ,stereognathus was given to it1 and1 as is usually the case in these old rocks 7see p4 #cbh71 it consisted of part of a lower jaw1 in which were implanted three double-fanged teeth1 differing in structure from those of all other known recent or extinct mammals4 ,plants of the ,oolite4--,the ,araucarian pines1 which are now abundant in ,australia and its islands1 together with marsupial quadrupeds1 are found in like manner to have accompanied the marsupials in ,europe during the ,oolitic period 7see ,fig4 #cdh74 ,in the same rock endogens of the most perfect structure are met with1 as1 for example1 fruits allied to the ,pandanus1 such as the ,kaidacarpum ooliticum of ,carruthers in the ,great ,oolite1 and the ,podocarya of ,buckland 7see ,fig4 #cdg7 in the ,inferior ,oolite4 ,fuller's ,earth4--,between the ,great and ,inferior ,oolite near ,bath1 an argillaceous deposit1 called 8the fuller's earth10 occurs2 but it is wanting in the north of ,england4 ,it abounds in the small oyster represented in ,fig4 #cdi4 ,the number of mollusca known in this deposit is about seventy2 namely1 fifty ,lamellibranchiate ,bivalves1 ten ,brachiopods1 three ,gasteropods1 and seven or eight ,cephalopods4 ,fig4 #cdg3 ,portion of a fossil fruit of ,podocarya ,bucklandii4 ,fig4 #cdh3 ,cone of fossil ,araucaria sphrocarpa4 ,fig4 #cdi3 ,ostrea acuminata4 ,inferior ,oolite4--,this formation consists of a calcareous freestone1 usually of small thickness1 but attaining in some places1 as in the typical area of ,cheltenham and the ,western ,cotswolds1 a thickness of #bej feet4 ,it sometimes rests upon yellow sands1 formerly classed as the sands of the ,inferior ,oolite1 but now regarded as a member of the ,upper ,lias4 ,these sands repose upon the ,upper ,lias clays in the south and west of ,england4 ,the ,collyweston slate1 formerly classed with the ,great ,oolite1 and supposed to represent in ,northamptonshire the ,stonesfield slate1 is now found to belong to the ,inferior ,oolite1 both by community of species and position in the series4 ,the ,collyweston beds1 on the whole1 assume a much more marine character than the ,stonesfield slate4 ,nevertheless1 one of the fossil plants ,aroides ,stutterdi1 ,carruthers1 remarkable1 like the ,pandanaceous species before mentioned 7,fig4 #cdg7 as a representative of the monocotyledonous class1 is common to the ,stonesfield beds in ,oxfordshire4 ,the ,inferior ,oolite of ,yorkshire consists largely of shales and sandstones1 which assume much the aspect of a true coal-field1 thin seams of coal having actually been worked in them for more than a century4 ,a rich harvest of fossil ferns has been obtained from them1 as at ,gristhorpe1 near ,scarborough 7,fig4 #cej74 ,they contain also ,cycade1 of which family a magnificent specimen has been described by ,mr4 ,williamson under the name ,zamia gigas1 and a fossil called ,equisetum ,columnare 7see ,fig4 #cig71 which maintains an upright position in sandstone strata over a wide area4 ,shells of ,estheria and ,unio1 collected by ,mr4 ,bean from these ,yorkshire coal-bearing beds1 point to the estuary or fluviatile origin of the deposit4 ,fig4 #cej3 ,hemitelites ,brownii4 ,at ,brora1 in ,sutherlandshire1 a coal formation1 probably coeval with the above1 or at least belonging to some of the lower divisions of the ,oolitic period1 has been mined extensively for a century or more4 ,it affords the thickest stratum of pure vegetable matter hitherto detected in any secondary rock in ,england4 ,one seam of coal of good quality has been worked three and a half feet thick1 and there are several feet more of pyritous coal resting upon it4 ,fig4 #cea3 ,terebratula fimbria4 ,fig4 #ceb3 ,rhynchonella spinosa4 ,fig4 #cec3 ,pholadomya fidicula4 ,among the characteristic shells of the ,inferior ,oolite1 ,i may instance ,terebratula fimbria 7,fig4 #cea71 ,rhynchonella spinosa 7,fig4 #ceb71 and ,pholadomya fidicula 7,fig4 #cec74 ,the extinct genus ,pleurotomaria is also a form very common in this division as well as in the ,oolitic system generally4 ,it resembles the ,trochus in form1 but is marked by a deep cleft 7a1 ,figs4 #ced1 #cee7 on one side of the mouth4 ,the ,collyrites 7,dysaster7 ringens 7,fig4 #cef7 is an ,echinoderm common to the ,inferior ,oolite of ,england and ,france1 as are the two ,ammonites 7,figs4 #ceg1 #ceh74 ,fig4 #ced3 ,pleurotomaria granulata4 ,fig4 #cee3 ,pleurotomaria ornata4 ,fig4 #cef3 ,collyrites 7,dysaster7 ringens4 ,fig4 #ceg3 ,ammonites ,humphresianus4 ,fig4 #ceh3 ,ammonites ,braikenridgii4 ,fig4 #cei3 ,ostrea ,marshii4 ,palontological ,relations of the ,oolitic ,strata4--,observations have already been made on the distinctness of the organic remains of the ,oolitic and ,cretaceous strata1 and the proportion of species common to the different members of the ,oolite4 ,between the ,lower ,oolite and the ,lias there is a somewhat greater break1 for out of #bef mollusca of the ,upper ,lias1 thirty-seven species only pass up into the ,inferior ,oolite4 ,fig4 #cfj3 ,ammonites macrocephalus4 ,in illustration of shells having a great vertical range1 it may be stated that in ,england some few species pass up from the ,lower to the ,upper ,oolite1 as1 for example1 ,rhynchonella obsoleta1 ,lithodomus inclusus1 ,pholadomya ovalis1 and ,trigonia costata4 ,of all the ,jurassic ,ammonites of ,great ,britain1 ,a4 macrocephalus 7,fig4 #cfj71 which is common to the ,great ,oolite and ,oxford ,clay1 has the widest range4 ,we have every reason to conclude that the gaps which occur1 both between the larger and smaller sections of the ,english ,oolites1 imply intervals of time1 elsewhere represented by fossiliferous strata1 although no deposit may have taken place in the ,british area4 ,this conclusion is warranted by the partial extent of many of the minor and some of the larger divisions even in ,england4 #a ,elements of ,geology1 #dth edition4 #b ,i allude to several ,zeuglodons found in ,alabama1 and referred by some zoologists to three species4 #c ,see ,phil4 ,trans4 #ahej1 p4 #cfc2 also ,huxley1 ,memoirs of ,geol4 ,survey1 #ahfd2 ,phillips1 ,palont4 ,soc4 #d ,p4 ,scrope1 ,proc4 ,geol4 ,soc41 ,march1 #ahca4 #e ,proceedings ,geol4 ,soc41 vol4 i1 p4 #dad4 #f ,a figure of this recent ,myrmecobius will be found in my ,principles of ,geology1 chap4 ix4 #g ,owen's ,british ,fossil ,mammals1 p4 #fb4 ,,chapter ,,xx4 ,,jurassic ,,group--continued--,,lias4 ,mineral ,character of ,lias4 -- ,numerous successive ,zones in the ,lias1 marked by distinct ,fossils1 without ,unconformity in the ,stratification1 or ,change in the ,mineral ,character of the ,deposits4 -- ,gryphite ,limestone4 -- ,shells of the ,lias4 -- ,fish of the ,lias4 -- ,reptiles of the ,lias4 -- ,ichthyosaur and ,plesiosaur4 -- ,marine ,reptile of the ,galapagos ,islands4 -- ,sudden ,destruction and ,burial of ,fossil ,animals in ,lias4 -- ,fluvio-marine ,beds in ,gloucestershire1 and ,insect ,limestone4 -- ,fossil ,plants4 -- ,the origin of the ,oolite and ,lias1 and of alternating ,calcareous and ,argillaceous ,formations4 ,lias4--,the ,english provincial name of ,lias has been very generally adopted for a formation of argillaceous limestone1 marl1 and clay1 which forms the base of the ,oolite1 and is classed by many geologists as part of that group4 ,the peculiar aspect which is most characteristic of the ,lias in ,england1 ,france1 and ,germany1 is an alternation of thin beds of blue or grey limestone1 having a surface which becomes light-brown when weathered1 these beds being separated by dark-coloured1 narrow argillaceous partings1 so that the quarries of this rock1 at a distance1 assume a striped and ribbon-like appearance4 ,the ,lias has been divided in ,england into three groups1 the ,upper1 ,middle1 and ,lower4 ,the ,upper ,lias consists first of sands1 which were formerly regarded as the base of the ,oolite1 but which1 according to ,dr4 ,wright1 are by their fossils more properly referable to the ,lias2 secondly1 of clay shale and thin beds of limestone4 ,the ,middle ,lias1 or marl-stone series1 has been divided into three zones2 and the ,lower ,lias1 according to the labours of ,quenstedt1 ,oppel1 ,strickland1 ,wright1 and others1 into seven zones1 each marked by its own group of fossils4 ,this ,lower ,lias averages from #fjj to #ijj feet in thickness4 ,from ,devon and ,dorsetshire to ,yorkshire all these divisions1 observes ,professor ,ramsay1 are constant2 and from top to bottom we cannot assert that anywhere there is actual unconformity between any two subdivisions1 whether of the larger or smaller kind4 ,in the whole of the ,english ,lias there are at present known about #icg species of mollusca1 and of these #bfg are ,cephalopods1 of which class more than two-thirds are ,ammonites1 the ,nautilus and ,belemnite also abounding4 ,the whole series has been divided by zones characterised by particular ,ammonites2 for while other families of shells pass from one division to another in numbers varying from about #bj to #ej per cent1 these cephalopods are almost always limited to single zones1 as ,quenstedt and ,oppel have shown for ,germany1 and ,dr4 ,wright and others for ,england4 ,as no actual unconformity is known from the top of the ,upper to the bottom of the ,lower ,lias1 and as there is a marked uniformity in the mineral character of almost all the strata1 it is somewhat difficult to account even for such partial breaks as have been alluded to in the succession of species1 if we reject the hypothesis that the old species were in each case destroyed at the close of the deposition of the rocks containing them1 and replaced by the creation of new forms when the succeeding formation began4 ,i agree with ,professor ,ramsay in not accepting this hypothesis4 ,no doubt some of the old species occasionally died out1 and left no representatives in ,europe or elsewhere2 others were locally exterminated in the struggle for life by species which invaded their ancient domain1 or by varieties better fitted for a new state of things4 ,pauses also of vast duration may have occurred in the deposition of strata1 allowing time for the modification of organic life throughout the globe1 slowly brought about by variation accompanied by extinction of the original forms4 ,fig4 #cfa3 ,plagiostoma 7,lima7 giganteum4 ,fig4 #cfb3 ,grypha incurva4 ,fossils of the ,lias4--,the name of ,gryphite limestone has sometimes been applied to the ,lias1 in consequence of the great number of shells which it contains of a species of oyster1 or ,grypha 7,fig4 #cfb74 ,a large heavy shell called ,hippopodium 7,fig4 #cfe71 allied to ,cypricardia1 is also characteristic of the upper part of the ,lower ,lias4 ,in this formation occur also the ,aviculas1 ,figs4 #cfc and #cfd4 ,the ,lias formation is also remarkable for being the newest of the secondary rocks in which brachiopoda of the genera ,spirifer and ,leptna 7,figs4 #cff1 #cfg7 occur1 although the former is slightly modified in structure so as to constitute the subgenus ,spiriferina1 ,davidson1 and the ,leptna has dwindled to a shell smaller in size than a pea4 ,no less than eight or nine species of ,spiriferina are enumerated by ,mr4 ,davidson as belonging to the ,lias4 ,palliobranchiate mollusca predominate greatly in strata older than the ,trias2 but1 so far as we yet know1 they did not survive the ,liassic epoch4 ,fig4 #cfc3 ,avicula inquivalvis4 ,fig4 #cfd3 ,avicula cygnipes4 ,fig4 #cfe3 ,hippopodium ponderosum4 ,fig4 #cff3 ,spiriferina 7,spirifera74 ,fig4 #cfg3 ,leptna ,moorei4 ,fig4 #cfh3 ,ammonites ,bucklandi4 ,fig4 #cfi3 ,ammonites planorbis4 ,fig4 #cgj3 ,nautilus truncatus4 ,fig4 #cga3 ,ammonites bifrons4 ,allusion has already been made1 p4 #ced1 to numerous zones in the ,lias having each their peculiar ,ammonites4 ,two of these occur near the base of the ,lower ,lias1 having a united thickness1 varying from #dj to #hj feet4 ,the upper of these is characterised by ,ammonites ,bucklandi1 and the lower by ,ammonites planorbis 7see ,figs4 #cfh1 #cfi74a ,sometimes1 however1 there is a third intermediate zone1 that of ,ammonites angulatus1 which is the equivalent of the zone called the infra-lias on the ,continent1 the species of which are for the most part common to the superior group marked by ,ammonites ,bucklandi4 ,fig4 #cgb3 ,ammonites margaritatus4 ,among the ,crinoids or ,stone-lilies of the ,lias1 the ,pentacrinites are conspicuous4 7,see ,fig4 #cgc47 ,of ,palocoma 7,ophioderma7 ,egertoni 7,fig4 #cgd71 referable to the ,ophiurid of ,muller1 perfect specimens have been met with in the ,middle ,lias beds of ,dorset and ,yorkshire4 ,fig4 #cgc3 ,extracrinus 7,pentacrinus7 ,briareus4 ,fig4 #cgd3 ,palocoma 7,ophioderma7 tenuibrachiata4 ,the ,extracrinus ,briareus 7removed by ,major ,austin from ,pentacrinus on account of generic differences7 occurs in tangled masses1 forming thin beds of considerable extent1 in the ,lower ,lias of ,dorset1 ,gloucestershire1 and ,yorkshire4 ,the remains are often highly charged with pyrites4 ,this ,crinoid1 with its innumerable tentacular arms1 appears to have been frequently attached to the driftwood of the liassic sea1 in the same manner as ,barnacles float about on wood at the present day4 ,there is another species of ,extracrinus and several of ,pentacrinus in the ,lias2 and the latter genus is found in nearly all the formations from the ,lias to the ,london ,clay inclusive4 ,it is represented in the present seas by the delicate and rare ,pentacrinus caput-medus of the ,antilles1 which1 with ,comatula1 is one of the few surviving members of the ancient family of the ,crinoids1 represented by so many extinct genera in the older formations4 ,fig4 #cge3 ,scales of ,lepidotus gigas4 ,fig4 #cgf3 a4 ,scales of chmodus ,leachii1 b4 chmodus 7restored outline71 c4 ,scales of ,dapedius monilifer4 ,fishes of the ,lias4--,the fossil fish1 of which there are no less than #aag species known as ,british1 resemble generically those of the ,oolite1 but differ1 according to ,m4 ,agassiz1 from those of the ,cretaceous period4 ,among them is a species of ,lepidotus 7,l4 gigas1 ,agassiz71 ,fig4 #cge1 which is found in the ,lias of ,england1 ,france1 and ,germany4#b ,this genus was before mentioned 7p4 #caf7 as occurring in the ,wealden1 and is supposed to have frequented both rivers and sea-coasts4 ,another genus of ,ganoids 7or fish with hard1 shining1 and enamelled scales71 called chmodus 7,fig4 #cgf71 is almost exclusively ,liassic4 ,the teeth of a species of ,acrodus1 also1 are very abundant in the ,lias 7,fig4 #cgg74 ,fig4 #cgg3 ,acrodus nobilis4 ,fig4 #cgh3 ,hybodus reticulatus1 a4 ,part of fin1 commonly called ,ichthyodorylite1 b4 ,tooth4 ,but the remains of fish which have excited more attention than any others are those large bony spines called ichthyodorulites 7a1 ,figure #cgh71 which were once supposed by some naturalists to be jaws1 and by others weapons1 resembling those of the living ,balistes and ,silurus2 but which ,m4 ,agassiz has shown to be neither the one nor the other4 ,the spines1 in the genera last mentioned1 articulate with the backbone1 whereas there are no signs of any such articulation in the ichthyodorulites4 ,fig4 #cgi3 ,chimra monstrosa4 ,fig4 #cgi3 ,chimra monstrosa4#c ,these last appear to have been bony spines which formed the anterior part of the dorsal fin1 like that of the living genera ,cestracion and ,chimra 7see a1 ,figure #cgi74 ,in both of these genera1 the posterior concave face is armed with small spines1 as in that of the fossil ,hybodus 7,fig4 #cgh71 a placoid fish of the shark family found fossil at ,lyme ,regis4 ,such spines are simply imbedded in the flesh1 and attached to strong muscles4 8,they serve10 says ,dr4 ,buckland1 8as in the ,chimra 7,fig4 #cgi71 to raise and depress the fin1 their action resembling that of a movable mast1 raising and lowering backward the sail of a barge40#d ,reptiles of the ,lias4--,it is not1 however1 the fossil fish which form the most striking feature in the organic remains of the ,lias2 but the ,enaliosaurian reptiles1 which are extraordinary for their number1 size1 and structure4 ,among the most singular of these are several species of ,ichthyosaurus and ,plesiosaurus 7,figs4 #chj1 #cha74 ,the genus ,ichthyosaurus1 or fish-lizard1 is not confined to this formation1 but has been found in strata as high as the ,white ,chalk of ,england1 and as low as the ,trias of ,germany1 a formation which immediately succeeds the ,lias in the descending order4 ,it is evident from their fish-like vertebr1 their paddles1 resembling those of a porpoise or whale1 the length of their tail1 and other parts of their structure1 that the ,ichthyosaurs were aquatic4 ,their jaws and teeth show that they were carnivorous2 and the half-digested remains of fishes and reptiles1 found within their skeletons1 indicate the precise nature of their food4 ,mr4 ,conybeare was enabled1 in #ahbd1 after examining many skeletons nearly perfect1 to give an ideal restoration of the osteology of this genus1 and of that of the ,plesiosaurus4#e 7,see ,figs4 #chj1 #cha47 ,the latter animal had an extremely long neck and small head1 with teeth like those of the crocodile1 and paddles analogous to those of the ,ichthyosaurus1 but larger4 ,it is supposed to have lived in shallow seas and estuaries1 and to have breathed air like the ,ichthyosaur and our modern cetacea4#f ,some of the reptiles above mentioned were of formidable dimensions4 ,one specimen of ,ichthyosaurus platydon1 from the ,lias at ,lyme1 now in the ,british ,museum1 must have belonged to an animal more than #bd feet in length2 and there are species of ,plesiosaurus which measure from #ah to #bj feet in length4 ,the form of the ,ichthyosaurus may have fitted it to cut through the waves like the porpoise2 as it was furnished besides its paddles with a tail-fin so constructed as to be a powerful organ of motion2 but it is supposed that the ,plesiosaurus1 at least the long-necked species 7,fig4 #cha71 was better suited to fish in shallow creeks and bays defended from heavy breakers4 ,it is now very generally agreed that these extinct saurians must have inhabited the sea2 and it was urged that as there are now chelonians1 like the tortoise1 living in fresh water1 and others1 as the turtle1 frequenting the ocean1 so there may have been formerly some saurians proper to salt1 others to fresh water4 ,the common crocodile of the ,ganges is well-known to frequent equally that river and the brackish and salt water near its mouth2 and crocodiles are said in like manner to be abundant both in the rivers of the ,isla de ,pinos 7,isle of ,pines71 south of ,cuba1 and in the open sea round the coast4 ,in #ahce a curious lizard 7,amblyrhynchus cristatus7 was discovered by ,mr4 ,darwin in the ,galapagos ,islands4#g ,it was found to be exclusively marine1 swimming easily by means of its flattened tail1 and subsisting chiefly on seaweed4 ,one of them was sunk from the ship by a heavy weight1 and on being drawn up after an hour was quite unharmed4 ,fig4 #chj3 ,skeleton of ,ichthyosaurus communis1 restored by ,conybeare and ,cuvier4 ,fig4 #cha3 ,skeleton of ,plesiosaurus dolichodeirus1 restored by ,rev4 ,w4 ,d4 ,conybeare4 ,the families of ,dinosauria1 crocodiles1 and ,pterosauria or winged reptiles1 are also represented in the ,lias4 ,sudden ,destruction of ,saurians4--,it has been remarked1 and truly1 that many of the fish and saurians1 found fossil in the ,lias1 must have met with sudden death and immediate burial2 and that the destructive operation1 whatever may have been its nature1 was often repeated4 8,sometimes10 says ,dr4 ,buckland1 8scarcely a single bone or scale has been removed from the place it occupied during life2 which could not have happened had the uncovered bodies of these saurians been left1 even for a few hours1 exposed to putrefaction1 and to the attacks of fishes and other smaller animals at the bottom of the sea40#h ,not only are the skeletons of the ,ichthyosaurs entire1 but sometimes the contents of their stomachs still remain between their ribs1 as before remarked1 so that we can discover the particular species of fish on which they lived1 and the form of their excrements4 ,not unfrequently there are layers of these coprolites1 at different depths in the ,lias1 at a distance from any entire skeletons of the marine lizards from which they were derived2 8as if10 says ,sir ,h4 ,de la ,beche1 8the muddy bottom of the sea received small sudden accessions of matter from time to time1 covering up the coprolites and other exuvi which had accumulated during the intervals40#i ,it is further stated that1 at ,lyme ,regis1 those surfaces only of the coprolites which lay uppermost at the bottom of the sea have suffered partial decay1 from the action of water before they were covered and protected by the muddy sediment that has afterwards permanently enveloped them4 ,numerous specimens of the ,calamary or pen-and-ink fish1 7,geoteuthis bollensis7 have also been met with in the ,lias at ,lyme1 with the ink-bags still distended1 containing the ink in a dried state1 chiefly composed of carbon1 and but slightly impregnated with carbonate of lime4 ,these ,cephalopoda1 therefore1 must1 like the saurians1 have been soon buried in sediment2 for1 if long exposed after death1 the membrane containing the ink would have decayed4#aj ,as we know that river-fish are sometimes stifled1 even in their own element1 by muddy water during floods1 it cannot be doubted that the periodical discharge of large bodies of turbid fresh water in the sea may be still more fatal to marine tribes4 ,in the 8,principles of ,geology0 ,i have shown that large quantities of mud and drowned animals have been swept down into the sea by rivers during earthquakes1 as in ,java in #afii2 and that indescribable multitudes of dead fishes have been seen floating on the sea after a discharge of noxious vapours during similar convulsions4 ,but in the intervals between such catastrophes1 strata may have accumulated slowly in the sea of the ,lias1 some being formed chiefly of one description of shell1 such as ammonites1 others of gryphites4 ,fig4 #chb3 ,wing of a neuropterous insect4 ,fresh-water ,deposits4--,insect-beds4--,from the above remarks the reader will infer that the ,lias is for the most part a marine deposit4 ,some members1 however1 of the series have an estuarine character1 and must have been formed within the influence of rivers4 ,at the base of the ,upper and ,lower ,lias respectively1 insect-beds appear to be almost everywhere present throughout the ,midland and ,south-western districts of ,england4 ,these beds are crowded with the remains of insects1 small fish1 and crustaceans1 with occasional marine shells4 ,one band in ,gloucestershire1 rarely exceeding a foot in thickness1 has been named the 8insect limestone40 ,it passes upward1 says the ,reverend ,p4 ,b4 ,brodie1#aa into a shale containing ,cypris and ,estheria1 and is full of the wing-cases of several genera of ,coleoptera1 with some nearly entire beetles1 of which the eyes are preserved4 ,the nervures of the wings of neuropterous insects 7,figure #chb7 are beautifully perfect in this bed4 ,ferns1 with ,cycads and leaves of monocotyledonous plants1 and some apparently brackish and fresh-water shells1 accompany the insects in several places1 while in others marine shells predominate1 the fossils varying apparently as we examine the bed nearer or farther from the ancient land1 or the source whence the fresh water was derived4 ,after studying #cjj specimens of these insects from the ,lias1 ,mr4 ,westwood declares that they comprise both wood-eating and herb-devouring beetles1 of the ,linnean genera ,elater1 ,carabus1 etc41 besides grasshoppers 7,gryllus71 and detached wings of dragon-flies and may-flies1 or insects referable to the ,linnean genera ,libellula1 ,ephemera1 ,hemerobius1 and ,panorpa1 in all belonging to no less than twenty-four families4 ,the size of the species is usually small1 and such as taken alone would imply a temperate climate2 but many of the associated organic remains of other classes must lead to a different conclusion4 ,fossil ,plants4--,among the vegetable remains of the ,lias1 several species of ,zamia have been found at ,lyme ,regis1 and the remains of coniferous plants at ,whitby4 ,m4 ,ad4 ,brongniart enumerates forty-seven liassic acrogens1 most of them ferns2 and fifty gymnosperms1 of which thirty-nine are cycads1 and eleven conifers4 ,among the cycads the predominance of ,zamites1 and among the ferns the numerous genera with leaves having reticulated veins 7as in ,fig4 #cdi71 are mentioned as botanical characteristics of this era4#ab ,the absence as yet from the ,lias and ,oolite of all signs of dicotyledonous angiosperms is worthy of notice4 ,the leaves of such plants are frequent in tertiary strata1 and occur in the ,cretaceous1 though less plentifully 7see p4 #cjc74 ,the angiosperms seem1 therefore1 to have been at the least comparatively rare in these older secondary periods1 when more space was occupied by the ,cycads and ,conifers4 ,origin of the ,oolite and ,lias4--,the entire group of ,oolite and ,lias consists of repeated alternations of clay1 sandstone1 and limestone1 following each other in the same order4 ,thus the clays of the ,lias are followed by the sands now considered 7see p4 #cec7 as belonging to the same formation1 though formerly referred to the ,inferior ,oolite1 and these sands again by the shelly and coralline limestone called the ,great or ,bath ,oolite4 ,so1 in the ,middle ,oolite1 the ,oxford ,clay is followed by calcareous grit and coral rag2 lastly1 in the ,upper ,oolite1 the ,kimmeridge ,clay is followed by the ,portland ,sand and limestone 7see ,fig4 #bih74ac ,the clay beds1 however1 as ,sir ,h4 de la ,beche remarks1 can be followed over larger areas than the sand or sandstones4#ad ,it should also be remembered that while the ,oolite system becomes arenaceous and resembles a coal-field in ,yorkshire1 it assumes in the ,alps an almost purely calcareous form1 the sands and clays being omitted2 and even in the intervening tracts it is more complicated and variable than appears in ordinary descriptions4 ,nevertheless1 some of the clays and intervening limestones do retain1 in reality1 a pretty uniform character for distances of from #djj to #fjj miles from east to west and north to south4 ,in order to account for such a succession of events1 we may imagine1 first1 the bed of the ocean to be the receptacle for ages of fine argillaceous sediment1 brought by oceanic currents1 which may have communicated with rivers1 or with part of the sea near a wasting coast4 ,this mud ceases1 at length1 to be conveyed to the same region1 either because the land which had previously suffered denudation is depressed and submerged1 or because the current is deflected in another direction by the altered shape of the bed of the ocean and neighbouring dry land4 ,by such changes the water becomes once more clear and fit for the growth of stony zoophytes4 ,calcareous sand is then formed from comminuted shell and coral1 or1 in some cases1 arenaceous matter replaces the clay2 because it commonly happens that the finer sediment1 being first drifted farthest from coasts1 is subsequently overspread by coarse sand1 after the sea has grown shallower1 or when the land1 increasing in extent1 whether by upheaval or by sediment filling up parts of the sea1 has approached nearer to the spots first occupied by fine mud4 ,the increased thickness of the limestones in those regions1 as in the ,alps and ,jura1 where the clays are comparatively thin1 arises from the calcareous matter having been derived from species of corals and other organic beings which live in clear water1 far from land1 to the growth of which the influx of mud would be unfavourable4 ,portions therefore of these clays and limestones have probably been formed contemporaneously to a greater extent than we can generally prove1 for the distinctness of the species of organic beings would be caused by the difference of conditions between the more littoral and the more pelagic areas and the different depths and nature of the sea-bottom4 ,independently of those ascending and descending movements which have given rise to the superposition of the limestones and clays1 and by which the position of land and sea are made in the course of ages to vary1 the geologist has the difficult task of allowing for the contemporaneous thinning out in one direction and thickening in another1 of the successive organic and inorganic deposits of the same era4 #a ,quart4 ,journ41 vol4 xvi1 p4 #cgf4 #b ,agassiz1 ,poissons ,fossiles1 vol4 ii1 tab4 #bh1 #bi4 #c ,agassiz1 ,poissons ,fossiles1 vol4 iii1 tab4 ,c1 ,fig4 #a4 #d ,bridgewater ,treatise1 p4 #bij4 #e ,geol4 ,soc4 ,transactions1 ,second ,series1 vol4 i1 p4 #di4 #f ,conybeare and ,de la ,beche1 ,geol4 ,trans41 ,first ,series1 vol4 v1 p4 #eei2 and ,buckland1 ,bridgewater ,treatise1 p4 #bjc4 #g ,see ,darwin1 ,naturalist's ,voyage1 p4 #che4 ,murray4 #h ,bridgewater ,treatise1 p4 #aae4 #i ,geological ,researches1 p4 #ccd4 #aj ,buckland1 ,bridgewater ,treatise1 p4 #cjg4 #aa ,a ,history of ,fossil ,insects1 etc41 #ahdf4 ,london4 #ab ,tableau des ,vg4 ,foss41 #ahdi1 p4 #aje4 #ac ,conybeare and ,philips's ,outlines1 etc41 p4 #aff4 #ad ,geological ,researches1 p4 #ccg4 ,,chapter ,,xxi4 ,,trias1 ,,or ,,new ,,red ,,sandstone ,,group4 ,beds of ,passage between the ,lias and ,trias1 ,rhtic ,beds4 -- ,triassic ,mammifer4 -- ,triple ,division of the ,trias4 -- ,keuper1 or ,upper ,trias of ,england4 -- ,reptiles of the ,upper ,trias4 -- ,foot-prints in the ,bunter formation in ,england4 -- ,dolomitic ,conglomerate of ,bristol4 -- ,origin of ,red ,sandstone and ,rock-salt4 -- ,precipitation of ,salt from inland ,lakes and ,lagoons4 -- ,trias of ,germany4 -- ,keuper4 -- ,st4 ,cassian and ,hallstadt ,beds4 -- ,peculiarity of their ,fauna4 -- ,muschelkalk and its ,fossils4 -- ,trias of the ,united ,states4 -- ,fossil ,foot-prints of ,birds and ,reptiles in the ,valley of the ,connecticut4 -- ,triassic ,mammifer of ,north ,carolina4 -- ,triassic ,coal-field of ,richmond1 ,virginia4 -- ,low ,grade of early ,mammals favourable to the ,theory of ,progressive ,development4 ,beds of ,passage between the ,lias and ,trias--,rhtic ,beds4--,we have mentioned in the last chapter 7p4 #cef7 that the base of the ,lower ,lias is characterised1 both in ,england and ,germany1 by beds containing distinct species of ,ammonites1 the lowest subdivision having been called the zone of ,ammonites planorbis4 ,below this zone1 on the boundary line between the ,lias and the strata of which we are about to treat1 called 8,trias10 certain cream-coloured limestones devoid of fossils are usually found4 ,these white beds were called by ,william ,smith the ,white ,lias1 and they have been shown by ,mr4 ,charles ,moore to belong to a formation similar to one in the ,rhtian ,alps of ,bavaria1 to which ,mr4 ,gumbel has applied the name of ,rhtic4 ,they have also long been known as the ,koessen beds in ,germany1 and may be regarded as beds of passage between the ,lias and ,trias4 ,they are named the ,penarth beds by the ,government surveyors of ,great ,britain1 from ,penarth1 near ,cardiff1 in ,glamorganshire1 where they sometimes attain a thickness of fifty feet4 ,the principal member of this group has been called by ,dr4 ,wright the ,avicula contorta bed1#a as this shell is very abundant1 and has a wide range in ,europe4 ,general ,portlock first described the formation as it occurs at ,portrush1 in ,antrim1 where the ,avicula contorta is accompanied by ,pecten ,valoniensis1 as in ,germany4 ,the best known member of the group1 a thin band or bone-breccia1 is conspicuous among the black shales in the neighbourhood of ,axmouth in ,devonshire1 and in the cliffs of ,westbury-on-,severn1 as well as at ,aust and other places on the borders of the ,bristol ,channel4 ,it abounds in the remains of saurians and fish1 and was formerly classed as the lowest bed of the ,lias2 but ,sir ,p4 ,egerton first pointed out1 in #ahda1 that it should be referred to the ,upper ,new ,red ,sandstone1 because it contained an assemblage of fossil fish which are either peculiar to this stratum1 or belong to species well-known in the ,muschelkalk of ,germany4 ,these fish belong to the genera ,acrodus1 ,hybodus1 ,gyrolepis1 and ,saurichthys4 ,fig4 #chc3 ,cardium rhticum4 ,fig4 #chd3 ,pecten ,valoniensis4 ,fig4 #che3 ,avicula contorta4 ,fig4 #chf3 ,hybodus plica ilis4 ,fig4 #chg3 ,saurichthys apicalis4 ,fig4 #chh3 ,gyrolepsis tenuistriatus4 ,among those common to the ,english bone-bed and the ,muschelkalk of ,germany are ,hybodus plicatilis 7,fig4 #chf71 ,saurychthys apicalis 7,fig4 #chg71 ,gyrolepis tenuistriatus 7,fig4 #chh71 and ,g4 ,albertii4 ,remains of saurians1 ,plesiosaurus among others1 have also been found in the bone-bed1 and plates of an ,encrinus4 ,it may be questioned whether some of those fossils which have the most ,triassic character may not have been derived from the destruction of older strata1 since in bone-beds1 in general1 many of the organic remains are undoubtedly derivative4 ,fig4 #chi3 ,microlestes antiquus1 molar tooth4 ,triassic ,mammifer4--,in ,north-western ,germany1 as in ,england1 there occurs beneath the ,lias a remarkable bone breccia4 ,it is filled with shells and with the remains of fishes and reptiles1 almost all the genera of which1 and some even of the species1 agree with those of the subjacent ,trias4 ,this breccia has accordingly been considered by ,professor ,quenstedt1 and other ,german geologists of high authority1 as the newest or uppermost part of the ,trias4 ,professor ,plieninger found in it1 in #ahdg1 the molar tooth of a small ,triassic mammifer1 called by him ,microlestes antiquus4 ,he inferred its true nature from its double fangs1 and from the form and number of the protuberances or cusps on the flat crown2 and considering it as predaceous1 probably insectivorous1 he called it ,microlestes from micros1 little1 and lestes1 a beast of prey4 ,soon afterwards he found a second tooth1 also at the same locality1 ,diegerloch1 about two miles to the south-east of ,stuttgart4 ,no anatomist had been able to give any feasible conjecture as to the affinities of this minute quadruped until ,dr4 ,falconer1 in #aheg1 recognised an unmistakable resemblance between its teeth and the two back molars of his new genus ,plagiaulax 7,fig4 #cjf71 from the ,purbeck strata4 ,this would lead us to the conclusion that ,microlestes was marsupial and plant-eating4 ,in ,wrtemberg there are two bone-beds1 namely1 that containing the ,microlestes1 which has just been described1 which constitutes1 as we have seen1 the uppermost member of the ,trias1 and another of still greater extent1 and still more rich in the remains of fish and reptiles1 which is of older date1 intervening between the ,keuper and ,muschelkalk4 ,the genera ,saurichthys1 ,hybodus1 and ,gyrolepis are found in both these breccias1 and one of the species1 ,saurichthys ,mongeoti1 is common to both bone-beds1 as is also a remarkable reptile called ,nothosaurus mirabilis4 ,the saurian called ,belodon by ,h4 von ,meyer1 of the ,thecodont family1 is another ,triassic form1 associated at ,diegerloch with ,microlestes4 ,,trias ,,of ,,england4 ,between the ,lias and the ,coal 7or ,carboniferous group7 there is interposed1 in the midland and western counties of ,england1 a great series of red loams1 shales1 and sandstones1 to which the name of the 8,new ,red ,sandstone formation0 was first given1 to distinguish it from other shales and sandstones called the 8,old ,red10 often identical in mineral character1 which lie immediately beneath the coal4 ,the name of 8,red ,marl0 has been incorrectly applied to the red clays of this formation1 as before explained 7p4 #ch71 for they are remarkably free from calcareous matter4 ,the absence1 indeed1 of carbonate of lime1 as well as the scarcity of organic remains1 together with the bright red colour of most of the rocks of this group1 causes a strong contrast between it and the ,jurassic formations before described4 ,the group in question is more fully developed in ,germany than in ,england or ,france4 ,it has been called the ,trias by ,german writers1 or the ,triple ,group1 because it is separable into three distinct formations1 called the 8,keuper10 the 8,muschelkalk10 and the 8,bunter-sandstein40 ,of these the middle division1 or the ,muschelkalk1 is wholly wanting in ,england1 and the uppermost 7,keuper7 and lowest 7,bunter7 members of the series are not rich in fossils4 ,upper ,trias or ,keuper4--,in certain grey indurated marls below the bone-bed ,mr4 ,boyd ,dawkins has found at ,watchet1 on the coast of ,somersetshire1 a molar tooth of ,microlestes1 enabling him to refer to the ,trias strata formerly supposed to be ,liassic4 ,mr4 ,charles ,moore had previously discovered many teeth of mammalia of the same family near ,frome1 in ,somersetshire1 in the contents of a vertical fissure traversing a mass of carboniferous limestone4 ,the top of this fissure must have communicated with the bed of the ,triassic sea1 and probably at a point not far from the ancient shore on which the small marsupials of that era abounded4 ,this upper division of the ,trias called the ,keuper is of great thickness in the central counties of ,england1 attaining1 according to ,mr4 ,hull's estimate1 no less than #cdej feet in ,cheshire1 and it covers a large extent of country between ,lancashire and ,devonshire4 ,in ,worcestershire and ,warwickshire in sandstone belonging to the uppermost part of the ,keuper the bivalve crustacean ,estheria minuta occurs4 ,the member of the ,english 8,new ,red0 containing this shell1 in those parts of ,england1 is1 according to ,sir ,roderick ,murchison and ,mr4 ,strickland1 #fjj feet thick1 and consists chiefly of red marl or slate1 with a band of sandstone4 ,ichthyodorulites1 or spines of ,hybodus1 teeth of fishes1 and footprints of reptiles were observed by the same geologists in these strata4 ,fig4 #cij3 ,estheria minuta4 ,fig4 #cia3 ,hyperodapedon ,gordoni4 ,left ,plate1 ,maxillary4 ,in the ,upper ,trias or ,keuper the remains of two saurians of the order ,lacertilia have been found4 ,the one called ,rhynchosaurus occurred at ,grinsell near ,shrewsbury1 and is characterised by having a small bird-like skull and jaws without teeth4 ,the other ,hyperodapedon 7,fig4 #cia7 was first noticed in #aheh1 near ,elgin1 in strata now recognised as ,upper ,triassic1 and afterwards in beds of about the same age in the neighbourhood of ,warwick4 ,remains of the same genus have been found both in ,central ,india and ,southern ,africa in rocks believed to be of ,triassic age4 ,the ,hyperodapedon has been shown by ,professor ,huxley to be a terrestrial reptile having numerous palatal teeth1 and closely allied to the living ,sphenodon of ,new ,zealand4 ,the recent discoveries of a living saurian in ,new ,zealand so closely allied to this supposed extinct division of the ,lacertilia seems to afford an illustration of a principle pointed out by ,mr4 ,darwin of the survival in insulated tracts1 after many changes in physical geography1 of orders of which the congeners have become extinct on continents where they have been exposed to the severer competition of a larger progressive fauna4 ,fig4 #cib3 ,tooth of ,labyrinthodon4 ,teeth of ,labyrinthodon 7,fig4 #cib7 found in the ,keuper in ,warwickshire were examined microscopically by ,professor ,owen1 and compared with other teeth from the ,german ,keuper4 ,he found after careful investigation that neither of them could be referred to true saurians1 although they had been named ,mastodonsaurus and ,phytosaurus by ,jger4 ,it appeared that they were of the ,batrachian order1 and of gigantic dimensions in comparison with any representatives of that order now living4 ,both the ,continental and ,english fossil teeth exhibited a most complicated texture1 differing from that previously observed in any reptile1 whether recent or extinct1 but most nearly analogous to the ,ichthyosaurus4 ,a section of one of these teeth exhibits a series of irregular folds1 resembling the labyrinthic windings of the surface of the brain2 and from this character ,professor ,owen has proposed the name ,labyrinthodon for the new genus4 ,fig4 #cic of part of one is given from his 8,odontography10 plate #fd1 ,a4 ,the entire length of this tooth is supposed to have been about three inches and a half1 and the breadth at the base one inch and a half4 ,fig4 #cic3 ,transverse section of upper part of tooth of ,labyrinthodon ,jaegeri4 ,rock-salt4--,in ,cheshire and ,lancashire there are red clays containing gypsum and salt of the age of the ,trias which are between #ajjj and #aejj feet thick4 ,in some places lenticular masses of pure rock-salt nearly #ajj feet thick are interpolated between the argillaceous beds4 ,at the base of the formation beneath the rock-salt occur the ,lower ,sandstones and ,marl1 called provincially in ,cheshire 8water-stones10 which are largely quarried for building4 ,they are often ripple-marked1 and are impressed with numerous footprints of reptiles4 ,the basement beds of the ,keuper rest with a slight unconformability upon an eroded surface of the 8,bunter0 next to be described4 ,fig4 #cid3 ,single footstep of ,cheirotherium4 ,lower ,trias or ,bunter4--,the lower division or ,english representative of the 8,bunter0 attains a thickness of #aejj feet in the counties last mentioned1 according to ,professor ,ramsay4 ,besides red and green shales and red sandstones1 it comprises much soft white quartzose sandstone1 in which the trunks of silicified trees have been met with at ,allesley ,hill1 near ,coventry4 ,several of them were a foot and a half in diameter1 and some yards in length1 decidedly of coniferous wood1 and showing rings of annual growth4#b ,impressions1 also1 of the footsteps of animals have been detected in ,lancashire and ,cheshire in this formation4 ,some of the most remarkable occur a few miles from ,liverpool1 in the whitish quartzose sandstone of ,storton ,hill1 on the west side of the ,mersey4 ,they bear a close resemblance to tracks first observed in this member of the ,upper ,new ,red ,sandstone1 at the village of ,hesseberg1 near ,hildburghausen1 in ,saxony4 ,for many years these footprints have been referred to a large unknown quadruped1 provisionally named ,cheirotherium by ,professor ,kaup1 because the marks both of the fore and hind feet resembled impressions made by a human hand4 7,see ,fig4 #cid47 ,the foot-marks at ,hesseberg are partly concave1 and partly in relief1 the former1 or the depressions1 are seen upon the upper surface of the sandstone slabs1 but those in relief are only upon the lower surfaces1 being1 in fact1 natural casts1 formed in the subjacent footprints as in moulds4 ,the larger impressions1 which seem to be those of the hind foot1 are generally eight inches in length1 and five in width1 and one was twelve inches long4 ,near each large footstep1 and at a regular distance 7about an inch and a half7 before it1 a smaller print of a fore foot1 four inches long and three inches wide1 occurs4 ,the footsteps follow each other in pairs1 each pair in the same line1 at intervals of fourteen inches from pair to pair4 ,the large as well as the small steps show the great toes alternately on the right and left side2 each step makes the print of five toes1 the first1 or great toe1 being bent inward like a thumb4 ,though the fore and hind foot differ so much in size1 they are nearly similar in form4 ,fig4 #cie3 ,line of footsteps on slab of sandstone4 ,as neither in ,germany nor in ,england had any bones or teeth been met with in the same identical strata as the footsteps1 anatomists indulged1 for several years1 in various conjectures respecting the mysterious animals from which they might have been derived4 ,professor ,kaup suggested that the unknown quadruped might have been allied to the ,marsupialia2 for in the kangaroo the first toe of the fore foot is in a similar manner set obliquely to the others1 like a thumb1 and the disproportion between the fore and hind feet is also very great4 ,but ,m4 ,link conceived that some of the four species of animals of which the tracks had been found in ,saxony might have been gigantic ,batrachians1 and when it was afterwards inferred that the ,labyrinthodon was an air-breathing reptile1 it was conjectured by ,professor ,owen that it might be one and the same as the ,cheirotherium4 ,dolomitic ,conglomerate of ,bristol4--,near ,bristol1 in ,somersetshire1 and in other counties bordering the ,severn1 the lowest strata belonging to the ,triassic series consist of a conglomerate or breccia resting unconformably upon the ,old ,red ,sandstone1 and on different members of the ,carboniferous rocks1 such as the ,coal ,measures1 ,millstone ,grit1 and ,mountain ,limestone4 ,this mode of superposition will be understood by reference to the section below ,dundry ,hill 7,fig4 #he71 where ,no4 #d is the dolomitic conglomerate4 ,such breccias may have been partly the result of the subrial waste of an old land-surface which gradually sank down and suffered littoral denudation in proportion as it became submerged4 ,the pebbles and fragments of older rocks which constitute the conglomerate are cemented together by a red or yellow base of dolomite1 and in some places the encrinites and other fossils derived from the ,mountain ,limestone are so detached from the parent rocks that they have the deceptive appearance of belonging to a fauna contemporaneous with the dolomitic beds in which they occur4 ,the imbedded fragments are both rounded and angular1 some consisting of sandstone from the coal-measures1 being of vast size1 and weighing nearly a ton4 ,fractured bones and teeth of saurians which are truly of contemporaneous origin are dispersed through some parts of the breccia1 and two of these reptiles called ,thecodont saurians1 named from the manner in which the teeth were implanted in the jawbone1 obtained great celebrity because the patches of red conglomerate in which they were found1 near ,bristol1 were originally supposed to be of ,permian or ,palozoic age1 and therefore the only representatives in ,england of vertebrate animals of so high a grade in rocks of such antiquity4 ,the teeth of these saurians are conical1 compressed1 and with finely serrated edges 7see ,fig4 #cif72 they are referred by ,professor ,huxley to the ,dinosaurian order4 ,fig4 #cif3 ,tooth of ,thecodontosaurus4 ,origin of ,red ,sandstone and ,rock-salt4--,in various parts of the world1 red and mottled clays and sandstones1 of several distinct geological epochs1 are found associated with salt1 gypsum1 and magnesian limestone1 or with one or all of these substances4 ,there is1 therefore1 in all likelihood1 a general cause for such a coincidence4 ,nevertheless1 we must not forget that there are dense masses of red and variegated sandstones and clays1 thousands of feet in thickness1 and of vast horizontal extent1 wholly devoid of saliferous or gypseous matter4 ,there are also deposits of gypsum and of common salt1 as in the blue-clay formation of ,sicily1 without any accompanying red sandstone or red clay4 ,these red deposits may be accounted for by the decomposition of gneiss and mica schist1 which in the eastern ,grampians of ,scotland has produced a mass of detritus of precisely the same colour as the ,old ,red ,sandstone4 ,it is a general fact1 and one not yet accounted for1 that scarcely any fossil remains are ever preserved in stratified rocks in which this oxide of iron abounds2 and when we find fossils in the ,new or ,old ,red ,sandstone in ,england1 it is in the grey1 and usually calcareous beds1 that they occur4 ,the saline or gypseous interstratified beds may have been produced by submarine gaseous emanations1 or hot mineral springs1 which often continue to flow in the same spots for ages4 ,beds of rock-salt are1 however1 more generally attributed to the evaporation of lakes or lagoons communicating at intervals with the ocean4 ,in ,cheshire two beds of salt occur of the extraordinary thickness of #ij or even #ajj feet1 and extending over an area supposed to be #aej miles in diameter4 ,the adjacent beds present ripple-marked sandstones and footprints of animals at so many levels as to imply that the whole area underwent a slow and gradual depression during the formation of the red sandstone4 ,major ,harris1 in his 8,highlands of ,ethiopia10 describes a salt lake1 called the ,bahr ,assal1 near the ,abyssinian frontier1 which once formed the prolongation of the ,gulf of ,tadjara1 but was afterwards cut off from the gulf by a broad bar of lava or of land upraised by an earthquake4 8,fed by no rivers1 and exposed in a burning climate to the unmitigated rays of the sun1 it has shrunk into an elliptical basin1 seven miles in its transverse axis1 half filled with smooth water of the deepest crulean hue1 and half with a solid sheet of glittering snow-white salt1 the offspring of evaporation40 8,if10 says ,mr4 ,hugh ,miller1 8we suppose1 instead of a barrier of lava1 that sand-bars were raised by the surf on a flat arenaceous coast during a slow and equable sinking of the surface1 the waters of the outer gulf might occasionally topple over the bar1 and supply fresh brine when the first stock had been exhausted by evaporation40 ,the ,runn of ,cutch1 as ,i have shown elsewhere1#c is a low region near the delta of the ,indus1 equal in extent to about a quarter of ,ireland1 which is neither land nor sea1 being dry during part of every year1 and covered by salt water during the monsoons4 ,here and there its surface is incrusted over with a layer of salt caused by the evaporation of sea-water4 ,a subsiding movement has been witnessed in this country during earthquakes1 so that a great thickness of pure salt might result from a continuation of such sinking4 ,,trias ,,of ,,germany4 ,in ,germany1 as before hinted1 chapter #ba1 the ,trias first received its name as a ,triple ,group1 consisting of two sandstones with an intermediate marine calcareous formation1 which last is wanting in ,england4 ,,nomenclature ,,of ,,trias4 ,german ,french ,english ,keuper ,marnes irises ,saliferous and gypseous shales and sandstone4 ,muschelkalk ,muschelkalk1 on calcaire coquillier ,wanting in ,england4 ,bunter-sandstein ,grs bigarr ,sandtone and quartzose conglomerate4 ,keuper4--,the first of these1 or the ,keuper1 underlying the beds before described as ,rhtic1 attains in ,wrtemberg a thickness of about #ajjj feet4 ,it is divided by ,alberti into sandstone1 gypsum1 and carbonaceous clay-slate4#d ,remains of reptiles called ,nothosaurus and ,phytosaurus1 have been found in it with ,labyrinthodon2 the detached teeth1 also1 of placoid fish and of ,rays1 and of the genera ,saurichthys and ,gyrolepis 7,figs4 #chg1 #chh74 ,the plants of the ,keuper are generically very analogous to those of the oolite and lias1 consisting of ferns1 equisetaceous plants1 cycads1 and conifers1 with a few doubtful monocotyledons4 ,a few species such as ,equisetites columnaris1 are common to this group and the oolite4 ,fig4 #cig3 ,equisetites columnaris4 ,st4 ,cassian and ,hallstadt ,beds 7see ,map1 ,fig4 #cih74-- ,the sandstones and clay of the ,keuper resemble the deposits of estuaries and a shallow sea near the land1 and afford1 in the ,n4,w4 of ,germany1 as in ,france and ,england1 but a scanty representation of the marine life of that period4 ,we might1 however1 have anticipated1 from its rich reptilian fauna1 that the contemporaneous inhabitants of the sea of the ,keuper period would be very numerous1 should we ever have an opportunity of bringing their remains to light4 ,this1 it is believed1 has at length been accomplished1 by the position now assigned to certain ,alpine rocks called the 8,st4 ,cassian beds10 the true place of which in the series was until lately a subject of much doubt and discussion4 ,it has been proved that the ,hallstadt beds on the northern flanks of the ,austrian ,alps correspond in age with the ,st4 ,cassian beds on their southern declivity1 and the ,austrian geologists1 ,m4 ,suess of ,vienna and others1 have satisfied themselves that the ,hallstadt formation is referable to the period of the ,upper ,trias4 ,assuming this conclusion to be correct1 we become acquainted suddenly and unexpectedly with a rich marine fauna belonging to a period previously believed to be very barren of organic remains1 because in ,england1 ,france1 and ,northern ,germany the upper ,trias is chiefly represented by beds of fresh or brackish water origin4 ,fig4 #cih3 ,map of ,tyrol and ,styria showing ,st4 ,cassian and ,hallstadt ,beds4 ,fig4 #cii3 ,scoliotoma4 ,fig4 #djj3 ,koninckia ,leonhardi4 ,about #fjj species of invertebrate fossils occur in the ,hallstadt and ,st4 ,cassian beds1 many of which are still undescribed2 some of the ,mollusca are of new and peculiar genera1 as ,scoliostoma1 ,fig4 #cii1 and ,platystoma1 ,fig4 #djj1 among the ,gasteropoda2 and ,koninckia1 ,fig4 #dja1 among the ,brachiopoda4 ,fig4 #dja3 ,koninckia ,leonhardi4 ,the following table of genera of marine shells from the ,hallstadt and ,st4 ,cassian beds1 drawn up first on the joint authority of ,m4 ,suess and the late ,dr4 ,woodward1 and since corrected by ,messrs4 ,etheridge and ,tate1 shows how many connecting links between the fauna of primary and secondary ,palozoic and ,mesozoic rocks are supplied by the ,st4 ,cassian and ,hallstadt beds4 ,,genera ,,of ,,fossil ,,mollusca ,,in ,,the ,,st4 ,,cassian ,,and ,,hallstadt ,,beds4 ,common to ,older ,rocks ,characteristic ,triassic ,genera ,common to ,newer ,rocks ,orthoceras ,bactrites ,macrocheilus ,loxonema ,holopella ,murchisonia ,porcellia ,athyris ,retzia ,cyrtina ,euomphalus ,ceratites ,cochloceras ,choristoceras ,rhabdoceras ,aulacoceras ,scoliostoma #e ,naticella ,platystoma ,ptychostoma ,euchrysalis ,halobia ,hornesia ,amphiclina ,koninckia ,cassianella #f ,myophoria #f ,ammonites ,chemnitzia ,cerithium ,monodonta ,opis ,sphoera ,cardita ,myoconcha ,hinnites ,monotis ,plicatula ,pachyrisma ,thecidium ,the first column marks the last appearance of several genera which are characteristic of ,palozoic strata4 ,the second shows those genera which are characteristic of the ,upper ,trias1 either as peculiar to it1 or1 as in the three cases marked by asterisks1 reaching their maximum of development at this era4 ,the third column marks the first appearance in ,triassic rocks of genera destined to become more abundant in later ages4 ,it is only1 however1 when we contemplate the number of species by which each of the above-mentioned genera are represented that we comprehend the peculiarities of what is commonly called the ,st4 ,cassian fauna4 ,thus1 for example1 the ,ammonite1 which is not common to older rocks1 is represented by no less than seventy-three species2 whereas ,loxonema1 which is only known as common to older rocks1 furnishes fifteen ,triassic species4 ,cerithium1 so abundant in tertiary strata1 and which still lives1 is represented by no less than fourteen species4 ,as the ,orthoceras had never been met with in the marine ,muschelkalk1 much surprise was naturally felt that seven or eight species of the genus should appear in the ,hallstadt beds1 assuming these last to belong to the ,upper ,trias4 ,among these species are some of large dimensions1 associated with large ,ammonites with foliated lobes1 a form never seen before so low in the series1 while the ,orthoceras had never been seen so high4 ,on the whole1 the rich marine fauna of ,hallstadt and ,st4 ,cassian1 now generally assigned to the lowest members of the ,upper ,trias or ,keuper1 leads us to suspect that when the strata of the ,triassic age are better known1 especially those belonging to the period of the ,bunter sandstone1 the break between the ,palozoic and ,mesozoic ,periods may be almost effaced4 ,indeed some geologists are not yet satisfied that the true position of the ,st4 ,cassian beds 7containing so great an admixture of types1 having at once both ,mesozoic and ,palozoic affinities7 is made out1 and doubt whether they have yet been clearly proved to be newer than the ,muschelkalk4 ,muschelkalk4--,the next member of the ,trias in ,germany1 the ,muschelkalk1 which underlies the ,keuper before described1 consists chiefly of a compact greyish limestone1 but includes beds of dolomite in many places1 together with gypsum and rock-salt4 ,this limestone1 a formation wholly unrepresented in ,england1 abounds in fossil shells1 as the name implies4 ,among the ,cephalopoda there are no belemnites1 and no ammonites with foliated sutures1 as in the ,lias1 and ,oolite1 and the ,hallstadt beds2 but we find instead a genus allied to the ,ammonite1 called ,ceratites by de ,haan1 in which the descending lobes 7,fig4 #djb7 terminate in a few small denticulations pointing inward4 ,among the bivalve crustacea1 the ,estheria minuta1 ,bronn 7see ,fig4 #cij71 is abundant1 ranging through the ,keuper1 ,muschelkalk1 and ,bunter-sandstein2 and ,gervillia socialis 7,fig4 #djc71 having a similar range1 is found in great numbers in the ,muschelkalk of ,germany1 ,france1 and ,poland4 ,fig4 #djb3 ,ceratites nodosus4 ,fig4 #djc3 ,gervillia 7,avicula7 socialis4 ,fig4 #djd3 ,enerinus liliiformis4 ,fig4 #dje3 ,aspidura loricata4 ,the abundance of the heads and stems of lily encrinites1 ,encrinus liliiformis 7,fig4 #djd71 7or ,encrinites moniliformis71 shows the slow manner in which some beds of this limestone have been formed in clear sea-water4 ,the star-fish called ,aspidura loricata 7,fig4 #dje7 is as yet peculiar to the ,muschelkalk4 ,in the same formation are found the skull and teeth of a reptile of the genus ,placodus 7see ,fig4 #djf71 which was referred originally by ,munster1 and afterwards by ,agassiz1 to the class of fishes4 ,but more perfect specimens enabled ,professor ,owen1 in #aheh1 to show that this fossil animal was a ,saurian reptile1 which probably fed on shell-bearing mollusks1 and used its short and flat teeth1 so thickly coated with enamel1 for pounding and crushing the shells4 ,fig4 #djf3 ,palatal teeth of ,placodus gigas4 ,fig4 #djg3 ,voltzia heterophylla4 ,bunter-sandstein4--,the ,bunter-sandstein consists of various-coloured sandstones1 dolomites1 and red clays1 with some beds1 especially in the ,hartz1 of calcareous pisolite or roe-stone1 the whole sometimes attaining a thickness of more than #ajjj feet4 ,the sandstone of the ,vosges is proved1 by its fossils1 to belong to this lowest member of the ,triassic group4 ,at ,sulzbad 7or ,soultz-les-bains71 near ,strasburg1 on the flanks of the ,vosges1 many plants have been obtained from the 8bunter10 especially conifers of the extinct genus ,voltzia1 of which the fructification has been preserved4 7,see ,fig4 #djg47 ,out of thirty species of ferns1 cycads1 conifers1 and other plants1 enumerated by ,m4 ,ad4 ,brongniart1 in #ahdi1 as coming from the 8,grs bigarr10 or ,bunter1 not one is common to the ,keuper4 ,the footprints of ,labyrinthodon observed in the clays of this formation at ,hildburghausen1 in ,saxony1 have already been mentioned4 ,some idea of the variety and importance of the terrestrial vertebrate fauna of the three members of the ,trias in ,northern ,germany may be derived from the fact that in the great monograph by the late ,hermann von ,meyer on the reptiles of the ,trias1 the remains of no less than eighty distinct species are described and figured4 ,,trias ,,of ,,the ,,united ,,states4 ,new ,red ,sandstone of the ,valley of the ,connecticut ,river4--,in a depression of the granitic or hypogene rocks in the ,states of ,massachusetts and ,connecticut strata of red sandstone1 shale1 and conglomerate are found1 occupying an area more than #aej miles in length from north to south1 and about five to ten miles in breadth1 the beds dipping to the eastward at angles varying from #e to #ej degrees4 ,the extreme inclination of #ej degrees is rare1 and only observed in the neighbourhood of masses of trap which have been intruded into the red sandstone while it was forming1 or before the newer parts of the deposit had been completed4 ,having examined this series of rocks in many places1 ,i feel satisfied that they were formed in shallow water1 and for the most part near the shore1 and that some of the beds were from time to time raised above the level of the water1 and laid dry1 while a newer series1 composed of similar sediment1 was forming4 ,fig4 #djh3 ,foot-prints of a bird1 ,turner's ,falls1 ,valley of the ,connecticut4 ,according to ,professor ,hitchcock1 the footprints of no less than thirty-two species of bipeds1 and twelve of quadrupeds1 have been already detected in these rocks4 ,thirty of these are believed to be those of birds1 four of lizards1 two of chelonians1 and six of batrachians4 ,the tracks have been found in more than twenty places1 scattered through an extent of nearly #hj miles from north to south1 and they are repeated through a succession of beds attaining at some points a thickness of more than #ajjj feet4#g ,the bipedal impressions are1 for the most part1 trifid1 and show the same number of joints as exist in the feet of living tridactylous birds4 ,now1 such birds have three phalangeal bones for the inner toe1 four for the middle1 and five for the outer one 7see ,fig4 #djh72 but the impression of the terminal joint is that of the nail only4 ,the fossil footprints exhibit regularly1 where the joints are seen1 the same number2 and we see in each continuous line of tracks the three-jointed and five-jointed toes placed alternately outward1 first on the one side1 and then on the other4 ,in some specimens1 besides impressions of the three toes in front1 the rudiment is seen of the fourth toe behind4 ,it is not often that the matrix has been fine enough to retain impressions of the integument or skin of the foot2 but in one fine specimen found at ,turner's ,falls1 on the ,connecticut1 by ,dr4 ,deane1 these markings are well preserved1 and have been recognised by ,professor ,owen as resembling the skin of the ostrich1 and not that of reptiles4 ,the casts of the footprints show that some of the fossil bipeds of the red sandstone of ,connecticut had feet four times as large as the living ostrich1 but scarcely1 perhaps1 larger than the ,dinornis of ,new ,zealand1 a lost genus of feathered giants related to the ,apteryx1 of which there were many species which have left their bones and almost entire skeletons in the superficial alluvium of that island4 ,by referring to what was said of the ,iguanodon of the ,wealden1 the reader will perceive that the ,dinosaur was somewhat intermediate between reptiles and birds1 and left a series of tridactylous impressions on the sand4 ,to determine the exact age of the red sandstone and shale containing these ancient footprints1 in the ,united ,states1 is not possible at present4 ,no fossil shells have yet been found in the deposit1 nor plants in a determinable state4 ,the fossil fish are numerous and very perfect2 but they are of a peculiar type1 called ,ischypterus1 by ,sir ,philip ,egerton1 from the great size and strength of the fulcral rays of the dorsal fin1 from ischus1 strength1 and pteron1 a fin4 ,the age of the ,connecticut beds cannot be proved by direct superposition1 but may be presumed from the general structure of the country4 ,that structure proves them to be newer than the movements to which the ,appalachian or ,allegheny chain owes its flexures1 and this chain includes the ancient or palozoic coal-formation among its contorted rocks4 ,coal-field of ,richmond1 ,virginia4--,in the ,state of ,virginia1 at the distance of about #ac miles eastward of ,richmond1 the capital of that ,state1 there is a coal-field occurring in a depression of the granite rocks1 and occupying a geological position analogous to that of the ,new ,red ,sandstone1 above-mentioned1 of the ,connecticut valley4 ,it extends #bf miles from north to south1 and from four to twelve from east to west4 ,the plants consist chiefly of zamites1 calamites1 equiseta1 and ferns1 and1 upon the whole1 are considered by ,professor ,heer to have the nearest affinity to those of the ,european ,keuper4 ,the equiseta are very commonly met with in a vertical position more or less compressed perpendicularly4 ,it is clear that they grew in the places where they are now buried in strata of hardened sand and mud4 ,i found them maintaining their erect attitude1 at points many miles apart1 in beds both above and between the seams of coal4 ,in order to explain this fact1 we must suppose such shales and sandstones to have been gradually accumulated during the slow and repeated subsidence of the whole region4 ,fig4 #dji3 ,triassic coal-shale1 ,richmond1 ,virginia4 ,the fossil fish are ,ganoids1 some of them of the genus ,catopterus1 others belonging to the liassic genus ,tetragonolepis 7chmodus71 see ,fig4 #cgf4 ,two species of ,entomostraca called ,estheria are in such profusion in some shaly beds as to divide them like the plates of mica in micaceous shales 7see ,fig4 #dji74 ,these ,virginian coal-measures are composed of grits1 sandstones1 and shales1 exactly resembling those of older or primary date in ,america and ,europe1 and they rival1 or even surpass1 the latter in the richness and thickness of the coal-seams4 ,one of these1 the main seam1 is in some places from #cj to #dj feet thick1 composed of pure bituminous coal4 ,the coal is like the finest kinds shipped at ,newcastle1 and when analysed yields the same proportions of carbon and hydrogen--a fact worthy of notice1 when we consider that this fuel has been derived from an assemblage of plants very distinct specifically1 and in part generically1 from those which have contributed to the formation of the ancient or palozoic coal4 ,triassic ,mammifer4--,in ,north ,carolina1 the late ,professor ,emmons has described the strata of the ,chatham coal-field1 which correspond in age to those near ,richmond1 in ,virginia4 ,in beds underlying them he has met with three jaws of a small insectivorous mammal which he has called ,dromatherium sylvestre1 closely allied to ,spalacotherium4 ,its nearest living analogue1 says ,professor ,owen1 8is found in ,myrmecobius2 for each ramus of the lower jaw contained ten small molars in a continuous series1 one canine1 and three conical incisors--the latter being divided by short intervals40 ,low ,grade of ,early ,mammals favourable to the ,theory of ,progressive ,development4--,there is every reason to believe that this fossil quadruped is at least as ancient as the ,microlestes of the ,european ,trias described in p4 #cfh2 and the fact is highly important1 as proving that a certain low grade of marsupials had not only a wide range in time1 from the ,trias to the ,purbeck1 or uppermost oolitic strata of ,europe1 but had also a wide range in space1 namely1 from ,europe to ,north ,america1 in an east and west direction1 and1 in regard to latitude1 from ,stonesfield1 in #eb ,n41 to that of ,north ,carolina1 #ce ,n4 ,if the three localities in ,europe where the most ancient mammalia have been found--,purbeck1 ,stonesfield1 and ,stuttgart--had belonged all of them to formations of the same age1 we might well have imagined so limited an area to have been peopled exclusively with pouched quadrupeds1 just as ,australia now is1 while other parts of the globe were inhabited by placentals2 for ,australia now supports one hundred and sixty species of marsupials1 while the rest of the continents and islands are tenanted by about seventeen hundred species of mammalia1 of which only forty-six are marsupial1 namely1 the opossums of ,north and ,south ,america4 ,but the great difference of age of the strata in each of these three localities seems to indicate the predominance throughout a vast lapse of time 7from the era of the ,upper ,trias to that of the ,purbeck beds7 of a low grade of quadrupeds2 and this persistency of similar generic and ordinal types in ,europe while the species were changing1 and while the fish1 reptiles1 and mollusca were undergoing great modifications1 would naturally lead us to suspect that there must also have been a vast extension in space of the same marsupial forms during that portion of the ,secondary or ,mesozoic epoch which has been termed 8the age of reptiles40 ,such an inference as to the wide geographical range of the ancient marsupials has been confirmed by the discovery in the ,trias of ,north ,america of the above-mentioned ,dromatherium4 ,the predominance in earlier ages of these mammalia of a low grade1 and the absence1 so far as our investigations have yet gone1 of species of higher organisation1 whether aquatic or terrestrial1 is certainly in favour of the theory of progressive development4 #a ,dr4 ,wright1 on ,lias and ,bone ,bed1 ,quart4 ,geol4 ,journ41 #ahfj1 vol4 xvi4 #b ,buckland1 ,proc4 ,geol4 ,soc41 vol4 ii1 p4 #dci2 and ,murchison and ,strickland1 ,geol4 ,trans41 ,second ,series41 vol4 v1 p4 #cdg4 #c ,principles of ,geology1 chap4 xxvii4 #d ,monog4 des ,bunter-,sandsteins4 #e ,reaches its maximum in the ,trias1 but passes down to older rocks4 #f ,reach their maximum in the ,trias1 but pass up to newer rocks4 #g ,hitchcock1 ,mem4 of ,amer4 ,acad41 ,new ,series1 vol4 iii1 p4 #abi1 #ahdh4 ,,primary ,,or ,,pal,,ozoic ,,series ,,chapter ,,xxii4 ,,permian ,,or ,,magnesian ,,limestone ,,group4 ,line of ,separation between ,mesozoic and ,palozoic ,rocks4 -- ,distinctness of ,triassic and ,permian ,fossils4 -- ,term ,permian4 -- ,thickness of calcareous and sedimentary ,rocks in ,north of ,england4 -- ,upper1 ,middle1 and ,lower ,permian4 -- ,marine ,shells and ,corals of the ,english ,magnesian ,limestone4 -- ,reptiles and ,fish of ,permian ,marl-slate4 -- ,foot-prints of ,reptiles4 -- ,angular ,breccias in ,lower ,permian4 -- ,permian ,rocks of the ,continent4 -- ,zechstein and ,rothliegendes of ,thuringia4 -- ,permian ,flora4 -- ,its generic ,affinity to the ,carboniferous4 ,in pursuing our examination of the strata in descending order1 we have next to pass from the base of the ,secondary or ,mesozoic to the uppermost or newest of the ,primary or ,palozoic formations4 ,as this point has been selected as a line of demarkation for one of the three great divisions of the fossiliferous series1 the student might naturally expect that by aid of lithological and palontological characters he would be able to recognise without difficulty a distinct break between the newer and older group4 ,but so far is this from being the case in ,great ,britain1 that nowhere have geologists found more difficulty in drawing the line of separation than between the ,secondary and ,primary series4 ,the obscurity has arisen from the great resemblance in colour and mineral character of the ,triassic and ,permian red marls and sandstones1 and the scarcity and often total absence in them of organic remains4 ,the thickness of the strata belonging to each group amounts in some places to several thousand feet2 and by dint of a careful examination of their geological position1 and of those fossil1 animal1 and vegetable forms which are occasionally met with in some members of each series1 it has at length been made clear that the older or ,permian rocks are more connected with the ,primary or ,palozoic than with the ,secondary or ,mesozoic strata already described4 ,the term ,permian has been proposed for this group by ,sir ,r4 ,murchison1 from ,perm1 a ,russian province1 where it occupies an area twice the size of ,france1 and contains a great abundance and variety of fossils1 both vertebrate and invertebrate4 ,professor ,sedgwick in #ahcba described what is now recognised as the central member of this group1 the ,magnesian limestone1 showing that it attained a thickness of #fjj feet along the north-east of ,england1 in the counties of ,durham1 ,yorkshire1 and ,nottinghamshire1 its lower part often passing into a fossiliferous marl-slate and resting on an inferior ,red ,sandstone1 the equivalent of the ,rothliegendes of ,germany4 ,it has since been shown that some of the ,red ,sandstones of newer date also belong to the ,permian group2 and it appears from the observations of ,mr4 ,binney1 ,sir ,r4 ,murchison1 ,mr4 ,harkness1 and others1 that it is in the region where the limestone is most largely developed1 as1 for example1 in the county of ,durham1 that the associated red sandstones or sedimentary rocks are thinnest1 whereas in the country where the latter are thickest the calcareous member is reduced to thirty1 or even sometimes to ten feet4 ,it is clear1 therefore1 says ,mr4 ,hull1 that the sedimentary region in the north of ,england area has been to the westward1 and the calcareous area to the eastward2 and that in this group there has been a development from opposite directions of the two types of strata4 ,in illustration of this he has given us the following table3 ,,thickness ,,of ,,permian ,,strata ,,in ,,north ,,of ,,england4 ,n4,w4 of ,england ,n4,e4 of ,england ,feet ,feet ,upper ,permian 7,sedimentary7 #fjj #ej-ajj ,middle ,permian 7,calcareous7 #aj-cj #fjj ,lower ,permian 7,sedimentary7 #cjjj #ajj-bejb ,upper ,permian4--,what is called in this table the ,upper ,permian will be seen to attain its chief thickness in the north-west1 or on the coast of ,cumberland1 as at ,st4 ,bee's ,head1 where it is described by ,sir ,roderick ,murchison as consisting of massive red sandstones with gypsum resting on a thin course of ,magnesian ,limestone with fossils1 which again is connected with the ,lower ,red ,sandstone1 resembling the upper one in such a manner that the whole forms a continuous series4 ,no fossil footprints have been found in this ,upper as in the ,lower ,red ,sandstone4 ,middle ,permian--,magnesian ,limestone and ,marl-slate4--,this formation is seen upon the coast of ,durham and ,yorkshire1 between the ,wear and the ,tees4 ,among its characteristic fossils are ,schizodus ,schlotheimi 7,fig4 #daj7 and ,mytilus septifer 7,fig4 #dab74 ,these shells occur at ,hartlepool and ,sunderland1 where the rock assumes an oolitic and botryoidal character4 ,some of the beds in this division are ripple-marked4 ,in some parts of the coast of ,durham1 where the rock is not crystalline1 it contains as much as #dd per cent of carbonate of magnesia1 mixed with carbonate of lime4 ,in other places--for it is extremely variable in structure--it consists chiefly of carbonate of lime1 and has concreted into globular and hemispherical masses1 varying from the size of a marble to that of a cannon-ball1 and radiating from the centre4 ,occasionally earthy and pulverulent beds pass into compact limestone or hard granular dolomite4 ,sometimes the limestone appears in a brecciated form1 the fragments which are united together not consisting of foreign rocks but seemingly composed of the breaking-up of the ,permian limestone itself1 about the time of its consolidation4 ,some of the angular masses in ,tynemouth cliff are two feet in diameter4 ,fig4 #daj3 ,schidozus ,schlotheimi1 ,permian crystalline limestone4 ,fig4 #daa3 ,the hinge of ,schizodus truncatus1 ,permian4 ,fig4 #dab3 ,mytilus septifer1 ,permian crystalline limestone4 ,the magnesian limestone sometimes becomes very fossiliferous and includes in it delicate bryozoa1 one of which1 ,fenestella retiformis 7,fig4 #dac71 is a very variable species1 and has received many different names4 ,it sometimes attains a large size1 single specimens measuring eight inches in width4 ,the same bryozoan1 with several other ,british species1 is also found abundantly in the ,permian of ,germany4 ,the total known fauna of the ,permian series of ,great ,britain at present numbers #adg species1 of which #gg1 or more than half1 are mollusca4 ,not one of these is common to rocks newer than the ,palozoic1 and the brachiopods are the only group which have furnished species common to the more ancient or ,carboniferous rocks4 ,of these ,lingula ,crednerii 7,fig4 #dae7 is an example4 ,there are #be ,gasteropods and only one cephalopod1 ,nautilus ,freieslebeni1 which is also found in the ,german ,zechstein4 ,fig4 #dac3 ,magnesian ,limestone4 ,fig4 #dac3 ,magnesian ,limestone1 ,humbleton ,hill1 near ,sunderland4#c ,shells of the genera ,productus 7,fig4 #dad7 and ,strophalosia 7the latter of allied form with hinge teeth71 which do not occur in strata newer than the ,permian1 are abundant in the ordinary yellow magnesian limestone1 as will be seen in the valuable memoirs of ,messrs4 ,king and ,howse4 ,they are accompanied by certain species of ,spirifera 7,fig4 #daf71 ,lingula ,crednerii 7,fig4 #dae71 and other brachiopoda of the true primary or palozoic type4 ,some of this same tribe of shells1 such as ,camarophoria1 allied to ,rhynchonella1 ,spiriferina1 and two species of ,lingula1 are specifically the same as fossils of the carboniferous rocks4 ,avicula1 ,arca1 and ,schizodus 7,fig4 #daj71 and other lamellibranchiate bivalves1 are abundant1 but spiral univalves are very rare4 ,fig4 #dad3 ,productus horridus4 ,fig4 #dae3 ,lingula ,crednerii4 ,fig4 #daf3 ,spirifera alata4 ,beneath the limestone lies a formation termed the marl-stone1 which consists of hard calcareous shales1 marl-slate1 and thin-bedded limestones4 ,at ,east ,thickley1 in ,durham1 where it is thirty feet thick1 this slate has yielded many fine specimens of fossil fish--of the genera ,paloniscus ten species1 ,pygopterus two species1 ,coelacanthus two species1 and ,platysomus two species1 which as genera are common to the older ,carboniferous formation1 but the ,permian species are peculiar1 and1 for the most part1 identical with those found in the marl-slate or copper-slate of ,thuringia4 ,fig4 #dag3 ,restored outline of a fish of the genus ,paloniscus4 ,fig4 #dah3 ,shark1 ,heterocercal4 ,fig4 #dai3 ,shad4 7,clupea4 ,herring tribe47 ,homocereal4 ,the ,paloniscus above mentioned belongs to that division of fishes which ,m4 ,agassiz has called 8,heterocercal10 which have their tails unequally bilobate1 like the recent shark and sturgeon1 and the vertebral column running along the upper caudal lobe4 7,see ,fig4 #dah47 ,the 8,homocercal0 fish1 which comprise almost all the #ijjj species at present known in the living creation1 have the tail-fin either single or equally divided2 and the vertebral column stops short1 and is not prolonged into either lobe4 7,see ,fig4 #dai47 ,now it is a singular fact1 first pointed out by ,agassiz1 that the heterocercal form1 which is confined to a small number of genera in the existing creation1 is universal in the magnesian limestone1 and all the more ancient formations4 ,it characterises the earlier periods of the earth's history1 whereas in the secondary strata1 or those newer than the ,permian1 the homocercal tail predominates4 ,a full description has been given by ,sir ,philip ,egerton of the species of fish characteristic of the marl-slate1 in ,professor ,king's monograph before referred to1 where figures of the ichthyolites1 which are very entire and well preserved1 will be found4 ,even a single scale is usually so characteristically marked as to indicate the genus1 and sometimes even the particular species4 ,they are often scattered through the beds singly1 and may be useful to a geologist in determining the age of the rock4 ,fig4 #dbj3 ,paloniscus comptus4 ,fig4 #dba3 ,paloniscus elegans4 ,fig4 #dbb3 ,paloniscus glaphyrus4 ,fig4 #dbc3 ,clacanthus granulatus4 ,fig4 #dbd3 ,pygopterus mandibularis4 ,fig4 #dbe3 ,acrolepis ,sedgwickii4 ,we are indebted to ,messrs4 ,hancock and ,howse for the discovery in this marl-slate at ,midderidge1 ,durham1 of two species of ,protosaurus1 a genus of reptiles1 one representative of which1 ,p4 ,speneri1 has been celebrated ever since the year #ahaj as characteristic of the ,kupfer-schiefer or ,permian of ,thuringia4 ,professor ,huxley informs us that the agreement of the ,durham fossil with ,hermann von ,meyer's figure of the ,german specimen is most striking4 ,although the head is wanting in all the examples yet found1 they clearly belong to the ,lacertian order1 and are therefore of a higher grade than any other vertebrate animal hitherto found fossil in a ,palozoic rock4 ,remains of ,labyrinthodont reptiles have also been met with in the same slate near ,durham4 ,lower ,permian4--,the inferior sandstones which lie beneath the marl-slate consist of sandstone and sand1 separating the ,magnesian ,limestone from the coal1 in ,yorkshire and ,durham4 ,in some instances1 red marl and gypsum have been found associated with these beds4 ,they have been classed with the ,magnesian ,limestone by ,professor ,sedgwick1 as being nearly co-extensive with it in geographical range1 though their relations are very obscure4 ,but the principal development of ,lower ,permian is1 as we have seen by ,mr4 ,hull's table p4 #chf1 in the northwest1 where the ,penrith sandstone1 as it has been called1 and the associated breccias and purple shales are estimated by ,professor ,harkness to attain a thickness of #cjjj feet4 ,organic remains are generally wanting1 but the leaves and wood of coniferous plants1 and in one case a cone1 have been found4 ,also in the purple marls of ,corncockle ,muir near ,dumfries1 very distinct footprints of reptiles occur1 originally referred to the ,trias1 but shown by ,mr4 ,binney in #ahef to be ,permian4 ,no bones of the animals which they represent have yet been discovered4 ,angular ,breccias in ,lower ,permian4--,a striking feature in these beds is the occasional occurrence1 especially at the base of the formation1 of angular and sometimes rounded fragments of ,carboniferous and older rocks of the adjoining districts being included in a paste of red marl4 ,some of the angular masses are of huge size4 ,in the central and southern counties1 where the ,middle ,permian or ,magnesian ,limestone is wanting1 it is difficult to separate the upper and lower sandstones1 and ,mr4 ,hull is of opinion that the patches of this formation found here and there in ,worcestershire1 ,shropshire1 and other counties may have been deposited in a sea separated from the northern basin by a barrier of ,carboniferous rocks running east and west1 and now concealed under the ,triassic strata of ,cheshire4 ,similar breccias to those before described are found in the more southern counties last mentioned1 where their appearance is rendered more striking by the marked contrast they present to the beds of well-rolled and rounded pebbles of the ,trias occupying a large area in the same region4 ,professor ,ramsay refers the angular form and large size of the fragments composing these breccias to the action of floating ice in the sea4 ,these masses of angular rock1 some of them weighing more than half a ton1 and lying confusedly in a red1 unstratified marl1 like stones in boulder-drift1 are in some cases polished1 striated1 and furrowed like erratic blocks in the moraine of a glacier4 ,they can be shown in some cases to have travelled from the parent rocks1 thirty or more miles distant1 and yet not to have lost their angular shape4#d ,permian ,rocks of the ,continent4--,germany is the classic ground of the ,magnesian ,limestone now called ,permian4 ,the formation was well studied by the miners of that country a century ago as containing a thin band of dark-coloured cupriferous shale1 characterised at ,mansfield in ,thuringia by numerous fossil fish4 ,beneath some variegated sandstones 7not belonging to the ,trias1 though often confounded with it7 they came down first upon a dolomitic limestone corresponding to the upper part of our ,middle ,permian1 and then upon a marl-slate richly impregnated with copper pyrites1 and containing fish and reptiles 7,protosaurus7 identical in species with those of the corresponding marl-slate of ,durham4 ,to the limestone they gave the name of ,zechstein1 and to the marl-slate that of ,mergel-schiefer or ,kupfer-schiefer4 ,beneath the fossiliferous group lies the ,rothliegendes or ,rothtodt-liegendes1 meaning the red-lyer or red-dead-lyer1 so-called by the ,german miners from its colour1 and because the copper had died out when they reached this underlying non-metalliferous member of the series4 ,this red under-lyer is1 in fact1 a great deposit of red sandstone1 breccia1 and conglomerate with associated porphyry1 basalt1 and amygdaloid4 ,according to ,sir ,r4 ,murchison1 the ,permian rocks are composed1 in ,russia1 of white limestone1 with gypsum and white salt2 and of red and green grits1 occasionally with copper ore2 also magnesian limestones1 marl-stones1 and conglomerates4 ,fig4 #dbf3 ,walchia piniformis4 ,permian ,flora4--,about #ah or #bj species of plants are known in the ,permian rocks of ,england4 ,none of them pass down into the ,carboniferous series1 but several genera1 such as ,alethopteris1 ,neuropteris1 ,walchia1 and ,ullmania1 are common to the two groups4 ,the ,permian flora on the ,continent appears1 from the researches of ,,mm4 ,murchison and de ,verneuil in ,russia1 and of ,,mm4 ,geinitz and von ,gutbier in ,saxony1 to be1 with a few exceptions1 distinct from that of the coal4 ,fig4 #bg3 ,cardiocarpon ,ottonis4 ,in the ,permian rocks of ,saxony no less than #fj species of fossil plants have been met with4 ,two or three of these1 as ,calamites gigas1 ,sphenopteris erosa1 and ,s4 lobata1 are also met with in the government of ,perm in ,russia4 ,seven others1 and among them ,neuropteris ,loshii1 ,pecopteris arborescens1 and ,p4 similis1 and several species of ,walchia 7see ,fig4 #dbf71 a genus of ,conifers1 called ,lycopodites by some authors1 are said by ,geinitz to be common to the coal-measures4 ,fig4 #dbh3 ,noeggerathia cuneifolia4 ,fig4 #dbh3 ,noeggerathia cuneifolia4 ,brongniart4#e ,among the genera also enumerated by ,colonel ,gutbier are the fruit called ,cardiocarpon 7see ,fig4 #dbg71 ,asterophyllites1 and ,annularia1 so characteristic of the ,carboniferous period2 also ,lepidodendron1 which is common to the ,permian of ,saxony1 ,thuringia1 and ,russia1 although not abundant4 ,neoggerathia 7see ,fig4 #dbh71 the leaves of which have parallel veins without a midrib1 and to which various generic synonyms1 such as ,cordaites1 ,flabellaria1 and ,poacites1 have been given1 is another link between the ,permian and ,carboniferous vegetation4 ,conifer1 of the ,araucarian division1 also occur2 but these are likewise met with both in older and newer rocks4 ,the plants called ,sigillaria and ,stigmaria1 so marked a feature in the ,carboniferous period1 are as yet wanting in the true ,permian4 ,among the remarkable fossils of the ,rothliegendes1 or lowest part of the ,permian in ,saxony and ,bohemia1 are the silicified trunks of tree-ferns called generically ,psaronius4 ,their bark was surrounded by a dense mass of air-roots1 which often constituted a great addition to the original stem1 so as to double or quadruple its diameter4 ,the same remark holds good in regard to certain living extra-tropical arborescent ferns1 particularly those of ,new ,zealand4 ,upon the whole1 it is evident that the ,permian plants approach much nearer to the ,carboniferous flora than to the ,triassic2 and the same may be said of the ,permian fauna4 #a ,trans4 ,geol4 ,soc4 ,lond41 ,second ,series1 vol4 iii1 p4 #cg4 #b ,edward ,hull1 ,ternary ,classification1 ,quart4 ,journ4 ,science1 ,no4 xxiii1 #ahfi4 #c ,king's ,monograph1 pl4 #b4 #d ,ramsay1 ,quart4 ,geol4 ,journ41 #ahee2 and ,lyell1 ,principles of ,geology1 vol4 i1 p4 #bbc1 #ajth edit4 #e ,murchison's ,russia1 vol4 ii1 pl4 ,a1 fig4 #c4 ,,chapter ,,xxiii4 ,,the ,,coal ,,or ,,carboniferous ,,group4 ,principal ,subdivisions of the ,carboniferous ,group4 -- ,different ,thickness of the sedimentary and calcareous ,members in ,scotland and the ,south of ,england4 -- ,coal-measures4 -- ,terrestrial ,nature of the ,growth of ,coal4 -- ,erect fossil ,trees4 -- ,uniting of many ,coal-seams into one thick ,bed4 -- ,purity of the ,coal explained4 -- ,conversion of ,coal into ,anthracite4 -- ,origin of ,clay-ironstone4 -- ,marine and brackish-water ,strata in ,coal4 -- ,fossil ,insects4 -- ,batrachian ,reptiles4 -- ,labyrinthodont ,foot-prints in ,coal-measures4 -- ,nova ,scotia ,coal-measures with successive ,growths of erect fossil ,trees4 -- ,similarity of ,american and ,european ,coal4 -- ,air-breathers of the ,american ,coal4 -- ,changes of ,condition of ,land and ,sea indicated by the ,carboniferous ,strata of ,nova ,scotia4 ,principal ,subdivisions of the ,carboniferous ,group4--,the next group which we meet with in the descending order is the ,carboniferous1 commonly called 8,the ,coal10 because it contains many beds of that mineral1 in a more or less pure state1 interstratified with sandstones1 shales1 and limestones4 ,the coal itself1 even in ,great ,britain and ,belgium1 where it is most abundant1 constitutes but an insignificant portion of the whole mass4 ,in ,south ,wales1 for example1 the thickness of the coal-bearing strata has been estimated at between #aa1jjj and #ab1jjj feet1 while the various coal seams1 about #hj in number1 do not1 according to ,professor ,phillips1 exceed in the aggregate #abj feet4 ,the ,carboniferous formation assumes various characters in different parts even of the ,british ,islands4 ,it usually comprises two very distinct members3 first1 the sedimentary beds1 usually called the ,coal-measures1 of mixed fresh-water1 terrestrial1 and marine origin1 often including seams of coal2 second1 that named in ,england the ,mountain or ,carboniferous ,limestone1 of purely marine origin1 and made up chiefly of corals1 shells1 and encrinites1 and resting on shales called the shales of the ,mountain ,limestone4 ,in the south-western part of our island1 in ,somersetshire and ,south ,wales1 the three divisions usually spoken of are3 ,coal-measures3 ,strata of shale1 sandstone1 and grit1 from #fjj to #ab1jjj feet thick1 with occasional seams of coal4 ,millstone grit3 ,a coarse quartzose sandstone passing into a conglomerate1 sometimes used for millstones1 with beds of shale2 usually devoid of coal2 occasionally above #fjj feet thick4 ,mountain or ,carboniferous ,limestone3 ,a calcareous rock containing marine shells1 corals1 and encrinites2 devoid of coal2 thickness variable1 sometimes more than #aejj feet4 ,if the reader will refer to the section in ,fig4 #he1 he will see that the ,upper and ,lower ,coal-measures of the coal-field near ,bristol are divided by a micaceous flaggy sandstone called the ,pennant ,rock4 ,the ,lower ,coal-measures of the same section rest sometimes1 especially in the north part of the basin1 on a base of coarse grit called the ,millstone ,grit 7,no4 #b on the previous page74 ,in the ,south ,welsh coal-field ,millstone ,grit occurs in like manner at the base of the productive coal4 ,it is called by the miners the 8,farewell ,rock10 as when they reach it they have no longer any hopes of obtaining coal at a greater depth in the same district4 ,in the central and northern coal-fields of ,england this same grit1 including quartz pebbles1 with some accompanying sandstones and shales containing coal plants1 acquires a thickness of several thousand feet1 lying beneath the productive coal-measures1 which are nearly #aj1jjj feet thick4 ,below the ,millstone ,grit is a continuation of similar sandstones and shales called by ,professor ,phillips the ,yoredale series1 from ,yoredale1 in ,yorkshire1 where they attain a thickness of from #hjj to #ajjj feet4 ,at several intervals bands of limestone divide this part of the series1 one of which1 called the ,main ,limestone or ,upper ,scar ,limestone1 composed in great part of encrinites1 is #gj feet thick4 ,thin seams of coal also occur in these lower ,yoredale beds in ,yorkshire1 showing that in the same region there were great alternations in the state of the surface4 ,for at successive periods in the same area there prevailed first terrestrial conditions favourable to the growth of pure coal1 secondly1 a sea of some depth suited to the formation of ,carboniferous ,limestone1 and1 thirdly1 a supply of muddy sediment and sand1 furnishing the materials for sandstone and shale4 ,there is no clear line of demarkation between the ,coal-measures and the ,millstone ,grit1 nor between the ,millstone ,grit and underlying ,yoredale rocks4 ,on comparing a series of vertical sections in a north-westerly direction from ,leicestershire and ,warwickshire into ,north ,lancashire1 we find1 says ,mr4 ,hull1 within a distance of #abj miles an augmentation of the sedimentary materials to the extent of #af1jjj feet4 ,leicestershire and ,warwickshire #b1fjj feet ,north ,staffordshire #i1jjj feet ,south ,lancashire #ab1acj feet ,north ,lancashire #ah1gjj feet ,in central ,england1 where the sedimentary beds are reduced to about #cjjj feet in all1 the ,carboniferous ,limestone attains an enormous thickness1 as much as #djjj feet at ,ashbourne1 near ,derby1 according to ,mr4 ,hull's estimate4 ,to a certain extent1 therefore1 we may consider the calcareous member of the formation as having originated simultaneously with the accumulation of the materials of grit1 sandstone1 and shale1 with seams of coal2 just as strata of mud1 sand1 and pebbles1 several thousand feet thick1 with layers of vegetable matter1 are now in the process of formation in the cypress swamps and delta of the ,mississippi1 while coral reefs are forming on the coast of ,florida and in the sea of the ,bermuda islands4 ,for we may safely conclude that in the ancient ,carboniferous ocean those marine animals which were limestone builders were never freely developed in areas where the rivers poured in fresh water charged with sand or clay2 and the limestone could only become several thousand feet thick in parts of the ocean which remained perfectly clear for ages4 ,the calcareous strata of the ,scotch coal-fields1 those of ,lanarkshire1 the ,lothians1 and ,fife1 for example1 are very insignificant in thickness when compared to those of ,england4 ,they consist of a few beds intercalated between the sandstones and shales containing coal and ironstone1 the combined thickness of all the limestones amounting to no more than #aej feet4 ,the vegetation of some of these northern sedimentary beds containing coal may be older than any of the coal-measures of central and southern ,england1 as being coeval with the ,mountain ,limestone of the south4 ,in ,ireland the limestone predominates over the coal-bearing sands and shales4 ,we may infer the former continuity of several of the coal-fields in northern and central ,england1 not only from the abrupt manner in which they are cut off at their outcrop1 but from their remarkable correspondence in the succession and character of particular beds4 ,but the limited extent to which these strata are exposed at the surface is not merely owing to their former denudation1 but even in a still greater degree to their having been largely covered by the ,new ,red ,sandstone1 as in ,cheshire1 and here and there by the ,permian strata1 as in ,durham4 ,it has long been the opinion of the most eminent geologists that the coal-fields of ,yorkshire and ,lancashire were once united1 the upper ,coal-measures and the overlying ,millstone ,grit and ,yoredale rocks having been subsequently removed2 but what is remarkable1 is the ancient date now assigned to this denudation1 for it seems that a thickness of no less than #aj1jjj feet of the coal-measures had been carried away before the deposition even of the lower ,permian rocks which were thrown down upon the already disturbed truncated edges of the coal-strata4#a ,the carboniferous strata most productive of workable coal have so often a basin-shaped arrangement that these troughs have sometimes been supposed to be connected with the original conformation of the surface upon which the beds were deposited4 ,but it is now admitted that this structure has been owing to movements of the earth's crust of upheaval and subsidence1 and that the flexure and inclination of the beds has no connection with the original geographical configuration of the district4 ,,coal-,,measures4 ,i shall now treat more particularly of the productive coal-measures1 and their mode of origin and organic remains4 ,coal formed on ,land4--,in ,south ,wales1 already alluded to1 where the coal-measures attain a thickness of #ab1jjj feet1 the beds throughout appear to have been formed in water of moderate depth1 during a slow1 but perhaps intermittent1 depression of the ground1 in a region to which rivers were bringing a never-failing supply of muddy sediment and sand4 ,the same area was sometimes covered with vast forests1 such as we see in the deltas of great rivers in warm climates1 which are liable to be submerged beneath fresh or salt water should the ground sink vertically a few feet4 ,in one section near ,swansea1 in ,south ,wales1 where the total thickness of strata is #cbdf feet1 we learn from ,sir ,h4 ,de la ,beche that there are ten principal masses of sandstone4 ,one of these is #ejj feet thick1 and the whole of them make together a thickness of #babe feet4 ,they are separated by masses of shale1 varying in thickness from #aj to #ej feet4 ,the intercalated coal-beds1 sixteen in number1 are generally from one to five feet thick1 one of them1 which has two or three layers of clay interposed1 attaining nine feet4 ,at other points in the same coal-field the shales predominate over the sandstones4 ,great as is the diversity in the horizontal extent of individual coal-seams1 they all present one characteristic feature1 in having1 each of them1 what is called its underclay4 ,these underclays1 co-extensive with every layer of coal1 consist of arenaceous shale1 sometimes called fire-stone1 because it can be made into bricks which stand the fire of a furnace4 ,they vary in thickness from six inches to more than ten feet2 and ,sir ,william ,logan first announced to the scientific world in #ahda that they were regarded by the colliers in ,south ,wales as an essential accompaniment of each of the eighty or more seams of coal met with in their coal-field4 ,they are said to form the floor on which the coal rests2 and some of them have a slight admixture of carbonaceous matter1 while others are quite blackened by it4 ,all of them1 as ,sir ,william ,logan pointed out1 are characterised by inclosing a peculiar species of fossil vegetable called ,stigmaria1 to the exclusion of other plants4 ,it was also observed that1 while in the overlying shales1 or 8roof0 of the coal1 ferns and trunks of trees abound without any ,stigmari1 and are flattened and compressed1 those singular plants of the underclay most commonly retain their natural forms1 unflattened and branching freely1 and sending out their slender rootlets1 formerly thought to be leaves1 through the mud in all directions4 ,several species of ,stigmaria had long been known to botanists1 and described by them1 before their position under each seam of coal was pointed out1 and before their true nature as the roots of trees 7some having been actually found attached to the base of ,sigillaria stumps7 was recognised4 ,it was conjectured that they might be aquatic1 perhaps floating plants1 which sometimes extended their branches and leaves freely in fluid mud1 in which they were finally enveloped4 ,now that all agree that these underclays are ancient soils1 it follows that in every instance where we find them they attest the terrestrial nature of the plants which formed the overlying coal1 which consists of the trunks1 branches1 and leaves of the same plants4 ,the trunks have generally fallen prostrate in the coal1 but some of them still remain at right angles to the ancient soils 7see ,fig4 #ddj74 ,professor ,goppert1 after examining the fossil vegetables of the coal-fields of ,germany1 has detected1 in beds of pure coal1 remains of plants of every family hitherto known to occur fossil in the carboniferous rocks4 ,many seams1 he remarks1 are rich in ,sigillari1 ,lepidodendra1 and ,stigmari1 the latter in such abundance as to appear to form the bulk of the coal4 ,in some places1 almost all the plants were calamites1 in others ferns4#b ,between the years #ahcg and #ahdj1 six fossil trees were discovered in the coal-fields of ,lancashire1 where it is intersected by the ,bolton railway4 ,they were all at right angles to the plane of the bed1 which dips about #ae degrees to the south4 ,the distance between the first and the last was more than #ajj feet1 and the roots of all were imbedded in a soft argillaceous shale4 ,in the same plane with the roots is a bed of coal1 eight or ten inches thick1 which has been found to extend across the railway1 or to the distance of at least ten yards4 ,just above the covering of the roots1 yet beneath the coal-seam1 so large a quantity of the ,lepidostrobus variabilis was discovered inclosed in nodules of hard clay1 that more than a bushel was collected from the small openings around the base of some of the trees 7see ,fig4 #deg of this genus74 ,the exterior trunk of each was marked by a coating of friable coal1 varying from one-quarter to three-quarters of an inch in thickness2 but it crumbled away on removing the matrix4 ,the dimensions of one of the trees is #ae feet in circumference at the base1 #g feet at the top1 its height being eleven feet4 ,all the trees have large spreading roots1 solid and strong1 sometimes branching1 and traced to a distance of several feet1 and presumed to extend much farther4 ,in a colliery near ,newcastle a great number of ,sigillari occur in the rock as if they had retained the position in which they grew4 ,no less than thirty1 some of them four or five feet in diameter1 were visible within an area of #ej yards square1 the interior being sandstone1 and the bark having been converted into coal4 ,such vertical stems are familiar to our coal-miners1 under the name of coal-pipes4 ,they are much dreaded1 for almost every year in the ,bristol1 ,newcastle1 and other coal-fields1 they are the cause of fatal accidents4 ,each cylindrical cast of a tree1 formed of solid sandstone1 and increasing gradually in size towards the base1 and being without branches1 has its whole weight thrown downward1 and receives no support from the coating of friable coal which has replaced the bark4 ,as soon1 therefore1 as the cohesion of this external layer is overcome1 the heavy column falls suddenly in a perpendicular or oblique direction from the roof of the gallery whence coal has been extracted1 wounding or killing the workman who stands below4 ,it is strange to reflect how many thousands of these trees fell originally in their native forests in obedience to the law of gravity2 and how the few which continued to stand erect1 obeying1 after myriads of ages1 the same force1 are cast down to immolate their human victims4 ,it has been remarked that if1 instead of working in the dark1 the miner was accustomed to remove the upper covering of rock from each seam of coal1 and to expose to the day the soils on which ancient forests grew1 the evidence of their former growth would be obvious4 ,thus in ,south ,staffordshire a seam of coal was laid bare in the year #ahdd1 in what is called an open work at ,parkfield colliery1 near ,wolverhampton4 ,in the space of about a quarter of an acre the stumps of no less than #gc trees with their roots attached appeared1 as shown in ,fig4 #dbi1 some of them more than eight feet in circumference4 ,the trunks1 broken off close to the root1 were lying prostrate in every direction1 often crossing each other4 ,one of them measured #ae1 another #cj feet in length1 and others less4 ,they were invariably flattened to the thickness of one or two inches1 and converted into coal4 ,their roots formed part of a stratum of coal ten inches thick1 which rested on a layer of clay two inches thick1 below which was a second forest resting on a two-foot seam of coal4 ,five feet below this1 again1 was a third forest with large stumps of ,lepidodendra1 ,calamites1 and other trees4 ,fig4 #dbi3 ,ground plan of fossil forest1 ,parkfield ,colliery1 near ,wolverhampton1 showing the position of #gc trees in a quarter of an ace4 ,blending of ,coal-seams4--,both in ,england and ,north ,america seams of coal are occasionally observed to be parted from each other by layers of clay and sand1 and1 after they have been persistent for miles1 to come together and blend in one single bed1 which is then found to be equal in the aggregate to the thickness of the several seams4 ,i was shown by ,mr4 ,h4 ,d4 ,rogers a remarkable example of this in ,pennsylvania4 ,in the ,shark ,mountain1 near ,pottsville1 in that ,state1 there are thirteen seams of anthracite coal1 some of them more than six feet thick1 separated by beds of white quartzose grit and a conglomerate of quartz pebbles1 often of the size of a hen's egg4 ,between ,pottsville and the ,lehigh ,summit ,mine1 seven of these seams of coal1 at first widely separated1 are1 in the course of several miles1 brought nearer and nearer together by the gradual thinning out of the intervening coarse-grained strata and their accompanying shales1 until at length they successively unite and form one mass of coal between forty and fifty feet thick1 very pure on the whole1 though with a few thin partings of clay4 ,this mass of coal ,i saw quarried in the open air at ,mauch ,chunk1 on the ,bear ,mountain4 ,the origin of such a vast thickness of vegetable remains1 so unmixed1 on the whole1 with earthy ingredients1 can be accounted for in no other way than by the growth1 during thousands of years1 of trees and ferns in the manner of peat--a theory which the presence of the ,stigmaria in situ under each of the seven layers of anthracite fully bears out4 ,the rival hypothesis1 of the drifting of plants into a sea or estuary1 leaves the non-intermixture of sediment1 or of clay1 sand1 and pebbles1 with the pure coal wholly unexplained4 ,the late ,mr4 ,bowman was the first who gave a satisfactory explanation of the manner in which distinct coal-seams1 after maintaining their independence for miles1 may at length unite1 and then persist throughout another wide area with a thickness equal to that which the separate seams had previously maintained4 ,fig4 #dcj3 ,uniting of distinct coal-seams4 ,let ,a ,c 7,fig4 #dcj7 be a three-foot seam of coal originally laid down as a mass of vegetable matter on the level area of an extensive swamp1 having an under-clay1 f g1 through which the ,stigmari or roots of the trees penetrate as usual4 ,one portion1 ,b ,c1 of this seam of coal is now inclined2 the area of the swamp having subsided as much as #be feet at ,e ,c1 and become for a time submerged under salt1 fresh1 or brackish water4 ,some of the trees of the original forest ,a ,b ,c fell down1 others continued to stand erect in the new lagoon1 their stumps and part of their trunks becoming gradually enveloped in layers of sand and mud1 which at length filled up the new piece of water ,c ,e4 ,when this lagoon has been entirely silted up and converted into land1 the forest-covered surface ,a ,b will extend once more over the whole area ,a ,b ,e1 and a second mass of vegetable matter1 ,d ,e1 forming three feet more of coal1 will accumulate4 ,we then find in the region ,e ,c two seams of coals1 each three feet thick1 with their respective under-clays1 with erect buried trees based upon the surface of the lower coal1 the two seams being separated by #be feet of intervening shale and sandstone4 ,whereas in the region ,a ,b1 where the growth of the forest has never been interrupted by submergence1 there will simply be one seam1 two yards thick1 corresponding to the united thickness of the beds ,b ,e and ,b ,c4 ,it may be objected that the uninterrupted growth of plants during the interval of time required for the filling up of the lagoon will have caused the vegetable matter in the region ,d ,a ,b to be thicker than the two distinct seams ,e and ,c1 and no doubt there would actually be a slight excess representing one or more generation of trees and plants forming the undergrowth2 but this excess of vegetable matter1 when compressed into coal1 would be so insignificant in thickness that the miner might still affirm that the seam ,d ,a throughout the area ,d ,a ,b was equal to the two seams ,c and ,e4 ,cause of the ,purity of ,coal4--,the purity of the coal itself1 or the absence in it of earthy particles and sand1 throughout areas of vast extent1 is a fact which appears very difficult to explain when we attribute each coal-seam to a vegetation growing in swamps4 ,it has been asked how1 during river inundations capable of sweeping away the leaves of ferns and the stems and roots of ,sigillari and other trees1 could the waters fail to transport some fine mud into the swamps8 ,one generation after another of tall trees grew with their roots in mud1 and their leaves and prostrate trunks formed layers of vegetable matter1 which was afterwards covered with mud since turned to shale4 ,yet the coal itself1 or altered vegetable matter1 remained all the while unsoiled by earthy particles4 ,this enigma1 however perplexing at first sight1 may1 ,i think1 be solved by attending to what is now taking place in deltas4 ,the dense growth of reeds and herbage which encompasses the margins of forest-covered swamps in the valley and delta of the ,mississippi is such that the fluviatile waters1 in passing through them1 are filtered and made to clear themselves entirely before they reach the areas in which vegetable matter may accumulate for centuries1 forming coal if the climate be favourable4 ,there is no possibility of the least intermixture of earthy matter in such cases4 ,thus in the large submerged tract called the 8,sunk ,country10 near ,new ,madrid1 forming part of the western side of the valley of the ,mississippi1 erect trees have been standing ever since the year #ahaa-ab1 killed by the great earthquake of that date2 lacustrine and swamp plants have been growing there in the shallows1 and several rivers have annually inundated the whole space1 and yet have been unable to carry in any sediment within the outer boundaries of the morass1 so dense is the marginal belt of reeds and brush-wood4 ,it may be affirmed that generally1 in the 8cypress swamps0 of the ,mississippi1 no sediment mingles with the vegetable matter accumulated there from the decay of trees and semi-aquatic plants4 ,as a singular proof of this fact1 ,i may mention that whenever any part of a swamp in ,louisiana is dried up1 during an unusually hot season1 and the wood set on fire1 pits are burnt into the ground many feet deep1 or as far down as the fire can descend without meeting with water1 and it is then found that scarcely any residuum or earthy matter is left4 ,at the bottom of all these 8cypress swamps0 a bed of clay is found1 with roots of the tall cypress 7,taxodium distichum71 just as the under-clays of the coal are filled with ,stigmaria4 ,conversion of ,coal into ,anthracite4--,it appears from the researches of ,liebig and other eminent chemists1 that when wood and vegetable matter are buried in the earth exposed to moisture1 and partially or entirely excluded from the air1 they decompose slowly and evolve carbonic acid gas1 thus parting with a portion of their original oxygen4 ,by this means they become gradually converted into lignite or wood-coal1 which contains a larger proportion of hydrogen than wood does4 ,a continuance of decomposition changes this lignite into common or bituminous coal1 chiefly by the discharge of carbureted hydrogen1 or the gas by which we illuminate our streets and houses4 ,according to ,bischoff1 the inflammable gases which are always escaping from mineral coal1 and are so often the cause of fatal accidents in mines1 always contain carbonic acid1 carbureted hydrogen1 nitrogen1 and olefiant gas4 ,the disengagement of all these gradually transforms ordinary or bituminous coal into anthracite1 to which the various names of glance-coal1 coke1 hard-coal1 culm1 and many others1 have been given4 ,there is an intimate connection between the extent to which the coal has in different regions parted with its gaseous contents1 and the amount of disturbance which the strata have undergone4 ,the coincidence of these phenomena may be attributed partly to the greater facility afforded for the escape of volatile matter1 when the fracturing of the rocks has produced an infinite number of cracks and crevices4 ,the gases and water which are made to penetrate these cracks are probably rendered the more effective as metamorphic agents by increased temperature derived from the interior4 ,it is well known that1 at the present period1 thermal waters and hot vapours burst out from the earth during earthquakes1 and these would not fail to promote the disengagement of volatile matter from the ,carboniferous rocks4 ,in ,pennsylvania the strata of coal are horizontal to the westward of the ,alleghany ,mountains1 where the late ,professor ,h4 ,d4 ,rogers pointed out that they were most bituminous2 but as we travel south-eastward1 where they no longer remain level and unbroken1 the same seams become progressively debitumenized in proportion as the rocks become more bent and distorted4 ,at first1 on the ,ohio ,river1 the proportion of hydrogen1 oxygen1 and other volatile matters ranges from forty to fifty per cent4 ,eastward of this line1 on the ,monongahela1 it still approaches forty per cent1 where the strata begin to experience some gentle flexures4 ,on entering the ,alleghany ,mountains1 where the distinct anticlinal axes begin to show themselves1 but before the dislocations are considerable1 the volatile matter is generally in the proportion of eighteen or twenty per cent4 ,at length1 when we arrive at some insulated coal-fields associated with the boldest flexures of the ,appalachian chain1 where the strata have been actually turned over1 as near ,pottsville1 we find the coal to contain only from six per cent of volatile matter1 thus becoming a genuine anthracite4 ,clay-ironstone4--,bands and nodules of clay-ironstone are common in coal-measures1 and are formed1 says ,sir ,h4 ,de la ,beche1 of carbonate of iron mingled mechanically with earthy matter1 like that constituting the shales4 ,mr4 ,hunt1 of the ,museum of ,practical ,geology1 instituted a series of experiments to illustrate the production of this substance1 and found that decomposing vegetable matter1 such as would be distributed through all coal strata1 prevented the further oxidation of the proto-salts of iron1 and converted the peroxide into protoxide by taking a portion of its oxygen to form carbonic acid4 ,such carbonic acid1 meeting with the protoxide of iron in solution1 would unite with it and form a carbonate of iron2 and this mingling with fine mud1 when the excess of carbonic acid was removed1 might form beds or nodules of argillaceous ironstone4#c ,intercalated ,marine ,beds in ,coal4--,both in the coal-fields of ,europe and ,america the association of fresh1 brackish-water1 and marine strata with coal-seams of terrestrial origin is frequently recognised4 ,thus1 for example1 a deposit near ,shrewsbury1 probably formed in brackish water1 has been described by ,sir ,r4 ,murchison as the youngest member of the coal-measures of that district1 at the point where they are in contact with the overlying ,permian group4 ,it consists of shales and sandstones about #aej feet thick1 with coal and traces of plants2 including a bed of limestone varying from two to nine feet in thickness1 which is cellular1 and resembles some lacustrine limestones of ,france and ,germany4 ,it has been traced for #cj miles in a straight line1 and can be recognised at still more distant points4 ,the characteristic fossils are a small bivalve1 having the form of a ,cyclas or ,cyrena1 also a small entomostracan1 ,cythere inflata 7,fig4 #dcb71 and the microscopic shell of an annelid of an extinct genus called ,microconchus 7,fig4 #dca71 allied to ,spirorbis4 ,in the coal-field of ,yorkshire there are fresh-water strata1 some of which contain shells referred to the family ,unionid2 but in the midst of the series there is one thin but very widely-spread stratum1 abounding in fishes and marine shells1 such as ,goniatites ,listeri 7,fig4 #dcc71 ,orthoceras1 and ,aviculopecten papyraceus1 ,goldf4 7,fig4 #dcd74 ,fig4 #dca3 ,microconchus 7,spirorbis7 carbonarius4 ,fig4 #dcb3 ,cythere 7,leperditia7 inflata4 ,fig4 #dcc3 ,goniatites ,listeri4 ,fig4 #dcd3 ,aviculopecten papyraceus4 ,insects in ,european ,coal4--,articulate animals of the genus ,scorpion were found by ,count ,sternberg in #ahce in the coal-measures of ,bohemia1 and about the same time in those of ,coalbrook ,dale by ,mr4 ,prestwich1 were also true insects1 such as beetles of the family ,curculionid1 a neuropterous insect of the genus ,corydalis1 and another related to the ,phasmid1 have been found4 ,from the coal of ,wetting1 in ,westphalia1 several specimens of the cockroach or ,blatta family1 and the wing of a cricket 7,acridites7 have been described by ,germar4 ,professor ,goldenberg published1 in #ahed1 descriptions of no less than twelve species of insects from the nodular clay-ironstone of ,saarbrck1 near ,trves4#d ,among them are several ,blattin1 three species of ,neuroptera1 one beetle of the ,scarabus family1 a grasshopper or locust1 ,gryllacris 7see ,fig4 #dce71 and several white ants or ,termites4 ,professor ,goldenberg showed me1 in #ahfd1 the wing of a white ant1 found low down in the productive coal-measures of ,saarbrck1 in the interior of a flattened ,lepidodendron4 ,it is much larger than that of any known living species of the same genus4 ,fig4 #dce3 ,wing of a ,grasshopper4 ,gryllacris lithanthraca4 ,fig4 #dcf3 ,archegosaurus minor4 ,fossil reptile from the coal-measures1 ,saarbrck4 ,batrachian ,reptiles in ,coal4--,no vertebrated animals more highly organised than fish were known in rocks of higher antiquity than the ,permian until the year #ahdd1 when the ,apateon pedestris1 ,meyer1 was discovered in the coal-measures of ,munster-,appel in ,rhenish ,bavaria1 and three years later1 in #ahdg1 ,professor von ,dechen found three other distinct species of the same family of ,amphibia in the ,saarbruck coal-field above alluded to4 ,these were described by the late ,professor ,goldfuss under the generic name of ,archegosaurus4 ,the skulls1 teeth1 and the greater portions of the skeleton1 nay1 even a large part of the skin1 of two of these reptiles have been faithfully preserved in the centre of spheroidal concretions of clay-ironstone4 ,the largest of these1 ,archegosaurus ,decheni1 must have been three feet six inches long4 ,figure #dcf represents the skull and neck bones of the smallest of the three1 of the natural size4 ,they were considered by ,goldfuss as saurians1 but by ,herman von ,meyer as most nearly allied to the ,labyrinthodon before mentioned 7p4 #cga71 and the remains of the extremities leave no doubt they were quadrupeds1 8provided10 says ,von ,meyer1 8with hands and feet terminating in distinct toes2 but these limbs were weak1 serving only for swimming or creeping40 ,the same anatomist has pointed out certain points of analogy between their bones and those of the ,proteus anguinus2 and ,professor ,owen has observed that they make an approach to the ,proteus in the shortness of their ribs4 ,two specimens of these ancient reptiles retain a large part of the outer skin1 which consisted of long1 narrow1 wedge-shaped1 tile-like1 and horny scales1 arranged in rows 7see ,fig4 #dcg74 ,fig4 #dcg3 ,imbricated covering of skin of ,archegosaurus medius4 ,in #ahfe1 several species belonging to three different genera of the same family of perennibranchiate ,batrachians were found in the coal-field of ,kilkenny in bituminous shale at the junction of the coal with the underlying ,stigmaria-bearing clay4 ,they were1 probably1 inhabitants of a marsh1 and the large processes projecting from the vertebr of their tail imply1 according to ,professor ,huxley1 great powers of swimming4 ,they were of the ,labyrinthodont family1 and their association with the fish of the coal1 of which so large a proportion are ganoids1 reminds us that the living perennibranchiate amphibia of ,america frequent the same rivers as the ganoid ,lepidostei or bony pikes4 ,labyrinthodont footprints in coal-measures4--,in #ahdd1 the very year when the ,apateon1 before mentioned1 of the coal was first met with in the country between the ,moselle and the ,rhine1 ,dr4 ,king published an account of the footprints of a large reptile discovered by him in ,north ,america4 ,these occur in the coal-strata of ,greensburg1 in ,westmoreland ,county1 ,pennsylvania2 and ,i had an opportunity of examining them when in that country in #ahdf4 ,the footmarks were first observed standing out in relief from the lower surface of slabs of sandstone1 resting on thin layers of fine unctuous clay4 ,i brought away one of these masses1 which is represented in ,fig4 #dch4 ,it displays1 together with footprints1 the casts of cracks 7a1 a7 of various sizes4 ,the origin of such cracks in clay1 and casts of the same1 has before been explained1 and referred to the drying and shrinking of mud1 and the subsequent pouring of sand into open crevices4 ,it will be seen that some of the cracks1 as at b1 c1 traverse the footprints1 and produce distortion in them1 as might have been expected1 for the mud must have been soft when the animal walked over it and left the impressions2 whereas1 when it afterwards dried up and shrank1 it would be too hard to receive such indentations4 ,fig4 #dch3 ,slab of sandstone from the coal-measures of ,pennsylvania1 with foot-prints of air-breathing reptile and casts of cracks4 ,we may assume that the reptile which left these prints on the ancient sands of the coal-measures was an air-breather1 because its weight would not have been sufficient under water to have made impressions so deep and distinct4 ,the same conclusion is also borne out by the casts of the cracks above described1 for they show that the clay had been exposed to the air and sun1 so as to have dried and shrunk4 ,nova ,scotia ,coal-measures4--,the sedimentary strata in which thin seams of coal occur attain a thickness1 as we have seen1 of #ah1jjj feet in the north of ,england exclusive of the ,mountain ,limestone1 and are estimated by ,von ,dechen at over #bj1jjj feet in ,rhenish ,prussia4 ,but the finest example in the world of a natural exposure in a continuous section ten miles long1 occurs in the sea-cliffs bordering a branch of the ,bay of ,fundy1 in ,nova ,scotia4 ,these cliffs1 called the 8,south ,joggins10 which ,i first examined in #ahdb1 and afterwards with ,dr4 ,dawson in #ahde1 have lately been admirably described by the last-mentioned geologist#e in detail1 and his evidence is most valuable as showing how large a portion of this dense mass was formed on land1 or in swamps where terrestrial vegetation flourished1 or in fresh-water lagoons4 ,his computation of the thickness of the whole series of carboniferous strata as exceeding three miles1 agrees with the measurement made independently by ,sir ,william ,logan in his survey of this coast4 ,there is no reason to believe that in this vast succession of strata1 comprising some marine as well as many fresh-water and terrestrial formations1 there is any repetition of the same beds4 ,there are no faults to mislead the geologist1 and cause him to count the same beds over more than once1 while some of the same plants have been traced from the top to the bottom of the whole series1 and are distinct from the flora of the antecedent ,devonian formation of ,canada4 ,eighty-one seams of coal1 varying in thickness from an inch to about five feet1 have been discovered1 and no less than seventy-one of these have been actually exposed in the sea-cliffs4 ,in the section 7,fig4 #dci71 which ,i examined in #ahdb1 the beds from c to i are seen all dipping the same way1 their average inclination being at an angle of #bd ,s4,s4,w4 ,the vertical height of the cliffs is from #aej to #bjj feet2 and between d and g--in which space ,i observed seventeen trees in an upright position1 or1 to speak more correctly1 at right angles to the planes of stratification--,i counted nineteen seams of coal1 varying in thickness from two inches to four feet4 ,at low tide a fine horizontal section of the same beds is exposed to view on the beach1 which at low tide extends sometimes #bjj yards from the base of the cliff4 ,the thickness of the beds alluded to1 between d and g1 is about #bejj feet1 the erect trees consisting chiefly of large ,sigillari1 occurring at ten distinct levels1 one above the other4 ,the usual height of the buried trees seen by me was from six to eight feet2 but one trunk was about #be feet high and four feet in diameter1 with a considerable bulge at the base4 ,in no instance could ,i detect any trunk intersecting a layer of coal1 however thin2 and most of the trees terminated downward in seams of coal4 ,some few only were based on clay and shale2 none of them1 except ,calamites1 on sandstone4 ,the erect trees1 therefore1 appeared in general to have grown on beds of vegetable matter4 ,in the underclays ,stigmaria abounds4 ,fig4 #dci3 ,section of the cliffs of the ,south ,joggins1 near ,minudie1 ,nova ,scotia4 ,these root-bearing beds have been found under all the coal-seams1 and such old soils are at present the most destructible masses in the whole cliff1 the sandstones and laminated shales being harder and more capable of resisting the action of the waves and the weather4 ,originally the reverse was doubtless true1 for in the existing delta of the ,mississippi those clays in which the innumerable roots of the deciduous cypress and other swamp trees ramify in all directions are seen to withstand far more effectually the undermining power of the river1 or of the sea at the base of the delta1 than do beds of loose sand or layers of mud not supporting trees4 ,it is obvious that if this sand or mud be afterwards consolidated and turned to sandstone and hard shale1 it would be the least destructible4 ,in regard to the plants1 they belonged to the same genera1 and most of them to the same species1 as those met with in the distant coal-fields of ,europe4 ,dr4 ,dawson has enumerated more than #aej species1 two-thirds of which are ,european1 a greater agreement than can be said to exist between the same ,nova ,scotia flora and that of the coal-fields of the ,united ,states4 ,by referring to the section1 ,fig4 #dci1 the position of the four-foot coal will be perceived1 and in ,fig4 #ddj 7a section made by me in #ahdb of a small portion7 that from e to f of the same cliff is exhibited1 in order to show the manner of occurrence of erect fossil trees at right angles to the planes of the inclined strata4 ,fig4 #ddj3 ,erect fossil trees1 ,coal-measures1 ,nova ,scotia4 ,in the sandstone which filled their interiors1 ,i frequently observed fern-leaves1 and sometimes fragments of ,stigmaria1 which had evidently entered together with sediment after the trunk had decayed and become hollow1 and while it was still standing under water4 ,thus the tree1 a1 ,fig4 #ddj1 represented in the bed e in the section1 ,fig4 #dci1 is a hollow trunk five feet eight inches in length1 traversing various strata1 and cut off at the top by a layer of clay two feet thick1 on which rests a seam of coal 7b1 ,fig4 #ddj7 one foot thick4 ,on this coal again stood two large trees 7c and d71 while at a greater height the trees f and g rest upon a thin seam of coal 7e71 and above them is an underclay1 supporting the four-foot coal4 ,occasionally the layers of matter in the inside of the tree are more numerous than those without2 but it is more common in the coal-measures of all countries to find a cylinder of pure sandstone--the cast of the interior of a tree--intersecting a great many alternating beds of shale and sandstone1 which originally enveloped the trunk as it stood erect in the water4 ,such a want of correspondence in the materials outside and inside1 is just what we might expect if we reflect on the difference of time at which the deposition of sediment will take place in the two cases2 the imbedding of the tree having gone on for many years before its decay had made much progress4 ,in many places distinct proof is seen that the enveloping strata took years to accumulate1 for some of the sandstones surrounding erect sigillarian trunks support at different levels roots and stems of ,calamites2 the ,calamites having begun to grow after the older ,sigillari had been partially buried4 ,the general absence of structure in the interior of the large fossil trees of the ,coal implies the very durable nature of their bark1 as compared with their woody portion4 ,the same difference of durability of bark and wood exists in modern trees1 and was first pointed out to me by ,dr4 ,dawson1 in the forests of ,nova ,scotia1 where the ,canoe ,birch 7,betula papyracea7 has such tough bark that it may sometimes be seen in the swamps looking externally sound and fresh1 although consisting simply of a hollow cylinder with all the wood decayed and gone4 ,when portions of such trunks have become submerged in the swamps they are sometimes found filled with mud4 ,one of the erect fossil trees of the ,south ,joggins fifteen feet in height1 occurring at a higher level than the main coal1 has been shown by ,dr4 ,dawson to have a coniferous structure1 so that some ,conifer of the ,coal period grew in the same swamps as ,sigillari1 just as now the deciduous ,cypress 7,taxodium distichum7 abounds in the marshes of ,louisiana even to the edge of the sea4 ,when the carboniferous forests sank below high-water mark1 a species of ,spirorbis or ,serpula 7,fig4 #dca71 attached itself to the outside of the stumps and stems of the erect trees1 adhering occasionally even to the interior of the bark--another proof that the process of envelopment was very gradual4 ,these hollow upright trees1 covered with innumerable marine annelids1 reminded me of a 8cane-brake10 as it is commonly called1 consisting of tall reeds1 ,arundinaria macrosperma1 which ,i saw in #ahdf1 at the ,balize1 or extremity of the delta of the ,mississippi4 ,although these reeds are fresh-water plants1 they were covered with barnacles1 having been killed by an incursion of salt-water over an extent of many acres1 where the sea had for a season usurped a space previously gained from it by the river4 ,yet the dead reeds1 in spite of this change1 remained standing in the soft mud1 enabling us to conceive how easily the larger ,sigillari1 hollow as they were but supported by strong roots1 may have resisted an incursion of the sea4 ,the high tides of the ,bay of ,fundy1 rising more than #fj feet1 are so destructive as to undermine and sweep away continually the whole face of the cliffs1 and thus a new crop of erect fossil trees is brought into view every three or four years4 ,they are known to extend over a space between two and three miles from north to south1 and more than twice that distance from east to west1 being seen in the banks of streams intersecting the coal-field4 ,structure of ,coal4--,the bituminous coal of ,nova ,scotia is similar in composition and structure to that of ,great ,britain1 being chiefly derived from sigillarioid trees mixed with leaves of ferns and of a ,lycopodiaceous tree called ,cordaites 7,noeggerathia1 etc41 for genus1 see ,fig4 #dbh71 supposed by ,dawson to have been deciduous1 and which had broad parallel veined leaves without a mid-rib4 ,on the surface of the seams of coal are large quantities of mineral charcoal1 which doubtless consist1 as ,dr4 ,dawson suggests1 of fragments of wood which decayed in the open air1 as would naturally be expected in swamps where so many erect trees were preserved4 ,beds of cannel-coal display1 says ,dr4 ,dawson1 such a microscopical structure and chemical composition as shows them to have been of the nature of fine vegetable mud such as accumulates in the shallow ponds of modern swamps4 ,the underclays are loamy soils1 which must have been sufficiently above water to admit of drainage1 and the absence of sulphurets1 and the occurrence of carbonate of iron in them1 prove that when they existed as soils1 rain-water1 and not sea-water1 percolated them4 ,with the exception1 perhaps1 of ,asterophyllites 7see ,fig4 #dfa71 there is a remarkable absence from the coal-measures of any form of vegetation properly aquatic1 the true coal being a sub-arial accumulation in soil that was wet and swampy but not permanently submerged4 ,air-breathers of the ,coal4--,if we have rightly interpreted the evidence of the former existence at more than eighty different levels of forests of trees1 some of them of vast extent1 and which lasted for ages1 giving rise to a great accumulation of vegetable matter1 it is natural to ask whether there were not many air-breathing inhabitants of these same regions4 ,as yet no remains of mammalia or birds have been found1 a negative character common at present to all the ,palozoic formations2 but in #aheb the osseous remains of a reptile1 the first ever met with in the carboniferous strata of the ,american continent1 were found by ,dr4 ,dawson and myself4 ,we detected them in the interior of one of the erect ,sigillari before alluded to as of such frequent occurrence in ,nova ,scotia4 ,the tree was about two feet in diameter1 and consisted of an external cylinder of bark1 converted into coal1 and an internal stony axis of black sandstone1 or rather mud and sand stained black by carbonaceous matter1 and cemented together with fragments of wood into a rock4 ,these fragments were in the state of charcoal1 and seem to have fallen to the bottom of the hollow tree while it was rotting away4 ,the skull1 jaws1 and vertebr of a reptile1 probably about #b feet in length 7,dendrerpeton ,acadianum1 ,owen71 were scattered through this stony matrix4 ,the shell1 also1 of a ,pupa 7see ,fig4 #ddb71 the first land-shell ever met with in the coal or in beds older than the tertiary1 was observed in the same stony mass4 ,dr4 ,wyman of ,boston pronounced the reptile to be allied in structure to ,menobranchus and ,menopoma1 species of batrachians1 now inhabiting the ,north ,american rivers4 ,the same view was afterwards confirmed by ,professor ,owen1 who also pointed out the resemblance of the cranial plates to those seen in the skull of ,archegosaurus and ,labyrinthodon4#f ,whether the creature had crept into the hollow tree while its top was still open to the air1 or whether it was washed in with mud during a flood1 or in whatever other manner it entered1 must be matter of conjecture4 ,footprints of two reptiles of different sizes had previously been observed by ,dr4 ,harding and ,dr4 ,gesner on ripple-marked flags of the lower coal-measures in ,nova ,scotia 7,no4 #b1 ,fig4 #ddg71 evidently made by quadrupeds walking on the ancient beach1 or out of the water1 just as the recent ,menopoma is sometimes observed to do4 ,the remains of a second and smaller species of ,dendrerpeton1 ,d4 ,oweni1 were also found accompanying the larger one1 and still retaining some of its dermal appendages2 and in the same tree were the bones of a third small lizard-like reptile1 ,hylonomus ,lyelli1 seven inches long1 with stout hind limbs1 and fore limbs comparatively slender1 supposed by ,dr4 ,dawson to be capable of walking and running on land4#g ,fig4 #dda3 ,xylobius ,sigillari4 ,coal1 ,nova ,scotia4 ,in a second specimen of an erect stump of a hollow tree #ae inches in diameter1 the ribbed bark of which showed that it was a ,sigillaria1 and which belonged to the same forest as the specimen examined by us in #aheb1 ,dr4 ,dawson obtained not only fifty specimens of ,pupa vetusta 7,fig4 #ddb71 and nine skeletons of reptiles belonging to four species1 but also several examples of an articulated animal resembling the recent centipede or gally-worm1 a creature which feeds on decayed vegetable matter 7see ,fig4 #dda74 ,under the microscope1 the head1 with the eyes1 mandible1 and labrum1 are well seen4 ,it is interesting1 as being the earliest known representative of the myriapods1 none of which had previously been met with in rocks older than the oolite or lithographic slate of ,germany4 ,fig4 #ddb3 ,pupa vetusta4 ,some years after the discovery of the first ,pupa1 ,dr4 ,dawson1 carefully examining the same great section containing so many buried forests in the cliffs of ,nova ,scotia1 discovered another bed1 separated from the tree containing ,dendrerpeton by a mass of strata more than #abjj feet thick4 ,as there were #ba seams of coal in this intervening mass1 the length of time comprised in the interval is not to be measured by the mere thickness of the sandstones and shales4 ,this lower bed is an underclay seven feet thick1 with stigmarian rootlets1 and the small land-shells occurring in it are in all stages of growth4 ,they are chiefly confined to a layer about two inches thick1 and are unmixed with any aquatic shells4 ,they were all originally entire when imbedded1 but are most of them now crushed1 flattened1 and distorted by pressure2 they must have been accumulated1 says ,dr4 ,dawson1 in mud deposited in a pond or creek4 ,fig4 #ddc3 ,zonites 7,conulus7 priseus4 ,the surface stri of ,pupa vetusta1 when magnified #ej diameters1 present exactly the same appearance as a portion corresponding in size of the common ,english ,pupa juniperi1 and the internal hexagonal cells1 magnified #ejj diameters1 show the internal structure of the fossil and recent ,pupa to be identical4 ,in #ahffh ,dr4 ,dawson discovered in this lower bed1 so full of the ,pupa1 another land-shell of the genus ,helix 7sub-genus ,zonites71 see ,fig4 #ddc4 ,none of the reptiles obtained from the coal-measures of the ,south ,joggins are of a higher grade than the ,labyrinthodonts1 but some of these were of very great size1 two caudal vertebr found by ,mr4 ,marsh in #ahfb measuring two and a half inches in diameter1 and implying a gigantic aquatic reptile with a powerful swimming tail4 ,except some obscure traces of an insect found by ,dr4 ,dawson in a coprolite of a terrestrial reptile occurring in a fossil tree1 no specimen of this class has been brought to light in the ,joggins4 ,but ,mr4 ,james ,barnes found in a bed of shale at ,little ,grace ,bay1 ,cape ,breton1 the wing of an ,ephemera1 which must have measured seven inches from tip to tip of the expanded wings--larger than any known living insect of the ,neuropterous family4 ,that we should have made so little progress in obtaining a knowledge of the terrestrial fauna of the ,coal is certainly a mystery1 but we have no reason to wonder at the extreme rarity of insects1 seeing how few are known in the carboniferous rocks of ,europe1 worked for centuries before ,america was discovered1 and now quarried on so enormous a scale4 ,these ,european rocks have not yet produced a single land-shell1 in spite of the millions of tons of coal annually extracted1 and the many hundreds of soils replete with the fossil roots of trees1 and the erect trunks and stumps preserved in the position in which they grew4 ,in many large coal-fields we continue as much in the dark respecting the invertebrate air-breathers then living1 as if the coal had been thrown down in mid-ocean4 ,the early date of the carboniferous strata cannot explain the enigma1 because we know that while the land supported a luxuriant vegetation1 the contemporaneous seas swarmed with life--with ,articulata1 ,mollusca1 ,radiata1 and ,fishes4 ,the perplexity in which we are involved when we attempt to solve this problem may be owing partly to our want of diligence as collectors1 but still more perhaps to ignorance of the laws which govern the fossilisation of land-animals1 whether of high or low degree4 ,carboniferous ,rain-prints4--,at various levels in the coal measures of ,nova ,scotia1 ripple-marked sandstones1 and shales with rain-prints1 were seen by ,dr4 ,dawson and myself1 but still more perfect impressions of rain were discovered by ,mr4 ,brown1 near ,sydney1 in the adjoining island of cape ,breton4 ,they consist of very delicate markings on greenish slates1 accompanied by worm-tracks 7a1 b1 ,fig4 #ddd71 such as are often seen between high and low water mark on the recent mud of the ,bay of ,fundy4 ,the great humidity of the climate of the ,coal period had been previously inferred from the number of its ferns and the continuity of its forests for hundreds of miles2 but it is satisfactory to have at length obtained such positive proofs of showers of rain1 the drops of which resembled in their average size those which now fall from the clouds4 ,from such data we may presume that the atmosphere of the ,carboniferous period corresponded in density with that now investing the globe1 and that different currents of air varied then as now in temperature1 so as to give rise1 by their mixture1 to the condensation of aqueous vapour4 ,fig4 #ddd3 ,carboniferous rain-prints with worm tracks on green shale1 from ,cape ,breton1 ,nova ,scotia4 ,fig4 #dde3 ,casts of rain-prints on a portion of the same slab 7,fig4 #ddd71 seen to project on the underside of an incumbent layer of arenaceous shale4 ,folding and ,denudation of the ,beds indicated by the ,nova ,scotia ,coal-strata4--,the series of events which are indicated by the great section of the coal-strata in ,nova ,scotia consist of a gradual and long-continued subsidence of a tract which throughout most of the period was in the state of a delta1 though occasionally submerged beneath a sea of moderate depth4 ,deposits of mud and sand were first carried down into a shallow sea on the low shores of which the footprints of reptiles were sometimes impressed 7see p4 #djg74 ,fig4 #ddf3 ,cone and branch of ,lepidodendron corrugatum4 ,though no regular seams of coal were formed1 the characteristic imbedded coal-plants are of the genera ,cyclopteris and ,alethopteris1 agreeing with species occurring at much higher levels1 and distinct from those of the antecedent ,devonian group4 ,the ,lepidodendron corrugatum 7see ,fig4 #ddf71 a plant predominating in the ,lower ,carboniferous group of ,europe1 is also conspicuous in these shallow-water beds1 together with many fishes and entomostracans4 ,a more rapid rate of subsidence sometimes converted part of the sea into deep clear water1 in which there was a growth of coral which was afterwards turned into crystalline limestone1 and parts of it1 apparently by the action of sulphuric acid1 into gypsum4 ,in spite of continued sinking1 amounting to several thousand feet1 the sea might in time have been rendered shallow by the growth of coral1 had not its conversion into land or swampy ground been accelerated by the pouring in of sand and the advance of the delta accompanied with such fluviatile and brackish-water formations as are common in lagoons4 ,the amount to which the bed of the sea sank down in order to allow of the formation of so vast a thickness of rock of sedimentary and organic origin is expressed by the total thickness of the ,carboniferous strata1 including the coal-measures1 ,no4 #a1 and the rocks which underlie them1 ,no4 #b1 ,fig4 #ddg4 ,fig4 #ddg3 ,diagram showing the curvature and supposed denudation of the ,carboniferous strata in ,nova ,scotia4 ,after the strata ,no4 #b had been elaborated1 the conditions proper to a great delta exclusively prevailed1 the subsidence still continuing so that one forest after another grew and was submerged until their under-clays with roots1 and usually seams of coal1 were left at more than eighty distinct levels4 ,here and there1 also1 deposits bearing testimony to the existence of fresh or brackish-water lagoons1 filled with calcareo-bituminous mud1 were formed4 ,in these beds 7h and i1 ,fig4 #dci7 are found fresh-water bivalves or mussels allied to ,anodon1 though not identical with that or any living genus1 and called ,naiadites carbonarius by ,dawson4 ,they are associated with small entomostracous crustaceans of the genus ,cythere1 and scales of small fishes4 ,occasionally some of the calamite brakes and forests of ,sigillari and ,conifer were exposed in the flood season1 or sometimes1 perhaps1 by slight elevatory movements to the denuding action of the river or the sea4 ,in order to interpret the great coast section exposed to view on the shores of the ,bay of ,fundy1 the student must1 in the first place1 understand that the newest or last-mentioned coal formations would have been the only ones known to us 7for they would have covered all the others71 had there not been two great movements in opposite directions1 the first consisting of a general sinking of three miles1 which took place during the ,carboniferous ,period1 and the second an upheaval of more limited horizontal extent1 by which the anticlinal axis ,a was formed4 ,that the first great change of level was one of subsidence is proved by the fact that there are shallow-water deposits at the base of the ,carboniferous series1 or in the lowest beds of ,no4 #b4 ,subsequent movements produced in the ,nova ,scotia and the adjoining ,new ,brunswick coal-fields the usual anticlinal and synclinal flexures4 ,in order to follow these1 we must survey the country for about thirty miles round the ,south ,joggins1 or the region where the erect trees described in the foregoing pages are seen4 ,as we pass along the cliffs for miles in a southerly direction1 the beds containing these fossil trees1 which were mentioned as dipping about #ah south1 are less and less inclined1 until they become nearly horizontal in the valley of a small river called the ,shoulie1 as ascertained by ,dr4 ,dawson4 ,after passing this synclinal line the beds begin to dip in an opposite or north-easterly direction1 acquiring a steep dip where they rest unconformably on the edges of the ,upper ,silurian strata of the ,cobequid ,hills1 as shown in ,fig4 #ddg4 ,but if we travel northward towards ,minudie from the region of the coal-seams and buried forests1 we find the dip of the coal-strata increasing from an angle of #ah to one of more than #dj1 lower beds being continually exposed to view until we reach the anticlinal axis ,a and see the lower ,carboniferous formation1 ,no4 #b1 at the surface4 ,the missing rocks removed by denudation are expressed by the faint lines at ,a1 and thus the student will see that1 according to the principles laid down in the seventh chapter1 we are enabled1 by the joint operations of upheaval and denudation1 to look1 as it were1 about three miles into the interior of the earth without passing beyond the limits of a single formation4 #a ,edward ,hull1 ,quart4 ,geol4 ,journ41 vol4 xxiv1 p4 #cbg4 #b ,quart4 ,geol4 ,journ41 vol4 v1 ,mem41 p4 #ag4 #c ,memoirs of the ,geol4 ,survey1 pp4 #ea1 #bee1 etc4 #d ,dunker and ,v4 ,meyer1 ,palont41 vol4 iv1 p4 #ag4 #e ,acadian ,geology1 #bnd edit41 #ahfh4 #f ,quart4 ,geol4 ,journ41 vol4 ix1 p4 #eh4 #g ,dawson1 ,air-,breathers of the ,coal in ,nova ,scotia1 ,montreal1 #ahfc4 #h ,dawson1 ,acadian ,geology1 #ahfh1 p4 #che4 ,,chapter ,,xxiv4 ,,flora ,,and ,,fauna ,,of ,,the ,,carboniferous ,,period4 ,vegetation of the ,coal ,period4 -- ,ferns1 ,lycopodiace1 ,equisetace1 ,sigillari1 ,stigmari1 ,conifer4 -- ,angiosperms4 -- ,climate of the ,coal ,period4 -- ,mountain ,limestone4 -- ,marine ,fauna of the ,carboniferous ,period4 -- ,corals4 -- ,bryozoa1 ,crinoidea4 -- ,mollusca4 -- ,great ,number of fossil ,fish4 -- ,foraminifera4 ,vegetation of the ,coal ,period4--,in the last chapter we have seen that the seams of coal1 whether bituminous or anthracitic1 are derived from the same species of plants1 and ,goppert has ascertained that the remains of every family of plants scattered through the shales and sandstones of the coal-measures are sometimes met with in the pure coal itself--a fact which adds greatly to the geological interest of this flora4 ,the coal-period was called by ,adolphe ,brongniart the age of ,acrogens1#a so great appears to have been the numerical preponderance of flowerless or cryptogamic plants of the families of ferns1 club-mosses1 and horse-tails4 ,he reckoned the known species in #ahdi at #ejj1 and the number has been largely increased by recent research in spite of reductions owing to the discovery that different parts of even the same plants had been taken for distinct species4 ,notwithstanding these changes1 ,brongniart's generalisation concerning this flora still holds true1 namely1 that the state of the vegetable world was then extremely different from that now prevailing1 not only because the cryptogamous plants constituted nearly the whole flora1 but also because they were1 on the whole1 more highly developed than any belonging to the same class now existing1 and united some forms of structure now only found separately and in distinct orders4 ,the only phnogamous plants were constitute any feature in the coal are the conifer2 monocotyledonous angiosperms appear to have been very rare1 and the dicotyledonous1 with one or two doubtful exceptions1 were wanting4 ,for this we are in some measure prepared by what we have seen of the ,secondary or ,mesozoic floras if1 consistently with the belief in the theory of evolution1 we expect to find the prevalence of simpler and less specialised organisms in older rocks4 ,ferns4--,we are struck at the first glance with the similarity of the ferns to those now living4 ,in the fossil genus ,pecopteris1 for example 7,fig4 #ddh71 it is not easy to decide whether the fossils might not be referred to the same genera as those established for living ferns2 whereas1 in regard to some of the other contemporary families of plants1 with the exception of the fir tribe1 it is not easy to guess even the class to which they belong4 ,the ferns of the ,carboniferous period are generally without organs of fructification1 but in the few instances in which these do occur in a fit state for microscopical investigations they agree with those of the living ferns4 ,fig4 #ddh3 ,pecopteris elliptica4 ,fig4 #ddi3 ,caulopteris primva4 ,fig4 #ddh3 ,pecopteris elliptica1 ,bunbury4#b ,frostburg4 ,fig4 #ddi3 ,caulopteris primva1 ,lindley4 ,when collecting fossil specimens from the coal-measures of ,frostburg1 in ,maryland1 ,i found in the iron-shales several species with well-preserved rounded spots or marks of the sori 7see ,fig4 #ddh74 ,in the general absence of such characters they have been divided into genera distinguished chiefly by the branching of the fronds and the way in which the veins of the leaves are disposed4 ,the larger portion are supposed to have been of the size of ordinary ,european ferns1 but some were decidedly arborescent1 especially the group called ,caulopteris 7see ,fig4 #ddi7 by ,lindley1 and the ,psaronius of the upper or newest coal-measures1 before alluded to 7p4 #cic74 ,all the recent tree-ferns belong to one tribe 7,polypodiace71 and to a small number only of genera in that tribe1 in which the surface of the trunk is marked with scars1 or cicatrices1 left after the fall of the fronds4 ,these scars resemble those of ,caulopteris4 ,no less than #acj species of ferns are enumerated as having been obtained from the ,british coal-strata1 and this number is more than doubled if we include the ,continental and ,american species4 ,even if we make some reduction on the ground of varieties which have been mistaken1 in the absence of their fructification1 for species1 still the result is singular1 because the whole of ,europe affords at present no more than sixty-seven indigenous species4 ,living tree-ferns of different genera4 ,fig4 #dej3 ,tree-fern from ,isle of ,bourbon4 ,fig4 #dea3 ,cyathea glauca1 ,mauritius4 ,fig4 #deb3 ,tree-fern from ,brazil4 ,lycopodiace--,lepidodendron4--,about forty species of fossil plants of the ,coal have been referred to this genus1 more than half of which are found in the ,british coal-measures4 ,they consist of cylindrical stems or trunks1 covered with leaf-scars4 ,in their mode of branching1 they are always dichotomous 7see ,fig4 #ded74 ,they belong to the ,lycopodiace1 bearing sporangia and spores similar to those of the living representatives of this family 7,fig4 #deg72 and although most of the ,carboniferous species grew to the size of large trees1 ,mr4 ,carruthers has found by careful measurement that the volume of the fossil spores did not exceed that of the recent club-moss1 a fact of some geological importance1 as it may help to explain the facility with which these seeds may have been transported by the wind1 causing the same wide distribution of the species of the fossil forests in ,europe and ,america which we now observe in the geographical distribution of so many living families of cryptogamous plants4 ,lepidodendrum ,sternbergii4 ,coal-measures1 near ,newcastle4 ,fig4 #dec3 ,branching trunk1 #di feet long1 supposed to have belonged to ,l4 ,sternbergii4 ,fig4 #ded3 ,branching stem with bark and leaves of ,l4 ,sternbergii4 ,fig4 #dee3 ,portion of same1 nearer the root4 ,fig4 #def3 a4 ,lycopodium densum4 ,living species1 ,new ,zealand2 b4 ,branch2 c4 ,part of same1 magnified4 ,the ,figs4 #dec-dee represent a fossil ,lepidodendron1 #di feet long1 found in ,jarrow ,colliery1 near ,newcastle1 lying in shale parallel to the planes of stratification4 ,fragments of others1 found in the same shale1 indicate1 by the size of the rhomboidal scars which cover them1 a still greater magnitude4 ,the living club-mosses1 of which there are about #bjj species1 are most abundant in tropical climates4 ,they usually creep on the ground1 but some stand erect1 as the ,lycopodium densum from ,new ,zealand 7see ,fig4 #def71 which attains a height of three feet4 ,in the ,carboniferous strata of ,coalbrook ,dale1 and in many other coal-fields1 elongated cylindrical bodies1 called fossil cones1 named ,lepidostrobus by ,m4 ,adolphe ,brongniart1 are met with4 7,see ,fig4 #deg47 ,they often form the nucleus of concretionary balls of clay-ironstone1 and are well preserved1 exhibiting a conical axis1 around which a great quantity of scales were compactly imbricated4 ,the opinion of ,m4 ,brongniart that the ,lepidostrobus is the fruit of ,lepidodendron has been confirmed1 for these strobili or fruits have been found terminating the tip of a branch of a well-characterised ,lepidodendron in ,coalbrook ,dale and elsewhere4 ,fig4 #deg3 a4 ,lepidostrobus ornatus2 b4 ,portion of a section1 showing the large sporangia in their natural position1 and each supported by its bract or scale2 c4 ,spores in these sporangia1 highly magnified4 ,fig4 #deh3 ,calamites ,sucowii1 common throughout ,europe4 ,fig4 #dei3 ,stem of ,fig4 #deh1 as retored by ,dr4 ,dawson4 ,equisetace4--,to this family belong two fossil genera of the coal1 ,equisetites and ,calamites4 ,the ,calamites were evidently closely related to the modern horse-tails 7,equiseta7 differing principally in their great size1 the want of sheaths at the joints1 and some details of fructification4 ,they grew in dense brakes on sandy and muddy flats in the manner of modern ,equisetace1 and their remains are frequent in the coal4 ,seven species of this plant occur in the great ,nova ,scotia section before described1 where the stems of some of them five inches in diameter1 and sometimes eight feet high1 may be seen terminating downward in a tapering root 7see ,fig4 #dfj74 ,fig4 #dfj3 ,radical termination of a ,calamite4 ,fig4 #dfa3 ,asterophyllites foliosus1 ,coal-measures1 ,newcastle4 ,botanists are not yet agreed whether the ,asterophyllites1 a species of which is represented in ,fig4 #dfa1 can form a separate genus from the ,calamite1 from which1 however1 according to ,dr4 ,dawson1 its foliage is distinguished by a true mid-rib1 which is wanting in the leaves known to belong to some ,calamites4 ,fig4 #dfb3 ,annularia sphenophylloides4,fig4 #dfc3 ,sphenophyllum erosum4 ,figs4 #dfb and #dfc represent leaves of ,annularia and ,sphenophyllum1 common in the coal1 and believed by ,mr4 ,carruthers to be leaves of ,calamites4 ,dr4 ,williamson1 who has carefully studied the ,calamites1 thinks that they had a fistular pith1 exogenous woody stem1 and thick smooth bark1 which last having always disappeared1 leaves a fluted stem1 as represented in ,fig4 #dei4 ,sigillaria4--,a large portion of the trees of the ,carboniferous period belonged to this genus1 of which as many as #bh species are enumerated as ,british4 ,the structure1 both internal and external1 was very peculiar1 and1 with reference to existing types1 very anomalous4 ,they were formerly referred1 by ,m4 ,ad4 ,brongniart1 to ferns1 which they resemble in the scalariform texture of their vessels and1 in some degree1 in the form of the cicatrices left by the base of the leaf-stalks which have fallen off 7see ,fig4 #dfd74 ,but some of them are ascertained to have had long linear leaves1 quite unlike those of ferns4 ,they grew to a great height1 from #cj to #fj1 or even #gj feet1 with regular cylindrical stems1 and without branches1 although some species were dichotomous towards the top4 ,their fluted trunks1 from one to five feet in diameter1 appear to have decayed more rapidly in the interior than externally1 so that they became hollow when standing2 and when thrown prostrate1 they were squeezed down and flattened4 ,hence1 we find the bark of the two opposite sides 7now converted into bright shining coal7 constitute two horizontal layers1 one upon the other1 half an inch1 or an inch1 in their united thickness4 ,these same trunks1 when they are placed obliquely or vertically to the planes of stratification1 retain their original rounded form1 and are uncompressed1 the cylinder of bark having been filled with sand1 which now affords a cast of the interior4 ,fig4 #dfd3 ,sigillaria lvigata4 ,dr4 ,hooker inclined to the belief that the ,sigillari may have been cryptogamous1 though more highly developed than any flowerless plants now living4 ,dr4 ,dawson having found in some species what he regards as medullary rays1 thinks with ,brongniart that they have some relation to gymnogens1 while ,mr4 ,carruthers leans to the opinion that they belong to the ,lycopodiace4 ,stigmaria4--,this fossil1 the importance of which has already been pointed out in p4 #cih1 was originally conjectured to be an aquatic plant4 ,it is now ascertained to be the root of ,sigillaria4 ,the connection of the roots with the stem1 previously suspected1 on botanical grounds1 by ,brongniart1 was first proved1 by actual contact1 in the ,lancashire coal-field1 by ,mr4 ,binney4 ,the fact has lately been shown1 even more distinctly1 by ,mr4 ,richard ,brown1 in his description of the ,stigmari occurring in the under-clays of the coal-seams of the ,island of ,cape ,breton1 in ,nova ,scotia4 ,in a specimen of one of these1 represented in ,fig4 #dfe1 the spread of the roots was sixteen feet1 and some of them sent out rootlets1 in all directions1 into the surrounding clay4 ,fig4 #dfe3 ,stigmaria attached to a trunk of ,sigillaria4 ,in the sea-cliffs of the ,south ,joggins in ,nova ,scotia1 ,i examined several erect ,sigillari1 in company with ,dr4 ,dawson1 and we found that from the lower extremities of the trunk they sent out ,stigmari as roots4 ,all the stools of the fossil trees dug out by us divided into four parts1 and these again bifurcated1 forming eight roots1 which were also dichotomous when traceable far enough4 ,the cylindrical rootlets formerly regarded as leaves are now shown by more perfect specimens to have been attached to the root by fitting into deep cylindrical pits4 ,in the fossil there is rarely any trace of the form of these cavities1 in consequence of the shrinkage of the surrounding tissues4 ,where the rootlets are removed1 nothing remains on the surface of the ,stigmaria but rows of mammillated tubercles 7see ,figs4 #dff1 #dfg71 which have formed the base of each rootlet4 ,fig4 #dff3 ,stigmaria ficoides4 ,fig4 #dfg3 ,surface of another individual of same species1 showing form of tubercles4 ,these protuberances may possibly indicate the place of a joint at the lower extremity of the rootlet4 ,rows of these tubercles are arranged spirally round each root1 which have always a medullary axis and woody system much resembling that of ,sigillaria1 the structure of the vessels being1 like it1 scalariform4 ,conifer4--,the coniferous trees of this period are referred to five genera2 the woody structure of some of them showing that they were allied to the ,araucarian division of pines1 more than to any of our common ,european firs4 ,some of their trunks exceeded forty-four feet in height4 ,many1 if not all of them1 seem to have differed from living ,conifer in having large piths2 for ,professor ,williamson has demonstrated the fossil of the coal-measures called ,sternbergia to be the pith of these trees1 or rather the cast of cavities formed by the shrinking or partial absorption of the original medullary axis 7see ,figs4 #dfh1 #dfi74 ,this peculiar type of pith is observed in living plants of very different families1 such as the common ,walnut and the ,white ,jasmine1 in which the pith becomes so reduced as simply to form a thin lining of the medullary cavity1 across which transverse plates of pith extend horizontally1 so as to divide the cylindrical hollow into discoid interspaces4 ,when these interspaces have been filled up with inorganic matter1 they constitute an axis to which1 before their true nature was known1 the provisional name of ,sternbergia 7d1 d1 ,fig4 #dfh7 was given4 ,in the above specimen the structure of the wood 7b1 ,figs4 #dfh and #dfi7 is coniferous1 and the fossil is referable to ,endlicher's fossil genus ,dadoxylon4 ,fig4 #dfh3 ,fragment of coniferous wood4 ,fig4 #dfh3 ,fragment of coniferous wood1 ,dadoxylon1 of ,endlicher1 fractured longitudinally2 from ,coalbrook ,dale4 ,w4,c4 ,williamson#c ,fig4 #dfi3 ,magnified portion of ,fig4 #dfh2 transverse section4 ,the fossil named ,trigonocarpon 7,figs4 #dgj and #dga71 formerly supposed to be the fruit of a palm1 may now1 according to ,dr4 ,hooker1 be referred1 like the ,sternbergia1 to the ,conifer4 ,its geological importance is great1 for so abundant is it in the coal-measures1 that in certain localities the fruit of some species may be procured by the bushel2 nor is there any part of the formation where they do not occur1 except the under-clays and limestone4 ,the sandstone1 ironstone1 shales1 and coal itself1 all contain them4 ,mr4 ,binney has at length found in the clay-ironstone of ,lancashire several specimens displaying structure1 and from these1 says ,dr4 ,hooker1 we learn that the ,trigonocarpon belonged to that large section of existing coniferous plants which bear fleshy solitary fruits1 and not cones4 ,it resembled very closely the fruit of the ,chinese genus ,salisburia1 one of the ,yew tribe1 or ,taxoid conifers4 ,fig4 #dgj3 ,trigonocarpum ovatum4,fig4 #dga3 ,trigonocarpum olivforme4 ,fig4 #dgb3 ,antholithes4 ,angiosperms4--,the curious fossils called ,antholithes by ,lindley have usually been considered to be flower spikes1 having what seems a calyx and linear petals 7see ,fig4 #dgb74 ,dr4 ,hooker1 after seeing very perfect specimens1 also thought that they resembled the spike of a highly-organised plant in full flower1 such as one of the ,bromeliace1 to which ,professor ,lindley had at first compared them4 ,mr4 ,carruthers1 who has lately examined a large series in different museums1 considers it to be a dicotyledonous angiosperm allied to ,orobanche 7broom-rape71 which grew1 not on the soil1 but parasitically on the trees of the coal forests4 ,in the coal-measures of ,granton1 near ,edinburgh1 a remarkable fossil 7,fig4 #dgc7 was found and described in #ahdj1d by ,dr4 ,robert ,paterson4 ,it was compressed between layers of bituminous shale1 and consists of a stem bearing a cylindrical spike1 a1 which in the portion preserved in the slate exhibits two subdivisions and part of a third4 ,the spike is covered on the exposed surface with the four-cleft calyces of the flowers arranged in parallel rows4 ,the stem shows1 at b1 a little below the spike1 remains of a lateral appendage1 which is supposed to indicate the beginning of the spathe4 ,the fossil has been referred to the ,aroidi1 and there is every probability that it is a true member of this order4 ,there can at least be no doubt as to the high grade of its organisation1 and that it belongs to the monocotyledonous angiosperms4 ,mr4 ,carruthers has carefully examined the original specimen in the ,botanical ,museum1 ,edinburgh1 and thinks it may have been an epiphyte4 ,fig4 #dgc3 ,pothocites ,grantonii4 ,climate of the ,coal ,period4--,as to the climate of the ,coal1 the ,ferns and the ,conifer are perhaps the two classes of plants which may be most relied upon as leading us to safe conclusions1 as the genera are nearly allied to living types4 ,all botanists admit that the abundance of ferns implies a moist atmosphere4 ,but the conifer1 says ,hooker1 are of more doubtful import1 as they are found in hot and dry1 and in cold and dry climates2 in hot and moist1 and in cold and moist regions4 ,in ,new ,zealand the conifer attain their maximum in numbers1 constituting #a_/fb part of all the flowering plants2 whereas in a wide district around the ,cape of ,good ,hope they do not form #a_/afjj of the phenogamic flora4 ,besides the conifers1 many species of ferns flourish in ,new ,zealand1 some of them arborescent1 together with many lycopodiums2 so that a forest in that country may make a nearer approach to the carboniferous vegetation than any other now existing on the globe4 ,,marine ,,fauna ,,of ,,the ,,carboniferous ,,period4 ,it has already been stated that the ,carboniferous or ,mountain ,limestone underlies the coal-measures in the ,south of ,england and ,wales1 whereas in the ,north1 and in ,scotland1 marine calcareous rocks partly of the age of the ,mountain ,limestone alternate with shales and sandstones1 containing seams of coal4 ,in its most calcareous form the ,mountain ,limestone is destitute of land-plants1 and is loaded with marine remains--the greater part1 indeed1 of the rock being made up bodily of crinoids1 corals1 and bryozoa with interspersed mollusca4 ,corals4--,the corals deserve especial notice1 as the cup-and-star corals1 which have the most massive and stony skeletons1 display peculiarities of structure by which they may be distinguished generally1 as ,,mm4 ,milne ,edwards and ,haime first pointed out1 from all species found in strata newer than the ,permian4 ,there is1 in short1 an ancient or ,palozoic1 and a modern or ,neozoic type1 if1 by the latter term1 we designate 7as proposed by ,professor ,e4 ,forbes7 all strata from the triassic to the most modern1 inclusive4 ,the accompanying diagrams 7,figs4 #dgd1 #dge7 may illustrate these types4 ,fig4 #dgd3 ,palozoic type of lamelliferous cup-shaped ,coral4 ,vertical section of ,campophyllum flexuosum1 7,cyathophyllum1 ,goldfuss72 from the ,devonian of the ,eifel4 ,the lamell are seen around the inside of the cup2 the walls consist of cellular tissue2 and large transverse plates1 called tubul1 divide the interior into chambers4 ,arrangement of the lamell in ,polycoelia profunda1 ,germar1 sp42 from the ,magnesian ,limestone1 ,durham4 ,this diagram shows the quadripartite arrangement of the primary septa1 characteristic of palozoic corals1 there being four principal and eight intermediate lamell1 the whole number in this type being always a multiple of four4 ,stauria astriformis1 ,milne ,edwards4 ,young group1 natural size4 ,upper ,silurian1 ,gothland4 ,the lamell or septal system in each cup are divided by four prominent ridges into four groups4 ,fig4 #dge3 ,neozoic type of lamelliferous cup-shaped ,coral4 ,parasmilia centralis1 ,mantell1 sp4 ,vertical section4 ,upper ,chalk1 ,gravesend4 ,in this type the lamell are massive1 and extend to the axis or columella composed of loose cellular tissue1 without any transverse plates like those in ,fig4 #dgd1 a4 ,cyathina ,bowerbankii1 ,ed4 and ,h4 ,transverse section1 enlarged4 ,gault1 ,folkestone4 ,in this coral the primary septa are a multiple of six4 ,the twelve principal plates reach the columella1 and between each pair there are three secondaries1 in all forty-eight4 ,the short intermediate plates which proceed from the columella are not counted4 ,they are called pali4 ,fungia patellaris1 ,lamarck4 ,recent2 very young state4 ,diagram of its six primary and six secondary septa1 magnified4 ,the sextuple arrangement is always more manifest in the young than in the adult state4 ,it will be seen that the more ancient corals have what is called a quadripartite arrangement of the chief plates or lamell--parts of the skeleton which support the organs of reproduction4 ,the number of these lamell in the ,palozoic type is #d1 #h1 #af1 etc42 while in the ,neozoic type the number is #f1 #ab1 #bd1 or some other multiple of six2 and this holds good1 whether they be simple forms1 as in ,figs4 #dgd1 a1 and #dge1 a1 or aggregate clusters of corallites1 as in #dgd1 c4 ,but further investigations have shown in this1 as in all similar grand generalisations in natural history1 that there are excepions to the rule4 ,thus in the ,lower ,greensand ,holocystis elegans 7,ed4 and ,h47 and other forms have the ,palozoic type1 and ,dr4 ,duncan has shown to what extent the ,neozoic forms penetrate downward into the ,carboniferous and ,devonian rocks4 ,fig4 #dgf3 ,lithostrotion basaltiforme4 ,fig4 #dgg3 ,lonsdaleia floriformis4 ,from a great number of lamelliferous corals met with in the ,mountain ,limestone1 two species 7,figs4 #dgf1 #dgg7 have been selected1 as having a very wide range1 extending from the eastern borders of ,russia to the ,british ,isles1 and being found almost everywhere in each country4 ,these fossils1 together with numerous species of ,zaphrentis1 ,amplexus1 ,cyathophyllum1 ,clisiophyllum1 ,syringopora1 and ,michelinia1#e form a group of rugose corals widely different from any that followed them4 ,bryozoa and ,crinoidea4--,of the ,bryozoa1 the prevailing forms are ,fenestella1 ,hemitrypa1 and ,polypora1 and these often form considerable beds4 ,their net-like fronds are easily recognised4 ,crinoidea are also numerous in the ,mountain ,limestone 7see ,figs4 #dgh1 #dgi71 two genera1 ,pentremites and ,codonaster1 being peculiar to this formation in ,europe and ,north ,america4 ,fig4 #dgh3 ,cyathocrinus planus4 ,fig4 #dgi3 ,cyathocrinus caryocrinoides4 ,fig4 #dhj3 ,palchinus gigas4 ,in the greater part of them1 the cup or pelvis1 ,figure #dgi1 b1 is greatly developed in size in proportion to the arms1 although this is not the case in ,fig4 #dgh4 ,the genera ,poteriocrinus1 ,cyathocrinus1 ,pentremites1 ,actinocrinus1 and ,platycrinus1 are all of them characteristic of this formation4 ,other ,echinoderms are rare1 a few ,sea-,urchins only being known3 these have a complex structure1 with many more plates on their surface than are seen in the modern genera of the same group4 ,one genus1 the ,palchinus 7,fig4 #dhj71 is the analogue of the modern ,echinus1 but has four1 five1 or six rows of plates in the interambulacral region or area1 whereas the modern genera have only two4 ,the other1 ,archocidaris1 represents1 in like manner1 the ,cidaris of the present seas4 ,mollusca4--,the ,british ,carboniferous mollusca enumerated by ,mr4 ,etheridge#f comprise #fec species referable to #hf genera1 occurring chiefly in the ,mountain ,limestone4 ,of this large number only #dj species are common to the underlying ,devonian rocks1 #i of them being ,cephalopods1 #g ,gasteropods1 and the rest bivalves1 chiefly ,brachiopoda 7or ,palliobranchiates74 ,this latter group constitutes the larger part of the ,carboniferous ,mollusca1 #aeg species being known in ,great ,britain alone1 and it will be found to increase in importance in the fauna of the primary rocks the lower we descend in the series4 ,perhaps the most characteristic shells of the formation are large species of ,productus1 such as ,p4 giganteus1 p4 hemisphericus1 ,p4 semireticulatus 7,fig4 #dha71 and ,p4 scabriculus4 ,large plaited spirifers1 as ,spirifera striata1 ,s4 rotundata1 and ,s4 trigonalis 7,fig4 #dhb71 also abound2 and smooth species1 such as ,spirifera glabra 7,fig4 #dhc71 with its numerous varieties4 ,fig4 #dha3 ,productus semireticulatus4 ,fig4 #dhb3 ,spirifera trigonalis4 ,fig4 #dhc3 ,spirifera glabra4 ,fig4 #dhd3 ,terebratula hastata4 ,fig4 #dhe3 ,aviculopecten sublobatus4 ,fig4 #dhf3 ,pleurotomaria carinata4 ,among the brachiopoda1 ,terebratula hastata 7,fig4 #dhd7 deserves mention1 not only for its wide range1 but because it often retains the pattern of the original coloured stripes which ornamented the living shell4 ,these coloured bands are also preserved in several lamellibranchiate bivalves1 as in ,aviculopecten 7,fig4 #dhe71 in which dark stripes alternate with a light ground4 ,in some also of the spiral univalves the pattern of the original painting is distinctly retained1 as in ,pleurotomaria 7,fig4 #dhf71 which displays wavy blotches1 resembling the colouring in many recent trochid4 ,fig4 #dhg3 ,euomphalus pentagulatus4 ,some few of the carboniferous mollusca1 such as ,avicula1 ,nucula 7sub-genus ,ctenodonta71 ,solemya1 and ,lithodomus1 belong no doubt to existing genera2 but the majority1 though often referred to as living types1 such as ,isocardia1 ,turritella1 and ,buccinum1 belong really to forms which appear to have become extinct at the close of the ,palozoic epoch4 ,euomphalus is a characteristic univalve shell of this period4 ,in the interior it is divided into chambers 7,fig4 #dhg1 d71 the septa or partitions not being perforated as in foraminiferous shells1 or in those having siphuncles1 like the ,nautilus4 ,the animal appears to have retreated at different periods of its growth from the internal cavity previously formed1 and to have closed all communication with it by a septum4 ,the number of chambers is irregular1 and they are generally wanting in the innermost whorl4 ,the animal of the recent ,turritella communis partitions off in like manner as it advances in age a part of its spire1 forming a shelly septum4 ,more than twenty species of the genus ,bellerophon 7see ,fig4 #dhh71 a shell like the living ,argonaut without chambers1 occur in the ,mountain ,limestone4 ,the genus is not met with in strata of later date4 ,it is most generally regarded as belonging to the pelagic ,nucleobranchiata and the family ,atlantid1 partly allied to the ,glass-,shell1 ,carinaria2 but by some few it is thought to be a simple form of ,cephalopod4 ,fig4 #dhh3 ,bellerophon costatus4 ,fig4 #dhi3 ,portion of ,orthoxeras laterale4 ,fig4 #dij3 ,goniatites crenistra4 ,the carboniferous ,cephalopoda do not depart so widely from the living type 7the ,nautilus7 as do the more ancient ,silurian representatives of the same order2 yet they offer some remarkable forms4 ,among these is ,orthoceras1 a siphuncled and chambered shell1 like a ,nautilus uncoiled and straightened 7,fig4 #dhi74 ,some species of this genus are several feet long4 ,the ,goniatite is another genus1 nearly allied to the ,ammonite1 from which it differs in having the lobes of the septa free from lateral denticulations1 or crenatures2 so that the outline of these is angular1 continuous1 and uninterrupted4 ,the species represented in ,fig4 #dij is found in most localities1 and presents the zigzag character of the septal lobes in perfection4 ,the dorsal position of the siphuncle1 however1 clearly distinguishes the ,goniatite from the ,nautilus1 and proves it to have belonged to the family of the ,ammonites1 from which1 indeed1 some authors do not believe it to be generically distinct4 ,fossil ,fish4--,the distribution of these is singularly partial2 so much so1 that ,m4 ,de ,koninck of ,lige1 the eminent palontologist1 once stated to me that1 in making his extensive collection of the fossils of the ,mountain ,limestone of ,belgium1 he had found no more than four or five examples of the bones or teeth of fishes4 ,judging from ,belgian data1 he might have concluded that this class of vertebrata was of extreme rarity in the ,carboniferous seas2 whereas the investigation of other countries has led to quite a different result4 ,thus1 near ,clifton1 on the ,avon1 as well as at numerous places around the ,bristol basin from the ,mendip ,hills to ,tortworth1 there is a celebrated 8bone-bed10 almost entirely made up of ichthyolites4 ,it occurs at the base of the ,lower ,limestone shales immediately resting upon the passage beds of the ,old ,red ,sandstone4 ,similar bone-beds occur in the ,carboniferous ,limestone of ,armagh1 in ,ireland1 where they are made up chiefly of the teeth of fishes of the ,placoid order1 nearly all of them rolled as if drifted from a distance4 ,some teeth are sharp and pointed1 as in ordinary sharks1 of which the genus ,cladodus afford an illustration2 but the majority1 as in ,psammodus and ,cochliodus1 are1 like the teeth of the ,cestracion of ,port ,jackson 7see ,fig4 #bfa71 massive palatal teeth fitted for grinding4 7,see ,figs4 #dia1 #dib47 ,fig4 #dia3 ,psammodus porosus4 ,fig4 #dib3 ,cochliodus controtus4 ,there are upward of seventy other species of fossil fish known in the ,mountain ,limestone of the ,british ,islands4 ,the defensive fin-bones of these creatures are not infrequent at ,armagh and ,bristol2 those known as ,oracanthus1 ,ctenocanthus1 and ,onchus are often of a very large size4 ,ganoid fish1 such as ,holoptychius1 also occur2 but these are far less numerous4 ,the great ,megalichthys ,hibberti appears to range from the ,upper ,coal-measures to the lowest ,carboniferous strata4 ,foraminifera4--,in the upper part of the ,mountain ,limestone group in the ,s4,w4 of ,england1 near ,bristol1 limestones having a distinct oolitic structure alternate with shales4 ,in these rocks the nucleus of every minute spherule is seen1 under the microscope1 to consist of a small rhizopod or foraminifer4 ,this division of the lower animals1 which is represented so fully at later epochs by the ,nummulites and their numerous minute allies1 appears in the ,mountain ,limestone to be restricted to a very few species1 among which ,textularia1 ,nodosaria1 ,endothyra1 and ,fusulina 7,fig4 #dic71 have been recognised4 ,the first two genera are common to this and all the after periods2 the third has been found in the ,upper ,silurian1 but is not known above the ,carboniferous strata2 the fourth 7,fig4 #dic7 is characteristic of the ,mountain ,limestone in the ,united ,states1 ,arctic ,america1 ,russia1 and ,asia ,minor1 but is also known in the ,permian4 ,fig4 #dic3 ,fusulina cylindrica4 #a ,for botanical nomenclature see p4 #cjd4 #b ,sir ,c4 ,bunbury1 ,quart4 ,geol4 ,journ41 vol4 ii1 #ahde4 #c ,manchester ,phil4 ,mem41 vol4 ix1 #ahea4 #d ,trans4 of ,bot4 ,soc4 of ,edinburgh1 vol4 i1 #ahdd4 #e ,for figures of these corals1 see ,palontographical ,society's ,monographs1 #aheb4 #f ,quart4 ,geol4 ,journ41 vol4 xxiii1 p4 #fgd1 #ahfg4 ,,chapter ,,xxv4 ,,devonian ,,or ,,old ,,red ,,sandstone ,,group4 ,classification of the ,old ,red ,sandstone in ,scotland and in ,devonshire4 -- ,upper ,old ,red ,sandstone in ,scotland1 with ,fish and ,plants4 -- ,middle ,old ,red ,sandstone4 -- ,classification of the ,ichthyolites of the ,old ,red1 and their ,relation to ,living ,types4 -- ,lower ,old ,red ,sandstone1 with ,cephalaspis and ,pterygotus4 -- ,marine or ,devonian ,type of ,old ,red ,sandstone4 -- ,table of ,devonian ,series4 -- ,upper ,devonian ,rocks and ,fossils4 -- ,middle4 -- ,lower4 -- ,eifel ,limestone of ,germany4 -- ,devonian of ,russia4 -- ,devonian ,strata of the ,united ,states and ,canada4 -- ,devonian ,plants and ,insects of ,canada4 ,classification of the two ,types of ,old ,red ,sandstone4--,we have seen that the ,carboniferous strata are surmounted by the ,permian and ,trias1 both originally included in ,england under the name 8,new ,red ,sandstone10 from the prevailing red colour of the strata4 ,under the coal came other red sandstones and shales which were distinguished by the title of 8,old ,red ,sandstone40 ,afterwards the name of 8,devonian0 was given by ,sir ,r4 ,murchison and ,professor ,sedgwick to marine fossiliferous strata which1 in the south of ,england1 occupy a similar position between the overlying coal and the underlying ,silurian formations4 ,it may be truly said that in the ,british ,isles the rocks of this age present themselves in their mineral aspect1 and even to some extent in their fossil contents1 under two very different forms2 the one as distinct from the other as are often lacustrine or fluviatile from marine strata4 ,it has indeed been suggested that by far the greater part of the deposits belonging to what may be termed the ,old ,red ,sandstone type are of fresh-water origin4 ,the number of land-plants1 the character of the fishes1 and the fact that the only shell yet discovered belongs to the genus ,anodonta1 must be allowed to lend no small countenance to this opinion4 ,in this case the difficulty of classification when the strata of this type are compared in different regions1 even where they are contiguous1 may arise partly from their having been formed in distinct hydrographical basins1 or in the neighbourhood of the land in shallow parts of the sea into which large bodies of fresh-water entered1 and where no marine mollusca or corals could flourish4 ,under such geographical conditions the limited extent of some kinds of sediment1 as well as the absence of those marine forms by which we are able to identify or contrast marine formations1 may be explained1 while the great thickness of the rocks1 which might seem at first sight to require a corresponding depth of water1 can often be shown to have been due to the gradual sinking down of the bottom of the estuary or sea where the sediment was accumulated4 ,another active cause of local variation in ,scotland was the frequency of contemporaneous volcanic eruptions2 some of the rocks derived from this source1 as between the ,grampians and the ,tay1 having formed islands in the sea1 and having been converted into shingle and conglomerate1 before the upper portions of the red shales and sandstones were superimposed4 ,the dearth of calcareous matter over wide areas is characteristic of the ,old ,red ,sandstone4 ,this is1 no doubt1 in great part due to the absence of shells and corals2 but why should these be so generally wanting in all sedimentary rocks the colour of which is determined by the red oxide of iron8 ,some geologists are of opinion that the waters impregnated with this oxide were prejudicial to living beings1 others that strata permeated with this oxide would not preserve such fossil remains4 ,in regard to the two types1 the ,old ,red ,sandstone and the ,devonian1 ,i shall first treat of them separately1 and then allude to the proofs of their having been to a great extent contemporaneous4 ,that they constitute a series of rocks intermediate in date between the lowest ,carboniferous and the uppermost ,silurian is not disputed by the ablest geologists2 and it can no longer be contended that the ,upper1 ,middle1 and ,lower ,old ,red ,sandstone preceded in date the three divisions to which1 by aid of the marine shells1 the ,devonian rocks have been referred1 while1 on the other hand1 we have not yet data for enabling us to affirm to what extent the subdivisions of the one series may be the equivalents in time of those of the other4 ,upper ,old ,red ,sandstone4--,the highest beds of the series in ,scotland1 lying immediately below the coal in ,fife1 are composed of yellow sandstone well seen at ,dura ,den1 near ,coupar1 in ,fife1 where1 although the strata contain no mollusca1 fish have been found abundantly1 and have been referred to the genera ,holoptychius1 ,pamphractus1 ,glyptopomus1 and many others4 ,in the county of ,cork1 in ,ireland1 a similar yellow sandstone occurs containing fish of genera characteristic of the ,scotch ,old ,red ,sandstone1 as for example ,coccosteus 7a form represented by many species in the ,old ,red ,sandstone and by one only in the ,carboniferous group71 and ,glytolepis and ,asterolepis1 both exclusively confined to the 8,old ,red40 ,in the same ,irish sandstone at ,kiltorkan has been found an ,anodonta or fresh-water mussel1 the only shell hitherto discovered in the ,old ,red ,sandstone of the ,british ,isles 7see ,fig4 #did74 ,fig4 #did3 ,anodonta ,jukesii4 ,fig4 #die3 ,bifurcating branch of ,lepidendron ,griffithsii4 ,fig4 #dif3 ,palopteris ,hibernia4 ,in the same formation are found the fern 7,fig4 #dif7 and the ,lepidodendron 7,fig4 #die71 and other species of plants1 some of which1 ,professor ,heer remarks1 agree specifically with species from the lower carboniferous beds4 ,this induces him to lean to the opinion long ago advocated by ,sir ,richard ,griffiths1 that the yellow sandstone1 in spite of its fish remains1 should be classed as ,lower ,carboniferous1 an opinion which ,i am not yet prepared to adopt4 ,between the ,mountain ,limestone and the yellow sandstone in the south-west of ,ireland there intervenes a formation no less than #ejjj feet thick1 called the 8,carboniferous slate10 and at the base of this1 in some places1 are local deposits1 such as the ,glengariff ,grits1 which appear to be beds of passage between the ,carboniferous and ,old ,red ,sandstone groups4 ,it is a remarkable result of the recent examination of the fossil flora of ,bear ,island1 latitude #gd #cj ,n41 that ,professor ,heer has described as occurring in that part of the ,arctic region 7nearly twenty-six degrees to the north of the ,irish locality7 a flora agreeing in several of its species with that of the yellow sandstones of ,ireland4 ,this ,bear ,island flora is believed by ,professor ,heer to comprise species of plants some of which ascend even to the higher stages of the ,european ,carboniferous formation1 or as high as the ,mountain ,limestone and ,millstone ,grit4 ,palontologists have long maintained that the same species which have a wide range in space are also the most persistent in time1 which may prepare us to find that some plants having a vast geographical range may also have endured from the period of the ,upper ,devonian to that of the ,millstone ,grit4 ,fig4 #dig3 ,scale of ,holoptychius nobilissimus4 ,outliers of the ,upper 8,old ,red0 occur unconformably on older members of the group1 and the formation represented at ,whiteness1 near ,arbroath1 a1 ,fig4 #ee1 may probably be one of these outliers1 though the want of organic remains renders this uncertain4 ,it is not improbable that the beds given in this section as ,nos4 #a1 #b1 and #c1 may all belong to the early part of the period of the ,upper ,old ,red1 as some scales of ,holoptychius nobilissimus have been found scattered through these beds1 ,no4 #b1 in ,strathmore4 ,another nearly allied ,holoptychius occurs in ,dura ,den1 see ,fig4 #dih of this fish and also ,fig4 #dig of one of its scales1 as these last are often the only parts met with2 being scattered in ,forfarshire through red-coloured shales and sandstones1 as are scales of a large species of the same genus in a corresponding matrix in ,herefordshire4#a ,the number of fish obtained from the ,british ,upper ,old ,red ,sandstone amounts to fifteen species referred to eleven genera4 ,fig4 #dih3 ,holoptychius1 as restored by ,professor ,huxley4 ,sir ,r4 ,murchison groups with this upper division of the ,old ,red of ,scotland certain light-red and yellow sandstones and grits which occur in the northernmost part of the mainland1 and extend also into the ,orkney and ,shetland ,islands4 ,they contain ,calamites and other plants which agree generically with ,carboniferous forms4 ,middle ,old ,red ,sandstone4--,in the northern part of ,scotland there occur a great series of bituminous schists and flagstones1 to the fossil fish of which attention was first called by the late ,hugh ,miller4 ,they were afterwards described by ,agassiz1 and the rocks containing them were examined by ,sir ,r4 ,murchison and ,professor ,sedgwick1 in ,caithness1 ,cromarty1 ,moray1 ,nairn1 ,gamrie in ,banff1 and the ,orkneys and ,shetlands1 in which great numbers of fossil fish have been found4 ,these were at first supposed to be the oldest known vertebrate animals1 as in ,cromarty the beds in which they occur seem to form the base of the ,old ,red system resting almost immediately on the crystalline or metamorphic rocks4 ,but in fact these fish-bearing beds1 when they are traced from north to south1 or to the central parts of ,scotland1 thin out1 so that their relative age to the ,lower ,old ,red ,sandstone1 presently to be mentioned1 was not at first detected1 the two formations not appearing in superposition in the same district4 ,in ,caithness1 however1 many hundred feet below the fish-zone of the middle division1 remains of ,pteraspis were found by ,mr4 ,peach in #ahfa4 ,this genus has never yet been found in either of the two higher divisions of the ,old ,red ,sandstone1 and confirms ,sir ,r4 ,murchison's previous suspicion that the rocks in which it occurs belong to the ,lower 8,old ,red10 or agree in age with the ,arbroath paving-stone4#b ,fossil ,fish of the ,middle ,old ,red ,sandstone4--,the ,devonian fish were referred by ,agassiz to two of his great orders1 namely1 the ,placoids and ,ganoids4 ,of the first of these1 which in the ,recent period comprise the shark1 the dog-fish1 and the ray1 no entire skeletons are preserved1 but fin-spines1 called ichthyodorulites1 and teeth occur4 ,on such remains the genera ,onchus1 ,odontacanthus1 and ,ctenodus1 a supposed cestraciont1 and some others1 have been established4 ,by far the greater number of the ,old ,red ,sandstone fishes belong to a sub-order of ,ganoids instituted by ,huxley in #ahfa1 and for which he has proposed the name of ,crossopterygid1#c or the fringe-finned1 in consideration of the peculiar manner in which the fin-rays of the paired fins are arranged so as to form a fringe round a central lobe1 as in the ,polypterus 7see a1 ,fig4 #dii71 a genus of which there are several species now inhabiting the ,nile and other ,african rivers4 ,the reader will at once recognise in ,osteolepis 7,fig4 #ejj71 one of the common fishes of the ,old ,red ,sandstone1 many points of analogy with ,polypterus4 ,they not only agree in the structure of the fin1 at first pointed out by ,huxley1 but also in the position of the pectoral1 ventral1 and anal fins1 and in having an elongated body and rhomboidal scales4 ,on the other hand1 the tail is more symmetrical in the recent fish1 which has also an apparatus of dorsal finlets of a very abnormal character1 both as to number and structure4 ,as to the dorsals of ,osteolepis1 they are regular in structure and position1 having nothing remarkable about them1 except that there are two of them1 which is comparatively unusual in living fish4 ,fig4 #dii3 ,polypterus4 ,living in the ,nile and other rivers4 ,fig4 #ejj3 ,restoration of ,osteolepis4 ,among the 8fringe-finned0 ,ganoids we find some with rhomboidal scales1 such as ,osteolepis1 ,fig4 #ejj2 others with cycloidal scales1 as ,holoptychius1 before mentioned 7see ,fig4 #dih74 ,in the genera ,dipterus and ,diplopterus1 as ,hugh ,miller pointed out1 and in several other of the fringe-finned genera1 as in ,gyroptychius and ,glyptolepis1 the two dorsals are placed far backward1 or directly over the ventral and anal fins4 ,the ,asterolepis was a ganoid fish of gigantic dimensions4 ,a4 ,asmusii1 ,eichwald1 a species characteristic of the ,old ,red ,sandstone of ,russia1 as well as that of ,scotland1 attained the length of between twenty and thirty feet4 ,it was clothed with strong bony armour1 embossed with star-like tubercles1 but it had only a cartilaginous skeleton4 ,the mouth was furnished with two rows of teeth1 the outer ones small and fish-like1 the inner larger and with a reptilian character4 ,the ,asterolepis occurs also in the ,devonian rocks of ,north ,america4 ,if we except the ,placoids already alluded to1 and a few other families of doubtful affinities1 all the ,old ,red ,sandstone fishes are ,ganoids1 an order so named by ,agassiz from the shining outer surface of their scales2 but ,professor ,huxley has also called our attention to the fact that1 while a few of the primary and the great majority of the secondary ,ganoids resemble the living bony pike1 ,lepidosteus1 or the ,amia1 genera now found in ,north ,american rivers1 and one of them1 ,lepidosteus1 extending as far south as ,guatemala1 the ,crossopterygii1 or fringe-finned ,ichthyolites1 of the ,old ,red are closely related to the ,african ,polypterus1 which is represented by five or six species now inhabiting the ,nile and the rivers of ,senegal4 ,these ,north ,american and ,african ,ganoids are quite exceptional in the living creation2 they are entirely confined to the northern hemisphere1 unless some species of ,polypterus range to the south of the line in ,africa2 and1 out of about #ijjj living species of fish known to ,m4 ,gnther1 and of which more than #fjjj are now preserved in the ,british ,museum1 they probably constitute no more than nine4 ,fig4 #eja3 ,pterichthys4 ,upper side1 showing mouth4 ,if many circumstances favour the theory of the fresh-water origin of the ,old ,red ,sandstone1 this view of its nature is not a little confirmed by our finding that it is in ,llake ,superior and the other inland ,canadian seas of fresh water1 and in the ,mississippi and ,african rivers1 that we at present find those fish which have the nearest affinity to the fossil forms of this ancient formation4 ,among the anomalous forms of ,old ,red fishes not referable to ,huxley's ,crossopterygii is the ,pterichthys1 of which five species have been found in the middle division of the ,old ,red of ,scotland4 ,some writers have compared their shelly covering to that of ,crustaceans1 with which1 however1 they have no real affinity4 ,the wing-like appendages1 whence the genus is named1 were first supposed by ,hugh ,miller to be paddles1 like those of the turtle2 and there can now be no doubt that they do really correspond with the pectoral fins4 ,the number of species of fish already obtained from the middle division of the ,old ,red ,sandstone in ,great ,britain is about #gj1 and the principal genera1 besides ,osteolepis and ,pterichthys1 already mentioned1 are ,glyptolepis1 ,diplacanthus1 ,dendrodus1 ,coccosteus1 ,cheirancanthus1 and ,acanthoides4 ,fig4 #ejb3 ,cephalapsis ,lyellii4 ,lower ,old ,red ,sandstone4--,the third or lowest division south of the ,grampians consists of grey paving-stone and roofing-slate1 with associated red and grey shales2 these strata underlie a dense mass of conglomerate4 ,in these grey beds several remarkable fish have been found of the genus named by ,agassiz ,cephalaspis1 or 8buckler-headed10 from the extraordinary shield which covers the head 7see ,fig4 #ejb71 and which has often been mistaken for that of a trilobite1 such as ,asaphus4 ,a species of ,pteraspis1 of the same family1 has also been found by the ,reverend ,hugh ,mitchell in beds of corresponding age in ,perthshire2 and ,mr4 ,powrie enumerates no less than five genera of the family ,acanthodid1 the spines1 scales1 and other remains of which have been detected in the grey flaggy sandstones4#d ,fig4 #ejc3 ,pteygotus anglicus4 ,in the same formation at ,carmylie1 in ,forfarshire1 commonly known as the ,arbroath paving-stone1 fragments of a huge crustacean have been met with from time to time4 ,they are called by the ,scotch quarrymen the 8,seraphim10 from the wing-like form and feather-like ornament of the thoracic appendage1 the part most usually met with4 ,agassiz1 having previously referred some of these fragments to the class of fishes1 was the first to recognise their crustacean character1 and1 although at the time unable correctly to determine the true relation of the several parts1 he figured the portions on which he founded his opinion1 in the first plate of his 8,poissons ,fossiles du ,vieux ,grs ,rouge40 ,fig4 #ejd3 ,pterygotus anglicus4 ,ventral aspect4 ,carapace1 showing the large sessile eyes at the anterior angles4 ,the metastoma or post-oral plate 7serving the office of a lower lip74 ,chelate appendages 7antennules74 ,first pair of simple palpi 7antenn74 ,second pair of simple palpi 7mandibles74 ,third pair of simple palpi 7first maxill74 ,pair of swimming feet with their broad basal joints1 whose serrated edges serve the office of maxill4 ,thoracic plate covering the first two thoracic segments1 which are indicated by the figures #a1 #b1 and a dotted line4 #a-f4 ,thoracic segments4 #g-ab4 ,abdominal segments4 #ac4 ,telson1 or tail-plate47 ,a restoration in correct proportion to the size of the fragments of ,p4 anglicus 7,fig4 #ejd71 from the ,lower ,old ,red ,sandstone of ,perthshire and ,forfarshire1 would give us a creature measuring from five to six feet in length1 and more than one foot across4 ,the largest crustaceans living at the present day are the ,inachus ,kaempferi1 of ,de ,haan1 from ,japan 7a brachyurous or short-tailed crab71 chiefly remarkable for the extraordinary length of its limbs2 the fore-arm measuring four feet in length1 and the others in proportion1 so that it covers about #be square feet of ground2 and the ,limulus ,moluccanus1 the great ,king ,crab of ,china and the ,eastern seas1 which1 when adult1 measures #a foot across its carapace1 and is three feet in length4 ,besides some species of ,pterygotus1 several of the allied genus ,eurypterus occur in the ,lower ,old ,red ,sandstone1 and with them the remains of grass-like plants so abundant in ,forfarshire and ,kincardineshire as to be useful to the geologist by enabling him to identify the inferior strata at distant points4 ,some botanists have suggested that these plants may be of the family ,fluviales1 and of fresh-water genera4 ,they are accompanied by fossils1 called 8berries0 by the quarrymen1 which they compared to a compressed blackberry 7see ,figs4 #eje1 #ejf71 and which were called 8,parka0 by ,dr4 ,fleming4 ,they are now considered by ,mr4 ,powrie to be the eggs of crustaceans1 which is highly probable1 for they have not only been found with ,pterygotus anglicus in ,forfarshire and ,perthshire1 but also in the ,upper ,silurian strata of ,england1 in which species of the same genus1 ,pterygotus1 occur4 ,fig4 #eje3 ,parka decipiens4 ,in sandstone of lower beds of ,old ,red1 ,ley's ,mill1 ,forfarshire4 ,fig4 #ejf3 ,parka decipiens4 ,in shale of ,lower ,old ,red1 ,park ,hill1 ,fife4 ,fig4 #ejg3 ,shale of ,old ,red ,sandstone4 ,forfarshire4 ,with impression of plants and eggs of ,crustaceans4 ,the grandest exhibitions1 says ,sir ,r4 ,murchison1 of the ,old ,red ,sandstone in ,england and ,wales appear in the escarpments of the ,black ,mountains and in the ,fans of ,brecon and ,carmarthen1 the one #bhfb1 and the other #beij feet above the sea4 ,the mass of red and brown sandstone in these mountains is estimated at not less than #aj1jjj feet1 clearly intercalated between the ,carboniferous and ,silurian strata4 ,no shells or corals have ever been found in the whole series1 not even where the beds are calcareous1 forming irregular courses of concretionary lumps called 8corn-stones10 which may be described as mottled red and green earthy limestones4 ,the fishes of this lowest ,english ,old ,red are ,cephalaspis and ,pteraspis1 specifically different from species of the same genera which occur in the uppermost ,ludlow or ,silurian tilestones4 ,crustaceans also of the genus ,eurypterus are met with4 ,marine or ,devonian ,type4--,we may now speak of the marine type of the ,british strata intermediate between the ,carboniferous and ,silurian1 in treating of which we shall find it much more easy to identify the ,upper1 ,middle1 and ,lower divisions with strata of the same age in other countries4 ,it was not until the year #ahcf that ,sir ,r4 ,murchison and ,professor ,sedgwick discovered that the culmiferous or anthracitic shales and sandstones of ,north ,devon1 several thousand feet thick1 belonged to the coal1 and that the beds below them1 which are of still greater thickness1 and which1 like the carboniferous strata1 had been confounded under the general name 8graywacke10 occupied a geological position corresponding to that of the ,old ,red ,sandstone already described4 ,in this reform they were aided by a suggestion of ,mr4 ,lonsdale1 who1 after studying the ,devonshire fossils1 perceived that they belonged to a peculiar palontological type of intermediate character between the ,carboniferous and ,silurian4 ,it is in the north of ,devon that these formations may best be studied1 where they have been divided into an ,upper1 ,middle1 and ,lower ,group1 and where1 although much contorted and folded1 they have for the most part escaped being altered by intrusive trap-rocks and by granite1 which in ,dartmoor and the more southern parts of the same county have often reduced them to a crystalline or metamorphic state4 ,,devonian ,,series ,,in ,,north ,,devon4 ,,upper ,,devonian ,,or ,,pilton ,,group 7a7 ,sandy slates and schists with fossils1 #cf species out of #aaj common to the ,carboniferous group 7,pilton1 ,barnstaple1 etc471 resting on soft schists in which fossils are very abundant 7,croyde1 etc471 and which pass down into 7b7 ,yellow1 brown1 and red sandstone1 with land plants 7,cyclopteris1 etc47 and marine shells4 ,one zone1 characterised by the abundance of cuculla 7,baggy ,point1 ,marwood1 ,sloly1 etc47 resting on hard grey and reddish sandstone and micaceous flags1 no fossils yet found 7,dulverton1 ,pickwell1 ,down1 etc47 ,,middle ,,devonian ,,or ,,ilfracombe ,,group4 7a7 ,green glossy slates of considerable thickness1 no fossils yet recorded from these beds 7,mortenoe1 ,lee ,bay1 etc474 7b7 ,slates and schists1 with several irregular courses of limestone containing shells and corals like those of the ,plymouth ,limestone 7,combe ,martin1 ,ilfracombe1 etc474 ,,lower ,,devonian ,,or ,,lynton ,,group4 7a7 ,hard1 greenish1 red1 and purple sandstone--no fossils yet found 7,hangman ,hill1 etc474 7b7 ,soft slates with subordinate sandstones--fossils numerous at various horizons--,orthis1 ,corals1 ,encrinites1 etc4 7,valley of ,rocks1 ,lynmouth1 etc474 ,the above table exhibits the sequence of the strata or subdivisions as seen both on the sea-coast of the ,british ,channel and in the interior of ,devon4 ,it will be seen that in all main points it agrees with the table drawn up in #ahfd for the sixth edition of my 8,elements40 ,mr4 ,etheridge#e has since published an excellent account of the different subdivisions of the rocks and their fossils1 and has also pointed out their relation to the corresponding marine strata of the ,continent4 ,the slight modifications introduced in my table since #ahfd are the result of a tour made in #ahgj in company with ,mr4 ,t4 ,mck4 ,hughes1 when we had the advantage of ,mr4 ,etheridge's memoir as our guide4 ,the place of the sandstones of the ,foreland is not yet clearly made out1 as they are cut off by a great fault and disturbance4 ,fig4 #ejh3 ,spirifera disjuncta4 ,fig4 #eji3 ,phacops latifrons4 ,upper ,devonian ,rocks4--,the slates and sandstones of ,barnstaple 7a and b of the preceding section7 contain the shell ,spirifera disjuncta1 ,sowerby 7,s4 ,verneuilii1 ,murch471 7see ,fig4 #ejh71 which has a very wide range in ,europe1 ,asia ,minor1 and even ,china2 also ,strophalosia caperata1 together with the large trilobite ,phacops latifrons1 ,bronn4 7,see ,fig4 #eji71 which is all but world-wide in its distribution4 ,the fossils are numerous1 and comprise about #aej species of mollusca1 a fifth of which pass up into the overlying ,carboniferous rocks4 ,to this ,upper ,devonian belong a series of limestones and slates well developed at ,petherwyn1 in ,cornwall1 where they have yielded #ge species of fossils4 ,the genus of ,cephalopoda called ,clymenia 7,fig4 #eaj7 is represented by no less than eleven species1 and strata occupying the same position in ,germany are called ,clymenien-,kalk1 or sometimes ,cypridinen-,schiefer1 on account of the number of minute bivalve shells of the crustacean called ,cypridina serrato-striata 7,fig4 #eaa71 which is found in these beds1 in the ,rhenish provinces1 the ,harz1 ,saxony1 and ,silesia1 as well as in ,cornwall and ,belgium4 ,middle ,devonian ,rocks4--,we come next to the most typical portion of the ,devonian system1 including the great limestones of ,plymouth and ,torbay1 replete with shells1 trilobites1 and corals4 ,of the corals #ea species are enumerated by ,mr4 ,etheridge1 none of which pass into the ,carboniferous formation4 ,among the genera we find ,favosites1 ,heliolites1 and ,cyathophyllum4 ,the two former genera are very frequent in ,silurian rocks3 some few even of the species are said to be common to the ,devonian and ,silurian groups1 as1 for example1 ,favosites cervicornis 7,fig4 #eac71 one of the commonest of all the ,devonshire fossils4 ,the ,cyathophyllum cspitosum 7,fig4 #ead7 and ,heliolites pyriformis 7,fig4 #eab7 are species peculiar to this formation4 ,fig4 #eaj3 ,clymenia linearis4 ,fig4 #eaa3 ,cypridina serrato-striata4 ,fig4 #eab3 ,heliolites porosa4 ,fig4 #eac3 ,favosites cervicornis4 ,fig4 #ead3 ,cyathophyllum cspitosum4 ,fig4 #eae3 ,stringocephalus ,burtini4 ,fig4 #eaf3 ,uncites ,gryphus4 ,with the above are found no less than eleven genera of stone-lilies or crinoids1 some of them1 such as ,cupressocrinites1 distinct from any ,carboniferous forms4 ,the mollusks1 also1 are no less characteristic2 of #fh species of ,brachiopoda1 ten only are common to the ,carboniferous ,limestone4 ,the ,stringocephalus ,burtini 7,fig4 #eae7 and ,uncites ,gryphus 7,fig4 #eaf7 may be mentioned as exclusively ,middle ,devonian genera1 and extremely characteristic of the same division in ,belgium4 ,the ,stringocephalus is also so abundant in the ,middle ,devonian of the banks of the ,rhine as to have suggested the name of ,stringocephalus ,limestone4 ,fig4 #eag3 ,megalodon cucullatus4 ,the only two species of ,brachiopoda common to the ,silurian and ,devonian formations are ,atrypa reticularis 7,fig4 #ecb71 which seems to have been a cosmopolite species1 and ,strophomena rhomboidalis4 ,among the peculiar lamellibranchiate bivalves common to the ,plymouth limestone of ,devonshire and the ,continent1 we find the ,megalodon 7,fig4 #eag74 ,there are also twelve genera of ,gasteropods which have yielded #cf species1 four of which pass to the ,carboniferous group1 namely ,macrocheilus1 ,acroculia1 ,euomphalus1 and ,murchisonia4 ,pteropods occur1 such as ,conularia 7,fig4 #eah71 and ,cephalopods1 such as ,cyrtoceras1 ,gyroceras1 ,orthoceras1 and others1 nearly all of genera distinct from those prevailing in the ,upper ,devonian ,limestone1 or ,clymenien-kalk of the ,germans already mentioned4 ,although but few species of ,trilobites occur1 the characteristic ,bronteus flabellifer 7,fig4 #eai7 is far from rare1 and all collectors are familiar with its fan-like tail4 ,in this same group1 called1 as before stated1 the ,stringocephalus1 or ,eifel ,limestone1 in ,germany1 several fish remains have been detected1 and among others the remarkable genus ,coccosteus1 covered with its tuberculated bony armour2 and these ichthyolites serve1 as ,sir ,r4 ,murchison observes 7,siluria1 p4 #cfb71 to identify this middle marine ,devonian with the ,old ,red ,sandstone of ,britain and ,russia4 ,fig4 #eah3 ,conularia ornata4,fig4 #eai3 ,bronteus flabellifer4 ,fig4 #ebj3 ,calceola sandalina4 ,beneath the ,eifel ,limestone 7the great central and typical member of 8the ,devonian0 on the ,continent7 lie certain schists called by ,german writers 8,calceola-schiefer10 because they contain in abundance a fossil body of very curious structure1 ,calceola sandalina 7,fig4 #ebj71 which has been usually considered a brachiopod1 but which some naturalists have lately referred to a ,goniophyllum1 supposing it to be an abnormal form of the order ,zoantharia rugosa 7see ,fig4 #dgd71 differing from all other corals in being furnished with a strong operculum4 ,this is by no means a rare fossil in the slaty limestone of ,south ,devon1 and1 like the ,eifel form1 is confined to the middle group of this country4 ,lower ,devonian ,rocks4--,a great series of sandstones and glossy slates1 with ,crinoids1 ,brachiopods1 and some corals1 occurring on the coast at ,lynmouth and the neighbourhood1 and called the ,lynton ,group 7see ,table p4 #ddi1 form the lowest member of the ,devonian in ,north ,devon4 ,among the #ah species of all classes enumerated by ,mr4 ,etheridge1 two-thirds are common to the ,middle ,devonian1 but only one1 the ubiquitous ,atrypa reticularis1 can with certainty be identified with ,silurian species4 ,among the characteristic forms are ,alveolites suborbicularis1 also common to this formation in the ,rhine1 and ,orthis arcuata1 very widely spread in the ,north ,devon localities4 ,but we may expect a large addition to the number of fossils whenever these strata shall have been carefully searched4 ,the ,spirifer ,sandstone of ,sandberger1 as exhibited in the rocks bordering the ,rhine between ,coblentz and ,caub1 belong to this ,lower division1 and the same broad-winged ,spirifers distinguish the ,devonian strata of ,north ,america4 ,fig4 #eba3 ,spirifora mucronata4 ,fig4 #ebb3 ,homalonotus armatus4 ,among the ,trilobites of this era several large species of ,homalonotus 7,fig4 #ebb7 are conspicuous4 ,the genus is still better known as a ,silurian form1 but the spinose species appear to belong exclusively to the 8,lower ,devonian10 and are found in ,britain1 ,europe1 and the ,cape of ,good ,hope4 ,devonian of ,russia4--,the ,devonian strata of ,russia extend1 according to ,sir ,r4 ,murchison1 over a region more spacious than the ,british ,isles2 and it is remarkable that1 where they consist of sandstone like the 8,old ,red0 of ,scotland and ,central ,england1 they are tenanted by fossil fishes often of the same species and still oftener of the same genera as the ,british1 whereas when they consist of limestone they contain shells similar to those of ,devonshire1 thus confirming1 as ,sir ,roderick has pointed out1 the contemporaneous origin which had been previously assigned to formations exhibiting two very distinct mineral types in different parts of ,britain4#f ,the calcareous and the arenaceous rocks of ,russia above alluded to alternate in such a manner as to leave no doubt of their having been deposited in different parts of the same great period4 ,fig4 #ebc3 ,psilophyton princeps4 ,devonian ,strata in the ,united ,states and ,canada4--,between the ,carboniferous and ,silurian strata there intervenes1 in the ,united ,states and ,canada1 a great series of formations referable to the ,devonian group1 comprising some strata of marine origin abounding in shells and corals1 and others of shallow-water and littoral origin in which terrestrial plants abound4 ,the fossils1 both of the deep and shallow water strata1 are very analogous to those of ,europe1 the species being in some cases the same4 ,in ,eastern ,canada ,sir ,w4 ,logan has pointed out that in the peninsula of ,gaspe1 south of the estuary of ,st4 ,lawrence1 a mass of sandstone1 conglomerate1 and shale referable to this period occurs1 rich in vegetable remains1 together with some fish-spines4 ,far down in the sandstones of ,gaspe1 ,dr4 ,dawson found1 in #ahfi1 an entire specimen of the genus ,cephalaspis1 a form so characteristic1 as we have already seen1 of the ,scotch ,lower ,old ,red ,sandstone4 ,some of the sandstones are ripple-marked1 and towards the upper part of the whole series a thin seam of coal has been observed1 measuring1 together with some associated carbonaceous shale1 about three inches in thickness4 ,it rests on an under-clay in which are the roots of ,psilophyton 7see ,fig4 #ebc74 ,at many other levels rootlets of this same plant have been shown by ,principal ,dawson to penetrate the clays1 and to play the same part as do the rootlets of ,stigmaria in the coal formation4 ,we had already learnt from the works of ,gppert1 ,unger1 and ,bronn that the ,european plants of the ,devonian epoch resemble generically1 with few exceptions1 those already known as ,carboniferous2 and ,dr4 ,dawson1 in #ahei1 enumerated #cb genera and #fi species which he had then obtained from the ,state of ,new ,york and ,canada4 ,a perusal of his catalogue1#g comprising ,conifer1 ,sigillari1 ,calamites1 ,asterophyllites1 ,lepidodendra1 and ferns of the genera ,cyclopteris1 ,neuropteris1 ,sphenopteris1 and others1 together with fruits1 such as ,cardiocarpum and ,trigonocarpum1 might dispose geologists to believe that they were presented with a list of ,carboniferous fossils1 the difference of the species from those of the coal-measures1 and even a slight admixture of genera unknown in ,europe1 being naturally ascribed to geographical distribution and the distance of the ,new from the ,old ,world4 ,but fortunately the coal formation is fully developed on the other side of the ,atlantic1 and is singularly like that of ,europe1 both lithologically and in the species of its fossil plants4 ,there is also the most unequivocal evidence of relative age afforded by superposition1 for the ,devonian strata in the ,united ,states are seen to crop out from beneath the ,carboniferous on the borders of ,pennsylvania and ,new ,york1 where both formations are of great thickness4 ,the number of ,american ,devonian plants has now been raised by ,dr4 ,dawson to #abj1 to which we may add about #hj from the ,european flora of the same age1 so that already the vegetation of this period is beginning to be nearly half as rich as that of the coal-measures which have been studied for so much longer a time and over so much wider an area4 ,the ,psilophyton above alluded to is believed by ,dr4 ,dawson to be a lycopodiaceous plant1 branching dichotomously 7see ,p4 princeps1 ,fig4 #ebc71 with stems springing from a rhizome1 which last has circular areoles1 much resembling those of ,stigmaria1 and like it sending forth cylindrical rootlets4 ,the extreme points of some of the branchlets are rolled up so as to resemble the croziers or circinate vernation of ferns2 the leaves or bracts1 a1 supposed to belong to the same plant1 are described by ,dawson as having inclosed the fructification4 ,the remains of ,psilophyton princeps have been traced through all the members of the ,devonian series in ,america1 and ,dr4 ,dawson has lately recognised it in specimens of ,old ,red ,sandstone from the north of ,scotland4 ,the monotonous character of the ,carboniferous flora might be explained by imagining that we have only the vegetation handed down to us of one set of stations1 consisting of wide swampy flats4 ,but ,dr4 ,dawson supposes that the geographical conditions under which the ,devonian plants grew were more varied1 and had more of an upland character4 ,if so1 the limitation of this more ancient flora1 represented by so many genera and species1 to the gymnospermous and cryptogamous orders1 and the absence or extreme rarity of plants of higher grade1 lead us naturally to speculate on the theory of progressive development1 however difficult it may be to avail ourselves of this explanation1 so long as we meet with even a few exceptional cases of what may seem to be monocotyledonous or dicotyledonous exogens4 ,devonian ,insects of ,canada4--,the earliest known insects were brought to light in #ahfe in the ,devonian strata of ,st4 ,john's1 ,new ,brunswick1 and are referred by ,mr4 ,scudder to four species of ,neuroptera4 ,one of them is a gigantic ,ephemera1 and measured five inches in expanse of wing4 ,like many other ancient animals1 says ,dr4 ,dawson1 they show a remarkable union of characters now found in distinct orders of insects1 or constitute what have been named 8synthetic types40 ,of this kind is a stridulating or musical apparatus like that of the cricket in an insect otherwise allied to the ,neuroptera4 ,this structure1 as ,dr4 ,dawson observes1 if rightly interpreted by ,mr4 ,scudder1 introduces us to the sounds of the ,devonian woods1 bringing before our imagination the trill and hum of insect life that enlivened the solitudes of these strange old forests4 #a ,siluria1 #dth ed41 p4 #bfe4 #b ,siluria1 #dth ed41 p4 #beh4 #c ,abridged from crossotos1 a fringe1 and pteryx1 a fin4 #d ,powrie1 ,geol4 ,quart4 ,journ41 vol4 xx1 p4 #dag4 #e ,quart4 ,geol4 ,journ41 vol4 xxiii41 #ahfg4 #f ,murchison's ,siluria1 p4 #cbi4 #g ,quart4 ,geol4 ,journ41 vol4 xv1 p4 #dgg1 #ahei2 also vol4 xviii1 p4 #bif1 #ahfb4 ,,chapter ,,xxvi4 ,,silurian ,,group4 ,classification of the ,silurian ,rocks4 -- ,ludlow ,formation and ,fossils4 -- ,bone-bed of the ,upper ,ludlow4 -- ,lower ,ludlow ,shales with ,pentamerus4 -- ,oldest known ,remains of fossil ,fish4 -- ,table of the progressive ,discovery of ,vertebrata in older ,rocks4 -- ,wenlock ,formation1 ,corals1 ,cystideans and ,trilobites4 -- ,llandovery ,group or ,beds of ,passage4 -- ,lower ,silurian ,rocks4 -- ,caradoc and ,bala ,beds4 -- ,brachiopoda4 -- ,trilobites4 -- ,cystide4 -- ,graptolites4 -- ,llandeilo ,flags4 -- ,arenig or ,stiper-stones ,group4 -- ,foreign ,silurian ,equivalents in ,europe4 -- ,silurian ,strata of the ,united ,states4 -- ,canadian ,equivalents4 -- ,amount of specific ,agreement of ,fossils with those of ,europe4 ,classification of the ,silurian ,rocks4--,we come next in descending order to that division of ,primary or ,palozoic rocks which immediately underlie the ,devonian group or ,old ,red ,sandstone4 ,for these strata ,sir ,roderick ,murchison first proposed the name of ,silurian when he had studied and classified them in that part of ,wales and some of the contiguous counties of ,england which once constituted the kingdom of the ,silures1 a tribe of ancient ,britons4 ,the following table will explain the two principal divisions1 ,upper and ,lower1 of the ,silurian rocks1 and the minor subdivisions usually adopted1 comprehending all the strata originally embraced in the ,silurian system by ,sir ,roderick ,murchison4 ,the formations below the ,arenig or ,stiper-stones group are treated of in the next chapter1 when the 8,primordial0 or ,cambrian group is described4 ,,upper ,,silurian ,,rocks4 ,thickness in feet #a4 ,,ludlow ,,formation3 a4 ,upper ,ludlow beds #ghj b4 ,lower ,ludlow beds3 #a1jej #b4 ,,wenlock ,,formation3 a4 ,wenlock limestone and shale above #d1jjj b4 ,woolhope limestone and shale1 and ,denbighshire grits3 #c4 ,,llandovery ,,formation 7,beds of passage between ,upper and ,lower ,silurian73 a4 ,upper ,llandovery 7,may-,hill beds73 #hjj b4 ,lower ,llandovery3 #fjj-a1jjj ,,lower ,,silurian ,,rocks4 #a4 ,,bala ,,and ,,caradoc ,,beds1 including volcanic rocks3 #ab1jjj #b4 ,,llandeilo ,,flags1 including volcanic rocks3 #d1ejj #c4 ,,arenig ,,or ,,stiper-,,stones ,,group1 including volcanic rocks3 above #aj1jjj ,,upper ,,silurian ,,rocks4 #a4 ,ludlow ,formation4--,this member of the ,upper ,silurian group1 as will be seen by above table1 is of great thickness1 and subdivided into two parts--the ,upper ,ludlow and the ,lower ,ludlow4 ,each of these may be distinguished near the town of ,ludlow1 and at other places in ,shropshire and ,herefordshire1 by peculiar organic remains2 but out of more than #ejj species found in the ,ludlow formation as a whole1 not more than five species per hundred are common to the overlying ,devonian4 ,the student may refer to the excellent tables given in the last edition of ,sir ,r4 ,murchison's ,siluria for a list of the organic remains of all classes distributed through the different subdivisions of the ,upper and ,lower ,silurian4 a4 ,upper ,ludlow3 ,downton ,sandstone4--,at the top of this subdivision there occur beds of fine-grained yellowish sandstone and hard reddish grits which were formerly referred by ,sir ,r4 ,murchison to the ,old ,red ,sandstone1 under the name of 8,tilestones40 ,in mineral character this group forms a transition from the ,silurian to the ,old ,red ,sandstone1 the strata of both being conformable2 but it is now ascertained that the fossils agree in great part specifically1 and in general character entirely1 with those of the underlying ,upper ,ludlow rocks4 ,among these are ,orthoceras bullatum1 ,platyschisma helicites1 ,bellerophon trilobatus1 ,chonetes lata1 etc41 with numerous defenses of fishes4 ,these beds1 therefore1 now generally called the 8,downton ,sandstone10 are classed as the newest member of the ,upper ,silurian4 ,they are well seen at ,downton ,castle1 near ,ludlow1 where they are quarried for building1 and at ,kington1 in ,herefordshire4 ,in the latter place1 as well as at ,ludlow1 crustaceans of the genera ,pterygotus 7for genus see ,fig4 #ejd7 and ,eurypterus are met with4 ,bone-bed of the ,upper ,ludlow4--,at the base of the ,downton sandstones there occurs a bone-bed which deserves especial notice as affording the most ancient example of fossil fish occurring in any considerable quantity4 ,it usually consists of one or two thin layers of brown bony fragments near the junction of the ,old ,red ,sandstone and the ,ludlow rocks1 and was first observed by ,sir ,r4 ,murchison near the town of ,ludlow1 where it is three or four inches thick4 ,it has since been traced to a distance of #de miles from that point into ,gloucestershire and other counties1 and is commonly not more than an inch thick1 but varies to nearly a foot4 ,near ,ludlow two bone-beds are observable1 with #ad feet of intervening strata full of ,upper ,ludlow fossils4#a ,at that point immediately above the upper fish-bed numerous small globular bodies have been found1 which were determined by ,dr4 ,hooker to be the sporangia of a cryptogamic land-plant1 probably lycopodiaceous4 ,fig4 #ebd3 ,onchus tenuistriatus4 ,fig4 #ebe3 ,shagreen-scales of a placoid fish1 ,thelodus parvidens4 ,most of the fish have been referred by ,agassiz to his placoid order1 some of them to the genus ,onchus1 to which the spine 7,fig4 #ebd7 and the minute scales 7,fig4 #ebe7 are supposed to belong4 ,it has been suggested1 however1 that ,onchus may be one of those ,acanthodian fish referred by ,agassiz to his ,ganoid order1 which are so characteristic of the base of the ,old ,red ,sandstone in ,forfarshire1 although the species of the ,old ,red are all different from these of the ,silurian beds now under consideration4 ,fig4 #ebf3 ,plectrodus mirabilis4 ,the jaw and teeth of another predaceous genus 7,fig4 #ebf7 have also been detected1 together with some specimens of ,pteraspis ,ludensis4 ,as usual in bone-beds1 the teeth and bones are1 for the most part1 fragmentary and rolled4 ,fig4 #ebg3 ,orthis elegantula4,fig4 #ebh3 ,rhynchonella navicula4 ,grey ,sandstone and ,mudstone1 etc4--,the next subdivision of the ,upper ,ludlow consists of grey calcareous sandstone1 or very commonly a micaceous stone1 decomposing into soft mud1 and contains1 besides the shells mentioned aon page #dei1 ,lingula cornea1 ,orthis orbicularis1 a round variety of ,o4 elegantula1 ,modiolopsis platyphylla1 ,grammysia cingulata1 all characteristic of the ,upper ,ludlow4 ,the lowest or mud-stone beds contain ,rhynchonella navicula 7,fig4 #ebh71 which is common to this bed and the ,lower ,ludlow4 ,as usual in ,palozoic strata older than the coal1 the brachiopodous mollusca greatly outnumber the lamellibranchiate 7see p4 #dgj72 but the latter are by no means unrepresented4 ,among other genera1 for example1 we observe ,avicula and ,pterinea1 ,cardiola1 ,ctenodonta 7sub-genus of ,nucula71 ,orthonota1 ,modiolopsis1 and ,palarca4 ,some of the ,upper ,ludlow sandstones are ripple-marked1 thus affording evidence of gradual deposition2 and the same may be said of the accompanying fine argillaceous shales1 which are of great thickness1 and have been provincially named 8mud-stones40 ,in some of these shales stems of crinoidea are found in an erect position1 having evidently become fossil on the spots where they grew at the bottom of the sea4 ,the facility with which these rocks1 when exposed to the weather1 are resolved into mud1 proves that1 notwithstanding their antiquity1 they are nearly in the state in which they were first thrown down4 ,fig4 #ebi3 ,pentamerus ,knightii4 b4 ,lower ,ludlow ,beds4--,the chief mass of this formation consists of a dark grey argillaceous shale with calcareous concretions1 having a maximum thickness of #ajjj feet4 ,in some places1 and especially at ,aymestry1 in ,herefordshire1 a subcrystalline and argillaceous limestone1 sometimes #ej feet thick1 overlies the shale4 ,sir ,r4 ,murchison therefore classes this ,aymestry limestone as holding an intermediate position between the ,upper and ,lower ,ludlow1 but ,mr4 ,lightbody remarks that at ,mocktrie1 near ,leintwardine1 the ,lower ,ludlow shales1 with their characteristic fossils1 occur both above and below a similar limestone4 ,this limestone around ,aymestry and ,sedgeley is distinguished by the abundance of ,pentamerus ,knightii1 ,sowerby 7,fig4 #ebi71 also found in the ,lower ,ludlow and ,wenlock shale4 ,this genus of brachiopoda was first found in ,silurian strata1 and is exclusively a palozoic form4 ,the name was derived from pente1 five1 and meros1 a part1 because both valves are divided by a central septum1 making four chambers1 and in one valve the septum itself contains a small chamber1 making five4 ,the size of these septa is enormous compared with those of any other brachiopod shell2 and they must nearly have divided the animal into two equal halves2 but they are1 nevertheless1 of the same nature as the septa or plates which are found in the interior of ,spirifera1 ,terebratula1 and many other shells of this order4 ,messrs4 ,murchison and ,de ,verneuil discovered this species dispersed in myriads through a white limestone of ,upper ,silurian age1 on the banks of the ,is1 on the eastern flank of the ,urals in ,russia1 and a similar species is frequent in ,sweden4 ,fig4 #ecj3 ,lingula ,lewisii4 ,three other abundant shells in the ,aymestry limestone are1 first1 ,lingula ,lewisii 7,fig4 #ecj72 second1 ,rhynchonella ,wilsoni1 ,sowerby 7,fig4 #eca71 which is also common to the ,lower ,ludlow and ,wenlock limestone2 third1 ,atrypa reticularis1 ,linn4 7,fig4 #ecb71 which has a very wide range1 being found in every part of the ,upper ,silurian system1 and even ranging up into the ,middle ,devonian series4 ,fig4 #eca3 ,rhynchonella 7,terebratula7 ,wilsoni4 ,the ,aymestry ,limestone contains many shells1 especially brachiopoda1 corals1 trilobites1 and other fossils1 amounting on the whole to #gd species1 all except three or four being common to the beds either above or below4 ,fig4 #ecb3 ,atrypa reticularis4 ,the ,lower ,ludlow ,shale contains1 among other fossils1 many large cephalopoda not known in newer rocks1 as the ,phragmoceras of ,broderip1 and the ,lituites of ,breynius 7see ,figs4 #ecc1 #ecd74 ,the latter is partly straight and partly convoluted in a very flat spire4 ,the ,orthoceras ,ludense 7,fig4 #ece71 as well as the cephalopod last mentioned1 occurs in this member of the species4 ,fig4 #ecc3 ,phragmoceras ventricosum4 ,a species of ,graptolite1 ,g4 priodon1 ,bronn 7,fig4 #ede71 occurs plentifully in the ,lower ,ludlow4 ,this fossil1 referred1 though somewhat doubtfully1 to a form of hydrozoid or sertularian polyp1 has not yet been met with in strata above the ,silurian4 ,star-fish1 as ,sir ,r4 ,murchison points out1 are by no means rare in the ,lower ,ludlow rock4 ,these fossils1 of which six extinct genera are now known in the ,ludlow series1 represented by #ah species1 remind us of various living forms now found in our ,british seas1 both of the families ,asteriad and ,ophiurid4 ,fig4 #ecd3 ,lituites 7,trochoceras7 giganteus4 ,fig4 #ece3 ,fragment of ,orthoceras ,ludense4 ,oldest known ,fossil ,fish4--,until #ahei there was no example of a fossil fish older than the bone-bed of the ,upper ,ludlow1 but in that year a specimen of ,pteraspis was found at ,church ,hill1 near ,leintwardine1 in ,shropshire1 by ,mr4 ,j4 ,e4 ,lee of ,caerleon1 ,f4,g4,s41 in shale below the ,aymestry limestone1 associated with fossil shells of the ,lower ,ludlow formation--shells which differ considerably from those characterising the ,upper ,ludlow already described4 ,this discovery is of no small interest as bearing on the theory of progressive development1 because1 according to ,professor ,huxley1 the genus ,pteraspis is allied to the sturgeon1 and therefore by no means of low grade in the piscine class4 ,it is a fact well worthy of notice that no remains of vertebrata have yet been met with in any strata older than the ,lower ,ludlow4 ,when we reflect on the hundreds of ,mollusks1 ,echinoderms1 ,trilobites1 ,corals1 and other fossils already obtained from more ancient ,silurian formations1 ,upper1 ,middle1 and ,lower1 we may well ask whether any set of fossiliferous rocks newer in the series were ever studied with equal diligence1 and over so vast an area1 without yielding a single ichthyolite4 ,yet we must hesitate before we accept1 even on such evidence1 so sweeping a conclusion1 as that the globe1 for ages after it was inhabited by all the great classes of invertebrata1 remained wholly untenanted by vertebrate animals4 ,dates of the ,discovery of different ,classes of ,fossil ,vertebrata2 showing the gradual progress made in tracing them to rocks of higher antiquity4 ,year ,formations ,geographical localities ,mammalia #agih ,upper ,eocene ,paris 7,gypsum of ,montmartre74#a #ahah ,lower ,oolite ,stonesfield4#b #ahdg ,upper ,trias ,stuttgart4#c ,aves #aghb ,upper ,eocene ,paris 7,gypsum of ,montmartre74#d #ahci ,lower ,eocene ,isle of ,sheppey 7,london ,clay74#e #ahed ,lower ,eocene ,woolwich ,beds4#f #ahee ,lower ,eocene ,mendon 7,plastic ,clay74#g #aheh ,chloritic ,series1 or ,upper ,greensand ,cambridge4#h #ahfc ,upper ,oolite ,solenhofen4#i ,reptilia #agaj ,permian 7or ,zechstein7 ,thuringia4#aj #ahdd ,carboniferous ,saarbrck1 near ,trves4#aa ,pisces #agji ,permian 7or ,kupferschiefer7 ,thuringia4#ab #agic ,carboniferous 7,mountain ,limestone7 ,glasgow4#ac #ahbh ,devonian ,caithness4#ad #ahdj ,upper ,ludlow ,ludlow4#ae #ahei ,lower ,ludlow ,leintwardine4#af #a4 ,george ,cuvier1 ,bulletin ,soc4 ,philom4 xx4 #b4 ,in #ahah1 ,cuvier1 visiting the ,museum of ,oxford1 decided on the mammalian character of a jaw from ,stonesfield4 ,see also p4 #cdg4 #c4 ,prof4 ,plieninger4 ,see p4 #cfh4 #d4 ,cuvier1 ,ossemens ,foss4 ,art4 8,oiseaux40 #e4 ,prof4 ,owen1 ,geol4 ,trans41 #bnd series1 vol4 vi1 p4 #bjc1 #ahci4 #f4 ,upper part of the ,woolwich beds4 ,prestwich1 ,quart4 ,geol4 ,journ41 vol4 x1 p4 #aeg4 #g4 ,gastornis ,parisiensis4 ,owen1 ,quart4 ,geol4 ,journ41 vol4 xii1 p4 #bjd1 #ahef4 #h4 ,coprolitic bed1 in the ,upper ,greensand4 ,see p4 #bii4 #i4 ,the ,archopteryx macrura1 ,owen4 ,see p4 #cch4 #aj4 ,the fossil monitor of ,thuringia 7,protosaurus ,speneri1 ,v4 ,meyer7 was figured by ,spener of ,berlin in #ahaj4 7,miscel4 ,berlin47 #aa4 ,see p4 #djf4 #ab4 ,memorabilia ,saxoni ,subterr41 ,leipsic1 #agji4 #ac4 ,history of ,rutherglen by ,rev4 ,david ,ure1 #agic4 #ad4 ,sedgwick and ,murchison1 ,geol4 ,trans41 #bnd series1 vol4 ii1 p4 #ada1 #ahbh4 #ae4 ,sir ,r4 ,murchison4 ,see p4 #dei4 #af4 ,see p4 #dfa4 ,obs4--,the evidence derived from foot-prints1 though often to be relied on1 is omitted in the above table1 as being less exact than that founded on bones and teeth4 ,in the preceding ,table a few dates are set before the reader of the discovery of different classes of animals in ancient rocks1 to enable him to perceive at a glance how gradual has been our progress in tracing back the signs of vertebrata to formations of high antiquity4 ,such facts may be useful in warning us not to assume too hastily that the point which our retrospect may have reached at the present moment can be regarded as fixing the date of the first introduction of any one class of beings upon the earth4 #b4 ,wenlock ,formation4--,we next come to the ,wenlock formation1 which has been divided 7see ,table1 p4 #deh7 into ,wenlock limestone1 ,wenlock shale1 and ,woolhope limestone and ,denbighshire grits4 ,fig4 #ecf3 ,halysites catenularius4 a4 ,wenlock ,limestone4--,this limestone1 otherwise well known to collectors by the name of the ,dudley ,limestone1 forms a continuous ridge in ,shropshire1 ranging for about #bj miles from ,s4,w4 to ,n4,e41 about a mile distant from the nearly parallel escarpment of the ,aymestry limestone4 ,this ridgy prominence is due to the solidity of the rock1 and to the softness of the shales above and below it4 ,near ,wenlock it consists of thick masses of grey subcrystalline limestone1 replete with corals1 encrinites1 and trilobites4 ,it is essentially of a concretionary nature2 and the concretions1 termed 8ball-stones0 in ,shropshire1 are often enormous1 even #hj feet in diameter4 ,they are of pure carbonate of lime1 the surrounding rock being more or less argillaceous#b ,sometimes in the ,malvern ,hills this limestone1 according to ,professor ,phillips1 is oolitic4 ,fig4 #ecg3 ,favosites ,gothlandica4 ,among the corals1 in which this formation is so rich1 #ec species being known1 the 8chain-coral10 ,halysites catenularius 7,fig4 #ecf71 may be pointed out as one very easily recognised1 and widely spread in ,europe1 ranging through all parts of the ,silurian group1 from the ,aymestry limestone to near the bottom of the ,llandeilo rocks4 ,another coral1 the ,favosites ,gothlandica 7,fig4 #ecg71 is also met with in profusion in large hemispherical masses1 which break up into columnar and prismatic fragments1 like that here figured 7,fig4 #ecg1 b74 ,another common form in the ,wenlock limestone is the ,omphyma turbinatum 7,fig4 #ech71 which1 like many of its modern companions1 reminds us of some cup-corals2 but all the ,silurian genera belong to the palozoic type before mentioned 7p4 #dcb71 exhibiting the quadripartite arrangement of the septalamell within the cup4 ,fig4 #ech3 ,omphyma turbinatum4,fig4 #eci3 ,pseudocrinites bifasciatus4 ,among the numerous ,crinoids1 several peculiar species of ,cyathocrinus 7for genus see ,figs4 #dgh1 #dgi7 contribute their calcareous stems1 arms1 and cups towards the composition of the ,wenlock limestone4 ,of ,cystideans there are a few very remarkable forms1 most of them peculiar to the ,upper ,silurian formation1 as1 for example1 the ,pseudocrinites1 which was furnished with pinnated fixed arms1#c as represented in ,fig4 #eci4 ,fig4 #edj3 ,strophomena 7,leptna7 depressa4 ,the ,brachiopoda are1 many of them1 of the same species as those of the ,aymestry limestone2 as1 for example1 ,atrypa reticularis 7,fig4 #ecb71 and ,strophomena depressa 7,fig4 #edj72 but the latter species ranges also from the ,ludlow rocks1 through the ,wenlock shale1 to the ,caradoc ,sandstone4 ,fig4 #eda3 ,calymene ,blumenbachii4 ,the crustaceans are represented almost exclusively by ,trilobites1 which are very conspicuous1 #bb being peculiar4 ,the ,calymene ,blumenbachii 7,fig4 #eda71 called the 0,dudley ,trilobite10 was known to collectors long before its true place in the animal kingdom was ascertained4 ,it is often found coiled up like the common ,oniscus or wood-louse1 and this is so usual a circumstance among certain genera of trilobites as to lead us to conclude that they must have habitually resorted to this mode of protecting themselves when alarmed4 ,the other common species is the ,phacops caudatus 7,asaphus caudatus71 ,brong4 7see ,fig4 #edb71 and this is conspicuous for its large size and flattened form4 ,sphrexochus mirus 7,fig4 #edc7 is almost a globe when rolled up1 the forehead or glabellum of this species being extremely inflated4 ,the ,homalonotus1 a form of ,trilobite in which the tripartite division of the dorsal crust is almost lost 7see ,fig4 #edd71 is very characteristic of this division of the ,silurian series4 ,fig4 #edb3 ,phacops 7,asaphus7 caudatus4,fig4 #edc3 ,sphrexochus mirus4 ,wenlock ,shale4--,this1 observes ,sir ,r4 ,murchison1 is infinitely the largest and most persistent member of the ,wenlock formation1 for the limestone often thins out and disappears4 ,the shale1 like the ,lower ,ludlow1 often contains elliptical concretions of impure earthy limestone4 ,fig4 #edd3 ,homalonotus delphinocephalus4 ,in the ,malvern district it is a mass of finely levigated argillaceous matter1 attaining1 according to ,professor ,phillips1 a thickness of #fdj feet1 but it is sometimes more than #ajjj feet thick in ,wales1 and is worked for flag-stones and slates4 ,the prevailing fossils1 besides corals and trilobites1 and some crinoids1 are several small species of ,orthis1 ,cardiola1 and numerous thin-shelled species of ,orthoceratites4 ,about six species of ,graptolite1 a peculiar group of sertularian fossils before alluded to 7p4 #dfc7 as being confined to ,silurian rocks1 occur in this shale4 ,of fossils of this genus1 which is very characteristic of the ,lower ,silurian1 ,i shall again speak in the sequel 7p4 #dgd74 ,fig4 #ede3 ,graptolithus priodon4 b4 ,woolhope ,beds4--,though not always recognised as a separate subdivision of the ,wenlock1 the ,woolhope beds1 which underlie the ,wenlock shale1 are of great importance4 ,usually they occur as massive or nodular limestones1 underlaid by a fine shale or flag-stone2 and in other cases1 as in the noted ,denbighshire sandstones1 as a coarse grit of very great thickness4 ,this grit forms mountain ranges through ,north and ,south ,wales1 and is generally marked by the great sterility of the soil where it occurs4 ,it contains the usual ,wenlock fossils1 but with the addition of some common in the uppermost ,ludlow rock1 such as ,chonetes lata and ,bellerophon trilobatus4 ,the chief fossils of the ,woolhope limestone are ,illnus ,barriensis1 ,homalonotus delphinocephalus 7,fig4 #edd71 ,strophomena imbrex1 and ,rhynchonella ,wilsoni 7,fig4 #eca74 ,the latter attains in the ,woolhope beds an unusual size for the species1 the specimens being sometimes twice as large as those found in the ,wenlock limestone4 ,in some places below the ,wenlock formation there are shales of a pale or purple colour1 which near ,tarannon attain a thickness of about #ajjj feet2 they can be traced through ,radnor and ,montgomery to ,north ,wales1 according to ,messrs4 ,jukes and ,aveline4 ,by the latter geologist they have been identified with certain shales above the ,may-,hill ,sandstone1 near ,llandovery1 but1 owing to the extreme scarcity of fossils1 their exact position remains doubtful4 #c4 ,llandovery ,group--,beds of ,passage4--,we now come to beds respecting the classification of which there has been much difference of opinion1 and which in fact must be considered as beds of passage between ,upper and ,lower ,silurian4 ,i formerly adopted the plan of those who class them as ,middle ,silurian1 but they are scarcely entitled to this distinction1 since after about #adjj ,silurian species have been compared the number peculiar to the group in question only gives them an importance equal to such minor subdivisions as the ,ludlow or ,bala groups4 ,i therefore prefer to regard them as the base of the ,upper ,silurian1 to which group they are linked by more than twice as many species as to the ,lower ,silurian4 ,by this arrangement the line of demarkation between the two great divisions1 though confessedly arbitrary1 is less so than by any other4 ,they are called ,llandovery ,rocks1 from a town in ,south ,wales1 in the neighbourhood of which they are well developed1 and where1 especially at a hill called ,noeth ,grug1 in spite of several faults1 their relations to one another can be clearly seen4 a4 ,upper ,llandovery or ,may-,hill ,sandstone4--,the ,may-,hill group1 which has also been named 0,upper ,llandovery10 by ,sir ,r4 ,murchison1 ranges from the west of the ,longmynd to ,builth1 ,llandovery1 and ,llandeilo1 and to the sea in ,marlow's ,bay1 where it is seen in the cliffs4 ,it consists of brownish and yellow sandstones with calcareous nodules1 having sometimes a conglomerate at the base derived from the waste of the ,lower ,silurian rocks4 ,these ,may-,hill beds were formerly supposed to be part of the ,caradoc formation1 but their true position was determined by ,professor ,sedgwick#d to be at the base of the ,upper ,silurian proper4 ,the more calcareous portions of the rock have been called the ,pentamerus limestone1 because ,pentamerus oblongus 7,fig4 #edf7 is very abundant in them4 ,it is usually accompanied by ,p4 7,stricklandinia7 lirata 7,fig4 #edg72 both forms have a wide geographical range1 being also met with in the same part of the ,silurian series in ,russia and the ,united ,states4 ,fig4 #edf3 ,pentamerus oblongus4 ,about #bbh species of fossils are known in the ,may-,hill division1 more than half of which are ,wenlock species4 ,they consist of trilobites of the genera ,illnus and ,calymene2 ,brachiopods of the genera ,orthis1 ,atrypa1 ,leptna1 ,pentamerus1 ,strophomena1 and others2 ,gasteropods of the genera ,turbo1 ,murchisonia 7for genus1 see ,fig4 #efg71 and ,bellerophon2 and ,pteropods of the genus ,conularia4 ,the ,brachiopods1 of which there are #ff species1 are almost all ,upper ,silurian4 ,fig4 #edg3 ,stricklandinia 7,pentamerus7 lirata4 ,fig4 #edh3 ,tentaculites annulatus4 ,among the fossils of the ,may-,hill shelly sandstone at ,malvern1 ,tentaculites annulatus 7,fig4 #edh71 an annelid1 probably allied to ,serpula1 is found4 ,lower ,llandovery ,rocks4--,below the ,may-,hill ,group are the ,lower ,llandovery ,rocks1 which consist chiefly of hard slaty rocks1 and beds of conglomerate from #fjj to #ajjj feet in thickness4 ,the fossils1 which are somewhat rare in the lower beds1 consist of #abh known species1 only eleven of which are peculiar1 #hc being common to the ,may-,hill group above1 and #ic common to the rocks below4 ,stricklandinia 7,pentamerus7 levis1 which is common in the ,lower ,llandovery1 becomes rare in the ,upper1 while ,pentamerus oblongus 7,fig4 #edf71 which is the characteristic shell of the ,upper ,llandovery1 occurs but seldom in the ,lower4 ,,lower ,,silurian ,,rocks4 ,the ,lower ,silurian has been divided into1 first1 the ,bala ,group2 second1 the ,llandeilo flags2 and1 third1 the ,arenig or ,lower ,llandeilo formation4 ,bala and ,caradoc ,beds4--,the ,caradoc sandstone was originally so named by ,sir ,r4 ,i4 ,murchison from the mountain called ,caer ,caradoc1 in ,shropshire2 it consists of shelly sandstones of great thickness1 and sometimes containing much calcareous matter4 ,the rock is frequently laden with the beautiful trilobite called by ,murchison ,trinucleus ,caractaci 7see ,fig4 #eec71 which ranges from the base to the summit of the formation1 usually accompanied by ,strophomena grandis 7see ,fig4 #eea71 and ,orthis vespertilio 7,fig4 #eej71 with many other fossils4 ,fig4 #edi3 ,orthis tricenaria4 ,fig4 #eej3 ,orthis vespertilio4 ,fig4 #eea3 ,orthis 7,strophomena7 grandis4 ,brachiopoda4--,nothing is more remarkable in these beds1 and in the ,silurian strata generally of all countries1 than the preponderance of brachiopoda over other forms of mollusca4 ,their proportional numbers can by no means be explained by supposing them to have inhabited seas of great depth1 for the contrast between the palozoic and the present state of things has not been essentially altered by the late discoveries made in our deep-sea dredgings4 ,we find the living brachiopoda so rare as to form about one forty-fourth of the whole bivalve fauna1 whereas in the ,lower ,silurian rocks of which we are now about to treat1 and where the brachiopoda reach their maximum1 they are represented by more than twice as many species as the ,lamellibranchiate bivalves4 ,there may1 indeed1 be said to be a continued decrease of the proportional number of this lower tribe of mollusca as we proceed from older to newer rocks4 ,in the ,british ,devonian1 for example1 the ,brachiopoda number #ii1 the ,lamellibranchiata #eh2 while in the ,carboniferous their proportions are more than reversed1 the ,lamellibranchiata numbering #ccd species1 and the ,brachiopoda only #aeg4 ,in the ,secondary or ,cainozoic formations the preponderance of the higher grade of bivalves becomes more and more marked1 till in the tertiary strata it approaches that observed in the living creation4 ,while on this subject1 it may be useful to the student to know that a ,brachiopod differs from ordinary bivalves1 mussels1 cockles1 etc41 in being always equal-sided and never quite equi-valved2 the form of each valve being symmetrical1 it may be divided into two equal parts by a line drawn from the apex to the centre of the margin4 ,trilobites4--,in the ,bala and ,caradoc beds the trilobites reach their maximum1 being represented by #aaa species referred to #bc genera4 ,burmeister1 in his work on the organisation of trilobites1 supposes that they swam at the surface of the water in the open sea and near coasts1 feeding on smaller marine animals1 and to have had the power of rolling themselves into a ball as a defence against injury4 ,he was also of opinion that they underwent various transformations analogous to those of living crustaceans4 ,m4 ,barrande1 author of an admirable work on the ,silurian rocks of ,bohemia1 confirms the doctrine of their metamorphosis1 having traced more than twenty species through different stages of growth from the young state just after its escape from the egg to the adult form4 ,he has followed some of them from a point in which they show no eyes1 no joints1 or body rings1 and no distinct tail1 up to the complete form with the full number of segments4 ,this change is brought about before the animal has attained a tenth part of its full dimensions1 and hence such minute and delicate specimens are rarely met with4 ,some of his figures of the metamorphoses of the common ,trinucleus are copied in ,figs4 #eeb and #eec4 ,it was not till #ahgj that ,mr4 ,billings was enabled1 by means of a specimen found in ,canada1 to prove that the trilobite was provided with eight legs4 ,it has been ascertained that a great thickness of slaty and crystalline rocks of ,south ,wales1 as well as those of ,snowdon and ,bala1 in ,north ,wales1 which were first supposed to be of older date than the ,silurian sandstones and mudstones of ,shropshire1 are in fact identical in age1 and contain the same organic remains4 ,at ,bala1 in ,merionethshire1 a limestone rich in fossils occurs1 in which two genera of star-fish1 ,protaster and ,palaster1 are found2 the fossil specimen of the latter 7,fig4 #eed7 being almost as uncompressed as if found just washed up on the sea-beach4 ,besides the star-fish there occur abundance of those peculiar bodies called ,cystide4 ,they are the ,sphronites of old authors1 and were considered by ,professor ,e4 ,forbes as intermediate between the crinoids and echinoderms4 ,the ,echinosphronite here represented 7,fig4 #eee7 is characteristic of the ,caradoc beds in ,wales1 and of their equivalents in ,sweden and ,russia4 ,fig4 #eeb3 ,young individuals of ,trinucleus concentricus4 ,fig4 #eec3 ,trinucleus concentricus4 ,fig4 #eed3 ,palaster asperimus4 ,fig4 #eee3 ,echinosphronites ballicus4 ,with it have been found several other genera of the same family1 such as ,sphronites1 ,hemicosmites1 etc4 ,among the mollusca are ,pteropods of the genus ,conularia of large size 7for genus1 see ,fig4 #eah74 ,about eleven species of ,graptolite are reckoned as belonging to this formation2 they are chiefly found in peculiar localities where black mud abounded4 ,the formation1 when traced into ,south ,wales and ,ireland1 assumes a greatly altered mineral aspect1 but still retains its characteristic fossils4 ,the known fauna of the ,bala group comprises #efe species1 #ceb of which are peculiar1 and #ic1 as before stated1 are common to the overlying ,llandovery rocks4 ,it is worthy of remark that1 when it occurs under the form of trappean tuff 7volcanic ashes of ,de la ,beche71 as in the crest of ,snowdon1 the peculiar species which distinguish it from the ,llandeilo beds are still observable4 ,the formation generally appears to be of shallow-water origin1 and in that respect is contrasted with the group next to be described4 ,professor ,ramsay estimates the thickness of the ,bala ,beds1 including the contemporaneous volcanic rocks1 stratified and unstratified1 as being from #aj1jjj to #ab1jjj feet4 ,fig4 #eef3 ,didymograpsus 7,graptolites7 ,murchisonii4 ,llandeilo ,flags4--,the ,lower ,silurian strata were originally divided by ,sir ,r4 ,murchison into the upper group already described1 under the name of ,caradoc ,sandstone1 and a lower one1 called1 from a town in ,carmarthenshire1 the ,llandeilo flags4 ,the last mentioned strata consist of dark-coloured micaceous flags1 frequently calcareous1 with a great thickness of shales1 generally black1 below them4 ,the same beds are also seen at ,builth1 in ,radnorshire1 where they are interstratified with volcanic matter4 ,a still lower part of the ,llandeilo rocks consists of a black carbonaceous slate of great thickness1 frequently containing sulphate of alumina1 and sometimes1 as in ,dumfriesshire1 beds of anthracite4 ,it has been conjectured that this carbonaceous matter may be due in great measure to large quantities of imbedded animal remains1 for the number of ,graptolites included in these slates was certainly very great4 ,in ,great ,britain eleven genera and about #dj species of ,graptolites occur in the ,llandeilo flags and underlying ,arenig beds4 ,the double ,graptolites1 or those with two rows of cells1 such as ,diplograpsus 7,fig4 #eeg71 are conspicuous4 ,fig4 #eeg3 ,diplograpsus pristis4 ,fig4 #eeh3 ,rastrites peregrinus4 ,fig4 #eei3 ,diplograpsus folium4 ,the brachiopoda of the ,llandeilo flags1 which number #dg species1 are in the main the same as those of the ,caradoc ,sandstone1 but the other mollusca are in great part of different species4 ,in ,europe generally1 as1 for example1 in ,sweden and ,russia1 no shells are so characteristic of this formation as ,orthoceratites1 usually of great size1 and with a wide siphuncle placed on one side instead of being central 7see ,fig4 #efj74 ,fig4 #efj3 ,orthoceras duplex4 ,among other ,cephalopods in the ,llandeilo flags is ,cyrtoceras2 in the same beds also are found ,bellerophon 7see ,fig4 #dhh7 and some ,pteropod shells 7,conularia1 ,theca1 etc471 also in spots where sand abounded1 lamellibranchiate bivalves of large size4 ,the ,crustaceans were plentifully represented by the ,trilobites1 which appear to have swarmed in the ,silurian seas just as crabs and shrimps do in our own2 no less than #bfc species have been found in the ,british ,silurian fauna4 ,the genera ,asaphus 7,fig4 #efa71 ,ogygia 7,fig4 #efb71 and ,trinucleus 7,figs4 #eeb and #eec7 form a marked feature of the rich and varied ,trilobitic fauna of this age4 ,fig4 #efa3 ,asaphus tyrannus4 ,fig4 #efb3 ,ogygia ,buchii4 ,beneath the black slates above described of the ,llandeilo formation1 ,graptolites are still found in great variety and abundance1 and the characteristic genera of shells and trilobites of the ,lower ,silurian rocks are still traceable downward1 in ,shropshire1 ,cumberland1 and ,north and ,south ,wales1 through a vast depth of shaly beds1 in some districts interstratified with trappean formations of contemporaneous origin2 these consist of tuffs and lavas1 the tuffs being formed of such materials as are ejected from craters and deposited immediately on the bed of the ocean1 or washed into it from the land4 ,according to ,professor ,ramsay1 their thickness is about #ccjj feet in ,north ,wales1 including those of the ,lower ,llandeilo4 ,the lavas are feldspathic1 and of porphyritic structure1 and1 according to the same authority1 of an aggregate thickness of #bejj feet4 ,fig4 #efc3 ,arenicolites linearis4 ,arenig or ,stiper-,stones ,group 7,lower ,llandeilo of ,murchison74--,next in the descending order are the shales and sandstones in which the quartzose rocks called ,stiper-,stones in ,shropshire occur4 ,originally these ,stiper-,stones were only known as arenaceous quartzose strata in which no organic remains were conspicuous1 except the tubular burrows of annelids 7see ,fig4 #efc1 ,arenicolites linearis71 which are remarkably common in the ,lowest ,silurian in ,shropshire1 and in the ,state of ,new ,york1 in ,america4 ,they have already been alluded to as occurring by thousands in the ,silurian strata unconformably overlying the ,cambrian1 in the mountain of ,queenaig1 in ,sutherlandshire 7,fig4 #hb74 ,i have seen similar burrows now made on the retiring of the tides in the sands of the ,bristol ,channel1 near ,minehead1 by lob-worms which are dug out by fishermen and used as bait4 ,when the term ,silurian was given by ,sir ,r4 ,murchison1 in #ahce1 to the whole series1 he considered the ,stiper-,stones as the base of the ,silurian system1 but no fossil fauna had then been obtained1 such as could alone enable the geologist to draw a line between this member of the series and the ,llandeilo flags above1 or a vast thickness of rock below1 which was seen to form the ,longmynd hills1 and was called 0unfossiliferous graywacke40 ,professor ,sedgwick had described1 in #ahdc1 strata now ascertained to be of the same age as largely developed in the ,arenig mountain1 in ,merionethshire2 and the ,skiddaw slates in the ,lake-,district of ,cumberland1 studied by the same author1 were of corresponding date1 though the number of fossils was1 in both cases1 too few for the determination of their true chronological relations4 ,the subsequent researches of ,messrs4 ,sedgwick and ,harkness1 in ,cumberland1 and of ,sir ,r4 ,i4 ,murchison and the ,government surveyors in ,shropshire1 have increased the species to more than sixty4 ,these were examined by ,mr4 ,salter1 and shown in the third edition of 0,siluria0 7p4 #eb1 #ahei7 to be quite distinct from the fossils of the overlying ,llandeilo flags4 ,among these the ,obolella plumbea1 glina binodosa1 ,ogygia ,selwynii1 and ,didymograpsus geminus 7,fig4 #efd71 and ,d4 ,hirundo1 are characteristic4 ,fig4 #efd3 ,didymograpsus geminus4 ,but1 although the species are distinct1 the genera are the same as those which characterise the ,silurian rocks above1 and none of the characteristic primordial or ,cambrian forms1 presently to be mentioned1 are intermixed4 ,the same may be said of a set of beds underlying the ,arenig rocks at ,ramsay ,island and other places in the neighbourhood of ,st4 ,david's4 ,these beds1 which have only lately become known to us through the labours of ,dr4 ,hicks1#e present already twenty new species1 the greater part of them allied generically to the ,arenig rocks4 ,this ,arenig group may therefore be conveniently regarded as the base of the great ,silurian system1 a system which1 by the thickness of its strata and the changes in animal life of which it contains the record1 is more than equal in value to the ,devonian1 or ,carboniferous1 or other principal divisions1 whether of primary or secondary date4 ,it would be unsafe to rely on the mere thickness of the strata1 considered apart from the great fluctuations in organic life which took place between the era of the ,llandeilo and that of the ,ludlow formation1 especially as the enormous pile of ,silurian rocks observed in ,great ,britain 7in ,wales more particularly7 is derived in great part from igneous action1 and is not confined to the ordinary deposition of sediment from rivers or the waste of cliffs4 ,in volcanic archipelagoes1 such as the ,canaries1 we see the most active of all known causes1 aqueous and igneous1 simultaneously at work to produce great results in a comparatively moderate lapse of time4 ,the outpouring of repeated streams of lava--the showering down upon land and sea of volcanic ashes--the sweeping seaward of loose sand and cinders1 or of rocks ground down to pebbles and sand1 by rivers and torrents descending steeply inclined channels--the undermining and eating away of long lines of sea-cliff exposed to the swell of a deep and open ocean--these operations combine to produce a considerable volume of superimposed matter1 without there being time for any extensive change of species4 ,nevertheless1 there would seem to be a limit to the thickness of stony masses formed even under such favourable circumstances1 for the analogy of tertiary volcanic regions lends no countenance to the notion that sedimentary and igneous rocks #be1jjj1 much less #de1jjj feet thick1 like those of ,wales1 could originate while one and the same fauna should continue to people the earth4 ,if1 then1 we allow that about #be1jjj feet of matter may be ascribed to one system1 such as the ,silurian1 as above described1 we may be prepared to discover in the next series of subjacent rocks a distinct assemblage of species1 or even in great part of genera1 of organic remains4 ,such appears to be the fact1 and ,i shall therefore conclude with the ,arenig beds my enumeration of the ,silurian formations in ,great ,britain1 and proceed to say something of their foreign equivalents1 before treating of rocks older than the ,silurian4 ,silurian ,strata of the ,continent of ,europe4--,when we turn to the continent of ,europe1 we discover the same ancient series occupying a wide area1 but in no region as yet has it been observed to attain great thickness4 ,thus1 in ,norway and ,sweden1 the total thickness of strata of ,silurian age is considerably less than #ajjj feet1 although the representatives both of the ,upper and ,lower ,silurian of ,england are not wanting there4 ,in ,russia the ,silurian strata1 so far as they are yet known1 seem to be even of smaller vertical dimensions than in ,scandinavia1 and they appear to consist chiefly of the ,llandovery group1 or of a limestone containing ,pentamerus oblongus1 below which are strata with fossils corresponding to those of the ,llandeilo beds of ,england4 ,the lowest rock with organic remains yet discovered is 0the ,ungulite or ,obolus grit0 of ,st4 ,petersburg1 probably coeval with the ,llandeilo flags of ,wales4 ,the shales and grits near ,st4 ,petersburg1 above alluded to1 contain green grains in their sandy layers1 and are in a singularly unaltered state1 taking into account their high antiquity4 ,the prevailing ,brachiopods consist of the ,obolus ,shells of the lowest known ,fossiliferous ,beds in ,russia4 ,fig4 #efe3 ,siphonotreta unguiculata4 ,fig4 #eff3 ,obolus ,apollinis4 or ,ungulite of ,pander1 and a ,siphonotreta 7,figs4 #efe1 #eff74 ,notwithstanding the antiquity of this ,russian formation1 it should be stated that both of these genera of brachiopods have been also found in the ,upper ,silurian of ,england1 i4e41 in the ,wenlock limestone4 ,among the green grains of the sandy strata above-mentioned1 ,professor ,ehrenberg announced in #ahed his discovery of remains of foraminifera4 ,these are casts of the cells2 and among five or six forms three are considered by him as referable to existing genera 7e4g41 ,textularia1 ,rotalia1 and ,guttulina74 ,silurian ,strata of the ,united ,states4--,the ,silurian formations can be advantageously studied in the ,states of ,new ,york1 ,ohio1 and other regions north and south of the great ,canadian lakes4 ,here they are often found1 as in ,russia1 nearly in horizontal position1 and are more rich in well-preserved fossils than in almost any spot in ,europe4 ,in the ,state of ,new ,york1 where the succession of the beds and their fossils have been most carefully worked out by the ,government surveyors1 the subdivisions given in the first column of the table below have been adopted4 ,subdivisions of the ,silurian ,strata of ,new ,york4 7,strata below the ,oriskany sandstone or base of the ,devonian47 ,new ,york ,names ,british equivalents #a4 ,upper ,pentamerus ,limestone #b4 ,encrinal ,limestone #c4 ,delthyris ,shaly ,limestone #d4 ,pentamerus and ,tentaculite ,limestones #e4 ,water ,lime ,group #f4 ,onondaga ,salt ,group #g4 ,niagara ,group ,upper ,silurian 7or ,ludlow and ,wenlock formations #h4 ,clinton ,group #i4 ,medina ,sandstone #aj4 ,oneida ,conglomerate #aa4 ,gray ,sandstone ,beds of ,passage1 ,llandovery ,group4 #ab4 ,hudson ,river ,group #ac4 ,trenton ,limestone #ad4 ,black-,river ,limestone #ae4 ,bird's-eye ,limestone #af4 ,chazy ,limestone #ag4 ,calciferous ,sandstone ,lower ,silurian 7or ,caradoc and ,bala1 ,llandeilo and ,arenig ,formations74 ,in the second column of the same table ,i have added the supposed ,british equivalents4 ,all ,palontologists1 ,european and ,american1 such as ,,mm4 ,de ,verneuil1 ,d4 ,sharpe1 ,professor ,hall1 ,e4 ,billings1 and others1 who have entered upon this comparison1 admit that there is a marked general correspondence in the succession of fossil forms1 and even species1 as we trace the organic remains downward from the highest to the lowest beds2 but it is impossible to parallel each minor subdivision4 ,that the ,niagara ,limestone1 over which the river of that name is precipitated at the great cataract1 together with its underlying shales1 corresponds to the ,wenlock limestone and shale of ,england there can be no doubt4 ,among the species common to this formation in ,america and ,europe are ,calymene ,blumenbachii1 ,homalonotus delphinocephalus 7,fig4 #edd71 with several other trilobites2 ,rhynchonella ,wilsoni1 ,fig4 #eca1 and ,retzia cuneata2 ,orthis elegantula1 ,pentamerus galeatus1 with many more brachiopods2 ,orthoceras annulatum1 among the cephalopodous shells2 and ,favosites gothlandica1 with other large corals4 ,fig4 #efg3 ,murchisonia gracilis4 ,the ,clinton ,group1 containing ,pentamerus oblongus and ,stricklandinia1 and related more nearly by its fossil species with the beds above than with those below1 is the equivalent of the ,llandovery ,group or beds of passage4 ,the ,hudson ,river ,group1 and the ,trenton ,limestone1 agree palontologically with the ,caradoc or ,bala group1 containing in common with them several species of trilobites1 such as ,asaphus 7,isotelus7 gigas1 ,trinucleus concentricus 7,fig4 #eec72 and various shells1 such as ,orthis striatula1 ,orthis biforata 7or ,o4 lynx71 ,o4 porcata 7,o4 occidentalis of ,hall71 and ,bellerophon bilobatus4 ,in the ,trenton limestone occurs ,murchisonia gracilis1 ,fig4 #efg1 a fossil also common to the ,llandeilo beds in ,england4 ,mr4 ,d4 ,sharpe1 in his report on the mollusca collected by me from these strata in ,north ,america1#f has concluded that the number of species common to the ,silurian rocks on both sides of the ,atlantic is between #cj and #dj per cent2 a result which1 although no doubt liable to future modification1 when a larger comparison shall have been made1 proves1 nevertheless1 that many of the species had a wide geographical range4 ,it seems that comparatively few of the gasteropods and lamellibranchiate bivalves of ,north ,america can be identified specifically with ,european fossils1 while no less than two-fifths of the brachiopoda1 of which my collection chiefly consisted1 are the same4 ,in explanation of these facts1 it is suggested that most of the recent brachiopoda 7especially the orthidiform ones7 are inhabitants of deep water1 and that they may have had a wider geographical range than shells living near shore4 ,the predominance of bivalve mollusca of this peculiar class has caused the ,silurian period to be sometimes styled 0the age of brachiopods40 ,in ,canada1 as in the ,state of ,new ,york1 the ,potsdam ,sandstone underlies the above-mentioned calcareous rocks1 but contains a different suite of fossils1 as will be hereafter explained4 ,in parts of the globe still more remote from ,europe the ,silurian strata have also been recognised1 as in ,south ,america1 ,australia1 and ,india4 ,in all these regions the facies of the fauna1 or the types of organic life1 enable us to recognise the contemporaneous origin of the rocks2 but the fossil species are distinct1 showing that the old notion of a universal diffusion throughout the 0primval seas0 of one uniform specific fauna was quite unfounded1 geographical provinces having evidently existed in the oldest as in the most modern times4 #a ,murchison's ,siluria1 p4 #adj4 #b ,murchison's ,siluria1 chap4 vi4 #c ,e4 ,forbes1 ,mem4 ,geol4 ,surv41 vol4 ii1 p4 #dif4 #d ,quart4 ,geol4 ,journ41 vol4 iv1 p4 #bae1 #ahec4 #e ,trans4 ,brit4 ,assoc41 #ahff4 ,proc4 ,liverpool ,geol4 ,soc41 #ahfi4 #f ,quart4 ,geol4 ,journ41 vol4 iv4 ,,chapter ,,xxvii4 ,,cambrian ,,and ,,laurentian ,,groups4 ,classification of the ,cambrian ,group1 and its ,equivalent in ,bohemia4 -- ,upper ,cambrian ,rocks4 -- ,tremadoc ,slates and their ,fossils4 -- ,lingula ,flags4 -- ,lower ,cambrian ,rocks4 -- ,menevian ,beds4 -- ,longmynd ,group4 -- ,harlech ,grits with large ,trilobites4 -- ,llanberis ,slates4 -- ,cambrian ,rocks of ,bohemia4 -- ,primordial ,zone of ,barrande4 -- ,metamorphosis of ,trilobites4 -- ,cambrian ,rocks of ,sweden and ,norway4 -- ,cambrian ,rocks of the ,united ,states and ,canada4 -- ,potsdam ,sandstone4 -- ,huronian ,series4 -- ,laurentian ,group1 upper and lower4 -- ,eozoon ,canadense1 oldest known ,fossil4 -- ,fundamental ,gneiss of ,scotland4 ,,cambrian ,,group4 ,the characters of the ,upper and ,lower ,silurian rocks were established so fully1 both on stratigraphical and palontological data1 by ,sir ,roderick ,murchison after five years' labour1 in #ahci1 when his 8,silurian ,system0 was published1 that these formations could from that period be recognised and identified in all other parts of ,europe and in ,north ,america1 even in countries where most of the fossils differed specifically from those of the classical region in ,britain1 where they were first studied4 ,while ,sir ,r4 ,i4 ,murchison was exploring in #ahcc1 in ,shropshire and the borders of ,wales1 the strata which in #ahce he first called ,silurian1 ,professor ,sedgwick was surveying the rocks of ,north ,wales1 which both these geologists considered at that period as of older date1 and for which in #ahcf ,sedgwick proposed the name of ,cambrian4 ,it was afterwards found that a large portion of the slaty rocks of ,north ,wales1 which had been considered as more ancient than the ,llandeilo beds and ,stiper-,stones before alluded to1 were1 in reality1 not inferior in position to those ,lower ,silurian beds of ,murchison1 but merely extensive undulations of the same1 bearing fossils identical in species1 though these were generally rarer and less perfectly preserved1 owing to the changes which the rocks had undergone from metamorphic action4 ,to such rocks the term 8,cambrian0 was no longer applicable1 although it continued to be appropriate to strata inferior to the ,stiper-,stones1 and which were older than those of the ,lower ,silurian group as originally defined4 ,it was not till #ahdf that fossils were found in ,wales in the ,lingula flags1 the place of which will be seen in the table below4 ,by this time ,barrande had already published an account of a rich collection of fossils which he had discovered in ,bohemia1 portions of which he recognised as of corresponding age with ,murchison's ,upper and ,lower ,silurian1 while others were more ancient1 to which he gave the name of 8,primordial10 for the fossils were sufficiently distinct to entitle the rocks to be referred to a new period4 ,they consisted chiefly of trilobites of genera distinct from those occurring in the overlying ,silurian formations4 ,these peculiar genera were afterwards found in rocks holding a corresponding position in ,wales1 and ,i shall retain for them the term ,cambrian1 as recent discoveries in our own country seem to carry the first fauna of ,barrande1 or his primordial type1 even into older strata than any which he found to be fossiliferous in ,bohemia4 ,the term primordial was intended to express ,m4 ,barrande's own belief that the fossils of the rocks so-called afforded evidence of the first appearance of vital phenomena on this planet1 and that consequently no fossiliferous strata of older date would or could ever be discovered4 ,the acceptance of such a nomenclature would seem to imply that we despaired of extending our discoveries of new and more ancient fossil groups at some future day when vast portions of the globe1 hitherto unexplored1 should have been thoroughly surveyed4 ,already the discovery of the ,laurentian ,eozoon in ,canada1 presently to be mentioned1 discountenances such views4 ,the following table will show the succession of the strata in ,england and ,wales which belong to the ,cambrian group or the fossiliferous rocks older than the ,arenig or ,lower ,llandeilo rocks3 ,,upper ,,cambrian ,,tremadoc ,,slates 7,primordial of ,barrande in part7 ,,lingula ,,flags 7,primordial of ,barrande7 ,,lower ,,cambrian ,,menevian ,,beds 7,primordial of ,barrande7 ,,longmynd ,,group a4 ,harlech ,grits b4 ,llanberis ,slates ,tremadoc ,slates4--,the ,tremadoc slates of ,sedgwick are more than #ajjj feet in thickness1 and consist of dark earthy slates occurring near the little town of ,tremadoc1 situated on the north side of ,cardigan ,bay1 in ,carnarvonshire4 ,these slates were first examined by ,sedgwick in #ahca1 and were re-examined by him and described in #ahdf1a after some fossils had been found in the underlying ,lingula flags by ,mr4 ,davis4 ,the inferiority in position of these ,lingula flags to the ,tremadoc beds was at the same time established4 ,the overlying ,tremadoc beds were traced by their pisolitic ore from ,tremadoc to ,dolgelly4 ,no fossils proper to the ,tremadoc slates were then observed1 but subsequently1 thirty-six species of all classes have been found in them1 thanks to the researches of ,messrs4 ,salter1 ,homfray1 and ,ash4 ,we have already seen that in the ,arenig or ,stiper-,stones group1 where the species are distinct1 the genera agree with ,silurian types2 but in these ,tremadoc slates1 where the species are also peculiar1 there is about an equal admixture of ,silurian types with those which ,barrande has termed 8primordial40 ,here1 therefore1 it may truly be said that we are entering upon a new domain of life in our retrospective survey of the past4 ,the trilobites of new species1 but of ,lower ,silurian genera1 belong to ,ogygia1 ,asaphus1 and ,cheirurus2 whereas those belonging to primordial types1 or ,barrande's first fauna as well as to the ,lingula flags of ,wales1 comprise ,dikelocephalus1 ,conocoryphe 7for genera see ,fig4 #egg and #eha71b ,olenus1 and ,angelina4 ,fig4 #efh3 ,theca 7,cleidotheca operculata4 ,in the ,tremadoc slates are found ,bellerophon1 ,orthoceras1 and ,cyrtoceras1 all specifically distinct from ,lower ,silurian fossils of the same genera3 the ,pteropods ,theca 7,fig4 #efh7 and ,conularia range throughout these slates2 there are no ,graptolites4 ,the ,lingula 7,lingulella7 ,davisii ranges from the top to the bottom of the formation1 and links it with the zone next to be described4 ,the ,tremadoc slates are very local1 and seem to be confined to a small part of ,north ,wales2 and ,professor ,ramsay supposes them to lie unconformably on the ,lingula flags1 and that a long interval of time elapsed between these formations4 ,cephalopoda have not yet been found lower than this group1 but it will be observed that they occur here associated with genera of ,trilobites considered by ,barrande as characteristically ,primordial1 some of which belong to all the divisions of the ,british ,cambrian about to be mentioned4 ,this renders the absence of cephalopoda of less importance as bearing on the theory of development4 ,lingula ,flags4--,next below the ,tremadoc slates in ,north ,wales lie micaceous flagstones and slates1 in which1 in #ahdf1 ,mr4 ,e4 ,davis discovered the ,lingula 7,lingulella71 ,fig4 #egj1 named after him1 and from which was derived the name of ,lingula flags4 ,these beds1 which are palontologically the equivalents of ,barrande's primordial zone1 are represented by more than #ejjj feet of strata1 and have been studied chiefly in the neighbourhood of ,dolgelly1 ,ffestiniog1 and ,portmadoc in ,north ,wales1 and at ,st4 ,david's in ,south ,wales4 ,they have yielded about forty species of fossils1 of which six only are common to the overlying ,tremadoc rocks1 but the two formations are closely allied by having several characteristic 8primordial0 genera in common4 ,dikelocephalus1 ,olenus 7,fig4 #ega71 and ,conocoryphe are prominent forms1 as is also ,hymenocaris 7,fig4 #efi71 a genus of phyllopod crustacean entirely confined to the ,lingula ,flags4 ,according to ,mr4 ,belt1 who has devoted much attention to these beds1 there are already palontological data for subdividing the ,lingula ,flags into three sections4#c 8,lingula ,flags0 of ,dolgelly1 and ,ffestiniog2 ,n4 ,wales4 ,in ,merionethshire1 according to ,professor ,ramsay1 the ,lingula ,flags attain their greatest development2 in ,carnarvonshire they thin out so as to have lost two-thirds of their thickness in eleven miles1 while in ,anglesea and on the ,menai ,straits both they and the ,tremadoc beds are entirely absent1 and the ,lower ,silurian rests directly on ,lower ,cambrian strata4 ,,lower ,,cambrian4 ,menevian ,beds4--,immediately beneath the ,lingula ,flags there occurs a series of dark grey and black flags and slates alternating at the upper part with some beds of sandstone1 the whole reaching a thickness of from #ejj to #fjj feet4 ,these beds were formerly classed1 on purely lithological grounds1 as the base of the ,lingula ,flags1 but ,messrs4 ,hicks and ,salter1 to whose exertions we owe almost all our knowledge of the fossils1 have pointed out#d that the most characteristic genera found in them are quite unknown in the ,lingula ,flags1 while they possess many of the strictly ,lower ,cambrian genera1 such as ,microdiscus and ,paradoxides4 ,they therefore proposed to place them1 and it seems to me with good reason1 at the top of the ,lower ,cambrian under the term 8,menevian10 ,menevia being the classical name of ,st4 ,david's4 ,the beds are well exhibited in the neighbourhood of ,st4 ,david's in ,south ,wales1 and near ,dolgelly and ,maentwrog in ,north ,wales4 ,they are the equivalents of the lowest part of ,barrande's ,primordial ,zone 7tage ,c74 ,more than forty species have been found in them1 and the group is altogether very rich in fossils for so early a period4 ,fig4 #egb3 ,paradoxides ,davidis4 ,the trilobites are of large size2 ,paradoxides ,davidis 7see ,fig4 #egb71 the largest trilobite known in ,england1 #bb inches or nearly two feet long1 is peculiar to the ,menevian ,beds4 ,by referring to the ,bohemian trilobite of the same genus 7,fig4 #egf71 the reader will at once see how these fossils 7though of such different dimensions7 resemble each other in ,bohemia and ,wales1 and other closely allied species from the two regions might be added1 besides some which are common to both countries4 ,the ,swedish fauna1 presently to be mentioned1 will be found to be still more nearly connected with the ,welsh ,menevian4 ,in all these countries there is an equally marked difference between the ,cambrian fossils and those of the ,upper and ,lower ,silurian rocks4 ,the trilobite with the largest number of rings1 ,erinnys venulosa1 occurs here in conjunction with ,agnostus and ,microdiscus1 the genera with the smallest number4 ,blind trilobites are also found as well as those which have the largest eyes1 such as ,microdiscus on the one hand1 and ,anoplenus on the other4 ,,longmynd ,,group4 ,older than the ,menevian ,beds are a thick series of olive green1 purple1 red and grey grits and conglomerates found in ,north and ,south ,wales1 ,shropshire1 and parts of ,ireland and ,scotland4 ,they have been called by ,professor ,sedgwick the ,longmynd or ,bangor ,group1 comprising1 first1 the ,harlech and ,barmouth sandstones2 and secondly1 the ,llanberis slates4 ,fig4 #egc3 ,histioderma ,hibernica4 ,harlech ,grits4--,the sandstones of this period attain in the ,longmynd hills a thickness of no less than #fjjj feet without any interposition of volcanic matter2 in some places in ,merionethshire they are still thicker4 ,until recently these rocks possessed but a very scanty fauna4 ,with the exception of five species of annelids 7see ,fig4 #dfj7 brought to light by ,mr4 ,salter in ,shropshire1 and ,dr4 ,kinahan in ,wicklow1 and an obscure crustacean form1 ,palopyge ,ramsayi1 they were supposed to be barren of organic remains4 ,now1 however1 through the labours of ,mr4 ,hicks1#e they have yielded at ,st4 ,david's a rich fauna of trilobites1 brachiopods1 phyllopods1 and pteropods1 showing1 together with other fossils1 a by no means low state of organisation at this early period4 ,already the fauna amounts to #bj species referred to #ag genera4 ,a new genus of trilobite called ,plutonia ,sedgwickii1 not yet figured and described1 has been met with in the ,harlech grits4 ,it is comparable in size to the large ,paradoxides ,davidis before mentioned1 has well-developed eyes1 and is covered all over with tubercles4 ,in the same strata occur other genera of trilobites1 namely1 ,conocoryphe1 ,paradoxides1 ,microdiscus1 and the ,pteropod ,theca 7,fig4 #efh71 all represented by species peculiar to the ,harlech grits4 ,the sands of this formation are often rippled1 and were evidently left dry at low tides1 so that the surface was dried by the sun and made to shrink and present sun-cracks4 ,there are also distinct impressions of rain-drops on many surfaces1 like those in ,fig4 #ddd and #dde4 ,lanberis ,slates4--,the slates of ,llanberis and ,penrhyn in ,carnarvonshire1 with their associated sandy strata1 attain a great thickness1 sometimes about #cjjj feet4 ,they are perhaps not more ancient than the ,harlech and ,barmouth beds last mentioned1 for they may represent the deposits of fine mud thrown down in the same sea1 on the borders of which the sands above-mentioned were accumulating4 ,in some of these slaty rocks in ,ireland1 immediately opposite ,anglesea and ,carnarvon1 two species of fossils have been found1 to which the late ,professor ,e4 ,forbes gave the name of ,oldhamia4 ,the nature of these organisms is still a matter of discussion among naturalists4 ,fig4 #egd3 ,oldhamia radiata4 ,fig4 #ege3 ,oldhamia antiqua4 ,cambrian ,rocks of ,bohemia 7,primordial zone of ,barrande74--,in the year #ahdf1 as before stated1 ,m4 ,joachim ,barrande1 after ten years' exploration of ,bohemia1 and after collecting more than a thousand species of fossils1 had ascertained the existence in that country of three distinct faunas below the ,devonian4 ,to his first fauna1 which was older than any then known in this country1 he gave the name of tage ,c2 his two first stages ,a and ,b consisting of crystalline and metamorphic rocks and unfossiliferous schists4 ,this tage ,c or primordial zone proved afterwards to be the equivalent of those subdivisions of the ,cambrian groups which have been above described under the names of ,menevian and ,lingula ,flags4 ,the second fauna tallies with ,murchison's ,lower ,silurian1 as originally defined by him when no fossils had been discovered below the ,stiper-,stones4 ,the third fauna agrees with the ,upper ,silurian of the same author4 ,barrande1 without government assistance1 had undertaken single-handed the geological survey of ,bohemia1 the fossils previously obtained from that country having scarcely exceeded #bj in number1 whereas he had already acquired1 in #ahej1 no less than #aajj species1 namely1 #bej crustaceans 7chiefly ,trilobites71 #bej ,cephalopods1 #afj gasteropods and pteropods1 #acj acephalous mollusks1 #baj brachiopods1 and #aaj corals and other fossils4 ,these numbers have since been almost doubled by subsequent investigations in the same country4 ,in the primordial zone ,c1 he discovered trilobites of the genera ,paradoxides1 ,conocoryphe1 ,ellipsocephalus1 ,sao1 ,arionellus1 ,hydrocephalus1 and ,agnostus4 ,m4 ,barrande pointed out that these primordial trilobites have a peculiar facies of their own dependent on the multiplication of their thoracic segments and the diminution of their caudal shield or pygidium4 ,fossils of the lowest ,fossiliferous ,beds in ,bohemia1 or 8,primordial ,zone0 of ,barrande4 ,fig4 #egf3 ,paradoxides ,bohemicus4 ,fig4 #egg3 ,conocoryphe striata4 ,fig4 #egh3 ,agnostus integer4 ,fig4 #egi3 ,agnostus ,rex4 ,fig4 #ehj3 ,sao hirsuta in its various stages of growth4 ,one of the 8primordial0 or ,upper ,cambrian ,trilobites of the genus ,sao1 a form not found as yet elsewhere in the world1 afforded ,m4 ,barrande a fine illustration of the metamorphosis of these creatures1 for he traced them through no less than twenty stages of their development4 ,a few of these changes have been selected for representation in ,figure #ehj1 that the reader may learn the gradual manner in which different segments of the body and the eyes make their appearance4 ,in ,bohemia the primordial fauna of ,barrande derived its importance exclusively from its numerous and peculiar trilobites4 ,besides these1 however1 the same ancient schists have yielded two genera of brachiopods1 ,orthis and ,orbicula1 a ,pteropod of the genus ,theca1 and four echinoderms of the cystidean family4 ,cambrian of ,sweden and ,norway4--,the ,cambrian beds of ,wales are represented in ,sweden by strata the fossils of which have been described by a most able naturalist1 ,m4 ,angelin1 in his 8,palontologica ,suecica0 7#aheb-d74 ,the 8alum-schists10 as they are called in ,sweden1 are horizontal argillaceous rocks which underlie conformably certain ,lower ,silurian strata in the mountain called ,kinnekulle1 south of the great ,wener ,lake in ,sweden4 ,these schists contain trilobites belonging to the genera ,paradoxides1 ,olenus1 ,agnostus1 and others1 some of which present rudimentary forms1 like the genus last mentioned1 without eyes1 and with the body segments scarcely developed1 and others1 again1 have the number of segments excessively multiplied1 as in ,paradoxides4 ,such peculiarities agree with the characters of the crustaceans met with in the ,cambrian strata of ,wales2 and ,dr4 ,torell has recently found in ,sweden the ,paradoxides ,hicksii1 a well-known ,lower ,cambrian fossil4 ,at the base of the ,cambrian strata in ,sweden1 which in the neighbourhood of ,lake ,wener are perfectly horizontal1 lie ripple-marked quartzose sandstones with worm-tracks and annelid borings1 like some of those found in the ,harlech grits of the ,longmynd4 ,among these are some which have been referred doubtfully to plants4 ,these sandstones have been called in ,sweden 8fucoid sandstones40 ,the whole thickness of the ,cambrian rocks of ,sweden does not exceed #cjj feet from the equivalents of the ,tremadoc beds to these sandstones1 which last seem to correspond with the ,longmynd1 and are regarded by ,torell as older than any fossiliferous primordial rocks in ,bohemia4 ,cambrian of the ,united ,states and ,canada 7,potsdam ,sandstone74--,this formation1 as we learn from ,sir ,w4 ,logan1 is #gjj feet thick in ,canada2 the upper part consists of sandstone containing fucoids1 and perforated by small vertical holes1 which are very characteristic of the rock1 and appear to have been made by annelids 7,scolithus linearis74 ,the lower portion is a conglomerate with quartz pebbles4 ,i have seen the ,potsdam sandstone on the banks of the ,st4 ,lawrence1 and on the borders of ,lake ,champlain1 where1 as at ,keesville1 it is a white quartzose fine-grained grit1 almost passing into quartzite4 ,it is divided into horizontal ripple-marked beds1 very like those of the ,lingula ,flags of ,britain1 and replete with a small round-shaped ,obolella1 in such numbers as to divide the rock into parallel planes1 in the same manner as do the scales of mica in some micaceous sandstones4 ,among the shells of this formation in ,wisconsin are species of ,lingula and ,orthis1 and several trilobites of the primordial genus ,dikelocephalus 7,fig4 #eha74 ,on the banks of the ,st4 ,lawrence1 near ,beauharnois and elsewhere1 many fossil footprints have been observed on the surface of the rippled layers4 ,they are supposed by ,professor ,owen to be the trails of more than one species of articulate animal1 probably allied to the ,king ,crab1 or ,limulus4 ,fig4 #eha3 ,dikelocephalus ,minnesotensis4 ,recent investigations by the naturalists of the ,canadian survey have rendered it certain that below the level of the ,potsdam ,sandstone there are slates and schists extending from ,new ,york to ,newfoundland1 occupied by a series of trilobitic forms similar in genera1 though not in species1 to those found in the ,european ,upper ,cambrian strata4 ,huronian ,series4--,next below the ,upper ,cambrian occur strata called the ,huronian by ,sir ,w4 ,logan1 which are of vast thickness1 consisting chiefly of quartzite1 with great masses of greenish chloritic slate1 which sometimes include pebbles of crystalline rocks derived from the ,laurentian formation1 next to be described4 ,limestones are rare in this series1 but one band of #cjj feet in thickness has been traced for considerable distances to the north of ,lake ,huron4 ,beds of greenstone are intercalated conformably with the quartzose and argillaceous members of this series4 ,no organic remains have yet been found in any of the beds1 which are about #ah1jjj feet thick1 and rest unconformably on the ,laurentian rocks4 ,,laurentian ,,group4 ,in the course of the geological survey carried on under the direction of ,sir ,w4,e4 ,logan1 it has been shown that1 northward of the river ,st4 ,lawrence1 there is a vast series of crystalline rocks of gneiss1 mica-schist1 quartzite1 and limestone1 more than #cj1jjj feet in thickness1 which have been called ,laurentian1 and which are already known to occupy an area of about #bjj1jjj square miles4 ,they are not only more ancient than the fossiliferous ,cambrian formations above described1 but are older than the ,huronian last mentioned1 and had undergone great disturbing movements before the ,potsdam sandstone and the other 8primordial0 or ,cambrian rocks were formed4 ,the older half of this ,laurentian series is unconformable to the newer portion of the same4 ,upper ,laurentian or ,labrador ,series4--,the ,upper ,group1 more than #aj1jjj feet thick1 consists of stratified crystalline rocks in which no organic remains have yet been found4 ,they consist in great part of feldspars1 which vary in composition from anorthite to andesine1 or from those kinds in which there is less than one per cent of potash and soda to those in which there is more than seven per cent of these alkalies1 the soda preponderating greatly4 ,these feldsparites sometimes form mountain masses almost without any admixture of other minerals2 but at other times they include augite1 which passes into hypersthene4 ,they are often granitoid in structure4 ,one of the varieties is the same as the apolescent labradorite rock of ,labrador4 ,the ,adirondack ,mountains in the ,state of ,new ,york are referred to the same series1 and it is conjectured that the hypersthene rocks of ,skye1 which resemble this formation in mineral character1 may be of the same geological age4 ,lower ,laurentian4--,this series1 about #bj1jjj feet in thickness1 is1 as before stated1 unconformable to that last mentioned2 it consists in great part of gneiss of a reddish tint with orthoclase feldspar4 ,beds of nearly pure quartz1 from #djj to #fjj feet thick1 occur in some places4 ,hornblendic and micaceous schists are often interstratified1 and beds of limestone1 usually crystalline4 ,beds of plumbago also occur4 ,that this pure carbon may have been of organic origin before metamorphism has naturally been conjectured4 ,there are several of these limestones which have been traced to great distances1 and one of them is from #gjj to #aejj feet thick4 ,in the most massive of them ,sir ,w4 ,logan observed1 in #ahei1 what he considered to be an organic body much resembling the ,silurian fossil called ,stromatopora rugosa4 ,it had been obtained the year before by ,mr4 ,j4 ,mac,mullen at the ,grand ,calumet1 on the river ,ottawa4 ,this fossil was examined in #ahfd by ,dr4 ,dawson of ,montreal1 who detected in it1 by aid of the microscope1 the distinct structure of a ,rhizopod or ,foraminifer4 ,dr4 ,carpenter and ,professor ,t4 ,rupert ,jones have since confirmed this opinion1 comparing the structure to that of the well-known nummulite4 ,it appears to have grown one layer over another1 and to have formed reefs of limestone as do the living coral-building polyp animals4 ,parts of the original skeleton1 consisting of carbonate of lime1 are still preserved2 while certain inter-spaces in the calcareous fossil have been filled up with serpentine and white augite4 ,on this oldest of known organic remains ,dr4 ,dawson has conferred the name of ,eozoon ,canadense 7see ,figs4 #ehb1 #ehc72 its antiquity is such that the distance of time which separated it from the ,upper ,cambrian period1 or that of the ,potsdam sandstone1 may1 says ,sir ,w4 ,logan1 be equal to the time which elapsed between the ,potsdam sandstone and the nummulitic limestones of the ,tertiary period4 ,the ,laurentian and ,huronian rocks united are about #ej1jjj feet in thickness1 and the ,lower ,laurentian was disturbed before the newer series was deposited4 ,we may naturally expect the other proofs of unconformability will hereafter be detected at more than one point in so vast a succession of strata4 ,fig4 #ehb and #ehc3 ,eozoon ,canadense4 ,fig4 #ehb4 a4 ,chambers of lower tier communicating at 1 and separated from adjoining chambers at ,o by an intervening septum1 traversed by passages4 b4 ,chambers of an upper tier4 c4 ,walls of the chambers traversed by fine tubules4 7,these tubules pass with uniform parallelism from the inner to the outer surface1 opening at regular distances from each other47 d4 ,intermediate skeleton1 composed of homogeneous shell substance1 traversed by f4 ,stoloniferous passages connecting the chambers of the two tiers4 e4 ,canal system in intermediate skeleton1 showing the arborescent saceodic prolongations4 7,fig4 #ehc shows these bodies in a decalcified state47 f4 ,stoloniferous passages4 ,fig4 #ehc4 ,decalcified portion of natural rock1 showing canal system and the several layers2 the acuteness of the planes prevents more than one or two parallel tiers being observed4 ,the mineral character of the ,upper ,laurentian differs1 as we have seen1 from that of the ,lower1 and the pebbles of gneiss in the ,huronian conglomerates are thought to prove that the ,laurentian strata were already in a metamorphic state before they were broken up to supply materials for the ,huronian4 ,even if we had not discovered the ,eozoon1 we might fairly have inferred from analogy that as the quartzites were once beds of sand1 and the gneiss and mica-schist derived from shales and argillaceous sandstones1 so the calcareous masses1 from #djj to #ajjj feet and more in thickness1 were originally of organic origin4 ,this is now generally believed to have been the case with the ,silurian1 ,devonian1 ,carboniferous1 ,oolitic1 and ,cretaceous limestones and those nummulitic rocks of tertiary date which bear the closest affinity to the ,eozoon reefs of the ,lower ,laurentian4 ,the oldest stratified rock in ,scotland is that called by ,sir ,r4 ,murchison 8the fundamental gneiss10 which is found in the north-west of ,ross-shire1 and in ,sutherlandshire 7see ,fig4 #hb71 and forms the whole of the adjoining island of ,lewis1 in the ,hebrides4 ,it has a strike from north-west to south-east1 nearly at right angles to the metamorphic strata of the ,grampians4 ,on this ,laurentian gneiss1 in parts of the western ,highlands1 the ,lower ,cambrian and various metamorphic rocks rest unconformably4 ,it seems highly probable that this ancient gneiss of ,scotland may correspond in date with part of the great ,laurentian group of ,north ,america4 #a ,quart4 ,geol4 ,journ41 vol4 iii1 p4 #aef4 #b ,this genus has been substituted for ,barrande's ,conocephalus1 as the latter term had been preoccupied by the entomologists4 #c ,geol4 ,mag41 vol iv4 #d ,british ,association ,report #ahfe1 #ahff1 #ahfh and ,quart4 ,geol4 ,journ41 vols4 xxi1 xxv4 #e ,brit4 ,assoc4 ,report1 #ahfh4 ,,chapter ,,xxviii4 ,,volcanic ,,rocks4 ,external ,form1 ,structure1 and ,origin of ,volcanic ,mountains4 -- ,cones and ,craters4 -- ,hypothesis of 8,elevation ,craters0 considered4 -- ,trap ,rocks4 -- ,name whence derived4 -- ,minerals most abundant in ,volcanic ,rocks4 -- ,table of the ,analysis of ,minerals in the ,volcanic and ,hypogene ,rocks4 -- ,similar ,minerals in ,meteorites4 -- ,theory of ,isomorphism4 -- ,basaltic ,rocks4 -- ,trachytic ,rocks4 -- ,special ,forms of ,structure4 -- ,the columnar and globular ,forms4 -- ,trap ,dikes and ,veins4 -- ,alteration of ,rocks by volcanic ,dikes4 -- ,conversion of ,chalk into ,marble4 -- ,intrusion of ,trap between ,strata4 -- ,relation of trappean ,rocks to the ,products of active ,volcanoes4 ,the aqueous or fossiliferous rocks having now been described1 we have next to examine those which may be called volcanic1 in the most extended sense of that term4 ,in the diagram 7,fig4 #ehd7 suppose a1 a to represent the crystalline formations1 such as the granitic and metamorphic2 b1 b the fossiliferous strata2 and c1 c the volcanic rocks4 ,these last are sometimes found1 as was explained in the first chapter1 breaking through a and b1 sometimes overlying both1 and occasionally alternating with the strata b1 b4 ,fig4 #ehd3 a4 ,hypogene formations1 stratified and unstratified4 b4 ,aqueous formations4 c4 ,volcanic rocks4 ,external ,form1 ,structure1 and ,origin of ,volcanic ,mountains4--,the origin of volcanic cones with crater-shaped summits has been explained in the 8,principles of ,geology0 7,chapters #bc to #bg71 where ,vesuvius1 ,etna1 ,santorin1 and ,barren ,island are described4 ,the more ancient portions of those mountains or islands1 formed long before the times of history1 exhibit the same external features and internal structure which belong to most of the extinct volcanoes of still higher antiquity2 and these last have evidently been due to a complicated series of operations1 varied in kind according to circumstances2 as1 for example1 whether the accumulation took place above or below the level of the sea1 whether the lava issued from one or several contiguous vents1 and1 lastly1 whether the rocks reduced to fusion in the subterranean regions happened to have contained more or less silica1 potash1 soda1 lime1 iron1 and other ingredients4 ,we are best acquainted with the effects of eruptions above water1 or those called subrial or supramarine2 yet the products even of these are arranged in so many ways that their interpretation has given rise to a variety of contradictory opinions1 some of which will have to be considered in this chapter4 ,fig4 #ehe3 ,part of the chain of extinct volcanoes called the ,monts ,dome1 ,aurvergne4 ,cones and ,craters4--,in regions where the eruption of volcanic matter has taken place in the open air1 and where the surface has never since been subjected to great aqueous denudation1 cones and craters constitute the most striking peculiarity of this class of formations4 ,many hundreds of these cones are seen in central ,france1 in the ancient provinces of ,auvergne1 ,velay1 and ,vivarais1 where they observe1 for the most part1 a linear arrangement1 and form chains of hills4 ,although none of the eruptions have happened within the historical era1 the streams of lava may still be traced distinctly descending from many of the craters1 and following the lowest levels of the existing valleys4 ,the origin of the cone and crater-shaped hill is well understood1 the growth of many having been watched during volcanic eruptions4 ,a chasm or fissure first opens in the earth1 from which great volumes of steam are evolved4 ,the explosions are so violent as to hurl up into the air fragments of broken stone1 parts of which are shivered into minute atoms4 ,at the same time melted stone or lava usually ascends through the chimney or vent by which the gases make their escape4 ,although extremely heavy1 this lava is forced up by the expansive power of entangled gaseous fluids1 chiefly steam or aqueous vapour1 exactly in the same manner as water is made to boil over the edge of a vessel when steam has been generated at the bottom by heat4 ,large quantities of the lava are also shot up into the air1 where it separates into fragments1 and acquires a spongy texture by the sudden enlargement of the included gases1 and thus forms scori1 other portions being reduced to an impalpable powder or dust4 ,the showering down of the various ejected materials round the orifice of eruption gives rise to a conical mound1 in which the successive envelopes of sand and scori form layers1 dipping on all sides from a central axis4 ,in the mean time a hollow1 called a crater1 has been kept open in the middle of the mound by the continued passage upward of steam and other gaseous fluids4 ,the lava sometimes flows over the edge of the crater1 and thus thickens and strengthens the sides of the cone2 but sometimes it breaks down the cone on one side 7see ,fig4 #ehe71 and often it flows out from a fissure at the base of the hill1 or at some distance from its base4 ,some geologists had erroneously supposed1 from observations made on recent cones of eruption1 that lava which consolidates on steep slopes is always of a scoriaceous or vesicular structure1 and never of that compact texture which we find in those rocks which are usually termed 8trappean40 ,misled by this theory1 they have gone so far as to believe that if melted matter has originally descended a slope at an angle exceeding four or five degrees1 it never1 on cooling1 acquires a stony compact texture4 ,consequently1 whenever they found in a volcanic mountain sheets of stony materials inclined at angles of from #e to #bj or even more than #cj1 they thought themselves warranted in assuming that such rocks had been originally horizontal1 or very slightly inclined1 and had acquired their high inclination by subsequent upheaval4 ,to such dome-shaped mountains with a cavity in the middle1 and with the inclined beds having what was called a ququversal dip or a slope outward on all sides1 they gave the name of 8,elevation craters40 ,as the late ,leopold ,von ,buch1 the author of this theory1 had selected the ,isle of ,palma1 one of the ,canaries1 as a typical illustration of this form of volcanic mountain1 ,i visited that island in #ahed1 in company with my friend ,mr4 ,hartung1 and ,i satisfied myself that it owes its origin to a series of eruptions of the same nature as those which formed the minor cones1 already alluded to4 ,in some of the more ancient or ,miocene volcanic mountains1 such as ,mont ,dor and ,cantal in central ,france1 the mode of origin by upheaval as above described is attributed to those dome-shaped masses1 whether they possess or not a great central cavity1 as in ,palma4 ,where this cavity is present1 it has probably been due to one or more great explosions similar to that which destroyed a great part of ancient ,vesuvius in the time of ,pliny4 ,similar paroxysmal catastrophes have caused in historical times the truncation on a grand scale of some large cones in ,java and elsewhere4#a ,among the objections which may be considered as fatal to ,von ,buch's doctrine of upheaval in these cases1 ,i may state that a series of volcanic formations extending over an area six or seven miles in its shortest diameter1 as in ,palma1 could not be accumulated in the form of lavas1 tuffs1 and volcanic breccias or agglomerates without producing a mountain as lofty as that which they now constitute4 ,but assuming that they were first horizontal1 and then lifted up by a force acting most powerfully in the centre and tilting the beds on all sides1 a central crater having been formed by explosion or by a chasm opening in the middle1 where the continuity of the rocks was interrupted1 we should have a right to expect that the chief ravines or valleys would open towards the central cavity1 instead of which the rim of the great crater in ,palma and other similar ancient volcanoes is entire for more than three parts of the whole circumference4 ,if dikes are seen in the precipices surrounding such craters or central cavities1 they certainly imply rents which were filled up with liquid matter4 ,but none of the dislocations producing such rents can have belonged to the supposed period of terminal and paroxysmal upheaval1 for had a great central crater been already formed before they originated1 or at the time when they took place1 the melted matter1 instead of filling the narrow vents1 would have flowed down into the bottom of the cavity1 and would have obliterated it to a certain extent4 ,making due allowance for the quantity of matter removed by subarial denudation in volcanic mountains of high antiquity1 and for the grand explosions which are known to have caused truncation in active volcanoes1 there is no reason for calling in the violent hypothesis of elevation craters to explain the structure of such mountains as ,teneriffe1 the ,grand ,canary1 ,palma1 or those of central ,france1 ,etna1 or ,vesuvius1 all of which ,i have examined4 ,with regard to ,etna1 ,i have shown1 from observations made by me in #aheg1 that modern lavas1 several of them of known date1 have formed continuous beds of compact stone even on slopes of #ae1 #cf1 and #ch degrees1 and1 in the case of the lava of #aheb1 more than #dj degrees4 ,the thickness of these tabular layers varies from #a foot to #bf feet4 ,and their planes of stratification are parallel to those of the overlying and underlying scori which form part of the same currents4#b ,nomenclature of ,trappean ,rocks4--,when geologists first began to examine attentively the structure of the northern and western parts of ,europe1 they were almost entirely ignorant of the phenomena of existing volcanoes4 ,they found certain rocks1 for the most part without stratification1 and of a peculiar mineral composition1 to which they gave different names1 such as basalt1 greenstone1 porphyry1 trap tuff1 and amygdaloid4 ,all these1 which were recognised as belonging to one family1 were called 8trap0 by ,bergmann1 from trappa1 ,swedish for a flight of steps--a name since adopted very generally into the nomenclature of the science2 for it was observed that many rocks of this class occurred in great tabular masses of unequal extent1 so as to form a succession of terraces or steps4 ,it was also felt that some general term was indispensable1 because these rocks1 although very diversified in form and composition1 evidently belonged to one group1 distinguishable from the ,plutonic as well as from the non-volcanic fossiliferous rocks4 ,by degrees familiarity with the products of active volcanoes convinced geologists more and more that they were identical with the trappean rocks4 ,in every stream of modern lava there is some variation in character and composition1 and even where no important difference can be recognised in the proportions of silica1 alumina1 lime1 potash1 iron1 and other elementary materials1 the resulting materials are often not the same1 for reasons which we are as yet unable to explain4 ,the difference also of the lavas poured out from the same mountain at two distinct periods1 especially in the quantity of silica which they contain1 is often so great as to give rise to rocks which are regarded as forming distinct families1 although there may be every intermediate gradation between the two extremes1 and although some rocks1 forming a transition from the one class to the other1 may often be so abundant as to demand special names4 ,these species might be multiplied indefinitely1 and ,i can only afford space to name a few of the principal ones1 about the composition and aspect of which there is the least discordance of opinion4 ,minerals most abundant in ,volcanic ,rocks4--,the minerals which form the chief constituents of these igneous rocks are few in number4 ,next to quartz1 which is nearly pure silica or silicic acid1 the most important are those silicates commonly classed under the several heads of feldspar1 mica1 hornblende or augite1 and olivine4 ,in ,table #bh4a1 in drawing up which ,i have received the able assistance of ,mr4 ,david ,forbes1 the chemical analysis of these minerals and their varieties is shown1 and he has added the specific gravity of the different mineral species1 the geological application of which in determining the rocks formed by these minerals will be explained in the sequel 7p4#ejd74 ,analysis of ,minerals most abundant in the ,volcanic and ,hypogene ,rocks4 ,,the ,,quartz ,,group ,,quartz #ajjj #bf ,silica ,specific gravity ,,tridymite #ajjj #bc ,silica ,specific gravity ,,the ,,feldspar ,,group ,,orthoclase4 ---- ,carisbad1 in granite 7bulk7 #febc #afbf #jbg nil trace nil #adff #ade nil #bee ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ---- ,sanadine1 ,drachenfels in trachyte 7,rammelsberg7 #fehg #ahec nil nil #jie #jcj #ajcb #cdi ,w4 #jdd #bee ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,albite4 ---- ,arendal1 in granite 7,g4 ,rose7 #fhdf #aicj nil #jbh #jfh nil nil #aabg nil #bfa ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,oligoclase4 ---- ,ytterby1 in granite 7,berzelius7 #faee #bchj nil nil #cah #jhj #jch #ifg nil #bfe ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ---- ,teneriffe1 in trachyte 7,deville7 #faee #bbjc nil nil #bha #jdg #cdd #ggd nil #bei ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,labradorite4 ---- ,hitteroe1 in ,labrador-rock 7,waage7 #eaci #bidb #bij nil #idd #jcg #aaj #ejc ,w4 #jga #bgb ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ---- ,iceland1 in volcanic 7,damour7 #ebag #bibb #aij nil #acaa nil nil #cdj nil #bga ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,anorthite4 ---- ,harzburg1 in diorite 7,streng7 #decg #cdha #jei nil #afeb #jhc #jdj #ade ,w4 #jhg #bgd ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ---- ,hecla1 in volcanic 7,waltershausen7 #dead #cbaj #bjc #jgh #ahcb nil #jbb #ajf nil #bgd ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,leucite4 ---- ,vesuvius1 #ahaa1 in lava 7,rammelsberg7 #efaj #bcbb nil nil nil nil #bjei #jeg nil #bdh ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,nepheline4 ---- ,miask1 in ,miascite 7,scheerer7 #ddcj #ccbe #jhb nil #jcb #jjg #ehb #afjb nil #bei ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ---- ,vesuvius1 in volcanic 7,arfvedson7 #ddaa #ccgc nil nil nil nil nil #bjdf ,w4 #jfb #bfj ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,the ,,mica ,,group ,,muscovite4 ---- ,finland1 in grante 7,rose7 #dfcf #cfhj #dec nil nil nil #ibb nil ,f4 #jfg ,w4 #ahd #bij ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,lepidolite4 ---- ,cornwall1 in granite 7,regnault7 #ebdj #bfhj nil #aej nil nil #iad nil ,f4 #dah ,li4 #dhe #bij ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,biotite4 ---- ,bodennais 7,v4 ,kobel #djhf #aeac #acjj nil nil #bbjj #hhc nil ,w4 #jdd #bgj ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ---- ,vesuvius1 in volcanic 7,chodnef7 #djia #agga #aajb nil #jcj #aijd #iif nil nil #bge ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,phlogopite4 ---- ,new ,york1 in metamorphic limestone 7,rammelsberg7 #daif #acdg nil #bfg #jcd #bgab #icg nil ,f4 #bic ,w4 #jfj #bha ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,margarite4 ---- ,nexos 7,smith7 #cjjb #dieb #afe nil #ajhb #jdh #abe ,w4 #eee #bii ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,rapidolite4 ---- ,pyrenees 7,delesse7 #cbaj #ahej nil #jjf nil #cfgj nil nil ,w4 #abaj #bfa ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,talc4 ---- ,zillerthal 7,delesse7 #fcjj nil nil trace nil #ccfj nil nil ,w4 #caj #bgh ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,the ,,amphibole ,,and ,,pyroxene ,,group ,,tremolite4 ---- ,st4 ,gothard 7,rammelsbeg7 #ehee nil nil nil #acij #bffc nil nil ,f4,w4 #jcd #bic ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,actinolite4 ---- ,arendal1 in granite 7,rammelsberg7 #efgg #jig nil #ehh #acef #badh nil nil ,w4 #bbj #cjb ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,hornblende4 ---- ,faymont1 in diorite 7,deville7 #daii #aaff nil #bbbb #iee #abei nil #ajb ,w4 #adg #cbj ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ---- ,etna1 in volcanic 7,waltershausen7 #djia #acfh nil #agdi #acdd #acai nil nil ,w4 #jhe #cja ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,uralite4 ---- ,ural1 7,rammelsberg7 #ejge #efe nil #agbg #aaei #abbh nil nil ,w4 #ahj #cad ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,augite4 ---- ,bohemia1 in dolerite 7,rammelsberg7 #eaab #cch #jie #hjh #bced #abhb nil nil nil #cce ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ---- ,vesuvius1 in lava of #aheh 7,rammelsberg7 #difa #ddb nil #ijh #bbhc #adbb nil nil nil #cbe ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,diallage4 ---- ,harz1 in ,gabbro 7,rammelsberg7 #ebjj #caj nil #icf #afbi #ahea nil nil ,w4 #aaj #cbc ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,hypersthene4 ---- ,labrador1 in ,labrador-,rock 7,damour7 #eacf #jcg nil #bbei #cji #baca nil nil nil #cci ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,the ,,olivine ,,group ,,bronzite4 ---- ,greenland 7,v4 ,kobell7 #ehjj #acc #aaad nil nil #biff nil nil nil #cbj ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,,olivine4 ---- ,carlsbad1 in basalt 7,rammelsberg7 #cicd nil nil #adhe nil #deha nil nil nil #cdj ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ---- ,mount ,somma1 in volcanic 7,walmstedt7 #ajjh #jah nil #aegd nil #ddbb nil nil nil #ccc ,silica ,alumina ,sesquioxide of ,iron ,protoxides of ,iron and ,manganese ,lime ,magnesia ,potash ,soda ,other constituents ,specific gravity ,in the 8,other constituents0 the following signs are used3 ,f,fluorine1 ,li,lithia1 ,w,loss on igniting the mineral1 in most instances only ,water4 ,from the table above it will be observed that many minerals are omitted which1 even if they are of common occurrence1 are more to be regarded as accessory than as essential components of the rocks in which they are found4#c ,such are1 for example1 ,garnet1 ,epidote1 ,tourmaline1 ,idocrase1 ,andalusite1 ,scapolite1 the various ,zeolites1 and several other silicates of somewhat rarer occurrence4 ,magnetite1 ,titanoferrite1 and ,iron-pyrites also occur as normal constituents of various igneous rocks1 although in very small amount1 as also ,apatite1 or phosphate of lime4 ,the other salts of lime1 including its carbonate or calcite1 although often met with1 are invariably products of secondary chemical action4 ,the ,zeolites1 above mentioned1 so named from the manner in which they froth up under the blow-pipe and melt into a glass1 differ in their chemical composition from all the other mineral constituents of volcanic rocks1 since they are hydrated silicates containing from #aj to #be per cent of water4 ,they abound in some trappean rocks and ancient lavas1 where they fill up vesicular cavities and interstices in the substance of the rocks1 but are rarely found in any quantity in recent lavas2 in most cases they are to be regarded as secondary products formed by the action of water on the other constituents of the rocks4 ,among them the species ,analcime1 ,stilbite1 ,natrolite1 and ,chabazite may be mentioned as of most common occurrence4 ,quartz ,group4--,the microscope has shown that pure quartz is oftener present in lavas than was formerly supposed4 ,it had been argued that the quartz in granite having a specific gravity of #bf1 was not of purely igneous origin1 because the silica resulting from fusion in the laboratory has only a specific gravity of #bc4 ,but ,mr4 ,david ,forbes has ascertained that the free quartz in trachytes1 which are known to have flowed as lava1 has the same specific gravity as the ordinary quartz of granite2 and the recent researches of ,von ,rath and others prove that the mineral ,tridymite1 which is crystallised silica of specific gravity #bc 7see ,table1 p4 #dii71 is of common occurrence in the volcanic rocks of ,mexico1 ,auvergne1 the ,rhine1 and elsewhere1 although hitherto entirely overlooked4 ,feldspar ,group4--,in the ,feldspar group 7,table1 p4 #dii7 the five mineral species most commonly met with as rock constituents are3 #a4 ,orthoclase1 often called common or potash-feldspar4 #b4 ,albite1 or soda-feldspar1 a mineral which plays a more subordinate part than was formerly supposed1 this name having been given to much which has since been proved to be ,oligoclase4 #c4 ,oligoclase1 or soda-lime feldspar1 in which soda is present in much larger proportion than lime1 and of which mineral andesite are andesine1 is considered to be a variety4 #d4 ,labradorite1 or lime-soda-feldspar1 in which the proportions of lime and soda are the reverse to what they are in ,oligoclase4 #e4 ,anorthite or lime-feldspar4 ,the two latter feldspars are rarely if ever found to enter into the composition of rocks containing quartz4 ,in employing such terms as potash-feldspar1 etc41 it must1 however1 always be borne in mind that it is only intended to direct attention to the predominant alkali or alkaline earth in the mineral1 not to assert the absence of the others1 which in most cases will be found to be present in minor quantity4 ,thus potash-feldspar 7orthoclase7 almost always contains a little soda1 and often traces of lime or magnesia2 and in like manner with the others4 ,the terms 8glassy0 and 8compact0 feldspars only refer to structure1 and not to species or composition2 the student should be prepared to meet with any of the above feldspars in either of these conditions3 the glassy state being apparently due to quick cooling1 and the compact to conditions unfavourable to crystallisation2 the so-called 8compact feldspar0 is also very commonly found to be an admixture of more than one feldspar species1 and frequently also contains quartz and other extraneous mineral matter only to be detected by the microscope4 ,feldspars when arranged according to their system of crystallisation are monoclinic1 having one axis obliquely inclined2 or triclinic1 having the three axes all obliquely inclined to each other4 ,if arranged with reference to their cleavage they are orthoclastic1 the fracture taking place always at a right angle2 or plagioclastic1 in which the cleavages are oblique to one another4 ,orthoclase is orthoclastic and monoclinic2 all the other feldspars are plagioclastic and triclinic4 ,minerals in ,meteorites4--,that variety of the ,feldspar ,group which is called ,anorthite has been shown by ,rammelsberg to occur in a meteoric stone1 and his analysis proves it to be almost identical in its chemical proportions to the same mineral in the lavas of modern volcanoes4 ,so also ,bronzite 7,enstatite7 and ,olivine have been met with in meteorites shown by analysis to come remarkably near to these minerals in ordinary rocks4 ,mica ,group4--,with regard to the micas1 the four principal species 7,table1 p4 #dii7 all contain potash in nearly the same proportion1 but differ greatly in the proportion and nature of their other ingredients4 ,muscovite is often called common or potash mica2 ,lepidolite is characterised by containing lithia in addition2 ,biotite contains a large amount of magnesia and oxide of iron2 whilst ,phlogopite contains still more of the former substance4 ,in rocks containing quartz1 muscovite or lepidolite are most common4 ,the mica in recent volcanic rocks1 gabbros1 and diorites is usually ,biotite1 while that so common in metamorphic limestones is usually1 if not always1 ,phlogopite4 ,amphibole and ,pyroxene ,group4--,the minerals included in the table under the ,amphibole and ,pyroxene ,group differ somewhat in their crystallisation form1 though they all belong to the monoclinic system4 ,amphibole is a general name for all the different varieties of ,hornblende1 ,actinolite1 ,tremolite1 etc41 while ,pyroxene includes ,augite1 ,diallage1 ,malacolite1 ,sahlite1 etc4 ,the two divisions are so much allied in chemical composition and crystallographic characters1 and blend so completely one into the other in ,uralite 7see page #dii71 that it is perhaps best to unite them in one group4 ,theory of ,isomorphism4--,the history of the changes of opinion on this point is curious and instructive4 ,werner first distinguished augite from hornblende2 and his proposal to separate them obtained afterwards the sanction of ,hay1 ,mohs1 and other celebrated mineralogists4 ,it was agreed that the form of the crystals of the two species was different1 and also their structure1 as shown by cleavage--that is to say1 by breaking or cleaving the mineral with a chisel1 or a blow of the hammer1 in the direction in which it yields most readily4 ,it was also found by analysis that augite usually contained more lime1 less alumina1 and no fluoric acid2 which last1 though not always found in hornblende1 often enters into its composition in minute quantity4 ,in addition to these characters1 it was remarked as a geological fact1 that augite and hornblende are very rarely associated together in the same rock4 ,it was also remarked that in the crystalline slags of furnaces augitic forms were frequent1 the hornblendic entirely absent2 hence it was conjectured that hornblende might be the result of slow1 and augite of rapid cooling4 ,this view was confirmed by the fact that ,mitscherlich and ,berthier were able to make augite artificially1 but could never succeed in forming hornblende4 ,lastly1 ,gustavus ,rose fused a mass of hornblende in a porcelain furnace1 and found that it did not1 on cooling1 assume its previous shape1 but invariably took that of augite4 ,the same mineralogist observed certain crystals called ,uralite 7see ,table1 p4 #dii7 in rocks from ,siberia1 which possessed the cleavage and chemical composition of hornblende1 while they had the external form of augite4 ,if1 from these data1 it is inferred that the same substance may assume the crystalline forms of hornblende or augite indifferently1 according to the more or less rapid cooling of the melted mass1 it is nevertheless certain that the variety commonly called augite1 and recognised by a peculiar crystalline form1 has usually more lime in it1 and less alumina1 than that called hornblende1 although the quantities of these elements do not seem to be always the same4 ,unquestionably the facts and experiments above mentioned show the very near affinity of hornblende and augite2 but even the convertibility of one into the other1 by melting and recrystallising1 does not perhaps demonstrate their absolute identity4 ,for there is often some portion of the materials in a crystal which are not in perfect chemical combination with the rest4 ,carbonate of lime1 for example1 sometimes carries with it a considerable quantity of silex into its own form of crystal1 the silex being mechanically mixed as sand1 and yet not preventing the carbonate of lime from assuming the form proper to it4 ,this is an extreme case1 but in many others some one or more of the ingredients in a crystal may be excluded from perfect chemical union2 and after fusion1 when the mass recrystallises1 the same elements may combine perfectly or in new proportions1 and thus a new mineral may be produced4 ,or some one of the gaseous elements of the atmosphere1 the oxygen for example1 may1 when the melted matter reconsolidates1 combine with some one of the component elements4 ,the different quantity of the impurities or the refuse above alluded to1 which may occur in all but the most transparent and perfect crystals1 may partly explain the discordant results at which experienced chemists have arrived in their analysis of the same mineral4 ,for the reader will often find that crystals of a mineral determined to be the same by physical characters1 crystalline form1 and optical properties1 have been declared by skilful analysers to be composed of distinct elements4 ,this disagreement seemed at first subversive of the atomic theory1 or the doctrine that there is a fixed and constant relation between the crystalline form and structure of a mineral and its chemical composition4 ,the apparent anomaly1 however1 which threatened to throw the whole science of mineralogy into confusion1 was reconciled to fixed principles by the discoveries of ,professor ,mitscherlich at ,berlin1 who ascertained that the composition of the minerals which had appeared so variable was governed by a general law1 to which he gave the name of isomorphism 7from isos1 equal1 and morphe1 form74 ,according to this law1 the ingredients of a given species of mineral are not absolutely fixed as to their kind and quality2 but one ingredient may be replaced by an equivalent portion of some analogous ingredient4 ,thus1 in augite1 the lime may be in part replaced by portions of protoxide of iron1 or of manganese1 while the form of the crystal1 and the angle of its cleavage planes1 remain the same4 ,these vicarious substitutions1 however1 of particular elements cannot exceed certain defined limits4 ,basaltic ,rocks4--,the two principal families of trappean or volcanic rocks are the basalts and the trachytes1 which differ chiefly from each other in the quantity of silica which they contain4 ,the basaltic rocks are comparatively poor in silica1 containing less than #ej per cent of that mineral1 and none in a pure state or as free quartz1 apart from the rest of the matrix4 ,they contain a larger proportion of lime and magnesia than the trachytes1 so that they are heavier1 independently of the frequent presence of the oxides of iron which in some cases forms more than a fourth part of the whole mass4 ,abich has1 therefore1 proposed that we should weigh these rocks1 in order to appreciate their composition in cases where it is impossible to separate their component minerals4 ,thus1 basalt from ,staffa1 containing #dghj per cent of silica1 has a specific gravity of #bie2 whereas trachyte1 which has #ff per cent of silica1 has a specific gravity of only #bfh2 trachytic porphyry1 containing #fi per cent of silica1 a specific gravity of only #beh4 ,if we then take a rock of intermediate composition1 such as that prevailing in the ,peak of ,teneriffe1 which ,abich calls ,trachyte-dolerite1 its proportion of silica being intermediate1 or #eh per cent1 it weighs #bgh1 or more than trachyte1 and less than basalt4#d ,basalt4--,the different varieties of this rock are distinguished by the names of basalts1 anamezites1 and dolerites1 names which1 however1 only denote differences in texture without implying any difference in mineral or chemical composition3 the term ,basalt being used only when the rock is compact1 amorphous1 and often semi-vitreous in texture1 and when it breaks with a perfect conchoidal fracture2 when1 however1 it is uniformly crystalline in appearance1 yet very close-grained1 the name ,anamesite 7from anamesos1 intermediate7 is employed1 but if the rock be so coarsely crystallised that its different mineral constituents can be easily recognised by the eye1 it is called ,dolerite 7from doleros1 deceitful71 in allusion to the difficulty of distinguishing it from some of the rocks known as ,plutonic4 ,melaphyre is often quite undistinguishable in external appearance from basalt1 for although rarely so heavy1 dark-coloured1 or compact1 it may present at times all these varieties of texture4 ,both these rocks are composed of triclinic feldspar and augite with more or less olivine1 magnetic or titaniferous oxide of iron1 and usually a little nepheline1 leucite1 and apatite2 basalt usually contains considerably more olivine than melaphyre1 but chemically they are closely allied1 although the melaphyres usually contain more silica and alumina1 with less oxides of iron1 lime1 and magnesia1 than the basalts4 ,the ,rowley ,hills in ,staffordshire1 commonly known as ,rowley ,ragstone1 are melaphyre4 ,greenstone4--,this name has usually been extended to all granular mixtures1 whether of hornblende and feldspar1 or of augite and feldspar4 ,the term diorite has been applied exclusively to compounds of hornblende and triclinic feldspar4 ,labrador-rock is a term used for a compound of labradorite or labrador-feldspar and hypersthene2 when the hypersthene predominates it is sometimes known under the name of ,hypersthene-rock4 ,gabbro and ,diabase are rocks mainly composed of triclinic feldspars and diallage4 ,all these rocks become sometimes very crystalline1 and help to connect the volcanic with the ,plutonic formations1 which will be treated of in ,chapter ,,xxxi4 ,trachytic ,rocks4--,the name trachyte 7from 9999,greek trachus1 rough7 was originally given to a coarse granular feldspathic rock which was rough and gritty to the touch4 ,the term was subsequently made to include other rocks1 such as clinkstone and obsidian1 which have the same mineral composition1 but to which1 owing to their different texture1 the word in its original meaning would not apply4 ,the feldspars which occur in ,trachytic rocks are invariably those which contain the largest proportion of silica1 or from #fj to #gj per cent of that mineral4 ,through the base are usually disseminated crystals of glassy feldspar1 mica1 and sometimes hornblende4 ,although quartz is not a necessary ingredient in the composition of this rock1 it is very frequently present1 and the quartz trachytes are very largely developed in many volcanic districts4 ,in this respect the trachytes differ entirely from the members of the ,basaltic family1 and are more nearly allied to the granites4 ,obsidian4--,obsidian1 ,pitchstone1 and ,pearlstone are only different forms of a volcanic glass produced by the fusion of trachytic rocks4 ,the distinction between them is caused by different rates of cooling from the melted state1 as has been proved by experiment4 ,obsidian is of a black or ash-grey colour1 and though opaque in mass is transparent in thin edges4 ,clinkstone or ,phonolite4--,among the rocks of the trachytic family1 or those in which the feldspars are rich in silica1 that termed ,clinkstone or ,phonolite is conspicuous by its fissile structure1 and its tendency to lamination1 which is such as sometimes to render it useful as roofing-slate4 ,it rings when struck with the hammer1 whence its name2 is compact1 and usually of a greyish blue or brownish colour2 is variable in composition1 but almost entirely composed of feldspar4 ,when it contains disseminated crystals of feldspar1 it is called ,clinkstone porphyry4 ,volcanic ,rocks distinguished by special ,forms of ,structure4--,many volcanic rocks are commonly spoken of under names denoting structure alone1 which must not be taken to imply that they are distinct rocks1 i4e41 that they differ from one another either in mineral or chemical composition4 ,thus the terms ,trachytic porphyry1 ,trachytic tuff1 etc41 merely refer to the same rock under different conditions of mechanical aggregation or crystalline development which would be more correctly expressed by the use of the adjective1 as porphyritic trachyte1 etc41 but as these terms are so commonly employed it is considered advisable to direct the student's attention to them4 ,fig4 #ehf3 ,porphyry4 ,white crystals of feldspar in a dark base of hornblende and feldspar4 ,porphyry is one of this class1 and very characteristic of the volcanic formations4 ,when distinct crystals of one or more minerals are scattered through an earthy or compact base1 the rock is termed a porphyry 7see ,fig4 #ehf74 ,thus trachyte is usually porphyritic2 for in it1 as in many modern lavas1 there are crystals of feldspar2 but in some porphyries the crystals are of augite1 olivine1 or other minerals4 ,if the base be greenstone1 basalt1 or pitchstone1 the rock may be denominated greenstone-porphyry1 pitchstone-porphyry1 and so forth4 ,the old classical type of this form of rock is the red porphyry of ,egypt1 or the well-known 8,rosso antico40 ,it consists1 according to ,delesse1 of a red feldspathic base in which are disseminated rose-coloured crystals of the feldspar called oligoclase1 with some plates of blackish hornblende and grains of oxide of iron 7iron-glance74 ,red quartziferous porphyry is a much more siliceous rock1 containing about #gj or #hj per cent of silex1 while that of ,egypt has only #fb per cent4 ,amygdaloid4--,this is also another form of igneous rock1 admitting of every variety of composition4 ,it comprehends any rock in which round or almond-shaped nodules of some mineral1 such as agate1 chalcedony1 calcareous spar1 or zeolite1 are scattered through a base of wacke1 basalt1 greenstone1 or other kind of trap4 ,it derives its name from the ,greek word amygdalon1 an almond4 ,the origin of this structure cannot be doubted1 for we may trace the process of its formation in modern lavas4 ,small pores or cells are caused by bubbles of steam and gas confined in the melted matter4 ,after or during consolidation1 these empty spaces are gradually filled up by matter separating from the mass1 or infiltered by water permeating the rock4 ,as these bubbles have been sometimes lengthened by the flow of the lava before it finally cooled1 the contents of such cavities have the form of almonds4 ,in some of the amygdaloidal traps of ,scotland1 where the nodules have decomposed1 the empty cells are seen to have a glazed or vitreous coating1 and in this respect exactly resemble scoriaceous lavas1 or the slags of furnaces4 ,fig4 #ehg3 ,scoriaceous lava in part converted into an amygdaloid4 ,fig4 #ehg represents a fragment of stone taken from the upper part of a sheet of basaltic lava in ,auvergne4 ,one-half is scoriaceous1 the pores being perfectly empty2 the other part is amygdaloidal1 the pores or cells being mostly filled up with carbonate of lime1 forming white kernels4 ,lava4--,this term has a somewhat vague signification1 having been applied to all melted matter observed to flow in streams from volcanic vents4 ,when this matter consolidates in the open air1 the upper part is usually scoriaceous1 and the mass becomes more and more stony as we descend1 or in proportion as it has consolidated more slowly and under greater pressure4 ,at the bottom1 however1 of a stream of lava1 a small portion of scoriaceous rock very frequently occurs1 formed by the first thin sheet of liquid matter1 which often precedes the main current1 and solidifies under slight pressure4 ,the more compact lavas are often porphyritic1 but even the scoriaceous part sometimes contains imperfect crystals1 which have been derived from some older rocks1 in which the crystals pre-existed1 but were not melted1 as being more infusible in their nature4 ,although melted matter rising in a crater1 and even that which enters a rent on the side of a crater1 is called lava1 yet this term belongs more properly to that which has flowed either in the open air or on the bed of a lake or sea4 ,if the same fluid has not reached the surface1 but has been merely injected into fissures below ground1 it is called trap4 ,there is every variety of composition in lavas2 some are trachytic1 as in the ,peak of ,teneriffe2 a great number are basaltic1 as in ,vesuvius and ,auvergne2 others are andesitic1 as those of ,chili2 some of the most modern in ,vesuvius consist of green augite1 and many of those of ,etna of augite and labrador-feldspar4#e ,scori and ,pumice may next be mentioned1 as porous rocks produced by the action of gases on materials melted by volcanic heat4 ,scori are usually of a reddish-brown and black colour1 and are the cinders and slags of basaltic or augitic lavas4 ,pumice is a light1 spongy1 fibrous substance1 produced by the action of gases on trachytic and other lavas2 the relation1 however1 of its origin to the composition of lava is not yet well understood4 ,von ,buch says that it never occurs where only labrador-feldspar is present4 ,volcanic ,ash or ,tuff1 ,trap ,tuff4--,small angular fragments of the scori and pumice1 above-mentioned1 and the dust of the same1 produced by volcanic explosions1 form the tuffs which abound in all regions of active volcanoes1 where showers of these materials1 together with small pieces of other rocks ejected from the crater1 and more or less burnt1 fall down upon the land or into the sea4 ,here they often become mingled with shells1 and are stratified4 ,such tuffs are sometimes bound together by a calcareous cement1 and form a stone susceptible of a beautiful polish4 ,but even when little or no lime is present1 there is a great tendency in the materials of ordinary tuffs to cohere together4 ,the term volcanic ash has been much used for rocks of all ages supposed to have been derived from matter ejected in a melted state from volcanic orifices4 ,we meet occasionally with extremely compact beds of volcanic materials1 interstratified with fossiliferous rocks4 ,these may sometimes be tuffs1 although their density or compactness is such as the cause them to resemble many of those kinds of trap which are found in ordinary dikes4 ,wacke is a name given to a decomposed state of various trap rocks of the basaltic family1 or those which are poor in silica4 ,it resembles clay of a yellowish or brown colour1 and passes gradually from the soft state to the hard dolerite1 greenstone1 or other trap rock from which it has been derived4 ,agglomerate4--,in the neighbourhood of volcanic vents1 we frequently observe accumulations of angular fragments of rocks formed during eruptions by the explosive action of steam1 which shatters the subjacent stony formations1 and hurls them up into the air4 ,they then fall in showers around the cone or crater1 or may be spread for some distance over the surrounding country4 ,the fragments consist usually of different varieties of scoriaceous and compact lavas2 but other kinds of rock1 such as granite or even fossiliferous limestones1 may be intermixed2 in short1 any substance through which the expansive gases have forced their way4 ,the dispersion of such materials may be aided by the wind1 as it varies in direction or intensity1 and by the slope of the cone down which they roll1 or by floods of rain1 which often accompany eruptions4 ,but if the power of running water1 or of the waves and currents of the sea1 be sufficient to carry the fragments to a distance1 it can scarcely fail to wear off their angles1 and the formation then becomes a conglomerate4 ,if occasionally globular pieces of scori abound in an agglomerate1 they may not owe their round form to attrition4 ,when all the angular fragments are of volcanic rocks the mass is usually termed a volcanic breccia4 ,laterite is a red or brick-like rock composed of silicate of alumina and oxide of iron4 ,the red layers called 8ochre beds10 dividing the lavas of the ,giant's ,causeway1 are laterites4 ,these were found by ,delesse to be trap impregnated with the red oxide of iron1 and in part reduced to kaolin4 ,when still more decomposed1 they were found to be clay coloured by red ochre4 ,as two of the lavas of the ,giant's ,causeway are parted by a bed of lignite1 it is not improbable that the layers of laterite seen in the ,antrim cliffs resulted from atmospheric decomposition4 ,in ,madeira and the ,canary ,islands streams of lava of subarial origin are often divided by red bands of laterite1 probably ancient soils formed by the decomposition of the surfaces of lava-currents1 many of these soils having been coloured red in the atmosphere by oxide of iron1 others burnt into a red brick by the overflowing of heated lavas4 ,these red bands are sometimes prismatic1 the small prisms being at right angles to the sheets of lava4 ,red clay or red marl1 formed as above stated by the disintegration of lava1 scori1 or tuff1 has often accumulated to a great thickness in the valleys of ,madeira1 being washed into them by alluvial action2 and some of the thick beds of laterite in ,india may have had a similar origin4 ,in ,india1 however1 especially in the ,deccan1 the term 8laterite0 seems to have been used too vaguely to answer the above definition4 ,the vegetable soil in the gardens of the suburbs of ,catania which was overflowed by the lava of #affi was turned or burnt into a layer of red brick-coloured stone1 or in other words1 into laterite1 which may now be seen supporting the old lava-current4 ,columnar and ,globular ,structure4--,one of the characteristic forms of volcanic rocks1 especially of basalt1 is the columnar1 where large masses are divided into regular prisms1 sometimes easily separable1 but in other cases adhering firmly together4 ,the columns vary1 in the number of angles1 from three to twelve2 but they have most commonly from five to seven sides4 ,they are often divided transversely1 at nearly equal distances1 like the joints in a vertebral column1 as in the ,giant's ,causeway1 in ,ireland4 ,they vary exceedingly in respect to length and diameter4 ,dr4 ,mac,culloch mentions some in ,skye which are about #djj feet long2 others1 in ,morven1 not exceeding an inch4 ,in regard to diameter1 those of ,ailsa measure nine feet1 and those of ,morven an inch or less4#f ,they are usually straight1 but sometimes curved2 and examples of both these occur in the island of ,staffa4 ,in a horizontal bed or sheet of trap the columns are vertical2 in a vertical dike they are horizontal4 ,fig4 #ehh3 ,lava of ,la ,coupe d',ayzac1 near ,antraigue1 in the ,department of ,ardche4 ,it being assumed that columnar trap has consolidated from a fluid state1 the prisms are said to be always at right angles to the cooling surfaces4 ,if these surfaces1 therefore1 instead of being either perpendicular or horizontal1 are curved1 the columns ought to be inclined at every angle to the horizon2 and there is a beautiful exemplification of this phenomenon in one of the valleys of the ,vivarais1 a mountainous district in the ,south of ,france1 where1 in the midst of a region of gneiss1 a geologist encounters unexpectedly several volcanic cones of loose sand and scori4 ,from the crater of one of these cones1 called ,la ,coupe d',ayzac1 a stream of lava has descended and occupied the bottom of a narrow valley1 except at those points where the river ,volant1 or the torrents which join it1 have cut away portions of the solid lava4 ,fig4 #ehh represents the remnant of the lava at one of these points4 ,it is clear that the lava once filled the whole valley up to the dotted line d a2 but the river has gradually swept away all below that line1 while the tributary torrent has laid open a transverse section2 by which we perceive1 in the first place1 that the lava is composed1 as usual in this country1 of three parts3 the uppermost1 at a1 being scoriaceous1 the second b1 presenting irregular prisms2 and the third1 c1 with regular columns1 which are vertical on the banks of the ,volant1 where they rest on a horizontal base of gneiss1 but which are inclined at an angle of #de1 at g1 and are nearly horizontal at f1 their position having been everywhere determined1 according to the law before mentioned1 by the form of the original valley4 ,fig4 #ehi3 ,columnar basalt in the ,vicentin4 ,in ,fig4 #ehi1 a view is given of some of the inclined and curved columns which present themselves on the sides of the valleys in the hilly region north of ,vicenza1 in ,italy1 and at the foot of the higher ,alps4#g ,unlike those of the ,vivarais1 last mentioned1 the basalt of this country was evidently submarine1 and the present valleys have since been hollowed out by denudation4 ,the columnar structure is by no means peculiar to the trap rocks in which augite abounds2 it is also observed in trachyte1 and other feldspathic rocks of the igneous class1 although in these it is rarely exhibited in such regular polygonal forms4 ,it has been already stated that basaltic columns are often divided by cross-joints4 ,sometimes each segment1 instead of an angular1 assumes a spheroidal form1 so that a pillar is made up of a pile of balls1 usually flattened1 as in the ,cheese-grotto at ,bertrich-,baden1 in the ,eifel1 near the ,moselle 7,fig4 #eij74 ,the basalt there is part of a small stream of lava1 from #cj to #dj feet thick1 which has proceeded from one of several volcanic craters1 still extant1 on the neighbouring heights4 ,fig4 #eij3 ,basaltic pillars of ,ksegrotte1 ,bertrich-,baden1 half-way between ,trves and ,coblenz4 ,in some masses of decomposing greenstone1 basalt1 and other trap rocks1 the globular structure is so conspicuous that the rock has the appearance of a heap of large cannon balls4 ,according to ,m4 ,delesse1 the centre of each spheroid has been a centre of crystallisation1 around which the different minerals of the rock arranged themselves symmetrically during the process of cooling4 ,but it was also1 he says1 a centre of contraction1 produced by the same cooling1 the globular form1 therefore1 of such spheroids being the combined result of crystallisation and contraction4#h ,fig4 #eia3 ,globiform pitchstone4 ,chiaja di ,luna1 ,isle of ,ponza4 ,mr4 ,scrope gives as an illustration of this structure a resinous trachyte or pitchstone-porphyry in one of the ,ponza islands1 which rise from the ,mediterranean1 off the coast of ,terracina and ,gaeta4 ,the globes vary from a few inches to three feet in diameter1 and are of an ellipsoidal form 7see ,fig4 #eia74 ,the whole rock is in a state of decomposition1 8and when the balls10 says ,mr4 ,scrope1 8have been exposed a short time to the weather1 they scale off at a touch into numerous concentric coats1 like those of a bulbous root1 inclosing a compact nucleus4 ,the lamin of this nucleus have not been so much loosened by decomposition2 but the application of a ruder blow will produce a still further exfoliation40#i ,fig4 #eib3 ,dike in valley1 near ,brazen ,head1 ,madeira4 7,from a drawing of ,captain ,basil ,hall1 ,r4,n47 ,volcanic or ,trap ,dikes4--,the leading varieties of the trappean rocks--basalt1 greenstone1 trachyte1 and the rest--are found sometimes in dikes penetrating stratified and unstratified formations1 sometimes in shapeless masses protruding through or overlying them1 or in horizontal sheets intercalated between strata4 ,fissures have already been spoken of as occurring in all kinds of rocks1 some a few feet1 others many yards in width1 and often filled up with earth or angular pieces of stone1 or with sand and pebbles4 ,instead of such materials1 suppose a quantity of melted stone to be driven or injected into an open rent1 and there consolidated1 we have then a tabular mass resembling a wall1 and called a trap dike4 ,it is not uncommon to find such dikes passing through strata of soft materials1 such as tuff1 scori1 or shale1 which1 being more perishable than the trap1 are often washed away by the sea1 rivers1 or rain1 in which case the dike stands prominently out in the face of precipices1 or on the level surface of a country 7see ,fig4 #eib74 ,in the islands of ,arran and ,skye1 and in other parts of ,scotland1 where sandstone1 conglomerate1 and other hard rocks are traversed by dikes of trap1 the converse of the above phenomenon is seen4 ,the dike1 having decomposed more rapidly than the containing rock1 has once more left open the original fissure1 often for a distance of many yards inland from the sea-coast4 ,there is yet another case1 by no means uncommon in ,arran and other parts of ,scotland1 where the strata in contact with the dike1 and for a certain distance from it1 have been hardened1 so as to resist the action of the weather more than the dike itself1 or the surrounding rocks4 ,when this happens1 two parallel walls of indurated strata are seen protruding above the general level of the country and following the course of the dike4 ,in ,fig4 #eic1 a ground plan is given of a ramifying dike of greenstone1 which ,i observed cutting through sandstone on the beach near ,kildonan ,castle1 in ,arran4 ,the larger branch varies from five to seven feet in width1 which will afford a scale of measurement for the whole4 ,fig4 #eic3 ,ground-plan of greenstone dikes traversing sandstone4 ,in the ,hebrides and other countries1 the same masses of trap which occupy the surface of the country far and wide1 concealing the subjacent stratified rocks1 are seen also in the sea-cliffs1 prolonged downward in veins or dikes1 which probably unite with other masses of igneous rock at a greater depth4 ,the largest of the dikes represented in ,fig4 #eid1 and which are seen in part of the coast of ,skye1 is no less than #ajj feet in width4 ,fig4 #eid3 ,trap dividing and covering sandstone near ,suishnish1 in ,skye4 ,every variety of trap-rock is sometimes found in dikes1 as basalt1 greenstone1 feldspar-porphyry1 and trachyte4 ,the amygdaloidal traps also occur1 though more rarely1 and even tuff and breccia1 for the materials of these last may be washed down into open fissures at the bottom of the sea1 or during eruption on the land may be showered into them from the air4 ,some dikes of trap may be followed for leagues uninterruptedly in nearly a straight direction1 as in the north of ,england1 showing that the fissures which they fill must have been of extraordinary length4 ,rocks altered by ,volcanic ,dikes4--,after these remarks on the form and composition of dikes themselves1 ,i shall describe the alterations which they sometimes produce in the rocks in contact with them4 ,the changes are usually such as the heat of melted matter and of the entangled steam and gases might be expected to cause4 ,plas-,newydd3 ,dike cutting through ,shale4--,a striking example1 near ,plas-,newydd1 in ,anglesea1 has been described by ,professor ,henslow4#aj ,the dike is #acd feet wide1 and consists of a rock which is a compound of feldspar and augite 7dolerite of some authors74 ,strata of shale and argillaceous limestone1 through which it cuts perpendicularly1 are altered to a distance of #cj1 or even1 in some places1 of #ce feet from the edge of the dike4 ,the shale1 as it approaches the trap1 becomes gradually more compact1 and is most indurated where nearest the junction4 ,here it loses part of its schistose structure1 but the separation into parallel layers is still discernible4 ,in several places the shale is converted into hard porcelanous jasper4 ,in the most hardened part of the mass the fossil shells1 principally ,producti1 are nearly obliterated2 yet even here their impressions may frequently be traced4 ,the argillaceous limestone undergoes analogous mutations1 losing its earthy texture as it approaches the dike1 and becoming granular and crystalline4 ,but the most extraordinary phenomenon is the appearance in the shale of numerous crystals of analcime and garnet1 which are distinctly confined to those portions of the rock affected by the dike4#aa ,some garnets contain as much as #bj per cent of lime1 which they may have derived from the decomposition of the fossil shells or ,producti4 ,the same mineral has been observed1 under very analogous circumstances1 in ,high ,teesdale1 by ,professor ,sedgwick1 where it also occurs in shale and limestone1 altered by basalt4#ab ,antrim3 ,dike cutting through ,chalk4--,in several parts of the county of ,antrim1 in the north of ,ireland1 chalk with flints is traversed by basaltic dikes4 ,the chalk is there converted into granular marble near the basalt1 the change sometimes extending eight or ten feet from the wall of the dike1 being greatest near the point of contact1 and thence gradually decreasing till it becomes evanescent4 8,the extreme effect10 says ,dr4 ,berger1 8presents a dark brown crystalline limestone1 the crystals running in flakes as large as those of coarse primitive 7metamorphic7 limestone2 the next state is saccharine1 then fine grained and arenaceous2 a compact variety1 having a porcelanous aspect and a bluish-grey colour1 succeeds3 this1 towards the outer edge1 becomes yellowish-white1 and insensibly graduates into the unaltered chalk4 ,the flints in the altered chalk usually assume a grey yellowish colour40#ac ,all traces of organic remains are effaced in that part of the limestone which is most crystalline4 ,fig4 #eie3 ,basaltic dikes in chalk in ,island of ,rathlin1 ,antrim4 ,ground-plan as seen on the beach4 ,fig4 #eie3 ,basaltic dikes in chalk in ,island of ,rathlin1 ,antrim4 ,ground-plan as seen on the beach4 7,conybeare and ,buckland#ad7 ,fig4 #eie represents three basaltic dikes traversing the chalk1 all within the distance of #ij feet4 ,the chalk contiguous to the two outer dikes is converted into a finely granular marble1 m1 m1 as are the whole of the masses between the outer dikes and the central one4 ,the entire contrast in the composition and colour of the intrusive and invaded rocks1 in these cases1 renders the phenomena peculiarly clear and interesting4 ,another of the dikes of the north-east of ,ireland has converted a mass of red sandstone into hornstone4 ,by another1 the shale of the coal-measures has been indurated1 assuming the character of flinty slate2 and in another place the slate-clay of the lias has been changed into flinty slate1 which still retains numerous impressions of ammonites4#ae ,it might have been anticipated that beds of coal would1 from their combustible nature1 be affected in an extraordinary degree by the contact of melted rock4 ,accordingly1 one of the greenstone dikes of ,antrim1 on passing through a bed of coal1 reduces it to a cinder for the space of nine feet on each side4 ,at ,cockfield ,fell1 in the north of ,england1 a similar change is observed4 ,specimens taken at the distance of about thirty yards from the trap are not distinguishable from ordinary pit-coal2 those nearer the dike are like cinders1 and have all the character of coke2 while those close to it are converted into a substance resembling soot4#af ,it is by no means uncommon to meet with the same rocks1 even in the same districts1 absolutely unchanged in the proximity of volcanic dikes4 ,this great inequality in the effects of the igneous rocks may often arise from an original difference in their temperature1 and in that of the entangled gases1 such as is ascertained to prevail in different lavas1 or in the same lava near its source and at a distance from it4 ,the power also of the invaded rocks to conduct heat may vary1 according to their composition1 structure1 and the fractures which they may have experienced1 and perhaps1 also1 according to the quantity of water 7so capable of being heated7 which they contain4 ,it must happen in some cases that the component materials are mixed in such proportions as to prepare them readily to enter into chemical union1 and form new minerals2 while in other cases the mass may be more homogeneous1 or the proportions less adapted for such union4 ,we must also take into consideration1 that one fissure may be simply filled with lava1 which may begin to cool from the first2 whereas in other cases the fissure may give passage to a current of melted matter1 which may ascend for days or months1 feeding streams which are overflowing the country above1 or being ejected in the shape of scori from some crater4 ,if the walls of a rent1 moreover1 are heated by hot vapour before the lava rises1 as we know may happen on the flanks of a volcano1 the additional heat supplied by the dike and its gases will act more powerfully4 ,intrusion of ,trap between ,strata4--,masses of trap are not unfrequently met with intercalated between strata1 and maintaining their parallelism to the planes of stratification throughout large areas4 ,they must in some places have forced their way laterally between the divisions of the strata1 a direction in which there would be the least resistance to an advancing fluid1 if no vertical rents communicated with the surface1 and a powerful hydrostatic pressure were caused by gases propelling the lava upward4 ,relation of ,trappean ,rocks to the ,products of active ,volcanoes4--,when we reflect on the changes above described in the strata near their contact with trap dikes1 and consider how complete is the analogy or often identity in composition and structure of the rocks called trappean and the lavas of active volcanoes1 it seems difficult at first to understand how so much doubt could have prevailed for half a century as to whether trap was of igneous or aqueous origin4 ,to a certain extent1 however1 there was a real distinction between the trappean formations and those to which the term volcanic was almost exclusively confined4 ,a large portion of the trappean rocks first studied in the north of ,germany1 and in ,norway1 ,france1 ,scotland1 and other countries1 were such as had been formed entirely under water1 or had been injected into fissures and intruded between strata1 and which had never flowed out in the air1 or over the bottom of a shallow sea4 ,when these products1 therefore1 of submarine or subterranean igneous action were contrasted with loose cones of scori1 tuff1 and lava1 or with narrow streams of lava in great part scoriaceous and porous1 such as were observed to have proceeded from ,vesuvius and ,etna1 the resemblance seemed remote and equivocal4 ,it was1 in truth1 like comparing the roots of a tree with its leaves and branches1 which1 although the belong to the same plant1 differ in form1 texture1 colour1 mode of growth1 and position4 ,the external cone1 with its loose ashes and porous lava1 may be likened to the light foliage and branches1 and the rocks concealed far below1 to the roots4 ,but it is not enough to say of the volcano1 8,quantum vertice in auras therias1 tantum radice in ,tartara tendit10 for its roots do literally reach downward to ,tartarus1 or to the regions of subterranean fire2 and what is concealed far below is probably always more important in volume and extent than what is visible above ground4 ,fig4 #eif3 ,strata intercepted by a trap dike1 and covered with alluvium4 ,we have already stated how frequently dense masses of strata have been removed by denudation from wide areas 7see ,chapter ,,vi72 and this fact prepares us to expect a similar destruction of whatever may once have formed the uppermost part of ancient submarine or subarial volcanoes1 more especially as those superficial parts are always of the lightest and most perishable materials4 ,the abrupt manner in which dikes of trap usually terminate at the surface 7see ,fig4 #eif71 and the water-worn pebbles of trap in the alluvium which covers the dike1 prove incontestably that whatever was uppermost in these formations has been swept away4 ,it is easy1 therefore1 to conceive that what is gone in regions of trap may have corresponded to what is now visible in active volcanoes4 ,as to the absence of porosity in the trappean formations1 the appearances are in a great degree deceptive1 for all amygdaloids are1 as already explained1 porous rocks1 into the cells of which mineral matter such as silex1 carbonate of lime1 and other ingredients1 have been subsequently introduced 7see p4 #ejg72 sometimes1 perhaps1 by secretion during the cooling and consolidation of lavas4 ,in the ,little ,cumbray1 one of the ,western ,islands1 near ,arran1 the amygdaloid sometimes contains elongated cavities filled with brown spar2 and when the nodules have been washed out1 the interior of the cavities is glazed with the vitreous varnish so characteristic of the pores of slaggy lavas4 ,even in some parts of this rock which are excluded from air and water1 the cells are empty1 and seem to have always remained in this state1 and are therefore undistinguishable from some modern lavas4#ag ,dr4 ,mac,culloch1 after examining with great attention these and the other igneous rocks of ,scotland1 observes1 8that it is a mere dispute about terms1 to refuse to the ancient eruptions of trap the name of submarine volcanoes2 for they are such in every essential point1 although they no longer eject fire and smoke40 ,the same author also considers it not improbable that some of the volcanic rocks of the same country may have been poured out in the open air4#ah ,it will be seen in the following chapters that in the earth's crust there are volcanic tuffs of all ages1 containing marine shells1 which bear witness to eruptions at many successive geological periods4 ,these tuffs1 and the associated trappean rocks1 must not be compared to lava and scori which had cooled in the open air4 ,their counterparts must be sought in the products of modern submarine volcanic eruptions4 ,if it be objected that we have no opportunity of studying these last1 it may be answered1 that subterranean movements have caused1 almost everywhere in regions of active volcanoes1 great changes in the relative level of land and sea1 in times comparatively modern1 so as to expose to view the effects of volcanic operations at the bottom of the sea4 #a ,principles1 vol4 ii1 pp4 #ef and #ade4 #b ,memoir on ,mount ,etna1 ,phil4 ,trans41 #aheh4 #c ,for analyses of these minerals see the ,mineralogies of ,dana and ,bristow4 #d ,dr4 ,daubeny on ,volcanoes1 #bnd ed41 pp4 #ad1 #ae4 #e ,g4 ,hose1 ,ann4 des ,mines1 tome viii1 p4 #cb4 #f ,mac,culloch ,sys4 of ,geol41 vol4 ii1 p4 #acg4 #g ,fortis1 ,mm4 sur l',hist4 ,nat4 de l',italie1 tome #a41 p4 #bcc1 plate #g4 #h ,delesse1 sur les ,roches ,globuleuses1 ,mm4 de la ,soc4 ,gol4 de ,france1 #b sr41 tome iv4 #i ,scrope1 ,geol4 ,trans41 #bnd series1 vol4 ii1 p4 #bje4 #aj ,cambridge ,transactions1 vol4 i1 p4 #djb4 #aa ,ibid41 vol4 i1 p4 #daj4 #ab ,ibid41 vol4 ii1 p4 #age4 #ac ,dr4 ,berger1 ,geol4 ,trans41 #ast series1 vol4 iii1 p4 #agb4 #ad ,geol4 ,trans41 #ast series1 vol4 iii1 p4 #baj and plate #aj4 #ae ,ibid41 vol4 iii1 p4 #bac2 and ,playfair1 ,illus4 of ,hutt4 ,theory1 s4 #bec4 #af ,sedgwick1 ,camb4 ,trans41 vol4 ii1 p4 #cg47 #ag ,mac,culloch1 ,west4 ,islands1 vol4 ii1 p4 #dhg4 #ah ,syst4 of ,geol41 vol4 ii1 p4 #aad4 ,,chapter ,,xxix4 ,,on ,,the ,,ages ,,of ,,volcanic ,,rocks4 ,tests of relative ,age of ,volcanic ,rocks4 -- ,why ancient and modern ,rocks cannot be identical4 -- ,tests by ,superposition and intrusion4 -- ,test by ,alteration of ,rocks in ,contact4 -- ,test by ,organic ,remains4 -- ,test of ,age by ,mineral ,character4 -- ,test by ,included ,fragments4 -- ,recent and ,post-pliocene volcanic ,rocks4 -- ,vesuvius1 ,auvergne1 ,puy de ,cme1 and ,puy de ,pariou4 -- ,newer ,pliocene volcanic ,rocks4 -- ,cyclopean ,isles1 ,etna1 ,dikes of ,palagonia1 ,madeira4 -- ,older ,pliocene volcanic ,rocks4 -- ,italy4 -- ,pliocene ,volcanoes of the ,eifel4 -- ,trass4 ,having in the former part of this work referred the sedimentary strata to a long succession of geological periods1 we have now to consider how far the volcanic formations can be classed in a similar chronological order4 ,the tests of relative age in this class of rocks are four3 first1 superposition and intrusion1 with or without alteration of the rocks in contact2 second1 organic remains2 third1 mineral characters2 fourth1 included fragments of older rocks4 ,besides these four tests it may be said1 in a general way1 that volcanic rocks of ,primary or ,palozoic antiquity differ from those of the ,secondary or ,mesozoic age1 and these again from the ,tertiary and ,recent4 ,not1 perhaps1 that they differed originally in a greater degree than the modern volcanic rocks of one region1 such as that of the ,andes1 differ from those of another1 such as ,iceland1 but because all rocks permeated by water1 especially if its temperature be high1 are liable to undergo a slow transmutation1 even when they do not assume a new crystalline form like that of the hypogene rocks4 ,although subarial and submarine denudation1 as before stated1 remove1 in the course of ages1 large portions of the upper or more superficial products of volcanoes1 yet these are sometimes preserved by subsidence1 becoming covered by the sea or by superimposed marine deposits4 ,in this way they may be protected for ages from the waves of the sea1 or the destroying action of rivers1 while1 at the same time1 they may not sink so deep as to be exposed to that ,plutonic action 7to be spoken of in ,chapter ,,xxxi7 which would convert them into crystalline rocks4 ,but even in this case they will not remain unaltered1 because they will be percolated by water often of high temperature1 and charged with carbonate of lime1 silex1 iron1 and other mineral ingredients1 whereby gradual changes in the constitution of the rocks may be superinduced4 ,every geologist is aware how often silicified trees occur in volcanic tuffs1 the perfect preservation of their internal structure showing that they have not decayed before the petrifying material was supplied4 ,the porous and vesicular nature of a large part1 both of the basaltic and trachytic lavas1 affords cavities in which silex and carbonate of lime are readily deposited4 ,minerals of the zeolite family1 the composition of which has already been alluded to1 p4 #ejj1 occur in amygdaloids and other trap-rocks in great abundance1 and ,daubre's observations have proved that they are not always simple deposits of substances held in solution by the percolating waters1 being occasionally products of the chemical action of that water on the rock through which they are filtered1 and portions of which are decomposed4 ,from these considerations it follows that the perfect identity of very ancient and very modern volcanic formations is scarcely possible4 ,fig4 #eig3 ,showing melted matter forced between two strata4 ,tests by ,superposition4--,if a volcanic rock rest upon an aqueous deposit1 the volcanic must be the newest of the two2 but the like rule does not hold good where the aqueous formation rests upon the volcanic1 for melted matter1 rising from below1 may penetrate a sedimentary mass without reaching the surface1 or may be forced in conformably between two strata1 as b below ,d in ,fig4 #eig1 after which it may cool down and consolidate4 ,superposition1 therefore1 is not of the same value as a test of age in the unstratified volcanic rocks as in fossiliferous formations4 ,we can only rely implicitly on this test where the volcanic rocks are contemporaneous1 not where they are intrusive4 ,now1 they are said to be contemporaneous if produced by volcanic action which was going on simultaneously with the deposition of the strata with which they are associated4 ,thus in the section at ,d 7,fig4 #eig71 we may perhaps ascertain that the trap b flowed over the fossiliferous bed c1 and that1 after its consolidation1 a was deposited upon it1 a and c both belonging to the same geological period4 ,but1 on the other hand1 we must conclude the trap to be intrusive1 if the stratum a be altered by b at the point of contact1 or if1 in pursuing b for some distance1 we find at length that it cuts through the stratum a1 and then overlies it as at ,e4 ,fig4 #eih3 ,section through sedimentary mass with melted matter4 ,we may1 however1 be easily deceived in supposing the volcanic rock to be intrusive1 when in reality it is contemporaneous2 for a sheet of lava1 as it spreads over the bottom of the sea1 cannot rest everywhere upon the same stratum1 either because these have been denuded1 or because1 if newly thrown down1 they thin out in certain places1 thus allowing the lava to cross their edges4 ,besides1 the heavy igneous fluid will often1 as it moves along1 cut a channel into beds of soft mud and sand4 ,suppose the submarine lava ,f 7,fig4 #eih7 to have come in contact in this manner with the strata a1 b1 c1 and that after its consolidation the strata d1 e are thrown down in a nearly horizontal position1 yet so as to lie unconformably to ,f1 the appearance of subsequent intrusion will here be complete1 although the trap is in fact contemporaneous4 ,we must not1 therefore1 hastily infer that the rock ,f is intrusive1 unless we find the overlying strata1 d1 e1 to have been altered at their junction1 as if by heat4 ,the test of age by superposition is strictly applicable to all stratified volcanic tuffs1 according to the rules already explained in the case of sedimentary deposits 7see p4 #abd74 ,test of ,age by ,organic ,remains4--,we have seen how1 in the vicinity of active volcanoes1 scori1 pumice1 fine sand1 and fragments of rock are thrown up into the air1 and then showered down upon the land1 or into neighbouring lakes or seas4 ,in the tuffs so formed shells1 corals1 or any other durable organic bodies which may happen to be strewed over the bottom of a lake or sea will be imbedded1 and thus continue as permanent memorials of the geological period when the volcanic eruption occurred4 ,tufaceous strata thus formed in the neighbourhood of ,vesuvius1 ,etna1 ,stromboli1 and other volcanoes now in islands or near the sea1 may give information of the relative age of these tuffs at some remote future period when the fires of these mountains are extinguished4 ,by evidence of this kind we can establish a coincidence in age between volcanic rocks and the different primary1 secondary1 and tertiary fossiliferous strata4 ,the tuffs alluded to may not always be marine1 but may include1 in some places1 fresh-water shells2 in others1 the bones of terrestrial quadrupeds4 ,the diversity of organic remains in formations of this nature is perfectly intelligible1 if we reflect on the wide dispersion of ejected matter during late eruptions1 such as that of the volcano of ,coseguina1 in the province of ,nicaragua1 ,january #ai1 #ahce4 ,hot cinders and fine scori were then cast up to a vast height1 and covered the ground as they fell to the depth of more than ten feet1 for a distance of eight leagues from the crater1 in a southerly direction4 ,birds1 cattle1 and wild animals were scorched to death in great numbers1 and buried in ashes4 ,some volcanic dust fell at ,chiapa1 upward of #abjj miles1 not to leeward of the volcano1 as might have been anticipated1 but to windward1 a striking proof of a counter-current in the upper region of the atmosphere2 and some on ,jamaica1 about #gjj miles distant to the north-east4 ,in the sea1 also1 at the distance of #aajj miles from the point of eruption1 ,captain ,eden of the 8,conway0 sailed #dj miles through floating pumice1 among which were some pieces of considerable size4#a ,test of ,age by ,mineral ,composition4--,as sediment of homogeneous composition1 when discharged from the mouth of a large river1 is often deposited simultaneously over a wide space1 so a particular kind of lava flowing from a crater during one eruption may spread over an extensive area2 thus in ,iceland1 in #aghc1 the melted matter1 pouring from ,skaptar ,jokul1 flowed in streams in opposite directions1 and caused a continuous mass the extreme points of which were #ij miles distant from each other4 ,this enormous current of lava varied in thickness from #ajj feet to #fjj feet1 and in breadth from that of a narrow river gorge to #ae miles4#b ,now1 if such a mass should afterwards be divided into separate fragments by denudation1 we might still1 perhaps1 identify the detached portions by their similarity in mineral composition4 ,nevertheless1 this test will not always avail the geologist2 for1 although there is usually a prevailing character in lava emitted during the same eruption1 and even in the successive currents flowing from the same volcano1 still1 in many cases1 the different parts even of one lava-stream1 or1 as before stated1 of one continuous mass of trap1 vary much in mineral composition and texture4 ,in ,auvergne1 the ,eifel1 and other countries where trachyte and basalt are both present1 the trachytic rocks are for the most part older than the basaltic4 ,these rocks do1 indeed1 sometimes alternate partially1 as in the volcano of ,mont ,dor1 in ,auvergne2 and in ,madeira trachytic rocks overlie an older basaltic series2 but the trachyte occupies more generally an inferior position1 and is cut through and overflowed by basalt4 ,it can by no means be inferred that trachyte predominated at one period of the earth's history and basalt at another1 for we know that trachytic lavas have been formed at many successive periods1 and are still emitted from many active craters2 but it seems that in each region1 where a long series of eruptions have occurred1 the lavas containing feldspar more rich in silica have been first emitted1 and the escape of the more augitic kinds has followed4 ,the hypothesis suggested by ,mr4 ,scrope may1 perhaps1 afford a solution of this problem4 ,the minerals1 he observes1 which abound in basalt are of greater specific gravity than those composing the feldspathic lavas2 thus1 for example1 hornblende1 augite1 and olivine are each more than three times the weight of water2 whereas common feldspar and albite have each scarcely more than #b times the specific gravity of water2 and the difference is increased in consequence of there being much more iron in a metallic state in basalt and greenstone than in trachyte and other allied feldspathic lavas4 ,if1 therefore1 a large quantity of rock be melted up in the bowels of the earth by volcanic heat1 the denser ingredients of the boiling fluid may sink to the bottom1 and the lighter remaining above would in that case be first propelled upward to the surface by the expansive power of gases4 ,those materials1 therefore1 which occupy the lowest place in the subterranean reservoir will always be emitted last1 and take the uppermost place on the exterior of the earth's crust4 ,test by ,included ,fragments4--,we may sometimes discover the relative age of two trap-rocks1 or of an aqueous deposit and the trap on which it rests1 by finding fragments of one included in the other in cases such as those before alluded to1 where the evidence of superposition alone would be insufficient4 ,it is also not uncommon to find a conglomerate almost exclusively composed of rolled pebbles of trap1 associated with some fossiliferous stratified formation in the neighbourhood of massive trap4 ,if the pebbles agree generally in mineral character with the latter1 we are then enabled to determine its relative age by knowing that of the fossiliferous strata associated with the conglomerate4 ,the origin of such conglomerates is explained by observing the shingle beaches composed of trap-pebbles in modern volcanoes1 as at the base of ,etna4 ,recent and ,post-pliocene ,volcanic ,rocks4--,i shall now select examples of contemporaneous volcanic rocks of successive geological periods1 to show that igneous causes have been in activity in all past ages of the world4 ,they have been perpetually shifting the places where they have broken out at the earth's surface1 and we can sometimes prove that those areas which are now the great theatres of volcanic action were in a state of perfect tranquillity at remote geological epochs1 and that1 on the other hand1 in places where at former periods the most violent eruptions took place at the surface and continued for a great length of time1 there has been an entire suspension of igneous action in historical times1 and even1 as in the ,british ,isles1 throughout a large part of the antecedent ,tertiary ,period4 ,in the absence of ,british examples of volcanic rocks newer than the ,upper ,miocene1 ,i may state that in other parts of the world1 especially in those where volcanic eruptions are now taking place from time to time1 there are tuffs and lavas belonging to that part of the ,tertiary era the antiquity of which is proved by the presence of the bones of extinct quadrupeds which co-existed with terrestrial1 fresh-water1 and marine mollusca of species still living4 ,one portion of the lavas1 tuffs1 and trap-dikes of ,etna1 ,vesuvius1 and the island of ,ischia has been produced within the historical era2 another and a far more considerable part originated at times immediately antecedent1 when the waters of the ,mediterranean were already inhabited by the existing testacea1 but when certain species of elephant1 rhinoceros1 and other quadrupeds now extinct1 inhabited ,europe4 ,vesuvius4--,i have traced in the 8,principles of ,geology0 the history of the changes which the volcanic region of ,campania is known to have undergone during the last #bjjj years4 ,the aggregate effect of igneous operations during that period is far from insignificant1 comprising as it does the formation of the modern cone of ,vesuvius since the year #gi1 and the production of several minor cones in ,ischia1 together with that of ,monte ,nuovo in the year #aech4 ,lava-currents have also flowed upon the land and along the bottom of the sea--volcanic sand1 pumice1 and scori have been showered down so abundantly that whole cities were buried--tracts of the sea have been filled up or converted into shoals--and tufaceous sediment has been transported by rivers and land-floods to the sea4 ,there are also proofs1 during the same recent period1 of a permanent alteration of the relative levels of the land and sea in several places1 and of the same tract having1 near ,puzzuoli1 been alternately upheaved and depressed to the amount of more than twenty feet4 ,in connection with these convulsions1 there are found1 on the shores of the ,bay of ,bai1 recent tufaceous strata1 filled with articles fabricated by the hands of man1 and mingled with marine shells4 ,it has also been stated 7p4 #bjf71 that when we examine this same region1 it is found to consist largely of tufaceous strata1 of a date anterior to human history or tradition1 which are of such thickness as to constitute hills from #ejj to more than #bjjj feet in height4 ,some of these strata contain marine shells which are exclusively of living species1 others contain a slight mixture1 one or two per cent of species not known as living4 ,the ancient part of ,vesuvius is called ,somma1 and consists of the remains of an older cone which appears to have been partly destroyed by explosion4 ,in the great escarpment which this remnant of the ancient mountain presents towards the modern cone of ,vesuvius1 there are many dikes which are for the most part vertical1 and traverse the inclined beds of lava and scori which were successively superimposed during those eruptions by which the old cone was formed4 ,they project in relief several inches1 or sometimes feet1 from the face of the cliff1 being extremely compact1 and less destructible than the intersected tuffs and porous lavas4 ,in vertical extent they vary from a few yards to #ejj feet1 and in breadth from one to twelve feet4 ,many of them cut all the inclined beds in the escarpment of ,somma from top to bottom1 others stop short before they ascend above halfway4 ,in mineral composition they scarcely differ from the lavas of ,somma1 the rock consisting of a base of leucite and augite1 through which large crystals of augite and some of leucite are scattered4 ,nothing is more remarkable than the usual parallelism of the opposite sides of the dikes1 which correspond almost as regularly as the two opposite faces of a wall of masonry4 ,this character appears at first the more inexplicable1 when we consider how jagged and uneven are the rents caused by earthquakes in masses of heterogeneous composition1 like those composing the cone of ,somma4 ,in explanation of this phenomenon1 ,m4 ,necker refers us to ,sir ,w4 ,hamilton's account of an eruption of ,vesuvius in the year #aggi1 who records the following fact3 8,the lavas1 when they either boiled over the crater1 or broke out from the conical parts of the volcano1 constantly formed channels as regular as if they had been cut by art down the steep part of the mountain2 and whilst in a state of perfect fusion1 continued their course in those channels1 which were sometimes full to the brim1 and at other times more or less so1 according to the quantity of matter in motion4 0,these channels 7says the same observer71 ,i have found1 upon examination after an eruption1 to be in general from two to five or six feet wide1 and seven or eight feet deep4 ,they were often hid from the sight by a quantity of scori that had formed a crust over them2 and the lava1 having been conveyed in a covered way for some yards1 came out fresh again into an open channel4 ,after an eruption1 ,i have walked in some of those subterraneous or covered galleries1 which were exceedingly curious1 the sides1 top1 and bottom being worn perfectly smooth and even in most parts by the violence of the currents of the red-hot lavas which they had conveyed for many weeks successively40 ,i was able to verify this phenomenon in #aheh1 when a stream of lava issued from a lateral cone4#c ,now1 the walls of a vertical fissure1 through which lava has ascended in its way to a volcanic vent1 must have been exposed to the same erosion as the sides of the channels before adverted to4 ,the prolonged and uniform friction of the heavy fluid1 as it is forced and made to flow upward1 cannot fail to wear and smooth down the surfaces on which it rubs1 and the intense heat must melt all such masses as project and obstruct the passage of the incandescent fluid4 ,the rock composing the dikes both in the modern and ancient part of ,vesuvius is far more compact than that of ordinary lava1 for the pressure of a column of melted matter in a fissure greatly exceeds that in an ordinary stream of lava2 and pressure checks the expansion of those gases which give rise to vesicles in lava4 ,there is a tendency in almost all the ,vesuvian dikes to divide into horizontal prisms1 a phenomenon in accordance with the formation of vertical columns in horizontal beds of lava2 for in both cases the divisions which give rise to the prismatic structure are at right angles to the cooling surfaces4 7,see p4 #eaj47 ,auvergne4--,although the latest eruptions in central ,france seem to have long preceded the historical era1 they are so modern as to have a very intimate connection with the present superficial outline of the country and with the existing valleys and river-courses4 ,among a great number of cones with perfect craters1 one called the ,puy de ,tartaret sent forth a lava-current which can be traced up to its crater1 and which flowed for a distance of thirteen miles along the bottom of the present valley to the village of ,nechers1 covering the alluvium of the old valley in which were preserved the bones of an extinct species of horse1 and of a lagomys and other quadrupeds all closely allied to recent animals1 while the associated land-shells were of species now living1 such as ,cyclostoma elegans1 ,helix hortensis1 ,h4 nemoralis1 ,h4 lapicida1 and ,clausilia rugosa4 ,that the current which has issued from the ,puy de ,tartaret may1 nevertheless1 be very ancient in reference to the events of human history1 we may conclude1 not only from the divergence of the mammiferous fauna from that of our day1 but from the fact that a ,roman bridge of such form and construction as continued in use only down to the fifth century1 but which may be older1 is now seen at a place about a mile and a half from ,st4 ,nectaire4 ,this ancient bridge spans the river ,couze with two arches1 each about fourteen feet wide4 ,these arches spring from the lava of ,tartaret1 on both banks1 showing that a ravine precisely like that now existing had already been excavated by the river through that lava thirteen or fourteen centuries ago4 ,while the river ,couze has in most cases1 as at the site of this ancient bridge1 been simply able to cut a deep channel through the lava1 the lower portion of which is shown to be columnar1 the same torrent has in other places1 where the valley was contracted to a narrow gorge1 had power to remove the entire mass of basaltic rock1 causing for a short space a complete breach of continuity in the volcanic current4 ,the work of erosion has been very slow1 as the basalt is tough and hard1 and one column after another must have been undermined and reduced to pebbles1 and then to sand4 ,during the time required for this operation1 the perishable cone of ,tartaret1 occupying the lowest part of the great valley descending from ,mont ,dor 7see p4 #edb71 and damming up the river so as to cause the ,lake of ,chambon1 has stood uninjured1 proving that no great flood or deluge can have passed over this region in the interval between the eruption of ,tartaret and our own times4 ,puy de ,cme4--,the ,puy de ,cme and its lava-current1 near ,clermont1 may be mentioned as another minor volcano of about the same age4 ,this conical hill rises from the granitic platform1 at an angle of between #cj and #dj1 to the height of more than #ijj feet4 ,its summit presents two distinct craters1 one of them with a vertical depth of #bej feet4 ,a stream of lava takes its rise at the western base of the hill instead of issuing from either crater1 and descends the granitic slope towards the present site of the town of ,pont ,gibaud4 ,thence it pours in a broad sheet down a steep declivity into the valley of the ,sioule1 filling the ancient river-channel for the distance of more than a mile4 ,the ,sioule1 thus dispossessed of its bed1 has worked out a fresh one between the lava and the granite of its western bank2 and the excavation has disclosed1 in one spot1 a wall of columnar basalt about fifty feet high4#d ,the excavation of the ravine is still in progress1 every winter some columns of basalt being undermined and carried down the channel of the river1 and in the course of a few miles rolled to sand and pebbles4 ,meanwhile the cone of ,cme remains unimpaired1 its loose materials being protected by a dense vegetation1 and the hill standing on a ridge not commanded by any higher ground1 so that no floods of rain-water can descend upon it4 ,there is no end to the waste which the hard basalt may undergo in future1 if the physical geography of the country continue unchanged--no limit to the number of years during which the heap of incoherent and transportable materials called the ,puy de ,cme may remain in an almost stationary condition4 ,puy de ,pariou4--,the brim of the crater of the ,puy de ,pariou1 near ,clermont1 is so sharp1 and has been so little blunted by time1 that it scarcely affords room to stand upon4 ,this and other cones in an equally remarkable state of integrity have stood1 ,i conceive1 uninjured1 not in spite of their loose porous nature1 as might at first be naturally supposed1 but in consequence of it4 ,no rills can collect where all the rain is instantly absorbed by the sand and scori1 as is remarkably the case on ,etna2 and nothing but a water-spout breaking directly upon the ,puy de ,pariou could carry away a portion of the hill1 so long as it is not rent or ingulfed by earthquakes4 ,newer ,pliocene ,volcanic ,rocks4--,the more ancient portion of ,vesuvius and ,etna originated at the close of the ,newer ,pliocene period1 when less than ten1 sometimes only one1 in a hundred of the shells differed from those now living4 ,in the case of ,etna1 it was before stated 7p4 #bje7 that ,post-pliocene formations occur in the neighbourhood of ,catania1 while the oldest lavas of the great volcano are ,pliocene4 ,these last are seen associated with sedimentary deposits at ,trezza and other places on the southern and eastern flanks of the great cone 7see p4 #bje74 ,cyclopean ,islands4--,the ,cyclopean ,islands1 called by the ,sicilians ,dei ,faraglioni1 in the sea-cliffs of which these beds of clay1 tuff1 and associated lava are laid open to view1 are situated in the ,bay of ,trezza1 and may be regarded as the extremity of a promontory severed from the main land4 ,here numerous proofs are seen of submarine eruptions1 by which the argillaceous and sandy strata were invaded and cut through1 and tufaceous breccias formed4 ,inclosed in these breccias are many angular and hardened fragments of laminated clay in different states of alteration by heat1 and intermixed with volcanic sands4 ,fig4 #eii3 ,view of the ,isle of ,cyclops1 in the ,bay of ,trezza4 ,the loftiest of the ,cyclopean islets1 or rather rocks1 is about #bjj feet in height1 the summit being formed of a mass of stratified clay1 the lamin of which are occasionally subdivided by thin arenaceous layers4 ,these strata dip to the ,n4,w41 and rest on a mass of columnar lava 7see ,fig4 #eii7 in which the tops of the pillars are weathered1 and so rounded as to be often hemispherical4 ,fig4 #fjj3 ,contortions of strata in the largest of the ,cyclopean ,islands4 ,in some places in the adjoining and largest islet of the group1 which lies to the north-eastward of that represented in ,figure #eii71 the overlying clay has been greatly altered and hardened by the igneous rock1 and occasionally contorted in the most extraordinary manner2 yet the lamination has not been obliterated1 but1 on the contrary1 rendered much more conspicuous1 by the indurating process4 ,in ,fig4 #fjj ,i have represented a portion of the altered rock1 a few feet square1 where the alternating thin lamin of sand and clay are contorted in a manner often observed in ancient metamorphic schists4 ,a great fissure1 running from east to west1 nearly divides this larger island into two parts1 and lays open its internal structure4 ,in the section thus exhibited1 a dike of lava is seen1 first cutting through an older mass of lava1 and then penetrating the superincumbent tertiary strata4 ,in one place the lava ramifies and terminates in thin veins1 from a few feet to a few inches in thickness 7see ,fig4 #fja74 ,the arenaceous lamin are much hardened at the point of contact1 and the clays are converted into siliceous schist4 ,in this island the altered rocks assume a honey-comb structure on their weathered surface1 singularly contrasted with the smooth and even outline which the same beds present in their usual soft and yielding state4 ,the pores of the lava are sometimes coated1 or entirely filled with carbonate of lime1 and with a zeolite resembling analcime1 which has been called cyclopite4 ,the latter mineral has also been found in small fissures traversing the altered marl1 showing that the same cause which introduced the minerals into the cavities of the lava1 whether we suppose sublimation or aqueous infiltration1 conveyed it also into the open rents of the contiguous sedimentary strata4 ,fig4 #fja3 ,newer pliocene strata invaded by lava4 ,isle of ,cyclops 7horizontal section74 ,dikes of ,palagonia4--,dikes of vesicular and amygdaloidal lava are also seen traversing marine tuff or peperino1 west of ,palagonia1 some of the pores of the lava being empty1 while others are filled with carbonate of lime4 ,in such cases we may suppose the tuff to have resulted from showers of volcanic sand and scori1 together with fragments of limestone1 thrown out by a submarine explosion1 similar to that which gave rise to ,graham ,island in #ahca4 ,when the mass was1 to a certain degree1 consolidated1 it may have been rent open1 so that the lava ascended through fissures1 the walls of which were perfectly even and parallel4 ,in one case1 after the melted matter that filled the rent 7,fig4 #fjb7 had cooled down1 it must have been fractured and shifted horizontally by a lateral movement4 ,in ,fig4 #fjc1 the lava has more the appearance of a vein1 which forced its way through the peperino4 ,it is highly probable that similar appearances would be seen1 if we could examine the floor of the sea in that part of the ,mediterranean where the waves have recently washed away the new volcanic island2 for when a superincumbent mass of ejected fragments has been removed by denudation1 we may expect to see sections of dikes traversing tuff1 or1 in other words1 sections of the channels of communication by which the subterranean lavas reached the surface4 ,figs4 #fjb and #fjc3 ,ground-plan of dikes near ,palagonia4 ,madeira4--,although the more ancient portion of the volcanic eruptions by which the island of ,madeira and the neighbouring one of ,porto ,santo were built up occurred1 as we shall presently see1 in the ,upper ,miocene ,period1 a still larger part of the island is of ,pliocene date4 ,that the latest outbreaks belonged to the ,newer ,pliocene ,period1 ,i infer from the close affinity to the present flora of ,madeira of the fossil plants preserved in a leaf-bed in the north-eastern part of the island4 ,these fossils1 associated with some lignite in the ravine of the river ,san ,jorge1 can none of them be proved to be of extinct species1 but their antiquity may be inferred from the following considerations3 ,firstly--,the leaf-bed1 discovered by ,mr4 ,hartung and myself in #ahec1 at the height of #ajjj feet above the level of the sea1 crops out at the base of a cliff formed by the erosion of a gorge cut through alternating layers of basalt and scori1 the product of a vast succession of eruptions of unknown date1 piled up to a thickness of #ajjj feet1 and which were all poured out after the plants1 of which about twenty species have been recognised1 flourished in ,madeira4 ,these lavas are inclined at an angle of about #ae to the north1 and came down from the great central region of eruption4 ,their accumulation implies a long period of intermittent volcanic action1 subsequently to which the ravine of ,san ,jorge was hollowed out4 ,secondly--,some few of the plants1 though perhaps all of living species1 are supposed to be of genera not now existing in the island4 ,they have been described by ,sir ,charles ,bunbury and ,professor ,heer1 and the former first pointed out that many of the leaves are of the laurel type1 and analogous to those now flourishing in the modern forests of ,madeira4 ,he also recognised among them the leaves of ,woodwardia radicans1 and ,davallia ,canariensis1 ferns now abundant in ,madeira4 ,thirdly--the great age of this leaf-bed of ,san ,jorge1 which was perhaps originally formed in the crater of some ancient volcanic cone afterwards buried under lava1 is proved by its belonging to a part of the eastern extremity of ,madeira1 which1 after the close of the igneous eruptions1 became covered in the adjoining district of ,canial with blown sand in which a vast number of land-shells were buried4 ,these fossil shells belonged to no less than #cf species1 among which are many now extremely rare in the island1 and others1 about five per cent1 extinct or unknown in any part of the world4 ,several of these of the genus ,helix are conspicuous from the peculiarity of their forms1 others from their large dimensions4 ,the geographical configuration of the country shows that this shell-bed is considerably more modern than the leaf-bed2 it must therefore be referred to the ,newer ,pliocene1 according to the definition of this period given in a former chapter 7p4 #adc74 ,older ,pliocene ,period4--,italy4--,in ,tuscany1 as at ,radicofani1 ,viterbo1 and ,aquapendente1 and in the ,campagna di ,roma1 submarine volcanic tuffs are interstratified with the ,older ,pliocene strata of the ,sub-apennine hills in such a manner as to leave no doubt that they were the products of eruptions which occurred when the shelly marls and sands of the ,sub-appenine hills were in the course of deposition4 ,this opinion ,i expressed#e after my visit to ,italy in #ahbh and it has recently 7#ahej7 been confirmed by the argument adduced by ,sir ,r4 ,murchison in favour of the submarine origin of the tertiary volcanic rocks of ,italy4#f ,these rocks are well-known to rest conformably on the ,sub-apennine marls1 even as far south as ,monte ,mario1 in the suburbs of ,rome4 ,on the exact age of the deposits of ,monte ,mario new light has recently been thrown by a careful study of their marine fossil shells1 undertaken by ,,mm4 ,rayneval1 ,van den ,hecke1 and ,ponzi4 ,they have compared no less than #afj species with the shells of the ,coralline ,crag of ,suffolk1 so well described by ,mr4 ,searles ,wood2 and the specific agreement between the ,british and ,italian fossils is so great1 if we make due allowance for geographical distance and the difference of latitude1 that we can have little hesitation in referring both to the same period1 or to the ,older ,pliocene of this work4 ,it is highly probable that1 between the oldest trachytes of ,tuscany and the newest rocks in the neighbourhood of ,naples1 a series of volcanic products might be detected of every age from the ,older ,pliocene to the historical epoch4 ,pliocene ,volcanoes of the ,eifel4--,some of the most perfect cones and craters in ,europe1 not even excepting those of the district round ,vesuvius1 may be seen on the left or west bank of the ,rhine1 near ,bonn and ,andernach4 ,they exhibit characters distinct from any which ,i have observed elsewhere1 owing to the large part which the escape of aqueous vapour has played in the eruptions and the small quantities of lava emitted4 ,the fundamental rocks of the district are grey and red sandstones and shales1 with some associated limestones1 replete with fossils of the ,devonian or ,old ,red ,sandstone group4 ,the volcanoes broke out in the midst of these inclined strata1 and when the present systems of hills and valleys had already been formed4 ,the eruptions occurred sometimes at the bottom of deep valleys1 sometimes on the summit of hills1 and frequently on intervening platforms4 ,in travelling through this district we often come upon them most unexpectedly1 and may find ourselves on the very edge of a crater before we had been led to suspect that we were approaching the site of any igneous outburst4 ,thus1 for example1 on arriving at the village of ,gemund1 immediately south of ,daun1 we leave the stream1 which flows at the bottom of a deep valley in which strata of sandstone and shale crop out4 ,we then climb a steep hill1 on the surface of which we see the edges of the same strata dipping inward towards the mountain4 ,when we have ascended to a considerable height1 we see fragments of scori sparingly scattered over the surface2 until at length1 on reaching the summit1 we find ourselves suddenly on the edge of a tarn1 or deep circular lake-basin called the ,gemunder ,maar4 ,in it we recognise the ordinary form of a crater1 for which we have been prepared by the occurrence of scori scattered over the surface of the soil4 ,but on examining the walls of the crater we find precipices of sandstone and shale which exhibit no signs of the action of heat2 and we look in vain for those beds of lava and scori1 dipping outward on every side1 which we have been accustomed to consider as characteristic of volcanic vents4 ,as we proceed1 however1 to the opposite side of the lake1 we find a considerable quantity of scori and some lava1 and see the whole surface of the soil sparkling with volcanic sand1 and strewed with ejected fragments of half-fused shale1 which preserves its laminated texture in the interior1 while it has a vitrified or scoriform coating4 ,other crater lakes of circular or oval form1 and hollowed out of similar ancient strata1 occur in the ,upper ,eifel1 where copious ariform discharges have taken place1 throwing out vast heaps of pulverized shale into the air4 ,i know of no other extinct volcanoes where gaseous explosions of such magnitude have been attended by the emission of so small a quantity of lava4 ,yet ,i looked in vain in the ,eifel for any appearances which could lend support to the hypothesis that the sudden rushing out of such enormous volumes of gas had ever lifted up the stratified rocks immediately around the vent so as to form conical masses1 having their strata dipping outward on all sides from a central axis1 as is assumed in the theory of elevation craters1 alluded to in the last chapter4 ,i have already given 7,fig4 #eij7 an example in the ,eifel of a small stream of lava which issued from one of the craters of that district at ,bertrich-,baden4 ,it shows that when some of these volcanoes were in action the valleys had already been eroded to their present depth4 ,trass4--,the tufaceous alluvium called trass1 which has covered large areas in the ,eifel1 and choked up some valleys now partially re-excavated1 is unstratified4 ,its base consists almost entirely of pumice1 in which are included fragments of basalt and other lavas1 pieces of burnt shale1 slate1 and sandstone1 and numerous trunks and branches of trees4 ,if1 as is probable1 this trass was formed during the period of volcanic eruptions1 it may have originated in the manner of the moya of the ,andes4 ,we may easily conceive that a similar mass might now be produced1 if a copious evolution of gases should occur in one of the lake-basins4 ,if a breach should be made in the side of the cone1 the flood would sweep away great heaps of ejected fragments of shale and sandstone1 which would be borne down into the adjoining valleys4 ,forests might be torn up by such a flood1 and thus the occurrence of the numerous trunks of trees dispersed irregularly through the trass can be explained4 ,the manner in which this trass conforms to the shape of the present valleys implies its comparatively modern origin1 probably not dating farther back than the ,pliocene ,period4 #a ,caldcleugh1 ,phil4 ,trans41 #ahcf1 p4 #bg4 #b ,see ,principles1 ,index1 8,skaptar ,jokul40 #c ,principles of ,geology1 vol4 i1 p4 #fbf4 #d ,scrope's ,central ,france1 p4 #fj1 and plate4 #e ,see #ast edit4 of ,principles of ,geology1 vol4 iii1 chaps4 xiii and xiv1 #ahcc2 and former editions of this work1 chap4 xxxi4 #f ,quart4 ,geol4 ,journ41 vol4 vi1 p4 #bha4 ,,chapter ,,xxx4 ,,age ,,of ,,volcanic ,,rocks--continued4 ,volcanic ,rocks of the ,upper ,miocene ,period4 -- ,madeira4 -- ,grand ,canary4 -- ,azores4 -- ,lower ,miocene ,volcanic ,rocks4 -- ,isle of ,mull4 -- ,staffa and ,antrim4 -- ,the ,eifel4 -- ,upper and ,lower ,miocene ,volcanic ,rocks of ,auvergne4 -- ,hill of ,gergovia4 -- ,eocene ,volcanic ,rocks of ,monte ,bolca4 -- ,trap of ,cretaceous ,period4 -- ,oolitic ,period4 -- ,triassic ,period4 -- ,permian ,period4 -- ,carboniferous ,period4 -- ,erect ,trees buried in ,volcanic ,ash in the ,island of ,arran4 -- ,old ,red ,sandstone ,period4 -- ,silurian ,period4 -- ,cambrian ,period4 -- ,laurentian ,volcanic ,rocks4 ,volcanic ,rocks of the ,upper ,miocene ,period4--,madeira4--,the greater part of the volcanic eruptions of ,madeira1 as we have already seen 7p4 #ecb71 belong to the ,pliocene ,period1 but the most ancient of them are of ,upper ,miocene date1 as shown by the fossil shells included in the marine tuffs which have been upraised at ,san ,vicente1 in the northern part of the island1 to the height of #acjj feet above the level of the sea4 ,a similar marine and volcanic formation constitutes the fundamental portion of the neighbouring island of ,porto ,santo1 forty miles distant from ,madeira1 and is there elevated to an equal height1 and covered1 as in ,madeira1 with lavas of supra-marine origin4 ,the largest number of fossils have been collected from the tuffs and conglomerates and some beds of limestone in the island of ,baixo1 off the southern extremity of ,porto ,santo4 ,they amount in this single locality to more than sixty in number1 of which about fifty are mollusca1 but many of these are only casts4 ,some of the shells probably lived on the spot during the intervals between eruptions1 and some may have been cast up into the water or air together with muddy ejections1 and1 falling down again1 have been deposited on the bottom of the sea4 ,the hollows in some of the fragments of vesicular lava of which the breccias and conglomerates are composed are partially filled with calc-sinter1 being thus half converted into amygdaloids4 ,among the fossil shells common to ,madeira and ,porto ,santo1 large cones1 strombs1 and cowries are conspicuous among the univalves1 and ,cardium1 ,spondylus1 and ,lithodomus among the lamellibranchiate bivalves1 and among the ,echinoderms the large ,clypeaster called ,c4 altus1 an extinct ,european ,miocene fossil4 ,the largest list of fossils has been published by ,mr4 ,karl ,meyer1 in ,hartung's 8,madeira20 but in the collection made by myself1 and in a still larger one formed by ,mr4 ,j4 ,yate ,johnson1 several remarkable forms not in ,meyer's list occur1 as1 for example1 ,pholadomya1 and a large ,terebra4 ,mr4 ,johnson also found a fine specimen of ,nautilus 7,atruria7 ziczac 7,fig4 #baa71 a well-known ,falunian fossil of ,europe2 and in the same volcanic tuff of ,baixo1 the ,echinoderm ,brissus ,scill1 a living ,mediterranean species1 found fossil in the ,miocene strata of ,malta4 ,mr4 ,meyer identifies one-third of the ,madeira shells with known ,european ,miocene 7or ,falunian7 forms4 ,the huge ,strombus of ,san ,vicente and ,porto ,santo1 ,s4 ,italicus1 is an extinct shell of the ,sub-apennine or ,older ,pliocene formations4 ,the mollusca already obtained from various localities of ,madeira and ,porto ,santo are not less than one hundred in number1 and1 according to the late ,dr4 ,s4 ,p4 ,woodward1 rather more than a third are of species still living1 but many of these are not now inhabitants of the neighbouring sea4 ,it has been remarked 7p4 #bab71 that in the ,older ,pliocene and ,upper ,miocene deposits of ,europe many forms occur of a more southern aspect than those now inhabiting the nearest sea4 ,in like manner the fossil corals1 or ,zoantharia1 six in number1 which ,i obtained from ,madeira1 of the genera ,astra1 ,sarcinula1 ,hydnophora1 were pronounced by ,mr4 ,lonsdale to be forms foreign to the adjacent coasts1 and agreeing with the fauna of a sea warmer than that now separating ,madeira from the nearest part of the ,african coast4 ,we learn1 indeed1 from the observations made in #ahei1 by the ,reverend ,r4 ,t4 ,lowe1 that more than one-half1 or fifty-three in ninety1 of the marine mollusks collected by him from the sandy beach of ,mogador are common ,british species1 although ,mogador is #ah degrees south of the nearest shores of ,england4 ,the living shells of ,madeira and ,porto ,santo are in like manner those of a temperate climate1 although in great part differing specifically from those of ,mogador4#a ,grand ,canary4--,in the ,canaries1 especially in the ,grand ,canary1 the same marine ,upper ,miocene formation is found4 ,stratified tuffs1 with intercalated conglomerates and lavas1 are there seen in nearly horizontal layers in sea-cliffs about #cjj feet high1 near ,las ,palmas4 ,mr4 ,hartung and ,i were unable to find marine shells in these tuffs at a greater elevation than #djj feet above the sea2 but as the deposit to which they belong reaches to the height of #aajj feet or more in the interior1 we conceive that an upheaval of at least that amount has taken place4 ,the ,clypeaster altus1 ,spondylus gderopus1 ,pectunculus pilosus1 ,cardita calyculata1 and several other shells1 serve to identify this formation with that of the ,madeiras1 and ,ancillaria glandiformis1 which is not rare1 and some other fossils1 remind us of the faluns of ,touraine4 ,the sixty-two ,miocene species which ,i collected in the ,grand ,canary were referred by the late ,dr4 ,s4 ,p4 ,woodward to forty-seven genera1 ten of which are no longer represented in the neighbouring sea1 namely ,corbis1 an ,african form1 ,hinnites1 now living in ,oregon1 ,thecidium 7,t4 ,mediterranean1 identical with the ,miocene fossil of ,st4 ,juvat1 in ,brittany71 ,calyptra1 ,hipponyx1 ,nerita1 ,erato1 ,oliva1 ,ancillaria1 and ,fasciolaria4 ,these tuffs of the southern shores of the ,grand ,canary1 containing the ,upper ,miocene shells1 appear to be about the same age as the most ancient volcanic rocks of the island1 composed of slaty diabase1 phonolite1 and trachyte4 ,over the marine lavas and tuffs trachytic and basaltic products of subarial volcanic origin1 between #djjj and #ejjj feet in thickness1 have been piled1 the central parts of the ,grand ,canary reaching the height of about #fjjj feet above the level of the sea4 ,a large portion of this mass is of ,pliocene date1 and some of the latest lavas have been poured out since the time when the valleys were already excavated to within a few feet of their present depth4 ,on the whole1 the rocks of the ,grand ,canary1 an island of a nearly circular shape1 and #f geographical miles diameter1 exhibit proofs of a long series of eruptions beginning like those of ,madeira1 ,porto ,santo1 and the ,azores1 in the ,upper ,miocene period1 and continued to the ,post-,pliocene4 ,the building up of the ,grand ,canary by subarial eruptions1 several thousand feet thick1 went on simultaneously with the gradual upheaval of the earliest products of submarine eruptions1 in the same manner as the ,pliocene marine strata of the oldest parts of ,vesuvius and ,etna have been upraised during eruptions of ,post-tertiary date4 ,in proof that movements of elevation have actually continued down to ,post-tertiary times1 ,i may remark that ,i found raised beaches containing shells of the ,recent ,period in the ,grand ,canary1 ,teneriffe1 and ,porto ,santo4 ,the most remarkable raised beach which ,i observed in the ,grand ,canary1 in the study of which ,i was assisted by ,don ,pedro ,maffiotte1 is situated in the north-eastern part of the island at ,san ,catalina1 about a quarter of a mile north of ,las ,palmas4 ,it intervenes between the base of the high cliff formed of the tuffs with ,miocene shells and the sea-shore4 ,from this beach1 at an elevation of twenty-five feet above high-water mark1 and at a distance of about #aej feet from the present shore1 ,i obtained more than fifty species of living marine shells4 ,many of them1 according to ,dr4 ,s4 ,p4 ,woodward1 are no longer inhabitants of the contiguous sea1 as1 for example1 ,strombus bubonius1 which is still living on the ,west ,coast of ,africa1 and ,cerithium procerum1 found at ,mozambique2 others are ,mediterranean species1 as ,pecten ,jacobus and ,p4 polymorphus4 ,some of these testacea1 such as ,cardita squamosa1 are inhabitants of deep water1 and the deposit on the whole seems to indicate a depth of water exceeding a hundred feet4 ,azores4--,in the island of ,st4 ,mary's1 one of the ,azores1 marine fossil shells have long been known4 ,they are found on the north-east coast on a small projecting promontory called ,ponta do ,papagaio 7or ,point-,parrot71 chiefly in a limestone about twenty feet thick1 which rests upon1 and is again covered by1 basaltic lavas1 scori1 and conglomerates4 ,the pebbles in the conglomerate are cemented together with carbonate of lime4 ,mr4 ,hartung1 in his account of the ,azores1 published in #ahfj1 describes twenty-three shells from ,st4 ,mary's1#b of which eight perhaps are identical with living species1 and twelve are with more or less certainty referred to ,european ,tertiary forms1 chiefly ,upper ,miocene4 ,one of the most characteristic and abundant of the new species1 ,cardium ,hartungi1 not known as fossil in ,europe1 is very common in ,porto ,santo and ,baixo1 and serves to connect the ,miocene fauna of the ,azores and the ,madeiras4 ,in some of the ,azores1 as well as in the ,canary islands1 the volcanic fires are not yet extinct1 as the recorded eruptions of ,lanzerote1 ,teneriffe1 ,palma1 ,st4 ,michael's1 and others1 attest4 ,lower ,miocene ,volcanic ,rocks4--,isle of ,mull and ,antrim4--,i may refer the reader to the account already given 7p4 #bdg7 of leaf-beds at ,ardtun1 in the ,isle of ,mull in the ,hebrides1 which bear a relation to the associated volcanic rocks of ,lower ,miocene date analogous to that which the ,madeira leaf-bed1 above described 7p4 #ecb71 bears to the ,pliocene lavas of that island4 ,mr4 ,geikie has shown that the volcanic rocks in ,mull are above #cjjj feet in thickness4 ,there seems little doubt that the well-known columnar basalt of ,staffa1 as well as that of ,antrim in ,ireland1 are of the same age1 and not of higher antiquity1 as once suspected4 ,the ,eifel4--,a large portion of the volcanic rocks of the ,lower ,rhine and the ,eifel are coeval with the ,lower ,miocene deposits to which most of the 8,brown-,coal0 of ,germany belongs4 ,the ,tertiary strata of that age are seen on both sides of the ,rhine1 in the neighbourhood of ,bonn1 resting unconformably on highly inclined and vertical strata of ,silurian and ,devonian rocks4 ,the ,brown-,coal formation of that region consists of beds of loose sand1 sandstone1 and conglomerate1 clay with nodules of clay-iron-stone1 and occasionally silex4 ,layers of light brown and sometimes black lignite are interstratified with the clays and sands1 and often irregularly diffused through them4 ,they contain numerous impressions of leaves and stems of trees1 and are extensively worked for fuel1 whence the name of the formation4 ,in several places layers of trachytic tuff are interstratified1 and in these tuffs are leaves of plants identical with those found in the brown-coal1 showing that1 during the period of the accumulation of the latter1 some volcanic products were ejected4 ,the igneous rocks of the ,westerwald1 and of the mountains called the ,siebengebirge1 consist partly of basaltic and partly of trachytic lavas1 the latter being in general the more ancient of the two4 ,there are many varieties of trachyte1 some of which are highly crystalline1 resembling a coarse-grained granite1 with large separate crystals of feldspar4 ,trachytic tuff is also very abundant4 ,m4 ,von ,dechen1 in his work on the ,siebengebirge1#c has given a copious list of the animal and vegetable remains of the fresh-water strata associated with the brown-coal of that part of ,germany4 ,plants of the genera ,flabellaria1 ,ceanothus1 and ,daphnogene1 including ,d4 cinnamomifolia 7,fig4 #aee71 occur in these beds1 with nearly #aej other plants4 ,the fishes of the brown-coal near ,bonn are found in a bituminous shale1 called paper-coal1 from being divisible into extremely thin leaves4 ,the individuals are very numerous2 but they appear to belong to a small number of species1 some of which were referred by ,agassiz to the genera ,leuciscus1 ,aspius1 and ,perca4 ,the remains of frogs also1 of extinct species1 have been discovered in the paper-coal2 and a complete series may be seen in the museum at ,bonn1 from the most imperfect state of the tadpole to that of the full-grown animal4 ,with these a salamander1 scarcely distinguishable from the recent species1 has been found1 and the remains of many insects4 ,upper and ,lower ,miocene ,volcanic ,rocks of ,auvergne4--,the extinct volcanoes of ,auvergne and ,cantal1 in central ,france1 seem to have commenced their eruptions in the ,lower ,miocene period1 but to have been most active during the ,upper ,miocene and ,pliocene eras4 ,i have already alluded to the grand succession of events of which there is evidence in ,auvergne since the last retreat of the sea 7see p4 #ebg74 ,the earliest monuments of the ,tertiary ,period in that region are lacustrine deposits of great thickness1 in the lowest conglomerates of which are rounded pebbles of quartz1 mica-schist1 granite1 and other non-volcanic rocks1 without the slightest intermixture of igneous products4 ,to these conglomerates succeed argillaceous and calcareous marls and limestones1 containing ,lower ,miocene shells and bones of mammalia1 the higher beds of which sometimes alternate with volcanic tuff of contemporaneous origin4 ,after the filling up or drainage of the ancient lakes1 huge piles of trachytic and basaltic rocks1 with volcanic breccias1 accumulated to a thickness of several thousand feet1 and were superimposed upon granite1 or the contiguous lacustrine strata4 ,the greater portion of these igneous rocks appear to have originated during the ,upper ,miocene and ,pliocene periods2 and extinct quadrupeds of those eras1 belonging to the genera ,mastodon1 ,rhinoceros1 and others1 were buried in ashes and beds of alluvial sand and gravel1 which owe their preservation to overspreading sheets of lava4 ,in ,auvergne1 the most ancient and conspicuous of the volcanic masses is ,mont ,dor1 which rests immediately on the granitic rocks standing apart from the fresh-water strata4 ,this great mountain rises suddenly to the height of several thousand feet above the surrounding platform1 and retains the shape of a flattened and somewhat irregular cone1 the slope of which is gradually lost in the high plain around4 ,this cone is composed of layers of scori1 pumice-stones1 and their fine detritus1 with interposed beds of trachyte and basalt1 which descend often in uninterrupted sheets until they reach and spread themselves round the base of the mountain4#d ,conglomerates1 also1 composed of angular and rounded fragments of igneous rocks1 are observed to alternate with the above2 and the various masses are seen to dip off from the central axis1 and to lie parallel to the sloping flanks of the mountain4 ,the summit of ,mont ,dor terminates in seven or eight rocky peaks1 where no regular crater can now be traced1 but where we may easily imagine one to have existed1 which may have been shattered by earthquakes1 and have suffered degradation by aqueous agents4 ,originally1 perhaps1 like the highest crater of ,etna1 it may have formed an insignificant feature in the great pile1 and1 like it1 may frequently have been destroyed and renovated4 ,respecting the age of the great mass of ,mont ,dor1 we cannot come at present to any positive decision1 because no organic remains have yet been found in the tuffs1 except impressions of the leaves of trees of species not yet determined4 ,it has already been stated 7p4 #bcd7 that the earliest eruptions must have been posterior in origin to those grits and conglomerates of the fresh-water formation of the ,limagne which contain no pebbles of volcanic rocks4 ,but there is evidence at a few points1 as in the hill of ,gergovia1 presently to be mentioned1 that some eruptions took place before the great lakes were drained1 while others occurred after the desiccation of those lakes1 and when deep valleys had already been excavated through fresh-water strata4 ,the valley in which the cone of ,tartaret1 above-mentioned 7p4 #ebg71 is situated affords an impressive monument of the very different dates at which the igneous eruptions of ,auvergne have happened2 for while the cone itself is of ,post-,pliocene date1 the valley is bounded by lofty precipices composed of sheets of ancient columnar trachyte and basalt1 which once flowed from the summit of ,mont ,dor in some part of the ,miocene period4 ,these ,miocene lavas had accumulated to a thickness of nearly #ajjj feet before the ravine was cut down to the level of the river ,couze1 a river which was at length dammed up by the modern cone and the upper part of its course transformed into a lake4 ,gergovia4--,it has been supposed by some observers that there is an alternation of a contemporaneous sheet of lava with fresh-water strata in the hill of ,gergovia1 near ,clermont4 ,but this idea has arisen from the intrusion of the dike represented in ,fig4 #fjd1 which has altered the green and white marls both above and below4 ,nevertheless1 there is a real alternation of volcanic tuff with strata containing ,lower ,miocene fresh-water shells1 among others a ,melania allied to ,m4 inquinata 7,fig4 #bag71 with a ,melanopsis and a ,unio2 there can1 therefore1 be no doubt that in ,auvergne some volcanic explosions took place before the drainage of the lakes1 and at a time when the ,lower ,miocene species of animals and plants still flourished4 ,fig4 #fjd3 ,hill of ,gergovia4 ,eocene ,volcanic ,rocks4--,monte ,bolca4--,the fissile limestone of ,monte ,bolca1 near ,verona1 has for many centuries been celebrated in ,italy for the number of perfect ,ichthyolites which it contains4 ,agassiz has described no less than #acc species of fossil fish from this single deposit1 and the multitude of individuals by which many of the species are represented is attested by the variety of specimens treasured up in the principal museums of ,europe4 ,they have been all obtained from quarries worked exclusively by lovers of natural history1 for the sake of the fossils4 ,had the lithographic stone of ,solenhofen1 now regarded as so rich in fossils1 been in like manner quarried solely for scientific objects1 it would have remained almost a sealed book to palontologists1 so sparsely are the organic remains scattered through it4 ,when ,i visited ,monte ,bolca1 in company with ,sir ,roderick ,murchison1 in #ahbh1 we ascertained that the fish-bearing beds were of ,eocene date1 containing well-known species of ,nummulites1 and that a long series of submarine volcanic eruptions1 evidently contemporaneous1 had produced beds of tuff1 which are cut through by dikes of basalt4 ,there is evidence here of a long series of submarine volcanic eruptions of ,eocene date1 and during some of them1 as ,sir ,r4 ,murchison has suggested1 shoals of fish were probably destroyed by the evolution of heat1 noxious gases1 and tufaceous mud1 just as happened when ,graham's ,island was thrown up between ,sicily and ,africa in #ahca1 at which time the waters of the ,mediterranean were seen to be charged with red mud1 and covered with dead fish over a wide area4#e ,associated with the marls and limestones of ,monte ,bolca are beds containing lignite and shale with numerous plants1 which have been described by ,unger and ,massalongo1 and referred by them to the ,eocene period4 ,i have already cited 7p4 #bfc7 ,professor ,heer's remark1 that several of the species are common to ,monte ,bolca and the white clay of ,alum ,bay1 a ,middle ,eocene deposit2 and the same botanist dwells on the tropical character of the flora of ,monte ,bolca and its distinctness from the sub-tropical flora of the ,lower ,miocene of ,switzerland and ,italy1 in which last there is a far more considerable mixture of forms of a temperate climate1 such as the willow1 poplar1 birch1 elm1 and others4 ,that scarcely any one of the ,monte ,bolca fish should have been found in any other locality in ,europe1 is a striking illustration of the extreme imperfection of the palontological record4 ,we are in the habit of imagining that our insight into the geology of the ,eocene period is more than usually perfect1 and we are certainly acquainted with an almost unbroken succession of assemblages of shells passing one into the other from the era of the ,thanet sands to that of the ,bembridge beds or ,paris gypsum4 ,the general dearth1 therefore1 of fish in the different members of the ,eocene series1 ,upper1 ,middle1 and ,lower1 might induce a hasty reasoner to conclude that there was a poverty of ichthyic forms during this period2 but when a local accident1 like the volcanic eruptions of ,monte ,bolca1 occurs1 proofs are suddenly revealed to us of the richness and variety of this great class of vertebrata in the ,eocene sea4 ,the number of genera of ,monte ,bolca fish is1 according to ,agassiz1 no less than seventy-five1 twenty of them peculiar to that locality1 and only eight common to the antecedent ,cretaceous period4 ,no less than forty-seven out of the seventy-five genera make their appearance for the first time in the ,monte ,bolca rocks1 none of them having been met with as yet in the antecedent formations4 ,they form a great contrast to the fish of the secondary strata1 as1 with the exception of the ,placoids1 they are all ,teleosteans1 only one genus1 ,pycnodus1 belonging to the order of ,ganoids1 which form1 as before stated1 the vast majority of the ichthyolites entombed in the secondary are ,mesozoic rocks4 ,cretaceous ,period4--,m4 ,virlet1 in his account of the geology of the ,morea1 p4 #bje1 has clearly shown that certain traps in ,greece are of ,cretaceous date2 as those1 for example1 which alternate conformably with cretaceous limestone and greensand between ,kastri and ,damala1 in the ,morea4 ,they consist in great part of diallage rocks and serpentine1 and of an amygdaloid with calcareous kernels1 and a base of serpentine4 ,in certain parts of the ,morea1 the age of these volcanic rocks is established by the following proofs3 first1 the lithographic limestones of the ,cretaceous era are cut through by trap1 and then a conglomerate occurs1 at ,nauplia and other places1 containing in its calcareous cement many well-known fossils of the chalk and greensand1 together with pebbles formed of rolled pieces of the same serpentinous trap1 which appear in the dikes above alluded to4 ,period of ,oolite and ,lias4--,although the green and serpentinous trap-rocks of the ,morea belong chiefly to the ,cretaceous era1 as before mentioned1 yet it seems that some eruptions of similar rocks began during the ,oolitic period2#f and it is probable that a large part of the trappean masses1 called ophiolites in the ,apennines1 and associated with the limestone of that chain1 are of corresponding age4 ,trap of the ,new ,red ,sandstone ,period4--,in the southern part of ,devonshire1 trappean rocks are associated with ,new ,red ,sandstone1 and1 according to ,sir ,h4 ,de la ,beche1 have not been intruded subsequently into the sandstone1 but were produced by contemporaneous volcanic action4 ,some beds of grit1 mingled with ordinary red marl1 resemble sands ejected from a crater2 and in the stratified conglomerates occurring near ,tiverton are many angular fragments of trap porphyry1 some of them one or two tons in weight1 intermingled with pebbles of other rocks4 ,these angular fragments were probably thrown out from volcanic vents1 and fell upon sedimentary matter then in the course of deposition4#g ,trap of the ,permian ,period4--,the recent investigations of ,mr4 ,archibald ,geikie in ,ayrshire have shown that some of the volcanic rocks in that county are of ,permian age1 and it appears highly probable that the uppermost portion of ,arthur's ,seat in the suburbs of ,edinburgh marks the site of an eruption of the same era4 ,trap of the ,carboniferous ,period4--,two classes of contemporaneous trap-rocks occur in the coal-field of the ,forth1 in ,scotland4 ,the newest of these1 connected with the higher series of coal-measures1 is well exhibited along the shores of the ,forth1 in ,fifeshire1 where they consist of basalt with olivine1 amygdaloid1 greenstone1 wacke1 and tuff4 ,they appear to have been erupted while the sedimentary strata were in a horizontal position1 and to have suffered the same dislocations which those strata have subsequently undergone4 ,in the volcanic tuffs of this age are found not only fragments of limestone1 shale1 flinty slate1 and sandstone1 but also pieces of coal4 ,the other or older class of carboniferous traps are traced along the south margin of ,stratheden1 and constitute a ridge parallel with the ,ochils1 and extending from ,stirling to near ,st4 ,andrews4 ,they consist almost exclusively of greenstone1 becoming1 in a few instances1 earthy and amygdaloidal4 ,they are regularly interstratified with the sandstone1 shale1 and iron-stone of the lower coal-measures1 and1 on the ,east ,lomond1 with ,mountain ,limestone4 ,i examined these trap-rocks in #ahch1 in the cliffs south of ,st4 ,andrews1 where they consist in great part of stratified tuffs1 which are curved1 vertical1 and contorted1 like the associated coal-measures4 ,in the tuff ,i found fragments of carboniferous shale and limestone1 and intersecting veins of greenstone4 ,fife--,flisk ,dike4--,a trap dike was pointed out to me by ,dr4 ,fleming1 in the parish of ,flisk1 in the northern part of the county of ,fife1 which cuts through the grey sandstone and shale1 forming the lowest part of the ,old ,red ,sandstone1 but which may probably be of carboniferous date4 ,it may be traced for many miles1 passing through the amygdaloidal and other traps of the hill called ,norman's ,law in that parish4 ,in its course it affords a good exemplification of the passage from the trappean into the ,plutonic1 or highly crystalline texture4 ,professor ,gustavus ,rose1 to whom ,i submitted specimens of this dike1 found it to be dolerite1 and composed of greenish black augite and ,labrador feldspar1 the latter being the most abundant ingredient4 ,a small quantity of magnetic iron1 perhaps titaniferous1 is also present4 ,the result of this analysis is interesting1 because both the ancient and modern lavas of ,etna consist in like manner of augite1 ,labradorite1 and titaniferous iron4 ,erect ,trees buried in ,volcanic ,ash at ,arran4--,an interesting discovery was made in #ahfg by ,mr4 ,e4 ,a4 ,wnsch in the carboniferous strata of the north-eastern part of the island of ,arran4 ,in the sea-cliff about five miles north of ,corrie1 near the village of ,laggan1 strata of volcanic ash occur1 forming a solid rock cemented by carbonate of lime and enveloping trunks of trees1 determined by ,mr4 ,binney to belong to the genera ,sigillaria and ,lepidodendron4 ,some of these trees are at right angles to the planes of stratification1 while others are prostrate and accompanied by leaves and fruits of the same genera4 ,i visited the spot in company with ,mr4 ,wnsch in #ahgj1 and saw that the trees with their roots1 of which about fourteen had been observed1 occur at two distinct levels in volcanic tuffs parallel to each other1 and inclined at an angle of about #dj1 having between them beds of shale and coaly matter seven feet thick4 ,it is evident that the trees were overwhelmed by a shower of ashes from some neighbouring volcanic vent1 as ,pompeii was buried by matter ejected from ,vesuvius4 ,the trunks1 several of them from three to five feet in circumference1 remained with their ,stigmarian roots spreading through the stratum below1 which had served as a soil4 ,the trees must have continued for years in an upright position after they were killed by the shower of burning ashes1 giving time for a partial decay of the interior1 so as to afford hollow cylinders into which the spores of plants were wafted4 ,these spores germinated and grew1 until finally their stems were petrified by carbonate of lime like some of the remaining portions of the wood of the containing ,sigillaria4 ,mr4 ,carruthers has discovered that sometimes the plants which had thus grown and become fossil in the inside of a single trunk belonged to several distinct genera4 ,the fact that the tree-bearing deposits now dip at an angle of #dj is the more striking1 as they must clearly have remained horizontal and undisturbed during a long period of intermittent and contemporaneous volcanic action4 ,in some of the associated carboniferous shales1 ferns and calamites occur1 and all the phenomena of the successive buried forests remind us of the sections in pp4 #daj and #daa of the ,nova ,scotia coal-measures1 with this difference only1 that in the case of the ,south ,joggins the fossilisation of the trees was effected without the eruption of volcanic matter4 ,trap of the ,old ,red ,sandstone ,period4--,by referring to the section explanatory of the structure of ,forfarshire1 already given 7p4 #gd71 the reader will perceive that beds of conglomerate1 ,no4 #c1 occur in the middle of the ,old ,red ,sandstone system1 #a1 #b1 #c1 #d4 ,the pebbles in these conglomerates are sometimes composed of granitic and quartzose rocks1 sometimes exclusively of different varieties of trap1 which last1 although purposely omitted in the section referred to1 is often found either intruding itself in amorphous masses and dikes into the old fossiliferous tilestones1 ,no4 #d1 or alternating with them in conformable beds4 ,all the different divisions of the red sandstone1 #a1 #b1 #c1 #d1 are occasionally intersected by dikes1 but they are very rare in ,nos4 #a and #b1 the upper members of the group consisting of red shale and red sandstone4 ,these phenomena1 which occur at the foot of the ,grampians1 are repeated in the ,sidlaw ,hills2 and it appears that in this part of ,scotland volcanic eruptions were most frequent in the earlier part of the ,old ,red ,sandstone period4 ,the trap-rocks alluded to consist chiefly of feldspathic porphyry and amygdaloid1 the kernels of the latter being sometimes calcareous1 often chalcedonic1 and forming beautiful agates4 ,we meet also with claystone1 greenstone1 compact feldspar1 and tuff4 ,some of these rocks look as if they had flowed as lavas over the bottom of the sea1 and enveloped quartz pebbles which were lying there1 so as to form conglomerates with a base of greenstone1 as is seen in ,lumley ,den1 in the ,sidlaw ,hills4 ,on either side of the axis of this chain of hills 7see ,fig4 #ee71 the beds of massive trap1 and the tuffs composed of volcanic sand and ashes1 dip regularly to the south-east or north-west1 conformably with the shales and sandstones4 ,but the geological structure of the ,pentland ,hills1 near ,edinburgh1 shows that igneous rocks were there formed during the newer part of the ,devonian or 8,old ,red0 period4 ,these hills are #aijj feet high above the sea1 and consist of conglomerates and sandstones of ,upper ,devonian age1 resting on the inclined edges of grits and slates of ,lower ,devonian and ,upper ,silurian date4 ,the contemporaneous volcanic rocks intercalated in this ,upper ,old ,red consist of feldspathic lavas1 or feldstones1 with associated tuffs or ashy beds4 ,the lavas were some of them originally compact1 others vesicular1 and these last have been converted into amygdaloids4 ,they consist chiefly of feldstone or compact feldspar4 ,the ,pentland ,hills1 say ,messrs4 ,maclaren and ,geikie1 afford evidence that at the time of the ,upper ,old ,red ,sandstone1 the district to the south-west of ,edinburgh was for a long while the seat of a powerful volcano1 which sent out massive streams of lava and showers of ash1 and continued active until well-nigh the dawn of the ,carboniferous period4#h ,silurian ,volcanic ,rocks4--,it appears from the investigations of ,sir ,r4 ,murchison in ,shropshire1 that when the ,lower ,silurian strata of that country were accumulating1 there were frequent volcanic eruptions beneath the sea2 and the ashes and scori then ejected gave rise to a peculiar kind of tufaceous sandstone or grit1 dissimilar to the other rocks of the ,silurian series1 and only observable in places where syenitic and other trap-rocks protrude4 ,these tuffs occur on the flanks of the ,wrekin and ,caer ,caradoc1 and contain ,silurian fossils1 such as casts of encrinites1 trilobites1 and mollusca4 ,although fossiliferous1 the stone resembles a sandy claystone of the trap family4#i ,thin layers of trap1 only a few inches thick1 alternate in some parts of ,shropshire and ,montgomeryshire with sedimentary strata of the ,lower ,silurian system4 ,this trap consists of slaty porphyry and granular feldspar rock1 the beds being traversed by joints like those in the associated sandstone1 limestone1 and shale1 and having the same strike and dip4#aj ,in ,radnorshire there is an example of twelve bands of stratified trap1 alternating with ,silurian schists and flagstones1 in a thickness of #cej feet4 ,the bedded traps consist of feldspar porphyry1 and other varieties2 and the interposed ,llandeilo flags are of sandstone and shale1 with trilobites and graptolites4#aa ,the ,snowdonian hills in ,carnarvonshire consist in great part of volcanic tuffs1 the oldest of which are interstratified with the ,bala and ,llandeilo beds4 ,there are some contemporaneous feldspathic lavas of this era1 which1 says ,professor ,ramsay1 alter the slates on which they repose1 having doubtless been poured out over them1 in a melted state1 whereas the slates which overlie them having been subsequently deposited after the lava had cooled and consolidated1 have entirely escaped alteration4 ,but there are greenstones associated with the same formation1 which1 although they are often conformable to the slates1 are in reality intrusive rocks4 ,they alter the stratified deposits both above and below them1 and when traced to great distances are sometimes seen to cut through the slates1 and to send off branches4 ,nevertheless1 these greenstones appear to belong1 like the lavas1 to the ,lower ,silurian period4 ,cambrian ,volcanic ,rocks4--,the ,lingula beds in ,north ,wales have been described as #ejjj feet in thickness4 ,in the upper portion of these deposits volcanic tuffs or ashy materials are interstratified with ordinary muddy sediment1 and here and there associated with thick beds of feldspathic lava4 ,these rocks form the mountains called the ,arans and the ,arenigs2 numerous greenstones are associated with them1 which are intrusive1 although they often run in the lines of bedding for a space4 8,much of the ash10 says ,professor ,ramsay1 8seems to have been subarial4 ,islands1 like ,graham's ,island1 may have sometimes raised their craters for various periods above the water1 and by the waste of such islands some of the ashy matter became waterworn1 whence the ashy conglomerate4 ,viscous matter seems also to have been shot into the air as volcanic bombs1 which fell among the dust and broken crystals 7that often form the ashes7 before perfect cooling and consolidation had taken place40#ab ,laurentian ,volcanic ,rocks4--,the ,laurentian rocks in ,canada1 especially in ,ottawa and ,argenteuil1 are the oldest intrusive masses yet known4 ,they form a set of dikes of a fine-grained dark greenstone or dolerite1 composed of feldspar and pyroxene1 with occasional scales of mica and grains of pyrites4 ,their width varies from a few feet to a hundred yards1 and they have a columnar structure1 the columns being truly at right angles to the plane of the dike4 ,some of the dikes send off branches4 ,these dolerites are cut through by intrusive syenite1 and this syenite1 in its turn1 is again cut and penetrated by feldspar porphyry1 the base of which consists of petrosilex1 or a mixture of orthoclase and quartz4 ,all these trap-rocks appear to be of ,laurentian date1 as the ,cambrian and ,huronian rocks rest unconformably upon them4#ac ,whether some of the various conformable crystalline rocks of the ,laurentian series1 such as the coarse-grained granitoid and porphyritic varieties of gneiss1 exhibiting scarcely any signs of stratification1 and some of the serpentines1 may not also be of volcanic origin1 is a point very difficult to determine in a region which has undergone so much metamorphic action4 #a ,linnean ,proceedings2 ,zoology1 #ahfj4 #b ,hartung1 ,die ,azoren1 #ahfj2 also ,insel ,gran ,canaria1 ,madeira und ,porto ,santo1 #ahfd1 ,leipsig4 #c ,geognost4 ,beschreib4 des ,siebengebirges am ,rhein4 ,bonn1 #aheb4 #d ,scrope's ,central ,france1 p4 #ih4 #e ,principles of ,geology1 chap4 xxvi1 #ith ed41 p4 #dcb4 #f ,boblaye and ,virlet1 ,morea1 p4 #bc4 #g ,de la ,beche1 ,geol4 ,proceedings1 vol4 ii1 p4 #aih4 #h ,maclaren1 ,geology of ,fife and ,lothians4 ,geikie1 ,trans4 ,royal ,soc4 ,edinburgh1 #ahfj-ahfa4 #i ,murchison1 ,silurian ,system1 etc41 p4 #bcj4 #aj ,ibid41 p4 #bab4 #aa ,murchison1 ,silurian ,system1 etc41 p4 #cbe4 #ab ,quart4 ,geol4 ,journ41 vol4 ix1 p4 #agj1 #aheb4 #ac ,logan1 ,geology of ,canada1 #ahfc4 ,,chapter ,,xxxi4 ,,plutonic ,,rocks4 ,general ,aspect of ,plutonic ,rocks4 -- ,granite and its ,varieties4 -- ,decomposing into ,spherical ,masses4 -- ,rude columnar ,structure4 -- ,graphic ,granite4 -- ,mutual ,penetration of ,crystals of ,quartz and ,feldspar4 -- ,glass ,cavities in ,quartz of ,granite4 -- ,porphyritic1 talcose1 and syenitic ,granite4 -- ,schorlrock and ,eurite4 -- ,syenite4 -- ,connection of the ,granites and ,syenites with the ,volcanic ,rocks4 -- ,analogy in ,composition of ,trachyte and ,granite4 -- ,granite ,veins in ,glen ,tilt1 ,cape of ,good ,hope1 and ,cornwall4 -- ,metalliferous ,veins in ,strata near their ,junction with ,granite4 -- ,quartz ,veins4 -- ,exposure of ,plutonic ,rocks at the surface due to ,denudation4 ,the ,plutonic rocks may be treated of next in order1 as they are most nearly allied to the volcanic class already considered4 ,i have described1 in the first chapter1 these ,plutonic rocks as the unstratified division of the crystalline or hypogene formations1 and have stated that they differ from the volcanic rocks1 not only by their more crystalline texture1 but also by the absence of tuffs and breccias1 which are the products of eruptions at the earth's surface1 whether thrown up into the air or the sea4 ,they differ also by the absence of pores or cellular cavities1 to which the expansion of the entangled gases gives rise in ordinary lava1 never being scoriaceous or amygdaloidal1 and never forming a porphyry with an uncrystalline base1 nor alternating with tuffs4 ,from these and other peculiarities it has been inferred that the granites have been formed at considerable depths in the earth1 and have cooled and crystallised slowly under great pressure1 where the contained gases could not expand4 ,the volcanic rocks1 on the contrary1 although they also have risen up from below1 have cooled from a melted state more rapidly upon or near the surface4 ,from this hypothesis of the great depth at which the granites originated1 has been derived the name of 8,plutonic rocks40 ,the beginner will easily conceive that the influence of subterranean heat may extend downward from the crater of every active volcano to a great depth below1 perhaps several miles or leagues1 and the effects which are produced deep in the bowels of the earth may1 or rather must1 be distinct2 so that volcanic and ,plutonic rocks1 each different in texture1 and sometimes even in composition1 may originate simultaneously1 the one at the surface1 the other far beneath it4 ,the ,plutonic formations also agree with the volcanic in having veins or ramifications proceeding from central masses into the adjoining rocks1 and causing alterations in these last1 which will be presently described4 ,they also resemble trap in containing no organic remains2 but they differ in being more uniform in texture1 whole mountain masses of indefinite extent appearing to have originated under conditions precisely similar4 ,the two principal members of the ,plutonic family of rocks are ,granite and ,syenite1 each of which1 with their varieties1 bear very much the same relation to each other as the trachytes bear to the basalts4 ,granite is a compound of feldspar1 quartz1 and mica1 the feldspars being rich in silica1 which forms from #fj to #gj per cent of the whole aggregate4 ,in ,syenite quartz is rare or wanting1 hornblende taking the place of mica1 and the proportion of silica not exceeding #ej to #fj per cent4 ,fig4 #fje3 ,mass of granite near the ,sharp ,tor1 ,cornwall4 ,granite and its ,varieties4--,granite often preserves a very uniform character throughout a wide range of territory1 forming hills of a peculiar rounded form1 usually clad with a scanty vegetation4 ,the surface of the rock is for the most part in a crumbling state1 and the hills are often surmounted by piles of stones like the remains of a stratified mass1 as in ,figure #fje1 and sometimes like heaps of boulders1 for which they have been mistaken4 ,the exterior of these stones1 originally quadrangular1 acquires a rounded form by the action of air and water1 for the edges and angles waste away more rapidly than the sides4 ,a similar spherical structure has already been described as characteristic of basalt and other volcanic formations1 and it must be referred to analogous causes1 as yet but imperfectly understood4 ,although it is the general peculiarity of granite to assume no definite shapes1 it is nevertheless occasionally subdivided by fissures1 so as to assume a cuboidal1 and even a columnar1 structure4 ,examples of these appearances may be seen near the ,land's ,end1 in ,cornwall4 7,see ,fig4 #fjf47 ,feldspar1 quartz1 and mica are usually considered as the minerals essential to granite1 the feldspar being most abundant in quantity1 and the proportion of quartz exceeding that of mica4 ,these minerals are united in what is termed a confused crystallisation2 that is to say1 there is no regular arrangement of the crystals in granite1 as in gneiss 7see ,fig4 #fbb71 except in the variety termed graphic granite1 which occurs mostly in granitic veins4 ,this variety is a compound of feldspar and quartz1 so arranged as to produce an imperfect laminar structure4 ,the crystals of feldspar appear to have been first formed1 leaving between them the space now occupied by the darker-coloured quartz4 ,this mineral1 when a section is made at right angles to the alternate plates of feldspar and quartz1 presents broken lines1 which have been compared to ,hebrew characters4 7,see ,fig4 #fjh47 ,the variety of granite called by the ,french ,pegmatite1 which is a mixture of quartz and common feldspar1 usually with some small admixture of white silvery mica1 often passes into graphic granite4 ,fig4 #fjf3 ,granite having a cuboidal and rude columnar structure1 ,land's ,end1 ,cornwall4 ,ordinary granite1 as well as syenite and eurite1 usually contains two kinds of feldspar3 ,first1 the common1 or orthoclase1 in which potash is the prevailing alkali1 and this generally occurs in large crystals of a white or flesh colour2 and secondly1 feldspar in smaller crystals1 in which soda predominates1 usually of a dead white or spotted1 and striated like albite1 but not the same in composition4#a ,graphic granite4 ,fig4 #fjg3 ,section parallel to the lamin4 ,fig4 #fjh3 ,section transverse to the lamin4 ,as a general rule1 quartz1 in a compact or amorphous state1 forms a vitreous mass1 serving as the base in which feldspar and mica have crystallised2 for although these minerals are much more fusible than silex1 they have often imprinted their shapes upon the quartz4 ,this fact1 apparently so paradoxical1 has given rise to much ingenious speculation4 ,we should naturally have anticipated that1 during the cooling of the mass1 the flinty portion would be the first to consolidate2 and that the different varieties of feldspar1 as well as garnets and tourmalines1 being more easily liquefied by heat1 would be the last4 ,precisely the reverse has taken place in the passage of most granite aggregates from a fluid to a solid state1 crystals of the more fusible minerals being found enveloped in hard1 transparent1 glassy quartz1 which has often taken very faithful casts of each1 so as to preserve even the microscopically minute striations on the surface of prisms of tourmaline4 ,various explanations of this phenomenon have been proposed by ,,mm4 de ,beaumont1 ,fournet1 and ,durocher4 ,they refer to ,m4 ,gaudin's experiments on the fusion of quartz1 which show that silex1 as it cools1 has the property of remaining in a viscous state1 whereas alumina never does4 ,this 8gelatinous flint0 is supposed to retain a considerable degree of plasticity long after the granitic mixture has acquired a low temperature4 ,occasionally we find the quartz and feldspar mutually imprinting their forms on each other1 affording evidence of the simultaneous crystallisation of both4#b ,according to the experiments and observations of ,gustavus ,rose1 the quartz of granite has the specific gravity of #bf1 which characterises silica when it is precipitated from a liquid solvent1 and not that inferior density1 namely1 #bc1 which belongs to it when it cools in the laboratory from a state of fusion in what is called the dry way4 ,by some it had been rashly inferred that the manner in which the consolidation of granite takes place is exceedingly different from the cooling of lavas1 and that the intense heat supposed to be necessary for the production of mountain masses of ,plutonic rocks might be dispensed with4 ,but ,mr4 ,david ,forbes informs me that silica can crystallise in the dry way1 and he has found in quartz forming a constituent part of some trachytes1 both from ,guadeloupe and ,iceland1 glass cavities quite similar to those met with in genuine volcanic minerals4 ,these 8glass cavities10 which with many other kindred phenomena have been carefully studied by ,mr4 ,sorby1 are those in which a liquid1 on cooling1 has become first viscous and then solid without crystallising or undergoing a definite change in its physical structure4 ,other cavities which1 like those just mentioned1 are frequently discernible under the microscope in the minerals composing granitic rocks1 are filled1 some of them with gas or vapour1 others with liquid1 and by the movements of the bubbles thus included the distinctness of such cavities from those filled with a glassy substance can be tested4 ,mr4 ,sorby admits that the frequent occurrence of fluid cavities in the quartz of granite implies that water was almost always present in the formation of this rock2 but the same may be said of almost all lavas1 and it is now more than forty years since ,mr4 ,scrope insisted on the important part which water plays in volcanic eruptions1 being so intimately mixed up with the materials of the lava that he supposed it to aid in giving mobility to the fluid mass4 ,it is well known that steam escapes for months1 sometimes for years1 from the cavities of lava when it is cooling and consolidating4 ,as to the result of ,mr4 ,sorby's experiments and speculations on this difficult subject1 they may be stated in a few words4 ,he concludes that the physical conditions under which the volcanic and granitic rocks originate are so far similar that in both cases they combine igneous fusion1 aqueous solution1 and gaseous sublimation--the proof1 he says1 of the operation of water in the formation of granite being quite as strong as of that of heat4#c ,when rocks are melted at great depths water must be present1 for two reasons--,first1 because rainwater and seawater are always descending through fissured and porous rocks1 and must at length find their way into the regions of subterranean heat2 and secondly1 because in a state of combination water enters largely into the composition of some of the most common minerals1 especially those of the aluminous class4 ,but the existence of water under great pressure affords no argument against our attributing an excessively high temperature to the mass with which it is mixed up4 ,bunsen1 indeed1 imagines that in ,iceland water attains a white heat at a very moderate depth4 ,to what extent some of the metamorphic rocks containing the same minerals as the granites may have been formed by hydrothermal action without the intervention of intense heat comparable to that brought into play in a volcanic eruption1 will be considered when we treat of the metamorphic rocks in the thirty-third chapter4 ,fig4 #fji3 ,porphyritic granite4 ,land's ,end1 ,cornwall4 ,porphyritic ,granite4--,this name has been sometimes given to that variety in which large crystals of common feldspar1 sometimes more than three inches in length1 are scattered through an ordinary base of granite4 ,an example of this texture may be seen in the granite of the ,land's ,end1 in ,cornwall 7,fig4 #fji74 ,the two larger prismatic crystals in this drawing represent feldspar1 smaller crystals of which are also seen1 similar in form1 scattered through the base4 ,in this base also appear black specks of mica1 the crystals of which have a more or less perfect hexagonal outline4 ,the remainder of the mass is quartz1 the translucency of which is strongly contrasted to the opaqueness of the white feldspar and black mica4 ,but neither the transparency of the quartz nor the silvery lustre of the mica can be expressed in the engraving4 ,the uniform mineral character of large masses of granite seems to indicate that large quantities of the component elements were thoroughly mixed up together1 and then crystallised under precisely similar conditions4 ,there are1 however1 many accidental1 or 8occasional10 minerals1 as they are termed1 which belong to granite4 ,among these black schorl or tourmaline1 actinolite1 zircon1 garnet1 and fluor spar are not uncommon2 but they are too sparingly dispersed to modify the general aspect of the rock4 ,they show1 nevertheless1 that the ingredients were not everywhere exactly the same2 and a still greater difference may be traced in the ever-varying proportions of the feldspar1 quartz1 and mica4 ,talcose ,granite1 or ,protogine of the ,french1 is a mixture of feldspar1 quartz1 and talc4 ,it abounds in the ,alps1 and in some parts of ,cornwall1 producing by its decomposition the kaolin or china clay1 more than #ab1jjj tons of which are annually exported from that country for the potteries4 ,schorl-rock1 and ,schorly ,granite4--,the former of these is an aggregate of schorl1 or tourmaline1 and quartz4 ,when feldspar and mica are also present1 it may be called schorly granite4 ,this kind of granite is comparatively rare4 ,eurite1 ,feldstone4--,eurite is a rock in which the ingredients of granite are blended into a finely granular mass1 mica being usually absent1 and1 when present1 in such minute flakes as to be invisible to the naked eye4 ,it is sometimes called ,feldstone1 and when the crystals of feldspar are conspicuous it becomes ,feldspar porphyry4 ,all these and other varieties of granite pass into certain kinds of trap--a circumstance which affords one of many arguments in favour of what is now the prevailing opinion1 that the granites are also of igneous origin4 ,the contrast of the most crystalline form of granite to that of the most common and earthy trap is undoubtedly great2 but each member of the volcanic class is capable of becoming porphyritic1 and the base of the porphyry may be more and more crystalline1 until the mass passes to the kind of granite most nearly allied in mineral composition4 ,syenitic ,granite4--,the quadruple compound of quartz1 feldspar1 mica1 and hornblende1 may be termed ,syenitic ,granite1 and forms a passage between the granites and the syenites4 ,this rock occurs in ,scotland and in ,guernsey4 ,syenite4--,we now come to the second division of the ,plutonic rocks1 or those having less than #fj per cent of silica1 and which1 as before stated 7p4 #eeb71 are usually called syenitic4 ,syenite originally received its name from the celebrated ancient quarries of ,syene1 in ,egypt4 ,it differs from granite in having hornblende as a substitute for mica1 and being without quartz4 ,werner at least considered syenite as a binary compound of feldspar and hornblende1 and regarded quartz as merely one of its occasional minerals4 ,miascite4--,miascite is one of the varieties of syenite most frequently spoken of2 it is composed chiefly of orthoclase and nepheline1 with hornblende and quartz as occasional accessory minerals4 ,it derives its name from ,miask1 in the ,ural ,mountains1 where it was first discovered by ,gustavus ,rose4 ,zircon-syenite is another variety closely allied to ,miascite1 but containing crystals of ,zircon4 ,connection of the ,granites and ,syenites with the ,volcanic ,rocks4--,the minerals which constitute alike the ,plutonic and volcanic rocks consist1 almost exclusively1 of seven elements1 namely1 silica1 alumina1 magnesia1 lime1 soda1 potash1 and iron 7see ,table p4 #ddi72 and these may sometimes exist in about the same proportions in a porous lava1 a compact trap1 and a crystalline granite4 ,the same lava1 for example1 may be glassy1 or scoriaceous1 or stony1 or porphyritic1 according to the more or less rapid rate at which it cools4 ,it would be easy to multiply examples and authorities to prove the gradation of the ,plutonic into the trap rocks4 ,on the western side of the ,fiord of ,christiania1 in ,norway1 there is a large district of trap1 chiefly greenstone-porphyry and syenitic-greenstone1 resting on fossiliferous strata4 ,to this1 on its southern limit1 succeeds a region equally extensive of syenite1 the passage from the trappean to the crystalline ,plutonic rock being so gradual that it is impossible to draw a line of demarkation between them4 8,the ordinary granite of ,aberdeenshire10 says ,dr4 ,mac,culloch1 8is the usual ternary compound of quartz1 feldspar1 and mica2 though sometimes hornblende is substituted for the mica4 ,but in many places a variety occurs which is composed simply of feldspar and hornblende2 and in examining more minutely this duplicate compound1 it is observed in some places to assume a fine grain1 and at length to become undistinguishable from the greenstones of the trap family4 ,it also passes in the same uninterrupted manner into a basalt1 and at length into a soft claystone1 with a schistose tendency on exposure1 in no respect differing from those of the trap islands of the western coast40 ,the same author mentions1 that in ,shetland a granite composed of hornblende1 mica1 feldspar1 and quartz graduates in an equally perfect manner into basalt4#d ,in ,hungary there are varieties of trachyte1 which1 geologically speaking1 are of modern origin1 in which crystals1 not only of mica1 but of quartz1 are common1 together with feldspar and hornblende4 ,it is easy to conceive how such volcanic masses may1 at a certain depth from the surface1 pass downward into granite4 ,granitic ,veins4--,i have already hinted at the close analogy in the forms of certain granitic and trappean veins2 and it will be found that strata penetrated by ,plutonic rocks have suffered changes very similar to those exhibited near the contact of volcanic dikes4 ,thus1 in ,glen ,tilt1 in ,scotland1 alternating strata of limestone and argillaceous schist come in contact with a mass of granite4 ,the contact does not take place as might have been looked for if the granite had been formed there before the strata were deposited1 in which case the section would have appeared as in ,fig4 #faj2 but the union is as represented in ,fig4 #faa1 the undulating outline of the granite intersecting different strata1 and occasionally intruding itself in torturous veins into the beds of clay-slate and limestone1 from which it differs so remarkably in composition4 ,the limestone is sometimes changed in character by the proximity of the granitic mass or its veins1 and acquires a more compact texture1 like that of hornstone or chert1 with a splintery fracture1 and effervescing freely with acids4 ,fig4 #faj and ,fig4 #faa3 ,junction of granite and arbillaceous schist in ,glen ,tilt4 7,mac,culloch47 ,fig4 #faj and ,fig4 #faa3 ,junction of granite and arbillaceous schist in ,glen ,tilt4 7,mac,culloch47#e ,the conversion of the limestone and these and many other instances into a siliceous rock1 effervescing slowly with acids1 would be difficult of explanation1 were it not ascertained that such limestones are always impure1 containing grains of quartz1 mica1 or feldspar disseminated through them4 ,the elements of these minerals1 when the rock has been subjected to great heat1 may have been fused1 and so spread more uniformly through the whole mass4 ,in the ,plutonic1 as in the volcanic rocks1 there is every gradation from a tortuous vein to the most regular form of a dike1 such as intersect the tuffs and lavas of ,vesuvius and ,etna4 ,dikes of granite may be seen1 among other places1 on the southern flank of ,mount ,battock1 one of the ,grampians1 the opposite walls sometimes preserving an exact parallelism for a considerable distance4 ,as a general rule1 however1 granite veins in all quarters of the globe are more sinuous in their course than those of trap4 ,they present similar shapes at the most northern point of ,scotland1 and the southernmost extremity of ,africa1 as ,figs4 #fab and #fac will show4 ,fig4 #fab3 ,granite veins traversing clay slate1 ,table ,mountain1 ,cape of ,good ,hope4 ,fig4 #fab3 ,granite veins traversing clay slate1 ,table ,mountain1 ,cape of ,good ,hope4#f ,fig4 #fac3 ,granite veins traversing gneiss1 ,cape ,wrath4 ,fig4 #fac3 ,granite veins traversing gneiss1 ,cape ,wrath4#g ,it is not uncommon for one set of granite veins to intersect another2 and sometimes there are three sets1 as in the environs of ,heidelberg1 where the granite on the banks of the river ,necker is seen to consist of three varieties1 differing in colour1 grain1 and various peculiarities of mineral composition4 ,one of these1 which is evidently the second in age1 is seen to cut through an older granite2 and another1 still newer1 traverses both the second and the first4 ,in ,shetland there are two kinds of granite4 ,one of them1 composed of hornblende1 mica1 feldspar1 and quartz1 is of a dark colour1 and is seen underlying gneiss4 ,the other is a red granite1 which penetrates the dark variety everywhere in veins4#h ,fig4 #fad is a sketch of a group of granite veins in ,cornwall1 given by ,messrs4 ,von ,oeynhausen and ,von ,dechen4#i ,the main body of the granite here is of a porphyritic appearance1 with large crystals of feldspar2 but in the veins it is fine-grained1 and without these large crystals4 ,the general height of the veins is from #af to #bj feet1 but some are much higher4 ,fig4 #fad3 ,granite veins passing through hornblende slate1 ,carnsilver ,cove1 ,cornwall4 ,granite1 syenite1 and those porphyries which have a granitiform structure1 in short all ,plutonic rocks1 are frequently observed to contain metals1 at or near their junction with stratified formations4 ,on the other hand1 the veins which traverse stratified rocks are1 as a general law1 more metalliferous near such junctions than in other positions4 ,hence it has been inferred that these metals may have been spread in a gaseous form through the fused mass1 and that the contact of another rock1 in a different state of temperature1 or sometimes the existence of rents in other rocks in the vicinity1 may have caused the sublimation of the metals4#aj ,fig4 #fae3 a1 b4 ,quartz vein passing through gneiss and greenstone4 ,tronstad ,strand1 near ,christiania4 ,veins of pure quartz are often found in granite as in many stratified rocks1 but they are not traceable1 like veins of granite or trap1 to large bodies of rock of similar composition4 ,they appear to have been cracks1 into which siliceous matter was infiltered4 ,such segregation1 as it is called1 can sometimes clearly be shown to have taken place long subsequently to the original consolidation of the containing rock4 ,thus1 for example1 ,i observed in the gneiss of ,tronstad ,strand1 near ,drammen1 in ,norway1 the section on the beach shown in ,figure #fae4 ,it appears that the alternating strata of whitish granitiform gneiss and black hornblende-schist were first cut by a greenstone dike1 about #b feet wide2 then the crack a1 b1 passed through all these rocks1 and was filled up with quartz4 ,the opposite walls of the vein are in some parts incrusted with transparent crystals of quartz1 the middle of the vein being filled up with common opaque white quartz4 ,fig4 #faf3 ,euritic porphyry alternating with primary fossiliferous strata1 near ,christiania4 ,we have seen that the volcanic formations have been called overlying1 because they not only penetrate others but spread over them4 ,m4 ,necker has proposed to call the granites the underlying igneous rocks1 and the distinction here indicated is highly characteristic4 ,it was1 indeed1 supposed by some of the earlier observers that the granite of ,christiania1 in ,norway1 was intercalated in mountain masses between the primary or palozoic strata of that country1 so as to overlie fossiliferous shale and limestone4 ,but although the granite sends veins into these fossiliferous rocks1 and is decidedly posterior in origin1 its actual superposition in mass has been disproved by ,professor ,keilhau1 whose observations on this controverted point ,i had opportunities1 in #ahcg1 of verifying4 ,there are1 however1 on a smaller scale1 certain beds of euritic porphyry1 some a few feet1 others many yards in thickness1 which pass into granite1 and deserve1 perhaps1 to be classed as ,plutonic rather than trappean rocks1 which may truly be described as interposed conformably between fossiliferous strata1 as the porphyries 7a1 c1 ,fig4 #faf7 which divide the bituminous shales and argillaceous limestones1 f1 f4 ,but some of these same porphyries are partially unconformable1 as b1 and may lead us to suspect that the others also1 notwithstanding their appearance of interstratification1 have been forcibly injected4 ,some of the porphyritic rocks above mentioned are highly quartzose1 others very feldspathic4 ,in proportion as the masses are more voluminous1 they become more granitic in their texture1 less conformable1 and even begin to send forth veins into contiguous strata4 ,in a word1 we have here a beautiful illustration of the intermediate gradations between volcanic and ,plutonic rocks1 not only in their mineralogical composition and structure1 but also in their relations of position to associated formations4 ,if the term 8overlying0 can in this instance be applied to a ,plutonic rock1 it is only in proportion as that rock begins to acquire a trappean aspect4 ,it has been already hinted that the heat which in every active volcano extends downward to indefinite depths must produce simultaneously very different effects near the surface and far below it2 and we cannot suppose that rocks resulting from the crystallising of fused matter under a pressure of several thousand feet1 much less several miles1 of the earth's crust can exactly resemble those formed at or near the surface4 ,hence the production at great depths of a class of rocks analogous to the volcanic1 and yet differing in many particulars1 might have been predicted1 even had we no ,plutonic formations to account for4 ,how well these agree1 both in their positive and negative characters1 with the theory of their deep subterranean origin1 the student will be able to judge by considering the descriptions already given4 ,it has1 however1 been objected1 that if the granitic and volcanic rocks were simply different parts of one great series1 we ought to find in mountain chains volcanic dikes passing upward into lava and downward into granite4 ,but we may answer that our vertical sections are usually of small extent2 and if we find in certain places a transition from trap to porous lava1 and in others a passage from granite to trap1 it is as much as could be expected of this evidence4 ,the prodigious extent of denudation which has been already demonstrated to have occurred at former periods1 will reconcile the student to the belief that crystalline rocks of high antiquity1 although deep in the earth's crust when originally formed1 may have become uncovered and exposed at the surface4 ,their actual elevation above the sea may be referred to the same causes to which we have attributed the upheaval of marine strata1 even to the summits of some mountain chains4 #a ,delesse1 ,ann4 des ,mines1 #aheb1 tome iii1 p4 #dji1 and #ahdh1 tome xiii1 p4 #fge4 #b ,bulletin1 #b;e srie1 iv1 #acjd2 and ,d',archiac1 ,hist4 des ,progrs de la ,gol41 i1 #ch4 #c ,see ,quart4 ,geol4 ,journ41 vol4 xiv1 pp4 #dfe1 #dhh4 #d ,syst4 of ,geol41 vol4 i1 pp4 #aeg and #aeh4 #e ,geol4 ,trans41 ,first ,series1 vol4 iii1 pl4 #ba4 #f ,captain ,b4 ,hall1 ,trans4 ,roy4 ,soc4 ,edinburgh1 vol4 vii4 #g ,western ,islands1 pl4 #ca4 #h ,mac,culloch1 ,syst4 of ,geol41 vol4 ii1 p4 #eh4 #i ,phil4 ,mag4 and ,annals1 ,no4 #bg1 ,new ,series1 ,march1 #ahbi4 #aj ,necker1 ,proceedings of the ,geol4 ,soc41 ,no4 #bf1 p4 #cib4 ,,chapter ,,xxxii4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,plutonic ,,rocks4 ,difficulty in ascertaining the precise ,age of a ,plutonic ,rock4 -- ,test of ,age by ,relative ,position4 -- ,test by ,intrusion and ,alteration4 -- ,test by ,mineral ,composition4 -- ,test by included ,fragments4 -- ,recent and ,pliocene ,plutonic ,rocks1 why invisible4 -- ,miocene ,syenite of the ,isle of ,skye4 -- ,eocene ,plutonic ,rocks in the ,andes4 -- ,granite altering ,cretaceous ,rocks4 -- ,granite altering ,lias in the ,alps and in ,skye4 -- ,granite of ,dartmoor altering ,carboniferous ,strata4 -- ,granite of the ,old ,red ,sandstone ,period4 -- ,syenite altering ,silurian ,strata in ,norway4 -- ,blending of the same with ,gneiss4 -- ,most ancient ,plutonic ,rocks4 -- ,granite protruded in a solid ,form4 ,when we adopt the igneous theory of granite1 as explained in the last chapter1 and believe that different ,plutonic rocks have originated at successive periods beneath the surface of the planet1 we must be prepared to encounter greater difficulty in ascertaining the precise age of such rocks than in the case of volcanic and fossiliferous formations4 ,we must bear in mind that the evidence of the age of each contemporaneous volcanic rock was derived either from lavas poured out upon the ancient surface1 whether in the sea or in the atmosphere1 or from tuffs and conglomerates1 also deposited at the surface1 and either containing organic remains themselves or intercalated between strata containing fossils4 ,but the same tests entirely fail1 or are only applicable in a modified degree1 when we endeavour to fix the chronology of a rock which has crystallised from a state of fusion in the bowels of the earth4 ,in that case we are reduced to the tests of relative position1 intrusion1 alteration of the rocks in contact1 included fragments1 and mineral character2 but all these may yield at best a somewhat ambiguous result4 ,test of ,age by ,relative ,position4--,unaltered fossiliferous strata of every age are met with reposing immediately on ,plutonic rocks2 as at ,christiania1 in ,norway1 where the ,post-pliocene deposits rest on granite2 in ,auvergne1 where the fresh-water ,miocene strata1 and at ,heidelberg1 on the ,rhine1 where the ,new ,red sandstone occupy a similar place4 ,in all these1 and similar instances1 inferiority in position is connected with the superior antiquity of granite4 ,the crystalline rock was solid before the sedimentary beds were superimposed1 and the latter usually contain in them rounded pebbles of the subjacent granite4 ,test by ,intrusion and ,alteration4--,but when ,plutonic rocks send veins into strata1 and alter them near the point of contact1 in the manner before described 7p4 #eei71 it is clear that1 like intrusive traps1 they are newer than the strata which they invade and alter4 ,examples of the application of this test will be given in the sequel4 ,test by ,mineral ,composition4--,notwithstanding a general uniformity in the aspect of ,plutonic rocks1 we have seen in the last chapter that there are many varieties1 such as syenite1 talcose granite1 and others4 ,one of these varieties is sometimes found exclusively prevailing throughout an extensive region1 where it preserves a homogeneous character2 so that1 having ascertained its relative age in one place1 we can recognise its identity in others1 and thus determine from a single section the chronological relations of large mountain masses4 ,having observed1 for example1 that the syenitic granite of ,norway1 in which the mineral called zircon abounds1 has altered the ,silurian strata wherever it is in contact1 we do not hesitate to refer other masses of the same zircon-syenite in the south of ,norway to a post-,silurian date4 ,some have imagined that the age of different granites might1 to a great extent1 be determined by their mineral characters alone2 syenite1 for instance1 or granite with hornblende1 being more modern than common or micaceous granite4 ,but modern investigations have proved these generalisations to have been premature4 ,test by ,included ,fragments4--,this criterion can rarely be of much importance1 because the fragments involved in granite are usually so much altered that they cannot be referred with certainty to the rocks whence they were derived4 ,in the ,white ,mountains1 in ,north ,america1 according to ,professor ,hubbard1 a granite vein1 traversing granite1 contains fragments of slate and trap which must have fallen into the fissure when the fused materials of the vein were injected from below1#a and thus the granite is shown to be newer than those slaty and trappean formations from which the fragments were derived4 ,recent and ,pliocene ,plutonic ,rocks1 why invisible4--,the explanations already given in the #bhth and in the last chapter of the probable relation of the ,plutonic to the volcanic formations1 will naturally lead the reader to infer that rocks of the one class can never be produced at or near the surface without some members of the other being formed below4 ,it is not uncommon for lava-streams to require more than ten years to cool in the open air2 and where they are of great depth1 a much longer period4 ,the melted matter poured from ,jorullo1 in ,mexico1 in the year #agei1 which accumulated in some places to the height of #eej feet1 was found to retain a high temperature half a century after the eruption4#b ,we may conceive1 therefore1 that great masses of subterranean lava may remain in a red-hot or incandescent state in the volcanic foci for immense periods1 and the process of refrigeration may be extremely gradual4 ,sometimes1 indeed1 this process may be retarded for an indefinite period by the accession of fresh supplies of heat2 for we find that the lava in the crater of ,stromboli1 one of the ,lipari ,islands1 has been in a state of constant ebullition for the last two thousand years2 and we may suppose this fluid mass to communicate with some caldron or reservoir of fused matter below4 ,in the ,isle of ,bourbon1 also1 where there has been an emission of lava once in every two years for a long period1 the lava below can scarcely fail to have been permanently in a state of liquefaction4 ,if then it be a reasonable conjecture1 that about #bjjj volcanic eruptions occur in the course of every century1 either above the waters of the sea or beneath them1#c it will follow that the quantity of ,plutonic rock generated or in progress during the ,recent epoch must already have been considerable4 ,but as the ,plutonic rocks originate at some depth in the earth's crust1 they can only be rendered accessible to human observation by subsequent upheaval and denudation4 ,between the period when a ,plutonic rock crystallises in the subterranean regions and the era of its protrusion at any single point of the surface1 one or two geological periods must usually intervene4 ,hence1 we must not expect to find the ,recent or even the ,pliocene granites laid open to view1 unless we are prepared to assume that sufficient time has elapsed since the commencement of the ,pliocene period for great upheaval and denudation4 ,a ,plutonic rock1 therefore1 must1 in general1 be of considerable antiquity relatively to the fossiliferous and volcanic formations1 before it becomes extensively visible4 ,as we know that the upheaval of land has been sometimes accompanied in ,south ,america by volcanic eruptions and the emission of lava1 we may conceive the more ancient ,plutonic rocks to be forced upward to the surface by the newer rocks of the same class formed successively below--subterposition in the ,plutonic1 like superposition in the sedimentary rocks1 being usually characteristic of a newer origin4 ,fig4 #fag3 ,diagram showing the relative position which the ,plutonic and sedimentary formations of different ages may occupy4 ,in ,fig4 #fag an attempt is made to show the inverted order in which sedimentary and ,plutonic formations may occur in the earth's crust4 ,the oldest ,plutonic rock1 ,no4 ,i1 has been upheaved at successive periods until it has become exposed to view in a mountain-chain4 ,this protrusion of ,no4 ,i has been caused by the igneous agency which produced the newer ,plutonic rocks ,nos4 ,,ii1 ,,iii and ,,iv4 ,part of the primary fossiliferous strata1 ,no4 ,i1 have also been raised to the surface by the same gradual process4 ,it will be observed that the ,recent strata ,no4 #d and the ,recent granite or ,plutonic rock ,no4 ,,iv are the most remote from each other in position1 although of contemporaneous date4 ,according to this hypothesis1 the convulsions of many periods will be required before ,recent or ,post-tertiary granite will be upraised so as to form the highest ridges and central axes of mountain-chains4 ,during that time the recent strata ,no4 #d might be covered by a great many newer sedimentary formations4 ,miocene ,plutonic ,rocks4--,a considerable mass of syenite1 in the ,isle of ,skye1 is described by ,dr4 ,mac,culloch as intersecting limestone and shale1 which are of the age of the lias4 ,the limestone1 which at a greater distance from the granite contains shells1 exhibits no traces of them near its junction1 where it has been converted into a pure crystalline marble4#d ,mac,culloch pointed out that the syenite here1 as in ,raasay1 was newer than the secondary rocks1 and ,mr4 ,geikie has since shown that there is a strong probability that this ,plutonic rock may be of ,miocene age1 because a similar ,syenite having a true granitic character in its crystallisation has modified the ,tertiary volcanic rocks of ,ben ,more1 in ,mull1 some of which have undergone considerable metamorphism4 ,eocene ,plutonic ,rocks4--,in a former part of this volume 7,chapter #af71 the great nummulitic formation of the ,alps and ,pyrenees was referred to the ,eocene period1 and it follows that vast movements which have raised those fossiliferous rocks from the level of the sea to the height of more than #aj1jjj feet above its level have taken place since the commencement of the ,tertiary epoch4 ,here1 therefore1 if anywhere1 we might expect to find hypogene formations of ,eocene date breaking out in the central axis or most disturbed region of the loftiest chain in ,europe4 ,accordingly1 in the ,swiss ,alps1 even the flysch1 or upper portion of the nummulitic series1 has been occasionally invaded by ,plutonic rocks1 and converted into crystalline schists of the hypogene class4 ,there can be little doubt that even the talcose granite or gneiss of ,mont ,blanc itself has been in a fused or pasty state since the flysch was deposited at the bottom of the sea2 and the question as to its age is not so much whether it be a secondary or tertiary granite or gneiss1 as whether it should be assigned to the ,eocene or ,miocene epoch4 ,great upheaving movements have been experienced in the region of the ,andes1 during the ,post-tertiary period4 ,in some part1 therefore1 of this chain1 we may expect to discover tertiary ,plutonic rocks laid open to view2 and ,mr4 ,darwin's account of the ,chilian ,andes1 to which the reader may refer1 fully realises this expectation3 for he shows that we have strong ground to presume that ,plutonic rocks there exposed on a large scale are of later date than certain ,secondary and ,tertiary formations4 ,but the theory adopted in this work of the subterranean origin of the hypogene formations would be untenable1 if the supposed fact here alluded to1 of the appearance of tertiary granite at the surface1 was not a rare exception to the general rule4 ,a considerable lapse of time must intervene between the formation of ,plutonic and metamorphic rocks in the nether regions and their emergence at the surface4 ,for a long series of subterranean movements must occur before such rocks can be uplifted into the atmosphere or the ocean2 and1 before they can be rendered visible to man1 some strata which previously covered them must have been stripped off by denudation4 ,we know that in the ,bay of ,bai in #aech1 in ,cutch in #ahai1 and on several occasions in ,peru and ,chili1 since the commencement of the present century1 the permanent upheaval or subsidence of land has been accompanied by the simultaneous emission of lava at one or more points in the same volcanic region4 ,from these and other examples it may be inferred that the rising or sinking of the earth's crust1 operations by which sea is converted into land1 and land into sea1 are a part only of the consequences of subterranean igneous action4 ,it can scarcely be doubted that this action consists1 in a great degree1 of the baking1 and occasionally the liquefaction1 of rocks1 causing them to assume1 in some cases a larger1 in others a smaller volume than before the application of heat4 ,it consists also in the generation of gases1 and their expansion by heat1 and the injection of liquid matter into rents formed in superincumbent rocks4 ,the prodigious scale on which these subterranean causes have operated in ,sicily since the deposition of the ,newer ,pliocene strata will be appreciated when we remember that throughout half the surface of that island such strata are met with1 raised to the height of from #ej to that of #bjjj and even #cjjj feet above the level of the sea4 ,in the same island also the older rocks which are contiguous to these marine tertiary strata must have undergone1 within the same period1 a similar amount of upheaval4 ,the like observations may be extended to nearly the whole of ,europe1 for1 since the commencement of the ,eocene ,period1 the entire ,european area1 including some of the central and very lofty portions of the ,alps themselves1 as ,i have elsewhere shown1#e has1 with the exception of a few districts1 emerged from the deep to its present altitude4 ,there must1 therefore1 have been at great depths in the earth's crust1 within the same period1 an amount of subterranean change corresponding to this vast alteration of level affecting a whole continent4 ,the principal effect of subterranean movements during the ,tertiary ,period seems to have consisted in the upheaval of hypogene formations of an age anterior to the ,carboniferous4 ,the repetition of another series of movements1 of equal violence1 might upraise the ,plutonic and metamorphic rocks of many secondary periods2 and1 if the same force should still continue to act1 the next convulsions might bring up to the day the tertiary and recent hypogene rocks4 ,in the course of such changes many of the existing sedimentary strata would suffer greatly by denudation1 others might assume a metamorphic structure1 or become melted down into ,plutonic and volcanic rocks4 ,meanwhile the deposition of a great thickness of new strata would not fail to take place during the upheaval and partial destruction of the older rocks4 ,but ,i must refer the reader to the last chapter but one of this volume for a fuller explanation of these views4 ,fig4 #fah3 ,section through three layers 7b1 c1 d7 of the ,cretaceous series over granite 7,a74 ,plutonic ,rocks of ,cretaceous ,period4--,it will be shown in the next chapter that chalk1 as well as lias1 has been altered by granite in the eastern ,pyrenees4 ,whether such granite be cretaceous or tertiary1 cannot easily be decided4 ,suppose b1 c1 d1 ,fig4 #fah1 to be three members of the ,cretaceous series1 the lowest of which1 b1 has been altered by the granite ,a1 the modifying influence not having extended so far as c1 or having but slightly affected its lowest beds4 ,now it can rarely be possible for the geologist to decide whether the beds d existed at the time of the intrusion of ,a1 and alteration of b and c1 or whether they were subsequently thrown down upon c4 ,but as some ,cretaceous and even ,tertiary rocks have been raised to the height of more than #ijjj feet in the ,pyrenees1 we must not assume that plutonic formations of the same periods may not have been brought up and exposed by denudation1 at the height of #bjjj or #cjjj feet on the flanks of that chain4 ,fig4 #fai3 ,junction of granite with ,jurassic or ,oolite strata in the ,alps1 near ,champoleon4 ,plutonic ,rocks of the ,oolite and ,lias4--,in the ,department of the ,hautes ,alpes1 in ,france1 ,m4 lie de ,beaumont traced a black argillaceous limestone1 charged with belemnites1 to within a few yards of a mass of granite4 ,here the limestone begins to put on a granular texture1 but is extremely fine-grained4 ,when nearer the junction it becomes grey1 and has a saccharoid structure4 ,in another locality1 near ,champoleon1 a granite composed of quartz1 black mica1 and rose-coloured feldspar is observed partly to overlie the secondary rocks1 producing an alteration which extends for about #cj feet downward1 diminishing in the beds which lie farthest from the granite4 7,see ,fig4 #fai47 ,in the altered mass the argillaceous beds are hardened1 the limestone is saccharoid1 the grits quartzose1 and in the midst of them is a thin layer of an imperfect granite4 ,it is also an important circumstance that near the point of contact1 both the granite and the secondary rocks become metalliferous1 and contain nests and small veins of blende1 galena1 iron1 and copper pyrites4 ,the stratified rocks become harder and more crystalline1 but the granite1 on the contrary1 softer and less perfectly crystallised near the junction4#f ,although the granite is incumbent in the section 7,fig4 #fai71 we cannot assume that it overflowed the strata1 for the disturbances of the rocks are so great in this part of the ,alps that their original position is often inverted4 ,at ,predazzo1 in the ,tyrol1 secondary strata1 some of which are limestones of the ,oolitic period1 have been traversed and altered by ,plutonic rocks1 one portion of which is an augitic porphyry1 which passes insensibly into granite4 ,the limestone is changed into granular marble1 with a band of serpentine at the junction4#g ,plutonic ,rocks of ,carboniferous ,period4--,the granite of ,dartmoor1 in ,devonshire1 was formerly supposed to be one of the most ancient of the ,plutonic rocks1 but is now ascertained to be posterior in date to the culm-measures of that county1 which from their position1 and1 as containing true coal-plants1 are now known to be members of the true ,carboniferous series4 ,this granite1 like the syenitic granite of ,christiania1 has broken through the stratified formations1 on the north-west side of ,dartmoor1 the successive members of the culm-measures abutting against the granite1 and becoming metamorphic as they approach4 ,these strata are also penetrated by granite veins1 and ,plutonic dikes1 called 8elvans40#h ,the granite of ,cornwall is probably of the same date1 and1 therefore1 as modern as the ,carboniferous strata1 if not newer4 ,fig4 #fbj3 ,section through ,silurian strata and ,granite4 ,plutonic ,rocks of ,silurian ,period4--,it has long been known that a very ancient granite near ,christiania1 in ,norway1 is posterior in date to the ,lower ,silurian strata of that region1 although its exact position in the ,palozoic series cannot be defined4 ,von ,buch first announced1 in #ahac1 that it was of newer origin than certain limestones containing orthocerata and trilobites4 ,the proofs consist in the penetration of granite veins into the shale and limestone1 and the alteration of the strata1 for a considerable distance from the point of contact1 both of these veins and the central mass from which they emanate4 7,see p4 #efb7 ,von ,buch supposed that the ,plutonic rock alternated with the fossiliferous strata1 and that large masses of granite were sometimes incumbent upon the strata2 but this idea was erroneous1 and arose from the fact that the beds of shale and limestone often dip towards the granite up to the point of contact1 appearing as if they would pass under it in mass1 as at a1 ,fig4 #fbj1 and then again on the opposite side of the same mountain1 as at b1 dip away from the same granite4 ,when the junctions1 however1 are carefully examined1 it is found that the ,plutonic rock intrudes itself in veins1 and nowhere covers the fossiliferous strata in large overlying masses1 as is so commonly the case with trappean formations4#i ,now this granite1 which is more modern than the ,silurian strata of ,norway1 also sends veins in the same country into an ancient formation of gneiss2 and the relations of the ,plutonic rock and the gneiss1 at their junction1 are full of interest when we duly consider the wide difference of epoch which must have separated their origin4 ,fig4 #fba3 ,granite sending veins into ,silurian strata and gneiss4 ,christiania1 ,norway4 ,the length of this interval of time is attested by the following facts3 ,the fossiliferous1 or ,silurian1 beds rest unconformably upon the truncated edges of the gneiss1 the inclined strata of which had been denuded before the sedimentary beds were superimposed 7see ,figure #fba74 ,the signs of denudation are twofold2 first1 the surface of the gneiss is seen occasionally1 on the removal of the newer beds containing organic remains1 to be worn and smoothed2 secondly1 pebbles of gneiss have been found in some of these ,silurian strata4 ,between the origin1 therefore1 of the gneiss and the granite there intervened1 first1 the period when the strata of gneiss were denuded2 secondly1 the period of the deposition of the ,silurian deposits upon the denuded and inclined gneiss1 a4 ,yet the granite produced after this long interval is often so intimately blended with the ancient gneiss1 at the point of junction1 that it is impossible to draw any other than an arbitrary line of separation between them2 and where this is not the case1 tortuous veins of granite pass freely through gneiss1 ending sometimes in threads1 as if the older rock had offered no resistance to their passage4 ,these appearances may probably be due to hydrothermal action 7see p4 #ehd74 ,i shall merely observe in this place that had such junctions alone been visible1 and had we not learnt1 from other sections1 how long a period elapsed between the consolidation of the gneiss and the injection of this granite1 we might have suspected that the gneiss was scarcely solidified1 or had not yet assumed its complete metamorphic character when invaded by the ,plutonic rock4 ,from this example we may learn how impossible it is to conjecture whether certain granites in ,scotland1 and other countries1 which send veins into gneiss and other metamorphic rocks1 are primary1 or whether they may not belong to some secondary or tertiary period4 ,oldest ,granites4--,it is not half a century since the doctrine was very general that all granitic rocks were primitive1 that is to say1 that they originated before the deposition of the first sedimentary strata1 and before the creation of organic beings 7see p4 #cd74 ,but so greatly are our views now changed1 that we find it no easy task to point out a single mass of granite demonstrably more ancient than known fossiliferous deposits4 ,could we discover some ,laurentian strata resting immediately on granite1 there being no alterations at the point of contact1 nor any intersecting granitic veins1 we might then affirm the ,plutonic rock to have originated before the oldest known fossiliferous strata4 ,still it would be presumptuous1 as we have already pointed out 7p4 #dfd71 to suppose that when a small part only of the globe has been investigated1 we are acquainted with the oldest fossiliferous strata in the crust of our planet4 ,even when these are found1 we cannot assume that there never were any antecedent strata containing organic remains1 which may have become metamorphic4 ,if we find pebbles of granite in a conglomerate of the ,lower ,laurentian system1 we may then feel assured that the parent granite was formed before the ,laurentian formation4 ,but if the incumbent strata be merely ,cambrian or ,silurian1 the fundamental granite1 although of high antiquity1 may be posterior in date to known fossiliferous formations4 ,protrusion of ,solid ,granite4--,in part of ,sutherlandshire1 near ,brora1 common granite1 composed of feldspar1 quartz1 and mica is in immediate contact with ,oolitic strata1 and has clearly been elevated to the surface at a period subsequent to the deposition of those strata4#aj ,professor ,sedgwick and ,sir ,r4 ,murchison conceive that this granite has been upheaved in a solid form2 and that in breaking through the submarine deposits1 with which it was not perhaps originally in contact1 it has fractured them so as to form a breccia along the line of junction4 ,this breccia consists of fragments of shale1 sandstone1 and limestone1 with fossils of the oolite1 all united together by a calcareous cement4 ,the secondary strata at some distance from the granite are but slightly disturbed1 but in proportion to their proximity the amount of dislocation becomes greater4 ,mr4 ,t4 ,mc,kenney ,hughes has suggested to me in explanation of these phenomena that they may be the effect of the association of more pliant strata with hard unyielding rocks1 the whole of which were subjected simultaneously to great movements1 whether of elevation or subsidence1 and of lateral pressure1 during which the more solid granite1 being incapable of compression1 was forced through the softer beds of shale1 sandstone1 and limestone4 ,he remarks that similar breccias with slickensides are observed on a minor scale where rocks of different composition and rigidity are contorted together4 ,such protrusion may have been brought about by degrees by innumerable shocks of earthquakes repeated after long intervals of time along the same tract of country4 ,the opening of new fissures in the hardest rocks is a frequent accompaniment of such convulsions1 and during the consequent vibrations1 breccias must often be caused4 ,but these catastrophes1 as we well know1 do not imply that the land or sea of the disturbed region are rendered uninhabitable by living beings1 and by no means indicate a state of things different from that witnessed in the ordinary course of nature4 #a ,silliman's ,journ41 ,no4 #fi1 p4 #abc4 #b ,see 8,principles10 ,index1 8,jorullo40 #c ,ibid41 8,volcanic ,eruptions40 #d 8,western ,islands10 vol4 i1 p4 #ccj4 #e ,see map of ,europe1 and explanation1 in ,principles1 book i4 #f lie de ,beaumont sur les ,montagnes de l',oisans1 etc4 ,mm4 de la ,soc4 d',hist4 ,nat4 de ,paris1 tome v4 #g ,von ,buch1 ,annales de ,chimie1 etc4 #h ,proceed4 ,geol4 ,soc41 vol4 ii1 p4 #efb2 and ,trans41 #bnd series1 vol4 v1 p4 #fhf4 #i ,see the ,ga ,norvegica and other works of ,keilhau1 with whom ,i examined this country4 #aj ,murchison1 ,geol4 ,trans41 #bnd series1 vol4 ii1 p4 #cjg4 ,,chapter ,,xxxiii4 ,,metamorphic ,,rocks4 ,general ,character of ,metamorphic ,rocks4 -- ,gneiss4 -- ,hornblende-schist4 -- ,serpentine4 -- ,mica-schist4 -- ,clay-slate4 -- ,quartzite4 -- ,chlorite-schist4 -- ,metamorphic ,limestone4 -- ,origin of the metamorphic ,strata4 -- ,their ,stratification4 -- ,fossiliferous ,strata near intrusive ,masses of ,granite converted into ,rocks identical with different ,members of the metamorphic ,series4 -- ,arguments hence derived as to the ,nature of ,plutonic ,action4 -- ,hydrothermal ,action1 or the ,influence of ,steam and ,gases in producing ,metamorphism4 -- ,objections to the metamorphic ,theory considered4 ,we have now considered three distinct classes of rocks3 first1 the aqueous1 or fossiliferous2 secondly1 the volcanic2 and1 thirdly1 the ,plutonic2 and it remains for us to examine those crystalline 7or hypogene7 strata to which the name of metamorphic has been assigned4 ,the last-mentioned term expresses1 as before explained1 a theoretical opinion that such strata1 after having been deposited from water1 acquired1 by the influence of heat and other causes1 a highly crystalline texture4 ,they who still question this opinion may call the rocks under consideration the stratified hypogene formations or crystalline schists4 ,these rocks1 when in their characteristic or normal state1 are wholly devoid of organic remains1 and contain no distinct fragments of other rocks1 whether rounded or angular4 ,they sometimes break out in the central parts of mountain chains1 but in other cases extend over areas of vast dimensions1 occupying1 for example1 nearly the whole of ,norway and ,sweden1 where1 as in ,brazil1 they appear alike in the lower and higher grounds4 ,however crystalline these rocks may become in certain regions1 they never1 like granite or trap1 send veins into contiguous formations4 ,in ,great ,britain1 those members of the series which approach most nearly to granite in their composition1 as gneiss1 mica-schist1 and hornblende-schist1 are confined to the country north of the rivers ,forth and ,clyde4 ,many attempts have been made to trace a general order of succession or superposition in the members of this family2 clay-slate1 for example1 having been often supposed to hold invariably a higher geological position than mica-schist1 and mica-schist to overlie gneiss4 ,but although such an order may prevail throughout limited districts1 it is by no means universal4 ,to this subject1 however1 ,i shall again revert1 in ,chapter ,,xxxv1 where the chronological relations of the metamorphic rocks are pointed out4 ,principal ,metamorphic ,rocks4--,the following may be enumerated as the principal members of the metamorphic class3--gneiss1 mica-schist1 hornblende-schist1 clay-slate1 chlorite-schist1 hypogene or metamorphic limestone1 and certain kinds of quartz-rock or quartzite4 ,fig4 #fbb3 ,fragment of gneiss2 section made at right angles to the planes of foliation4 ,gneiss4--,the first of these1 gneiss1 may be called stratified--or by those who object to that term1 foliated--granite1 being formed of the same materials as granite1 namely1 feldspar1 quartz1 and mica4 ,in the specimen in ,fig4 #fbb1 the white layers consist almost exclusively of granular feldspar1 with here and there a speck of mica and grain of quartz4 ,the dark layers are composed of grey quartz and black mica1 with occasionally a grain of feldspar intermixed4 ,the rock splits most easily in the plane of these darker layers1 and the surface thus exposed is almost entirely covered with shining spangles of mica4 ,the accompanying quartz1 however1 greatly predominates in quantity1 but the most ready cleavage is determined by the abundance of mica in certain parts of the dark layer4 ,instead of consisting of these thin lamin1 gneiss is sometimes simply divided into thick beds1 in which the mica has only a slight degree of parallelism to the planes of stratification4 ,hand specimens may often be obtained from such gneiss which are undistinguishable from granite1 affording an argument to which we shall allude in the concluding part of this chapter1 in favour of those who regard all granite and syenite not as igneous rocks1 but as aqueous formations so altered as to have lost all signs of their original stratified arrangement4 ,gneiss in geology is commonly used to designate not merely stratified and foliated rocks having the same component materials as granite or syenite1 but also in a wider sense to embrace the formation with which other members of the metamorphic series1 such as hornblende-schist1 may alternate1 and which are then considered subordinate to the true gneiss4 ,the different varieties of rock allied to gneiss1 into which feldspar enters as an essential ingredient1 will be understood by referring to what was said of granite4 ,thus1 for example1 hornblende may be superadded to mica1 quartz1 and feldspar1 forming a hornblendic or syenitic gneiss2 or talc may be substituted for mica1 constituting talcose gneiss 7called stratified protogine by the ,french71 a rock composed of feldspar1 quartz1 and talc1 in distinct crystals or grains4 ,eurite1 which has already been mentioned as a ,plutonic rock1 occurs also with precisely the same composition in beds subordinate to gneiss or mica-slate4 ,hornblende-schist is usually black1 and composed principally of hornblende1 with a variable quantity of feldspar1 and sometimes grains of quartz4 ,when the hornblende and feldspar are in nearly equal quantities1 and the rock is not slaty1 it corresponds in character with the greenstones of the trap family1 and has been called 8primitive greenstone40 ,it may be termed hornblende rock1 or amphibolite4 ,some of these hornblendic masses may really have been volcanic rocks1 which have since assumed a more crystalline or metamorphic texture4 ,serpentine is a greenish rock1 a silicate of magnesia1 in which there is sometimes from #cj to #dj per cent of magnesia4 ,it enters largely into the composition of a trap dike cutting through ,old ,red ,sandstone in ,forfarshire1 and in that case is probably an altered basaltic dike which had contained much olivine4 ,the theory of its having been originally a volcanic product subsequently altered by metamorphism may at first sight seem inconsistent with its occurrence in large and regularly stratified masses in the metamorphic series in ,scotland1 as in ,aberdeenshire4 ,but it has been suggested in explanation that such serpentine may have been originally regularly-bedded trap tuff1 and volcanic breccia1 with much olivine1 which would still retain a stratified appearance after their conversion into a metamorphic rock4 ,actinolite ,schist is a slaty foliated rock1 composed chiefly of actinolite1 an emerald-green mineral1 allied to hornblende1 with some admixture of garnet1 mica1 and quartz4 ,mica-schist or ,micaceous ,schist is1 next to gneiss1 one of the most abundant rocks of the metamorphic series4 ,it is slaty1 essentially composed of mica and quartz1 the mica sometimes appearing to constitute the whole mass4 ,beds of pure quartz also occur in this formation4 ,in some districts1 garnets in regular twelve-sided crystals form an integrant part of mica-schist4 ,this rock passes by insensible gradations into clay-slate4 ,clay-slate--,argillaceous ,schist--,argillite4--,this rock sometimes resembles an indurated clay or shale4 ,it is for the most part extremely fissile1 often affording good roofing-slate4 ,occasionally it derives a shining and silky lustre from the minute particles of mica or talc which it contains4 ,it varies from greenish or bluish-grey to a lead colour2 and it may be said of this1 more than of any other schist1 that it is common to the metamorphic and fossiliferous series1 for some clay-slates taken from each division would not be distinguishable by mineral characters alone4 ,it is not uncommon to meet with an argillaceous rock having the same composition1 without the slaty cleavage1 which may be called argillite4 ,chlorite ,schist is a green slaty rock1 in which chlorite is abundant in foliated plates1 usually blended with minute grains of quartz1 or sometimes with feldspar or mica2 often associated with1 and graduating into1 gneiss and clay-slate4 ,quartzite1 or ,quartz ,rock1 is an aggregate of grains of quartz which are either in minute crystals1 or in many cases slightly rounded1 occurring in regular strata1 associated with gneiss or other metamorphic rocks4 ,compact quartz1 like that so frequently found in veins1 is also found together with granular quartzite4 ,both of these alternate with gneiss or mica-schist1 or pass into those rocks by the addition of mica1 or of feldspar and mica4 ,crystalline1 or ,metamorphic ,limestone4--,this hypogene rock1 called by the earlier geologists primary limestone1 is sometimes a white crystalline granular marble1 which when in thick beds can be used in sculpture2 but more frequently it occurs in thin beds1 forming a foliated schist much resembling in colour and arrangement certain varieties of gneiss and mica-schist4 ,when it alternates with these rocks1 it often contains some crystals of mica1 and occasionally quartz1 feldspar1 hornblende1 talc1 chlorite1 garnet1 and other minerals4 ,it enters sparingly into the structure of the hypogene districts of ,norway1 ,sweden1 and ,scotland1 but is largely developed in the ,alps4 ,origin of the ,metamorphic ,strata4--,having said thus much of the mineral composition of the metamorphic rocks1 ,i may combine what remains to be said of their structure and history with an account of the opinions entertained of their probable origin4 ,at the same time1 it may be well to forewarn the reader that we are here entering upon ground of controversy1 and soon reach the limits where positive induction ends1 and beyond which we can only indulge in speculations4 ,it was once a favourite doctrine1 and is still maintained by many1 that these rocks owe their crystalline texture1 their want of all signs of a mechanical origin1 or of fossil contents1 to a peculiar and nascent condition of the planet at the period of their formation4 ,the arguments in refutation of this hypothesis will be more fully considered when ,i show1 in ,chapter ,,xxxv1 to how many different ages the metamorphic formations are referable1 and how gneiss1 mica-schist1 clay-slate1 and hypogene limestone 7that of ,carrara1 for example7 have been formed1 not only since the first introduction of organic beings into this planet1 but even long after many distinct races of plants and animals had flourished and passed away in succession4 ,the doctrine respecting the crystalline strata implied in the name metamorphic may properly be treated of in this place2 and we must first inquire whether these rocks are really entitled to be called stratified in the strict sense of having been originally deposited as sediment from water4 ,the general adoption by geologists of the term stratified1 as applied to these rocks1 sufficiently attests their division into beds very analogous1 at least in form1 to ordinary fossiliferous strata4 ,this resemblance is by no means confined to the existence in both occasionally of a laminated structure1 but extends to every kind of arrangement which is compatible with the absence of fossils1 and of sand1 pebbles1 ripple-mark1 and other characters which the metamorphic theory supposes to have been obliterated by ,plutonic action4 ,thus1 for example1 we behold alike in the crystalline and fossiliferous formations an alternation of beds varying greatly in composition1 colour1 and thickness4 ,we observe1 for instance1 gneiss alternating with layers of black hornblende-schist or of green chlorite-schist1 or with granular quartz or limestone2 and the interchange of these different strata may be repeated for an indefinite number of times4 ,in the like manner1 mica-schist alternates with chlorite-schist1 and with beds of pure quartz or of granular limestone4 ,we have already seen that1 near the immediate contact of granitic veins and volcanic dikes1 very extraordinary alterations in rocks have taken place1 more especially in the neighbourhood of granite4 ,it will be useful here to add other illustrations1 showing that a texture undistinguishable from that which characterises the more crystalline metamorphic formations has actually been superinduced in strata once fossiliferous4 ,fossiliferous ,strata rendered metamorphic by intrusive ,masses of ,granite4--,in the southern extremity of ,norway there is a large district1 on the west side of the fiord of ,christiania1 which ,i visited in #ahcg with the late ,professor ,keilhau1 in which syenitic granite protrudes in mountain masses through fossiliferous strata1 and usually sends veins into them at the point of contact4 ,the stratified rocks1 replete with shells and zoophytes1 consist chiefly of shale1 limestone1 and some sandstone1 and all these are invariably altered near the granite for a distance of from #ej to #djj yards4 ,the aluminous shales are hardened1 and have become flinty4 ,sometimes they resemble jasper4 ,ribboned jasper is produced by the hardening of alternate layers of green and chocolate-coloured schist1 each stripe faithfully representing the original lines of stratification4 ,nearer the granite the schist often contains crystals of hornblende1 which are even met with in some places for a distance of several hundred yards from the junction2 and this black hornblende is so abundant that eminent geologists1 when passing through the country1 have confounded it with the ancient hornblende-schist1 subordinate to the great gneiss formation of ,norway4 ,frequently1 between the granite and the hornblende-slate above-mentioned1 grains of mica and crystalline feldspar appear in the schist1 so that rocks resembling gneiss and mica-schist are produced4 ,fossils can rarely be detected in these schists1 and they are more completely effaced in proportion to the more crystalline texture of the beds1 and their vicinity to the granite4 ,fig4 #fbc3 ,ground-plan of altered slate and limestone near granite4 ,christiania4 ,the arrows indicate the dip1 and the oblique lines the strike of the beds4 ,in some places the siliceous matter of the schist becomes a granular quartz2 and when hornblende and mica are added1 the altered rock loses its stratification1 and passes into a kind of granite4 ,the limestone1 which at points remote from the granite is of an earthy texture and blue colour1 and often abounds in corals1 becomes a white granular marble near the granite1 sometimes siliceous1 the granular structure extending occasionally upward of #djj yards from the junction2 the corals being for the most part obliterated1 though sometimes preserved1 even in the white marble4 ,both the altered limestone and hardened slate contain garnets in many places1 also ores of iron1 lead1 and copper1 with some silver4 ,these alterations occur equally whether the granite invades the strata in a line parallel to the general strike of the fossiliferous beds1 or in a line at right angles to their strike1 both of which modes of junction will be seen by the ground-plan in ,fig4 #fbc4a ,the granite of ,cornwall sends forth veins into a coarse argillaceous-schist1 provincially termed killas4 ,this killas is converted into hornblende-schist near the contact with the veins4 ,these appearances are well seen at the junction of the granite and killas1 in ,st4 ,michael's ,mount1 a small island nearly #cjj feet high1 situated in the bay1 at a distance of about three miles from ,penzance4 ,the granite of ,dartmoor1 in ,devonshire1 says ,sir ,h4 ,de la ,beche1 has intruded itself into the ,carboniferous slate and slaty sandstone1 twisting and contorting the strata1 and sending veins into them4 ,hence some of the slate rocks have become 8micaceous2 others more indurated1 and with the characters of mica-slate and gneiss2 while others again appear converted into a hard zoned rock strongly impregnated with feldspar40#b ,we learn from the investigation of ,m4 ,dufrenoy that in the eastern ,pyrenees there are mountain masses of granite posterior in date to the formations called lias and chalk of that district1 and that these fossiliferous rocks are greatly altered in texture1 and often charged with iron-ore1 in the neighbourhood of the granite4 ,thus in the environs of ,st4 ,martin1 near ,st4 ,paul de ,fenouillet1 the chalky limestone becomes more crystalline and saccharoid as it approaches the granite1 and loses all trace of the fossils which it previously contained in abundance4 ,at some points1 also1 it becomes dolomitic1 and filled with small veins of carbonate of iron1 and spots of red iron-ore4 ,at ,rancie the lias nearest the granite is not only filled with iron-ore1 but charged with pyrites1 tremolite1 garnet1 and a new mineral somewhat allied to feldspar1 called1 from the place in the ,pyrenees where it occurs1 8couzeranite40 8,hornblende-schist10 says ,dr4 ,mac,culloch1 8may at first have been mere clay2 for clay or shale is found altered by trap into ,lydian stone1 a substance differing from hornblende-schist almost solely in compactness and uniformity of texture40#c 8,in ,shetland10 remarks the same author1 8argillaceous-schist 7or clay-slate71 when in contact with granite1 is sometimes converted into hornblende-schist1 the schist becoming first siliceous1 and ultimately1 at the contact1 hornblende-schist40 ,in like manner gneiss and mica-schist may be nothing more than altered micaceous and argillaceous sandstones1 granular quartz may have been derived from siliceous sandstone1 and compact quartz from the same materials4 ,clay-slate may be altered shale1 and granular marble may have originated in the form of ordinary limestone1 replete with shells and corals1 which have since been obliterated2 and1 lastly1 calcareous sands and marls may have been changed into impure crystalline limestones4 ,the anthracite and plumbago associated with hypogene rocks may have been coal2 for not only is coal converted into anthracite in the vicinity of some trap dikes1 but we have seen that a like change has taken place generally even far from the contact of igneous rocks1 in the disturbed region of the ,appalachians4 ,at ,worcester1 in the ,state of ,massachusetts1 #de miles due west of ,boston1 a bed of plumbago and impure anthracite occurs1 interstratified with mica-schist4 ,it is about two feet in thickness1 and has been made use of both as fuel1 and in the manufacture of lead pencils4 ,at the distance of #cj miles from the plumbago1 there occurs1 on the borders of ,rhode ,island1 an impure anthracite in slates containing impressions of coal-plants of the genera ,pecopteris1 ,neuropteris1 ,calamites1 etc4 ,this anthracite is intermediate in character between that of ,pennsylvania and the plumbago of ,worcester1 in which last the gaseous or volatile matter 7hydrogen1 oxygen1 and nitrogen7 is to the carbon only in the proportion of three per cent4 ,after traversing the country in various directions1 ,i came to the conclusion that the carboniferous shales or slates with anthracite and plants1 which in ,rhode ,island often pass into mica-schists1 have at ,worcester assumed a perfectly crystalline and metamorphic texture2 the anthracite having been nearly transmuted into that state of pure carbon which is called plumbago or graphite4#d ,now the alterations above described as superinduced in rocks by volcanic dikes and granite veins prove incontestably that powers exist in nature capable of transforming fossiliferous into crystalline strata1 a very few simple elements constituting the component materials common to both classes of rocks4 ,these elements1 which are enumerated in the table at p4 #dii1 may be made to form new combinations by what has been termed ,plutonic action1 or those chemical changes which are no doubt connected with the passage of heat1 unusually heated steam and waters1 through the strata4 ,hydrothermal ,action1 or the ,influence of ,steam and ,gases in producing ,metamorphism4--,the experiments of ,gregory ,watt1 in fusing rocks in the laboratory1 and allowing them to consolidate by slow cooling1 prove distinctly that a rock need not be perfectly melted in order that a re-arrangement of its component particles should take place1 and a partial crystallisation ensue4#e ,we may easily suppose1 therefore1 that all traces of shells and other organic remains may be destroyed1 and that new chemical combinations may arise1 without the mass being so fused as that the lines of stratification should be wholly obliterated4 ,we must not1 however1 imagine that heat alone1 such as may be applied to a stone in the open air1 can constitute all that is comprised in ,plutonic action4 ,we know that volcanoes in eruption not only emit fluid lava1 but give off steam and other heated gases1 which rush out in enormous volume1 for days1 weeks1 or years continuously1 and are even disengaged from lava during its consolidation4 ,we also know that long after volcanoes have spent their force1 hot springs continue for ages to flow out at various points in the same area4 ,in regions1 also1 subject to violent earthquakes such springs are frequently observed issuing from rents1 usually along lines of fault or displacement of the rocks4 ,these thermal waters are most commonly charged with a variety of mineral ingredients1 and they retain a remarkable uniformity of temperature from century to century4 ,a like uniformity is also persistent in the nature of the earthy1 metallic1 and gaseous substances with which they are impregnated4 ,it is well ascertained that springs1 whether hot or cold1 charged with carbonic acid1 especially with hydrofluoric acid1 which is often present in small quantities1 are powerful causes of decomposition and chemical reaction in rocks through which they percolate4 ,the changes which ,daubre has shown to have been produced by the alkaline waters of ,plombires in the ,vosges1 are more especially instructive4#f ,these waters have a heat of #afj ,f41 or an excess of #aji above the average temperature of ordinary springs in that district4 ,they were conveyed by the ,romans to baths through long conduits or aqueducts4 ,the foundations of some of their works consisted of a bed of concrete made of lime1 fragments of brick1 and sandstone4 ,through this and other masonry the hot waters have been percolating for centuries1 and have given rise to various zeolites--apophyllite and chabazite among others2 also to calcareous spar1 arragonite1 and fluor spar1 together with siliceous minerals1 such as opal--all found in the inter-spaces of the bricks and mortar1 or constituting part of their re-arranged materials4 ,the quantity of heat brought into action in this instance in the course of #bjjj years has1 no doubt1 been enormous1 but the intensity of it developed at any one moment has been always inconsiderable4 ,from these facts and from the experiments and observations of ,snarmont1 ,daubre1 ,delesse1 ,scheerer1 ,sorby1 ,sterry ,hunt1 and others1 we are led to infer that when in the bowels of the earth there are large volumes of matter containing water and various acids intensely heated under enormous pressure1 these subterranean fluid masses will gradually part with their heat by the escape of steam and various gases through fissures1 producing hot springs2 or by the passage of the same through the pores of the overlying and injected rocks4 ,even the most compact rocks may be regarded1 before they have been exposed to the air and dried1 in the light of sponges filled with water4 ,according to the experiments of ,henry1 water1 under a hydrostatic pressure of #if feet1 will absorb three times as much carbonic acid gas as it can under the ordinary pressure of the atmosphere4 ,there are other gases1 as well as the carbonic acid1 which water absorbs1 and more rapidly in proportion to the amount of pressure4 ,although the gaseous matter first absorbed would soon be condensed1 and part with its heat1 yet the continual arrival of fresh supplies from below might1 in the course of ages1 cause the temperature of the water1 and with it that of the containing rock1 to be materially raised2 the water acts not only as a vehicle of heat1 but also by its affinity for various silicates1 which1 when some of the materials of the invaded rocks are decomposed1 form quartz1 feldspar1 mica1 and other minerals4 ,as for quartz1 it can be produced under the influence of heat by water holding alkaline silicates in solution1 as in the case of the ,plombires springs4 ,the quantity of water required1 according to ,daubre1 to produce great transformations in the mineral structure of rocks1 is very small4 ,as to the heat required1 silicates may be produced in the moist way at about incipient red heat1 whereas to form the same in the dry way would require a much higher temperature4 ,m4 ,fournet1 in his description of the metalliferous gneiss near ,clermont1 in ,auvergne1 states that all the minute fissures of the rock are quite saturated with free carbonic acid gas2 which gas rises plentifully from the soil there and in many parts of the surrounding country4 ,the various elements of the gneiss1 with the exception of the quartz1 are all softened2 and new combinations of the acid with lime1 iron1 and manganese are continually in progress4#g ,the power of subterranean gases is well illustrated by the stufas of ,st4 ,calogero in the ,lipari ,islands1 where the horizontal strata of tuffs1 forming cliffs #bjj feet high1 have been discoloured in places by the jets of steam often above the boiling point1 called 8stufas10 issuing from the fissures2 and similar instances are recorded by ,m4 ,virlet of corrosion of rocks near ,corinth1 and by ,dr4 ,daubeny of decomposition of trachytic rocks by sulphureted hydrogen and muriatic acid gases in the ,solfatara1 near ,naples4 ,in all these instances it is clear that the gaseous fluids must have made their way through vast thicknesses of porous or fissured rocks1 and their modifying influence may spread through the crust for thousands of yards in thickness4 ,it has been urged as an argument against the metamorphic theory1 that rocks have a small power of conducting heat1 and it is true that when dry1 and in the air1 they differ remarkably from metals in this respect4 ,the syenite of ,norway1 as we have seen 7p4 #eeh71 has sometimes altered fossiliferous strata both in the direction of their dip and strike for a distance of a quarter of a mile1 but the theory of gneiss and mica-schist above proposed requires us to imagine that the same influence has extended through strata miles in thickness4 ,professor ,bischof has shown what changes may be superinduced1 on black marble and other rocks1 by the steam of a hot spring having a temperature of no more than #acc to #afg ,fahrenheit1 and we are becoming more and more acquainted with the prominent part which water is playing in distributing the heat of the interior through mountain masses of incumbent strata1 and of introducing into them various mineral elements in a fluid or gaseous state4 ,such facts may induce us to consider whether many granites and other rocks of that class may not sometimes represent merely the extreme of a similar slow metamorphism4 ,but1 on the other hand1 the heat of lava in a volcanic crater when it is white and glowing like the sun must convince us that the temperature of a column of such a fluid at the depth of many miles exceeds any heat which can ever be witnessed at the surface4 ,that large portions of the ,plutonic rocks had been formed under the influence of such intense heat is in perfect accordance with their great volume1 uniform composition1 and absence of stratification4 ,the forcing also of veins into contiguous stratified or schistose rocks is a natural consequence of the hydrostatic pressure to which columns of molten matter many miles in height must give rise4 ,objections to the ,metamorphic ,theory considered4--,it has been objected to the metamorphic theory that the crystalline schists contain a considerable proportion of potash and soda1 whilst the sedimentary strata out of which they are supposed to have been formed are usually wanting in alkaline matter4 ,but this reasoning proceeds on mistaken data1 for clay1 marl1 shale1 and slate often contain a considerable proportion of alkali1 so much so as to make them frequently unfit to be burnt into bricks or pottery1 and the ,old ,red ,sandstone in ,forfarshire and other parts of ,scotland1 derived from disintegration of granite1 contains much triturated feldspar rich in potash4 ,in the common salt by which strata are often largely impregnated1 as in ,patagonia1 much soda is present1 and potash enters largely into the composition of fossil sea-weeds1 and recent analysis has also shown that the carboniferous strata in ,england1 the ,upper and ,lower ,silurian in ,east ,canada1 and the oldest clay-slates in ,norway1 all contain as much alkali as is generally present in metamorphic rocks4 ,another objection has been derived from the alternation of highly crystalline strata with others less crystalline4 ,the heat1 it is said1 in its ascent from below1 must have traversed the less altered schists before it reached a higher and more crystalline bed4 ,in answer to this1 it may be observed1 that if a number of strata differing greatly in composition from each other be subjected to equal quantities of heat1 or hydrothermal action1 there is every probability that some will be much more fusible or soluble than others4 ,some1 for example1 will contain soda1 potash1 lime1 or some other ingredient capable of acting as a flux or solvent2 while others may be destitute of the same elements1 and so refractory as to be very slightly affected by the same causes4 ,nor should it be forgotten that1 as a general rule1 the less crystalline rocks do really occur in the upper1 and the more crystalline in the lower part of each metamorphic series4 #a ,keilhau1 ,ga ,norvegica1 pp4 #fa-fc4 #b ,geol4 ,manual1 p4 #dgi4 #c ,syst4 of ,geol41 vol4 i1 pp4 #baj1 #baa4 #d ,see ,lyell1 ,quart4 ,geol4 ,journ41 vol4 i1 p4 #aii4 #e ,phil4 ,trans41 #ahjd4 #f ,daubre1 ,sur le ,mtamorphisme4 ,paris1 #ahfj4 #g ,see ,principles1 ,index1 8,carbonated ,springs10 etc4 ,,chapter ,,xxxiv4 ,,metamorphic ,,rocks--continued4 ,definition of slaty ,cleavage and ,joints4 -- ,supposed ,causes of these ,structures4 -- ,crystalline ,theory of ,cleavage4 -- ,mechanical ,theory of ,cleavage4 -- ,condensation and ,elongation of slate ,rocks by lateral ,pressure4 -- ,lamination of some volcanic ,rocks due to ,motion4 -- ,whether the ,foliation of the crystalline ,schists be usually parallel with the original ,planes of ,stratification4 -- ,examples in ,norway and ,scotland4 -- ,causes of ,irregularity in the ,planes of ,foliation4 ,we have already seen that chemical forces of great intensity have frequently acted upon sedimentary and fossiliferous strata long subsequently to their consolidation1 and we may next inquire whether the component minerals of the altered rocks usually arrange themselves in planes parallel to the original planes of stratification1 or whether1 after crystallisation1 they more commonly take up a different position4 ,in order to estimate fairly the merits of this question1 we must first define what is meant by the terms cleavage and foliation4 ,there are four distinct forms of structure exhibited in rocks1 namely1 stratification1 joints1 slaty cleavage1 and foliation2 and all these must have different names1 even though there be cases where it is impossible1 after carefully studying the appearances1 to decide upon the class to which they belong4 ,slaty ,cleavage4--,professor ,sedgwick1 whose essay 8,on the ,structure of large ,mineral ,masses0 first cleared the way towards a better understanding of this difficult subject1 observes1 that joints are distinguishable from lines of slaty cleavage in this1 that the rock intervening between two joints has no tendency to cleave in a direction parallel to the planes of the joints1 whereas a rock is capable of indefinite subdivision in the direction of its slaty cleavage4 ,in cases where the strata are curved1 the planes of cleavage are still perfectly parallel4 ,this has been observed in the slate rocks of part of ,wales 7see ,fig4 #fbd71 which consists of a hard greenish slate4 ,the true bedding is there indicated by a number of parallel stripes1 some of a lighter and some of a darker colour than the general mass4 ,such stripes are found to be parallel to the true planes of stratification1 wherever these are manifested by ripple-mark or by beds containing peculiar organic remains4 ,some of the contorted strata are of a coarse mechanical structure1 alternating with fine-grained crystalline chloritic slates1 in which case the same slaty cleavage extends through the coarser and finer beds1 though it is brought out in greater perfection in proportion as the materials of the rock are fine and homogeneous4 ,it is only when these are very coarse that the cleavage planes entirely vanish4 ,in the ,welsh hills these planes are usually inclined at a very considerable angle to the planes of the strata1 the average angle being as much as from #cj to #dj4 ,sometimes the cleavage planes dip towards the same point of the compass as those of stratification1 but often to opposite points4#a ,the cleavage1 as represented in ,fig4 #fbd1 is generally constant over the whole of any area affected by one great set of disturbances1 as if the same lateral pressure which caused the crumpling up of the rock along parallel1 anticlinal1 and synclinal axes caused also the cleavage4 ,fig4 #fbd3 ,parallel planes of cleavage intersecting curved strata4 ,fig4 #fbe3 ,section in ,lower ,silurian slates of ,cardiganshire1 showing the cleavage planes bent along the junction of the beds4 ,mr4 ,t4 ,mc,k4 ,hughes remarks1 that where a rough cleavage cuts flag-stones at a considerable angle to the planes of stratification1 the rock often splits into large slabs1 across which the lines of bedding are frequently seen1 but when the cleavage planes approach within about #ae of stratification1 the rock is apt to split along the lines of bedding4 ,he has also called my attention to the fact that subsequent movements in a cleaved rock sometimes drag and bend the cleavage planes along the junction of the beds in the manner indicated in ,fig4 #fbe4 ,jointed ,structure4--,in regard to joints1 they are natural fissures which often traverse rocks in straight and well-determined lines4 ,they afford to the quarryman1 as ,sir ,r4 ,murchison observes1 when speaking of the phenomenon1 as exhibited in ,shropshire and the neighbouring counties1 the greatest aid in the extraction of blocks of stone2 and1 if a sufficient number cross each other1 the whole mass of rock is split into symmetrical blocks4 ,the faces of the joints are for the most part smoother and more regular than the surfaces of true strata4 ,the joints are straight-cut chinks1 sometimes slightly open1 and often passing1 not only through layers of successive deposition1 but also through balls of limestone or other matter which have been formed by concretionary action since the original accumulation of the strata4 ,such joints1 therefore1 must often have resulted from one of the last changes superinduced upon sedimentary deposits4#b ,fig4 #fbf3 ,stratification1 joints1 and cleavage4 ,in ,fig4 #fbf the flat-surfaces of rock1 ,a1 ,b1 ,c1 represent exposed faces of joints1 to which the walls of other joints1 ,j ,j1 are parallel4 ,s ,s are the lines of stratification2 ,d ,d are lines of slaty cleavage1 which intersect the rock at a considerable angle to the planes of stratification4 ,in the ,swiss and ,savoy ,alps1 as ,mr4 ,bakewell has remarked1 enormous masses of limestone are cut through so regularly by nearly vertical partings1 and these joints are often so much more conspicuous than the seams of stratification1 that an inexperienced observer will almost inevitably confound them1 and suppose the strata to be perpendicular in places where in fact they are almost horizontal4#c ,now such joints are supposed to be analogous to the partings which separate volcanic and ,plutonic rocks into cuboidal and prismatic masses4 ,on a small scale we see clay and starch when dry split into similar shapes2 this is often caused by simple contraction1 whether the shrinking be due to the evaporation of water1 or to a change of temperature4 ,it is well known that many sandstones and other rocks expand by the application of moderate degrees of heat1 and then contract again on cooling2 and there can be no doubt that large portions of the earth's crust have1 in the course of past ages1 been subjected again and again to very different degrees of heat and cold4 ,these alternations of temperature have probably contributed largely to the production of joints in rocks4 ,in many countries where masses of basalt rest on sandstone1 the aqueous rock has1 for the distance of several feet from the point of junction1 assumed a columnar structure similar to that of the trap4 ,in like manner some hearth-stones1 after exposure to the heat of a furnace without being melted1 have become prismatic4 ,certain crystals also acquire by the application of heat a new internal arrangement1 so as to break in a new direction1 their external form remaining unaltered4 ,crystalline ,theory of ,cleavage4--,professor ,sedgwick1 speaking of the planes of slaty cleavage1 where they are decidedly distinct from those of sedimentary deposition1 declared1 in the essay before alluded to1 his opinion that no retreat of parts1 no contraction in the dimensions of rocks in passing to a solid state1 can account for the phenomenon4 ,he accordingly referred it to crystalline or polar forces acting simultaneously1 and somewhat uniformly1 in given directions1 on large masses having a homogeneous composition4 ,sir ,john ,herschel1 in allusion to slaty cleavage1 has suggested that 8if rocks have been so heated as to allow a commencement of crystallisation--that is to say1 if they have been heated to a point at which the particles can begin to move among themselves1 or at least on their own axes1 some general law must then determine the position in which these particles will rest on cooling4 ,probably1 that position will have some relation to the direction in which the heat escapes4 ,now1 when all1 or a majority of particles of the same nature have a general tendency to one position1 that must of course determine a cleavage-plane4 ,thus we see the infinitesimal crystals of fresh-precipitated sulphate of barytes1 and some other such bodies1 arrange themselves alike in the fluid in which they float2 so as1 when stirred1 all to glance with one light1 and give the appearance of silky filaments4 ,some sorts of soap1 in which insoluble margarates#d exist1 exhibit the same phenomenon when mixed with water2 and what occurs in our experiments on a minute scale may occur in nature on a great one40#e ,mechanical ,theory of ,cleavage4--,professor ,phillips has remarked that in some slaty rocks the form of the outline of fossil shells and trilobites has been much changed by distortion1 which has taken place in a longitudinal1 transverse1 or oblique direction4 ,this change1 he adds1 seems to be the result of a 8creeping movement0 of the particles of the rock along the planes of cleavage1 its direction being always uniform over the same tract of country1 and its amount in space being sometimes measurable1 and being as much as a quarter or even half an inch4 ,the hard shells are not affected1 but only those which are thin4#f ,mr4 ,d4 ,sharpe1 following up the same line of inquiry1 came to the conclusion that the present distorted forms of the shells in certain ,british slate rocks may be accounted for by supposing that the rocks in which they are imbedded have undergone compression in a direction perpendicular to the planes of cleavage1 and a corresponding expansion in the direction of the dip of the cleavage4#g ,subsequently 7#ahec7 ,mr4 ,sorby demonstrated the great extent to which this mechanical theory is applicable to the slate rocks of ,north ,wales and ,devonshire1#h districts where the amount of change in dimensions can be tested and measured by comparing the different effects exerted by lateral pressure on alternating beds of finer and coarser materials4 ,thus1 for example1 in ,fig4 #fbg it will be seen that the sandy bed d f1 which has offered greater resistance1 has been sharply contorted1 while the fine-grained strata1 a1 b1 c1 have remained comparatively unbent4 ,the points d and f in the stratum d f must have been originally four times as far apart as they are now4 ,they have been forced so much nearer to each other1 partly by bending1 and partly by becoming elongated in the direction of what may be called the longer axes of their contortions1 and lastly1 to a certain small amount1 by condensation4 ,the chief result has obviously been due to the bending2 but1 in proof of elongation1 it will be observed that the thickness of the bed d f is now about four times greater in those parts lying in the main direction of the flexures than in a plane perpendicular to them2 and the same bed exhibits cleavage planes in the direction of the greatest movement1 although they are much fewer than in the slaty strata above and below4 ,fig4 #fbg3 ,vertical section of slate rock in the cliffs near ,ilfracombe1 ,north ,devon4 ,above the sandy bed d f1 the stratum c is somewhat disturbed1 while the next bed1 b1 is much less so1 and a not at all2 yet all these beds1 c1 b1 and a1 must have undergone an equal amount of pressure with d1 the points a and g having approximated as much towards each other as have d and f4 ,the same phenomena are also repeated in the beds below d1 and might have been shown1 had the section been extended downward4 ,hence it appears that the finer beds have been squeezed into a fourth of the space they previously occupied1 partly by condensation1 or the closer packing of their ultimate particles 7which has given rise to the great specific gravity of such slates71 and partly by elongation in the line of the dip of the cleavage1 of which the general direction is perpendicular to that of the pressure4 8,these and numerous other cases in ,north ,devon are analogous10 says ,mr4 ,sorby1 8to what would occur if a strip of paper were included in a mass of some soft plastic material which would readily change its dimensions4 ,if the whole were then compressed in the direction of the length of the strip of paper1 it would be bent and puckered up into contortions1 while the plastic material would readily change its dimensions without undergoing such contortions2 and the difference in distance of the ends of the paper1 as measured in a direct line or along it1 would indicate the change in the dimensions of the plastic material40 ,by microscopic examination of minute crystals1 and by other observations1 ,mr4 ,sorby has come to the conclusion that the absolute condensation of the slate rocks amounts upon an average to about one half their original volume4 ,most of the scales of mica occurring in certain slates examined by ,mr4 ,sorby lie in the plane of cleavage2 whereas in a similar rock not exhibiting cleavage they lie with their longer axes in all directions4 ,may not their position in the slates have been determined by the movement of elongation before alluded to8 ,to illustrate this theory some scales of oxide of iron were mixed with soft pipe-clay in such a manner that they inclined in all directions4 ,the dimensions of the mass were then changed artificially to a similar extent to what has occurred in slate rocks1 and the pipe-clay was then dried and baked4 ,when it was afterwards rubbed to a flat surface perpendicular to the pressure and in the line of elongation1 or in a plane corresponding to that of the dip of cleavage1 the particles were found to have become arranged in the same manner as in natural slates1 and the mass admitted of easy fracture into thin flat pieces in the plane alluded to1 whereas it would not yield in that perpendicular to the cleavage4#i ,dr4 ,tyndall1 when commenting in #ahef on ,mr4 ,sorby's experiments1 observed that pressure alone is sufficient to produce cleavage1 and that the intervention of plates of mica or scales of oxide of iron1 or any other substances having flat surfaces1 is quite unnecessary4 ,in proof of this he showed experimentally that a mass of 8pure white wax1 after having been submitted to great pressure1 exhibited a cleavage more clean than that of any slate-rock1 splitting into lamin of surpassing tenuity40#aj ,he remarks that every mass of clay or mud is divided and subdivided by surfaces among which the cohesion is comparatively small4 ,on being subjected to pressure1 such masses yield and spread out in the direction of least resistance1 small nodules become converted into lamin separated from each other by surfaces of weak cohesion1 and the result is that the mass cleaves at right angles to the line in which the pressure is exerted4 ,in further illustration of this1 ,mr4 ,hughes remarks that 8concretions which in the undisturbed beds have their longer axes parallel to the bedding are1 where the rock is much cleaved1 frequently found flattened laterally1 so as to have their longer axes parallel to the cleavage planes1 and at a considerable angle1 even right angles1 to their former position40 ,mr4 ,darwin attributes the lamination and fissile structure of volcanic rocks of the trachytic series1 including some obsidians in ,ascension1 ,mexico1 and elsewhere1 to their having moved when liquid in the direction of the lamin4 ,the zones consist sometimes of layers of air-cells drawn out and lengthened in the supposed direction of the moving mass4#aa ,foliation of ,crystalline ,schists4--,after studying1 in #ahce1 the crystalline rocks of ,south ,america1 ,mr4 ,darwin proposed the term foliation for the lamin or plates into which gneiss1 mica-schist1 and other crystalline rocks are divided4 ,cleavage1 he observes1 may be applied to those divisional planes which render a rock fissile1 although it may appear to the eye quite or nearly homogeneous4 ,foliation may be used for those alternating layers or plates of different mineralogical nature of which gneiss and other metamorphic schists are composed4 ,that the planes of foliation of the crystalline schists in ,norway accord very generally with those of original stratification is a conclusion long since espoused by ,keilhau4#ab ,numerous observations made by ,mr4 ,david ,forbes in the same country 7the best probably in ,europe for studying such phenomena on a grand scale7 confirm ,keilhau's opinion4 ,in ,scotland1 also1 ,mr4 ,d4 ,forbes has pointed out a striking case where the foliation is identical with the lines of stratification in rocks well seen near ,crianlorich on the road to ,tyndrum1 about eight miles from ,inverarnon1 in ,perthshire4 ,there is in that locality a blue limestone foliated by the intercalation of small plates of white mica1 so that the rock is often scarcely distinguishable in aspect from gneiss or mica-schist4 ,the stratification is shown by the large beds and coloured bands of limestone all dipping1 like the folia1 at an angle of #cb ,n4,e4#ac ,in stratified formations of every age we see layers of siliceous sand with or without mica1 alternating with clay1 with fragments of shells or corals1 or with seams of vegetable matter1 and we should expect the mutual attraction of like particles to favour the crystallisation of the quartz1 or mica1 or feldspar1 or carbonate of lime1 along the planes of original deposition1 rather than in planes placed at angles of #bj or #dj degrees to those of stratification4 ,we have seen how much the original planes of stratification may be interfered with or even obliterated by concretionary action in deposits still retaining their fossils1 as in the case of the magnesian limestone 7see p4 #fc74 ,hence we must expect to be frequently baffled when we attempt to decide whether the foliation does or does not accord with that arrangement which gravitation1 combined with current-action1 imparted to a deposit from water4 ,moreover1 when we look for stratification in crystalline rocks1 we must be on our guard not to expect too much regularity4 ,the occurrence of wedge-shaped masses1 such as belong to coarse sand and pebbles--diagonal lamination 7p4 #db7--ripple-marked1 unconformable stratification1--the fantastic folds produced by lateral pressure--faults of various width--intrusive dikes of trap--organic bodies of diversified shapes1 and other causes of unevenness in the planes of deposition1 both on the small and on the large scale1 will interfere with parallelism4 ,if complex and enigmatical appearances did not present themselves1 it would be a serious objection to the metamorphic theory4 ,mr4 ,sorby has shown that the peculiar structure belonging to ripple-marked sands1 or that which is generated when ripples are formed during the deposition of the materials1 is distinctly recognisable in many varieties of mica-schists in ,scotland4#ad ,fig4 #fbh3 ,lamination of clay-stone4 ,montagne de ,seguinat1 near ,gavarnie1 in the ,pyrenees4 ,in ,fig4 #fbh ,i have represented carefully the lamination of a coarse argillaceous schist which ,i examined in #ahcj in the ,pyrenees4 ,in part it approaches in character to a green and blue roofing-slate1 while part is extremely quartzose1 the whole mass passing downward into micaceous schist4 ,the vertical section here exhibited is about three feet in height1 and the layers are sometimes so thin that fifty may be counted in the thickness of an inch4 ,some of them consist of pure quartz4 ,there is a resemblance in such cases to the diagonal lamination which we see in sedimentary rocks1 even though the layers of quartz and of mica1 or of feldspar and other minerals1 may be more distinct in alternating folia than they were originally4 #a ,geol4 ,trans41 #bnd series1 vol4 iii1 p4 #dfa4 #b ,silurian ,system1 p4 #bdf4 #c ,introduction to ,geology1 chap4 iv4 #d ,margaric acid is an oleaginous acid1 formed from different animal and vegetable fatty substances4 ,a margarate is a compound of this acid with soda1 potash1 or some other base1 and is so named from its pearly lustre4 #e ,letter to the author1 dated ,cape of ,good ,hope1 ,feb4 #bj1 #ahcf4 #f ,report1 ,brit4 ,assoc41 ,cork1 #ahdc1 ,sect4 p4 #fj4 #g ,quart4 ,geol4 ,journ41 vol4 iii1 p4 #hg1 #ahdg4 #h ,on the ,origin of ,slaty ,cleavage1 by ,h4 ,c4 ,sorby1 ,edin4 ,new ,phil4 ,journ41 #ahec1 vol4 lv1 p4 #acg4 #i ,sorby1 as cited above1 p4 #gda1 note4 #aj ,tyndall1 ,view of the ,cleavage of ,crystals and ,slate rocks4 #aa ,darwin1 ,volcanic ,islands1 pp4 #fi1 #gj4 #ab ,norske ,mag4 ,naturvidsk41 vol4 i1 p4 #ga4 #ac ,memoir read before the ,geol4 ,soc4 ,london1 ,jan4 #ca1 #ahee4 #ad ,h4 ,c4 ,sorby1 ,quart4 ,geol4 ,journ41 vol4 xix41 p4 #dja4 ,,chapter ,,xxxv4 ,,on ,,the ,,different ,,ages ,,of ,,the ,,metamorphic ,,rocks4 ,difficulty of ascertaining the ,age of metamorphic ,strata4 -- ,metamorphic ,strata of ,eocene date in the ,alps of ,switzerland and ,savoy4 -- ,limestone and ,shale of ,carrara4 -- ,metamorphic ,strata of older date than the ,silurian and ,cambrian ,rocks4 -- ,order of ,succession in metamorphic ,rocks4 -- ,uniformity of mineral ,character4 -- ,supposed ,azoic ,period4 -- ,connection between the ,absence of ,organic ,remains and the ,scarcity of calcareous ,matter in metamorphic ,rocks4 ,according to the theory adopted in the last chapter1 the metamorphic strata have been deposited at one period1 and have become crystalline at another4 ,we can rarely hope to define with exactness the date of both these periods1 the fossils having been destroyed by ,plutonic action1 and the mineral characters being the same1 whatever the age4 ,superposition itself is an ambiguous test1 especially when we desire to determine the period of crystallisation4 ,suppose1 for example1 we are convinced that certain metamorphic strata in the ,alps1 which are covered by cretaceous beds1 are altered lias2 this lias may have assumed its crystalline texture in the cretaceous or in some tertiary period1 the ,eocene for example4 ,when discussing the ages of the ,plutonic rocks1 we have seen that examples occur of various primary1 secondary1 and tertiary deposits converted into metamorphic strata near their contact with granite4 ,there can be no doubt in these cases that strata once composed of mud1 sand1 and gravel1 or of clay1 marl1 and shelly limestone1 have for the distance of several yards1 and in some instances several hundred feet1 been turned into gneiss1 mica-schist1 hornblende-schist1 chlorite-schist1 quartz rock1 statuary marble1 and the rest4 7,see the two preceding chapters47 ,it may be easy to prove the identity of two different parts of the same stratum2 one1 where the rock has been in contact with a volcanic or ,plutonic mass1 and has been changed into marble or hornblende-schist1 and another not far distant1 where the same bed remains unaltered and fossiliferous2 but when hydrothermal action1 as described in ,chapter ,,xxxiii1 has operated gradually on a more extensive scale1 it may have finally destroyed all monuments of the date of its development throughout a whole mountain chain1 and all the labour and skill of the most practised observers are required1 and may sometimes be at fault4 ,i shall mention one or two examples of alteration on a grand scale1 in order to explain to the student the kind of reasoning by which we are led to infer that dense masses of fossiliferous strata have been converted into crystalline rocks4 ,eocene ,strata rendered metamorphic in the ,alps4--,in the eastern part of the ,alps1 some of the ,palozoic strata1 as well as the older ,mesozoic formations1 including the oolitic and cretaceous rocks1 are distinctly recognisable4 ,tertiary deposits also appear in a less elevated position on the flanks of the ,eastern ,alps2 but in the ,central or ,swiss ,alps1 the ,palozoic and older ,mesozoic formations disappear1 and the ,cretaceous1 ,oolitic1 ,liassic1 and at some points even the ,eocene strata1 graduate insensibly into metamorphic rocks1 consisting of granular limestone1 talc-schist1 talcose-gneiss1 micaceous schist1 and other varieties4 ,as an illustration of the partial conversion into gneiss of portions of a highly inclined set of beds1 ,i may cite ,sir ,r4 ,murchison's memoir on the structure of the ,alps4 ,slates provincially termed 8flysch0 7see p4 #bgh71 overlying the nummulite limestone of ,eocene date1 and comprising some arenaceous and some calcareous layers1 are seen to alternate several times with bands of granitoid rock1 answering in character to gneiss4 ,in this case heat1 vapour1 or water at a high temperature may have traversed the more permeable beds1 and altered them so far as to admit of an internal movement and re-arrangement of the molecules1 while the adjoining strata did not give passage to the same heated gases or water1 or1 if so1 remained unchanged because they were composed of less fusible or decomposable materials4 ,whatever hypothesis we adopt1 the phenomena establish beyond a doubt the possibility of the development of the metamorphic structure in a tertiary deposit in planes parallel to those of stratification4 ,the strata appear clearly to have been affected1 though in a less intense degree1 by that same ,plutonic action which has entirely altered and rendered metamorphic so many of the subjacent formations2 for in the ,alps this action has by no means been confined to the immediate vicinity of granite4 ,granite1 indeed1 and other ,plutonic rocks1 rarely make their appearance at the surface1 notwithstanding the deep ravines which lay open to view the internal structure of these mountains4 ,that they exist below at no great depth we cannot doubt1 for at some points1 as in the ,valorsine1 near ,mont ,blanc1 granite and granitic veins are observable1 piercing through talcose gneiss1 which passes insensibly upward into secondary strata4 ,it is certainly in the ,alps of ,switzerland and ,savoy1 more than in any other district in ,europe1 that the geologist is prepared to meet with the signs of an intense development of ,plutonic action2 for here strata thousands of feet thick have been bent1 folded1 and overturned1 and marine secondary formations of a comparatively modern date1 such as the ,oolitic and ,cretaceous1 have been upheaved to the height of #ab1jjj1 and some ,eocene strata to elevations of #aj1jjj feet above the level of the sea2 and even deposits of the ,miocene era have been raised #djjj or #ejjj feet1 so as to rival in height the loftiest mountains in ,great ,britain4 ,in one of the sections described by ,m4 ,studer in the highest of the ,bernese ,alps1 namely in the ,roththal1 a valley bordering the line of perpetual snow on the northern side of the ,jungfrau1 there occurs a mass of gneiss #ajjj feet thick1 and #ae1jjj feet long1 which ,i examined1 not only resting upon1 but also again covered by strata containing oolitic fossils4 ,these anomalous appearances may partly be explained by supposing great solid wedges of intrusive gneiss to have been forced in laterally between strata to which ,i found them to be in many sections unconformable4 ,the superposition1 also1 of the gneiss to the oolite may1 in some cases1 be due to a reversal of the original position of the beds in a region where the convulsions have been on so stupendous a scale4 ,northern ,apennines4--,carrara4--,the celebrated marble of ,carrara1 used in sculpture1 was once regarded as a type of primitive limestone4 ,it abounds in the mountains of ,massa ,carrara1 or the 8,apuan ,alps10 as they have been called1 the highest peaks of which are nearly #fjjj feet high4 ,its great antiquity was inferred from its mineral texture1 from the absence of fossils1 and its passage downward into talc-schist and garnetiferous mica-schist2 these rocks again graduating downward into gneiss1 which is penetrated1 at ,forno1 by granite veins4 ,but the researches of ,,mm4 ,savi1 ,bou1 ,pareto1 ,guidoni1 ,de la ,beche1 ,hoffman1 and ,pilla demonstrated that this marble1 once supposed to be formed before the existence of organic beings1 is1 in fact1 an altered limestone of the ,oolitic period1 and the underlying crystalline schists are secondary sandstones and shales1 modified by ,plutonic action4 ,in order to establish these conclusions it was first pointed out that the calcareous rocks bordering the ,gulf of ,spezia1 and abounding in ,oolitic fossils1 assume a texture like that of ,carrara marble1 in proportion as they are more and more invaded by certain trappean and ,plutonic rocks1 such as diorite1 serpentine1 and granite1 occurring in the same country4 ,it was then observed that1 in places where the secondary formations are unaltered1 the uppermost consist of common ,apennine limestone with nodules of flint1 below which are shales1 and at the base of all1 argillaceous and siliceous sandstones4 ,in the limestone fossils are frequent1 but very rare in the underlying shale and sandstone4 ,then a gradation was traced laterally from these rocks into another and corresponding series1 which is completely metamorphic2 for at the top of this we find a white granular marble1 wholly devoid of fossils1 and almost without stratification1 in which there are no nodules of flint1 but in its place siliceous matter disseminated through the mass in the form of prisms of quartz4 ,below this1 and in place of the shales1 are talc-schists1 jasper1 and hornstone2 and at the bottom1 instead of the siliceous and argillaceous sandstones1 are quartzite and gneiss4#a ,had these secondary strata of the ,apennines undergone universally as great an amount of transmutation1 it would have been impossible to form a conjecture respecting their true age2 and then1 according to the method of classification adopted by the earlier geologists1 they would have ranked as primary rocks4 ,in that case the date of their origin would have been thrown back to an era antecedent to the deposition of the ,lower ,silurian or ,cambrian strata1 although in reality they were formed in the ,oolitic period1 and altered at some subsequent and perhaps much later epoch4 ,metamorphic ,strata of older date than the ,silurian and ,cambrian ,rocks4--,it was remarked 7,fig4 #fag7 that as the hypogene rocks1 both stratified and unstratified1 crystallise originally at a certain depth beneath the surface1 they must always1 before they are upraised and exposed at the surface1 be of considerable antiquity1 relatively to a large portion of the fossiliferous and volcanic rocks4 ,they may be forming at all periods2 but before any of them can become visible1 they must be raised above the level of the sea1 and some of the rocks which previously concealed them must have been removed by denudation4 ,in ,canada1 as we have seen 7p4 #dia71 the ,lower ,laurentian gneiss1 quartzite1 and limestone may be regarded as metamorphic1 because1 among other reasons1 organic remains 7,eozoon ,canadense7 have been detected in a part of one of the calcareous masses4 ,the ,upper ,laurentian or ,labrador series lies unconformably upon the ,lower1 and differs from it chiefly in having as yet yielded no fossils4 ,it consists of gneiss with ,labrador-feldspar and feldstones1 in all #aj1jjj feet thick1 and both its composition and structure lead us to suppose that1 like the ,lower ,laurentian1 it was originally of sedimentary origin and owes its crystalline condition to metamorphic action4 ,the remote date of the period when some of these old ,laurentian strata of ,canada were converted into gneiss may be inferred from the fact that pebbles of that rock are found in the overlying ,huronian formation1 which is probably of ,cambrian age 7p4 #dij74 ,the oldest stratified rock of ,scotland is the hornblendic gneiss of ,lewis1 in the ,hebrides1 and that of the north-west coast of ,ross-shire1 represented at the base of the section given at ,fig4 #hb4 ,it is the same as that intersected by numerous granite veins which forms the cliffs of ,cape ,wrath1 in ,sutherlandshire 7see ,fig4 #fac71 and is conjectured to be of ,laurentian age4 ,above it1 as shown in the section 7,fig4 #hb71 lie unconformable beds of a reddish or purple sandstone and conglomerate1 nearly horizontal1 and between #cjjj and #djjj feet thick4 ,in these ancient grits no fossils have been found1 but they are supposed to be of ,cambrian date1 for ,sir ,r4 ,murchison found ,lower ,silurian strata resting unconformably upon them4 ,these strata consist of quartzite with annelid burrows already alluded to 7p4 #aab71 and limestone in which ,mr4 ,charles ,peach was the first to find1 in #ahed1 three or four species of ,orthoceras1 also the genera ,cyrtoceras and ,lituites1 two species of ,murchisonia1 a ,pleurotomaria1 a species of ,maclurea1 one of ,euomphalus1 and an ,orthis4 ,several of the species are believed by ,mr4 ,salter to be identical with ,lower ,silurian fossils of ,canada and the ,united ,states4 ,the discovery of the true age of these fossiliferous rocks was one of the most important steps made of late years in the progress of ,british ,geology1 for it led to the unexpected conclusion that all the ,scotch crystalline strata to the eastward1 once called primitive1 which overlie the limestone and quartzite in question1 are referable to some part of the ,silurian series4 ,these ,scotch metamorphic strata are of gneiss1 mica-schist1 and clay-slate of vast thickness1 and having a strike from north-east to south-west almost at right angles to that of the older ,laurentian gneiss before mentioned4 ,the newer crystalline series1 comprising the crystalline rocks of ,aberdeenshire1 ,perthshire1 and ,forfarshire1 were inferred by ,sir ,r4 ,murchison to be altered ,silurian strata2 and his opinion has been since confirmed by the observations of three able geologists1 ,messrs4 ,ramsay1 ,harkness1 and ,geikie4 ,the newest of the series is a clay-slate1 on which1 along the southern borders of the ,grampians1 the ,lower ,old ,red1 containing ,cephalaspis ,lyelli1 ,pterygotus ,anglicus1 and ,parka decipiens1 rests unconformably4 ,order of ,succession in ,metamorphic ,rocks4--,there is no universal and invariable order of superposition in metamorphic rocks1 although a particular arrangement may prevail throughout countries of great extent1 for the same reason that it is traceable in those sedimentary formations from which crystalline strata are derived4 ,thus1 for example1 we have seen that in the ,apennines1 near ,carrara1 the descending series1 where it is metamorphic1 consists of1 first1 saccharine marble2 second1 talcose-schist2 and third1 of quartz-rock and gneiss3 where unaltered1 of1 first1 fossiliferous limestone2 second1 shale2 and third1 sandstone4 ,but if we investigate different mountain chains1 we find gneiss1 mica-schist1 hornblende-schist1 chlorite-schist1 hypogene limestone1 and other rocks1 succeeding each other1 and alternating with each other in every possible order4 ,it is1 indeed1 more common to meet with some variety of clay-slate forming the uppermost member of a metamorphic series than any other rock2 but this fact by no means implies1 as some have imagined1 that all clay-slates were formed at the close of an imaginary period when the deposition of the crystalline strata gave way to that of ordinary sedimentary deposits4 ,such clay-slates1 in fact1 are variable in composition1 and sometimes alternate with fossiliferous strata1 so that they may be said to belong almost equally to the sedimentary and metamorphic order of rocks4 ,it is probable that1 had they been subjected to more intense ,plutonic action1 they would have been transformed into hornblende-schist1 foliated chlorite-schist1 scaly talcose-schist1 mica-schist1 or other more perfectly crystalline rocks1 such as are usually associated with gneiss4 ,uniformity of ,mineral ,character in ,hypogene ,rocks4--,it is true1 as ,humboldt has happily remarked1 that when we pass to another hemisphere1 we see new forms of animals and plants1 and even new constellations in the heavens2 but in the rocks we still recognise our old acquaintances--the same granite1 the same gneiss1 the same micaceous schist1 quartz-rock1 and the rest4 ,there is certainly a great and striking general resemblance in the principal kinds of hypogene rocks in all countries1 however different their ages2 but each of them1 as we have seen1 must be regarded as geological families of rocks1 and not as definite mineral compounds4 ,they are more uniform in aspect than sedimentary strata1 because these last are often composed of fragments varying greatly in form1 size1 and colour1 and contain fossils of different shapes and mineral composition1 and acquire a variety of tints from the mixture of various kinds of sediment4 ,the materials of such strata1 if they underwent metamorphism1 would be subject to chemical laws1 simple and uniform in their action1 the same in every climate1 and wholly undisturbed by mechanical and organic causes4 ,it would1 however1 be a great error to assume1 as some have done1 that the hypogene rocks1 considered as aggregates of simple minerals1 are really more homogeneous in their composition than the several members of the sedimentary series4 ,not only do the proportional quantities of feldspar1 quartz1 mica1 hornblende1 and other minerals1 vary in hypogene rocks bearing the same name2 but what is still more important1 the ingredients1 as we have seen1 of the same simple mineral are not always constant 7see p4 #ejc and table1 p4 #dii74 ,supposed ,azoic ,period4--,the total absence of any trace of fossils has inclined many geologists to attribute the origin of the most ancient strata to an azoic period1 or one antecedent to the existence of organic beings4 ,admitting1 they say1 the obliteration1 in some cases1 of fossils by ,plutonic action1 we might still expect that traces of them would oftener be found in certain ancient systems of slate which can scarcely be said to have assumed a crystalline structure4 ,but in urging this argument it seems to have been forgotten that there are stratified formations of enormous thickness1 and of various ages1 some of them even of ,tertiary date1 and which we know were formed after the earth had become the abode of living creatures1 which are1 nevertheless1 in some districts1 entirely destitute of all vestiges of organic bodies4 ,in some1 the traces of fossils may have been effaced by water and acids1 at many successive periods2 indeed the removal of the calcareous matter of fossil shells is proved by the fact of such organic remains being often replaced by silex or other minerals1 and sometimes by the space once occupied by the fossil being left empty1 or only marked by a faint impression4 ,those who believed the hypogene rocks to have originated antecedently to the creation of organic beings1 imputed the absence of lime1 so remarkable in metamorphic strata1 to the non-existence of those mollusca and zoophytes by which shells and corals are secreted2 but when we ascribe the crystalline formations to ,plutonic action1 it is natural to inquire whether this action itself may not tend to expel carbonic acid and lime from the materials which it reduces to fusion or semi-fusion4 ,not only carbonate of lime1 but also free carbonic acid gas1 is given off plentifully from the soil and crevices of rocks in regions of active and spent volcanoes1 as near ,naples and in ,auvergne4 ,by this process1 fossil shells or corals may often lose their carbonic acid1 and the residual lime may enter into the composition of augite1 hornblende1 garnet1 and other hypogene minerals4 ,although we cannot descend into the subterranean regions where volcanic heat is developed1 we can observe in regions of extinct volcanoes1 such as ,auvergne and ,tuscany1 hundreds of springs1 both cold and thermal1 flowing out from granite and other rocks1 and having their waters plentifully charged with carbonate of lime4 ,if all the calcareous matter transferred in the course of ages by these and thousands of other springs from the lower part of the earth's crust to the atmosphere could be presented to us in a solid form1 we should find that its volume was comparable to that of many a chain of hills4 ,calcareous matter is poured into lakes and the ocean by a thousand springs and rivers2 so that part of almost every new calcareous rock chemically precipitated1 and of many reefs of shelly and coralline stone1 must be derived from mineral matter subtracted by ,plutonic agency1 and driven up by gas and steam from fused and heated rocks in the bowels of the earth4 ,the scarcity of limestone in many extensive regions of metamorphic rocks1 as in the ,eastern and ,southern ,grampians of ,scotland1 may have been the result of some action of this kind2 and if the limestones of the ,lower ,laurentian in ,canada afford a remarkable exception to the general rule1 we must not forget that it is precisely in this most ancient formation that the ,eozoon ,canadense has been found4 ,the fact that some distinct bands of limestone from #gjj to #aejj feet thick occur here1 may be connected with the escape from destruction of some few traces of organic life1 even in a rock in which metamorphic action has gone so far as to produce serpentine1 augite1 and other minerals found largely intermixed with the carbonate of lime4 #a ,see notices of ,savi1 ,hoffman1 and others1 referred to by ,bou1 ,bull4 de la ,soc4 ,gol4 de ,france1 tome v1 p4 #cag and tome iii1 p4 #dd2 also ,pilla1 cited by ,murchison1 ,quart4 ,geol4 ,journ41 vol4 v1 p4 #bff4 ,,chapter ,,xxxvi4 ,,mineral ,,veins4 ,different ,kinds of mineral ,veins4 -- ,ordinary metalliferous ,veins or ,lodes4 -- ,their frequent ,coincidence with ,faults4 -- ,proofs that they originated in ,fissures in solid ,rock4 -- ,veins shifting other ,veins4 -- ,polishing of their ,walls or 8,slicken sides40 ,shells and ,pebbles in ,lodes4 -- ,evidence of the successive ,enlargement and ,reopening of veins4 -- ,examples in ,cornwall and in ,auvergne4 -- ,dimensions of ,veins4 -- ,why some alternately swell out and contract4 -- ,filling of ,lodes by ,sublimation from below4 -- ,supposed relative ,age of the precious ,metals4 -- ,copper and lead ,veins in ,ireland older than ,cornish ,tin4 -- ,lead ,vein in ,lias1 ,glamorganshire4 -- ,gold in ,russia1 ,california1 and ,australia4 -- ,connection of hot ,springs and mineral ,veins4 ,the manner in which metallic substances are distributed through the earth's crust1 and more especially the phenomena of those more or less connected masses of ore called mineral veins1 from which the larger part of the precious metals used by man are obtained1 are subjects of the highest practical importance to the miner1 and of no less theoretical interest to the geologist4 ,on different ,kinds of ,mineral ,veins4--,the mineral veins with which we are most familiarly acquainted are those of quartz and carbonate of lime1 which are often observed to form lenticular masses of limited extent traversing both hypogene strata and fossiliferous rocks4 ,such veins appear to have once been chinks or small cavities1 caused1 like cracks in clay1 by the shrinking of the mass1 during desiccation1 or in passing from a higher to a lower temperature4 ,siliceous1 calcareous1 and occasionally metallic matters have sometimes found their way simultaneously into such empty spaces1 by infiltration from the surrounding rocks4 ,mixed with hot water and steam1 metallic ores may have permeated the mass until they reached those receptacles formed by shrinkage1 and thus gave rise to that irregular assemblage of veins1 called by the ,germans a 8stockwerk10 in allusion to the different floors on which the mining operations are in such cases carried on4 ,the more ordinary or regular veins are usually worked in vertical shafts1 and have evidently been fissures produced by mechanical violence4 ,they traverse all kinds of rocks1 both hypogene and fossiliferous1 and extend downward to indefinite or unknown depths4 ,we may assume that they correspond with such rents as we see caused from time to time by the shock of an earthquake4 ,metalliferous veins referable to such agency are occasionally a few inches wide1 but more commonly three or four feet4 ,they hold their course continuously in a certain prevailing direction for miles or leagues1 passing through rocks varying in mineral composition4 ,that ,metalliferous ,veins were ,fissures4--,as some intelligent miners1 after an attentive study of metalliferous veins1 have been unable to reconcile many of their characteristics with the hypothesis of fissures1 ,i shall begin by stating the evidence in its favour4 ,the most striking fact1 perhaps1 which can be adduced in its support is1 the coincidence of a considerable proportion of mineral veins with faults1 or those dislocations of rocks which are indisputably due to mechanical force1 as above explained 7p4 #hg74 ,there are even proofs in almost every mining district of a succession of faults1 by which the opposite walls of rents1 now the receptacles of metallic substances1 have suffered displacement4 ,thus1 for example1 suppose a a1 ,fig4 #fbi1 to be a tin lode in ,cornwall1 the term lode being applied to veins containing metallic ores4 ,this lode1 running east and west1 is a yard wide1 and is shifted by a copper lode 7b b7 of similar width4 ,the first fissure 7a a7 has been filled with various materials1 partly of chemical origin1 such as quartz1 fluor-spar1 peroxide of tin1 sulphuret of copper1 arsenical pyrites1 bismuth1 and sulphuret of nickel1 and partly of mechanical origin1 comprising clay and angular fragments or detritus of the intersected rocks4 ,the plates of quartz and the ores are1 in some places1 parallel to the vertical sides or walls of the vein1 being divided from each other by alternating layers of clay or other earthy matter4 ,occasionally the metallic ores are disseminated in detached masses among the vein-stones4 ,it is clear that1 after the gradual introduction of the tin and other substances1 the second rent 7b b7 was produced by another fracture accompanied by a displacement of the rocks along the plane of b b4 ,this new opening was then filled with minerals1 some of them resembling those in a a1 as fluor-spar 7or fluate of lime7 and quartz2 others different1 the copper being plentiful and the tin wanting or very scarce4 ,we must next suppose a third movement to occur1 breaking asunder all the rocks along the line c c1 ,fig4 #fcj2 the fissure1 in this instance1 being only six inches wide1 and simply filled with clay1 derived1 probably1 from the friction of the walls of the rent1 or partly1 perhaps1 washed in from above4 ,this new movement has displaced the rock in such a manner as to interrupt the continuity of the copper vein 7b b71 and1 at the same time1 to shift or heave laterally in the same direction a portion of the tin vein which had not previously been broken4 ,vertical sections of the mine at ,huel ,peever1 ,redruth1 ,cornwall4 ,fig4 #fbi3 ,tin2 ,fig4 #fcj3 ,copper2 ,fig4 #fca3 ,clay4 ,again1 in ,fig4 #fca we see evidence of a fourth fissure 7d d71 also filled with clay1 which has cut through the tin vein 7a a71 and has lifted it slightly upward towards the south4 ,the various changes here represented are not ideal1 but are exhibited in a section obtained in working an old ,cornish mine1 long since abandoned1 in the parish of ,redruth1 called ,huel ,peever1 and described both by ,mr4 ,williams and ,mr4 ,carne4#a ,the principal movement here referred to1 or that of c c1 ,fig4 #fca1 extends through a space of no less than #hd feet2 but in this1 as in the case of the other three1 it will be seen that the outline of the country above1 d1 c1 b1 a1 etc41 or the geographical features of ,cornwall1 are not affected by any of the dislocations1 a powerful denuding force having clearly been exerted subsequently to all the faults4 7,see p4 #ic47 ,it is commonly said in ,cornwall1 that there are eight distinct systems of veins1 which can in like manner be referred to as many successive movements or fractures2 and the ,german miners of the ,hartz ,mountains speak also of eight systems of veins1 referable to as many periods4 ,besides the proofs of mechanical action already explained1 the opposite walls of veins are often beautifully polished1 as if glazed1 and are not unfrequently striated or scored with parallel furrows and ridges1 such as would be produced by the continued rubbing together of surfaces of unequal hardness4 ,these smoothed surfaces resemble the rocky floor over which a glacier has passed 7see ,fig4 #ajf74 ,they are common even in cases where there has been no shift1 and occur equally in non-metalliferous fissures4 ,they are called by miners 8slicken-sides10 from the ,german schlichten1 to plane1 and seite1 side4 ,it is supposed that the lines of the stri indicate the direction in which the rocks were moved4 ,in some of the veins in the mountain limestone of ,derbyshire1 containing lead1 the vein-stuff1 which is nearly compact1 is occasionally traversed by what may be called a vertical crack passing down the middle of the vein4 ,the two faces in contact are slicken-sides1 well polished and fluted1 and sometimes covered by a thin coating of lead-ore4 ,when one side of the vein-stuff is removed1 the other side cracks1 especially if small holes be made in it1 and fragments fly off with loud explosions1 and continue to do so for some days4 ,the miner1 availing himself of this circumstance1 makes with his pick small holes about six inches apart1 and four inches deep1 and on his return in a few hours finds every part ready broken to his hand4#b ,that a great many veins communicated originally with the surface of the country above1 or with the bed of the sea1 is proved by the occurrence in them of well-rounded pebbles1 agreeing with those in superficial alluviums1 as in ,auvergne and ,saxony4 ,marine fossil shells1 also1 have been found at great depths1 having probably been ingulfed during submarine earthquakes4 ,thus1 a grypha is stated by ,m4 ,virlet to have been met with in a lead-mine near ,semur1 in ,france1 and a madrepore in a compact vein of cinnabar in ,hungary4#c ,in ,bohemia1 similar pebbles have been met with at the depth of #ahj fathoms2 and in ,cornwall1 ,mr4 ,carne mentions true pebbles of quartz and slate in a tin lode of the ,relistran ,mine1 at the depth of #fjj feet below the surface4 ,they were cemented by oxide of tin and bisulphuret of copper1 and were traced over a space more than twelve feet long and as many wide4#d ,when different sets or systems of veins occur in the same country1 those which are supposed to be of contemporaneous origin1 and which are filled with the same kind of metals1 often maintain a general parallelism of direction4 ,thus1 for example1 both the tin and copper veins in ,cornwall run nearly east and west1 while the lead veins run north and south2 but there is no general law of direction common to different mining districts4 ,the parallelism of the veins is another reason for regarding them as ordinary fissures1 for we observe that faults and trap dikes1 admitted by all to be masses of melted matter which have filled rents1 are often parallel4 ,fracture1 ,re-opening and ,successive ,formation of ,veins4--,assuming1 then1 that veins are simply fissures in which chemical and mechanical deposits have accumulated1 we may next consider the proofs of their having been filled gradually and often during successive enlargements4 ,werner observed1 in a vein near ,gersdorff1 in ,saxony1 no less than thirteen beds of different minerals1 arranged with the utmost regularity on each side of the central layer4 ,this layer was formed of two plates of calcareous spar1 which had evidently lined the opposite walls of a vertical cavity4 ,the thirteen beds followed each other in corresponding order1 consisting of fluor-spar1 heavy spar1 galena1 etc4 ,in these cases the central mass has been last formed1 and the two plates which coat the walls of the rent on each side are the oldest of all4 ,if they consist of crystalline precipitates1 they may be explained by supposing the fissure to have remained unaltered in its dimensions1 while a series of changes occurred in the nature of the solutions which rose up from below3 but such a mode of deposition1 in the case of many successive and parallel layers1 appears to be exceptional4 ,if a vein-stone consist of crystalline matter1 the points of the crystals are always turned inward1 or towards the centre of the vein2 in other words1 they point in the direction where there was space for the development of the crystals4 ,thus each new layer receives the impression of the crystals of the preceding layer1 and imprints its crystals on the one which follows1 until at length the whole of the vein is filled3 the two layers which meet dovetail the points of their crystals the one into the other4 ,but in ,cornwall1 some lodes occur where the vertical plates1 or combs1 as they are there called1 exhibit crystals so dovetailed as to prove that the same fissure has been often enlarged4 ,sir ,h4 ,de la ,beche gives the following curious and instructive example 7,fig4 #fcb71 from a copper-mine in granite1 near ,redruth4#e ,each of the plates or combs 7a1 b1 c1 d1 e1 f7 is double1 having the points of their crystals turned inward along the axis of the comb4 ,the sides or walls 7#b1 #c1 #d1 #e and #f7 are parted by a thin covering of ochreous clay1 so that each comb is readily separable from another by a moderate blow of the hammer4 ,the breadth of each represents the whole width of the fissure at six successive periods1 and the outer walls of the vein1 where the first narrow rent was formed1 consisted of the granitic surfaces #a and #g4 ,fig4 #fcb3 ,copper lode1 near ,redruth1 enlarged at six successive periods4 ,a somewhat analogous interpretation is applicable to many other cases1 where clay1 sand1 or angular detritus1 alternate with ores and vein-stones4 ,thus1 we may imagine the sides of a fissure to be incrusted with siliceous matter1 as ,von ,buch observed1 in ,lancerote1 the walls of a volcanic crater formed in #agca to be traversed by an open rent in which hot vapours had deposited hydrate of silica1 the incrustation nearly extending to the middle4#f ,such a vein may then be filled with clay or sand1 and afterwards re-opened1 the new rent dividing the argillaceous deposit1 and allowing a quantity of rubbish to fall down4 ,various metals and spars may then be precipitated from aqueous solutions among the interstices of this heterogeneous mass4 ,that such changes have repeatedly occurred1 is demonstrated by occasional cross-veins1 implying the oblique fracture of previously formed chemical and mechanical deposits4 ,thus1 for example1 ,m4 ,fournet1 in his description of some mines in ,auvergne worked under his superintendence1 observes that the granite of that country was first penetrated by veins of granite1 and then dislocated1 so that open rents crossed both the granite and the granitic veins4 ,into such openings1 quartz1 accompanied by sulphurets of iron and arsenical pyrites1 was introduced4 ,another convulsion then burst open the rocks along the old line of fracture1 and the first set of deposits were cracked and often shattered1 so that the new rent was filled1 not only with angular fragments of the adjoining rocks1 but with pieces of the older vein-stones4 ,polished and striated surfaces on the sides or in the contents of the vein also attest the reality of these movements4 ,a new period of repose then ensued1 during which various sulphurets were introduced1 together with hornstone quartz1 by which angular fragments of the older quartz before mentioned were cemented into a breccia4 ,this period was followed by other dilatations of the same veins1 and the introduction of other sets of mineral deposits1 as well as of pebbles of the basaltic lavas of ,auvergne1 derived from superficial alluviums1 probably of ,miocene or even ,older ,pliocene date4 ,such repeated enlargement and re-opening of veins might have been anticipated1 if we adopt the theory of fissures1 and reflect how few of them have ever been sealed up entirely1 and that a country with fissures only partially filled must naturally offer much feebler resistance along the old lines of fracture than anywhere else4 ,cause of alternate ,contraction and ,swelling of ,veins4--,a large proportion of metalliferous veins have their opposite walls nearly parallel1 and sometimes over a wide extent of country4 ,there is a fine example of this in the celebrated vein of ,andreasburg in the ,hartz1 which has been worked for a depth of #ejj yards perpendicularly1 and #bjj horizontally1 retaining almost everywhere a width of three feet4 ,but many lodes in ,cornwall and elsewhere are extremely variable in size1 being one or two inches in one part1 and then eight or ten feet in another1 at the distance of a few fathoms1 and then again narrowing as before4 ,such alternate swelling and contraction is so often characteristic as to require explanation4 ,the walls of fissures in general1 observes ,sir ,h4 ,de la ,beche1 are rarely perfect planes throughout their entire course1 nor could we well expect them to be so1 since they commonly pass through rocks of unequal hardness and different mineral composition4 ,if1 therefore1 the opposite sides of such irregular fissures slide upon each other1 that is to say1 if there be a fault1 as in the case of so many mineral veins1 the parallelism of the opposite walls is at once entirely destroyed1 as will be readily seen by studying ,figs4 #fcc to #fce4 ,let a b1 ,fig4 #fcc1 be a line of fracture traversing a rock1 and let a b1 ,fig4 #fcd1 represent the same line4 ,now1 if we cut in two a piece of paper representing this line1 and then move the lower portion of this cut paper sideways from a to a1 taking care that the two pieces of paper still touch each other at the points #a1 #b1 #c1 #d1 #e1 we obtain an irregular aperture at c1 and isolated cavities at d1 d1 d1 and when we compare such figures with nature we find that1 with certain modifications1 they represent the interior of faults and mineral veins4 ,if1 instead of sliding the cut paper to the right hand1 we move the lower part towards the left1 about the same distance that it was previously slid to the right1 we obtain considerable variation in the cavities so produced1 two long irregular open spaces1 f1 f1 ,fig4 #fce1 being then formed4 ,this will serve to show to what slight circumstances considerable variations in the character of the openings between unevenly fractured surfaces may be due1 such surfaces being moved upon each other1 so as to have numerous points of contact4 ,figs4 #fcc1 #fcd1 #fce3 ,lines of fracture traversing a rock4 ,fig4 #fcf3 ,nipped ores where the course of a vein departs from verticality4 ,most lodes are perpendicular to the horizon1 or nearly so2 but some of them have a considerable inclination or 8hade10 as it is termed1 the angles of dip being very various4 ,the course of a vein is frequently very straight2 but if tortuous1 it is found to be choked up with clay1 stones1 and pebbles1 at points where it departs most widely from verticality4 ,hence at places1 such as a1 ,fig4 #fcf1 the miner complains that the ores are 8nipped10 or greatly reduced in quantity1 the space for their free deposition having been interfered with in consequence of the pre-occupancy of the lode by earthy materials4 ,when lodes are many fathoms wide1 they are usually filled for the most part with earthy matter1 and fragments of rock1 through which the ores are disseminated4 ,the metallic substances frequently coat or encircle detached pieces of rock1 which our miners call 8horses0 or 8riders40 ,that we should find some mineral veins which split into branches is also natural1 for we observe the same in regard to open fissures4 ,chemical ,deposits in ,veins4--,if we now turn from the mechanical to the chemical agencies which have been instrumental in the production of mineral veins1 it may be remarked that those parts of fissures which were choked up with the ruins of fractured rocks must always have been filled with water2 and almost every vein has probably been the channel by which hot springs1 so common in countries of volcanoes and earthquakes1 have made their way to the surface4 ,for we know that the rents in which ores abound extend downward to vast depths1 where the temperature of the interior of the earth is more elevated4 ,we also know that mineral veins are most metalliferous near the contact of ,plutonic and stratified formations1 especially where the former send veins into the latter1 a circumstance which indicates an original proximity of veins at their inferior extremity to igneous and heated rocks4 ,it is moreover acknowledged that even those mineral and thermal springs which1 in the present state of the globe1 are far from volcanoes1 are nevertheless observed to burst out along great lines of upheaval and dislocation of rocks4#g ,it is also ascertained that all the substances with which hot springs are impregnated agree with those discharged in a gaseous form from volcanoes4 ,many of these bodies occur as vein-stones2 such as silex1 carbonate of lime1 sulphur1 fluor-spar1 sulphate of barytes1 magnesia1 oxide of iron1 and others4 ,i may add that1 if veins have been filled with gaseous emanations from masses of melted matter1 slowly cooling in the subterranean regions1 the contraction of such masses as they pass from a plastic to a solid state would1 according to the experiments of ,deville on granite 7a rock which may be taken as a standard71 produce a reduction in volume amounting to #aj per cent4 ,the slow crystallisation1 therefore1 of such ,plutonic rocks supplies us with a force not only capable of rending open the incumbent rocks by causing a failure of support1 but also of giving rise to faults whenever one portion of the earth's crust subsides slowly while another contiguous to it happens to rest on a different foundation1 so as to remain unmoved4 ,although we are led to infer1 from the foregoing reasoning1 that there has often been an intimate connection between metalliferous veins and hot springs holding mineral matter in solution1 yet we must not on that account expect that the contents of hot springs and mineral veins would be identical4 ,on the contrary1 ,m4 ,e4 de ,beaumont has judiciously observed that we ought to find in veins those substances which1 being least soluble1 are not discharged by hot springs--or that class of simple and compound bodies which the thermal waters ascending from below would first precipitate on the walls of a fissure1 as soon as their temperature began slightly to diminish4 ,the higher they mount towards the surface1 the more will they cool1 till they acquire the average temperature of springs1 being in that case chiefly charged with the most soluble substances1 such as the alkalies1 soda and potash4 ,these are not met with in veins1 although they enter so largely into the composition of granitic rocks4#h ,to a certain extent1 therefore1 the arrangement and distribution of metallic matter in veins may be referred to ordinary chemical action1 or to those variations in temperature which waters holding the ores in solution must undergo1 as they rise upward from great depths in the earth4 ,but there are other phenomena which do not admit of the same simple explanation4 ,thus1 for example1 in ,derbyshire1 veins containing ores of lead1 zinc1 and copper1 but chiefly lead1 traverse alternate beds of limestone and greenstone4 ,the ore is plentiful where the walls of the rent consist of limestone1 but is reduced to a mere string when they are formed of greenstone1 or 8toad-stone10 as it is called provincially4 ,not that the original fissure is narrower where the greenstone occurs1 but because more of the space is there filled with vein-stones1 and the waters at such points have not parted so freely with their metallic contents4 8,lodes in ,cornwall10 says ,mr4 ,robert ,w4 ,fox1 8are very much influenced in their metallic riches by the nature of the rock which they traverse1 and they often change in this respect very suddenly1 in passing from one rock to another4 ,thus many lodes which yield abundance of ore in granite1 are unproductive in clay-slate1 or killas and vice versa4 ,supposed relative ,age of the different ,metals4--,after duly reflecting on the facts above described1 we cannot doubt that mineral veins1 like eruptions of granite or trap1 are referable to many distinct periods of the earth's history1 although it may be more difficult to determine the precise age of veins2 because they have often remained open for ages1 and because1 as we have seen1 the same fissure1 after having been once filled1 has frequently been re-opened or enlarged4 ,but besides this diversity of age1 it has been supposed by some geologists that certain metals have been produced exclusively in earlier1 others in more modern times2 that tin1 for example1 is of higher antiquity than copper1 copper than lead or silver1 and all of them more ancient than gold4 ,i shall first point out that the facts once relied upon in support of some of these views are contradicted by later experience1 and then consider how far any chronological order of arrangement can be recognised in the position of the precious and other metals in the earth's crust4 ,in the first place1 it is not true that veins in which tin abounds are the oldest lodes worked in ,great ,britain4 ,the government survey of ,ireland has demonstrated that in ,wexford veins of copper and lead 7the latter as usual being argentiferous7 are much older than the tin of ,cornwall4 ,in each of the two countries a very similar series of geological changes has occurred at two distinct epochs--in ,wexford1 before the ,devonian strata were deposited2 in ,cornwall1 after the ,carboniferous epoch4 ,to begin with the ,irish mining district3 ,we have granite in ,wexford traversed by granite veins1 which veins also intrude themselves into the ,silurian strata1 the same ,silurian rocks as well as the veins having been denuded before the ,devonian beds were superimposed4 ,next we find1 in the same county1 that elvans1 or straight dikes of porphyritic granite1 have cut through the granite and the veins before mentioned1 but have not penetrated the ,devonian rocks4 ,subsequently to these elvans1 veins of copper and lead were produced1 being of a date certainly posterior to the ,silurian1 and anterior to the ,devonian2 for they do not enter the latter1 and1 what is still more decisive1 streaks or layers of derivative copper have been found near ,wexford in the ,devonian1 not far from points where mines of copper are worked in the ,silurian strata4 ,although the precise age of such copper lodes cannot be defined1 we may safely affirm that they were either filled at the close of the ,silurian or commencement of the ,devonian period4 ,besides copper1 lead1 and silver1 there is some gold in these ancient or primary metalliferous veins4 ,a few fragments also of tin found in ,wicklow in the drift are supposed to have been derived from veins of the same age4#i ,next1 if we turn to ,cornwall1 we find there also the monuments of a very analogous sequence of events4 ,first1 the granite was formed2 then1 about the same period1 veins of fine-grained granite1 often tortuous 7see ,fig4 #fad71 penetrating both the outer crust of granite and the adjoining fossiliferous or primary rocks1 including the coal-measures2 thirdly1 elvans1 holding their course straight through granite1 granitic veins1 and fossiliferous slates2 fourthly1 veins of tin also containing copper1 the first of those eight systems of fissures of different ages already alluded to1 p4 #fjg4 ,here1 then1 the tin lodes are newer than the elvans4 ,it has1 indeed1 been stated by some ,cornish miners that the elvans are in some instances posterior to the oldest tin-bearing lodes1 but the observations of ,sir ,h4 de la ,beche during the survey led him to an opposite conclusion1 and he has shown how the cases referred to in corroboration can be otherwise interpreted4#aj ,we may1 therefore1 assert that the most ancient ,cornish lodes are younger than the coal-measures of that part of ,england1 and it follows that they are of a much later date than the ,irish copper and lead of ,wexford and some adjoining counties4 ,how much later1 it is not so easy to declare1 although probably they are not newer than the beginning of the ,permian period1 as no tin lodes have been discovered in any red sandstone which overlies the coal in the south-west of ,england4 ,there are lead veins in ,glamorganshire which enter the lias1 and others near ,frome1 in ,somersetshire1 which have been traced into the ,inferior ,oolite4 ,in ,bohemia1 the rich veins of silver of ,joachimsthal cut through basalt containing olivine1 which overlies tertiary lignite1 in which are leaves of dicotyledonous trees4 ,this silver1 therefore1 is decidedly a tertiary formation4 ,in regard to the age of the gold of the ,ural mountains1 in ,russia1 which1 like that of ,california1 is obtained chiefly from auriferous alluvium1 it occurs in veins of quartz in the schistose and granitic rocks of that chain1 and is supposed by ,sir ,r4 ,murchison1 ,,mm4 ,deverneuil and ,keyserling to be newer than the syenitic granite of the ,ural--perhaps of tertiary date4 ,they observe that no gold has yet been found in the ,permian conglomerates which lie at the base of the ,ural ,mountains1 although large quantities of iron and copper detritus are mixed with the pebbles of those ,permian strata4 ,hence it seems that the ,uralian quartz veins1 containing gold and platinum1 were not formed1 or certainly not exposed to aqueous denudation1 during the ,permian era4 ,in the auriferous alluvium of ,russia1 ,california1 and ,australia1 the bones of extinct land-quadrupeds have been met with1 those of the mammoth being common in the gravel at the foot of the ,ural ,mountains1 while in ,australia they consist of huge marsupials1 some of them of the size of the rhinoceros and allied to the living wombat4 ,they belong to the genera ,diprotodon and ,nototherium of ,professor ,owen4 ,the gold of ,northern ,chili is associated in the mines of ,los ,hornos with copper pyrites1 in veins traversing the cretaceo-oolitic formations1 so-called because its fossils have the character partly of the cretaceous and partly of the oolitic fauna of ,europe4#aa ,the gold found in the ,united ,states1 in the mountainous parts of ,virginia1 ,north and ,south ,carolina1 and ,georgia1 occurs in metamorphic ,silurian strata1 as well as in auriferous gravel derived from the same4 ,gold has now been detected in almost every kind of rock1 in slate1 quartzite1 sandstone1 limestone1 granite1 and serpentine1 both in veins and in the rocks themselves at short distances from the veins4 ,in ,australia it has been worked successfully not only in alluvium1 but in vein-stones in the native rock1 generally consisting of ,silurian shales and slates4 ,it has been traced on that continent over more than nine degrees of latitude 7between the parallels of #cj and #ci ,s471 and over twelve of longitude1 and yielded in #ahec an annual supply equal1 if not superior1 to that of ,california2 nor is there any apparent prospect of this supply diminishing1 still less of the exhaustion of the gold-fields4 ,origin of ,gold in ,california4--,mr4 ,j4 ,arthur ,phillips1#ab in his treatise 8,on the ,gold ,fields of ,california10 has shown that the ore in the gold workings is derived from drifts1 or gravel clay1 and sand1 of two distinct geological ages1 both comparatively modern1 but belonging to different river-systems1 the older of which is so ancient as to be capped by a thick sheet of lava divided by basaltic columns4 ,the auriferous quartz of these drifts is derived from veins apparently due to hydrothermal agency1 proceeding from granite and penetrating strata supposed to be of ,jurassic and ,triassic date4 ,the fossil wood of the drift is sometimes beautifully silicified1 and occasionally the trunks of trees are replaced by iron pyrites1 but gold seems not to have been found as in the pyrites of similarly petrified trees in the drift of ,australia4 ,the formation of recent metalliferous veins is now going on1 according to ,mr4 ,phillips1 in various parts of the ,pacific coast4 ,thus1 for example1 there are fissures at the foot of the eastern declivity of the ,sierra ,nevada in the state of that name1 from which boiling water and steam escape1 forming siliceous incrustations on the sides of the fissures4 ,in one case1 where the fissure is partially filled up with silica inclosing iron and copper pyrites1 gold has also been found in the vein-stone4 ,it has been remarked by ,m4 de ,beaumont1 that lead and some other metals are found in dikes of basalt and greenstone1 as well as in mineral veins connected with trap-rock1 whereas tin is met with in granite and in veins associated with the ,plutonic series4 ,if this rule hold true generally1 the geological position of tin accessible to the miner will belong1 for the most part1 to rocks older than those bearing lead4 ,the tin veins will be of higher relative antiquity for the same reason that the 8underlying0 igneous formations or granites which are visible to man are older1 on the whole1 than the overlying or trappean formations4 ,if different sets of fissures1 originating simultaneously at different levels in the earth's crust1 and communicating1 some of them with volcanic1 others with heated ,plutonic masses1 be filled with different metals1 it will follow that those formed farthest from the surface will usually require the longest time before they can be exposed superficially4 ,in order to bring them into view1 or within reach of the miner1 a greater amount of upheaval and denudation must take place in proportion as they have lain deeper when first formed and filled4 ,a considerable series of geological revolutions must intervene before any part of the fissure which has been for ages in the proximity of the ,plutonic rock1 so as to receive the gases discharged from it when it was cooling1 can emerge into the atmosphere4 ,but ,i need not enlarge on this subject1 as the reader will remember what was said in the #cjth1 #cbnd1 and #ceth chapters on the chronology of the volcanic and hypogene formations4 #a ,geol4 ,trans41 vol4 iv1 p4 #aci2 ,trans4 ,royal ,geol4 ,society1 ,cornwall1 vol4 ii1 p4 #ij #b ,conybeare and ,phil4 ,geol41 p4 #dja1 and ,farey's ,derbyshire1 p4 #bdc4 #c ,fournet1 tudes sur les ,dpts ,mtallifres4 #d ,carne1 ,trans4 ,geol4 ,soc41 ,cornwall1 vol4 iii1 p4 #bch4 #e ,geol4 ,rep4 on ,cornwall1 p4 #cdj4 #f ,principles1 chap4 xxvii1 #hth edit41 p4 #dbb4 #g ,see ,dr4 ,daubeny's ,volcanoes4 #h ,bulletin1 iv1 p4 #abgh4 #i ,sir ,h4 ,de la ,beche1 ,,ms4 ,notes on ,irish ,survey4 #aj ,report on ,geology of ,cornwall1 p4 #caj4 #aa ,darwin's ,south ,america1 p4 #bji1 etc4 #ab ,proc4 ,royal ,soc41 #ahfh1 p4 #bid4 ,,index4 ----33---- ,the ,fossils1 the names of which appear in ,italics1 are figured in the ,text4 ,,abbeville1 flint tools of1 #aeb ,aberdeenshire1 granite of1 #eeh ,abich1 ,m41 on trachytic rocks1 #ejd ,acer trilobatum1 ,miocene1 #bbj1 #bba ,acrodus nobilis1 ,lias1 #cei ,acrogens1 term explained1 #cjc ,acrolepis ,sedgwickii1 ,permian1 #cij ,acton acutus1 ,great ,oolite1 #cde ,actinocyclas1 in ,atlantic mud1 #bhh ,actinolite1 #dii1 #ejb ---- schist1 #egh chmodus ,leachii1 ,lias1 #ceh ,adiantites ,hibernica1 ,old ,red1 #dda ,agassiz on fish of ,sheppey1 #bfg ---- on fish of the ,brown-,coal1 #edj ---- on fish of ,monte ,bolca1 #edd ---- on ,old ,red fossil fish1 #ddc1 #ddg ---- on ,silurian fish1 #dfj ,age of metamorphic rocks1 #eig ---- of ,plutonic rocks1 #efd ---- of strata1 tests of1 #abc ---- of volcanic rocks1 #ebj ,agglomerate described1 #eji ,agnostus integer4 ,a4 ,rex1 #dhh ,air-breathers of the ,coal1 #dac ,aix-la-,chapelle1 ,cretaceous flora of1 #cjb ,alabaster defined1 #ci ,alberti on ,keuper1 #cgf ,albite1 #dii1 #ejj ,aldeby and ,chillesford beds1 #aib ,alkali1 present in the ,palozoic strata1 #ehg ,alpine blocks on the ,jura1 #afi ,alps1 age of metamorphic rocks in1 #eii ----1 nummulitic limestone and flysch of1 #gg ,alum schists of ,norway and ,sweden1 #dhi ,alluvial deposits1 ,recent and ,post-pliocene1 #aea ,alluvium1 term explained1 #ii ---- in ,auvergne1 #ajj ,alternations of marine and fresh-water strata1 #gb ,alum ,bay beds1 plants of the1 #bfb ,amblyrhynchus cristatus1 a living marine saurian1 #cfb ,america4 ,see ,united ,states1 ,canada1 ,nova ,scotia4 ----1 ,north1 ,glacial formations of1 #ahb ----1 ,south1 gradual rise of land in1 #gb ----1 ,silurian strata of1 #dgh ,american character of ,lower ,miocene flora1 #bch ---- forms in ,swiss ,miocene flora1 #bbc ,amiens1 flint tools of1 #aeb ,ammonites bifrons1 ,lias1 #cef ---- ,braikenridgii1 ,oolite1 #cea ---- ,bucklandi1 ,lias1 #cef ---- ,deshayesii1 ,neocomian1 #caa ---- ,humphresianus1 ,inferior ,oolite1 #cea ---- ,jason1 ,oxford ,clay1 #cdj ---- ,noricus1 ,speeton1 #cab ---- macrocephalus1 ,oolite1 #ceb ---- margaritatus1 ,lias1 #ceg ---- planorbis1 ,lias1 #cef ---- rhotomagensis1 ,chalk marl1 #bih ,amphibole group of minerals1 #dii1 #ejb ,amphistegina ,hauerina1 ,vienna basin1 #bbe ,amphitherium ,broderipii1 in ,stonesfield1 #cdh ---- ,prevostii1 ,stonesfield slate1 #cdg ,ampullaria glauca1 #ef ,amygdaloid1 #ejg ,analcime1 #ejj ,anamesite1 a variety of basalt1 #ejd ,ananchytes ovatus1 ,white chalk1 #bic ----1 with crania attached1 #di ,ancillaria subulata1 ,eocene1 #eg ,ancyloceras gigas1 #cji ---- spinigerum1 ,gault1 #cja ---- ,duvallei1 ,neocomian1 #cab ,ancylus velletia 7,a4 elegans71 #ee ,andalusite1 #ejj ,andes1 ,plutonic rocks of the1 #efi ,andreasburg1 metalliferous vein of1 #faa ,angelin1 on ,cambrian of ,sweden1 #dhi ,angiosperms1 #cjc ---- of the ,coal1 #dbi ,anglesea1 dike cutting through shale in1 #ead ,anodonta ,cordierii1 #ed ---- ,jukesii1 ,upper ,old ,red1 #dda ---- latimarginata1 #ed ,anoplotherium commune1 ,binstead1 #bed ---- gracile1 ,paris basin1 #bga ,anorthite1 #dii1 #eja ,annularia sphenophylloides1 ,coal1 #dbe ,antholithes1 coal-measures1 #dbi ,anthracite1 conversion of coal into1 #djh ,anticlinal and synclinal curves1 #gd1 #he ,antrim1 ,chalk altered by a dike in1 #eaf ----1 ,lower ,miocene1 volcanic rocks of1 #eci ,antwerp ,crag1 #bjd ,apateon pedestris1 a carboniferous reptile1 #djf ,apatite1 #ejj ,apennines1 ,northern1 metamorphic rocks of1 #eii ,apes1 fossil of the ,upper ,miocene1 #bae ,apiocrinites rotundus1 ,bradford1 #cdc ,appalachians1 long lines of flexures in1 #ib1 #ic ----1 vast thickness of successive strata in1 #aaj ,aptychus1 part of ammonite1 #ccf ,aqueous rocks defined1 #bg1 #ce ,araucaria sphrocarpa1 ,inferior ,oolite1 #cdh ,arbroath1 section of ,old ,red at1 #gd ,archopteryx macrura1 ,solenhofen1 #cch ,archegosaurus minor and ,a4 medius1 coal measures1 #djf1 #djg ,archiac1 ,m4 de1 on nummulites1 #bgg ----1 on chalk of ,france1 #cjf ,arctic ,miocene ,flora1 #bci ,area of the ,wealden1 #cai ,areas1 permanence of continental1 #aag ,arenaceous rocks described1 #ce ,arenicolites linearis1 ,arenig beds1 #dge ,arenig or ,stiper-,stones group1 #dgd ----1 volcanic formations of1 #edi ,argile plastique1 #bgf ,argillaceous rocks described1 #cf ,argillite1 ,argillaceous schist1 #egi ,argyll1 ,duke of1 on ,isle of ,mull leaf-beds1 #bdg ,armagh1 bone-beds in ,mountain ,limestone at1 #dcg ,arran1 amygdaloid filled with spar near1 #eah ----1 erect trees in volcanic ash of1 #edf ----1 ,greenstone dike in1 #ead ,arthur's seat1 trap rocks of1 #ede ,arvicola1 tooth of1 #afe ,asaphus caudatus1 ,silurian1 #dfg ---- tyrannus1 ,a4 ,buchii1 #dgd ,ascension1 lamination of volcanic rocks in1 #eie ,ash1 ,mr41 on fossils of ,tremadoc beds1 #dhc ,ashby-de-la-,zouch1 fault in coal field of1 #ia ,aspidura loricata1 ,muschelkalk1 #cgi ,astarte borealis 7,a4 arctica,a4 compressa71 #agf ---- ,omalii1 ,crag1 #aii ,asterophyllites foliosus1 ,coal1 #dbe ,astrangia lineata 7,anthophyllum lineatum71 #bbi ,astra basaltiforme1 ,carboniferous1 #dcb ,astropecten crispatus1 ,london clay1 #bff ,atherfield clay1 #cji ,atlantic mud1 composition of1 #bhg ,atrypa reticularis1 ,aymestry1 #dfb ,aturia ziczac 7,nautilus ziczac71 #bff ,augite1 #dii1 #ejb ,auricula1 recent1 #ee ,austen1 ,mr4 ,godwin1 on marine deposit of ,selsea ,bill1 #ahb ----1 on boulders in chalk1 #bib ,australian cave breccias1 #aeh ,australia1 auriferous gravel of1 #fag ,auvergne1 alluvium in1 #ajj ----1 chain of extinct volcanoes in1 #die ----1 granite veins in1 #faj ----1 ,lower ,miocene of1 #bcc ----1 ,miocene volcanic rocks of1 #edj ----1 ,post-pliocene volcanic eruptions in1 #ebg ----1 springs from spent volcanoes in1 #fjd ,aveline ,mr41 on ,tarannon shales1 #dfh ,avicula contorta1 ,rhtic beds1 #cff ---- cygnipes1 ,lias1 #cee ---- inquivalvis1 ,lias1 #cee ---- socialis1 ,muschelkalk1 #cgi ,aviculopecten papyraceus1 coal measures1 #dje ---- sublobatus1 mountain limestone1 #dcd ,aymestry ,limestone1 #dfa ,azoic period1 supposed1 #fjc ,azores1 ,miocene lavas with shells1 #eci ,,bacillaria paradoxa1 #ea ,baculites anceps1 ,lower ,chalk1 #bih ---- ,fauiasii1 chalk1 #bhf ,baffin's ,bay1 formation of drift in1 #aga1 #agc ,bagshot sands1 #beh1 #bei1 #bfb ,bai1 ,bay of1 subterranean igneous action in1 #efi ,bakewell1 ,mr41 on cleavage in ,swiss ,alps1 #eij ,bala and ,caradoc beds1 #dgj ,balistid1 defensive spine of1 #bfa ,bangor1 or ,longmynd group1 #dhe ,banksia1 seed and fruit of1 ,lower ,miocene1 #bch ,barmouth sandstones1 #dhf ,barnes1 ,mr4 ,j41 on insects in ,american coal1 #daf ,barnstaple1 ,upper ,devonian of1 #dej ,barrande1 ,m4 ,joachim1 his 8,primordial ,zone10 #dga1 #dhb1 #dhg ----1 on metamorphosis of trilobites1 #dga ,barrett1 ,mr41 on bird in ,blackdown beds1 #bii ,barton series sands and clays1 #beh ---- shells1 percentage of1 common to ,london clay1 #beh ,basalt1 columnar1 #eaa ----1 composition of1 #ejd ,basaltic rocks1 poor in silica1 #ejd ----1 specific gravity of minerals in1 #ejd ,basilosaurus1 ,eocene1 ,united ,states1 #bhj ,basset1 term explained1 #hc ,basterot1 ,m4 de1 on ,bordeaux tertiary strata1 #ada ,bath ,oolite1 #cdb ,batrachian reptiles in coal1 #djf ,bay of ,fundy1 denudation in coalfield in1 #dah ,bean1 ,mr41 on ,yorkshire ,oolite1 #cej ,bear ,island carboniferous flora1 #dda ,beaumont1 ,m4 ,e4 de1 on island in ,cretaceous sea1 #cje ----1 on mineral veins1 #fac ----1 on ,jurassic plutonic rocks1 #ega ----1 on formation of granite1 #eec ,beckles1 ,mr4 ,s4 ,h41 on footprints in ,hastings sands1 #cae1 #ccj ---- on ,mammalia of ,purbeck1 #cbf ,belemnitella mucronata1 ,chalk1 #bhc ,belemnites hastatus1 ,oxford clay1 #cdj ---- ,puzosianus1 ,oxford clay1 #cda ,belgium1 ,lower ,miocene of1 #bda ,bellerophon costatus1 ,mountain ,limestone1 #dcf ,belosepia sepioidea1 ,sheppey1 #bff ,belt1 ,mr41 on subdivision of ,lingula ,flags1 #dhd ,bembridge beds1 ,yarmouth1 #beb ,berger1 ,dr41 on rocks altered by dikes1 #eae ,berlin1 ,miocene strata near1 #bdb ,bernese ,alps1 gneiss in the1 #eii ,berthier on isomorphism1 #ejb ,bertrich-,baden1 columnar basalt of1 #eab ,beyrich on term ,oligocene for ,lower ,miocene1 #bdd ,billings1 ,mr41 on trilobites1 #dga ,binney1 ,mr41 on ,sigillari in volcanic ash1 #edf ----1 on ,stigmaria1 the root of ,sigillaria1 #dbf ,biotite1 #dii1 #eja ,bird in argile plastique1 #bgf ,bischoff1 ,professor1 on ,nile and ,rhine mud1 #aed ----1 on conversion of coal into anthracite1 #djc ----1 on hydrothermal action1 #ehf ,blackdown beds1 #cja ,blacklead of ,borrowdale1 #fe ,bog-iron-ore1 #eb ,bohemia1 ,cambrian rocks of1 #dhg ----1 silver veins in1 #faf ,bolderberg1 in ,belgium1 ,upper ,miocene of1 #bbd ,bone-bed of fish remains1 ,armagh1 #dcg ---- of ,upper ,ludlow1 #dej ---- of the ,trias1 #cfg ,boom1 ,lower ,miocene of1 #bda ,bordeaux1 ,upper ,miocene of1 #bad ,borrowdale1 blacklead of1 #fe ,bosquet1 ,m4 on chalk fossils1 #bhc ----1 on ,maestricht beds1 #bhc ,botanical nomenclature1 #cjc ,boucher de ,perthes on ,abbeville alluvium1 #aeb ,boulder-clay1 whether formed by icebergs or land-ice1 #aff-gc1 #agh ,boulder-clay of ,canada1 #ahb ---- fauna of1 #agf1 #ahi ,boulders and pebbles in chalk1 #bib ,bournemouth beds 7,lower ,bagshot71 #bfb ,bovey ,tracey1 lignites and clays of1 #bdf ,bowerbank1 ,mr41 on fossil fruits of ,london ,clay1 #bfe ----1 on fossil fruits of ,sheppey1 #bfe ,bowman1 ,mr41 on uniting of distinct coal-seams1 #dja ,brachiopoda1 preponderance of1 in older rocks1 #dgj ----1 mode of recognising shells of1 #dga ,bracklesham beds and ,bagshot ,sands1 #bei ,bradford encrinites1 #cdb ,breccias of ,lower ,permian1 #cia ,brick-earth or fluviatile loam1 #aec ,bridlington drift1 #ahi ,bristol1 dolomitic conglomerate of1 #cgc ,bristow1 ,mr41 on volcanic minerals1 #ejj ,brixham cave near ,torquay1 #aeh ,brocchi on ,italian tertiary strata1 #ada ---- on subapennine strata1 #bjh ,brockenhurst1 corals and shells of1 #beg ,brodie1 ,rev4 ,p4 ,b41 on ,lias insects1 #cfc ,brodie1 ,mr4 ,w4 ,r41 on ,purbeck mammalia1 #cbf ,brongniart1 ,m4 ,adolphe1 on botanical nomenclature1 #cjc ----1 on ,lias plants1 #cfd ----1 on flora of the ,bunter1 #chj ----1 on flora of the coal1 #dbj ----1 on fruit of ,lepidodendron1 #dbd ----1 ,m4 ,alex41 on ,tertiary series1 #ada ,bronteus flabellifer1 ,devonian1 #dec ,brora1 oolitic coal formation of1 #cej ,brown1 ,mr4 ,richard1 on ,stigmaria1 #dbf ----1 on carboniferous rain-prints1 #daf ,brown1 ,robert1 on ,eocene protaceous fruit1 #bfd ,brown1 ,reverend ,t41 on marine shells in ,scotch drift1 #agg ,brown-coal of ,germany1 #edj ,bryce1 ,mr41 on ,scotch till1 #agf ,bryozoa of ,mountain ,limestone1 #dcc ---- and polyzoa1 terms explained1 #aig ,buch1 von4 ,see ,von ,buch4 ,buckland1 ,dr41 on ,kirkdale cave1 #aeh ----1 on violent death of saurians1 #cfb ----1 on spines of fish1 #cei ----1 on ,eocene oysters1 #bfh ----1 on pot-stones in chalk1 #bia ,buddle1 ,mr41 on creeps in coal-mines1 #gh ,bulimus ellipticus1 ,bembridge1 #bec ---- lubricus1 ,loess1 #ef ,bullock1 ,capt41 ,r4,n41 on ,atlantic mud1 #bhg ,bunbury1 ,sir ,c41 on leaf-bed of ,madeira1 #ecb ----1 on ferns of the ,maryland coal1 #dba ,bunter of ,germany1 #chj ---- or ,lower ,trias of ,england1 #cgb ,buprestis8 ,elytron of1 ,stonesfield1 #cdf ,burmeister on trilobites1 #dga ,,cainozoic1 term defined1 #abc ,caithness1 fish beds of1 #ddc ,calamite1 root of1 #dbe ,calamites ,sucowii1 coal1 and restored stem1 #dbd ,calamophyllia radiata1 ,bath ,oolite1 #cdb ,calcaire de la ,beauce1 age of the1 #bcj ---- grossier1 fossils of the1 #bgd ---- siliceux of ,france1 #bgc ,calcareous matter poured out by springs1 #fjd ---- rocks described1 #cf ---- nodules in ,lias1 #fc ,calcarina rarispina1 ,eocene1 #bge ,calceola sandalina1 ,devonian1 #dec ----1 schiefer of ,germany1 #dec ,california1 aurifrous gravel of1 #fag ----1 gold in petrified wood of age of alluvium1 #fja ,calymene ,blumenbachii1 ,silurian1 #dff ,cambrian ,group1 classification of the1 #dha ,cambrian1 ,upper1 #dhb ----1 ,lower1 #dhd ----1 of ,sweden and ,norway1 #dhi ----1 strata of ,bohemia1 #dhg ----1 of ,north ,america1 #dhi ----1 volcanic rocks1 #edi ,campophyllum flexuosum1 #dca ,canada1 ,cambrian of1 #dhi ----1 ,devonian of1 #dee ----1 trap-rocks of1 #edi ,canadian drift1 #ahb ,canary1 ,grand1 shelly tuffs of1 #ech ,cantal1 ,lower ,miocene of the1 #bca ,cape ,breton1 rain-prints in coal-measures of1 #daf ,cape ,wrath1 granite veins in gneiss at1 #efj ,caradoc and ,bala beds1 #dgj ,carbonate of lime in rocks1 how tested1 #cg ,carboniferous ,group1 subdivisions of the1 #cid ---- flora1 #dbj-cj ---- limestone1 thickness of1 #cif ----1 marine fauna of the1 #dcb ---- ,period1 trap-rocks of1 #ede ---- plutonic rocks1 #egb ---- reptiles1 #djf ---- insects1 #dje ,carcharodon angustidens1 ,bracklesham1 #bfb ,cardiganshire1 section of slaty cleavage in1 #ehi ,cardiocarpon ,ottonis1 ,permian1 #cic ,cardita 7,venericardia7 planicosta1 #bfj ---- sulcata1 ,barton1 #bei ,cardium dissimile1 ,portland ,stone1 #ccf ---- rhticum1 ,rhtic ,beds1 #cff ---- striatulum1 ,kimmeridge clay1 #ccf ,carne1 ,mr4 ,n41 on ,cornish lodes1 #fjg ,carpenter1 ,dr41 on ,atlantic mud1 #bhh ----1 on ,eozoon ,canadense1 #dia ,carrara1 marble of1 #eii ,carruthers1 ,mr41 on ,eocene proteaceous fruit1 #bfe ----1 on cycads of the ,purbeck1 #ccb ----1 on leaves of calamite1 #dbe ----1 on spores of carboniferous ,lycopodiace1 #dbb ----1 on structure of sigillaria1 #dbf ----1 on trees in volcanic ash1 #edg ,cashmere1 recent formations in1 #adf ,cassian1 ,st41 ,triassic strata of1 #cgf ,castrogiovanni1 curved strata near1 #hf ,catania1 laterite formed in1 #eaj ----1 ,tertiary beds in1 #bjf ,catillus ,lamarckii1 ,white ,chalk1 #bie ,caucasus1 absence of lakes in the1 #ahg ,caulopteris primva1 ,coal1 #dba ,cave-breccias of ,australia1 #aeh ,cavern deposits with human and animal remains1 #aef ,caves of ,kirkdale and ,brixham1 #aeg ,celts described1 #aeb ,cementing of strata1 #fa ,cephalaspis ,lyelli1 ,old ,red1 #ddf ,ceratites nodosus1 ,muschelkalk1 #cgi ,cerithium concavum1 ,headon1 #bef ---- elegans1 ,hempstead beds1 #bde ---- 7,terebra7 ,portlandicum1 #cce ---- plicatum1 ,hempstead beds1 #bde ---- melanoides1 #bfh ,cervus alces1 tooth of1 #afd ,cestracion ,phillippi1 ,recent1 #big ,chabasite1 #ejj ,chalk1 composition1 extent1 and origin of1 #bhf ---- of ,faxoe1 #bhf ---- flints1 origin of1 #bij ---- fossils of the ,white1 #bic-f ----1 iceborne boulders in the1 #bib ---- of ,north and ,south ,europe1 #cje ----1 ,lower ,white1 without flints1 #bih ---- marl1 fossils of the1 #bih ---- ,period1 popular error concerning1 #bhh ,chalk-pit with pot-stones1 view of1 #bia ,chama squamosa1 ,barton1 #beh ,champoleon1 junction of granite with ,jurassic strata near1 #ega ,chara elastica1 ,c4 medicaginula1 #eh ---- tuberculata1 ,bembridge1 #bec ,charpentier1 ,m41 on ,alpine glaciers1 #agj ----1 on depression of ,alps in ,glacial ,period1 #ahe ,chatham coal-field1 #chc ,cheirotherium1 footprints of1 #cgb ,chemical deposits in veins1 #fab ---- and mechanical deposits1 #fj ,chiapa1 fall of volcanic dust at1 #ebc ,chichester1 erratics near1 #aha ,chili1 copper pyrites with gold in1 #faf ----1 walls cracked by earthquake in1 #hg ,chillesford and ,aldeby beds1 #aib ,chimra monstrosa1 ,lias1 #cei ,chlorite-schist1 #egi ,chloritic series1 or ,upper ,greensand1 #bih ,christiania1 ,euritic porphyry at1 #efb ----1 granite veins in ,silurian strata of1 #egb ----1 quartz vein in gneiss at1 #efa ,chronological groups of formations1 #abi ,chronology1 test of1 in rocks1 #aba ,cinder-bed of the ,purbeck1 #cbe ,cinnamomum polymorphum1 ,miocene1 #bai ---- ,rossmssleri1 ,miocene1 #bci ,claiborne beds1 ,eocene fossils of1 #bgi ,clarke ,county1 ,united ,states1 ,zeuglodon of1 #bgi ,classification of ,tertiary formations1 #acg1 #adc ----1 value of shells in1 #adb ,clausilia bidens1 ,loess1 #ef ,clay defined1 #cf ---- iron-stone defined1 #djd ----1 plastic1 #bfg ---- slate1 #egi ----1 ,weald1 #cac ,cleavage explained1 #ejb ----1 crystalline theory of1 #eia ----1 mechanical theory of1 #eib ---- of metamorphic rocks1 #ehh ,cleidotheca operculata1 #dhc ,clermont1 metalliferous gneiss near1 #ehf ,climate of the ,crags1 #bjj ---- of the ,coal1 #dcj ---- of the ,miocene in the ,arctic regions1 #bdj ---- of the ,post-pliocene period1 #afa ,clinkstone1 #ejf ,clinton group1 fossils of the1 #dgi ,clyde1 buried canoes in estuary of1 #adf ----1 arctic marine shells in drifts of1 #agf ,clymenia linearis1 ,devonian1 #dea ,clymenien-,kalk of ,germany1 #dej ,coal1 conversion into anthracite of1 #djc ---- a land and swamp formation1 #cig ----1 cause of the purity of1 #djb ----1 conversion of lignite into1 #djc ----1 erect trees in1 #daa ----1 structure of the1 #dab ----1 vegetation of the1 #dbj ----1 air-breathers in the1 #dje1 #dac ,coal ,period1 climate of the1 #dcj ---- field of ,virginia1 #chb ---- measures of ,nova ,scotia1 #djh ---- measures1 thickness of1 in ,wales1 #cig ---- pipes1 danger of1 #cij ----1 rainprints in1 #daf ---- seams1 uniting of1 #djj ,coalbrook-,dale1 faults in1 #hh ,cochliodus contortus1 #dcg ,cockfield ,fell rocks1 altered by dikes1 #eaf ,coelacanthus granulatus1 ,permian1 #cij ,coleoptera of ningen beds1 #bbc ,collyrites ringens1 ,inferior ,oolite1 #cea ,columnar structure of volcanic rocks1 #eaj ---- basalt in the ,vicentin1 #eaa ,compact feldspar1 #eja ,concretionary structure1 #fc ,cone of ,tartaret1 #ebg1 #edb ---- of ,cme1 #bh ,cones and craters described1 #die ----1 absence of1 in ,england1 #cj ,conformable stratification1 #ci ,conglomerate or pudding-stone1 #cf ----1 ,dolomitic1 of ,bristol1 #cgc ,conifer of the coal-measures1 #dbg ,connecticut ,valley1 ,new ,red ,sandstone of1 #cha ,conocephalus striatus1 #dhh ,conocoryphe striata1 #dhh ,conrad1 ,mr41 on age of ,american cretaceous rocks1 #cjg ,consolidation of strata1 #fa ,continents and oceans1 permanence of1 #aag ,contorted strata1 in drift1 #agh ,conularia ornata1 ,devonian1 #dec ,conulus priscus1 ,coal1 #dae ,conus deperditus1 ,bracklesham1 #bfb ,conybeare and ,phillips on ninety-fathom dike1 #ij ,conybeare1 ,mr41 on reptiles of the ,lias1 #cfj ,copper lode near ,redruth1 #fjg ,coprolite bed of ,chloritic ,series1 #bii ---- beds of ,red and ,coralline crags1 #aig1 #aih ,coprolites of fish from the chalk1 #bih ,coral ,rag1 fossils of the1 #cci ,coralline of ,white ,crag1 #aig ,corals of the ,devonian1 #dea ---- of the ,mountain ,limestone1 #dcc ----1 ,neozoic type of1 #dca ----1 ,palozoic type of1 #dca ,corbicella 7,cyrena7 fluminalis1 #ed ,corbula pisum1 ,hempstead beds1 #bde ,corinth1 corrosion of rocks by gases near1 #ehf ,cornbrash or ,forest ,marble1 #cda ,cornwall1 granite veins in1 #efa1 #ehb ----1 lodes in1 #fae ----1 mass of granite in1 #eeb ----1 vertical sections of veins in mine1 #fjg ,cosequina volcano1 burying of organic remains by1 #ebc ,crag1 term defined1 #aib ---- of ,antwerp1 #bjd ----1 fauna of1 its relation to that of present seas1 #bja ----1 ,norwich1 #aic ----1 ,coralline or ,white1 #aig ----1 ,red1 #aid ----1 tables of marine testacea in1 #bjb ---- deposits1 climate of1 #bjj ,crania attached to a sea-urchin1 #di ---- ,parisiensis1 ,white ,chalk1 #bid ,crassatella sulcata1 ,barton1 #bei ,craters and cones described1 #die ----1 ,theory of ,elevation1 #dif ,craven fault1 #ij ,creeps in coal-mines1 #gh ,cretaceous rocks of ,united ,states1 #cjg ---- ,period1 error as to continuity of1 #bhh ----1 flora of the ,upper1 #cjb ---- volcanic rocks1 #edd ---- plutonic rocks1 #egj ---- ,period1 distinct mineral character of rocks in1 #bib ---- rocks1 classification of1 #bhb ---- strata1 connection between ,upper and ,lower1 #cja ,crinoidea of ,mountain ,limestone1 #dcc ,croatia1 ,lower ,miocene beds of1 #bdb ,croll1 ,mr41 on amount of subarial denudation1 #aad ,cromer forest-bed1 #aia ,crop out1 term explained1 #hc ,crossopterygid1 or fringe-finned fish1 #ddc ,crowfoot1 ,mr41 on shells of ,aldeby beds1 #aib ,crust of the earth defined1 #bf ,crustaceans of ,old ,red ,sandstone1 #ddf ,cryptodon angulatum1 ,london ,clay1 #bff ,crystalline ,limestone1 #egi ---- rocks defined1 #cb ---- schists1 much alkali in the1 #ehg ---- theory of cleavage1 #eia ,cup and ,star corals1 #dca ,curved strata1 #gc-gf ,cutch1 salt-layers in the ,runn of1 #cge ,cuvier1 ,m41 on fauna of the ,paris basin1 #bga ----1 on ,mammalia of ,paris gypsum1 #bca ----1 on ,tertiary series1 #ada ,cyathocrinus caryocrinoides1 #dcc ---- planus1 #dcc ,cyathophyllum cspitosum1 #dea ,cyclopean isles1 beds of tuff and clay in1 #ebi ----1 contorted strata in1 #ecj ,cyclopteris ,hibernica1 ,old ,red1 #dda ,cyclostigma 7,lepidodendron71 ,old ,red1 #dda ,cyclostoma elegans1 ,loess1 #ef ,cylindrites acutus1 ,great ,oolite1 #cde ,cypress swamps of the ,mississippi1 #djb ,cyprides in the ,weald ,clay1 #cae ,cypridina serrato-striata1 #dea ,cypris in fresh-water deposits1 #eg ---- gibbosa1 ,c4 tuberculata1 ,c4 leguminella1 #cbd ---- striato-punctata1 ,c4 fasciculata1 ,c4 granulata1 #cbe ---- ,purbeckensis1 ,cypris punctata1 #cca ---- spinigera1 ,weald ,clay1 #cae ,cyrena 7,corbicella7 fluminalis1 #ed ---- cuneiformis1 ,woolwich ,clays1 #bfh ---- obovata1 #ed ---- semistriata1 ,hempstead beds1 #bde ,cystide of ,silurian rocks1 #dff ,cythere inflata1 coal-measures1 #dje ,,dadoxylon1 fragment of coniferous wood1 #dbh ,dana1 on volcanic minerals1 #ejj ,danish kitchen-middens1 #adf ,dapedius monilifer1 ,lias1 #ceh ,darbishire on shells of ,moel ,tryfaen1 #ahj ,dartmoor1 post-carboniferous granite of1 #egb ---- intrusive granite at1 #egb ,darwin1 ,mr41 on foliation and lamination1 #eie ----1 on mammalia of ,south ,america1 #afj ----1 on marine saurian1 #cfb ----1 on rise of part of ,south ,america1 #gb ----1 on sinking of coral reefs1 #gb ----1 on plutonic rocks of the ,andes1 #efi ----1 on relationship of extinct to living types1 #afj ,dates of discovery of fossil vertebrata1 #dfd ,daubeny1 ,dr41 on decomposition of trachytic rocks1 #ehf ,daubre1 on formation of zeolites1 #eba ----1 on alkaline waters of ,plombires1 #ehd ,davidson1 ,mr41 on ,spiriferina1 #cee ,davis1 ,mr4 ,e41 on fossils of ,lingula ,flags1 #dhd ,dawkins1 ,mr4 ,boyd1 on ,hyna spela1 #aeh ----1 on mammalia of ,cromer ,forest-bed1 #aia ----1 on ,triassic mammifer1 #cfi ,dawson1 ,dr41 on ,devonian flora and insects1 #def1 #deg ----1 on ,eozoon ,canadense1 #dia ----1 on ,nova ,scotia coal-measures1 #dji ----1 on ,nova ,scotia coal-plants1 #daj1 #dab ----1 on ,pupa vetusta1 #dae ----1 on reptiles and shells in ,nova ,scotia coal1 #dac ----1 on structure of calamite1 #dbe ----1 on structure of sigillaria1 #dbf ,deane1 ,dr41 on footprints in ,trias1 #chb ,debey1 ,dr41 on flora and fauna of ,aix1 #cjb-jd ,dechen1 ,m4 von1 on organic remains of the brown coal1 #edj ----1 on ,cornish granite veins1 #efj ,de la ,beche1 ,sir ,h41 on granite of ,dartmoor1 #ehb ----1 on ,carrara marble1 #eii ----1 on mineral veins1 #faf ----1 on ,redruth copper-mine1 #faj ----1 on saurians of the ,lias1 #cfb ----1 on trap-rocks of ,new ,red1 #ede ----1 on ,welsh coal-measures1 #cig ,delesse1 on action of water in metamorphism1 #ehe ,deltas1 strata accumulated in1 #bh ,dendrerpeton in ,coal1 #dac ,denudation defined1 #if ----1 subarial1 #ig ----1 littoral1 #ajb ----1 submarine1 #aje ----1 average annual amount of subarial1 #aac ---- of carboniferous strata1 #cif ---- counteracting upheaval1 #ajf-ae1 #ajh-ae ---- a means of exposing crystalline rocks1 #efc ----1 trap-dikes cut off by1 #eah ---- and volcanic force antagonistic powers1 #aae ,deposition1 rate of1 shown by fossils1 #dg ,derbyshire1 veins in ,mountain ,limestone1 #fjh ,derivative shells of the ,red ,crag1 #aie-bjc ,desnoyers1 ,m41 on age of ,faluns1 #adb ----1 on ,eocene fossil footprints1 #bgb ,desor1 ,m41 on ,celtic coins in lake-dwellings1 #adi ,devonian ,period1 ,upper1 #dej ,middle1 #dej ,lower1 #dec ---- fossils of the ,eifel1 #ecd ---- of ,russia1 #ded ---- of ,united ,states and ,canada1 #dee ---- insects of ,canada1 #deg ---- strata1 classification of1 #dci-ej ,devonshire1 cleavage of slate rocks in1 #eic ,diabase1 #eje ,diagonal1 or cross-stratification1 #db ,diagram of fossiliferous rocks1 #acg ---- of plutonic and sedimentary formations1 #efg ,diallage1 #ejj1 #ejb ,diastopora diluviana1 ,bath ,oolite1 #cdc ,diatomace forming tripoli1 #ea ,diceras ,lonsdalii1 ,neocomian1 #caj ,didelphys ,azar1 ,recent1 #cdg ,didymograpsus geminus1 #dgf ---- ,murchisonii1 #dgc ,dike cutting through shale1 ,anglesea1 #eae ---- cutting through chalk1 ,antrim1 #eae1 #eaf ,dikelocephalus ,minnesotensis1 #dij ,dikes defined1 #cj ---- of ,monte ,somma1 #ebf ---- in ,palagonia1 ground-plan of1 #ecb ----1 volcanic or trap1 #eac-g ,diluvium1 origin of term1 #afg ,dinornis ,palapteryx1 of ,new ,zealand1 #afj ,dinotherium giganteum1 #bab ,diorite1 #eje ,dip and strike1 terms explained1 #hj ,diplograpsus folium1 ,llandeilo ,flags1 #dgd ---- pristis1 ,llandeilo beds1 #dgc ,dirt-bed of the ,purbeck1 #cca ,dogger-bank described1 #aje ,dolerite1 a variety of basalt1 #ejd ,dolomite defined1 #ch ,dolomitic conglomerate of ,bristol1 #cgc ,downs1 escarpments of ,north and ,south1 #ajd ,downton ,sandstone1 #dei ,dowson1 ,mr41 on shells of ,aldeby beds1 #aib ,drew1 ,mr41 on ,hastings ,sands1 #caf ,drift of ,ireland1 #aij ---- of ,norfolk cliffs1 #aij ---- of ,scandinavia1 #agd ---- of ,bridlington1 #ahi ---- carried by icebergs1 #agb ---- shells in ,canada1 #ahc ----1 contorted strata in1 #agh ----1 marine shells in ,scotch1 #age ,dudley ,limestone1 #dfe ,dufrenoy1 ,m41 on granite of ,pyrenees1 #ehb ,dumont1 ,professor1 on ,belgian ,lower ,eocene1 #bhb ,duncan1 ,dr41 on ,neozoic corals passing down to ,devonian1 #dcb ,dundry ,hill1 near ,bristol1 section of1 #acj ,dunker1 ,dr41 on wealden of ,germany1 #cai ,dura ,den1 yellow sandstone of1 #ddj ,,earth',s crust defined1 #bf ,echinoderms of ,suffolk ,crag1 #bjj ,echinosphronites balticus1 #dgb ,egerton1 ,sir ,p41 on fish of ,headon series1 #bef ----1 on fish of the ,permian1 #chi ----1 on fish of ,penarth beds1 #cff ,ehrenberg1 ,professor1 on term ,bryozoum1 #aig ----1 on ,silurian foraminifera1 #dgh ----1 on infusoria1 #ea ,eifel ,limestone1 #dec ----1 ,lake-craters of1 #ecd ---- ,miocene1 volcanic rocks of1 #eci ---- ,pliocene1 volcanoes of the1 #ecd ----1 trass of the1 #ece ,elephas antiquus1 molar of1 #afc ---- meridionalis1 molar of1 #afc ---- primigenius1 molar of1 #afb ,elevation craters1 theory of1 #dif ,elvans1 term explained1 #egb ---- of ,ireland and ,cornwall1 #fae ,elytron of ,buprestis8 ,stonesfield1 #cdf ,emmons1 ,professor1 on jaws of ,triassic quadruped1 #chc ----1 on ,dromatherium1 #chc ,encrinites of ,bradford1 #cdb ,encrinus liliiformis1 ,muschelkalk1 #cgi ,endogens1 term explained1 #cjc ,engihoul cave1 human and animal remains in1 #aeg ,england and ,wales1 glaciation of1 #ahj ,enstatite1 #eja ,eocene areas of ,europe1 map of1 #bej ---- foraminifera1 #bgd ---- formations of ,france1 #bgj-f ---- of ,england1 #beb ---- period1 volcanic rocks of1 #edc ----1 plutonic rocks of the1 #efh ----1 metamorphic rocks of the1 #eih ---- of ,france1 footprints in1 #bgb ---- and ,miocene1 line between the1 #bcj1 #bej ----1 term defined1 #adc ---- of the ,united ,states1 #bgh ,eozoon ,canadense1 oldest known fossil1 #dib ,epidote1 #ejj ,eppelsheim1 ,dinotherium of1 #bbe ,equisetace of the ,coal1 #dbd ,equisetites columnaris1 ,keuper1 #cgf ,equus caballus1 tooth of1 #afd ,erratic blocks1 nature of1 #afg ---- of ,greenland1 #aga ---- near ,chichester1 #aha ---- in the ,red ,crag1 #bja ,erratics1 ,alpine1 #afi ,escarpments explained1 #ajd ,eschara disticha1 ,white ,chalk1 #bif ,escharina oceani1 ,white ,chalk1 #bif ,estheria minuta1 ,trias1 #cgj ---- ovata1 ,richmond1 ,virginia1 #chc ,ethridge1 ,mr41 on ,atlantic mud1 #bhh ----1 on ,devonian series1 in ,devon1 #dej ----1 on ,devonian fauna1 #dea1 #ded ----1 on mollusca of ,bracklesham1 #bfj ----1 on ,st4 ,cassian fossils1 #cgg ,etna1 built up since ,newer ,pliocene1 #bjd ----1 ,pliocene lavas of1 #ebi ,ettingshausen on ,sheppey ,eocene fruit1 #bfe ,eunomia radiata1 ,bath ,oolite1 #cdb ,eunotia bidens1 ,atlantic mud1 #bhh ,euomphalus pentangulatus1 #dce ,eurite1 #eeg1 #egh ,euritic porphyry of ,norway1 #efb ,evans1 ,mr41 on ,archopteryx1 #ccg ,exogens1 #big ,exogyra virgula1 ,kimmeridge ,clay1 #ccf ,extracrinus 7,pentacrinus7 ,briareus1 ,lias1 #ceg ,,falconer1 ,dr41 on ,miocene fauna of ,siwalik ,hills1 #bbf ----1 on ,brixham ,cave flint knives1 #aeg ----1 on ,purbeck mammalia1 #cbf ,faluns of ,loire1 recent shells in1 #bad ---- of ,touraine1 #baa ,farnham1 phosphate of lime near1 #bii ,fascicularia aurantium1 ,coralline crag1 #aii ,faults in coal-measures of ,coalbrook ,dale1 #hh ---- described1 #hg-ib ---- often the result of repeated movements1 #ij ,fauna of the crag1 its relation to that of our present seas1 #bja ---- of the ,mountain ,limestone1 #dcj ---- of the ,paris basin1 #bga ,favosites cervicornis1 ,devonian1 #dea ---- ,gothlandica1 ,silurian1 #dfe ,favre1 ,m4 ,e41 on glaciers and moraines of the ,caucasus1 #ahg ,faxoe1 chalk of1 #bhe ,feldspar-porphyry1 #eeg ,feldspar1 varieties of1 #dii1 #ejj ,feldstone1 #eeg ,felis tigris1 tooth of1 #aff ,fenestella retiformis1 ,magnesian ,limestone1 #chh ,ferns of the coal1 #dba ,fife1 trap-dike in1 #edc ,fish1 fossil of the ,carboniferous1 #dcf ----1 ,eocene of ,monte ,bolca1 #edd ----1 oldest known fossil1 #dfc ----1 number of living1 #dde ----1 fresh-water and marine1 #eh ---- of the ,upper ,ludlow1 #dei ---- of the ,old ,red ,sandstone1 #ddc-e ---- of the ,permian marl slate1 #chi ---- of the brown coal1 #edj ---- of the ,lias1 #ceh ,fisherton1 ,greenland lemming in drift of1 #afa ,fissures1 filled with metallic matter1 #fjf ,fitton1 ,dr41 on the ,neocomian strata1 #cad ,fleming1 ,dr41 on ,parka decipiens1 #ddh ----1 on trap-dike in ,fife1 #edf ,flints in the ,chalk1 #bij ,flisk dike of ,fife1 #edf ,flora of the ,carboniferous1 #dbj ----1 ,devonian1 compared to ,carboniferous1 #deg ---- of the ,subapennines1 #bjh ----1 ,lower ,miocene of ,switzerland1 #bce ----1 ,miocene of the ,arctic ,regions1 #bci ----1 ,older ,pliocene of ,italy1 #bjh ---- of the ,permian1 #cib ---- of the ,upper ,cretaceous1 #cjb ----1 ,upper ,miocene of ,switzerland1 #bae-bb ---- of the ,wealden1 #cbj ,fluvio-marine or ,norwich ,crag1 #aic ,flysch of the ,alps1 #bgh ----1 plutonic rocks invading1 #efh ,folding and denudation of ,nova ,scotia ,carboniferous rocks1 #dag ,folds of parallel strata1 arrangement and direction of1 #ic ,foliation of crystalline rocks1 #eie ----1 irregularities in1 #eif ,folkestone and ,hythe beds1 #cjh ,fontainebleau1 ,gres de1 #bcj ,footprints in ,potsdam sandstone1 #dij ---- of reptiles in ,coal-measures1 #djh ----1 fossil in ,new red1 #cha ---- in ,paris gypsum1 #bgb ,foraminifera1 ,eocene1 #bge ---- of ,mountain ,limestone1 #dcg ---- of the ,chalk1 #bhg ,forbes1 ,mr4 ,david1 on glass cavities in quartz1 #eee ----1 on planes of foliation1 #eie ----1 on specific gravity of quartz1 #ejj ----1 on volcanic minerals1 #dih ,forbes1 ,professor ,e41 on fossils of ,bembridge beds1 #beb ----1 on ,hempstead beds1 #bdd ----1 on shells of the crag1 #bjj ----1 on sphronites1 #dgb ----1 on subdivisions of the ,purbeck1 #ccc ----1 on testacea of the ,faluns1 #bab ----1 on thickness of ,upper ,neocomian1 #cji ,forest-bed at ,cromer1 #aia ---- marble or cornbrash1 #cda ----1 submerged1 #ajc1 #ajd ----1 fossil in ,coal1 #djj ----1 fossil of ,isle of ,portland1 #ccb ,forfarshire1 ,cephalaspis beds of1 #ddf ----1 contorted strata in1 #agh ,formation1 term defined1 #bg ,fossil1 term defined1 #bi ---- trees erect in coal1 #daj ---- ,fish of ,old ,red ,sandstone1 #ddb ,fossiliferous groups1 table of succession of1 #aca ,fossils1 arrangement of1 in strata1 #dg ----1 destruction of1 in older formations1 #aci ----1 fresh-water and marine1 #eb ---- obliterated by metamorphic action1 #fjc ----1 recent1 and ,post-pliocene1 #aed-fe ---- of the drift1 #agf1 #ahj1 #aib ---- of the ,crags1 #aic-bjc ----1 ,upper ,miocene1 #bad-bi ----1 ,lower ,miocene of ,switzerland1 #bcf ---- of the ,hempstead ,beds1 #bdd ----1 ,eocene1 #bec ---- of the ,barton ,clay1 #bei ---- of the ,white ,chalk1 #bic ---- of the ,neocomian1 #cji ---- of the ,oolite1 #cbd ---- of the ,stonesfield ,slate1 #cdg ---- of the ,lias1 #ced ---- of the ,trias1 #cgj ---- of the ,magnesian ,limestone1 #chg ---- of the ,coal1 #dje ---- plants of the ,coal1 #dba ---- of the ,mountain ,limestone1 #dcj ----1 ,devonian1 #ddi ----1 ,silurian1 #dfj ----1 ,cambrian1 #dhd ---- ,laurentian1 #dib ,fournet1 ,m4 on metalliferous gneiss1 #ehf ----1 on veins in granite1 #faj ,fox1 ,rev4 ,d41 on ,isle of ,wight ,eocene fossils1 #bed ,fox1 ,mr4 ,r41 on lodes in ,cornwall1 #fad ,fractures of strata1 and faults1 #hg ,fragments1 included1 a test of age of plutonic rocks1 #efe ----1 included1 a test of age of strata1 #abi ---- a test of age in volcanic rocks1 #ebd ,france1 ,eocene formations of1 #bgj-f ----1 ,lower ,miocene of1 #bca ----1 ,upper ,miocene of1 #baa ,freshfield1 ,mr41 on absence of lakes in the ,caucasus1 #ahg ,fresh-water strata1 how distinguished from marine1 #ec-i ---- formation of ,auvergne1 #bcc ,fucoid sandstones of ,sweden1 #dhi ,fulgur canaliculatus1 ,maryland1 #bbh ,fuller's earth1 fossils of the1 #cdh ,fundy1 ,bay of1 fossil trees exposed in cliffs at1 #dab ,fusilina cylindrica1 #dch ,fusion of quartz1 #ejj ,fusus contrarius 7,trophon antiquum71 #aif ---- quadricostatus1 ,maryland1 #bbh ,,gabbro1 #eje ,gaillonella ferruginea1 and ,g4 distans1 #eb ,galapagos ,islands1 living marine saurian in1 #cfb ,galeocerdo latidens1 ,bracklesham1 #bfb ,galerites albogalerus1 ,white ,chalk1 #bid ,galestes in ,middle ,purbeck1 #cbh ,ganoids1 the type of ,old ,red ,sandstone fish1 #ddc ---- of the ,wealden1 #caf ---- of the ,trias1 #chc ,gaps in the sequence of fossil remains1 #ach ,garnet1 #ejj ,gases1 corrosion of rocks by1 #ehf ,gaudin on ,lower ,miocene of ,switzerland1 #bcf ---- on ,pliocene flora of ,italy1 #bji ---- on ,proteace in ,bournemouth ,eocene1 #bfc ,gault1 thickness and fossils of1 #cjj ,geikie1 ,mr4 ,a41 on ,ayrshire ,permian trap-rocks1 #ede ----1 on subarial denudation1 #aae ----1 on ice erosion of lake-basins1 #ahg ----1 on ,isle of ,mull volcanic rocks1 #eci ----1 on ,pentland ,old ,red volcanic rocks1 #edh ----1 on ,silurian metamorphic rocks1 #fjb ----1 on syenite of ,skye1 #efh ,geinitz1 ,m41 on ,permian flora1 #cic ,gemunder ,maar1 volcanic rocks of1 #ecd ,geneva1 ,lower ,miocene of1 #bcf ,geology defined1 #be ,gergovia1 tuffs and associated lacustrine strata of1 #edb ,germany1 ,lower ,miocene of1 #bdb ----1 ,triassic fauna of1 #cge ,gers1 ,upper ,miocene of1 #bae ,gervillia anceps1 ,neocomian1 #caj ---- socialis1 ,muschelkalk1 #cgi ,giant's ,causeway basalt1 age of1 #bdh ----1 laterite of the1 #eji ----1 columnar basalt of1 #eaj ,girgenti1 ,newer ,pliocene of1 #bjg ,glacial drift1 distribution and nature of1 #aff ---- epoch in the ,post-pliocene1 #aff ---- formations of ,pliocene age1 #ahi-ib ,glaciation of ,russia and ,scandinavia1 #agd ---- of ,scotland1 #age ---- of ,wales and ,england1 #ahj ---- of ,north ,america1 #ahb ,glaciers1 transporting and abrading power of1 #afh ,glasgow1 marine strata near1 #adf ,glauconie grossiere1 #bge ,glen ,tilt1 junction of granite and schist at1 #eei ,globiform pitchstone1 #eab ,globigerina bulloides1 #bhh ,globular structure of volcanic rocks1 #eaj ,glyptostrobus1 ,europus1 ningen1 #bbc ,gneiss1 granite veins traversing1 #efj ---- defined and figured1 #egg ----1 fundamental1 of ,scotland1 #dic ,gold mines of ,australia and ,chili1 #faf ---- veins of ,russia1 #faf ---- of ,california1 of age of alluvium1 #fag ,goldenberg1 ,professor1 on ,saarbrck coal insects1 #djf ,goldfuss1 ,professor1 on reptiles in coal1 #djf ,goniatites crenistria1 #dcf ---- ,listeri1 coal-measures1 #dje ,gppert1 on ,american forms in ,swiss ,miocene flora1 #bbc ---- on petrification1 #fh ---- on plants of coal-measures1 #cih ,gorgonia infundibuliformis1 ,permian1 #chh ,graham's ,island1 forming ashy conglomerate1 #edi ,grampians1 ,old ,red conglomerates of1 #gc ----1 trap-rocks of the1 #edg ----1 former glaciers in the1 #age ,grand ,canary1 ,upper ,miocene1 shelly tuffs of1 #eeh ,granite1 composition of1 #eeb ----1 graphic and columnar1 #eec1 #eed ----1 how far connected with trap-rocks1 #eeh ----1 hydrothermal action in formation of1 #eee ---- metamorphosing fossiliferous strata1 #eha ----1 porphyritic1 #eef ----1 oldest1 #egd ----1 protrusion of solid1 #egd ----1 passage of1 into trap1 #eeh ----1 schorly1 #eeg ---- veins1 #eei ---- veins in talcose gneiss1 #efj ,granton1 angiosperm found in coal at1 #dbi ,graptolites of ,llandeilo flags1 #dgd ,graptolites ,murchisonii4 ,llandeilo flags1 #dgc ,graptolithus priodon1 ,silurian1 #dfg ,gray's1 ,essex1 pachyderms found at1 #afa ,great 7or ,bath7 ,oolite1 #cdb ,greece1 ,upper ,miocene formations of1 #bbf ,greenland1 continental ice of1 #agj ----1 gradual sinking of1 #gb ,greenstone1 #eje ,gres de ,beauchamp1 ,paris basin1 #bgc ,gres de ,fontainebleau1 age of the1 #bcj ,griffiths1 ,sir ,r41 on yellow sandstone of ,ireland1 #dda ,grit defined1 #cf ,groups1 older1 rise highest above the sea1 #aci ---- why the newest to be studied first1 #adj ,gryllacris lithanthraca1 coal1 #dje ,grypha coated with serpul1 #dh ---- columba1 ,chloritic ,sand1 #cjj ---- convexa1 ,chalk1 #bie ---- incurva 7,g4 arcuata71 #ed1 #ced ---- virgula1 ,kimmeridge clay1 #ccf ,gryphite ,limestone1 #ced ,guadaloupe1 glass cavities in quartz of1 #eee ,gulf-,stream1 probable abrading power of1 #aje ,gmbel1 ,m41 on ,rhtic beds1 #cff ,gunn1 ,mrs41 on pot-stones in the chalk1 #bia ,gutbier1 ,colonel1 on ,permian flora1 #cic ,gymnogens1 term explained1 #cjc ,gypseous marls of ,auvergne1 #bcc ,gypsum and gypseous marl defined1 #ch1 #ci ,gyrolepis tenuistriatus1 ,rhtic beds1 #cfg ,,haime1 ,mr41 on palozoic corals1 #dca ,hakea silicina and ,hakea saligna1 ningen1 #bbb ,hall1 ,captain ,basil1 on ,cyclopean ,isles1 #ecj ,hall1 ,sir ,james1 on curved strata1 #ge ,hall1 ,mr4 ,j41 on ,appalachian palozoic rocks1 #aaj ,hallstadt and ,st4 ,cassian beds1 #cgf ,halysites catenularis1 ,silurian1 #dfe ,hamilton1 ,sir ,w41 on eruption of ,vesuvius1 #aggi1 #ebf ,hamites spiniger1 ,gault1 #cja ,hancock1 ,mr41 on ,protosaurus in ,permian1 #cij ,harkness1 ,professor1 on ,silurian metamorphic rocks1 #fjb ,harlech grits1 fossils of the1 #dhf ,harris1 ,major1 on the ,salt ,lakes1 #cgd ,harpactor maculipes1 ningen1 #bbd ,harpe1 ,m4 de la1 on ,bournemouth ,eocene flora1 #bfc ,hartung1 ,mr41 cited1 #dif ,hartz mountains1 mineral veins of1 #fjh ----1 ,bunter ,sandstein of1 #chj ,hastings ,sands1 subdivisions of the1 #caf ,hautes ,alpes1 granite of the1 #ega ,hauy on isomorphism1 #ejb ,headon series1 fossils of the1 #bee ,heat1 powerful in consolidating rocks1 #fe ----1 rocks upraised and folded by1 #ib ,hbert1 ,m41 on age of ,sables de ,bracheux1 #ccj ----1 comparison of ,sables ,moyens and ,barton shells1 #beh ----1 on pisolitic limestone1 #bhe ,hebrides1 dikes in the1 #ead ,heer1 ,professor1 on ,american genera in ,swiss ,miocene1 #bci ----1 on age of ,madeira leaf-bed1 #ecb ----1 on ,arctic ,miocene flora1 #bci ----1 on ,bear ,island flora1 #dda ----1 on ,bovey ,tracey ,miocene flora1 #bdg ----1 on fossil plants of ,switzerland1 #bae1 #bai1 #bba1 #bbd1 #bcf ----1 on ,lower ,miocene plants of ,mull1 #bdh ----1 on ,monte ,bolca ,eocene plants1 #bfc1 #edc ----1 on ,proteas of ,lower ,miocene1 #bcg ----1 on plants of ,hempstead beds1 #bdf ----1 on plants of coal-field1 ,virginia1 #chc ----1 on ,swiss ,miocene insects1 #bbc ----1 on supposed ,proteace of ningen beds1 #bba ----1 on ,superga fossil plants1 #bdd ,heidelberg1 varieties of granite near1 #efj ,heliolites porosa1 ,devonian1 #dea ,helix hispida 7plebeia71 #aee ---- labyrinthica1 ,headon1 #bee ---- occlusa1 ,bembridge1 #bec ---- ,turonensis1 faluns1 #ef ,hemicidaris ,purbeckensis1 ,purbeck1 #cbd ,hemipneustes radiatus1 ,chalk1 #bhd ,hemitelites ,brownii1 ,inferior ,oolite1 #cej ,hempstead beds1 subdivisions of the1 #bdd ,henry1 on absorption of carbonic acid gas in water1 #ehe ,henslow1 ,professor1 on dike in ,anglesea1 #eae ----1 on ,red ,crag coprolite bed1 #aig ,herschel1 ,sir ,j41 on slaty cleavage1 #eij ,hertfordshire pudding-stone1 #fb ,heterocercal tail of fish1 #chi ,hicks1 ,dr41 on fossils of ,arenig beds1 #dgf ----1 on fossils of ,harlech grits1 #dhf ----1 on ,menevian beds1 #dhe ,himalaya1 shells #ah1jjj feet high in1 #bi ----1 ,upper ,miocene of1 #bbf ,hippopodium ponderosum1 ,lias1 #cee ,hippopotamus1 tooth of1 #afd ,hippurite ,limestone1 #cjd ,hippurites organisans1 ,chalk1 #cjf ,histioderma hibernica1 #dhf ,hitchcock1 ,professor1 on ,trias footprints1 #cha ,holoptychius nobilissimus1 scale of1 and restoration1 #ddb ,homalonotus ,delphinocephalus1 #dfg ---- armatus1 ,devonian1 #ded ,homfray1 ,mr41 on fossils of ,tremadoc beds1 #dhc ,homocercal tail of fish1 #chi ,hooghly ,river1 analysis of water1 #fi ,hooker1 ,dr41 on conifer1 #dbi1 #dcj ----1 on structure of sigillaria1 #dbf ----1 on sporangia of ,silurian plant1 #dfj ,horizontality of strata1 #dj ,horizontal strata1 upheaval of1 #ga ,hornblende1 #dii1 #ejb ,hornblende-schist1 #egh ,hrnes1 ,dr41 on fossil mollusca of ,vienna basin1 #bbe ,horstead1 pot-stones at1 #bia ,hour-glass illustrating the destruction and renovation of land1 #aai ,howse1 ,mr41 on ,protosaurus in ,permian1 #cij ,hubbard1 ,professor1 on granite of ,white ,mountains1 #efe ,hudson ,river ,group1 fossils of the1 #dgi ,hughes1 ,mr4 ,t4 ,mc,kenny1 cited1 #dej ----1 on slaty cleavage1 #ehi ----1 on protrusion of solid granite1 #ege ,hull1 ,mr4 ,e41 on breccias in ,permian1 #cia ----1 on carboniferous of ,lancashire1 #cie ----1 on carboniferous rocks of north of ,england1 #aaa ----1 on faults in ,lancashire coal-field1 #ia ----1 on anticlinals and synclinals1 ,lancashire1 #he ----1 on thickness of the ,upper ,trias1 #cfi ----1 on thickness of ,permian1 #chf ----1 on three lines of flexure since the coal in ,lancashire1 #id ,human remains of ,recent ,period1 #aeg ---- in cavern deposits1 #aef ,humboldt1 on mineral character of rocks1 #fjb ,humphrey and ,abbot on ,mississippi denudation1 #aad ,hungary1 trachyte of1 #eeh ,hunt1 ,sterry1 on action of water in metamorphism1 #ehe ,huronian series1 thickness of the1 #dij ,huxley1 ,professor1 on ,atlantic chalk-mud1 #bhg ----1 on affinity between reptiles and birds1 #cch ----1 on batrachians of the coal1 #djg ----1 on fish of ,old ,red ,sandstone1 #ddc-e ----1 on ,pteraspis1 #dfc ,hyna den of ,kirkdale cave1 #aeg ,hyna spela1 tooth of1 #afe ,hybodus plicatilis1 ,rhtic beds1 #cfg ---- reticulatus1 ,lias1 #cei ,hydrothermal action producing metamorphism1 #ehd ---- in formation of granite1 #eee ---- forming granite veins1 #egc ,hymenocaris vermicauda1 #dhd ,hyperodapedon ,gordoni1 ,trias1 #cgj ,hypersthene1 #dii1 #ejb ---- rock1 #eje ---- rocks of ,skye1 #dia ,hypogene rocks1 uniformity of mineral character in1 #fjb ---- rocks1 term defined1 #bf ,hypsiprymnus ,gaimardi1 molar of recent1 #cbg ,hythe1 ,neocomian beds of1 #cjh ,,ice1 erosion of lake-basins considered1 #ahd1 #ahh ----1 abrading power of1 #afh ----1 continental1 of ,greenland1 #agj ,icebergs1 drift carried by1 #agb ---- stranded in ,baffin's ,bay1 #agc ,ice-borne erratics at ,chichester1 #aha ,iceland1 glass cavities in quartz of1 #eee ----1 flow of lava in1 #ebc ,ichthyosaurus communis1 ,lias1 #cfa ,idocrase1 #ejj ,ichthyodorulite of the ,lias1 #cei ,iguanodon ,mantelli1 ,weald ,clay1 #cae ,ilfracombe ,group of ,devon1 #ddi ,inclined strata1 #gc ,india1 ,miocene formations of1 #bbf ,india1 ,upper ,miocene of1 #bbf ,inferior ,oolite1 thickness and fossils of1 #cdi ,infusoria in tripoli1 #ea ,inland sea-cliffs1 #ajc ,inoceramus ,lamarckii1 ,white ,chalk1 #bie ,insect in ,american coal1 #daf ---- beds of the ,lias1 #cfc ,insect wing of neuropterous1 #cfc ,insects1 ,devonian1 of ,canada1 #deg ---- in ,european coal1 #dje ----1 ,miocene1 of ,croatia1 #bdc ----1 ,upper ,miocene1 at ningen1 #bbc ,intrusion1 a test of age of ,plutonic rocks1 #efe ----1 a test of age of volcanic rocks1 #eba ,inundation mud of rivers1 #aec ,ireland1 glacial drift of1 #aij ----1 yellow sandstone of1 #dda ,iron pyrites1 #ejj ---- weapons of ,swiss lake-dwellings1 #adh ,isastra oblonga1 ,portland ,sand1 #cce ,isle of ,bourbon1 lava current of the1 #eff ---- ,wight1 ,hempstead beds1 #bdd ---- ,wight1 ,eocene beds1 #bee ---- ,mull1 ,miocene leaf-bed of1 #bdg ---- ,mull1 volcanic rocks1 #bdh ,isomorphism1 theory of1 #ejb ,italy1 ,lower ,miocene of1 #bdd ----1 ,older ,pliocene volcanoes of1 #ebc ----1 ,pliocene of1 #bjg ----1 ,older ,pliocene flora of1 #bjh ----1 ,upper ,miocene strata of1 #bbf ,,jamieson1 ,mr4 ,t4 ,f41 on ,scotch glacial drift1 #age ,jaws of mammalia in ,purbeck1 #cbg ,jeffreys1 ,mr4 ,gwyn1 on ,atlantic mud1 #bhh ,jointed structure of metamorphic rocks1 #ehi ,jones1 ,dr4 ,rupert1 on ,eozoon ,canadense1 #dia ,jorullo1 lava stream of1 #eff ,judd1 ,mr41 on ,speeton clay1 #caa ,jukes1 ,mr41 on ,tarannon shales1 #dfh ,jura1 erratic blocks on the1 #afi ----1 structure of the1 #hb ,,kangaroo1 jaws of1 #aei ,ksegrotte1 ,bertrich ,baden1 ,basaltic pillars of1 #eab ,kaup1 ,professor1 on footprints of the ,trias1 #cgc ,keilhau1 ,professor1 on granite veins1 #efb ----1 on planes of foliation1 #eie ----1 on ,silurian granite of ,norway1 #egc ----1 on protrusion of granite1 #eha ,keller1 ,dr4 ,f41 on lake-dwellings1 #adh ,kelloway ,rock1 percentage of ,oxford clay fossils in1 #cda ,kentish ,rag1 #cjh ,keuper1 of ,germany1 #cge ---- or ,upper ,trias of ,england1 #cfi ,kilkenny1 fossil plants of1 #dda ,killas1 altered by granite in ,cornwall1 #ehb ,kiltorkan1 yellow sandstone of1 with ,anodonta1 #dda ,kimmeridge ,clay1 #cce ,king1 ,dr41 on reptile footprints in coal1 #djg ,king1 ,mr41 on ,permian fossils1 #chh ,kirkdale cave1 hyna's den of1 #aeg ,kitchen-middens of ,denmark1 #adf ,kleyn ,spawen beds1 #bdb ,knen1 ,baron von1 on ,brockenhurst shells1 #beg ,koninck1 ,m4 de1 on ,mountain ,limestone fish1 #dcf ----1 on shells of ,mayence basin1 #bdb ,koninckia ,leonhardi1 ,hallstadt1 #cgg ,,labrador rock1 #eje ---- series1 #dij ,labradorite1 #dii1 #eja ,labyrinthodon ,jgeri1 section of tooth1 #cga ----1 tooth of1 #cgj ,labyrinthodonts of ,coal1 #djg ,lake-craters of the ,eifel1 #ecd ,lake districts1 southern limits of the1 #ahd ,lake-dwellings1 scarcity of human remains in1 #adi ---- of ,switzerland1 #adh ,lakes1 deposits in1 #bg ----1 connection of1 with glacial action1 #ahd-h ,lamarck on bivalve mollusca1 #ed ,lamination of clay slate1 #eid ,lamna elegans1 ,bracklesham1 #bfb ,lancashire1 vast thickness of rocks without corresponding altitude in1 #aaa ,land1 balance of dry1 how preserved1 #aaf1 #aah ---- has been raised1 not the sea lowered1 #gj ----1 mean height of1 above the sea1 #aae ----1 rise of1 in ,sweden1 #gb ----1 rise and fall of1 affecting denudation1 #aja ,land-ice1 action of1 in ,greenland1 #aga ,land's ,end1 columnar granite at1 #eec ----1 porphyritic granite at1 #eef ,la ,roche1 recent deposits in estuary of1 #dj ,lartet1 ,m41 on mammalia of ,faluns1 #bad ----1 on ,gastornis ,parisiensis1 #bgf ----1 on reindeer period1 #aej ,lastra stiriaca1 ,monod1 #bci ,lateral compression causing curved strata1 #ge ,laterite of ,giant's ,causeway1 #eji ,laurentian gneiss of ,scotland1 #dic ---- ,group1 ,upper and ,lower1 #dia ---- metamorphic rocks1 #fja ---- volcanic rocks1 #edi ,lava1 #ejg ---- consolidating on slopes1 #dif ---- currents of ,auvergne1 #eda ---- streams1 effect of1 #cj ---- of ,la ,coupe d',ayzac1 #eaa ---- of ,jorullo1 #eff ,lead veins1 age of1 #faf ,leaf-bed of ,madeira in basalt and scori1 #ecb ----1 ,isle of ,mull ,miocene1 #bdh ,leda amygdaloides1 ,london ,clay1 #bff ---- ,deshayesiana 7,nucula ,deshayesiana71 #bda ---- lanceolata 7,l4 oblonga71 ,scotch drift1 #agf ---- truncata1 ,scotch drift1 #agg ,lee1 ,mr4 ,j4,e41 on ,pteraspis of ,lower ,ludlow1 #dfc ,leidy1 ,dr41 on fossil quadrupeds of ,nebraska1 #bdi ,leperditia inflata1 coal-measures1 #dje ,lepidodendron1 ,griffithsii1 #dda ---- corrugatum1 carboniferous41 #dag ---- ,sternbergii1 coal-measures1 #dbc ,lepidolite1 #dii1 #eja ,lepidostrobus ornatus1 ,coal1 #dbd ,lepidotus gigas1 ,lias1 #ceh ---- ,mantelli1 ,wealden1 #cag ,leptna depressa1 ,wenlock1 #dff ---- ,moorei1 ,lias1 #cee ,level of surface altered by change of subterranean heat1 #aai ,lewis1 hornblendic gneiss of1 #fja ,lias1 fishes of the1 #ceh ----1 fossils of the1 #ced ---- and ,oolite1 origin of the1 #cfd ----1 reptiles of the1 #cfj ----1 insects of the1 #cfc ----1 plants of the1 #cfd ----1 plutonic rocks of the1 #ega ----1 subdivisions of the1 #cec ----1 volcanic rocks of the1 #edd ,liebig1 on conversion of coal into anthracite1 #djc ----1 on origin of stalactite1 #aef ,lige1 limestone caverns at1 #aef ,lightbody1 ,mr41 on ,lower ,ludlow shales1 #dfa ,lignite1 conversion of into coal1 #djc ,lima giganteum1 #ced ---- ,hoperi1 ,chalk1 #cjj ---- spinosa1 ,white ,chalk1 #bid ,limagne d',auvergne1 ,lower ,miocene mammalia of the1 #bcd ,limburg beds1 #bdb ,lime1 scarcity of1 in metamorphic rocks1 #fjd ---- in solution1 source of1 #fi ,limestone1 block of striated1 #afh ----1 brecciated1 #chg ---- of chemical and organic origin1 #fa ----1 compact1 #eja ----1 ,hippurite1 #cjd ----1 magnesian1 #chg ----1 metamorphic or crystalline1 #egi ----1 ,mountain1 and its fossils1 #dcj-h ----1 striated1 #afh ,limna longiscata1 #ee ,lingula beds1 volcanic tuffs of the1 #edi ,lingula ,credneri1 ,permian1 #chh ,lingula ,flags1 fossils of the1 #dhd ,lingula ,dumortieri1 ,crag1 #bjj ---- ,lewisii1 ,ludlow1 #dfb ,lingulella ,davisii1 #dhd ,lipari ,isles1 tufas in1 #ehf ,liquidambar europum1 #bji ,lithrostrotion basaltiforme1 ,carboniferous1 #dcb ,lits coquilliers1 #bge ,littoral denudation defined1 #ajb ,lituites giganteus1 ,ludlow1 #dfc ,llanberis slates1 #dhf ,llandeilo ,flags1 fossils of the1 #dgc-e ,llandeilo formation1 thickness of the1 #dge ----1 ,lower1 #dge ,llandovery ,group1 classification of the1 #dfh ---- ,rocks1 thickness of the ,lower1 #dfi ,loam defined1 #ch1 #aec ,lodes1 shells and pebbles in1 #fjh ---- ,see ,mineral ,veins4 ,loess of fluviatile loam described1 #aec ----1 fossil shells of the1 #aed ,logan1 ,sir ,w41 on ,eozoon ,canadense1 #dij ----1 on ,gaspe sandstones1 #dee ----1 on ,huronian and ,laurentian1 #dij ----1 on stigmaria in under-clays1 #cih ----1 on thickness of ,nova ,scotia coal1 #dji ----1 on thickness of ,laurentian in ,canada1 #aac ,loire1 faluns of the1 #baa ,london ,clay1 fossils of the1 #bfd1 #bff ,longevity1 relative1 of mammalia and testacea1 #afb ,longmynd ,group1 fauna of the1 #dhf ,lonsdale1 ,mr41 on corals of ,america1 #bbi ----1 on ,devonian fossils1 #ddi ----1 on ,stonesfield slate1 #cde ----1 on ,united ,states ,miocene corals1 #bbi ,lonsdaleia floriformis1 ,carboniferous1 #dcb ,lowe1 ,reverend ,r4 ,t41 on ,mogador shells1 #ecg ,lubbock1 ,sir ,j41 on the two stone-periods1 #adg ,lucina serrata1 ,bracklesham1 #bfb ,ludlow formation1 ,upper1 #dei2 ,lower1 #dfa ----1 bone-bed of the ,upper1 #dei ,lulworth ,cove1 dirt-bed of1 #ccc ,lycett1 ,mr41 on fossils of the ,great ,oolite1 #cdd ,lycopodiace of ,coal1 #dbb ,lycopodium densum1 living species1 #dbc ,lym-fiord1 mingled fresh-water and marine strata of1 #ei ,lymnea caudata1 ,headon1 #bef ---- longiscata1 ,bembridge1 #bec ,lynton ,group of ,devon1 #ded ,,maclaren1 ,mr41 on ,pentland ,hills1 volcanic rocks1 #edh ,macclesfield1 marine shells #a1bjj feet high at1 #aha ,mac,clintock1 ,sir ,l41 on ,atlantic mud1 #bhg ,mac,culloch1 ,dr41 on ,aberdeenshire granite1 #eeh ----1 on basaltic columns in ,skye1 #eaj ----1 on formation of hornblende-schist1 #ehb ----1 on trap1 #eai ,mac,mullen1 ,mr4 ,j41 on ,eozoon ,canadense1 #dia ,macropus atlas1 lower jaw of1 #aeh ---- major 7living71 lower jaw of1 #aei ,madeira1 beds of laterite in1 #eji ----1 dike in valley in1 #eac ----1 ,pliocene leaf-bed and shells in lavas of1 #ecb ----1 ,miocene volcanic rocks of1 #ecf ----1 wind1 removing scori in1 #ig ,maestricht beds and their fossils1 #bhc ,maffiotte1 ,don ,pedro1 cited1 #ech ,magas pumila1 ,white ,chalk1 #bid ,magnesian ,limestone defined1 #ch ---- and marl-slate1 #chg ,magnetite1 #ejj ,maidstone1 ,upper ,cretaceous fossils of1 #big ,malacolite1 #ejb ,malaise1 ,professor1 on ,engihoul cave1 #aeg ,mammalia1 anterior to ,paris gypsum1 table of1 #cbi ----1 extinct1 coeval with man1 #aeb1 #aeg ----1 fossil1 of ,middle ,purbeck1 #cbe ----1 fossil1 in ,pliocene in ,val d',arno1 #bjh ----1 fossil1 in the ,crag1 #aic1 #aig ----1 fossil1 of ,vienna basin1 #bbe ---- of the ,limagne d',auvergne1 #bcd ---- of ,siwalik ,hills1 #bbg ---- of the ,stonesfield slate1 #cde ----1 teeth of ,post-pliocene1 #afe ,mammalia and testacea1 comparative longevity of1 #afb ,mammoth1 rude carving of in ,perigord cave1 #aej ---- in ,scotch till1 #age ---- ,see ,elephas primigenius4 ,man1 antiquity of1 #aeb ,manfredi on amount of subarial denudation1 #aad ,mantell1 ,dr41 on iguanodon of ,wealden1 #cac ----1 on ,oxford ,clay belemnites1 #cdj ----1 on ,wealden fossils1 #caf ,mantellia nidiformis1 ,purbeck1 #cca ,map of ,chalk formation in ,france1 #cje ---- of ,eocene tertiary basins1 #bej ---- of ,hallstadt and ,st4 ,cassian beds1 #cgf ,marble defined1 #cg ---- of ,carrara1 metamorphic1 #eii ,marcou1 ,m41 on age of ,wealden beds1 #cai ,margaric acid1 #eia ,marine fauna of the ,carboniferous1 #dcb ---- beds underlying the ,london ,clay1 #bfi ---- and brackish-water strata in coal1 #djd ---- strata1 how distinguished from fresh-water1 #ec-ei ,marl from ,lake ,superior1 #fc ---- and marl-slate defined1 #ch ----1 red1 green1 and white1 of ,auvergne1 #bcc ---- slate of ,middle ,permian1 #chg ,marsupials1 extinct1 of ,australia1 #aei ,marsupites ,milleri1 ,white ,chalk1 #bid ,massachusetts1 plumbago of1 #ehc ,mastodon arvernensis1 molar of1 ,norwich crag1 #aic ---- giganteus1 in ,united ,states after the drift1 #ahc ,mayence basin tertiaries1 #bdb ,may-,hill ,sandstone1 #dfh ,mechanical and chemical deposits1 #fj ---- theory of cleavage1 #eib ,mediterranean1 one zoological province1 #abg ,megalodon cucullatus1 ,devonian1 #deb ,melania inquinata 7,cerithium melanoides71 #ee1 #bfh ,melania turritissima1 ,bembridge1 #bec ,melanopsis buccinoidea1 #ee ,melaphyre1 a variety of basalt1 #ejd ,menevian beds and their fossils1 #dhd ,mesozoic1 term explained1 #abc ---- and ,cainozoic periods1 gap between the1 #bhb ---- and ,palozoic rocks1 limits of the1 #che ,metals1 relative age of different1 #fad ,metamorphic limestone1 #egi ---- strata1 origin of1 #egi ---- theory1 objections to1 considered1 #ehg ---- rocks defined1 #cb ,metamorphic rocks1 #egf ----1 cleavage of1 #ehh ----1 scarcity of lime in1 #fjd ----1 ages of1 #eig ----1 order of succession of1 #fjb ----1 uniformity of mineral character in1 #fjb ,metamorphism1 hydrothermal action producing1 #ehd ,metamorphosis of trilobites1 #dga1 #dhg ,meteorites1 minerals in1 #eja ,mexico1 ,gulf of1 terrestrial remains washed into1 #abh ,meyer1 ,mr4 ,karl1 on fossil shells of ,madeira1 #ecg ----1 ,m4 ,h4 von1 on reptiles in coal1 #djg ----1 on ,wealden of ,germany1 #cai ,miascite1 #eeh ,mica and its varieties1 #dii1 #eja ----1 how deposited1 #dj ---- schist or micaceous schist1 #egh ,micaceous sandstone1 origin of1 #cf ,micraster cor-anguinum1 #bid ,microconchus carbonarius1 coal-measures1 #dje ,microlestes antiquus1 ,upper ,trias1 #cfh ,migrations of quadrupeds1 #afa ,miliolite limestone1 #bgd ,miller1 ,hugh1 on ,old ,red ,sandstone fish1 #ddc ----1 on salt lakes1 #cge ,milne ,edwards1 ,mr41 on ,palozoic corals1 #dcb ,minchinhampton1 ,great ,oolite of1 #cdd ,mineral composition a test of age of volcanic rocks1 #ebc ---- a test of age of plutonic rocks1 #efe ---- a test of age of strata1 #abd ---- character of hypogene rocks1 #fjb ---- springs of ,auvergne1 #fjd ,mineral veins1 #fje ---- formed in fissures1 #fjf ----1 successive formation of1 #fji ----1 swelling and contraction of1 #faa ----1 relative age of1 #fad ----1 pebbles in1 #fjh ,mineralisation of organic remains1 #fe ,minerals in meteorites1 #eja ----1 table of the most abundant in hypogene rocks1 #dii ,miocene of ,bordeaux and south of ,france1 #bad ---- and ,eocene1 line between the1 #bcj1 #bea ----1 ,lower1 of ,england1 #bdd ----1 ,lower1 of ,germany and ,croatia1 #bdb ----1 ,lower1 of ,central ,france1 #bca ----1 ,lower1 of ,italy1 #bdd ----1 ,lower1 of ,nebraska1 ,united ,states1 #bdh ----1 term defined1 #adc ----1 ,upper1 of the ,bolderberg1 #bbd ----1 ,upper1 of ,france1 #baa ----1 ,upper1 of ,italy1 #bbf ----1 ,upper1 of ,greece1 #bbf ----1 ,upper1 of ,india1 #bbf ----1 ,upper1 of ,vienna basin1 #bbd ,mississippi1 sediment of1 used as a test of denudation by rivers1 #aad ---- valley1 deposition and denudation in the1 #ajb ,mitchell1 ,mr41 on ,aralia fruit in ,alum ,bay1 ,eocene1 #bfc ,mitchell1 ,sir ,t41 on ,wellington caves1 #aeh ,mitchell1 ,rev4 ,hugh1 on ,pteraspis1 #ddf ,mitra ,scabra1 ,barton clay1 #bei ,mitscherlich1 on ,isomorphism1 #ejb ,modiola acuminata1 ,permian1 #chg ,moel ,tryfaen1 shells found at1 #aha ,mohs on isomorphism1 #ejb ,molasse1 ,lower1 of ,switzerland1 #bce ----1 ,middle1 or ,marine1 of ,switzerland1 #bbc ----1 ,upper1 fresh-water1 of ,switzerland1 #bag ----1 term explained1 #bag ,mollusca4 ,see ,shells4 ----1 longevity of species of1 #afb ---- of ,hallstadt beds1 #cgg ----1 value of1 in classification1 #adb ---- of the ,carboniferous1 #dce ,monitor of ,thuringia1 #dfc ,monoclinic feldspars1 #eja ,monod1 flora of the ,lower ,molasse at1 #bcf ,mons1 unconformable strata near1 #ie ,montblanc1 talcose granite of1 #efh ---- ,dor1 ,auvergne1 extinct volcanoes of1 #bcb ----1 age of volcano of1 #eda ,monte ,bolca1 fossil fish of1 #edc ---- ,calvo1 section of cross stratification1 #dd ---- ,mario1 age of volcanic deposits of1 #ecc ---- ,nuovo1 formed #aech1 #ebe ,montmartre1 gypseous series of1 #bgj ,monts ,dome1 ,auvergne1 extinct volcanoes1 #die ,moore1 ,mr4 ,c41 on ,rhtic beds1 #cff ----1 on ,upper ,trias quadrupeds1 #cfi ,moraines described1 #afi ,morea1 cretaceous volcanic rocks of1 #edd ,mortillet1 ,m4 de1 on ice-erosion of lake-basins1 #ahd ,morton1 ,dr41 on age of ,american cretaceous rocks1 #cjg ,mosasaurus ,camperi1 ,chalk1 #bhd ,mountain ,limestone1 fossils of the1 #dcc-h ,mull1 ,isle of1 leaf-bed1 #bdg ,mnster1 ,count1 on fossils of ,solenhofen1 #ccg ,murchison1 ,sir ,r41 on brackish-water strata in coal1 #djd ----1 on ,devonian series1 #dci1 #ddi1 #ded ----1 on ,devonian ichthyolites1 #dec ----1 on ,eocene igneous rocks1 #bgh ----1 on ,llandovery beds1 #dfh ----1 on ,laurentian gneiss of ,scotland1 #dib ----1 on metamorphic rocks of ,north ,highlands1 #fja ----1 on ,monte ,bolca fish-beds1 #edc ----1 on name ,permian1 #che ----1 on ,old ,red ,sandstone1 #ddi ----1 on ,palozoic strata1 ,queenaig1 #aab1 #aac ----1 on protrusion of solid granite1 #egd ----1 on ,silurian1 #deh1 #dei1 #dfa1 #dfg1 #dgj1 #dgc1 #dge ----1 on ,tertiary volcanic rocks of ,italy1 #ecc ----1 on thickness of chalk in ,russia1 #bhg ----1 on thickness of the ,trias1 #cfi ----1 on the ,upper 8,old ,red01 #dfh ,murchisonia gracilis1 #dgi ,murex vaginatus1 #bjd ,muschelkalk1 fossils of the1 #cgh ,muscovite1 or common mica1 #dii1 #eja ,musk-ox1 fossil1 in ,thames valley1 #afa ,myliobates ,edwardsi1 ,bracklesham1 #bfa ,mytilus septifer1 ,permian1 #chg ,,naples1 ,post-pliocene volcanic rocks of1 #ebe ----1 escape of carbonic acid near1 #fjd ,natica clausa1 ,scotch drift1 #agf ---- helicoides1 ,chillesford beds1 #aib ,natrolite1 #ejj ,nautilus centralis1 ,london ,clay1 #bff ---- ,danicus1 ,faxoe ,chalk1 #bhf ---- plicatus1 ,hythe beds1 #cji ---- truncatus1 ,lias1 #cef ---- ziczac 7,aturia ziczac71 #bff ,nebraska1 ,miocene strata of1 #bdh ,necker1 ,m41 on 8underlying0 igneous rocks1 #efb ----1 on dikes in ,vesuvius1 #ebf ,neocomian1 ,upper1 #cjh ----1 ,middle1 #cab ----1 ,lower1 #cab ----1 use of the term1 #bhb ,neolithic era1 #adg ,neozoic type of corals1 #dca ,nerina ,goodhallii1 ,coral ,rag1 #cci ,nerinan limestone1 #cdj ,nerita conoidea 7,n4 ,schmidelliana71 #bge ---- costulata1 ,great ,oolite1 #cde ---- granulosa1 #ee ,neritina concava1 ,headon1 #bee ---- globulus1 #ee ,neufchtel1 coins and iron tools in lake of1 #adi ,newberry1 ,dr41 on flora of ,american cretaceous rocks1 #cjg ,newcastle coal-field1 faults in1 #ij ,newfoundland bank described1 #ajf ,new ,jersey1 mastodon in1 #ahc ,new ,madrid1 8,sunk ,country0 in1 #djb ,new ,red sandstone of ,connecticut ,valley1 #cha ----1 trappean rocks of the1 #ede ,new ,york1 ,devonian strata of1 #def ----1 ,cambrian strata of1 #dij ----1 ,silurian strata of1 #dgh ----1 ,laurentian strata of1 #dia ,niagara ,limestone1 fossils of the1 #dgi ,nidau1 iron tools in lake of1 #adh ,nile1 homogeneous mud of the1 #aed ,ninety-fathom dike in coal1 #ij ,nipadites ellipticus1 ,sheppey1 #bfd ,nodules in strata1 how formed1 #fc ,noeggerathia cuneifolia1 ,permian1 #cic ,nomenclature of rocks1 #adj ---- of volcanic minerals1 #dii ,norfolk cliffs1 drift of1 #aij ,north ,america4 ,see ,america4 ,norway1 ,cambrian of1 #dhi ----1 foliation of crystalline schists in1 #eie ----1 granite veins in gneiss of1 #egc ----1 granite altering fossiliferous strata in1 #eha ,norwich1 or ,fluvio-marine crag1 #aic ,nova ,scotia coal-measures1 #dji ---- coal1 reptiles and shells in1 #dad ----1 folding and denudation of beds in1 #dag ,nucula ,cobboldi1 ,crag1 #aid ,nummulites lvigata1 ,bracklesham1 #bfj ---- ,puschi1 ,pyrenees1 #bgh ---- variolaria1 ,bracklesham1 #bei ,nummulitic formations1 #bgg ,,obolus ,,apollinis1 in ,russian grit1 #dgh ,obsidian1 #eje ,oceanic areas1 permanence of1 #aag ningen1 ,upper ,miocene beds of1 #bae ,oeynhausen1 ,m4 von1 on ,cornish granite veins1 #efj ,ogygia ,buchii1 #dgd ,oldhamia radiata3 ,o4 antiqua1 #dhg ,old ,red ,sandstone1 ,upper1 #ddj ----1 ,middle1 with fish1 #ddc ----1 ,lower1 #ddf ----1 trap of the1 #edg ----1 classification of1 #dci ,olenus micrurus1 #dhd ,oligocene1 term for ,lower ,miocene1 #bcj1 #bdd ,oligoclase1 #dii1 #ejj ,oliva ,dufresnii1 ,bolderberg1 ,belgium1 #bbd ,olivine1 #dii ,omphyma turbinatum1 ,silurian1 #dff ,onchus tenuistriatus1 ,silurian1 #dfj ,oolite1 classification and physical geography of the1 #cba ----1 defined1 #cg ----1 ,inferior1 fossils of the1 #cdi1 #cej ---- and ,lias1 origin of the1 #cfd ---- and ,chalk1 ,palontological break between1 #cch ,oolitic strata1 palontological relations of1 #cea ---- volcanic rocks1 #ede ,ophioderma tenuibrachiata1 ,lias1 #ceg ,oppel on zones of ,lias1 #cec ,orbigny1 ,alcide de1 on foraminifera of ,vienna basin1 #bbe ----1 on orbitoidal limestone1 #bgi ----1 on ,pisolitic limestone1 #bhe ----1 on ,snonian1 #cjb ,oreodaphne ,heerii1 ,italian ,pliocene1 #bji ,organic remains1 mineralisation of1 #fe ----1 tests of age of strata1 #abe ----1 tests of age of volcanic rocks1 #ebb ----1 geological provinces of1 #abg ,oriskany ,sandstone1 #dgh ,orthis elegantula1 ,ludlow1 #df ---- grandis1 ,caradoc beds1 #dgj ---- tricenaria1 ,bala beds1 #dgj ---- vespertilio1 ,bala beds1 #dgj ,orthoceras duplex1 #dgd ---- ,ludense1 ,silurian1 #dfc ---- laterale1 #dcf ---- ventricosum1 ,silurian1 #dfb ,orthoclase1 #dii1 #ejj ,orthoclastic feldspars1 #eja ,osborne or ,st4 ,helen's series1 ,eocene1 #bee ,osteolepis1 ,old ,red ,sandstone1 #ddd ,ostraceon1 spine of1 ,bracklesham1 #bfa ,ostrea acuminata1 ,fuller's earth1 #cdi ---- carinata1 ,chalk marl1 #cjj ---- columba1 ,chloritic sand1 #cjj ---- gregarea1 ,coral ,rag1 #cci ---- deltoidea1 ,kimmeridge clay1 #ccf ---- distorta1 ,middle ,purbeck1 #cbd ---- expansa1 ,portland sand1 #ccf ---- ,marshii1 ,oolite1 #cea ---- vesicularis1 ,chalk1 #bie ,otodus obliquus1 ,bracklesham1 #bfb ,outcrop of strata1 #hc ,overlapping strata1 #ie ,owen1 ,professor on ,archopteryx1 #ccg ----1 on ,eocene ,zeuglodon1 #bgi ----1 on footprints in ,trias1 #chb ----1 on fauna of ,sheppey1 #bfe1 #bfg ----1 on ,gastornis ,parisiensis1 #bgf ----1 on ,labyrinthodon1 #cgj ----1 on mammalia of ,stonesfield1 #cdg ----1 on ,purbeck mammalia1 #cbf1 #cbh ----1 on reptiles of coal1 #djg1 #dad ----1 on zoological provinces of extinct animals1 #afj ,ox1 tooth of 7recent71 #afe ,oxford ,clay1 thickness and fossils of1 #cdj ,,pagham1 erratic block at1 #ahb ,palaster asperimus1 #dgb ,palchinus gigas1 ,mountain ,limestone1 #dc ,palocoma tenuibrachiata1 ,lias1 #ceg ,paloniscus1 ,permian fish1 #chi ---- comptus1 ,p4 elegans1 ,p4 glaphyrus1 #cij ,palotherium magnum1 #bed ,palophis typhoeus1 ,bracklesham1 #bfa ,palozoic or ,paleozoic1 term defined1 #abc ---- ,plutonic rocks1 #egb ---- rocks1 #deh ---- type of corals1 #dca ,palagonia1 dikes of lava in1 #eca ,paleolithic era1 #adg1 #adi ----1 alluvial deposits of1 #aej ,palm in ,swiss ,miocene1 #bcg ,palma1 volcanic crater of1 #dig ,paludina lenta1 ,hempstead beds1 #ee ---- orbicularis1 ,bembridge1 #bec ,paradoxides ,bohemicus1 #dhh ---- ,davidis1 ,lower ,cambrian1 #dhe ,parallelism of folded strata for long distances1 #ic ,paris basin1 ,tertiary group first studied in1 #ada ----1 ,tertiaries of the1 #bgj ,parka decipiens1 8,old ,red10 #ddh ,parkfield ,colliery1 ground-plan of1 #djj ,patagonia1 strata of1 rich in soda1 #ehg ,patella rugosa1 ,great ,oolite1 #cde ,paterson1 ,dr41 on angiosperm of the ,coal1 #dbi ,peach1 ,mr4 ,c1 cited1 #fja ----1 ,pteraspis1 found by1 #ddc ,pearlstone1 #eje ,pebbles in mineral veins1 #fjh ---- in chalk1 #bib ,pecopteris elliptica1 ,coal1 #dba ,pecten ,beaveri1 ,white ,chalk1 #bid ---- cinctus1 ,neocomian1 #cab ---- islandicus1 ,scotch ,drift1 #agf ---- jacobus1 in tertiary of ,sicily1 #bjf ---- quinque-costatus1 #cjj ---- ,valoniensis1 ,rhtic beds1 #cff ,pegmatite1 #eec ,penarth beds1 #cff ,pengelly1 ,mr41 on ,bovey ,tracey lignite1 #bdf ----1 on flint-knives of ,brixham ,cave1 #aeg ,pentacrinus ,briareus1 ,lias1 #ceg ,pentamerus ,knightii1 ,aymestry1 #dfa ---- oblongus1 and ,p4 lirata1 #dfi ,pentland ,hills1 volcanic rocks of the1 #edh ,perigord cave1 carving of mammoth in1 #aej ,permanence of continents and oceans1 #aag ,permian ,flora1 #cib ---- of ,germany1 #cic ---- strata1 thickness of1 in north of ,england1 #chf ----1 ,upper and ,middle1 #chf1 #chg ----1 ,lower1 #cij ,perna ,mulleti1 ,neocomian1 #caj ,petherwyn1 ,devonian fossils of1 #dej ,petrifaction1 process of1 #fg ,petrophiloides ,richardsoni1 ,sheppey1 #be ,pahcops caudatus1 ,silurian1 #dfg ---- latifrons1 ,devonian1 #dej ,phascolotherium ,bucklandi1 #cdh ,phasianella ,heddingtonensis1 and cast1 #ff ,phillippi1 on tertiary shells of ,sicily1 #bje ,phillips1 ,professor1 on fossils distorted by cleavage1 #eib ----1 on ninety fathom dike1 #ij ----1 on ,wenlock limestone and shale1 #dfe1 #dfg ----1 on ,yoredale series1 #cie ,phillips1 ,mr4 ,j4 ,arthur1 on origin of gold of ,california1 #fag ,phlebopteris contigua1 ,inferior ,oolite1 #cej ,phlogopite1 #dii1 #eja ,pholadomya fidicula1 ,inferior ,oolite1 #cej ,phonolite1 #ejf ,phorus extensus1 ,london ,clay1 #bff ,phragmoceras ventricosum1 ,silurian1 #dfc ,physa ,bristovii1 ,middle ,purbeck1 #cbe ---- columnaris1 #ee ---- hypnorum1 #ee ,piedmont1 absence of lakes in1 #ahf ,pile dwellings of ,switzerland1 #adh ,pilton1 group of1 ,devon1 #ddi ,pinnularia in ,atlantic mud1 #bhh ,pinus sylvestris in peat1 #adg ,pisolitic limestone of ,france1 #bhe ,pitchstone1 #eje ,placodus gigas1 ,muschelkalk1 #chj ,placoids1 rare in ,old ,red ,sandstone1 #ddc ,plagiaulax ,becklesii1 jaw and molar of1 #cbg ,plagioclastic feldspars1 #eja ,plagiostoma giganteum1 ,lias1 #ced ---- ,hoperi1 ,chalk1 #cjj ,planorbis discus1 ,bembridge1 #bec ---- euomphalus1 #ee1 #bee ,plants of ,bovey ,tracey1 ,miocene1 #bdg ----1 fossil fresh-water1 #eg ---- of the ,coal1 #dbj ---- of the ,lias1 #cfd ---- of the ,swiss ,upper ,miocene1 #bai ,plas ,newydd1 rock altered by dike near1 #eae ,plastic ,clay1 ,eocene1 #bfg ,platanus aceroides1 ,miocene1 #bba ,platystoma ,suessii1 ,hallstadt1 #cgg ,playfair1 on amount of subarial denudation1 #aad ---- on faults1 #hg ,plectrodus mirabilis1 ,ludlow1 #dfj ,plesiosaurus dolichodeirus1 ,lias1 #cfa ,pleurotoma attenuata1 ,bracklesham1 #bfb ---- exorta1 ,eocene1 #eg ,pleurotomaria anglica1 and cast1 #ff ---- carinata 7flammigera71 #dcd ---- granulata1 ,inferior ,oolite1 #cea ---- ornata1 ,inferior ,oolite1 #cea ,plieninger1 ,professor1 on ,triassic mammifer1 #cfh ,pliocene glacial formations1 #ahi-ib ---- ,period1 #ahi ---- plutonic rocks1 #efe ---- strata of ,sicily1 #bjd ----1 term defined1 #adc ---- volcanic rocks1 #ebi ,plombires1 alkaline waters of1 #ehe ,plumbago of ,massachusetts1 #ehc ,plutonic and sedimentary formations1 diagram of1 #efg ----1 origin of the term1 #eea ---- rocks1 ,mesozoic1 #egj ----1 ,recent and ,pliocene1 #efe ----1 ,miocene and ,eocene1 #efh ----1 uncertain tests of age of1 #efd ---- defined1 #ca ,podocarya ,bucklandi1 ,oolite1 #cdh ,polypterus of the ,nile1 #ddd ,polyzoa and ,bryozoa1 terms explained1 #aig ,pomel1 ,m41 on fossil mammalia of the ,limagne1 #bce ,ponza ,islands1 globiform pitchstone of1 #eab ,porites pyriformis1 ,devonian1 #dea ,porphyritic granite1 #eef ,porphyry1 #ejf ,portland1 ,cycads in dirt-bed of1 #cca ---- oolite and sand1 #ccd 8,portland screw10 a cast of a shell1 #cce ,porto ,santo1 marine shells in volcanic tuff of1 #ecf ,post-pliocene period1 climate of the1 #afa ---- mammalia1 teeth of1 #afc ----1 term defined1 #ade ---- lakes of ,switzerland1 #ahe ---- volcanic rocks1 #ebd ,potamides cinctus1 #ef ,pothocites ,grantonii1 coal-measures1 #dbi ,potsdam ,sandstone1 #dhj1 #dhi ,pot-stones in the ,chalk1 #bij ,pottsville1 coal seams of1 #djj ,powrie1 ,mr41 on ,cephalaspis beds1 #ddf ----1 on ,parka decipiens1 #ddh ,pratt1 ,mr41 on ,eocene ,isle of ,wight mammalia1 #bed ,predazzo1 altered rocks at1 #ega ,pressure1 solidifying rocks1 #fe ,prestwich1 ,mr41 on age of ,sables inferieurs1 #bgf ----1 on ,chillesford beds1 #aib ----1 on ,coalbrook ,dale insects1 #dje ----1 on ,eocene strata1 #bfg1 #bfi ----1 on faults in coal-measure of ,coalbrook ,dale1 #hh ----1 on shells of ,london clay1 #bfd ----1 on thickness of ,coralline ,crag1 #aih ,prvost1 ,m4 ,constant1 on ,paris basin1 #bgj ,primary ,limestone1 #egi ---- rocks1 #deh ----1 term defined1 #abc 8,primordial ,zone0 of ,bohemia1 #dha1 #dhb ,productus horridus1 ,permian1 #chh ---- semireticulatus 7antiquatus71 #dcd ,progressive development indicated by low grade of early mammals1 #chd ,proteace of ,aix-la-,chapelle flora1 #cjd ---- of ,lower ,molasse1 ,switzerland1 #bcg ---- of ningen beds1 #bba ,protogine1 #egh ,protosaurus of ,thuringia1 #cij1 #dfd ,protrusion of solid granite1 #egd ,provinces of animals and plants1 #abf ,psammodus porosus1 #dcg ,pseudocrinites bifasciatus1 ,silurian1 #dff ,psilophyton princeps1 ,devonian1 #dee ,pteraspis in ,lower ,ludlow shale1 #dfc ,pterichthys1 ,old ,red ,sandstone1 #dde ,pterodactyl of ,kentish chalk1 #big ,pterodactylus anglicus1 ,old ,red1 #ddg ---- crassirostris1 ,solenhofen1 #ccg ,ptychodus decurrens1 ,white ,chalk1 #big ,pudding-stone or conglomerate1 #cf ----1 formation of1 #fb ,pumice1 #ejh ,punfield beds1 brackish and marine1 #cah ,pupa muscorum1 #aee ---- tridens1 ,loess1 #ef ---- vetusta1 ,coal1 #dae ,purbeck beds1 ,upper1 ,middle1 and ,lower1 #cbc1 #cbd1 #ccf ----1 fossil mammalia of the ,middle1 #cbe ---- marble1 #cbd ----1 subdivisions of the1 #ccc ,purity of coal1 cause of1 #djb ,purpura tetragona1 ,red ,crag1 #aif ,purpuroidea nodulata1 ,great ,oolite1 #cde ,puy de ,cme1 cone and lava-current of1 #ebh ---- de ,tartaret1 lava-current and cone of1 #ebg1 #edb ---- de ,pariou1 crater of the1 #ebi ,puzzuoli1 elevation of land at1 #ebe ,pygopterus mandibularis1 ,permian1 #cij ,pyrenees1 chalk altered by granite in the1 #egj ----1 curved strata in1 #hf ----1 lamination of clay-slate in1 #eif ,pyroxene group of minerals1 #dii1 #ejb ,pyrula reticulata1 ,crag1 #bjj ,,quader-,,sandstein1 ,cretaceous age of the1 #bic ,quadrumana of ,gers1 #bae ,quadrupeds1 extinct1 in ,paleolithic gravels1 #aeb ,quartz1 specific gravity of1 #dii1 #ejj1 #eee ,quartzite or ,quartz ,rock1 #egi ,queenaig1 unconformable ,palozoic strata at1 #aab ,quenstedt on zones of ,lias1 #cec ,,radaboj ,miocene1 brown coal of1 #bdb ,radiolites foliaceus1 ,white ,chalk1 #cjf ---- ,mortoni1 ,white ,chalk1 #bie ---- radiosa1 ,white ,chalk1 #cjf ,radnorshire1 stratified trap in1 #edi ,rain-prints with worm tracks in ,coal1 #daf ----1 carboniferous1 #daf ,ramsay1 ,professor1 on break between ,upper and ,lower ,cretaceous1 #cja ----1 on breccias in ,permian1 #cia ----1 on escarpments1 #ajd ----1 on denudation1 #ih ----1 on ice-erosion of lake-basins1 #ahd ----1 on ,lingula ,flags1 #dhd ----1 on position of ,tremadoc beds1 #dhc ----1 on ,silurian metamorphic rocks1 #fjb ----1 on submergence in glacial period1 #aha ----1 on thickness of the ,lower ,trias1 #cgb ----1 on thickness of ,llandeilo beds1 #dge ----1 on thickness of the ,bala beds1 #dgc ----1 on volcanic tuffs of ,snowdon1 #edi ----1 on zones of the ,lias1 #cec ,rastrites peregrinus1 ,llandeilo ,flags1 #dgc ,rath1 ,von1 on ,tridymite1 #ejj ,recent ,period defined1 #ade ---- volcanic rocks1 #ebd ,record1 imperfection of1 in the earth's crust1 #ach ,red ,crag1 older ,pliocene1 #aid ---- ,sandstone1 ,origin of1 #cgd ---- ,sea and ,mediterranean1 distinct species in1 #abg ,redruth1 ,cornwall1 section of veins in mine1 #fjg ,reindeer ,period in ,south of ,france1 #adi ,relistran mine1 pebbles in tin of1 #fji ,reptiles of the ,coal1 #djf1 #dac ,reptiles of the ,lias1 #cfj ,retepora flustracea1 ,permian1 #chh ,rhtic beds between ,lias and ,trias1 #cff ,rhine1 fresh-water strata of the1 #ec ----1 loess of the1 #aed ,rhinoceros in drift of ,abbeville1 #aec ---- leptorhinus 7megarhinus71 molar of1 #afd ---- tichorhinus1 molar of1 #afd ,rhode ,island1 metamorphic rocks of1 #ehc ,rhynchonella navicula1 ,ludlow1 #dfj ---- octoplicata1 ,white ,chalk1 #bid ---- spinosa1 ,inferior ,oolite1 #cej ---- ,wilsoni1 ,aymestry1 #dfb ,richmond1 ,virginia1 ,triassic coal-field of1 #chb ,rigi and ,speer1 ,lower ,miocene of the1 #bce ,rimula clathrata1 ,great ,oolite1 #cde ,rink1 ,mr41 on ,greenland land-ice1 #aga ,ripple-marked sandstone1 how formed1 #df ,rise and fall of land1 #adf ,rissoa ,chastelii1 ,hempstead beds1 #bde ,rivers1 denuding powers of1 #aja1 #aad ,roches moutonnees described1 #afi ,rock1 term defined1 #bf ,rocks altered by volcanic dikes1 #ead ---- altered by subterranean gases1 #ehf ----1 analysis of minerals in1 #dii ----1 aqueous or stratified1 #bg ----1 classification of1 #aba ----1 great thickness of palozoic1 #aaj ----1 glacial scorings on1 #afi ----1 metamorphic1 age of1 #eig ----1 plutonic age of1 #efd ----1 volcanic1 age of1 #ebj ----1 trappean1 #dig ----1 metamorphic1 defined1 #cb ----1 four classes of contemporaneous1 #cc ----1 plutonic1 defined1 #ca ----1 tests of age of1 #abc1 #abe1 #ebj1 #efd1 #eig ----1 four contemporaneous classes of1 #abb ----1 underlying1 not always the oldest1 #abb ----1 volcanic1 defined1 #bi ,rock-salt of ,trias1 #cga ----1 origin of1 #cgd ,rogers1 ,mr4 ,h4 ,d41 on blending of coal-seams1 #djj ----1 on ,virginian fault1 #ib ,rose1 ,gustavus1 on isomorphism1 #ejb ----1 on ,fifeshire dike1 #edf ----1 on quartz in granite1 #eee ,rosso antico1 red porphyry of ,egypt1 #ejf ,rostellaria 7,hippocrenes7 ampla1 ,london ,clay1 #bff ,roth1 ,m41 on ,miocene of ,greece1 #bbf ,runn of ,cutch1 salt of1 #cge ,rupelian beds of ,dumont1 #bda1 #bdb ,russia1 glaciation of1 #agd ----1 ,devonian of1 #ded ----1 ,silurian strata of1 #dgh ,,saarbruck1 reptiles in coal-field of1 #djf ,sabal major1 ,lower ,miocene1 #bcg ,sables de ,bracheux1 #bgf ---- moyens1 ,paris basin1 #bgc ,sahlite1 #ejb ,st4 ,abb's ,head1 curved strata of1 #gf ----1 unconformable stratification at1 #id ,st4 ,andrews1 carboniferous trap-rocks of1 #ede ,st4 ,cassian1 fossil mollusca of1 #cgg ---- and ,hallstadt beds1 #cgf ,st4 ,david's1 ,menevian beds of1 #dhe ,st4 ,mary's1 shells of1 #eci ,salt1 rock1 origin of1 #cgb ,salter1 ,mr41 on fossils of ,arenig group1 #dgf ----1 on ,menevian beds1 #dhe ----1 on ,tremadoc fossils1 #dhc ,sandberger1 ,dr4 ,f41 on ,mayence basin1 #bdb ,sandstone1 ,new ,red1 #cfi ----1 ,old ,red1 #dci ---- slab with cracks1 #cag ----1 slab of ripple-marked1 #de ---- slab with footprints1 #djh ,sao hirsuta1 #dhh ,saurians of the ,lias1 #cfa ----1 sudden destruction of1 #cfb ,saurichthys apicalis1 ,rhtic ,beds1 #cfg ,saussure1 on vertical conglomerates1 #gc ,saxicava rugosa1 ,scotch drift1 #agf ,saxony1 beds of minerals in1 #fji ,scandinavia1 glaciation of1 #agd ,scaphites qualis1 ,chloritic marl1 #bii ,scapolite1 #ejf ,scheerer on action of water in metamorphism1 #ehe ,schist1 mica1 #egh ----1 argillaceous1 #egi ----1 hornblende1 #egh ,schizodus ,schlotheimi1 ,permian1 #chg ---- truncatus1 ,permian1 #chg ,schmerling1 ,dr41 on ,lige caverns1 #aeg ,schorl-rock1 and schorly granite1 #eeg ,schwab1 ,m41 on ,celtic coins in lake-dwellings1 #adi ,scoliostoma1 ,st4 ,cassian1 #cgg ,scoresby1 on ,arctic icebergs1 #agb ,scoriaceous lava1 #ejg ,scori1 #ejh ,scotland1 8,fundamental gneiss0 of1 #dic ----1 ,old ,red ,sandstone of1 #ddj ----1 glaciation of1 #age ,screws1 fossil1 internal casts of shells1 #ff ,scrope1 ,mr41 on ,isle of ,ponza1 globiform pitchstone1 #eab ----1 on minerals in lava1 #ebd ----1 on water in lava1 #eee ,scudder1 ,mr41 on ,devonian insects of ,canada1 #deg ,sea1 apparent fall of1 caused by rise of land1 #gj ----1 denuding power of the1 #aje ----1 deep soundings in1 #bhg ----1 mean depth of the1 #aah ---- cliffs1 inland1 #ajc ,secondary and ,tertiary1 gap between the1 #bha ----1 term defined1 #abc ,section of ,auvergne alluvium1 #ajj ---- of carboniferous rocks1 ,lancashire1 #he ---- of chalk and greensand1 #bhg ---- of crags near ,woodbridge1 ,suffolk1 #aih ---- of cross-stratification1 #db-dd ---- of curved strata of the ,jura1 #hb ---- of dirt-bed in ,isle of ,portland1 #ccb ---- of ,forfarshire1 showing curved strata1 #gd ---- of fossil tree1 showing texture1 #fg ---- of folded and denuded carboniferous beds1 ,nova ,scotia1 #dah ---- of the ,oolitic strata1 #cbb ---- of ,recent and ,post-pliocene alluvial deposits1 #aea ---- showing creeps in coal-mines1 #gi ---- of slaty cleavage1 #ehi ---- showing valleys of denudation1 #ih ---- showing the ,weald formation1 #cac ---- of strata thinning out1 #da ---- of superimposed groups at ,dundry ,hill1 #acj ---- of unconformable strata near ,mons1 #ie ,sections illustrating faults1 #hh1 #ij1 #ia ,sedgwick1 ,professor1 on the ,cambrian ,group1 #dha1 #dhb1 #dhf ----1 on classification of ,arenig group1 #dgf ----1 on ,devonian series1 #dci1 #ddi ----1 on position of the ,may-,hill beds1 #efh ----1 on protrusion of solid granite1 #egd ----1 on slaty cleavage1 #ehh1 #eia ----1 on garnet in altered rock1 #eae ----1 on concretionary structure1 #fc ,sediment1 accumulation of1 causing a shifting of the subterranean1 #aag isothermals4 ,sedimentary beds of the ,carboniferous1 #cif ,selsea ,bill1 erratics at1 #ahb ,senarmont on action of water in metamorphism1 #ehe ,sequoia ,langsdorfii1 #bch 8,seraphim10 head of ,pterygotus anglicus1 #ddf ,serapis1 marine littoral deposits of1 #adf ,serpentine1 #egh ,serpul attached to ,grypha1 #dh ---- attached to ,spatangus1 #di ---- attached to ,apiocrinus1 #cdc ,shale defined1 #cf ---- of the ,lower ,ludlow1 #dfa ,sharpe1 ,mr4 ,d41 on ,american ,silurian fossils1 #dgi ----1 on fossils distorted by cleavage1 #eib ,shell-mounds of ,denmark1 #adf ,shells1 ,arctic1 in ,scotch drift1 #agg ----1 derivative1 in the ,crag1 #aie-bjc ----1 marine1 found at great heights above the sea1 #bi ----1 proportion of living1 in the ,crags1 #aid1 #aie1 #aii ----1 value of1 in classification1 #adb ----1 fossil1 of ,virginia1 #bbh ---- of the ,london clay1 #bff ---- of the mountain limestone1 #dcc ---- of the ,barton clay1 #beh ---- of the ,oolite1 #cce1 #cde1 #cej ----1 marine1 of ,moel ,tryfaen1 #ahj ,sheppey1 fauna and flora of1 #bfd ----1 ,eocene fish of1 #bfg ,sherringham1 erratic block at1 #aia ,shetland1 granite of1 #eeh ----1 hornblende-schist of1 #ehc ,sicily1 fauna and flora of1 older than the country itself1 #bjg ----1 newer ,pliocene strata of1 #bjd ----1 subterranean igneous action in1 #efi ----1 undulating gypseous marls of1 #hf ----1 volcanic dikes of1 #eca ,sidlaw ,hills1 trap of1 #edh ,sigillaria in coal-measures1 #chj1 #daa1 #dbe ,sigillaria lvigata1 coal-measures1 #dbf ,siliceous limestone defined1 #cg ,silurian1 derivation of the name1 #deh ----1 granite of ,norway1 #egc ----1 metamorphic1 of ,north ,highlands1 #fja ---- rocks1 classification of1 #deh ---- strata of the continent of ,europe1 #dgg ---- strata of ,united ,states1 #dgh ---- volcanic rocks1 #edh ,siphonotreta unguiculata1 obolus grits1 #dgh ,siwlik ,hills1 fresh-water deposits of1 #bbf ,skaptar ,jokul1 flow of lava from1 #ebc ,skye1 hypersthene rocks of1 #dia ----1 ,isle of1 ,miocene syenite of the1 #efh ----1 trap dike in1 #ead ,slaty cleavage1 #ehh ,slicken-sides1 in opposite walls of veins1 #fjh ----1 term defined1 #hg ,smilax sagittifera1 ningen1 #bbb ,smith1 ,mr4 ,w41 on ,white ,lias bed1 #cff ,snowdon1 volcanic tuffs of1 #edi ,soissonnais sands1 #bge ,solenastra cellulosa1 ,brockenhurst1 #beg ,solenhofen stone1 fossils in the1 #ccg ,solfatara1 decomposition of rocks in the1 #ehf ,somma1 cone and dikes of1 #ebf ,sopwith1 ,mr4 ,t41 models of outcrop of strata1 #he ,sorby1 ,mr41 on action of water in metamorphism1 #ehe ----1 on glass cavities in quartz1 #eee ----1 on mechanical theory of cleavage1 #eib ----1 on ripple-marks in mica schist1 #eif ,south ,joggins1 section of cliffs at1 #daj ,spalacotherium1 ,purbeck1 #cdf ,spatangus radiatus1 ,chalk1 #bhd ---- with serpula attached1 #di ,species1 gradual change of1 #aci ---- older than the land they inhabit1 #bjg ----1 similarity of conditions causing reappearance of1 #caa ,specific gravity of basalt and trachyte1 #ejd ,speer and ,rigi1 ,lower ,miocene of the1 #bce ,speeton ,clay1 #caa ,sphrexochus mirus1 ,silurian1 #dfg ,sphrulites agariciformis1 ,white ,chalk1 #cjf ---- of volcanic minerals1 #dii ,sphenophyllum erosum1 ,coal1 #dbe ,sphenopteris gracilis1 ,hastings sands1 #cah ,spheroidal concretions in limestone1 #fd ,spicula of sponge1 ,atlantic mud1 #bhh ,spirifera disjuncta1 ,devonian1 #dej ---- alata1 ,permian1 #chh ---- mucronata1 #ded ---- trigonalis1 and ,s4 glabra1 #dcd ,spiriferina ,walcotti1 ,lias1 #cee ,spirolina stenostoma1 ,eocene1 #bge ,spirorbis carbonarius1 coal-measures1 #dje ,spondylus spinosus1 ,white ,chalk1 #bid ,sponge in flint from ,white ,chalk1 #bif ,sponges1 vitreous1 in the chalk1 #bia ,springs1 mineral of ,auvergne1 #fjd ,staffa1 age of columnar basalt of1 #eci ,stalactite1 origin of1 explained1 #aef ,starfish in ,silurian strata1 #dgb ,stations of species affecting distribution of fossils1 #ced ,stauria astriformis1 #dca ,stereognathus of ,stonesfield1 #cdh ,sternberg1 ,count1 on insects in coal1 #die ,stigmaria attached to trunk of ,sigillaria1 #dbg ---- in coal-measures1 #cih1 #daa1 #dbf ---- ficoides and surface showing tubercles1 ,coal1 #dbg ,stilbite1 #ejj ,stiper-,stones or ,arenig ,group1 #dge ,stockwerk1 assemblage of veins1 #fje ,stonesfield slate1 mammalia of the1 #cde ,strata1 term defined1 alternations of fresh-water1 and shallow and deep1 #bg sea4 ----1 alternations of marine and fresh-water1 #ajh ----1 curved1 inclined1 and vertical1 #gc ----1 apparent horizontality of inclined1 #ha ----1 contorted in drift1 #agh ----1 contortion of1 in ,cyclopean ,isles1 #ecj ----1 general table of fossiliferous1 #aca ----1 horizontality of1 #dj ----1 origin of metamorphic1 #hc ----1 overlapping1 #ie ---- repeated by being doubled back1 #hg ----1 slow growth of1 attested by fossils1 #dg-ej ---- of organic origin1 #ea ----1 tests of age of1 #abc ----1 unconformability of1 #id1 #ach ----1 vast thickness of1 not forming high mountains1 #aji-ac ,stratification1 diagonal or cross1 #db1 #dd ----1 different forms described1 #ci ---- of metamorphic rocks considered1 #ehj ,stratified rocks1 composition of1 #ce ,stri1 production of1 #afh ,strickland1 ,mr41 on thickness of the ,trias1 #cfi ,stricklandinia lirata1 #dfi ,strike1 term explained1 #hj ,stringocephalus ,burtini1 #deb ,stromboli1 lava of1 #eff ,strophomena depressa1 ,wenlock1 #dff ---- grandis1 #dga ,studer1 ,mr41 on gneiss of the ,jungfrau1 #eii subarial denudation1 average annual amount of1 #aac ,subapennine beds1 proportion of recent species in1 #adc ---- strata1 older ,pliocene1 #bjh ,submarine denudation1 #aje ,subsidence of land must preponderate over upheaval1 #aaf ,succinea amphibia1 #ee ---- elongata1 #aee ,suess1 ,m41 on fossils of ,st4 ,cassian beds1 #cgf1 #cgg ----1 on ,vienna basin1 #bbe ,suffolk1 ,crag of1 #aie 8,sunk country10 ,new ,madrid1 #djb ,superga1 ,lower ,miocene of the1 #bdd ,superior1 ,lake1 marl in1 #fc ,superposition of deposits1 a test of age1 #abd ---- a test of age of volcanic rocks1 #eba ,sutherlandshire1 unconformable ,palozoic strata in1 #aab ,swanage1 fossil mammalia found at1 #cbf ,sweden1 ,cambrian of1 #dhi ----1 slow rise of land in1 #gb ----1 small thickness of ,silurian strata in1 #dgg ,switzerland1 lake-dwellings of1 #adh ----1 ,lower ,molasse of1 #bce ----1 ,middle or ,marine ,molasse of1 #bbc ----1 ,upper ,miocene of1 at ningen1 #bae ,sydney coal-field1 rain-prints in1 #daf ,syenite1 composition of1 #eeb1 #eeg ----1 how far connected with trap-rocks1 #eeh ,syenitic granite1 #eeg ,symonds1 ,rev4 ,w4 ,s41 on ,moel ,tryfaen shells1 #ahj ,synclinal and anticlinal curves1 #gd1 #he ,,table of ,botanical ,nomenclature1 #cjc ---- of ,st4 ,cassian fossil mollusca1 #cgg ---- of ,cretaceous formations1 #bhc ---- of ,devonian series in ,devon1 #ddi ---- of divisions of ,hastings ,sand1 #caf ---- of ,english and ,french ,eocene strata1 #beb ---- of ages of fossil vertebrata1 #dfd ---- of ,neocomian strata1 #cjh ---- of mammalia older than ,paris gypsum1 #cbi ---- of marine testacea in the ,crag1 #bjb ---- of ,oolitic strata1 #cba ---- of volcanic minerals1 #dii ---- of ,silurian strata of ,united ,states1 #dgh ---- of ,silurian rocks1 #deh ---- of ,triassic strata1 #cge ---- of ,cambrian strata1 #dhb ---- of ,permian of north of ,england1 #chf ---- of ,welsh coal-measures1 #cid ---- of thicknesses of ,carboniferous limestone1 #cie ----1 general1 of fossiliferous strata1 #aca ,table ,mountain1 granite veins in clay-slate of1 #efj ,tails of homocercal and heterocercal fish1 #chi ,talcose granite1 #eeg ---- gneiss1 #egh ,tarannon shales1 #dfh ,tartaret cone1 and lava of1 #ebg1 #edb ,tate1 ,mr41 on ,st ,cassian fossils1 #cgg ,tealby series1 ,middle ,neocomian1 #cab ,teeth of extinct mammalia1 #afc1 #afd ,tellina balthica 7,t4 solidula71 #aij ---- calcarea 7,t4 proxima71 #agg ---- obliqua1 ,crag1 #aid ,temnechinus excavatus1 #bjj ,temnopleurus excavatus1 #bjj ,tentaculites annulatus1 ,silurian1 #dhi ,terebellum fusiforme1 ,barton1 #bei ---- sopita1 ,barton1 #bei ,terebratula affinis1 ,aymestry1 #dfb ---- biplicata1 ,white ,chalk1 #bid ---- carnea1 ,white ,chalk1 #bid ---- digona1 ,bradford clay1 #cde ---- fimbria1 ,inferior ,oolite1 #cej ---- hastata1 ,mountain ,limestone1 #dcd ---- sella1 ,neocomian1 #caj ---- ,wilsoni1 ,aymestry1 #dfb ,terebratulina striata1 ,white ,chalk1 #bid ,terebrirostra lyra1 ,chloritic ,sand1 #cjj ,teredo navalis1 boring wood1 #ej ,tertiary formations1 classification of1 #acg1 #adc ---- strata1 subdivisions of1 #adc ----1 term defined1 #abc ,testacea4 ,see ,shells4 ,thallogens1 #cjc ,thamnastra1 ,coral ,rag1 #cci ,thanet sands1 #bfi ,theca operculata1 ,tremadoc beds1 #dhc ,thecodontosaurus1 tooth of1 #cgd ,thecodus parvidens1 ,ludlow1 #dfj ,thecosmilia annularis1 ,coral ,rag1 #cci ,thirria1 ,m41 on ,nerinan limestone1 #cdj ,thompson1 ,dr41 on ,nummulites of ,thibet1 #bgg ,thomson1 ,wyville1 on ,atlantic mud1 #bhh ----1 on sponges in chalk mud1 #bib ,thuringia1 monitor of1 #cij1 #dfc ,thurmann1 ,m41 on ,bernese ,jura ,oolite1 #cdd ----1 on structure of the ,jura1 #hc ,thylacotherium ,prevostii1 ,stonesfield1 #cdg ,tile-stones of the ,upper ,ludlow1 #dei ,tilgate forest1 fossil ,iguanodon in1 #cae ,till described1 #aff ----1 mammoth in ,scotch1 #age ---- of ,north ,america1 #ahb ,tin veins1 age of1 in ,cornwall1 #fae ,titanoferrite1 #ejj ,torell1 ,dr41 on ice-action in ,greenland1 #agb ----1 on ,swedish ,cambrian fossils1 #dhi ,touraine1 faluns of1 #baa ,tourmaline1 #ejj ,trachytic rocks1 #eje ---- tuff1 #ejf ---- porphyry1 #ejf ---- lava1 age of1 #ebc ,trap1 term defined1 #dih ---- dike1 intercepting strata1 #eah ---- dikes1 #eac-ag ----1 intrusion of1 between strata1 #eag ---- rocks1 ages of1 #ebd-ej ---- rocks passing into granite1 #eei ---- tuff described1 #ejh ,trappean rocks1 nomenclature of1 #dig ---- rocks1 their relation to active volcanoes1 #eag ,trass of ,lower ,eifel1 #ece ,travertin1 how deposited1 #fj ----1 infrieur of ,paris basin1 #bgc ,tree ferns1 living1 #dbb ,trees erect in coal1 ,nova ,scotia1 #daa ,tremadoc slates and their fossils1 #dhb ,tremolite1 #dii1 #ejb ,trenton limestone1 fossils of the1 #dgi ,trezza1 volcanic rocks of1 #ebi ,trias1 beds of passage between ,lias and1 #cff ---- of ,england1 #cfi-gd ---- of ,germany1 #cge ----1 ,saurians of the1 #cgj ---- of the ,united ,states1 #cha ,triassic mammifer1 ,north ,carolina1 #chc ,triclinic feldspars1 #eja ,tridymite1 crystallised silica1 #ejj ,trigonellites latus1 ,kimmeridge clay1 #ccf ,trigonia caudata1 ,neocomian1 #caj ---- gibbosa1 ,portland stone1 #cce ,trigonocarpum ovatum1 and ,t4 olivforme1 ,coal1 #dbi ,trigonotreta undulata1 ,permian1 #chh ,trilobites of ,bala and ,caradoc beds1 #dga ----1 metamorphosis of1 #dga1 #dhh ---- of primordial zone1 #dhg ,triloculina inflata1 ,eocene1 #bge ,trimmer1 ,mr41 on contorted strata1 #agi ----1 on shells of ,moel ,tryfaen1 #ahf ,trinucleus concentricus1 ,t4 ,caractaci1 #dgb ,trionyx1 carapace of1 ,bembridge1 #bec ,tripoli composed of diatomace1 #ea ,trochoceras giganteus1 ,ludlow1 #dfc ,trophon antiquum 7,fusus contrarius71 #aif ---- clathratum1 ,scotch drift1 #agf ,tuff defined1 #cj ----1 shelly1 of the ,grand ,canary1 #ech ----1 trappean1 of ,llandeilo rocks1 #dgc ----1 shelly1 of ,gergovia1 #edb ,tupaia ,tana1 recent1 #cdg ,turner1 ,dr41 on chemical decomposition1 #fh ,turrilites costatus1 ,chalk1 #bii ,turritella multisulcata1 ,bracklesham1 #bfb ,tuscany1 mineral springs of1 #fjd ,tylor1 ,mr41 on amount of subarial denudation1 #aad ,tyndall1 ,dr41 on slaty cleavage1 #eid ,tynedale fault1 #ij ,tynemouth cliff1 brecciated limestone of1 #chg ,typhis pungens1 ,barton clay1 #bei ,,uncites ,gryphus1 ,devonian1 #deb ,unconformability of strata1 #id1 #ach ,underlying1 term applied to plutonic rocks1 #cd ,unger on ,american forms in ,swiss ,miocene flora1 #bbc1 #bci ---- on ,miocene plants of ,croatia1 #bdc ,ungulite1 or ,obolus grit of ,russia1 #dgg ,unio littoralis1 #ed ---- ,valdensis1 ,hastings ,sands1 #cag ,united ,states1 ,cambrian of the1 #dhi ----1 ,cretaceous rocks of1 #cjg ----1 ,devonian of1 #dee ----1 ,eocene strata in the1 #bgh ----1 footprints in ,carboniferous of1 #djg ----1 ,lower ,miocene of1 #bdh ----1 older ,pliocene and ,miocene formations of1 #bbg ----1 ,silurian strata of1 #dgh ----1 ,trias of the1 #cha ,upheaval of land more than counteracted by subsidence1 #aaf ----1 power of denudation to counteract1 #aje1 #aae ,upper ,greensand1 or ,chloritic series1 #bih ,upsala1 erratics on modern marine drift near1 #agd ,ural ,mountains1 auriferous alluvium of1 #faf ,uralite1 #dii ,ursus spelus1 tooth of1 #afe ,urville1 ,captain de1 on size of icebergs1 #agb ,,val ,d,,rsquo2,,arno1 ,newer ,pliocene of1 #bjg ,valleys1 origin of1 #ajb ,valorsine1 granite veins in talcose gneiss in1 #eii ,valvata piscinalis1 #ee ,vanessa ,pluto1 ,lower ,miocene1 ,croatia1 #bdc ,vegetation of the ,coal1 #dbj ---- of the ,devonian of ,america1 #dee ----4 ,see ,plants4 ,veins1 chemical deposits in1 #fab ----1 granite rocks altered by1 #eei ----1 different kinds of minerals1 #fje ----4 ,see ,mineral veins4 ,vein-stones1 #faj ,venericardia planicosta1 #bfj ,venetz1 ,m41 on ,alpine glaciers1 #agj ,ventriculites radiatus1 ,chalk1 #bib ,verneuil1 ,m4 de1 on ,russian ,silurian1 #dfb ----1 on ,permian flora1 #cib ,vertebrata1 progress of discovery of fossil1 #dfd ,vertical strata1 #gc ,vesuvius1 ,recent and ,post-pliocene volcanic rocks of1 #ebe ----1 basaltic lavas of1 #ejh ----1 tufaceous strata of1 #ebb ----1 dikes of1 #ebg ,vicarya ,lujani1 ,punfield1 #cai ,vicentin1 columnar basalt of the1 #eaa ,vienna ,basin1 ,upper ,miocene beds of1 #bbd ,vine in ,upper ,miocene beds at ningen1 #bba ,virginia1 eighty miles of fault in1 #ib ----1 coal-field of1 #chb ,virlet1 ,m1 on corrosion of rocks near ,corinth1 #ehf ----1 on ,cretaceous traps of ,greece1 #edd ----1 on fossils in veins1 #fjh ----1 on volcanic rocks of the ,morea1 #edd ,volcanic ash or tuff1 #ejh ---- breccia1 #eji ---- dikes1 #eac-af ---- force and denudation opposing powers1 #aag ---- mountains1 structure and origin of1 #did ,volcanic rocks defined1 #bi ----1 mineral composition of1 #dih ----1 ,recent and ,post-pliocene1 #ebd ----1 ,pliocene1 #ebi ----1 ,miocene1 #ecf-dc ----1 ,eocene1 #edc ----1 ,cretaceous and ,liassic1 #edd1 #ede ----1 ,new ,red1 ,permian and ,carboniferous1 #ede ----1 ,old ,red ,sandstone1 #edg ----1 ,silurian1 ,cambrian and ,laurentian1 #edh1 #edi ---- of ,auvergne1 #edj ----1 columnar and globular1 structure of1 #eaj ---- of ,grand ,canary1 #ebh ---- of ,silurian age1 #dgg ----1 special forms of structure of1 #ejf ----1 tests of age of1 #ebj-d ,volcanoes1 extinct1 #cj ---- of ,auvergne1 #die ,voltzia heterophylla1 ,bunter1 #chj ,voluta ambigua1 ,barton clay1 #bei ---- athleta1 ,barton1 #bei ---- ,lamberti1 coralline and ,red ,crag1 #aif ---- ,lamberti1 faluns1 #bad ---- nodosa1 ,london clay1 #bff ---- ,selseensis1 ,bracklesham1 #bfb ,von ,buch1 ,leopold1 on 8elevation craters10 #dif ----1 on ,silurian plutonic rocks1 #egb ,,wacke described1 #ejh ,wagner1 ,m41 on ,miocene of ,greece1 #bbf ,walchia piniformis1 ,permian1 #cib ,wales and ,england1 glaciation of1 #ahj ,wallich1 ,dr41 on ,atlantic mud1 #bhg ,water1 denuding power of running1 #ih1 #aae ----1 action of1 in metamorphism1 #ehd ,watt1 ,gregory1 on fusion of rock1 #ehd ,weald clay and its fossils1 #cag ,wealden area1 thickness of the1 #cai ---- formation1 #cac ---- flora1 #cbj ,webster1 ,mr4 ,t41 on ,tertiary strata1 #ada ,wellington ,valley caves1 #aeh ,wenlock formation1 fossils of the1 #dfe-h ---- limestone1 #dfe ---- shale1 #dfg ,werner on mineral veins in ,saxony1 #fji ---- on isomorphism1 #ejb ,westwood1 ,mr41 on ,lias beetles1 #cfc ,wexford1 veins of copper at1 #fae ,whitaker1 ,mr41 on subarial origin of escarpments1 #ajd ,white or coralline crag1 #aig ---- sand of ,alum ,bay1 #ch ,whymper1 ,mr41 on ,arctic ,miocene plants1 #bdj ,williams1 ,mr41 on ,cornish lodes1 #fjg ,williamson1 ,professor1 on ,conifers of the ,coal1 #dbh ----1 on structure of calamite1 #dbe ,wind1 denuding action of the1 #ig ,wood1 ,mr4 ,searles1 on ,bridlington shells1 #aij ----1 on ,chillesford and ,aldeby beds1 #aib ----1 on shells of the ,crags1 #aid1 #aie1 #aii ----1 on shells of ,crag and faluns compared1 #bac ----1 on fish of ,headon series1 #bee ----1 table of marine testacea of the ,crag1 #bjb ----1 on thickness of coralline crag1 #aih ,woodward1 ,dr41 on ,st4 ,cassian fossils1 #cgg ,woodward1 ,mr4 ,h41 on ,pterygotus1 #ddg ,woolhope beds1 #dfg ,woolwich and ,reading series1 #bfg ,wright1 ,dr41 on ,barton shells1 #beh ----1 on zones of the ,lias1 #cec ,wunsch1 ,mr4 ,e4 ,a41 on trees in volcanic ash1 #edf ,wyville ,thomson4 ,see ,thomson4 ,,xiphodon gracile1 ,paris basin1 #bga ,xylobius ,sigillari1 ,nova ,scotia coal1 #dae ,,yoredale beds1 thickness of the1 #cie ,yorkshire1 ,oolite of1 #cdi ,young1 ,mr41 on seeds washed out of mammoth tusks1 #agf ,,zechstein of ,germany1 #cib ,zeolites1 secondary volcanic minerals1 #ejj ,zeuglodon cetoides1 ,eocene1 ,united ,states1 #bhj ,zircon-syenite1 #eeh ,zoantharia rugosa and ,z4 aporosa1 #dca ,zones of the ,lias1 #cec ,zonites priscus1 ,coal1 #dae ,zoological provinces1 great extent of1 #abg ,zoophytes1 fossil1 #dh ----4 ,see ,corals1 ,bryozoa1 etc4 ,zurich1 lake-dwellings in ,lake of1 #adh