,transcriber's ,note ,italic text is denoted by underscores4 ,,the ,,international ,,scientific ,,series ,,volume ,,lxix ,,the ,,international ,,scientific ,,series4 ,each book complete in ,one ,volume1 #abmo1 and bound in ,cloth4 #a4 ,,the ,,forms ,,of ,,water ,,in ,,clouds ,,and ,,rivers1 ,,ice ,,and ,,glaciers4 ,by ,j4 ,tyndall1 ,,ll4 ,d41 ,f4 ,r4 ,s4 ,with #ce ,illustrations4 #a4ej4 #b4 ,,physics ,,and ,,politics2 or1 ,thoughts on the ,application of the ,principles of ,natural ,selection and ,inheritance to ,political ,society4 ,by ,walter ,bagehot4 #a4ej4 #c4 ,,foods4 ,by ,edward ,smith1 ,m4 ,d41 ,,ll4 ,b41 ,f4 ,r4 ,s4 ,with numerous ,illustrations4 #a4ge4 #d4 ,,mind ,,and ,,body3 ,the ,theories of their ,relation4 ,by ,alexander ,bain1 ,,ll4 ,d4 ,with #d ,illustrations4 #a4ej4 #e4 ,,the ,,study ,,of ,,sociology4 ,by ,herbert ,spencer4 #a4ej4 #f4 ,,the ,,new ,,chemistry4 ,by ,professor ,j4 ,p4 ,cooke1 ,harvard ,university4 ,with #ca ,illustrations4 #b4jj4 #g4 ,,the ,,conservation ,,of ,,energy4 ,by ,balfour ,stewart1 ,m4,a41 ,,ll4 ,d41 ,f4 ,r4 ,s4 ,with #ad ,illustrations4 #a4ej4 #h4 ,,animal ,,locomotion2 or1 ,walking1 ,swimming1 and ,flying4 ,by ,j4 ,b4 ,pettigrew1 ,m4 ,d41 ,f4 ,r4 ,s41 etc4 ,with #acj ,illustrations4 #a4ge4 #i4 ,,responsibility ,,in ,,mental ,,disease4 ,by ,henry ,maudsley1 ,m4 ,d41 #a4ej4 #aj4 ,,the ,,science ,,of ,,law4 ,by ,professor ,sheldon ,amos4 #a4ge4 #aa4 ,,animal ,,mechanism3 ,a ,treatise on ,terrestrial and ,arial ,locomotion4 ,by ,professor ,e4 ,j4 ,marey1 ,college of ,france4 ,with #aag ,illustrations4 #a4ge4 #ab4 ,,the ,,history ,,of ,,the ,,conflict ,,between ,,religion ,,and ,,science4 ,by ,j4 ,w4 ,draper1 ,m4 ,d41 ,,ll4 ,d4 #a4ge4 #ac4 ,,the ,,doctrine ,,of ,,descent ,,and ,,darwinism4 ,by ,professor ,oscar ,schmidt1 ,strasburg ,university4 ,with #bf ,illustrations4 #a4ej4 #ad4 ,,the ,,chemistry ,,of ,,light ,,and ,,photography ,,in ,,their ,,application ,,to ,,art1 ,,science1 ,,and ,,industry4 ,by ,dr4 ,hermann ,vogel1 ,royal ,industrial ,academy of ,berlin4 ,with #ajj ,illustrations44 #b4jj4 #ae4 ,,fungi3 ,their ,nature and ,uses4 ,by ,m4 ,c4 ,cooke1 ,m4 ,a41 ,,ll4 ,d4 ,edited by the ,rev4 ,m4 ,j4 ,berkeley1 ,m4 ,a41 ,f4 ,l4 ,s4 ,with #aji ,illustrations4 #a4ej4 #af4 ,,the ,,life ,,and ,,growth ,,of ,,language4 ,by ,professor ,william ,dwight ,whitney1 ,yale ,college4 #a #ej4 #ag4 ,,money ,,and ,,the ,,mechanism ,,of ,,exchange4 ,by ,w4 ,stanley ,jevons1 ,m4 ,a41 ,f4 ,r4 ,s4 #a4ge4 #ah4 ,,the ,,nature ,,of ,,light1 with a ,general ,account of ,physical ,optics4 ,by ,dr4 ,eugene ,lommel4 ,with #ahh ,illustrations and a ,table of ,spectra in ,colors4 #b4jj4 #ai4 ,,animal ,,parasites ,,and ,,messmates4 ,by ,professor ,p4 ,j4 ,van ,beneden1 ,university of ,louvain4 ,with #hc ,illustrations4 #a4ej4 #bj4 ,,fermentation4 ,by ,professor ,p4 ,schtzenberger4 ,with #bh ,illustrations4 #a4ej4 #ba4 ,,the ,,five ,,senses ,,of ,,man4 ,by ,professor ,julius ,bernstein1 ,university of ,halle4 ,with #ia ,illustrations4 #a4ge4 #bb4 ,,the ,,theory ,,of ,,sound ,,in ,,its ,,relation ,,to ,,music4 ,by ,professor ,pietro ,blaserna1 ,royal ,university of ,rome4 ,with numerous ,illustrations4 #a4ej4 #bc4 ,,studies ,,in ,,spectrum ,,analysis4 ,by ,j4 ,norman ,lockyer1 ,f4 ,r4 ,s4 ,with #g ,photographic ,illustrations of ,spectra1 and #eb other ,illustrations4 #b4ej4 #bd4 ,a ,,history ,,of ,,the ,,growth ,,of ,,the ,,steam-,,engine4 ,by ,professor ,r4 ,h4 ,thurston1 ,cornell ,university4 ,with #afc ,illustrations4 #b4ej4 #be4 ,,education ,,as ,a ,,science4 ,by ,alexander ,bain1 ,,ll4 ,d4 #a4ge4 #bf4 ,,students #a ,,text-,,book ,,of ,,color2 or1 ,modern ,chromatics4 ,with ,applications to ,art and ,industry4 ,by ,professor ,ogden ,n4 ,rood1 ,columbia ,college4 ,with #acj ,illustrations4 #b4jj4 #bg4 ,,the ,,human ,,species4 ,by ,professor ,a4 de ,quatrefages1 ,museum of ,natural ,history1 ,paris4 #b4jj4 #bh4 ,,the ,,crayfish3 ,an ,introduction to the ,study of ,zology4 ,by ,t4 ,h4 ,huxley1 ,f4 ,r4 ,s4 ,with #hb ,illustrations4 #a4ge4 #bi4 ,,the ,,atomic ,,theory4 ,by ,professor ,a4 ,wurtz4 ,translated by ,e4 ,cleminshaw1 ,f4 ,c4 ,s4 ,with ,illustrative ,chart1 #a4ej4 #cj4 ,,animal ,,life ,,as ,,affected ,,by ,,the ,,natural ,,conditions ,,of ,,existence4 ,by ,professor ,karl ,semper1 ,university of ,wrzburg4 ,with #ajf ,illustrations and #b ,maps4 #b4jj4 #ca4 ,,sight3 ,an ,exposition of the ,principles of ,monocular and ,binocular ,vision4 ,by ,professor ,joseph ,le ,conte1 ,,ll4 ,d41 ,university of ,california4 ,with #acb ,illustrations4 #a4ej4 #cb4 ,,general ,,physiology ,,of ,,muscles ,,and ,,nerves4 ,by ,professor ,i4 ,rosenthal1 ,university of ,erlangen4 ,with #ge ,illustrations4 #a4ej4 #cc4 ,,illusions3 ,a ,psychological ,study4 ,by ,james ,sully4 #a4ej4 #cd4 ,,the ,,sun4 ,by ,professor ,c4 ,a4 ,young1 ,college of ,new ,jersey4 ,with #hc ,illustrations4 #b4jj4 #ce4 ,,volcanoes2 ,what they ,are and ,what they ,teach4 ,by ,professor ,john ,w4 ,judd1 ,f4 ,r ,s41 ,royal ,school of ,mines4 ,with #if ,illustrations4 #b4jj4 #cf4 ,,suicide3 ,an ,essay in ,comparative ,moral ,statistics4 ,by ,professor ,henry ,morselli1 ,m4 ,d41 ,royal ,university1 ,turin4 ,with #d ,statistical ,maps4 #a4ge4 #cg4 ,,the ,,formation ,,of ,,vegetable ,,mould1 ,,through ,,the ,,action ,,of ,,worms4 ,with ,observations on their ,habits4 ,by ,charles ,darwin1 ,,ll4 ,d41 ,f4 ,r4 ,s4 ,with #ae ,illustrations4 #a4ej4 #ch4 ,,the ,,concepts ,,and ,,theories ,,of ,,modern ,,physics4 ,by ,j4 ,b4 ,stallo4 #a4ge4 #ci4 ,,the ,,brain ,,and ,,its ,,functions4 ,by ,j4 ,luys1 ,hospice ,salptrire1 ,paris4 ,with #f ,illustrations4 #a4ej4 #dj4 ,,myth ,,and ,,science4 ,by ,tito ,vignoli4 #a4ej4 #da4 ,,diseases ,,of ,,memory3 ,an ,essay in the ,positive ,psychology4 ,by ,th4 ,ribot1 author of ,heredity4 #a4ei4 #db4 ,,ants1 ,,bees4 ,,and ,,wasps4 ,a ,record of ,observations of the ,habits of the ,social ,hymenoptera4 ,by ,sir ,john ,lubbock1 ,bart41 ,f4 ,r4 ,s41 etc4 #b4jj4 #dc4 ,,the ,,science ,,of ,,politics4 ,by ,professor ,sheldon ,amos4 #a4ge4 #dd4 ,,animal ,,intelligence4 ,by ,george ,j4 ,romanes1 ,m4 ,d41 ,f4 ,r4 ,s4 #a4ge4 #de4 ,,man ,,before ,,metals4 ,by ,professor ,n4 ,jolt1 ,science ,faculty of ,toulouse4 ,with #adh ,illustrations4 #a4ge4 #df4 ,,the ,,organs ,,of ,,speech ,,and ,,their ,,application ,,in ,,the ,,formation ,,of ,,articulate ,,sounds4 ,by ,professor ,g4 ,h4 von ,meter1 ,university of ,zrich4 ,with #dg ,illustrations4 #a4ge4 #dg4 ,,fallacies3 ,a ,view of ,logic from the ,practical ,side4 ,by ,alfred ,sidgwick1 ,b4 ,a41 ,oxon4 #a4ge4 #dh4 ,,origin ,,of ,,cultivated ,,plants4 ,by ,alphonse de ,candolle4 #b4jj4 #di4 ,,jelly-,,fish1 ,,star-,,fish1 ,,and ,,sea-,,urchins4 ,a ,research on ,primitive ,nervous ,systems4 ,by ,george ,j4 ,romanes1 ,m4 ,d41 ,f4 ,r4 ,s4 ,with #fc ,illustrations4 #a4ge4 #ej4 ,,the ,,common ,,sense ,,of ,,the ,,exact ,,sciences4 ,by ,william ,kingdon ,clifford4 ,with #ajj ,figures4 #a4ej4 #ea4 ,,physical ,,expression3 ,its ,modes and ,principles4 ,by ,francis ,warner1 ,m4,d41 ,assistant ,physician1 ,london ,hospital4 ,with #ea ,illustrations #a4ge4 #eb4 ,,anthropoid ,,apes4 ,by ,professor ,robert ,hartmann1 ,university of ,berlin4 ,with #fc ,illustrations4 #a4ge4 #ec4 ,,the ,,mammalia ,,in ,,their ,,relation ,,to ,,primeval ,,times ,by ,professor ,oscar ,schmidt1 ,university of ,strasburg4 ,with #ea ,illustrations4 #a4ej4 #ed4 ,,comparative ,,literature4 ,by ,professor ,h4 ,m4 ,posnett1 ,m4 ,a41 ,university ,college1 ,auckland4 #a4ge4 #ee4 ,,earthquakes ,,and ,,other ,,earth ,,movements4 ,by ,professor ,john ,milne1 ,imperial ,college of ,engineering1 ,tokio4 ,with #ch ,figures4 #a4ge4 #ef4 ,,microbes1 ,,ferments1 ,,and ,,moulds4 ,by ,e4 ,l4 ,trouessart4 ,with #ajg ,illustrations4 #a4ej4 #eg4 ,,the ,,geographical ,,and ,,geological ,,distribution ,,of ,,animals4 ,by ,professor ,angelo ,heilprin1 ,academy of ,natural ,sciences1 ,philadelphia4 #b4jj4 #eh4 ,,weather4 ,a ,popular ,exposition of the ,nature of ,weather ,changes from ,day to ,day4 ,with #if ,diagrams4 ,by ,hon4 ,ralph ,abercromby4 #a4ge4 #ei4 ,,animal ,,magnetism4 ,by ,alfred ,binet and ,charles ,fr1 ,assistant ,physician1 ,hospice ,salptrire1 ,paris4 ,with #af ,figures4 #a4ej4 #fj4 ,,international ,,law1 with ,materials for a ,code of ,international ,law4 ,by ,professor ,leone ,levi1 ,king's ,college1 ,london4 #a4ej4 #fa4 ,,the ,,geological ,,history ,,of ,,plants4 ,with #gi ,illustrations4 ,by ,sir ,j4 ,william ,dawson4 ,,ll4 ,d44 ,f4 ,b4 ,s4 #a4ge4 #fb4 ,,anthropology4 ,an ,introduction to the ,study of ,man and ,civilization4 ,by ,edward ,b4 ,tylor1 ,d4 ,c4 ,l41 ,f4 ,r4 ,s4 ,with #gh ,illustrations4 #b4jj4 #fc4 ,,the ,,origin ,,of ,,floral ,,structures1 ,,through ,,insect ,,and ,,other ,,agencies4 ,by the ,rev4 ,george ,henslow1 ,m4 ,a41 etc4 ,with #hh ,illustrations4 #a4ge4 #fd4 ,,the ,,senses1 ,,instincts1 ,,and ,,intelligence ,,of ,,animals1 ,,with ,,special ,,reference ,,to ,,insects4 ,by ,sir ,john ,lubbock1 ,bart41 ,f4 ,r4 ,s41 etc4 ,with #aah ,illustrations4 #a4ge4 #fe4 ,,the ,,primitive ,,family ,,in ,,its ,,origin ,,and ,,development4 ,by ,dr4 ,c4 ,n4 ,starcke1 ,university of ,copenhagen4 #a4ge4 #ff4 ,,physiology ,,of ,,bodily ,,exercise4 ,by ,f4 ,lagrange1 ,m4,d4 #a4ge4 #fg4 ,,the ,,colors ,,of ,,animals3 ,their ,meaning and ,use4 ,by ,edward ,bagnall ,poulton1 ,f4 ,r4 ,s4 ,with #cf ,illustrations and #a ,colored ,plate4 #a4ge4 #fh4 ,,socialism3 ,new and ,old4 ,by ,professor ,william ,graham1 ,m4 ,a41 ,queen's ,college1 ,belfast4 #a4ge4 #fi4 ,,man ,,and ,,the ,,glacial ,,period4 ,by ,professor ,g4 ,frederick ,wright1 ,d4 ,d41 ,oberlin ,theological ,seminary4 ,with #ajh ,illustrations and #c ,maps4 #a4ge4 #gj4 ,,handbook ,,of ,,greek ,,and ,,latin ,,pal,,ography4 ,by ,edward ,maunde ,thompson1 ,d4 ,c4 ,l41 etc4 #b4jj4 #ga4 ,a ,,history ,,of ,,crustacea4 ,recent ,malacostraca4 ,by the ,rev4 ,thomas ,r4 ,r4 ,stebbing1 ,m4 ,a4 ,with #ea ,illustrations4 #b4jj4 #gb4 ,,race ,,and ,,language4 ,by ,professor ,andr ,lefvre1 ,anthropological ,school1 ,paris4 ,new ,york3 ,d4 ,,appleton ,,co41 #gb ,filth ,avenue4 99 99 99 99 99 ,illustration3 ,,contour ,,and ,,glacial ,,map ,,of ,,the ,,british ,,isles ,,the ,,international ,,scientific ,,series ,,man ,,and ,,the ,,glacial ,,period ,,by ,g4 ,,frederick ,,wright ,d4 ,d41 ,,ll4 ,d41 ,f4 ,g4 ,s4 ,a4 ,,professor ,,in ,,oberlin ,,theological ,,seminary ,,formerly ,,assistant ,,on ,,the ,,united ,,states ,,geological ,,survey ,,author ,,of ,,the ,,ice ,,age ,,in ,,north ,,america4 ,,logic ,,of ,,christian ,,evidences1 ,,etc4 ,,with ,,an ,,appendix ,,on ,,tertiary ,,man ,by ,,prof4 ,,henry ,w4 ,,haynes ,,fully ,,illustrated ,,second ,,edition ,,new ,,york ,d4 ,,appleton ,,and ,,company #ahie ,copyright1 #ahib1 ,by ,d4 ,,appleton ,,and ,,company4 ,electrotyped and ,printed at the ,appleton ,press1 ,u4 ,s4 ,a4 ,,to ,,judge ,c4 ,c4 ,,baldwin ,,president ,,of ,,the ,,western ,,reserve ,,historical ,,society ,,cleveland ,,this ,,volume ,,is ,,dedicated ,,in ,,recognition ,,of ,,his ,,sagacious ,,and ,,unfailing ,,interest ,,in ,,the ,,investigations ,,which ,,have ,,made ,,it ,,possible ,,preface ,,to ,,the ,,second ,,edition4 ,since1 as stated in the ,introduction 7page #a71 the plan of this volume permitted only a concise presentation of the facts1 it was impossible to introduce either full references to the illimitable literature of the subject or detailed discussion of all disputed points4 ,the facts selected1 therefore1 were for the most part those upon which it was supposed there would be pretty general agreement4 ,the discussion upon the subject of the continuity of the ,glacial period was1 however1 somewhat elaborate 7see pages #ajf-aba1 #caa1 #cbd1 #ccb71 and was presented with excessive respect for the authority of those who maintain the opposite view2 all that was claimed 7page #aaj7 being that one might maintain the unity or continuity of the ,glacial period without forfeiting his right to the respect of his fellow-geologists4 ,but it already appears that there was no need of this extreme modesty of statement4 ,on the contrary1 the vigorous discussion of the subject which has characterized the last two years reveals a decided reaction against the theory that there has been more than one ,glacial epoch in ,quaternary times2 while there have been brought to light many most important if not conclusive facts in favour of the theory supported in the volume4 ,in ,america the continuity of the ,glacial period has been maintained during the past two years with important new evidence1 among others by authorities of no less eminence and special experience in glacial investigations than ,professor ,dana1,a ,mr4 ,warren ,upham1,b and ,professor ,edward ,h4 ,williams1 ,jr4,c ,professor ,williams's investigations on the attenuated border of the glacial deposits in the ,lehigh1 the most important upper tributary to the ,delaware ,valley1 ,pa41 are of important significance1 since the area which he so carefully studied lies wholly south of the terminal moraine of ,lewis and ,wright1 and belongs to the portion of the older drift which ,professors ,chamberlin and ,salisbury have been most positive in assigning to the first ,glacial epoch1 which they have maintained was separated from the second epoch by a length of time sufficient for the streams to erode rock gorges in the ,delaware and ,lehigh ,rivers from two hundred to three hundred feet in depth4,d ,but ,professor ,williams has found that the rock gorges of the ,lehigh1 and even of its southern tributaries1 had been worn down approximately to the present depth of that of the ,delaware before this earliest period of glaciation1 and that the gorges were filled with the earliest glacial dbris4 ,footnote ,a3 ,american ,journal of ,science1 vol4 xlvi1 pp4 #cbg1 #ccj4 ,footnote ,b3 ,american ,journal of ,science1 vols1 xlvi1 pp4 #aad-aba2 xlvii1 pp4 #ceh-cfe2 ,american ,geologist1 vols1 x1 pp4 #cci-cfb1 especially pp4 #cfa1 #cfb2 xiii1 pp4 #aad1 #bgh2 ,bulletin of the ,geological ,society of ,america1 vol4 v1 pp4 #ga-hf1 #hg-ajj4 ,footnote ,c3 ,bulletin of the ,geological ,society of ,america1 vol4 v1 pp4 #ac-af1 #bha-bif2 ,american ,journal of ,science1 vol4 xlvii1 pp4 #cc-cf4 ,footnote ,d3 ,see especially ,chamberlin1 in the ,american ,journal of ,science1 vol4 xlv1 p4 #aib2 ,salisbury1 in the ,american ,geologist1 vol4 xi1 p4 #ah4 ,a similar relation of the glacial deposits of the attenuated border to the preglacial erosion of the rock gorges of the ,alleghany and upper ,ohio ,rivers has been brought to light by the joint investigations of ,mr4 ,frank ,leverett and myself in western ,pennsylvania1 in the vicinity of ,warren1 ,pa41 where1 in an area which was affected by only the earliest glaciation1 glacial deposits are found filling the rock channels of old tributaries to the ,alleghany to a depth of from one hundred and seventy to two hundred and fifty feet1 and carrying the preglacial erosion at that point very closely1 if not quite1 down to the present rock bottoms of all the streams4 ,this removes from ,professor ,chamberlin a most important part of the evidence of a long interglacial period to which he had appealed2 he having maintained,e that the higher glacial gravels antedated those of the moraine-forming epoch by the measure of the erosion of the channel through the old drift and the rock1 whose mean depth here is about three hundred feet1 of which perhaps two hundred and fifty feet may be said to be rock1 adding that the excavation that intervened between the two epochs in other portions of the ,alleghany1 ,monongahela1 and upper ,ohio valleys is closely comparable with this4 ,footnote ,e3 ,bulletin #eh of the ,united ,states ,geological ,survey1 p4 #ce2 ,american ,journal of ,science1 vol4 xlv1 p4 #aie4 ,these observations of ,mr4 ,leverett and myself seem to demonstrate the position maintained in the volume 7page #bah71 namely1 that the inner precipitous rock gorges of the upper ,ohio and its tributaries are mainly preglacial1 rather than interglacial4 ,the only way in which ,professor ,chamberlin can in any degree break the force of this discovery is by assuming that in preglacial times the present narrow rock gorges of the ,alleghany and the ,ohio were not continuous1 but that 7as indicated in the present volume on page #bjf7 the drainage of various portions of that region was by northern outlets to the ,lake ,erie basin1 leaving1 on this supposition1 the cols between two or three drainage areas to be lowered in glacial or interglacial time4 ,on the theory of continuity the erosion of these cols would have been rapidly effected by the reversed drainage consequent upon the arrival of the ice-front at the southern shore of the ,lake ,erie basin4 ,during all the time elapsing thereafter1 until the ice had reached its southern limit1 the stream was also augmented by the annual partial melting of the advancing glacier which was constantly bringing into the valley the frozen precipitation of the far north4 ,the distance is from thirty to seventy miles1 so that a moderately slow advance of the ice at that stage would afford time for a great amount of erosion before sufficient northern gravel had reached the region to begin the filling of the gorge4,f ,footnote ,f3 ,see an elaborate discussion of the subject in its new phases by ,chamberlin and ,leverett1 in the ,american ,journal of ,science1 vol4 xlvii1 pp4 #bdg-bhc4 ,mr4 ,leverett also presented an important paper before the ,geological ,society of ,america at its meeting at ,madison1 ,wis41 in ,august1 #ahic1 adducing evidence which1 he thinks1 goes to prove that the post-glacial erosion in the earlier drift in the region of ,rock ,river1 ,ill41 was seven or eight times as much as that in the later drift farther north2 while ,mr4 ,oscar ,h4 ,hershey arrives at nearly the same conclusions from a study of the buried channels in northwestern ,illinois4,g ,but even if these estimates are approximately correct--which is by no means certain--they only prove the length of the ,glacial period1 and not necessarily its discontinuity4 ,footnote ,g3 ,american ,geologist1 vol4 xii1 p4 #cad;f4 ,other important evidence to a similar effect is given by ,mr4 ,leverett1 in an article on ,the ,glacial ,succession in ,ohio1 ,journal of ,geology1 vol4 i1 pp4 #abi-adf4 ,at the same time it should be said that these investigations in western ,pennsylvania somewhat modify a portion of the discussion in the present volume concerning the effects of the ,cincinnati ice-dam4 ,it now appears that the full extent of the gravel terraces of glacial origin in the ,alleghany ,river had not before been fully appreciated1 since they are nearly continuous on the two-hundred-foot rock shelf1 and are often as much as eighty feet thick4 ,it seems probable1 therefore1 that the ,alleghany and upper ,ohio gorge was filled with glacial gravel to a depth of about two hundred and fifty or three hundred feet1 as far down at least as ,wheeling1 ,w4 ,va4 ,if this was the case1 it would obviate the necessity of bringing in the ,cincinnati ice-dam 7as set forth in pages #bab-baf7 to account directly for all the phenomena in that region1 except as this obstruction at ,cincinnati would greatly facilitate the silting up of the gorge4 ,the simple accumulation of glacial gravel in the ,alleghany gorge would of itself dam up the ,monongahela at ,pittsburg1 so as to produce the results detailed by ,professor ,white on page #bae4;,h ,footnote ,h3 ,for a full discussion of these topics1 see paper by ,professor ,b4 ,c4 ,jillson1 ,transactions of the ,academy of ,science and ,art of ,pittsburg1 ,december #h1 #ahic2 ,g4 ,f4 ,wright1 ,american ,journal of ,science1 vol4 xlvii1 pp4 #afa-ahg2 especially pp4 #agg1 #agh2 ,the ,popular ,science ,monthly1 vol4 xlv1 pp4 #ahd-aih4 ,of ,european authorities who have recently favoured the theory of the continuity of the ,quaternary ,glacial period1 as maintained in the volume1 it is enough to mention the names of ,prestwich1,i ,hughes1,j ,kendall1,k ,lamplugh1,l and ,wallace1,m of ,england2 ,falsan1,n of ,france2 ,holst1,o of ,sweden2 ,credner,p and ,diener1,q of ,germany2 and ,nikitin,r and ,kropotkin1,s of ,russia4,t ,among leading authorities still favouring a succession of ,glacial epochs are3 ,professor ,james ,geikie1,u of ,scotland2 ,baron de ,geer1,v of ,sweden2 and ,professor ,felix ,wahnschaffe1,w of ,germany4 ,footnote ,i3 ,quarterly ,journal of the ,geological ,society for ,august1 #ahhg4 ,footnote ,j3 ,american ,geologist1 vol4 viii1 p4 #bda4 ,footnote ,k3 ,transactions of the ,leeds ,geological ,association for ,february #aj1 #ahic4 ,footnote ,l3 ,quarterly ,journal of the ,geological ,society1 ,august1 #ahia4 ,footnote ,m3 ,fortnightly ,review1 ,november1 #ahic1 p4 #fcc2 reprinted in ,the ,popular ,science ,monthly1 vol4 xliv1 p4 #gij4 ,footnote ,n3 ,la ,priode glaciaire 7,flix ,alcan4 ,paris1 #ahhi74 ,footnote ,o3 ,american ,geologist1 vol4 viii1 p4 #bdb4 ,footnote ,p3 ,ibid41 p4 #bda4 ,footnote ,q3 ,ibid41 p4 #bdb4 ,footnote ,r3 ,congrs ,international d',archologie1 ,moscow1 #ahib4 ,footnote ,s3 ,nineteenth ,century1 ,january1 #ahid1 p4 #aea1 note4 ,footnote ,t3 ,the volume ,the ,glacial ,geology of ,great ,britain and ,ireland1 edited from the unpublished ,,mss4 of the late ,henry ,carvill ,lewis 7,london1 ,longmans1 ,green ,co41 #ahid71 adds much important evidence in favour of the continuity of the ,glacial epoch2 see especially pp4 #ahg1 #dfj1 #dfa1 #dff4 ,footnote ,u3 ,transactions of the ,royal ,society of ,edinburgh1 vol4 xxxvii1 ,part ,i1 pp4 #abg-aej4 ,footnote ,v3 ,american ,geologist1 vol4 viii1 p4 #bdf4 ,footnote ,w3 ,forschungen zur deutschen ,landes und ,volkskunde von ,dr4 ,a4 ,kirchhoff4 ,bd4 vi1 ,heft i4 ,when the first edition was issued1 two years ago1 there seemed to be a general acceptance of all the facts detailed in it which directly connected man with the ,glacial period both in ,america and in ,europe2 and1 indeed1 ,i had studiously limited myself to such facts as had been so long and so fully before the public that there would seem to be no necessity for going again into the details of evidence relating to them4 ,it appears1 however1 that this confidence was ill-founded2 for the publication of the book seems to have been the signal for a confident challenge1 by ,mr4 ,w4 ,h4 ,holmes1 of all the ,american evidence1 with intimations that the ,european also was very likely equally defective4,x ,in particular ,mr4 ,holmes denies the conclusiveness of the evidence of glacial man adduced by ,dr4 ,abbott and others at ,trenton1 ,n4 ,j42 ,dr4 ,metz1 at ,madisonville1 ,ohio2 ,mr4 ,mills1 at ,newcomerstown1 ,ohio2 and ,miss ,babbitt1 at ,little ,falls1 ,minn4 ,footnote ,x3 ,journal of ,geology1 vol4 i1 pp4 #ae-cg1 #adg-afc2 ,american ,geologist1 vol4 xi1 pp4 #bai-bdj4 ,the sum of ,mr4 ,holmes's effort amounts1 however1 to little more than the statement that1 with a limited amount of time and labour1 neither he nor his assistants had been able to find any implements in undisturbed gravel in any of these places2 and the suggestion of various ways in which he thinks it possible that the observers mentioned may have been deceived as to the original position of the implements found4 ,but1 as had been amply and repeatedly published1,y ,professor ,j4 ,d4 ,whitney1 ,professor ,lucien ,carr1 ,professor ,n4 ,s4 ,shaler1 ,professor ,f4 ,w4 ,putnam1 of ,harvard ,university1 besides ,dr4 ,c4 ,c4 ,abbott1 all expressly and with minute detail describe finding implements in the undisturbed gravel at ,trenton1 which no one denies to be of glacial origin4 ,in the face of such testimony1 which had been before the public and freely discussed for several years1 it is an arduous undertaking for ,mr4 ,holmes to claim that none of the implements have been found in place1 because he and his assistants 7whose opportunities for observation had scarcely been one twentieth part as great as those of the others7 failed to find any4 ,to see how carefully the original observations were made1 one has but to read the reports to ,professor ,putnam which have from time to time appeared in the ,proceedings of the ,peabody ,museum and of the ,boston ,society of ,natural ,history11 and which are partially summed up in the thirty-second chapter of ,dr4 ,abbott's volume on ,primitive ,industry4 ,footnote ,y3 ,proceedings of the ,boston ,society of ,natural ,history1 vol4 xxi1 ,january #ai1 #ahha2 ,report of the ,peabody ,museum1 vol4 ii1 pp4 #dd-dg2 chap1 xxxii of ,abbott's ,primitive ,industry2 ,american ,geologist1 vol4 xi1 pp4 #ahj-ahd4 ,in the case of the discovery at ,newcomerstown1 ,mr4 ,holmes is peculiarly unfortunate in his efforts to present the facts1 since1 in endeavouring to represent the conditions under which the implement was found by ,mr4 ,mills1 he has relied upon an imaginary drawing of his own1 in which an utterly impossible state of things is pictured4 ,the claim of ,mr4 ,holmes in this case1 as in the other1 is that possibly the gravel in which the implements were found had been disturbed4 ,in some cases1 as in ,little ,falls and at ,madison ville1 he thinks the implements may have worked down to a depth of several feet by the overturning of trees or by the decay of the tap-root of trees4 ,a sufficient answer to these suggestions is1 that ,mr4 ,holmes is able to find no instance in which the overturning of trees has disturbed the soil to a depth of more than three or four feet1 while some of the implements in these places had been found buried from eight to sixteen feet4 ,even if1 as ,mr4 ,chamberlin suggests1,z fifty generations of trees have decayed on the spot since the retreat of the ice1 it is difficult to see how that would help the matter1 since the effect could not be cumulative1 and fifty upturnings of three or four feet would not produce the results of one upturning of eight feet4 ,moreover1 at ,trenton1 where the upturning of trees and the decaying of tap-roots would have been as likely as anywhere to bury implements1 none of those of flint or jasper 7which occur upon the surface by tens of thousands7 are buried more than a foot in depth2 while the argillite implements occur as low down as fifteen or twenty feet4 ,this limitation of flint and jasper implements to the surface is conclusively shown not only by ,dr4 ,abbott's discoveries1 but also by the extensive excavations at ,trenton of ,mr4 ,ernest ,volk1 whose collections formed so prominent a part of ,professor ,putnam's ,palolithic exhibit at the ,columbian ,exposition at ,chicago4 ,in the village sites explored by ,mr4 ,volk1 argillite was the exclusive material of the implements found in the lower strata of gravel4 ,similar results are indicated by the excavations of ,mr4 ,h4 ,c4 ,mercer at ,point ,pleasant1 ,pa41 about twenty miles above ,trenton1 where1 in the lower strata1 the argillite specimens are sixty-one times more numerous than the jasper are4 ,footnote ,z3 ,american ,geologist1 vol4 xi1 p4 #ahh4 ,to discredit the discoveries at ,trenton and ,newcomerstown1 ,mr4 ,holmes relies largely upon the theory that portions of gravel from the surface had slid down to the bottom of the terrace1 carrying implements with them1 and forming a talus1 which1 he thinks1 ,mr4 ,mills1 ,dr4 ,abbott1 and the others have mistaken for undisturbed strata of gravel4 ,in his drawings ,mr4 ,holmes has even represented the gravel at ,newcomerstown as caving down into a talus without disturbing the strata to any great extent1 and at the same time he speaks slightingly of the promise which ,i had made to publish a photograph of the bank as it really was4 ,in answer1 it is sufficient to give1 first1 the drawing made at the time by ,mr4 ,mills1 to show the general situation of the gravel bank at ,newcomerstown1 in which the implement figured on page #beb was found2 and1 secondly1 an engraving from a photograph of the bank1 taken by ,mr4 ,mills after the discovery of the implement1 but before the talus had obscured its face4 ,the implement was found by ,mr4 ,mills with its point projecting from a fresh exposure of the terrace1 just after a mass1 loosened by his own efforts1 had fallen away4 ,the gravel is of such consistency that every sign of stratification disappears when it falls down1 and there could be no occasion for a mistake even by an ordinary observer1 while ,mr4 ,mills was a well-trained geologist and collector1 making his notes upon the spot4,,aa ,footnote ,,aa3 ,the ,popular ,science ,monthly1 vol4 xliii1 pp4 #bi-ci4 ,illustration3 ,height of ,terrace exposed1 #be feet4 ,palolith was found #ad-c_/d feet from surface4 ,illustration3 ,terrace in ,newcomerstown1 showing where ,w4 ,c4 ,mills found the ,palolithic implement4 ,i had thought at first that ,mr4 ,holmes had made out a better case against the late ,miss ,babbitt's discoveries at ,little ,falls 7referred to on page #bed71 but in the ,american ,geologist for ,may1 #ahid1 page #cfc1 ,mr4 ,warren ,upham1 after going over the evidence1 expresses it as still his conviction that ,mr4 ,holmes's criticism fails to shake the force of the original evidence1 so that ,i do not see any reason for modifying any of the statements made in the body of the book concerning the implements supposed to have been found in glacial deposits4 ,yet if ,i had expected such an avalanche of criticism of the evidence as has been loosened1 ,i should at the time have fortified my statements by fuller references1 and should possibly have somewhat enlarged the discussion4 ,but this seemed then the less necessary1 from the fact that ,mr4 ,mc,gee had1 in most emphatic manner1 indorsed nearly every item of the evidence adduced by me1 and much more1 in an article which appeared in ,the ,popular ,science ,monthly four years before the publication of the volume 7,november1 #ahhh74 ,in this article he had said3 ,but it is in the aqueo-glacial gravels of the ,delaware ,river at ,trenton1 which were laid down contemporaneously with the terminal moraine one hundred miles farther northward1 and which have been so thoroughly studied by ,abbott1 that the most conclusive proof of the existence of glacial man is found 7p4 #bc74 ,excluding all doubtful cases1 there remains a fairly consistent body of testimony indicating the existence of a widely distributed human population upon the ,north4 ,american continent during the later ,ice epoch 7p4 #bd74 ,however the doubtful cases may be neglected1 the testimony is cumulative1 parts of it are unimpeachable1 and the proof of the existence of glacial man seems conclusive 7p4 #be74 ,in view of the grossly erroneous statements made by ,mr4 ,mc,gee concerning the ,nampa image 7described on pages #bih1 #bii71 it is necessary for me to speak somewhat more fully of this important discovery4 ,the details concerning the evidence were drawn out by me at length in two communications to the ,boston ,society of ,natural ,history 7referred to on page #big71 which fill more than thirty pages of closely printed matter1 while two or three years before the appearance of the volume the facts had been widely published in the ,new ,york ,independent1 the ,scientific ,american1 ,the ,nation1 ,scribner's ,magazine1 and the ,atlantic ,monthly1 and in ,washington at a meeting of the ,geological ,society of ,america in #ahij4 ,in the second communication to the ,boston ,society of ,natural ,history an account was given of a personal visit to the ,snake ,river ,valley1 largely for the purpose of further investigation of the evidence brought to my notice by ,mr4 ,charles ,francis ,adams1 and of the conditions under which the figurine was found4 ,among the most important results of this investigation was the discovery of numerous shells under the lava deposits1 which ,mr4 ,dall1 of the ,united ,states ,geological ,survey1 identified for me as either post-,tertiary or late ,pliocene2 thus throwing the superficial lava deposits of the region into the ,quaternary period1 and removing from the evidence the antecedent improbability which would bear so heavily against it if we were compelled to suppose that the lava of the ,snake ,river region was all of ,tertiary or even of early ,quaternary age4 ,furthermore1 the evidence of the occurrence of a great dbcle in the ,snake ,river ,valley during the ,glacial period1 incident upon the bursting of the banks of ,lake ,bonneville1 goes far to remove antecedent presumptions against the occurrence of human implements in such conditions as those existing at ,nampa 7see below1 pp4 #bcc-bcg74 ,mr4 ,mc,gee's misunderstanding of the evidence on one point is so gross1 that ,i must make special reference to it4 ,he says,,ab that this image is alleged to have been pounded out of volcanic tuff by a heavy drill1 444 under a thick ,tertiary lava bed4 ,the statement of facts on page #bih bears no resemblance to this representation4 ,it is there stated that there were but fifteen feet of lava1 and that near the surface2 that below this there was nothing but alternating beds of clay and quicksand1 and that the lava is post-,tertiary4 ,the sand-pump ,i should perhaps have described more fully in the book1 as ,i had already done in the communication to the ,boston ,society of ,natural ,history4 ,it was a tube eight feet long1 with a valve at the bottom three and a half inches in diameter on the inside4 ,through this it was the easiest thing in the world for the object1 which is only one inch and a half long1 to be brought up in the quicksand without injury4 ,footnote ,,ab3 ,literary ,northwest1 vol4 ii1 p4 #bge4 ,the baseless assertions of ,mr4 ,mc,gee1 involving the honesty of ,messrs4 ,kurtz and ,duffes1 are even less fortunate and far more reprehensible4 ,it is a fact1 says ,mr4 ,mc,gee1 that one of the best-known geologists of the world chanced to visit ,nampa while the boring was in progress1 and the figurine and the pretty fiction were laid before him4 ,he recognized the figurine as a toy such as the neighbouring ,indians give their children1 and laughed at the story2 whereupon the owner of the object enjoined secrecy1 pleading3 ',don't give me away2 ,i've fooled a lot of fellows already1 and ,i'd like to fool some more4',,ac ,this well-known geologist1 on being challenged by ,professor ,claypole,,ad to give a full1 exact1 and certified statement of the conversation above referred to1 proved to be ,major ,powell1 who responded with the following statement3 ,in the fall of #ahhi the writer visited ,boise ,city1 in ,idaho twenty miles from ,nampa4 ,while stopping at a hotel1 some gentlemen called on him to show him a figurine which they said they had found in sinking an artesian well in the neighbourhood1 at a depth1 if ,i remember rightly1 of more than three hundred feet4444 ,when this story was told the writer1 he simply jested with those who claimed to have found it4 ,he had known the ,indians that live in the neighbourhood1 had seen their children play with just such figurines1 and had no doubt that the little image had lately belonged to some ,indian child1 and said the same4 ,while stopping at the hotel different persons spoke about it1 and it was always passed off as a jest2 and various comments were made about it by various people1 some of them claiming that it had given them much sport1 and that a good many tenderfeet had looked at it1 and believed it to be genuine2 and they seemed rather pleased that ,i had detected the hoax4,,ae ,footnote ,,ac3 ,american ,anthropologist1 vol4 vi1 p4 #id3 repeated by ,mr4 ,mc,gee in the ,literary ,northwest1 vol4 ii1 p4 #bgf4 ,footnote ,,ad3 ,the ,popular ,science ,monthly1 vol4 xlii1 p4 #ggc4 ,footnote ,,ae3 ,ibid41 vol4 xliii1 pp4 #cbb1 #cbc4 ,thus it appears that ,major ,powell has made no such statement1 at least in public1 as ,mr4 ,mc,gee attributes to him4 ,it should be said1 also1 that ,major ,powell's memory is very much at fault when he affirms that there is a close resemblance between this figurine and some of the children's playthings among the ,pocatello ,indians4 ,on the contrary1 it would have been even more of a surprise to find it in the hands of these children than to find it among the prehistoric deposits on the ,pacific coast4 ,to most well-informed people it is sufficient to know that no less high authorities than ,mr4 ,charles ,francis ,adams and ,mr4 ,g4 ,m4 ,gumming1 ,general ,manager for the ,union ,pacific line for that district1 carefully investigated the evidence at the time of the discovery1 and1 knowing the parties1 were entirely satisfied with its sufficiency4 ,it was also subjected to careful examination by ,professor ,f4 ,w4 ,putnam1 who discerned1 in a deposit of an oxide of iron on various parts of the image1 indubitable evidence that it was a relic which had lain for a long time in some such condition as was assigned to it in the bottom of the well--all of which is detailed in the papers referred to below1 on page #big4 ,finally1 the discovery1 both in its character and conditions1 is in so many respects analogous to those made under ,table ,mountain1 near ,sonora1 ,cal4 7described on pages #bid-big71 that the evidence of one locality adds cumulative force to that of the other4 ,the strata underneath the lava in which these objects were found are all indirectly1 but pretty certainly1 connected with the ,glacial period4,,af ,no student of glacial archology1 therefore1 can hereafter afford to disregard these facts from the ,pacific coast4 ,footnote ,,af3 ,see below1 p4 #cdi4 ,oberlin1 ,ohio1 ,june #b1 #ahid4 ,,preface ,,to ,,the ,,first ,,edition4 ,the wide interest manifested in my treatise upon ,the ,ice ,age in ,north ,america and its ,bearing upon the ,antiquity of ,man 7of which a third edition was issued a year ago71 seemed to indicate the desirability of providing for the public a smaller volume discussing the broader question of man's entire relation to the ,glacial period in ,europe as well as in ,america4 ,when the demand for such a volume became evident1 ,i set about preparing for the task by spending1 first1 a season in special study of the lava-beds of the ,pacific coast1 whose relations to the ,glacial period and to man's antiquity are of such great interest2 and1 secondly1 a summer in ,europe1 to enable me to compare the facts bearing upon the subject on both continents4 ,of course1 the chapters of the present volume relating to ,america cover much of the same ground gone over in the previous treatise2 but the matter has been entirely rewritten and very much condensed1 so as to give due proportions to all parts of the subject4 ,it will interest some to know that most of the new material in this volume was first wrought over in my second course of ,lowell ,institute ,lectures1 given in ,boston during the month of ,march last4 ,i am under great obligations to ,mr4 ,charles ,francis ,adams for his aid in prosecuting investigations upon the ,pacific coast of ,america2 and also to ,dr4 ,h4 ,w4 ,crosskey1 of ,birmingham1 ,england1 and to ,mr4 ,g4 ,w4 ,lamplugh1 of ,bridlington1 as well as to ,mr4 ,c4 ,e4 ,de ,rance and ,mr4 ,clement ,reid1 of the ,british ,geological ,survey1 besides many others in ,england who have facilitated my investigations2 but pre-eminently to ,prof4 ,percy ,f4 ,kendall1 of ,stockport1 who consented to prepare for me the portion of ,chapter ,,vi which relates to the glacial phenomena of the ,british ,isles4 ,i have no doubt of the general correctness of the views maintained by him1 and little doubt1 also1 that his clear and forcible presentation of the facts will bring about what is scarcely less than a revolution in the views generally prevalent relating to the subject of which he treats4 ,for the glacial facts relating to ,france and ,switzerland ,i am indebted largely to ,m4 ,falsan's valuable compendium1 ,la ,priode ,glaciaire4 ,it goes without saying1 also1 that ,i am under the deepest obligation to the works of ,prof4 ,james ,geikie upon ,the ,great ,ice ,age and upon ,prehistoric ,europe1 and to the remarkable volume of the late ,mr4 ,james ,croll upon ,climate and ,time1 as well as to the recent comprehensive geological treatises of ,sir ,archibald ,geikie and ,prof4 ,prestwich4 ,finally1 ,i would express my gratitude for the great courtesy of ,prof4 ,fraipont1 of ,lige1 in assisting me to an appreciation of the facts relating to the late remarkable discovery of two entire skeletons of ,paleolithic man in the grotto of ,spy4 ,comparative completeness is also given to the volume by the appendix on the question of man's existence during the ,tertiary period1 prepared by the competent hand of ,prof4 ,henry ,w4 ,haynes1 of ,boston4 ,i trust this brief treatise will be useful not only in interesting the general public1 but in giving a clear view of the present state of progress in one department of the inquiries concerning man's antiquity4 ,if the conclusions reached are not as positive as could be wished1 still it is both desirable and important to see what degree of indefiniteness rests upon the subject1 in order that rash speculations may be avoided and future investigations directed in profitable lines4 ,g4 ,frederick ,wright4 ,oberlin1 ,ohio1 ,may #a1 #ahib4 ,,contents4 ,,pages ,,chapter ,i4 ,introductory #a-h ,,chapter ,,ii4 ,existing ,glaciers #i-db ,in ,europe2 in ,asia2 in ,oceanica2 in ,south ,america2 on the ,antarctic ,continent2 in ,north ,america4 ,,chapter ,,iii4 ,glacial ,motion #dc-ej ,,chapter ,,iv4 ,signs of ,past ,glaciation #ea-fe ,,chapter ,v4 ,ancient ,glaciers in the ,western ,hemisphere #ff-abh ,new ,england2 ,new ,york1 ,new ,jersey1 and ,pennsylvania2 the ,mississippi ,basin2 west of the ,rocky ,mountains4 ,,chapter ,,vi4 ,ancient ,glaciers in the ,eastern ,hemisphere #abi-aib ,central and ,southern ,europe2 the ,british ,isles--the ,preglacial ,level of the ,land1 the ,great ,glacial ,centres1 the ,confluent ,glaciers1 the ,east ,anglian ,glacier1 the so-called ,great ,submergence2 ,northern ,europe2 ,asia2 ,africa4 ,,chapter ,,vii4 ,drainage ,systems in the ,glacial ,period #aic-bda ,in ,america--,preglacial ,erosion1 ,buried ,outlets and ,channels1 ,ice-dams1 ,ancient ,river ,terraces2 in ,europe4 ,,chapter ,,viii4 ,relics of ,man in the ,glacial ,period #bdb-cja ,in ,glacial ,terraces of the ,united ,states2 in ,glacial ,terraces of ,europe2 in ,cave ,deposits in the ,british ,isles2 in ,cave ,deposits on the ,continent2 ,extinct ,animals associated with ,man2 ,earliest ,man on the ,pacific ,coast of ,north ,america4 ,,chapter ,,ix4 ,the ,cause of the ,glacial ,period #cjb-cca ,,chapter ,x4 ,the ,date of the ,glacial ,period #ccb-cfd ,appendix on the ,tertiary ,man #cfe-cgd ,index #cge-che ,,list ,,of ,,illustrations4 ,,fig4 ,,page #a4 ,zermatt ,glacier #b #b4 ,formation of veined structure #c #c1 #d4 ,formation of marginal fissures and veins #d #e4 ,fissures and seracs #d #f4 ,section across glacial valley1 showing old lateral moraines #e #g4 ,mont ,blanc glacier region #aj #h4 ,svartisen ,glacier #ac #i4 ,floating berg #ah #aj4 ,iceberg in the ,antarctic ,ocean #bj #aa4 ,map of southeastern ,alaska #bb #ab4 ,map of ,glacier ,bay1 ,alaska #be #ac4 ,front of ,muir ,glacier #bf #ad4 ,map of glaciers in the ,st4 ,elias ,alps #ca #ae4 ,map of ,greenland #cc #af4 ,diagram showing the character of glacial motion #dc #ag4 ,line of most rapid glacial motion #de #ah4 ,diagram showing retardation of the bottom of a glacier #df #ai4 ,bed-rock scored with glacial marks #eb #bj4 ,scratched stone from the till of ,boston #ed #ba4 ,typical section of till in ,seattle1 ,wash4 #ee #bb4 ,ideal section showing how the till overlies the stratified rocks #ef #bc4 ,vessel ,rock1 a glacial boulder #ef #bd4 ,map of ,rhne ,glacier #eh #be4 ,conglomerate boulder found in ,boone ,county1 ,ky4 #fc #bf4 ,mohegan ,rock #gb #bg4 ,drumlins in ,goffstown1 ,n4 ,h4 #gc #bh4 ,map of drumlins in the vicinity of ,boston #ge #bi4 ,section of kame #gg #cj4 ,map of kames in ,andover1 ,mass4 #gh #ca4 ,longitudinal kames near ,hingham1 ,mass4 #gi #cb4 ,map showing the kames of ,maine and southeastern ,new ,hampshire #ha #cc4 ,western face of the ,kettle ,moraine near ,eagle1 ,wis4 #ii #cd4 ,section of the east-and-west glacial furrows on ,kelly's ,island #ajc #ce4 ,same as the preceding #aje #cf4 ,section of till near ,germantown1 ,ohio #ajh #cg4 ,moraines of ,grape ,creek1 ,col4 #abc #ch4 ,map of ,north ,america in the ,ice period #abg #ci4 ,quartzite boulder on ,mont ,lachat #abh #dj4 ,map showing glaciated areas in ,north ,america and ,europe #acj #da4 ,maps showing lines of dbris extending from the ,alps into the plains of the ,po #acd #db4 ,section of the ,cefn ,cave #adh #dc4 ,map showing moraine between ,speeton and ,flamborough #aef #dd4 ,diagram-section near ,cromer #aff #de4 ,section through the westerly chalk bluff at ,trimingham1 ,norfolk #afb #df4 ,section across ,wales #agb #dg4 ,section of cliff at ,flamborough ,head #agf #dh4 ,enlarged section of the shelly sand and surrounding clay at ,b in preceding figure #agg #di4 ,map showing the glaciated area of ,europe #ahd #ej4 ,map showing old channel and mouth of the ,hudson #aie #ea4 ,new ,york ,harbor in preglacial times #aig #eb4 ,section across the valley of the ,cuyahoga ,river #bjj #ec4 ,map of ,mississippi ,river from ,fort ,snelling to ,minneapolis #bji #ed4 ,map showing the effect of the glacial dam at ,cincinnati #bac #ee4 ,map of ,lake ,erie-,ontario #bai #ef4 ,map of ,cuyahoga ,lake #bba #eg4 ,section of the lake ridges near ,sandusky1 ,ohio #bbc #eh4 ,map showing stages of recession of the ice in ,minnesota #bbe #ei4 ,glacial terrace on ,raccoon ,creek1 in ,ohio #bbg #fj4 ,ideal section across a river-bed in drift region #bbi #fa4 ,map of ,lakes ,bonneville and ,lahontan #bcd #fb4 ,parallel roads of ,glen ,roy #bci #fc4 ,map showing glacial terraces on the ,delaware and ,schuylkill ,rivers #bdc #fd4 ,palolith found by ,abbott in ,new ,jersey #bdd #fe4 ,section across the ,delaware ,river at ,trenton1 ,n4 ,j4 #bde #ff4 ,section of the ,trenton gravel #bdf #fg4 ,face view of argillite implement found by ,dr4 ,c4 ,c4 ,abbott in #ahgf4 #bdg #fh4 ,argillite implement found by ,dr4 ,c4 ,c4 ,abbott1 ,march1 #ahgi #bdh #fi4 ,chipped pebble of black chert found by ,dr4 ,c4 ,l4 ,metz1 ,october1 #ahhe #bdi #gj4 ,map showing glaciated area in ,ohio #bej #ga4 ,paloliths from ,newcomerstown and ,amiens 7face view7 #beb #gb4 ,edge view of the preceding #bec #gc4 ,section across the ,mississippi ,valley at ,little ,falls1 ,minn4 #bed #gd4 ,quartz implement found by ,miss ,f4 ,e4 ,babbitt1 #ahgh1 at ,little ,falls1 ,minn #bee #ge4 ,argillite implement found by ,h4 ,t4 ,cresson1 #ahhg #bei #gf4 ,general view of ,baltimore and ,ohio ,railroad cut1 ,claymont1 ,del4 #bfj #gg4 ,section across valley of the ,somme #bfb #gh4 ,mouth of ,kent's ,hole #bfh #gi4 ,engis skull 7reduced7 #bgd #hj4 ,comparison of forms of skulls #bgf #ha4 ,skull of the ,man of ,spy #bgg #hb4 ,tooth of ,machairodus neogus #bha #hc4 ,perfect tooth of an ,elephas #bha #hd4 ,skull of ,hyena spela #bhb #he4 ,celebrated skeleton of mammoth in ,st4 ,petersburg ,museum #bhc #hf4 ,molar tooth of mammoth #bhd #hg4 ,tooth of ,mastodon ,americanus #bhd #hh4 ,skeleton of ,mastodon ,americanus #bhf #hi4 ,skeleton of ,rhinoceros tichorhinus #bhg #ij4 ,skull of cave-bear #bhg #ia4 ,skeleton of the ,irish elk #bhh #ib4 ,musk-sheep #bhi #ic4 ,reindeer #bij #id4 ,section across ,table ,mountain1 ,tuolumne ,county1 ,cal4 #bid #ie4 ,calaveras skull #bie #if4 ,three views of ,nampa image1 drawn to scale #bih #ig4 ,map showing ,pocatello1 ,nampa1 and the valley of ,snake ,river #bii #ih4 ,section across the channel of the ,stanislaus ,river #cjj #ii4 ,diagram showing effect of precession #cjh #ajj4 ,map showing course of currents in the ,atlantic ,ocean #cad #aja4 ,map showing how the land clusters about the north pole #cai #ajb4 ,diagram showing oscillations of land-surface and ice-surface during the ,glacial epoch #cbc #ajc4 ,diagram of eccentricity and precession #ccc #ajd4 ,map of the ,niagara ,river below the ,falls #ccd #aje4 ,section of strata along the ,niagara ,gorge #ccf #ajf4 ,map showing the recession of the ,horseshoe ,falls since #ahdb #cch #ajg4 ,section of kettle-hole near ,pomp's ,pond1 ,andover1 ,mass4 #cde #ajh4 ,flint-flakes collected by ,abb ,bourgeois #cfh ,,maps4 ,,to ,,face ,,page ,contour and glacial map of the ,british ,isles ,frontispiece4 ,map showing the glacial geology of the ,united ,states #ff ,map of glacial movements in ,france and ,switzerland #acb ,,man ,,and ,,the ,,glacial ,,period4 ,,chapter ,i4 ,,introductory4 ,that glaciers now exist in the ,alps1 in the ,scandinavian range1 in ,iceland1 in the ,himalayas1 in ,new ,zealand1 in ,patagonia1 and in the mountains of ,washington1 ,british ,columbia1 and southeastern ,alaska1 and that a vast ice-sheet envelops ,greenland and the ,antarctic ,continent1 are statements which can be verified by any one who will take the trouble to visit those regions4 ,that1 at a comparatively recent date1 these glaciers extended far beyond their present limits1 and that others existed upon the highlands of ,scotland and ,british ,america1 and at one time covered a large part of the ,british ,isles1 the whole of ,british ,america1 and a considerable area in the northern part of the ,united ,states1 are inferences drawn from phenomena which are open to every one's observations4 ,that man was in existence and occupied both ,europe and ,america during this great expansion of the northern glaciers is proved by evidence which is now beyond dispute4 ,it is the object of the present volume to make a concise presentation of the facts which have been rapidly accumulating during the past few years relating to the ,glacial period and to its connection with human history4 ,before speaking of the number and present extent of existing glaciers1 it will be profitable1 however1 to devote a little attention to the definition of terms4 ,illustration3 ,fig4 #a4--,zermatt ,glacier 7,agassiz74 ,a glacier is a mass of ice so situated and of such size as to have motion in itself4 ,the conditions determining the character and rate of this motion will come up for statement and discussion later4 ,it is sufficient here to say that ice has a capacity of movement similar to that possessed by such plastic substances as cold molasses1 wax1 tar1 or cooling lava4 ,the limit of a glacier's motion is determined by the forces which fix the point at which its final melting takes place4 ,this will therefore depend upon both the warmth of the weather and upon the amount of ice4 ,if the ice is abundant1 it will move farther into the region of warm temperature than it will if it is limited in supply4 ,upon ascending a glacier far enough1 one reaches a comparatively motionless part corresponding to the lake out of which a river often flows4 ,technically this is called the nv4 ,glacial ice is formed from snow where the annual fall is in excess of the melting power of the sun at that point4 ,through the influence of pressure1 such as a boy applies to a snow-ball 7but which in the nv-field arises from the weight of the accumulating mass71 the lower strata of the nv are gradually transformed into ice4 ,this process1 is also assisted by the moisture which percolates through the snowy mass1 and which is furnished both by the melting of the surface snow and by occasional rains4 ,the division between the nv and the glacier proper is not always easily determined4 ,the beginnings of the glacial movement--that is1 of the movement of the ice-stream flowing out of the nv-field--are somewhat like the beginnings of the movement of the water from a great lake into its outlet4 ,the nv is the reservoir from which the glacier gets both its supply of ice and the impulse which gives it its first movement4 ,there can not be a glacier without a nv-field1 as there can not be a river without a drainage basin4 ,but there may be a nv-field without a glacier--that is1 a basin may be partially filled with snow which never melts completely away1 while the equilibrium of forces is such that the ice barely reaches to the outlet from which the tongue-like projection 7to which the name glacier would be applied7 fails to emerge only because of the lack of material4 ,illustration3 ,fig4 #b4--;,illustrates the formation of veined structure by pressure at the junction of two branches4 ,a glacier is characterised by both veins and fissures4 ,the veins give it a banded or stratified appearance1 blue alternating with lighter-coloured portions of ice4 ,as these bands are not arranged with any apparent uniformity in the glacier1 their explanation has given rise to much discussion4 ,sometimes the veins are horizontal1 sometimes vertical1 and at other times at an angle with the line of motion4 ,on close investigation1 however1 it is found that the veins are always at right angles to the line of greatest pressure4 ,this leads to the conclusion that pressure is the cause of the banded structure4 ,the blue strata in the ice are those from which the particles of air have been expelled by pressure2 the lighter portions are those in which the particles are less thoroughly compacted4 ,snow is but pulverized ice1 and differs in colour from the compact mass for the same reason that almost all rocks and minerals change their colour when ground into a powder4 ,illustration3 ,figs4 #c1 #d4--;,illustrate the formation of marginal fissures and veins4 ,illustration3 ,fig4 #e4--;c1 c1 show fissures and seracs where the glacier moves down the steeper portion of its incline2 s1 s1 show the vertical structure produced by pressure on the gentler slopes4 ,the fissures1 which1 when of large size1 are called crevasses1 are formed in those portions of a glacier where1 from some cause1 the ice is subjected to slight tension4 ,this occurs especially where1 through irregularities in the bottom1 the slope of the descent is increased4 ,the ice1 then1 instead of moving in a continuous stream at the top1 cracks open along the line of tension1 and wedge-shaped fissures are formed extending from the top down to a greater or less distance1 according to the degree of tension4 ,usually1 however1 the ice remains continuous in the lower strata1 and when the slope is diminished the pressure reunites the faces of the fissure1 and the surface becomes again comparatively smooth4 ,where there are extensive areas of tension1 the surface of the ice sometimes becomes exceedingly broken1 presenting a tangled mass of towers1 domes1 and pinnacles of ice called seracs4 ,illustration3 ,fig4 #f4--,section across ,glacial ,valley1 showing old ,lateral ,moraines4 ,like running water1 moving ice is a powerful agent in transporting rocks and earthy dbris of all grades of fineness2 but1 owing to the different consistencies of ice and water1 there are great differences in the mode and result of transportation by them4 ,while water can hold in suspension only the very finest material1 ice can bear upon its surface rocks of the greatest magnitude1 and can roll or shove along under it boulders and pebbles which would be ,unaffected except by torrential currents of water4 ,we find1 therefore1 a great amount of earthy material of all sizes upon the top of a glacier1 which has reached it very much as dbris reaches the bed of a river1 namely1 by falling down upon it from overhanging cliffs1 or by land-slides of greater or less extent4 ,such material coming into a river would either disappear beneath its surface1 or would form a line of dbris along the banks2 in both cases awaiting the gradual erosion and transportation which running water is able to effect4 ,but1 in case of a glacier1 the material rests upon the surface of the ice1 and at once begins to partake of its motion1 while successive accessions of material keep up the supply at any one point1 so as to form a train of boulders and other dbris1 extending below the point as far as the glacial motion continues4 ,such a line of dbris is called a moraine4 ,when it forms along the edge of the ice1 it is called a lateral moraine4 ,it is easy to see that1 where glaciers come out from two valleys which are tributary to a larger valley1 their inner sides must coalesce below the separating promontory1 and the two lateral moraines will become united and will move onward in the middle of the surface of the glacier4 ,such lines of dbris are called medial moraines4 ,these are characteristic of all extensive glaciers formed by the union of tributaries4 ,there is no limit to the number of medial moraines1 except in the number of tributaries4 ,a medial moraine1 when of sufficient thickness1 protects the ice underneath it from melting2 so that the moraine will often appear to be much larger than it really is3 what seems to be a ridge of earthy material being in reality a long ridge of ice1 thinly covered with earthy dbris1 sliding down the slanting sides as the ice slowly wastes away ,large blocks of stone in the same manner protect the ice from melting underneath1 and are found standing on pedestals of ice1 often several feet in height4 ,an interesting feature of these blocks is that1 when the pedestal fails1 the block uniformly falls towards the sun1 since that is the side on which the melting has proceeded most rapidly4 ,if the meteorological forces are so balanced that the foot of a glacier remains at the same place for any great length of time1 there must be a great accumulation of earthy dbris at the stationary point1 since the motion of the ice is constantly bearing its lines of lateral and medial moraine downwards to be deposited1 year by year1 at the melting line along the front4 ,such accumulations are called terminal moraines1 and the process of their formation may be seen at the foot of almost any large glacier4 ,the pile of material thus confusedly heaped up in front of some of the larger glaciers of the world is enormous4 ,the melting away of the lower part of a glacier gives rise also to several other characteristic phenomena4 ,where the foot of a glacier chances to be on comparatively level land1 the terminal moraine often covers a great extent of ice1 and protects it from melting for an indefinite period of time4 ,when the ice finally melts away and removes the support from the overlying morainic dbris1 this settles down in a very irregular manner1 leaving enclosed depressions to which there is no natural outlet4 ,these depressions1 from their resemblance to a familiar domestic utensil1 are technically known as kettle-holes4 ,the terminal moraines of ancient glaciers may often be traced by the relative abundance of these kettle-holes4 ,the streams of water arising both from the rainfall and from the melting of the ice also produce a peculiar effect about the foot of an extensive glacier4 ,sometimes these streams cut long1 open channels near the end of the glacier1 and sweep into it vast quantities of morainic material1 which is pushed along by the torrential current1 and1 after being abraded1 rolled1 and sorted1 is deposited in a delta about its mouth1 or left stranded in long lines between the ice-walls which have determined its course4 ,at other times the stream has disappeared far back in the glacier1 and plunged into a crevasse 7technically called a moulin71 whence it flows onwards as a subglacial stream4 ,but in this case the deposits might closely resemble those of the previous description4 ,in both cases1 when the ice has finally melted away1 peculiar ridge-like deposits of sorted material remain1 to mark the temporary line of drainage4 ,these exist abundantly in most regions which have been covered with glacial ice1 and are referred to in ,scotland as kames1 in ,ireland as eskers1 and in ,sweden as osars4 ,in this volume we shall call them kames1 and the deltas spread out in front of them will be referred to as kame-plains4 ,with this preliminary description of glacial phenomena1 we will proceed to give1 first1 a brief enumeration and description of the ice-fields which are still existing in the world2 second1 the evidences of the former existence of far more extensive ice-fields2 and1 third1 the relation of the ,glacial period to some of the vicissitudes which have attended the life of man in the world4 ,the geological period of which we shall treat is variously designated by different writers4 ,by some it is simply called the post-,tertiary1 or ,quaternary2 by others the term post-,pliocene is used1 to indicate more sharply its distinction from the latter portion of the ,tertiary period2 by others this nicety of distinction is expressed by the term ,pleistocene4 ,but1 since the whole epoch was peculiarly characterised by the presence of glaciers1 which have not even yet wholly disappeared1 we may properly refer to it altogether under the descriptive name of ,glacial period4 ,,chapter ,,ii4 ,,existing ,,glaciers4 ,in ,europe4--,our specific account of existing glaciers naturally begins with those of the ,alps1 where ,hugi1 ,charpentier1 ,agassiz1 ,forbes1 and ,guyot1 before the middle of this century1 first brought clearly to light the reality and nature of glacial motion4 ,according to ,professor ,heim1 of ,zrich1 the total area covered by the glaciers and ice-fields of the ,alps is upwards of three thousand square kilometres 7about eleven hundred square miles74 ,the ,swiss ,alps alone contain nearly two-thirds of this area4 ,professor ,heim enumerates #a1aee distinct glaciers in the region4 ,of these1 #add are in ,france1 #gh in ,italy1 #dga in ,switzerland1 and #dfb in ,austria4 ,desor describes fourteen principal glacial districts in the ,alps1 the westernmost of which is that of ,mont ,pelvoux1 in ,dauphiny1 and the easternmost that in the vicinity of the ,gross ,glockner1 in ,carinthia4 ,the most important of the ,alpine systems are those which are grouped around ,mont ,blanc1 ,monte ,rosa1 and the ,finsteraarhorn1 the two former peaks being upwards of fifteen thousand feet in height1 and the latter upwards of fourteen thousand4 ,the area covered by glaciers and snow-fields in the ,bernese ,oberland1 of which ,finsteraarhorn is the culminating point1 is about three hundred and fifty square kilometres 7a hundred square miles71 and contains the ,aletsch ,glacier1 which is the longest in ,europe1 extending twenty-one kilometres 7about fourteen miles7 from the nv-field to its foot4 ,the ,mer de ,glace1 which descends from ,mont ,blanc to the valley of ,chamounix1 has a length of about eight miles below the nv-field4 ,in all1 there are estimated to be twenty-four glaciers in the ,alps which are upwards of four miles long1 and six which are upwards of eight miles in length4 ,the principal of these are the ,mer de ,glace1 of ,chamounix1 on ,mont ,blanc2 the ,gorner ,glacier1 near ,zermatt1 on ,monte ,rosa2 the lower glacier of the ,aar1 in the ,bernese ,oberland2 and the ,aletsch ,glacier and ,glacier of the ,rhne1 in ,vallais2 and the ,pasterzen1 in ,carinthia4 ,illustration3 ,fig4 #g4--,mount ,blanc ,glacier ,region3 m1 ,mer de ,glace2 g1 ,du ,gant2 l1 ,leschaux2 t1 ,talfre2 ,b1 ,bionassay2 b1 ,bosson4 ,these glaciers adjust themselves to the width of the valleys down which they flow1 in some places being a mile or more in width1 and at others contracting into much narrower compass4 ,the greatest depth which ,agassiz was able directly to measure in the ,aar ,glacier was two hundred and sixty metres 7five hundred and twenty-eight feet71 but at another point the depth was estimated by him to be four hundred and sixty metres 7or fifteen hundred and eighty-four feet74 ,the glaciers of the ,alps are mostly confined to the northern side and to the higher portions of the mountain-chain1 none of them descending below the level of four thousand feet1 and all of them varying slightly in extent1 from year to year1 according as there are changes in the temperature and in the amount of snow-fall4 ,the ,pyrenees1 also1 still maintain a glacial system1 but it is of insignificant importance4 ,this is partly because the altitude is much less than that of the ,alps1 the culminating point being scarcely more than eleven thousand feet in height4 ,doubtless1 also1 it is partly due to the narrowness of the range1 which does not provide gathering-places for the snow sufficiently extensive to produce large glaciers4 ,the snow-fall also is less upon the ,pyrenees than upon the ,alps4 ,as a consequence of all these conditions1 the glaciers of the ,pyrenees are scarcely more than stationary nv-fields lingering upon the north side of the range4 ,the largest of these is near ,bagnres de ,luchon1 and sends down a short1 river-like glacier4 ,in ,scandinavia the height of the mountains is also much less than that of the ,alps1 but the moister climate and the more northern latitude favours the growth of glaciers at a much lower level ,north of the sixty-second degree of latitude1 the plateaus over five thousand feet above the sea pretty generally are gathering-places for glaciers4 ,from the ,justedal a snow-field1 covering five hundred and eighty square miles1 in latitude #fb1 twenty-four glaciers push outwards towards the ,german ,sea1 the largest of which is five miles long and three-quarters of a mile wide4 ,the ,fondalen snow-field1 between latitudes #ff and #fg1 covers an area about equal to that of the ,justedal2 but1 on account of its more northern position1 its glaciers descend through the valleys quite to the ocean-level4 ,the ,folgofon snow-field is still farther south1 but1 though occupying an area of only one hundred square miles1 it sends down as many as three glaciers to the sea-level4 ,the total area of the ,scandinavian snow-fields is about five thousand square miles4 ,in ,sweden ,dr4 ,svenonius estimates that there are1 between latitudes #fg and #fh-a_/b1 twenty distinct groups of glaciers1 covering an area of four hundred square kilometres 7one hundred and forty-four square miles71 and he numbers upwards of one hundred distinct glaciers of small size4 ,as is to be expected1 the large islands in the ,polar ,sea north of ,europe and ,asia are1 to a great extent1 covered with nv-fields1 and numerous glaciers push out from them to the sea in all directions1 discharging their surplus ice as bergs1 which float away and cumber the waters with their presence in many distant places4 ,illustration3 ,fig4 #h4--,the ,svartisen ,glacier on the west coast of ,norway1 just within the ,arctic circle1 at the head of a fiord ten miles from the ocean4 ,the foot of the ,glacier is one mile wide1 and a quarter of a mile back from the water4 ,terminal moraine in front4 7,photographed by ,dr4 ,l4 ,c4 ,warner47 ,the island of ,spitzbergen1 in latitude #gf to #ha1 is favourably situated for the production of glaciers1 by reason both of its high northern latitude1 and of its relation to the ,gulf ,stream1 which conveys around to it an excessive amount of moisture1 thus ensuring an exceptionally large snow-fall over the island4 ,the mountainous character of the island also favours the concentration of the ice-movement into glaciers of vast size and power4 ,still1 even here1 much of the land is free from snow and ice in summer4 ,but upon the northern portion of the island there is an extensive table-land1 upwards of two thousand feet above the sea1 over which the ice-field is continuous4 ,four great glaciers here descend to tide-water in ,magdalena ,bay4 ,the largest of these presents at the front a wall of ice seven thousand feet across and three hundred feet high2 but1 as the depth of the water is not great1 few icebergs of large size break off and float away from it4 ,nova ,zembla1 though not in quite so high latitude1 has a lower mean temperature upon the coasts than ,spitzbergen4 ,owing to the absence of high lands and mountains1 however1 it is not covered with perpetual snow1 much less with glacial ice1 but its level portions are carpeted with grasses and flowers1 and sustain extensive forests of stunted trees4 ,franz-,josef ,land1 to the north of ,nova ,zembla1 both contains high mountains and supports glaciers of great size4 ,mr4 ,payer conducted a sledge party into this land in #ahgd1 and reported that a precipitous wall of glacial ice1 of more than a hundred feet in height1 formed the usual edge of the coast4 ,but the motion of the ice is very slow1 and the ice coarse-grained in structure1 and it bears a small amount only of morainic material4 ,so low is here the line of perpetual snow1 that the smaller islands are covered with caps of ice1 so that a cross-section would exhibit a regular flat segment of ice4 ,it is interesting to note1 also1 that many ice-streams1 descending from the high nv plateau1 spread themselves out over the mountain-slopes1 and are not1 as in the ,alps1 confined to definite valleys4 ,iceland seems to have been properly named1 since a single one of the snow-fields--that of ,vatnajokll1 with an extreme elevation of only six thousand feet--is estimated by ,helland to cover one hundred and fifty ,norwegian square miles 7about seven thousand ,english square miles71 while five other ice-fields 7the ,langjokll1 the ,hofsjokll1 the ,myrdalsjokll1 the ,drangajokll1 and the ,glamujokll7 have a combined area of ninety-two ,norwegian or about four thousand five hundred ,english square miles4 ,the glaciers are supposed by ,whitney to have been rapidly advancing for some time past4 ,in ,asia4--,notwithstanding its lofty mountains and its great extent of territory lying in high latitudes1 glaciers are for two reasons relatively infrequent3 #a4 ,the land in the more northern latitudes is low4 #b4 ,the dryness of the atmosphere in the interior of the continent is such that it unduly limits the snow-fall4 ,long before they reach the central plateau of ,asia1 the currents of air which sweep over the continent from the ,indian ,ocean have parted with their burdens of moisture1 having left them in a snowy mantle upon the southern flanks of the ,himalayas4 ,as a result1 we have the extensive deserts of the interior1 where1 on account of the clear atmosphere1 there is not snow enough to resist continuously the intense activity of the unobstructed rays of the sun4 ,in spite of their high latitude and considerable elevation above the sea-level1 glaciers are absent from the ,ural ,mountains1 for the range is too narrow to afford nv-fields of sufficient size to produce glaciers of large extent4 ,the ,caucasus ,mountains present more favourable conditions1 and for a distance of one hundred and twenty miles near their central portion have an average height of #ab1jjj feet1 with individual peaks rising to a height of #af1jjj feet or more2 but1 owing to their low latitude1 the line of perpetual snow scarcely reaches down to the #aa1jjj-;foot level4 ,so great are the snow-fields1 however1 above this height that many glaciers push their way down through the narrow mountain-gorges as far as the #f1jjj-;foot level4 ,the ,himalaya ,mountains present many favourable conditions for the development of glaciers of large size4 ,the range is of great extent and height1 thus affording ample gathering-places for the snows1 while the relation of the mountains to the moisture-laden winds from the ,indian ,ocean is such that they enjoy the first harvest of the clouds where the interior of ,asia gets only the gleanings4 ,as is to be expected1 therefore1 all the great rivers which course through the plains of ,hindustan have their rise in large glaciers far up towards the summits of the northern mountains4 ,the ,indus and the ,ganges are both glacial streams in their origin1 as are their larger tributary branches--the ,basha1 the ,shigar1 and the ,sutlej4 ,many of the glaciers in the higher levels of the ,himalaya ,mountains where these streams rise have a length of from twenty-five to forty miles1 and some of them are as much as a mile and a half in width and extend for a long distance1 with an inclination as small as one degree and a half or one hundred and thirty-eight feet to a mile4 ,in the ,mustagh range of the western ,himalayas there are two adjoining glaciers whose united length is sixty-five miles1 and another not far away which is twenty-one miles long and from one to two miles wide in its upper portion4 ,its lower portion terminates at an altitude of #af1jjj feet above tide1 where it is three miles wide and two hundred and fifty feet thick4 ,oceanica4---,passing eastward to the islands of the ,pacific ,ocean1 ,new ,zealand is the only one capable of supporting glaciers4 ,their existence on this island seems the more remarkable because of its low latitude 7#db to #de72 but a grand range of mountains rises abruptly from the water on the western coast of the southern island1 culminating in ,mount ,cook1 #ac1jjj feet above the sea1 and extending for a distance of about one hundred miles4 ,the extent and height of this chain1 coupled with the moisture of the winds1 which sweep without obstruction over so many leagues of the tropical ,pacific1 are specially favourable to the production of ice-fields of great extent4 ,consequently we find glaciers in abundance1 some of which are not inferior in extent to the larger ones of the ,alps4 ,the ,tasman ,glacier1 described by ,haas1 is ten miles long and nearly two miles broad at its termination1 the lower portion for a distance of three miles being covered with morainic detritus4 ,the ,mueller ,glacier is about seven miles long and one mile broad in its lower portion4 ,south ,america4--,in ,america1 existing glaciers are chiefly confined to three principal centres1 namely1 to the ,andes1 south of the equator2 to the ,cordilleras1 north of central ,california2 and to ,greenland4 ,in ,south ,america1 however1 the high mountains of ,ecuador sustain a few glaciers above the twelve-thousand-foot level4 ,the largest of these are upon the eastern slope of the mountains1 giving rise to some of the branches of the ,amazon--indeed1 on the flanks of ,cotopaxi1 ,chimborazo1 and ,illinissa there are some glaciers in close proximity to the equator which are fairly comparable in size to those of the ,alps4 ,in ,chili1 at about latitude #ce1 glaciers begin to appear at lower levels1 descending beyond the six-thousand-foot line1 while south of this both the increasing moisture of the winds and the decreasing average temperature favour the increase of ice-fields and glaciers4 ,consequently1 as ,darwin long ago observed1 the line of perpetual snow here descends to an increasingly lower level1 and glaciers extend down farther and farther towards the sea1 until1 in ,tierra del ,fuego1 at about latitude #de1 they begin to discharge their frozen contents directly into the tidal inlets4 ,darwin's party surveyed a glacier entering the ,gulf of ,penas in latitude #df #ej'1 which was fifteen miles long1 and1 in one part1 seven broad4 ,at ,eyre's ,sound1 also1 in about latitude #dh1 they found immense glaciers coming clown to the sea and discharging icebergs of great size1 one of which1 as they encountered it floating outwards1 was estimated to be at least one hundred and sixty-eight feet in total height4 ,in ,tierra del ,fuego1 where the mountains are only from three thousand to four thousand feet in height and in latitude less than #ee1 ,darwin reports that every valley is filled with streams of ice descending to the sea-coast1 and that the inlets penetrated by his party presented miniature likenesses of the polar sea4 ,illustration3 ,fig4 #i4--;,floating berg1 showing the proportions above and under the water4 ,about seven feet under water to one above4 ,antarctic ,continent4--,of the so-called ,antarctic ,continent little is known2 but icebergs of great size are frequently encountered up to #eh south latitude1 in the direction of ,cape ,horn1 and as far as latitude #cc in the direction of ,cape of ,good ,hope4 ,nearly all that is known about this continent was discovered by ,sir ,j4 ,c4 ,ross during the period extending from #ahci to #ahdc1 when1 between the parallels of #gj and #gh south latitude1 he encountered in his explorations a precipitous mountain coast1 rising from seven thousand to ten thousand feet above tide4 ,through the valleys intervening between the mountain-ranges huge glaciers descended1 and projected in many places several miles into the sea and terminated in lofty1 perpendicular cliffs4 ,in a few places the rocks broke through their icy covering1 by which alone we could be assured that land formed the nucleus of this1 to appearance1 enormous iceberg4,,ag ,footnote ,,ag3 ,quoted by ,whitney in ,climatic ,changes1 p4 #cad4 ,again1 speaking of the region in the vicinity of the lofty volcanoes ,terror and ,erebus1 between ten thousand and twelve thousand feet high1 the same navigator says3 ,we perceived a low1 white line extending from its extreme eastern point1 as far as the eye could discern1 to the eastward4 ,it presented an extraordinary appearance1 gradually increasing in height as we got nearer to it1 and proving at length to be a perpendicular cliff of ice1 between one hundred and fifty and two hundred feet above the level of the sea1 perfectly flat and level at the top1 and without any fissures or promontories on its even1 seaward face4 ,what was beyond it we could not imagine2 for1 being much higher than our mast-head1 we could not see anything except the summit of a lofty range of mountains extending to the southward as far as the seventy-ninth degree of latitude4 ,these mountains1 being the southernmost land hitherto discovered1 ,i felt great satisfaction in naming after ,sir ,edward ,parry4444 ,whether ,parry ,mountains again take an easterly trending and form the base to which this extraordinary mass of ice is attached1 must be left for future navigators to determine4 ,if there be land to the southward it must be very remote1 or of much less elevation than any other part of the coast we have seen1 or it would have appeared above the barrier4 ,this ice-cliff or barrier was followed by ,captain ,ross as far as #aih west longitude1 and found to preserve very much the same character during the whole of that distance4 ,on the lithographic view of this great ice-sheet given in ,ross's work it is described as part of the ,south ,polar ,barrier1 one hundred and eighty feet above the sea-level1 one thousand feet thick1 and four hundred and fifty miles in length4 ,a similar vertical wall of ice was seen by ,d',urville1 off the coast of ,adelie ,land4 ,he thus describes it3 ,its appearance was astonishing4 ,we perceived a cliff having a uniform elevation of from one hundred to one hundred and fifty feet1 forming a long line extending off to the west4444 ,thus for more than twelve hours we had followed this wall of ice1 and found its sides everywhere perfectly vertical and its summit horizontal4 ,not the smallest irregularity1 not the most inconsiderable elevation1 broke its uniformity for the twenty leagues of distance which we followed it during the day1 although we passed it occasionally at a distance of only two or three miles1 so that we could make out with ease its smallest irregularities4 ,some large pieces of ice were lying along the side of this frozen coast2 but1 on the whole1 there was open sea in the offing4 ,,ah ,footnote ,,ah3 ,whitney's ,climatic ,changes1 pp4 #cae1 #caf4 ,illustration3 ,fig4 #aj4--;,iceberg in the ,antarctic ,ocean4 ,north ,america4--,in ,north ,america living glaciers begin to appear in the ,sierra ,nevada ,mountains1 in the vicinity of the ,yosemite ,park1 in central ,california4 ,here the conditions necessary for the production of glaciers are favourable1 namely1 a high altitude1 snow-fields of considerable extent1 and unobstructed exposure to the moisture-laden currents of air from the ,pacific ,ocean4 ,sixteen glaciers of small size have been noted among the summits to the east of the ,yosemite2 but none of them descend much below the eleven-thousand-foot line1 and none of them are over a mile in length4 ,indeed1 they are so small1 and their motion is so slight1 that it is a question whether or not they are to be classed with true glaciers4 ,owing to the comparatively low elevation of the ,sierra ,nevada north of ,tuolumne ,county1 ,california1 no other living glaciers are found until reaching ,mount ,shasta1 in the extreme northern part of the ,state4 ,this is a volcanic peak1 rising fourteen thousand five hundred feet above the sea1 and having no peaks within forty miles of it as high as ten thousand feet2 yet so abundant is the snow-fall that as many as five glaciers are found upon its northern side1 some of them being as much as three miles long and extending as low down as the eight-thousand-foot level4 ,upon the southern side glaciers are so completely absent that ,professor ,whitney ascended the mountain and remained in perfect ignorance of its glacial system4 ,in #ahgj ,mr4 ,clarence ,king first discovered and described them on the northern side4 ,north of ,california glaciers characterise the ,cascade ,range in increasing numbers all the way to the ,alaskan ,peninsula4 ,they are to be found upon ,diamond ,peak1 the ,three ,sisters1 ,mount ,jefferson1 and ,mount ,hood1 in ,oregon1 and appear in still larger proportions upon the flanks of ,mount ,rainier 7or ,tacoma7 and ,mount ,baker1 in the ,state of ,washington4 ,the glacier at the head of the ,white ,river ,valley is upon the north side of ,rainier1 and is the largest one upon that mountain1 reaching down to within five thousand feet of the sea-level1 and being ten miles or more in length4 ,all the streams which descend the valleys upon this mountain are charged with the milky-coloured water which betrays their glacial origin4 ,illustration3 ,fig4 #aa4--,map of ,southeastern ,alaska4 ,the arrow-points mark glaciers4 ,in ,british ,columbia1 ,glacier ,station1 upon the ,canadian ,pacific ,railroad1 in the ,selkirk ,mountains1 is within half a mile of the handsome ,illicilliwaet ,glacier1 while others of larger size are found at no great distance4 ,the interior farther north is unexplored to so great an extent that little can be definitely said concerning its glacial phenomena4 ,the coast of ,british ,columbia is penetrated by numerous fiords1 each of which receives the drainage of a decaying glacier2 but none are in sight of the tourist-steamers which thread their way through the intricate network of channels characterising this coast1 until the ,alaskan boundary is crossed and the mouth of the ,stickeen ,river is passed4 ,a few miles up from the mouth of the ,stickeen1 however1 glaciers of large size come down to the vicinity of the river1 both from the north and from the south1 and the attention of tourists is always attracted by the abundant glacial sediment borne into the tide-water by the river itself and discolouring the surface for a long distance beyond the outlet4 ,northward from this point the tourist is rarely out of sight of ice-fields4 ,the ,auk and ,patterson ,glaciers are the first to come into view1 but they do not descend to the water-level4 ,on nearing ,holcomb ,bay1 however1 small icebergs begin to appear1 heralding the first of the glaciers which descend beyond the water's edge4 ,taku ,inlet1 a little farther north1 presents glaciers of great size coming down to the sea-level1 while the whole length of ,lynn ,canal1 from ,juneau to ,chilkat1 a distance of eighty miles1 is dotted on both sides by conspicuous glaciers and ice-fields4 ,the ,davidson ,glacier1 near the head of the canal1 is one of the most interesting for purposes of study4 ,it comes down from an unknown distance in the western interior1 bearing two marked medial moraines upon its surface4 ,on nearing tide-level1 the valley through which it flows is about three-quarters of a mile in width2 but1 after emerging from the confinement of the valley1 the ice spreads out over a fan-shaped area until the width of its front is nearly three miles4 ,the supply of ice not being sufficient to push the front of the glacier into deep water1 equilibrium between the forces of heat and cold is established near the water's edge4 ,here1 as from year to year the ice melts and deposits its burdens of earthy dbris1 it has piled up a terminal moraine which rises from two hundred to three hundred feet in height1 and is now covered with evergreen trees of considerable size4 ,from ,chilkat1 at the head of ,lynn ,canal1 to the sources of the ,yukon ,river1 the distance is only thirty-five miles1 but the intervening mountain-chain is several thousand feet in height and bears numerous glaciers upon its seaward side4 ,about forty miles west of ,lynn ,canal1 and separated from it by a range of mountains of moderate height1 is ,glacier ,bay1 at the head of one of whose inlets is the ,muir ,glacier1 which forms the chief attraction for the great number of tourists that now visit the coast of southeastern ,alaska during the summer season4 ,this glacier meets tide-water in latitude #eh #ej'1 and longitude #acf #dj' west of ,greenwich4 ,it received its name from ,mr4 ,john ,muir1 who1 in company with ,rev4 ,mr4 ,young1 made a tour of the bay and discovered the glacier in #ahgi4 ,it was soon found that the bay could be safely navigated by vessels of large size1 and from that time on tourists in increasing number have been attracted to the region4 ,commodious steamers now regularly run close up to the ice-front1 and lie-to for several hours1 so that the passengers may witness the calving of icebergs1 and may climb upon the sides of the icy stream and look into its deep crevasses and out upon its corrugated and broken surface4 ,illustration3 ,fig4 #ab4--,map of ,glacier ,bay4 ,alaska1 and its surroundings4 ,arrow-points indicate glaciated area4 ,the first persons who found it in their way to pay more than a tourist's visit to this interesting object were ,rev4 ,j4 ,l4 ,patton1 ,mr4 ,prentiss ,baldwin1 and myself1 who spent the entire month of ,august1 #ahhf1 encamped at the foot of the glacier1 conducting such observations upon it as weather and equipment permitted4 ,from that time till the summer of #ahij no one else stopped off from the tourist steamers to bestow any special study upon it4 ,but during this latter season ,mr4 ,muir returned to the scene of his discovered wonder1 and spent some weeks in exploring the interior of the great ice-field4 ,during the same season1 also1 ,professors ,h4 ,f4 ,reid and ,h4 ,cushing1 with a well-equipped party of young men1 spent two months or more in the same field1 conducting observations and experiments1 of various kinds1 relating to the extent1 the motion1 and the general behaviour of the vast mass of moving ice4 ,illustration3 ,fig4 #ac4--,shows central part of the front of ,muir ,glacier one half mile distant4 ,near the lower left hand corner the ice is seen one mile distant resting for about one half mile on gravel which it had overrun4 ,the ice is now retreating in the channel4 7,from photograph47 ,the main body of the ,muir ,glacier occupies a vast amphitheatre1 with diameters ranging from thirty to forty miles1 and covers an area of about one thousand square miles4 ,from one of the low mountains near its mouth ,i could count twenty-six tributary glaciers which came together and became confluent in the main stream of ice4 ,nine medial moraines marked the continued course of as many main branches1 which becoming united formed the grand trunk of the glacier4 ,numerous rocky eminences also projected above the surface of the ice1 like islands in the sea1 corresponding to what are called nunataks in ,greenland4 ,the force of the ice against the upper side of these rocky prominences is such as to push it in great masses above the surrounding level1 after the analogy of waves which dash themselves into foam against similar obstructions4 ,in front of the nunataks there is uniformly a depression1 like the eddies which appear in the current below obstacles in running water4 ,over some portions of the surface of the glacier there is a miniature river system1 consisting of a main stream1 with numerous tributaries1 but all flowing in channels of deep blue ice4 ,before reaching the front of the glacier1 however1 each one of these plunges down into a crevasse1 or moulin1 to swell the larger current1 which may be heard rushing along in an impetuous course hundreds of feet beneath1 and far out of sight4 ,the portion of the glacier in which there is the most rapid motion is characterised by innumerable crags and domes and pinnacles of ice1 projecting above the general level1 whose bases are separated by fissures1 extending in many cases more than a hundred feet below the general level4 ,these irregularities result from the combined effect of the differential motion 7as illustrated in the diagram on page #d71 and the influence of sunshine and warm air in irregularly melting the unprotected masses4 ,the description given in our introductory chapter of medial moraines and ice-pillars is amply illustrated everywhere upon the surface of the ,muir ,glacier4 ,i measured one block of stone which was twenty feet square and about the same height1 standing on a pedestal of ice three or four feet high4 ,the mountains forming the periphery of this amphitheatre rise to a height of several thousand feet2 ,mount ,fairweather1 upon the northwest1 from whose flanks probably a portion of the ice comes1 being1 in fact1 more than fifteen thousand feet high4 ,the mouth of the amphitheatre is three miles wide1 in a line extending from shoulder to shoulder of the low mountains which guard it4 ,the actual water-front where the ice meets tide-water is one mile and a half4,,ai ,here the depth of the inlet is so great that the front of the ice breaks off in icebergs of large size1 which float away to be dissolved at their leisure4 ,at the water's edge the ice presents a perpendicular front of from two hundred and fifty to four hundred feet in height1 and the depth of the water in the middle of the inlet immediately in front of the ice is upwards of seven hundred feet2 thus giving a total height to the precipitous front of a thousand feet4 ,footnote ,,ai3 ,these are the measurements of ,professor ,reid4 ,in my former volume ,i have given the dimensions as somewhat smaller4 ,the formation of icebergs can here be studied to admirable advantage4 ,during the month in which we encamped in the vicinity the process was going on continuously4 ,there was scarcely an interval of fifteen minutes during the whole time in which the air was not rent with the significant boom connected with the calving of a berg4 ,sometimes this was occasioned by the separation of a comparatively small mass of ice from near the top of the precipitous wall1 which would fall into the water below with a loud splash4 ,at other times ,i have seen a column of ice from top to bottom of the precipice split off and fall over into the water1 giving rise to great waves1 which would lash the shore with foam two miles below4 ,this manner of the production of icebergs differs from that which has been ordinarily represented in the text-books1 but it conforms to the law of glacial motion1 which we will describe a little later1 namely1 that the upper strata of ice move faster than the lower4 ,hence the tendency is constantly to push the upper strata forwards1 so as to produce a perpendicular or even projecting front1 after the analogy of the formation of breakers on the shelving shore of a large body of water4 ,evidently1 however1 these masses of ice which break off from above the water do not reach the whole distance to the bottom of the glacier below the water2 so that a projecting foot of ice remains extending to an indefinite distance underneath the surface4 ,but at occasional intervals1 as the superincumbent masses of ice above the surface fall off and relieve the strata below of their weight1 these submerged masses suddenly rise1 often shooting up considerably higher than they ultimately remain when coming to rest4 ,the bergs formed by this latter process often bear much earthy material upon them1 which is carried away with the floating ice1 to be deposited finally wherever the melting chances to take place4 ,numerous opportunities are furnished about the front and foot of this vast glacier to observe the manner of the formation of kames1 kettle-holes1 and various other irregular forms into which glacial dbris is accustomed to accumulate4 ,over portions of the decaying foot of the glacier1 which was deeply covered with morainic dbris1 the supporting ice is being gradually removed through the influence of subglacial streams or of abandoned tunnels1 which permit the air to exert its melting power underneath4 ,in some places where old moulins had existed1 the supporting ice is melting away1 so that the superincumbent mass of sand1 gravel1 and boulders is slowly sliding into a common centre1 like grain in a hopper4 ,this must produce a conical hill1 to remain1 after the ice has all melted away1 a mute witness of the impressive and complicated forces which have been so long in operation for its production4 ,in other places ,i have witnessed the formation of a long ridge of gravel by the gradual falling in of the roof of a tunnel which had been occupied by a subglacial stream1 and over which there was deposited a great amount of morainic material4 ,as the roof gave way1 this was constantly falling to the bottom1 where1 being exempt from further erosive agencies1 it must remain as a gravel ridge or kame4 ,in other places1 still1 there were vast masses of ice covering many acres1 and buried beneath a great depth of morainic material which had been swept down upon it while joined to the main glacier4 ,in the retreat of the ice1 however1 these masses had become isolated1 and the sand1 gravel1 and boulders were sliding down the wasting sides and forming long ridges of dbris along the bottom1 which1 upon the final melting of the ice1 will be left as a complicated network of ridges and knolls of gravel1 enclosing an equally complicated nest of kettle-holes4 ,beyond ,cross ,sound the ,pacific coast is bounded for several hundred miles by the magnificent semicircle of mountains known as the ,st4 ,elias ,alps1 with ,mount ,crillon at the south1 having an elevation of nearly sixteen thousand feet1 and ,st4 ,elias in the centre1 rising to a greater height4 ,everywhere along this coast1 as far as the ,alaskan ,peninsula1 vast glaciers come down from the mountain-sides1 and in many cases their precipitous fronts form the shore-line for many miles at a time4 ,icy ,bay1 just to the south of ,mount ,st1 ,elias1 is fitly named1 on account of the extent of the glaciers emptying into it and the number of icebergs cumbering its waters4 ,in the summer of #ahij a party1 under the lead of ,mr4 ,i4 ,c4 ,russell1 of the ,united ,states ,geological ,survey1 made an unsuccessful attempt to scale the heights of ,mount ,st4 ,elias2 but the information brought back by them concerning the glaciers of the region amply repaid them for their toil and expense1 and consoled them for the failure of their immediate object4 ,illustration3 ,fig4 #ad4--;,by the courtesy of the ,national ,geographical ,society4 ,leaving ,yakutat ,bay1 and following the route indicated upon the accompanying map1 they travelled on glacial ice almost the entire distance to the foot of ,mount ,st4 ,elias4 ,the numerous glaciers coming down from the summit of the mountain-ridge become confluent nearer the shore1 and spread out over an area of about a thousand square miles4 ,this is fitly named the ,malaspina ,glacier1 after the ,spanish explorer who discovered it in #agib4 ,it is not necessary to add further particulars concerning the results of this expedition1 since they are so similar to those already detailed in connection with the ,muir ,glacier4 ,a feature1 however1 of special interest1 pertains to the glacial lakes which are held in place by the glacial ice at an elevation of thousands of feet above the sea4 ,one of considerable size is indicated upon the map just south of what was called ,blossom ,island1 which1 however1 is not an island1 but simply a nunatak1 the ice here surrounding a considerable area of fertile land1 which is covered with dense forests and beautified by a brilliant assemblage of flowering plants4 ,in other places considerable vegetation was found upon the surface of moraines1 which were probably still in motion with the underlying ice4 ,greenland4--,the continental proportions of ,greenland1 and the extent to which its area is covered by glacial ice1 make it by far the most important accessible field for glacial observations4 ,the total area of ,greenland can not be less than five hundred thousand square miles--equal in extent to the portion of the ,united ,states east of the ,mississippi and north of the ,ohio4 ,it is now pretty evident that the whole of this area1 except a narrow border about the southern end1 is covered by one continuous sheet of moving ice1 pressing outward on every side towards the open water of the surrounding seas4 ,for a long time it was the belief of many that a large region in the interior of ,greenland was free from ice1 and was perhaps inhabited4 ,it was in part to solve this problem that ,baron ,nordenskild set out upon his expedition of #ahhc4 ,ascending the ice-sheet from ,disco ,bay1 in latitude #fi1 he proceeded eastward for eighteen days across a continuous ice-field4 ,rivers were flowing in channels upon the surface like those cut on land in horizontal strata of shale or sandstone1 only that the pure deep blue of the ice-walls was1 by comparison1 infinitely more beautiful4 ,these rivers were not1 however1 perfectly continuous4 ,after flowing for a distance in channels on the surface1 they1 one and all1 plunged with deafening roar into some yawning crevasse1 to find their way to the sea through subglacial channels4 ,numerous lakes with shores of ice were also encountered4 ,illustration3 ,fig4 #ae4--,map of ,greenland4 ,the arrow-points mark the margin of the ice-field4 ,on bending down the ear to the ice1 says this explorer1 we could hear on every side a peculiar subterranean hum1 proceeding from rivers flowing within the ice2 and occasionally a loud1 single report1 like that of a cannon1 gave notice of the formation of a new glacier-cleft4444 ,in the afternoon we saw at some distance from us a well-defined pillar of mist1 which1 when we approached it1 appeared to rise from a bottomless abyss1 into which a mighty glacier-river fell4 ,the vast1 roaring water-mass had bored for itself a vertical hole1 probably down to the rock1 certainly more than two thousand feet beneath1 on which the glacier rested4,,aj ,footnote ,,aj3 ,geological ,magazine1 vol4 ix1 pp4 #cic1 #cii4 ,at the end of the eighteen days ,nordenskild found himself about a hundred and fifty miles from his starting-point1 and about five thousand feet above the sea4 ,here the party rested1 and sent two ,eskimos forward on skidor--a kind of long wooden skate1 with which they could move rapidly over the ice1 notwithstanding the numerous small1 circular holes which everywhere pitted the surface4 ,these ,eskimos were gone fifty-seven hours1 having slept only four hours of the period4 ,it is estimated that they made about a hundred and fifty miles1 and attained an altitude of six thousand feet4 ,the ice is reported as rising in distinct terraces1 and as seemingly boundless beyond4 ,if this is the case1 two hundred miles from ,disco ,bay1 there would seem little hope of finding in ,greenland an interior freed from ice4 ,so we may pretty confidently speak of that continental body of land as still enveloped in an ice-sheet4 ,up to about latitude #ge1 however1 the continent is fringed by a border of islands1 over which there is no continuous covering of ice4 ,in south ,greenland the continuous ice-sheet is reached about thirty miles back from the shore4 ,a summary of the results of ,greenland exploration was given by ,dr4 ,kink in #ahhf1 from which it appears that since #ahgf one thousand miles of the coast-line have been carefully explored by entering every fiord and attempting to reach the inland ice4 ,according to this authority-- ,we are now able to demonstrate that a movement of ice from the central regions of ,greenland to the coast continually goes on1 and must be supposed to act upon the ground over which it is pushed so as to detach and transport fragments of it for such a distance4444 ,the plainest idea of the ice-formation here in question is given by comparing it with an inundation4444 ,only the marginal parts show irregularity2 towards the interior the surface grows more and more level and passes into a plain very slightly rising in the same direction4 ,it has been proved that1 ascending its extreme verge1 where it has spread like a lava-stream over the lower ground in front of it1 the irregularities are chiefly met with up to a height of #b1jjj feet1 but the distance from the margin in which the height is reached varies much4 ,while under #fh-a_/b north latitude it took twenty-four miles before this elevation was attained1 in #gb-a_/b the same height was arrived at in half the distance4444 ,a general movement of the whole mass from the central regions towards the sea is still continued1 but it concentrates its force to comparatively few points in the most extraordinary degree4 ,these points are represented by the ice-fiords1 through which the annual surplus ice is carried off in the shape of bergs4444 ,in ,danish ,greenland are found five of the first1 four of the second1 and eight of the third 7or least productive7 class1 besides a number of inlets which only receive insignificant fragments4 ,direct measurements of the velocity have now been applied on three first-rate and one second-rate fiords1 all situated between #fi and #ga north latitude4 ,the measurements have been repeated during the coldest and the warmest season1 and connected with surveying and other investigations of the inlets and their environs4 ,it is now proved that the glacier branches which produce the bergs proceed incessantly at a rate of thirty to fifty feet per diem1 this movement being not at all influenced by the seasons4 4 4 4 ,in the ice-fiord of ,jakobshavn1 which spreads its enormous bergs over ,disco ,bay and probably far into the ,atlantic1 the productive part of the glacier is #d1ejj metres 7about #b-a_/b miles7 broad4 ,the movement along its middle line1 which is quicker than on the sides nearer the shores1 can be rated at fifty feet per diem4 ,the bulk of ice here annually forced into the sea would1 if taken on the shore1 make a mountain two miles long1 two miles broad1 and #a1jjj feet high4 ,the ice-fiord of ,torsukatak receives four or five branches of the glacier2 the most productive of them is about #i1jjj metres broad 7five miles71 and moves between sixteen and thirty-two feet per diem4 ,the large ,karajak ,glacier1 about #g1jjj metres 7four miles7 broad1 proceeds at a rate of from twenty-two to thirty-eight feet per diem4 ,finally1 a glacier branch dipping into the fiord of ,jtivdliarsuk1 #e1hjj metres broad 7three miles71 moved between twenty-four and forty-six feet per diem4,,ak ,footnote ,,ak3 ,see ,transactions of the ,edinburgh ,geological ,society for ,february #ah1 #ahhf1 vol4 v1 part ii1 pp4 #bhf-bic4 ,the principal part of our information concerning the glaciers of ,greenland north of ,melville ,bay was obtained by ,drs4 ,kane and ,hayes1 in #ahec and #ahed1 while conducting an expedition in search of ,sir ,john ,franklin and his unfortunate crew4 ,dr4 ,hayes conducted another expedition to the same desolate region in #ahfj1 while other explorers have to some extent supplemented their observations4 ,the largest glacier which they saw enters the sea between latitude #gi and #hj1 where it presents a precipitous discharging front more than sixty miles in width and hundreds of feet in perpendicular height4 ,dr4 ,kane gives his first impressions of this grand glacier in the following vivid description3 ,i will not attempt to do better by florid description4 ,men only rhapsodize about ,niagara and the ocean4 ,my notes speak simply of the 'long1 ever-shining line of cliff diminished to a well-pointed wedge in the perspective'2 and1 again1 of 'the face of glistening ice1 sweeping in a long curve from the low interior1 the facets in front intensely illuminated by the sun4' ,but this line of cliff rose in a solid1 glassy wall three hundred feet above the water-level1 with an unknown1 unfathomable depth below it2 and its curved face1 sixty miles in length from ,cape ,agassiz to ,cape ,forbes1 vanished into unknown space at not more than a single day's railroad-travel from the pole4 ,the interior1 with which it communicated and from which it issued1 was an unsurveyed mer de glace--an ice-ocean to the eye1 of boundless dimensions4 ,it was in full sight--the mighty crystal bridge which connects the two continents of ,america and ,greenland4 ,i say continents1 for ,greenland1 however insulated it may ultimately prove to be1 is in mass strictly continental4 ,its least possible axis1 measured from ,cape ,farewell to the line of this glacier1 in the neighbourhood of the eightieth parallel1 gives a length of more than #a1bjj miles1 not materially less than that of ,australia from its northern to its southern cape4 ,imagine1 now1 the centre of such a continent1 occupied through nearly its whole extent by a deep1 unbroken sea of ice that gathers perennial increase from the water-shed of vast snow-covered mountains and all the precipitations of its atmosphere upon its own surface4 ,imagine this1 moving onwards like a great glacial river1 seeking outlets at every fiord and valley1 rolling icy cataracts into the ,atlantic and ,greenland seas2 and1 having at last reached the northern limit of the land that has borne it up1 pouring out a mighty frozen torrent into unknown arctic space6 ,it is thus1 and only thus1 that we must form a just conception of a phenomenon like this great glacier4 ,i had looked in my own mind for such an appearance1 should ,i ever be fortunate enough to reach the northern coast of ,greenland2 but1 now that it was before me1 ,i could hardly realize it4 ,i had recognized1 in my quiet library at home1 the beautiful analogies which ,forbes and ,studer have developed between the glacier and the river4 ,but ,i could not comprehend at first this complete substitution of ice for water4 ,it was slowly that the conviction dawned on me that ,i was looking upon the counterpart of the great river-system of ,arctic ,asia and ,america4 ,yet here were no water-feeders from the south4 ,every particle of moisture had its origin within the polar circle and had been converted into ice4 ,there were no vast alluvions1 no forest or animal traces borne down by liquid torrents4 ,here was a plastic1 moving1 semi-solid mass1 obliterating life1 swallowing rocks and islands1 and ploughing its way with irresistible march through the crust of an investing sea4,,al ,footnote ,,al3 ,arctic ,explorations in the ,years #ahec1 #ahed1 and #ahee1 vol4 i1 pp4 #bbe-bbh4 ,much less is known concerning the eastern coast of ,greenland than about the western coast4 ,for a long time it was supposed that there might be a considerable population in the lower latitudes along the eastern side4 ,but that is now proved to be a mistake4 ,the whole coast is very inhospitable and difficult of approach4 ,from latitude #fe to latitude #fi little or nothing is known of it4 ,in #ahbb-'bc ,scoresby1 ,cleavering1 and ,sabine hastily explored the coast from latitude #fi to #gf1 and reported numerous glaciers descending to the sea-level through extensive fiords1 from which immense icebergs float out and render navigation dangerous4 ,in #ahfi and #ahgj the second ,north-,german ,expedition partly explored the coast between latitude #gc and #gg4 ,mr4 ,payer1 an experienced ,alpine explorer1 who accompanied the expedition1 reports the country as much broken1 and the glaciers as subordinated in position to the higher peaks1 and having their moraines1 both lateral and terminal1 like those of the ,alpine ranges1 and on a still grander scale4 ,petermann ,peak1 in latitude #gc1 is reported as #ac1jjj feet high4 ,captain ,koldewey1 chief of the expedition1 found extensive plateaus on the mainland1 in latitude #ge1 to be entirely clear of snow1 although only sparsely covered with vegetation4 ,the mountains in this vicinity1 also1 rising to a height of more than #b1jjj feet1 were free from snow in the summer4 ,some of the fiords in this vicinity penetrate the continent through several degrees of longitude4 ,an interesting episode of this expedition was the experience of the crew of the ship ,hansa1 which was caught in the ice and destroyed4 ,the crew1 however1 escaped by encamping on the ice-floe which had crushed the ship4 ,from this1 as it slowly floated towards the south through several degrees of latitude1 they had opportunity to make many important observations upon the continent itself4 ,as viewed from this unique position the coast had the appearance everywhere of being precipitous1 with mountains of considerable height rising in the background1 from which numerous small glaciers descended to the sea-level4 ,in #ahhh ,dr4 ,f4 ,nansen1 with ,lieutenant ,sverdrup and four others1 was left by a whaler on the ice-pack bordering the east of ,greenland about latitude #fe1 and in sight of the coast4 ,for twelve days the party was on the ice-pack floating south1 and so actually reached the coast only about latitude #fd4 ,from this point they attempted to cross the inland ice in a northwesterly direction towards ,christianshaab4 ,they soon reached a height of #g1jjj feet1 and were compelled by severe northerly storms to diverge from their course1 taking a direction more to the west4 ,the greatest height attained was #i1ejj feet1 and the party arrived on the western coast at ,ameralik ,fiord1 a little south of ,godhaab1 about the same latitude at which they entered4 ,it thus appears that subsequent investigations have confirmed in a remarkable manner the sagacious conclusions made by the eminent ,scotch geologist and glacialist ,robert ,brown in #ahge1 soon after his own expedition to the country4 ,i look upon ,greenland and its interior ice-field1 he writes1 in the light of a broad-lipped1 shallow vessel1 but with chinks in the lips here and there1 and the glacier like viscous matter in it4 ,as more is poured in1 the viscous matter will run over the edges1 naturally taking the line of the chinks as its line of outflow4 ,the broad lips of the vessel are the outlying islands or 'outskirts'2 the viscous matter in the vessel the inland ice1 the additional matter continually being poured in in the form of the enormous snow covering1 which1 winter after winter1 for seven or eight months in the year1 falls almost continuously on it2 the chinks are the fiords or valleys down which the glaciers1 representing the outflowing viscous matter1 empty the surplus of the vessel--in other words1 the ice floats out in glaciers1 overflows the land in fact1 down the valleys and fiords of ,greenland by force of the superincumbent weight of snow1 just as does the grain on the floor of a barn 7as admirably described by ,mr4 ,jamieson7 when another sackful is emptied on the top of the mound already on the floor4 ',the floor is flat1 and therefore does not conduct the grain in any direction2 the outward motion is due to the pressure of the particles of grain on one another2 and1 given a floor of infinite extension and a pile of sufficient amount1 the mass would move outward to any distance1 and with a very slight pitch or slope it would slide forward along the incline4' ,to this let me add that if the floor on the margin of the heap of grain was undulating the stream of grain would take the course of such undulations4 ,the want1 therefore1 of much slope in a country and the absence of any great mountain-range are of very little moment to the movement of land-ice1 provided we have snow enough ,on another page ,dr4 ,brown had well said that the country seems only a circlet of islands separated from one another by deep fiords or straits1 and bound together on the landward side by the great ice covering which overlies the whole interior4444 ,no doubt under this ice there lies land1 just as it lies under the sea2 but nowadays none can be seen1 and as an insulating medium it might as well be water4 ,in his recently published volumes descriptive of the journey across the ,greenland ice-sheet1 alluded to on page #ci1 ,dr4 ,nansen sums up his inferences in very much the same way3 ,the ice-sheet rises comparatively abruptly from the sea on both sides1 but more especially on the east coast1 while its central portion is tolerably flat4 ,on the whole1 the gradient decreases the farther one gets into the interior1 and the mass thus presents the form of a shield with a surface corrugated by gentle1 almost imperceptible1 undulations lying more or less north and south1 and with its highest point not placed symmetrically1 but very decidedly nearer the east coast than the west4 ,from this rapid glance at the existing glaciers of the world we see that a great ice age is not altogether a strange thing in the world4 ,the lands about the south pole and ,greenland are each continental in dimensions1 and present at the present time accumulations of land-ice so extensive1 so deep1 and so alive with motion as to prepare our minds for almost anything that may be suggested concerning the glaciated condition of other portions of the earth's surface4 ,the vera causa is sufficient to accomplish anything of which glacialists have ever dreamed4 ,it only remains to enquire what the facts really are and over how great an extent of territory the actual results of glacial action may be found4 ,but we will first direct more particular attention to some of the facts and theories concerning glacial motion4 ,,chapter ,,iii4 ,,glacial ,,motion4 ,that glacial ice actually moves after the analogy of a semi-fluid has been abundantly demonstrated by observation4 ,in the year #ahbg ,professor ,hugi1 of ,soleure1 built a hut far up upon the ,aar ,glacier in ,switzerland1 in order to determine the rate of its motion4 ,after three years he found that it had moved #ccj feet2 after nine years1 #b1ced feet2 and after fourteen years ,louis ,agassiz found that its motion had been #d1gab feet4 ,in #ahda ,agassiz began a more accurate series of observation upon the same glacier4 ,boring holes in the ice1 he set across it a row of stakes which1 on visiting in #ahdb1 he found to be no longer in a straight line4 ,all had moved downwards with varying velocity1 those near the centre having moved farther than the others4 ,the displacements of the stakes were in order1 from side to side1 as follows3 #afj feet1 #bbe feet1 #bfi feet1 #bde feet1 #baj feet1 and #abe feet4 ,agassiz followed up his observations for six years1 and in #ahdg published the results in his celebrated work ,system ,glacire4 ,illustration3 ,fig4 #af4 ,but in ,august1 #ahda1 the distinguished ,swiss investigator had invited ,professor ,j4 ,d4 ,forbes1 of ,edinburgh1 to interest himself in solving the problem of glacial motion4 ,in response to this request1 ,professor ,forbes spent three weeks with ,agassiz upon the ,aar ,glacier4 ,stimulated by the interest of this visit1 ,forbes returned to ,switzerland in #ahdb and began a series of independent investigations upon the ,mer de ,glace4 ,after a week's observations with accurate instruments1 ,forbes wrote to ,professor ,jameson1 editor of the ,edinburgh ,new ,philosophical ,journal1 that he had already made it certain that the central part of the glacier moves faster than the edges in a very considerable proportion1 quite contrary to the opinion generally maintained4 ,this letter was dated ,july #d1 #ahdb1 but was not published until the ,october following1 ,agassiz's results1 so far as then determined1 were1 however1 published in ,comptes ,rendus of the #bith of ,august1 #ahdb1 two months before the publication of ,forbes's letter4 ,but ,agassiz's letter was dated twenty-seven days later than that of ,forbes4 ,it becomes certain1 therefore1 that both ,agassiz and ,forbes1 independently and about the same time1 discovered the fact that the central portion of a glacier moves more rapidly than the sides4 ,in #aheg ,professor ,tyndall began his systematic and fruitful observations upon the ,mer de ,glace and other ,alpine glaciers4 ,professor ,forbes had already demonstrated that1 with an accurate instrument of observation1 the motion of a line of stakes might be observed after the lapse of a single clay1 or even of a few hours4 ,as a result of ,tyndall's observations1 it was found that the most rapid daily motion in the ,mer de ,glace in #aheg was about thirty-seven inches4 ,this amount of motion was near the lower end of the glacier ,on ascending the glacier1 the rate was found in general to be diminished2 but the diminution was not uniform throughout the whole distance1 being affected both by the size and by the contour of the valley4 ,the motion in the tributary glaciers was also much less than that of the main glacier4 ,this diminution of movement in the tributary glaciers was somewhat proportionate to their increase in width4 ,for example1 the combined width of the three tributaries uniting to form the ,mer de ,glace is #b1eig yards2 but a short distance below the junction of these tributaries the total width of the ,mer de ,glace itself is only #hic yards1 or one-third that of the tributaries combined4 ,yet1 though the depth of the ice is probably here much greater than in the tributaries1 the rapidity of movement is between two and three times as great as that of any one of the branches4,,am ,footnote ,,am3 ,see ,tyndall's ,forms of ,water1 pp4 #gh-hb4 ,from ,tyndall's observations it appears also that the line of most rapid motion is not exactly in the middle of the channel1 but is pushed by its own momentum from one side to the other of the middle1 so as always to be nearer the concave side2 in this respect conforming1 as far as its nature will permit1 to the motion of water in a tortuous channel4 ,illustration3 ,fig4 #ag4 ,it is easy to account for this differential motion upon the surface of a glacier1 since it is clear that the friction of the sides of the channel must retard the motion of ice as it does that of water4 ,it is clear also that the friction of the bottom must retard the motion of ice even more than it is known to do in the case of water4 ,in the formation of breakers1 when the waves roll in upon a shallowing beach1 every one is familiar with the effect of the bottom upon the moving mass4 ,here friction retards the lower strata of water1 and the upper strata slide over the lower1 and1 where the water is of sufficient depth and the motion is sufficiently great1 the crest breaks down in foam before the ever-advancing tide4 ,a similar phenomenon occurs when dams give way and reservoirs suddenly pour their contents into the restricted channels below4 ,at such times the advancing water rolls onwards like the surf with a perpendicular front1 varying in height according to the extent of the flood4 ,seasoning from these phenomena connected with moving water1 it was naturally suggested to ,professor ,tyndall that an analogous movement must take place in a glacier4 ,choosing1 therefore1 a favourable place for observation on the ,mer de ,glace where the ice emerged from a gorge1 he found a perpendicular side about one hundred and fifty feet in height from bottom to top4 ,in this face he drove stakes in a perpendicular line from top to bottom4 ,upon subsequently observing them1 ,tyndall found1 as he expected1 that there was a differential motion among them as in the stakes upon the surface4 ,the retarding effect of friction upon the bottom was evident4 ,the stake near the top moved forwards about three times as fast as the one which was only four feet from the bottom4 ,illustration3 ,fig4 #ah4 ,the most rapid motion 7thirty-seven inches per day7 observed by ,professor ,tyndall upon the ,alpine glaciers occurred in midsummer4 ,in winter the rate was only about one-half as great2 but in the year #ahge the ,norwegian geologist1 ,helland1 reported a movement of twenty metres 7about sixty-five feet7 per day in the ,jakobshavn ,glacier which enters ,disco ,bay1 ,greenland1 about latitude #gj4 ,for some time there was a disposition on the part of many scientific men to doubt the correctness of ,holland's calculations4 ,subsequent observations have shown1 however1 that from the comparatively insignificant glaciers of the ,alps they were not justified in drawing inferences with respect to the motion of the vastly larger masses which come down to the sea through the fiords of ,greenland4 ,the ,jakobshavn ,glacier was about two and a half miles in width and its depth very likely more than a thousand feet1 making a cross-section of more than #a1djj1jjj square yards1 whereas the cross-section of the ,mer de ,glace at ,montanvert is estimated to be but #aij1jjj square yards or only about one-seventh the above estimate for the ,greenland glacier4 ,as the friction of the sides would be no greater upon a large stream than upon a small one1 while upon the bottom it would be only in proportion to the area1 it is evident that we cannot tell beforehand how rapidly an increase in the volume of the ice might augment the velocity of the glacier4 ,at any rate1 all reasonable grounds for distrusting the accuracy of ,helland's estimates seem to have been removed by later investigations4 ,according to my own observations in the summer of #ahhf upon the ,muir ,glacier1 ,alaska1 the central portions1 a mile back from the front of that vast ice-current1 were moving from sixty-five to seventy feet per day4 ,these observations were taken with a sextant upon pinnacles of ice recognizable from a baseline established upon the shore4 ,it is fair to add1 however1 that during the summer of #ahij ,professor ,h4 ,f4 ,reid attempted to measure the motion of the same glacier by methods promising greater accuracy than could be obtained by mine4 ,he endeavoured to plant1 after the method of ,tyndall1 a line of stakes across the ice-current4 ,but with his utmost efforts1 working inwards from both sides1 he was unable to accomplish his purpose1 and so left unmeasured a quarter of a mile or more of the most rapidly-moving portion of the glacier4 ,his results1 therefore1 of ten feet per day in the most rapidly-moving portion observed cannot discredit my own observations on a portion of the stream inaccessible by his method4 ,a quarter of a mile in width near the centre of so vast a glacier gives ample opportunity for a much greater rate of motion than that observed by ,professor ,reid4 ,especially may this be true in view of ,tyndall's suggestion that the contour of the bottom over which the ice flows may greatly affect the rate in certain places4 ,a sudden deepening of the channel may affect the motion of ice in a glacier as much as it does that of water in a river4 ,other observations also amply sustain the conclusions of ,helland4 ,as already stated1 the ,danish surveying party under ,steenstrup1 after several years' work upon the southwestern coast of ,greenland1 have ascertained that the numerous glaciers coming down to the sea in that region and furnishing the icebergs incessantly floating down ,baffin's ,bay1 move at a rate of from thirty to fifty feet per day1 while ,lieutenants ,ryder and ,bloch1 of the ,danish ,navy1 who spent the year #ahhg in exploring the coast in the vicinity of ,upernavik1 about latitude #gc1 found that the great glacier entering the fiord east of the village had a velocity of ninety-nine feet per day during the month of ,august4,,an ,footnote ,,an3 ,nature1 ,december #bi1 #ahhg4 ,it is easier to establish the fact of glacial motion than to explain how the motion takes place1 for ice seems to be as brittle as glass4 ,this1 however1 is true of it only when compelled suddenly to change its form4 ,when subjected to slow and long-continued pressure it gradually yet readily yields1 and takes on new forms4 ,from this capacity of ice1 it has come to be regarded by some as a really viscous substance1 like tar or cooling lava1 and upon that theory ,professor ,forbes endeavours to explain all glacial movement4 ,the theory1 however1 seems to be contradicted by familiar facts2 for the iceman1 after sawing a shallow groove across a piece of ice1 can then split it as easily as he would a piece of sandstone or wood4 ,on the glaciers themselves1 likewise1 the existence of innumerable crevasses would seem to contradict the plastic theory of glacier motion2 for1 wherever the slope of the glacier's bed increases1 crevasses are formed by the increased strain to which the ice is subjected4 ,crevasses are also formed in rapidly-moving glaciers by the slight strain occasioned by the more rapid motion of the middle portion4 ,still1 in the words of ,tyndall1 it is undoubted that the glacier moves like a viscous body4 ,the centre flows past the sides1 the top flows over the bottom1 and the motion through a curved valley corresponds to fluid motion4,,ao ,footnote ,,ao3 ,forms of ,water1 p4 #afc4 ,to explain this combination of the seemingly contradictory qualities of brittleness and viscosity in ice1 physicists have directed attention to the remarkable transformations which take place in water at the freezing-point4 ,faraday discovered in #ahej that when two pieces of thawing ice are placed together they freeze together at the point of contact4,,ap ,footnote ,,ap3 ,ibid41 p4 #afd4 ,place a number of fragments of ice in a basin of water and cause them to touch each other2 they freeze together where they touch4 ,you can form a chain of such fragments2 and then1 by taking hold of one end of the chain1 you can draw the whole series after it4 ,chains of icebergs are sometimes formed in this way in the arctic seas4,,aq ,footnote ,,aq3 ,ibid41 pp4 #afd1 #afe4 ,this is really what takes place when a hard snow-ball is made by pressure in the hand4 ,so1 by subjecting fragments of ice to pressure it is first crumbled to powder1 and then1 as the particles are pressed together in close contact1 it resumes the nature of ice again1 though in a different form1 taking now the shape of the mould in which it has been pressed4 ,thus it is supposed that1 when the temperature of ice is near the melting-point1 the pressure of the superincumbent mass may produce at certain points insensible disintegration1 while1 upon the removal of the pressure by change of position1 regulation instantly takes place1 and thus the phenomena which simulate plasticity are produced4 ,as the freezing-point of water is1 within a narrow range1 determined by the amount of pressure to which it is subjected1 it is not difficult to see how these changes may occur4 ,pressure slightly lowers the freezing-point1 and so would liquefy the portions of ice subjected to greatest pressure1 wherever that might be in the mass of the glacier1 and thus permit a momentary movement of the particles1 until they should recongeal in adjusting themselves to spaces of less pressure4,,ar ,this is the theory by which ,professor ,james ,thompson would account for the apparent plasticity of glacial ice4 ,footnote ,,ar3 ,forms of ,water1 p4 #afh4 ,,chapter ,,iv4 ,,signs ,,of ,,past ,,glaciation4 ,the facts from which we draw the inference that vast areas of the earth's surface which are now free from glaciers were1 at a comparatively recent time1 covered with them1 are fourfold1 and are everywhere open to inspection4 ,these facts are3 #a4 ,scratches upon the rocks4 #b4 ,extensive unstratified deposits of clay and sand intermingled with scratched stones and loose fragments of rock4 #c4 ,transported boulders left in such positions and of such size as to preclude the sufficiency of water-carriage to account for them4 #d4 ,extensive gravel terraces bordering the valleys which emerge from the glaciated areas4 ,we will consider these in their order3 #a4 ,the scratches upon the rocks4 ,almost anywhere in the region designated as having been covered with ice during the ,glacial period1 the surface of the rocks when freshly uncovered will be found to be peculiarly marked by grooves and scratches more or less fine1 and such as could not be produced by the action of water4 ,but1 when we consider the nature of a glacier1 these marks seem to be just what would be produced by the pushing or dragging along of boulders1 pebbles1 gravel1 and particles of sand underneath a moving mass of ice4 ,running water does indeed move gravel1 pebbles1 and boulders along with the current1 but these objects are not held by it in a firm grasp1 such as is required to make a groove or scratch in the rock4 ,if1 also1 there are inequalities in the compactness or hardness of the rock1 the natural action of running water is to hollow out the soft parts1 and leave the harder parts projecting4 ,but1 in the phenomena which we are attributing to glacial action1 there has been a movement which has steadily planed down the surface of the underlying rock2 polishing it1 indeed1 but also grooving it and scratching it in a manner which could be accomplished only by firmly held graving-tools4 ,illustration3 ,fig4 #ai4--;,bed-rock scored with glacial marks1 near ,amherst1 ,ohio4 7,from a photograph by ,chamberlin47 ,this polishing and scratching can indeed be produced by various agencies2 as1 for example1 by the forces which fracture the earth's crust1 and shove one portion past another1 producing what is called a slicken-side4 ,or1 again1 avalanches or land-slides might be competent to produce the results over limited and peculiarly situated areas4 ,icebergs1 also1 and shore ice which is moved backwards and forwards by the waves1 would produce a certain amount of such grooving and scratching4 ,but the phenomena to which we refer are so extensive1 and occur in such a variety of situations1 that the movement of glacial ice is alone sufficient to afford a satisfactory explanation4 ,moreover1 in ,alaska1 ,greenland1 ,norway1 and ,switzerland1 and wherever else there are living glaciers1 it is possible to follow up these grooved and striated surfaces till they disappear underneath the existing glaciers which are now producing the phenomena4 ,thus by its tracks we can1 as it were1 follow this monster to its lair with as great certainty as we could any animal with whose footprints we had become familiar4 #b4 ,the till1 or boulder-clay4 ,a second sign of the former existence of glaciers over any area consists of an unstratified deposit of earthy material1 of greater or less depth1 in which scratched pebbles and fragments of rock occur without any definite arrangement4 ,moving water is a most perfect sieve4 ,during floods1 a river shoves along over its bed gravel and pebbles of considerable size1 whereas in time of low-water the current may be so gentle as to transport nothing but fine sand1 and the clay will be carried still farther onwards1 to settle in the still water and form a delta about the river's mouth4 ,the transporting capacity of running water is in direct ratio to the sixth power of its velocity4 ,other things being equal1 if the velocity be doubled1 the size of the grains of sand or gravel which it transports is increased sixty-four fold4,,as ,so frequent are the changes in the velocity of running water1 that the stratification of its deposits is almost necessary and universal4 ,if large fragments of rocks or boulders are found embedded in stratified clay1 it is pretty surely a sign that they have been carried to their position by floating ice4 ,a small mountain stream with great velocity may move a good-sized boulder1 while the ,amazon1 with its mighty but slow-moving current1 would pass by it forever without stirring it from its position4 ,but the vast area which is marked in our map as having been covered with ice during the ,glacial period is characterised by deep and extensive deposits of loose material devoid of stratification1 and composed of soil and rock gathered in considerable part from other localities1 and mixed in an indiscriminate mass with material which has originated in the disintegration of the underlying local strata4 ,footnote ,,as3 ,le ,conte's ,geology1 p4 #ai4 ,illustration3 ,fig4 #bj4--,scratched stone from the till of ,boston4 ,natural size about one foot and a half long by ten inches wide4 7,from photograph47 ,illustration3 ,fig4 #ba4--,typical section of till in ,seattle4 ,washington ,state1 about two hundred feet above ,puget ,sound4 ,this is on the height between the sound and ,lake ,washington4 ,illustration3 ,fig4 #bb4--;,ideal section1 showing how the till overlies the stratified rocks4 ,illustration3 ,fig4 #bc4--,vessel ,rock1 a glacial boulder in ,gilsum4 ,n4 ,h4 7,c4 ,h4 ,hitchcock47 #c4 ,transported boulders4 ,where there is a current of water deep enough to float large masses of ice1 there is scarcely any limit to the size of boulders which may be transported upon them1 or to the distance to which the boulders may be carried and dropped upon the bottom4 ,the icebergs which break off from the glaciers of ,greenland may bear their burdens of rock far down into the ,atlantic1 depositing them finally amidst the calcareous ooze and the fine sediment from the ,gulf ,stream which is slowly covering the area between ,northern ,america and ,europe4 ,northern streams like the ,st4 ,lawrence1 which are deeply frozen over with ice in the winter1 and are heavily flooded as the ice breaks up in the spring1 afford opportunity for much transportation of boulders in the direction of their current4 ,in attributing the transportation of a boulder to glacial ice1 it is necessary1 therefore1 to examine the contour of the country1 so as to eliminate from the problem the possibility of the effects having been produced by floating ice4 ,another source of error against which one has to be on his guard arises from the close resemblance of boulders resulting from disintegration to those which have been transported by ice from distant places4 ,owing to the fact that large masses of rocks1 especially those which are crystalline1 are seldom homogeneous in their structure1 it results that1 under the slow action of disintegrating and erosive agencies1 the softer parts often are completely removed before the harder nodules are sensibly affected1 and these may remain as a collection of boulders dotting the surface4 ,such boulders are frequent in the granitic regions of ,north ,carolina and vicinity1 where there has been no glacial transportation4 ,several localities in ,pennsylvania1 also1 south of the line of glacial action as delineated by ,professor ,lewis and myself1 had previously been supposed to contain transported boulders of large size1 but on examination they proved in all cases to be resting upon undisturbed strata of the parent rock1 and were evidently the harder portions of the rock left in loco by the processes of erosion spoken of4 ,in ,new ,england1 also1 it is possible that some boulders heretofore attributed to ice-action may be simply the results of these processes of disintegration and erosion4 ,whether they are or not can usually be determined by their likeness or unlikeness to the rocks on which they rest2 but oftentimes1 where a particular variety of rock is exposed over a broad area1 it is difficult to tell whether a boulder has suffered any extensive transportation or not4 ,one of the most interesting and satisfactory demonstrations of the distribution of boulders by glacial ice was furnished by ,guyot in ,switzerland in #ahde4 ,his observations and argument will be most readily understood by reference to the accompanying map1 taken from ,lyell's clear description4,,at ,the ,jura ,mountains are separated from the ,alps by a valley1 about eighty miles in width1 which constitutes the main habitable portion of ,switzerland1 and they rise upwards of two thousand feet above it4 ,but large ,alpine boulders are found as high as two thousand feet above the ,lake ,neufchtel upon the flanks of the ,jura ,mountains beyond ,chasseron 7at the point marked ,g on the map71 and the whole valley is dotted with ,alpine boulders4 ,upon comparing these with the native rocks in the ,alps1 ,guyot in many cases was able to determine the exact centres from which they were distributed1 and the distribution is such as to demonstrate that glacial ice was the medium of distribution4 ,footnote ,,at3 ,antiquity of ,man1 p4 #bii4 ,illustration3 ,fig4 #bd4--,map showing the outline and course of flow of the great ,rhne ,glacier 7after ,lyell74 ,for example1 the dotted lines upon the map indicate the motion of the transporting medium4 ,on ascending the valley of the ,rhne to ,a1 the diminutive representative of the ancient glacier is still found in existence1 and is at work transporting boulders and moraines according to the law of ice-movement4 ,following down the valley from ,a1 boulders from the head of the ,rhne ,valley are found distributed as far as ,b at ,martigny1 where the valley turns at right angles towards the north4 ,it is evident that floating ice in a stream of water would by its momentum be carried to the left bank1 so that if icebergs were the medium of transportation we should expect to find the boulders from the right-hand side of the ,rhne ,valley distributed towards the left end of the great valley of ,switzerland--that is1 in the direction of ,geneva4 ,but1 instead1 the boulders derived from ,c1 ,d1 and ,e1 on the ,bernese ,oberland side1 instead of crossing the valley at ,b1 continue to keep on the right-hand side and are distributed over the main valley in the direction of the river ,aar4 ,as is to be expected also1 the direct northward motion of the ice from ,b is stronger than the lateral movement to the right and left after it emerges from the mouth of the ,rhne ,valley1 at ,f1 and consequently it has pushed forwards in a straight line1 so as to raise the ,alpine boulders to a greater height upon the ,jura ,mountains at ,g than anywhere else1 the upper limit of boulders at ,g being #a1ejj feet higher than the limits at ,i or ,k on the left and right1 points distant about one hundred miles from each other4 ,all the boulders to the right of the line from ,b to ,g have been derived from the right side of the ,rhne1 while all the boulders to the left of that line have been derived from its left side4 ,a boulder of talcose granite containing #fa1jjj ,french cubic feet1 measuring about forty feet in one direction1 came1 according to ,charpentier1 from the point n1 near the head of the ,rhne ,valley1 and must have travelled one hundred and fifty miles to reach its present position4 ,it scarcely needs to be added that the grooves and scratches upon the rocks over the floor of this great valley of ,switzerland indicate a direction of the ice-movement corresponding to that implied in the distribution of boulders4 ,thus1 at ,k upon the map referred to1 ,lyell reports that the abundant grooves and stri upon the polished marble all trend down the valley of the ,aar4,,au ,footnote ,,au3 ,antiquity of ,man1 p4 #cje4 ,similar facts concerning the transportation of boulders have been observed at ,trogen1 in ,appenzel1 where boulders derived from ,trons1 one hundred miles distant1 are found to keep upon the left bank of the ,rhine1 however much the valley may wind about2 and in some places1 as at ,mayenfeld1 it turns almost at right angles1 as did the ,rhne at ,martigny4 ,upon reaching the lower country at ,lake ,constance1 these granite blocks from the left side of the valley deploy out upon the same side and do not cross over1 as they would inevitably have done had they been borne along by currents of water4 ,in ,america ,ave do not have quite so easy a field as is presented in ,switzerland for the discovery of crucial instances showing that boulders have been transported by glacial ice rather than by floating ice1 for in ,switzerland the glaciated area is comparatively small and the diminutive remnants of former glaciers are still in existence1 furnishing a comprehensive object-lesson of great interest and convincing power4 ,still1 it is not difficult to find decisive instances of glacial transportation even in the broad fields of ,america which now retain no living remnants of the great continental ice-sheet4 ,as every one who resides in or who visits ,new ,england knows1 boulders are scattered freely over all parts of that region1 but for a long time the theory suggested to account for their distribution was that of floating ice during a period of submergence4 ,one of the most convincing evidences that the boulders were distributed by glacial ice rather than by icebergs is found in ,professor ,c4 ,h4 ,hitchcock's discovery of boulders on the summit of ,mount ,washington 7over #f1jjj feet above the sea71 which he was able to identify as derived from the ledges of light grey ,bethlehem gneiss1 whose nearest outcrop is in ,jefferson1 several miles to the northwest1 and #c1jjj or #d1jjj feet lower than ,mount ,washington4 ,however difficult it may be to explain the movement of these boulders by glacial ice1 it is not impossible to do so1 but the attempt to account for their transportation by floating ice is utterly preposterous4 ,no iceberg could pick up boulders so far beneath the surface of the water1 and even if it could advance thus far in its work it could not by any possibility land them afterwards upon the summit of ,mount ,washington4 ,among the most impressive instances of boulders evidently transported by glacial ice1 rather than by icebergs1 were some which came to my notice when1 in company with the late ,professor ,h4 ,carvill ,lewis1 ,i was tracing the glacial boundary across the ,state of ,pennsylvania4 ,we had reached the elevated plateau 7two thousand feet above the sea7 which extends westwards and southwards from the peak of ,pocono ,mountain1 in ,monroe ,county4 ,this plateau consists of level strata of sandstone1 the southern part of which is characterised by a thin sandy soil1 such as is naturally formed by the disintegration of the underlying rock1 and there is no foreign material to be found in it4 ,but1 on going northwards to the boundary of ,tobyhanna township1 we at once struck a large line of accumulations1 stretching from east to west1 and rising to a height of seventy or eighty feet4 ,this was chiefly an accumulation of transported boulders1 resembling in its structure the terminal moraines which are found at the front of glaciers in the ,alps and in ,alaska1 and indeed wherever active glaciers still remain4 ,but here we were upon the summit of the mountain1 where there are no higher levels to the north of us1 down which the ice could flow4 ,besides1 among these boulders we readily recognised many of granite1 which must have come either from the ,adirondack ,mountains1 two hundred miles to the north1 or from the ,canadian highlands1 still farther away4 ,limiting our observations simply to the boulders1 we should indeed have been at liberty to suppose that they had been transported across the valley of the ,mohawk or of the ,great ,lakes by floating ice during a period of submergence4 ,but we were forbidden to resort to this hypothesis by the abrupt marginal line1 running east and west1 upon ,pocono plateau1 along which these northern boulders ceased4 ,south of this evident terminal moraine there was no barrier1 and there were no northern boulders4 ,on the theory of submergence1 there was no reason for the boundary-line so clearly manifested4 ,ice which had floated so far would have floated farther4 ,still further1 on going a few miles east of the ,pocono plateau1 one descends into a parallel valley1 lying between ,pocono ,mountain and ,blue ,mountain1 and one thousand feet below their level4 ,but our marginal southern boundary of transported granite rocks did not extend much farther south in the valley than it did on the plateau1 except where we could trace the action of a running stream1 evidently corresponding to the subglacial rivers which pour forth from the front of every extensive glacier4 ,in these facts1 therefore1 we had a crucial test of the glacial hypothesis1 and1 in view of them1 could maintain1 against all objectors1 the theory of the distant glacial transportation of boulders1 even over vast areas of the ,north ,american continent4 ,since that experience1 ,i have traced this limit of southern boulders for thousands of miles across the continent1 according to the delineation which may be seen in the map in a later chapter4 ,if necessary1 ,i could indicate hundreds of places where the proof of glacial transportation is almost as clear as that on the ,pocono plateau in ,pennsylvania4 ,one of the most interesting of these is on the hills in ,kentucky1 about twelve miles south of the ,ohio ,river1 at ,cincinnati1 where ,i discovered boulders of a conglomerate containing many pebbles of red jasper1 which can be identified as from a limited formation cropping out in ,canada1 to the north of ,lake ,huron1 six hundred or seven hundred miles distant4 ,that this was transported by glacial ice1 and not by floating ice1 is evident from the fact that here1 too1 there was no barrier to the south1 requiring deposits to cease at that point1 and from the further fact that boulders of this material are found in increasing frequency all the way from ,kentucky to the parent ledges in ,canada4 ,with reference to these boulders1 as with reference to those found on the summit of ,mount ,washington1 we can reason1 also1 that any northerly subsidence permitting a body of water to occupy the space between ,kentucky and ,lake ,superior1 and deep enough to facilitate the movement across it of floating ice1 would render it impossible for the ice to have loaded itself with them4 ,illustration3 ,fig4 #be4--;,conglomerate boulder found in ,boone ,county1 ,kentucky4 7,see text47 ,the same line of reasoning is conclusive respecting the innumerable boulders which cover the northern portion of ,ohio1 where ,i have my residence4 ,the whole ,state of ,ohio1 and indeed almost the entire ,mississippi basin between the ,appalachian and the ,rocky ,mountains1 is completely covered1 and to a great depth1 with stratified rocks which have been but slightly disturbed in the elevation of the continent2 yet1 down to an irregular border-line running east and west1 granitic boulders everywhere occur in great numbers4 ,in the locality spoken of in northern ,ohio the elevation of the country is from two hundred to five hundred feet above the level of ,lake ,erie4 ,the nearest outcrops of granitic rock occur about four hundred miles to the north1 in ,canada4 ,after the meeting of the ,american ,association for the ,advancement of ,science in ,toronto in the summer of #ahhi1 ,i had the privilege of joining a company of geologists in an excursion1 conducted by members of the ,canadian ,survey1 to visit the region beyond ,lake ,nipissing1 north of ,lake ,huron1 where the ancient ,laurentian and ,huronian rocks are most typically developed4 ,i took advantage of the trip to collect specimens of a great variety of the granites and gneisses and metamorphic schists and trap-rock of the region4 ,on bringing them home ,i turned them over to the professor of geology1 who at once set his class at work to see if they could match my fragments from ,canada with corresponding fragments from the boulders of the vicinity4 ,to the great gratification1 both of the pupils and myself1 they were able to do so in almost every case2 and so they might have done in any county or township to the south until reaching the limit of glacier action which ,i had previously mapped4 ,here1 at ,oberlin1 on the north side of the water-shed1 it is possible to imagine that we are on the southern border of an ancient lake upon whose bosom floating ice had brought these objects from their distant home in ,canada4 ,but this theory would not apply to the portion of the ,state which is south of the water-shed and which slopes rapidly towards the ,gulf of ,mexico4 ,yet the distribution of boulders is practically uniform over the glaciated area on both sides of the water-shed1 constituting thus an indisputable proof of the glacial theory4 #dth4 ,as the significance of the gravel terraces which mark the lines of outward drainage from the glaciated area cannot well be indicated in a single paragraph1 the reader is referred for further information upon this point to the general statements respecting them throughout the next chapter4 ,,chapter ,v4 ,,ancient ,,glaciers ,,in ,,the ,,western ,,hemisphere4 ,new ,england4 ,in ,north ,america all the indubitable signs of glacial action are found over the entire area of ,new ,england1 the southern coast being bordered by a double line of terminal moraines4 ,the outermost of these appears in ,nantucket1 ,martha's ,vineyard1 ,no ,man's ,land1 ,block ,island1 and through the entire length of ,long ,island--from ,montauk ,point1 through the centre of the island1 to ,brooklyn1 ,n4 ,y41 and thence across ,staten ,island to ,perth ,amboy in ,new ,jersey4 ,the interior line is nearly parallel with the outer1 and1 beginning at the east end of ,cape ,cod1 runs in a westerly direction to ,falmouth1 and thence southwesterly through ,wood's ,holl1 and the ,elizabeth ,islands--these being1 indeed1 but the unsubmerged portions of the moraine4 ,on the mainland this interior line reappears near ,point ,judith1 on the south shore of ,rhode ,island1 and1 running slightly south of west1 serves to give character to the scenery at ,watch ,hill1 and thence crops out in the ,sound as ,fisher and ,plum ,islands1 and farther west forms the northern shore of ,long ,island to ,port ,jefferson4 ,illustration3 ,,map ,,showing ,,the ,,glacial ,,geology ,,of ,,the ,,united ,,states4 ,in these accumulations bordering the southern shore of ,new ,england1 the characteristic marks of glacial action can readily be detected even by the casual observer1 and prolonged examination will amply confirm the first impression4 ,the material of which they are composed is1 for the most part1 foreign to the localities1 and can be traced to outcrops of rock at the north4 ,the boulders scattered over the surface of ,long ,island1 for example1 consist largely of granite1 gneiss1 hornblende1 mica slate1 and red sandstone1 which are easily recognised as fragments from well-known quarries in ,connecticut1 ,rhode ,island1 and ,massachusetts2 yet they have been transported bodily across ,long ,island ,sound1 and deposited in a heterogeneous mass through the entire length of the island4 ,not only do they lie upon the surface1 but1 in digging into the lines of hills which constitute the backbone of ,long ,island1 these transported boulders are found often to make up a large part of the accumulation4 ,almost any of the railroad excavations in the city of ,brooklyn present an interesting object-lesson respecting the composition of a terminal moraine4 ,all these things are true also of the lines of moraine farther east1 as just described4 ,professor ,shaler has traced to its source a belt of boulders occurring extensively over southern ,rhode ,island1 and found that they have spread out pretty evenly over a triangular area to the southward1 in accordance with the natural course to be pursued by an ice-movement4 ,nearly all of ,plymouth ,county1 in southeastern ,massachusetts1 is composed of foreign material1 much of which can be traced to the hills and mountains to the north4 ,even ,plymouth ,rock is a boulder from the direction of ,boston1 and the rock-bound shores upon which the ,pilgrims are poetically conceived to have landed are known1 in scientific prose1 as piles of glacial rubbish dumped into the edge of the sea by the great continental ice-sheet4 ,the whole area of southeastern ,massachusetts is dotted with conical knolls of sand1 gravel1 and boulders1 separated by circular masses of peat or ponds of water1 whose origin and arrangement can be accounted for only by the peculiar agency of a decaying ice-front4 ,indeed1 this whole line of moraines1 from the end of ,cape ,cod to ,brooklyn1 ,n4 ,y41 consists of a reticulated network of ridges and knolls1 so deposited by the ice as to form innumerable kettle-holes which are filled with water where other conditions are favourable4 ,those which are dry are so because of their elevation above the general level1 and of the looseness of the surrounding soil2 while many have been filled with a growth of peat1 so that their original character as lakelets is disguised4 ,as already described1 these depressions1 so characteristic of the glaciated region1 are1 in the majority of cases1 supposed to have originated by the deposition of a great quantity of earthy material around and upon the masses of ice belonging to the receding front of the glacier1 so that1 when at length the ice melted away1 a permanent depression in the soil was left1 without any outlet4 ,to some extent1 however1 the kettle-holes may have been formed by the irregular deposition of streams of water whose courses have crossed each other1 or where eddies of considerable force have been produced in any way4 ,the ordinary formation of kettle-holes can be observed in progress on the foot of almost any glacier1 or1 indeed1 on a small scale1 during the melting away of almost any winter's snow4 ,where1 from any cause1 a stratum of dirt has accumulated upon a mass of compact snow or ice1 it will be found to settle down in an irregular manner2 furrows will be formed in various directions by currents of water1 so that the melting will proceed irregularly1 and produce upon a miniature scale exactly what ,i have seen on a large scale over whole square miles of the decaying foot of the great ,muir ,glacier in ,alaska4 ,the effects of similar causes and conditions we can see on a most enormous scale in the ten thousand lakes and ponds and peat-bogs of the whole glaciated area both in ,north ,america and in ,europe4 ,in addition to these two lines of evidence of glacial action in ,new ,england1 we should mention also the innumerable glacial grooves and scratches upon the rocks which can be found on almost any freshly uncovered surface4 ,in ,new ,england the direction of these grooves is ordinarily a little east of south4 ,upon the east coast of ,massachusetts and ,new ,hampshire the scratches trend much more to the east than they do over most of the interior4 ,this is as it should be on the glacial theory1 since the ice would naturally move outwards in the line of least resistance1 which would1 of course1 be towards the open sea wherever that is near4 ,in the interior of ,new ,england the scratches upon the rocks indicate a more southerly movement in the ,connecticut ,valley than upon the mountains in the western part of ,massachusetts4 ,this also is as it should be upon the glacial theory4 ,the scratches upon the mountains were made when the ice was at its greatest depth and when it moved over the country in comparative disregard of minor irregularities of surface1 while in the valleys1 at least in the later portion of the ,ice age1 the movement would be obstructed except in one direction4 ,in the interpretation of the glacial grooves and scratches it should be borne in mind that they often represent the work done during the closing stages of the period4 ,just as the last shove of the carpenter's plane removes the marks of the previous work1 so the last rasping of a glacial movement wears away the surfaces which have been previously polished and striated4 ,in various places of ,new ,england it is interesting as well as instructive to trace the direction of the ice-movement by the distribution of boulders4 ,my own attention was early attracted to numerous fragments of gneiss in eastern ,massachusetts containing beautiful crystals of feldspar1 which proved to be peculiar to the region of ,lake ,winnepesaukee1 a hundred miles to the north1 and to a narrow belt stretching thence to the southwestward4 ,in ascending almost any of the lower summits of the ,white ,mountains one's attention can scarcely fail of being directed to the difference between the material of which the mountains are composed and that of the numerous boulders which lie scattered over the surface4 ,the local geologist readily recognises these boulders as pilgrims that have wandered far from their homes to the northward4 ,trains of boulders1 such as those already described in ,rhode ,island1 can frequently be traced to some prominent outcrop of the rock in a hill or mountain-peak from which they have been derived4 ,one of the earliest of these to attract attention occurs in the towns of ,richmond1 ,lenox1 and ,stockbridge1 in the western part of ,massachusetts4 ,here a belt of peculiar boulders about four hundred feet wide is found to originate in the town of ,lebanon1 ,n4 ,y41 and to run continuously to the southeast for a distance of nine miles4 ,west of ,fry's ,hill1 where the outcrop occurs1 no boulders of this variety of rock are to be found1 while to the southeast the boulders gradually diminish in size as their distance from the outcrop increases4 ,near the outcrop boulders of thirty feet in diameter occur1 while nine miles away two feet is the largest diameter observed4 ,sir ,charles ,lyell endeavoured to explain this train of boulders by the action of icebergs during a period of submergence--supposing that1 as icebergs floated past or away from this hill in ,lebanon1 ,n4 ,y41 they were the means of the regular distribution described4 ,it is needless to repeat the difficulties arising in connection with such a theory1 since now both by observation and experiment we have become more familiar with the movement of glacial ice4 ,what we have already said about the transportation of boulders over ,switzerland by the ,alpine glaciers1 and what is open to observation at the present time upon the large glaciers of ,alaska1 closely agree with the facts concerning this ,richmond train of boulders1 and we have no occasion to look further for a cause4 ,indeed1 trains of boulders ought to appear almost everywhere over the glaciated area2 and so they do where all the circumstances are favourable4 ,but1 readily to identify the train1 requires that to furnish the boulders there should be in the line of the ice-movement a projecting mass of rock hard enough to offer considerable resistance to the abrading agency of the ice and characteristic enough in its composition to be readily recognised4 ,ship ,rock1 in ,peabody1 ,mass41 weighing about eleven hundred tons1 and ,mohegan ,rock1 in ,montville1 ,conn41 weighing about ten thousand tons1 have ordinarily been pointed to as boulders illustrating the power of ice-action4 ,their glacial character1 however1 has been challenged from the fact that the variety of granite to which they belong occurs in the neighbourhood1 and indeed constitutes the bed-rock upon which they rest4,,av ,some would therefore consider them1 like some of which we have already spoken1 to be boulders which have originated through the disintegration of great masses of rock1 of which these were harder nuclei that have longer resisted the ravages of the tooth of time4 ,it must be admitted that possibly this explanation is correct2 but it is scarcely probable that1 in a region where there are so many other evidences of glacial action1 these boulders could have remained immovable in presence of the onward progress of the ice-current that certainly passed over them4 ,footnote ,,av3 ,popular ,science ,monthly1 vol4 xxxvii1 pp4 #aif-bja4 ,however1 as already seen1 we are not left to doubt as to the movement of some boulders of great size4 ,that which now claims the reputation of being the largest in ,new ,england is in ,madison1 ,n4 ,h41 and measures thirty by forty by seventy-five feet4 ,this can be traced to ledges of ,conway granite1 about two miles away4,,aw ,many boulders in the vicinity of ,new ,haven1 ,conn41 can be identified1 as from well-known trap-dykes1 sixteen miles or more to the north4 ,the so-called ,judge's ,cave1 on ,west ,rock1 #cfe feet above the adjoining valley and weighing a thousand tons1 is one of these4 ,professor ,edward ,orton,,ax describes a mass of ,clinton limestone near ,freeport1 ,warren ,county1 ,ohio1 as covering an area of three-fourths of an acre1 and as sixteen feet in thickness4 ,it overlies glacial clays and gravels1 and must have been transported bodily from the elevations containing this rock several miles to the northwest4 ,footnote ,,aw3 ,see ,w4 #j4 ,crosby's paper in ,appalachia1 vol4 vi1 pp4 #ei-gj4 ,footnote ,,ax3 ,geological ,survey of ,ohio1 vol4 iii1 p4 #che1 ,illustration3 ,fig4 #bf4--,mohegan ,rock4 ,portions of ,new ,england present the best illustrations anywhere afforded in ,america of what are called drumlins4 ,these are lenticular-shaped hills1 composed of till1 and containing1 interspersed through their mass1 numerous scratched stones of all sizes4 ,they vary in length from a few hundred feet to a mile1 and are usually from half to two-thirds as wide as they are long4 ,in height they vary from twenty-five to two hundred feet4 ,but1 according to the description of ,mr4 ,upham1 whatever may be their size and height1 they are singularly alike in outline and form1 usually having steep sides1 with gently sloping1 rounded tops1 and presenting a very smooth and regular contour4 ,from this resemblance in shape to an elliptical convex lens1 ,professor ,hitchcock has called them lenticular hills to distinguish these deposits of till from the broadly flattened or undulating sheets which are common throughout ,new ,england4 ,illustration3 ,fig4 #bg4--;,drumlins in ,goffstown1 ,n4 ,h4 7,hitchcock74 ,the trend1 or direction of the longer axis1 of these lenticular hills is nearly the same for all of them comprised within any limited area1 and is approximately like the course of the stri or glacial furrows marked upon the neighbouring ledges4 ,in eastern ,massachusetts and ,new ,hampshire1 within twenty-five miles of the coast1 it is quite uniformly to the southeast1 or east-southeast4 ,farther inland1 in both of these ,states1 it is generally from north to south1 or a few degrees east of south2 while in the valley of the ,connecticut ,river it is frequently a little to the west of south4 ,in ,new ,hampshire1 besides its accumulation in these hills1 the till is frequently amassed in slopes of similar lenticular form4 ,these have their position almost invariably upon either the south or north side of the ledgy hills against which they rest1 showing a considerable deflection towards the southeast and northwest in the east part of the ,state4 ,it cannot be doubted that the trend of the lenticular hills1 and the direction taken by these slopes1 have been determined by the glacial current1 which produced the stri with which they are parallel4,,ay ,footnote ,,ay3 ,proceedings of the ,boston ,society of ,natural ,history1 vol4 xx1 pp4 #bbd1 #bbe4 ,drumlins are abundant in the vicinity of ,boston1 and constitute nearly all the islands in ,boston ,harbour4 ,on the mainland1 ,beacon ,hill1 ,bunker ,hill1 ,green ,hill1 ,powderhorn ,hill1 ,tufts ,college ,hill1 ,winter ,hill1 ,mount ,ida1 ,corey ,hill1 ,parker ,hill1 ,wollaston ,heights1 ,prospect ,hill1 and ,telegraph ,hill are specimens4 ,the northeastern corner of ,massachusetts and the southeastern corner of ,new ,hampshire are largely covered with these peculiar-shaped glacial deposits1 while they are numerous as far west as ,fitchburg1 in ,massachusetts1 and ,ware1 ,n4 ,h41 and in the northeastern part of ,connecticut4 ,a little later1 also1 we shall refer to an interesting line of them in central ,new ,york4 ,elsewhere in ,america1 except in a portion of ,wisconsin1 they rarely occur in such fine development as in ,new ,england4 ,in ,europe they are best developed in portions of ,ireland4 ,one's first impression in examining an exposed section of a drumlin would lead him to think that the mass was entirely unstratified2 but closer examination shows that there is a coarse stratification1 but evidently not produced by water-action4 ,the accumulation has probably taken place gradually by successive deposits underneath the glacier itself4 ,professor ,william ,m4 ,davis has suggested a plausible explanation which we will briefly state4 ,illustration3 ,fig4 #bh4--;,drumlins in the vicinity of ,boston 7,davis74 ,the frequency with which drumlins are found to rest upon a mass of projecting rock1 the general co-ordination of the direction of their axes with the direction of the scratches upon the underlying rock1 and the abundance of scratched stones in them1 all support the theory that drumlins are formed underneath the ice-sheet1 somewhat in the way that islands and bars of silt are formed in the delta of a great river4 ,the movement of ice seems to have been concentrated in pretty definite lines1 often determined by the contour of the bottom1 leaving a slacker movement in intervening areas1 which were evidently protected in some cases by projecting masses of rock4 ,in these areas of slower movement there was naturally an accumulation at the same time that there was vigorous erosion in the lines of more rapid movement4 ,there was doubtless a continual transfer of material from the end of the drumlin which abutted against the moving mass of ice to the lower end1 as there is in the formation of an island in a river4 ,if time enough had elapsed1 the whole accumulation would have been levelled by the glacier and spread over the broader area where the more rapid lines of movement became confluent1 and where the differential motion was less marked4 ,drumlins are thus characteristic of areas in the glaciated region whose floor was originally only moderately irregular1 and where there was an excessive amount of ground-moraine to be transported1 and where the movement did not continue indefinitely4 ,it has been suggested1 also1 that some of the long belts of territory in ,new ,england and central ,new ,york covered by drumlins may represent old terminal moraines which were subsequently surmounted by a readvance of the ice1 and partially wrought over into their present shape4 ,it is in ,new ,england1 also1 that kames are to be found in better development than anywhere else in ,america4 ,these interesting remnants of the ,glacial age are clearly described by ,mr4 ,james ,geikie4 ,his account will serve as well for ,new ,england as for ,scotland4 ,the sands and gravels have a tendency to shape themselves into mounds and winding ridges1 which give a hummocky and rapidly undulating outline to the ground4 ,indeed1 so characteristic is this appearance1 that by it alone we are often able to mark out the boundaries of the deposits with as much precision as we could were all the vegetation and soil stripped away and the various subsoils laid bare4 ,occasionally1 ridges may be tracked continuously for several miles1 running like great artificial ramparts across the country4 ,these vary in breadth and height1 some of the more conspicuous ones being upward of four or five hundred feet broad at the base1 and sloping upward at an angle of twenty-five or even thirty-five degrees1 to a height of sixty feet and more above the general surface of the ground4 ,it is most common1 however1 to find mounds and ridges confusedly intermingled1 crossing and recrossing each other at all angles1 so as to enclose deep hollows and pits between4 ,seen from some dominant point1 such an assemblage of kames1 as they are called1 looks like a tumbled sea--the ground now swelling into long undulations1 now rising suddenly into beautiful peaks and cones1 and anon curving up in sharp ridges that often wheel suddenly round so as to enclose a lakelet of bright clear water4,,az ,footnote ,,az3 ,the ,great ,ice ,age1 pp4 #baj1 #baa4 ,illustration3 ,fig4 #bi4--,section of kame near ,dover1 ,new ,hampshire4 ,length1 three hundred feet2 height1 forty feet2 base1 about forty feet above the ,cocheco ,river1 or seventy-five feet above the sea4 a1 a1 gray clay2 b1 fine sand2 c1 c1 coarse gravel containing pebbles from six inches to one foot and a half in diameter2 d1 d1 fine gravel 7,upham74 ,illustration3 ,fig4 #cj4--,kames in ,andover ,mass4 ,in ,new ,england attention was first directed to kames in #ahdb1 by ,president ,edward ,hitchcock1 in a paper before the ,american ,association of ,geologists and ,naturalists1 describing the gravel ridges in ,andover1 ,mass4 ,in the accompanying plate is shown a portion of this kame system1 which has a double interest to me from the fact that it was while living upon the banks of the ,shawshin ,river1 near where the kames and the river intersect1 that ,i began1 in #ahgd1 my special study of glacial deposits4 ,the ,andover ridges are composed of imperfectly stratified water-worn material1 and are very sharply defined1 from the town of ,chelsea1 back from the coast into ,new ,hampshire1 for a distance of twenty-five miles4 ,the base of the ridges does not maintain a uniform level1 but the system descends into shallow valleys1 and rises over elevations of one hundred to two hundred feet1 without interruption4 ,this indifference to slight changes of level is specially noticeable where the system crosses the ,merrimac ,river1 just above the city of ,lawrence4 ,it is also represented in the accompanying plate1 where the base of the ridges in the immediate valley of the ,shawshin is fifty feet lower than the base of those a short distance to the north1 at the points marked a1 b1 and c4 ,the ridges here terminate at the surface in a sharp angle1 and are above their base forty-one feet at a1 forty-nine feet at b1 and ninety-one feet at c4 ,between c and b there is an extensive peat-swamp1 filling the depression up to the level of an outlet through which the surplus water has found a passage4 ,illustration3 ,fig4 #ca4--,longitudinal kames near ,hingham1 ,massachusetts4 ,the parallel ridges of gravel in the foreground run nearly east and west1 and coalesce at each end1 near the edges of the picture1 to form an elongated kettle-hole4 ,the ridges from fifty to sixty feet in height4 ,the kame-stream was here evidently emptying into the ocean a few miles to the east 7,bouv74 ,several systems of kames approximately parallel to this have been traced out in ,massachusetts and ,new ,hampshire1 while the remnants of a very extensive system are found in the ,connecticut ,valley above the ,massachusetts line4 ,but they abound in greatest profusion in the ,state of ,maine1 where ,professor ,george ,h4 ,stone has plotted them with much care4 ,the accompanying map gives only an imperfect representation of the ramifying systems which he has traced out1 and of the extent to which they are independent of the present river-channels4 ,one of the longest of these extends more than one hundred miles1 crossing the ,penobscot ,river nearly opposite ,grand ,lake1 and terminating in an extensive delta of gravel and sand in ,cherryfield1 nearly north of ,mount ,desert4 ,this is represented on our map by the shaded portion west of the ,machias ,river4 ,locally these ridges are variously designated as horsebacks1 hogbacks1 or whalebacks1 but that in ,andover1 ,mass41 was for some reason called ,indian ,ridge4 ,nowhere else in the world are these ridges better developed than in ,new ,england1 except it be in southern ,sweden1 where they have long been known and carefully mapped4 ,illustration3 ,fig4 #cb4--,the kames of ,maine and southeastern ,new ,hampshire4 7,stone47 ,the investigations of ,mr4 ,w4 #j4 ,crosby upon the composition of till in eastern ,massachusetts is sufficiently important in its bearings upon the question of glacial erosion to merit notice at this point4,,ba ,the object of his investigations was to determine how much of the so-called ground moraine1 or till1 consisted of material disintegrated by mechanical action1 and how much by chemical action4 ,the residuary clay1 which has arisen from chemical decomposition1 would properly be attributed to the disintegrating agencies of preglacial times1 while the clay1 which is strictly mechanical in its origin1 remains to represent the true grist or rock flour of the ,glacial period4 ,footnote ,,ba3 ,proceedings of the ,boston ,society of ,natural ,history1 vol4 xxv 7#ahij71 pp4 #aae-adj4 ,the results of ,mr4 ,crosby's investigations show that not more than one-third of the detritus composing the till of the ,boston ,basin was in existence before the ,ice age1 and that the remaining two-thirds must be attributed to the mechanical action of the ice-sheet and its accompanying torrents of water4 ,in other words1 if we assume the average thickness of the drift as thirty feet1 the amount of glacial erosion can scarcely fall below twenty feet4 ,after scraping away the residuary clays and half-decomposed material1 the ice-sheet has cut more than an equal depth into the solid rocks4 ,mr4 ,crosby's investigations also convinced him that the movement of the till1 or ground moraine1 underneath the ice was not en masse1 but that it must have experienced differential horizontal movements or flowing1 in which1 normally1 every particle or fragment slipped or was squeezed forward with reference to those immediately below it1 the velocity diminishing downward through the friction of the underlying ledges4444 ,the glaciation was not limited to masses which were firmly caught between the ice and the solid ledges1 and it was in every case essentially a slipping and not a rolling movement4444 ,these differential horizontal movements mean that the till acted as a lubricant for the ice-sheet2 and the clayey element1 especially1 co-operating in many cases with the pent-up subglacial waters1 must have greatly facilitated the onward progress of the ice4 ,he concludes1 therefore1 that the onward movement of the vast ice-sheet greatly exceeded that of the main part of the ground moraine1 the ice-sheet slipping over the till1 the whole being in some degree analogous to that of a great land-slip4 ,in both cases the progress of a somewhat yielding and mobile mass is facilitated by an underlying clayey layer saturated with water4 ,new ,york1 ,new ,jersey1 and ,pennsylvania4 ,west of ,new ,england the glacial phenomena over the northern part of the ,united ,states are equally marked all the way to the ,missouri ,river1 and the boundary-line of the glaciated region can be traced with little difficulty4 ,it emerges from ,new ,york ,bay on ,staten ,island and enters ,new ,jersey at ,perth ,amboy4 ,a well-formed moraine covers the northern part of ,staten ,island1 and upon the mainland marks the boundary from ,perth ,amboy1 around through ,raritan1 ,plainfield1 ,chatham1 ,morris1 and ,hanover1 to ,rockaway1 and thence in a southwesterly direction to ,belvidere1 on the ,delaware ,river4 ,that portion of ,new ,jersey lying north of this serpentine line of moraine hills is characterised by the presence of transported boulders1 by numerous lakes of evident glacial origin1 and by every other sign of glacial action1 while south of it all these peculiar characteristics are absent4 ,the observant passenger upon the railroad trains between ,new ,york and ,philadelphia can easily recognise the moraine as it is passed through on the ,pennsylvania ,railroad at ,metuchen and on the ,bound ,brook ,railroad at ,plainfield4 ,near ,drakestown1 in ,morris ,county1 there is a mass of blue limestone measuring1 as exposed1 thirty-six by thirty feet1 and which was quarried for years before discovering that it was a boulder brought with other drift material from many miles to the northwest and lodged here a thousand feet above the sea4 ,across ,pennsylvania the glacial boundary passes through ,northampton1 ,monroe1 ,luzerne1 ,columbia1 ,sullivan1 ,lycoming1 ,tioga1 and ,potter ,counties1 where it enters the ,state of ,new ,york1 running still in a northwest direction through ,allegany and ,cattaraugus ,counties to the vicinity of ,salamanca4 ,here it turns to the south nearly at a right angle1 running southwestward to ,chautauqua ,county and re-entering ,pennsylvania in ,warren ,county1 and thence passing onward in the same general direction through ,crawford1 ,venango1 ,mercer1 ,butler1 and ,lawrence ,counties to the ,ohio line in ,columbiana ,county1 about ten miles north of the ,ohio ,river4 ,the occurrence of a well-defined terminal moraine to mark the glacial boundary eastward from ,pennsylvania led ,professor ,lewis and myself1 who made the survey of that ,state in #ahhj1 to be rather too sanguine in our expectations of finding an equally well-marked moraine everywhere along the southern margin of the glaciated area2 still1 the results are even more interesting than would have been the exact fulfilment of our expectations1 since they more fully revealed to us the great complexity of effect which is capable of being brought about by ice-action4 ,before proceeding farther with the details1 therefore1 it will be profitable at this point to pause in the narrative and briefly record a few generalisations that have forced themselves into prominence during the years in which field-work has been in progress4 ,previous to our explorations in ,pennsylvania it had been thought that the indications of ice-action would extend much farther south in the valleys than on the mountains1 and this indeed would have been the case if the glaciers in northern ,pennsylvania had been of local origin2 but our experience very soon demonstrated that the great gathering-place of the snows which produced the glacial movement in northern ,pennsylvania could not have been local1 but that over the northern part of that ,state there was distinct evidence of a continental movement of ice whose centre was far beyond the ,alleghanies4 ,for example1 we found that the evidences of direct glacial action extended farther south upon the hills and plateaus than they did in the narrow valleys1 while everywhere on the very southern border of glacial indications we found boulders that had been brought from the granitic region of northern ,new ,york or central ,canada4 ,in eastern ,pennsylvania we found indeed a terminal moraine more or less distinctly marking the southern border over the highlands4 ,this was more specially true in ,northampton and ,monroe ,counties4 ,in ,northampton ,county it was very interesting to see long lines of hills1 a hundred or more feet in height and lying several hundred feet above the ,delaware ,river1 composed entirely of glacial dbris1 much of which had been brought bodily over the sharp summit of the ,blue ,ridge1 or ,kittatinny ,mountain1 which rises as a continuous wall to the northwest and is everywhere several hundred feet higher than the moraine in ,northampton ,county4 ,the summit of ,blue ,ridge1 also1 as far south as the glacial movement extended1 shows evident signs of glacial abrasion1 some hundreds of feet evidently having been removed by that means1 leaving a well-defined shoulder1 marking the limits of its southwestern border4 ,resting upon the summit of the glaciated portion of the ,blue ,ridge1 there are also numerous boulders of ,helderberg limestone1 which must have been brought from ledges at least five hundred feet lower than the places upon which they now lie4 ,in ,monroe ,county the terminal moraine marking there the extreme limit of the ice-movement is upon an extensive plateau of ,pocono sandstone1 about eighteen hundred feet above sea-level1 and five or six hundred feet lower than the crest of the ,alleghany ,mountains1 a short distance to the north4 ,the moraine hills are here well marked by the occurrence of circular lakelets and kettle-holes 7such as have been described as characteristic of the shores and islands bordering the south of ,new ,england72 by the occurrence of granitic boulders1 which must have been brought from the ,adirondacks or ,canada2 and by the various other indications referred to on a previous page4 ,as already intimated1 the instructive point in our observations is the fact that1 between ,kittatinny ,mountain1 in ,northampton ,county1 and ,pocono plateau1 in ,monroe ,county1 there is a longitudinal depression1 running northeast by southwest1 parallel with the ranges of the mountain system1 which is here about a thousand feet below the respective ridges on either side4 ,this1 therefore1 is one of the places where we should have expected a considerable southern extension of the ice1 if it had been largely due to local causes4 ,now1 while there is indeed a gradual southern trend down the flanks of the mountain1 yet1 upon reaching the axis of the valley1 there appears at once a very marked change in the character of the deposit1 and the influence of powerful streams of water becomes manifest1 and it is evident1 upon a slight inspection1 that we have come upon a line of drainage which sustained a peculiar relation to the continental ice-sheet4 ,from ,stroudsburg1 near the ,delaware ,water-,gap1 to ,weissport1 on the ,lehigh ,river1 a distance of about thirty miles1 the valley between the mountains is continuous1 and the elevation at each end very nearly the same4 ,but about half-way between the two places1 near ,saylorsburg1 there is a river-parting from which the water now runs on the one hand north to ,stroudsburg1 and thence to the ,delaware ,river1 and on the other hand south1 through ,big and ,aquonchichola ,creeks1 to the ,lehigh ,river4 ,the river-parting is formed by a great accumulation of gravel1 whose summit is about two hundred feet above the level of the valleys into which the creeks empty at either end2 and there are numerous kettle-holes and lakelets in the vicinity1 such as characterize the glacial region in general4 ,in short1 we are1 without doubt1 here on a well-marked terminal moraine much modified by strong water-action in a valley of glacial drainage4 ,the gravel and boulders are all well water-worn1 and the material is of various kinds1 including granite boulders from the far north1 such as characterise the terminal moraine on the highlands2 but the pebbles are not scratched1 and the gravel is more or less stratified4 ,it is evident that we are here where a violent stream of water poured forth from that portion of the ice-front which filled this valley1 and which found its only outlet in the direction of the ,lehigh ,river4 ,the gravel can be traced in diminishing quantities to the southward1 in accordance with this theory1 while to the northward there extends a series of gravel ridges1 or kames1 such as we have shown naturally to owe their origin to the accumulations taking place in ice-channels formed near the front of a glacier as it slowly melts away4 ,from similar occurrences of vast gravel accumulations in other valleys stretching southward from the glacial margin1 we came to expect that1 wherever there was an open1 line of drainage from the glaciated region southward1 the point of intersection between the glacial margin and the drainage valley would be marked by an excessive accumulation of water-worn gravel1 diminishing in coarseness and abundance down the valleys in proportion to the distance from the glacial margin4 ,for example1 the ,delaware ,river emerges from the glaciated region at ,belvidere1 and there are there vast accumulations of gravel rising a hundred or more feet above the present level of the river1 while gravel terraces1 diminishing in height1 mark the river below to tide-water at ,trenton4 ,the ,lehigh ,river leaves the glaciated region at ,hickory ,run1 a few miles above ,mauch ,chunk1 but the gorge is so steep that there was little opportunity either for the accumulation of gravel there or for its preservation4 ,still1 the transported gravel and boulders characteristic of the melting floods pouring forth from a glacier1 are found lining the banks of the ,lehigh all along the lower portion of its course4 ,in the ,susquehanna ,river we have a better example at ,beach ,haven1 in ,luzerne ,county1 where there are very extensive accumulations of gravel resting on the true glacial deposits of the valley1 and extending down the river in terraces of regularly diminishing height for many miles1 and merging into terraces of moderate elevation which line the ,susquehanna ,valley throughout the rest of its course4 ,above ,beach ,haven the gravel deposits in the trough of the river valley are more irregular1 and betray the modifying influence of the slowly decaying masses of ice which belonged to the enveloping continental glacier4 ,westward from the north fork of the ,susquehanna1 similar extensive accumulations of gravel occur at the intersection of ,fishing ,creek in ,columbia ,county1 ,muncy1 ,loyalsock1 ,lycoming1 and ,pine ,creeks in ,lycoming ,county1 all tributary to the ,susquehanna ,river1 and all evidently being channels through which the melting floods of the ice-sheet brought vast quantities of gravel down to the main stream4 ,williamsport1 on the ,west ,branch of the ,susquehanna1 is built upon an extensive terrace containing much granitic material1 brought down from the glaciated region by ,lycoming ,creek1 when it was flooded with the waters melted from the continental ice-sheet which had here surmounted the ,alleghanies and invaded the valley of the ,susquehanna4 ,analogous deposits of unusual amounts of gravel1 occurring in streams flowing southward from the glaciated region1 occur at ,great ,valley1 ,little ,valley1 and ,steamburg in ,cattaraugus ,county1 ,new ,york1 and at ,russelburg and ,garland in ,warren ,county1 ,pennsylvania1 also at ,titusville and ,franklin in ,venango ,county1 and at ,wampum in ,lawrence ,county1 of the same ,state4 ,as a rule1 ,professor ,lewis and myself found it more difficult to determine with accuracy the exact point to which the ice extended in the axis of these south-flowing valleys than we did upon the highlands upon either side2 and1 in looking for the positive indications of direct ice-action in these lines of drainage1 we were almost always led up the valley to a considerable distance inside of the line4 ,this arose from our inexperience in interpreting the phenomena1 or rather from our inattention to the well-known determining facts in the problem4 ,on further reflection it readily appeared that this was as it should be4 ,the ice-front1 instead of extending farther down in a narrow valley than on the adjoining highlands 7where they are of only moderate elevation7 ought not to extend so far1 for the subglacial streams would not only wear away the ice of themselves1 but would admit the air into the tunnels formed by them so as to melt the masses both from below and from above1 and thus cause a recession of the front4 ,if we had understood this principle at the beginning of our survey1 it would have saved us much perplexity and trouble4 ,a single further illustration of this point will help to an understanding of many references which will hereafter be made to the water deposits which accumulated in the lines of drainage running southward from the glaciated area4 ,at ,warren1 ,pa41 ,conewango ,creek1 which is the outlet from ,chautauqua ,lake1 enters the ,alleghany ,river after flowing for a number of miles in a deep valley with moderate slopes4 ,in ascending the creek from ,warren1 the gravel terraces1 which rise twenty-five or thirty feet above high-water mark1 rapidly increase in breadth and height1 and the pebbles become more and more coarse4 ,after a certain distance the regular terraces begin to give place to irregular accumulations of gravel in ridges and knobs4 ,in the lower portion of the valley no pebbles could be found which were scratched4 ,up the valley a few miles pebbles were occasionally discovered which showed some slight indications of having been scratched1 but which had been subjected to such an amount of abrasion by water-action as almost to erase the scratches4 ,on reaching ,ackley's ,station1 the stream is found to be cutting through a regular terminal moraine1 extending across the valley and full of clearly marked glaciated stones4 ,above this terminal moraine the terraces and gravel ridges which had characterised the valley below disappear1 giving place to long stretches of level and swampy land1 which had been subject to overflow4 ,something similar to this so often appears1 that there can be no question as to its meaning1 which is1 that during the farthest extent of the ice the front rested for a considerable period of time along the line marked by the terminal moraine4 ,during this period there occurred both the accumulation of the moraine and of the gravel terraces in the valley below1 due to the vast flow of water emerging from the ice-front1 especially during the period when it was most rapidly melting away4 ,upon the retreat of the ice1 the moraine constituted a dam which has not yet been wholly worn away4 ,for a while the water was so effectually ponded back by this as to form a lake1 which has since become filled up with sediment and accumulations of peat4 ,from this it is evident1 also1 that when the ice began to retreat1 the retreat was so continuous and rapid that no parallel terminal moraines were formed for many miles4 ,before leaving this section we will summarise the leading facts concerning the glacial phenomena north of ,pennsylvania and ,new ,jersey4 ,from the observations of ,professor ,smock1 it appears that1 from the southern margin the ascent to the summit of the ice-sheet was pretty rapid2 the depth one mile back from the margin being not much less than a thousand feet4 ,northward the angle of the slope diminished1 and the glacier surface approximated to a great level plain4 ,the distance between the high southwestern peaks of the ,catskills and ,pocono ,knob in ,pennsylvania is sixty miles4 ,the difference in the elevation of the glacier could not have exceeded a thousand feet1,,bb that is1 the slope of the surface was about seventeen feet to the mile4 ,footnote ,,bb3 ,american ,journal of ,science1 vol4 cxxv1 #ahhc1 p4 #cci et seq4 ,professor ,dana estimates the thickness of the ice in southern ,connecticut to have been between fifteen hundred and two thousand feet4 ,attempts to calculate the thickness of the ice farther north1 except from actual discovery of glacial action on the summits of the mountains1 are based upon uncertain data with reference to the slope necessary to secure glacial movement4 ,in the ,alps the lowest mean slopes down which glaciers move are about two hundred and fifty feet to a mile2 but in ,greenland1 ,jensen found the slope of the ,frederickshaab ,glacier to be only seventy-five feet to the mile1 while ,helland found that of the ,jakobshavn ,glacier to be only forty-five feet4 ,it is doubtful if even that amount is necessary to secure a continental movement of ice1 since1 as already remarked1 it is unsafe to draw inferences concerning the movements of large masses of ice from those of smaller masses in more constricted areas4 ,we have seen1 from the glacial deposits on the top of ,mount ,washington1 that over the northern part of ,new ,england the ice was more than a mile in depth4 ,we have no direct evidence of the depth of the stream which surrounded the ,adirondack ,mountains4 ,nor1 on the other hand1 are we certain that the ,catskills were not completely enveloped in ice1 though most observers1 reasoning from negative evidence1 have supposed that to be the case4 ,but from the facts stated concerning the boulders along the glacial boundary in ,pennsylvania1 it is certain that the ice was deep enough to surmount the ridge of the ,alleghanies where they are two thousand and more feet in height4 ,at the least calculation the ice must have been five hundred feet thick1 in order to secure the movement of which there is evidence across the ,appalachian range4 ,supposing this to be the height of the ice above the sea on the crest of the ,alleghanies1 and that the slope of the surface of the ice-sheet was as moderate as ,professor ,smock has estimated it 7namely seventeen feet to the mile71 the ice would be upwards of six thousand feet in thickness in the latitude of the ,adirondacks1 which corresponds closely with the positive evidence ,ave have from the mountains in ,new ,england4 ,a study of the map of ,new ,york will make it easy to understand the distribution of some interesting glacial marks over the ,state4 ,the distance along the ,hudson from the glacial boundary in the vicinity of ,new ,york to the valley of the ,mohawk is about one hundred and sixty miles4 ,prom the glacial boundary at ,salamanca1 ,n4 ,y41 to the same valley1 is not over eighty miles4 ,it is easy to see1 therefore1 that when1 in advancing1 the ice moved southward past the ,adirondacks1 the east end of the valley of the ,mohawk was reached and closed by the ice1 while at the west end of ,lake ,ontario the ice-front was still in ,canada4 ,thus the drainage1 which naturally followed the course of the ,st4 ,lawrence1 would first be turned through the ,mohawk4 ,afterwards1 when the ,mohawk had been closed by ice1 the vast amount of ponded water was compelled to seek a temporary outlet over the lower passages leading into the ,susquehanna or into the ,alleghany4 ,a number of such passages exist4 ,one can be traced along the line of the old canal from ,utica to ,binghamton1 whose highest level is not far from eleven hundred feet4 ,another lies in a valley leading south of ,cayuga ,lake1 whose highest point1 at ,wilseyville1 is nine hundred and forty feet above tide4 ,another leads south to the ,chemung ,river from ,seneca ,lake1 whose highest point1 at ,horseheads1 is less than nine hundred feet above tide4 ,the cols farther west are somewhat more elevated2 the one at ,portage1 leading from the ,genesee ,river into the ,canisteo1 being upwards of thirteen hundred feet1 and that of ,dayton1 leading from ,cattaraugus ,creek into the ,conewango1 being about the same4 ,of other southern outlets farther west we will speak later on4 ,fixing our minds now upon the region under consideration1 in the southern part of the ,state of ,new ,york1 we can readily see that a glacial lake must have existed in front of the ice while it was advancing1 until it had reached the river-partings between the ,mohawk and the ,st4 ,lawrence ,rivers on the north and the ,susquehanna and ,alleghany ,rivers on the south4 ,after the ice had attained its maximum extension1 and was in process of retreat1 there would be a repetition of the phenomena1 only they would occur in the reverse order4 ,the glacial markings which we see are1 of course1 mainly those produced during the general retreat of the ice4 ,the ,susquehanna ,river stretching out its arms--the ,chenango and ,chemung ,rivers--to the east and the west1 evidently serves as a line of drainage for the vast glacial floods4 ,these floods have left1 along their courses1 extensive elevated gravel terraces1 with much material in them which is not local1 but which has been washed out of the direct glacial deposits from the far north4 ,the east-and-west line of the water-parting throughout the ,state is characterised by excessive accumulations of glaciated material1 forming something like a terminal moraine1 and is designated by ,president ,chamberlin as the terminal moraine of the second ,glacial epoch1 corresponding1 as he thinks1 to the interior line already described as characterising the south shore of ,new ,england4 ,in the central part of ,new ,york the remarkable series of ,finger ,lakes1 tributary to ,lake ,ontario and emptying into it through the ,oswego and ,genesee ,rivers1 all have a glacial origin4 ,probably1 however1 they are not due in any great degree to glacial erosion1 but they seem to occupy north-and-south valleys which had been largely formed by streams running towards the ,st4 ,lawrence when there was1 by some means 7probably through the ,mohawk ,river71 a much deeper outlet than now exists1 but which has been filled up and obliterated by glacial dbris4 ,the ice-movement naturally centred itself more or less in these north-and-south valleys1 and hence somewhat enlarged them1 but probably did not deepen them4 ,the ice1 however1 did prevent them from becoming filled with sediment1 and on its final retreat gave place to water4 ,between these lakes and ,lake ,ontario1 also1 and extending east and west nearly all the way from ,syracuse to ,rochester1 there is a remarkable series of hills1 from one hundred to two or three hundred feet in height1 composed of glacial dbris4 ,but while the range extends east and west1 the axis of the individual hills lies nearly north and south4 ,these are probably remnants of a morainic accumulation which were made during a pause in the first advance of the ice1 and were finally sculptured into their present shape by the onward movement of the ice4 ,these are really drumlins1 similar to those already described in northeastern ,massachusetts and southeastern ,new ,hampshire4 ,in the valley of central ,new ,york these have determined the lines of drainage of the ,finger ,lakes1 and formed dams across the natural outlets of nearly all of them4 ,north of the ,state of ,new ,york the innumerable lakes in ,canada are all of glacial origin1 being mostly due to depressions of the nature of kettle-holes1 or to the damming up of old outlets by glacial deposits4 ,a pretty well-marked line of moraine hills1 formed probably as terminal deposits in the later stages of the ,ice age1 runs from near the eastern end of ,lake ,ontario to the ,georgian ,bay1 passing south of ,lake ,simcoe4 ,the ,mississippi ,basin4 ,the physical geography of the glaciated region north of the ,ohio ,river is so much simpler than that of ,new ,england and the ,middle ,states1 that its characteristics can be briefly stated4 ,ohio1 ,indiana1 and ,illinois are covered with nearly parallel strata of rock mostly of the ,carboniferous age4 ,in general1 the surface slopes gently to the west2 the average elevation of ,ohio being about a thousand feet above tide1 while that of the ,great ,lakes to the north and of the middle portion of the ,mississippi ,valley is less than six hundred feet4 ,the glacial deposits are spread in a pretty even sheet over the area which was reached by the ice in these ,states1 and the lines of moraine1 of which a dozen or more have been partially traced in receding order1 are much less clearly marked than they are in ,new ,england1 or in ,michigan1 and the ,states farther to the northwest4 ,the line marking the southern limit attained by the ice of the ,glacial period in these three ,states is as follows3 ,entering ,ohio in ,columbiana ,county1 about ten miles north of the ,ohio ,river1 the glacial boundary runs westward through ,new ,lisbon to ,canton in ,stark ,county1 and thence to ,millersburg in ,holmes ,county4 ,a few miles west of this place it turns abruptly south1 passing through ,danville in ,knox ,county1 ,newark in ,licking ,county1 ,lancaster in ,fairfield ,county1 to ,adelphi in ,ross ,county4 ,thence bearing more westward it passes through ,chillicothe to southeastern ,highland ,county and northwestern ,adams1 reaching the ,ohio ,river near ,ripley1 in ,clermont ,county4 ,thence1 following the north bank of the ,ohio ,river to ,cincinnati1 it crosses the river1 and after extending through the northern part of ,boone ,county1 ,kentucky1 and recrossing the river to ,indiana1 not far from ,rising ,sun1 it again follows approximately the north bank of the river to within about ten miles of ,louisville1 ,ky41 where it bends northward running through ,clarke1 ,scott1 ,jackson1 ,bartholomew1 and ,brown ,counties to ,martinsville1 in ,morgan ,county1 where it turns again west and south and follows approximately the ,west ,branch of the ,white ,river through ,owen1 ,greene1 and ,knox ,counties1 where it crosses the main stream of ,white ,river1 and1 continuing through ,gibson and ,posey ,counties1 crosses the ,wabash ,river near ,new ,harmony4 ,in ,illinois the line still continues southwesterly through ,white1 ,gallatin1 ,saline1 and ,williamson ,counties1 where it reaches its southern limit near ,carbondale1 in latitude #cg #dj'1 and from this point trends northwestward1 approximately following the northeastern bluff of the ,mississippi ,river1 to the vicinity of ,carondelet1 ,mo41 a short distance south of ,st4 ,louis4 ,beyond the ,mississippi the line follows approximately the course of the ,missouri ,river across ,missouri1 and continues westward to the vicinity of ,manhattan1 in ,kansas1 where it turns northward1 keeping about a hundred miles west of the ,missouri ,river1 through eastern ,kansas and ,nebraska1 and striking the river near the mouth of the ,niobrara1 in ,south ,dakota4 ,from there the line follows approximately the course of the ,missouri ,river to the vicinity of ,fort ,benton1 in northwestern ,montana1 where the line again bears more northward1 running into ,british ,america4 ,it is still in dispute whether the ice extended from the eastern centre far enough west to join the ice-movement from the ,rocky ,mountain plateau4 ,dr4 ,george ,m4 ,dawson,,bc is of the opinion that it did not1 but that there was a belt of a hundred miles or more1 east of the ,rocky ,mountains1 which was never covered by true glacial ice4 ,mr4 ,upham,,bd is equally confident that the two ice-movements became confluent1 and united upon the western plateau of ,manitoba4 ,the opportunity for such a difference of opinion arises in the difficulty sometimes encountered of distinguishing between a direct glacial deposit and a deposit taking place in water containing boulder-laden icebergs4 ,where ,mr4 ,upham supposes the ice-fields of the east and of the west to have been confluent in western ,manitoba1 ,dr4 ,dawson supposes there was an extensive subsidence of the land sufficient to admit the waters of the ocean4 ,leaving this question for the present undetermined1 we will now rapidly summarise the glacial phenomena west of the third meridian from ,washington 7which corresponds nearly with the western boundary of ,pennsylvania71 and east of the ,rocky ,mountains4 ,footnote ,,bc3 ,transactions of the ,royal ,society of ,canada1 vol4 viii1 sec4 iv1 pp4 #ed-gd4 ,footnote ,,bd3 ,american ,geologist1 vol4 vi1 ,september1 #ahij2 ,bulletin of the ,geological ,society of ,america1 vol4 ii1 pp4 #bdc-bgf4 ,that the glacial movement extended to the southern boundary just delineated is established by the presence down to that line of all the signs of glacial action1 and their absence beyond4 ,glacial groovings are found upon the freshly uncovered rock surfaces at frequent intervals in close proximity to the line all along its course1 while granitic boulders from the far north are scattered1 with more or less regularity1 over the whole intervening space between this line and the ,canadian highlands4 ,i have already referred to a boulder of jasper conglomerate found in ,boone ,county1 ,kentucky1 which must have come from unique outcroppings of this rock north of ,lake ,huron4 ,granitic boulders from the ,lake ,superior region are also found in great abundance at the extreme margin mentioned in southern ,illinois4 ,west of the ,missouri ,river it is somewhat more difficult to delineate the boundary with accuracy1 on account of an enveloping deposit of fine loam1 technically called loess4 ,loess is very abundant in the whole valley of the ,missouri ,river below ,yankton1 ,south ,dakota1 being for a long distance in the vicinity of the river a hundred feet or more in depth4 ,over northern ,missouri and southern ,illinois the deposit is nearly continuous1 but less in depth1 and everywhere in that region tends to hide from view the unstratified glacial deposit continuously underlying it4 ,a single instance of personal experience will illustrate the condition of things4 ,while going south from ,chicago1 in search of the southern limit of glacial action1 ,i stopped off from the train at ,du ,quoin1 about forty miles north of where ,i subsequently found the boundary4 ,here the whole surface was covered with loess1 two or three feet in depth4 ,below this was a gravelly soil1 three or four feet in thickness1 which contained many scratched pebbles of granite4 ,a well which had recently been dug1 reached the rock at a depth of twenty feet1 and revealed a beautifully polished and scratched surface1 betraying1 beyond question1 the action of glacial ice4 ,as we shall show a little later1 it is probable that1 about the time the ice of the ,glacial period had reached its maximum development1 this area1 which is covered with loess1 was depressed in level1 and remained under water during a considerable portion of the period when the ice-front was retreating4 ,illustration3 ,fig4 #cc4--,western face of the kettle-moraine1 near ,eagle1 ,waukesha ,county1 ,wisconsin4 7,from a photograph by ,president ,t4 ,c4 ,chamberlain1 ,united ,states ,geological ,survey47 ,to such an extent is this portion of the area included in southern ,iowa1 northern ,missouri1 southern ,illinois1 and the extreme southern portions of ,indiana and ,ohio covered with loess1 that it has been difficult to determine the relation of its underlying glacial deposits to the more irregular deposits found farther north4 ,at an early period of recent investigations1 while making a geological survey of the ,state of ,wisconsin1 ,president ,t4 ,c4 ,chamberlin fixed upon the line of moraine hills1 which can be seen upon our map1 running southward between ,green ,bay and ,lake ,michigan1 and sweeping around in a curve to the right1 passing south of ,madison and northward along the line of ,wisconsin ,river1 and in another curve to the left1 around the southern end of ,lake ,michigan1 as the terminal moraine of the second ,glacial epoch4 ,in ,wisconsin the character of this line of moraine hills had been discovered and described by ,colonel ,charles ,whittlesey1 in #ahff4 ,it was first named the kettle-moraine1 because of the frequent occurrence in it of kettle-holes4 ,this line of moraine hills has been traced with a great degree of confidence across the entire glaciated area1 as shown upon our map1 but it is not everywhere equally distinct1 and1 as will be observed1 follows a very irregular course4 ,beginning in ,ohio we find it coinciding nearly with the extreme glacial boundary until it reaches the valley of the ,scioto ,river1 on the sixth meridian west from ,washington1 where it begins to bear northward and continues in that direction for a distance of sixty or seventy miles1 and then turns southward again in the valley of the ,miami1 having formed between these two valleys a sort of medial moraine4,,be ,a similar medial moraine had also been noted by ,president ,chamberlin between the valleys of the ,grand and ,cuyahoga ,rivers1 in the eastern part of ,ohio4 ,indeed1 for the whole distance across ,ohio and ,indiana1 this moraine occurs in a series of loops pointing to the south1 corresponding in general to the five gentle valleys which mark the territory1 namely1 those of the ,grand and ,mahoning ,rivers2 the ,sandusky and ,scioto ,rivers2 the ,great ,miami ,river2 the ,white ,river2 and the ,maumee and ,wabash ,rivers4 ,everywhere1 however1 over this area these morainic accumulations approximate pretty closely to the extreme boundary of the glaciated region4 ,footnote ,,be3 ,see map at the beginning of the chapter4 ,in ,illinois ,president ,chamberlin's original determination of the moraine fixed it near the southern end of ,lake ,michigan1 as shown upon our map1 but ,mr4 ,frank ,leverett has subsequently demonstrated that there is a concentric series of moraines south of this1 reaching across the ,state1 7but somewhat obscured by superficial accumulations of loess referred to7 and extending nearly to the latitude of ,st4 ,louis4 ,west of ,wisconsin ,president ,chamberlin's terminal moraine of the second ,glacial epoch bends southward through eastern ,minnesota1 and1 sweeping down through central ,iowa1 forms1 near the middle of the northern part of that ,state1 a loop1 having its southern extremity in the vicinity of ,des ,moines4 ,the western arm of this loop runs through ,minnesota in a northwesterly direction nearly parallel with the upper portion of the valley of the ,minnesota1 until reaching the latitude of the head-waters of that river1 where1 in the vicinity of the ,sisseton ,agency1 in ,dakota1 it turns to the south by an acute angle1 and makes a loop in that ,state1 extending to the vicinity of ,yankton1 and with the valley of the ,james ,river as its axis4 ,the western arm of this loop follows pretty closely the line of the eastern edge of the trough of the ,missouri ,river1 constituting what is called the ,missouri ,coteau1 which continues on as a well-marked line of hills running in a northwesterly direction far up into the ,dominion of ,canada4 ,one of the most puzzling glacial phenomena in the ,mississippi ,valley is the driftless area which occupies the southeastern portion of ,minnesota1 the southwestern part of ,wisconsin1 and the northwestern corner of ,iowa1 as delineated upon our map4 ,this is an area which1 while being surrounded on every side by all the characteristic marks of glaciation1 is itself conspicuous for their entire absence4 ,its rocks preserve no glacial scratches and are covered by no deposits of till1 while northern boulders avoided it in their journey to more southern latitudes4 ,the reason for all this is not evident in the topography of the region4 ,the land is not higher than that to the north of it1 nor is there any manifest protection to it by the highlands south of ,lake ,superior4 ,nor yet is there any reason to suppose that any extensive changes of level in former times seriously affected its relations to the surrounding country4 ,professor ,dana1 however1 has called attention to the fact that even now it is in a region of comparatively light precipitation1 suggesting that the snow-fall over it may always have been insignificant in amount4 ,but this could scarcely account for the failure of the great ice-wave of the north to overrun it4 ,we are indebted again to the sagacity of ,president ,chamberlin in suggesting the true explanation4 ,by referring to the map it will be noticed that this area sustains a peculiar relation to the troughs of ,lake ,michigan and ,lake ,superior1 while from the arrangements of the moraines in front of these lakes it will be seen that these lake basins were prominent factors in determining the direction of the movement of the surplus ice from the north4 ,it is the more natural that they should do so because of their great depth1 their bottoms being in both cases several hundred feet below the present water-level1 reaching even below the level of the sea4 ,these broad1 deep channels seem to have furnished the readiest outlet for the surplus ice of the ,north1 and so to have carried both currents of ice beyond this driftless area before they became again confluent4 ,the slight elevation south of ,lake ,superior served to protect the area on account of the feebleness of direct movement made possible by the strength of these diverging lateral ice-currents4 ,the phenomenon is almost exactly what occurs where a slight obstruction in a river causes an eddy and preserves a low portion of land below it from submergence4 ,a glance at the map will make it easily credible that an ice-movement south of ,manitoba1 becoming confluent with one from ,lake ,superior1 pushed far down into the ,missouri ,valley and spread eastward to the ,mississippi ,river1 south of the unglaciated driftless area1 and there became confluent with a similar movement which had been directed by the valleys of ,lake ,michigan and ,lake ,erie4 ,there can be little doubt that ,president ,chamberlin's explanation is in the main correct1 and we have in this another illustration of the analogy between the behaviour of moving ice and that of moving water4 ,illustration3 ,fig4 #cd4--,section of the east-and-west glacial furrows1 on ,kelly's ,island1 preserved by ,mr4 ,younglove4 ,fine sediment rests immediately on the rock1 with washed pebbles at the surface4 ,the accompanying illustrations will give a better idea than words can do of the celebrated glacial grooves on the hard limestone islands near ,sandusky1 in the western part of ,lake ,erie4 ,through the interest aroused in them by an excursion of the ,american ,association for the ,advancement of ,science1 while meeting in ,cleveland1 ,ohio1 in #ahhh1 the ,kelly ,island ,lime and ,transport ,company1 of which ,mr4 ,m4 ,c4 ,younglove is the president1 has been induced to deed to the ,western ,reserve ,historical ,society for preservation a portion of one of the most remarkable of the grooves still remaining4 ,the portion of the groove preserved is thirty-three feet across1 and the depth of the cut in the rock is seventeen feet below the line1 extending from rim to rim4 ,originally there was probably here a small depression formed by preglacial water erosion1 into which the ice crowded the material1 which became its graving-tool1 and so the rasping and polishing went on in increasing degree until this enormous furrow is the result4 ,the groove1 however1 is by no means simple1 but presents a series of corrugations merging into each other by beautiful curves4 ,when exposed for a considerable length it will resemble nothing else so much as a collection of prostrate ,corinthian columns lying side by side on a concave surface4 ,the direction of these grooves is a little south of west1 corresponding to that of the axis of the lake4 ,this is nearly at right angles to the course of the ice-scratches on the summit of the water-shed south of this1 between the lake and the ,ohio ,river4 ,the reason for this change of direction can readily be seen by a little attention to the physical geography4 ,the highlands to the south of the lake rise about seven hundred feet above it4 ,when the ,ice period was at its climax and overran these highlands1 the ice took its natural course at right angles to the terminal moraine and flowed southeast according to the direction indicated by the scratches on the summit2 but when the supply of ice was not sufficient to overrun the highlands1 the obstruction in front turned the course and the resultant was a motion towards ,toledo and the ,maumee ,valley1 where in the vicinity of ,fort ,wayne an extensive terminal moraine was formed4 ,illustration3 ,fig4 #ce4--,same as the preceding4 7,courtesy of ,m4 ,c4 ,younglove47 ,the much-mooted question of a succession of glacial epochs finds the most of its supporting facts in the portion of the glaciated area lying west of ,pennsylvania4 ,that there have been frequent oscillations of the glacial front over this area is certain4 ,but it is a question whether the glacial deposits south of this distinct line of moraine hills are so different from those to the north of it as to necessitate the supposition of two entirely distinct glacial epochs4 ,this can be considered most profitably here4 ,the following are among the points with reference to which the phenomena south of the moraine just delineated differ from those north of the line3 #a4 ,the glacial deposits to the south appear to be distributed more uniformly than those to the north4 ,to the north the drift is often accumulated in hills1 and is dotted over with kettle-holes1 while to the south these are pretty generally absent4 ,any one travelling upon a line of railroad which traverses these two portions of the glaciated area as indicated upon our map can easily verify these statements4 #b4 ,the amount of glacial erosion seems to be much less south of the line of moraine hills delineated than north of them4 ,still1 glacial stri are found1 almost everywhere1 close down to the extreme margin of the glaciated area4 #c4 ,the gravel deposits connected with the drainage of the ,glacial period are much less abundant south of the so-called terminal moraine of the second ,glacial period than they are north of it4 ,south of this moraine the water deposits attributed to the ,glacial period are of such fine silt as to indicate slow-moving currents over a gentle low slope of the surface4 #d4 ,the glacial deposits to the south are more deeply coloured than those to the north1 showing that they have been longer exposed to oxidising agencies4 ,even the granitic boulders show the marks of greater age south of this line1 being disintegrated to a greater extent than those to the north4 #e4 ,and1 finally1 there occur1 over a wide belt bordering the so-called moraine hills of the second ,glacial epoch1 extensive intercalated beds of vegetal deposits4 ,among the earliest of these to be discovered were those of ,montgomery ,county1 ,ohio1 where1 in #ahgj1 ,professor ,orton1 of the ,ohio ,survey1 found at ,germantown a deposit of peat fourteen feet thick underneath ninety-five feet of till1 and there seem also to be glacial deposits underneath the peat as well as over it4 ,the upper portion of the peat contains much undecomposed sphagnous mosses1 grasses1 and sedges1 and both the peat and the clayey till above it contain many fragments of coniferous wood which can be identified as red cedar 7,juniperus ,virginianus74 ,in numerous other places in that portion of ,ohio fresh-appearing logs1 branches1 and twigs of wood are found underneath the till1 or mingled with it1 much as boulders are4 ,near ,darrtown1 in ,butler ,county1 ,ohio1 red cedar logs were found under a covering of sixty-five feet of till1 and so fresh that the perfume of the wood is apparently as strong as ever4 ,similar facts occur in several other counties in the glaciated area of southern ,ohio and southern ,indiana4 ,professor ,collett reports that all over southwestern ,indiana peat1 muck1 rotted stumps1 branches1 and leaves of trees are found from sixty to one hundred and twenty feet below the surface1 and that these accumulations sometimes occur to a thickness of from two to twenty feet4 ,illustration3 ,fig4 #cf4--,section of till near ,germantown1 ,ohio1 overlying thick bed of peat4 ,the man in the picture stands upon a shelf of peat from which the till has been eroded by the stream4 ,the dark spot at the right hand of the picture1 just above the water1 is an exposure of the peat4 ,the thickness of the till is ninety-five feet4 ,the partial stratification spoken of in the text can be seen about the middle of the picture4 ,the furrows up and down had been made by recent rains4 7,united ,states ,geological ,survey47 7,wright47 ,farther to the northwest similar phenomena occur4 ,professor ,n4 ,h4 ,winchell has described them most particularly in ,fillmore and ,mower ,counties1 ,minnesota1 from which they extend through a considerable portion of ,iowa4 ,in the above counties of ,minnesota a stratum of peat from eighteen inches to six or eight feet in thickness1 with much wood1 is pretty uniformly encountered in digging wells1 the depth varying from twenty to fifty feet4 ,this county is near the highest divide in the ,state of ,minnesota1 and from it flow the sources of the streams to the north1 south1 and east4 ,the wood encountered in this stratum indicates the prevalence f coniferous trees1 and the peat mosses indicate a cool and moist climate4 ,nor are intercalated vegetable deposits absent from the vast region farther north over the area that drains into ,hudson ,bay4 ,at ,barnesville1 in ,clay ,county1 ,minnesota1 which lies in the valley of the ,red ,river of the ,north1 and also in ,wilkin ,county in the same valley1 tamarack wood and sandy black mud containing many snail-shells have been found from eight to twelve feet below a surface of till2 and ,dr4 ,robert ,bell reports the occurrence of limited deposits of lignite between layers of till1 far to the northwest1 in ,canada1 and even upon the southern part of ,hudson ,bay2 while ,mr4 ,j4 ,b4 ,tyrrell reports,,bf many indications of successive periods of glaciation near the northern end of the ,duck ,mountain4 ,the most characteristic indications which he had witnessed consisted of stratified beds of silt1 containing fresh-water shells1 with fragments of plants and fish similar to those living in the lakes of the region at the present time4 ,footnote ,,bf3 ,bulletin of the ,geological ,society of ,america1 vol4 i1 pp4 #cie-daj4 ,reviewing these facts with reference to their bearing upon the point under consideration1 we grant1 at the outset1 that they do indicate a successive retreat and readvance of the ice over extensive areas4 ,this is specially clear with respect to the vegetal deposits interstratified with beds of glacial origin4 ,but the question at issue concerning the interpretation of these phenomena is1 ,do they necessarily indicate absolutely distinct glacial epochs separated by a period in which the ice had wholly disappeared from the glaciated area to the north8 ,that they do1 is maintained by ,president ,chamberlin and many others who have wide acquaintance with the facts4 ,that they do not certainly indicate a complete disappearance of the ice during an extensive interglacial epoch1 is capable1 however1 of being maintained1 without forfeiting one's rights to the respect of his fellow-geologists4 ,the opposite theory is thus stated by ,dr4 ,robert ,bell3 ,it appears as if all the phenomena might be referred to one general ,glacial period1 which was long continued1 and consequently accompanied by varying conditions of temperature1 regional oscillations of the surface1 and changes in the distributions of sea and land1 and in the currents in the ocean4 ,these changes would necessarily give rise to local variations in the climate1 and might permit of vegetation for a time in regions which need not have been far removed from extensive glaciers4,,bg ,footnote ,,bg3 ,bulletin of the ,geological ,society of ,america1 vol4 i1 pp4 #bhg-caj4 ,at my request1 ,professor ,j4 ,e4 ,todd1 of ,iowa1 whose acquaintance with the region is extensive1 has kindly written out for me his conclusions upon this subject1 which ,i am permitted to give in his own words3 ,i am not prepared to write as ,i would like concerning the forest-beds and old soils4 ,i will1 however1 offer the following as a partial report4 ,i have come to think that there is considerable confusion on the subject4 ,i believe there are five or six different things classed under one head4 #a4 ,recent ,much and ,soils4--,the finest example ,i have found in the whole ,missouri ,valley was twenty feet below silt and clay1 in a basin inside the outer moraine1 near ,grand ,view1 ,south ,dakota4 ,from my examination of the reported old soil near ,albia1 ,iowa1 ,i think the most rational way of reconciling the conflicting statements concerning it is that it also belongs to this class4 #b4 ,peat or ,soil under ,loess4--,this does not signify much if the loess was formed in a lake subject to orographic oscillations1 or if1 as ,i am coming to believe1 it is a fluviatile deposit of an oscillating river like the ,hoang-,ho on the great ,chinese plain4 ,it at least does not mean an interglacial epoch4 #c4 ,wood and ,dirt rearranged1 not in situ4--,this occurs either in subaqueous or in subglacial deposits4 ,i have found drift-wood in the lower layers of the loess here1 but not in situ4 ,i have frequently found traces of wood in till in ,dakota1 but always in an isolated way4 ,i think1 from reading statements about the deposits in eastern ,iowa1 that most if not all of the cases are of this sort4 ,two things have conspired to lead to this error3 one1 the influence of ,croll's speculation2 and the other1 the easy inference of many well-diggers1 and especially well-borers1 that what they pass through are always in layers4 ,in this way a log becomes a forest-bed4 ,scattered logs and muck fragments occurring frequently in a region1 though at different levels1 are readily imagined by an amateur geologist to be one continuous stratum antedating the glacier or floods 7as the case may be in that particular region71 when1 in fact1 it has been washed down from the margin of the transporting agent and is contemporaneous with it4 ,i suspect the prevalence of wood in eastern ,iowa may be traced to a depression of the driftless region during the advance of the glacier1 so as to bring the western side of that area more into the grasp of glacial agencies4 #d4 ,peat between ,subglacial ,tills4--,if cases of this sort are found1 they are in ,illinois1 ,indiana1 and ,ohio4 ,professor ,worthen insisted that there were no interglacial soils or forest-beds in ,illinois2 and in the cases mentioned in the ,state reports he repeatedly explains the sections given by his assistants1 so as to harmonize them with that statement4 ,i think he usually makes his explanations plausible4 ,he was very confident in referring most of them1 to preglacial times4 ,his views1 ,i suppose1 will be published in the long-delayed volume1 now about to be issued4 #e4 ,vegetable ,matter between ,glacial ,till and ,underlying ,berg ,till or other ,drift ,deposits4--,when one remembers that the front of the great ice-sheet may have been as long in reaching its southern boundary as in receding from it1 and with as many advance and retrograde movements1 we can easily believe that much drift material would have outrun the ice and have formed deposits so far ahead of it that vegetation would have grown before the ice arrived to bury it4 #f4 ,preglacial ,soils1 etc4--,i believe that this will be found to include most in southern ,ohio1 if not in ,illinois1 as ,worthen claimed4 ,the phenomena of the ,glacial period are too vast either to have appeared or to have disappeared suddenly4 ,by whatever cause the great accumulation of ice was produced1 the advance to the southward must have been slow and its disappearance must have been gradual1 though1 as we shall show a little later1 the final retreat of the ice-front occupied but a short time relatively to the whole period which has elapsed since4 ,as we shall show also1 the advent of the ,ice period was probably preceded and accompanied by a considerable elevation of the northern part of the continent ,whether this elevation was contemporaneous upon both sides of the continent is perhaps an open question2 but with reference to the area east of the ,rocky ,mountains1 which is now under consideration1 the centre of elevation was somewhere south of ,hudson ,bay4 ,putting together what we know1 from the nature of the case1 concerning the accumulation and movement of glacial ice1 and what we know from the relics of the great glacial invasion1 which have enabled us to determine its extent and the vigour of its action1 the course of events seems to have been about as follows3 ,throughout the ,tertiary period a warm climate had prevailed over ,british ,america1 ,greenland1 and indeed over all the lands in proximity to the north pole1 so far as explorers have been able to penetrate them4 ,the vegetation characterizing these regions during the ,tertiary period indicates a temperature about like that which now prevails in ,north ,carolina and ,virginia4 ,whatever may be said in support of the theory that the ,glacial period was produced by astronomical causes1 in view of present facts those causes cannot be regarded as predominant2 at most they were only co-operative4 ,the predominant cause of the ,glacial period was probably a late ,tertiary or post-,tertiary elevation of the northern part of the continents1 accompanied with a subsidence in the central portion4 ,of such a subsidence in the ,isthmus of ,panama indications are thought to be afforded by the occurrence of late ,tertiary or1 more probably1 post-,tertiary sea-shells at a considerable elevation on the divide along the ,isthmus of ,panama1 between the ,atlantic and ,pacific ,oceans4 ,of this we shall speak more fully in a later chapter4 ,fixing our thoughts upon what is known as the ,laurentian plateau1 which1 though now in the neighbourhood of but two thousand feet above the sea1 was then much higher1 we can easily depict in imagination the beginnings of the great ,laurentide ,glacier1 which eventually extended to the margin already delineated on the south and southwest in the ,united ,states1 and spread northward and eastward over an undetermined area4 ,year after year and century after century the accumulating snows over this elevated region consolidated into glacial ice and slowly pushed outward the surplus reservoirs of cold4 ,for a long time this process of ice-accumulation may have been accompanied by the continued elevation of the land1 which1 together with the natural effect of the enlarging area of ice and snow1 would tend to lower the temperature around the margin and to increase still more the central area of accumulation4 ,the vigour of movement in any direction was determined partly by the shape of the valleys opening southward in which the ice-streams would naturally concentrate1 and partly by those meteorological conditions which determine the extent of snow-fall over the local centres of glacial dispersion4 ,for example1 the general map of ,north ,america in the ,ice period indicates that there were two marked subcentres of dispersion for the great ,laurentide ,glacier1 the eastern one being in ,labrador and the western one north of ,lake ,superior4 ,in a general way the southern boundary of the glaciated region in the ,united ,states presents the appearance of portions of two circumferences of circles intersecting each other near the eastern end of ,lake ,erie4 ,these circles1 ,i am inclined to believe1 represent the areas over which a semi-fluid 7or a substance like ice1 which flows like a semi-fluid7 would disperse itself from the subcentres above mentioned4 ,a study of the contour of the country shows that that also1 in a general way1 probably had something to do with the lines of dispersion4 ,the western lobe of this glaciated area corresponds in its boundary pretty closely with the ,mississippi ,valley1 having the ,ohio ,river approximately as its eastern arm and the ,missouri as its western1 with the ,mississippi ,river nearly in its north and south axis4 ,the eastern lobe has its farthest extension in the axis of the ,champlain and ,hudson ,river ,valleys1 its western boundary being thrown more and more northward as the line proceeds to the west over the ,alleghany ,mountains until reaching the longitude of the eastern end of ,lake ,erie2 but this southern boundary is by no means a water-level1 nor is the contour of the country such that it could ever have been a water-level4 ,but it conforms in nearly every particular to what would be the resultant arising from a pretty general southward flow of a semi-fluid from the two subcentres mentioned1 meeting with the obstructions of the ,adirondacks in northern ,new ,york and of the broader ,appalachian uplift in northern ,pennsylvania4 ,how far south the area of glacial accumulation may have extended cannot be definitely ascertained1 but doubtless at an early period of the great ,ice age the northern portions of the ,appalachian range in ,new ,york1 ,new ,england1 ,new ,brunswick1 and ,nova ,scotia became themselves centres of dispersion1 while only at the height of the period did all their glaciers become confluent1 so that there was one continuous ice-sheet4 ,in the western portion of the area covered by the ,laurentide ,glacier1 the depression occupied by the ,great ,lakes1 especially ,lakes ,michigan and ,superior1 evidently had a marked influence in directing the flow of ice during the stages which were midway between the culmination of the ,ice period and both its beginning and its end4 ,this would follow from the great depth of these lakes1 the bottom of ,lake ,michigan being #bhf feet below sea-level1 and that of ,lake ,superior #cge feet1 making a total depth of water of about #ijj and #a1jjj feet respectively4 ,into these oblong depressions the ice would naturally gravitate until they were filled1 and they would become the natural channels of subsequent movement in the direction of their longest diameters1 while the great thickness of ice in them would make them the conservative centres of glacial accumulation and action after the ice had begun to retreat4 ,these deductions from the known nature of ice and the known topography of the region are amply sustained by a study of the detailed map showing the glacial geology in the ,united ,states4 ,but on this we can represent indeed only the marks left by the ice at various stages of its retreat1 since1 as already remarked1 the marks of each stage of earlier advance would be obliterated by later forward movements4 ,we may presume1 however1 that in general the marks left by the retreating ice correspond closely with those actually made and obliterated by the advancing movement4 ,from observations upon the glaciers of ,switzerland and of ,alaska1 it is found that neither the advance nor the retreat of these glaciers is constant1 but that1 in obedience to meteorologic agencies not fully understood1 they advance and retreat in alternate periods1 at one time receding for a considerable distance1 and at other times regaining the lost ground and advancing over the area which has been uncovered by their retreat4 ,m4 ,forel reports1 from the data which he has collected with much care1 that there have been in this century five periods in the ,alpine glaciers3 of enlargement1 from #ahjj 787 to #ahae2 of diminution1 from #ahae to #ahcj2 of enlargement1 from #ahcj to #ahde2 of diminution1 from #ahde to #ahge2 and of enlargement again1 from #ahge onward4 ,he remarks further that these periods correspond with those deduced by ,mr4 ,c4 ,lang for the variations for the precipitations and temperature of the air2 and1 consequently1 that the enlargement of the glaciers has gone forward in the cold and rainy period1 and the diminution in the warm and the dry4,,bh ,footnote ,,bh3 ,american ,journal of ,science1 vol4 cxxxii1 #ahhf1 p4 #gg4 ,when1 now1 we attentively consider the combination of causes necessary to produce the climatic conditions of the great ,ice age of ,north ,america1 we shall be prepared to find far more extensive variations in the progress of the continental glacier1 both during its advance and during its retreat1 than are to be observed in any existing local glaciers4 ,with respect to the arguments adduced in favor of a succession of glacial epochs in ,america the following criticisms are pertinent3 #a4 ,so far as we can estimate1 a temporary retreat of the front1 lasting a few centuries1 would be sufficient to account for the vegetable accumulations that are found buried beneath the glacial deposits in southern ,ohio1 ,indiana1 central ,illinois1 and ,iowa1 while a temporary readvance of the ice would be sufficient to bury the vegetable remains beneath a freshly accumulated mass of till4 ,thus1 as ,dr4 ,bell suggested1 the interglacial vegetal deposits do not necessarily indicate anything more than a temporary oscillation of the ice-front1 and do not carry with them the necessity of supposing a disappearance of the ice from the whole glaciated area4 ,thus the introduction of a whole ,glacial period to account for such limited phenomena is a violation of the well-known law of parsimony1 which requires us in our explanations of phenomena to be content with the least cause which is sufficient to produce them4 ,in the present instance a series of comparatively slight oscillations of the ice-front during a single glacial period would seem to be sufficient to account for all the buried forests and masses of vegetal dbris that occur either in the ,united ,states or in the ,dominion of ,canada4 #b4 ,another argument for the existence of two absolutely distinct glacial periods in ,north ,america has been drawn from the greater oxidation of the clays and the more extensive disintegration of certain classes of the boulders found over the southern part of the glaciated area of the ,mississippi ,valley1 than has taken place in the more northerly regions4 ,without questioning this statement of fact 7which1 however1 ,i believe to be somewhat exaggerated71 it is not difficult to see that the effects probably are just what would result from a single long glacial period brought about by such causes as we have seen to be probably in operation in ,america4 ,for if one reflects upon the conditions existing when the ,glacial period began1 he will see that1 during the long ages of warm climate which characterised the preceding period1 the rocks must have been extensively disintegrated through the action of subarial agencies4 ,the extent to which this disintegration takes place can be appreciated now only by those who reside outside of the glaciated area1 where these agencies have been in uninterrupted action4 ,in the ,appalachian range south of the glaciated region the granitic masses and strata of gneiss are sometimes found to be completely disintegrated to a depth of fifty or sixty feet2 and what seem to be beds of gravel often prove in fact to be horizontal strata of gneiss from which the cementing material has been removed by the slow action of acids brought down by the percolating water4 ,now1 there can be no question that this process of disintegration had proceeded to a vast extent before the ,glacial period1 so that1 when the ice began to advance1 there was an enormous amount of partially oxidised and disintegrated material ready to be scraped off with the first advance of ice1 and this is the material which would naturally be transported farthest to the south2 and thus1 on the theory of a single glacial period1 we can readily account for the greater apparent age of the glacial dbris near the margin4 ,this dbris was old when the ,glacial period began4 #c4 ,with reference to the argument for two distinct glacial periods drawn from the smaller apparent amount of glacial erosion over the southern part of the glaciated area1 we have to remark that that would occur in case of a single ice-invasion as well as in case of two distinct ice-invasions1 in which the later did not extend so far as the former4 ,from the very necessity of the case1 glacial erosion diminishes as the limit of the extent of the glaciation is approached4 ,at the very margin of the glacier1 motion has ceased altogether4 ,back one mile from the margin only one mile of ice-motion has been active in erosion1 while ten miles back from its front there has been ten times as much moving ice actually engaged in erosion1 and in the extreme north several hundred times as much ice1 ,thus it is evident that we do not need to resort to two glacial periods to account for the relatively small amount of erosion exhibited over the southern portion of our glaciated area4 ,at the same time1 it should be said that the indications of active glacial erosion near the margin are by no means few or small4 ,in ,lawrence ,county1 ,pennsylvania1 on the very margin of the glaciated area1 ,mr4 ,max ,foshay,,bi has discovered very extensive glacial grooves1 indicating much vigour of ice-action even beyond the more extensive glacial deposits which ,professor ,lewis and myself had fixed upon as the terminal moraine4 ,in ,highland and ,butler ,counties1 ,ohio1 and in southwestern ,indiana and southern ,illinois1 near the glacial margin1 glacial grooves and stri are as clear and distinct in many cases as can anywhere be found2 while upon the surface of the limestone rocks within the limits of the city of ,st4 ,louis1 where the glacial covering is thin1 and where disintegrating agencies had had special opportunities to work1 ,i found very clear evidences of a powerful ice-movement1 which had planed and scratched the rock surface2 and at ,du ,quoin1 ,illinois1 as already related1 the fragments thrown up from the surface of the rock1 fifty or sixty feet below the top of the soil1 were most beautifully planed and striated4 ,it should be observed1 also1 that this whole area is so deeply covered with dbris that the extent of glacial erosion underneath is pretty generally hid from view4 ,footnote ,,bi3 ,bulletin of the ,geological ,society1 vol4 ii1 pp4 #deg-dfd4 #d4 ,the uniformity of the distribution of the glacial deposits over the southern portion of the glaciated area in the ,mississippi ,valley is partly an illusion1 due to the fact that there was a vast amount of deposition by water over that area during the earlier stages of the ice-retreat4 ,this has been due partly to the gentler slope which would naturally characterise the borders of an area of elevation1 and partly to an extensive subsidence which seems to have begun soon after the ice had reached its farthest extent of motion4 ,it should be borne in mind that at all times a glacier is accompanied by the issue of vast streams of water from its front1 and that these of course increase in volume when the climax has been reached and the ameliorating influences begin to melt away the accumulated mass of ice and to add the volume of its water to that produced by ordinary agencies4 ,as these subglacial streams of water poured out upon the more gentle slopes of the area in front of the ice1 they would distribute a vast amount of fine material1 which would settle into the hollow places and tend to obscure the irregularities of the previous direct glacial deposit4 ,such an instance came clearly under my own observation in the vicinity of ,yankton1 in ,south ,dakota1 where1 upon visiting a locality some miles from any river1 and to which workmen were resorting for sand1 ,i found that the deposit occupied a kettle-hole1 filling it to its brim1 and had evidently been superimposed by a temporary stream of water flowing over the region while the ice was still in partial occupation of it4 ,thus1 no doubt1 in many cases1 the original irregularities of the direct glacial deposits have been obliterated1 even where there has been no general subsidence4 ,but1 in the area under consideration1 the loess1 or loam1 is so extensive that it is perhaps necessary to suppose that the central portions of the ,mississippi ,valley were subjected to a subsidence amounting to about five hundred feet2 so that the glacial streams from the retreating ice-front met the waters of the ocean in southern ,illinois and ,indiana2 thus accounting for the extensive fine silt which has done so much over that region to obscure the glacial phenomena4 ,west of the ,rocky ,mountains4 ,the glacial phenomena in the ,united ,states west of the ,rocky ,mountains must be treated separately1 since ,american geologists have ceased to speak of an all-pervading ice-cap extending from the north pole4 ,but1 as already said1 the glaciation of ,north ,america has proceeded from two definite centres of ice-accumulation1 one of which we have been considering in the pages immediately preceding4 ,the great centre of glacial dispersion east of the ,rocky ,mountains is the region south of ,hudson ,bay1 and the vast ice-field spreading out from that centre is appropriately named the ,laurentide ,glacier4 ,the movement of ice in this glacial system was outward in all directions from the ,laurentian hills1 and extended west several hundred miles1 well on towards the eastern foot of the ,rocky ,mountains4 ,the second great centre of glacial dispersion occupies the vast ,cordilleran region of ,british ,columbia1 reaching from the ,rocky ,mountains on the northeast to the ,coast ,range of the ,pacific on the southwest1 a width of four hundred miles4 ,the length is estimated by ,dr4 ,dawson to be twelve hundred miles4 ,the principal centre of ice-accumulation lies between the fifty-fifth and the fifty-ninth parallel4 ,from this centre the movement was in all directions1 but chiefly to the northwest and to the south4 ,the movement of the ,cordilleran glaciers extended northwest to a distance of three hundred and fifty miles1 leaving their moraines far down in the ,yukon ,valley on the ,lewes and ,pelly ,rivers4,,bj ,southward the ,cordilleran ,glacier moved to a distance of six hundred miles1 extending to the ,columbia ,river1 in the eastern part of the ,state of ,washington4 ,footnote ,,bj3 ,see ,george ,m4 ,dawson1 in ,science1 vol4 xi1 #ahhh1 p4 #ahf1 and ,american ,geologist1 ,september1 #ahij1 pp4 #aec-afb4 ,from this centre1 also1 the ice descended to the sea-level upon the west1 and filled all the channels between ,vancouver's ,island and the mainland1 as well as those in the ,alexander ,archipelago of ,alaska4 ,south of ,vancouver's ,island a glacier pushed out through the straits of ,juan de ,fuca to an unknown distance4 ,all the islands in ,puget ,sound are composed of glacial dbris1 resembling in every respect the terminal moraines which have been described as constituting many of the islands south of the ,new ,england coast4 ,the ice-movement in ,puget ,sound1 however1 was probably northward1 resulting from glaciers which are now represented by their diminutive descendants on the flanks of ,mount ,rainier4 ,south of the ,columbia ,river the country was never completely enveloped by the ice1 but glaciers extended far down in the valleys from all the lofty mountain-peaks4 ,in ,idaho there are glacial signs from the summit of the ,rocky ,mountains down to the westward of ,lake ,pend d',oreille4 ,in the ,yellowstone ,park there are clear indications that the whole area was enveloped in glacial ice4 ,an immense boulder of granite1 resting upon volcanic deposits1 may be found a little west of ,inspiration ,point1 on the ,yellowstone ,caon4 ,abundant evidences of glacial action are also visible down the ,yellowstone ,river to the vicinity of ,livingston1 showing that that valley must have been filled with glacial ice to a depth of sixteen hundred feet4 ,to the west the glaciers from the ,yellowstone ,park extended to the border of ,idaho1 where a clearly marked terminal moraine is to be found in the ,tyghee ,pass1 leading over from the western fork of the ,madison ,river into ,lewis ,fork of the ,snake ,river4 ,south of ,yellowstone ,park the ,teton ,mountains were an important centre for the dispersion of local glaciers1 but they did not descend upon the western side much below the #f1jjj-;foot level1 and only barely came to the edge of the great ,snake ,river lava plains4 ,to the east the movement from the ,teton ,mountains joined that from various other lofty mountains1 where altogether they have left a most intricate system of glacial deposits1 in whose reticulations ,jackson's ,lake is held in place4 ,illustration3 ,fig4 #cg4--,moraines of ,grape ,creek1 ,sangre del ,cristo ,mountains1 ,colorado 7after ,stevenson74 ,in ,utah extensive glaciers filled all the northern valleys of the ,uintah ,mountains1 and extended westward in the ,wahsatch range to the vicinity of ,salt ,lake ,city4 ,the mountain region of ,colorado1 also1 had its glaciers1 occupying the head-waters of the ,arkansas1 the ,platte1 the ,gunnison1 and the ,grand ,rivers4 ,the most southern point in the ,rocky ,mountains at which signs of local glaciers have been noted is near the summits of the ,san ,juan range1 in southwestern ,colorado4 ,here a surface of about twenty-five square miles1 extending from an elevation of #ab1jjj feet down to #h1jjj feet1 shows every sign of the former presence of moving ice4 ,the greater part of the glaciation in ,colorado is confined to elevations above #aj1jjj feet4 ,the whole range of the ,sierra ,nevada through ,oregon1 and as far south as the ,yosemite ,valley in ,california1 formerly sustained glaciers of far greater size than any which are now found in those mountains4 ,in general these glaciers were much longer on the western side of the ,sierra ,nevada than on the eastern4 ,on the eastern side glaciers barely came down to ,lake ,tahoe and ,lake ,mono in ,california4 ,the ,state of ,nevada seems to have been entirely free from glaciers1 although it contains numerous mountain-peaks more than ten thousand feet high4 ,in the ,yosemite ,caon glaciers extended down the ,merced ,river to the mouth of the caon2 while in the ,tuolumne ,river1 a few miles to the north1 the glaciers which still linger about the peaks of ,mount ,dana filled the valley for a distance of forty miles4 ,it is a question among geologists whether or not the glaciation west of the ,rocky ,mountains was contemporaneous with that of the eastern part of the continent4 ,the more prevalent opinion among those who have made special study of the phenomena is that the development of the ,cordilleran glaciers was independent of that of the ,laurentide system4 ,at any rate1 the intense glaciation of the ,pacific coast seems to have been considerably later than that of the ,atlantic region4 ,of this we will speak more particularly in discussing the questions of the date and the cause of the ,glacial period4 ,it is sufficient for us here simply to say that1 from his extensive field observations throughout the ,cordilleran region1 ,dr4 ,george ,m4 ,dawson infers that there have been several successive alternations of level on the ,pacific coast corresponding to successive glacial and interglacial epochs1 and that when there was a period of elevation west of the ,rocky ,mountains there was a period of subsidence to the east1 and vice versa4 ,in short1 he supposes that the east and west for a long time played a game of seesaw1 with the ,rocky ,mountains as the fulcrum4 ,we give his scheme in tabulated form4 ,scheme of ,correlation of the ,phenomena of the ,glacial ,period in the ,cordilleran ,region and in the ,region of the ,great ,plains4 ,,cordilleran ,,region4 ,,region ,,of ,,the ,,great ,,plains4 ,cordilleran zone at a high ,correlative subsidence and elevation4 ,period of most severe submergence of the great plains1 glaciation and maximum development with possible contemporaneous of the great ,cordilleran ,glacier4 increased elevation of the ,laurentian axis and maximum development of ice upon it4 ,deposition of the lower boulder-clay of the plains4 ,gradual subsidence of the ,correlative elevation of the ,cordilleran region and decay of the western part1 at least1 of the great glacier1 with deposition of great plains1 which was probably the boulder-clay of the interior more or less irregular and led to plateau and the ,yukon basin1 of the the production of extensive lakes lower boulder-clay of the littoral in which interglacial deposits1 and probably also1 at a later stage including peat1 were formed4 7and with greater submergence71 of the interglacial silts of the same region4 ,re-elevation of the ,cordilleran ,correlative subsidence of the region to a level probably as high plains1 which 7at least in the as or somewhat higher than the western part of the region7 present4 ,maximum of second period exceeded the first subsidence and of glaciation4 extended submergence to the base of the ,rocky ,mountains near the forty-ninth parallel4 ,formation of second boulder-clay1 and 7at a later stage7 dispersion of large erratics4 ,partial subsidence of the ,correlative elevation of the ,cordilleran region1 to a level plains1 or at least of their about #b1ejj feet lower than the western portion1 resulting in a present4 ,long stage of stability4 condition of equilibrium as ,glaciers of the second period between the plains and the considerably reduced4 ,upper ,cordillera1 their relative boulder-clay of the coast probably levels becoming nearly as at formed at this time1 though perhaps present4 ,probable formation of the in part during the second maximum ,missouri coteau along a shore-line of glaciation4 during this period of rest4 ,renewed elevation of the ,simultaneous elevation of the great ,cordilleran region1 with one plains to about their present well-marked pause1 during which the level1 with final exclusion of littoral stood about #bjj feet lower waters in connection with the sea4 than at present4 ,glaciers much ,lake ,agassiz formed and eventually reduced1 and diminishing in drained towards the close of this consequence of general amelioration period4 ,this simultaneous movement of climate towards the close of the in elevation of both great areas ,glacial period4 may probably have been connected with a more general northern elevation of land at the close of the ,glacial period4 ,in ,new ,zealand the marks of the ,glacial period are unequivocal ,the glaciers which now come down from the lofty mountains upon the ,south ,island of ,new ,zealand to within a few hundred feet of the sea then descended to the sea-level4 ,the longest existing glacier in ,new ,zealand is sixteen miles1 but formerly one of them had a length of seventy-eight miles4 ,one of the ancient moraines contains a boulder from thirty to forty feet in diameter1 and the amount of glacial dbris covering the mountain-sides is said to be enormous4 ,reports have also been recently brought of signs of ancient glaciers in ,australia4 ,illustration3 ,fig4 #ch4--;,generalised view of the whole glaciated region of ,north ,america4 ,the area of motionless ground-ice is shown by the white lines in northern part of ,alaska4 ,according to ,darwin1 there are distinct signs of glaciation upon the plains of ,patagonia sixty or seventy miles east of the foot of the mountains1 and in the ,straits of ,magellan he found great masses of unstratified glacial material containing boulders which were at least one hundred and thirty miles away from their parent rock2 while upon the island of ,chiloe he found embedded in hardened mud boulders which must have come from the mountain-chains of the continent4 ,agassiz also observed unquestionable glacial phenomena on various parts of the ,fuegian coast1 and indeed everywhere on the continent south of latitude #cg4 ,between ,concepcion and ,arauco1 in latitude #cg1 ,agassiz observed1 near the sea-level1 a glacial surface well marked with furrows and scratches1 and as well preserved1 he says1 as any he had seen under the glaciers of the present day4 ,illustration3 ,fig4 #ci4--,quartzite boulder of #de cubic metres1 on ,mont ,lachat1 #hjj metres above the valley of the ,belley1 in ,ain1 ,france 7,falsan74 ,,chapter ,,vi4 ,,ancient ,,glaciers ,,in ,,the ,,eastern ,,hemisphere4 ,about two million square miles of northern ,europe were covered with perennial ice during the ,glacial period4 ,from the scratches upon the rocks1 and from the direction in which material has been transported1 it is evident that the main centre of radiation is to be found in the mountains of ,scandinavia1 and that the glaciers still existing in ,norway are the lineal descendants of those of the great ,ice age4 ,so shallow are the ,baltic ,sea and the ,german ,ocean1 that their basins were easily filled with ice1 upon which ,scandinavian boulders could be transported westward to the east shore of ,england1 southward into the plains of ,germany1 and eastward far out upon the steppes of ,russia4 ,the islands north of ,scotland bear marks also of an ice-movement from the direction of ,norway4 ,if ,scotland itself was not overrun with ,scandinavian glaciers1 the reason was that it had ice enough of its own1 and from its highlands set up a counter-movement1 which successfully resisted the invasion from the ,scandinavian ,peninsula4 ,but1 elsewhere in ,europe1 ,scandinavian ice moved freely outward to the extent of its capacity4 ,then1 as now also1 the ,alps furnished centres for ice-movement1 but the glaciers were limited to the upper portions of the valleys of the ,rhne1 the ,rhine1 and the ,danube upon the west and north1 and to a still smaller area upon the southern side4 ,illustration3 ,fig4 #dj4 ,,map showing ,,glaciated ,,areas in ,north ,america and ,europe4 ,central and ,southern ,europe4 ,the main centres of ice-movement in the ,alps during the ,glacial period are the same as those which furnish the lingering glaciers of the present time4 ,from the water-shed between the ,rhine1 the ,rhne1 and the ,aar1 glaciers of immense size descended all the valleys now occupied by those streams4 ,the valley of the ,rhne between the ,bernese and the ,pennine ,alps was filled with a glacier of immense depth1 which was maintained by fresh supplies from tributaries upon either side as far down as ,martigny4 ,glacial markings at the head of the ,rhne ,valley are found upon the ,schneestock1,,bk at an elevation above the sea of about #aa1ejj feet 7#c1eej metres71 or about #a1ejj feet above the present surface of the ,rhne ,glacier4 ,at ,fiesch1 about twenty miles below1 where tributaries from the ,bernese ,oberland snow-fields were received1 the thickness of the glacier was upwards of #e1jjj feet 7#a1fhj metres74 ,near ,martigny1 about fifty miles farther down the valley1 where the glacier was abruptly deflected to the north1 the depth of the ice was still upwards of #a1fjj metres4 ,from ,martigny northward the thickness of the ice decreased rapidly for a few miles1 where1 at the enlargement of the valley above the head of ,lake ,geneva1 it was less than #a1bjj metres in thickness1 and spread out over the intervening plain as far as ,chasseron1 with a nearly level surface1 transporting1 as we have before said1 ,alpine boulders to the flanks of the ,juras1 and landing them about #c1jjj feet 7#a1bge metres7 above the level of ,lake ,geneva4 ,the width of the main valley is here about fifty miles1 making the slope of the surface of the ice about twenty feet to the mile4 ,footnote ,,bk3 ,a4 ,falsan's ,la ,priode ,grlaciaire tudie principalement en ,france et en ,suisse1 chapitre xv4 ,from its vomitory1 at the head of ,lake ,geneva1 the ice of the ancient ,rhne ,glacier spread to the right and to the left1 while its northern boundary was abruptly terminated by the line of the ,jura ,mountains4 ,the law of glacial motion was1 however1 admirably illustrated in the height to which the ice rose upon the flanks of the ,jura4 ,at ,chasseron1 in the direct line of its onward motion1 it rose to its highest point1 while both to the southwest and to the northeast1 along the line of the ,juras1 the ice-action was limited to constantly decreasing levels4 ,down the valley of the ,rhne the direction of motion was determined by the depression of ,lake ,geneva1 at the lower end of which it received its main tributary from ,mont ,blanc1 which had come down from ,chamouni through the valley of the river ,arve4 ,from this point it was deflected by a spur of the ,jura ,mountains more and more southward to the vicinity of ,culoz1 near the mouth of ,lake ,bourget4 ,here the glacier coming down from the western flanks of the ,alps1 through the upper valley of the ,isre1 past ,chambry1 became predominant1 and deflected the motion to the west and north1 whither the ice extended to a line passing through ,bourg1 ,lyons1 and ,vienne1 leaving upon one of the eminences on which ,lyons is built a boulder several feet in diameter1 which is duly preserved and labelled in the public park in that portion of the city4 ,farther south1 glaciers of less extent marked the ,alps most of the way to the ,mediterranean1 but they were not at all comparable in size to those from the central region4 ,to the right of ,lake ,geneva the movement started by the ,rhne ,glacier spread eastward1 being joined in the vicinity of ,berne by the confluent ice-stream which descended from the north flank of the ,bernese ,oberland1 through the valley of the ,aar4 ,these united streams filled the whole valley with ice as far down as ,soleure4,,bl ,footnote ,,bl3 ,see map of ,rhne ,glacier1 on p4 #eh4 ,illustration3 ,,map ,,of ,,glacial ,,movements ,,in ,,france ,,and ,,switzerland4 ,farther eastward1 other ice-streams from the ,alps became predominant1 one of which1 moving down the ,reuss1 deployed out upon the country lying north of ,lucerne and ,zug4 ,still farther down1 the ancient glacier which descended the ,limmatt spread itself out over the hills and lowlands about ,zrich1 one of its moraines of retrocession nearly dividing the lake into two portions4 ,guyot and others have shown that the superficial deposits of this portion of ,switzerland are just such as would be distributed by glaciers coming down from the above-mentioned ,alpine valleys4 ,uniting together north of ,zrich1 these glaciers pushed onward as far as the ,rhine below ,schaffhausen4 ,in ,frickthal the glacial ice was still #a1bjj feet thick1 and at ,kaisterberg between #djj and #ejj feet4 ,at ,lucerne there is a remarkable exposure of pot-holes1 and a glaciated surface such as could be produced only by the combined action of moving ice and running water2 thus furnishing to tourists an instructive object-lesson4 ,among the remarkable instances of boulders transported a long distance in ,switzerland1 is that of a block of granite carried from the ,valais to the vicinity of ,soleure1 a distance of one hundred and fifteen miles1 which weighs about #d1ajj tons4 ,the celebrated ,pierre--,bot1 above ,neufchtel1 measures #ej' #bj' #dj'1 and contains about #dj1jjj cubic feet of stone2 while the ,pierre-des-,marmettes1 near ,monthey1 contains no less than #fj1hdj cubic feet4 ,the ancient glacier of the ,rhine1 receiving its initial impulse in the same centre as that of the ,rhne1 fully equalled it in all its dimensions4 ,descending eastward from its source near the ,schneestock to ,chur1 a distance of fifty miles1 it turned northward and continued forty-five miles farther to the head of ,lake ,constance1 where it spread out in fan-shape1 extending northwest to ,thiengen1 below ,schaffhausen1 and covering a considerable area north and northeastward of the lake1 reaching in the latter direction ,ulm1 upon the ,danube--the whole distance of the movement being more than one hundred and fifty miles4 ,through other valleys tributary to the ,danube1 glaciers descended upon the upper plains of ,bavaria1 from the ,tyrolese ,alps to the vicinity of ,munich4 ,from ,gross ,glockner as a centre in the ,noric ,alps1 vast rivers of ice1 of which the ,pasterzen ,glacier is the remnant1 poured far down into the valleys of the ,inn and the ,enns on the north and into that of the ,drave on the southeast4 ,farther eastward in this part of ,europe the mountains seem to have been too low to have furnished centres for any general dispersion of glacial ice4 ,illustration3 ,fig4 #da4--,map showing the ,lines of ,dbris extending from the ,alps into the ,plains of the ,po 7after ,lyell74 ,a4 ,crest of the ,alpine water-shed2 ,b4 ,nv-fields of the ancient glaciers2 ,c4 ,moraines of ancient glaciers4 ,upon the south side of the ,alps the ancient glaciers spread far out upon the plains of ,lombardy1 where moraines of vast extent and of every description enable the student to determine the exact limits of the ancient ice-action4 ,from the southern flanks of ,mont ,blanc and ,monte ,rosa1 and from the snow-fields of the western ,alps1 glaciers of great volume descended into the valley of ,dora ,baltea 7vale of ,aosta71 and on emerging from the mountain valley ,spread ,out over the plains around ,ivrea1 leaving moraine hills in some instances #a1ejj feet in height4 ,the total length of this glacier was as much as one hundred and twenty miles4 ,from the snow-fields in the vicinity of ,mont ,cenis1 also1 glaciers extended down the ,dora ,ripera to the vicinity of ,turin1 and down other valleys to a less extent4 ,the lateral moraines of the ,diore1 on the south side of ,mont ,blanc1 at the head of the ,dora ,baltea1 are #b1jjj feet above the present river1 and extend upon the left bank for a distance of twenty miles4 ,from the eastern ,alps1 glaciers descended through all the valleys of the ,italian lakes and deposited vast terminal moraines1 which still obstruct the drainage1 and produce the charming lakes of that region4 ,a special historic interest pertains to the series of concentric moraines south of ,lake ,garda1 since it was in the reticulations of this glacial deposit that the last great battle for ,italian liberty was fought on ,june #bd1 #ahei4 ,defeated in the engagements farther up the valley of the ,po1 the ,austrian general ,benedek took his final stand to resist the united forces of ,france and ,italy behind an outer semicircle of the moraine hills south of this lake 7some of which are #ejj or #fjj feet above the surrounding country71 with his centre at ,solferino1 about ten miles from ,peschera4 ,here1 behind this natural fortification1 he awaited the enemy1 who was compelled to perform his manoeuvres on the open plain which spread out on every side4 ,but the natural fortifications furnished by the moraine hills were too extensive to be defended by an army of moderate size4 ,the troops of ,napoleon and ,victor ,immanuel concentrated at ,solferino and broke through the line4 ,thus the day was lost to the ,austrians1 and they retired from ,lombardy1 leaving to ,italy both the artificial and the natural fortifications that guard the southern end of this important entrance to the ,tyrolese ,alps4 ,when once his attention is called to the subject1 the traveller upon the railroad cannot fail to notice this series of moraines1 as he enters it through a tunnel at ,lonato on the west1 and emerges from it at ,soma ,campagna1 eighteen or twenty miles distant to the east4 ,a monument celebrating the victory stands upon a moraine hill about half-way between1 at ,martino della ,battaglie4 ,in other portions of central and southern ,europe the mountains were too low to furnish important centres for glacial movements4 ,still1 to a limited extent1 the signs of ancient glaciers are seen in the mountains of the ,black ,forest1 in the ,harz and ,erzgebirge1 and in the ,carpathians on the east and among the ,apennines on the south4 ,in ,spain1 also1 there were limited ice-fields on the higher portions of the ,sierra ,nevada and in the mountains of ,estremadura1 and perhaps in some other places4 ,in ,france1 small glaciers were to be found in the higher portions of the ,auvergne1 of the ,morvan1 of the ,vosges1 and of the ,cevennes2 while1 from the ,pyrenees1 glaciers extended northward throughout nearly their whole extent4 ,the ice-stream descending from the central mass of ,maladetta through the upper valley of the ,garonne1 was joined by several tributaries1 and attained a length of about forty-five miles4 ,the ,british ,isles4 ,during the climax of the ,glacial period the ,hebrides to the north of ,scotland were covered with ice to a depth of #a1fjj feet4 ,how far westward of this it moved out to the sea1 it is of course impossible to tell4 ,but in the channels between the ,hebrides and ,scotland it is evident that the water was completely expelled by the ice1 and that1 from a height of #a1fjj feet above the ,hebrides to the northern shores of ,scotland1 there was a continuous ice-field sloping southward at the rate of about twenty-five feet a mile4 ,scotland itself was completely enveloped in glacial ice4 ,prevented by the ,scandinavian ,glacier from moving eastward1 the ,scotch movement was compelled to be westward and southward4 ,on the southwest the ice-stream reached the shores of ,ireland1 and became confluent with the glaciers that enveloped that island1 completely filling the ,irish ,sea4 ,there are so many controverted points respecting the glacial geology of ,england1 and they have such an important bearing upon the main question of this volume1 that a pretty full discussion of them will be necessary4 ,i have recently been over enough of the ground myself to become satisfied of the general correctness of the views entertained by my late colleague1 the lamented ,professor ,henry ,carvill ,lewis1 whose death in #ahhh took place before the publication of his most mature conclusions4 ,but the lines of investigation to which he gave so powerful an impulse have since been followed out by an active body of scientific observers4 ,to give the statement of facts greater precision and authority1 ,i have committed the preparation of it to the ,secretary of the ,northwest of ,england ,boulder ,committee1 ,percy ,f4 ,kendall1 ,f4 ,g4 ,s41 ,lecturer on ,geology at the ,yorkshire ,college1 ,leeds1 and at the ,stockport ,technical ,school1 ,england4,,bm ,footnote ,,bm3 ,mr4 ,kendall's contribution extends to page #aha4 ,all the characteristic evidences of the action of land-ice can be found in the greatest perfection in many parts of ,england and ,wales4 ,drumlins1 kames1 roches moutonnes1 far-travelled erratics1 terminal moraines1 and perched blocks1 all occur4 ,there are1 besides1 in the wide-spread deposits of boulder-clay which cover so many thousands of square miles on the low grounds lying on either side of the ,pennine chain1 evidences of the operation of ice-masses of a size far exceeding that of the grandest of existing ,european glaciers4 ,but1 while the proofs of protracted and severe glaciation are thus patent1 there are1 nevertheless1 many apparently anomalous circumstances which arrest the attention when the whole country is surveyed4 ,the glacial phenomena appear to be strictly limited to the country lying to the northward of a line extending from the ,bristol ,channel to the mouth of the ,thames2 and within the glaciated area there are many extensive tracts of land devoid of 'drift' or other indications of ice-action4 ,by comparison with the phenomena displayed in the ,north ,american continent1 ,english glacial geology must seem puny and insignificant2 but1 just as with the features of the ',solid ,geology1' we have compressed within the narrow limits of our isles an epitome of the features which across the ,atlantic require a continent for their exposition4 ,it has resulted from this concentration that ,english geology requires a much closer and more minute investigation4 ,and the difficulty which has been experienced by glacial geologists of dealing with an involved series of facts has1 in the absence of any clue leading to the co-ordination of a vast series of more or less disconnected observations1 resulted in the adoption1 to meet certain local anomalies1 of explanations which were very difficult if not impossible of reconciliation with facts observed in adjacent areas4 ,thus1 to account for shell-bearing drift extending up to the water-shed on one side of a lofty range of hills1 a submergence of the land to a depth of #a1djj feet has been postulated2 leaving for independent explanation the fact1 that the opposite slopes of the hills and the low ground beyond were absolutely destitute of drift or of any evidence of marine action4 ,in the following pages ,i must adopt a somewhat dogmatic tone1 in order to confine myself within the limits of space which are imposed2 and trust rather to the cohesion and consistency of the explanations offered and to a few pregnant facts than to the weighing and contrasting of rival theories4 ,the facts point conclusively to the action in the ,british ,isles of a series of glaciers radiating outward from the great hill chains or clusters1 and1 as the refrigeration progressed1 becoming confluent and moving though in the same general direction1 yet with less regard to the minor inequalities of the ground4 ,during these two stages many glaciers must have debouched upon the sea-coast1 with the consequent production of icebergs1 which floated off with loads of boulders and dispersed them in the random fashion which is a necessary characteristic of transport by floating ice4 ,with a further accentuation of the cold conditions the discharge of bergs from terminal fronts which advanced into the extremely shallow seas surrounding the ,british shores would be quite inadequate to relieve the great press of ice1 and a further coalescence of separate elements must have resulted4 ,in the case of enclosed seas--as1 for example1 the ,irish ,sea--the continued inthrust of glacier-ice would expel the water completely2 and the conjoined ice-masses would take a direction of flow the resultant of the momentum and direction of the constituent elements4 ,in other cases--as1 for example1 in the ,north ,sea--extraneous ice approaching the shores might cause a deflection of the flow of the native glaciers1 even though the foreign ice might never actually reach the shore4 ,to such a system of confluent glaciers1 and to the separate elements out of which they grew1 and into which1 after the culmination1 they were resolved1 ,i attribute the whole of the phenomena of the ,english and ,welsh drift4 ,and only at one or two points upon the coast1 and raised but little above the sea-level1 can ,i recognise any signs of marine action4 ,the ,preglacial ,level of the ,land4--,there is very little direct evidence bearing upon this point4 ,in ,norfolk the famous forest bed1 with its associated deposits1 stands at almost precisely the level which it occupied in preglacial times4 ,at ,sewerby1 near ,flamborough ,head1 there is an ancient beach and 'buried cliff' which the sea is now denuding of its swathing of drift-deposits1 and its level can be seen to be almost absolutely coincident with the present beach4 ,mr4 ,lamplugh1 whose description of the ',drifts of ,flamborough ,head1',,bn constitutes one of the gems of glacial literature1 considers that there is clear evidence that the land stood at this level for a long period4 ,the beach is covered by a rain-wash of small extent1 and that in turn by an ancient deposit of blown sand1 while the lowest member of the drift series of ,yorkshire covers the whole4 ,mr4 ,lamplugh thinks that the blown sand may indicate a slight elevation of the land2 but the beach appears to me to be the storm beach1 and the reduction in the force of the waves such as would result from the approach of an ice-front a few miles to the seaward would probably produce the necessary conditions4 ,footnote ,,bn3 ,quarterly ,journal of the ,geological ,society1 vol4 xlvii4 ,six miles to the northward of ,flamborough1 at ,speeton1 a bed of estuarine silt containing the remains of mollusca in the position of life occurs at an altitude of ninety feet above high-water mark4 ,mr4 ,lamplugh inclines to the opinion that this bed is of earlier date than the 'buried cliff'2 he also admits the possibility that its superior altitude may be due to a purely local upward bulging of the soft ,lower ,cretaceous clays upon which the estuarine bed rests by the weight of the adjacent lofty chalk escarpment4 ,the evidence obtained from inland sections and borings in different parts of ,england has been taken to indicate a greater altitude in preglacial times4 ,thus1 in ,essex1 deep-borings have revealed the existence of deep drift-filled valleys1 having their floors below sea-level4 ,the valley of the ,mersey is a still better example4 ,numerous borings have been made in the neighbourhood of ,widnes and at other places in the lower reaches of the river1 making it clear that there is a channel filled with drift and extending to #adf feet below mean sea-level4 ,this1 with several other instances1 has been taken to indicate a greater altitude for the land in preglacial times1 since a river could not erode its channel to such a depth below sea-level4 ,the argument appears inconclusive for one principal reason3 no mention is made of any river gravels or other alluvium in the borings4 ,indeed1 there is an explicit statement that the deposits are all glacial1 showing that the channel must have been cleared out by ice4 ,this1 therefore1 leaves open the vital question1 whether the deposits removed were marine or fluviatile4 ,it may be remarked that the great estuary of the ,mersey has undoubtedly been produced by a post-glacial 7and probably post-,roman7 movement of depression4 ,the ,preglacial ,climate4--,in all speculations regarding the cause of the ,glacial epoch1 due account must be taken of the undoubted fact that it came on with extreme slowness and departed with comparative suddenness4 ,in the east of ,england an almost perfect and uninterrupted sequence of deposits is preserved1 extending from the early part of the ,pliocene period down to the present day4 ,these in descending order are3 #a4 ,post-glacial sands1 gravels1 etc4 #b4 ,glacial series4 #c4 ,the ',forest ,bed' and associated marine deposits4 #d4 ,chillesford clay and sand4 #e4 ,the many successive stages of the ,red ,crag4 7,the ,norwich ,crag is a local variation of the upper part of the ,red ,crag47 #f4 ,the ,coralline ,crag4 ,the fossils preserved in these deposits1 apart from the physical indications1 exhibit the climatal changes which accompanied their deposition4 ,the ,coralline ,crag contains a fauna consisting mainly of species which now range to the ,mediterranean1 many of them being restricted to the warm southern waters4 ,associated with these are a few boreal forms1 but they are represented in general by few individuals4 ,here and there in the deposits of this age far-travelled stones are to be found1 but they are always accounted great rarities4 ,the ,red ,crag consists of an irregular assemblage of beaches and sand-banks of widely different ages1 but their sequence can be made out with ease by a study of the fauna4 ,in the oldest deposits1 ,mediterranean species are very numerous1 while the boreal forms are comparatively rare2 but in successive later deposits the proportions are very gradually reversed1 and from the overlying ,chillesford series the ,mediterranean species are practically absent4 ,the physical indications run pari passu with the paleontological1 and in the newer beds of the ,red ,crag far-travelled stones are common4 ,in the ,forest ,bed series there is a marine band--the ,leda myalis bed--which contains an almost arctic assemblage of shells2 while at about the same horizon plant remains have been found1 including such high northern species as ,salix polaris and ,betula nana4 ,the glacial deposits do not1 in my opinion1 contain anywhere in ,england or ,wales a genuine intrinsic fauna1 such shells as occur in the ,east ,anglian glacial deposits having been derived in part from a contemporary sea-bed1 and1 for the rest1 from the older formations1 down perhaps to the ,coralline ,crag4 ,in the post-glacial deposits we have hardly any trace of a survival of the boreal forms1 and ,i consider that the whole marine fauna of the ,north ,sea was entirely obliterated at the culmination of the ,glacial epoch1 and that the repeopling in post-glacial times proceeded mainly from the ,english ,channel1 into which the northern forms never penetrated4 ,the ,great ,glacial ,centres4 ,where such complex interactions have to be described as were produced by the conflicting glaciers of the ,british ,isles it is difficult to deal consecutively with the phenomena of any one area1 but with short digressions in explanation of special points it may be possible to accomplish a clear presentation of the facts4 ,wales4--,the phenomena of ,south ,wales are comparatively simple4 ,great glaciers travelled due southward from the lofty ,brecknock ,beacons1 and left the characteristic moutonne appearance upon the rocky bed over which they moved4 ,the boulder-transport is in entire agreement with the other indications1 and there are no shells in the drift4 ,the facts awaiting explanation are the occurrence in the boulder-clays of ,glamorganshire1 at altitudes up to four hundred feet1 of flints1 and of igneous rocks somewhat resembling those of the ,archan series of the ,wrekin4 ,at ,clun1 in ,shropshire1 a train of erratics 7see map7 has been traced back to its source to the westward4 ,on the west coast1 in ,cardigan ,bay1 the boulders are all such as might have been derived from the interior of ,wales4 ,at ,st4 ,david's ,peninsula1 ,pembrokeshire1 stri occur coming in from the northwest1 and1 taken with the discovery of boulders of northern rocks1 may point to a southward extension of a great glacier produced by confluent sheets that choked the ,irish ,sea4 ,information is very scanty regarding large areas in mid-,wales1 but such as can be gathered seems to point to ice-shedding having taken place from a north and south parting line4 ,in ,north ,wales1 much admirable work has been done which clearly indicates the neighbourhood of ,great ,arenig 7,arenig ,mawr7 as the radiant point for a great dispersal of blocks of volcanic rock of a characteristic ,welsh type4 ,ireland4--,a brief reference must be made to ,ireland1 as the ice which took origin there played an important part in bringing about some strange effects in ,english glaciation1 which would be inexplicable without a recognition of the causes in operation across the ,irish ,sea4 ,ireland is a great basin1 surrounded by an almost continuous girdle of hills4 ,the rainfall is excessive1 and the snow-fall was probably more than proportionately great2 therefore we might expect that an ice-sheet of very large dimensions would result from this combination of favouring conditions4 ,the ,irish ice-sheet appears to have moved outward from about the centre of the island1 but the main flow was probably concentrated through the gaps in the encircling mountains4 ,galloway4--,the great range of granite mountains in the southwestern corner of ,scotland seems to have given origin to an immense mass of ice which moved in the main to the southward1 and there are good grounds for the belief that the whole ice-drainage of the area1 even that which gathered on the northern side of the water-shed1 ultimately found its way into the ,irish ,sea basin and came down coastwise and across the low grounds of the ,rinns of ,galloway1 being pushed down by the press of ,highland ice which entered the ,firth of ,clyde4 ,it is a noteworthy fact that marine shells occur in the drift in the course taken by the ice coming on to the extremity of ,galloway from the ,clyde4 ,the ,lake ,district4--,a radial flow of ice took place down the valleys from about the centre of the ,cumbrian hill-plexus1 but movement to the eastward was at first forbidden by the great rampart of the ,cross ,fell escarpment1 which stretches like a wall along the eastern side of the ,vale of ,eden4 ,during the time when the ,cumbrian glaciers had unobstructed access to the ,solway ,frith1 to the ,irish ,sea1 and to ,morecambe ,bay1 the dispersal of boulders of characteristic local rocks would follow the ordinary drainage-lines2 but1 as will be shown later1 a state of affairs supervened in the ,irish ,sea which resulted1 in many cases1 in a complete reversal of the ice-flow4 ,the ,pennine ,chain was the source of glaciers of majestic dimensions upon both its flanks in the region north of ,skipton1 but to the southward of that breach in the chain 7see map7 no evidence is obtainable of any local glaciers4 ,the ,confluent ,glaciers4 ,with the growth of ice-caps upon the great centres a condition of affairs was brought about in the ,irish ,sea productive of results which will readily be foreseen4 ,the enormous volumes of ice poured into the shallow sea from north1 south1 east1 and west1 resulted in such a congestion as to necessitate the initiation of some new systems of drainage4 ,the ,irish ,sea ,glacier4--,the ice from ,galloway1 ,cumbria1 and ,ireland became confluent1 forming what the late ,professor ,carvill ,lewis termed 'the ,irish ,sea ,glacier1' and took a direction to the southward4 ,here it came in diametrical conflict with the northward-flowing element of the ,welsh sheet1 which it arrested and mastered2 and the ,irish ,sea ,glacier bifurcated1 probably close upon the precipitous ,welsh coast to the eastward of the ,little ,orme's ,head1 and the two branches flowed coastwise to eastward and westward1 keeping near the shore-line4 ,the westerly branch swept round close to the coast in a southwesterly direction1 and completely overrode ,anglesea2 striating the rock-surfaces from northeast to southwest 7see map71 and strewing the country with its bottom-moraine1 containing characteristic northern rocks1 such as the ,galloway granites1 the lavas and granites of the central and western portions of the ,lake ,district1 and fragments of shells derived from shell-banks in the ,irish ,sea4 ,one episode of this phase of the ice-movement was the invasion of the first line of hills between the ,menai ,straits and ,snowdon4 ,the gravels and sands of ,fridd-bryn-mawr1 ,moel ,tryfaen1 and ,moel-y-,cilgwyn1 are the coarser washings of the bottom-moraine1 and consequently contain such rock-fragments and shells as characterise it4 ,from ,moel-y-,cilgwyn southward1 evidence is lacking regarding the course taken by the glacier1 but it probably passed over or between the ,rivals ,mountains 7,yr ,eifl71 and down ,cardigan ,bay at some distance from the coast in confluence with the ice from mid-,wales2 and1 as ,i have suggested1 may have passed over ,st4 ,david's ,head4 ,returning now towards the head of the glacier we may follow with advantage its left bank downward4 ,the ice-flow on the ,cumberland coast appears to have resembled very much that in ,north ,wales4 ,a great press of ice from the northward 7,galloway7 seems to have had a powerful 'easting' imparted to it by the conjoint influences of the thrust of the ,irish ice and the inflow of ice from the ,clyde4 ,whatever may have been the cause1 the effect is clear3 about ,ravenglass cleavage took place1 and a flow to northward and to southward1 each bending easterly4 ,by far the larger mass took a southerly course and bent round ,black ,combe1 over ,walney1 and a strip of the mainland about ,barrow in ,furness1 and out into and across ,morecambe ,bay4 ,its limits are marked in the field by the occurrence of the same rocks which characterise it in ,anglesea1 viz41 the granites of ,galloway and of west and central ,cumbria4 ,the continued thrust shouldered in the glacier upon the mainland of ,lancashire1 but the precise point of emergence has not yet been traced1 though it cannot be more than a few miles from the position indicated on the map4 ,i should here remark1 that all along the boundaries the ,irish ,sea ,glacier was confluent with local ice1 except1 probably1 in that part of the ,pennine chain to the southward of ,skipton4 ,down to ,skipton there was a great mass of ,pennine ice which was compelled to take an almost due southerly course1 and thus to run directly athwart the direction of the main hills and valleys4 ,a sharp easterly inflection of the ,irish ,sea ,glacier carried it up the valley of the ,ribble1 and thence1 under the shoulder of ,pendle1 to ,burnley1 where ,scottish granites are found in the boulder-clay4 ,on the summit of the ,pennine water-shed1 at ,heald ,moor1 near ,todmorden 7#a1dai feet71 boulder-clay has been found containing erratics belonging to this dispersion2 while in the gorge of the ,yorkshire ,calder1 which flows along the eastern side of the same hill1 not a vestige of such a deposit is to be found1 saving a few erratic pebbles at a distance of eight or ten miles1 which were probably carried down by flood-wash from the edge of the ice4 ,from this point the limits of the ice may be traced along the flanks of the ,pennine chain at an average altitude of about #a1ajj feet4 ,at one place the erratics can be traced to a position which would indicate the formation of an extra-morainic lake having its head at a col about #a1jjj feet above sea-level1 separating it from the valley of an eastward-flowing stream1 the ,wye1 about twelve miles down which a few granite blocks have been found4 ,other extra-morainic lakes must have been formed1 but very little information has been collected regarding them4 ,the ,irish ,sea ,glacier can be shown to have spread across the whole country to the westward of the line ,i have traced1 and beyond the estuary of the ,dee4 ,i may now follow its boundaries on the ,welsh coast1 and pursue the line to the final melting-place of the glacier4 ,from the ,little ,orme's ,head the line of confluence with the native ice is pretty clearly defined4 ,it runs in1 perhaps1 half a mile from the shore1 until the broad low tract of the ,vale of ,clwyd is reached4 ,here the northern ice obtained a more complete mastery1 and pushed in even as far as ,denbigh4 ,this extreme limit was probably attained as a mere temporary episode4 ,horizontal stri on a vertical face of limestone on the crags dominating the mouth of the vale on the eastern side attest beyond dispute the action of a mass of land-ice moving in from the north4 ,i may here remark1 that in this district the deposits furnish a very complete record of the events of the ,glacial period4 ,in the cliffs on the eastern side of the ,little ,orme's ,head1 and at several other points along the coast towards the east1 a sequence may be observed as follows3 #d4 ,boulder-clay with northern erratics and shells4 #c4 ,sands and gravels with northern erratics and shells4 #b4 ,boulder-clay with northern erratics and shells4 #a4 ,boulder-clay with ,welsh erratics and no shells4 ,a similar succession is to be seen in the ,vale of ,clwyd4 ,the interpretation is clear3 ,in the early stages of glaciation the ,welsh ice spread without hindrance to1 and laid down1 bed ,no4 #a2 then the northern ice came down1 bringing its typical erratics and the scourings of the sea-bottom1 and laid down the variable series of clays1 sands1 and gravels which constitute ,nos4 #b1 #c1 and #d of the section4 ,illustration3 ,fig4 #db4--,the ,cefn ,cave1 in ,vale of ,clwyd4 7,trimmer47 a1 ,entrance2 b1 mud with pebbles and wood covered with stalagmite2 c1 mud1 bones1 and angular fragments of limestone2 d1 sand and silt1 with fragments of marine shells2 e1 fissure2 f1 northern drift2 g1 cave cleared of mud2 h1 river ,elwy1 #ajj feet below2 i1 limestone rock4 ,in the ,vale of ,clwyd an additional interest is imparted to the study of the drift from the circumstance that the remains of man have been found in deposits in caves sealed with drift-beds4 ,the best example is the ,cae ,gwyn caves1 in which flint implements and the bones and teeth of various extinct animals were found embedded in 'cave-earth' which was overlaid by bedded deposits of shell-bearing drift1 with erratics of the northern type4 ,it has been supposed that the drift-deposits were marine accumulations2 but it is inconceivable that the cave could ever have been subjected to wave-action without the complete scouring out of its contents4 ,to resume the delineation of the limits of the great ,irish ,sea ,glacier3 ,from the ,vale of ,clwyd the boundary runs along the range of hills parallel to the estuary of the ,dee at an altitude of about nine hundred feet4 ,as it is traced to the southeast it gradually rises1 until at ,frondeg1 a few miles to the northward of the embouchure of the ,yale of ,llangollen1 it is at a height of #a1dej feet above sea-level4 ,thence it falls to #a1aej feet at ,gloppa1 three miles to the westward of ,oswestry1 and this is the most southerly point to which it has been definitely traced on the ,welsh border1 though scattered boulders of northern rocks are known to occur at ,church ,stretton4 ,along the line from the ,vale of ,clwyd to ,oswestry the boundary is marked by a very striking series of moraine-mounds4 ,they occur on the extreme summits of lofty hills in a country generally almost driftless1 and their appearance is so unusual that one--,moel-y-crio--at least has been mistaken for an artificial tumulus4 ,the limitation of the dispersal of northern erratics by these mounds is very clear and sharp2 and ,mackintosh1 in describing those at ,frondeg1 remarked that1 while no northern rocks extended to the westward of them1 so no ,welsh erratics could be found to cross the line to the eastward4 ,there are ,welsh erratics in the low grounds of ,cheshire and ,shropshire1 but their distribution is sporadic1 and will be explained in a subsequent section4 ,having thus followed around the edges of this glacier1 it remains to describe its termination4 ,it is clear that the ice must have forced its way over the low water-shed between the respective basins of the ,dee and the ,severn4 ,so soon as this ridge 7less than #ejj feet above the sea7 is crossed1 we find the deposits laid down by the glacier change their character1 and sands and gravels attain a great predominance4,,bo ,near ,bridgenorth1 and1 at other places1 hills composed of such materials attain an altitude of #bjj feet4 ,from ,shrewsbury via ,burton1 and thence1 in a semicircular sweep1 through ,bridgenorth and ,enville1 there is an immense concentration of boulders and pebbles1 such as to justify the designation of a terminal moraine4 ,to the southward1 down the valley of the ,severn1 existing information points to the occurrence merely of such scattered pebbles as might have been carried down by floods4 ,in the district lying outside this moraine there is a most interesting series of glacial deposits and of boulders of an entirely different character4 7,see map47 ,footnote ,,bo3 ,mackintosh1 ,q4 ,j4 ,g4 ,s4 ,from the neighbourhood of ,lichfield1 through some of the suburbs of ,birmingham1 and over ,frankley ,hill and the ,lickey ,hills to ,bromsgrove1 there is a great accumulation of ,welsh erratics1 from the neighbourhood1 probably1 of ,arenig ,mawr4 ,the late ,professor ,carvill ,lewis suggested that these ,arenig rocks might have been derived from some adjacent outcrop of ,palozoic rocks--a suggestion having its justification in the discoveries that had been made of ,cumbrian rocks in the ,midlands4 ,to test the matter1 an excavation was made at a point selected on ,frankley ,hill1 and a genuine boulder-clay was found1 containing erratics of the same type as those found upon the surface4 ,the explanation has since been offered that this boulder-clay was a marine deposit laid down during a period of submerge nee4,,bp ,apart from the difficulty that the boulder-clay displays none of the ordinary characteristics of a marine deposition1 but possesses a structure1 or rather absence of structure1 in many respects quite inconsistent with such an origin1 and contains no shells or other remains of marine creatures1 it must be pointed out that no theory of marine notation will explain the distribution of the erratics1 and especially their concentration in such numbers at a station sixty or seventy miles from their source4 ,footnote ,,bp3 ,proceedings of the ,birmingham ,philosophical ,society1 vol4 vi1 ,part ,i1 p4 #aha4 ,upon the land-ice hypothesis this difficulty disappears4 ,during the early stages of the ,glacial period the ,welsh ice had the whole of the ,severn ,valley at its mercy1 and a great glacier was thrust down from ,arenig1 or some other point in central ,wales1 having an initial direction1 broadly speaking1 from west to east4 ,this glacier extended across the valley of the ,severn1 sweeping past the ,wrekin1 whence it carried blocks of the very characteristic rocks to be lodged as boulders near ,lichfield2 and it probably formed its terminal moraine along the line indicated4 7,see lozenge-shaped marks on the map47 ,as the ice in the north gathered volume it produced the great ,irish ,sea ,glacier1 which pressed inland and down the ,vale of ,severn in the manner ,i have described1 and brushed the relatively small ,welsh stream out of its path1 and laid down its own terminal moraine in the space between the ,welsh border and the ,lickey ,hills4 ,it seems probable that the ,welsh stream came mainly down the ,vale of ,llangollen1 and thence to the ,lickey ,hills4 ,boulders of ,welsh rocks occur in the intervening tract by ones and twos1 with occasional large clusters1 the preservation of any more connected trail being rendered impossible by the great discharge of water from the front of the ,irish ,sea ,glacier1 and the distributing action of the glacier itself4 ,within the area in ,england and ,wales covered by the ,irish ,sea ,glacier all the phenomena point to the action of land-ice1 with the inevitable concomitants of subglacial streams1 extra-morainic lakes1 etc4 ,there is nothing to suggest marine conditions in any form except the occurrence of shells or shell fragments2 and these present so many features of association1 condition1 and position inconsistent with1 what we should be led to expect from a study of recent marine life1 that conchologists are unanimous in declaring that not one single group of them is on the site whereon the shells lived4 ,it is a most significant fact--one out of a hundred which could be cited did space permit--that in the ten thousand square miles of1 as it is supposed1 recently elevated sea-bottom1 not a single example of a bivalve shell with its valves in apposition has ever been found6 ,nor has a boulder or other stone been found encrusted with those ubiquitous marine parasites1 the barnacles4 ,the evidences of the action of land-ice within the area are everywhere apparent in the constancy of direction of-- 7#a47 ,stri upon rock surfaces4 7#b47 ,the terminal curvature of rocks4 7#c47 ,the 'pull-over' of soft rocks4 7#d47 ,the transportal of local boulders4 7#e47 ,the orientation of the long axes of large boulders4 7#f47 ,the false bedding of sands and gravels4 7#g47 ,the elongation of drift-hills4 7#h47 ,the relations of 'crag and tail4' ,there is a similar general constancy1 too1 in the directions of the stri upon large boulders4 ,upon the under side they run longitudinally from southeast 7or thereabouts7 to northwest1 while upon the upper surface they originate at the opposite end1 showing that the scratches on the under side were produced by the stone being dragged from northwest to southeast1 while those on the top were the product of the passage of stone-laden ice over it in the same direction4 ,such an agreement cannot be fortuitous1 but must be attributed to the operation of some agent acting in close parallelism over the whole area4 ,to attribute such regularity to the action of marine currents is to ignore the most elementary principles of marine hydrology4 ,icebergs must1 in the nature of things1 be the most erratic of all agents1 for the direction of drift is determined--among other varying factors--by the draught of the berg4 ,a mass of small draught will be carried by surface currents1 while one of greater depth will be brought within the influence of under-currents2 and hence it not infrequently happens that while floe-ice is drifting1 say1 to the southeast1 giant bergs will go crashing through it to the northwest4 ,there are tidal influences also to be reckoned with1 and it is matter of common knowledge that flotsam and jetsam travel back and forth1 as they are alternately affected by ebb and flood tide4 ,bearing these facts in mind1 it is surely too much to expect that marine ice should transport boulders 7how it picked up many of them also requires explanation7 with such unfailing regularity that it can be said without challenge1,,bq 'boulders in this district ,south ,lancashire and ,cheshire never occur to the north or west of the parent rock4' ,the same rule applies without a single authentic exception to the whole area covered by the eastern branch of the ,irish ,sea ,glacier2 and hence it comes about that not a single boulder of ,welsh rock has ever been recorded from ,lancashire4 ,footnote ,,bq3 ,brit4 ,assoc4 ,report1 #ahij1 p4 #cdc4 ,the ,solway ,glacier4--,the pressure which forced much of the ,irish ,sea ice against the ,cumbrian coast-line caused1 as has been described1 a cleavage of the flow near ,ravenglass1 and1 having followed the southerly branch to its termination in the midlands1 the remaining moiety demands attention4 ,the 'easting' motion carried it up the ,solway ,frith1 its right flank spreading over the low plain of northern ,cumberland1 which it strewed with boulders of the well-known 'syenite' 7granophyre7 of ,buttermere4 ,when this ice reached the foot of the ,cross ,fell escarpment1 it suffered a second bifurcation1 one branch pushing to the eastward up the valley of the ,irthing and over into ,tyneside1 and the other turning nearly due southward and forcing its way up the broad ,vale of ,eden4 ,under the pressure of an enormous head of ice1 this stream rose from sea-level1 turned back or incorporated the native ,cumbrian ,glacier which stood in its path1 and1 having arrived almost at the water-shed between the northern and the southern drainage1 it swept round to the eastward and crossed over the ,pennine water-shed2 not1 however1 by the lowest pass1 which is only some #a1djj feet above sea-level1 but by the higher pass of ,stainmoor1 at altitudes ranging from #a1hjj to #b1jjj feet4 ,the lower part of the course of this ice-flow is sufficiently well characterised by boulders of the granite of the neighbourhood of ,dalbeattie in ,galloway2 but on its way up the ,vale of ,eden it gathered several very remarkable rocks and posted them as way-stones to mark its course4 ,one of these rocks1 the ,permian ,brockram1 occurs nowhere in situ at altitudes exceeding #gjj feet1 yet in the course of its short transit it was lifted about a thousand feet above its source4 ,the ,shap granite 7see radiant point on map7 is on the northern side of the east and west water-sheds of the ,lake ,district1 and reaches its extreme elevation1 7#a1fef feet7 on ,wasdale ,pike2 yet boulders of it were carried over ,stainmoor1 at an altitude of #a1hjj feet literally by tens of thousands4 ,this ,stainmoor ,glacier passed directly over the ,pennine chain1 past the mouths of several valleys1 and into ,teesdale1 which it descended and spread out in the low grounds beyond4 ,pursuing its easterly course1 it abutted upon the lofty ,cleveland ,hills and separated into two streams1 one of which went straight out to sea at ,hartlepool1 while the other turned to the southward and flowed down the ,vale of ,york1 being augmented on its way by tributary glaciers coming down ,wensleydale4 ,the final melting seems to have taken place somewhere a little to the southward of ,york2 but boulders of ,shap granite by which its extension is characterised have been found as far to the southward as ,royston1 near ,barnsley4 ,the other branch of the ,solway ,glacier--that which travelled due eastward--passed up the valley of the ,irthing1 and over into that of the ,tyne1 and out to sea at ,tynemouth4 ,it carried the ,scottish granites with it1 and tributary masses joined on either hand1 bringing characteristic boulders with them4 ,the fate of those elements of the ,solway ,frith ,glacier which reached the sea is not left entirely to conjecture4 ,the striated surfaces near the coast of ,northumberland indicate a coastwise flow of ice from the northward--probably from the ,frith of ,forth--and the glaciers coming out from the ,tyne and ,tees were deflected to the southward4 ,there is conclusive evidence that this ice rasped the cliffs of the ,yorkshire coast and pressed up into some of the valleys4 ,where it passed the mouth of the ,tees near ,whitby it must have had a height of at least #hjj feet1 but farther down the coast it diminished in thickness4 ,it nowhere extended inland more than a mile or two1 and for the most part kept strictly to the coast-line4 ,along the whole coast are scattered erratics derived from ,galloway and the places lying in the paths of the glaciers4 ,in many places the cliffs exhibit signs of rough usage1 the rocks being crumpled and distorted by the violent impact of the ice4 ,at ,filey ,brigg a well-scratched surface has been discovered1 the striation being from a few degrees east of north4 ,at ,speeton the evidence of ice-sheet or glacier-work is of the most striking character4 ,on the top of the cliffs of ,cretaceous strata a line of moraine-hills has been laid down1 extending in wonderful perfection for a distance of six miles4 ,they consist of a mixture of sand1 gravel1 and a species of clay-rubble1 with occasional masses of true boulder-clay1 the whole showing the arched bedding so characteristic of such accumulations4 ,at the northerly end the moraine keeps close to the edge of the chalk cliffs1 which are there #djj feet high1 and the hills are frequently displayed in section2 but as the elevation of the cliffs declines they fall back from the edge of the cliffs and run quite across the headland of ,flamborough1 and are again exposed in section in ,bridlington ,bay4 ,one remarkable and significant fact is pointed out1 namely1 that behind this moraine1 within half a mile and at a lower level1 the country is almost absolutely devoid of any drift whatever4 ,illustration3 ,fig4 #dc4--,moraine between ,speeton and ,flamborough 7,lamplugh74 ,the interpretation of these phenomena is as follows3 ,when the valley-glaciers reached the sea they suffered the deflection which has been mentioned1 partly as the result of the interference of ice from the east of ,scotland1 but also influenced directly by the cause which operated upon the ,scottish ice and gave direction to it--that is1 the impact of a great glacier from ,scandinavia1 which almost filled the ,north ,sea1 and turned in the eastward-flowing ice upon the ,british coast4 ,it is easy to see how this pressure must have forced the glacier-ice against the ,yorkshire coast1 but vertical chalk cliffs #djj feet in height are not readily surmounted by ice of any thickness1 however great1 and so it coasted along and discharged its lateral moraine upon the cliff-tops4 ,as the cliffs diminished in height we find the moraine farther inland1 and1 as ,i have pointed out1 the ice completely overrode ,flamborough ,head4 ,amongst the boulders at ,flamborough are many of ,shap granite1 a few ,galloway granites1 a profusion of ,carboniferous rocks1 brought by the ,tyne branch of the ,sol way ,glacier as well as by that of ,stainmoor1 and1 besides many torn from the cliffs of ,yorkshire1 a few examples of unquestionable ,scandinavian rocks1 such as the well-known ,rhomben-porphyr4 ,it is important to note that about ten to twenty miles from the ,yorkshire coast there is a tract of sea-bottom called by trawlers 'the rough ground1' in allusion to the fact that it is strewn with large boulders1 amongst which are many of ,shap granite4 ,this probably represents a moraine of the ,teesdale ,glacier1 laid down at a time when the ,scandinavian ,glacier was not at its greatest development4 ,on the south side of ,flamborough ,head the 'buried cliff' previously alluded to occurs4 ,the configuration of the country shows--and the conclusion is established by numerous deep-borings--that the preglacial coast-line takes a great sweep inland from here1 and that the plain of ,holderness is the result of the banking-up of an immense thickness of glacial dbris4 ,in the whole country reviewed1 from ,tynemouth to ,bridlington1 wherever the ice came on to the land from the seaward1 it brought in shells and fragmentary patches of the sea-bottom involved in its ground moraine4 ,space does not permit of a detailed description of the several members of the ,yorkshire ,drift1 and ,i pass on to deal in a general way with the glacial phenomena of the eastern side of ,england4 ,the ,east ,anglian ,glacier4--,the influence of the ,scandinavian ice is clearly seen in the fact that the entire ice-movement down the east coast south of ,bridlington was all from the seaward4 ,clays1 sands1 and gravels1 the products of a continuous mass of land-ice coming from the northeast are spread over the whole country1 from the ,trent to the high grounds on the north of ,london overlooking the ,thames4 ,the line of extreme extension of these drift-deposits runs from ,finchley 7near ,london71 in the south across ,hertfordshire1 through ,cambridgeshire1 with outlying patches at ,gogmagog and near ,buckingham1 and northwestward over a large portion of ,leicestershire into the upper waters of the ,trent1 embracing the elevated region of ,palozoic rocks at ,charnwood ,forest1 near ,leicester4 ,reserving the consideration of the very involved questions connected with the drifts of the upper part of the ,trent ,valley1 ,i may pass on to join the phenomena of the southeastern counties with those at ,flamborough ,head4 ,from ,nottinghamshire the limits of the drift of the ,east ,anglian ,glacier seem to run in a direction nearly due west to east1 for the great oolitic escarpment upon which ,lincoln ,cathedral is built is absolutely driftless to the northward of the breach about ,sleaford4 ,however1 along the western flank of the oolitic range true boulder-clay occurs1 bordering and doubtless underlying the great fen-tract of mid-,lincolnshire2 and the great ,lincolnshire ,wolds appear to have been completely whelmed beneath the ice4 ,the most remarkable of the deposits in this area is the ,great ,chalky ,boulder-,clay1 which consists of clay containing much ground-up chalk1 and literally packed with well-striated boulders of chalk of all sizes1 from minute pebbles up to blocks a foot or more in diameter4 ,associated with them are boulders of various foreign rocks1 and many flints in a remarkably fresh condition1 and still retaining the characteristic white coat1 except where partially removed by glacial attrition4 ,one of the perplexing features of the glacial phenomena in the eastern counties of ,england is the extension of true chalky boulder-clay to the north ,london heights at ,finchley and elsewhere2 for only the faintest traces are to be found in the gravel deposits of the ,thames ,valley of any wash from such a deposit1 or from a glacier carrying such materials4 ,it has been suggested that the deposit may have been laid down in an extra-morainic lake1 or in an extension of the ,north4 ,sea1 but these suggestions leave the difficulty just where it was4 ,if a lake or sea could exist without shores1 a glacier-stream might equally dispense with banks4 ,within the area of glaciation1 defined above1 abundant evidence of the action of land-ice is obtainable1 though striated surfaces are extremely rare--a fact attributable to the softness of the chalk and clays which occupy almost the whole area4 ,well-striated surfaces are found on the harder rocks1 as1 for example1 on the oolitic limestone at ,dunston1 near ,lincoln4 ,mr4 ,skertchly has remarked that the proofs of the action of land-ice are irrefragable4 ,the ,great ,chalky ,boulder-,clay covers an area of #c1jjj square miles1 and attains an altitude of #ejj feet above the sea-level1 thus bespeaking1 if the product of icebergs1 'an extensive gathering-ground of chalk1 having an elevation of more than #ejj feet4 ,but where is it8 ,certainly not in ,western ,europe1 for the chalk does not attain so great an elevation except in a few isolated spots4',,br ,footnote ,,br3 ,geikie's ,great ,ice ,age1 p4 #cfj4 ,illustration3 ,fig4 #dd4--;,diagram-section near ,cromer 7,woodward74 #f4 ,gravel and sand 7,middle ,glacial7 resting on contorted drift 7loam1 sand1 and marl1 with large included boulders of chalk72 #e4 ,cromer till3 #d4 ,laminated clay and sands 7,leda myalis bed72 #c4 ,fresh-water loams and sands3 #c;a4 ,black fresh-water bed of ,runton 7upper fresh-water bed72 #b4 ,forest bed--laminated clays and sands1 with roots and dbris of wood1 bones of mammalia1 estuarine mollusca1 etc41 the upper part in places penetrated by rootlets 7rootlet bed72 #b;a4 ,weybourn crag2 #a4 ,chalk with flints2 99 ,large included boulder of chalk4 ,it has been further pointed out by ,mr4 ,skertchly1 that the condition of the flints in this deposit furnishes strong evidence that they could not have been carried by floating ice nor upon a glacier1 for1 in either of the latter events1 there must have been some exposure to the weather1 which1 as he remarks1 would have rendered them worthless to the makers of gun-flints1 whereas they are now regularly collected for their use4 ,the way in which the boulder-clay is related to the rocks upon which it rests is a conclusive condemnation of any theory of floating ice2 for example1 where it rests upon ,oxford ,clay1 it contains the fossils characteristic of that formation1 as it is largely made up of the clay itself4 ,the exceptions to this rule are as suggestive as those cases which conform to it4 ,each outcrop yields material to the boulder-clay to the south westward1 showing a pull-over from the northeast4 ,one of the most remarkable features of the drift of this part of ,england is the inclusion of gigantic masses of rock transported for a short distance from their native outcrop1 very often with so small a disturbance that they have been mapped as in situ4 ,examples of chalk-masses #hjj feet in length1 and of considerable breadth and thickness1 have been observed in the cliffs near ,cromer1 in ,norfolk1 but they are by no means restricted to situations near the coast4 ,one example is mentioned in which quarrying operations had been carried on for some years before any suspicion was aroused that it was merely an erratic4 ,the huge boulders were probably dislodged from the parent rock by the thrust of a great glacier1 which first crumbled the beds1 then sheared off a prominent fold and carried it along4 ,this explanation we owe to ,mr4 ,clement ,reid4,,bs ,the drift-deposits of this region frequently contain shells1 but they rarely constitute what may be termed a consistent fauna1 usually showing such an association as could only be found where some agent had been at work gathering together shells of different habitats and geological age4 ,footnote ,,bs3 ,see ,geology of the ,country around ,cromer1 and ,geology of ,holderness1 ,memoirs of ,geological ,survey of ,england and ,wales4 ,illustration3 ,fig4 #de4--,section at right angles to the cliff through the westerly chalk bluff at ,trimingham1 ,norfolk1 showing the manner in which chalk masses are incorporated into the till 7,clement ,reid74 ,scale1 #bej fret to an inch4 ,a4 ,level of low-water spring-tides2 ,b4 ,chalk1 with sandy bed at 992 ,c4 ,forest-bed series1 etc41 seen in the cliffs a few yards north and south of this point2 ,d4 ,cromer till1 stiff lead-colored boulder-clay2 ,e4 ,fine1 chalky sands1 much false-bedded2 ,f4 ,contorted drift1 brown bouldery-clay with marked bedding- or fluxion-structure2 ,g4 ,the bed1 above the white line were seen and measured by more snow and measured by ,mr4 ,reid2 99 ,chalk seen in situ on beach4 ,if the ice-sheet1 instead of flowing over the beds1 happens to plough into them or abut against them1 it would bend up a boss of chalk1 as at ,beeston4 ,a more extensive disturbance1 like that at ,trimingham drives before it a long ridge of the bads1 and nips up the chalk1 till1 like a cloth creased by the sliding of a heavy book1 it is folded into an inverted anticlinal4 ,a slight increase of pressure1 and the third stage is reached--the top of the anticlinal being entirely sheared off1 the chalk boulder driven up an incline1 and forced into the overlying boulder-clays4 7,clement ,reid47 ,attempts have been made to correlate the deposits over the whole area1 but with very indifferent success4 ,a consideration of the consequences of the invasion of the country by an ice-stream from the northeast will prepare us for any conceivable complication of the deposits4 ,the main movement was against the drainage of the country1 so that the ice-front must have been frequently in water4 ,there would be aqueous deposition and erosion2 the kneading up of morainic matter into ground-moraine2 irregularities of distribution and deposition due to ice floating in an extra-morainic lake2 flood-washes at different points of overflow2 and other confusing causes1 which make it rather matter for surprise that any order whatever is traceable4 ,i now turn to the valley of the ,trent4 ,we find that it occupies such a position that it would be exposed1 successively or simultaneously1 to the action of ice-streams of most diverse origin4 ,i have shown that the area to the westward of ,lichfield was invaded at one period by a ,welsh glacier1 and at a subsequent one by the ,irish ,sea ,glacier1 and both of these streams entered the valley of the ,trent or some of its affluents4 ,from the eastward1 again1 the great ,north ,sea ,glacier encroached in like manner1 carrying the ,great ,chalky ,boulder-,clay even into the drainage area of the westward-flowing rivers near ,coventry4 ,the glacial geology of the ,trent ,valley from ,burton to ,nottingham has been ably dealt with by ,mr4 ,r4 ,m4 ,deeley1,,bt who recognises a succession which may be generalised as follows3 7#a47 ,a lower series containing rocks derived from the ,pennine chain2 7#b47 ,a middle series containing rocks from the eastward 7chalky boulder-clay1 etc472 and 7#c47 ,an upper series with ,pennine rocks4 ,mr4 ,deeley thinks the ,pennine dbris may have been brought by glaciers flowing down the valleys of the ,dove1 the ,wye1 and the ,derwent2 but1 while recognising the importance of the testimony adduced1 especially that of the boulders1 ,i am compelled to reserve judgment upon this point until something like moraines or other evidences of local glaciers can be shown in those valleys4 ,in their upper parts there is not a sign of glaciation4 ,some of the deposits described must have been laid down by land-ice2 while the conformation of the country shows that during some stages of glaciation a lake must have existed into which the different elements of the converging glaciers must have projected4 ,this condition will account for the remarkable commingling of boulders observed in some of the deposits4 ,welsh1 ,cumbrian1 and ,scottish rocks occur in the western portion of the ,trent ,valley4 ,the overflow of the extra-morainic lake would find its way into the valleys of the ,avon and ,severn1 and may be taken to account for the abundance of flints in some of the gravels4 ,footnote ,,bt3 ,quarterly ,journal ,geological ,society1 vol4 xlii1 p4 #dcg4 ,the ,isle of ,man4--,this little island in mid-seas constituted in the early stages of the ,glacial epoch an independent centre of glaciation1 and from some of its valleys ice-streams undoubtedly descended to the sea2 but with the growth of the great ,irish ,sea ,glacier the native ice was merged in the invading mass1 and at the climax of the period the whole island was completely buried1 even to its highest peak 7,snae ,fell1 #b1jed feet71 beneath the ice4 ,the effects of this general glaciation are clearly seen in the mantle of unstratified drift material which overspread the hills2 in the moutonne appearance of the entire island2 and in the transport of boulders of local rocks4 ,the striations upon rock surfaces show a constancy of direction in agreement with the boulder-transport which can be ascribed to no other agency than a great continuous sheet of such dimensions as to ignore minor hills and valleys4 ,the disposition of the stri is equally conclusive1 for we find that on a stepped escarpment of limestone both the horizontal and the vertical faces are striated continuously and obliquely from the one on to the other1 showing that the ice had a power of accommodating itself to the surface over which it passed that could not be displayed by floating ice4 ,there is a remarkable fact concerning the distribution of boulders on this island which would strike the most superficial observers1 namely1 that foreign rocks are confined to the low grounds4 ,it might be argued that the local ice always retained its individuality1 and so kept the foreign ice with its characteristic boulders at bay4 ,but1 apart from the a priori improbability of so small a hill-cluster achieving what the ,lake ,district could not accomplish1 the fact that ,snae ,fell1 an isolated conical hill1 is swathed in drift from top to bottom1 is quite conclusive that the foreign ice must have got in4 ,why1 then1 did it carry no stones with it8 ,the following suggestion ,i make not without misgivings1 though there are many facts to which ,i might appeal that seem strongly corroborative3 ,the hilly axis of the island runs in a general northeast and southwest direction1 and it rises from a great expanse of drift in the north with singular abruptness1 some of the hills being almost inaccessible to a direct approach without actual climbing4 ,i imagine that the ice which bore down upon the northern end of the island was1 so far as its lower strata were concerned1 unable to ascend so steep an acclivity1 and was cleft1 and flowed to right and left4 ,the upper ice1 being of ice-sheet origin1 would be relatively clean1 and this flowing straight over the top of the obstruction would glaciate the country with such material as was lying loose upon the ground or could be dislodged by mere pressure4 ,it would appear from published descriptions that the ,isle of ,arran offers the same problem1 and ,i would suggest the application of the same solution to it4 ,marine shells occur in the ,manx drift1 but only in such situations as were reached by the ice-laden with foreign stones4 ,they present similar features of association of shells of different habitat1 and perhaps of geological age1 to those already referred to as being common characteristics of the shell-faunas of the drift of the mainland4 ,four extinct species of mollusca have been recognised by me in the ,manx drift4 ,the ,manx drift is of great interest as showing1 perhaps better than any locality yet studied1 those features of the distribution of boulders of native rocks which attest so clearly the exclusive action of land-ice4 ,there are in the island many highly characteristic igneous rocks1 and ,i have found that boulders of these rocks never occur to the northward of the parent mass1 and very rarely in any direction except to the southwest4 ,cumming observed in regard to one rock1 the ,foxdale granite1 that whereas the highest point at which it occurs in situ was #feg feet above sea-level1 boulders of it occurred in profusion within #bjj feet of the summit of ,south ,barrule 7#a1ehe feet71 a hill two miles only1 in a southwesterly direction1 from the granite outcrop4 ,they also occur on the summit of ,cronk-na-,irrey-,lhaa1 #a1ddi feet above sea-level4 ,the vertical uplift has been #gbh and #gib feet respectively4 ,in the low grounds of the north of the island a finely developed terminal moraine extends in a great sweep so as to obstruct the drainage and convert thousands of acres of land into lake and morass1 which is only now yielding to artificial drainage4 ,many fine examples of drumlin and esker mounds occur at low levels in different parts of the island2 and it was remarked nearly fifty years ago by ,cumming1 that their long axes were parallel to the direction of ice-movement indicated by the striated surfaces and the transport of boulders4 ,the foreign boulders are mainly from the granite mountains of ,galloway1 but there are many flints1 presumably from ,antrim1 a very small number of ,lake ,district rocks1 and a remarkable rock containing the excessively rare variety of hornblende1 ,riebeckite4 ,this has now been identified with a rock on ,ailsa ,crag1 a tiny islet in the ,frith of ,clyde2 and a ,manx geologist1 the ,rev4 ,s4 ,n4 ,harrison1 has discovered a single boulder of the highly characteristic pitchstone of ,corriegills1 in the ,isle of ,arran4 ,the ,so-called ,great ,submergence4 ,it may be convenient to adduce some additional facts which render the theory of a great submergence of the country south of the ,cheviots untenable4 ,the sole evidence upon which it rests is the occurrence of shells1 mostly in an extremely fragmentary condition1 in deposits occurring at various levels up to about #a1djj feet above sea-level3 ,a little space may profitably be devoted to a criticism of this evidence4 ,moel ,tryfaen 7',the ,hill of the ,three ,rocks'74--,this celebrated locality is on the first rise of the ground between the ,menai ,straits and the congeries of hills constituting ',snowdonia'2 and when we look to the northward from the top of the hill 7#a1cej feet7 we see the ground rising from the straits in a series of gentle undulations whose smooth contours would be found from a walk across the country to be due to the thick mask of glacial deposits which obliterates the harsher features of the solid rocks4 ,the deposits on ,moel ,tryfaen are exposed in a slate-quarry on the northern aspect of the hill near the summit1 and consist of two wedges of structureless boulder-clay1 each thinning towards the top of the hill4 ,the lower mass of clay1 wherever it rests upon the rock1 contains streaks and irregular patches of eccentric form1 of sharp1 perfectly angular fragments of slate2 and the underlying rock may be seen to be crushed and broken1 its cleavage-lamin being thrust over from northwest to southeast--that is1 up-hill4 ,the famous 'shell-bed' is a thick series of sands and gravels interosculated with the clays on the slope of the hill1 but occupying the entire section above the slate towards the top4 ,the bedding shows unmistakable signs of the action of water1 both regular stratification and false bedding being well displayed4 ,the stones occurring in the clays are mainly if not entirely ,welsh1 including some from the interior of the country1 and they are not infrequently of large size--two or three tons' weight--and well scratched4 ,the stones found in the sands and gravels include a great majority of local rocks1 but besides these there have been recorded the following3 ,rock4 ,source4 ,highest ,minimum point uplift in situ4 in feet4 ,granite ,eskdale1 ,cumberland #a1bhf #fd ,granite ,criffel1 ,galloway 44444 444 ,flint ,antrim 787 #a1jjj #cej ,to these ,i can add3 ,granophyre ,buttermere1 ,cumberland 44444 444 ,eurite ,,bu ,ailsa ,craig1 ,frith of ,clyde #a1jig #bec ,footnote ,,bu3 ,the altitude at which this rock occurs on ,ailsa ,craig has not been announced1 so #a have put it as the extreme height of the island4 ,the shells in the ,moel ,tryfaen deposit have been fully described1 so far as the enumeration of species and relative frequency are concerned1 but little has been said as to their absolute abundance and their condition4 ,the shells are extremely rare1 and daring a recent visit a party of five persons1 in an assiduous search of about two hours1 succeeded in finding five whole shells and about two ounces of fragments4 ,the opportunities for collecting are as good as could be desired4 ,the sections exposed have an aggregate length of about a quarter of a mile1 with a height varying from ten to twenty feet of the shelly portion2 and besides this there are immense spoil-banks1 upon whose rain-washed slopes fossil-collecting can be carried on under the most favorable conditions4 ,i would here remark1 that the occurrence of small seams of shelly material of exceptional richness has impressed collectors with the idea that they were dealing with a veritable shell-bed1 when the facts would bear a very different interpretation4 ,a fictitious abundance is brought about by a process of what may be termed 'concentration1' by the action of a gently flowing current of water upon materials of different sizes and different specific gravities4 ,shells when but recently vacated consist of materials of rather high specific gravity1 penetrated by pores containing animal matter1 so that the density of the whole mass is far below that of rocks in general1 and hence a current too feeble to move pebbles would yet carry shells4 ,illustrations of this process may be observed upon any shore in the concentration of fragments of coal1 corks1 or other light material4 ,regarding the interpretation of these facts3 ,the commonly received idea is1 that the beds were laid down in the sea during a period of submergence1 and that the shells lived1 not perhaps on the spot1 but somewhere near1 and that the terminal curvature of the slate was produced by the grounding of icebergs which also brought the boulders4 ,but if this hypothesis were accepted1 it would be necessary to invest the flotation of ice with a constancy of direction entirely at variance with observed facts1 for the phenomena of terminal curvature is shown with perfect persistence of direction wherever the boulder-clay rests upon the rock2 and1 further1 there is the highly significant fact1 that neither the sands and gravels nor the rock upon which they rest show any signs of disturbance or contortion1 such as must have been produced if floating ice had been an operative agent4 ,the uplift of foreign rocks is equally significant2 and when we take into account the great distances from which they have been borne and the frequency with which such an operation must have been repeated1 the inadequacy becomes apparent of ,darwin's ingenious suggestion1 that it might have been effected by a succession of uplifts by shore-ice during a period of slow subsidence2 while the character and abundance of the molluscan remains invest with a species of irony the application of the term 'shell-bed' to the deposit4 ,i now turn to the alternative explanation 7see ante1 p4 #ade71 viz41 that the whole of the phenomena were produced by a mass of land-ice which was forced in upon ,moel ,tryfaen from the north or northwest1 overpowering any ,welsh ice which obstructed its course4 ,this view is in harmony with the observations regarding the 'terminal curvature' of the slates1 the occurrence of sharp angular chips of slate in the boulder-clay1 and the coincidence of direction of these indications of movement with the carry of foreign stones4 ,the few shells and shell-crumbs in the sands and gravels would1 upon this hypothesis1 be the infinitesimal relics of huge shell-banks in the ,irish ,sea which were destroyed by the glacier and in part incorporated in its ground-moraine or involved in the ice itself4 ,the sands and gravels would represent the wash which would take place wherever1 by the occurrence of a 'nunatak' or by approach to the edge of the ice1 water could have a free escape4 ,two principal objections have been urged to the land-ice explanation of the ,moel ,tryfaen deposits4 ,an able critic asks1 ',can1 then1 ice walk up-hill8' ,to this we answer1 ,given a sufficient 'head' behind it1 and ice can certainly achieve that feat1 as every roche moutonne proves4 ,if it be granted that ice on the small scale can move up-hill1 there is no logical halting-place between the uplift of ten or twenty feet to surmount a roche moutonne1 and an equally gradual elevation to the height of ,moel ,tryfaen4 ,furthermore1 the inland ice of ,greenland is known to extrude its ground-moraine on the 'weather-side' of the nunataks1 and the same action would account for the material uplifted on ,moel ,tryfaen4 ,the second objection brought forward was couched in somewhat these terms3 ',if the ,lake ,district had its ice-sheet1 surely ,wales had one also4 ,could not ,snowdonia protect the heart of its own domain8' ,of course1 ,wales had its ice-sheet1 and the question so pointedly raised by the objector needs an answer2 and though it is merely a question of how much force is requisite to overcome a certain resistance 7both factors being unknown71 still there are features in the case which render it specially interesting and at the same time comparatively easy of explanation4 ,it seems rather like stating a paradox1 yet the fact is1 that it was the proximity of ,snowdon which1 in my opinion1 enabled the foreign ice to invade ,wales at that point4 ,a glance at the map will show that the 'radiant point' of the ,welsh ice was situated on or near ,arenig ,mawr1 and that the great mass of ,snowdon stands quite on the periphery of the mountainous regions of ,north ,wales1 so that it would oppose its bulk to fend off the native ice-sheet and prevent it from extending seaward in that direction4 ,illustration3 ,fig4 #df4--,section across ,wales to show the relationship of native to foreign ice4 ,as a consequence1 the only ,welsh ice in position to obstruct the onward march of the invader would be such trifling valley-glaciers as could form on the western slopes of ,snowdon itself4 ,the peak of ,snowdon is #c1egj feet above sea-level1 and ,arenig ,mawr1 #b1hag feet high1 is eighteen miles to the eastward1 and a broad1 deep valley with unobstructed access to ,cardigan ,bay intervenes2 so1 if any ice from the central mass made its way over the ,snowdonian range1 it performed a much more surprising feat than that involved in the ascent of ,moel ,tryfaen from the westward4 ,the profile shows in diagrammatic form the probable relations of the foreign to the native ice at the time when the ,moel ,tryfaen deposits were laid down4 ,from what has been said regarding the great glaciers1 it would seem that ice advanced upon the land from the seaward in several parts of the coast of ,england1 ,wales1 and the ,isle of ,man4 ,now1 it is in precisely those parts of the country1 and those alone1 that the remains of marine animals occur in the glacial deposits4 ,if the dispersal of the shells found in the drift had been effected by the means ,i have suggested1 it would follow1 as an inevitable consequence1 that wherever shells occur there should also be boulders which have been brought from beyond the sea4 ,this ,i find to be the case1 and in two instances the discovery of shells was preliminary to the extension of the boundaries of the known distribution of boulders of trans-marine origin4 ,the officers of the ,geological ,survey some years ago observed the occurrence of 'obscure fragments of marine shells' in a deposit at ,whalley1 ,lancashire1 in which they could find only local rocks4 ,one case such as this would be fatal to the theory of the remani origin of the shells1 but on visiting the section with ,mr4 ,w4 ,a4 ,downham1 ,i found1 amongst the very few stones which occurred in the shell-bearing sand at the spot indicated1 two well-marked examples of ,cumbrian volcanic rocks1 and1 at a little distance1 large boulders of ,scottish granites4 ,the second case is more striking4 ,the announcement was made that shells had been found on a hill called ,gloppa near ,oswestry1 in ,shropshire1 and1 as it lay about five miles to the westward of ,mackintosh's boundary of the ,irish ,sea ,glacier1 and therefore well within the area of exclusively ,welsh boulders1 it furnished an excellent opportunity of putting the theory to the test4 ,an examination of the boulders associated with the shells showed that the whole suite of ,galloway and ,cumbrian erratics such as belong to the ,irish ,sea ,glacier were present in great abundance4 ,not only this1 but in the midst of the series of shell-bearing gravels ,i observed a thin lenticular bed of greenish clay1 which upon examination was found to be crowded with well-scratched specimens of ,welsh rocks2 but neither a morsel of shell nor a single pebble of a foreign rock could be found1 either by a careful examination in the field or by washing the clay at home1 and examining with a lens the sand and stones separated out4 ,the fact that predictions such as these have been verified affords a very striking corroboration of the theory put forward2 and1 though shells cannot be found in every deposit in which they might1 ex hypothesi1 be found1 yet the strict limitation of them to situations which conform to those assigned upon theoretical grounds cannot be ascribed to mere coincidence4 ,if the land had ever been submerged during any part of the ,glacial epoch to a depth of #a1djj feet1 it is inconceivable that clear and indisputable evidence should not be found in abundance in the sheltered valleys of the ,lake ,district and ,wales1 which would have been deep1 quiet fiords1 in which vast colonies of marine creatures would have found harbour1 as they do in the deep lochs of ,scotland to-day4 ,it has been urged1 in explanation of this absence of marine remains in the great hill-centres1 that the 'second glaciation' might have destroyed them2 but to do this would require that the ice should make a clean and complete sweep of all the loose deposits both in the hollows of the valleys and on the hill-sides1 and further that it should destroy all the shells and all the foreign stones which floated in during the submergence4 ,at the same time we should have to suppose that the drift which lay in the paths of the great glaciers was not subjected to any interference whatever4 ,but1 assuming that these difficulties were explained1 there would still remain the fact that the valleys which have never been glaciated--as1 for example1 those of ,derbyshire--show no signs whatever of any marine deposits1 nor of marine action in any form whatever4 ,the sea leaves other traces also1 besides shells1 of its presence in districts that have really been submerged1 yet there are no signs whatever to be found of them in all ,england1 except the post-glacial raised beaches4 ,furthermore1 in all the area occupied by glacial deposits there are no true sea-beaches1 no cliffs nor sea-worn caves1 no barnacle-encrusted rocks1 nor rocks bored by ,pholas or ,saxicava4 ,are we to believe that these never existed2 or that1 having existed1 they have been obliterated by subsequent denudations8 ,to make good the former proposition1 it would be necessary as a preliminary to show that the movement of subsidence and re-elevation was so rapid1 and the interval between so brief1 that no time was allowed for any marine erosion to take place4 ,if this were so1 it would be the most stupendous catastrophe of which we have any geological record2 but we are not left in doubt regarding the duration of the submerged condition1 for the occurrence of forty feet of gravel upon the summits of the hills indicates plainly that1 if they were accumulated by the sea1 the land must have stood at that level for a very long period1 amply sufficient for the formation of a well-marked coast-line4 ,the alternative proposition1 that post-glacial denudation had removed the traces of subsidence1 is equally at variance with the evidence4 ,post-glacial denudation has left kames and drumlins1 and all the other forms of glacial deposits1 in almost perfect integrity2 the small kettle-holes are not yet filled up2 and it is therefore quite out of the question that the far more enduring features1 such as sea-cliffs1 shore platforms1 and beaches1 should have been destroyed4 ,the only reasonable conclusion is1 that these evidences of marine action never existed1 because the land in glacial times was never depressed below its present level4 ,if the level were different at all 7as ,i think may have been the case on the western side of ,england71 it was higher1 and not lower4 ,the details of the submergence hypothesis have1 so far as ,i am aware1 never been dealt with by its advocates1 otherwise ,i cannot but think that it would have been abandoned long since4 ,it has been stated in general terms that the subsidence was greatest in the north and diminished to zero in the south1 but no attempt was made to trace the evidence of extreme subsidence across country and along the principal hill-ranges--in fact1 to see how it varied in every direction4 ,if we take a traverse of ,england1 say from ,flamborough ,head upon the east to ,moel ,tryfaen on the west1 and accept as evidence of submergence any true glacial deposits 7except1 as in the case of the interior of ,wales1 the deposits are obviously the effects of purely local glaciers and contain1 therefore1 no shells71 we shall find that the subsidence1 if any1 must have been not simply differential but sporadic4 ,illustration3 ,fig4 #dg4--,section of the cliff on the east side of ,south ,sea ,landing1 ,flamborough ,head4 ,scale1 #abj feet to #a inch2 length of section #bij yards2 average height1 #abe feet4 7,see above map of moraine between ,speeton and ,flamborough47 ,explanation4--#d4 ,brownish boulder-clay1 a band of pebbles2 #d;a1 in places about seven feet from top4 #c4 ,washed gravel1 with thin sand-seams1 well-bedded1 pebbles chiefly erratics4 #b4 ,basement boulder-clay1 with many included patches of sand1 gravel1 and silt2 #b;a1 at ,b1 one of these #b;b contain shells4 #a;b4 ,sand and silt1 overlying and in places interbedded with #a4 #a4 ,rubble of angular and subangular chalk-blocks and gravel1 with occasional erratic1 passes partly into chalky boulder-clay1 #a;a4 x4 ,white chalk1 without flints1 surface much shaken4 ,at ,flamborough ,head shelly drift attains an altitude of #djj feet1 but half a mile from the coast the country is practically driftless even at lower levels4 ,the ,yorkshire ,wolds were not submerged4 ,on the western flanks of the wolds drift comes in at about #ajj to #aej feet1 and persists1 probably1 under the post-glacial warp1 from which it again protrudes on the western side of the valley of the ,ouse1 and however the drift between there and the ,pennine water-shed may be interpreted1 it shows not a sign of marine origin2 but1 even granting that it did1 we find that it does not reach within a thousand feet of the water-shed4 ,when the water-shed is crossed1 however1 abundant glacial deposits are met with which are not to be differentiated from others at slightly lower levels which contain shells4 ,illustration3 ,fig4 #dh4--;,enlarged section of the shelly sand and surrounding clay at ,b in preceding figure4 ,scale1 #d feet to #a inch4 ,explanation4--#b4 ,basement boulder-clay4 #b;a4 ,pure compact blue and brown clay of aqueous origin1 bedding contorted and nearly obliterated1 but the mass is cut up by shearing planes4 #b;b4 ,irregular seam1 and scattered streaks1 of greenish-yellow sand with many marine shells4 #b;c4 ,patch of pale-yellow sand1 different from #b;b1 without trace of fossils4 ,if we suppose that the line of our traverse crosses the ,pennine ,chain at ,heald ,moor1 we shall find that on the eastern side no traces of drift occur above about #cjj feet2 while the very summit of the water-shed is occupied by boulder-clay1 and thence downward the trace is practically continuous1 and at about #a1jjj feet and downward the drift contains marine shells4 ,across the great plain of ,lancashire and ,cheshire the 'marine' drift is fully developed--though it may be remarked in parentheses that it contains a shallow-water fauna1 albeit ex hypothesi deposited1 in part at least1 in a depth of #bjj fathoms of water--and to the ,welsh border at ,frondeg1 where it again reaches a water-shed at an altitude of #a1dej feet2 but at #ajj yards to the westward of the summit all traces of subsidence disappear1 and through the centre of ,wales no sign is visible2 then we emerge on the western slopes at ,moel ,tryfaen1 and they assume their fullest dimensions1 though only to finish abruptly on the hill-top1 and put in no appearance in the lower grounds which extend from there to the sea4 ,the conclusions pointed to by the evidence 7and1 as ,i have endeavoured to show1 all the evidence which existed at the close of the ,glacial period is there still7 are1 that a subsidence of the ,yorkshire ,wolds took place on the east1 but not in the centre or west2 that the ,pennine ,chain was submerged on the western side to a depth of #a1djj feet1 and on the east to not more than #cjj feet1 even on opposite sides of the same individual hill2 that all the lowlands between1 say1 ,bacup and the ,welsh border1 were submerged1 and that the hills near ,frondeg partook of this movement1 but only on their eastern sides2 that the centre of ,wales was exempt1 but that the summit of ,moel ,tryfaen forms an isolated spot submerged1 while the surrounding country escaped4 ,these absurdities might be indefinitely multiplied1 and they must follow unless it be admitted that the phenomena are the results of glacial ice1 and that ice can move 'up-hill4' ,the south of ,england certainly has partaken of no movement of subsidence4 ,a line drawn from ,bristol to ,london will leave all the true glacial deposits to the northward1 except a bed of very questionable boulder-clay at ,watchet1 and a peculiar deposit of clayey rubble which has been produced on the flanks of the ,cornish hills probably1 as the late ,s4 ,v4 ,wood1 ,jr1 suggested1 by the slipping of material over a permanently frozen subsoil4 ,for the remainder of the southern area the evidence is plain that there has been no considerable subsidence during glacial times4 ,the presence over large areas of chalk country of the 'clay with flints'--a deposit produced by the gradual solution of the chalk and the accumulation in situ of its insoluble residue--is absolute demonstration that for immense periods of time the country has been exempt from any considerable aqueous action4 ,the enormous accumulations of china clay upon the granite bosses of ,cornwall and ,devon tell the same tale4 ,a few erratics have been found at low levels at various points on the southern coasts1 usually not above the reach of the waves4 ,these consist of rocks which may have been floated by shore-ice from the ,channel ,islands or the ,french coast4 ,this imperfect survey of the evidence against the supposed submergence has been rendered the more difficult by the fact that it is not considered necessary to produce the evidence of marine shells in all cases4 ,indeed1 it has been argued that post-,tertiary beds covering thousands of square miles might be absolutely destitute of shells without prejudice to the theory of their formation in the sea4 ,but such a suggestion1 one would think1 could hardly come from anyone familiar with marine ,tertiary deposits1 or even with the appearance of modern sea-beaches4 ,admitting1 however1 for the purposes of argument1 that the beaches along a great extent of coast might be devoid of shells1 it cannot be argued that the deep waters were destitute of life2 and hence the boulder-clays1 if of marine origin1 should contain a great abundance of shells and other remains1 and1 once entombed1 it is beyond belief that they could all be removed from such a deposit in the short lapse of post-glacial time4 ,now1 some of the boulder-clays--as1 for example1 those of ,lancashire and ,cheshire--are held to be of marine origin1 and this is indeed a vital necessity to the submergence theory2 for1 if these are not marine deposits1 neither are the other shelly deposits2 but these boulder-clays are absolutely indistinguishable from those lying within the hill-centres1 and1 as it passes belief that such deposits could be of diverse origin and yet possess an identical structure and arrangement1 then we should have a right to demand that these clays should have enclosed shells and should still contain them1 but they do not4 ,i may here mention that ,i am informed by ,mr4 ,w4 ,shone1 ,f4 ,g4 ,s4--and he was good enough to permit me to quote the statement--that the boulder-clay of ,cheshire and the shelly boulder-clay of ,caithness are 'as like as two peas4' ,the importance of this comparison lies in the fact that1 since ,croll's classical description1 all observers have agreed that it was the product of land-ice which moved in upon the land out of the ,dornoch ,firth4 ,it was pointed out then1 as since has been done for ,england1 that it was only where the direction of ice-movement was from the seaward that any shells occur in the boulder-clay4 ,the ,dispersion of ,erratics of ,shap ,granite4--,so great a significance attaches to the peculiar distribution of this remarkable rock1 that ,i may add a few details here which could not be conveniently introduced elsewhere4 ,this granite occupies an area which lies just to the northward of the water-shed between the basins of the ,lime and the ,eden1 and its extreme elevation is #a1fef feet4 ,boulders occur in large numbers as far to the northward as ,cross ,fells1 while1 as already described1 they pass over ,stainmoor and are dispersed in great numbers along the route taken by the great ,stainmoor branch of the ,solway ,glacier4 ,but a considerable number of the boulders also found their way to the southward1 and a well-marked trail can be followed down into ,morecambe ,bay2 and at ,hest ,bank1 to the north of ,lancaster1 the boulder-clay contains many examples1 together with the 'mica-trap' of the ,kendal and ,sedbergh dykes and other local rocks1 but no shells or erratics from other sources than the country draining into ,morecambe ,bay4 ,to the southward the ice which bore these rocks was deflected by the great ,irish ,sea ,glacier1 and1 so far as present information enables me to state1 the ,shap granite blocks mark the course of the medial moraine between these two ice-streams4 ,it has been found near ,garstang1 at ,longridge1 and at ,whalley1 this being the exact line of junction of the ,irish ,sea ,glacier with the ice from ,morecambe ,bay and the ,pennine ,chain4 ,it is a very remarkable and significant fact1 that not a single authentic occurrence of the rock across the boundary indicated has yet been recorded4 ,northern ,europe4 ,on passing over the shallow ,german ,sea from ,england to the ,continent1 the southern border of the ,scandinavian ice-field is found south of the ,zuyder ,zee1 between ,utrecht and ,arnhem--the moraine hills in the vicinity of ,arnhem being quite marked1 and a barren1 sandy plain dotted with boulders and irregular moraine hills extending most of the way to the ,zuyder ,zee4 ,from ,arnhem the southern boundary of the great ice-field runs eastward across the ,rhine ,valley1 along the base of the ,westphalian ,hills1 around the projecting promontory of the ,hartz1 and then southward through ,saxony to the roots of the ,erzgebirge4 ,passing next southeastward along the flanks of the ,riesen and ,sudeten chain1 it sweeps across ,poland into ,russia1 circling round by ,kiev1 and northward by ,nijni-,novgorod towards the ,urals4,,bv ,thence the boundary passes northward to the ,arctic ,ocean1 a little east of the ,white ,sea4 ,footnote ,,bv3 ,a4 ,geikie's ,text-,book of ,geology1 p4 #hhe4 ,the depth of this northern ice-sheet is proved to have been upwards of #a1djj feet where it met the ,hartz ,mountains1 for it has deposited northern dbris upon them to that height2 while1 as already shown1 it must have been over #b1jjj feet in the main valley of ,switzerland4 ,in ,norway it is estimated that the ice was between #f1jjj and #g1jjj feet thick4 ,the amount of work done by the continental glaciers of ,europe in the erosion1 transportation1 and deposition of rock and earthy material is immense4 ,according to ,helland1 the average depth of the glacial deposits over ,north ,germany and northwestern ,russia is #aej ,german feet1 i4 e41 about #ace ,english feet4 ,as the deposition towards the margin of a glacier must be commensurate with its erosion near the centre of movement1 this vast amount implies a still greater proportionate waste in the mountains of ,scandinavia1 where the area diminishes with every contraction of the circle4 ,two hundred and fifty feet is therefore not an extravagant calculation for the amount of glacial erosion in the ,scandinavian ,peninsula4 ,it is not difficult to see how the ,scandinavian mountains were able to contribute so much soil to the plains of northern ,germany and northwestern ,russia4 ,previous to the ,glacial period1 a warm climate extended so far north as to permit the growth of semi-tropical vegetation in ,spitsbergen1 ,greenland1 and the northern shores of ,british ,america4 ,such a climate1 with its abundant moisture and vegetation1 afforded most favourable conditions for the superficial disintegration of the rocks4 ,when1 therefore1 the cold of the ,glacial period came on1 the moving currents of ice would have a comparatively easy task in stripping the mantle of soil from the hills of ,norway and ,sweden1 and transporting it towards the periphery of its movement4 ,of course1 erosion in ,scandinavia meant subglacial deposition beyond the ,baltic4 ,doubtless1 therefore1 the plains of northern ,germany1 with their great depth of soil1 are true glacial deposits1 whose inequalities of surface have since been much obliterated1 through the general influences of the lapse of time1 and by the ceaseless activity of man4 ,an interesting series of moraines in the north of ,germany1 bordering the ,baltic ,sea1 was discovered in #ahhh by ,professor ,salisbury1 of the ,united ,states ,geological ,survey4 ,its course lies through ,schleswig-,holstein1 ,mecklenburg1 ,potsdam 7about forty miles north of ,berlin71 thence swinging more to the north1 and following nearly the line between ,pomerania and ,west ,prussia1 crossing the ,vistula about twenty miles south of ,dantzic1 thence easterly to the ,spirding ,see1 near the boundary of ,poland4 ,among the places where this moraine can be best seen are--#a4 ,in ,province ,holstein1 the region about 7especially north of7 ,eutin2 #b4 ,province ,mecklenburg1 north of ,crivitz1 and between ,btow and ,krpelin2 #c4 ,province ,brandenburg1 south of ,reckatel1 between ,strassen and ,brenbusch1 south of ,frstenberg and north of ,everswalde1 and between ,pyritz and ,solden2 #d4 ,province ,posen1 east of ,locknitz1 and at numerous points to the south1 and especially about ,falkenburg1 and between ,lompelburg and ,brwalde4 ,this is one of the best localities4 #e4 ,province ,west ,preussen1 east of ,btow2 #f4 ,province ,ost ,preussen1 between ,horn and ,widikin4 ,comparing these with the moraines of ,america1 ,professor ,salisbury remarks3 ,in its composition from several members1 in its variety of development1 in its topographic relations1 in its topography1 in its constitution1 in its associated deposits1 and in its wide separation from the outermost drift limit1 this morainic belt corresponds to the extensive morainic belt of ,america1 which extends from ,dakota to the ,atlantic ,ocean4 ,that the one formation corresponds to the other does not admit of doubt4 ,in all essential characteristics they are identical in character4 ,what may be their relations in time remains to be determined4 ,illustration3 ,fig4 #di4--,map showing the glaciated area of ,europe according to ,j4 ,geikie1 and the moraines in ,britain and ,germany according to ,lewis and ,salisbury4 ,the physical geography of ,europe is so different from that of ,america1 that there was a marked difference in the secondary or incidental effects of the ,glacial period upon the two regions4 ,in ,america the continental area over which the glaciers spread is comparatively simple in its outlines4 ,east of the ,rocky ,mountains1 as we have seen1 the drainage of the ,glacial period was1 for a time1 nearly all concentrated in the ,mississippi basin1 and the streams had a free course southward4 ,but in ,europe there was no free drainage to the south1 except over a small portion of the glaciated area in central ,russia1 about the head-waters of the ,dnieper1 the ,don1 and the ,volga2 though the ,danube and the ,rhne afforded free course for the waters of a portion of the great ,alpine glaciers4 ,but all the great rivers of northern ,europe flow to the northward1 and1 with the exception of the ,seine1 they all for a time encountered the front of the continental ice-sheet4 ,this circumstance makes it difficult to distinguish closely between the direct glacial deposits in ,europe and those which are more or less modified by water-action4 ,at first sight it would seem also somewhat hazardous to attempt to correlate with any portion of the ,glacial period the deposition of the gravelly and loamy deposits in valleys1 which1 like those of the ,seine and ,somme1 lie entirely outside of the glaciated area4 ,upon close examination1 however1 the elements of doubt more and more disappear4 ,the ,glacial period was one of great precipitation1 and it is natural to suppose that the area of excessive snow-fall extended considerably beyond the limit of the ice-front4 ,during that period therefore1 the rivers of central ,france must have been annually flooded to an extent far beyond anything which is known at the present time4 ,since these rivers flowed to the northward1 at a period when1 during the long and severe winters1 the annual accumulation of ice near their mouths was excessive1 ice-gorges of immense extent1 such as now form about the mouths of the ,siberian rivers1 would regularly occur4 ,we are not surprised1 therefore1 to find1 even in these streams1 abundant indications of the indirect influence of the great northern ice-sheet4 ,the indications referred to consist of high-level gravel terraces occasionally containing boulders1 of from four to five tons weight1 which have been transported for a considerable distance4 ,the elevation of the terraces above the present flood-plains of the ,seine and ,somme reaches from #ajj to #aej feet4 ,we are not to suppose1 however1 that even in glacial times the floods of the river ,seine could have filled its present valley to that height4 ,the highest flood in this river known in historic times rose only to a height of twenty-nine feet4 ,mr4 ,prestwich estimates that1 without taking into consideration the more rapid discharge1 a flood of sixty times this magnitude would be required to fill the present valley to the level of the ancient gravels1 while at ,amiens the shape of the valley of the ,somme is such that five hundred times the mean average of the stream would be required to reach the high-level gravels4 ,the conclusion1 therefore1 is that the troughs of these streams have been largely formed by erosion since the deposition of the high-level gravels4 ,connected with these terrace gravels in northern ,france is a loamy deposit1 corresponding to the loess in other parts of ,europe1 and to a similar deposit to which we have referred in describing the southwestern part of the glaciated area in ,north ,america4 ,in northern ,france this fine silt overlies the high-level gravel deposits1 and1 as ,mr4 ,prestwich has pretty clearly shown1 was deposited contemporaneously with them during the early inundations and before the stream had eroded its channel to its present level4 ,the distribution of loess in ,europe was doubtless connected with the peculiar glacial conditions of the continent4 ,its typical development is in the valley of the ,rhine1 where it is described by ,professor ,james ,geikie as a yellow or pale greyish-brown1 fine-grained1 and more or less homogeneous1 consistent1 non-plastic loam1 consisting of an intimate admixture of clay and carbonate of lime4 ,it is frequently minutely perforated by long1 vertical1 root-like tubes which are lined with carbonate of lime--a structure which imparts to the loess a strong tendency to cleave or divide in vertical planes4 ,thus it usually presents upright bluffs or cliffs upon the margins of streams and rivers which intersect it4 ,very often it contains concretions or nodules of irregular form4444 ,land-shells and the remains of land animals are the most common fossils of the loess1 but occasionally fresh-water shells and the bones of fresh-water fish occur4 ,from the margins of the modern alluvial flats which form the bottoms of the valleys it rises to a height of #bjj or #cjj feet above the streams--sweeping up the slopes of the valleys1 and imparting a rich productiveness to many districts which would otherwise be comparatively unfruitful4 ,from the ,rhienthal itself it extends into all the tributary valleys--those of the ,neckar1 the ,main1 the ,lahn1 the ,moselle1 and the ,meuse1 being more or less abundantly charged with it4 ,it spreads1 in short1 like a great winding-sheet over the country--lying thickly in the valleys and dying off upon the higher slopes and plateaux4 ,wide and deep accumulations appear likewise in the ,rhne ,valley1 as also in several other river-valleys of ,france1 as in those of the ,seine1 the ,sane1 and the ,garonne1 and the same is the case with many of the valleys of middle ,germany1 such as those of the ,fulda1 the ,werra1 the ,weser1 and the upper reaches of the great basin of the ,elbe4 ,it must not be supposed that the loess is restricted to valleys and depressions in the surface of the ground4 ,it is true that it attains in these its greatest thickness1 but extensive accumulations may often be followed far into the intermediate hilly districts and over the neighbouring plateaux4 ,thus the ,odenwald1 the ,taunus1 the ,vogelgebirge1 and other upland tracts1 are cloaked with loess up to a considerable height4 ,crossing into the drainage system of the ,danube1 we find that this large river and many of its tributaries flow through vast tracts of loess4 ,lower ,bavaria is thickly coated with it1 and it attains a great development in ,bohemia1 ,upper and ,lower ,austria1 and ,moravia--in the latter country rising to an elevation of #a1cjj feet4 ,it is equally abundant in ,hungary1 ,galicia1 ,bukowina1 and ,transylvania4 ,from the ,danubian flat lands and the low grounds of ,galicia it stretches into the valleys of the ,carpathians1 up to heights of #hjj and #b1jjj feet4 ,in some cases it goes even higher--namely1 to #c1jjj feet1 according to ,zeuschner1 and to #d1jjj or #e1jjj feet1 according to ,korzistka4 ,these last great elevations1 it will be understood1 are in the upper valleys of the northern ,carpathians4 ,in ,roumania loess is likewise plentiful1 but it has not been observed south of the ,balkans4 ,east of the ,carpathians--that is to say1 in the regions watered by the ,dniester1 the ,dnieper1 and the ,don--loess appears also to be wanting1 and to be represented by those great steppe-deposits which are known as ,tchernozen1 or black earth4,,bw ,footnote ,,bw3 ,prehistoric ,europe1 pp4 #add-adf4 ,the shells found in the loess indicate both a colder and a wetter climate during its deposition than that which now exists4 ,the relics of land animals are infrequently found in the deposit1 yet they do occur1 but mostly in fragmentary condition--the principal animals represented being the mammoth1 the rhinoceros1 the reindeer1 and the horse2 which is about the same variety as is found in the gravel deposits of the ,glacial period1 both in western ,europe and in ,america4 ,a species of loess--differing1 however1 somewhat in color from that on the ,rhine--covers the plains of northeastern ,france up to an elevation of #gjj feet above the the sea1 where1 as we have already said1 it overlies the high-level gravels of the ,seine and the ,somme4 ,above this height the superficial soil in ,france is evidently merely the decomposed upper surface of the native rock4 ,the probable explanation of all these deposits1 included under the term loess1 is the same as that already given by ,prestwich of the loamy deposits of northern ,france4 ,but in case of rivers1 which1 like the ,rhine1 encountered the ice-front in their northward flow1 a flooded condition favouring the accumulation of loess was doubtless promoted by the continental ice-barrier4 ,in the case of the ,danube and the ,rhne1 however1 where there was a free outlet away from the glaciated region1 the loess in the upper part of the valleys must have accumulated in connection with glacial floods quite similar to those which we have described as spreading over the imperfectly formed water-courses of the ,mississippi basin during the close of the ,ice age4 ,that the typical loess is of glacial origin is pretty certainly shown1 both by its distribution in front of glaciers and by its evident mechanical origin when studied under the microscope4 ,it is1 in short1 the fine sediment which gives the milky whiteness to glacial rivers4 ,in central ,russia there is a considerable area in which the glacial conditions were1 in one respect1 similar to those in the northern part of the ,mississippi ,valley in the ,united ,states4 ,in both regions the continental ice-sheet surmounted the river partings1 and spread over the upper portion of an extensive plain whose drainage was to the south4 ,the ,dnieper1 the ,don1 and the western branch of the ,volga1 like the ,ohio and the ,mississippi1 have their head-waters in the glaciated region4 ,in some other respects1 also1 there is a resemblance between the plains bordering the glaciated region in central ,russia and those which in ,america border it in the ,mississippi ,valley4 ,mr4 ,james ,geikie is of the opinion that the extensive belt of black earth adjoining the glaciated area in ,russia1 and constituting the most productive agricultural portion of the country1 derives its fertility1 as does much of the ,mississippi ,valley1 from the blanket of glacial silt spread pretty evenly over it4 ,thus it would appear that in ,europe1 as in ,america1 the ice of the ,glacial period was a most beneficent agent1 preparing the face of the earth for the permanent occupation of man4 ,on both continents the seat of empire is in the area once occupied by the advance of the great ice-movements of that desolate epoch4 ,asia4 ,east of the ,urals1 in northern ,asia1 there is no evidence of moving ice upon the land during the ,glacial period2 but at ,yakutsk1 in latitude #fb north1 the soil is frozen at the present time to an unknown depth1 and many of the ,siberian rivers1 as they approach and empty into the ,arctic ,sea1 flow between cliffs of perpetual ice or frozen ground4 ,the changes that came over this region during the ,glacial period are impressively indicated by the animal remains which have been preserved in these motionless icy cliffs4 ,in the early part of the period herds of mammoth and woolly rhinoceros roamed over the plains of ,siberia1 and waged an unequal warfare with the slowly converging and destructive forces4 ,the heads and tusks of these animals were so abundant in ,siberia that they long supplied all ,russia with ivory1 besides contributing no small amount for export to other countries4 ,in #ahgb and #ahgc as many as #b1ggj mammoth-tusks1 weighing from #adj to #afj pounds each1 were entered at the ,london clocks4,,bx ,so perfectly have the carcasses of these extinct animals been preserved in the frozen soil of northern ,siberia that when1 after the lapse of thousands of years1 floods have washed them out from the frozen cliffs1 dogs and wolves and bears have fed upon their flesh with avidity4 ,in some instances even portions of the food of these animals were found in the cavities of the teeth4 ,microscopic examination showed that they fed upon the leaves and shoots of the coniferous trees which then clothed the plains of ,siberia4 ,a skeleton and parts of the skin1 and some of the softer portions of the body of a mammoth1 discovered in #agii in the frozen cliff near the mouth of the ,lena1 was carried to ,st4 ,petersburg in #ahjf1 from which it was ascertained that this huge animal was covered with alight-coloured1 curly1 very thick-set hair one to two inches in length1 interspersed with darker-colored hair and bristles from four to eighteen inches long4,,by ,footnote ,,bx3 ,prestwich's ,geology1 vol4 ii1 p4 #dfj4 ,footnote ,,by3 ,prestwich's ,geology1 vol4 ii1 p4 #dfj4 ,in the valleys of ,sikkim and eastern ,nepaul1 in northern ,india1 glaciers formerly extended #f1jjj feet lower than now1 or to about the #e1jjj-;foot level1 and in the western ,himalayas to a still lower level4 ,the higher ranges of mountains in other portions of ,asia also show many signs of former glaciation4 ,this is specially true of the ,caucasus1 where the ancient glaciers were of vast extent4 ,according1 also1 to ,sir ,joseph ,hooker1 the cedars of ,lebanon flourish upon an ancient moraine4 ,of the glacial phenomena in other portions of ,asia little is known4 ,africa4 ,northern and even central ,africa must likewise come in for their share of attention4 ,the ,atlas ,mountains1 rising to a height of #ac1jjj feet1 though supporting none at the present time1 formerly sustained glaciers of considerable size4 ,moraines are found in several places as low as the #d1jjj-;foot level1 and one at an altitude of #d1jjj feet is from #hjj to #ijj feet high1 and completely crosses and dams up the ravine down which the glacier formerly came4 ,some have supposed that there are indubitable evidences of former glaciation in the mountain-ranges of southwestern ,africa between latitude #cj and #cc1 but the evidence is not as unequivocal as we could wish1 and we will not pause upon it4 ,the mountains of ,australia1 also1 some of which rise to a height of more than #g1jjj feet1 are supposed to have been once covered with glacial ice down to the level of #e1hjj feet1 but the evidence is at present too scanty to build upon4 ,but in ,new ,zealand the glaciers now clustering about the peaks in the middle of the ,south ,island1 culminating in ,mount ,cook1 are but diminutive representatives of their predecessors4 ,this is indicated by extensive moraines in the lower part of the valleys and by the existence of numerous lakes1 attributable1 like so many in ,europe and ,north ,america1 to the irregular deposition of morainic material by the ancient ice-sheet4,,bz ,footnote ,,bz3 ,see ,with ,axe and ,rope in the ,new ,zealand ,alps1 by ,g4 ,e4 ,mannering1 #ahia4 ,,chapter ,,vii4 ,,drainage ,,systems ,,and ,,the ,,glacial ,,period4 ,we will begin the consideration of this part of our subject1 also1 with the presentation of the salient facts in ,north ,america1 since that field is simpler than any field in the ,old ,world4 ,the natural drainage basins of ,north ,america east of the ,rocky ,mountains are readily described4 ,the ,mississippi ,river and its branches drain nearly all the region lying between the ,appalachian chain and the ,rocky ,mountains and south of the ,dominion of ,canada and of the ,great ,lakes4 ,all the southern tributaries to the ,great ,lakes are insignificant1 the river partings on the south being reached in a very short distance4 ,the drainage of the rather limited basin of the ,great ,lakes is northeastward through the ,st4 ,lawrence ,river1 leaving nearly all of the ,dominion of ,canada east of the ,rocky ,mountains to pour its surplus waters northward into ,hudson ,bay and the ,arctic ,ocean4 ,with the exception of the ,st4 ,lawrence ,river1 these are essentially permanent systems of drainage4 ,to understand the extent to which the ice of the ,glacial period modified these systems1 we must first get before our minds a picture of the country before the accumulation of ice began4 ,preglacial ,erosion4 ,reference has already been made to the elevated condition of the northern and central parts of ,north ,america at the beginning of the ,glacial period4 ,the direct proof of this preglacial elevation is largely derived from the fiords and great lake basins of the continent4 ,the word fiord is descriptive of the deep and narrow inlets of the sea specially characteristic of the coasts of ,norway1 ,denmark4 ,iceland1 and ,british ,columbia4 ,usually also fiords are connected with valleys extending still farther inland1 and occupied by streams4 ,fiords are probably due in great part to river erosion when the shores stood at considerably higher level than now4 ,slowly1 during the course of ages1 the streams wore out for themselves immense gorges1 and were assisted1 perhaps1 to some extent by the glaciers which naturally came into existence during the higher continental elevation4 ,the present condition of fiords1 occupied as they usually are by great depths of sea-water1 would be accounted for by recent subsidence of the land4 ,in short1 fiords seem essentially to be submerged river gorges1 partially silted up near their mouths1 or perhaps partially closed by terminal moraines4 ,it is not alone in northwestern ,europe and ,british ,columbia that fiords are found1 but they characterize as well the eastern coast of ,america north of ,maine1 while even farther south1 both on the ,atlantic and on the ,pacific coast1 some extensive examples exist1 whose course has been revealed only to the sounding-line of the ,government survey4 ,the most remarkable of the submerged fiords in the middle ,atlantic region of the ,united ,states is the continuation of the trough of ,hudson ,river beyond ,new ,york ,bay4 ,as long ago as #ahdd the work of the ,united ,states ,coast ,survey showed that there was a submarine continuation of this valley1 extending through the comparatively shallow waters eighty miles or more seaward from ,sandy ,hook4 ,illustration3 ,fig4 #ej4--,map showing old channel and mouth of the ,hudson 7dewberry74 ,the more accurate surveys conducted from #ahhj to #ahhd have brought to our knowledge the facts about this submarine valley almost as clearly as those relating to the inland portion of it above ,new ,york city4 ,according to ,mr4 ,a4 ,lindenkohl1,,ca this submarine valley began to be noticeable in the soundings ten miles southeast of ,sandy ,hook4 ,the depth of the water where the channel begins is nineteen fathoms 7#aad feet74 ,ten miles out the channel has sunk ninety feet below the general depth of the water on the bank1 and continues at this depth for twenty miles farther4 ,this narrow channel continues with more or less variation for a distance of seventy-five miles1 where it suddenly enlarges to a width of three miles and to a depth of #bjj fathoms1 or #a1bjj feet1 and extends for a distance of twenty-five miles1 reaching near that point a depth of #dgd fathoms1 or #b1hdd feet4 ,according to ,mr4 ,lindenkohl1 this ravine maintains for half its length a vertical depth of more than #b1jjj feet1 measuring from the top of its banks1 and the banks have a nearly uniform slope of about #ad4 ,the mouth of the ravine opens out into the deep basin of the central ,atlantic4 ,footnote ,,ca3 ,bulletin of the ,geological ,society of ,america1 vol4 i1 p4 #efd2 ,american ,journal of ,science1 ,june1 #ahia4 ,with little question there is brought to light in these remarkable investigations a channel eroded by the extension of the ,hudson ,river1 into the bordering shelf of the ,atlantic basin at a time when the elevation of the continent was much greater than now4 ,this is shown to have occurred in late ,tertiary or post-,tertiary times by the fact that the strata through which it is worn are the continuation of the ,tertiary deposits of ,new ,jersey4 ,the subsidence to its present level has probably been gradual1 and1 according to ,professor ,cook1 is still continuing at the rate of two feet a century4 ,similar submarine channels are found extending out from the present shore-line to the margin of the narrow shelf bordering the deep water of the central ,atlantic running from the mouth of the ,st4 ,lawrence ,river1 through ,st4 ,lawrence ,bay1 and through ,delaware and ,chesapeake ,bays4,,cb ,all these submerged fiords on the ,atlantic coast were probably formed during a continental elevation which commenced late in the ,tertiary period1 and reached the amount of from #b1jjj to #c1jjj feet in the northern part of the continent4 ,footnote ,,cb3 ,see ,lindenkohl in ,american ,journal of ,science1 for ,june1 #ahia4 ,illustration3 ,fig4 #ea4--,new ,york harbor in preglacial times looking south1 from south end of ,new ,york ,island 7,newberry74 ,to this period must probably be referred also the formation of the gorge1 or more properly fiord1 of the ,saguenay1 which joins the ,st4 ,lawrence below ,quebec4 ,the great depth of this fiord is certainly surprising1 since1 according to ,sir ,william ,dawson1 its bottom1 for fifty miles above the ,st4 ,lawrence1 is #hdj feet below the sea-level1 while the bordering cliffs are in some places #a1ejj feet above the water4 ,the average width is something over a mile4 ,it seems impossible to account for such a deep gorge extending so far below the sea-level1 except upon the supposition of a long-continued continental elevation1 which should allow the stream to form a caon to an extent somewhat comparable with that of the caons of the ,colorado and other rivers in the far ,west4 ,then1 upon the subsidence of the continent to the present level1 it would remain partially or wholly submerged1 as we find it at the present time4 ,during the ,glacial period it was so filled with ice as to prevent silting up4 ,the rivers entering the ,pacific ,ocean1 both in the ,united ,states and in ,british ,columbia1 are also lost in submerged channels extending out to the deeper waters of the ,pacific basin in a manner closely similar to the ,atlantic streams which have been mentioned4 ,during this continental elevation which preceded1 accompanied1 and perhaps brought on the ,glacial period1 erosion must have proceeded with great intensity along all the lines of drainage1 and throughout the whole region which is now covered1 and to a considerable extent smoothed over1 by glacial deposits1 and the whole country must have presented a very different appearance from what it does now4 ,a pretty definite idea of its preglacial condition can probably be formed by studying the appearance of the regions outside of and adjoining that which was covered by the continental glacier4 ,the contrast between the glaciated and the unglaciated region is striking in several respects aside from the presence and absence of transported rocks and other dbris1 but in nothing is it greater than in the extent of river erosion which is apparent upon the surface4 ,for example1 upon the western flanks of the ,alleghanies the regions south of the glacial limit is everywhere deeply channeled by streams4 ,indeed1 so long have they evidently been permitted to work in their present channels that1 wherever there have been waterfalls1 they have receded to the very head-waters1 and no cataracts exist in them at the present time4 ,nor are there in the unglaciated region any lakes of importance1 such as characterize the glaciated region4 ,if there have been lakes1 the lapse of time has been sufficient for their outlets to lower their beds sufficiently to drain the basins dry4 ,on entering the glaciated area all this is changed4 ,the ice-movement has everywhere done much to wear down the hills and fill the valleys1 and1 where there was dbris enough at command1 it has obliterated the narrow gorges originally occupied by the preglacial streams4 ,thus it has completely changed the minor lines of superficial drainage1 and in many instances has produced most extensive and radical changes in the whole drainage system of the region4 ,in the glaciated area1 channels buried beneath glaciated dbris are of frequent occurrence1 while many of the streams which occupy their preglacial channels are flowing at a very much higher level than formerly1 the lower part of the channel having been silted up by the superabundant dbris accessible since the glacial movement began4 ,buried ,outlets and ,channels4 ,it is easy to see how the great number of shallow lakes which frequent the glaciated region were formed by the irregular deposition of glacial dbris1 but it is somewhat more difficult to trace out the connection between the ,glacial period and the ,great ,lakes of ,north ,america1 several of which are of such depth that their bottoms are some hundreds of feet below the sea-level1 ,lake ,erie furnishing the only exception4 ,this lake is so shallow that it is easy to see how its basin may have been principally formed by river erosion1 while it is evident that such must have been the mode of its formation1 since it is surrounded by sedimentary strata lying nearly in a horizontal position4 ,illustration3 ,fig4 #eb4--,section across the valley of the ,cuyahoga ,river1 twenty miles above its mouth 7,claypole74 ,that ,lake ,erie is really nothing but a glacial mill-pond is proved also by much direct evidence1 especially that derived from the depth of the buried channels of the streams flowing into it from the south4 ,of these1 the ,cuyahoga ,river1 which enters the lake at ,cleveland1 has been most fully investigated4 ,in searching for oil1 some years ago1 borings were made at many places for twenty-five miles above the mouth of the river4 ,as a result1 it appeared that for the whole distance the rocky bottom of the gorge was about two hundred feet below the present bottom of the river1 while the river itself is two or three hundred feet below the general level of the country1 occupying a trough about half a mile in width1 with steep1 rocky sides4 ,these facts indicate that at one time the river must have found opportunity to discharge its contents at a level two hundred feet below that of the present lake1 while an examination of the material filling up the bottom of the gorge to its present level shows it to be glacial dbris1 thus proving that the silting up was accomplished during the ,glacial period4 ,as the water of ,lake ,erie is for the most part less than one hundred feet in depth1 and is nowhere much more than two hundred feet deep1 it is clear that the preglacial outlet which drained it down to the level of the rocky bottom of the ,cuyahoga ,river must have destroyed the lake altogether4 ,hence ,ave may be certain that1 before the ,glacial period1 the area now covered by the lake was simply a broad1 shallow valley through which there coursed a single river of great magnitude1 with tributary branches occupying deep gorges4 ,professor ,j4 ,w4 ,spencer has shown with great probability that the old line of drainage from ,lake ,erie passed through the lower part of the valley of ,grand ,river1 in ,canada1 and entered ,lake ,ontario at its western extremity1 and that during the great ,ice age this became so completely obstructed with glacial dbris as to form an impenetrable dam1 and to cause the pent-up water to flow through the ,niagara ,valley1 which chanced to furnish the lowest opening4 ,in speaking of the present area of ,lake ,erie1 however1 as being then occupied by a river valley1 we do not mean to imply that it was not afterwards greatly modified by glacial erosion2 for undoubtedly this was the case1 whatever views we may have as to the relative efficiency of ice and water in scooping out lake basins4 ,in the case of ,lake ,erie1 we need suppose no change of level to account for the erosion of its basin1 but only that1 since the strata in which it is situated were deposited1 time enough had elapsed for a great river to cut a gorge extending from the western end of ,lake ,ontario through to the present bed of ,lake ,erie1 and that here a great enlargement of the valley was occasioned by the existence of deep beds of soft shale which could easily be worn away by a ramifying system of tributary streams4 ,rivers acting at present relative levels would be amply sufficient to produce the results which are here manifest4 ,but in the case of ,lakes ,ontario1 ,huron1 ,michigan1 and ,superior1 whose depths descend considerably below the sea-level1 we must suppose that they were1 in the main1 eroded when the continent was so much elevated that their bottoms were brought above tide-level4 ,the depth of ,lake ,ontario implies the existence of an outlet more than four hundred feet lower than at present1 which1 of course1 could exist only when the general elevation was more than four hundred feet greater than now4 ,the existence of an outlet at that depth seems to be proved also by the fact that at ,syracuse1 where numerous wells have been sunk to obtain brine for the manufacture of salt1 deposits of sand1 gravel1 and rolled stones1 four hundred and fifty feet thick1 are penetrated without reaching rock4 ,since this lies in the basin of ,lake ,ontario1 it follows that if the basin itself has been produced by river erosion1 the land must have been of sufficient height to permit an outlet through a valley1 or caon1 of the required depth1 and this outlet must now be buried beneath the abundant glacial dbris that covers the region4 ,professor ,newberry1 who has studied the vicinity carefully1 is of the opinion that there is ample opportunity for such a line of drainage to have extended through the ,mohawk ,valley to the ,hudson ,river4 ,but1 at ,little ,falls1 a spur of the ,adirondack ,mountains projects into the valley1 and the ,archan rocks over which the river runs are so prominent and continuous that some have thought it impossible for the requisite channel to have ever existed there4 ,extensive deposits of glacial dbris1 however1 are found in the vicinity1 especially in places some distance to the north1 and in ,professor ,newberry's opinion the existence of a buried channel around the obstruction upon the north side is by no means improbable4 ,the preglacial drainage of ,lake ,huron has not been determined with any great degree of probability4 ,professor ,spencer formerly supposed that it passed from the southern end of the lake through ,london1 in the western part of ,ontario1 and reached the ,erie basin near ,port ,stanley1 and so augmented the volume of the ancient river which eroded the buried caon from ,lake ,erie to ,lake ,ontario4 ,but he now supposes1 though the evidence is by no means demonstrative1 that the waters of ,lake ,huron passed into ,lake ,ontario by means of a channel extending from ,georgian ,bay to the vicinity of ,toronto4 ,with a fair degree of probability1 the basin of ,lake ,superior is supposed by ,professor ,newberry to have been joined to that of ,lake ,michigan by some passage1 now buried1 considerably to the west of the ,strait of ,mackinac1 and thence to have had an outlet southward from the vicinity of ,chicago directly into the ,mississippi ,river4 ,of this there is considerable evidence furnished by deeply buried channels which have been penetrated by borings in various places in ,kankakee1 ,livingston1 and ,mc,lean ,counties1 ,illinois2 but the whole area extending from ,lake ,michigan to the ,mississippi is so deeply covered with glacial dbris that the surface of the country gives no satisfactory indication of the exact lines of preglacial drainage4 ,some of the most remarkable instances of ancient river channels buried by the glacial deposits have been brought to light in southwestern ,ohio1 where there has been great activity in boring for gas and oil4 ,at ,st4 ,paris1 ,champaign ,county1 for example1 in a locality where the surface of the rock near by was known to be not far below the general level1 a boring was begun and continued to a depth of more than five hundred feet without reaching rock1 or passing out of glacial dbris4 ,many years ago ,professor ,newberry collected sufficient facts to show that pretty generally the ancient bed of the ,ohio ,river was as much as #aej feet below that over which it now flows4 ,during a continental elevation the erosion had proceeded to that extent1 and then the channel had been silted up during the ,glacial period with the abundant material carried down by the streams from the glaciated area4 ,one of the evidences of the preglacial depth of the channel of the ,ohio was brought to light at ,cincinnati1 where gravel and sand have been found to extend to a depth of over one hundred feet below low-water mark1 and the bottom of the trough has not been reached4 ,in the valley of ,mill ,creek1 also1 in the suburbs of ,cincinnati1 gravel and sand were penetrated to the depth of #abj feet below the stream before reaching rock4 ,but from the general appearance of the channel1 ,professor ,j4 ,f4 ,james was led to surmise that a rock bottom extended all the way across the present channel of the ,ohio1 between ,price ,hill and ,ludlow1 ,ky41 a short distance below ,cincinnati1 which would preclude the possibility of a preglacial outlet at the depth disclosed in that direction4 ,mr4 ,charles ,j4 ,bates 7who was inspector of the masonry for the ,cincinnati ,southern ,railroad while building the bridge across the ,ohio at this point7 informs me that ,mr4 ,james's surmise is certainly correct1 and that his in all probability may be displaced by certainly1 since the bedded rocks supposed by ,professor ,james to extend across the river a few feet below its present bottom were found by the engineers to be in actual existence4 ,in looking for an outlet for the waters of the upper ,ohio which should permit them to flow off at the low level reached in the channel at ,cincinnati1 ,professor ,james was led to inspect the valley extending up ,mill ,creek to the north towards ,hamilton1 where it joins the ,great ,miami4 ,the importance of ,mill ,creek ,valley is readily seen in the fact that the canal and the railroads have been able to avoid heavy grades by following it from ,cincinnati to ,hamilton4 ,as a glance at a map will show1 it is also practically but a continuation of the northerly course pursued by the ,ohio for twenty miles before reaching ,cincinnati4 ,this1 therefore1 was a natural place in which to look beneath the extensive glacial dbris for the buried channel of the ancient ,ohio1 and here in all probability it has been found4 ,the borings which have been made in ,milk ,creek ,valley north of ,cincinnati1 show that the bedded rock lies certainly thirty-four feet below the low-water mark of the ,ohio just below ,cincinnati1 while at ,hamilton1 twenty-five miles north of ,cincinnati1 where the valley of the ,great ,miami is reached1 the bedded rock of the valley lies as much as ninety feet below present low-water mark in the ,ohio4 ,other indications of the greater depth of the preglacial gorge of the ,ohio are abundant4 ,at the junction of the ,anderson with the ,ohio1 in ,indiana1 a well was sunk ninety-four feet below the level of the ,ohio before rock was found4 ,at ,louisville1 ,ky41 the occurrence of falls in the ,ohio seemed at first to discredit the theory in question1 but ,professor ,newberry was able to show that the falls at ,louisville are produced by the water's being now compelled to flow over a rocky point projecting from the north side into the old valley1 while to the south there is ample opportunity for an old channel to have passed around this point underneath the city on the south side4 ,the lowlands upon which the city stands are made lands1 where glacial dbris has filled up the old channel of the ,ohio4 ,above ,cincinnati the tributaries of the ,ohio exhibit the same phenomena4 ,at ,new ,philadelphia1 ,tuscarawas ,county1 the borings for salt-wells show that the ,tuscarawas is running #age feet above its ancient bed4 ,the ,beaver1 at the junction of the ,mahoning and ,shenango1 is flowing #aej feet above the bottom of its old trough1 as is demonstrated by a large number of oil-wells bored in the vicinity4 ,oil ,creek is shown by the same proofs to run from #ge to #ajj feet above its old channel1 and that channel had sometimes vertical and even overhanging walls4,,cc ,footnote ,,cc3 ,geological ,survey of ,ohio1 vol4 ii1 pp4 #ac1 #ad4 ,the course of preglacial drainage in the upper basin of the ,alleghany ,river is worthy of more particular mention4 ,mr4 ,carll1 of the ,pennsylvania ,geological ,survey1 has adduced plausible reasons for believing that previous to the ,glacial period the drainage of the valley of the upper ,alleghany north of the neighbourhood of ,tidioute1 in ,warren ,county1 instead of passing southward as now1 was collected into one great stream flowing northward through the region of ,cassadaga ,lake to enter the ,lake ,erie basin at ,dunkirk1 ,n4 ,y4 ,the evidence is that between ,tidioute and ,warren the present ,alleghany is shallow1 and flows over a rocky basin2 but from ,warren northward along the valley of the ,conewango1 the bottom of the old trough lies at a considerably lower level1 and slopes to the north4 ,borings show that in thirteen miles the slope of the preglacial floor of ,conewango ,creek to the north is #acf feet4 ,the actual height above tide of the old valley floor at ,fentonville1 where the ,conewango crosses the ,new ,york line1 is only #ifd feet2 while that of the ancient rocky floor of the ,alleghany at ,great ,bend1 a few miles south of ,warren1 was #a1agj feet4 ,again1 going nearer the head-waters of the ,alleghany1 in the neighbourhood of ,salamanca1 it is found that the ancient floor of the ,alleghany is1 at ,carrollton1 #gj feet lower than the ancient bed of the present stream at ,great ,bend1 about sixty miles to the south2 while at ,cole's ,spring1 in the neighbourhood of ,steamburg1 ,cattaraugus ,county1 ,n4 ,y41 there has been an accumulation of #cae feet of drift in a preglacial valley whose rocky floor is #aee feet below the ancient rocky floor at ,great ,bend4 ,unless there has been a great change in levels1 there must1 therefore1 have been some other outlet than the present for the waters collecting in the drainage basin to the north of ,great ,bend4,,cd ,footnote ,,cd3 ,for a criticism of ,mr4 ,carll's views1 see an article on ,pleistocene ,fluvial ,planes of ,western ,pennsylvania1 by ,mr4 ,frank ,leverett1 in ,american ,journal of ,science1 vol4 xlii1 pp4 #bjj-bab4 ,while there are numerous superficial indications of buried channels running towards ,lake ,erie in this region1 direct exploration has not been made to confirm these theoretical conclusions4 ,in the opinion of ,mr4 ,carll1 ,chautauqua ,lake did not flow directly to the north1 but1 passing through a channel nearly coincident with that now occupied by it1 joined the northerly flowing stream a few miles northeast from ,jamestown4,,ce ,it is probable1 however1 that ,chautauqua did not then exist as a lake1 since the length of preglacial time would have permitted its outlet to wear a continuous channel of great depth corresponding to that known to have existed in the ,conewango and upper ,alleghany4 ,footnote ,,ce3 ,second ,geological ,survey of ,pennsylvania1 vol4 iii4 ,the foregoing are but a few of the innumerable instances where the local lines of drainage have been disturbed1 and even permanently changed1 by the glacial deposits4 ,almost every lake in the glaciated region is a witness to this disturbance of the established lines of drainage by glacial action1 while in numerous places where lakes do not now exist they have been so recently drained that their shore-lines are readily discernible4 ,an interesting instance of the recent disappearance of one of these glacial lakes is that of ,runaway ,pond1 in northern ,vermont4 ,in the early part of the century the ,lamoille ,river had its source in a small lake in ,craftsbury1 ,orleans ,county4 ,the sources of the ,missisquoi ,river were upon the same level just to the north1 and the owner of a mill privilege upon this latter stream1 desiring to increase his power by obtaining access to the water of the lake1 began digging a ditch to turn it into the ,missisquoi1 but no sooner had he loosened the thin rim of compact material which formed the bottom and the sides of the inclosure1 than the water began to rush out through the underlying and adjacent quicksands4 ,this almost instantly enlarged the channel1 and drained the whole body of water oft #c in an incredibly short time4 ,as a consequence1 the torrent went rushing down through the narrow valley1 sweeping everything before it2 and nothing but the unsettled condition of the country prevented a disaster like that which occurred in #ahhi at ,johnstown1 ,pa4 ,doubtless there are many other lakes held in position by equally slender natural embankments4 ,artificial reservoirs are by no means the only sources of such danger4 ,the buried channel of the old ,mississippi ,river in the vicinity of ,minneapolis is another instructive example of the instability of many of the present lines of drainage4 ,the gorge of the ,mississippi ,river extending from ,fort ,snelling to the ,falls of ,st4 ,anthony at ,minneapolis is of post-glacial origin4 ,one evidence of this is its narrowness when contrasted with the breadth of the valley below ,fort ,snelling4 ,below this point the main trough of the ,mississippi has a width of from two to eight miles1 and the faces of the bluffs on either side show the marks of extreme age4 ,the tributary streams also have had time to wear gorges proportionate to that of the main stream1 and the agencies which oxidise and discolor the rocks have had time to produce their full effects4 ,but from ,fort ,snelling up to ,minneapolis1 a distance of about seven miles1 the gorge is scarcely a quarter of a mile in width1 and the faces of the high1 steep bluffs on either side are remarkably fresh looking by comparison with those below2 while the tributary gorges1 of which that of the ,minnehaha ,river is a fair specimen1 are very limited in their extent4 ,upon looking for the cause of this condition of things we observe that the broad trough of the ,mississippi ,river1 which had characterised it all the way below ,fort ,snelling1 continues westward1 without interruption1 up the valley of the present ,minnesota ,river1 and1 what seems at first most singular1 it does not cease at the sources of the ,minnesota1 but1 through ,lake ,traverse and ,big ,stone ,lake1 is continuous with the trough of the ,red ,river of the ,north4 ,illustration3 ,fig4 #ec4--,map of ,mississippi ,river from ,fort ,snelling to ,minneapolis and the vicinity1 showing the extent of the recession of the ,falls of ,st4 ,anthony since the great ,ice age4 ,notice the greater breadth of the valley of the ,minnesota ,river as described in the text 7,winchell74 ,deferring1 however1 for a little the explanation of this1 we will go back to finish the history of the preglacial channel around the ,falls of ,st4 ,anthony4 ,as early as the year #ahgf ,professor ,n4 ,h4 ,winchell had collected sufficient evidence from wells1 one of which had been sunk to a depth of one hundred and seventy-five feet1 to show that the preglacial course of the stream corresponding to the present ,mississippi ,river ran to the west of ,minneapolis and of the ,falls of ,minnehaha1 and joined the main valley some distance above ,fort ,snelling1 as shown in the accompanying map4 ,this condition of things was at one time very painfully brought to the notice of the citizens of ,minneapolis4 ,a large part of the wealth of the city at that time consisted of the commercial value of the water-power furnished by the ,falls of ,st4 ,anthony4 ,to facilitate the discharge of the waste water from their wheels1 some mill-owners dug a tunnel through the soft sandstone underlying the limestone strata over which the river falls2 but it very soon became apparent that the erosion was proceeding with such rapidity that in a few years the recession of the falls would be carried back to the preglacial channel1 when the river would soon scour out the channel and destroy their present source of wealth4 ,the citizens rallied to protect their property1 and spent altogether as much as half a million dollars in filling up the holes that had been thoughtlessly made2 but so serious was the task that they were finally compelled to appeal for aid to the ,united ,states ,government4 ,permanent protection was provided by running a tunnel1 some ways back from the falls1 completely across the channel1 through the soft sandstone underlying the limestone1 and filling this up with cement hard enough and compact enough to prevent the further percolation of the water from above4 ,ice-,dams4 ,the foregoing changes in lines of drainage due to the ,glacial period were produced by deposits of earthy material in preglacial channels4 ,another class of temporary but equally interesting changes were produced by the ice itself acting directly as a barrier4 ,many such lakes on a small scale are still in existence in various parts of the world4 ,the ,merjelen ,see in ,switzerland is a well-known instance4 ,this is a small body of water held back by the great ,aletsch ,glacier1 in a little valley leading to that of the ,fiesch ,glacier1 behind the ,eggischorn4 ,at irregular intervals the ice-barrier gives way1 and allows the water to rush out in a torrent and flood the valley below4 ,afterwards the ice closes up again1 and the water reaccumulates in preparation for another flood4 ,other instances in the ,alps are found in the ,mattmark ,see1 which fills the portion of the ,saas ,valley between ,monte ,rosa and the ,rhne4 ,this body of water is held in place by the ,allalin ,glacier1 which here crosses the main valley4 ,the ,lac du ,combal is held back by the ,glacier de ,miage at the southern base of ,mont ,blanc4 ,a more famous case is that of the ,gietroz ,glacier in the valley of ,bagnes1 south of ,martigny4 ,in #ahah this lake had grown to be a mile long1 and was #gjj feet wide and #bjj feet deep4 ,an attempt was made to drain it by cutting through the ice1 and about half the water was slowly drawn off in this way2 but then the barrier broke1 and the rest of the lake was emptied in half an hour1 causing a dreadful flood in the valley below4 ,in the ,tyrol1 the ,vernagt ,glacier has many times caused disastrous floods by its inability to hold up the lake formed behind it4 ,in the northwestern ,himalaya1 the upper branches of the ,indus are sometimes held back in this way4 ,a noted flood occurred in #ahce2 it advanced twenty-five miles in an hour1 and was felt three hundred miles down-stream1 destroying all the villages on the lower plain1 and strewing the fields with stones1 sand1 and mud4,,cf ,footnote ,,cf3 ,professor ,william ,m4 ,davis in4 ,proceedings of the ,boston ,society of ,natural ,history1 vol4 xxi1 pp4 #cej1 #cea4 ,in ,greenland such temporary obstructions are frequent1 forming lakes of considerable size4 ,instances occur1 in connection with the ,jakobshavn and the ,frederickshaab ,glaciers1 and in the ,north ,isortok and ,alangordlia ,fiords4 ,frequently1 also1 bodies of water of considerable size are found in depressions of the ice itself1 even at high levels4 ,i have myself seen them covering more than an acre1 and as much as a thousand feet above the sea-level1 upon the surface of the ,muir ,glacier1 ,alaska4 ,they are reported by ,mr4 ,i4 ,c4 ,russell,,cg of larger size and at still higher elevations upon the glaciers radiating from ,mount ,st4 ,elias2 while the explorers of ,greenland mention them of impressive size upon the surface of its continental ice-sheet4 ,footnote ,,cg3 ,see ,national ,geographic ,magazine1 vol4 iii1 pp4 #aaf-abj4 ,with these facts in mind we can the more readily enter into the description which will now be given of some temporary lakes of vast size which were formed by direct ice-obstructions during portions of the period4 ,one of the most interesting of these is illustrated upon the accompanying map1 which will need little description4 ,illustration3 ,fig4 #ed4--,map showing the effect of the glacial dam at ,cincinnati 7,claypole74 7,from ,transactions of the ,edinburgh ,geological ,society47 ,while tracing the boundary-line of the glaciated area in the ,mississippi ,valley during the summer of #ahhb1 ,i discovered the existence of unmistakable glacial deposits in ,boone ,county1 ,kentucky1 across the ,ohio ,river1 from ,cincinnati4,,ch2 ,these deposits were upon the height of land #eej feet above the ,ohio ,river1 or nearly #a1jjj feet above the sea1 which is about the height of the water-shed between the ,licking and ,kentucky ,rivers4 ,as the ,ohio ,river occupies a trough of erosion some hundreds of feet in depth1 and extending all the way from this point to the mountains of western ,pennsylvania1 it would follow that the ice which conveyed boulders across the ,ohio ,river at ,cincinnati1 and deposited them upon the highlands between the ,licking and ,kentucky ,rivers1 would so obstruct the channel of the ,ohio as to pond the water back1 and hold it up to the level of the lowest pass into the ,ohio ,river farther down4 ,direct evidences of obstruction by glacial ice appear also for a distance of fifty or sixty miles1 extending both ways1 from ,cincinnati4 ,footnote ,,ch3 ,the existence of portions of this evidence had previously been pointed out by ,mr4 ,robert ,b4 ,warder and ,dr4 ,george ,sutton 7see ,geological ,reports of ,indiana1 #ahgb and #ahgh74 ,the consequences connected with this state of things are of the most interesting character4 ,the bottom of the ,ohio ,river at ,cincinnati is #dcb feet above the sea-level4 ,a dam of #eej feet would raise the water in its rear to a height of #ihb feet above tide4 ,this would produce a long1 narrow lake1 of the width of the eroded trough of the ,ohio1 submerging the site of ,pittsburg to a depth of #bha feet1 and creating slack water up the ,monongahela nearly to ,grafton1 ,west ,virginia1 and up the ,alleghany as far as ,oil ,city4 ,all the tributaries of the ,ohio would likewise be filled to this level4 ,the length of this slack-water lake in the main valley1 to its termination up either the ,alleghany or the ,monongahela1 was not far from one thousand miles4 ,the conditions were also peculiar in this1 that all the northern tributaries rose within the southern margin of the ice-front1 which lay at varying distances to the north4 ,down these there must have poured during the summer months immense torrents of water to strand boulder-laden icebergs on the summits of such high hills as were lower than the level of the dam4 ,naturally enough1 this hypothesis of a glacial dam at ,cincinnati aroused considerable discussion1 and led to some differences of opinion4 ,professors ,i4 ,c4 ,white and ,j4 ,p4 ,lesley1 whose field work has made them perfectly familiar with the upper ,ohio and its tributaries1 at once supported the theory1 with a great number of facts concerning certain high-level terraces along the ,alleghany and ,monongahela ,rivers2 while additional facts of the same character have been brought to light by myself and others4 ,in general1 it may be said that in numerous places terraces occur at a height so closely corresponding to that of the supposed dam at ,cincinnati1 that they certainly strongly suggest direct dependence upon it4 ,the upward limit of these terraces in the ,monongahela ,river is #a1jfe feet1 and they are found in various places in situations which indicate that they were formed in still water of such long standing as would require an obstruction below of considerable permanence4 ,one of the most decisive cases adduced by ,professor ,white occurs near ,morgantown1 in ,west ,virginia1 of which he gives the following description3 ,owing to the considerable elevation--#bge feet--of the fifth terrace above the present river-bed in the vicinity of ,morgantown1 its deposits are frequently found far inland from the ,monongahela1 on tributary streams4 ,a very extensive deposit of this kind occurs on a tributary one mile and a half northeast of ,morgantown2 and the region1 which includes three or four square miles1 is significantly known as the ',flats4' ,the elevation of the ',flats' is #bge feet above the river1 or #a1jfe feet above tide4 ,the deposits on this area consist almost entirely of clays and fine1 sandy material1 there being very few boulders intermingled4 ,the depth of the deposit is unknown1 since a well sunk on the land of ,mr4 ,baker passed through alternate beds of clay1 fine sand1 and muddy trash1 to a depth of sixty-five feet without reaching bed-rock4 ,in some portions of the clays which make up this deposit1 the leaves of our common forest-trees are found most beautifully preserved4 ,at ,clarksburg1 where the river unites with ,elk ,creek1 there is a wide stretch of terrace deposits1 and the upper limit is there about #a1jej feet above tide1 or only #acj feet above low-water 7#ibj feet72 while at ,weston1 forty miles above 7by the river71 these deposits cease at seventy feet above low water1 which is there #ihe feet above tide4 ,it will thus be observed that the upper limit of the deposits retains a practical horizontality from ,morgantown to ,weston1 a distance of one hundred miles1 since the upper limit has the same elevation above tide 7#a1jde to #a1jfe feet7 at every locality4 ,these deposits consist of rounded boulders of sandstone1 with a large amount of clay1 quicksand1 and other detrital matter4 ,the country rock in this region consists of the soft shales and limestones of the upper coal-measures1 and hence there are many 'low gaps' from the head of one little stream to that of another1 especially along the immediate region of the river2 and in every case the summits of these divides1 where they do not exceed an elevation of #a1jej feet above tide1 are covered with transported or terrace material2 but where the summits go more than a few feet above that level we find no transported material upon them1 but simply the decomposed country rock4 ,other noteworthy terraces naturally attributable to the ,cincinnati ice-dam are to be found in the valley of the ,kanawha1 in ,west ,virginia1 and one of special significance on the pass between the valleys of the ,ohio and ,monongahela1 west of ,clarksburg1 ,west ,virginia4 ,according to ,professor ,white1 there is at this latter place a broad1 level summit1 having an elevation of #a1ajj feet1 in a gap about #cjj feet below the enclosing hills4 ,this gap1 or valley1 is covered by a deposit of fine clay4 ,the cut through it is about thirty feet1 and one can observe the succession of clays of all kinds and of different colours1 from yellow on the surface down to the finest white potter's clay at the level of the railway1 where the cut reaches bed-rock1 thus proving that the region has been submerged4,,ci ,footnote ,,ci3 ,bulletin of the ,geological ,society of ,america1 vol4 i1 p4 #dgh4 ,another crucial case ,i have myself described at ,bellevue1 in the angle of the ,ohio and ,alleghany ,rivers1 about five miles below ,pittsburg1 where the gravel terrace is nearly #cjj feet above the river1 making it about #a1jjj feet above the sea4 ,a significant circumstance connected with this terrace is that not only does its height correspond with that of the supposed obstruction at ,cincinnati1 but it contains many pebbles of ,canadian origin1 which could not have got into the valley of the ,alleghany before the ,glacial period1 and could only have reached their present position by being brought down the ,alleghany ,river upon floating ice1 or by the ordinary movement of gravel along the margin of a river4 ,thus this terrace1 while corresponding closely with the elevation of those on the ,monongahela ,river1 is directly connected with the ,glacial period1 and furnishes a twofold argument for our theory4 ,a still stronger case occurs at ,beech ,flats1 at the head of ,ohio ,brush ,creek1 in the northwest corner of ,pike ,county1 ,ohio1 where1 at an elevation of about #iej feet above the sea1 there is an extensive flat-topped terrace just in front of the terminal moraine4 ,this terrace consists of fine loam1 such as is derived from the glacial streams1 but which must have been deposited in still water4 ,the occurrence of still water at that elevation just in front of the continental ice-sheet is best accounted for by the supposed dam at ,cincinnati4 ,indeed1 it is extremely difficult to account for it in any other way4 ,there are1 however1 two other methods of attempting to account for the class of facts above cited in support of the ice-dam theory1 of which the most plausible is1 that in connection with the ,glacial period there was a subsidence of the whole region to an extent of #a1ajj feet4 ,the principal objection heretofore alleged against this supposition is that there are not corresponding signs of still-water action at the same level on the other side of the ,alleghany ,mountains4 ,this will certainly be fatal to the subsidence theory1 if it proves true4 ,but it is possible that sufficient search for such marks has not yet been made on the eastern side of the mountains4 ,the other theory to account for the facts is1 that the terraces adduced in proof of the ,cincinnati ice-dam were left by the streams in the slow process of lowering their beds from their former high levels4 ,this is the view advocated by ,president ,t4 ,c4 ,chamberlin4 ,but the freshness of the leaves and fragments of wood1 such as were noted by ,professor ,white at ,morgantown1 and the great extent of fine silt occasionally resting upon the summits of the water-sheds1 as described above1 near ,clarksburg1 bear strongly against it4 ,furthermore1 to account for the terrace described at ,bellevue1 which contains ,canadian pebbles1 ,president ,chamberlin is compelled to connect the deposit with his hypothetical first ,glacial epoch1 and to assume that all the erosion of the ,alleghany and ,monongahela ,rivers1 and indeed of the whole trough of the ,ohio ,river1 took place in the interval between the first and the second ,glacial periods 7for he would connect the glacial deposits upon the south side of the river at ,cincinnati with the first ,glacial epoch7--all of which1 it would seem1 is an unnecessary demand upon the forces of ,nature1 when the facts are so easily accounted for by the simple supposition of the dam at ,cincinnati4,,cj ,footnote ,,cj3 ,see matter discussed more at length in the lee ,age1 pp4 #cbf-cej1 #dhj-ejj2 ,bulletin of the ,united ,states ,geological ,survey1 ,no4 #eh1 pp4 #gf-ajj2 ,popular ,science ,monthly1 vol4 xlv1 pp4 #ahd-aii4 ,per contra1 ,mr4 ,frank ,leverett1 in ,american ,geologist1 vol4 x1 pp4 #ah-bd4 ,illustration3 ,fig4 #ee4--,map showing the condition of things when the ice-front had withdrawn about on hundred and twenty miles1 and while it still filled the valley of the ,mohawk4 ,the outlet was then through the ,wabash4 ,niagara was not yet born 7,claypole74 7,transactions of the ,edinburgh ,geological ,society47 ,we have already described,,ck the various temporary lakes and lines of drainage caused by the direct obstruction of the northward outlets to the basin of the ,great ,lakes4 ,in connection with the map1 it will be unnecessary to do anything more here than add a list of such temporary southern outlets from the ,erie-,ontario basin4,,cl ,the first is at ,fort ,wayne1 ,indiana1 through a valley connecting the ,maumee ,river basin with that of the ,wabash4 ,the channel here is well defined1 and the high-level gravel terraces down the ,wabash ,river are a marked characteristic of the valley4 ,the elevation of this col above the sea is #gdj feet4 ,similar temporary lines of drainage existed from the ,st4 ,mary's ,river to the ,great ,miami1 at an elevation of #idb feet2 from the ,sandusky ,river to the ,scioto1 through the ,tymochtee ,gap1 at an elevation of #iab feet2 from ,black ,river to the ,killbuck 7a tributary of the ,muskingum7 through the ,harrisville ,gap1 at #iaa feet2 from the ,cuyahoga into the ,tuscarawas ,valley1 through the ,akron ,gap1 at #iga feet2 from ,grand ,river into the ,mahoning1 through the ,orwell ,gap1 #ich feet2 from ,cattaraugus ,creek1 ,n4 ,y41 into the ,alleghany ,valley through the ,dayton ,gap1 about #a1cjj feet2 between ,conneaut ,creek and ,shenango ,river1 at ,summit ,station1 #a1ada feet2 from the ,genesee ,river1 ,n4 ,y41 into the head-waters of the ,canisteo1 a branch of the ,susquehanna1 at ,portageville1 #a1cad feet2 from ,seneca ,lake to ,chemung ,river1 at ,horseheads1 #hgi feet2 from ,cayuga ,lake to the valley of ,cayuga ,creek1 at ,spencer1 ,n4 ,y41 #a1jjj feet2 from ,utica1 ,n4 ,y41 into the ,chenango ,valley at ,hamilton1 about #ijj feet4 ,footnote ,,ck3 ,see pp4 #ib seq41 #aii seq4 ,footnote ,,cl3 ,see also accompanying map4 ,illustration3 ,fig4 #ef4--,map illustrating a stage in the recession of the ice in ,ohio4 ,for a section of the deposit in the bed of this lakelet1 see page #bjj4 ,the gravel deposits formed at this stage along the outlet into the ,tuscarawas ,river are very clearly marked 7,claypole74 7,transactions of the ,edinburgh ,geological ,society47 ,perhaps it would have been best to give this list in the reverse order1 which would be more nearly chronological1 since it is clear that the highest outlets are the oldest4 ,we should then have to mention1 after the ,fort ,wayne outlet1 two others at lower levels which are pretty certainly marked by distinct beach ridges upon the south side of ,lake ,erie4 ,the first was opened when the ice had melted back from the south peninsula of ,michigan to the water-shed across from the ,shiawassee and ,grand ,rivers1 uncovering a pass which is now #gbi feet above the sea4 ,this continued to be the outlet of ,lake ,erie-,ontario until the ice had further retreated beyond the ,strait of ,mackinac1 when the water would fall to the level of the old outlet from ,lake ,michigan into the ,illinois ,river1 which is a little less than #fjj feet1 where it would remain until the final opening of the ,mohawk ,river in ,new ,york attracted the water in that direction1 and lowered the level to that of the pass from ,lake ,ontario to the ,mohawk at ,rome4,,cm ,footnote ,,cm3 ,mr4 ,warren ,upham1 in the ,bulletin of the ,geological ,society of ,america1 vol4 ii1 p4 #bei4 ,a study of these lines of temporary drainage during the ,glacial period sheds much light upon the long lines of gravel ridges running parallel with the shores of ,lake ,erie and ,lake ,ontario4 ,south of ,lake ,erie a series of four ridges of different elevations can be traced4 ,in ,lorain ,county1 ,ohio1 the highest of these is #bbj feet above the lake2 the next #afj feet2 the next #aah feet2 and the lower one #ajj feet1 which would make them respectively #gie1 #gee1 #gae1 and #gjj feet above tide4 ,these gravel ridges are evidently old beach lines1 and indicate the different levels up to which the water was held by ice-obstructions across the various outlets of the drainage valley4 ,the material in the ridges is water-worn and well assorted1 and in coarseness ranges from fine sand up to pebbles several inches in diameter4 ,the predominant material in them is of local origin4 ,where the rocks over which they run are sandstone1 the material is chiefly sand1 and where the outcropping rock is shale1 the ridges consist chiefly of the harder nodules of that formation which have successfully resisted the attrition of the waves4 ,ordinarily these ridges are steepest upon the side facing the lake4 ,according to ,mr4 ,upham1 who has driven over them with me1 the ,lake ,erie ridges correspond1 both in general appearance and in all other important respects1 to those which he has so carefully surveyed around the shores of the ancient ,lake ,agassiz in ,minnesota and ,manitoba1 an account of which will be given a little farther on in this chapter4 ,illustration3 ,fig4 #eg4--,section of the lake ridges near ,sandusky1 ,ohio4 ,we are not permitted1 however1 to assume that there have been no changes of level since the deposition of these beaches surrounding the ancient glacial ,lake ,erie-,ontario4 ,on the contrary1 there appears to have been a considerable elevation towards the east and northeast in post-glacial times4 ,the highest ridge south of ,lake ,erie1 which at ,fort ,wayne is about #ghj feet high1 is now about #gie feet in ,lorain ,county4 ,the second of the ridges above-mentioned1 which is about #gdj feet above tide at ,cleveland1 ,ohio1 rises to #hgj feet where the last traces of it have been discovered at ,hamburg1 ,n4 ,y4 ,the third ridge1 which is #fgc feet at ,cleveland1 has risen to the height of #hfj feet at ,crittenden1 about one hundred miles to the east of ,buffalo1 ,n4 ,y4 ,a similar eastern increase of elevation is discoverable in the main ridge surrounding ,lake ,ontario4 ,what ,professor ,spencer calls the ,iroquois beach1 which is #cfc feet above tide at ,hamilton1 ,ontario1 has risen to a height of #dhd feet near ,syracuse1 ,n4 ,y42 while farther to the northeast1 in the vicinity of ,watertown1 it is upwards of #hjj feet above tide4 ,there is also a similar northward increase of elevation in the beaches surrounding the higher lands of ,ontario eastward of ,lake ,huron and ,georgian ,bay4 ,all this indicates that at the close of the ,glacial period there was a subsidence of several hundred feet in the area of greatest ice-accumulation lying to the east and north of the ,great ,lake region4 ,the formation of these ridges occurred during that period of subsidence4 ,the re-elevation which followed the disappearance of the ice of course carried with it these ridges1 and brought them to their present position4,,cn ,footnote ,,cn3 ,see ,spencer1 in ,bulletin of the ,geological ,society of ,america1 vol4 ii1 pp4 #dfe-dgf4 ,in returning to consider more particularly the remarkable gorge joining the ,minnesota with the ,red ,river of the ,north1 we are brought to the largest of the glacial lakes of this class1 and to the typical place in ,america in which to study the temporary changes of drainage produced by the ice itself daring the periods both of its advance and of its retreat4 ,illustration3 ,fig4 #eh4--,map showing the stages of recession of the ice in ,minnesota as described in the text 7,upham74 ,by turning to our general map of the glaciated region of the ,united ,states1,,co one can readily see the relation of the valley between ,lake ,traverse and ,big ,stone ,lake to an area marked as the bed of what is called ,lake ,agassiz4 ,during the ,glacial period ,brown's ,valley1 the depression joining these two lakes1 was the outlet of an immense body of water to the north1 whose natural drainage was towards ,hudson ,bay or the ,arctic ,ocean1 but which was cut off1 by the advancing ice1 from access to the ocean-level in that direction1 and was compelled to seek an exit to the south4 ,footnote ,,co3 ,see page #ff4 ,thus for a long period the present ,minnesota ,river ,valley was occupied by a stream of enormous dimensions1 and this accounts for the great size of the trough--the present ,minnesota being but an insignificant stream winding about in this deserted channel of the old ,father of ,waters1 and having as much room as a child of tender age would have in his parent's cast-off garments4 ,this glacial stream has been fittingly named ,river ,warren1 after ,general ,warren1 who first suggested and proved its existence1 and so we have designated it on the accompanying map of ,minnesota4 ,lake ,traverse is fifteen miles long1 and the water is nowhere more than twenty feet deep4 ,big ,stone ,lake is twenty-six miles long1 and of about the same depth4 ,brown's ,valley1 which connects the two1 is five miles long1 and the lakes are so nearly on a level that during floods the water from ,lake ,traverse sometimes overflows and runs to the south as well as to the north4 ,illustration3 ,fig4 #ei4--;,glacial terrace near the boundary of the glaciated area1 on ,raccoon ,creek1 a tributary of the ,licking ,river1 in ,granville1 ,licking ,county1 ,ohio4 ,height about fifty feet4 ,the trough occupied by these lakes and valley is from one mile to one mile and a half in width and about #abj feet in depth4 ,if we had been permitted to stand upon the bluffs overlooking it during the latter part of the ,glacial period1 we should have seen the whole drainage of the north passing by our feet on its way to the ,gulf of ,mexico4 ,as lie follows down the valley of the ,minnesota ,river1 the observant traveller1 even now1 cannot fail to see in the numerous well-preserved gravel terraces the high-water marks of that stream when flooded with the joint product of the annual precipitation over the vast area to the north1 and of the still more enormous quantities set free by the melting of the western part of the great ,laurentide ,glacier4 ,numerous other deserted water-ways in the northwestern part of the valley of the ,mississippi have been brought to light in the more recent geological surveys1 both in the ,united ,states and in ,canada4 ,during a considerable portion of the ,glacial period the ,saskatchewan1 the ,assiniboine1 the ,pembina1 and the ,cheyenne ,rivers1 whose present drainage is into the ,red ,river of the ,north1 were all turned to the south1 and their temporary channels can be distinctly traced by deserted water-courses marked by lines of gravel deposits4,,cp ,footnote ,,cp3 ,for further particulars1 see ,ice ,age1 pp4 #bic et seq4 ,in ,dakota1 ,professor ,j4 ,e4 ,todd has discovered large deserted channels on the southwestern border of the glaciated region near the ,missouri ,river1 where evidently streams must have flowed for a long distance in ice-channels when the ice still continued to occupy the valley of the ,james ,river4 ,from these channels of ice in which the water was held up to the level of the ,missouri ,coteau the water debouched directly into channels with sides and bottom of earthy material1 which still show every mark of their former occupation by great streams4,,cq ,footnote ,,cq3 ,for particulars1 see ,ice ,age1 p4 #bib4 ,in ,minnesota1 also1 there is abundant evidence that while the northeastern part of the valley from ,mankato to ,st4 ,paul was occupied by ice1 the drainage was temporarily turned directly southward across the country through ,union ,slough and ,blue ,earth ,river into the head-waters of the ,des ,moines ,river in ,iowa4 ,ancient ,river ,terraces4 ,the interest of the whole inquiry respecting the relation of man to the ,glacial period in ,america concentrates upon these temporary lines of southern drainage4 ,wherever they existed1 the swollen floods of the ,glacial period have left their permanent marks in the deposition of extensive gravel terraces4 ,the material thus distributed is derived largely from the glacial deposits through which they run and out of which they emerge4 ,while the height of the terraces depended upon various conditions which must be studied in detail1 in general it may be said that it corresponds pretty closely with the extent of the area whose drainage was turned through the channel during the prevalence of the ice4 ,the height of the terraces and the coarseness of the material seem also to have been somewhat dependent upon the proximity of their valleys to the areas of most vigorous ice-action1 and this1 in turn1 seems to lie in the rear of the moraines which ,president ,chamberlin has attributed to the second ,glacial epoch4 ,southward from this belt of moraines the terraces uniformly and gradually diminish both in height and in the coarseness of their gravel1 until they finally disappear in the present flood-plain of the ,mississippi ,river4 ,illustration3 ,fig4 #fj4--;,ideal section across a river-bed in drift region3 b b b1 old river-bed2 ,r1 the present river2 t t1 upper or older terraces2 t' t'1 lower terraces4 ,an interesting illustration of this principle is to be observed in the continuous valley of the ,alleghany and ,ohio ,rivers4 ,the trough of this valley was reached by the continental glacier at only a few points1 the ice barely touching it at ,salamanca1 ,n4 ,y41 ,franklin1 ,pa41 and ,cincinnati1 ,ohio4 ,but throughout its whole length the ice-front was approximately parallel to the valley1 and occupied the head-waters of nearly all its tributaries4 ,now1 wherever tributaries which could be fed by glacial floods1 enter the trough of the main stream1 they brought down an excessive amount of gravel1 and greatly increased the size of the terrace in the trough itself1 and from the mouth of each such tributary to that of the next one below there is a gradual decrease in the height of the terrace and in the coarseness of the material4 ,this law is illustrated with special clearness in ,pennsylvania between ,franklin and ,beaver4 ,franklin is upon the ,alleghany ,river1 at the last point where it was reached directly by the ice4 ,below this point no tributary reaches it from the glaciated region1 and none such reaches the ,ohio after its junction with the ,alleghany until we come to the mouth of ,beaver ,creek1 about twenty-five miles below ,pittsburg4 ,but at this point the ,ohio is joined by a line of drainage which emerges from the glaciated area only ten or twelve miles to the north1 and whose branches occupy an exceptionally large glaciated area4 ,accordingly1 there is at ,beaver a remarkable increase in the size of the glacial terrace on the ,ohio4 ,in the angle down-stream between the ,beaver and the ,ohio there is an enormous accumulation of granitic pebbles1 many of them almost large enough to be called boulders1 forming the delta terrace1 upon which the city is built and rising to a height of #ace feet above the low-water mark in the ,ohio4 ,in striking confirmation of our theory1 also1 the terrace in the ,ohio ,valley upon the upper side of ,beaver ,creek is composed of fine material1 largely derived from local rocks and containing but few granitic pebbles4 ,from the mouth of ,beaver ,creek1 down the ,ohio1 the terrace is constant 7sometimes upon one side of the river and sometimes upon the other71 but1 according to rule1 the material of which it is composed gradually grows finer1 and the elevation of the terrace decreases4 ,according to rule1 also1 there is a notable increase in the height of the terrace below each affluent which enters the river from the glaciated region4 ,this is specially noticeable below ,marietta1 at the mouth of the ,muskingum1 whose head-waters drain an extensive portion of the glaciated area4 ,from the mouth of the ,little ,beaver to this point the tributaries of the ,ohio are all small1 and none of them rise within the glacial limit4 ,hence they could contribute nothing of the granitic material which enters so largely into the formation of the river terrace2 but below the mouth of the ,muskingum the terrace suddenly ascends to a height of nearly one hundred feet above low-water mark4 ,again1 at the mouth of the ,scioto at ,portsmouth1 there is a marked increase in the size of the terrace1 which is readily accounted for by the floods which came down the ,scioto ,valley from the glaciated region4 ,the next marked increase is at ,cincinnati1 just below the mouth of the ,little ,miami1 whose whole course lay in the glaciated region1 and whose margin is lined by very pronounced terraces4 ,at ,cincinnati the upper terrace upon which the city is built is #abj feet above the flood-plain4 ,twenty-five miles farther down the river1 near ,lawrenceburg1 these glacial terraces are even more extensive1 the valley being there between three and four miles wide1 and being nearly filled with gravel deposits to a height of #aab feet above the flood-plain4 ,below this point the terraces gradually diminish in height1 and the material becomes finer and more water-worn1 until it merges at last in the flood-plain of the ,mississippi4 ,the course of the ,wabash ,river is too long to permit it to add materially to the size of the terraces which characterise the broader valley of the ,ohio below the ,illinois line4 ,it is in terraces such as these just described that we find the imbedded relics of man which definitely connect him with the great ,ice age4 ,these have now been found in the glacial terraces of the ,delaware ,river at ,trenton1 ,n4 ,j42 in similar terraces in the valley of the ,tuscarawas ,river at ,new ,comerstown1 and in the valley of the ,little ,miami at ,loveland and ,madisonville1 in ,ohio2 on the ,east ,fork of ,white ,river1 at ,medora1 ,ind42 and still1 again1 at ,little ,falls1 in the trough of the ,mississippi1 some distance above ,minneapolis1 ,minn4 ,i append a list of the points at which various streams from the ,atlantic ,ocean to the ,mississippi ,river emerge from the glacial boundary1 and below which the terraces are specially prominent4 ,of course1 with the retreat of the ice1 the formation of the terraces continued northward in the glaciated area to a greater or less distance1 according to the extent of the valley or to the length of time during which the drainage was temporarily turned into it4 ,these points of emergence are3 ,in the ,delaware ,valley1 at ,belvidere1 ,n4 ,j42 in the ,susquehanna1 at ,beach ,haven1 ,pa42 in the ,conewango1 at ,ackley1 ,warren ,county2 in ,oil ,creek1 above ,titusville3 in ,french ,creek1 a little above ,franklin2 in ,beaver ,creek1 at ,chewtown1 ,lawrence ,county2 on the ,middle ,fork of ,little ,beaver1 near ,new ,lisbon1 ,ohio2 on the east branch of ,sandy ,creek1 at ,east ,rochester1 ,columbiana ,county2 on the ,nimishillin1 at ,canton1 ,stark ,county2 on the ,tuscarawas1 at ,bolivar2 on ,sugar ,creek1 at ,beech ,city2 on the ,killbuck1 at ,millersburg1 ,holmes ,county2 on the ,mohican1 near the northeast corner of ,knox ,county2 on the ,licking ,river1 at ,newark2 on ,jonathan ,creek1 ,perry ,county2 on the ,hocking1 at ,lancaster2 on the ,scioto1 at ,hopetown1 just above ,chillicothe2 on ,paint ,creek1 and its various tributaries1 between ,chillicothe and ,bainbridge2 and on the ,wabash1 above ,new ,harmony1 ,ind42 to which may be added the ,ohio ,river itself1 at its junction with the ,miami1 near ,lawrenceburg4 ,another class of terraces having most interesting connection with the ,glacial period is found in the arid basins west of the ,rocky ,mountains4 ,over wide areas in ,utah and ,nevada the evaporation now just balances the precipitation1 and all the streams disappear in shallow bodies of salt water of moderate dimensions1 of which ,great ,salt ,lake in ,utah1 and ,mono1 ,pyramid1 and ,north ,carson ,lakes in ,nevada1 are the most familiar examples4 ,these occupy the lowest sinks of enclosed basins of great depth4 ,but there is abundant evidence that in consequence of the increased precipitation and diminished evaporation of the ,glacial period one of these basins was filled to the brim and the other to a depth of several hundred feet4 ,these former enlargements have been named after the first explorers of the region1 ,captains ,lahontan and ,bonneville1 and are shown on the accompanying sketch map by the shading surrounding the existing lakes4 ,lake ,lahontan has been carefully studied by ,mr4 ,i4 ,c4 ,russell1 and has been found to extend from the boundary of ,oregon to latitude #ch #cj' south1 a distance of two hundred and sixty miles4 ,the ,central ,pacific ,railroad runs through its dried-up bed from ,golconda to ,wadsworth1 a distance of one hundred and sixty-five miles4 ,the terraces of the former lake are distinctly traceable at a height of #gjj feet above the present level of ,lake ,mono4 ,lake ,bonneville1 whose present representative is ,great ,salt ,lake1 is the subject of a recent monograph by ,mr4 ,g4 ,k4 ,gilbert1 from which it appears that this ancient body of water occupied #ai1gej square miles--an area about ten times that of the present lake4 ,at the time of its maximum extension its depth was #a1jjj feet1 while ,great ,salt ,lake ranges only from fifteen to fifty feet in depth4 ,the pass through which the discharge finally took place is at ,red ,rock1 on the ,utah and ,northern ,railroad1 at the head of ,cache ,valley on the south and the lower part of ,marsh ,creek ,valley on the north4 ,during the long period preceding and accompanying the gradual rise of water in the ,utah basin to the level of the highest terrace1 ,marsh ,creek 7the upper portion of which comes from the mountains on the east and turns at right angles7 had been at work depositing a delta of loose material in the col which separates the two valleys4 ,this deposit rested upon a stratum of limestone at the bottom of the pass1 and covered it with sand1 clay1 and gravel to a depth of #cge feet4 ,thus1 when the water was approaching its upper level1 the only barrier to prevent its escape was this unstable accumulation of loose material upon top of the rock4 ,it would have required1 therefore1 no prophet's eye to predict that the way was preparing for a tremendous dbcle4 ,illustration3 ,fig4 #fa4--,map of the ,quaternary ,lakes4 ,bonneville and ,lahontan 7after ,gilbert and ,russell74 ,the critical point at length was reached4 ,after remaining nearly at the elevation of the pass for a considerable period1 during which the #a1jjj-;foot shore-line was formed1 the crisis came when the water began to flow northward towards ,snake ,river4 ,once begun in such loose material1 the channel rapidly enlarged until soon a stream equal to ,niagara1 and at times probably much larger1 was pouring northward through the valley heretofore occupied by the insignificant rivulets of ,marsh ,creek and the ,port ,neuf4 ,it is impossible to tell how rapidly the loose barrier wore away1 but there is abundant evidence in the valley below that not only the present channel of the lower part of ,marsh ,creek1 but the whole bottom of the valley for a mile or more in width1 was for a considerable time covered by a rapid stream from ten to twenty feet in depth1 and descending at the rate of thirteen feet to the mile4 ,the continuance of this flood was dependent upon the amount of water to be discharged1 which1 as we have seen1 was that contained in an area of #bj1jjj square miles1 with a depth of #cge feet4 ,a stream of the size of ,niagara would occupy about twenty-five years in the discharge of such a mass1 and this may fairly be taken as a measure of the time through which it lasted4 ,when the loose material lying above the strata of limestone in ,red ,rock ,pass had been washed away1 the lake then continued at that level for an indefinite period1 with an overflow regulated by the annual precipitation of the drainage basin4 ,this stage of the lake1 during which it occupied #ac1jjj square miles and was #fbe feet above its present level1 is also marked by an extensive and persistent shore-line all around the basin4 ,but1 finally1 the balance again turned when the evaporation exceeded the precipitation1 and the vast body of water has since dwindled to its present insignificant dimensions4 ,my own interest in this discovery of ,mr4 ,gilbert is enhanced by the explanation it gives of a phenomenon in the ,snake ,river ,valley which ,i was unable to solve when on the ground in #ahij4 ,the present railroad town of ,pocatello is situated just where this flood emerged from the narrower valley of ,marsh ,creek and the ,port ,neuf1 and spread itself out upon the broad plain of the ,snake ,river basin4 ,the southern edge of the plain upon which the city is built is a vast boulder-bed covered with a thin stratum of sand and gravel4 ,everywhere1 in sinking wells and digging ditches on the vacant lots and in the streets of the city1 water-worn boulders of a great variety of material and sometimes three or four feet in diameter are encountered4 ,i was debarred from regarding this as a terminal moraine1 both by the water-worn character of the boulders and by the absence of any sign of ice-action in the surrounding mountains1 and ,i was equally debarred from attributing it to any ordinary stream of water1 both by the size of the boulders and the fact that for a mile or more up the ,port ,neuf ,valley there is an intervale1 forty or fifty feet below the surface at ,pocatello1 and occupying the whole width of the valley1 in which there is only gravel and fine sand1 through which the present ,port ,neuf pursues a meandering course4 ,the upper end of this short intervale is bounded by the terminus of a basaltic stream which had flowed down the valley and filled it to a considerable depth1 but had subsequently been much eroded by violent water-action4 ,in the light of ,mr4 ,gilbert's discoveries1 however1 everything is clear4 ,the tremendous dbcle which he has brought within the range of scientific vision would naturally produce just the condition of things which is so puzzling at ,pocatello4 ,coming down through the restricted channel with sufficient force to roll along boulders of great size and to clear them all out from the upper portion of the valley1 the torrent would naturally deposit them where the current was first checked1 a mile below the lava cliffs4 ,the plunge of the water over these cliffs would keep a short space below clear from boulders1 and the more moderate stream of subsequent times would fill in the depression with the sand and gravel now occupying it4 ,what other effects of this remarkable outburst may be traced farther down in the ,snake ,river ,valley ,i cannot say1 but it will be surprising if they do not come to light and help to solve some of the many geological problems yet awaiting us in this interesting region4 ,it should have been said that during the formation of the #fbe-;foot1 or so-called ,provo shore-line1 glaciers descended from the caons on the west flank of the ,wahsatch ,mountains1 and left terminal moraines to mark the coincidence of the ,glacial period with that stage of the enlargement of the lake4 ,evidences of a similar coincidence are to be found on the high-level terraces surrounding ,lake ,mono1 to which glaciers formerly descended from the western flanks of the ,sierra ,nevada4 ,the ancient shore-lines surrounding ,lakes ,bonneville and ,lahontan bear evidence also of various other episodes in the ,glacial period4 ,evidently there were two periods of marked increase in the size of the lakes1 with an arid period intervening4 ,during the first rise the level of ,bonneville attained to within ninety feet of the second1 and numerous beaches were formed1 and a large amount of yellow clay deposited4 ,then it seems to have been wholly evaporated1 while its soluble mineral matter was precipitated1 and so mingled with silt that it did not readily redissolve during the second great rise of water4 ,partly on this account1 and partly through the influence of the outlet into the ,snake ,river1 the lake was nearly fresh during its second enlargement4 ,european ,facts4 ,in ,chapter ,,vi it came in place to mention many of the facts connected with the influence of the ,glacial period upon the drainage systems of ,europe4 ,we there discussed briefly the probable influence of the ice-obstructions that extended across the mouths of the ,dwina1 the ,vistula1 the ,oder1 the ,elbe1 the ,weser1 and the ,rhine4 ,the drainage of the obstructed rivers in ,russia was perhaps turned southward into the ,caspian and ,black ,seas1 and then assisted in forming the fertile soil of the plains in the southern part of that empire4 ,the obstructed drainage of the ,german rivers was probably turned westward in front of the ice through the ,straits of ,dover or across the southern part of ,england4 ,this was during the climax of the ,glacial period2 but later1 according to ,dawkins1 during a period in which the land of the ,british ,isles stood about #fjj feet above its present level1 the streams of the eastern coast--namely1 the ,thames1 ,medway1 ,humber1 ,tyne1 and others1 joined the ,rhine1 the ,weser1 and the ,elbe1 to form a river flowing through the valley of the ocean4 ,in like manner1 the rivers of the south of ,england and of the north of ,france formed a great river flowing past the ,channel ,islands due west into the ,atlantic1 and the ,severn united with the rivers of the south of ,ireland2 while those to the east of ,ireland joined the ,dee1 ,mersey ,ribble1 and ,lune1 as well as those of western ,scotland1 ultimately reaching the ,atlantic to the west of the ,hebrides4 ,the water-shed between the valleys of the ,british ,channel and the ,north ,sea is represented by a ridge passing due south from ,folkestone to ,dieppe1 and that between the drainage area and the ,severn and its tributaries on the one hand1 and of the ,irish ,channel on the other1 by a ridge from ,holyhead westward to ,dublin4 ,this tract of low1 undulating land which surrounded ,britain and ,ireland on every side consisted not merely of rich hill1 valley1 and plain1 but also of marsh-land studded with lakes1 like the meres of ,norfolk1 now indicated by the deeper soundings4 ,these lakes were very numerous to the south of the ,isle of ,wight and off the coast of ,norfolk and ,suffolk4,,cr ,footnote ,,cr3 ,early ,man in ,britain1 p4 #aea4 ,the evidence first regarded by scientific men to be demonstrative of the formation of extensive lakes during the ,glacial period by the direct influence of ice-dams exists in the ,parallel ,roads of ,glen ,roy in ,scotland4 ,illustration3 ,fig4 #fb4--,parallel roads of ,glen ,roy4 ,according to the description of ,sir ,charles ,lyell1 ,glen ,roy is situated in the western ,highlands1 about ten miles north of ,fort ,william1 near the western end of the great glen of ,scotland1 or ,caledonian ,canal1 and near the foot of the highest of the ,grampians1 ,ben ,nevis4 ,throughout nearly its whole length1 a distance of more than ten miles1 three parallel roads or shelves are traced along the steep sides of the mountains1 each maintaining a perfect horizontality1 and continuing at exactly the same level on the opposite sides of the glen4 ,seen at a distance they appear like ledges1 or roads1 cut artificially out of the sides of the hills2 but when we are upon them1 we can scarcely recognize their existence1 so uneven is their surface and so covered with boulders4 ,they are from ten to sixty feet broad1 and merely differ from the side of the mountain by being somewhat less steep4 ,on closer inspection1 we find that these terraces are stratified in the ordinary manner of alluvial or littoral deposits1 as may be seen at those points where ravines have been excavated by torrents4 ,the parallel shelves1 therefore1 have not been caused by denudation1 but by the deposition of detritus1 precisely similar to that which is dispersed in smaller quantities over the declivities of the hills above4 ,these hills consist of clay-slate1 mica-schist1 and granite1 which rocks have been worn away and laid bare at a few points immediately above the parallel roads4 ,the lowest of these roads is about #hej feet above the level of the sea1 and the next about #bab feet higher1 and the third #hb feet above the second4 ,there is a fourth shelf1 which occurs only in a contiguous valley called ,glen ,gluoy1 which is twelve feet above the highest of all the ,glen ,roy roads1 and consequently about #a1aef feet above the level of the sea4 ,one only1 the lowest of the three roads of ,glen ,roy1 is continued through ,glen ,spean1 a large valley with which ,glen ,roy unites4 ,as the shelves1 having no slope towards the sea like ordinary river terraces1 are always at the same absolute height1 they become continually more elevated above the river in proportion as we descend each valley2 and they at length terminate very abruptly1 without any obvious cause1 or any change either in the shape of the ground or in the composition or hardness of the rocks4,,cs ,footnote ,,cs3 ,antiquity of ,man1 pp4 #beb1 #bec4 ,early in his career ,charles ,darwin studied these ancient beaches1 and ascribed them to the action of the sea during a period of continental subsidence4 ,in this view he was supported by the majority of geologists until the region was visited by ,agassiz1 who saw at once the true explanation4 ,if these were really sea-beaches1 similar deposits should be found at the same elevation on other mountains than those surrounding ,glen ,roy4 ,their absence elsewhere points1 therefore1 to some local cause1 which was readily suggested to the trained eye of one like ,agassiz1 then fresh from the study of ,alpine glaciers1 who saw that these beaches were formed upon the margin of temporary lakes1 held back during the ,glacial period 7as the ,merjelen ,see now is7 by a glacier which came out of one glen and projected itself directly across the course of another1 and thus obstructed its drainage4 ,the glacier of ,glen ,spean had pushed itself across ,glen ,roy1 as the great ,aletsch ,glacier in ,switzerland now pushes itself across the little valley behind the ,eggishorn4 ,,chapter ,,viii4 ,,relics ,,of ,,man ,,in ,,the ,,glacial ,,period4 ,in ,glacial ,terraces of the ,united ,states4 ,although the first clear evidence of glacial man was discovered in ,europe1 the problem is so much simpler on the ,western ,continent that we shall find it profitable to study the ,american facts first4 ,we will therefore present a summary of them at once1 and then proceed to the more obscure problems of ,european archology4 ,the first definite discovery of human relics clearly connected with1 glacial deposits in ,america1 and of the same age with them1 was made by ,dr4 ,c4 ,c4 ,abbott1 at ,trenton1 ,n4 ,j41 in the year #ahge4 ,the city of ,trenton is built upon a delta terrace about three miles wide which occurs at the head of tide-water on the ,delaware ,river4 ,this terrace bears every mark of having been deposited by a torrential stream which came down the valley during the closing period of the great ,ice age4 ,the material of which the terrace consists is all water-worn4 ,according to the description of ,professor ,n4 ,s4 ,shaler3 ,illustration3 ,fig4 #fc4--,the glaciated portion is shaded4 ,the shading on the ,lehigh and ,delaware ,rivers indicates glacial terraces1 which are absent from the ,schuylkill4 ,the general structure of the mass is neither that of ordinary boulder-clay nor of stratified gravels1 such as are formed by the complete rearrangement by water of the elements of simple drift-deposits4 ,it is made up of boulders1 pebbles1 and sand1 varying in size from masses containing one hundred cubic feet or more to the finest sand of the ordinary sea-beaches4 ,there is little trace of true clay in the deposit2 there is rarely enough to give the least trace of cementation to the masses4 ,the various elements are rather confusedly arranged2 the large boulders not being grouped on any particular level1 and their major axes not always distinctly coinciding with the horizon4 ,all the pebbles and boulders1 so far as observed1 are smooth and water-worn1 a careful search having failed to show evidence of distinct glacial scratching or polishing on their surfaces4 ,the type of pebble is the subovate or discoidal1 and though many depart from this form1 yet nearly all observed by me had been worn so as to show that their shape had been determined by running water4 ,the materials comprising the deposit are very varied1 but all ,i observed could apparently with reason be supposed to have come from the extensive valley of the river near which they lie1 except perhaps the fragments of some rather rare hypogene rocks4 ,illustration3 ,fig4 #fd4--,palolith found by ,abbott in ,new ,jersey1 slightly reduced4 ,a conclusive proof of the relation of this ,trenton delta terrace to the ,glacial period is found in the fact that the gravel deposit is continuous with terraces extending up the trough of the valley of the ,delaware to the glaciated area and beyond4 ,as1 however1 the descent of the river-bed is rapid 7about four feet to the mile7 from the glacial border down to tide-water1 the terrace is not remarkably high1 being only about fifteen or twenty feet above the present flood-plain4 ,but it is continuous1 and similar in composition with the great enlargement in the delta at ,trenton4 ,without doubt1 therefore1 the deposit represents the overwash gravel of the ,glacial period4 ,fortunately for science1 ,dr4 ,c4 ,c4 ,abbott1 whose tastes for archological investigations were early developed1 had his residence upon the border of this glacial delta terrace at ,trenton1 and as early as #ahge began to find rough-stone implements of a peculiar type in the talus of the bank where the river was undermining the terrace4 ,in turning his attention to the numerous fresh exposures of gravel made by railroad and other excavations during the following year1 he found several of the implements in undisturbed strata1 some of which were sixteen feet below the surface4 ,since that time he has continued to make discoveries at various intervals4 ,in #ahhh he had found four hundred implements of the palolithic type at ,trenton1 sixty of which had been taken from recorded depths in the gravel1 two hundred and fifty from the talus at the bluff facing the river1 and the remainder from the surface1 or derived from collectors who did not record the positions or circumstances under which they were found4 ,illustration3 ,fig4 #fe4--,section across the ,delaware ,river at ,trenton4 ,new ,jersey3 a1 a1 ,philadelphia red gravel and brick-clay 7,mc,gee's ,columbia deposit72 b4 b1 ,trenton gravel1 in which the implements are found3 c1 present flood-plain of the ,delaware ,river 7after ,lewis74 7,from ,abbott's ,primitive ,industry47 ,the material from which the implements at ,trenton are made is argillite--that is1 a clay slate which has been so metamorphosed as to be susceptible of fracture1 almost like flint4 ,it is1 however1 by no means capable of being worked into such delicate forms as flint is4 ,but as it is the only material in the vicinity capable of being chipped1 prehistoric men of that vicinity were compelled to make a virtue of necessity and use the inferior material4 ,of all the implements found by ,dr4 ,abbott in the gravel1 only one was flint2 while upon the surface innumerable arrow-heads of flint have been found4 ,the transition1 also1 in the type of implements is as sudden as that in the kind of material of which they are made4 ,below the superficial deposit of black soil1 extending down to the depth of about one foot1 the modern ,indian flint implements entirely disappear1 and implements of palolithic type only are found4 ,illustration3 ,fig4 #ff4--,section of the ,trenton gravel in which the implements described in the text are found4 ,the shelf on which the man stands is made in process of excavation4 ,the gravel is the same above and below 7photograph by ,abbott74 ,illustration3 ,fig4 #fg4--;,face view of argillite implement1 found by ,dr4 ,c4 ,c4 ,abbott1 in #ahgf1 at ,trenton1 ,new ,jersey1 in gravel1 three feet from face of bluff1 and twenty-two feet from the surface 7,no4 #aj1ihe7 7,putnam74 ,in the year #ahhb1 after ,i had traced the glacial boundary westward from the ,delaware ,river1 across the ,states of ,pennsylvania1 ,ohio1 and ,indiana1 ,i was struck with the similarity between the terrace at ,trenton and numerous terraces which ,i had attributed to the ,glacial age in ,ohio and the other ,states4 ,it adds much to the interest of subsequent discoveries to note that in #ahhd1 in my report to the ,western ,reserve ,historical ,society upon the glacial boundary of ,ohio1 ,i wrote as follows3 ,illustration3 ,fig4 #fh4--;,argillite implement found by ,dr4 ,c4 ,c ,abbott1 ,march1 #ahgi1 at ,a4 ,k4 ,rowan's farm1 ,trenton1 ,new ,jersey1 in gravel sixteen feet from surface3 a1 face view2 b1 side view 7,no4 #aa1bhf7 7,putnam74 ,the gravel in which they ,dr4 ,abbott's implements are found is glacial gravel deposited upon the banks of the ,delaware when1 during the last stages of the ,glacial period1 the river was swollen with vast floods of water from the melting ice4 ,man was on this continent at that period when the climate and ice of ,greenland extended to the mouth of ,new ,york ,harbor4 ,the probability is1 that if he was in ,new ,jersey at that time1 he was also upon the banks of the ,ohio1 and the extensive terrace and gravel deposits in the southern part of our ,state should be closely scanned by archologists4 ,when observers become familiar with the rude form of these palolithic implements1 they will doubtless find them in abundance4 ,but whether we find them or not in this ,state ,ohio1 if you admit1 as ,i am compelled to do1 the genuineness of those found by ,dr4 ,abbott1 our investigation into the glacial phenomena of ,ohio must have an important archological significance1 for they bear upon the question of the chronology of the ,glacial period1 and so upon that of man's appearance in ,new ,jersey4 ,illustration3 ,fig4 #fi4--;,chipped pebble of black chert1 found by ,dr4 ,c4 ,l4 ,metz4 ,october1 #ahhe1 at ,madisonville1 ,ohio1 in gravel eight feet from surface under clay3 a1 face view2 b1 side view4 ,the expectation of finding evidence of preglacial man in ,ohio was justified soon after this 7in #ahhe71 when ,dr4 ,c ,l4 ,metz1 while co-co-operating with ,professor ,f4 ,w4 ,putnam1 of the ,peabody ,museum1 ,cambridge1 ,mass41 in field work1 discovered a flint implement of palolithic type in undisturbed strata of the glacial terrace of the ,little ,miami ,river1 near his residence at ,madisonville1 ,ohio4 ,in #ahhg ,dr4 ,metz found another implement in the terrace of the same river1 at ,loveland1 about twenty-five miles farther up the stream4 ,the implement at ,madisonville occurred eight feet below the surface1 and about a mile back from the edge of the terrace2 while that at ,loveland was found in a coarser deposit1 about a quarter of a mile back from the present stream1 and thirty feet below the surface4 ,mastodon-bones also were discovered in close proximity to the implement at ,loveland4 ,illustration3 ,fig4 #gj4 ,interest in these investigations was still further increased by the report of ,mr4 ,hilborne ,t4 ,cresson1 of ,philadelphia1 that in #ahhf1 with my map of the glaciated region in hand1 he had found an implement of palolithic type in undisturbed strata of the glacial terrace bordering the ,east ,branch of ,white ,river1 near the glacial boundary at ,medora1 ,jackson ,county1 ,ind4 ,the terrace was about fifty feet above the flood-plain of the river4 ,later still1 in ,october1 #ahhi1 ,mr4 ,w4 ,c4 ,mills1 of ,newcomerstown1 ,tuscarawas ,county1 ,ohio1 found in that town a finely shaped flint implement sixteen feet below the surface of the terrace of glacial gravel which lines the margin of the ,tuscarawas ,valley4,,ct ,mr4 ,mills was not aware of the importance of this discovery until meeting with me some months later1 when he described the situation to me1 and soon after sent the implement for examination4 ,in company with ,judge ,c4 ,c4 ,baldwin1 ,president of the ,western ,reserve ,historical ,society1 and several others1 a visit was made to ,mr4 ,mills1 and we carefully examined the gravel-pit in which the implement occurred1 and collected evidence which was abundant to corroborate all his statements4 ,the implement in question is made from a peculiar flint which is found in the ,lower ,mercer limestone1 of which there are outcrops a few miles distant1 and it resembles in so many ways the typical implements found by ,boucher de ,perthes1 at ,abbeville1 that1 except for the difference in the material from which it is made1 it would be impossible to distinguish it from them4 ,the similarity of pattern is too minute to have originated except from imitation4 ,footnote ,,ct3 ,for typical section of a glacial terrace in ,ohio1 see p4 #bbg4 ,illustration3 ,fig4 #ga4--,the smaller is the palolith from ,newcomerstown1 the larger from ,amiens 7face view71 reduced one half in diameter4 ,in #ahgg1 a year after the discoveries by ,dr4 ,abbott in ,new ,jersey1 some rude quartz implements were discovered by ,professor ,n4 ,h4 ,winchell in the glacial terraces of the upper ,mississippi1 in the vicinity of ,little ,falls1 ,morrison ,county1 ,minn4 ,this locality was afterwards more fully explored by ,miss ,franc ,e4 ,babbitt1 who succeeded in finding so large a number of the implements as to set at rest all question concerning their human origin4 ,according to ,mr4 ,warren ,upham1 the glacial flood-plain of the ,mississippi is here about three miles wide1 with an elevation of from twenty-five to thirty feet above the river4 ,it is in a stream near the bottom of this glacial terrace that the most of ,miss ,babbitt's discoveries were made1 and ,mr4 ,upham has pretty clearly shown that the gravel of the terrace overlying them was mostly deposited while the ice-front was still lingering about sixty miles farther north1 in the vicinity of ,itasca ,lake4,,cu ,footnote ,,cu3 ,for a general map1 see p4 #ff2 also p4 #bbe4 ,illustration3 ,fig4 #gb4--;,edge view of the preceding4 ,illustration3 ,fig4 #gc4--,section across the ,mississippi ,valley at ,little ,falls1 ,minnesota1 showing the stratum in which chipped quartz fragments were found by ,miss ,f4 ,e4 ,babbitt1 as described in the text 7,upham74 ,up to this time the above are all the instances in which the relics of man are directly and indubitably connected with deposits of this particular period east of the ,rocky ,mountains4 ,probably it is incorrect to speak of these as preglacial1 for the portion of the period at which the deposits incorporating human relics were made is well on towards the close of the great ,ice age1 since these terraces were1 in some cases1 and may have been in all cases1 deposited after the ice-front had withdrawn nearly1 if not quite1 to the water-shed of the ,st ,lawrence basin4 ,it may be difficult to demonstrate this with reference to the gravel deposits at ,trenton1 ,madisonville1 and ,medora1 but it is evident at a glance in the case of ,newcomerstown and ,little ,falls4 ,that the implement-bearing gravel of ,trenton1 ,n4 ,j41 belongs to the later stages of the ,glacial period is evident from its relation to what ,professor ,h4 ,carvill ,lewis called the ,philadelphia red gravel and brick-clay1 but which1 from its large development in the ,district of ,columbia at ,washington1 is called by ,mr4 ,mc,gee the ,columbia deposit4 ,the city of ,philadelphia is built upon this formation in the ,delaware ,valley1 and the brick for its houses is obtained from it2 the cellar of each house ordinarily furnishing clay enough for its brick walls4 ,this clay is of course a deposit in comparatively still water1 which would imply deposition during a period of land subsidence4 ,but that it was ice-laden water which flooded the banks is shown by the frequent occurrence of large blocks of stone in the deposits1 such as could have been transported only in connection with floating ice4 ,the boulders in the ,columbia formation clearly belong to the individual river valleys in which they are found1 and doubtless are to be connected with the flooded condition of those valleys when1 by means of a northerly subsidence1 the gradient of the streams was considerably less than now4 ,illustration3 ,fig4 #gd4--,quartz implement1 found by ,miss ,f4 ,e4 ,babbitt1 #ahgh1 at ,little ,falls1 ,minnesota1 in modified drift1 fifteen feet below surface3 a1 face view2 b1 profile view4 ,the black represented on the cut is the matrix of the quartz vein 7,no4 #ca1cbc7 7,putnam74 ,there is some difference of opinion in respect to the extent of this subsidence1 and1 indeed1 respecting the height attained by the ,philadelphia brick-clay1 or ,mc,gee's ,columbia deposit4 ,professor ,lewis 7whose residence was at ,philadelphia1 and who had devoted much time to field observations7 insisted that the deposit could not be found higher than from #ahj to #bjj feet above the immediate flood-plain of the river valleys where they occur4 ,but1 without entering upon this disputed question1 it is sufficient to consider the bearing of the facts that are accepted by all--namely1 that towards the close of the ,glacial period there was a marked subsidence of the land on the eastern coast of ,north ,america1 increasing towards the north4 ,fully to comprehend the situation1 we need to bring before the mind some of the indirect effects of the ,glacial period in this region4 ,the most important of these was the necessary projection of subglacial conditions over a considerable belt of territory to the south of that actually reached by glacial ice2 so that1 while there are no clear indications of the existence of local glaciers in the ,appalachian ,mountains south of the central part of ,pennsylvania1 there are many indications of increased snow-fall upon the mountains1 connected with prolonged winters and with a great increase of spring floods and ice-gorges upon the annual breaking up of winter4 ,these facts have been stated in detail by ,mr4 ,mc,gee1,,cv from whose report it appears that1 on the ,potomac at ,washington1 the surface of the ,columbia deposit is #aej feet above tide1 and that the deposit itself contains many boulders1 some of which are as much as two or three feet in diameter4 ,these are mingled with the gravel in such a way as to show that they must have been brought down by floating ice from the head-waters of the ,potomac when the winters were much more severe than now4 ,that this deposit is properly the work of the river is shown by the entire absence of marine shells4 ,footnote ,,cv3 ,seventh ,annual ,report of the ,united ,states ,geological ,survey for #ahhe and #ahhf1 pp4 #ecg-fdf4 ,according to ,mr4 ,mc,gee1 also1 there is a gradual decrease in the height of these delta terraces of the ,columbia period as they recede from the glacial boundary--that at the mouth of the ,susquehanna being #bde feet1 that of the ,potomac #adj feet1 that on the ,rappahannock #abe1 that on the ,james #ajj1 and that on the ,roanoke #ge2 while the size of the transported boulders along the streams also gradually diminishes in the same order4 ,during the ,columbia period the ,susquehanna ,river transported boulders fifty times the size now transported1 while the ,potomac transported them only up to twenty times1 the ,rappahannock only ten times1 the ,james only five1 and the ,roanoke only two or three times the size of those now transported4 ,this progressive diminution1 both in the extent of the deposit and in the coarseness of the material deposited by these rivers at about the time of the maximum portion of the ,glacial period1 is what would naturally be expected under the conditions supposed to exist in connection with the great ,ice age1 and is an important confirmation of the glacial theory4 ,that the period of subsidence and more intense glacial conditions during which the ,columbia deposits took place1 preceded1 by a long interval1 the deposition of the gravel terraces at ,trenton1 ,n4 ,j41 and the analogous deposits in the ,mississippi ,valley where palolithic implements have been found1 is evident enough4 ,the ,trenton gravel was deposited in a recess in the ,columbia deposit which had been previously worn out by the stream4 ,indeed1 in every place where opportunity offers for direct observation the ,trenton gravel is seen to be distinctly subsequent to the other4 ,it was not buried by the ,philadelphia red gravel and brick-clay1 but to a limited degree overlies and buries it4 ,the data for measuring the absolute length of time between these two stages of the ,glacial period are very indefinite4 ,mr4 ,mc,gee1 however1 supposes that since the ,columbia period a sufficient time has elapsed for the falls of the ,susquehanna to recede more than twenty miles and for those of the ,potomac eighteen miles1 and this through a rock which is exceedingly obdurate4 ,but1 in channels opening1 as these do1 freely outward1 it is difficult to tell in what epochs the erosion has been principally performed1 since there are no buried channels1 as in the glaciated area1 enabling us to determine whether or not much of the eroding work of the river may have been accomplished in preglacial times4 ,the lapse of time which1 upon the least calculation1 separates the ,columbia epoch from the ,trenton1 gives unusual importance to any discovery of palolithic implements which may be made in the earlier deposits4 ,we are bound1 therefore1 to consider with special caution the reported discovery of an implement in these deposits at ,claymont1 ,delaware4 ,the discovery was made by ,dr4 ,hilborne ,t4 ,cresson1 on ,july #ac1 #ahhg1 during the progress of an extensive excavation in constructing the ,baltimore and ,ohio ,railroad1 nineteen miles south of ,philadelphia4 ,the implement was from eight to nine feet below the surface4 ,as there is so much chance for error of judgment respecting the undisturbed condition of the strata1 and as there was so little opportunity for ,dr4 ,cresson to verify his conclusion1 we may well wait for the cumulative support of other discoveries before building a theory upon it2 still1 it will be profitable to consider the situation4 ,illustration3 ,fig4 #ge4--;,argillite implement1 found by ,h4 ,t4 ,cresson1 #ahhg1 in ,baltimore and ,ohio ,railroad cut1 one mile from ,claymont1 ,delaware1 in ,columbia gravel1 eight to nine feet below the overlying clay bed3 a1 face view2 b1 side view 7,no4 #de1gbf7 7,putnam74 ,both ,mr4 ,mc,gee and myself have visited the locality with ,dr4 ,cresson1 and there can be no doubt that the implement occurred underneath the ,columbia gravel4 ,the line of demarcation is here very sharp between that gravel and the decomposed strata of underlying gneiss rock1 which appears in our illustration as a light band in the middle of the section exposed4 ,some large boulders which could have been moved only in connection with floating ice are found in the overlying deposit near by4 ,this excavation is about one mile and a half west of the ,delaware ,river1 and about #aej feet above it1 being nearly at the uppermost limit of the ,columbia deposit in that vicinity4 ,illustration3 ,fig4 #gf4--;,general section of ,baltimore and ,ohio cut1 near ,claymont1 ,delaware1 where ,mr4 ,cresson found palolithic implements figured in the text 7from photograph by ,cresson74 ,the age of these deposits in which implements have been found at ,claymont and at ,trenton will be referred to again when we come to the specific discussion of the date of the ,glacial period4 ,it is sufficient here to bring before our minds clearly1 first1 the fact that this at ,claymont is connected with the river floods accompanying the ice at its time of maximum extension1 and when there was a gradually increasing or differential depression of the country to an unknown extent to the northward4 ,two radically different theories are presented to account for the deposits variously known as the ,columbia gravel and the ,philadelphia brick-clay4 ,mr4 ,mc,gee1 in the monograph above referred to1 supposes them to have been deposited during a period of a general subsidence of the coast-line2 so that they took place at about tide-level4 ,mr4 ,upham1 on the other hand1 supposes them to have been deposited during the period of general elevation to whose influence he mainly attributes the ,glacial period itself4 ,in his view much of the shallow sea-bottom adjoining the present shore off from ,delaware and ,chesapeake ,bays was then a land-surface1 and the ,hudson1 the ,delaware1 and the ,susquehanna ,rivers1 coming down from the still higher elevations of the north1 flowed through extensive plains so related to the northern areas of elevation that deposition was occurring in their valleys1 owing in part to the flooded condition of the streams1 in part to the differential elevation1 and in part to the superabundance of silt and other dbris furnished by the melting ice-sheet in the head-waters of these streams4 ,the deposits of ,trenton gravel occurred much later1 at a time when the ice had melted far back towards the head-waters of the ,delaware1 and after the land had nearly resumed its present relations of level1 if indeed it had not risen northward to a still greater relative height4 ,as would be expected from the climatic conditions accompanying the ,glacial epoch1 man's companions in the animal world were very different during the period when the high-level river gravels of ,america were forming from those with which he is now associated4 ,from the remains actually discovered1 either in these gravels or in close proximity to them1 we infer that1 while the mastodon was the most frequent of the extinct quadrupeds with which man then had to contend in that region1 he must have been familiar also with the walrus1 the ,greenland reindeer1 the caribou1 the bison1 the moose1 and the musk ox4 ,in the ,glacial ,terraces of ,europe4 ,the existence of glacial man in ,europe was first determined in connection with the high-level river gravels already described in the valley of the ,somme1 situated in ,picardy in the northern part of ,france4 ,here in #ahda ,boucher de ,perthes began to discover rudely fashioned stone implements in undisturbed strata of the gravel terraces1 whose connection with the ,glacial period we have already made clear4 ,but for nearly twenty years his discoveries were ignored by scientific men1 although he made persistent efforts to get the facts before them1 and published a full account of them with illustrations as early as #ahdg4 ,some suggested fraud on the part of the workmen2 others without examination declared that the gravel must have been disturbed2 while others1 still1 denied altogether the artificial character of the implements4 ,illustration3 ,fig4 #gg4--,section across valley of the ,somme3 #a1 peat1 twenty to thirty feet thick1 resting on gravel1 a2 #b1 lower-level gravels1 with elephant-bones and flint implements1 covered with river-loam twenty to forty feet thick2 #c1 upper-level gravels1 with similar fossils covered with loam1 in all1 thirty feet thick2 #d1 upland-loam1 five to six feet thick2 #e1 ,eocene-,tertiary4 ,at length1 ,dr4 ,regillout1 an eminent physician residing at ,amiens1 about forty miles higher up the ,somme than ,abbeville1 visited ,boucher de ,perthes1 and1 upon seeing the similarity between the gravel terraces at ,abbeville and ,amiens1 returned home to look for similar implements in the high-level gravel-pits at ,st4 ,acheul1 a suburb of ,amiens4 ,almost immediately he discovered flint implements there of the same pattern with those at ,abbeville1 and in undisturbed strata of the gravel terrace1 where it rested on the original chalk formation1 at a height of #ij feet above the river4 ,in the course of four years1 ,dr4 ,regillout found several hundred of these implements1 and in #ahed published an illustrated report upon the discoveries4 ,still the scientific world remained incredulous until the years #aheh and #ahei1 when ,dr4 ,falconer1 ,mr4 ,prestwich1 ,mr4 ,john ,evans1 ,mr4 ,flower1 ,sir ,charles ,lyell1 of ,england1 and ,,mm4 ,pouchet and ,gaudry1 of ,france1 visited ,abbeville and ,amiens1 and succeeded in making similar discoveries for themselves4 ,additional discoveries at ,st4 ,acheul have continued up to the present time whenever excavations have gone on at the gravel-pits4 ,mr4 ,prestwich estimates that there is an implement to every cubic metre of gravel1 and says that he himself has brought away at different times more than two hundred specimens1 and that the total number found in this one locality can hardly be under four thousand4 ,the gravel-beds are on the brow of a hill #ig feet above the river ,somme1 and besides the relics of man contain numerous fluviatile and land shells together with teeth and bones of the mammoth1 rhinoceros1 horse1 reindeer1 and red deer1 but not of the hippopotamus1,,cw bones of the latter animal being found here only in the gravels of the lower terraces1 where they are less than thirty feet above the river1 and mark a considerably later stage in the erosion of the valley4 ,while many of the implements found at ,amiens seem to have been somewhat worn and rolled1 others are as sharp and fresh as when first made4444 ,the bedding of the gravel is extremely irregular and contorted1 as though it had been pushed about by a force acting from above2 and this1 together with the occurrence of blocks of ,tertiary sandstone of considerable size1 leads to the inference that both are due to the action of river-ice4 ,in the ,seine ,valley blocks of still larger size1 and transported from greater distances1 are found in gravels of the same age4 ,footnote ,,cw3 ,prestwich's ,geology1 vol4 ii1 p4 #dha4 ,flint implements are found under similar conditions in many of the river-valleys of other parts of ,france1 especially in the neighbourhood of ,paris2 of ,mons in ,belgium2 in ,spain1 in the neighbourhood of ,madrid1 in ,portugal1 in ,italy1 and in ,greece2 but they have not been discovered in the drift-beds of ,denmark1 ,sweden1 or ,russia1 nor is there any well-authenticated instance of the occurrence of paloliths in ,germany4,,cx ,footnote ,,cx3 ,prestwich's ,geology1 vol4 ii1 pp4 #dha1 #dhb4 ,when once the fact had been established that man was in northern ,france at the time of the deposition of the high-level gravels of the ,somme and the ,seine1 renewed attention was directed to terraces of similar age in southern ,england4 ,one of these is that upon which the city of ,london is built1 and which1 according to ,lyell's description1 extends from above ,maidenhead through the metropolis to the sea1 a distance from west to east of fifty miles1 having a width varying from two to nine miles4 ,its thickness ranges commonly from five to fifteen feet4,,cy ,footnote ,,cy3 ,antiquity of ,man1 pp4 #aed1 #aee4 ,for a long time geologists had been familiar with the fact that these terraces of the ,thames contain the remains of numerous extinct animals1 among which are included the mammoth and a species of rhinoceros4 ,upon directing special attention to the subject1 it was found that1 at various intervals1 the remains of man1 also1 had been reported from the same deposits4 ,as long ago as #agae ,mr4 ,conyers discovered a palolithic implement1 in connection with the skeleton of an elephant1 at ,black ,mary's1 near ,gray's ,inn ,lane1 ,london4 ,this implement is preserved in the ,british ,museum1 and closely resembles typical specimens from the gravel at ,amiens4 ,other implements of similar character have been found in the valley of the ,wey near ,guilford1 also in the valley of the ,darent1 near ,whitstable in ,kent1 and between ,heme ,bay and the ,reculvers4 ,while the exact position of these implements in the gravel had not been so positively noted as in the case of those found at ,amiens and ,abbeville1 there can be little doubt that man1 in company with the extinct animals mentioned1 inhabited the valley of the ,thames at a period when its annual floods spread over the whole terrace-plain upon which the main part of ,london is built4 ,in the valley of the ,ouse1 however1 near ,bedford1 the discovery of palolithic implements in the gravel terraces connected with the ,glacial period and in intimate association with bones of the elephant1 rhinoceros1 hippopotamus1 and other extinct animals1 has been as fully established as in the valley of the ,somme4 ,the discoveries here were first made in the year #ahfj1 by ,mr4 ,james ,wyatt1 in a gravel-pit at ,biddenham1 two miles northwest of ,bedford4 ,two flint implements were thrown out by workmen in one day from undisturbed strata thirteen feet below the surface1 and numerous other specimens have since been found in a similar situation4 ,the valley of the ,ouse is bordered on either side by sections of a superficial blanket of glacial drift containing many transported boulders of considerable size4 ,the valley is here about two miles wide1 and ninety feet deep4 ,the gravel deposit1 however1 in which the implements were found1 is only about thirty feet above the present level of the river1 and hence represents the middle period of the work of the river in erosion4 ,another locality in ,england in which similar discoveries have been made1 is at ,hoxne1 about five miles from ,diss1 in ,suffolk ,county4 ,like that in the valley of the ,thames1 however1 the implements were found a long time before the significance of the discovery was recognized4 ,mr4 ,john ,frere reported the discovery to the ,society of ,antiquaries in #ahja1 and gave some of the implements both to the society and to the ,british ,museum1 in whose collections they are still preserved4 ,the implements are of the true palolithic type1 and existed in such abundance1 and were so free from signs of wear1 that the conclusion seemed probable that a manufactory of them had been uncovered4 ,as many as five or six to the square yard are said to have been found4 ,indeed1 their numbers were so great that the workmen had emptied baskets of them into the ruts of the adjoining road before becoming aware of their value4 ,the deposit in which they are found is situated in the valley of ,gold ,brook1 a tributary of the ,waveney4 ,the implements occurred about twelve feet below the surface1 in fresh-water deposits1 filling a hollow eroded in the glacial deposit covering that part of ,england4 ,this1 therefore1 is clearly either of post-glacial or of late glacial age4 ,still another locality in which similar palolithic implements were found in undisturbed gravel of this same age in eastern ,england is ,icklingham1 in the valley of the ,lark1 where the situation is quite similar to that already described at ,bedford1 on the ,ouse4 ,the last place we will stop to mention in ,england which was visited by palolithic man1 during or soon after the ,glacial epoch1 is to be found in the vicinity of ,southampton4 ,at this time the ,isle of ,wight was joined to the mainland1 and not improbably ,england itself to the ,continent4 ,the river1 then flowing through the depression of the ,solent and the ,southampton ,water1 occupied a much higher level than now1 leaving terraces along the shore at various places1 in which the tools of palolithic man have been discovered4 ,though these are the best authenticated discoveries connecting man with the ,glacial period in ,england1 they are by no means the only probable cases4 ,almost every valley of southern ,england furnishes evidence of a similar but less demonstrative character4 ,in ,cave ,deposits4 ,the discovery of the remains of man in the high-level river-gravels deposited near the close of the ,glacial period led to a revision of the evidence which had from time to time been reported connecting the remains of man with those of various extinct animals in cave deposits both in ,england and upon the ,continent4 ,the ,british ,isles4 ,as early as #ahbf1 ,rev4 ,j4 ,mac,enery1 a ,roman ,catholic priest residing near ,torquay1 in ,devonshire1 ,england1 had made some most remarkable discoveries in a cavern at ,kent's ,hole1 near his home2 but1 owing to his early death1 and to the incredulity of that generation of scientific men1 his story was neither credited nor published till #ahei4 ,about this time1 a new cave having been discovered not far away1 at ,brixham1 the best qualified members of the ,royal ,society 7,lyell1 ,phillips1 ,lubbock1 ,evans1 ,vivian1 ,pengelly1 ,busk1 ,dawkins1 and ,sanford7 were deputed to see that it was carefully explored4 ,mr4 ,pengelly1 who had had twenty years' experience in similar explorations1 directed and superintended the work4 ,every portion of the contents was examined with minutest care4 ,kent's ,hole is #ahj to #aij feet above the level of mean tide1 and about #gj feet above the bottom of the valley immediately adjacent4,,cz ,in one chamber the excavation was about sixty feet square4 ,the contents were arranged in the following order3 ,footnote ,,cz3 ,dawkins's ,cave-,hunting1 p4 #cbe4 ,illustration3 ,fig4 #gh4--,mouth of ,kent's ,hole4 #a4 ,a surface of dark earth a few inches thick1 containing ,roman pottery1 iron and bronze spear-heads1 together with polished stone weapons4 ,there were1 too1 in this stratum bones of cows1 goats1 and horses1 mingled with large quantities of charcoal4 #b4 ,below this was a stalagmite floor from one to three feet thick1 formed by the dripping of lime-water from the roof4 #c4 ,under this crust of stalagmite was a compact deposit of red earth1 from two to thirteen feet thick4,,da ,flint implements of various kinds and charcoal were also found at different depths2 also an awl1 or piercer2 a needle with the eye large enough to admit small pack-thread2 and three harpoon-heads made out of bone and deer's horn4 ,footnote ,,da3 ,dawkins's ,cave-,hunting1 p4 #cbf2 ,lyell's ,antiquity of ,man1 p4 #aja4 #d4 ,flint implements were also obtained in a conglomerate 7breccia7 still below this4 ,the fossil bones in this cave belonged to the same species of animals as those discovered in a cave near ,wells4 ,the ,brixham cave occurs near the small village of that name1 not far from ,torquay4 ,the entrance to it is about ninety-five feet above high water4 ,its deposits1 in descending order1 are3 #a4 ,stalagmitic floor from six to twelve or fifteen inches in thickness4 #b4 ,a thin breccia of limestone fragments cemented together by carbonate of lime4 ,this had accumulated about the mouth1 so as to fill up the entrance4 #c4 ,a layer of blackish earth about one foot in thickness #d4 ,a deposit of from two to four feet thick1 consisting of clayey loam1 mingled with fragments of limestone1 from small bits up to rocks weighing a ton4 ,bounded pebbles of other material were also occasionally met with4 #e4 ,shingle consisting of rounded pebbles largely of foreign material4 ,all these strata1 except the third1 contained fossils of some kind1 but the fourth was by far the richest repository4 ,among the bones found are those of the mammoth1 the woolly rhinoceros1 the horse1 the ox1 the reindeer1 the cave-lion1 the cave-hyena1 and the cave-bear4 ,associated with these remains a number of worked flints was found4 ,in one place the bones of an entire leg of a cave-bear occurred in such a position as to show that they must have been bound together by the ligaments when they were buried4 ,immediately below these bones a flint implement was found4,,db ,footnote ,,db3 ,see ,pengelly's ,reports to the ,devonshire ,association1 #ahfg4 ,the hyena's den1 at ,wookey ,hole1 near ,wells1 in ,somerset1 was carefully explored by ,professor ,boyd ,dawkins1 who stood by and examined every shovelful of material as it was thrown out4 ,this cave alone yielded #ce specimens of palolithic art1 #dfg jaws and teeth of the cave-hyena1 #ae of the cave lion1 #bg of the cave-bear1 #aa of the grizzly bear1 #aa of the brown bear1 #g of the wolf1 #h of the fox1 #cj of the mammoth1 #bcc of the woolly rhinoceros1 #dja of the horse1 #af of the wild ox1 #cj of the bison1 #ce of the ,irish elk1 and #cj of the reindeer 7jaws and teeth only74 ,in ,derbyshire numerous caves were explored by ,professor ,dawkins at ,cress well ,crags1 which1 in addition to flint implements and the remains of the animals occurring in the ,brixham cave1 yielded the bones of the machairodus1 an extinct species of tiger or lion which lived during the ,tertiary period4 ,the ,victoria cave1 near ,settle1 in west ,yorkshire1 is the only other one in ,england which we need to mention4 ,in this there were no remains found which could be positively identified as human1 but the animal remains in the lower strata of the cave deposit were so different from those in the upper bed as to indicate the great lapse of time which separated the two4 ,this cave is #a1dej feet above the sea-level1 and there were found in the upper strata of the floor1 down to a depth of from two to ten feet1 many remains of existing animals4 ,then1 for a distance of twelve feet1 there occurred a clay deposit1 containing no organic remains whatever1 but some well-scratched boulders4 ,below this was a third stratum of earth mingled with limestone fragments1 at the base of which were numerous remains of the mammoth1 rhinoceros1 hippopotamus1 bison1 hyena1 etc4 ,one bone occurred which was by some supposed to be human1 but by others to have belonged to a bear4 ,this lower stratum is1 without much doubt1 preglacial1 and the thickness of the deposit intervening between it and the upper fossiliferous bed is taken by some to indicate the great lapse of time separating the period of the mammoth and rhinoceros in ,england from the modern age4 ,the scratched boulders in the middle stratum of laminated clay1 would indicate certainly that the material found its way into the cave during the ,glacial epoch1 when ice filled the whole valley of the ,ribble1 which flows past the foot of the hill1 and whose bed is #ijj feet below the mouth of the cave4 ,in ,north ,wales the ,vale of ,clwyd contains numerous caves which were occupied by hyenas in preglacial times and with their bones are associated those of the mammoth1 the rhinoceros1 the hippopotamus1 the cave-lion1 the cave-bear1 and various other animals4 ,flint implements also were found in the cave at ,cae ,gwyn1 near the village of ,tremeirchon1 on the eastern side of the valley1 opposite ,cefn1 and about four miles distant4 ,we have already given an illustration of the ,cefn cave 7see page #adh74 ,it will be observed that this valley of the ,clwyd opens to the north1 and has a pretty rapid descent to the sea from the ,welsh mountains1 and was in position to be obstructed by the ,irish ,sea glacier1 so as to have been occupied at times by one of the characteristic marginal lakes of the ,glacial period4 ,it is evident also that the northern ice prevailed over the ,welsh ice for a considerable portion of the lower part of the valley2 for northern drift is the superficial deposit upon the hills on the sides of the valley up to a height of over #ejj feet4 ,from the investigations of ,mr4 ,c4 ,e4 ,de ,rance1 ,f4 ,g4 ,s41,,dc it is equally clear also that the northern drift1 which until lately sealed up the entrance of the cave1 was subsequent to its occupation by man1 and this was the opinion formed by ,sir ,archibald ,geikie1 ,director ,general of the ,geological ,survey of the ,united ,kingdom1 as the result of special investigations which he made of the matter4,,dd ,footnote ,,dc3 ,proceedings of the ,yorkshire ,geological ,society for #ahhh1 pp4 #a-bj4 ,footnote ,,dd3 ,see ,de ,ranee1 as above1 p4 #ag2 and article by ,h4 ,hicks1 in ,quarterly ,journal of ,geological ,society1 vol4 xlii1 p4 #c2 ,geological ,magazine1 ,may1 #ahhe1 p4 #eaj4 ,from the caves in the ,vale of ,clwyd as many as #djj teeth of rhinoceros1 #ejj of horse1 #ahj of hyena1 and #ae of mammoth have been taken4 ,a section of the cave deposits in the cave at ,cae ,gwyn is as follows3 ,below the soil for about eight feet a tolerably stiff boulder-clay1 containing many ice-scratched boulders and narrow bands and pockets of sand4 ,below this about seven feet of gravel and sand1 with here and there bands of red clay1 having also many ice-scratched boulders4 ,the next deposit was a laminated brown clay1 and under this was found the bone-earth1 a brown1 sandy clay with small pebbles and with angular fragments of limestone1 stalagmites1 and stalactites4 ,during the excavations it became clear that the bones had been greatly disturbed by water action2 that the stalagmite floor1 in parts more than a foot in thickness1 and massive stalactites1 had also been broken and thrown about in all positions2 and that these had been covered afterwards by clays and sand containing foreign pebbles4 ,this seemed to prove that the caverns1 now #djj feet above ordnance datum1 must have been submerged subsequently to their occupation by the animals and by man4 ,in ,dr4 ,hicks's opinion1 the contents of the cavern must have been disturbed by marine action during the great submergence in mid-glacial times1 and afterwards covered by marine sands and by an upper boulder-clay1 identical in character with that found at many points in the ,vale of ,clwyd4 ,the paleontological evidence suggests that the deposits in question are not preglacial1 but may be equivalent to the ,pleistocene deposits of our river-valleys4,,de ,footnote ,,de3 ,h4 ,b4 ,woodward's ,geology of ,england and ,wales1 pp4 #edc1 #edd ,if the views of ,professor ,lewis and ,mr4 ,kendall are correct concerning the unity of the ,glacial period in ,england1 the shelly and sandy deposits connected with these ,clwydian caves at an elevation of #djj feet or more would be explained in connection with the marginal lakes which must have occupied the valley during both the advance and the retreat of the ice-front2 the shells having been carried up from the sea-bottom by the ice-movement1 after the manner supposed in the case of those at ,macclesfield and ,moel ,tryfaen4 ,if1 therefore1 the statements concerning the discovery of flint implements in this ,cae ,gwyn cave can be relied upon1 this is the most direct evidence yet obtained in ,europe of man's occupation of the island during the continuance of the ,glacial period4 ,in all these caves it is to be noted that there is a sharp line of demarcation between the strata containing palolithic implements and those containing only the remains of modern animals4 ,palolithic implements are confined to the lower strata1 which in some of the caves are separated from the upper by a continuous bed of stalagmite1 to which reference will be made when discussing the chronology of the ,glacial period4 ,the remains of extinct animals also are confined to the lower beds4 ,the caves which we have been considering in ,england are all in limestone strata1 and have been formed by streams of water which have enlarged some natural fissures both by mechanical action in wearing away the rocks1 and by chemical action in dissolving them4 ,through the lowering of the main line of drainage1 caverns with a dry floor are at length left1 offering shelter and protection both to man and beast4 ,oftentimes1 but not always1 some idea of the age of these caverns may be obtained by observing the depth to which the main channel of drainage to which they were tributary has been lowered since their formation4 ,but to this subject also we will return when we come specifically to discuss the chronological question4 ,the ,continent4 ,systematic explorations in the caves of ,belgium were begun in #ahcc by ,dr4 ,schmerling1 in the valley of the ,meuse1 near his residence in ,lige4 ,the ,meuse is here bordered by limestone precipices #bjj or more feet in height4 ,opening out from these rocky walls are the entrances to the numerous caverns which have rendered the region so famous4 ,to get access to the most important of these1 ,dr4 ,schmerling had to let himself down over a precipice by a rope tied to a tree1 and then to creep along on all-fours through intricate channels to reach the larger chambers which it was his object to explore4 ,in the cave at ,engis1 on the left bank of the ,meuse1 about eight miles above ,lige1 he found a human skull deeply buried in breccia in company with many bones of the extinct animals previously stated to have been associated with man during the ,glacial period4 ,this so-called ,engis skull was by no means apelike in its character1 but closely resembled that of the average ,caucasian man4 ,but this established the association upon the ,continent of man with some of the extinct animals of the ,glacial period4 ,illustration3 ,fig4 #gi4--;,engis skull1 reduced 7after ,lyell47 ,the vicinity of ,lige has also furnished us another cavern whose contents are of the highest importance1 ranking indeed as perhaps the most significant single discovery yet made4 ,the cave referred to is on the property of the ,count of ,beauffort1 in the commune of ,spy1 in the province of ,namur in ,belgium4 ,for the facts relating to it we are indebted to ,messrs3 ,lohest and ,fraipont1 the former ,professor of ,geology and the latter of ,anatomy in the ,university of ,lige4 ,the exploration of the cave was made in #ahhf1 and the full report with illustrations published in the following year in ,archives de ,biologie4,,df ,the significance of this discovery is enhanced by the light it sheds upon and the confirmation it brings to the famous ,neanderthal skull and others of similar character1 which for a long time had been subjects of vigorous discussion4 ,before describing it1 therefore1 we will give a brief account of the previous discoveries4 ,footnote ,,df3 ,see pp4 #ehg1 #geg4 ,the famous ,neanderthal skull was brought to light in #aheg by workmen in a limestone-quarry1 near ,dsseldorf1 in the valley of the ,neander1 a small tributary to the ,rhine4 ,by these workmen a cavern was opened upon the southern side of the winding ravine1 about sixty feet above the stream and one hundred feet below the top of the cliff4 ,the skull attracted much attention from its supposed possession of many apelike characteristics2 indeed1 it was represented by some to be a real intermediate link between man and the anthropoid apes4 ,the accompanying cut enables one to compare the outline of the ,neanderthal skull with that of a chimpanzee on the one hand and of the highly developed ,european on the other4 ,the apelike peculiarities of this skull appear in its vertical depression1 in the enormous thickness of the bony ridges just above the eyes1 and in the gradual slope of the back part of the head1 together with some other characteristics which can only be described in technical language2 so that it was pronounced by the highest authorities the most apelike of human crania which had yet been discovered4 ,unfortunately1 the jaw was not found4 ,the capacity of the skull1 however1 was seventy-five cubic inches1 which is far above that of the highest of the apes1 being indeed equal to the average capacity of ,polynesian and ,hottentot skulls4,,dg ,huxley well remarks that so large a mass of brain as this would alone suggest that the pithecoid tendencies indicated by this skull did not extend deep into the organization4 ,footnote ,,dg3 ,huxley's ,man's ,place in ,nature1 p4 #aha4 ,illustration3 ,fig4 #hj4--;,comparison of forms of skulls3 a1 ,european2 b1 the ,neanderthal man2 c1 a chimpanzee 7after ,lyell74 ,illustration3 ,fig4 #ha4--,skull of the ,man of ,spy4 7,from photograph47 ,upon extending inquiries1 it was found that the ,neanderthal type of skull is one which still has representatives in all nations2 so that it is unsafe to infer that the individual was a representative of all the individuals living in his time4 ,the skull of ,bruce1 the celebrated ,scotch hero1 was a close reproduction of the ,neanderthal type2 while1 according to ,quatrefages1,,dh the skull of the ,bishop of ,toul in the fourth century even exaggerates some of the most striking features of the ,neanderthal cranium4 ,the forehead is still more receding1 the vault more depressed1 and the head so long that the cephalic index is #fi-da4 ,the discovery of ,messrs4 ,fraipont and ,lohest adds much to our definite knowledge of the ,neanderthal type of man1 since the ,belgic specimens are far more complete than any others heretofore found1 there being in their collection two skulls1 together with the jawbones and most of the other parts of the frame4 ,in this case also there is no suspicion that the deposits had been disturbed1 so as to admit any intrusion of human relics into the company of relics of an earlier age4 ,according to ,m1 ,lohest1 there were three distinct ossiferous beds1 separated by layers of stalagmite4 ,all the ossiferous beds contained the remains of the mammoth1 but in the upper stratum they were few1 and probably intrusive4 ,the implements found in this were also of a more modern type4 ,in the second stratum from the top numerous hearths were found with burnt wood and ashes1 together with the bones of the rhinoceros1 the horse1 the mammoth1 the cave-bear1 and the cave-hyena1 all of which were abundant1 while there were also specimens of the ,irish elk1 the reindeer1 the bison1 the cave-lion1 and several other species4 ,in this layer also there were numerous implements of ivory1 together with ornaments and some faint indications of carving upon the rib of a mammoth1 besides a few fragments of pottery4 ,footnote ,,dh3 ,human ,species1 p4 #caj1 ,it was in the third1 or lowest1 of these beds that the skeletons were found4 ,here they were associated with abundant remains of the rhinoceros1 the horse1 the bison1 the mastodon1 the cave-hyena1 and a few other extinct species4 ,flint implements also1 of the ,mousterien pattern 7which1 according to the opinion of the ,french archologists1 is characteristic of middle palolithic times71 were abundant ,neither of the skeletons was complete1 but they were sufficiently so to give an adequate idea of the type to which they belong1 and one of the skulls is nearly perfect4 ,according to ,m4 ,fraipont1 one of these skulls is apparently that of an old woman1 the other that of a middle-aged man4 ,they are both very thick2 the former is clearly dolichocephalic 7long-headed1 index #gj71 the other less so4 ,both have very prominent eyebrows and large orbits1 with low1 retreating foreheads1 excessively so in the woman4 ,the lower jaws are heavy4 ,the older has almost no projecting chin4 ,the teeth are large1 and the last molar is as large as the others4 ,these points are characteristic of an inferior and the oldest-known race4 ,the bones indicate1 like those of the ,neanderthal and ,naulette specimens1 small1 square-shouldered individuals4 ,they were powerfully built1 with strong1 curiously curved thigh-bones1 the lower ends of which are so fashioned that they must have walked with a bend at the knees4,,di ,footnote ,,di3 ,huxley1 ,nineteenth ,century1 vol4 xxviii 7,november1 #ahij71 p4 #ggd4 ,other crania from various ,quaternary deposits in ,europe seem to warrant the inference that this type of man was the prevalent one during the early part of the ,palolithic age4 ,as long ago as #agjj a skull of this type was exhumed in ,canstadt1 a village in the neighbourhood of ,stuttgart1 in ,wrtemberg4 ,this was found in coexistence with the extinct animals whose bones we have described as so often appearing in the high-level river-gravel of the ,glacial age4 ,but the importance of the discovery at ,canstadt was not appreciated until about the middle of the present century4 ,from the priority of the discovery1 and of the discussion among ,german anthropologists concerning it1 it has been thought proper1 however1 by some to give the name of this village to the race and call it the ,canstadt race4 ,but1 whatever name prevails1 it is important in our reading to keep in mind that the man of ,canstadt1 the man of ,neanderthal1 and the man of ,spy are identical in type1 and probably in age4 ,similar discoveries have been made in various other places4 ,among these are a lower jaw of the same type discovered in #ahfe by ,m4 ,dupont1 at ,naulette1 in the valley of the ,lesse1 in ,belgium1 and associated with the remains of extinct animals2 a jawbone found in a grotto at ,arcy2 a fragment of a skull found in #ahfe by ,faudel1 in the loess of ,eguisheim1 near ,colmar2 a skull at ,olmo1 discovered in #ahfc1 in a compact clayey deposit forty-five feet below the surface2 and a skull discovered in #ahhd at ,marcilly4 ,m4 ,dupont has brought to light much additional testimony to glacial man from other caves in different parts of ,belgium4 ,in all he has explored as many as sixty4 ,three of these1 in the valley of the ,montaigle1 situated about one hundred feet above the river1 contained both remains of man and many bones of the mammoth and other associated animals1 which had evidently been brought in for food4 ,in the hilly parts of ,germany1 also1 and in ,hungary1 and even in the ,ural ,mountains in ,russia1 and in one of the provinces of ,siberia1 the remains of the rhinoceros1 and most of the other animals associated with man in glacial times1 have been found in the cave deposits which have been examined4 ,though it can not be directly proved that these animals were associated with man in any of these places1 still it is interesting to see how wide-spread the animals were in northern ,europe and ,asia during the ,glacial period4 ,some northern animals1 also1 spread at this time into southern ,europe--remains of the reindeer having been discovered on the south slope of the ,pyrenees1 but the remains of the mammoth1 the woolly rhinoceros1 and the musk ox1 have not been found so far south4 ,african species of the elephant1 however1 seem at one time to have had free range throughout ,spain1 and the hippopotamus roamed in vast herds over the valleys of ,sicily1 while several species of pygmy elephants seem to be peculiar to the island of ,malta4 ,in the case of all the cave deposits referred to 7with possibly the exception of those of ,victoria1 ,england1 and ,cae ,gwyn1 ,wales71 the evidence of man's existence during the ,glacial period is inferential1 and consists largely in the fact that he was associated with various extinct animals which did not long survive that period1 or with animals that have since retired from ,europe to their natural habitat in mountain-heights or high latitudes4 ,the men whose remains are found in the high-level river-drift1 and in the caverns described1 were evidently not in possession of domestic animals1 as their bones are conspicuous for their absence in all these places4 ,the horse1 which would seem to be an exception1 was doubtless used for food1 and not for service4 ,if we were writing upon the general subject of the antiquity and development of the human race1 we should speak here in detail of several other caves and rock shelters in ,france and southern ,europe1 where remains of man belonging to an earlier period have been found4 ,we should mention the rock shelter of ,cro-,magnon in the valley of ,vezre1 as well as that of ,mentone1 where entire human skeletons were found4 ,but it is doubtful if these and other remains from caves which might be mentioned belong in any proper sense to the ,glacial period4 ,the same remarks should be made also with reference to the lake-dwellings in ,switzerland1 of which so much has been written in late years4 ,all these belong to a much later age than the river-drift man of whom we are speaking1 and of whom we have such abundant evidence both in ,europe and in ,america4 ,illustration3 ,fig4 #hb4--,tooth of ,machairodus neogus1 #a_/f 7drawn from a cast74 ,illustration3 ,fig4 #hc4--,perfect tooth of an ,elephas1 found in ,stanislaus ,county1 ,california1 #a_/h natural size4 ,extinct ,animals associated with ,man during the ,glacial ,period4 ,this is the proper place in which to speak more fully of the extinct animals which accompanied man in his earliest occupation of ,europe and ,america1 and whose remains are so abundant in the river-drift gravel and in the caves of ,england1 in connection with the relics of man4 ,among these animals are ,the ,lion1 which is now confined1 to ,africa and the warmer portions of ,asia4 ,but in glacial times a large species of this genus ranged over ,europe from ,sicily to central ,england4 ,the saber-toothed ,tiger1 with tusks ten inches long3 7,machairodus latidens71 is now extinct4 ,this species was in existence during the latter part of the ,tertiary period1 but continued on until after man's appearance in the ,glacial period4 ,the presence of this animal would seem to indicate a warm climate4 ,the ,leopard 7,felis pardus7 is now confined to ,africa and southern ,asia1 and the larger islands adjoining2 but during man's occupation of ,europe in the ,glacial epoch he was evidently haunted at every step by this animal2 for his bones are found as far north in ,england as palolithic man is known to have ranged4 ,the ,hyena4 ,two species of this animal are found in the bone-caves of ,europe4 ,during the ,glacial epoch they ranged as far up as northern ,england1 but they are now limited to ,africa and southwestern ,asia4 ,illustration3 ,fig4 #hd4--,skull of ,hyena spela1 #a_/d4 ,the ,elephant is represented in the ,preglacial and ,glacial epochs by several species1 some of which ranged as far north as ,siberia4 ,the ,african elephant is not now found north of the ,pyrenees and the ,alps4 ,but a species of dwarf elephant1 but four or five feet in height1 has already been referred to as having occupied ,malta and ,sicily2 and still another species has been found in ,malta1 whose average height was less than three feet4 ,an extinct species 7,elephas antiquus71 whose remains are found in the river-drift and in the lower strata of sediment in many caverns as far north as ,yorkshire1 ,england1 was of unusual size1 and during the ,glacial period was found on both sides of the ,mediterranean4 ,but the species most frequently met with in palolithic times was the mammoth 7,elephas primigenius74 ,this animal1 now extinct1 accompanied man in nearly every portion both of ,europe and ,north ,america1 and lingered far down into post-glacial times before becoming extinct4 ,this animal was nearly twice the weight of the modern elephant1 and one third taller4 ,occasionally his tusks were more than twelve feet long1 and curved upward in a circle4 ,it is the carcasses of this animal which have been found in the frozen soil of ,siberia and ,alaska4 ,it had a thick covering of long1 black hair1 with a dense matting of reddish wool at the roots4 ,during the ,glacial period these animals must have roamed in vast herds over the plains of northern ,france and southern ,england1 and the northern half of ,north ,america4 ,illustration3 ,fig4 #he4--;,celebrated skeleton of mammoth1 in ,st4 ,petersburg museum4 ,illustration3 ,fig4 #hf4--,molar tooth of mammoth 7,elephas primigenius73 a1 grinding surface2 b1 side view4 ,the ,hippopotamus is at present a familiar animal in the larger rivers of ,africa1 but is not now found in ,europe4 ,during the ,glacial period1 however1 he ranged as far north as ,yorkshire1 ,england1 and his remains were found in close association with those of man1 both in ,europe and on the ,pacific coast in ,america4 ,twenty tons of their bones have been taken from a single cave in ,sicily4,,dj ,footnote ,,dj3 ,prestwich's ,geology1 vol4 ii1 p4 #ejh4 ,illustration3 ,fig4 #hg4--,tooth of ,mastodon ,americanus4 ,the mammoth and the rhinoceros we know to have been adapted to cold climates by the possession of long hair and thick fur1 but the hippopotamus by its love for water would seem to be precluded from the possession of this protective covering4 ,it is suggested1 however1 by ,sir ,william ,dawson1 that he may have been adapted to arctic climates by a fatty covering1 as the walrus is at the present time4 ,a difficulty in accounting for many of the remains of the hippopotamus in some of the ,english caverns is that they are so far away from present or possible water-courses4 ,but it would seem that due credit has not been ordinarily given to the migratory instincts of the animal4 ,in southern ,africa they are known to travel speedily for miles over land from one pool of a dried-up river to another2 but it is by water that their powers of locomotion are surpassingly great1 not only in rivers1 but in the sea4444 ,the geologist1 therefore1 may freely speculate on the time when herds of hippopotami issued from ,north ,african rivers1 such as the ,nile1 and swam northward in summer along the coasts of the ,mediterranean1 or even occasionally visited islands near the shore4 ,here and there they may have landed to graze or browse1 tarrying awhile1 and afterwards continuing their course northward4 ,others may have swum in a few summer days from rivers in the south of ,spain or ,france to the ,somme1 ,thames1 or ,severn1 making timely retreat to the south before the snow and ice set in4,,dk ,footnote ,,dk3 ,lyell1 ,antiquity of ,man1 p4 #ahj1 ,the ,mastodon 7,mastodon ,americanus71 7,fig4 #hh71 is probably the largest land mammal known1 unless we except the ,dinotherium4 ,it was twelve to thirteen feet high1 and1 including the tusks1 twenty-four to twenty-five feet long4 ,it differed from the elephant chiefly in the character of its teeth4 ,the difference is seen in ,figs4 #hf and #hg4 ,the elephant's tooth given above 7,fig4 #hf7 is sixteen inches long1 and the grinding surface eight inches by four4 ,illustration3 ,fig4 #hh4--,mastodon ,americanus 7after ,owen74 ,the mastodon1 together with the mammoth1 made their appearance about the middle of the ,miocene epoch4 ,at the close of the ,tertiary period the mastodon became extinct on the ,eastern ,continent1 but continued in ,north ,america to be a companion of man well on toward the close of the ,glacial period4 ,many perfect skeletons have been found in the deposits of this period in ,north ,america4 ,one magnificent specimen was found in a marsh near ,newburg1 ,new ,york1 with its legs bent under the body1 and the head thrown up1 evidently in the very position in which it mired4 ,the teeth were still filled with the half-chewed remnants of its food1 which consisted of twigs of spruce1 fir1 and other trees2 and within the ribs1 in the place where the stomach had been1 a large quantity of similar material was found4,,dl ,footnote ,,dl3 ,le ,conte's ,geology 7edition of #ahia71 p4 #ehb4 ,the ,rhinoceros is now confined to ,africa and southern ,asia2 but the remains of four species have been found in ,america1 ,europe1 and northern ,asia1 in deposits of the ,glacial period4 ,in company with that of the mammoth1 already spoken of1 a carcass of the woolly rhinoceros was found in #agga in the frozen soil of northern ,siberia4 ,the bones of other species have been found as far north as ,yorkshire1 ,england4 ,in the valley of the ,somme there was found the whole hind limb of a rhinoceros1 the bones of which were still in their true relative position4 ,they must have been joined together by ligaments and even surrounded by muscles at the time of their interment4 ,an entire skeleton was found near by4 ,the gravel terrace in which these occurred is about forty feet above the floor of the valley1 and must have been formed subsequent to some of the strata which contained the remains of human art4 ,in ,america the bones are found in the gold-bearing gravels of ,california1 in connection with human remains4 ,illustration3 ,fig4 #hi4--,skeleton of ,rhinoceros tichorhinus4 ,illustration3 ,fig4 #ij4--,skull of cave-bear 7,ursus spelus71 ,the ,bear was represented in ,europe in palolithic times by three species1 of which only one exists there at the present time4 ,but during the ,glacial period the grizzly bear1 now confined to the western part of ,america1 and the extinct cave-bear were companions1 or enemies as the case may be1 of man throughout ,europe4 ,the cave-bear was of large size1 and his bones occur almost everywhere in the lower strata of sediment in the caves of ,england4 ,the ,great ,irish ,elk1 or deer1 is now extinct1 though it is supposed by some to have lingered until historic times4 ,its remains are found widely distributed over middle ,europe in deposits of palolithic age4 ,illustration3 ,fig4 #ia4--,skeleton of the ,irish elk 7,cervus megaceros74 ,the ,horse was also1 as we have seen1 a very constant associate of man in middle ,europe during the ,palolithic age1 but probably not as a domesticated animal4 ,the evidence is pretty conclusive that he was prized chiefly for food4 ,about some of the caves in ,france such immense quantities of their bones are found that they can be accounted for best as refuse-heaps into which the useless bones had been thrown after their feasts1 after the manner of the disposal of shells of shell-fish4 ,in ,america the horses associated with man were probably of a species now extinct4 ,the skull of one 7,equus excelsus7 recently found in ,texas1 in ,pleistocene deposits1 associated with human implements1 is1 according to ,cope1 intermediate in character between the horse and quagga4,,dm ,the frontal bone was crushed in in a manner to suggest that it had been knocked in the head with a stone hammer1 such as was found in the same bed4 ,possibly1 therefore1 man's love of horse-flesh may have been an important element in securing the extinction of the species in ,america4 ,footnote ,,dm3 ,american ,naturalist1 vol4 xxv 7,october1 #ahia71 p4 #iab4 ,besides these animals there were associated with man at this time the ,musk ,sheep and the ,reindeer1 both now confined to the regions of the far north1 but during the ,glacial period ranging into southern ,france1 and mingling their bones with those both of man and of the southern species already enumerated4 ,illustration3 ,fig4 #ib4--,musk-sheep 7,ovibos moschatius74 ,the ,wolverine1 the ,arctic ,fox1 the ,marmot1 the ,lemming--all now confined to colder regions--at that time mingled on the plains of central ,europe with the species mentioned as belonging now to ,africa and southern ,asia4 ,the ,ibex1 also1 and the ,snowy ,vole and ,chamois descended to the plains from their mountain-heights1 and joined in the strange companionship of animals from the north and from the south4 ,besides these extremes there were associated with man during the ,glacial period numerous representatives of the temperate group of existing animals1 such as the bison1 the horse1 the stag1 the beaver1 the hare1 the rabbit1 the otter1 the weasel1 the wild-cat1 the fox1 the wolf1 the wild boar1 and the brown bear4 ,illustration3 ,fig4 #ic4--,reindeer4 ,to account for this strange intermingling of arctic and torrid species of animals1 especially in ,europe1 during man's occupancy of the region in glacial times1 various theories have been resorted to1 but none of them can be said to be altogether satisfactory4 ,one hypothesis is that the bones of these diverse animals became mingled by reason of the great range of the annual migration of the species4 ,the reindeer1 for example1 still performs extensive annual migrations4 ,in summer it ventures far out upon the tundras of ,north ,america and ,siberia to feed upon the abundant vegetation that springs up like magic under the influence of the long days of sunshine2 while1 as winter approaches1 it returns to the forests of the interior4 ,or in other places this animal and his associates1 like birds of passage1 move northward in summer to escape the heat1 and southward in the winter to escape the extreme cold4 ,many of the other animals also are more or less migratory in their habits4 ,thus it is thought that during the ,glacial period1 when man occupied northern ,france and southern ,england1 the reindeer1 the musk sheep1 the arctic fox1 and perhaps the hippopotamus and some other animals1 annually vibrated between northern ,england and southern ,france1 a slight elevation of the region furnishing a land passage from ,england to the continent2 while the chamois and other ,alpine species vibrated as regularly between the valleys in winter and the mountain-heights in summer4 ,the habits of these species are such that it is not difficult to see how in their case this migration could have taken place4 ,professor ,boyd ,dawkins attempts to reduce the difficulty by supposing that the ,glacial epoch was marked by the occurrence of minor periods of climatic variation1 during which1 in comparatively short periods1 the isothermal lines vibrated from north to south1 and vice versa4 ,in this view the southern species gradually crowded upon the northern during the periods of climatic amelioration1 until they reached their limit in central ,england1 and then in turn1 as the climate became more rigorous1 slowly retreated before the pressure of their northern competitors4 ,meanwhile the hyena sallied forth from his various caves1 over this region1 at one time of the year to feed upon the reindeer1 and at another time of the year upon the flesh of the hippopotamus1 in both cases dragging their bones with him to his sheltered retreat in the limestone caverns,,dn which he shared at intervals with palolithic man4 ,footnote ,,dn3 ,early ,man in ,britain1 p4 #aad4 ,the theory of ,mr4 ,james ,geikie is that the period1 while one of great precipitation1 was characterised by a climate of comparatively even temperature1 in which there was not so great a difference as now between the winters and the summers1 the winters not being so cold and the summers not so hot as at present4 ,this is substantially the condition of things in southern ,alaska at the present time1 where extensive glaciers come down to the sea-level1 even though the thermometer at ,sitka rarely goes below zero 7,fahrenheit74 ,it is1 therefore1 easy to conceive that if there were extensive plains bordering the ,alaskan archipelago1 so as to furnish ranging grounds for more southern species1 the animals of the north and the animals of the south might partially occupy the same belt of territory1 and their bones become mingled in the same river deposits4 ,in order to clear the way for either of these hypotheses to account for the mingling of arctic and torrid species characteristic of the period under consideration in ,europe1 we must probably suppose such an elevation of the region to the south as to afford land connection between ,europe and ,africa4 ,this would be furnished by only a moderate amount of elevation across the ,strait of ,gibraltar and from the south of ,italy to the opposite shore in ,africa2 and there are many indications1 in the distribution of species1 of the existence in late geological times of such connection4 ,it should also be observed that the present capacities and habits of species are not a certain criterion of their past habits and capacities4 ,as already remarked1 both the rhinoceros and the mammoth of glacial times were probably furnished with a woolly protection1 which enabled them to endure more cold than their present descendants could do1 while the elephant is even now known to be able to endure the rigors of the climate at great elevations upon the ,himalaya ,mountains4 ,we can easily imagine these species to have been adjusted to quite different climatic conditions from those which now seem necessary to their existence4 ,in the case of the hippopotamus1 also1 it is quite possible1 as already suggested1 that it is more inclined to migration than is generally supposed4 ,geikie's theory of the prevalence of an equable climate during a portion of the ,glacial period in ,europe is thought to be further sustained by the character of the vegetation which then covered the region1 as well as by the remains of the mollusks which occupied the waters4 ,then temperate and southern species like the ash1 the poplar1 the sycamore1 the fig-tree1 the ,judas-tree1 the laurel1 etc41 overspread all the low ground of ,france1 as far north at least as ,paris4444 ,it was under such conditions1 continues ,geikie1 that the elephants1 rhinoceroses1 and hippopotamuses1 and the vast herds of temperate cervine and bovine species ranged over ,europe1 from the shores of the ,mediterranean up to the latitude of ,yorkshire1 and probably even farther north still2 and from the borders of ,asia to the ,western ,ocean4 ,despite the presence of numerous fierce carnivora--lions1 hyenas1 tigers1 and others--,europe at that time1 with its shady forests1 its laurel-margined streams1 its broad and deep-flowing rivers1 a country in every way suited to the needs of a race of hunters and fishers--must have been no unpleasant habitation for palolithic man4 ,this1 however1 is only one side of the picture4 ,there was a time when the climate of ,pleistocene ,europe presented the strongest contrast to those genial conditions--a time when the dwarf birch of the ,scottish ,highlands1 and the arctic willow1 with their northern congeners1 grew upon the low grounds of middle ,europe4 ,arctic animals1 such as the musk sheep and the reindeer1 lived then1 all the year round1 in the south of ,france2 the mammoth ranged into ,spain and ,italy2 the glutton descended to the shores of the ,mediterranean2 the marmot came down to the low grounds at the foot of the ,apennines2 and the lagomys inhabited the low-lying maritime districts of ,corsica and ,sardinia4 ,the land and fresh-water shells of many ,pleistocene deposits tell a similar tale2 boreal1 high alpine1 and hyperborean forms are characteristic of these accumulations in central ,europe2 even in the southern regions of our continent the shells testify to a former colder and wetter climate4,,do ,footnote ,,do3 ,prehistoric ,europe1 p4 #fg4 ,in ,mr4 ,geikie's view these facts indicate two ,glacial periods1 with an intervening epoch of mild climate4 ,in the opinion of others they are readily explainable by the coming on and departure of a single ,ice age1 with its various minor episodes4 ,earliest ,remains of ,man on the ,pacific ,coast of ,north ,america4 ,most interesting evidence concerning the antiquity of man in ,america1 and his relation to the ,glacial period1 has come from the ,pacific coast4 ,during the height of the mining activity in ,california1 from #ahej to #ahfj1 numerous reports were rife that human remains had been discovered in the gold-bearing gravel upon the flanks of the ,sierra ,nevada ,mountains4 ,these reports did not attract much scientific attention until they came to relate to the gravel deposits found deeply buried beneath a flow of lava locally known as the ,sonora or ,tuolumne ,table ,mountain4 ,this lava issued from a vent near the summit of the mountain-range1 and flowed down the valley of the ,stanislaus ,river for a distance of fifty or sixty miles1 burying everything in the valley beneath it1 and compelling the river to seek another channel4 ,the thickness of the lava averages about one hundred feet1 and so long a time has elapsed since the eruption that the softer strata on either side of the valley down which it flowed have been worn away to such an extent that the lava now rises nearly everywhere above the general level1 and has become a striking feature in the landscape1 stretching for many miles as a flat-topped ridge about half a mile in width1 and presenting upon the sides a perpendicular face of solid basalt for a considerable distance near the lower end of the flow4 ,illustration3 ,fig4 #id4--,section across ,table ,mountain1 ,tuolumne ,county1 ,california3 ,l1 lava2 ,g1 gravel2 ,s1 slate2 ,r1 old river-bed2 ,r'1 present river-bed4 ,illustration3 ,fig4 #ie4--;,calaveras ,skull4 7,from ,whitney47 ,it was under this mountain of lava that the numerous implements and remains of man occurred which were reported to ,professor ,j4 ,d4 ,whitney when he was conducting the geological survey of ,california between #ahfj and #ahgj4 ,the implements consisted of stone mortars and pestles1 suitable for use in grinding acorns and other coarse articles of food4 ,there were1 however1 some rude articles of ornament4 ,in one of the mining shafts penetrating the gravel underneath ,table ,mountain1 near ,sonora1 there was reported to have been discovered1 in #aheg1 a human jawbone1 one portion of which was sent by responsible parties to the ,boston ,society of ,natural ,history1 and another part to the ,philadelphia ,academy of ,sciences1 in whose collections the fragments can now be seen4 ,interest reached a still higher pitch when1 in #ahfj1 an entire human skull with some other human bones was reported to have been discovered under this same lava deposit1 a few miles from ,sonora1 at ,altaville1 in ,calaveras ,county1 and hence known as the ,calaveras skull4 ,persistent efforts were made soon after to discredit the genuineness of this discovery4 ,bret ,harte showered upon it the shafts of his ridicule1 and various other persons gave currency to the story that the whole report originated in a joke played by the miners upon unsuspecting geologists4 ,these attacks were so successful that many conservative archologists and men of science have refused to accept the skull as genuine4 ,recent events1 however1 have brought such additional evidence,,dp to the support of this discovery that it would seem unreasonable any longer to refuse to credit the testimony4 ,at the meeting of the ,geological ,society of ,america1 at ,washington1 in ,january1 #ahia1 ,mr4 ,george ,p4 ,becker1 of the ,united ,states ,geological ,survey1 who for some years has had charge of investigations relating to the gold-bearing gravels of the ,pacific coast1 presented the affidavit of ,mr4 ,j4 ,h4 ,neale1 a well-known mining engineer of unquestionable character1 stating that he had taken a stone mortar and pestle1 together with some spear-heads 7which through ,mr4 ,becker he presented to the ,society71 from undisturbed strata of gravel underneath the lava of ,table ,mountain1 near ,rawhide ,gulch1 a few miles from ,sonora4 ,at the same meeting ,mr4 ,becker presented a pestle which ,mr4 ,clarence ,king1 the first director of the ,united ,states ,geological ,survey1 took with his own hands out of undisturbed gravel under this same lava deposit1 near ,tuttletown1 a mile or two from the preceding locality mentioned4 ,footnote ,,dp3 ,see ,bulletin ,geological ,society of ,america1 #ahia1 pp4 #ahi-bjj4 ,i was so fortunate1 also1 as to be able to report to the ,society at the same meeting the discovery1 in #ahhg1 of a small stone mortar by ,mr4 ,c4 ,mc,tarnahan1 the assistant surveyor of ,tuolumne ,county4 ,this mortar was found by ,mr4 ,mc,tarnahan in the ,empire mine1 which penetrates the gravel underneath ,table ,mountain1 about three miles from ,sonora1 and not far from the other localities above mentioned4 ,the place where the mortar was found is about one hundred and seventy-five feet in from the edge of the superincumbent lava1 which is here about one hundred feet in thickness4 ,at my request1 this mortar was presented by its owner1 ,mrs4 ,m4 ,j4 ,darwin1 to the ,western ,reserve ,historical ,society of ,cleveland1 ,ohio1 in whose collection it can now be seen4 ,these three independent instances1 each of them authenticated by the best of evidence1 have such cumulative force that probably few men of science will longer stand out against it4 ,associated with these discoveries1 there is to be mentioned another1 which was brought to my notice by ,mr4 ,charles ,francis ,adams in ,october1 #ahhi4;,,dq ,this was a miniature clay image of a female form1 about one inch and a half in length1 and beautifully formed1 which was found1 in ,august1 #ahhi1 by ,mr4 ,m4 ,a4 ,kurtz1 while boring an artesian well at ,nampa1 ,ada ,county1 ,idaho4 ,the strata passed through included1 near the surface1 fifteen feet of lava4 ,underneath this1 alternating beds of clay and quicksand occurred to a depth of three hundred and twenty feet1 where there appeared indications of a former surface soil lying just above the bed-rock1 from which the clay image was brought up in the sand-pump4 ,footnote ,,dq3 ,see ,proceedings ,boston ,society ,natural ,history1 ,january1 #ahij1 and ,february1 #ahia4 ,illustration3 ,fig4 #if4--,three views of ,nampa image drawn to scale4 ,the middle one is from a photograph4 ,i devoted the summer of #ahij to a careful study of the lava deposits both in ,idaho and in ,california1 with a view to learning their significance with reference to these discoveries4 ,the main facts brought to light by this investigation are that in the ,snake ,river ,valley1 ,idaho1 there are not far from twelve thousand square miles of territory covered with a continuous stratum of basaltic lava1 extending nearly across the entire diameter of the ,state from east to west4 ,nampa1 where the miniature image was discovered1 is within five miles of the western limit of this lava-flow1 and where it had greatly thinned out4 ,the relative age of the lava is shown by its relation to ,tertiary beds of shale and sandstone1 containing numerous fossils of late ,pliocene species4 ,these are overlaid in this vicinity by the lava1 thus determining its post-,tertiary character4 ,examination with reference to the more precise determination of age reveals channels of erosion formed since the lava-flow took place1 which1 when studied sufficiently1 will probably lead to valuable approximate results4 ,at present ,i can only say that the amount of erosion since the lava eruptions of western ,idaho is not excessive1 and very likely may be brought within a period of from ten thousand to twenty thousand years4 ,the enormous erosion in the caon of the ,snake ,river1 near ,shoshone ,falls1 in central ,idaho1 is doubtless of a much earlier date than that in the ,boise ,river1 near ,nampa4 ,illustration3 ,fig4 #ig4--,map showing ,pocatello1 ,nampa1 and the valley of ,snake ,river4 ,the disturbances created in this part of the valley by the bursting of the barriers between the glacial ,lake ,bonneville and the ,snake ,river1 already described 7see above1 page #bcc71 have not been worked out4 ,there can be no doubt1 however1 that interesting results will come to light in connection with the problem2 for ,pocatello1 the point at which the dbcle reached the ,snake ,river plain1 is about #b1jjj feet higher than ,nampa1 and #cej miles distant1 and the water must have poured into the valley faster than the river in its upper portion could have discharged it4 ,by just what channels the mighty current worked down to the lower levels on the western borders of the ,state it would be most interesting as well as instructive to know4 ,a study of the situation in ,tuolumne and ,calaveras ,counties1 ,california1 reveals a state of things closely resembling1 in important respects1 that in western ,idaho4 ,at first sight the impression is made that an immense lapse of time must have occurred since the volcanic eruption which furnished the lava of ,table ,mountain4 ,the ,stanislaus ,river flows in a channel of erosion a thousand feet or more lower than the ancient channel filled by lava1 and in two or three places cuts directly across it4 ,an immense amount of time1 also1 would seem to be required to permit the smaller local streams to have worn away so much of the sides of the ancient valley as to allow the lava deposit now so continuously to rise above the general surface4 ,still1 the question of absolute time cannot be considered separately without much further study4 ,it is by no means certain that1 when the lava-stream poured down the mountain1 it always followed the lowest depressions2 but at certain points it may have been dammed up in its course by its own accumulations so as to be turned off into what was then an ancient abandoned channel4 ,illustration3 ,fig4 #ih4--,section along the line1 north and south3 r' r'1 old river-beds2 r r1 present river-beds2 ,l1 lava2 sl1 slate4 ,the forms of animal and vegetable life with which the remains of man under ,table ,mountain are associated1 are1 indeed1 to a considerable extent1 species now extinct in ,california1 and some of them no longer exist anywhere in the world4 ,but a suggestion of ,professor ,prestwich1 in ,england1 made with reference to the extinct forms of life associated with human remains in the glacial deposits in ,europe1 is revived by ,mr4 ,becker1 of the ,geological ,survey1 with reference to the ,california discoveries2 his inference being1 not that man is so extremely ancient in ,california1 but that many of these plants and animals have continued to a more recent date than has ordinarily been supposed4 ,the connection of these lava-flows on the ,pacific coast with the ,glacial period is unquestionably close4 ,for some reason which we do not fully understand1 the vast accumulation of ice in ,north ,america during the ,glacial period is correlated with enormous eruptions of lava west of the ,rocky ,mountains1 and1 in connection with these events1 there took place on the ,pacific coast an almost entire change in the plants and animals occupying the region4 ,mr4 ,warren ,upham is of the opinion that on the ,pacific coast they lingered much later than in the region east of the ,rocky ,mountains4 ,indeed1 it is pretty certain that not many centuries have elapsed since the glacial phenomena of the ,sierra ,nevada ,mountains were much more pronounced than they are at the present time1 and it is equally certain that there have been vast eruptions of lava in ,california within three hundred years4 ,from these data1 therefore1 ,mr4 ,becker has real foundation for his suggestion that perhaps in the ,glacial period ,california was a kind of health resort for ,pliocene animals1 as it is at the present time for man2 or1 at any rate1 that the later date of the accumulations permitted the animals to survive there much longer than in the region east of the ,rocky ,mountains4 ,further discussion of the preceding facts will profitably be deferred until1 in the next two chapters1 the questions of the cause and date of the ,glacial period have been considered4 ,,chapter ,,ix4 ,,the ,,cause ,,of ,,the ,,glacial ,,period4 ,in searching for the cause of the ,glacial period1 it is evident that we must endeavor to find conditions which will secure over the centre of the glaciated area either a great increase of snow-fall or a great decrease in the mean annual temperature1 or both of these conditions combined in greater or less degree4 ,as can be seen1 both from the nature of the case and from the unglaciated condition of ,siberia and northern ,alaska1 a low degree of temperature is not sufficient to produce permanent ice-fields4 ,if the snow-fall is excessively meagre1 even the small amount of heat in an arctic summer will be sufficient to melt it all away4 ,from the condition of ,greenland1 however1 it appears that a moderate amount of precipitation where it is chiefly in the form of snow may produce enormous glaciers if at the same time the average temperature is low4 ,in southeastern ,alaska1 on the other hand1 the glaciers are of enormous size1 though the mean annual temperature is by no means low1 for there the great amount of snow-fall amply compensates for the higher temperature4 ,snow stores the cold and keeps it in a definite place4 ,if the air becomes chilled1 circulation at once sets in1 and the cold air is transferred to warmer regions2 but if there is moisture in the air1 so that snow forms1 the cold becomes locked up1 as it were1 and falls to the earth4 ,the amount of cold thus locked up in snow is enormous4 ,to melt one cubic foot of ice requires as much heat as would raise the temperature of a cubic foot of water #agf ,fahrenheit4 ,to melt a layer of ice only one inch and a half thick would require as much heat as would raise a stratum of air eight hundred feet thick from the freezing-point to the tropical heat of #hh ,fahrenheit4 ,it is the slowness with which ice melts which enables it to accumulate as it does1 both in winter and upon high mountains and in arctic regions4 ,captain ,scoresby relates that when near the north pole the sun would sometimes be so hot as to melt the pitch on the south side of his vessel1 while water was freezing on the north side1 in the shade1 owing to the cooling effect of the masses of ice with which he was surrounded4 ,thus it will appear that a change in the direction of the moist winds blowing from the equator towards the poles might produce a ,glacial epoch4 ,if snow falls upon the ocean it cools the water1 but through the currents1 everywhere visible in the sea1 the temperature in the water in the different parts soon becomes equalized4 ,if1 however1 the snow falls upon the land1 it must be melted by the direct action of the sun and wind upon the spot where it is4 ,if the heat furnished by these agencies is not sufficient to do it year by year1 there will soon be such an accumulation that glaciers will begin to form4 ,it is clear1 therefore1 that the conditions producing a ,glacial period are likely to prove very complicated1 and we need not be surprised if the conclusions to which we come are incapable of demonstration4 ,theories respecting the cause of the ,glacial period may be roughly classified as astronomical and geological4 ,among the astronomical theories1 one which has sometimes been adduced is that the solar system in its movement through space is subjected to different degrees of heat at different times4 ,according to this theory1 the temperate climate which characterised the polar regions during the ,tertiary period1 and continued up to the beginning of the ,glacial epoch1 was produced by the influence of the warmer stretches of space through which the whole solar system was moving at that time2 while the ,glacial period resulted from the influence upon the earth of the colder spaces through which the system subsequently moved4 ,while it is impossible absolutely to disprove this hypothesis1 it labors under the difficulty of having little positive evidence in its favor1 and thus contravenes a fundamental law of scientific reasoning1 that we must have a real cause upon which to rest our theories4 ,in endeavouring to explain the unknown1 we should have something known to start with4 ,but in this case we are not sure that there are any such variations in the temperature of the space through which the solar system moves4 ,this theory1 therefore1 cannot come in for serious consideration until all others have been absolutely disproved4 ,as we shall also more fully see1 in the subsequent discussion1 the distribution of the ice during the ,glacial period was not such as to indicate a gradual extension of it from the north pole1 but rather the accumulation upon centres many degrees to the south4 ,closely allied with the preceding theory is the supposition broached by some astronomers that the sun is a variable star1 dependent to some extent for its heat upon the impact of meteorites1 or to the varying rapidity with which the contraction of its volume is proceeding4 ,it is well known that when two solid bodies clash together1 heat is produced proportionate to the momentum of the two bodies4 ,in other words1 the motion which is arrested is transformed into heat4 ,mr4 ,croll1 in his last publication,,dr upon the subject1 ingeniously attempted to account for the gaseous condition of the nebul and the heat of the sun and other fixed stars by supposing it to be simply transformed motion4 ,according to this theory1 the original form of force imparted to the universe was that exerted in setting in motion innumerable dark bodies1 which from time to time have collided with each other4 ,the effects of such collisions would be to transform a large amount of motion into heat and its accompanying forms of molecular force4 ,the violence of the compact of two worlds would be so great as to break them up into the original atoms of which they are composed1 and the heat set free would be sufficient to keep the masses in a gaseous condition and cause them to swell out into enormous proportions4 ,from that time on1 as the heat radiated into space1 there would be the gradual contraction which we suppose is going on in all the central suns1 accompanied1 of course1 with a gradual decline of the heat-energy in the system4 ,footnote ,,dr3 ,stellar ,evolution and its ,relation to ,geological ,time4 ,now1 it is well known that the earth and the solar system in their onward progress pass through trains of meteorites4 ,the tails of some of the comets are indeed pretty clearly proved to be streams of ponderable matter1 through which1 from time to time1 the minor members of the solar system plunge1 and receive some accession to their bulk and weight4 ,the shooting-stars1 which occasionally attract our attention in the sky1 mark the course of such meteorites as they pass through the earth's atmosphere1 and are heated to a glow by the friction with it4 ,it has been suggested1 therefore1 that the sun itself may at times have its amount of heat sensibly affected by such showers of meteorites or asteroids4 ,upon this theory the warm period of the ,tertiary epoch1 for instance1 may have been due to the heat temporarily added to the sun by impact with minor astronomical bodies4 ,when1 afterwards1 it gradually cooled down1 receiving through a long period no more accessions of heat from that source1 the way was prepared for the colder epoch of the ,glacial period1 which1 in turn1 was dispelled by fresh showers of meteorites upon the sun1 sufficient to produce the amelioration of climate which we experience at the present time4 ,as intimated1 this theory is closely allied to the preceding1 the principal difference being that it limits the effects of the supposed cause to the solar system1 and looks to our sun as the varying source of heat-supply4 ,it has the advantage over that1 however1 of possessing a more tangible vera causa4 ,meteorites1 asteroids1 and comets are known to be within this system1 and have occasional collisions with other members of it4 ,but the principal objection urged against the preceding theory applies here1 also1 with equal force4 ,the accumulations of ice during the ,glacial period were not determined by latitude4 ,in ,north ,america the centre of accumulation was south of the ,arctic ,circle--a fact which points clearly enough to some other cause than that of a general lowering of the temperature exterior to the earth4 ,the same objections would bear against the theory ably set forth by ,mr4 ,sereno ,e4 ,bishop1 of ,honolulu1 which1 in substance1 is that there may be considerable variability in the sun's emission of heat1 owing to fluctuations in the rate of the shrinkage of its diameter1 brought about by the unequal struggle between the diminishing amount of heat in the interior and the increasing force of the gravitation of its particles1 and by the changes in the enveloping atmosphere of the sun1 which1 like an enswathing blanket1 arrests a large portion of the radiant heat from the nucleus1 and is itself evidently subject to violent movements1 some of which seem to carry it down to the sun's interior4 ,unknown electrical forces1 he thinks1 may also combine to add an element of variability4 ,these supposed changes may be compared to those which take place upon the surface of the earth when1 at irregular intervals1 immense sheets of lava1 like those upon the ,pacific coast of ,north ,america1 are exuded in a comparatively brief time1 to be succeeded by a long period of rest4 ,the heat thus brought to the surface of the earth would add perceptibly to that radiated from it into space in ordinary times4 ,something similar to this upon the sun1 it is thought1 might produce effects perceptible upon the earth1 and account for alternate periods of heat and cold4 ,a fourth astronomical theory is that there has been a shifting of the earth's axis2 that at the time of the ,glacial period the north pole1 instead of being where it now is1 was somewhere in the region of central ,greenland4 ,this attractive theory has been thought worthy of attention by ,president ,t4 ,c4 ,chamberlin and by ,professor ,g4 ,c4 ,comstock1,,ds but it likewise labours under a twofold difficulty3 ,first1 the shifting of the poles observed 7#dej feet per year7 is too slight to have produced the changes within any reasonable time1 and it is not likely to have been continuous for a long period4 ,but still more fatal to the theory is the fact that the warm climate preceding the ,glacial period seems to have extended towards the present north pole upon every side2 a temperate flora having been found in the fossil plants of the ,tertiary beds in ,greenland and northern ,british ,america1 as well as upon ,nova ,zembla and ,spitzbergen4 ,footnote ,,ds3 ,see papers by these gentlemen read at the meeting of the ,american ,association for the ,advancement of ,science1 in ,washington1 in ,august1 #ahia4 ,professor ,comstock's paper appeared in the ,american ,journal of ,science for ,january1 #ahic4 ,a fifth astronomical theory1 and one which has of late years been received with great favour1 is that so ably advocated by the late ,dr4 ,james ,croll and by ,professor ,james ,geikie4 ,following the suggestions of the astronomer ,adhmar1 these writers have attempted to show that not only one ,glacial epoch1 but a succession of such epochs1 has been produced in the world by the effect of the changes which are known to have taken place in the eccentricity of the earth's orbit when combined with the precession of the equinoxes--another calculable astronomical cause4 ,illustration3 ,fig4 #ii4--;,diagram showing effect of precession3 ,a4 condition of things now2 ,b4 as it will be #aj1ejj years hence4 ,the eccentricity is of course greatly exaggerated4 ,it is well known that the earth's orbit is elliptical2 that is1 it is longer in one direction than in the other1 so that the sun is one side of the centre4 ,during the winter of the northern hemisphere the earth is now about three million miles nearer the sun than in the summer2 but the summer makes up for this distance by being about seven days longer than the winter4 ,through the precession of the equinoxes this state of things will be reversed in ten thousand five hundred years2 at which time we shall be nearer the sun during our northern summer1 and farther away in winter1 our winter then being also longer than our summer4 ,besides1 through the unequal attraction of the planets the eccentricity of the earth's orbit periodically increases and diminishes1 so that there have been periods when the earth was ten million five hundred thousand miles farther from the sun in winter than in summer2 at which times1 also1 the winter was nearly twenty-eight days longer than the summer4 ,such an extreme elongation of the earth's orbit occurred about two hundred and fifty thousand years ago4 ,it is easy to assume that such a change in astronomical conditions would produce great effects upon the earth's climate2 and equally easy to connect with those effects the vast extension of ice during the ,glacial period4 ,since1 also1 this period of extreme eccentricity terminated only eighty thousand years ago1 the close of the ,glacial period would1 perhaps1 upon ,mr4 ,croll's theory1 be comparatively a recent event2 for if the secular summer of the earth's eccentricity lags relatively as far behind the secular movements as the annual summer does behind the vernal equinox1 we should1 as ,professor ,charles ,h4 ,hitchcock suggests1 have to place the complete breaking up of the ,ice period as late as forty thousand years ago4,,dt ,footnote ,,dt3 ,geology of ,new ,hampshire1 vol4 iii1 p4#cbg4 ,we have no space to indicate1 as it deserves1 the comparative merits and demerits of this ingenious theory4 ,it would1 however1 be a great calamity to have geologists accept it without scrutiny4 ,it is1 indeed1 a part of the business of geologists to doubt such theories until they are verified by a thorough examination of all accessible terrestrial evidence bearing upon the subject4 ,there is no reason to question the reality of the variations in the relative positions of the earth and the sun assumed by ,mr4 ,croll2 though there may be serious doubt whether the effects of those changes upon climate would be all that is surmised1 since equal amounts of heat would fall upon the earth during summer1 whether made longer or shorter by the cause referred to4 ,during the short summers the earth is so much nearer the sun that it receives each season absolutely as much heat as it does during the longer summers1 when it is so much farther away from the sun4 ,thus the theory rests at last upon the question what would become of the heat reaching the earth in these differing conditions4 ,it is plausibly urged by ,mr4 ,croll that when a hemisphere of the earth is passing through a period of long winters the radiation of heat will be so excessive that the temperature would fall much below what it would during the shorter winters2 and so ice and snow would accumulate far beyond the usual amount4 ,it is also supposed that the effect of the summer's sun in melting the ice during the short summer would be diminished through natural increase of the amount of foggy and cloudy weather4 ,adhmar's theory is supposed by ,sir ,robert ,ball1 ,royal ,astronomer of ,ireland1 to be considerably re-enforced by a discovery which he has made concerning the distribution of heat upon the earth during the seasons culminating in the summer and winter solstices4 ,croll had assumed1 on the authority of ,herschel1 that a hemisphere of the earth during the longer winter in aphelion would receive the same actual amount of heat which would fall upon it during the shorter summer in perihelion2 whereas1 according to ,dr4 ,ball's discovery1 of the total amount of heat received from the sun on a hemisphere of the earth in the course of a year1 sixty-three per cent is received during the summer and thirty-seven per cent during the winter4,,du ,when1 therefore1 the summers occur in perihelion the heat is more intense than ,croll had supposed1 and1 at the same time1 the winters occurring in aphelion are more deficient in heat than he had assumed4 ,this discovery of ,dr4 ,ball will not1 however1 materially affect the discussion of ,croll's theory upon its inherent merits1 since it is simply an intensification of the causes invoked by him4 ,we will therefore let it stand or fall in the light of the general considerations hereafter to be adduced4 ,footnote ,,du3 ,cause of an ,ice ,age1 p4 #ij4 ,the aid of theoretical consequent changes in the volume of the ,gulf ,stream1 and in the area of the trade-winds1 has also to be invoked by ,mr4 ,croll4 ,the theory likewise receives supposed confirmation from facts alleged concerning the present climate of the southern hemisphere which is passing through the astronomical conditions thought to be favourable to its glaciation4 ,the antarctic continent is completely enveloped in ice1 even down to the sixty-seventh degree of latitude4 ,a few degrees nearer the pole ,sir ,j4 ,c4 ,boss describes the ice as rising from the water in a precipitous wall one hundred and eighty feet high4 ,in front of such a wall1 and nearly twenty degrees from the south pole1 this navigator sailed four hundred and fifty miles6 ,voyagers1 in general1 are said to agree that the summers of the antarctic zone are much more foggy and cold than they are in corresponding latitudes in the northern hemisphere2 and this1 even though the sun is #c1jjj1jjj miles nearer the earth during the southern summer than it is during the northern4 ,another direction from which evidence is invoked in confirmation of ,mr4 ,croll's theory is the geological indications of successive ,glacial epochs in times past4 ,if there be a recurring astronomical cause sufficient of itself to produce ,glacial periods1 such periods should recur as often as the cause exists2 but glaciation upon the scale of that which immediately preceded the historic era could hardly have occurred in early geological time without leaving marks which geologists would have discovered4 ,were the till now covering the glaciated region to be converted into rock1 its character would be unmistakable1 and the deposit is so extensive that it could not escape notice4 ,in his inaugural address before the ,british ,association in #ahhj1 ,professor ,ramsey1 ,director-,general of the ,geological ,survey of ,great ,britain1 presented a formidable list of glacial observations in connection with rocks of a remote age4,,dv ,beginning at the earliest date1 he cites ,professor ,archibald ,geikie1 one of the most competent judges1 as confident that the rounded knobs and knolls of ,laurentian rocks exposed over a large region in northwestern ,scotland1 together with vast beds of coarse1 angular1 unstratified conglomerates1 are unquestionable evidences of glacial action at that early period4 ,masses of similar conglomerates1 resembling consolidated glacial boulder-beds1 occur also in the ,lower ,silurian formation at ,corswall1 ,england4 ,in ,dunbar1 ,scotland1 ,professor ,forbes also found1 in formations of but little later age than the ,coal period1 brecciated conglomerates1 consisting of pebbles and large blocks of stone1 generally angular1 embedded in a marly paste1 in which some of the pebbles are as well scratched as those found in medial moraines4 ,in formations of corresponding antiquity the geologists of ,india have found similar boulder-beds1 in which some of the blocks are polished and striated4 ,footnote ,,dv3 ,nature 7,august #bf1 #ahhj71 vol4 xxii1 pp4 #chh1 #chi4 ,still1 this evidence is less abundant than we should expect1 if there had been the repeated ,glacial epochs supposed by ,mr4 ,croll's astronomical theory2 and it is by no means impossible that the conglomerates of scratched stones described by ,professor ,ramsey in ,great ,britain1 and by ,messrs4 ,blandford and ,medlicott in ,india1 may have resulted from local glaciers coming down from mountain-chains which have been since removed by erosion or subsidence4 ,we are not aware that any incontestable evidence has been presented in ,america of any glaciation previous to that of the ,glacial period4 ,upon close consideration1 also1 it appears that ,mr4 ,croll's theory has not properly taken into account the anomalous distribution of heat which we actually find to take place on the surface of the earth4 ,he has done good service in showing what an enormous transfer of heat there is from the southern to the northern ,atlantic by means of the ,gulf ,stream1 estimating that the heat conveyed by the ,gulf ,stream into the ,atlantic ,ocean is equal to one fifth of all possessed by the waters of the ,north ,atlantic2 or to the heat received from the sun upon a million and a half square miles at the equator1 or two million square miles in the temperate zone4 ,the stoppage of the ,gulf ,stream would deprive the ,atlantic of #gg1dgi1fej1jjj1jjj1jjj1jjj foot-pounds of energy in the form of heat per day4 ,among the objections which bear against this ingenious theory is one which will appear with great force when we come to discuss the date of the ,glacial period1 when we shall show that even ,professor ,hitchcock's supposition that the lingering effects of the last great eccentricity of the earth's orbit1 continued down to forty thousand years ago1 is not sufficient to account for the recentness of the close of the period as shown by abundant geological evidence4 ,it is certainly not more than ten or fifteen thousand years ago that the ice finally melted off from the ,laurentian highlands2 while on the ,pacific coast the period of glaciation was still more recent4 ,from inspection of the accompanying map the main point of ,mr4 ,croll's reasoning may be understood4 ,it will be seen that the direction of the currents in the central ,atlantic is largely determined by the contour of the northeastern coast of ,south ,america4 ,from some cause the southeast trade-winds are stronger than the northeast1 and their force is felt in pushing the superficial currents of warm water farther north than ,cape ,st4 ,roque1 the eastern extremity of ,brazil4 ,as the direction of the ,south ,american coast trends rapidly westward from this point to the ,isthmus of ,panama1 the resultant of the forces is a strong current northwestward into the cul-de-sac of the ,gulf of ,mexico1 from which there is only the one outlet between ,cuba and the peninsula of ,florida4 ,through this the warm water is forced into the region where westerly winds prevail1 and spreads its genial influence far to the northward1 modifying the climate of the ,british ,isles1 and even of far-off ,norway4 ,illustration3 ,fig4 #ajj4--,map showing course of currents in the ,atlantic ,ocean3 b and b' are currents set in motion by opposite trade-winds2 meeting1 they produce the equatorial current1 which divides into c and c'1 continuing on as a and a' and e4 ,but why are the southeast trade-winds of the ,atlantic stronger than the northeast8 ,the ultimate reason1 of course1 is to be found in the fact that the northern hemisphere is warmer than the southern4 ,the atmosphere over the northern-central portion of the ,atlantic region is more thoroughly rarefied by the sun's heat than is that over the region south of the equator4 ,the strong southeast trades are simply the rush of atmosphere from the ,south ,atlantic to fill the vacuum caused by the heat of the sun north of the equator4 ,but1 again1 why is this8 ,because1 says ,mr4 ,croll1 we are now in that stage of astronomical development favourable to the increased warmth of the northern hemisphere4 ,in the northern hemisphere the summers are longer than the winters4 ,perihelion occurs in winter and aphelion in summer4 ,this is the reason why the ,north ,atlantic is warmer than the ,south ,atlantic1 and why the trade-winds of the south are drawn to the north of the equator4 ,ten thousand five hundred years ago1 however1 the conditions were reversed1 and the greater rarefaction of the atmosphere would have taken place south of the equator1 thus drawing the trade-winds in that direction4 ,by again inspecting the map1 one will see how far-reaching the effect on the climate of northern countries this change in the prevalences of the trades would have been4 ,then1 instead of having the northwest current leading along the northeast coast of ,south ,america into the ,gulf of ,mexico augmented by the warm currents circulating south of the equator1 the warm currents of the north would have been pushed down so far that they would augment the current running to the southwest beyond ,cape ,st4 ,roque1 along the southeast shore of ,south ,america2 thus the northern portion of the ,atlantic1 instead of robbing the southern portion of heat1 would itself be robbed of its warm currents to contribute to the superfluous heat of the ,south ,atlantic4 ,this theory is certainly very ingenious4 ,there is a weak point in it1 however4 ,mr4 ,croll assumes that when the winters of the northern hemisphere occur in aphelion1 they must necessarily be colder than now4 ,but1 evidently1 this assertion implies a fuller knowledge than we possess of the laws by which the heat received from the sun is distributed over the earth4 ,for it appears from observation that the equator is by no means so hot now as1 theoretically1 it ought to be1 and that the arctic regions are not so cold as1 according to theory1 they should be1 and this in places which could not be affected by oceanic currents4 ,for example1 at ,iquitos1 on the ,amazon1 only three hundred feet above tide1 three degrees and a half south of the equator1 and more than a thousand miles from the ,atlantic 7so that ocean-currents cannot abstract the heat from its vicinity71 the mean yearly temperature is but #gh ,fahr42 while at ,verkhojansk1 in northeast ,siberia1 which is #fg north of the equator1 and is situated where it is out of the reach of ocean-currents1 and where the conditions for the radiation of heat are most favourable1 and where1 indeed1 the winter is the coldest on the globe 7,january averaging--#ef ,fahr471 the mean yearly temperature is two degrees and a half above zero2 so that the difference between the temperature upon the equator and that at the coldest point on the sixty-seventh parallel is only about #ge ,fahr42 whereas1 if temperature were in proportion to heat received from the sun1 the difference ought to be #agb4 ,again1 the difference between the actual ,january temperature on the fiftieth parallel and that upon the sixtieth is but #bj ,fahr41 whereas1 the quantity of solar heat received on the fiftieth parallel during the month of ,january is three times that received upon the sixtieth1 and the difference in temperature ought to be about #agj ,fahr4 upon any known law in the case4 ,woeikoff1 a ,russian meteorologist1 and one of the ablest critics of ,mr4 ,croll's theory1 and to whom we are indebted for these facts1 ascribes the greater present warmth of the northern ,atlantic basin1 not to the astronomical cause invoked by ,mr4 ,croll1 but to the relatively small extent of sea in the middle latitudes of the northern hemisphere4 ,the extent and depth of the oceans of the southern hemisphere would of themselves give greater steadiness and force to its trade-winds1 and lead to a general lowering of the temperature2 so that it is doubtful if the astronomical causes introduced by ,mr4 ,croll1 even with ,dr4 ,ball's re-enforcement1 would produce any appreciable effect while the distribution of land and water remains substantially what it is at the present time4 ,still another variation in the astronomical theory has been set forth and defended by ,major-,general ,a4 ,w4 ,drayson1 ,f4 ,r4 ,a4 ,s41 instructor in the ,royal ,military ,school at ,woolwich1 ,england4 ,he contends that what has been called the precession of the equinoxes1 and supposed to be a conical movement of the earth's axis in a circle around a point as a centre1 from which it continually decreases its distance1,,dw is really a second rotation of the earth about its centre4 ,as a consequence of this second rotation1 he endeavours to show that the inclination of the earth's axis varies as much as #ab2 so that1 whereas the ,arctic and ,antarctic ,circles and the tropics extend to only about #bc from the poles and the equator1 respectively1 about thirteen thousand five hundred years ago they extended more than #ce2 thus bringing the frigid zones in both cases #ab nearer the equator than now4 ,this1 he contends1 would have produced the ,glacial period at the time now more generally assigned to it by direct geological evidence4 ,footnote ,,dw3 ,untrodden ,ground in ,astronomy and ,geology1 p4 #bf4 ,the difficulty with this theory1 even if the mathematical calculations upon which it is based are correct1 would be substantially the same as those already urged against that of ,mr4 ,croll4 ,it is specially difficult to see how ,general ,drayson would account for the prolonged temperate climate in high northern latitudes during the larger part of the ,tertiary epoch4 ,it will be best to turn again to the map to observe the possible effect upon the ,gulf ,stream of a geological event of which we have some definite evidence1 and which is adduced by ,mr4 ,upham and others as one of the important probable causes of the ,glacial period1 namely1 the subsidence of the ,isthmus of ,panama and the adjacent narrow neck of land connecting ,north with ,south ,america4 ,it will be seen at a glance that a subsidence sufficient to allow the northwest current of warm water1 pushed by the trade-winds along the northeast shore of ,south ,america1 to pass into the ,pacific ,ocean1 instead of into the ,gulf of ,mexico1 would be a cause sufficient to produce the most far-reaching results2 it would rob the ,north ,atlantic of the immense amount of heat and moisture now distributed over it by the ,gulf ,stream1 and would add an equal amount to the northern ,pacific ,ocean1 and modify to an unknown extent the distribution of heat and moisture over the lands of the northern hemisphere4 ,the supposition that a subsidence of the ,isthmus of ,panama was among the contributing causes of the ,glacial period has been often made1 but without any positive proof of such subsidence4 ,from evidence which has recently come to light1 however1 it is certain that there has actually been considerable subsidence there in late ,tertiary if not in post-,tertiary times4 ,this evidence is furnished by ,dr4 ,g4 ,a4 ,maack and ,mr4 ,william ,m4 ,gabb in their report to the ,united ,states ,government in #ahgd upon the explorations for a ship-canal across the isthmus1 and consists of numerous fossils belonging to existing species which are found at an elevation of #aej feet above tide4 ,as the dividing ridge is more than #gjj feet above tide1 this does not positively prove the point1 but so much demonstrated subsidence makes it easy to believe1 in the absence of contradictory evidence1 that there was more1 and that the isthmus was sufficiently submerged to permit a considerable portion of the warm equatorial current which now passes northward from the ,caribbean ,sea and the ,gulf of ,mexico to pass into the ,pacific ,ocean4 ,illustration3 ,fig4 #aja4--,map showing how the land clusters about the north pole4 ,an obvious objection to the theory of a late ,tertiary or post-,tertiary subsidence of the ,isthmus of ,panama presents itself in the fact that there is at present a complete diversity of species between the fish inhabiting the waters upon the different sides of the isthmus4 ,if there had been such a subsidence1 it seems natural to suppose that ,atlantic species would have migrated to the ,pacific side and obtained a permanent lodgment there1 and that ,pacific species would have found a congenial home on the ,atlantic side4 ,it must be confessed that this is a serious theoretical difficulty1 but perhaps not insuperable4 ,for it is by no means certain that colonists from the heated waters of the ,caribbean ,sea would become so permanently established upon the ,pacific side that they could maintain themselves there upon the re-establishment of former conditions4 ,on the contrary1 it seems reasonable to suppose that upon the re-elevation of the isthmus the northern currents1 which would then resume their course1 would bring back with them conditions unfavourable to the ,atlantic species1 and favourable to the competing species which had only temporarily withdrawn from the field1 and which might now be better fitted than ever to renew the struggle with their ,atlantic competitors4 ,it is by no means certain1 therefore1 that with the re-establishment of the former conditions there would not also be a re-establishment of the former equation of life upon the two sides of the isthmus4 ,mr4 ,upham's theory involves also extensive elevations of land in the northern part of ,america2 in this respect agreeing with the opinions early expressed by ,professors ,j4 ,d4 ,dana and ,j4 ,s4 ,newberry4 ,of the positive indications of such northward elevations of land we have already spoken when treating in a previous chapter of the fiords and submerged channels which characterise northern ,europe and both the eastern and the western coasts of ,north ,america4 ,but in working out the problem the solution is only half reached when we have got the ,gulf ,stream into the ,pacific ,ocean1 and the land in the northern part of the continents elevated to some distance above its present level4 ,there is still the difficulty of getting the moisture-laden currents from the ,pacific ,ocean to carry their burdens over the crest of the ,sierra ,nevada and ,rocky ,mountains and to deposit them in snow upon the ,laurentian highlands4 ,an ingenious supplement to the theory1 therefore1 has been brought forward by ,professor ,carpenter1 who suggests that the immense ,tertiary and post-,tertiary lava-flows which cover so much of the area west of the ,rocky ,mountains were the cause of the accumulations of snow which formed the ,laurentide ,glacier4 ,this statement1 which at first seems so paradoxical as to be absurd1 appears less so upon close examination4 ,the extent of the outflows of lava west of the ,rocky ,mountains is almost beyond comprehension4 ,literally1 hundreds of thousands of square miles have been covered by them to a depth in many places of thousands of feet4 ,these volcanic eruptions are mostly of late date1 beginning in the middle of the ,tertiary and culminating probably about the time of the maximum extent of the ,laurentide ,glacier4 ,indeed1 so nearly contemporaneous was the growth of the ,laurentide ,glacier with these outflows that ,professor ,alexander ,winchell had1 with a good deal of plausibility1 suggested that the outflows of the eruptions of lava were caused by the accumulation of ice over eastern ,british ,america4 ,his theory was that the three million cubic miles of ice which is proved to have been abstracted from the ocean and piled up over that area was so serious a disturbance of the equilibrium of the earth's crust that it caused great fissures to be opened along the lines of weakness west of the ,rocky ,mountains1 and pressed the liquid lava out1 as the juice is pressed out of an orange in one place by pressing upon the rind in another4 ,professor ,carpenter's view is the exact reverse of ,professor ,winchell's4 ,going back to those orographic changes which produced the lava-flows and the elevation of the northern part of ,british ,america1 he thinks the problem of getting the moisture transferred from the ,pacific ,ocean to the ,canadian highlands is solved by the lava-flows west of the ,rocky ,mountains4 ,this immense exudation of molten matter was accompanied by an enormous liberation of heat1 which must have produced significant changes in the meteorological conditions4 ,the moisture of the atmosphere is precipitated by means of the condensation connected with a lowering of its temperature4 ,ordinarily1 therefore1 when moist winds from an oceanic area pass directly over a lofty mountain-chain1 the precipitation takes place immediately1 and the water finds its way back by a short course to the sea4 ,this is what now actually occurs on the ,pacific coast4 ,the ,sierra ,nevada condense nearly all the moisture2 so that very little falls on the vast area extending from their summits eastward to the ,rocky ,mountains4 ,all that region is now practically a desert land1 where the evaporation exceeds the precipitation4 ,in ,professor ,carpenter's view the heat radiated from the freshly exuded lava is supposed to have prevented the precipitation near the coast-line1 and to have helped the winds in carrying it farther onward to the northeast1 where it would be condensed upon the elevated highlands1 upon which the snows of the great ,laurentide ,glacier were collected4 ,it is not necessary for us to attempt to measure the amount of truth in this subsidiary hypothesis of ,professor ,carpenter1 but it illustrates how complicated are the conditions which have to be considered before we rest securely upon any particular hypothesis4 ,the unknown elements of the problem are so numerous1 and so far-reaching in their possible scope1 that a cautious attitude of agnosticism1 with respect to the cause of the ,glacial period1 is most scientific and becoming4 ,still1 we are ready to go so far as to say that ,mr4 ,upham's theory comes nearest to giving a satisfactory account of all the phenomena1 and it is to this that ,professor ,joseph ,le ,conte gives his cautious approval4 ,summarily stated1 this theory is1 that the passage from the ,tertiary to the ,quaternary or ,glacial period was characterised by remarkable oscillations of land-level1 and by corresponding changes of climate1 and of ice-accumulation in northern regions2 that the northern elevation was connected with subsidence in the equatorial regions2 that these changes of land-level were both initiated and1 in the main1 continued by the interior geological forces of the globe2 but that the very continental elevation which mainly brought on the ,glacial period added at length1 in the weight of the ice which accumulated over the elevated region1 a new force to hasten and increase the subsidence1 which would have taken place in due time in the natural progress of the orographic oscillations already begun4 ,professor ,le ,conte illustrates the subject by the following diagram1 which1 for simplicity's sake1 treats the ,glacial epoch as one2 the horizontal line1 ,a ,b1 represents time from the later ,pliocene until now2 but it also represents the present condition of things both as to land-level and as to ice-accumulation4 ,the full line1 c d e1 represents the oscillations of land 7and presumably of temperature7 above and below the present condition4 ,the broken line represents the rise1 culmination1 and decline of ice-accumulation4 ,the dotted line represents the crust-movement as it would have been if there had been no ice-accumulation4 ,illustration3 ,fig4 #ajb4 ,succession of ,epochs1 ,glacial and ,fluvial ,deposits1 and ,eastern ,provinces and ,middle and ,southern ,epochs4 ,new ,england4 ,atlantic ,states4 ,recent or ,rise of the land to its ,continued subsidence of ,terrace4 present height1 or coast at ,new ,york and 7,mostly within somewhat higher1 soon southward1 and rise of the period of after the departure of the mountainous belt1 by traditional the ice4 ,rivers eroding displacement along the and written their glacial fall line of the rivers4 history47 flood-plains1 leaving ,much erosion of the remnants as terraces4 ,columbia formation since ,warmer climate than now1 culmination of second probably due to greater ,glacial epoch2 ,gulf ,stream1 formerly sedimentation in bays1 permitted southern sounds1 and estuaries4 mollusks to extend to ,gulf of ,st4 ,lawrence1 now represented by isolated colonies4 ,glacial ,period of ,ice ,age4 ,pleistocene ,period4 ,champlain4 ,land depressed under ,less subsidence in ice-weight2 glacial latitude of ,new ,york and 7,close of the recession2 continued southward than at north2 second ,glacial deposition of upper till lower ,hudson ,valley1 and epoch47 and deep flood-plains of part of its present gravel1 sand and clay submarine continuation1 7modified drift74 above sea-level4 ,gravel ,terminal moraines marking and sand deposits from pauses or readvance englacial drift in during general retreat of ,delaware and ,susquehanna ice4 ,marine submergence4 ,valleys1 inclosing #aej to #bcj feet on coast abundant human implements of ,maine1 to #ebj feet in at ,trenton1 ,n4,j4 ,gulf and valley of ,st4 ,lawrence4 ,second ,glacial4 ,second great uplift of ,renewal of great the land1 #c4jjj to #d1jjj continental elevation feet higher than now2 7#c4jjj feet in latitude snow-fall again all the of ,new ,york and year2 ice probably two ,philadelphia71 of miles thick on ,laurentide excessive snow-fall and highlands1 and extending rains1 and of wide-spread somewhat farther south fluvial deposits1 the here than in first ,columbia formation1 on glaciation4 ,lower till the coastal plain1 during 7ground moraine71 and early part of this epoch4 upper till 7englacial ,implements of man at drift74 ,terminal ,claymont1 ,del4 moraines1 kames1 osars1 valley drift4 ,inter-glacial4 ,ice-sheet melted here2 ,depression1 but generally probably not more ice in not to the present level4 7,longest epoch arctic regions than now4 ,deep channels cut in the of this era47 bed-rocks by the ,fluvial and lacustrine ,delaware1 ,susquehanna1 deposits of this time1 ,potomac1 and other with those of the first rivers4 ,the ,appomattox ,glacial epoch1 were deposits much eroded4 eroded by the second glaciation4 ,relative length of this epoch made known by ,mc,gee from study of this region4 ,first ,glacial4 ,begun by high continental ,continental elevation2 uplift1 cool climate and erosion of ,delaware and snow-fall throughout the ,chesapeake ,bays1 and of year1 producing ,albemarle and ,pamlico ice-sheet4 ,much glacial ,sounds4 ,plentiful erosion and snow-fall on the southern transportation2 till and ,appalachian ,mountains2 stratified deposits4 snows melted in summer1 ,ended by depression of and heavy rains1 land2 return of warm producing broad climate1 with rain2 final river-floods1 with melting of the ice4 deposition of the ,isthmus of ,panama ,appomattox formation4 probably submerged 7,gulf ,stream smaller71 and again in second ,glacial epoch4 ,changes in ,altitude and ,climate1 during the ,quaternary ,era4 ,mississippi ,basin and ,cordilleran ,region4 ,europe and ,asia4 northward4 ,terracing of river ,including a stage of ,erosion and terracing valleys4 ,northward rise considerable uplift1 of stratified drift in of area of ,lake ,agassiz with return of humid river valleys4 ,land nearly complete before conditions1 ,alpine passage of ,european the ice was melted on glaciation 7third flora to ,greenland2 the country crossed by ,glacial epoch71 and succeeded by subsidence ,nelson ,river2 but rise the second great rise there1 admitting warm about ,hudson ,bay is still of ,lakes ,bonneville currents to ,arctic ,sea4 going on2 #g1jjj to #h1jjj and ,lahontan4 ,very ,minor climatic changes1 years since ice-melting recent subsidence including a warmer uncovered ,niagara and and change to present stage than now4 ,upper falls of ,st4 ,anthony4 aridity4 and outer portions of ,indo-,gangetic alluvial plain2 extensive deposits of ,hwang ,ho1 and destructive changes of its course4 ,abundant deposition of ,depression probably ,final departure of the englacial drift4 ,stone almost to the present ice-sheets2 glacial implements in river level4 ,restoration of rivers forming eskers gravels of ,ohio1 ,ind41 arid climate2 nearly or and kames4 ,loess and ,minn4 ,laurentian quite complete deposited while the lakes held at higher evaporation of ,lakes region of the ,alps was levels1 and ,lake ,bonneville and ,lahontan4depressed lower than ,agassiz formed in ,red ,formation of the adobenow4 ,upper 7englacial7 ,river basin1 by continuing through the till1 and asar1 of barrier of retreating second ,glacial1 ,sweden4 ,marine ice1 with outlets over ,champlain1 and ,recent submergence #ejj to #fjj lowest points of their epochs4 feet in ,scotland1 present southern ,scandinavia1 and water-shed4 ,marine ,spitzbergen4 submergence #cjj to #ejj feet on southwest side of ,hudson ,bay4 ,ice-sheet here less ,probable uplift #c1j ,second elevation and extensive than in the feet1 shown by general glaciation of first ,glacial epoch1 and submerged valleys near northwestern ,europe2 not generally bordered ,cape ,mendocino4 ,second the ice-sheets of ,great as then by lakes in ice-sheet on ,british ,britain probably more valleys which now drain ,columbia and ,vancouver extensive than in first southward4 ,island2 local ,glacial epoch4 glaciation of ,rocky ,oscillations of ,terminal moraines at ,mountains1 ,cascade and ice-front2 ,british extreme limit of the ,sierra range1 ,nevada1 ,lower and ,upper ice-advance1 and at ten south to latitude #cg4 the ,chalky1 ,purple1 and or more stages of halt or ,first great rise of bowlder-clays1 ,hessle readvance in its retreat4 ,lakes ,bonneville bowlder-clays4 ,terminal and ,lahontan4 moraines in ,germany4 ,depression nearly to ,continental depression4 ,recession1 or probably present level southward2 ,arid climate4 ,long- complete departure1 of more northward1 but continued denudation of the ice-sheets4 followed there1 by the mountains3 differential uplift of resulting very thick ,land connection between #hjj or #a1jjj feet4 subarial deposits of ,europe and ,africa1 ,great erosion of loess the adobe4 permitting southern and other modified animals to extend far drift1 and of ,orange ,intermittent volcanic northward4 ,sand4 ,valleys of this action in various parts epoch1 partly filled of this region1 ,erosion of the ,somme with later till1 are throughout the ,valley below its oldest marked by chains of ,quaternary era to very implement-bearing lakes in southern recent times1 and gravels4 ,minnesota4 liable to break forth again4 ,pliocene elevation of ,latest rise 7#c4jjj ,uplift and glaciation continent brought to feet7 of the ,colorado of northwestern ,europe3 culmination at ,caon district4 ,sierra maximum elevation4 beginning of ,nevada and other ,great #b1ejj feet or more ,quaternary era2 this ,basin mountain-ranges 7depth of the ,skager whole basin probably formed by immense ,rack72 ,france and then uplifted #c4jjj uplifts1 with faulting4 ,britain united with the feet2 excessive ,california river- ,fre ,islands1 ,iceland1 snow-fall and rain2 courses changed2 human and ,greenland4 ,uplifts deposition of the bones and implements in of the ,himalayas and ,orange ,sand4 ,ice- the old river gravels1 other mountain-ranges sheet south to lava-covered4 ,ice-sheet attendant on both ,cincinnati and ,st4 on ,british ,columbia2 ,glacial epochs4 ,louis1 at length local glaciers depressing the earth's southward4 crust beneath it2 slackened river floods and shallow lakes1 forming the loess4 ,it is seen from the diagram that the ice-accumulation culminated at a time when the land1 under the pressure of the ice-load1 had already commenced to subside2 and that the subsidence was greatest at a time when the pressure had already begun to diminish4 ,but the fact that the land1 after the removal of the ice-load1 did not return again to its former height in the ,pliocene1 is proof positive that there were other and more fundamental causes of crust-movement at work besides weighting and lightening4 ,the land did not again return to its former level because the cycle of elevation1 whatever its cause1 which commenced in the ,pliocene and culminated in the early ,quaternary1 had exhausted itself4 ,if it had not been for the ice-load interfering with and modifying the natural course of the crust-movement determined previously and primarily by other and probably internal causes1 the latter would probably have taken the course represented by the dotted line4 ,it would have risen higher and culminated later1 and its curve would have been of simpler form4 ,we append a carefully prepared table by ,mr4 ,warren ,upham1 showing the probable changes in altitude and climate during the ,quaternary era4,,dx ,footnote ,,dx3 ,on page #ajf and sequel ,i have summarised the reasons which lead me to discard the ,inter-,glacial epoch1 and to look upon the whole ,glacial period as constituting a grand unity with minor episodes4 ,it does not yet seem to me that the duality of the period is proved4 ,on the contrary1 ,mr4 ,kendall's chapter on the ,glacial phenomena of ,great ,britain strongly confirms my view4 ,on the part of many the theory here provisionally adopted will be regarded with disfavour by reason of a disinclination to supposing any great recent changes of level in the continental areas4 ,so firmly established do the continents appear to be1 that it seems like invoking an inordinate display of power to have them exalted for the sake of producing a ,glacial period4 ,due reflection1 however1 will make it evident that within certain limits the continents are exceedingly unstable1 and that they have displayed this instability to as great an extent in recent geological times as they have done in any previous geological periods4 ,when one reflects1 also1 upon the size of the earth1 a continental elevation of #c1jjj or #d1jjj feet upon a globe whose diameter is more than #dj1jjj1jjj feet is an insignificant trifle4 ,on a globe one foot in diameter it would be represented by a protuberance of barely one thousandth of an inch4 ,a corresponding wrinkle upon a large apple would require a magnifying-glass for its detection4 ,moreover1 the activity of existing volcanoes1 the immense outflows of lava which have taken place in the later geological periods1 together with the uniform increase of heat as we penetrate to deeper strata in the crust of the earth--all point to a condition of the earth's interior that would make the elevations of land which we have invoked for the production of the ,glacial period easily credible4 ,physicists do not1 indeed1 now hold to the entire fluidity of the earth's interior1 but rather to a solid centre1 where gravity overcomes the expansive power of heat1 and maintains solidity even when the heat is intense4 ,but between the cooling crust of the earth's exterior and a central solid core there is now believed to be a film where the influences of heat and of the pressure of gravity are approximately balanced1 and the space is occupied by a half-melted or viscous magma1 capable of yielding to a slow pressure1 and of moving in response to it from one portion of the enclosed space to another where the pressure is for any cause relieved4 ,as a result of prolonged enquiries respecting the nature of the forces at work both in the interior and upon the exterior of the earth1 and of a careful study of the successive changes marking the geological period1 we are led to believe that the continental elevations necessary to produce the phenomena of the ,glacial period are not only entirely possible but easily credible1 and in analogy with the natural progress of geological history4 ,in the first place1 it is easy to see that two causes are in operation to produce a contraction of the earth's volume and a shortening of its diameter4 ,heat is constantly being abstracted from the earth by conduction and radiation1 but perhaps to a greater extent through ceaseless volcanic eruptions which at times are of enormous extent4 ,it requires but a moment's thought to see that contraction of the volume of the earth's interior means that the hardened exterior crust must adjust itself by wrinkles and folds4 ,for a long period this adjustment might show itself principally in gentle swells1 lifting portions of the continents to a higher level1 accompanied by corresponding subsidence in other places4 ,this gradually accumulating strain would at length be relieved along some line of special weakness in the crust by that folding process which has pushed up the great mountain systems of the world4 ,careful study of the principal mountain systems shows that all the highest of them are of late geological origin4 ,indeed1 the latter part of the ,tertiary period has been the great mountain-building epoch in the earth's history4 ,the principal part of the elevation of the ,andes and the ,rocky ,mountains has taken place since the middle of the ,tertiary period4 ,in ,europe there is indubitable evidence that the ,pyrenees have been elevated eleven thousand feet during the same period1 and that the western ,alps have been elevated thirteen thousand feet in the same time4 ,the ,carpathians1 the western ,caucasus1 and the ,himalayas likewise bear explicit evidence to the fact that a very considerable portion of their elevation1 amounting to many thousand feet1 has been effected since the middle of the ,tertiary period1 while a considerable portion of this elevation of the chiefest mountain systems of the world has occurred in what would be called post-,tertiary time--that is1 has been coincident with a portion of the ,glacial period4 ,the ,glacial period1 however1 we suppose to have been brought about1 not by the specific plications in the earth's crust which have produced the mountain-chains1 but by the gentler swells of larger continental areas whose strain was at last relieved by the folding and mashing together of the strata along the lines of weakness now occupied by the mountain systems4 ,the formation of the mountains seems to have relieved the accumulating strain connected with the continental elevations1 and to have brought about a subsequent subsidence4 ,doubtless1 also1 correlated subsidences and elevations of the earth's crust have been aided by the transfer of the sediment from continental to oceanic areas1 and1 as already suggested1 during the ,glacial period by the transfer of water evaporated from the surface of the ocean to the ice-fields of the glaciated area4 ,for example1 present erosive agencies are lowering the level of the whole ,mississippi basin from the ,alleghanies to the ,rocky ,mountains at the rate of a foot in five thousand years4 ,all this sediment removed is being transferred to the ocean-bed4 ,present agencies1 therefore1 if not counteracted1 would remove the whole continent of ,america 7whose average elevation above the sea is only #gdh feet7 in less than four million years2 while the great rivers which descend in all directions from the central plateau of ,asia are transferring sediment to the ocean from two to four times as fast as the ,mississippi is1 and the ,po is transferring it from the ,alps to the ,adriatic fully seven times as fast as the ,mississippi is from its basin to the ,gulf of ,mexico4 ,this rapid transfer of sediment from the continents to the ocean is producing effects in disturbing the present equilibrium of the earth's crust1 which are too complicated for us fully to calculate2 but it is by no means improbable that when accumulating for a considerable length of time1 the ultimate results may be very marked and perhaps sudden in their appearance4 ,the same may also be said of the accumulation of ice during the ,glacial period4 ,the glaciated areas of ,north ,america and ,europe combined comprise about six million square miles4 ,at a moderate estimate1 the ice was three-quarters of a mile deep4 ,here1 therefore1 there would be between four and five million cubic miles of water1 which had first relieved the ocean-beds of the pressure of its weight1 and then concentrated its force over the elevated areas of the northern hemisphere4 ,this disturbance of the equilibrium1 by the known transfer of force from one part of the earth's crust to another1 certainly gives much plausibility to the theory of ,jamieson1 ,winchell1 ,le ,conte1 and ,upham1 that the ,glacial period partly contained in itself its own cure1 and by the weight of its accumulated weight of ice helped to produce that depression over the glaciated area which at length rendered the accumulation of ice there impossible4 ,this general view of the known causes in operation during the ,glacial period will go far towards answering an objection that has probably before this presented itself to the reader's mind4 ,it seems clear that the ,glacial period in the southern hemisphere has been nearly contemporaneous with that of the northern4 ,the ,glacial period proper of the southern hemisphere is long since passed4 ,the existing glaciers of ,new ,zealand1 of the southern portion of the ,andes ,mountains1 and of the ,himalaya ,mountains are but remnants of those of former days4 ,in the light of the considerations just presented1 it would not seem improbable that the same causes should produce these similar effects in the northern and the southern hemisphere contemporaneously4 ,at any rate1 it would not seem altogether unlikely that the pressure of ice during the climax of the ,glacial period upon the northern hemisphere 7which1 as we have seen1 there is reason to believe aided in the depression of the continent to below its present level in the latter part of the ,glacial period7 should have contributed towards the elevation of mountains in other parts of the world1 and so to the temporary enlargement of the glaciers about their summits4 ,nor are we wholly without evidence that these readjustments of land-level which have been carried on so ,vigorously since the middle of the ,tertiary period are still going on with considerable though doubtless with diminished rapidity4 ,there has been a re-elevation of the land in ,north ,america since the ,glacial period amounting to #bcj feet upon the coast of ,maine1 #ejj feet in the vicinity of ,montreal1 from #a1jjj to #a1fjj feet in the extreme northern part of the continent1 and in ,scandinavia to the extent of #fjj feet4 ,in portions of ,scandinavia the land is now rising at the rate of three feet in a century4 ,other indications of even the present instability of the earth's surface occur in numbers too numerous to mention4,,dy ,footnote ,,dy3 ,for a convincing presentation of the views here outlined1 together with abundant references to literature1 see ,mr4 ,warren ,upham's ,appendix to the author's ,ice ,age in ,north ,america4 ,but1 while we are increasingly confident that the main causes of the ,glacial period have been changes in the relative relation of land-levels connected with diversion of oceanic currents1 it is by no means impossible1 as ,wallace,,dz and others have suggested1 that these were combined with the astronomical causes urged by ,drs4 ,croll and ,geikie4 ,by some this combination is thought to be the more probable1 because of the extreme recentness of the close of the ,glacial period1 as shown by the evidence which will be presented in the following chapter4 ,the continuance of glaciers in the highlands of ,canada1 down to within a few thousand years of the present time1 coincides in a remarkable manner with the last occurrence of the conditions favourable to glaciation upon ,mr4 ,croll's theory1 which took place about eleven thousand years ago4 ,footnote ,,dz3 ,see ,island ,life1 chapters viii and ix4 ,,chapter ,x4 ,,the ,,date ,,of ,,the ,,glacial ,,period4 ,in approaching the subject of glacial chronology1 we are compelled to recognise at the outset the approximate character of all our calculations4 ,still1 we shall find that there are pretty well-defined limits of time beyond which it is not reasonable to place the date of the close of the ,glacial period2 and1 where exact figures cannot be determined1 it may yet be of great interest and importance to know something near the limits within which our speculations must range4 ,for many years past ,mr4 ,croll's astronomical theory as to the cause of the ,glacial period has been considered in certain circles as so nearly established that it has been adopted by them as a chronological table in which to insert a series of supposed successive ,glacial epochs which are thought to have characterised not merely the ,quaternary epoch but all preceding geological eras4 ,what we have already said1 however1 respecting the weakness of ,mr4 ,croll's theory is probably sufficient to discredit it as a chronological apparatus4 ,we will therefore turn immediately to the more tangible evidences bearing upon the subject4 ,the data directly relating to the length of time which separates the present from the ,glacial period are mainly connected with two classes of facts3 #a4 ,the amount of erosion which has been accomplished by the river systems since the ,glacial period2 and #b4 ,the amount of sedimentation which has taken place in lakes and kettle-holes4 ,we will consider first the evidence from erosion4 ,illustration3 ,fig4 #ajc4--;,diagram of eccentricity and precession3 ,abscissa represents time and ordinates1 degrees of eccentricity and also of cold4 ,the dark and light shades show the warmer and colder winters1 and therefore indicate each #aj1ejj years1 the whole representing a period of #cjj1jjj years4 ,the gorge below ,niagara ,falls affords an important chronometer for measuring the time which has elapsed since a certain stage in the recession of the great ,north ,american ice-sheet4 ,as already shown1 the present ,niagara ,river is purely a post-glacial line of drainage2,,ea the preglacial outlet to ,lake ,erie having been filled up by glacial deposits1 so that1 on the recession of the ice1 the lowest level between ,lake ,erie and ,lake ,ontario was in the line of the trough of the present outlet4 ,but1 from what has already been said1 it also appears that the ,niagara ,river did not begin to flow until considerably after the ice-front had withdrawn from the escarpment at ,queenston1 where the river now emerges from its caon to the low shelf which borders ,lake ,ontario4 ,for a considerable period afterwards the ice continued to block up the easterly and northerly outlets through the valleys of the ,mohawk and of the ,st4 ,lawrence1 and held the water in front of the ice up to the level of the passes leading into the ,mississippi ,valley4 ,niagara ,river1 of course1 was not born until these ice-barriers on the east and northeast melted away sufficiently to allow the drainage to take its natural course4 ,footnote ,,ea3 ,see above1 p4 #bjj et seq4 ,illustration3 ,fig4 #ajd4--,map of the ,niagara ,river below the falls1 showing the buried channel from the whirlpool to ,st4 ,davids4 ,small streams1 a1 b1 c1 fall into the main gorge over a rocky escarpment4 ,no rock appears in the channel at d1 but the rocky escarpment reappears at e4 ,of these barriers1 that across the ,mohawk ,valley doubtless gave way first4 ,this would allow the confluent waters of this great glacial lake to fall down to the level of the old outlet from the basin of ,lake ,ontario into the ,mohawk ,valley1 in the vicinity of ,home1 ,n4 ,y4 ,the moment1 however1 that the water had fallen to this level1 the plunging torrents of ,niagara would begin their work2 and the gorge extending from ,queenston up to the present falls is the work done by this great river since that point of time in the ,glacial period when the ice-barrier across the ,mohawk ,valley broke away4 ,the problem is therefore a simple one4 ,considering the length of this gorge as the dividend1 the object is to find the rate of annual recession2 this will be the divisor4 ,the quotient will be the number of years which have elapsed since the ice first melted away from the ,mohawk ,valley4 ,we are favoured in our calculation by the simplicity of the geologic arrangement4 ,the strata at ,niagara dip slightly to the south1 but not enough to make any serious disturbance in the problem4 ,that at the surface1 over which the water now plunges1 consists of hard limestone1 seventy or eighty feet in thickness1 and this is continuous from the falls to the face of the escarpment at ,queenston1 where the river emerges from the gorge4 ,immediately underneath this hard superficial stratum there is a stratum of soft rock1 of about the same thickness1 which disintegrates readily4 ,as a consequence1 the plunging water continually undermines the hard stratum at the surface1 and prepares the way for it to fall down1 from time to time1 in huge blocks1 which are1 in turn1 ground to powder by the constant commotion in which they are kept1 and thus the channel is cleared of dbris4 ,illustration3 ,fig4 #aje4--,section of strata along the ,niagara gorge from the falls to the lake3 #a1 #c1 strata of hard rock2 #b1 #d1 of soft rock4 ,below these two main strata there is considerable variation in the hardness of the rock1 as shown in the accompanying diagram1 where #c and #e are hard strata separated by a soft stratum4 ,in view of this fact it seems probable that1 for a considerable period in the early part of the recession1 instead of there being simply one1 there was a succession of cataracts1 as the water unequally wore back through the harder strata1 numbered #e1 #c1 and #a2 but1 after having receded half the distance1 these would cease to be disturbing influences1 and the problem is thus really the simple one of the recession through the strata numbered #a and #b1 which are continuous4 ,so uniform in consistency are these throughout the whole distance1 that the rate of recession could never have been less than it is now4 ,we come1 therefore1 to the question of the rapidity with which the falls are now receding4 ,in #ahda ,sir ,charles ,lyell and ,professor ,james ,hall 7the ,state ,geologist of ,new ,york7 visited the falls together1 and estimated that the rate of recession could not be greater than one foot a year1 which would make the time required about thirty-five thousand years4 ,but ,lyell thought this rate was probably three times too large2 so that he favoured extending the time to one hundred thousand years4 ,before this the eminent ,french geologist ,desor had estimated that the recession could not have been more than a foot in a century1 which would throw the beginning of the gorge back more than three million years4 ,but these were mere guesses of eminent men1 based on no well-ascertained facts2 while ,mr4 ,bakewell1 an eminent ,english geologist1 trusting to the data furnished him by the guides and the old residents of ,niagara1 had1 even then1 estimated that the rate of recession was as much as three feet a year1 which would reduce the whole time required to about ten thousand years4 ,but the visit of ,lyell and ,hall in #ahda led to the beginning of more accurate calculations4 ,professor ,hall soon after had a trigonometrical survey of the falls made1 from which a map was published in the ,state geological report4 ,from this and from the monuments erected1 we have had since that time a basis of comparison in which we could place absolute confidence4 ,in recent years three surveys have been made3 the first by the ,new ,york ,state ,geologists1 in #ahge2 and the third by ,mr4 ,r4 ,s4 ,woodward1 the mathematician of the ,united ,states ,geological ,survey1 in #ahhf4 ,the accompanying map shows the outlines of the falls at the time of these three measurements1 from #ahdb to #ahhf4 ,according to ,mr4 ,woodward1 the length of the front of the ,horseshoe ,fall is twenty-three hundred feet4 ,between #ahdb and #ahge four and a quarter acres of rock were worn away by the recession of the falls4 ,between #ahge and #ahhf a little over one acre and a third disappeared in a similar manner1 making in all1 from #ahdb to #ahhf1 about five and a half acres removed1 and giving an annual rate of recession of about two feet and a half per year for the last forty-five years4 ,but in the central parts of the curve1 where the water is deepest1 the ,horseshoe ,fall retreated between two hundred and two hundred and seventy-five feet in the eleven years between #ahge and #ahhf4 ,illustration3 ,fig4 #ajf4--,map showing the recession of the ,horseshoe ,falls since #ahdb1 as by survey mentioned in the text 7,pohlman74 7by courtesy of the ,american ,institute of ,mining ,engineers47 ,it will be perceived that the recession in the centre of the ,horseshoe is very much more rapid than that nearer the margin2 yet this rate at the centre is more nearly the standard of calculation than is that near the margin1 for the gorge constantly tends to enlarge itself below the falls1 and so gradually to bring itself into line with the full-formed channel4 ,taking all things into account1 ,mr4 ,woodward and the other members of the ,geological ,survey thought it not improbable that the average rate of actual recession in the ,horseshoe ,fall was as great as five feet per annum2 and that1 if we can rely upon the uniformity of the conditions in the past1 seven thousand years is as long a period as can be assigned to its commencement4 ,the only condition in the problem about which there can be much chance of question relates to the constancy of the volume of water flowing in the ,niagara channel4 ,mr4 ,gilbert had suggested that1 as a consequence of the subsidence connected with the closing portions of the ,glacial period1 the water of the ,great ,lakes may have been largely diverted from its present outlet in ,niagara ,river and turned northeastward1 through ,georgian ,bay1 ,french ,river1 and ,lake ,nipissing1 into a tributary of the ,ottawa ,river1 and so carried into the ,st4 ,lawrence below ,lake ,ontario4 ,of this theory there is also much direct evidence4 ,a well-defined shore line of rounded pebbles extends1 at an elevation of about fifty feet1 across the col from ,lake ,nipissing to the head-waters of the ,mattawa1 a tributary of the ,ottawa2 while at the junction with the ,ottawa there is an enormous delta terrace of boulders1 forming a bar across the main stream just such as would result from ,mr4 ,gilbert's supposed outlet4 ,but this outlet was doubtless limited to a comparatively few centuries1 and ,dr4 ,robert ,bell thinks the evidence still inconclusive4,,eb ,footnote ,,eb3 ,see ,bul4 ,geol4 ,soc4 ,am41 vol4 iv1 pp4 #dbc-dbg1 vol4 v1 pp4 #fbj-fbf4 ,a second noteworthy glacial chronometer is found in the gorge of the ,mississippi ,river1 extending from the ,falls of ,st4 ,anthony1 at ,minneapolis1 to its junction with the preglacial trough of the old ,mississippi1 at ,fort ,snelling1 a distance likewise of about seven miles4 ,above ,fort ,snelling the preglacial gorge is occupied by the ,minnesota ,river1 and1 as we have before stated1 extends to the very sources of this river1 and is continuous with the southern portion of the valley of the trough of the ,red ,river of the ,north4 ,before the ,glacial period the drainage of the present basin of the upper ,mississippi joined this main preglacial valley1 not at ,fort ,snelling1 but some little distance above1 as shown upon our map4,,ec ,this part of the preglacial gorge became partially filled up with glacial deposits1 but it can be still traced by the lakelets occupying portions of the old depression1 and by the records of wells which have been sunk along the line4 ,when the ice-front had receded beyond the site of ,minneapolis1 the only line of drainage left open for the water was along the course of the present gorge from ,minneapolis to ,fort ,snelling4 ,footnote ,,ec3 ,see above1 p4 #bji4 ,here1 as at ,niagara1 the problem is comparatively simple4 ,the upper strata of rock consist of hard limestone1 which is underlaid by a soft sandstone1 which1 like the underlying shale at ,niagara1 is eroded faster than the upper strata1 and so a perpendicular fall is maintained4 ,the strata are so uniform in texture and thickness that1 with the present amount of water in the river1 the rate of recession of the falls must have been1 from the beginning1 very constant4 ,if1 therefore1 the rate can be determined1 the problem can be solved with a good degree of confidence4 ,fortunately1 the first discoverer of the cataract--the ,catholic missionary ,hennepin--was an accurate observer1 and was given to recording his observations for the instruction of the outside world and of future generations4 ,from his description1 printed in ,amsterdam in #agjd1 ,professor ,n4 ,h4 ,winchell is able to determine the precise locality of the cataract when discovered in #afhj4 ,again1 in #agff the ,catholic missionary ,carver visited the falls1 and not only wrote a description1 but made a sketch 7found in an account of his travels1 published in ,london in #aghh7 which confirms the inferences drawn from ,hennepin's narrative4 ,the actual period of recession1 however 7which ,professor ,winchell duly takes into account71 extends only to the year #ahef1 at which time such artificial changes were introduced as to modify the rate of recession and disturb further calculations4 ,but between #afhj and #agff the falls had evidently receded about #dab feet4 ,between #agff and #ahef the recession had been #fjj feet4 ,the average rate is estimated by ,professor ,winchell to be about five feet per year1 and the total length of time required for the formation of the gorge above ,fort ,snelling is a little less than eight thousand years1 or about the same as that calculated by ,messrs4 ,woodward and ,gilbert for the ,niagara gorge4 ,to these calculations of ,professor ,winchell it does not seem possible to urge any valid objection4 ,it does not seem credible that the amount of water in the ,mississippi should ever have been less than now1 while during the continuance of the ice in the upper portion of the ,mississippi basin the flow of water was certainly far greater than now4 ,if any one is inclined to challenge ,professor ,winchell's interpretation of the facts1 even a hasty visit to the locality will suffice to produce conviction4 ,the comparative youth of the gorge from ,fort ,snelling up to ,minneapolis is evident3 #a4 ,from its relative narrowness1 when compared with the main valley below4 ,this is represented by the shading upon the map4 ,the gorge from ,fort ,snelling up is not old enough to have permitted much enlargement by the gradual undermining of the superficial strata on either side1 which slowly but constantly goes on4 #b4 ,from the abruptness with which it merges into the preglacial valley of the ,minnesota-,mississippi4 ,the opening at ,fort ,snelling is not ,y-shaped1 as in gorges where there has been indefinite time for the operation of erosive agencies4 #c4 ,furthermore1 the precipices lining the post-glacial gorge above ,fort ,snelling are far more abrupt than those in the preglacial valley below1 and they give far less evidence of weathering4 #d4 ,still1 again1 the tributary streams1 like the ,minnehaha ,river1 which empty into the ,mississippi between ,fort ,snelling and ,minneapolis1 flow upon the surface1 and have eroded gorges of very limited extent2 whereas1 below ,fort ,snelling1 the small streams have usually either found underground access to the river or occupy gorges of indefinite extent4 ,the above estimates1 setting such narrow limits to post-glacial time in ,america1 will seem surprising only to those who have not carefully considered the glacial phenomena of various kinds to be observed all over the glaciated area4 ,as already said1 the glaciated portion of ,north ,america is a region of waterfalls1 caused by the filling up of old channels with glacial dbris1 and the consequent diversion of the water-courses4 ,by this means the streams in countless places have been forced to fall over precipices1 and to begin anew their work of erosion4 ,waterfalls abound in the glaciated region because post-glacial time is so short4 ,give these streams time enough1 and they will wear their way back to their sources1 as the preglacial streams had done over the same area1 and as similar streams have done outside the glaciated region4 ,upon close observation1 it will be found that the waterfalls in ,america are nearly all post-glacial1 and that their work of erosion has been confined to a very limited time4 ,a fair example is to be seen at ,elyria1 ,ohio1 in the falls of ,black ,river1 one of the small streams which empty into ,lake ,erie from the south4 ,its post-glacial gorge1 worn in sandstone which overlies soft shale1 is only about two thousand feet in length1 and it has as yet made no approach toward a ,v-shaped outlet4 ,the same impression of recent age is made by examining the outlets of almost any of the lakes which dot the glaciated area4 ,the very reason of the continued existence of these lakes is that they have not had time enough to lower their outlets sufficiently to drain the water off1 as has been done in all the unglaciated region4 ,in many cases it is easy to see that the time during which this process of lowering the outlets has been going on cannot have been many thousand years4 ,the same impression is made upon studying the evidences of post-glacial valley erosion4 ,ordinary streams constantly enlarge their troughs by impinging against the banks now upon one side and now upon the other1 and transporting the material towards the sea4 ,it is estimated by ,wallace that nine-tenths of the sedimentary material borne along by rivers is gathered from the immediate vicinity of its current1 and goes to enlarge the trough of the stream4 ,upon measuring the cubical contents of many eroded troughs of streams in the glaciated region1 and applying the tables giving the average amount of annual transportation of sediment by streams1 we arrive at nearly the same results as by the study of the recession of post-glacial waterfalls4 ,professor ,l4 ,e4 ,hicks1 of ,granville1 ,ohio1 has published the results of careful calculations made by him1 concerning the valley of ,raccoon ,creek in ,licking ,county1 ,ohio4,,ed ,these show that fifteen thousand years would be more than abundant time for the erosion of the immediate valley adjoining that small stream4 ,i have made and published similar calculations concerning ,plum ,creek1 at ,oberlin1 in ,lorain ,county1 ,ohio4,,ee ,like ,raccoon ,creek1 this has its entire bed in glacial deposits1 and has had nothing else to do since its birth but to enlarge its borders4 ,the drainage basin of the creek covers an area of about twenty-five square miles4 ,its main trough averages about twenty feet in depth by five hundred in width1 along a distance of about ten miles4 ,from the rate at which the stream is transporting sediment1 it is incredible that it could have been at work at this process more than ten thousand years without producing greater results4 ,footnote ,,ed3 ,see ,baptist ,quarterly for ,july4 #ahhd4 ,footnote ,,ee3 ,see ,ice ,age in ,north ,america1 p4 #dfi4 ,calculations based upon the amount of sediment deposited since the retreat of the ice-sheet point to a like moderate conclusion4 ,when one looks upon the turbid water of a raging stream in time of flood1 and considers that all the sediment borne along will soon settle down upon the bottom of the lake into which the stream empties1 he can but feel surprised that the wash of the hills has not already filled up the depression of the lake4 ,it certainly would have done so had the present condition of things existed for an indefinite period of time4 ,naturally1 while prosecuting the survey of the superficial geology of ,minnesota1 ,mr4 ,upham was greatly impressed by the continued existence of the innumerable lakelets that give such a charm to the scenery of that ,state4 ,every day's investigations added to the evidence that the lapse of time since the ,ice age must have been comparatively brief1 since1 otherwise1 the rains and streams would have filled these basins with sediment1 and cut outlets low enough to drain them dry1 for in many instances he could see such changes slowly going forward4,,ef ,footnote ,,ef3 ,minnesota ,geological ,report for #ahgi1 p4 #gc4 ,illustration3 ,fig4 #ajg4--,section of kettle-hole near ,pomp's ,pond1 ,andover1 ,massachusetts 7see text74 7,for general view of the situation1 see ,fig4 #cj1 p4 #gh47 ,some years ago ,i myself made a careful estimate of the amount of deposition and vegetable accumulation which had taken place in a kettle-hole near ,pomp's ,pond1 in ,andover1 ,mass4 ,the diameter of the depression at the rim was #bgf feet4 ,the inclination of the sides was such that the extreme depression of the apex of the inverted cone could not have been more than seventy feet2 yet the accumulation of peat and sediment only amounted to a depth of seventeen feet4 ,the total amount of material which had accumulated would be represented by a cone ninety-six feet in diameter at the base and seventeen feet at the apex1 which would equal only a deposit of about five feet over the present surface of the bottom4 ,it is easy to see that ten thousand years is a liberal allowance of time for the accumulation of five feet of sediment in the bottom of an enclosure like a kettle-hole1 for upon examination it is clear that whatever insoluble material gets into a kettle-hole must remain there1 since there is no possible way by which it can get out4 ,now five feet is sixty inches1 and if this amount has been six thousand years in accumulating1 that would represent a rate of an inch in one hundred years1 while1 if it has been twelve thousand years in accumulation1 the rate will be only one two-hundredth of an inch per year1 a film so small as to be almost inappreciable4 ,if we may judge from appearance1 the result would not be much different in the case of the tens of thousands of kettle-holes and lakelets which dot the surface of the glaciated region4 ,in the year #ahfi ,dr4 ,e4 ,andrews1 of ,chicago1 made an important series of calculations concerning the rate at which the waters of ,lake ,michigan are eating into the shores and washing the sediment into deeper water or towards the southern end of the lake4 ,with reference to the erosion of the shores1 it appears from the work of the ,united ,states ,coast ,survey that a shoulder1 covered with sixty feet of water1 representing the depth at which wave-action is efficient in erosion1 extends outward from the west shore a distance of about three miles1 where the sounding line reveals the shore of the deeper original lake as it appeared upon the first withdrawal of the ice4 ,from a variety of observations the average rate at which the erosion of the bluffs is proceeding is found to be such that the post-glacial time cannot be more than ten thousand years1 and probably not more than seven thousand4 ,an independent mode of calculating this period is afforded by the accumulations of sand at the south end of the lake1 to which it is constantly drifting by the currents of water propelled against the shores by the wind2 for the body of water in the lake is moving southward along the shores towards the closed end in that direction1 there being a returning current along the middle of the lake4 ,all the railroads approaching ,chicago from the east pass through these sand deposits1 and few of the observant travellers passing over the routes can have failed to notice the dunes into which the sand has been drifted by the wind4 ,now1 all the material of these dunes and sand-beaches has been washed out of the bluffs to the northward by the process already mentioned1 and has been slowly transferred by wave-action to its present position4 ,it is estimated that south of ,chicago and ,grand ,haven1 this wave-transported sand amounts to #c1djg1dea1jjj cubic yards4 ,this occupies a belt curving around the south end about ten miles wide and one hundred miles long4 ,the rate at which the sand is moving southward along the shore is found by observing the amount annually arrested by the piers at ,chicago1 ,grand ,haven1 and ,michigan ,city4 ,this equals #abi1jjj cubic yards for a year1 which can scarcely be more than one quarter or one fifth of the total amount in motion4 ,at this rate1 the sand accumulations at the southern end of the lake would have been produced in a little less than seven thousand years4 ,if1 says ,dr4 ,andrews1 we estimate the total annual sand-drift at only twice the amount actually stopped by the very imperfect piers built--which1 in the opinion of the engineers1 is setting it far too low--and compare it with the capacity of the clay-basin of ,lake ,michigan1 we shall find that1 had this process continued one hundred thousand years the whole south end of ,lake ,michigan1 up to the line connecting ,chicago and ,michigan ,city1 would have been full and converted into dry land twenty-five thousand years ago1 and the coast-line would now be found many miles north of ,chicago4,,eg ,footnote ,,eg3 ,southall's ,recent ,origin of ,man1 p4 #ejb4 ,it is proper to add a word in answer co an objection which may arise in the reader's mind1 for it will doubtless occur to some to ask why this sand which is washed out by the waves from the bluffs is not carried inward towards the deeper portion of the trough of the lake1 thus producing a waste which would partly counteract the forces of accumulation at the south end4 ,the answer is found in the fact that the south end of ,lake ,michigan is closed1 and that the currents set in motion by the wind are such that there is no off-shore motion sufficient to move sand1 and1 as a matter of fact1 dredgings show that the sand is limited to the vicinity of the shore4 ,by comparing the eroded cliffs upon ,michigan and the other ,great ,lakes with what occurs in similar situations about the glacial ,lake ,agassiz1 we obtain an interesting means of estimating the comparative length of time occupied by the ice-front in receding from the ,canadian border to ,hudson ,bay4 ,as we have seen1 ,lake ,agassiz occupied a position quite similar in most respects to ,lake ,michigan4 ,its longest diameter was north and south1 and the same forces which have eroded the cliffs of ,lake ,michigan and piled up sand-dunes at its southern end would have produced similar effects upon the shores of ,lake ,agassiz1 had its continuance been anywhere near as long as that of the present ,lake ,michigan has been4 ,but1 according to ,mr4 ,upham1 who has most carefully surveyed the whole region1 there are nowhere on the shores of the old ,lake ,agassiz any evidence of eroded cliffs at all to be compared with those found upon the present ,great ,lakes1 while there is almost an entire lack of sand deposits about the south end such as characterise the shore of ,lake ,michigan4 ,the great tracts of dunes about the south end of ,lake ,michigan belong1 as ,upham well observes1 wholly to beach accumulations1 being sand derived from erosion of the western and eastern shores of the lake4444 ,but none of the beaches of our glacial lakes are large enough to make dunes like those on ,lake ,michigan1 though the size and depth of ,lake ,agassiz1 its great extent from north to south1 and the character of its shores1 seem equally favorable for their accumulation4 ,it is thus again indicated that the time occupied by the recession of the ice-sheet was comparatively brief4,,eh ,footnote ,,eh3 ,proceedings of the ,boston ,society of ,natural ,history1 vol4 xxiv1 p4 #ded2 ,upham's ,glacial ,lakes in ,canada1 in ,bulletin of the ,geological ,society of ,america1 vol4 ii1 p4 #bdh4 ,from ,mr4 ,upham's conclusions it would seem that if ten thousand years be allowed for the post-glacial existence of ,lake ,michigan1 one tenth of that period would be more than sufficient to account for the cliffs1 deltas1 beaches1 and other analogous phenomena about ,lake ,agassiz4 ,in other words1 the duration of ,lake ,agassiz could not have been more than a thousand years1 which gives us a measure of the rate at which the recession of the ice-front went on after it had withdrawn to the international boundary4 ,the distance from there to the mouth of ,nelson ,river is about #fjj miles4 ,the recession of the ice-front over that area proceeded1 therefore1 at the average rate of about half a mile per year4 ,there are many evidences that the main period of glaciation west of the ,rocky ,mountains was considerably later than that in the eastern part of the continent4 ,a portion of the facts pointing to this conclusion have been well stated by ,mr4 ,george ,f4 ,becker1 of the ,united ,states ,geological ,survey4 ,no one1 he says1 who has examined the glaciated regions of the ,sierra can doubt that the great mass of the ice disappeared at a very recent period4 ,the immense areas of polished surfaces fully exposed to the severe climate of say from #g1jjj to #ab1jjj feet altitude1 the insensible erosion of streams running over glaciated rocks1 and the freshness of erratic boulders are sufficient evidence of this4 ,there is also evidence that the glaciation began at no very distant geologic date4 ,as ,professor ,whitney pointed out1 glaciation is the last important geological phenomenon and succeeded the great lava flows4 ,there is also much evidence that erosion has been trifling since the commencement of glaciation1 excepting under peculiar circumstances4 ,east of the range1 for example1 at ,virginia ,city1 andesites which there is every reason to suppose preglacial have scarcely suffered at all from erosion1 so that depressions down which water runs at every shower are not yet marked with water-courses1 while older rocks1 even of ,tertiary age and close by1 are deeply carved4 ,the rainfall at ,virginia ,city is1 to be sure1 only about ten inches1 so that rock would erode only say one third as fast as on the ,california coast2 but even when full allowance is made for this difference1 it is clear that these andesites must be much younger than the commencement of glaciation in the northeastern portion of the continent as usually estimated4 ,so1 too1 the andesites near ,clear ,lake1 in ,california1 though beyond a doubt preglacial1 have suffered little erosion1 and one of the masses1 ,mount ,konocti 7or ,uncle ,sam71 has nearly as characteristic a volcanic form as ,mount ,vesuvius4,,ei ,footnote ,,ei3 ,bulletin of the ,geological ,society of ,america1 vol4 ii1 pp4 #aif1 #aig4 ,this view of ,mr4 ,becker is amply sustained by many other obvious facts1 some of which may be easily observed by tourists who visit the ,yosemite ,park4 ,the freedom of the abutting walls of this caon from talus1 as well as the freshness of the glacial scratches upon both the walls and the floor of the tributary caons1 all indicate a lapse of centuries only1 rather than of thousands of years1 since their occupation by glacial ice4 ,the freshness of the high-level terraces surrounding the valleys of ,great ,salt ,lake1 in ,utah1 and of ,pyramid and ,north ,carson ,lakes1 in ,nevada1 and the small amount of erosion which has taken place since the formation of these terraces1 point in the same direction--namely1 to a very recent date for the glaciation of the ,pacific coast4 ,we have already detailed the facts concerning the formation of these terraces and the evidence of their probable connection with the ,glacial period4 ,it is sufficient1 therefore1 here to add that1 according to ,mr4 ,russell and ,mr4 ,gilbert 7two of the most eminent members of the ,united ,states ,geological ,survey1 who have each published monographs minutely embodying the results of their extensive observations in this region71 the erosion of present streams in the beds which were deposited during the enlargement of the lakes is very slight1 and the modification of the shores since the formation of the high terraces has been insignificant4 ,according to ,mr4 ,gilbert3 ,the ,bonneville shores are almost unmodified4 ,intersecting streams1 it is true1 have scored them and interrupted their continuity for brief spaces2 but the beating of the rain has hardly left a trace4 ,the sea-cliffs still stand as they first stood1 except that frost has wrought upon their faces so as to crumble away a portion and make a low talus at the base4 ,the embankments and beaches and bars are almost as perfect as though the lake had left them yesterday1 and many of them rival in the symmetry and perfection of their contours the most elaborate work of the engineer4 ,there are places where boulders of quartzite or other enduring rock still retain the smooth1 glistening surfaces which the waves scoured upon them by clashing against them the sands of the beach4 ,when this preservation is compared with that of the lowest ,tertiary rocks of the region--the ,pliocene beds to which ,king has given the name ,humboldt--the difference is most impressive4 ,the ,pliocene shore-lines have disappeared4 ,the deposits are so indurated as to serve for building-stone4 ,they have been upturned in many places by the uplifting of mountains4 ,elsewhere they have been divided by faults1 and the fragments1 dissevered from their continuation in the valley1 have been carried high up on the mountain-flanks1 where erosion has carved them in typical mountain forms4444 ,the date of the ,bonneville flood is the geologic yesterday1 and1 calling it yesterday1 we may without exaggeration refer the ,pliocene of ,utah to the last decade2 the ,eocene of the ,colorado basin to the last century1 and relegate the laying of the ,potsdam sandstone to prehistoric times4,,ej ,footnote ,,ej3 ,second ,annual ,report of the ,united ,states ,geological ,survey1 p4 #ahh4 ,mr4 ,russell adds to this class of evidence that of the small extent to which the glacial stri have been effaced since the withdrawal of the ice from the borders of these old lakes3 ,the smooth surfaces are still scored with fine1 hair-like lines1 and the eye fails to detect more than a trace of disintegration that has taken place since the surfaces received their polish and striation4444 ,it seems reasonable to conclude that in a severe climate like that of the high ,sierra it 7the polish7 could not remain unimpaired for more than a few centuries at the most4,,ek ,footnote ,,ek3 ,see also ,mr4 ,upham in ,american ,journal of ,science1 vol4 xli1 pp4 #da1 #ea4 ,europe does not seem to furnish so favourable opportunities as ,america for estimating the date of the ,glacial period2 still it is not altogether wanting in data bearing upon the subject4 ,some of the caves in which palolithic implements were found associated with the bones of extinct animals in southern ,england contain floors of stalagmite which have been thought by some to furnish a measure of the time separating the deposits underneath from those above4 ,this is specially true in the case of ,kent's ,cavern1 near ,torquay1 which contains two floors of stalagmite1 the upper one almost continuous and varying in thickness from sixteen inches to five feet1 the lower one being in places twelve feet thick1 underneath which human implements were found4 ,but it is difficult to determine the rate at which stalagmite accumulates4 ,as is well known1 this deposit is a form of carbonate of lime1 and accumulates when water holding the substance in solution drops down upon the surface1 where it is partially evaporated4 ,it then leaves a thin film of the substance upon the floor4 ,the rate of the accumulation will depend upon both the degree to which the water is saturated with the carbonate and upon the quantity of the water which percolates through the roof of the cavern4 ,these factors are so variable1 and so dependent upon unknown conditions in the past1 that it is very difficult to estimate the result for any long period of time4 ,occasionally a quarter of an inch of stalagmite accretion has been known to take place in a cavern in a single year1 while in ,kent's ,cavern1 over a visitor's name inscribed in the year #afhh1 a film of stalagmite only a twentieth of an inch in thickness has accumulated4 ,if1 therefore1 we could reckon upon a uniformity of conditions stretching indefinitely back into the past1 we could determine the age of these oldest remains of man in ,kent's ,hole by a simple sum in arithmetic1 and should infer that the upper layer of stalagmite required #bdj1jjj years1 and the lower #egf1jjj years1 for their growth1 which would carry us back more than #gjj1jjj years1 and some have not hesitated to affix as early a date as this to these lowest implement-bearing gravels4 ,but other portions of the cave show an actual rate of accretion very much larger4 ,six inches of stalagmite is there found overlying some remains of ,romano-,saxon times which cannot be more than #b1jjj years old4 ,assuming this as the uniform rate1 the total time required for the deposit of the stalagmitic floors would still be about #gj1jjj years4 ,but1 as we have seen1 the present rates of deposition are probably considerably less than those which took place during the moister climate of the ,glacial epoch4 ,still1 even by supposing the rate to be increased fourfold1 the age of this lower stratum would be reduced to only #ab1jjj years4 ,so that1 as ,mr4 ,james ,geikie well maintains1 ,even on the most extravagant assumption as to the former rate of stalagmitic accretion1 we shall yet be compelled to admit a period of many thousands of years for the formation of the stalagmitic pavements in ,kent's ,cavern4,,el ,we should add1 however1 that there is much well-founded doubt whether the implements found in the lowest stratum were really in place1 since1 according to ,dr4 ,evans1 ,owing to previous excavations and to the presence of burrowing animals1 the remains from above and below the stalagmite have become intermingled4,,em ,footnote ,,el3 ,prehistoric ,europe1 p4 #hc4 ,footnote ,,em3 ,stone and ,flint ,implements1 p4 #ddf4 ,an attempt was made by ,m4 ,morlot in ,switzerland to obtain the chronology of the ,glacial period by studying the deltas of the streams descending the glaciated valleys4 ,he paid special attention to that of the ,tinire1 a stream which flows into ,lake ,geneva near ,villeneuve4 ,the modern delta of this stream consists of gravel and sand deposited in the shape of a flattened cone1 and investigations upon it were facilitated by a long railroad cutting through it4 ,three layers of vegetable soil1 each of which must at one time have formed the surface of the cone1 have been cut through at different depths4,,en ,in the upper stratum ,roman tiles and a coin were found2 in the second stratum1 unvarnished pottery and implements of bronze2 while in the lower stratum1 at a depth of nineteen feet from the surface1 a human skull was found1 to which ,morlot assigned an age of from #e1jjj to #g1jjj years4 ,footnote ,,en3 ,lyell's ,antiquity of ,man1 p4 #bh4 ,but ,dr4 ,andrews1 after carefully revising the data1 felt confident that the time required for the whole deposit of this lower delta was not more than #e1jjj years1 and that the oldest human remains in it1 which were about half way from between the base and the surface of the cone1 were probably not more than #c1jjj years old4 ,still1 the significance of this estimate principally arises from the relation of the modern delta to older deltas connected with the ,glacial period4 ,above this modern delta1 formed by the river in its present proportions1 there is another1 more ancient1 about ten times as large1 whose accumulation doubtless took place upon the final retreat of the ice from ,lake ,geneva4 ,no remains of man have been found in this1 but it doubtless corresponds in age with the high-level gravels in the valley of the ,somme1 in which the remains of man and the mammoth1 together with other extinct animals1 have been found4 ,we do not see1 however1 that any very definite calculation can be made concerning the time required for its deposition4 ,lyell was inclined to consider it ten times as old as the modern delta1 simply upon the ground of its being ten times as large4 ,on ,morlot's estimate of the age of the modern delta1 therefore1 the retreat of the ice whose melting torrents deposited the upper delta would be fixed at #ajj1jjj years ago1 and upon ,dr4 ,andrews's calculation1 at about #bj1jjj4 ,but it is evident that the problem is not one of simple multiplication4 ,the floods of water which accompanied the melting back of the ice from the upper portions of this valley must have been immensely larger than those of the present streams1 and their transporting power immensely greater still4 ,hence we do not see that any conclusions can be drawn from the deltas of the ,tinire to give countenance to extreme views concerning the date of the close of the ,glacial period4,,eo ,footnote ,,eo3 ,lyell's ,antiquity of ,man1 p4 #cba4 ,in the valley of the ,somme the chronological data relating to the ,glacial period1 and indicating a great antiquity for man1 have been thought to be more distinct than anywhere else in ,europe4 ,as already stated1 it is the prevalent opinion that since man first entered the valley1 in connection with the mammoth and the other extinct animals characteristic of the ,glacial period1 the trough of the ,somme1 about a mile in width and a hundred feet in depth1 has been eroded by the drainage of its present valley4 ,an extensive accumulation of peat also has taken place along the bottom of the trough of the river since it was originally eroded to its present level4 ,this substance occurs all along the bottom of the valley from far above ,amiens to the sea1 and is in some places more than thirty feet in depth4 ,the animal and vegetable remains in it all belong to species now inhabiting ,europe4 ,the depth of the peat indicates that when it was formed the land stood at a slightly higher elevation than now1 for the base of the stratum is now below the sea-level1 while the peat is of fresh-water origin1 and1 according to ,dr4 ,andrews1,,ep is formed from the vegetable accumulations connected with forest growths4 ,when1 therefore1 the country was covered with forests1 as it was in prehistoric times1 the accumulation must have proceeded with considerable rapidity4 ,this inference is confirmed by the occurrence in the peat of prostrate trunks of oak1 four feet in diameter1 so sound that they were manufactured into furniture4 ,the stumps of trees1 especially of the birch and alder1 were also found in considerable number1 standing erect where they grew1 sometimes to a height of three feet4 ,now1 as ,dr4 ,andrews well remarks1 it is evident that1 in order to prevent these stumps and prostrate trunks from complete decay1 the accumulation of peat must have been rapid4 ,from certain ,roman remains found six feet and more beneath the surface1 he estimates that the accumulation since the ,roman occupation has been as much as six inches a century1 at which rate the whole would take place in somewhat over #e1jjj years4 ,footnote ,,ep3 ,american ,journal of ,science1 ,october1 #ahfh4 ,still1 if we accept this estimate1 we have obtained but a starting-point from which to estimate the age of the high-level gravels in which palolithic implements were found2 for1 if we accept the ordinary theory1 we must add to this the time required for the river to lower its bed from eighty to a hundred feet1 and to carry out to the sea the contents of its wide trough4 ,but1 as already shown1 the ,glacial period was1 even in the north of ,france1 a time of great precipitation and of a considerable degree of cold1 when ice formed to a much greater extent than now upon the surface of the ,somme4 ,the direct evidence of this consists in the boulders mingled with the high-level gravel which are of such size as to require floating ice for their transportation4 ,in addition to the natural increase in the eroding power of the ,somme brought about by the increase in its volume1 on account of the greater precipitation in the ,glacial age1 there would also be1 as ,prestwich has well shown1 a great increase in rate through the action of ground-ice1 which plays a very important part in the river erosion of arctic countries1 and in all probability did so during the ,glacial period in the valley of the ,somme4 ,when the water is reduced to and below #cb ,fahr41 although the rapid motion may prevent freezing on the surface for a time1 any pointed surfaces at the bottom of the river1 such as stones and boulders1 will determine 7as is the case with a saturated saline solution7 a sort of crystallisation1 needles of ice being formed1 which gradually extend from stone to stone and envelop the bodies with which they are in contact4 ,by this means the whole surface of a gravelly river-bed may become coated with ice1 which1 on a change of temperature1 or of atmospheric pressure1 or on acquiring certain dimensions and buoyancy1 rises to the surface1 bringing with it the loose materials to which it adhered4 ,colonel ,jackson remarks1 in speaking of this bottom-ice1 that 'it frequently happens that these pieces1 in rising from the bottom1 bring up with them sand and stones1 which are thus transported by the current4444 ,when the thaw sets in the ice1 becoming rotten1 lets fall the gravel and stones in places far distant from those whence they came4' ,again1 ,baron ,wrangell remarks that1 'in all the more rapid and rocky streams of this district northern ,siberia the formation of ice takes place in two different manners2 a thin crust spreads itself along the banks and over the smaller bays where the current is least rapid2 but the greater part is formed in the bed of the river1 in the hollows among the stones1 where the weeds give it the appearance of a greenish mud4 ,as soon as a piece of ice of this kind attains a certain size1 it is detached from the ground and raised to the surface by the greater specific gravity of the water2 these masses1 containing a quantity of gravel and weeds1 unite and consolidate1 and in a few hours the river becomes passable in sledges instead of in boats4' ,similar observations have been made in ,america2 but instances need not be multiplied1 as it is a common phenomenon in all arctic countries1 and is not uncommon on a small scale even in our latitudes4 ,the two causes combined--torrential river-floods and rafts of ground-ice1 together with the rapid wear of the river cliffs by frost--constituted elements of destruction and erosion of which our present rivers can give a very inadequate conception2 and the excavations of the valleys must have proceeded with a rapidity with which the present rate of erosion cannot be compared2 and estimates of time founded on this1 like those before mentioned on surface denudation1 are therefore not to be relied upon4,,eq ,footnote ,,eq3 ,prestwich's ,geology1 vol4 ii1 pp4 #dga1 #dgb4 ,speaking a little later of taking the present rates of river erosion as a standard to estimate the chronology of the ,glacial period1 the same high authority remarks3 ,it no more affords a true and sufficient guide than it would be to take the tottering paces and weakened force of an old man as the measure of what that individual was1 and what he could do1 in his robust and active youth4 ,it may be right to take the effects at present produced by a given power as the known quantity1 a1 but it is equally indispensable1 in all calculations relative to the degree of those forces in past times1 to take notice of the unknown quantity1 x1 although this1 in the absence of actual experience1 which cannot be had1 can only be estimated by the results and by a knowledge of the contemporaneous physical conditions4 ,it may be a complicated equation1 but it is not to be avoided4,,er ,footnote ,,er3 ,prestwich's ,geology1 vol4 ii1 pp4 #ebj1 #eba4 ,in this country and in the north of ,france broad valleys have been excavated to the depth of from about eighty to a hundred and fifty feet in glacial and post-glacial times4 ,difficult as it is by our present experience to conceive this to have been effected in a comparatively short geological term1 it is equally1 and to my mind more1 difficult to suppose that man could have existed eighty thousand years or more1 and that existing forms of our fauna and flora should have survived during two hundred and forty thousand years without modification or change4,,es ,footnote ,,es3 ,ibid41 p4 #ecc4 ,the discussion of the age of the high-level river gravels of the ,somme and other streams in northwestern ,europe is not complete1 however1 without considering another possibility as to the mode of their deposition4 ,the conclusion to which ,mr4 ,alfred ,tylor arrived1 after a prolonged and careful study of the subject1 was that the main valleys of the ,somme and other streams in northern ,france and southern ,england were preglacial in their origin1 and that the accumulations of gravel at high levels along their margin were due to enormous floods which characterised the closing portion of the great ice age1 which he denominated the pluvial period4,,et ,the credibility of floods large enough to accomplish the results manifest in the valley of the ,somme is supported by reference to a flood which occurred on the ,mulleer ,river1 in ,india1 in #ahef1 when a stream1 which is usually insignificant1 was so swollen by a rainfall of a single day that it rose high enough to sweep away an iron bridge the bottoms of whose girders were sixty-five feet above high-water mark4 ,one iron girder weighing eighty tons was carried two miles down the river1 and nearly buried in sand4 ,the significance of these facts is enhanced by observing also that for fifteen miles above the bridge the fall of the river only averaged ten feet per mile4 ,floods to this extent are not uncommon in ,india4 ,during the ,glacial period spring freshets1 must have been greatly increased by the melting of a large amount of snow and ice which had accumulated during the winter1 and also by the formation of ice-gorges near the mouths of many of the streams4 ,it is probable1 also1 that the accumulation of ice across the northern part of the ,german ,ocean may have permanently flooded the streams entering that body of water2 for it is by no means improbable that there was a land connection between ,england and ,france across the ,straits of ,dover until after the climax of the ,glacial period4 ,in support of his theory1 ,mr4 ,tylor points to the fact that the gravel in the valley of the ,somme at ,amiens is partly derived from dbris brought down by the river ,somme and by the two rivers the ,celle and the ,arve1 and partly consists of material from the adjoining higher grounds washed in by land floods1 and that the ,quaternary gravels of the ,somme are not separated into two divisions by an escarpment of chalk parallel to the river1 but thin out gradually as they slope from the high land down to the ,somme4 ,mr4 ,tylor's reasoning seems especially cogent to one who stands on the ground where he can observe the size of the valley and the diminutive proportions of the present stream4 ,even if we do not grant all that is claimed by ,mr4 ,tylor1 it is difficult to resist the main force of his argument1 and to avoid the conclusion that the valley of the ,somme is largely the work of preglacial erosion1 and has been1 at any rate1 only in slight degree deepened and enlarged during post-,tertiary time4 ,footnote ,,et3 ,proceedings of the ,geological ,society1 ,london1 ,november #h1 #ahfg1 pp4 #ajc-abf3 ,quarterly ,journal of the ,geological ,society1 ,february #a1 #ahfi1 pp4 #eg-ajj4 ,summary4 ,in briefly summarising our conclusions concerning the question of man's antiquity as affected by his known relations to the ,glacial period1 it is important1 first1 to remark upon the changes of opinion which have taken place with respect to geological time within the past generation4 ,under the sway of ,sir ,charles ,lyell's uniformitarian ideas1 geologists felt themselves at liberty to regard geological time as practically unlimited1 and did not hesitate to refer the origin of life upon the globe back to a period of #ejj1jjj1jjj years4 ,in the first edition of his ,origin of ,species ,charles ,darwin estimated that the time required for the erosion of the ,wealden deposits in ,england was #cjf1ffb1djj years1 which he spoke of as a mere trifle of that at command for establishing his theory of the origin of species through natural selection4 ,in his second edition1 however1 he confesses that his original statement concerning the length of geological time was rash2 while in later editions he quietly omitted it4 ,meanwhile astronomers and physicists have been gradually setting limits to geological time until they have now reached conclusions strikingly in contrast with those held by the mass of ,english geologists forty years ago4 ,mr4 ,george ,h4 ,darwin1 ,professor of ,mathematics at ,cambridge ,university1 has from a series of intricate calculations shown that between fifty and one hundred million years ago the earth was revolving from six to eight times faster than now1 and that the moon then almost touched the earth1 and revolved about it once every three or four hours4 ,from this proximity of the moon to the earth1 it would result that if the oceans had been then in existence the tides would have been two hundred times as great as now1 creating a wave six hundred feet in height1 which would sweep around the world every four hours4 ,such a condition of things would evidently be incompatible with geological life1 and geology must limit itself to a period which is inside of #ajj1jjj1jjj years4 ,sir ,william ,thomson and ,professor ,tait1 of ,great ,britain1 and ,professor ,newcomb1 of the ,united ,states ,naval ,observatory1 approaching the question from another point of view1 seem to demonstrate that the radiation of heat from the sun is diminishing at a rate such that ten or twelve million years ago it must have been so hot upon the earth's surface as to vaporise all the water1 and thus render impossible the beginning of geological life until later than that period4 ,indeed1 they seem to prove by rigorous mathematical calculations that the total amount of heat originally possessed by the nebula out of which the sun has been condensed would only be sufficient to keep up the present amount of radiation for #ah1jjj1jjj years4 ,the late ,dr4 ,croll1 feeling the force of these astronomical conclusions1 thought it possible to add sufficiently to the sun's heat to extend its rule backwards approximately #ajj1jjj1jjj years by the supposition of a collision with it of another moving body of near its own size4 ,professor ,young and others have thought that possibly the heat of the sun might have been kept up by the aid of the impact of asteroids and meteorites for a period of #cj1jjj1jjj years4 ,mr4 ,wallace obtains similar figures by estimating the time required for the deposition of the stratified rocks open to examination upon the land surface of the globe4 ,as a result of his estimates1 it would appear that #bh1jjj1jjj years is all the time required for the formation of the geological strata4 ,from all this it is evident that geologists are much more restricted in their speculations involving time than they thought themselves to be a half-century ago4 ,taking as our standard the medium results attained by ,wallace1 we shall find it profitable to see how this time can be portioned out to the geological periods1 that we may ascertain how much approximately can be left for the ,glacial epoch4 ,on all hands it is agreed that the geological periods decrease in length as they approach the present time4 ,according to ,dana's estimates1,,eu the ratio for the ,palozoic1 ,mesozoic1 and ,cenozoic periods would be #ab3c3a--that is1 ,cenozoic time is but one sixteenth of the whole4 ,this embraces the whole of the ,tertiary period1 during which placental mammals have been in existence1 together with the post-,tertiary or ,glacial period1 extending down to the present time2 that is1 the time since the beginning of the ,tertiary period and the existence of the higher animals is considerably less than two million years1 even upon ,mr4 ,wallace's basis of calculation4 ,but if we should be compelled to accept the calculations of ,sir ,william ,thomson1 ,professor ,tait1 and ,professor ,newcomb1 the ,cenozoic period would be reduced to considerably less than one million years4 ,it is difficult to tell how much of ,cenozoic time is to be assigned to the ,glacial period1 since there is1 in fact1 no sharply drawn line between the two periods4 ,the climax of the ,glacial period represented a condition of things slowly attained by the changes of level which took place during the latter part of the ,tertiary epoch4 ,footnote ,,eu3 ,see revised edition of his ,geology1 p4 #ehf4 ,in order to estimate the degree of credibility with which we may at the outset regard the theory of ,mr4 ,prestwich and others1 that all the phenomena of the ,glacial period can be brought within the limits of thirty or forty thousand years1 it is important to fix our minds upon the significance of the large numbers with which we are accustomed to multiply and divide geological quantities4,,ev ,footnote ,,ev3 ,see ,croll's ,climate and ,time1 chap4 xx4 ,few people realise either the rapidity with which geological changes are now proceeding or the small amount of change which might produce a ,glacial period1 and fewer still have an adequate conception of how long a period a million years is1 and how much present geological agencies would accomplish in that time4 ,at the present rate at which erosive agencies are now acting upon the ,alps1 their dimensions would be reduced one half in a million years4 ,at the present rate of the recession of the ,falls of ,st4 ,anthony1 the whole gorge from ,st4 ,louis to ,minneapolis would have been produced in a million years4 ,a river lowering its bed a foot in a thousand years would produce a caon a thousand feet deep in a million years4 ,if we suppose the ,glacial period to have been brought about by an elevation of land in northern ,america and northern ,europe1 proceeding at the rate of three feet a century1 which is that now taking place in some portions of ,scandinavia1 this would amount to three thousand feet in one hundred thousand years1 and that is probably all1 and even more than all1 which is needed4 ,one hundred thousand years1 therefore1 or even less1 might easily include both the slow coming on of the ,glacial period and its rapid close4 ,prestwich estimates that the ice now floating away from ,greenland as icebergs is sufficient if accumulating on a land-surface to extend the borders of a continental glacier about four hundred and fifty feet a year1 or one mile in twelve years1 one hundred miles in twelve hundred years1 and seven hundred miles 7about the limit of glacial transportation in ,america7 in less than ten thousand years4 ,after making all reasonable allowances1 therefore1 ,prestwich's conclusion that twenty-five thousand years is ample time to allow to the reign of the ice of the ,glacial period cannot be regarded as by any means incredible or1 on a priori grounds1 improbable4 ,,appendix4 ,,the ,,tertiary ,,man4 ,by ,professor ,henry ,w4 ,haynes4 ,it must not be imagined that it is in any way proved that the ,palolithic man was the first human being that existed4 ,we must be prepared to wait1 however1 for further and better authenticated discoveries before carrying his existence back in time further than the ,pleistocene or post-,tertiary period4,,ew ,this was the position assumed more than twelve years ago by the eminent ,english geologist and archologist1 ,dr4 ,john ,evans1 and it was still maintained in his address before the ,anthropological ,section of the ,british ,association on ,september #ah1 #ahij4 ,i believe that the study of all the evidence in favor of the existence of the ,tertiary man that has been brought forward down to the present time will leave the question in precisely the same state of uncertainty4 ,footnote ,,ew3 ,a ,few ,words on ,tertiary ,man1 ,trans1 of ,hertfordshire ,nat4 ,hist4 ,soc1 vol4 i1 p4 #aej4 ,in order to establish the existence of man at such a remote period the proofs must be convincing4 ,it must be shown1 first1 that the objects found are of human workmanship2 secondly1 that they are really found as stated2 and1 thirdly1 the age of the beds in which they are found must be clearly ascertained and determined4,,ex ,these tests ,i propose to apply to the evidence for the ,tertiary man recently brought forward in ,europe1 and then to consider the significance of certain discoveries on the ,pacific coast of our own continent4 ,footnote ,,ex3 ,ibid41 p4 #adh4 ,tertiary deposits in ,europe are alleged to have supplied three sorts of evidence of this fact3 ,first1 the bones of man himself2 second1 bones of animals showing incisions or fractures supposed to have been produced by human agency2 third1 chipped flints believed to exhibit marks of design in their production4 ,a very complete survey of the question of the antiquity of man was published in #ahhc by ,m4 ,gabriel de ,mortillet1 one of its most eminent investigators1 under the title of ,le ,prhistorique4 ,in that work he subjected to a most rigid examination all the evidence for ,tertiary man1 coming under either of these three heads1 that had been brought forward up to that date4 ,the instances of the discovery of human bones in ,europe were two--at ,colle del ,vento1 in ,savona1 and ,castenedolo1 near ,brescia1 both in ,italy4 ,at the former site1 in a ,pliocene marine deposit abounding in fossil oysters and containing some scattered bones of fossil mammals1 a human skeleton was found with the bones lying in their natural connection4 ,mortillet1 however1 and many others regard this as an instance of a subsequent interment rather than as proof that the man lived in ,pliocene times4,,ey ,at ,castenedolo1 in a similar marine ,pliocene formation1 on three different occasions human skeletons have been discovered1 but in different strata4 ,one investigator has accounted for these as the result of a shipwreck in the ,pliocene period4 ,this bold hypothesis not only requires that man should have been sufficiently advanced at that very remote period to have navigated the sea1 but it calls for two shipwrecks1 at different times1 at the same point4 ,it has1 however1 since been abandoned by its author in favor of the presumption of subsequent interments1 as in the previous instance4,,ez ,footnote ,,ey3 ,this is also the opinion of ,hamy1 ,prcis de ,palontologie ,humaine1 p4 #fg4 ,professor ,le ,conte1 ,elements of ,geology 7third edition1 #ahia71 p4 #fji1 is wrong in attributing the opposite conclusion to ,hamy1 on the evidence of flint implements found in this locality4 ,footnote ,,ez3 ,bullettino di ,paletnologia ,italiana1 tome xv1 p4 #aji 7,august #ah1 #ahhi74 ,animal bones showing cuts or breaks supposed to be the work of man have been found in seventeen different localities in ,europe4 ,they can all1 however1 be accounted for as the result of natural movements or pressure of the soil acting in connection with sharp substances1 like fractured flints1 or else as having been made by the teeth of sharks1 whose fossil remains are found in great abundance in the same formation4 ,all the discoveries of flints supposed to show traces of intentional chipping are pronounced to be unsatisfactory1 with the exception of those found in three localities--,thenay 7near ,tours7 and ,puy-,courny 7near ,aurillac71 in ,france1 and ,otta1 in the valley of the ,tagus1 in ,portugal4 ,as ,european archologists at the present time are substantially in accord with ,mortillet in restricting the discussion to these three places1 ,i will follow their example4 ,but although ,mortillet believes that flints found at all these localities exhibit marks of intelligent action1 he will not admit that they are the work of man4 ,he attributes them to an intelligent ancestor of man1 whom he calls by the name of anthropopithecus1 or the precursor of man4 ,of this creature he distinguishes three different species1 named respectively after the discoverers of the flints in the three localities just mentioned4 ,the precursor1 however1 has found up to this time only a very limited acceptance among men of science1 although a few believe in him on purely theoretical grounds4 ,the discussion generally turns upon the question whether these flints were chipped intentionally or are the result of natural causes2 and also upon the determination of the geological age of the formations in which they are found4 ,illustration3 ,fig4 #ajh4--;,flint flakes collected by ,abb ,bourgeois from ,miocene strata at ,thenay 7after ,gaudry74 ,natural size4 ,i visited ,thenay1 the most celebrated of these three localities1 in #ahgg1 and had the advantage of studying the question there under the guidance of the late ,abb ,bourgeois1 the discoverer of the flints1 and one of the most prominent advocates of the ,tertiary man4 ,this was the year before he died1 and he showed me at the time his complete collection1 and gave me several of the objects he had discovered4 ,geologists are agreed in assigning the deposits in which they occur to the lower ,miocene or middle ,tertiary period1 which restricts the discussion to the character of the flints themselves4 ,the accompanying woodcut,,fa gives some indication of their appearance1 although it is misleading1 because the long figure resembling a flint knife is intended to represent a solid nucleus4 ,none of these objects1 however1 ought to be called flints flakes1 as very few1 if any1 flakes showing the bulb of percussion1 always seen upon them1 have been discovered in the ,tertiary deposits at ,thenay1,,fb although ,i have found them there myself upon the surface4 ,the three other figures would be classed by archologists as piercers1 as ,bourgeois has himself designated them1 and are also solid objects4 ,many of the ,thenay flints exhibit a crackled appearance1 due to the action of heat4 ,on this account ,mortillet maintains that they were splintered by fire1 and not formed by percussion1 the usual method by which flint implements were fabricated in the stone age4 ,the ,thenay objects are all of very small dimensions1 and are so absolutely unlike the large1 rudely-chipped axes of the ,chellean type1 found in so many different parts of the world1 and generally accepted as the implement used by ,palolithic man1 that the question naturally suggests itself1 ,what could have been the purpose for which these little implements were employed8 ,no better answer has been suggested than the ludicrous one that they were used by the hairy anthropopithecus to rid himself of the vermin with which he was infested4 ,footnote ,,fa3 ,from ,le ,conte1 op4 cit41 p4 #fjh4 ,the figures are copied from ,gaudry1 who borrowed them from the article by ,bourgeois1 ,congrs ,internat4 de ,bruxelles1 #ahgb1 p4 #hi1 pl4 ii2 and from his ,la ,question de l',homme ,tertiare4 ,revue des ,questions ,scientifiques1 #ahgg1 p4 #ae4 ,footnote ,,fb3 ,le ,prhistorique1 p4 #ia4 ,but1 leaving aside the question of their purpose1 let us consider the evidence presented by the flints themselves4 ,do they exhibit the unmistakable traces of intentional chipping produced by a series of slight blows or thrusts1 delivered in regular succession and in the same direction1 with the result of forming a distinctly marked edge8 ,and does the appearance of the action of fire upon their surface imply the intervention of intelligence8 ,to both questions ,m4 ,adrien ,arcelin1 the well-known geologist of ,mcon1 has given very sufficient replies in the negative4 ,he has discovered numerous objects of precisely similar appearance in ,eocene deposits in the neighborhood of ,mcon4,,fc ,but1 instead of pushing man back on this account so much further into the past1 he accounts for the marks of chipping to be seen on many of these objects as the result of the accidental shocks of one stone against another in the countless overturnings and movements to which the strata have been subjected during the long ages of geological time4 ,he gives photographs of some of these objects1 which are to me entirely convincing1 and describes how he has surprised ,nature in the very act of fabricating them in an abandoned quarry worked in an ,eocene deposit4 ,he thinks the crackled surfaces can be readily explained as the result of atmospheric action1 or of hot springs charged with silex4 ,numerous examples of similar changes in the surface of flint1 that have been noticed by himself and others in different localities1 are instanced4 ,even if some have been caused by fire1 this does not necessarily imply the intervention of man to have produced it4 ,similar discoveries have also been made by ,m4 d',ault de ,mesnil1 at ,thenay1 in ,eocene deposits1,,fd and by ,m4 ,paul ,cabanne1 in the ,gironde4,,fe ,my own opinion1 based upon the experience of many years spent in the study of flints broken naturally as well as artificially1 and upon a careful examination of ,bourgeois's collections1 is that the so-called ,thenay flints are the result of natural causes4 ,footnote ,,fc3 ,matriaux pour l',histoire ,prim1 et ,nat4 de l',homme1 tome xix1 p4 #aic4 ,footnote ,,fd3 ,matriaux1 ibid41 p4 #bdf4 ,footnote ,,fe3 ,id41 tome xxii1 p4 #bje4 ,the second locality where flints alleged to display marks of human action have been found is the vicinity of ,aurillac1 in the ,auvergne1 especially on the flanks of a hill called ,puy-,courny4 ,they occur in a conglomerate of the upper ,miocene period1 and are consequently much later than the ,thenay flints4 ,in this conglomerate1 in #ahfi1 ,m4 ,tardy discovered a worked flint flake which has every appearance of being artificial4,,ff ,mortillet1 however1 says that it was found in the upper surface of the deposit1 where there may easily have been a mingling with the ,quaternary formation2 and it certainly resembles worked flakes1 which are not uncommon in the ,quaternary4 ,the geological determination of the find may consequently be regarded as uncertain4 ,footnote ,,ff3 ,see ,matriaux1 tome vi1 p4 #id4 ,s4 ,reinach1 however1 ,description ,raison4 du ,muse de ,saint-,germain-en-,laye1 i1 p4 #ajg1 n4 #h1 calls it gravure inexacte4 ,the flints discovered at ,puy-,courny by ,m4 ,barnes are of small dimensions1 and have all been produced by percussion4 ,many of them are said to bear some resemblance to pointed flakes of artificial origin1 and one has been figured1 probably selected for its excellence4,,fg ,it is by no means convincing to me1 and ,i am not at all surprised that so many archologists question the artificial character of these objects1 which exhibit a great variety of forms4 ,upon this point ,rames does not profess to be qualified to pronounce judgment1 limiting himself solely to the geological questions4 ,he argues1 however1 that the fact that all the objects supposed to be artificial are made of the best qualities of flint1 of which implements are ordinarily made1 although fragments of inferior quality are abundant in the same formation1 implies the intervention of man's judgment in making the selection4 ,but ,m4 ,boule shows that this is merely the result of the erosion of an ancient river1 which operated only upon the upper beds1 in which alone the better qualities of flint are to be found2 and ,rames has accepted this explanation4,,fh ,the flints of ,puy-,courny seem to fall within the same category as those of ,thenay4 ,they are the product of denudation1 have travelled long distances1 and have been subjected to the action of powerful agents4 ,these causes are sufficient to account for the shocks of which they show the traces1 and to explain the production of splinters arising therefrom4 ,footnote ,,fg3 ,matriaux1 tome xviii1 p4 #djj4 ,footnote ,,fh3 ,revue d',anthropologie 7third series71 tome iv1 p4 #bag4 ,the last locality in which flints claimed to have been manufactured by the ,tertiary man are supposed to have been discovered is the so-called desert of ,otta1 in the valley of the ,tagus1 not far from ,lisbon4 ,the formation there is a lacustrine deposit of great thickness1 belonging to the upper ,miocene1 and abounding in flint4 ,here1 during the course of twenty years1 ,m4 ,ribeiro discovered1 but mostly upon the surface1 a large number of flakes of flint and quartzite4 ,after much debate in regard to them1 ninety-five of them were finally sent by him to ,paris1 in #ahgh1 and placed in the archological department of the great exposition4 ,there they were to be submitted to the judgment of the assembled prehistoric archologists of all nationalities1 many of whom1 including the writer1 availed themselves of the opportunity of carefully studying them4 ,the judgment of ,mortillet is that twenty-two specimens exhibited unmistakable traces of intentional chipping1 in which opinion ,i entirely concur4 ,only nine1 however1 were represented as coming from the ,miocene1 some of which showed on their surface an incrustation of grit1 which was claimed as proof of their origin4 ,but the opinion was freely expressed that1 even if they really came from the ,miocene deposits1 they might have penetrated into them from the surface1 through cracks1 and thus have become so incrusted4 ,it was accordingly resolved to hold the next international congress of prehistoric archologists at ,lisbon1 in #ahhj1 mainly for the purpose of settling this question1 if possible1 by an investigation conducted upon the spot4 ,in the course of a visit made at that time to ,otta1 several artificial specimens were found on the surface by different searchers1 but ,professor ,bellucci1 of ,perugia1 was fortunate enough to discover a flint flake in situ1 still so closely imbedded in the deposit that it required to be detached by a hammer4 ,there is no question that this object was actually found in a ,miocene deposit1 but unfortunately it belongs to the doubtful category of external flakes1 which1 although they exhibit the bulb of percussion1 have no other sure indication that they are the work of man4,,fi ,as such bulbs can be produced by natural causes1 some stronger proof than this of the existence of ,tertiary man is demanded4 ,footnote ,,fi3 ,it has been figured by ,bellucci1 ,archivio per l',anthropologia e la ,etnologia di ,firenze1 tome xi1 p4 #ab1 tav4 iv1 fig4 #b4 ,to me it possesses no value as evidence4 ,these are all the localities in ,europe claimed by ,mortillet to have furnished such evidence1 but he thinks a strong confirmation of it is afforded by certain discoveries made in the auriferous gravels of ,california4 ,i will not occupy space here in repeating arguments ,i have brought forward elsewhere to show the utter insufficiency of this evidence to prove the existence of man on the ,pacific coast of our continent during the ,pliocene period1,,fj ,they may all be summed up in the words of ,le ,conte3 ,the doubts in regard to this extreme antiquity of man are of three kinds1 viz43 #a4 ,doubts as to the ,pliocene age of the gravels--they may be early ,quaternary4 #b4 ,doubts as to the authenticity of the finds--no scientist having seen any of them in situ4 #c4 ,doubts as to the undisturbed conditions of the gravels1 for auriferous gravels are especially liable to disturbance4 ,the character of the implements said to have been found gives peculiar emphasis to this last doubt1 for they are not ,paleolithic1 but ,neolithic4,,fk ,the question has been raised whether this archological objection is applicable to the stone mortars1 numerous examples of which have been found in the gravels1 some of them quite recently4,,fl ,if the evidence brought forward by ,professor ,whitney and others were limited to these mortars1 it might very well be claimed that they are neither ,palolithic nor ,neolithic2 that the smoothness of their surface is owing to their having been hollowed out of pebbles that have been polished and worn by natural forces4 ,but ,professor ,whitney has cited numberless instances of spear-heads1 arrow-heads1 discoidal stones1 stone beads1 and a hatchet that have been found under precisely similar conditions as the mortars4 ,so ,mr4 ,becker has recently produced an affidavit of a certain ,mr4 ,neale that in a tunnel run into the gravel in #ahgg between two hundred and three hundred feet beyond the edge of the solid lava1 he saw several spear-heads nearly one foot in length4,,fm ,now it cannot be questioned that such objects as these clearly belong to the ,neolithic period1 which does not imply that all the objects used at that time were polished1 but that together with chipped implements polished stone implements were also used4,,fn ,no archologist will believe that1 while ,palolithic man has not yet been discovered in the ,tertiary deposits of western ,europe1 the works of ,neolithic man have been found in similar deposits in western ,america4 ,peculiar difficulties seem to surround the evidence brought forward in support of such an assumption4 ,we are told by ,professor ,whitney that a stone mortar was found standing upright1 and the pestle was in it1 in its proper place1 just as it had been left by the owner4 ,he fails1 however1 to explain how this was brought about in a gravel deposit supposed to have been laid down by great floods of water4 ,so1 when ,mr4 ,neale swears that he saw fifteen years ago in the same gravels spear-heads a great deal larger than those known to archologists1 may we not ask whether reliance can be placed on the memory of witnesses who testify to impossibilities to justify conclusions that rest upon such testimony8 ,i think we shall have to wait for further and better evidence than this before we are called upon to admit that the existence of the ,tertiary man upon our ,pacific coast has been established4 ,footnote ,,fj3 ,the ,prehistoric ,archology of ,north ,america1 ,narrative and ,critical ,history of ,america1 vol4 i1 pp4 #hej-cef4 ,footnote ,,fk3 ,le ,conte1 op4 cit41 p4 #fad4 ,footnote ,,fl3 ,professor ,george ,frederick ,wright1 ,prehistoric ,man on the ,pacific ,coast1 ,atlantic ,monthly1 ,april1 #ahia1 p4 #eab2 ,table ,mountain ,archology1 ,nation1 ,may #ba1 #ahia1 p4 #dai4 ,footnote ,,fm3 ,antiquities from under ,tuolome ,table ,mountain in ,california1 ,bulletin of the ,geological ,society of ,america1 vol4 ii1 p4 #aib4 ,footnote ,,fn3 ,le ,conte1 op4 cit41 p4 #fjg4 ,,index4 ,aar ,glacier1 #aa1 #dc1 #acb4 ,abbeville1 ,france1 #bea1 #bfc4 ,abbott1 ,c4 ,c1 cited1 #bdb1 #bde4 ,adams1 ,charles ,francis1 cited1 #big4 ,adhmar1 cited1 #cjg1 #caj4 ,africa1 ancient glaciers of1 #aia4 ,agassiz1 ,louis1 cited1 #i1 #aa1 #dc1 #abh1 #bda4 ,ailsa ,crag1 #afg1 #afh4 ,akron4 ,ohio1 #bbj1 #bba4 ,alaska1 #a1 #bb1 #bc et seq41 #dg1 #bab1 #bhc2 climate of1 #bia1 #cjb4 ,aletsch ,glacier1 #i1 #baa1 #bda4 ,alleghany ,valley1 #bjf1 #bad2 terraces in1 #bbi4 ,alpine glaciers1 existing1 #i-aa1 #dc et seq42 size and number of1 #i2 depth of1 #aa2 velocity of1 #dc et seq42 ancient1 #eh-fj1 #aca-acf2 advance and retreat of1 #aaf4 ,alps1 #a1 #i-aa1 #dc et seq41 #eh et seq41 #ia1 #aca et seq41 #baa2 age of1 #cbh4 ,altaville1 ,cal1 #bif4 ,amazon ,valley1 temperature of1 #caf4 ,amherst1 ,ohio1 glacial marks near1 #eb4 ,amiens1 ,france1 implements from1 #beb1 #bfc et seq42 terraces at1 #cfj4 ,andes1 #ag1 #ccj2 age of1 #cbh4 ,andover1 ,mass41 #gg et seq41 #cde4 ,andrews1 cited1 #cde1 #cdg1 #ced1 #cef4 ,animals1 extinct1 associated with man in eastern ,america1 #bfb2 in ,france1 #bfc2 in ,england1 #bfd et seq42 in ,wales1 #bgb2 in ,belgium1 #bgg et seq42 summary concerning1 #bha-bic4 ,animals1 relics of1 in loess1 #ahh4 ,antarctic ,continent1 existing glaciers of1 #a1 #ah et seq4 ,arcy1 ,belgium1 grotto at1 #bgi4 ,arenig ,mawr1 ,wales1 #aej1 #aea1 #agb4 ,argillite implement1 face and side view of1 #bdg1 #bei4 ,arnhem1 ,holland1 moraine at1 #aha4 ,asia1 existing glaciers in1 #ad et seq42 ancient glaciers of1 #aij4 ,assiniboine ,river1 #bbh4 ,astronomical theories of the ,glacial period1 #cjc et seq4 ,atlantic ,ocean1 #cad4 ,aurillac1 supposed flint-chips near1 #cfg1 #cgj4 ,australia1 ancient glaciers of1 #abf1 #aib4 ,austria1 existing glaciers of1 #i4 ,auvergne1 #acf4 ,babbitt1 ,miss ,f4 ,e41 cited1 #bec1 #bed1 #bee4 ,bakewell on age of ,niagara gorge1 #ccg4 ,baldwin1 ,c4 ,c1 #bea4 ,baldwin1 ,p41 #be4 ,ball1 cited1 #caj1 #cag4 ,baltic ,sea1 #abi4 ,barnsley1 ,england1 #aee4 ,bates1 cited1 #bjd4 ,bear1 #bgj1 #bhg1 #bij4 ,bear1 grizzly1 #bgj1 #bhh4 ,beaver1 #bhi4 ,beaver ,creek1 ,pa41 #bje1 #bcj1 #bcb4 ,becker1 cited1 #bif1 #cjj1 #cdi4 ,bedford1 ,england1 #bfe4 ,beech ,flats1 ,ohio1 terrace at1 #bag4 ,belgium1 human relics in glacial terraces in1 #bfd2 caverns of1 #bgd4 ,bell1 cited1 #aji1 #aag2 on unity of the ,glacial period1 #aaj4 ,bellevue1 ,pa41 glacial terrace on the ,ohio at1 #bag4 ,bellucci1 cited1 #cgb4 ,ben ,nevis1 #bdj4 ,bernese ,oberland1 #i1 #ei1 #aca1 #acb4 ,big ,stone ,lake1 #bjh1 #bbf4 ,birmingham4 ,england1 #aej4 ,bishop1 cited4 #cjf4 ,bison1 #bfb1 #bgj1 #bga1 #bgh1 #bhi4 ,black ,forest1 the1 #acf4 ,black ,river1 ,ohio1 #cdc4 ,black ,sea1 #bch4 ,blanc1 ,mont1 #a1 #i-aa1 #acb1 #baa4 ,blandford1 cited1 #cab4 ,boone ,county1 ,ky41 glacial deposits in1 #bab4 ,boston1 scratched stone from till of1 #ed2 drumlins in the vicinity of1 #ge4 ,boston ,society of ,natural ,history1 #bif4 ,boulder-clay4 7,see ,till47 ,boulders1 disintegrated1 #eg1 #ga4 ,boulders1 distribution of1 in ,new-,england1 #eg1 #fj1 #fa1 #fi et seq42 in ,switzerland1 #eh et seq41 #acc4 ,boulders1 transportation of1 in ,pennsylvania1 #eg1 #fa1 #he2 in ,new ,hampshire1 #fj1 #ga2 in ,kentucky1 #fc1 #ig2 in ,ohio1 #fd1 #gb2 in ,rhode ,island1 #fg2 in ,massachusetts1 #fi et seq42 in ,connecticut1 #ga1 #gb2 in ,new ,jersey1 #hc2 in ,illinois1 #ig4 ,bourgeois1 ,abb1 cited1 #cfg4 ,bridgenorth1 ,england1 #aej4 ,bridlington1 ,england1 #aef1 #aeh4 ,bristol ,channel1 #ach1 #agh4 ,british ,columbia1 #a1 #bc1 #aba et seq41 #aid1 #aih4 ,british ,isles1 ancient glaciers of1 #acf-aha2 preglacial level of land in1 #aci-ada2 preglacial climate in #ada1 #adb2 great glacial centres-- ,wales1 #adc2 ,ireland1 #adc2 ,galloway1 #add2 ,lake ,district1 #add2 ,pennine ,chain1 #add2 confluent glaciers-- ,irish ,sea ,glacier1 #ade-aec2 ,solway ,glacier1 #aec-aeh2 ,east ,anglian ,glacier1 #aeh2 ,isle of ,man1 #afd-afg2 the so-called ,great ,submergence1 #afg-ahj2 dispersion of erratics of ,shap granite1 #ahj1 #aha2 drainage of1 #bch2 caverns of1 #bfg2 climate of1 #cad4 ,brixham ,cave1 #bfg et seq4 ,bromsgrove1 ,england1 #aej4 ,brooklyn1 ,n4 ,y41 #ff1 #fg4 ,brown1 on glaciers of ,greenland1 #dj1 #da4 ,brown's ,valley1 #bbf4 ,bruce1 skull of1 #bgf4 ,buried forests in ,america1 #ajg et seq4 ,buried outlets and channels1 #aii-baj2 of ,lake ,erie1 #bja1 #ccc2 of ,lake ,huron1 #bjb2 of ,lake ,ontario1 #bjb2 of ,lake ,superior1 #bjc2 of ,lake ,michigan1 #bjc2 in southwestern ,ohio1 #bjc2 near ,cincinnati1 #bjc2 near ,louisville1 ,ky41 #bje2 in the ,tuscarawas ,valley1 #bje2 in the valley of the ,beaver1 #bje2 of oil ,creek1 #bje2 in the valley of the ,alleghany1 #bjf2 of ,chautauqua ,lake1 #bjg2 near ,minneapolis1 #bjh4 ,burton1 ,england1 #afd4 ,busk1 cited1 #bfg4 ,buttermere1 ,england1 #aec1 #afh4 ,cache ,valley1 ,utah1 #bcc4 ,cae ,gwyn ,cave1 #adh1 #bga et seq41 #bhj4 ,caithness1 ,scotland1 #ahj4 ,calaveras skull1 #bie1 #cjj4 ,california1 #ba1 #abd1 #bha1 #bhg1 #bid1 #ceh1 #cgb4 ,cambridgeshire1 ,england1 #aeh4 ,canada1 #id1 #ie4 ,canstadt1 man of1 #bgi4 ,canton1 ,ohio1 #bcb4 ,cape ,st4 ,roque1 #ca #c4 ,caribbean ,sea1 #cah4 ,caribou1 #bfb4 ,carll1 cited1 #bje1 #bjg4 ,carpathian ,mountains1 #acf1 #cbh4 ,carpenter1 ,f4 ,r41 cited1 #cba1 #cbb4 ,cascade ,range1 #ba4 ,caspian ,sea1 #bch4 ,cattaraugus ,creek1 ,n4 ,y41 #bbj4 ,caucasus ,mountains1 #ae2 age of1 #cbh4 ,cave-bear1 #bfi-bga1 #bgh1 #bhj2 hyena1 #bfi1 #bgj1 #bgh2 lion1 #bfi-bga1 #bgh4 ,caverns1 ,british1 #bfg-bgd2 on the ,continent1 #bgd-bha4 ,cefn ,cave1 #adh1 #bga4 ,cenis1 ,mont1 #ace4 ,centres of glacial dispersion1 #cjd et seq41 #cbc et seq41 #cbh2 in ,america1 #aac1 #aba2 in ,europe1 #abi et seq42 in the ,british ,isles1 #adb et seq4 ,cevennes1 #acf4 ,chamberlin1 ,t4 ,c1 terminal moraine of second ,glacial epoch1 #ic1 #ih et seq42 on driftless area1 #ajb1 #ajc2 cited1 #aaj1 #bah1 #bbi1 #cjg2 on ,cincinnati ice-dam1 #bah4 ,chamois1 #bhi1 #bij4 ,chamouni1 #acb4 ,charpentier1 #i1 #ei4 ,chasseron1 #eh1 #acb4 ,chautauqua ,lake1 buried outlet of1 #bjg4 ,chenango ,river1 #bbj4 ,cheshire1 ,england1 #adi1aec1agh1ahj4 ,cheyenne ,river1 #bbh4 ,chicago1 ,ill41 #cdf4 ,chimpanzee1 skull of1 #bgf4 ,chur1 #acc4 ,cincinnati1 buried channels near1 #bjc et seq42 glacial dam at1 #bab et seq42 terraces at1 #bca4 ,clarksburg1 ,w4 ,va41 #baf4 ,claymont1 ,del41 #beh et seq42 view of implement found near1 #bei4 ,claypole1 cited1 #bjj1 #bai1 #bba4 ,climate of ,glacial period1 #bia4 ,clwyd1 vale of1 #adg et seq44 #bga et seq4 ,clyde1 the1 #add4 ,collett1 cited1 #ajg4 ,colorado1 #abc1 #abd4 ,columbia deposit1 #bde1 #bed et seq4 ,columbiana ,county1 ,ohio1 #bcb4 ,comstock1 cited1 #cjg4 ,conewango ,creek1 #bcb2 ancient depth of1 #bjf4 ,connecticut1 #ga1 #gb1 #gd1 #ia4 ,conyers1 cited1 #bfe4 ,cook on subsidence in ,new ,jersey1 #aif4 ,cope1 cited1 #bhh4 ,cordilleran ,glacier1 #aba et seq4 ,corswall1 ,england1 #cab4 ,cows1 #bfh4 ,cresson1 cited1 #bea1 #beh et seq4 ,crevasses4 7,see ,fissures47 ,croll1 cited1 #cjd1 #cjg et seq41 #ccb1 #cfb4 ,cro-,magnon1 rock shelter of1 #bha4 ,cromer1 ,england1 #afj4 ,crosby1 on composition of till1 #ha et seq4 ,cross ,fell escarpment1 #aec1 #ahj4 ,culoz1 #acb4 ,cumberland1 ,england1 #adf1 #aec1 #afh1 #agc4 ,gumming1 quoted1 #aff4 ,gushing1 ,h41 #bf ,cuyahoga ,river1 #bbj1 #bba2 buried channel of1 #bjj4 ,dana1 ,professor ,j4 ,d41 on depth of ice1 #ia2 on driftless area1 #ajb2 cited1 #cbj1 #cfc4 ,danube1 ancient glaciers of the1 #abi1 #acd1 #ahh4 ,darent1 valley of1 #bfe4 ,darrtown1 ,ohio1 #ajg4 ,darwin1 ,charles1 cited1 #ag1 #abf1 #agj1 #bda1 #cfa4 ,darwin1 ,george ,g41 cited1 #cfa4 ,darwin1 ,mrs4 ,m4 ,j41 mortar owned by1 #big4 ,date of ,glacial period1 chapter on1 #ccb-cfd4 ,davidson ,glacier1 #bc4 ,davis on drumlins1 #ge4 ,dawkins1 cited1 #bch1 #bfg1 #bfi1 #bia4 ,dawson1 ,g4 ,m41 cited1 #aba2 on ice-movements1 #ig2 on oscillation of land-level1 #abe1 #abf4 ,dawson1 ,sir ,william1 on the fiord of the ,saguenay1 #aig2 cited1 #bhe4 ,dee1 the river1 #adi4 ,deeley1 quoted1 #afd4 ,delaware ,river1 #bcb1 #bdb et seq41 #bed1 #beh2 section across the1 #bde4 ,delta terrace at ,trenton1 ,n4 ,j41 #bdb et seq42 at ,beaver1 ,pa41 #bcj4 ,de ,ranee1 cited1 #bgb4 ,derbyshire1 ,england1 #bgj4 ,desor on age of ,niagara gorge1 #ccg4 ,diore1 glaciers of the1 #ace4 ,disintegration1 amount of1 near glacial margin1 #aag1 #aah4 ,diss1 ,england1 #bff4 ,dnieper1 the1 #ahe1 #ahh4 ,don1 the1 #ahe1 #ahh4 ,dora ,baltea1 #acd4 ,dover1 ,n4 ,h41 section of kame near1 #gg4 ,dover1 ,straits of1 #bch4 ,drave1 glaciers in the1 #acd4 ,drainage systems in the ,glacial period1 #cce1 #cci1 #cdj1 #cdc1 #cdd2 chapter on1 #aic-bda4 ,drayson1 cited1 #cag4 ,driftless area in the ,mississippi ,valley1 #aja1 #ajb4 ,drumlins1 description of1 #gc et seq42 view of1 #gc2 occurrence of1 in ,massachusetts1 #gc2 in ,new ,hampshire1 #gd2 in ,connecticut1 #gd2 in ,new ,york1 #gd1 #id2 in the ,british ,isles1 #gd1 #acg1 #afg4 ,dunbar1 ,scotland1 #cab4 ,dupont1 cited1 #bgi4 ,du ,quoin1 ,ill41 #ih1 #aai4 ,d',urville1 #bj4 ,dsseldorf1 #bge4 ,eagle1 ,wis41 view of kettle-moraine near1 #ii4 ,east ,anglian ,glacier1 #aeh-afd4 ,eccentricity of the earth's orbit1 #cjh4 ,eden ,valley1 #ahj4 ,eggischorn1 #baa1 #bda4 ,eguisheim1 skull found at1 #bgi4 ,elephant1 #bfe1 #bhj1 #bhb1 #bhc1 #bib4 ,elevation1 preglacial1 #aab1 #aid1 #aih2 the cause of the ,glacial period1 #aac1 #cbj-cca2 about the ,great ,lakes1 #bbd2 in the latitude of ,new ,york1 #bfa4 ,elyria1 ,ohio1 #cdb4 ,engis skull1 view of1 #bgd4 ,england4 7,see ,british ,isles47 ,enville1 ,england1 #aej4 ,erosion1 preglacial1 #aic et seq4 ,erosion in river valleys1 #aih1 #cbi1 #ccb4 ,erzgebirge1 #acf1 #aha4 ,europe1 existing glaciers in1 #i1 et seq41 #dc et seq42 ancient glaciers of1 #abi-aij2 former elevation of1 #bch2 ice-dams in1 #cfj4 ,evans1 cited1 #bfc1 #bfg1 #ced1 #cfe4 ,falconer1 cited1 #bfc4 ,falls of ,st ,anthony1 #bjj4 ,faudel1 cited1 #bgi4 ,fiesch1 ,switzerland1 #aca1 #baa4 ,filey ,brigs21 ,eng41 #aee4 ,finchley1 ,eng41 #aeh1 #aei4 ,finger ,lakes1 #id4 ,finsteraarhorn1 #i4 ,fiords1 #aid et seq42 of ,greenland1 #bab4 ,fissures in glacial ice1 #c1 #dh1 #di4 ,flamborough1 #adj1 #aef1 #aeg1 #agf4 ,florida1 #cad4 ,flower1 cited #bfc4 ,forbes1 #i1 #ch1 #dc1 #dd1 #dh4 ,forel1 ,m41 cited1 #aaf4 ,fort ,snelling1 ,mississippi gorge at1 #bjh1 #cdj et seq4 ,fort ,wayne1 ,incl41 #bbj1 #bbd4 ,foshay1 cited1 #aai4 ,fox1 #bgj1 #bhi1 #bij4 ,fraipont1 cited1 #bge et seq4 ,france1 existing glaciers of1 #ai2 ancient glaciers of1 #acf2 glacial gravels of1 #bfb et seq4 ,frankley ,hill1 ,england1 #aej4 ,franklin1 ,pa41 #bcj1 #bcb4 ,franz-,josef ,land1 #ad4 ,frederickshaab ,glacier1 #ia1 #bab4 ,frere1 cited1 #bff4 ,frickthal1 #acc4 ,frondeg1 ,wales1 #adi1 #agh4 ,gabb1 cited1 #cah4 ,galloway1 ancient glaciers of1 #add1 #ade1 #aed1 #aeg1 #afg1 #afh1 #agc4 ,garda1 ,lake1 moraine in front of1 #ace4 ,garonne1 the1 #acf1 #ahh4 ,gaudry1 cited1 #bfc4 ,geikie1 ,archibald1 cited1 #bgb1 #cab4 ,geikie1 ,james1 on kames1 #gf2 on loess1 #ahg1 #ahh2 cited1 #bia et seq41 #cjg1 #cec4 ,genesee ,river1 #bbj4 ,geological time1 #cfa et seq4 ,georgian ,bay1 #cci4 ,german ,ocean1 #abi4 ,germantown1 ,ohio1 #ajg1 #ajh4 ,germany1 ,north1 moraine in1 #aha1 #ahc2 glacial lakes in1 #bch2 ,quaternary animals in1 #bgi4 ,gietroz ,glacier1 #baa4 ,gilbert1 cited1 #bcc et seq41 #cej et seq42 on age of ,niagara gorge1 #cci4 ,glacial dispersion4 7,see ,centres of ,glacial ,dispersion47 ,glacial boundary in ,new ,england1 #fg2 in ,new ,jersey1 #hc2 in ,pennsylvania1 #hd et seq42 in ,new ,york1 #hd2 in ,ohio1 #ie1 #ajj1 #ajf2 in ,kentucky1 #if2 in ,indiana1 #if2 in ,illinois1 #if1 #ajj2 in ,kansas1 ,nebraska1 ,missouri1 ,montana1 ,south ,dakota1 #if2 in ,minnesota1 #aja2 in ,british ,isles1 #acg1 #adh1 #aej1 #aea1 #aee1 #afg2 in ,holland1 #aha2 in ,germany1 #aha1 #ahc2 in ,russia1 #aha1 #ahi4 ,glacial erosion1 #aah1 #aai1 #ahb4 ,glacial ice1 depth of1 in ,pennsylvania1 #ij et seq42 in ,connecticut1 #ia2 in ,new ,york4 #ia2 in ,greenland1 #ia2 in the ,alps1 #ia1 #aca1 #acc1 #ahb2 in ,germany1 #ahb2 in ,norway1 #ahb2 amount of1 #ccj4 ,glacial lakes in ,germany1 #bhc4 ,glacial motion1 limit of1 #b2 chapter on1 #dc-ej2 plastic theory of1 #dh4 ,glacial outlets of the ,great ,lakes1 #bbj-bbb4 ,glacial periods1 cause of1 #aac2 chapter on1 #cjb-cca2 date of1 chapter on1 #ccb-cfd4 ,glacial periods1 supposed succession of1 #ajf et seq41 #caa1 #cbd-cbf1 #ccb2 criticisms of the theory1 #aaf et seq4 ,glacial stri4 7,see ,rock-,scoring47 ,glacial terraces1 #bbi-bch2 in ,pennsylvania1 #hg et seq41 #bae1 #bag1 #bbi1 #bcj2 in ,new ,york1 #hh2 at ,beech ,flats1 ,ohio1 #bag2 at ,granville1 ,ohio1 #bbg2 on the ,minnesota ,river1 #bbh2 around ,great ,salt ,lake1 #bcc et seq42 on ,delaware ,river1 #bdc et seq42 in ,europe1 #bch-bda2 in ,ohio1 #bdi et seq42 human relics in1 #bda-bfg2 on ,delaware ,river1 #bde2 of the ,mississippi ,river1 #bed2 in ,france1 #bfc et seq41 #cfj2 in ,england1 #bfd et seq42 in ,belgium1 #bfd2 in ,spain1 #bfd2 in ,portugal1 #bfd2 in ,italy1 #bfd2 in ,greece1 #bfd4 ,glacial theory1 crucial tests of1 #fb1 #fe1 #beg1 #cjb et seq4 ,glaciation1 signs of past1 chapter on1 #ea et seq4 ,glacier ,bay1 #bd2 map of1 #be4 ,glacier1 denned1 #b2 formation of1 #c2 characterised by veins and fissures1 #c2 advance and retreat of1 #aaf2 velocity of1 in the ,alps1 #dc et seq42 in ,greenland1 #cf1 #df-dh2 in ,alaska1 #dg4 ,glaciers1 ancient1 in ,north ,america1 #ff-abh2 in ,central and ,northern ,europe1 #eh-fj1 #aca-acf2 in the ,british ,isles1 #acf-aha2 in ,northern ,europe1 #aha-aij2 in ,australia1 #abf1 #aib2 in ,asia1 #aij1 #aia2 in ,africa4 #aia1 #aib4 ,glaciers1 existing1 in the ,alps1 #i et seq41 #dc et seq42 in ,scandinavia1 #ab2 in ,spitzbergen1 ,nova ,zembla1 and ,franz-,josef ,land1 #ab2 in ,iceland1 #ad2 in ,asia1 #ad et seq42 in ,oceanica1 #af2 in ,south ,america1 #ag2 in ,antarctic ,continent1 #ah et seq42 in ,north ,america1 #bj et seq42 in ,greenland1 #cb et seq41 #df1 #dh1 #cfd4 ,glen ,roy1 parallel roads of1 #bci4 ,glutton1 #bic4 ,goat1 #bfh4 ,goffstown1 ,n4 ,h41 #gc4 ,grafton1 ,w4 ,va41 #bad4 ,grand ,haven1 ,mich41 #cdf4 ,granville1 ,ohio1 terrace at1 #bbg1 #cdc4 ,grape ,creek1 ,col41 view of moraines of1 #abc4 ,great ,bend1 ,pa41 depth of river-channel at1 #bjf4 ,great ,lakes1 depth of1 #aae2 formation of1 #aii et seq42 glacial outlets of1 #bbj-bbb2 elevation about1 #bbd4 ,great ,salt ,lake1 ,utah1 #bcc et seq41 #cej4 ,greece1 human relics in glacial terraces of1 #bfd4 ,greenland1 existing glaciers of1 #a1 #cb et seq41 #df1 #dh1cfd2 map of1 #cc2 climate of1 #cjb4 ,gross ,glockner1 #i1 #acd4 ,ground ice1 #ceg4 ,gulf of ,mexico1 #cac1 #cah4 ,gulf ,stream1 #ac1 #caa1 #cac1 #cag et seq4 ,guyot1 #i1 #eh1 #acc4 ,haas1 #af4 ,hall1 on the age of ,niagara1 #ccf4 ,hare1 #bhi4 ,harrison1 quoted1 #afg4 ,harte1 ,bret1 cited1 #bif4 ,hartz ,mountains1 #acf1 #aha4 ,hayes1 #cf4 ,haynes on ,tertiary ,man1 #cfe-cgd4 ,heald ,moor1 ,england1 #adg4 ,hebrides1 the1 #acf4 ,heim1 #i4 ,helland1 #ad1 #df-dh4 ,hennepin1 cited1 #cdj4 ,heme ,bay1 ,england1 #bfe4 ,herschel1 cited1 #caj4 ,hertfordshire1 ,england1 #aeh4 ,hicks1 ,dr4 ,,ii41 cited1 #bgb4 ,hicks1 ,l4 ,e41 cited1 #cdc4 ,himalayas1 #a1de1 #bib1 #ccj2 age of1 #cbh4 ,hingham1 ,mass41 section of kame near1 #gi4 ,hippopotamus1 #bfc1 #bfe1 #bga1 #bhj1 #bhd1 #bhe1 #bij1 #bib4 ,hitchcock1 ,c4 ,,ii41 discovery of boulders on ,mount ,washington1 #fj2 on drumlins1 #gc2 cited1 #cji1 #cac4 ,hitchcock1 ,e41 on kames1 #gg4 ,holland1 terminal moraine in1 #aha4 ,holderness1 #aeg4 ,hooker1 cited1 #aia4 ,horse1 #ahh1 #bfc1 #bfh-bgj1 #bgb1 #bgh1 #bhj1 #bhh1 #bhi4 ,horseheads1 ,n4 ,y41 #bbj4 ,horseshoe ,fall1 #ccg et seq4 ,hottentot skull1 #bgf4 ,hoxney1 ,england1 #bff4 ,hudson ,river1 preglacial channel of1 #aid et seq4 ,hugi1 #i1 #dc4 ,hungary1 ,quaternary animals in1 #bgi4 ,huxley1 cited1 #bgf1 #bgh4 ,hyena1 #bga1 #bgb1 #bhb1 #bia1 #bib4 ,ibex1 #bhi4 ,icebergs1 #ah1 #bj2 formation of1 #bh4 ,ice1 characteristics of1 #b1 #dh et seq41 #cjb et seq42 transporting power of moving1 #e4 ,ice-dams1 #baa-bbh2 in the ,alps1 #baa2 in the ,himalayas1 #baa2 in ,greenland1 #bab2 in ,alaska1 #bab2 at ,cincinnati1 #bac et seq42 across the ,mohawk1 #ib1 #bbj1 #ccd1 #cce2 in the ,red ,river of the ,north1 #bbe2 in ,europe1 #cfj4 ,iceland1 existing glaciers of1 #a1 #ad4 ,ice-pillars1 #f1 #bg4 ,ice-sheet1 retreat of1 #ccc et seq4 ,idaho1 #abb2 lava-beds of1 #big4 ,illicilliwaet ,glacier1 #bc4 ,illinois1 #if-ih1 #ajj1 #aai1 #aba1 #cde et seq4 ,indiana1 #if1 #ih1 #ajg1 #aai1 #aba4 ,indian ,ridge1 #hj4 ,iowa1 #ih1 #aja4 ,ireland1 ancient glaciers of1 #adc4 ,irish elk1 #bgj1 #bgh1 #bhh4 ,irish ,sea ,glacier1 #acg1 #ade-aec1 #afd1 #bga4 ,irthing1 valley of the1 #aec4 ,isre1 glaciers of the1 #acb4 ,isle of ,man1 #afd-afg4 ,isle of ,wight1 #bff4 ,italy1 existing glaciers of1 #i2 ancient glaciers of1 #ahe2 human relics in glacial terraces of1 #bfd2 supposed ,tertiary man in1 #cff4 ,ivrea1 #acd4 ,jackson1 cited1 #ceg4 ,jackson's ,lake1 #abc4 ,jakobshavn ,glacier1 velocity of1 #df1 #dg2 depth of1 #ia2 ice-dams of1 #bab4 ,james1 cited1 #bjd4 ,james ,river1 ,dak41 #bbh4 ,james ,river1 ,va41 #beg4 ,jamieson1 cited1 #ccj4 ,jensen1 #ia4 ,judge's ,cave1 #gb4 ,jura ,mountains1 ancient glaciers of1 #eh-fj1 #acb4 ,kames1 formation of1 #g1 #gf1 #gg2 of ,muir ,glacier1 #bi1 #cj2 in ,massachusetts1 #gg et seq42 in ,new ,hampshire1 #hj2 map of1 in ,maine1 #ha2 in ,pennsylvania1 #hg4 ,kanawha ,river1 #baf4 ,kane1 #cf-ch4 ,kansas1 #if4 ,kelly's ,island1 view of grooves on1 #ajc1 #aje4 ,kendall1 chapter by4 #acg-aha2 cited1 #bgc4 ,kent1 ,england1 #bfe4 ,kent's ,hole1 #bfg et seq41 #ceb et seq4 ,kentucky1 #fc1 #if1 #ig1 #bab2 view of boulder in1 #fc4 ,kentucky ,river1 #bad4 ,kettle-holes1 formation of1 #g1 #fh2 of ,muir ,glacier1 #bi1 #cj2 in ,new ,england1 #ff et seq41 #cdd1 #cde2 in ,pennsylvania1 #hf2 sedimentation of1 #ccc1 #cdd et seq4 ,kettle-moraine in ,wisconsin1 #ajj4 ,king1 #ba1 #cea2 implement discovered by1 #big4 ,knox ,county1 ,ohio1 #bcb4 ,kurtz1 ,nam pa image discovered by1 #big4 ,lake ,agassiz1 #abf1 #bbc1 #bbe2 continuance of1 #cdg et seq4 ,lake ,bonneville1 #bcc et seq41 #bii1 #cej et seq4 ,lake ,constance1 #fj1 #acc4 ,lake ,erie1 origin of1 #bjj et seq42 ridges around1 #bbb2 preglacial outlet of1 #bjj1 #ccc4 ,lake ,geneva during the ,glacial period1 #aca1 #acb4 ,lake ,huron1 preglacial outlet of1 #bjb2 ridges around1 #bbd4 ,lake ,itasca1 #bed4 ,lake ,lahontan1 #bcc1 #bcd4 ,lake ,michigan1 age of1 #cde et seq4 ,lake ,nipissing1 #cci4 ,lake ,ontario1 origin of1 #bja et seq4 ,lake ,traverse1 #bjh1 #bbf4 ,lake ,district1 ,england1 the1 #add4 ,lake dwellings in ,switzerland1 #bha4 ,lake ridges1 #bbb et seq4 ,lakes1 sedimentation of1 #ccc1 #cdd et seq4 ,lamplugh1 glacial observations of1 #adj1 #aif4 ,lancashire1 #aec1 #agh1 #ahj4 ,lancaster1 ,ohio1 #bcb4 ,lang1 cited1 #aaf4 ,lark1 ,england1 valley of the1 #bff4 ,lateral moraines1 #e4 ,laurentide ,glacier1 #aac et seq41 #aba1 #cba4 ,lava on the ,pacific coast of ,north ,america1 #bid1 #bih1 #cjj1 #cjf1 #cba4 ,lawrence1 ,mass41 #hj4 ,lawrenceburg1 ,ind41 #bca1 #bcb4 ,le ,conte1 cited1 #bhf1 #cbb et seq41 #ccj1 #cgb4 ,leicestershire1 ,england1 #aeh4 ,lehigh ,river1 #bdc4 ,lemming1 #bhi4 ,lenticular hills1 #gc4 ,leopard1 #bhb4 ,lesley1 cited1 #bae4 ,lesse1 ,belgium1 valley of the1 #bgi4 ,leverett1 cited1 #aja1 #bah4 ,lewis1 on transported boulders1 #eg1 #fa2 work of1 in ,pennsylvania1 #hd1 #aai2 in ,great ,britain1 #acg2 cited1 #bed et seq41 #bgc4 ,lickey ,hills1 #aea4 ,licking ,river1 #bad4 ,lige1 ,belgium1 #bgd4 ,lincolnshire1 ,england1 #aeh4 ,lindenkohl on old channel of the ,hudson1 #aie et seq4 ,lion1 #bhb1 #bic4 ,little ,beaver ,creek1 #bca1 #bcb4 ,little ,falls1 ,minn41 #bbe1 #bcb1 #beb1 #bed4 ,little ,falls1 ,n4 ,y41 buried channel near1 #bjb4 ,livingston1 ,mont41 #abb4 ,llangollen1 vale of1 #aea4 ,loess in the ,mississippi ,valley1 #ih1 #aai1 #abj2 in ,europe1 #ahf et seq4 ,lohest1 cited1 #bge et seq4 ,lombardy1 #acd4 ,london1 #aeh1 #aei1 #agh2 glacial terrace in1 #bfd4 ,long ,island1 #ff1 #fg4 ,louisville1 ,ky41 buried channel near1 #bje4 ,loveland1 ,ohio1 #bcb1 #bej4 ,lubbock1 cited1 #bfg4 ,lucerne1 #acc4 ,lyell1 on ,richmond train of boulders1 #gj2 cited1 #bci1 #bfc1 #bfg1 #bgd1 #bgf1 #bhe1 #cee1 #cfa2 on the age of ,niagara1 #ccf4 ,lyons1 #acb4 ,maack1 cited1 #cah4 ,macclesfield1 ,england1 #bgc4 ,mac,enery1 cited1 #bfg4 ,machairodus1 #bgj1 #bhb4 ,mackintosh1 quoted1 #adi1 #aej1 #agc4 ,mcon1 ,france1 #cfi4 ,mc,tarnahan1 mortar discovered1 by #big4 ,madison boulder1 #ga4 ,madisonville1 ,ohio1 #bcb1 #bej1 #bed4 ,magdalena ,bay1 #ac4 ,mahoning ,river1 #bbj4 ,maine1 #hj2 re-elevation of1 #cca4 ,malaspina ,glacier1 map of1 #ca4 ,mammoth1 #ahh1 #aij1 #bfc1 #bfe1 #bfi-bgb1 #bgh1 #bhj1 #bhc-bhe1 #bhg1 #bib1 #bic4 ,man1 relics of1 in the ,glacial period1 chapter on1 #bdb-cja2 in glacial terraces of the ,united ,states1 #bdb-bfb2 of ,europe1 #bfb-bfg2 in cave deposits of ,british ,isles1 #adh1 #bfg-bgd2 of the ,continent1 #bgd-bha2 under lava-beds of the ,pacific coast of ,north ,america1 #bid-cja2 extinct animals associated with1 #bha-bic4 ,manitoba1 #ig4 ,mankato1 ,minn41 #bbi4 ,marcilly1 skull at1 #bgi4 ,marietta1 ,ohio1 #bca4 ,marmot1 #bhi1 #bic4 ,marsh ,creek ,valley1 ,utah1 #bcc4 ,martigny1 ancient glaciers near1 #ei1 #fj1 #aca1 #baa4 ,massachusetts1 #fg et seq41 #gc1 #gg et seq41 #ha1 #cdd1 #cde4 ,mastodon1 #bfb1 #bgh1 #bhe1 #bhf4 ,mattmark ,see1 #baa4 ,maumee ,river1 #bbj4 ,mc,gee1 cited1 #bde1 #bed et seq4 ,medial moraines1 formation of1 #f2 of ,muir ,glacier1 #bg2 in ,ohio1 #ajj4 ,medlicott1 cited1 #cab4 ,medora1 ,ind41 #bcb1 #bea1 #bed4 ,menai ,straits1 #ade4 ,mentone1 skeleton of1 #bha4 ,mer de ,glace1 #aa1 #dd4 ,merjelen ,see1 #baa1 #bda4 ,mersey1 the1 #adj4 ,meteorites1 #cje4 ,metz1 cited1 #bej4 ,meuse1 valley of1 #bgd et seq4 ,miami1 the ,great1 #bjd1 #bbj4 ,miami1 the ,little1 #bca1 #bej4 ,millersburg1 ,ohio1 #bcb4 ,mills1 cited1 #bea4 ,minneapolis1 #bcb2 buried outlet near1 #bjh2 recession of falls at1 #baj1 #cdj et seq41 #cfd4 ,minnehaha1 ,falls of1 #cdb4 ,minnesota1 #aja1 #ajg1 #beb et seq42 lakes of1 #cdd4 ,minnesota ,river1 a glacial outlet1 #bjh1 #bbe1 #bbh1 #cdb4 ,miocene epoch1 animals of the1 #bhe4 ,mississippi ,river1 gorge of1 at ,fort ,snelling1 #bjh1 #cfd2 terraces on1 #bbi2 erosion by1 #cbi2 glacial drainage of1 #cce1 #cdj4 ,missouri ,coteau1 #aja1 #abf1 #bbh4 ,missouri1 #if1 #ih1 #aai4 ,moel ,tryfaen1 #ade1 #afg et seq41 #agh1 #bgc4 ,mohawk ,river1 glacial drainage of1 #ib1 #bjb1 #cce2 ice-dam across1 #bbj1 #ccd1 #cce4 ,mohegan ,bock1 #ga2 view of1 #gb4 ,monongahela ,river1 #bad et seq4 ,montaigle1 valley of the1 #bgi4 ,montana1 #if4 ,montreal1 re-elevation of1 #cca4 ,moose1 #bfb4 ,moraines1 formation of1 #f2 in ,wisconsin1 #ih-ajj2 in ,italy1 #acd1 #ace2 between ,speeton and ,flamborough1 #aef2 in ,germany1 #ahc4 ,morecambe ,bay1 #adf1 #ahj4 ,morgantown1 ,w4 ,va41 #bae4 ,morlot1 cited1 #ced4 ,mortillet1 cited1 #cff1 #cfi1 #cgb4 ,morvan1 the1 #acf4 ,moulins1 formation of1 #g4 ,mount ,shasta1 #ba4 ,mount ,washington1 #fa4 ,mueller ,glacier1 #ag4 ,muir ,glacier1 #bd et seq44 #dg1 #fh1 #bab2 view of front of1 #bf4 ,muir1 ,john1 #bd4 ,muskingum ,river1 #bbj1 #bca4 ,musk ox1 #bfb1 #bhj4 ,musk sheep1 #bhi1 #bij1 #bic4 ,nampa image1 #big et seq4 ,nansen1 #ci1 #da4 ,naulette1 jaw found at1 #bgh1 #bgi4 ,neale1 implements discovered by1 #bif1 #cgc4 ,neanderthal skull1 #bge et seq4 ,nebraska1 #if4 ,nelson ,river1 #cdi4 ,neufchtel1 #acc4 ,nevada1 #abd2 lakes of1 #bcc4 ,nv-field defined1 #c4 ,newark1 ,ohio1 #bcb4 ,newberry on the preglacial drainage of the ,hudson1 #aie et seq42 on the formation of the ,great ,lakes1 #bjb et seq42 cited1 #cbj4 ,newburg1 ,n4 ,y41 #bhf4 ,new ,comerstown1 implement from1 #bcb1 #bej1 #bea et seq41 #bed4 ,new ,england1 #eg1 #fj1 #fa1 #ia2 ancient glaciers in1 #ff-hc4 ,new ,hampshire1 #fi1 #ga1 #gd1 #hj4 ,new ,harmony1 ,ind41 #bcb4 ,new ,jersey1 #hc4 ,new ,lisbon1 ,ohio1 #bcb4 ,new ,york1 #gd1 #hd1 #hh1 #ia1 #ib et seq4 ,new ,york ,bay1 #ahd1 #aig1 #bdi4 ,new ,zealand1 #a1 #abf1 #aib1 #ccj4 ,niagara gorge1 age of1 #ccc et seq42 section of strata along the1 #ccf4 ,nile ,river1 #bhe4 ,nordenskild1 #cb1 #cd4 ,norfolk1 ,england1 #afa4 ,north ,america1 existing glaciers in1 #bj et seq4 ,north ,sea1 #bch4 ,norway1 climate of1 #cad4 ,nottingham1 ,england1 #afd4 ,nova ,zembla1 #ad4 ,oberlin1 ,ohio1 #fd1 #cdd4 ,oceanica1 existing glaciers of1 #af1 #ag4 ,ohio ,river1 glacial terrace1 #bag1 #bbi4 ,ohio1 #fd1gb1 #ie1 #ih1 #ajj1 #ajc1 #ajf1ajg-aag1 #aai1 #bag1 #bdi et seq41 #cdc1 #cdd4 ,oil ,creek1 #bje1 #bcb4 ,olmo1 skull at1 #bgi4 ,oregon1 #ba1 #abd4 ,orme's ,head1 ,little1 #adg4 ,orton1 cited1 #gb1 #ajg4 ,oscillations of land-level in ,america1 #abd et seq4 ,oswestry4 ,england1 #agc4 ,ottawa ,river1 #cci4 ,otter1 #bij4 ,ouse1 valley of the1 #bfe4 ,ox1 #bfi1 #bgj4 ,pacific coast of ,america1 #cdi4 ,pacific ,ocean1 #cah1 #cbj4 ,panama1 ,isthmus of1 #aac1 #cac1 #cad1 #cah4 ,parsimony1 law of1 #aag4 ,pasterzen ,glacier1 #acd4 ,patagonia1 #a4 ,patton1 #be4 ,payer1 #ad1 #ci4 ,peat-beds1 #fh1 #abe2 in ,ohio1 #ajg2 in ,minnesota1 #ajh2 in valley of the ,somme1 #cee et seq4 ,pembina ,river1 #bbh4 ,pengelly1 cited1 #bfg1 #bgj4 ,pennine ,chain1 glaciation of1 #acg1 #add1 #adf1 #adg1 #aed1 #agg4 ,pennsylvania1 #eg1 #fa1 #hd et seq41 #aai1 #bag4 ,perry ,county1 ,ohio1 #bcb4 ,perthes1 ,boucher de1 #bfb et seq4 ,philadelphia ,academy of ,sciences1 #bif4 ,philadelphia1 red gravel of1 #bed et seq4 ,phillips1 cited1 #bfg4 ,picardy1 glacial gravels of1 #bfb4 ,pittsburg1 ,pa41 submergence of1 #bad1 #bag1 #bcj4 ,plum ,creek1 ,ohio1 #cdd4 ,po1 valley of the1 #ace2 erosion by1 #cbh4 ,pocatello1 ,idaho1 #bcf1 #bii4 ,pocono ,mountain1 #fa4 ,poland1 #aha4 ,polynesian skull1 #bgf4 ,pomp's ,pond1 section of kettle-hole near1 #cde4 ,portageville1 ,n4 ,y41 #bbj4 ,port ,neuf ,river1 ,idaho1 #bcf4 ,portsmouth1 ,ohio1 #bca4 ,portugal1 human relics in glacial terraces of1 #bfd2 supposed ,tertiary man in1 #cfg1 #cga et seq4 ,post-glacial erosion1 #ccb et seq42 in ,ohio1 #cdc1 #cdd2 in ,illinois1 #cde et seq4 ,potomac ,river1 #bef et seq4 ,pot-holes in ,lucerne1 #acc4 ,pouchet1 cited1 #bfc4 ,precession of equinoxes1 #cjh4 ,preglacial climate in ,england1 #ada1 #adb4 ,preglacial levels in ,england1 #aci-adb4 ,prestwich1 cited1 #ahf1 #ahi1 #bfc et seq41 #bhd2 on date of ,glacial period1 #ced1 #ceg1 #cfc1 #cfd4 ,provo shore-line1 #bcg4 ,putnam1 cited1 #bej4 ,puy-,courny1 ,france1 supposed ,tertiary man at1 #cfg1 #cgj1 #cga4 ,pyramid ,lake1 #cej4 ,pyrenees1 glaciers of the1 #aa1 #acf2 ,quaternary animals of1 #bhj1 #bhb2 age of1 #cbh4 ,quaternary animals of ,california1 #bha1 #bhg2 in ,germany1 #bgi2 in ,hungary1 #bgi4 ,quatrefages1 cited1 #bgf4 ,queenston1 ,canada1 #ccc et seq4 ,rabbit1 #bhi4 ,raccoon ,creek1 #cdc2 view of glacial terrace near1 #bbg4 ,rames1 cited1 #cgj1 #cga4 ,ramsay1 cited1 #caa4 ,rappahannock ,river1 #beg4 ,rawhide ,gulch1 ,cal41 #bif4 ,recession1 rate of1 of ,falls of ,niagara1 #ccc et seq42 of ,falls of ,st4 ,anthony1 #cdj et seq41 #cfd2 of ,black ,river1 #cdb1 #cdc4 ,red deer1 #bfc4 ,red ,river of the ,north1 #bji1 #bbh1 #cdj2 ice-dam in1 #bbe4 ,regillout1 #bfc4 ,reid1 ,clement1 quoted1 #afb4 ,reid1 ,h4 ,f41 #bf1 #dg4 ,reindeer1 #ahh1 #bfb1 #bfc1 #bfi1 #bgj1 #bgh1 #bhj1 #bhg1 #bij1 #bic4 ,rhine1 ancient glaciers of the1 #abi1 #acc4 ,rhinoceros1 #ahh1 #bfc1 #bfe1 #bga1 #bgg1 #bgh1 #bhj1 #bhd1 #bhf1 #bhg1 #bib2 woolly1 #bfi1 #bgj1 #bgb1 #bhj1 #bhg4 ,rhode ,island1 #fg4 ,rhne1 ancient glaciers of1 #eh-fj1 #aca1acb1 #ahe1 #ahh2 map of1 #eh4 ,richmond1 ,mass41 train of boulders in1 #gj1 #ga4 ,rink1 ,dr41 #ce4 ,roanoke ,river1 #beg4 ,rocky ,mountains1 #cbj1 #cbb2 age of the1 #cbh4 ,rock-scorings1 cause of1 #ea et seq42 in ,new ,england1 #fi2 on islands of ,lake ,erie1 #ajc1 #ajd2 in ,pennsylvania1 #aai2 in ,ohio1 #ajc1 #aai2 in ,indiana1 #aai2 in ,illinois1 #aai2 in ,missouri1 #aai4 ,roman remains1 #cef4 ,rome1 ,n4 ,y41 #cce4 ,rosa1 ,mount1 #i1 #acd1 #baa4 ,ross1 ,sir ,j4 ,c1 #ah1 #ai1 #caa4 ,royston1 ,england1 #aee4 ,runaway ,pond1 #bjg4 ,russell1 ,i4 ,c1 exploration of ,mount ,st4 ,elias by1 #cj1 #bab2 cited1 #bcc1 #cej et seq4 ,russia1 glacial boundary in1 #aha1 #ahi2 glacial drainage of1 #bch4 ,saguenay1 fiord of the1 #aig4 ,salamanca1 ,n4 ,y41 buried channels near1 #bjf4 ,salisbury1 cited1 #ahc1 #ahd4 ,salt ,lake ,city1 #abc4 ,sandusky1 ,ohio1 section of the lake ridges near1 #bbc4 ,sandusky ,river1 #bbj4 ,sanford1 cited1 #bfg4 ,saskatchewan ,river1 #bbh4 ,saxony1 #aha4 ,scandinavia1 existing glaciers of1 #b1 #ab2 ancient glaciers of1 #abi1 #acf1 #aeg1 #aha-aij2 re-elevation of1 #cca4 ,scioto ,river1 #bca4 ,scotland4 7,see ,british ,isles47 ,seattle1 section of till in1 #ee4 ,second ,glacial period1 #ajf et seq4 ,section1 ideal1 across river bed in drift region1 #bbi4 ,sedimentation of lakes1 #ccc4 ,seine1 terraces of the1 #ahf1 #ahh1 #bfd4 ,seracs1 #d1 #e4 ,settle1 ,england1 #bgj4 ,severn1 the1 #adi-aea1 #bhe4 ,shaler1 #fg1 #bdb4 ,shap granite1 #aed1 #aeg1 #ahj4 ,ship ,rock1 #ga4 ,shone1 cited1 #ahj4 ,shoshone ,falls1 #bii4 ,shrewsbury1 ,england1 #aej4 ,shropshire1 ,england1 #adi1 #agc4 ,siberia1 #aij2 ,quaternary animals in1 #bhj1 #bhb1 #bhc1 #bij2 climate of1 #cjb1 #caf4 ,sierra ,nevada ,mountains1 #ba1 #bid1 #cja1 #cbj1 #cbb1 #cdi1 #ceb4 ,skertchly1 quoted1 #aei4 ,skipton1 #add1 #adf4 ,skull1 comparative study of1 #bgf4 ,slickenside1 #ec4 ,smock on depth of glacial ice1 #ij4 ,snake ,river ,valley1 #bcf et seq41 #bih4 ,snowdon1 #ade1 #aga4 ,snowy vole1 #bhi4 ,soleure1 #acc4 ,solferino1 #ace4 ,solway ,glacier1 #aec1 #aee1 #ahj4 ,somme1 terraces of the1 #ahf1 #bfb et seq41 #bhe1 #bhf1 #cee1 #cei et seq4 ,sonora1 ,cal41 #bid et seq4 ,south ,america1 existing glaciers of1 #ag2 ancient glaciers in1 #abf4 ,southampton1 ,england1 #bff4 ,south ,dakota1 #if1 #ih4 ,spain1 ancient glaciers of1 #acf2 human relics in glacial terraces of1 #bfd2 ,quaternary animals of1 #bhj4 ,speeton1 #adj1 #aee1 #aef4 ,spencer1 cited1 #bbd4 ,spencer1 ,n4 ,y41 #bbj4 ,spitsbergen1 #ab4 ,spy1 man of1 #bge1 #bgg4 ,st4 ,acheul1 #bfc4 ,stag1 #bhi4 ,stainmoor1 ,england1 #aed1 #aeg1 #ahj4 ,stalagmite1 rate of accumulation of1 #ceb et seq4 ,stanislaus ,river1 ,cal41 #bid4 ,st4 ,anthony1 ,falls of1 #cdj et seq41 #cfd4 ,steamburg1 ,n4 ,y41 buried channel at1 #bjf4 ,st4 ,elias1 #cj et seq41 #bab4 ,st4 ,lawrence ,river1 glacial drainage of1 #cce1 #cci4 ,st4 ,louis1 ,mo41 #aai1 #cfd4 ,st4 ,paul1 ,minn41 #bbh4 ,stone on kames in ,maine1 #hj4 ,straits of ,dover1 #cfj4 ,straits of ,gibraltar1 #bib4 ,stri1 direction of1 in ,new ,hampshire1 #fi2 in ,lake ,erie1 #ajd2 presence of1 in ,pennsylvania1 #he1 #aai2 in ,ohio1 ,indiana1 ,illinois1 and ,missouri1 #aai2 in ,stuttgart1 #bgi4 ,subglacial streams1 #bc1 #bi1 #abj4 ,submerged channels on the coasts of ,america1 #aid-aih4 ,submergence theory1 #fj-fc1 #gj4 ,subsidence of the ,isthmus of ,panama1 #aac1 #cah2 in ,mississippi ,valley1 #ic1 #aac1 #abj1 #aba2 on east coast of ,north ,america1 #bee et seq42 about the ,great ,lakes1 #bbd1 #cci2 in ,great ,britain1 #afg-aha4 ,susquehanna ,river1 glacial drainage of1 #ic1 #bcb1 #beg4 ,svartisen ,glacier1 #ac4 ,svenonius1 ,dr41 #ab4 ,sweden1 #ha4 ,switzerland1 existing glaciers of1 #i-aa2 ancient glaciers of1 #aca-acf2 lake-dwellings in1 #bha4 ,table ,mountain1 ,cal41 #bid et seq41 #cjj4 ,table of changes during the ,glacial epochs1 #cbd1 #cbe4 ,tagus1 valley of the1 #cfg1 #cga et seq4 ,tait1 cited1 #cfb4 ,tardy1 cited1 #cgj4 ,tasman ,glacier1 #af4 ,teesdale1 ,england1 #aee1 #aeg4 ,terminal moraines1 formation of1 #f2 in ,pennsylvania1 #fa1 #fb1 #he et seq42 on the southern coast of ,new ,england1 #ff et seq42 in ,ohio1 #ajf2 in ,puget ,sound1 #abb2 in ,tyghee ,pass1 #abb2 in ,italy1 #ace4 ,terminal moraines of the second ,glacial epoch1 #ic1 #ajj1 #aja1 #ajf4 ,terraces4 7,see ,glacial ,terraces47 ,tertiary animals1 #bhf4 ,tertiary man1 #cfe-cgd4 ,tertiary period1 climate of1 #aac1 #aag1 #ahb1 #cje1 #cjg4 ,teton ,mountains1 #abc4 ,texas1 ,pleistocene animals of1 #bhh4 ,thames1 ,england1 #ach1 #bfd1 #bhe4 ,thenay1 ,france1 supposed ,tertiary man in1 #cfg1 #cga2 view of flint-flakes collected at1 #cfh4 ,thompson1 #ej4 ,thomson1 cited1 #cfb4 ,till1 description of1 #ec2 composition of1 in ,massachusetts1 #ha et seq42 section of1 in ,ohio1 #ajh2 depth of1 in ,germany1 ,scandinavia1 and ,russia1 #ahb4 ,tinire ,river1 #ced4 ,titusville1 ,pa41 #bcb4 ,todd1 on forest beds and old soils1#aaj et seq42 cited1 #bbh4 ,torquay1 ,england1 #bfg4 ,trade-winds of the ,atlantic1 #cad1 #cah4 ,tremeirchon1 ,wales1 #bga4 ,trenton1 ,n4 ,j41 #hg1 #bcb1 #bdb et seq41 #bed1 #beg2 view of implement found at1 #bdg4 ,trenton gravel1 section of the1 #bdf4 ,trent1 valley of the1 #afc1 #afd4 ,trimmer1 quoted1 #adh4 ,trimingham1 ,england1 #afb4 ,trogen1 ,switzerland1 #fj4 ,trons1 ,switzerland1 #fj4 ,tuolumne ,county1 ,cal41 #bid1 #bii4 ,turin1 #ace4 ,tuscarawas ,valley1 #bbj1 #bba1 #bcb1 #bea2 buried channel in1 #bje4 ,tylor1 cited1 #cei et seq4 ,tyndall1 #dd-df1 #di4 ,tynemouth1 ,england1 #aee1 #aeg4 ,tyrol1 #acd1 #ace1 #baa4 ,tyrrell1 cited1 #aji4 ,ulm1 #acd4 ,upham1 on drumlins1 #gc2 on two ice-movements1 #ig2 cited1 #bbb1 #bec et seq41 #cja1 #cah1 #cbj et seq41 #ccj1 #cdh2 on the ,columbia gravel1 #bfa2 on date of the ,glacial period1 #cdd4 ,ural ,mountains1 #ae1 #bhj4 ,utah1 #abc2 lakes of1 #bcc4 ,utica1 ,n4 ,y41 #bbj4 ,utrecht1 moraine near1 #aha4 ,valais1 the1 #acc4 ,vegetable remains in glacial deposits1 #aag1 #abe2 in ,ohio1 #ajg1 #aag2 in ,indiana1 #ajg2 in ,minnesota1 #ajg1 #aji2 in ,iowa1 #ajh2 in ,british ,america1 #aji4 ,veins in glacial ice1 #c4 ,vermont1 ,runaway ,pond in1 #bjg4 ,vernagt ,glacier1 #baa4 ,vessel ,rock1 view of1 #ef4 ,vezre1 valley of1 #bha4 ,victoria ,cave1 ,england1 #bgj1 #bhj4 ,virginia ,city1 #cdi4 ,vivian1 cited1 #bfg4 ,volga1 the1 #ahe4 ,vosges ,mountains1 #acf4 ,wabash ,river1 #bbj1 #bca1 #bcb4 ,wahsatch ,mountains1 #bcg4 ,wales1 ancient glaciers of1 #adc1 #aej et seq42 caverns of1 #bga4 ,wallace1 cited1 #cca1 #cdc1 #cfb4 ,walrus1 #bfb1 #bhe4 ,warren1 ,pa41 buried channel near1 #bjf4 ,warren ,river1 #bbf4 ,washington1 #a1 #ba1 #abb4 ,washington1 ,d4 ,c41 gravel deposit of1 #bed4 ,water1 transporting power of running1 #e1 #ea-ec4 ,waveney1 ,england1 valley of the1 #bff4 ,wealden formation1 #cfa4 ,weasel1 #bij4 ,wells1 ,england1 #bgj4 ,western ,reserve ,historical ,society1 #ajd4 ,weston1 ,w4 ,va41 #baf4 ,west ,virginia1 #bad et seq42 glacial terrace in1 #baf4 ,wey1 valley of the1 #bfe4 ,whitby1 ,england1 #aee4 ,white1 cited1 #bae et seq4 ,white ,river1 ,ind41 #bcb1 #bea4 ,white ,sea1 #aha4 ,whitney1 #ad1 #ba1 #bie1 #cdi1 #cgc4 ,whittlesey1 #ajj4 ,wild-boar1 #bij4 ,wild-cat1 #bij4 ,winchell1 ,alexander1 cited1 #cba1 #ccj4 ,winchell1 ,n4 ,h41 cited1 #ajg1 #baj1 #beb2 on the ,falls of ,st4 ,anthony1 #cda et seq4 ,wisconsin1 #ih1 #ii1 #ajj1 #aja4 ,woeikoff1 cited1 #caf4 ,wolf1 #bgj1 #bij4 ,wolverine1 #bhi4 ,wood1 cited1 #agi4 ,woodward1 quoted1 #afj2 on age of ,niagara1 #ccg et seq4 ,wookey ,hole1 ,england1 #bgj4 ,wrangell1 cited1 #ceg4 ,wright1 #cgc4 ,yankton1 #abj4 ,yellowstone ,park1 #abb4 ,yorkshire1 #adj1 #aed1 #aee1 #aeg1 #agf1 #bgj1 #bhc1 #bhf4 ,yosemite ,park1 #ba1 #cej4 ,young1 ,rev4 ,mr41 #bd4 ,young1 ,professor1 cited1 #cfb4 ,younglove1 #ajd4 ,zermatt ,glacier1 view of1 #b4 ,zuyder ,zee1 #aha4 ,,the ,,end4 99 99 99 99 99 ,d4 ,,appleton ,,co4',s ,,publications4 ,,the ,,ice ,,age ,,in ,,north ,,america1 and its ,bearings upon the ,antiquity of ,man4 ,by ,g4 ,frederick ,wright1 ,d4 ,d41 ,,ll4 ,d41 ,f4 ,g4 ,s4 ,a41 ,professor in ,oberlin ,theological ,seminary2 ,assistant on the ,united ,states ,geological ,survey4 ,with an appendix on ,the ,probable ,cause of ,glaciation1 by ,warren ,upham1 ,f4 ,g4 ,s4 ,a41 ,assistant on the ,geological ,surveys of ,new ,hampshire1 ,minnesota1 and the ,united ,states4 ,new and enlarged edition4 ,with #aej ,maps and ,illustrations4 #hvo1 #fbe pages1 and ,index4 ,cloth1 #e4jj4 ,not a novel in all the list of this year's publications has in it any pages of more thrilling interest than can be found in this book by ,professor ,wright4 ,there is nothing pedantic in the narrative1 and the most serious themes and startling discoveries are treated with such charming naturalness and simplicity that boys and girls1 as well as their seniors1 will be attracted to the story1 and find it difficult to lay it aside4--,new ,york ,journal of ,commerce4 ,one of the most absorbing and interesting of all the recent issues in the department of popular science4--,chicago ,herald4 ,though his subject is a very deep one1 his style is so very unaffected and perspicuous that even the unscientific reader can peruse it with intelligence and profit4 ,in reading such a book we are led almost to wonder that so much that is scientific can be put in language so comparatively simple4--,new ,york ,observer4 ,the author has seen with his own eyes the most important phenomena of the ,ice age on this continent from ,maine to ,alaska4 ,in the work itself1 elementary description is combined with a broad1 scientific1 and philosophic method1 without abandoning for a moment the purely scientific character4 ,professor ,wright has contrived to give the whole a philosophical direction which lends interest and inspiration to it1 and which in the chapters on ,man and the ,glacial ,period rises to something like dramatic intensity4--,the ,independent4 444 ,to the great advance that has been made in late years in the accuracy and cheapness of processes of photographic reproduction is due a further signal advantage that ,dr4 ,wright's work possesses over his predecessors'4 ,he has thus been able to illustrate most of the natural phenomena to which he refers by views taken in the field1 many of which have been generously loaned by the ,united ,states ,geological ,survey1 in some cases from unpublished material2 and he has admirably supplemented them by numerous maps and diagrams4--,the ,nation4 ,,man ,,and ,,the ,,glacial ,,period4 ,by ,g4 ,frederick ,wright1 ,d4 ,d41 ,,ll4 ,d41 author of ,the ,ice ,age in ,north ,america1 ,logic of ,christian ,evidences1 etc4 ,international ,scientific ,series4 ,with numerous ,illustrations4 #abmo4 ,cloth1 #a4ge4 ,it may be described in a word as the best summary of scientific conclusions concerning the question of man's antiquity as affected by his known relations to geological time4--,philadelphia ,press4 ,the earlier chapters describing glacial action1 and the traces of it in ,north ,america--especially the defining of its limits1 such as the terminal moraine of the great movement itself--are of great interest and value4 ,the maps and diagrams are of much assistance in enabling the reader to grasp the vast extent of the movement4--,london ,spectator4 ,new ,york3 ,d4 ,,appleton ,,co41 #gb ,fifth ,avenue4 99 99 99 99 99 ,d4 ,,appleton ,,co4',s ,,publications4 ,,principles ,,of ,,geology2 or1 the ,modern ,changes of the ,earth and its ,inhabitants1 considered as illustrative of ,geology4 ,by ,sir ,charles ,lyell1 ,bart4 ,illustrated with ,maps1 ,plates1 and ,woodcuts4 ,two vols41 royal #hvo4 ,cloth1 #h4jj4 ,the ,principles of ,geology may be looked upon with pride1 not only as a representative of ,english ,science1 but as without a rival of its kind anywhere4 ,growing in fullness and accuracy with the growth of experience and observation in every region of the world1 the work has incorporated with itself each established discovery1 and has been modified by every hypothesis of value which has been brought to bear upon1 or been evolved from1 the most recent body of facts4 ,,the ,,autobiography ,,of ,,the ,,earth3 ,a ,popular ,account of ,geological history4 ,by ,rev4 ,h4 ,n4 ,hutchinson1 ,b4 ,a41 ,f4 ,g4 ,s4 ,with #bg ,illustrations4 ,crown #hvo4 ,cloth1 #a4ej4 ,a scientific work1 divested of technicalities1 and put into a bright1 narrative form which can not but attract even the most general reader4--,boston ,transcript4 ,it is hardly conceivable that the rich results of the science of geology can be so treated as to prove uninteresting to thinking people1 be they young or old4 ,when1 therefore1 we say that ,mr4 ,hutchinson's book is extremely interesting1 no more might be implied than that the author has skillfully used the vast materials at his hand4 ,but ,mr4 ,hutchinson has successfully carried out a difficult design on an admirable plan1 and has adhered to that plan throughout4 ,his sketch of historical geology has a genuine continuity4--,saturday ,review4 ,a ,,reprint ,,of ,,annual ,,reports ,,and ,,other ,,papers ,,of ,,the ,,geology ,,of ,,the ,,virginias4 ,by the late ,william ,barton ,rogers1 ,,ll4 ,d41 etc41 ,director of the ,geological ,survey of ,virginia from #ahce to #ahda4 ,with numerous ,maps1 ,colored ,charts1 etc4 #abmo4 ,cloth1 #e4jj4 ,,natural ,,resources ,,of ,,the ,,united ,,states4 ,by ,jacob ,harris ,patton1 ,m4 ,a41 ,ph4 ,d4 #hvo4 #ebc pages4 ,cloth1 #c4jj4 ,this portly octavo of over #ejj pages is an encyclopedic directory to its subject1 and a work of comprehensive scope1 exhaustive research1 scientific spirit1 and good literary form4444 ,capitalists1 investors1 railroad projectors1 land speculators1 and all who need to know the distribution of land values1 will find a vast amount of information in this well-arranged work1 the contents of which1 it is safe to say1 could not be found assembled in similar compass elsewhere4--,boston ,literary ,world4 ,as interesting to read as it is valuable to consult4 ,by the employment of fine white paper and large1 clear type1 the publishers have made it an elegant specimen of the printer's art4--,new ,york ,sun4 ,new ,york3 ,d4 ,,appleton ,,co41 #gb ,fifth ,avenue4 99 99 99 99 99 ,d4 ,,appleton ,,co4',s ,,publications4 ,,the ,,ice ,,age ,,in ,,north ,,america1 and its ,bearings upon the ,antiquity of ,man4 ,by ,g4 ,frederick ,wright1 ,d4 ,d41 ,,ll4 ,d4 ,with #aeb ,maps and ,illustrations4 ,third edition1 containing ,appendix on the ,probable ,cause of ,glaciation1 by ,warren ,upham1 ,f4 ,g4 ,s4 ,a41 and ,supplementary ,notes4 #hvo4 #fbe pages1 and complete ,index4 ,cloth1 #e4jj4 ,prof4 ,wright's work is great enough to be called monumental4 ,there is net a page that is not instructive and suggestive4 ,it is sure to make a reputation aboard as well as at home for its distinguished author1 as one of the most active and intelligent of the living students of natural science and the special department of glacial action4--,philadelphia ,bulletin4 ,,the ,,great ,,ice ,,age1 and ,us ,relation to the ,antiquity of ,man4 ,by ,james ,geikie1 ,f4 ,r4 ,s4 ,e41 of ,h4 ,m4 ,geological ,survey of ,scotland4 ,with ,maps and ,illustrations4 #abmo4 ,cloth1 #b4ej4 ,a systematic account of the ,glacial epoch in ,england and ,scotland1 with special reference to its changes of climate4 ,,the ,,cause ,,of ,,an ,,ice ,,age4 ,by ,sir ,robert ,j4 ,ball1 ,,ll4 ,d41 ,f4 ,r4 ,s41 ,royal ,astronomer of ,ireland1 author of ,starland4 ,the first volume in the ,modern ,science ,series1 edited by ,sir ,john ,lubbock4 #abmo4 ,cloth1 #a4jj4 ,an exceedingly bright and interesting discussion of some of the marvelous physical revolutions of which our earth has been the scene4 ,of the various ages traced and located by scientists1 none is more interesting or can be more so than the ,ice age1 and never have its phenomena been more clearly and graphically described1 or its causes more definitely located1 than in this thrillingly interesting volume4--,boston ,traveller4 ,,town ,,geology4 ,by the ,rev4 ,charles ,kingsley1 ,f4 ,l4 ,s41 ,f4 ,g4 ,s41 ,caon of ,chester4 #abmo4 ,cloth1 #a4ej4 ,i have tried rather to teach the method of geology than its facts2 to furnish the student with a key to all geology2 rough indeed and rudimentary1 but sure and sound enough1 ,i trust1 to help him to unlock most geological problems which may meet him in any quarter of the globe4--,from the ,preface4 ,,an ,,american ,,geological ,,railway ,,guide4 ,giving the ,geological ,formation along the ,rail-roads1 with ,altitude above ,tide-water1 ,notes on ,interesting ,places on the ,routes1 and a ,description of each of the ,formations4 ,by ,james ,macfarlane1 ,ph4 ,d41 and more than ,seventy-five ,geologists4 ,second edition1 #dbf pp41 #hvo4 ,cloth1 #b4ej4 ,the idea is an original one4444 ,mr4 ,macfarlane has produced a very convenient and serviceable hand-book1 available alike to the practical geologist1 to the student of that science1 and to the intelligent traveler who would like to know the country through which he is passing4--,boston ,evening ,transcript4 ,new ,york3 ,d4 ,,appleton ,,co41 #gb ,fifth ,avenue4 99 99 99 99 99 ,d4 ,,appleton ,,co4',s ,,publications4 ,,richard ,a4 ,,proctor',s ,,works4 ,,other ,,worlds ,,than ,,ours3 ,the ,plurality of ,worlds1 ,studied under the ,light of ,recent ,scientific ,researches4 ,by ,richard ,anthony ,proctor4 ,with ,illustrations1 some colored4 #abmo4 ,cloth1 #a4ge4 ,contents4--,introduction4--,what the ,earth teaches us4--,what we learn from the ,sun4--,the ,inferior ,planets4--,mars1 the ,miniature of our ,earth4--,jupiter1 the ,giant of the ,solar ,system4--,saturn1 the ,ringed ,world4--,uranus and ,neptune1 the ,arctic ,planets4--,the ,moon and other ,satellites4--,meteors and ,comets3 their ,office in the ,solar ,system4--,other ,suns than ,ours4--,of ,minor ,stars1 and of the ,distribution of ,stars in ,space4--,the ,nebul3 are they ,external ,galaxies8--,supervision and ,control4 ,,our ,,place ,,among ,,infinities4 ,a ,series of ,essays contrasting our ,little ,abode in ,space and ,time with the ,infinities around us4 ,to which are added ,essays on the ,jewish ,sabbath and ,astrology4 #abmo4 ,cloth1 #a4ge4 ,contents4--,past and ,future of the ,earth4--,seeming ,wastes in ,nature4--,new ,theory of ,life in other ,worlds4--,a ,missing ,comet4--,the ,lost ,comet and its ,meteor ,train4--,jupiter4--,saturn and its ,system4--,a ,giant ,sun4--,the ,star ,depths4--,star ,gauging4--,saturn and the ,sabbath of the ,jews4--,thoughts on ,astrology4 ,,the ,,expanse ,,of ,,heaven4 ,a ,series of ,essays on the ,wonders of the ,firmament4 #abaaaj4 ,cloth #b4jj4 ,contents4--,a ,dream that was not all a ,dream4--,the ,sun4--,the ,queen of ,night4--,the ,evening ,star4--,the ,ruddy ,planet4--,life in the ,ruddy ,planet4--,the ,prince of ,planets4--,jupiter's ,family of ,moons4--,the ,ring-,girdled ,planet4--,newton and the ,law of the ,universe4--,the ,discovery of ,two ,giant ,planets4--,the ,lost ,comet4--,visitants from the ,star ,depths4--,whence come the ,comets8--,the ,comet ,families of the ,giant ,planets4--,the ,earth's ,journey through ,showers4--,how the ,planets ,grew4--,our ,daily ,light4--,the ,flight of ,light4--,a ,cluster of ,suns4--,worlds ruled by ,colored ,suns4--,the ,king of ,suns4--,four ,orders of ,suns4 --,the ,depths of ,space4--,charting the ,star ,depths4--,the ,star ,depths ,astir with ,life4--,the ,drifting ,stars4--,the ,milky ,way4 ,,the ,,moon3 ,her ,motions1 ,aspect1 ,scenery1 and ,physical ,conditions4 ,with ,three ,lunar ,photographs1 ,map1 and many ,plates1 ,charts1 etc4 #abmo4 ,cloth1 #b4jj4 ,contents4--,the ,moon's ,distance1 ,size1 and ,mass4--,the ,moon's ,motions4--,the ,moon's ,changes of ,aspect1 ,rotation1 ,libration1 etc4--,study of the ,moon's ,surface4--,lunar ,celestial ,phenomena4--,condition of the ,moon's ,surface4--,index to the ,map of the ,moon4 ,,light ,,science ,,for ,,leisure ,,hours4 ,a ,series of ,familiar ,essays on ,scientific ,subjects1 ,natural ,phenomena1 etc4 #abaaaj4 ,cloth1 #a4ge4 ,d4 ,,appleton ,,co41 #gb ,fifth ,avenue1 ,new ,york4 99 99 99 99 99 ,d4 ,,appleton ,,co4',s ,,publications4 ,,astronomy ,,with ,,an ,,opera-,,glass4 ,a ,popular ,introduction to the ,study of the ,starry ,heavens with the ,simplest of ,optical ,instruments4 ,by ,garrett ,p4 ,serviss4 #hvo4 ,cloth1 #a4ej4 ,this is a unique book1 quite alone in the field that it occupies4 ,the call for a fourth edition within two years after its first publication attests its popularity4 ,as one of its reviewers has said1 ,it is the most human book on the subject of the stars4 ,it would have supplied ,thomas ,carlyle's want when he wrote1 ,why did not somebody teach me the stars and make me at home in the starry heavens8 ,interest in the geography of the heavens is increasing every year1 as the discoveries of astronomers with the giant telescopes of our day push back the limits of the known universe1 and this book is to those who read of such discoveries like an atlas to the student of history4 ,some of the compliments that the book has received are these3 ,a most interesting and even fascinating book4--,christian ,union4 ,the glimpses he allows to be seen of far-stretching vistas opening out on every side of his modest course of observation help to fix the attention of the negligent1 and lighten the toil of the painstaking student4444 ,mr4 ,serviss writes with freshness and vivacity4--,london ,saturday ,review4 ,we are glad to welcome this1 the second edition1 of a popular introduction to the study of the heavens4444 ,there could hardly be a more pleasant road to astronomical knowledge than it affords4444 ,a child may understand the text1 which reads more like a collection of anecdotes than anything else1 but this does not mar its scientific value4--,nature4 ,mr4 ,garrett ,p4 ,serviss's book1 ',astronomy with an ,opera-,glass1' offers us an admirable hand-book and guide in the cultivation of this noble sthetic discipline 7the study of the stars74--,new ,york ,home ,journal4 ,the book should belong to every family library4--,boston ,home ,journal4 ,this book ought to make star-gazing popular4--,new ,york ,herald4 ,the author attributes much of the indifference of otherwise well-informed persons regarding the wonders of the starry firmament to the fact that telescopes are available to few1 and that most people have no idea of the possibilities of the more familiar instrument of almost daily use whose powers he sets forth4--,new ,orleans ,times-,democrat4 ,by its aid thousands of people who have resigned themselves to the ignorance in which they were left at school1 by our wretched system of teaching by the book only1 will thank ,mr4 ,serviss for the suggestions he has so well carried out4--,new ,york ,times4 ,for amateur use this book is easily the best treatise on astronomy yet published4--,chicago ,herald4 ',astronomy with an ,opera-,glass' fills a long-felt want4--,albany ,journal4 ,no intelligent reader of this book but will feel that if the author fails to set his public star-gazing the fault is not his1 for his style is as winning1 as graphic1 and as clear as the delightful type in which it is printed4--,providence ,journal4 ,mr4 ,serviss neither talks over the heads of his readers nor ignores the sublime complexity and range of his themes1 but unites simplicity with scholarship1 scientific precision with life-long enthusiasm1 and a genuine eloquence with rare touches of humor4 ,considered as a product of the publishing industry1 the book is elegance itself4--,the ,chautauquan4 ,new ,york3 ,d4 ,,appleton ,,co41 #gb ,fifth ,avenue4 99 99 99 99 99 ,d4 ,,appleton ,,co4',s ,,publications4 ,,outings ,,at ,,odd ,,times4 ,by ,charles ,c4 ,abbott1 author of ,days out of ,doors and ,a ,naturalist's ,rambles about ,home4 #afmo4 ,cloth1 gilt top1 #a4be4 ,a charming little volume1 literally alone with ,nature1 for it discusses seasons and the fields1 birds1 etc41 with the loving freedom of a naturalist born4 ,every page reads like a sylvan poem2 and for the lovers of the beautiful in quiet outdoor and out-of-town life1 this beautifully bound and attractively printed little volume will prove a companion and friend4--,rochester ,union and ,advertiser4 ,a ,,naturalist',s ,,rambles ,,about ,,home4 ,by ,charles ,c4 ,abbott4 #abmo4 ,cloth1 #a4ej4 ,the home about which ,dr4 ,abbott rambles is clearly the haunt of fowl and fish1 of animal and insect life2 and it is of the habits and nature of these that he discourses pleasantly in this book4 ,summer and winter1 morning1 and evening1 he has been in the open air all the time on the alert for some new revelation of instinct1 or feeling1 or character on the part of his neighbor creatures4 ,most that he sees and hears he reports agreeably to us1 as it was no doubt delightful to himself4 ,books like this1 which are free from all the technicalities of science1 but yet lack little that has scientific value1 are well suited to the reading of the young4 ,their atmosphere is a healthy one for boys in particular to breathe4--,boston ,transcript4 ,,days ,,out ,,of ,,doors4 ,by ,charles ,c4 ,abbott4 #abmo4 ,cloth1 #a4ej4 ',days out of ,doors' is a series of sketches of animal life by ,charles ,c ,abbott1 a naturalist whose graceful writings have entertained and instructed the public before now4 ,the essays and narratives in this book are grouped in twelve chapters1 named after the months of the year4 ,under ',january' the author talks of squirrels1 muskrats1 water-snakes1 and the predatory animals that withstand the rigor of winter2 under ',february' of frogs and herons1 crows and blackbirds2 under ',march' of gulls and fishes and foxy sparrows2 and so on appropriately1 instructively1 and divertingly through the whole twelve4--,new ,york ,sun4 ,,the ,,playtime ,,naturalist4 ,by ,dr4 ,j4 ,e4 ,taylor1 ,f4 ,l4 ,s41 editor of ,science ,gossip4 ,with #cff ,illustrations4 #abmo4 ,cloth1 #a4ej4 ,the work contains abundant evidence of the author's knowledge and enthusiasm1 and any boy who may read it carefully is sure to find something to attract him4 ,the style is clear and lively1 and there are many good illustrations4--,nature4 ,,the ,,origin ,,of ,,floral ,,structures through ,insects and other ,agencies4 ,by the ,rev4 ,george ,henslow1 ,professor of ,botany1 ,queen's ,college4 ,with numerous ,illustrations4 #abmo4 ,cloth1 #a4ge4 ,much has been written on the structure of flowers1 and it might seem almost superfluous to attempt to say anything more on the subject1 but it is only within the last few years that a new literature has sprung up1 in which the authors have described their observations and given their interpretations of the uses of floral mechanisms1 more especially in connection with the processes of fertilization4--,from ,introduction4 ,new ,york3 ,d4 ,,appleton ,,co41 #gb ,fifth ,avenue4 99 99 99 99 99 ,d4 ,,appleton ,,co4',s ,,publications4 ,,the ,,garden',s ,,story2 or1 ,pleasures and ,trials of an ,amateur ,gardener4 ,by ,george ,h4 ,ellwanger4 ,with ,head and ,tail ,pieces by ,rhead4 #abmo4 ,cloth1 extra1 #a4ej4 ,mr4 ,ellwanger's instinct rarely errs in matters of taste4 ,he writes out of the fullness of experimental knowledge1 but his knowledge differs from that of many a trained cultivator in that his skill in garden practice is guided by a refined sthetic sensibility1 and his appreciation of what is beautiful in nature is healthy1 hearty1 and catholic4 ,his record of the garden year1 as we have said1 begins with the earliest violet1 and it follows the season through until the witch-hazel is blossoming on the border of the wintry woods4444 ,this little book can not fail to give pleasure #aj all who take a genuine interest in rural life4--,new ,york ,tribune4 ,,the ,,origin ,,of ,,cultivated ,,plants4 ,by ,alphonse de ,candolle4 #abmo4 ,cloth1 #b4jj4 ,though a fact familiar to botanists1 it is not generally known hew great is the uncertainty as to the origin of many of the most important cultivated plants4 444 ,in endeavoring to unravel the matter1 a knowledge of botany1 of geography1 of geology1 of history1 and of philosophy is required4 ,by a combination of testimony derived from these sources ,m4 de ,candolle has been enabled to determine the botanical origin aid geographical source of the large proportion of species he deals with4--,the ,athenum4 ,,the ,,folk-,,lore ,,of ,,plants4 ,by ,t4 ,f4 ,thiselton ,dyer1 ,m4 ,a4 #abaaaj4 ,cloth1 #a4ej4 ,a handsome and deeply interesting volume4444 ,in all respects the book is excellent4 ,its arrangement is simple and intelligible1 its style bright and alluring4444 ,to all who seek an introduction to one of the most attractive branches of folk-lore1 this delightful volume may be warmly commended4--,notes and ,queries4 ,,flowers ,,and ,,their ,,pedigrees4 ,by ,grant ,allen1 author of ,vignettes of ,nature1 etc4 ,illustrated4 #abmo4 ,cloth1 #a4ej4 ,no writer treats scientific subjects with so much ease and charm of style as ,mr4 ,grant ,allen4 ,the study is a delightful one1 and the hook is fascinating to any one who has either love for flowers or curiosity about them4--,hartford ,courant4 ,any one with even a smattering of botanical knowledge1 and with either a heart or mind1 must be charmed with this collection of essays4--,chicago ,evening ,journal4 ,,the ,,geological ,,history ,,of ,,plants4 ,by ,sir ,j4 ,william ,dawson1 ,f4 ,r4 ,s4 ,illustrated4 #abmo4 ,cloth1 #a4ge4 ,the object of this work is to give1 in a connected form1 a summary of the development of the vegetable kingdom in geological time4 ,to the geologist and botanist the subject is one of importance with reference to their special pursuits1 and one on which it has not been easy to find any convenient manual of information4 ,it is hoped that its treatment in the present volume will also be found sufficiently simple and popular to be attractive to the general reader4--,from the ,preface4 ,new ,york3 ,d4 ,,appleton ,,co41 #gb ,fifth ,avenue4 99 99 99 99 99 ,d4 ,,appleton ,,co4',s ,,publications4 ,,idle ,,days ,,in ,,patagonia4 ,by ,w4 ,h4 ,hudson1 ,c4 ,m4 ,z4 ,s41 author of ,the ,naturalist in ,la ,plata1 etc4 ,with #bg ,illustrations4 #hvo4 ,cloth1 #d4jj4 ,of all modern books of travel it is certainly one of the most original1 and many1 we are sure1 will also find it one of the most interesting and suggestive4--,new ,york ,tribune4 ,mr4 ,hudson's remarks on color and expression of eyes in man and animals are reserved for a second chapter1 ',concerning ,eyes4' ,he is eloquent upon the pleasures afforded by ',bird ,music in ,south ,america1' and relates some romantic tales of white men in captivity to savages4 ,but it makes very little difference what is the topic when ,mr4 ,hudson writes4 ,he calls up bright images of things unseen1 and is a thoroughly agreeable companion4--,philadelphia ,ledger4 ,,the ,,naturalist ,,in ,,la ,,plata4 ,by ,w4 ,h4 ,hudson1 ,c4 ,m4 ,z4 ,s41 author of ,idle ,days in ,patagonia1 and joint author of ,argentine ,ornithology4 ,with #bg ,illustrations4 #hvo4 ,cloth1 #d4jj4 ,mr4 ,hudson is not only a clever naturalist1 but he possesses the rare gift of interesting his readers in whatever attracts him1 and of being dissatisfied with mere observation unless it enables him to philosophize as well4 ,with his lucid accounts of bird1 beast1 and insect1 no one will fail to be delighted4--,london ,academy4 ,a notably clear and interesting account of scientific observation and research4 ,mr4 ,hudson has a keen eye for the phenomena with which the naturalist is concerned1 and a lucid and delightful way of writing about them1 so that any reader may be charmed by the narrative and the reflections here set forth4 ,it is easy to follow him1 and we get our information agreeably as he conducts us over the desert pampas1 and makes us acquainted with the results of his studies of animals1 insects1 and birds4--,new ,york ,sun4 ,,the ,,naturalist ,,on ,,the ,,river ,,amazons4 ,by ,henry ,walter ,bates1 ,f4 ,r4 ,s41 late ,assistant ,secretary of the ,royal ,geographical ,society4 ,with a ,memoir of the ,author1 by ,edward ,clodd4 ,with ,map and numerous ,illustrations4 #hvo4 ,cloth1 #e4jj4 ,this famous work is a natural history classic4--,london ,literary ,world4 ,more than thirty years have passed since the first appearance of ',the ,naturalist on the ,river ,amazons1' which ,darwin unhesitatingly pronounced the best book on natural history which ever appeared in ,england4 ,the work still retains its prime interest1 and in rereading it one can not but be impressed by the way in which the prophetic theories1 disputed and ridiculed at the time1 have since been accepted4 ,such is the common experience of those who keep a few paces in advance of their generation4 ,bates was a 'born' naturalist4--,philadelphia ,ledger4 ,no man was better prepared or gave himself up more thoroughly to the task of studying an almost unknown fauna1 or showed a zeal more indefatigable in prosecuting his researches1 than ,bates4 ,as a collector alone his reputation would be second to none1 but there is a great deal more than sheer industry to be cited4 ,the naturalist of the ,amazons is1 par excellence1 possessed of a happy literary style4 ,he is always clear and distinct4 ,he tells of the wonders of tropical growth so that you can understand them all4--,new ,york ,times4 ,new ,york3 ,d4 ,,appleton ,,co41 #gb ,fifth ,avenue4 99 99 99 99 99 ,d4 ,,appleton ,,co4',s ,,publications4 ,,works ,,by ,,arabella ,b4 ,,buckley 7,,mrs4 ,,fisher74 ,,the ,,fairy-,,land ,,of ,,science4 ,with #gd ,illustrations4 #abmo4 ,cloth1 gilt1 #a4ej4 ,deserves to take a permanent place in the literature of youth4--,london ,times4 ,so interesting that1 having once opened the book1 we do not know how to leave off reading4 --,saturday ,review4 ,,through ,,magic ,,glasses1 and other ,lectures4 ,a ,sequel to ,the ,fairy-,land of ,science4 ,illustrated4 #abmo4 ,cloth1 #a4ej4 ,,contents4 ,the ,magician's ,chamber by ,moonlight4 ,magic ,glasses and ,how to ,use ,them4 ,fairy ,rings and ,how ,they are ,made4 ,the ,life-,history of ,lichens and ,mosses4 ,the ,history of a ,lava-,stream4 ,an ,hour with the ,sun4 ,an ,evening with the ,stars4 ,little ,beings from a ,miniature ,ocean4 ,the ,dartmoor ,ponies4 ,the ,magician's ,dream of ,ancient ,days4 ,,life ,,and ,,her ,,children3 ,glimpses of ,animal ,life from the ,amoeba to the ,insects4 ,with over #ajj ,illustrations4 #abaaaj4 ,cloth1 gilt1 #a4ej4 ,the work forms a charming introduction to the study of zoology--the science of living things--which1 we trust1 will find its way into many hands4--,nature4 ,,winners ,,in ,,life',s ,,race2 or1 ,the ,great ,backboned ,family4 ,with numerous ,illustrations4 #abmo4 ,cloth1 gilt1 #a4ej4 ,we can conceive of no better gift-book than this volume4 ,miss ,buckley has spared no pains to incorporate in her book the latest results of scientific research4 ,the illustrations in the book deserve the highest praise--they are numerous1 accurate1 and striking4--,spectator4 ,,short ,,history ,,of ,,natural ,,science2 and of the ,progress of ,discovery from the ,time of the ,greeks to the ,present ,time4 ,new edition1 revised and rearranged4 ,with #gg ,illustrations4 #abmo4 ,cloth1 #b4jj4 ,the work1 though mainly intended for children and young persons1 may be most advantageously read by many persons of riper age1 and may serve to implant in their minds a fuller and clearer conception of 'the promises1 the achievements1 and the claims of science4'--,journal of ,science4 ,,moral ,,teachings ,,of ,,science4 #abmo4 ,cloth1 #ge cents4 ,a little book that proves1 with excellent clearness and force1 how many and striking are the moral lessons suggested by the study of the life history of the plant or bird1 beast or insect4--,london ,saturday ,review4 ,new ,york3 ,d4 ,,appleton ,,co41 #gb ,fifth ,avenue4 99 99 99 99 99 ,d4 ,,appleton ,,co4',s ,,publications4 ,,modern ,,science ,,series4 ,edited by ,sir ,john ,lubbock1 ,bart41 ,f4 ,r4 ,s4 ,,the ,,cause ,,of ,,an ,,ice ,,age4 ,by ,sir ,robert ,ball1 ,,ll4 ,d41 ,f4 ,r4 ,s41 ,royal ,astronomer of ,ireland2 author of ,star ,land1 ,the ,story of the ,sun1 etc4 ,sir ,robert ,ball's book is1 as a matter of course1 admirably written4 ,though but a small one1 it is a most important contribution to geology4--,london ,saturday ,review4 ,a fascinating subject1 cleverly related and almost colloquially discussed4--,philadelphia ,public ,ledger4 ,,the ,,horse2 ,a ,study in ,natural ,history4 ,by ,william ,h4 ,flower1 ,c4 ,b41 ,director in the ,british ,natural ,history ,museum4 ,with #bg ,illustrations4 ,the author admits that there are #c1hjj separate treatises on the horse already published1 but he thinks that he can add something to the amount of useful information now before the public1 and that something not heretofore written will be found in this book4 ,the volume gives a large amount of information1 both scientific and practical1 on the noble animal of which it treats4--,new ,york ,commercial ,advertiser4 ,,the ,,oak3 ,a ,study in ,botany4 ,by ,h4 ,marshall ,ward1 ,f4 ,r4 ,s4 ,with #ec ,illustrations4 ,from the acorn to the timber which has figured so gloriously in ,english ships and houses1 the tree is fully described1 and all its living and preserved beauties and virtues1 in nature and in construction1 are recounted and pictured4--,brooklyn ,eagle4 ,,ethnology ,,in ,,folk ,,lore4 ,by ,george ,l4 ,gomme1 ,f4 ,s4 ,a41 ,president of the ,folklore ,society1 etc4 ,the author puts forward no extravagant assumptions1 and the method he points out for the comparative study of folk-lore seems to promise a considerable extension of knowledge as to prehistoric times4--,independent4 ,,the ,,laws ,,and ,,properties ,,of ,,matter4 ,by ,r4 ,t4 ,glazebrook1 ,f4 ,r4 ,s41 ,fellow of ,trinity ,college1 ,cambridge4 ,it is astonishing how interesting such a took can be made when the author has a perfect mastery of his subject1 as ,mr4 ,glazebrook has4 ,one knows nothing of the world in which he lives until he has obtained some insight of the properties of matter as explained in this excellent work4--,chicago ,herald4 ,,the ,,fauna ,,of ,,the ,,deep ,,sea4 ,by ,sydney ,j4 ,j4 ,hickson1 ,m4 ,a41 ,fellow of ,downing ,college1 ,cambridge4 ,with #bc ,illustrations4 ,that realm of mystery and wonders at the bottom of the great waters is gradually being mapped and explored and studied until its secrets seem no longer secrets4 4 4 4 ,this excellent book has a score of illustrations and a careful index to add to its value1 and in every way is to be commended for its interest and its scientific merit4--,chicago ,times4 ,each1 #abmo1 cloth1 #a4jj4 ,new ,york3 ,d4 ,,appleton ,,co41 #gb ,fifth ,avenue4 99 99 99 99 99 ,transcriber ,note ,figure captions were standardized4 ,all figures were moved to avoid splitting paragraphs4 ,any minor typos were corrected4