,transcriber's ,note ,text emphasis is displayed as ,italics and ,bold respectively4 ,superscript characters are denoted with the carat character 7i4e41 #h;e74 ,whole and fractional parts are displayed as #e-a_/b4 ,,fragments ,,of ,,earth ,,lore ,illustration3 ,,plate ,i ,,orographic ,,map ,,of ,,scotland ,,fragments ,,of ,,earth ,,lore ,,sketches ,,addresses ,geological and ,geographical ,,by ,,james ,,geikie1 ,d4,c4,l41 ,,ll4,d41 ,f4,r4,s41 c4 ,,murchison-,,professor ,,of ,,geology ,,and ,,mineralogy ,,in ,,the ,,university ,,of ,,edinburgh ,,formerly ,,of ,h4,m4 ,,geological ,,survey ,,of ,,scotland ,,with ,,maps ,,and ,,illustrations ,,edinburgh ,,john ,,bartholomew ,,co4 ,,london3 ,,simpkin1 ,,marshall1 ,,hamilton1 ,,kent ,co41 ,ltd4 #ahic ,,preface4 ,the articles in this volume deal chiefly with the history of ,glacial times and the origin of surface-features4 ,as they were not written with any view to their subsequent appearance in a collected form1 each is so far independent and complete in itself4 ,under these circumstances some repetition was unavoidable1 if the articles were not to be recast1 and ,i did not think it advisable to make such radical alteration4 ,with the exception of verbal changes and some excisions1 therefore1 the papers remain substantially in their original state4 ,here and there a footnote has been added to indicate where the views expressed in the text have since been modified2 but ,i have not been careful to insert such notes throughout4 ,geologists1 like other folk1 live and learn1 and the reader will probably discover that the opinions set forth in some of the later articles are occasionally in advance of those maintained in the writer's earlier days4 ,i have to thank the ,publishers of ,good ,words for allowing me to republish the articles on the ,cheviot ,hills and the ,outer ,hebrides4 ,my acknowledgments are also due to ,mr4 ,bartholomew for the excellent maps with which the volume is so well illustrated4 ,edinburgh1 ,april #eth1 #ahic4 ,,list ,,of ,,maps4 ,plate ,i4 ,,physical ,,features ,,of ,,scotland ,frontispiece ,,ii4 ,,structure ,,of ,,mountains #fj ,,iii4 ,,past ,,and ,,present ,,glaciation ,,of ,,the ,,world #aic ,,iv4 ,,ice ,,age ,,in ,,northern ,,europe #cbd ,v4 ,,the ,,geographical ,,evolution ,,of ,,continents #cdh ,,vi4 ,,bathy-,,hypsometrical ,,map1 ,,illustrating ,,development ,,of ,,coast-,,lines #dbh ,,contents4 ,,chap4 ,,page ,i4 ,,geography ,,and ,,geology #a ,,ii4 ,,the ,,physical ,,features ,,of ,,scotland #ad ,,iii4 ,,mountains3 ,,their ,,origin1 ,,growth1 ,,and ,,decay #cf ,,iv4 ,,the ,,cheviot ,,hills #fb ,v4 ,,the ,,long ,,island1 ,,or ,,outer ,,hebrides #abe ,,vi4 ,,the ,,ice ,,age ,,in ,,europe ,,and ,,north ,,america #afj ,,vii4 ,,the ,,intercrossing ,,of ,,erratics ,,in ,,glacial ,,deposits #aid ,,viii4 ,,recent ,,researches ,,in ,,the ,,glacial ,,geology ,,of ,,the ,,continent #bbj ,,ix4 ,,the ,,glacial ,,period ,,and ,,the ,,earth-,,movement ,,hypothesis #bdh ,x4 ,,the ,,glacial ,,succession ,,in ,,europe #bhh ,,xi4 ,,the ,,geographical ,,evolution ,,of ,,europe #cbf ,,xii4 ,,the ,,evolution ,,of ,,climate #cdi ,,xiii4 ,,the ,,scientific ,,results ,,of ,,dr4 ,,nanssen',s ,,expedition #chb ,,xiv4 ,,the ,,geographical ,,development ,,of ,,coast-,,lines #cic ,i4 ,geography and ,geology4,a ,a ,portion of a lecture given in #ahhf to the ,class of ,geology in the ,university of ,edinburgh4 ,the teaching of ,geography naturally occupies a prominent place in every school curriculum4 ,it is rightly considered essential that we should from an early age begin to know something of our own and other countries4 ,i am not sure1 however1 that ,geography is always taught in the most interesting and effective manner4 ,indeed1 according to some geographers1 who are well qualified to express an opinion1 the manner in which their subject is presented in many of our schools leaves much to be desired4 ,but a decided advance has been made in recent years1 and with the multiplication of excellent text-books1 maps1 and other appliances1 ,i have no doubt that this improvement will continue4 ,when ,i attended school the text-books used by my teachers were about as repellent as they could be4 ,our most important lesson was to commit to memory a multitude of place-names1 and the maps which were supposed to illustrate the text-books were1 if possible1 less interesting and instructive4 ,nowadays1 however1 teachers have a number of more or less excellent manuals at their service1 and the educational maps issued by our cartographers show in many cases a very great advance on the bald and misleading caricatures which did duty in my young days as pictures of the earth's surface4 ,during the progress of some war we often remark that the task of following the military operations compels us to brush up our ,geography4 ,i am uncharitable enough to suspect that it would frequently be truer to say that1 before these campaigns commenced1 we had no such knowledge to brush up4 ,the countries involved in the commotion were probably mere names to many of us4 ,we had no immediate interest in them or their inhabitants1 and had we been asked1 before the outbreak of hostilities1 to indicate the precise positions of the places upon a map1 some of us perhaps might have been sorely puzzled to do so4 ,nor is such ignorance always discreditable4 ,one cannot know everything2 the land-surface of the globe contains upwards of #ej millions of square miles1 and one may surely be excused for not having a detailed knowledge of this vast area4 ,i have referred to the subject simply because ,i think it gives us a hint as to how the teaching of ,political ,geography might be made most instructive and interesting4 ,historical narrative might often be interwoven with the subject in such a way as to fix geographical features indelibly on the memory4 ,striking and picturesque incidents1 eventful wars1 the rise and progress of particular trades1 the routes followed by commerce1 the immigration and emigration of races1 the gradual development of the existing political divisions of the ,old ,world1 the story of ,columbus and the early voyagers1 the geographical discoveries of later times--all these1 and such as these1 might be introduced into our lessons in ,political ,geography4 ,the wanderings of a ,mungo ,park1 a ,bruce1 a ,livingstone1 a ,stanley1 traced on a good map1 could not fail to arrest the attention of the youthful student of ,african geography4 ,in like manner1 the campaigns of the great ,napoleon might be made to do good service in illustrating the geographical features of large portions of our own continent4 ,then1 as regards ,britain1 what a world of poetry and romantic story clings to every portion of its surface--why1 the very place-names themselves might suggest to any intelligent teacher themes and incidents1 the deft treatment of which would make the acquisition of ,geography a delightful task to the dullest boy or girl4 ,the intimate relation that obtains between ,political ,geography and ,history has indeed long been recognised1 and is in fact self-evident4 ,and we are all well aware that in our school manuals of ,geography it has been usual for very many years to note the scenes of remarkable events4 ,such notes1 however1 are of necessity extremely brief2 and it need hardly be said that to fully incorporate history in a text-book of general ,geography would be quite impracticable4 ,it might be done to a certain extent for our own and a few of the more important countries2 but similar detail need not be attempted in regard to regions which are of less consequence from the political point of view4 ,indeed1 ,i should be inclined to leave the proper application of historical knowledge in the teaching of ,geography very much to the teacher himself1 who would naturally select such themes and incidents as seemed best adapted to attract the attention of his pupils4 ,be that1 however1 as it may1 it is enough for my present purpose if ,i insist upon the fact that the proper study of ,political ,geography involves the acquisition of some historical knowledge4 ,one can hardly conceive the possibility of an intelligent student taking pains to become acquainted with the political geography of a country without at the same time endeavouring to learn something of its history--otherwise1 his geographical attainments would hardly surpass those of a commercial traveller1 whose geographical studies have been confined to the maps and tables of his ,bradshaw4 ,but if it be impossible to ignore ,history in the teaching of ,political ,geography1 it is just as impossible to exclude from our attention great physical features and characteristics4 ,surface-configuration1 climate1 and natural products all claim our attention4 ,it is obvious1 in fact1 that the proper study of ,political ,geography must give us at least a general notion of the configuration1 the river-systems1 and climatic conditions of many different lands4 ,for has not the political development of races depended most largely on the physical conditions and natural resources of the countries occupied by them8 ,so far1 then1 as these have sensibly influenced the progress of peoples1 they come naturally under the consideration of ,political ,geography4 ,thus1 if ,political ,geography be closely connected and interwoven1 as it were1 with ,history1 not less intimate are its relations to ,physical ,geography4 ,it does not embrace all ,physical ,geography1 but it introduces us to many facts and phenomena1 the causes and mutual relations of which we cannot understand without first mastering the teachings of ,physical ,geography4 ,in the study of this latter science we come more closely into contact with ,nature2 we cease to think of the surface of the earth as parcelled out into so many lots by its human occupants--we no longer contemplate that surface from the limited point of view of the political geographer--we are now not merely members of one particular community1 but have become true citizens of the world4 ,to us north and south1 east and west are of equal interest and importance4 ,our desire now is to understand1 if haply we may1 the complex system of which we ourselves form a part4 ,the distribution of land and water--the configuration of continental areas and oceanic basins--the circulation of oceanic and terrestrial waters--earth-movements and volcanoes--ice-formations--the atmosphere--climatology--the geographical distribution of plants and animals--in a word1 the world as one organic whole now forms the subject of our contemplation4 ,such being the scope of ,physical ,geography1 it is satisfactory to know that its importance as a subject of study in our schools has been fully recognised4 ,this being admitted1 ,i shall now proceed to show that ,physical ,geography1 although1 like ,political ,geography1 it is a separate and distinct subject1 yet1 just as the study of the latter involves some knowledge of ,history1 so the prosecution of ,physical ,geography compels us to make a certain acquaintance with ,geology4 ,we cannot1 in fact1 learn much about the atmosphere1 about rain and rivers1 glaciers and icebergs1 earthquakes and volcanoes1 and the causes of climate1 without at the same time becoming more or less familiar with the groundwork on which geological investigations are based4 ,and just as a knowledge of history enables us better to understand the facts of ,political ,geography1 so some acquaintance with the results of geological inquiry are necessary before we can hope to comprehend many of the phenomena of which ,physical ,geography treats4 ,let me try to make this plain4 ,the physical geographer1 we shall suppose1 is considering the subject of terrestrial waters4 ,he tells us what is meant by the drainage-system of a country1 points out how the various minor water-courses or brooks and streams unite to form a river1 describes for us the shape of the valley through which a typical river makes its way--how the valley-slope diminishes from the mountains onwards to the sea-coast--how1 at first1 in its upper or mountain-track1 the flow of the river is torrential--how1 as the slope of the valley decreases1 the river begins to wind about more freely1 until it reaches the head of its plain-track or delta1 when1 no longer receiving affluents1 it begins to divide1 and enters the sea at last by many mouths4 ,he tells us further what proportion of the rainfall of the country passes seawards in our river1 and he can measure for us the quantity of water which is actually discharged4 ,all this is purely ,physical ,geography2 but when we come to ask why some rivers flow in deep caons1 like those of the ,colorado--why valleys should widen out in one part and contract1 as it were1 elsewhere--why the courses of some rivers are interrupted by waterfalls and rapids1 and many other similar questions1 the physical geographer must know something of ,geology before he can give an answer4 ,he can describe the actual existing conditions2 without the aid of ,geology1 he can tell us nothing of their origin and cause4 ,so the political geographer can map out for us the present limits of the various countries of ,europe1 but ,history must be invoked if we would know how those boundaries came to be determined4 ,the moment1 therefore1 the physical geographer begins to inquire into the origin of any particular physical feature1 he enters upon the domains of the geologist4 ,and as he cannot possibly avoid doing so1 it is quite common now to find a good deal of the subject-matter of ,geology treated of in text-books of ,physical ,geography4 ,i state this merely to show how very closely the two sciences are interlocked4 ,take1 for example1 the configuration of river valleys just referred to4 ,the physical geographer recognises the fact that a river performs work2 by means of the sediment which it carries in suspension and rolls along its course1 it erodes its bed in many places1 and undermines its banks1 and thus its channel is deepened and widened4 ,he can measure the amount of sediment which it carries down to the sea1 and the quantity of saline matters which its waters hold in solution3 and knowing that all these substances have been abstracted from the land1 he is able to estimate approximately the amount of material which is annually transferred from the surface of the drainage-area involved4 ,he discovers this to be so relatively enormous that he has no difficulty in believing that the valleys in which rivers flow might have been hollowed out by the rivers themselves4 ,but1 without trespassing further into the geologist's domains1 he cannot go beyond this3 and you will at once perceive that something more is required to prove that any particular valley owes its origin to the erosive action of running water4 ,suppose someone were to suggest to him that his river-valley might be a minor wrinkle in the earth's crust caused by earth-movements1 or that it might indicate the line of a fissure or dislocation1 due to some comparatively recent convulsion--how could his computation of the amount of material at present carried seawards by the river prove such suggestions to be erroneous8 ,and what light could it throw upon the origin of the varied configuration of the river-valley--how would it explain the presence or absence of cascades and rapids1 of narrow gorges and open expanses8 ,none of these phenomena can be interpreted and accounted for without the aid of the geologist3 without some knowledge of rocks and rock-structures1 the origin of the earth's surface-features is quite inexplicable4 ,to give an adequate explanation of all the surface-features of a country in detail would of course require a profound study of ,geology2 but a general acquaintance only with its elementary facts is quite sufficient to enable us to form a reasonable and intelligent view of the cause and origin of the main features of the land as a whole4 ,thus a few lessons in elementary ,geology would make clear to any child how rivers have excavated valleys1 why cataracts and gorges occur here1 and open valleys with gently-flowing waters elsewhere4 ,let me select yet another example to show how dependent ,physical ,geography is upon ,geology4 ,the physical geographer1 in describing the features of the land1 tells us how the great continental areas are traversed in various directions by what he calls mountain-chains4 ,thus1 in speaking of ,america1 he tells us that it may be taken as a type of the continental structure--namely a vast expanse of land1 low or basin-like in the interior1 and flanked along the maritime regions by elevated mountain borders--the highest border facing the deepest ocean4 ,he points out further that the great continental areas are crossed from west to east by well-marked depressions1 to a large extent occupied by water4 ,thus ,europe is separated from ,africa by the ,mediterranean1 a depression which is continued eastward through the ,black ,sea into the ,aralo-,caspian area4 ,south ,america is all but cut away from ,north ,america1 while ,australia is separated from ,asia by the ,east ,india ,seas4 ,we find1 in fact1 all over the world that well-marked natural features are constantly being repeated4 ,not only do the great land-masses of the globe bear certain resemblances to each other1 but even in their detailed structure similar parallelisms recur4 ,the physical geographer notes all these remarkable phenomena1 but he can give us no clue to their meaning4 ,he may describe with admirable skill the characteristic features of plains and plateaux1 of volcanic mountains and mountain-chains1 but he cannot tell us why plains should occur here and mountains there2 nor can he explain why some mountains1 such as those of ,scotland or ,norway1 differ so much in configuration from the ,alps and the ,pyrenees4 ,the answer to all these questions can only be given by ,geology4 ,it is from this science we learn how continental areas and oceanic basins have been evolved4 ,the patient study of the rocks has revealed the origin of the present configuration of the land4 ,there is not a hill or valley1 not a plateau or mountain-region1 which does not reveal its own history4 ,the geologist can tell you why continents are bordered by coast-ranges1 and why their interiors are generally comparatively low and basin-shaped4 ,the oceanic basins and continental areas1 we learn1 are primeval wrinkles in the earth's crust1 caused by its irregular subsidence upon the gradually cooling and contracting nucleus4 ,the continents are immense plateau-like areas rising more or less abruptly above those stupendous depressions of the earth's crust which are occupied by the ocean4 ,while those depressions are in progress the maritime borders of the land-areas are subjected to enormous squeezing and crushing1 and coast-ranges are the result--the elevation of those ranges necessarily holding some relation to the depth of the contiguous ocean4 ,for1 the deeper the ocean the greater has been the depression under the sea1 and1 consequently1 the more intense the upheaval along the continental borders4 ,it is for the same reason that destructive earthquakes are most likely to occur in the vicinity of coast-ranges which are of comparatively recent geological age4 ,these1 and indeed all1 mountains of elevation are lines of weakness along which earth-movements may continue from time to time to take place4 ,but all mountains are not mountains of elevation2 many elevated regions owe their mountainous character simply to the erosive action of sub-arial agents1 such as rain1 frost1 ice1 and running water1 the forms assumed by the mountains being due to their petrological character and geological structure4 ,there are1 for example1 no true mountains of elevation in ,scotland2 hence to write of the chain of the ,grampians or the range of the ,lowthers is incorrect and actually misleading4 ,without the aid of ,geology the geographer cannot1 in fact1 discriminate between mountains of elevation and mountains of denudation2 hence geographical terms so constantly in use as mountain-range and mountain-chain are very often applied by writers1 ignorant of geological structure1 to elevated regions which have no claim to be described either as chains or ranges4 ,some knowledge of ,geology1 therefore1 is essential to us if we would have correct views of many of the grandest features of the globe4 ,but it will be said that1 after all1 the physical geographer deals with the earth as we now find it2 he does not need to trouble himself with the origin of the phenomena he describes4 ,well1 as ,i have just shown1 he cannot1 even if he would1 escape trenching on ,geology2 and if he could1 his subject would be shorn of much of its interest4 ,he recognises that the world he studies has in it the elements of change--the forces of ,nature are everywhere modifying the earth's surface--considerable changes are sometimes brought about even in one's lifetime1 while within the course of historical ages still greater mutations have taken place--he becomes conscious1 in short1 that the existing state of things is but the latest phase of an interminable series of changes stretching back into the illimitable past1 and destined to be prolonged into the indefinite future4 ,thus he gladly welcomes the labours of the geologist1 whose researches into the past have thrown such a flood of light upon the present4 ,in fact1 he can no more divorce his attention from the results of geological inquiry than the political geographer can shut his eyes to the facts of ,history4 ,let me1 in conclusion1 give one further illustration of the close inter-dependence of the two sciences of which ,i am speaking4 ,one of the subjects treated of by ,physical ,geography is the present geographical distribution of plants and animals4 ,the land-surface of the globe has been mapped out into so many biological regions1 each of which is characterised by its special fauna and flora4 ,the greatest changes in the flora and fauna of a continent are met with as we pass from south to north1 or vice versa4 ,proceeding in the direction of the latitude1 the changes encountered are much less striking4 ,now1 these facts are readily explained by the physical geographer1 who points out that the distribution is due chiefly to climatic conditions--a conclusion which is obvious enough4 ,but when we go into details we find that mere latitude will not account for all the phenomena4 ,take1 for example1 the case of the ,scandinavian flora of our own ,continent4 ,it is true that this flora is largely confined to northern latitudes2 but isolated colonies occur in our own mountains and in the mountains of middle and southern ,europe4 ,how are these to be accounted for8 ,the physical geographer says that the plants grow there simply because they obtain at high levels in low latitudes the favourable climatic conditions underneath which they flourish at low levels in high latitudes4 ,he therefore concludes that the distribution of life-forms is due to varying climatic and physical conditions4 ,but if we ask him how those curious colonies of foreigners come to be planted on our mountains1 he cannot tell4 ,to get our answer we must come to the geologist2 and he will explain that they are1 as it were1 living fossils--monuments of former great physical and climatic changes4 ,he will prove to us that the climate of ,europe was at a recent geological period so cold that the ,scandinavian flora spread south into middle ,europe1 where it occupied the low grounds4 ,when the climate became milder1 then the northern invaders gradually retired--the main body migrating back to the north--while some stragglers1 retreating before the stronger ,germanic flora1 took shelter in the mountains1 whither the latter could not or would not follow1 and so there our ,scandinavians remain1 the silent witnesses of a stupendous climatic revolution4 ,now1 all the world over1 plants and animals have similar wonderful tales to tell of former geographical changes4 ,the flora and fauna of our country1 for example1 prove that the ,british ,islands formed part of the ,continent at a very recent geological period2 and so1 from similar evidence1 we know that not long ago ,europe was joined on to ,africa4 ,on the other hand1 the facts connected with the present distribution of life demonstrate that some areas1 such as ,australia1 have been separated from the nearest continental land for vastly prolonged periods of time4 ,it would be a very easy matter to adduce many further illustrations to show how close is the connection between the studies of the physical geographer and the geologist4 ,i do not indeed exaggerate when ,i say that no one can hope to become a geologist who is not well versed in ,physical ,geography2 nor1 on the other hand1 can the physical geographer possibly dispense with the aid of ,geology4 ,the two subjects are as closely related and interwoven1 the one with the other1 as ,history is with ,political ,geography4 ,i do not see therefore how educationists who have admitted the great importance of ,physical ,geography as a branch of general education1 can logically exclude ,geology as a subject of instruction in schools4 ,already1 indeed1 it has been introduced by many teachers1 and ,i am confident that ere long it will be as generally taught as ,physical ,geography4 ,i would not1 however1 present the subject to young people as a lesson to be learned from books4 ,a good teacher should be able to dispense with these helps1 or rather hindrances--for such they really are to a young beginner4 ,his pupils ought to have previously studied the subject of ,physical ,geography1 and if they have been well taught they ought to have already acquired no mean store of geological knowledge4 ,they ought1 in fact1 to have learned a good deal about the great forces which are continually modifying the surface of the globe1 and what they have now to do is to study more particularly the results which have followed from the constant operation of those forces4 ,we shall suppose1 for example1 that the teacher has described how rivers erode their channels1 and waves tend to cut back a coast-line1 and how the products of erosion1 consisting of gravel1 sand1 and mud1 are distributed along river-valleys and accumulated in lakes and seas4 ,he now exhibits to his class good-sized fragments of conglomerate1 sandstone1 and shale1 and points out how each of these rocks is of essentially the same character1 and must therefore have had the same origin1 as modern sedimentary accumulations4 ,his pupils should be encouraged to examine the rocks of their own neighbourhood1 whether exhibited in natural sections or artificial exposures1 and to compare these with the products of modern geological action4 ,one hour's instruction in the field is1 in fact1 worth twenty hours of reading or listening to lectures4 ,knowledge at first hand is what is wanted4 ,there are many excellent popular or elementary treatises dealing with ,historical ,geology1 and these have their uses1 and may be read with profit as well as pleasure4 ,but the mere reading of such books1 it is needless to say1 will never make us geologists4 ,they help no doubt to store the mind with interesting and entertaining knowledge1 but they do not cultivate the faculties of observation and reasoning4 ,and unless geology is so taught as to accomplish this result1 ,i do not see why it should enter into any school curriculum4 ,further1 ,i would remark that1 however interesting a geological treatise may be1 it cannot possibly stimulate the imagination as the practical study of the science is bound to do4 ,one may put into the hands of a youth a clear and well-written description of some particular fossiliferous limestone1 and he may by dint of slavish toil be able to repeat verbatim all that he has read4 ,that is how a good deal of book-knowledge of science is acquired4 ,only think1 however1 of the drudgery it involves--the absolute waste of time and energy4 ,but let us illustrate our lesson by means of a lump of the limestone itself2 let us show him the character of the rock and the nature of its fossil contents1 and his difficulties disappear4 ,better still--let us take him1 if we can1 into a limestone quarry1 and he will be a dull boy indeed if he fails fully to understand what limestone is1 or to realise the fact that the rock he is looking at accumulated slowly1 like existing oceanic formations1 at the bottom of a sea that teemed with animal life4 ,it is unnecessary1 however1 that ,i should illustrate this subject further4 ,i would only repeat that the beginner should be taught from the very first to use his own eyes1 and to draw logical conclusions from the facts which he observes4 ,trained after this manner1 he would acquire1 not only a precise and definite knowledge of what geological data really are1 but he would learn also how to interpret those data4 ,he would become familiar1 in fact1 with the guiding principles of geological inquiry4 ,how much or how little of ,historical ,geology should be given in schools will depend upon circumstances4 ,great care1 however1 should be taken to avoid wearying the youthful student with strings of mere names4 ,what good is gained by learning to repeat the names of fifty or a hundred fossils1 if you cannot recognise any one of these when it is put into your hand8 ,with young beginners ,i should not attempt anything of that kind4 ,if the neighbourhood chanced to be rich in fossils1 ,i should take my pupils out on ,saturday to the sections where they were found1 and let them ply their hammers and collect specimens for themselves4 ,i should describe no fossils which they had not seen and handled4 ,of the more remarkable forms of extinct animals and plants1 which are often represented by only fragmentary remains1 ,i should exhibit drawings showing the creatures as they have been restored by the labours of comparative anatomists4 ,such restorations and ideal views of geological scenes like those given by ,heer1 ,dana1 ,saporta1 and others1 convey far more vivid impressions of the life of a geological period than the most elaborate description4 ,in fine1 the story of our earth should be told much in the same manner as ,scott wrote the history of ,scotland for his grandson4 ,there is no more reason for requiring the juvenile student to drudge through minute geological data before introducing him to the grand results of geological investigation1 than there is for compelling him to study the manuscripts in our ,record ,offices before allowing him to read the history which has been drawn from these and similar sources of information4 ,it is enough if at the beginning of his studies he has already learned the general nature of geological evidence and the method of its interpretation4 ,provided with such a stock of geological knowledge as ,i have indicated1 our youth would leave school with some intelligent appreciation of existing physical conditions1 and a not inadequate conception of world-history4 ,,ii4 ,the ,physical ,features of ,scotland4,b ,b ,scottish ,geographical ,magazine1 vol4 i41 #ahhe4 ,scotland1 like all ,gaul1 is divided into three parts1 namely1 the ,highlands1 the ,central ,lowlands1 and the ,southern ,uplands4 ,these1 as a correctly drawn map will show1 are natural divisions1 for they are in accordance not only with the actual configuration of the surface1 but with the geological structure of the country4 ,the boundaries of these principal districts are well defined4 ,thus1 an approximately straight or gently undulating line taken from ,stonehaven1 in a south-west direction1 along the northern outskirts of ,strathmore to ,glen ,artney1 and thence through the lower reaches of ,loch ,lomond to the ,firth of ,clyde at ,kilcreggan1 marks out with precision the southern limits of the ,highland area and the northern boundary of the ,central ,lowlands4 ,the line that separates the ,central ,lowlands from the ,southern ,uplands is hardly so prominently marked throughout its entire course1 but it follows precisely the same north-east and south-west trend1 and may be traced from ,dunbar along the base of the ,lammermoor and ,moorfoot ,hills1 the ,lowthers1 and the hills of ,galloway and ,carrick1 to ,girvan4 ,in each of the two mountain-tracts--the ,highlands and the ,southern ,uplands--areas of low-lying land occur1 while in the intermediate ,central ,lowlands isolated prominences and certain well-defined belts of hilly ground make their appearance4 ,the statement1 so frequently repeated in class-books and manuals of geography1 that the mountains of ,scotland consist of three 7some writers say five7 ranges is erroneous and misleading4 ,the original author of this strange statement probably derived his ignorance of the physical features of the country from a study of those antiquated maps upon which the mountains of poor ,scotland are represented as sprawling and wriggling about like so many inebriated centipedes and convulsed caterpillars4 ,properly speaking1 there is not a true mountain-range in the country4 ,if we take this term1 which has been very loosely used1 to signify a linear belt of mountains--that is1 an elevated ridge notched by cols or passes and traversed by transverse valleys--then in place of three or five such ranges we might just as well enumerate fifty or sixty1 or more1 in the ,highlands and ,southern ,uplands4 ,or1 should any number of such dominant ridges be included under the term mountain-range1 there seems no reason why all the mountains of the country should not be massed under one head and styled the ,scottish ,range4 ,a mountain-range1 properly so called1 is a belt of high ground which has been ridged up by earth-movements4 ,it is a fold1 pucker1 or wrinkle in the earth's crust1 and its general external form coincides more or less closely with the structure or arrangement of the rock-masses of which it is composed4 ,a mountain-range of this characteristic type1 however1 seldom occurs singly1 but is usually associated with other parallel ranges of the same kind--the whole forming together what is called a mountain-chain1 of which the ,alps may be taken as an example4 ,that chain consists of a vast succession of various kinds of rocks1 which at one time were disposed in horizontal layers or strata4 ,but during subsequent earth-movements those horizontal beds were compressed laterally1 squeezed1 crumpled1 contorted1 and thrown1 as it were1 into gigantic undulations and sharper folds and plications4 ,and1 notwithstanding the enormous erosion or denudation to which the long parallel ridges or ranges have been subjected1 we can yet see that the general contour of these corresponds in large measure to the plications or foldings of the strata4 ,this is well shown in the ,jura1 the parallel ranges and intermediate hollows of which are formed by undulations of the folded strata--the tops of the long hills coinciding more or less closely with the arches1 and the intervening hollows with the troughs4 ,now folded1 crumpled1 and contorted rock-masses are common enough in the mountainous parts of ,scotland1 but the configuration of the surface rarely or never coincides with the inclination of the underlying strata4 ,the mountain-crests1 so far from being formed by the tops of great folds of the strata1 frequently show precisely the opposite kind of structure4 ,in other words1 the rocks1 instead of being inclined away from the hill-tops like the roof of a house from its central ridge1 often dip into the mountains4 ,when they do so on opposite sides the strata of which the mountains are built up seem arranged like a pile of saucers1 one within another4 ,there is yet another feature which brings out clearly the fact that the slopes of the surface have not been determined by the inclination of the strata4 ,the main water-parting that separates the drainage-system of the west from that of the east of ,scotland does not coincide with any axis of elevation4 ,it is not formed by an anticlinal fold or saddleback4 ,in point of fact it traverses the strata at all angles to their inclination4 ,but this would not have been the case had the ,scottish mountains consisted of a chain of true mountain-ranges4 ,our mountains1 therefore1 are merely monuments of denudation1 they are the relics of elevated plateaux which have been deeply furrowed and trenched by running water and other agents of erosion4 ,a short sketch of the leading features presented by the three divisions of the country will serve to make this plain4 99 99 99 99 99 ,the ,highlands4--,the southern boundary of this1 the most extensive of the three divisions1 has already been defined4 ,the straightness of that boundary is due to the fact that it coincides with a great line of fracture of the earth's crust--on the north or ,highland side of which occur slates1 schists1 and various other hard and tough rocks1 while on the south side the prevailing strata are sandstones1 etc41 which are not of so durable a character4 ,the latter1 in consequence of the comparative ease with which they yield to the attacks of the eroding agents--rain and rivers1 frost and ice--have been worn away to a greater extent than the former1 and hence the ,highlands1 along their southern margin1 abut more or less abruptly upon the ,lowlands4 ,looking across ,strathmore from the ,sidlaws or the ,ochils1 the mountains seem to spring suddenly from the low grounds at their base1 and to extend north-east and south-west1 as a great wall-like rampart4 ,the whole area north and west of this line may be said to be mountainous1 its average elevation being probably not less than #aejj feet above the sea4 ,a glance at the contoured or the shaded sheets of the ,ordnance ,survey's map of ,scotland will show better than any verbal description the manner in which our ,highland mountains are grouped4 ,it will be at once seen that to apply the term range to any particular area of those high grounds is simply a misuse of terms4 ,not only are the mountains not formed by plications and folds1 but they do not even trend in linear directions4 ,it is true that a well-trained eye can detect certain differences in the form and often in the colouring of the mountains when these are traversed from south-east to north-west4 ,such differences correspond to changes in the composition and structure of the rock-masses1 which are disposed or arranged in a series of broad belts and narrower bands1 running from south-west to north-east across the whole breadth of the ,highlands4 ,each particular kind of rock gives rise to a special configuration1 or to certain characteristic features4 ,thus1 the mountains that occur within a belt of slate1 often show a sharply cut outline1 with more or less pointed peaks and somewhat serrated ridges--the ,aberuchill ,hills1 near ,comrie1 are an example4 ,in regions of gneiss and granite the mountains are usually rounded and lumpy in form4 ,amongst the schists1 again1 the outlines are generally more angular4 ,quartz-rock often shows peaked and jagged outlines2 while each variety of rock has its own particular colour1 and this in certain states of the atmosphere is very marked4 ,the mode in which the various rocks yield to the weather--the forms of their cliffs and corries--these and many other features strike a geologist at once2 and therefore1 if we are to subdivide the ,highland mountains into ranges1 a geological classification seems the only natural arrangement that can be followed4 ,unfortunately1 however1 our geological lines1 separating one belt or range from another1 often run across the very heart of great mountain-masses4 ,our ranges are distinguished from each other simply by superficial differences of feature and structure4 ,no long parallel hollows separate a range of schist-mountains from the succeeding ranges of quartz-rock1 gneiss1 or granite4 ,and no degree of careful contouring could succeed in expressing the niceties of configuration just referred to1 unless the maps were on a very large scale indeed4 ,a geological classification or grouping of the mountains into linear belts cannot therefore be shown upon any ordinary orographical map4 ,such a map can present only the relative heights and disposition of the mountain-masses1 and these last1 in the case of the ,highlands1 as we have seen1 cannot be called ranges without straining the use of that term4 ,any wide tract of the ,highlands1 when viewed from a commanding position1 looks like a tumbled ocean in which the waves appear to be moving in all directions4 ,one is also impressed with the fact that the undulations of the surface1 however interrupted they may be1 are broad--the mountains1 however they may vary in detail according to the character of the rocks1 are massive1 and generally round-shouldered and often somewhat flat-topped1 while there is no great disparity of height amongst the dominant points of any individual group4 ,let us take1 for example1 the knot of mountains between ,loch ,maree and ,loch ,torridon4 ,there we have a cluster of eight pyramidal mountain-masses1 the summits of which do not differ much in elevation4 ,thus in ,liathach two points reach #cceh feet and #cdhf feet2 in ,beinn ,alligin there are also two points reaching #cjba feet and #cbcb feet respectively2 in ,beinn ,dearg we have a height of #biie feet2 in ,beinn ,eighe are three dominant points--#cahh feet1 #cbag feet1 and #ccji feet4 ,the four pyramids to the north are somewhat lower--their elevations being #bhfj feet1 #bhja feet1 #bcgj feet1 and #bhib feet4 ,the mountains of ,lochaber and the ,monadhliath ,mountains exhibit similar relationships2 and the same holds good with all the mountain-masses of the ,highlands4 ,no geologist can doubt that such relationship is the result of denudation4 ,the mountains are monuments of erosion--they are the wreck of an old table-land--the upper surface and original inclination of which are approximately indicated by the summits of the various mountain-masses and the direction of the principal water-flows4 ,if we in imagination fill up the valleys with the rock-material which formerly occupied their place1 we shall in some measure restore the general aspect of the ,highland area before its mountains began to be shaped out by ,nature's saws and chisels4 ,it will be observed that while streams descend from the various mountains to every point in the compass1 their courses having often been determined by geological structure1 etc41 their waters yet tend eventually to collect and flow as large rivers in certain definite directions4 ,these large rivers flow in the direction of the average slope of the ancient table-land1 while the main water-partings that separate the more extensive drainage-areas of the country mark out1 in like manner1 the dominant portions of the same old land-surface4 ,the water-parting of the ,north-west ,highlands runs nearly north and south1 keeping quite close to the western shore1 so that nearly all the drainage of that region flows inland4 ,the general inclination of the ,north-west ,highlands is therefore easterly towards ,glenmore and the ,moray ,firth4 ,in the region lying east of ,glenmore the average slopes of the land are indicated by the directions of the rivers ,spey1 ,don1 and ,tay4 ,these two regions--the ,north-west and ,south-east ,highlands--are clearly separated by the remarkable depression of ,glenmore1 which extends through ,loch ,linnhe1 ,loch ,lochy1 and ,loch ,ness1 and the further extension of which towards the north-east is indicated by the straight coast-line of the ,moray ,firth as far as ,tarbat ,ness4 ,now1 this long depression marks a line of fracture and displacement of very great geological antiquity4 ,the old plateau of the ,highlands was fissured and split in two--that portion which lay to the north-west sinking along the line of fissure to a great but at present unascertained depth4 ,thus the waters that flowed down the slopes of the north-west portion of the broken plateau were dammed by the long wall of rock on the up-cast1 or south-east side of the fissure1 and compelled to flow off to north-east and south-west along the line of breakage4 ,the erosion thus induced sufficed in the course of time to hollow out ,glenmore and all the mountain-valleys that open upon it from the west4 ,the inclination of that portion of the fissured plateau which lay to the south-east is indicated1 as already remarked1 by the trend of the principal rivers4 ,it was north-east in the ,spey district1 nearly due east in the area drained by the ,don1 east and south-east in that traversed by the ,tay and its affluents1 westerly and south-westerly in the district lying east of ,loch ,linnhe4,c ,thus1 a line drawn from ,ben ,nevis through the ,cairngorm and ,ben ,muich ,dhui ,mountains to ,kinnaird ,point passes through the highest land in the ,south-east ,highlands1 and probably indicates approximately the dominant portion of the ancient plateau4 ,north of that line the drainage is towards the ,moray ,firth2 east of it the rivers discharge to the ,north ,sea2 while an irregular winding line1 drawn from ,ben ,nevis eastward through the ,moor of ,rannoch and southward to ,ben ,lomond1 forms the water-parting between the ,north ,sea and the ,atlantic1 and doubtless marks another dominant area of the old table-land4 ,c ,the geological reader hardly requires to be reminded that many of the minor streams would have their courses determined1 or greatly modified1 by the geological structure of the ground4 ,thus1 such streams often flow along the strike and other lines of weakness1 and similar causes1 doubtless1 influenced the main rivers during the gradual excavation of their valleys4 ,that the valleys which discharge their water-flow north and east to the ,moray ,firth and the ,north ,sea have been excavated by rivers and the allied agents of erosion1 is sufficiently evident4 ,all the large rivers of that wide region are typical4 ,they show the orthodox three courses--namely1 a torrential or mountain-track1 a middle or valley-track1 and a lower or plain-track4 ,the same is the case with some of the rivers that flow east from the great north-and-south water-parting of the ,north-west ,highlands1 as1 for example1 those that enter the heads of ,beauly ,firth1 ,cromarty ,firth1 and ,dornoch ,firth4 ,those1 however1 which descend to ,loch ,lochy and ,loch ,linnhe1 and the sea-lochs of ,argyllshire1 have no lower or plain-track4 ,when we cross the north-and-south water-parting of the ,north-west ,highlands1 we find that many of the streams are destitute of even a middle or valley-track4 ,the majority are mere mountain-torrents when they reach the sea4 ,again1 on the eastern watershed of the same region1 a large number of the valleys contain lakes in their upper and middle reaches1 and this is the case also with not a few of the valleys that open upon the ,atlantic4 ,more frequently1 however1 the waters flowing west pass through no lakes1 but enter the sea at the heads of long sea-lochs or fiords4 ,this striking contrast between the east and west is not due to any difference in the origin of the valleys4 ,the western valleys are as much the result of erosion as those of the east4 ,the present contrast1 in fact1 is more apparent than real1 and arises from the fact that the land area on the ,atlantic side has been greatly reduced in extent by subsidence4 ,the western fiords are merely submerged land-valleys4 ,formerly the ,inner and ,outer ,hebrides were united to themselves and the mainland1 the country of which they formed a part stretching west into the ,atlantic1 as far probably as the present #ajj fathoms line4 ,were that drowned land to be re-elevated1 each of the great sea-lochs would appear as a deep mountain-valley containing one or more lake-basins of precisely the same character as those that occur in so many valleys on the eastern watershed4 ,thus we must consider all the islands lying off the west coast of the ,highlands1 including the major portions of ,arran and ,bute1 as forming part and parcel of the ,highland division of ,scotland4 ,the presence of the sea is a mere accident2 the old lands now submerged were above its level during a very recent geological period--a period well within the lifetime of the existing fauna and flora4 ,the old table-land of which the ,highlands and ,islands are the denuded and unsubmerged relics1 is of vast geological antiquity4 ,it was certainly in existence1 and had even undergone very considerable erosion1 before the ,old ,red ,sandstone period1 as is proved by the fact that large tracts of the ,old ,red ,sandstone formation are found occupying hollows in its surface4 ,glenmore had already been excavated when the conglomerates of the ,old ,red ,sandstone began to be laid down4 ,some of the low-lying maritime tracts of the ,highland area in ,caithness1 and the borders of the ,moray ,firth1 are covered with the sandstones of that age2 and there is evidence to show that these strata formerly extended over wide regions1 from which they have since been removed by erosion4 ,the fact that the ,old ,red ,sandstone deposits still occupy such extensive areas in the north-east of the mainland1 and in ,orkney1 shows that the old table-land shelved away gradually to north and east1 and the same conclusion may be drawn1 as we have seen1 from the direction followed by the main lines of the existing drainage-system4 ,we see1 in short1 in the table-land of the ,highlands1 one of the oldest elevated regions of ,europe--a region which has been again and again submerged either in whole or in part1 and covered with the deposits of ancient seas and lakes1 only to be re-elevated1 time after time1 and thus to have those deposits in large measure swept away from its surface by the long-continued action of running water and other agents of denudation4 99 99 99 99 99 ,the ,central ,lowlands4--,the belt of low-lying ground that separates the ,highlands from the ,southern ,uplands is1 as we have seen1 very well defined4 ,in many places the ,uplands rise along its southern margin as abruptly as the ,highlands in the north4 ,the southern margin coincides1 in fact1 for a considerable distance 7from ,girvan to the base of the ,moorfoots7 with a great fracture that runs in the same direction as the bounding fracture or fault of the ,highlands4 ,the ,central ,lowlands may be described1 in a word1 as a broad depression between two table-lands4 ,a glance at the map will show that the principal features of the ,lowlands have a north-easterly trend--the same trend1 in fact1 as the bounding lines of the division4 ,to this arrangement there are some exceptions1 the principal being the belt of hilly ground that extends from the neighbourhood of ,paisley1 south-east through the borders of ,renfrewshire and ,ayrshire1 to the vicinity of ,muirkirk4 ,the major part of the ,lowlands is under #ejj feet in height1 but some considerable portions exceed an elevation of #ajjj feet1 while here and there the hills approach a height of #bjjj feet--the two highest points 7#bceb and #bcce feet7 being attained in ,ben ,cleugh1 one of the ,ochils1 and in ,tinto4 ,probably the average elevation of the ,lowland division does not exceed #cej or #djj feet4 ,speaking generally1 the belts of hilly ground1 and the more or less isolated prominences1 are formed of more durable rocks than are met with in the adjacent lower-lying tracts4 ,thus the ,sidlaws1 the ,ochil ,hills1 and the heights in ,renfrewshire and ,ayrshire1 are composed chiefly of more or less hard and tough volcanic rocks2 and when sandstones enter into the formation of a line of hills1 as in the ,sidlaws1 they generally owe their preservation to the presence of the volcanic rocks with which they are associated4 ,this is well illustrated by the ,lomond ,hills in ,fifeshire1 the basal and larger portion of which consists chiefly of somewhat soft sandstones1 which have been protected from erosion by an overlying sheet of hard basalt-rock4 ,all the isolated hills in the basin of the ,forth are formed of knobs1 bosses1 and sheets of various kinds of igneous rock1 which are more durable than the sandstones1 shales1 and other sedimentary strata by which they are surrounded4 ,hence it is very evident that the configuration of the ,lowland tracts of ,central ,scotland is due to denudation4 ,the softer and more readily disintegrated rocks have been worn away to a greater extent than the harder and less yielding masses4 ,only in a few cases do the slopes of the hill-belts coincide with folds of the strata4 ,thus1 the northern flanks of the ,sidlaws and the ,ochils slope towards the north-west1 and this also is the general inclination of the old lavas and other rocks of which those hills are composed4 ,the southern flanks of the same hill-belt slope in ,fifeshire towards the south-east--this being also the dip or inclination of the rocks4 ,the crest of the ,ochils coincides1 therefore1 more or less closely1 with an anticlinal arch or fold of the strata4 ,but when we follow the axis of this arch towards the north-east into the ,sidlaws1 we find it broken through by the ,tay valley--the axial line running down through the ,carse of ,gowrie to the north of ,dundee4 ,from the fact that many similar anticlinal axes occur throughout the ,lowlands1 which yet give rise to no corresponding features at the surface1 we may conclude that the partial preservation of the anticline of the ,ochils and ,sidlaws is simply owing to the greater durability of the materials of which those hills consist4 ,had the arch been composed of sandstones and shales it would most probably have given rise to no such prominent features as are now visible4 ,another hilly belt1 which at first sight appears to correspond roughly to an anticlinal axis1 is that broad tract of igneous rocks which separates the ,kilmarnock coal-field from the coal-fields of the ,clyde basin4 ,but although the old lavas of that hilly tract slope north-east and south-west1 with the same general inclination as the surface1 yet examination shows that the hills do not form a true anticline4 ,they are built up of a great variety of ancient lavas and fragmental tuffs or ashes1 which are inclined in many different directions4 ,in short1 we have in those hills the degraded and sorely denuded fragments of an ancient volcanic bank1 formed by eruptions that began upon the bottom of a shallow sea in early ,carboniferous times1 and subsequently became sub-arial4 ,and there is evidence to show that after the eruptions ceased the volcanic bank was slowly submerged1 and eventually buried beneath the accumulating sediments of later ,carboniferous times4 ,the exposure of the ancient volcanic bank at the surface has been accomplished by the denudation of the stratified masses which formerly covered it1 and its existence as a dominant elevation at the present day is solely due to the fact that it is built up of more resistant materials than occur in the adjacent low-lying areas4 ,the ,ochils and the ,sidlaws are of greater antiquity1 but have a somewhat similar history4 ,into this1 however1 it is not necessary to go4 ,the principal hills of the ,lowlands form two interrupted belts1 extending north-east and south-west1 one of them1 which we may call the ,northern ,heights1 facing the ,highlands1 and the other1 which may in like manner be termed the ,southern ,heights1 flanking the great ,uplands of the south4 ,the former of these two belts is represented by the ,garvock ,hills1 lying between ,stonehaven and the valley of the ,north ,esk2 the ,sidlaws1 extending from the neighbourhood of ,montrose to the valley of the ,tay at ,perth2 the ,ochil ,hills1 stretching along the south side of the ,firth of ,tay to the valley of the ,forth at ,bridge-of-,allan2 the ,lennox ,hills1 ranging from the neighbourhood of ,stirling to ,dumbarton2 the ,kilbarchan ,hills1 lying between ,greenock and ,ardrossan2 the ,cumbrae ,islands and the southern half of ,arran2 and the same line of heights reappears in the south end of ,kintyre4 ,a well-marked hollow1 trough1 or undulating plain of variable width1 separates these ,northern ,heights from the ,highlands1 and may be followed all the way from near ,stonehaven1 through ,strathmore1 to ,crieff and ,auchterarder4 ,between the valleys of the ,earn and ,teith this plain attains an abnormal height 7the ,braes of ,doune72 but from the ,teith1 south-west by ,flanders ,moss and the lower end of ,loch ,lomond to the ,clyde at ,helensburgh1 it resumes its characteristic features4 ,it will be observed also that a hollow separates the southern portion of ,arran from the much loftier northern or ,highland area4 ,the tract known as the ,braes of ,doune1 extending from ,glen ,artney south-east to ,strath ,allan1 although abutting upon the ,highlands1 is clearly marked off from that great division by geological composition and structure1 by elevation and configuration4 ,it is simply a less deeply eroded portion of the long trough or hollow4 ,passing now to the ,southern ,heights of the ,lowlands1 we find that these form a still more interrupted belt than the ,northern ,heights1 and that they are less clearly separated by an intermediate depression from the great ,uplands which they flank4 ,they begin in the north-east with the isolated ,garleton ,hills1 between which and the ,lammermoors a narrow low-lying trough or hollow appears4 ,a considerable width of low ground now intervenes before we reach the ,pentland ,hills1 which are in like manner separated from the ,southern ,uplands by a broad low-lying tract4 ,at their southern extremity1 however1 the ,pentlands merge more or less gradually into a somewhat broken and interrupted group of hills which abut abruptly on the ,southern ,uplands1 in the same manner as the ,braes of ,doune abut upon the slate hills of the ,highland borders4 ,in this region the greatest heights reached are in ,tinto 7#bcce feet71 and ,cairntable 7#ahdd feet71 and1 at the same time1 the hills broaden out towards north-west1 where they are continued by the belt of volcanic rocks already described as extending between the coal-fields of the ,clyde and ,kilmarnock4 ,although the ,southern ,heights abut so closely upon the ,uplands lying to the south1 there is no difficulty in drawing a firm line of demarcation between the two areas--geologically and physically they are readily distinguished4 ,no one with any eye for form1 no matter how ignorant he may be of geology1 can fail to see how strongly contrasted are such hills as ,tinto and ,cairntable with those of the ,uplands1 which they face4 ,the ,southern ,heights are again interrupted towards the south-east by the valleys of the ,ayr and the ,doon1 but they reappear in the hills that extend from the ,heads of ,ayr to the valley of the ,girvan4 ,betwixt the ,northern and ,southern ,heights spread the broad ,lowland tracts that drain towards the ,forth1 together with the lower reaches of the ,clyde valley1 and the wide moors that form the water-parting between that river and the estuary of the ,forth4 ,the hills that occur within this inner region of the ,central ,lowlands are usually more or less isolated1 and are invariably formed by outcrops of igneous rock4 ,their outline and general aspect vary according to the geological character of the rocks of which they are composed--some forming more or less prominent escarpments like those of the ,bathgate ,hills and the heights behind ,burntisland and ,kinghorn1 others showing a soft rounded contour like the ,saline ,hills in the west of ,fifeshire4 ,of the same general character as this inner ,lowland region is the similar tract watered by the ,irvine1 the ,ayr1 and the ,doon4 ,this tract1 as we have seen1 is separated from the larger inner region lying to the east by the volcanic hills that extend from the ,southern ,heights north-west into ,renfrewshire4 ,the largest rivers that traverse the ,central ,lowlands take their rise1 as might be expected1 in the mountainous table-lands to the north and south4 ,of these the principal are the ,north and ,south ,esks1 the ,tay and the ,isla1 the ,earn1 and the ,forth1 all of which1 with numerous tributaries1 descend from the ,highlands4 ,and it will be observed that they have breached the line of the ,northern ,heights in three places--namely1 in the neighbourhood of ,montrose1 ,perth1 and ,stirling4 ,the only streams of importance coming north from the ,southern ,uplands are the ,clyde and the ,doon1 both of which in like manner have broken through the ,southern ,heights4 ,now1 just as the main water-flows of the ,highlands indicate the average slope of the ancient land-surface before it was trenched and furrowed by the innumerable valleys that now intersect it1 so the direction followed by the greater rivers that traverse the ,lowlands mark out the primeval slopes of that area4 ,one sees at a glance1 then1 that the present configuration of this latter division has been brought about by the erosive action of the principal rivers and their countless affluents1 aided by the sub-arial agents generally--rain1 frost1 ice1 etc4 ,the hills rise above the average level of the ground1 not because they have been ridged up from below1 but simply owing to the more durable nature of their component rocks4 ,that the ,northern and ,southern ,heights are breached only shows that the low grounds1 now separating those heights from the adjacent ,highlands and ,southern ,uplands1 formerly stood at a higher level1 and so allowed the rivers to make their way more or less directly to the sea4 ,thus1 for example1 the long trough of ,strathmore has been excavated out of sandstones1 the upper surface of which once reached a much greater height1 and sloped outwards from the ,highlands across what is now the ridge of the ,sidlaw ,hills4 ,here then1 in the ,central ,lowlands1 as in the ,highlands1 true mountain- or hill-ranges are absent4 ,but if we are permitted to term any well-marked line or belt of high ground a range1 then the ,northern and ,southern ,heights of the ,lowlands are better entitled to be so designated than any series of mountains in the ,highlands4 99 99 99 99 99 ,the ,southern ,uplands4--,the northern margin of this wide division having already been defined1 we may now proceed to examine the distribution of its mountain-masses4 ,before doing so1 however1 it may be as well to point out that considerable tracts in ,tweeddale1 ,teviotdale1 and ,liddesdale1 together with the ,cheviot ,hills1 do not properly belong to the ,southern ,uplands4 ,in fact1 the ,cheviots bear the same relation to those ,uplands as the ,northern ,heights do to the ,highlands4 ,like them they are separated by a broad hollow from the ,uplands1 which they face--a hollow that reaches its greatest extent in ,tweeddale1 and rapidly wedges out to south-west1 where the ,cheviots abut abruptly on the ,uplands4 ,even where this abrupt contact takes place1 however1 the different configuration of the two regions would enable any geologist to separate the one set of mountains from the other4 ,but for geographical purposes we may conveniently disregard these geological contrasts1 and include within the ,southern ,uplands all the area lying between the ,central ,lowlands and the ,english ,border4 ,if there are no mountains in the ,highlands so grouped and arranged as to be properly termed ranges1 this is not less true of the ,southern ,uplands4 ,perhaps it is the appearance which those ,uplands present when viewed from the ,central ,lowlands that first suggested the notion that they were ranges4 ,they seem to rise like a wall out of the low grounds at their base1 and extend far as eye can reach in an approximately straight line4 ,it seems more probable1 however1 that our earlier cartographers merely meant1 by their conventional hill-shading1 to mark out definitely the water-partings4 ,but to do so in this manner now1 when the large contour maps of the ,ordnance ,survey may be in any one's hands1 is inexcusable4 ,a study of those maps1 or1 better still1 a visit to the tops of a few of the dominant points in the area under review1 will effectually dispel the idea that the ,southern ,uplands consist of a series of ridges zigzagging across the country4 ,like the ,highlands1 the area of the ,southern ,uplands is simply an old table-land1 furrowed into ravine and valley by the operation of the various agents of erosion4 ,beginning our survey of these ,uplands in the east1 we encounter first the ,lammermoor ,hills--a broad undulating plateau--the highest elevations of which do not reach #bjjj feet4 ,west of this come the ,moorfoot ,hills and the high grounds lying between the ,gala and the ,tweed--a tract which averages a somewhat higher elevation--two points exceeding #bjjj feet in height4 ,the next group of mountains we meet is that of the ,moffat ,hills1 in which head a number of important rivers--the ,tweed1 the ,yarrow1 the ,ettrick1 and the ,annan4 ,many points in this region exceed #bjjj feet1 others approach #bejj feet2 and some reach nearly #cjjj feet1 such as ,broad ,law 7#bged feet71 and ,dollar ,law 7#bfhj feet74 ,in the south-west comes the group of the ,lowthers1 with dominant elevations of more than #bjjj feet4 ,then follow the mountain-masses in which the ,nith1 the ,ken1 the ,cree1 the ,doon1 and the ,girvan take their rise1 many of the heights exceeding #bjjj feet1 and a number reaching and even passing #bejj feet1 the dominant point being reached in the noble mountain-mass of the ,merrick 7#bgfd feet74 ,in the extreme south-west the ,uplands terminate in a broad undulating plateau1 of which the highest point is but little over #ajjj feet4 ,all the mountain-groups now referred to are massed along the northern borders of the ,southern ,uplands4 ,in the south-west the general surface falls more or less gradually away towards the ,solway--the #ejj feet contour line being reached at fifteen miles1 upon an average1 from the sea-coast4 ,in the extreme north-east the high grounds descend in like manner into the rich low grounds of the ,merse4 ,between these low grounds and ,annandale1 however1 the ,uplands merge1 as it were1 into the broad elevated moory tract that extends south-east1 to unite with the ,cheviots--a belt of hills rising along the ,english ,border to heights of #aifd feet 7,peel ,fell71 and #bfgf feet 7the ,cheviot74 ,the general configuration of the main mass of the ,southern ,uplands--that is to say1 the mountain-groups extending along the northern portion of the area under review1 from ,loch ,ryan to the coast between ,dunbar and ,st4 ,abb's ,head--is somewhat tame and monotonous4 ,the mountains are flat-topped elevations1 with broad1 rounded shoulders and smooth grassy slopes4 ,standing on the summits of the ,higher hills1 one seems to be in the midst of a wide1 gently undulating plain1 the surface of which is not broken by the appearance of any isolated peaks or eminences4 ,struggling across the bogs and peat-mosses that cover so many of those flat-topped mountains1 the wanderer ever and anon suddenly finds himself on the brink of a deep green dale4 ,he discovers1 in short1 that he is traversing an elevated undulating table-land1 intersected by narrow and broad trench-like valleys that radiate outwards in all directions from the dominant bosses and swellings of the plateau4 ,the mountains1 therefore1 are merely broad ridges and banks separating contiguous valleys2 in a word1 they are1 like the mountains of the ,highlands1 monuments of erosion1 which do not run in linear directions1 but form irregular groups and masses4 ,the rocks that enter into the formation of this portion of the ,southern ,uplands have much the same character throughout4 ,consequently there is less variety of contour and colour than in the ,highlands4 ,the hills are not only flatter atop1 but are much smoother in outline1 there being a general absence of those beetling crags and precipices which are so common in the ,highland regions4 ,now and again1 however1 the mountains assume a rougher aspect4 ,this is especially the case with those of ,carrick and ,galloway1 amongst which we encounter a wildness and grandeur which are in striking contrast to the gentle pastoral character of the ,lowthers and similar tracts extending along the northern and higher parts of the ,southern ,uplands4 ,descending to details1 the geologist can observe also modifications of contour even among those monotonous rounded hills4 ,such modifications are due to differences in the character of the component rocks1 but they are rarely so striking as the modifications that arise from the same cause in the ,highlands4 ,to the trained eye1 however1 they are sufficiently manifest1 and upon a geologically coloured map1 which shows the various belts of rock that traverse the ,uplands from south-west to north-east1 it will be found that the mountains occurring within each of those separate belts have certain distinctive features4 ,such features1 however1 cannot be depicted upon a small orographical map4 ,the separation of those mountains into distinct ranges1 by reference to their physical aspect1 is even less possible here than in the ,highlands4 ,now and again1 bands of certain rocks1 which are of a more durable character than the other strata in their neighbourhood1 give rise to pronounced ridges and banks1 while hollows and valleys occasionally coincide more or less closely with the outcrops of the more readily eroded strata2 but such features are mere minor details in the general configuration of the country4 ,the courses of brooks and streams may have been frequently determined by the nature and arrangement of the rocks1 but the general slope of the ,uplands and the direction of the main lines of water-flow are at right angles to the trend of the strata1 and cannot therefore have been determined in that way4 ,the strata generally are inclined at high angles--they occur1 in short1 as a series of great anticlinal arches and synclinal curves1 but the tops of the grand folds have been planed off1 and the axes of the synclinal troughs1 so far from coinciding with valleys1 very often run along the tops of the highest hills4 ,the foldings and plications do not1 in a word1 produce any corresponding undulations of the surface4 ,mention has been made of the elevated moory tracts that serve to connect the ,cheviots with the loftier ,uplands lying to north-west4 ,the configuration of these moors is tamer even than that of the regions just described1 but the same general form prevails from the neighbourhood of the ,moffat ,hills to the head-waters of the ,teviot4 ,there1 however1 other varieties of rock appear1 and produce corresponding changes in the aspect of the high grounds4 ,not a few of the hills in this district stand out prominently4 ,they are more or less pyramidal and conical in shape1 being built up of sandstones often crowned atop with a capping of some crystalline igneous rock1 such as basalt4 ,the ,maiden ,paps1 ,leap ,hill1 ,needs ,law1 and others are examples4 ,the heights draining towards ,liddesdale and lower reaches of ,eskdale1 composed chiefly of sandstones1 with here and there intercalated sheets of harder igneous rock1 frequently show escarpments and terraced outlines1 but have a general undulating contour2 and similar features are characteristic of the sandstone mountains that form the south-west portion of the ,cheviots4 ,towards the north-east1 however1 the sandstones give place to various igneous rocks1 so that the hills in the north-east section of the ,cheviots differ very much in aspect and configuration from those at the other extremity of the belt4 ,they have a more varied and broken outline1 closely resembling many parts of the ,ochils and other portions of the ,northern and ,southern ,heights of the ,central ,lowlands4 ,the low-lying tracts of ,roxburghshire and the ,merse1 in like manner1 present features which are common to the inner region of the ,central ,lowlands4 ,occasional ridges of hills rise above the general level of the land1 as at ,smailholm and ,stitchell to the north of ,kelso1 while isolated knolls and prominences--some bald and abrupt1 others smooth and rounded--help to diversify the surface4 ,bonchester ,hill1 ,rubers ,law1 the ,dunian1 ,penielheugh1 ,minto ,hills1 and the ,eildons may be mentioned as examples4 ,all of these are of igneous origin1 some being mere caps of basalt resting upon a foundation of sandstone1 while others are the stumps of isolated volcanoes4 ,in the maritime tracts of ,galloway the low grounds repeat1 on a smaller scale1 the configuration of the lofty ,uplands behind1 for they are composed of the same kinds of rock4 ,their most remarkable feature is the heavy mountain-mass of ,criffel1 rising near the mouth of the ,nith to a height of #ahjj feet4 ,everywhere1 therefore1 throughout the region of the ,southern ,uplands1 in hilly and low-lying tracts alike1 we see that the land has been modelled and contoured by the agents of erosion4 ,we are dealing1 as in the ,highlands1 with an old table-land1 in which valleys have been excavated by running water and its helpmates4 ,nowhere do we encounter any linear banks1 ridges1 or ranges as we find described in the class-books1 and represented upon many general maps of the country4 ,in one of those manuals we read that in the southern district the principal range of mountains is that known as the ,lowther ,hills1 which springs off from the ,cheviots1 and1 running in a zigzag direction to the south-west1 terminates on the west coast near ,loch ,ryan4 ,this is quite true1 according to many common maps1 but unfortunately the range exists upon those maps and nowhere else4 ,the zigzag line described is not a range of mountains1 but a water-parting1 which is quite another matter4 ,the table-land of the ,southern ,uplands1 like that of the ,highlands1 is of immense antiquity4 ,long before the ,old ,red ,sandstone period1 it had been furrowed and trenched by running water4 ,of the original contour of its surface1 all we can say is that it formed an undulating plateau1 the general slope of which was towards south-east4 ,this is shown by the trend of the more important rivers1 such as the ,nith and the ,annan1 the ,gala and the ,leader2 and by the distribution of the various strata pertaining to the ,old ,red ,sandstone and later geological periods4 ,thus1 strata of ,old ,red ,sandstone and ,carboniferous age occupy the ,merse and the lower reaches of ,teviotdale1 and extend up the valleys of the ,whiteadder and the ,leader into the heart of the ,silurian ,uplands4 ,in like manner ,permian sandstones are well developed in the ancient hollows of ,annandale and ,nithsdale4 ,along the northern borders of the ,southern ,uplands we meet with similar evidence to show that even as early as ,old ,red ,sandstone times the old plateau1 along what is now its northern margin1 was penetrated by valleys that drained towards the north4 ,the main drainage1 however1 then as now1 was directed towards south-east4 ,many geological facts conspire to show that the ,silurian table-land of these ,uplands has been submerged1 like the ,highlands1 in whole or in part4 ,this happened at various periods1 and each time the land went down it received a covering of newer accumulations--patches of which still remain to testify to the former extent of the submergences4 ,from the higher portions of the ,uplands those accumulations have been almost wholly swept away1 but they have not been entirely cleared out of the ancient valleys4 ,they still mantle the borders of the ,silurian area1 particularly in the north-east1 where they attain a great thickness in the moors of ,liddesdale and the ,cheviot ,hills4 ,the details of the evolution of the whole area of the ,southern ,uplands form an interesting study1 but this pertains rather to ,geology than to ,physical ,geography4 ,it is enough1 from our present point of view1 to be assured that the main features of the country were chalked out1 as it were1 at a very distant geological period1 and that all the infinite variety in the relief of our land has been brought about directly1 not by titanic convulsions and earth-movements1 but by the long-continued working of rain and rivers--of frost and snow and ice1 supplemented from time to time by the action of the sea4 ,the physical features more particularly referred to in this paper are of course only the bolder and more prominent contours--those namely which can be expressed with sufficient accuracy upon sheets of such a size as the accompanying orographical map of ,scotland 7,plate ,i474 ,with larger maps considerably more detail can be added1 and many characteristic and distinguishing features will appear according to the care with which such maps are drawn4 ,in the case of the ,ordnance ,survey map1 on the scale of #a inch to a mile1 the varying forms of the surface are so faithfully delineated as frequently to indicate to a trained observer the nature of the rocks and the geological structure of the ground4 ,the artists who sketched the hills must indeed have had good eyes for form4 ,so carefully has their work been done1 that it is often not difficult to distinguish upon their maps hills formed of such rocks as sandstone from those that are composed of more durable kinds4 ,the individual characteristics of mountains of schist1 of granite1 of quartz-rock1 of slate1 are often well depicted3 nay1 even the varieties of igneous rock which enter into the formation of the numerous hills and knolls of the ,lowlands can frequently be detected by the features which the artists have so intelligently caught4 ,another set of features which their maps display are those due to glaciation4 ,these are admirably brought out1 even down to the smallest details4 ,a glance at such maps as those of ,teviotdale and the ,merse1 for example1 shows at once the direction taken by the old mer de glace4 ,the long parallel flutings of the hill-slopes1 roches moutonnes1 projecting knolls and hills with their tails1 the great series of banks and ridges of stony clay which trend down the valley of the ,tweed--these1 and many more details of interest to specialists1 are shown upon the maps4 ,all over ,scotland similar phenomena are common1 and have been reproduced with marvellous skill on the shaded sheets issued by the ,ordnance ,survey4 ,and yet the artists were not geologists4 ,the present writer is glad of this opportunity of recording his obligations to those gentlemen4 ,their faithful delineations of physical features have given him many valuable suggestions1 and have led up to certain observations which might otherwise not have been made4 ,,iii4 ,mountains3 ,their ,origin1 ,growth1 and ,decay4,d ,d ,scottish ,geographical ,magazine1 vol4 ii41 #ahhf4 ,mountains have long had a fascination for lovers of nature4 ,time was1 however1 when most civilised folk looked upon them with feelings akin to horror2 and good people1 indeed1 have written books to show that they are the cursed places of the earth--the ruin and desolation of their gorges and defiles affording indubitable proof of the evils which befell the world when man lapsed from his primitive state of innocence and purity4 ,all this has changed4 ,it is the fashion now to offer a kind of worship to mountains2 and every year their solitudes are invaded by devotees--some1 according to worthy ,meg ,dods1 rinning up hill and down dale1 knapping the chuckie-stanes to pieces wi' hammers1 like sae mony roadmakers run daft--to see1 as they say1 how the warld was made--others trying to transfer some of the beauty around them to paper or canvas--yet others1 and these perhaps not the least wise1 content1 as old ,sir ,thomas ,browne has it1 to stare about with a gross rusticity1 and humbly thankful that they are beyond the reach of telegrams1 and see nothing to remind them of the fumun et opes strepitumque ,rom4 ,but if the sentiment with which mountains are regarded has greatly changed1 so likewise have the views of scientific men as to their origin and history4 ,years ago no one doubted that all mountains were simply the result of titanic convulsions4 ,the crust of the earth had been pushed up from below1 tossed into great billows1 shivered and shattered--the mountains corresponding to the crests of huge earth-waves1 the valleys to the intervening depressions1 or to gaping fractures and dislocations4 ,this view of the origin of mountains has always appeared reasonable to those who do not know what is meant by geological structure1 and in some cases it is pretty near the truth4 ,a true mountain-chain1 like that of the ,alps1 does indeed owe its origin to gigantic disturbances of the earth's crust1 and in such a region the larger features of the surface often correspond more or less closely with the inclination of the underlying rocks4 ,but in many elevated tracts1 composed of highly disturbed and convoluted strata1 no such coincidence of surface-features and underground structure can be traced4 ,the mountains do not correspond to great swellings of the crust--the valleys neither lie in trough-shaped strata1 nor do they coincide with gaping fractures4 ,again1 many considerable mountains are built up of rocks which have not been convoluted at all1 but occur in approximately horizontal beds4 ,evidently1 therefore1 some force other than subterranean action must be called upon to explain the origin of many of the most striking surface-features of the land4 ,every geologist admits--it is one of the truisms of his science--that corrugations and plications are the result of subterranean action4 ,nor does any one deny that when a true mountain-chain was first upheaved the greater undulations of the folded strata probably gave rise to similar undulations at the surface4 ,some of the larger fractures and dislocations might also have appeared at the surface and produced mural precipices4 ,so long a time1 however1 has elapsed since the elevation of even the youngest mountain-chains of the globe that the sub-arial agents of erosion--rain1 frost1 rivers1 glaciers1 etc4--have been enabled greatly to modify their primeval features4 ,for these mountains1 therefore1 it is only partially true that their present slopes coincide with those of the underlying strata4 ,such being the case with so young a chain as the ,alps1 we need not be surprised to meet with modifications on a still grander scale in mountain-regions of much greater antiquity4 ,in many such tracts the primeval configuration due to subterranean action has been entirely remodelled1 so that hills now stand where deep hollows formerly existed1 while valleys frequently have replaced mountains4 ,and this newer configuration is the direct result of erosion1 guided by the mineralogical composition and structural peculiarities of the rocks4 ,it is difficult1 or even impossible1 for one who is ignorant of geological structure to realise that the apparently insignificant agents of erosion have played so important a rle in the evolution of notable earth-features4 ,it may be well1 therefore1 to illustrate the matter by reference to one or two regions where the geological structure is too simple to be misunderstood4 ,the first examples ,i shall give are from tracts of horizontal strata4 ,many readers are doubtless aware of the fact that our rock-masses consist for the most part of the more or less indurated and compacted sediments of former rivers1 lakes1 and seas4 ,frequently those ancient water-formed rocks have been very much altered1 so as even sometimes to acquire a crystalline character4 ,but it is enough for us now to remember that the crust of the globe1 so far as that is accessible to observation1 is built up mostly of rocks which were originally accumulated as aqueous sediments4 ,such being the case1 it is obvious that our strata of sandstone1 conglomerate1 shale1 limestone1 etc41 must at first have been spread out in approximately horizontal or gently inclined sheets or layers4 ,we judge so from what we know of sediments which are accumulating at present4 ,the wide flats of our river valleys1 the broad plains that occupy the sites of silted-up lakes1 the extensive deltas of such rivers as the ,nile and the ,po1 the narrow and wide belts of low-lying land which within a recent period have been gained from the sea1 are all made up of various kinds of sediment arranged in approximately horizontal layers4 ,now1 over wide regions of the earth's surface the sedimentary strata still lie horizontally1 and we can often tell at what geological period they became converted into dry land4 ,thus1 for example1 we know that the elevated plateau through which the river ,colorado flows is built up of a great series of nearly horizontal beds of various sedimentary deposits1 which reach a thickness of many thousand feet4 ,it is self-evident that the youngest strata must be those which occur at the surface of the plateau1 and they1 as we know1 are of lacustrine origin and belong to the ,tertiary period4 ,now1 ,american geologists have shown that since that period several thousands of feet of rock-materials have been removed from the surface of that plateau--the thickness of rock so carried away amounting in some places to nearly #aj1jjj feet4 ,yet all that prodigious erosion has been effected since early ,tertiary times4 ,indeed1 it can be proved that the excavation of the ,grand ,caon of the ,colorado1 probably the most remarkable river-trench in the world1 has been accomplished since the close of the ,tertiary period1 and is therefore a work of more recent date than the last great upheaval of the ,swiss ,alps4 ,the origin of the caon is self-evident--it is a magnificent example of river-erosion1 and the mere statement of its dimensions gives one a forcible impression of the potency of sub-arial denudation4 ,the river-cutting is about #cjj miles long1 #aa or #ab miles broad1 and varies from #cjjj to #fjjj feet in depth4 ,take another example of what denuding agents have done within a recent geological period4 ,the ,fare ,islands1 some twenty in number1 extend over an area measuring about #gj miles from south to north1 and nearly #ej miles from west to east4 ,these islands are composed of volcanic rocks--beds of basalt with intervening layers of fine fragmental materials1 and are obviously the relics of what formerly was one continuous plateau1 deeply trenched by valleys running in various directions4 ,subsequent depression of the land introduced the sea to these valleys1 and the plateau was then converted into a group of islands1 separated from each other by narrow sounds and fiords4 ,were the great plateau through which the ,colorado flows to be partially submerged1 it would reproduce on a larger scale the general phenomena presented by this lonely island-group of the ,north ,atlantic4 ,the flat-topped buttes and mesas1 and the pyramidal mountains of the ,colorado district would form islands comparable to those of the ,fares4 ,most of the latter attain a considerable elevation above the sea--heights of #agjj1 #bjjj1 #bejj1 and #bhej feet being met with in several of the islands4 ,indeed1 the average elevation of the land in this northern archipelago can hardly be less than #ijj feet4 ,the deep trench-like valleys are evidently only the upper reaches of valleys which began to be excavated when the islands formed part and parcel of one and the same plateau--the lower reaches being now occupied by fiords and sounds4 ,it is quite certain that all these valleys are the work of erosion4 ,one can trace the beds of basalt continuously across the bottoms1 and be quite sure that the valleys are not gaping cracks or fractures4 ,now1 as the strata are approximately horizontal1 it is obvious that the hollows of the surface have nothing whatever to do with undulations produced by earth-movements4 ,the sub-arial erosion of the islands has resulted in the development of massive flat-topped and pyramidal mountains4 ,these stand up as eminences simply because the rock-material which once surrounded them has been gradually broken up and carried away4 ,nothing can well be more impressive to the student of physical geology than the aspect presented by these relics of an ancient plateau 7,plate ,,ii4 ,fig4 #a74 ,standing on some commanding elevation1 such as ,nakkin in ,sudere1 one sees rising before him great truncated pyramids--built up of horizontal beds of basalt rising tier above tier--the mountains being separated from each other by wide and profound hollows1 across which the basalt-beds were once continuous4 ,owing to the parallel and undisturbed position of the strata1 it is not hard to form an estimate of the amount of material which has been removed during the gradual excavation of the valleys4 ,in order to do so we have simply to measure the width1 depth1 and length of the valleys4 ,thus in ,sudere1 which is #ai miles long and #f miles broad1 the bottoms of the valleys are #ajjj feet at least below the tops of the mountains1 and some of the hollows in question are a mile in width4 ,now1 the amount of rock worn away from this one little island by sub-arial erosion cannot be less than that of a mass measuring #aj miles in length by #f miles in breadth1 and #hjj feet in thickness4 ,and yet the ,fare ,islands are composed of rocks which had no existence when the soft clays1 etc41 of the ,london ,basin were being accumulated4 ,all the erosion referred to has taken place since the great upheaval of the ,eocene strata of the ,swiss ,alps4 ,but if the evidence of erosion be so conspicuous in regions composed of horizontal strata1 it is not less so in countries where the rocks are inclined at various angles to the horizon4 ,indeed1 the very fact that inclined strata crop out at the surface is sufficient evidence of erosion4 ,for it is obvious that these outcrops are merely the truncated ends of beds which must formerly have had a wider extension4 ,but while the effects produced by the erosion of horizontal strata are readily perceived by the least-informed observer1 it requires some knowledge of geological structure to appreciate the denudation of curved or undulating strata4 ,and yet there is really no mystery in the matter4 ,all we have to do is by careful observation to ascertain the mode of arrangement of the rocks--this accomplished1 we have no difficulty in estimating the minimum erosion which any set of strata may have experienced4 ,an illustration may serve to make this plain4 ,here1 for example1 is a section across a region of undulating strata 7,fig4 #b74 ,let the line ,a ,b represent the surface of the ground1 and ,c ,d be any datum line--say1 the sea-level4 ,an observer at ,a1 who should walk in the direction of ,b1 would cross successively eight outcrops of coal2 and1 were he incapable of reading the geological structure of the ground1 he might imagine that he had come upon eight separate coal-seams4 ,a glance at the section1 however1 shows that in reality he had met with only two coals1 and that the deceptive appearances1 which might be misread by an incautious observer1 are simply the result of denudation4 ,in this case the tops of a series of curved or arched beds have been removed 7as at ,e71 and1 by protracting the lines of the truncated beds until they meet1 we can estimate the minimum amount of erosion they have sustained4 ,thus1 if the strata between o and p be #cjj feet thick1 it is self-evident that a somewhat greater thickness of rock must have been removed from the top of the anticlinal arch or saddleback at ,e4 ,again1 let us draw a section across strata which have been fractured and dislocated1 and we shall see how such fractures likewise enable us to estimate the minimum amount of erosion which certain regions have experienced4 ,in ,fig4 #c we have a series of strata containing a bed of limestone ,l1 and a coal-seam a4 ,the present surface of the ground is represented by the line ,a ,b4 ,at ,f the strata are traversed by a fault or dislocation--the beds being thrown down for say #ejj feet on the low side of the fault--so that the coal at a#b occurs now at a depth of #ejj feet below its continuation at a#a4 ,at the surface of the ground there is no inequality of level--the beds overlying the coal 7a7 having been removed by denudation4 ,were the missing rocks to be replaced1 they would occupy the space contained within the dotted lines above the present surface ,a ,b4 ,such dislocations are of common occurrence in our coal-fields1 and it is not often that they give rise to any features at the surface4 ,we may thus traverse many level or gently-undulating tracts1 and be quite unconscious of the fact that geologically we have frequently leaped up or dropped down for hundreds of feet in a single step4 ,nay1 some ,scottish streams and rivers flow across dislocations by which the strata have been shifted up or down for thousands of feet1 and in some places one can have the satisfaction of sitting upon rocks which are geologically #cjjj yards below or above those on which he rests his feet4 ,in other words1 thousands of feet of strata have been removed by denudation from the high sides of faults4 ,these1 as ,i have said1 often give rise to no feature at the surface2 but1 occasionally1 when soft rocks have been shifted by dislocations1 and brought against hard rocks1 the latter1 by better resisting denudation than the former1 cause a more or less well-marked feature at the surface1 and thus betray the presence of a fault to the geologist4 ,the phenomena presented by faults1 therefore1 are just as eloquent of denudation as is the truncated appearance of our strata2 and only after we have carefully examined the present extension and mutual relations of our rock-masses1 their varied inclination1 and the size of the dislocations by which they are traversed1 can we properly appreciate the degree of erosion which they have sustained4 ,before we are entitled to express any opinion as to the origin of the surface-features of a country1 we must first know its geological structure4 ,until we have attained such knowledge1 all our views as to the origin of mountains are of less value than the paper they are written upon4 ,i have spoken of the evidence of denudation which we find in our truncated and dislocated rock-masses2 there is yet another line of evidence which ,i may very shortly point out4 ,as every one knows1 there exist in this and many other countries enormous masses of igneous rocks1 which have certainly been extruded from below4 ,now1 some of these rocks1 such as granite1 belong to what is called the plutonic class of rocks2 they are of deep-seated origin--that is to say1 they never were erupted at the surface1 but cooled and consolidated at great depths in the earth's crust4 ,i need not go into any detail to show that this is the case--it is a conclusion based upon incontrovertible facts1 and accepted by every practical geologist4 ,when1 therefore1 we encounter at the actual surface of the earth great mountain-masses of granite1 we know that in such regions enormous denudation has taken place4 ,the granite appears at the surface simply because the thick rock-masses under which it solidified have been gradually removed by erosion4 ,the facts which ,i have now briefly passed in review must convince us that erosion is one of the most potent factors with which the geologist has to deal4 ,we have seen what it has been able to effect in certain tracts composed of strata which date back to a recent geological period1 such as the plateau of the ,colorado and the pyramidal mountains of the ,fare ,islands4 ,if in regions built up of strata so young as the rocks of those tracts the amount of erosion be so great1 we may well expect to meet with evidence of much more extensive denudation in regions which have been subjected for enormously longer periods to the action of the eroding agents4 ,the study of geological structure1 or the architecture of the earth's crust1 has enabled us to group all mountains under these three principal heads3-- #a4 ,mountains of ,accumulation4 #b4 ,mountains of ,elevation4 #c4 ,mountains of ,circumdenudation4 #a4 ,mountains of ,accumulation4--,volcanoes may be taken as the type of this class of mountains4 ,these are1 of course1 formed by the accumulation of igneous materials around the focus or foci of eruption1 and their mode of origin is so generally understood1 and1 indeed1 so obvious1 that ,i need do no more than mention them4 ,of course1 they are all subject to erosion1 and many long-extinct volcanoes are highly denuded4 ,some very ancient ones1 as those of our own country1 have been so demolished that frequently all that remains are the now plugged-up pipes or flues through which the heated materials found a passage to the surface--all those materials1 consisting of lavas and ashes1 having in many cases entirely disappeared4 ,in former times volcanic eruptions often took place along the line of an extensive fissure--the lava1 instead of being extruded at one or more points1 welled-up and overflowed along the whole length of the fissure1 so as to flood the surrounding regions4 ,and this happening again and again1 vast plateaux of igneous rock came to be built up1 such as those of the ,rocky ,mountains1 ,iceland1 the ,fares1 ,antrim and ,mull1 ,abyssinia and the ,deccan4 ,these are called plateaux of accumulation 7see ,fig4 #a71 and all of them are more or less highly denuded1 so that in many cases the plateaux have quite a mountainous appearance4 ,of course1 plateaux of accumulation are not always formed of igneous rocks4 ,any area of approximately horizontal strata of aqueous origin1 rising to a height of a thousand feet or more above the sea1 would come under this class of plateau--the plateau of the ,colorado being a good example4 ,although that plateau is of recent origin1 yet its surface1 as we have seen1 has been profoundly modified by superficial erosion2 and this is true to a greater extent of plateaux which have been much longer exposed to denudation4 ,it is obvious that even mountains and plateaux of accumulation often owe many of their present features to the action of the surface-agents of change4 #b4 ,mountains of ,elevation4--,we have seen that the strata which enter most largely into the composition of the earth's crust1 so far as that is open to observation1 consist of rocks which must originally have been disposed in horizontal or approximately horizontal layers4 ,but1 as every one knows1 the stratified rocks are not always horizontally arranged4 ,in ,scotland they rarely are so4 ,on the contrary1 they are inclined at all angles from the horizon1 and not infrequently they even stand on end4 ,moreover1 they are often traversed by dislocations1 large and small4 ,no one doubts that these tilted and disturbed rocks are evidence of wide-spread earth-movements4 ,and it has been long known to geologists that such movements have happened again and again in this and many other countries where similar disturbed strata occur4 ,some of these movements1 resulting in the upheaval of enormous mountain-masses1 have taken place within comparatively recent geological times4 ,others again date back to periods inconceivably remote4 ,the ,pyrenees1 the ,alps1 the ,caucasus1 the ,himalaya1 which form the back-bone of ,eurasia1 are among the youngest mountains of the globe4 ,the ,highlands of ,scotland and ,scandinavia are immeasurably more ancient2 they are1 in point of fact1 the oldest high grounds in ,europe1 nor are there any mountain-masses elsewhere which can be shown to be older4 ,but while the ,alps and other recent mountains of elevation still retain much of their original configuration1 not a vestige of the primeval configuration of our own ,highlands has been preserved2 their present surface-features have no direct connection with those which must have distinguished them in late ,silurian times4 ,our existing mountains are not1 like those of the ,alps1 mountains of elevation4 ,the structure of a true mountain-chain is frequently very complicated1 but the general phenomena can be readily expressed in a simple diagram4 ,let ,fig4 #e be a section taken across a mountain-chain1 i4e4 at right angles to its trend or direction4 ,the dominant point of the chain is shown at ,b1 while ,a and ,c represent the low grounds4 ,now1 an observer at ,a1 advancing towards ,b1 would note that the strata1 at first horizontal1 would gradually become undulating as he proceeded on his way--the undulations getting always more and more pronounced4 ,he would observe1 moreover1 that the undulations1 at first symmetrical1 as at a1 would become less so as he advanced--one limb of an arch or anticline1 as it is termed1 being inclined at a greater angle than the other1 as at b4 ,approaching still nearer to ,b1 the arches or anticlines would be seen eventually to bend over upon each other1 so as to produce a general dip or inclination of the strata towards the central axis of the chain4 ,crossing that axis 7,b71 and walking in the direction of the low grounds 7,c71 the observer would again encounter the same structural arrangement1 but of course in reverse order4 ,thus1 in its simplest expression1 a true mountain-chain consists of strata arranged in a series of parallel undulations--the greater mountain ridges and intervening hollows corresponding more or less closely to the larger undulations and folds of the strata4 ,now1 could these plicated strata be pulled out1 could the folds and reduplications be smoothed away1 so as to cause the strata to assume their original horizontal position1 it is obvious that the rocks would occupy a greater superficial area4 ,we see1 then1 that such a mountain-chain must owe its origin to a process of tangential or lateral thrusting and crushing4 ,the originally horizontal strata have been squeezed laterally1 and have yielded to the force acting upon them by folding and doubling up4 ,it seems most probable that the larger contortions and foldings which are visible in all true mountain-chains1 owe their origin to the sinking down of the earth's crust upon the cooling and contracting nucleus4 ,during such depressions of the crust the strata are necessarily subjected to enormous lateral compression2 they are forced to occupy less space at the surface1 and this they can only do by folding and doubling-back upon themselves4 ,if the strata are equally unyielding throughout a wide area1 then general undulation may ensue2 but should they yield unequally1 then folding and contortion will take place along one or more lines of weakness4 ,in other words1 the pressure will be relieved by the formation of true mountain-chains4 ,thus1 paradoxical as it may seem1 the loftiest mountains of the globe bear witness to profound depression or subsidence of the crust4 ,the ,andes1 for example1 appear to owe their origin to the sinking down of the earth's crust under the ,pacific2 and so in like manner the ,alps would seem to have been ridged up by depression of the crust in the area of the ,mediterranean4 ,mountain-chains1 therefore1 are true wrinkles in the crust of the earth2 they are lines of weakness along which the strata have yielded to enormous lateral pressure4 ,a glance at the geological structure of the ,alps and the ,jura shows us that these mountains are a typical example of such a chain2 they are mountains of elevation4 ,in the ,jura the mountains form a series of long parallel ridges separated by intervening hollows2 and the form or shape of the ground coincides in a striking manner with the foldings of the strata4 ,in these mountains we see a succession of symmetrical flexures1 the beds dipping in opposite directions at the same angle from the axis of each individual anticline4 ,there each mountain-ridge corresponds to an anticline1 and each valley to a syncline1 or trough-shaped arrangement of strata4 ,but as we approach the ,alps the flexures become less and less symmetrical1 until in the ,alps themselves the most extraordinary convolutions and intricate plications appear1 the strata being often reversed or turned completely upside down4 ,though it is true that the slopes of this great mountain-chain not infrequently correspond more or less closely to the slope or inclination of the underlying rocks1 it must not be supposed that this correspondence is often complete4 ,sometimes1 indeed1 we find that the mountains1 so far from coinciding with anticlines1 are in reality built up of synclinal or basin-shaped strata2 while in other cases deep and broad valleys run along the lines of anticlinal axes 7,fig4 #f74 ,all this speaks to enormous erosion4 ,a study of the geological structure of the ,alps demonstrates that thousands of feet of rock have been removed from those mountains since the time of their elevation4 ,a section drawn across any part of the chain would show that the strata have been eroded to such an extent1 and the whole configuration so profoundly modified1 that it is often difficult1 or even impossible1 to tell what may have been the original form of the surface when the chain was upheaved4 ,and yet the ,alps1 it must be remembered1 are of comparatively recent age1 some of their highly-confused and contorted rocks consisting of marine strata which are of no greater antiquity than the incoherent clays and sands of the ,london ,tertiary basin4 ,now1 when we reflect upon the fact that1 in the case of so young a mountain-chain1 the configuration due to undulations of the strata has been so greatly modified1 and even in many places obliterated1 it is not hard to believe that after sufficient time has elapsed--after the ,alps have existed for as long a period1 say1 as the mountains of middle ,germany--every mountain formed of anticlinal strata shall have disappeared1 and those synclines which now coincide with valleys shall have developed into hills4 ,the reader who may have paid little or no attention to geological structure and its influence upon the form of the ground1 will probably think this a strange and extravagant statement2 yet ,i hope to show presently that it is supported by all that we know of regions of folded strata which have been for long periods of time subjected to denudation4 99 99 99 99 99 #c4 ,mountains of ,circumdenudation4--,in countries composed of undulating and folded strata which have been for long ages exposed to the action of eroding agents1 the ultimate form assumed by the ground is directly dependent on the character of the rocks1 and the mode of their arrangement4 ,the various rock-masses which occur in such a neighbourhood as ,edinburgh1 for example1 differ considerably in their power of resisting denudation4 ,hence the less readily eroded rocks have come in time to form hills of less or greater prominence4 ,such is the case with the ,castle ,rock1 ,corstorphine ,hill1 the ,braids1 the ,pentlands1 etc4 ,these hills owe their existence1 as such1 to the fact that they are composed of more enduring kinds of rock than the softer sandstones and shales by which they are surrounded1 and underneath which they were formerly buried to great depths4 ,some hills1 again1 which are for the most part built up of rocks having the same character as the strata that occur in the adjacent low grounds1 stand up as prominences simply because they have been preserved by overlying caps or coverings of harder rocks--rocks which have offered a stronger resistance to the action of the denuding agents4 ,the ,lomond ,hills are good examples4 ,those hills consist chiefly of sandstones which have been preserved from demolition by an overlying sheet of basalt-rock4 ,but the mode in which rocks are arranged is a not less important factor in determining the shape which the ground assumes under the action of the agents of erosion4 ,thus1 as we have already seen1 flat-topped1 pyramidal mountains1 and more or less steep-sided or trench-like valleys1 are characteristic features in regions of horizontal strata4 ,when strata dip or incline in one general direction1 then we have a succession of escarpments or dip-slopes1 corresponding to the outcrops of harder or less readily eroded beds1 and separated from each other by long valleys1 hollows1 or undulating plains1 which have the same trend as the escarpments 7,fig4 #g74 ,this kind of configuration is well exemplified over a large part of ,england4 ,the general dip or inclination of the ,mesozoic or ,secondary strata throughout that country1 between the shores of the ,north ,sea and the ,english ,channel1 is easterly and south-easterly--so that the outcrops of the more durable strata form well-defined escarpments that face the west and north-west1 and can be followed almost continuously from north to south4 ,passing from the ,malvern ,hills in a south-easterly direction1 we traverse two great escarpments--the first coinciding with the outcrop of the ,oolite1 and forming the ,cotswold ,hills2 and the second corresponding to the outcrop of the ,chalk1 and forming the ,chiltern ,hills4 ,the plains and low undulating tracts that separate these escarpments mark the outcrops of more yielding strata--the low grounds that intervene between the ,cotswolds and the ,malvern ,hills being composed of ,liassic and ,triassic clays and sandstones4 ,in ,scotland similar escarpments occur1 but owing to sudden changes of the dip1 and various interruptions of the strata1 the ,scottish escarpments are not so continuous as those of the sister-country4 ,many of the belts of hilly ground in the ,scottish ,lowlands1 however1 exemplify the phenomena of escarpment and dip-slope4 ,thus1 the ,sidlaws in ,forfarshire consist of a series of hard igneous rocks and interbedded sandstones and flags--the outcrops of which form a succession of escarpments with intervening hollows4 ,the same appearances recur again and again all over the ,lowlands4 ,wherever1 indeed1 any considerable bed of hard rock occurs in a series of less enduring strata--the outcrop of the harder rock invariably forms a well-marked feature or escarpment4 ,as examples1 ,i may refer to ,salisbury ,crags1 ,craiglockhart ,hill1 ,dalmahoy ,crags1 the ,bathgate ,hills1 ,king ,alexander's ,crag1 etc4 ,all these are conspicuous examples of the work of denudation--for it can be demonstrated that each of these rock-masses was at one time deeply buried under sandstones and shales1 and they now crop out at the surface1 and form prominent features simply because the beds which formerly covered and surrounded them have been gradually removed4 ,from what has now been said it will be readily understood that in regions composed of strata the inclination or dip of which is not constant but continually changing in direction1 the surface-features must be more or less irregular4 ,if the strata dip east the outcrops of the harder beds will form escarpments facing the west1 and the direction of the escarpments will obviously change with the direction of the dip4 ,undulating strata of variable composition will1 in short1 give rise to an undulating surface1 but the superficial undulations will not coincide with those of the strata4 ,on the contrary1 in regions consisting of undulating strata of diverse consistency the hills generally correspond with synclinal troughs--or1 in other words1 trough-shaped strata tend to form hills2 while1 on the other hand1 arch-shaped or anticlinal strata most usually give rise to hollows 7see ,fig4 #b74 ,this remarkable fact is one of the first to arrest the attention of every student of physical geology1 and its explanation is simple enough4 ,an anticlinal arrangement of strata is a weak structure--it readily succumbs to the attacks of the denuding agents2 a synclinal arrangement on the contrary1 is a strong structure1 which is much less readily broken up4 ,hence it is that in all regions which have been exposed for prolonged periods to sub-arial denudation synclinal strata naturally come to form hills1 and anticlinal strata valleys or low grounds4 ,in the case of a mountain-chain so recently elevated as that of the ,alps1 the mountain-ridges1 as we have seen1 often coincide roughly with the greater folds of the strata4 ,such anticlinal mountains are weakly built1 and consequently rock-falls and landslips are of common occurrence among them--far more common1 and on a much larger scale1 than among the immeasurably older mountains of ,scandinavia and ,scotland4 ,the valleys of the ,pyrenees1 the ,alps1 and the ,apennines1 are cumbered with enormous chaotic heaps of fallen rock-masses4 ,from time to time peaks and whole mountain-sides give way1 and slide into the valleys1 burying hamlets and villages1 and covering wide tracts of cultivated land4 ,hundreds of such disastrous rock-falls have occurred in the ,alps within historical ages1 and must continue to take place until every weakly-formed mountain has been demolished4 ,the hills and mountains of ,scotland have long since passed through this phase of unstable equilibrium4 ,after countless ages of erosion our higher grounds have acquired a configuration essentially different from that of a true mountain-chain4 ,enormous landslips like that of the ,rossberg are here impossible1 for all such weakly-constructed mountains have disappeared4 ,a little consideration will serve to show how such modifications and changes have come about4 ,when strata are crumpled up they naturally crack across1 for they are not elastic4 ,during the great movements which have originated all mountains of elevation1 it is evident that the strata forming the actual surface of the ground would often be greatly fissured and shattered along the crests of the sharper anticlinal ridges4 ,in the synclinal troughs1 however1 although much fissuring would take place1 yet the strata would be compelled by the pressure to keep together4 ,now1 when we study the structure of such a region as the ,alps1 we find that the tops of the anticlines have almost invariably been removed1 so as to expose the truncated ends of the strata--the ruptured and shattered rock-masses having in the course of time been carried away by the agents of erosion4 ,such mountains are pre-eminently weak structures4 ,let us suppose that the mountains represented in the diagram 7,fig4 #h7 consist of a succession of strata1 some of which are more or less permeable by water1 while others are practically impermeable4 ,it is obvious that water soaking down from the surface will find its way through the porous strata 7p71 and come out on the slopes of the mountains along the joints and cracks 7c7 by which all strata are traversed4 ,under the influence of such springs and the action of frost1 the rock at the surface will eventually be broken up1 and ever and anon larger and smaller portions will slide downwards over the surface of the underlying impermeable stratum4 ,the undermining action of rivers will greatly intensify this disintegrating and disrupting process4 ,as the river deepens and widens its valley 7v71 it is apparent that in doing so it must truncate the strata that are inclined towards it4 ,the beds will then crop out upon the slopes of the valley 7as at b1 b71 and so the conditions most favourable for a landslip will arise4 ,underground water1 percolating through the porous beds 7p71 and over the surface of the underlying impermeable beds 7i1 i1 i71 must eventually bring about a collapse4 ,the rocks forming the surface-slopes of the mountain will from time to time give and slide into the valley1 or the whole thickness of the truncated strata may break away and rush downwards2 and this process must continue so long as any portion of the anticlinal arch remains above the level of the adjacent synclinal troughs4 ,thus it will be seen that an anticlinal arch is a weak structure--a mountain so constructed falls a ready prey to the denuding agents2 and hence in regions which have been exposed to denudation for as long a period as the ,scottish or ,scandinavian uplands1 a mountain formed of anticlinally arranged strata is of very exceptional occurrence4 ,when it does appear1 it is only because the rocks of which it is composed happen to be of a more enduring character than those of the adjacent tracts4 ,the ,ochil ,hills exemplify this point4 ,these hills consist of a great series of hard igneous rocks1 which are arranged in the form of a depressed anticlinal arch--the low grounds lying to the north and south being composed chiefly of sandstones and shales4 ,here it is owing to the more enduring character of the igneous rocks that the anticlinal arch has not been entirely removed4 ,we know1 however1 that these igneous rocks were formerly buried under a great thickness of strata1 and that their present appearance at the surface is simply the result of denudation4 ,if an anticlinal arch be a weak structure1 a synclinal arrangement of strata is quite the opposite4 ,in the case of the former each bed has a tendency to slip or slide away from the axis1 while in a syncline it is just the reverse--the strata being inclined towards and not away from the axis4 ,underground water1 springs1 and frost are enabled to play havoc with anticlinal strata1 for the structure is entirely in their favour4 ,but in synclinal beds the action of these powerful agents is opposed by the structure of the rocks--and great rock-falls and landslips cannot take place4 ,synclinal strata therefore endure1 while anticlinal strata are worn more readily away4 ,even in a true mountain-range so young as the ,alps1 denudation has already demolished many weakly-built anticlinal mountains1 and opened up valleys along their axes2 while1 on the other hand1 synclinal troughs have been converted into mountains4 ,and if this be true of the ,alps1 it is still more so of much older mountain-regions1 in which the original contours due to convolutions of the strata have entirely disappeared 7see ,fig4 #i74 ,the mountains of such regions1 having been carved out and modelled by denuding agents1 are rightly termed mountains of circumdenudation1 for they are just as much the work of erosion as the flat-topped and pyramidal mountains which have been carved out of horizontal strata4 ,the ,scottish ,highlands afford us an admirable example of a mountainous region of undulating and often highly-flexed strata1 in which the present surface-features are the result of long-continued erosion4 ,as already remarked1 this region is one of the oldest land-surfaces in the world4 ,in comparison with it1 the ,pyrenees1 the ,alps1 and the ,himalayas are creations of yesterday4 ,the original surface or configuration assumed by the rocks composing our ,highland area at the time when these were first crushed and folded into anticlines and synclines had already been demolished at a period inconceivably more remote than the latest grand upheaval of the ,alps4 ,even before the commencement of ,old ,red ,sandstone times1 our ,archan1 ,cambrian1 and ,silurian rocks had been planed down for thousands of feet1 so that the bottom beds of the ,old ,red ,sandstone were deposited upon a gently undulating surface1 which cuts across anticlines and synclines alike4 ,in late ,silurian and early post-,silurian times the ,north-west ,highlands probably existed as a true mountain-chain1 consisting of a series of parallel ranges formed by the folding and reduplication of the strata4 ,the recent observations of my friends1 ,professor ,lapworth and ,messrs4 ,peach and ,horne1 in ,sutherland1 have brought to light the evidence of gigantic earth-movements1 by which enormous masses of strata have been convoluted and pushed for miles out of place4 ,we see in that region part of a dissected mountain-chain4 ,the mountain-masses which are there exposed to view are the basal or lower portions of enormous sheets of disrupted rock1 the upper parts of which have been removed by denudation4 ,in a word1 the mountains of ,sutherland are mountains of circumdenudation--they have been carved out of elevated masses by the long-continued action of erosion4 ,to prove this1 one has only to draw an accurate section across the ,north-west ,highlands1 when it becomes apparent that the form or shape of the ground does not correspond or coincide with the convolutions of the strata1 and that a thickness of thousands of feet of rock has been denuded away since those strata were folded and fractured4 ,all over the ,highlands we meet with similar evidence of enormous denudation4 ,the great masses of granite which appear at the surface in many places are eloquent of the result produced by erosion continued for immeasurable periods of time4 ,every geologist knows that granite is a rock which could only have been formed and consolidated at great depths4 ,when1 therefore1 such a rock occurs at the surface1 it is evidence beyond all doubt of prodigious erosion4 ,the granite has been laid bare by the removal of the thick rock-masses underneath which it cooled and consolidated4 ,a glance at any map of ,scotland will show that many river-valleys1 and not a few lakes1 of the ,highlands have a north-east and south-west trend4 ,this trend corresponds to what geologists call the strike of the strata4 ,the rocks of the ,highlands have been compressed into a series of folds or anticlines and synclines1 which have the direction just stated--namely1 north-east and south-west4 ,a careless observer might therefore rashly conclude that these surface-features resembled those of the ,jura--in other words1 that the long parallel hollows were synclinal troughs1 and that the intervening ridges and high grounds were anticlinal arches or saddle-backs4 ,nothing could be further from the truth4 ,a geological examination of the ground would show that the features in question were everywhere the result of denudation1 guided by the petrological character and geological structure of the rocks4 ,several of the most marked hollows run along the backs of anticlinal axes1 while some of the most conspicuous mountains are built up of synclinal or trough-shaped strata4 ,ben ,lawers1 and the depression occupied by ,loch ,tay1 are excellent examples2 and since that district has recently been mapped in detail by ,mr4 ,j4 ,grant ,wilson1 of the ,geological ,survey1 ,i shall give a section 7,fig4 #aj7 to show the relation between the form of the ground and the geological structure of the rocks4 ,this section speaks for itself4 ,here evidently is a case where valleys have been exalted and mountains made low4 ,a well-marked syncline1 it will be observed1 passes through ,ben ,lawers1 while ,loch ,tay occupies a depression scooped out of an equally well-defined anticline--a structure which is just the opposite of that which we should expect to find in a true mountain-chain4 ,it will be also noted that ,glen-,lyon coincides neither with a syncline nor a fault2 it has been eroded along the outcrops of the strata4 ,many of the north-east and south-west hollows of the ,highlands indeed run along the base of what are really great escarpments--a feature which1 as we have seen1 is constantly met with in every region where the strata strike more or less steadily in one direction4 ,in the ,highlands the strata are most frequently inclined at considerable angles1 so that the escarpments succeed each other more rapidly than would be the case if the strata were less steeply inclined4 ,in no case does any north-east and south-west hollow coincide with a structural cavity4 ,loch ,awe has been cited as an example of a superficial depression formed by the inward dip of the strata on either side4 ,but1 as was shown many years ago by my brother1 ,a4 ,geikie1,e this lake winds across the strike of the strata4 ,moreover1 if it owed its existence to a great synclinal fold1 why1 he asks1 does it not run along the same line as far as the same structure continues8 ,it does not do so3 it is not continuous with the synclinal fold1 while vertical strata appear in the middle of the lake1 where1 as my brother remarks1 they have clearly no business to be if the sides of the lake are formed by the inward dip of the schists4 ,e ,trans4 ,edin4 ,geol4 ,soc4 vol4 ii4 p4 #bfg4 ,the ,great ,glen1 as ,i mentioned in the preceding article1 coincides with a fracture or dislocation--a line of weakness along which the denuding agents had worked for many ages before the beginning of ,old ,red ,sandstone times2 and it is possible that smaller dislocations may yet be detected in other valleys4 ,but in each and every case the valleys as we now see them are valleys of erosion2 in each and every case the mountains are mountains of circumdenudation2 they project as eminences because the rock-masses which formerly surrounded them have been gradually removed4 ,we have only to protract the outcrops of the denuded strata--to restore their continuations--to form some faint idea of the enormous masses of rock which have been carried away from the surface of the ,highland area since the strata were folded and fractured4 ,all this erosion speaks to the lapse of long ages4 ,the mountains of elevation which doubtless at one time existed within the ,highland area had already1 as we have seen1 suffered extreme erosion before the beginning of ,old ,red ,sandstone times1 much of the area having been converted into an undulating plateau or plain1 which1 becoming submerged in part1 was gradually overspread by the sedimentary deposits of the succeeding ,old ,red ,sandstone period4 ,those sediments were doubtless derived in large measure from the denudation of the older rocks of the ,highlands1 and since they attain in places a thickness of #bj1jjj feet1 and cover many square miles1 they help us to realise in some measure the vast erosion the ,highland area had sustained before the commencement of the ,carboniferous period4 ,nor must we forget that the ,old ,red ,sandstone formation which borders the ,highlands has itself experienced excessive denudation3 it formerly had a much greater extension1 and doubtless at one time overspread large tracts of the ,highlands4 ,again1 we have to remember that during the ,carboniferous and ,permian periods1 and the later ,mesozoic and ,cainozoic eras1 the ,highlands probably remained more or less continuously in the condition of land4 ,bearing this in mind1 we need not be surprised that not a vestige of the primeval configuration brought about by the great earth-movements of late ,silurian times has been preserved4 ,indeed1 had the ,highland area1 after the disappearance of the ,old ,red ,sandstone inland seas1 remained undisturbed by any movement of elevation or depression1 it must long ago have been reduced by sub-arial erosion to the condition of a low-lying undulating plain4 ,but elevation en masse from time to time took place1 and so running water and its numerous allies have been enabled to carry on the work of denudation4 ,thus in the geological history of the ,scottish ,highlands we may trace the successive phases through which many other elevated tracts have passed4 ,the ,scandinavian plateau1 and many of the mountains of middle ,germany--such1 for example1 as the ,harz1 the ,erzgebirge1 the ,thringer-,wald1 etc4--show by their structure that they have undergone similar changes4 ,first we have an epoch of mountain-elevation1 when the strata are squeezed and crushed laterally1 fractured and shattered--the result being the production of a series of more or less parallel anticlines and synclines1 or1 in other words1 a true mountain-chain4 ,next we have a prolonged period of erosion1 during which running water flows through synclinal troughs1 works along the backs of broken and shattered anticlines1 and makes its way by joints1 gaping cracks1 and dislocations1 to the low grounds4 ,as time goes on1 the varying character of the rocks and the mode of their arrangement begin to tell3 the weaker structures are broken up2 rock-falls and landslips ever and anon take place2 anticlinal ridges are gradually demolished1 while synclines tend to endure1 and thus grow1 as it were1 into hills1 by the gradual removal of the more weakly-constructed rock-masses that surround them4 ,valleys continue to be deepened and widened1 while the intervening mountains1 eaten into by the rivers and their countless feeders1 and shattered and pulverised by springs and frosts1 are gradually narrowed1 interrupted1 and reduced1 until eventually what was formerly a great mountain-chain becomes converted into a low-lying undulating plain4 ,should the region now experience a movement of depression1 and sink under the sea1 new sedimentary deposits will gather over its surface to a depth1 it may be1 of many hundreds or even thousands of feet4 ,should this sunken area be once more elevated en masse--pushed up bodily until it attains a height of several thousand feet--it will form a plateau1 composed of a series of horizontal strata resting on the contorted and convoluted rocks of the ancient denuded mountain-chain4 ,the surface of the plateau will now be traversed by streams and rivers1 and in course of time it must become deeply cleft and furrowed1 the ground between the various valleys rising into mountain-masses4 ,should the land remain stationary1 its former fate shall again overtake it2 it will inevitably be degraded and worn down by the sub-arial agents of erosion1 until once more it assumes the character of a low-lying undulating plain4 ,through such phases our ,highlands have certainly passed4 ,at a very early epoch the ,archan rocks of the north-west were ridged up into great mountain-masses1 but before the beginning of the pre-,cambrian period wide areas of those highly-contorted rocks had already been planed across1 so that when subsidence ensued the pre-,cambrian sandstones were deposited upon a gently undulating surface of highly convoluted strata4 ,another great epoch of mountain-making took place after ,lower ,silurian times1 and true mountain-ranges once more appeared in the ,highland area4 ,we cannot tell how high those mountains may have been1 but they might well have rivalled the ,alps4 ,after their elevation a prolonged period of erosion ensued1 and the lofty mountain-land was reduced in large measure to the condition of a plain1 wide areas of which were subsequently overflowed by the inland seas of ,old ,red ,sandstone times--so that the sediments of those seas or lakes now rest with a violent unconformity on the upturned and denuded edges of the folded and contorted ,silurian strata4 ,at a later geological period the whole ,highland area was elevated en masse1 forming an undulating plateau1 traversed by countless streams and rivers1 some of which flowed in hollows that had existed before the beginning of ,old ,red ,sandstone times4 ,since that epoch of elevation the ,highland area1 although subject to occasional oscillations of level1 would appear to have remained more or less continuously in the condition of dry land4 ,the result is1 that the ancient plateau of erosion has been deeply incised--the denuding agents have carved it into mountain and glen--the forms and directions of which have been determined partly by the original surface-slopes of the plateau1 and partly by the petrological character of the rocks and the geological structure of the ground4 ,illustration3 ,,plate ,,ii4 ,,influence ,,of ,,rock ,,structure ,,on ,,the ,,form ,,of ,,the ,,ground4 ,,fig4 #a4 ,,plateau ,,of ,,accumulation3 ,,horizontal ,,strata1 ,,denuded4 ,,fig4 #b4 ,,synclinal 7,s4,o47 ,,and ,,anticlinal 7,e47 ,,strata1 ,,denuded4 ,,fig4 #c4 ,,faulted ,,strata1 ,,showing ,,denudation4 ,,fig4 #d4 ,,mountain ,,of ,,accumulation1--,,volcano4 ,,fig4 #e4 ,,diagrammatic ,,section ,,of ,a ,,typical ,,mountain ,,chain1 ,,or ,,mountains ,,of ,,upheaval4 ,,fig4 #f4 ,,types ,,of ,,rock ,,structure ,,in ,,the ,,alps 7,,after ,,prof4 ,,heim7 ,the dotted lines show portions of strata1 denuded4 ,,fig4 #g4 ,,escarpments 7e7 ,,and ,,dip ,,slopes 7d74 ,,fig4 #h4 ,,erosion ,,of ,,anticlinal ,,mountains4 ,,fig4 #i4 ,,plateau ,,of ,,erosion1 ,,showing ,,mountains ,,of ,,circumdenudation 7aa74 ,,fig #aj4 ,,section ,,across ,,ben ,,lawers ,,and ,,loch ,,tay1 ,,showing ,,mountains ,,of ,,circumdenudation4 ,the ,edinburgh ,geographical ,institute ,j4 ,g4 ,bartholomew ,f4,r4,g4,s4 ,thus1 in the evolution of the surface-features of the earth1 the working of two great classes of geological agents is conspicuous--the subterranean and the sub-arial4 ,the sinking down of the crust upon the cooling nucleus would appear to have given rise to the great oceanic depressions and continental ridges1 just as the minor depressions within our continental areas have originated many mountain-chains4 ,in the area undergoing depression the strata are subjected to intense lateral pressure1 to which they yield along certain lines by folding up4 ,the strata forming the ,alps1 which are #acj miles broad1 originally occupied a width of #bjj miles2 and similar evidence of enormous compression is conspicuous in the structure of all mountains of elevation4 ,great elevation1 however1 may take place with little or no disturbance of stratification3 wide continental areas have been slowly upheaved en masse1 and sea-bottoms and low-lying plains have in this way been converted into lofty plateaux4,f ,many of the most conspicuous features of the earth's surface1 therefore1 are due directly to subterranean action4 ,all those features1 however1 become modified by denudation1 and eventually the primeval configuration may be entirely destroyed1 and replaced by contours which bear no direct relation to the form of the original surface4 7,see ,fig4 #i47 ,in the newer mountain-chains of the globe the surface-features are still largely those due directly to upheaval2 so in some recently elevated plateaux the ground has not yet been cut up and converted into irregular mountain-masses4 ,many of the more ancient mountain-chains and ranges1 however1 have been exposed so long to the abrading action of the denuding agents that all trace of their original contour has vanished4 ,and in like manner plateaux of great age have been so highly denuded1 so cut and carved by the tools of erosion1 that their plateau character has become obscured4 ,they have been converted into undulating mountainous and hilly regions4 ,everywhere throughout the world we read the same tale of subsidence and accumulation1 of upheaval and denudation4 ,the ancient sedimentary deposits which form the major portion of our land-surfaces1 are the waste materials derived from the demolition of plains1 plateaux1 and mountains of elevation4 ,in some mountain-regions we read the evidence of successive epochs of uplift1 separated by long intervening periods of erosion1 followed by depression and accumulation of newer sediments over the denuded surface4 ,thus the ,alps began to be elevated towards the close of ,palozoic times4 ,erosion followed1 and subsequently the land became depressed1 and a vast succession of deposits accumulated over its surface during the long-continued ,mesozoic era into early ,cainozoic times4 ,again1 a great upheaval ensued1 and the ,mesozoic and ,eocene strata were violently contorted and folded along the flanks of the chain4 ,then succeeded another period of erosion and depression1 which was again interrupted by one or more extensive upheavals4 ,away from those lines of weakness which we call mountain-chains1 we constantly encounter evidence of widespread movements of elevation1 during which broad areas of sea-bottom have been upheaved to the light of day1 and1 after suffering extensive denudation have subsided1 to be again overspread with the spoils of adjacent lands1 and then upheaved once more4 ,and such oscillations of level have occurred again and again4 ,looking back through the long vista of the past1 we see each continental area in a state of flux--land alternating with sea1 and sea with land--mountains and plateaux appearing and disappearing--a constant succession of modifications1 brought about by the antagonistic subterranean and sub-arial agents4 ,the hills are shadows1 and they flow ,from form to form1 and nothing stands2 ,they melt like mists1 the solid lands1 ,like clouds they shape themselves and go4 ,f ,this is the generally accepted view of modern geologists4 ,it is very difficult1 however1 to understand how a wide continental area can be vertically upheaved4 ,it seems more probable that the upheaval of the land is only apparent4 ,the land seems to rise because the sea retreats as the result of the subsidence of the crust within the great oceanic basins4 ,see ,article xiv4 7#ahib47 ,,iv4 ,the ,cheviot ,hills4,g ,g ,from ,good ,words for #ahgf4 ,i4 ,the ridge of high ground that separates ,england from ,scotland is not1 like many other hilly districts1 the beloved of tourists4 ,no guide-book expatiates upon the attractiveness of the ,cheviots2 no cunningly-worded hotel-puffs lure the unwary vagrant in search of health1 or sport1 or the picturesque1 to the quiet dells and pastoral uplands of the ,borders4 ,since the biographer of ,dandie ,dinmont1 of joyous memory1 joined the shades1 no magic sentences1 either in verse or prose1 have turned any appreciable portion of the annual stream of tourists in the direction of the ,cheviots4 ,the scenery is not of a nature to satisfy the desires of those who look for something piquant--something sensational1 as it were4 ,it is therefore highly improbable that the primeval repose of these ,border uplands will ever be disturbed by inroads of the travelling public1 even should some second ,burns arise to render the names of hills and streams as familiar as household words4 ,and yet those who can spare the time to make themselves well acquainted with that region should do so2 they will have no reason to regret their visit1 but very much the reverse4 ,for the scenery is of a kind which grows upon one4 ,it shows no clamant beauties--you cannot have its charms photographed--the passing stranger may see nothing in it to detain him2 but only tarry for a while amongst these green uplands1 and you shall find a strange attraction in their soft outlines1 in their utter quiet and restfulness4 ,for those who are wearied with the crush and din of life1 ,i cannot think of a better retreat4 ,one may wander at will amongst the breezy hills1 and inhale the most invigorating air2 springs of the coolest and clearest water abound1 and there are few of the brooks in their upper reaches which will not furnish natural shower-baths4 ,did the reader ever indulge in such a mountain-bath8 ,if not1 then let him on a summer day seek out some rocky pool1 sheltered from the sun1 if possible1 by birch and mountain-ash1 and1 creeping in below the stream where it leaps from the ledges above1 allow the cool water to break upon his head1 and he will confess to having discovered a new aqueous luxury4 ,then from the slopes and tops of the hills you have some of the finest panoramic views to be seen in this island4 ,nor are there wanting picturesque nooks1 and striking rock scenery amongst the hills themselves3 the sides of the ,cheviot are seamed with some wild1 rugged chasms1 which are just as weird in their way as many of the rocky ravines that eat into the heart of our ,highland mountains4 ,the beauty of the lower reaches of some of the streams that issue from the ,cheviots is well known2 and few tourists who enter the vale of the ,teviot neglect to make the acquaintance of the sylvan ,jed4 ,but other streams1 such as the ,bowmont1 the ,kale1 the ,oxnam1 and the ,rule will also well repay a visit4 ,in addition to all these natural charms1 the ,cheviot district abounds in other attractions4 ,those who are fond of ,border lore1 who love to seek out the sites of old forays1 and battles1 and romantic incidents1 will find much to engage them2 for every stream1 and almost every hill1 is noted in tale and ballad4 ,or if the visitor have antiquarian tastes1 he may rival old ,monkbarns1 and do his best to explain the history of the endless camps1 ramparts1 ditches1 and terraces which abound everywhere1 especially towards the heads of the valleys4 ,to the geologist the district is not less interesting1 as ,i hope to be able1 in the course of these papers1 to show4 ,the geological history of the ,cheviots might be shortly summed up1 and given in a narrative form1 but it will perhaps be more interesting1 and1 at the same time more instructive1 if we shall1 instead1 go a little into detail1 and show first what the nature of the evidence is1 and1 second1 how that evidence may be pieced together so as to tell its own story4 ,i may just premise that my descriptions refer almost exclusively to the ,scottish side of the ,cheviots--which is not only the most picturesque1 but also the most interesting1 both from an antiquarian and geological point of view4 ,the ,cheviots extend from the head of the ,tyne in ,northumberland1 and of the ,liddel in ,roxburghshire1 to ,yeavering ,bell and the heights in its neighbourhood 7near ,wooler71 a distance of upwards of thirty miles4 ,some will have it that the range goes westward so as to include the heights about the source of the ,teviot1 but this is certainly a mistake1 for after leaving ,peel ,fell and crossing to the heights on the other side of the ,liddel ,water1 we enter a region which1 both in its physical aspect and its geological structure1 differs considerably from the hilly district that lies between ,peel ,fell and the high-grounds that roll down to the wide plains watered by the ,glen and the ,till4 ,the highest point in the range is that which gives its name to the hills--namely1 the ,cheviot--a massive broad-topped hill1 which reaches an elevation of #bgfg feet above the sea1 and from which a wonderful panorama can be scanned on a clear day4 ,the top of the hill is coated with peat1 fifteen to twenty feet thick1 in some places4 ,a number of deep ravines trench its slopes1 the most noted of which are ,hen ,hole and the ,bizzle4 ,peel ,fell1 at the other extremity of the range1 is only #aifd feet high1 while the dominant points between ,peel ,fell and the ,cheviot are still lower--ranging from #aejj feet to #ahjj feet4 ,the general character of the hills is that of smooth rounded masses1 with long flowing outlines4 ,there are no peaks1 nor serrated ridges1 such as are occasionally met with in the northern ,highlands2 and the valleys as a rule show no precipitous crags and rocky precipices1 the most conspicuous exceptions being the deep clefts mentioned as occurring in the ,cheviot4 ,the hills fall away with a long gentle slope into ,england1 while on the ,scottish side the descent is somewhat abrupt2 so that upon the whole the northern or ,scottish portion of the ,cheviots has more of the picturesque to commend it than the corresponding districts in ,england4 ,indeed1 the opposite slopes of the range show some rather striking contrasts4 ,the long1 flat-topped elevations on the ,english side1 that sweep south and south-west from ,carter ,fell and ,harden ,edge1 and which are drained by the ,tyne1 the ,rede ,water1 and the ,coquet1 are covered for the most part with peat4 ,sometimes1 however1 when the slope is too great to admit of its growth1 the peat gives place to rough scanty grass and scrubby heath1 which barely suffice to hide the underlying barren sandstone rocks4 ,one coming from the ,scottish side is hardly prepared1 indeed1 for the dreary aspect of this region as viewed from the dominant ridge of the ,cheviots4 ,if in their physical aspect the ,english slopes of these hills are for the most part less attractive than the ,scottish1 it is true also that they offer less variety of interest to the geologist4 ,those who have journeyed in stagecoaching times from ,england into ,scotland by ,carter ,fell1 will remember the relief they felt when1 having surmounted the hill above ,whitelee1 and escaped from the dreary barrens of the ,english border1 they suddenly caught a sight of the green slopes of the ,scottish hills1 and the well-wooded vales of ,edgerston ,burn and ,jed ,water4 ,on a clear day the view from this point is very charming4 ,away to the west stretch in seemingly endless undulations the swelling hills that circle round the upper reaches of ,teviotdale4 ,to east and north-east the eye glances along the bright-green ,cheviots of the ,scottish border1 and marks how they plunge1 for the most part somewhat suddenly1 into the low grounds1 save here and there1 where they sink in gentler slopes1 or throw out a few scattered outposts--abrupt verdant hills that somehow look as if they had broken away from the main mass of the range4 ,from the same standpoint one traces the valleys of the ,rule and the ,jed--sweetest of border streams--stretching north into the well-clothed vale of the ,teviot4 ,indeed1 nearly the whole of that highly-cultivated and often richly-wooded country that extends from the base of the ,cheviots to the foot of the ,lammermuirs1 lies stretched before one4 ,here and there abrupt isolated hills rise up amid the undulating low grounds1 to hide the country behind them4 ,of these the most picturesque are dark ,rubers ,law1 overlooking the ,rule ,water2 ,minto ,crags1 and ,penielheugh with its ugly excrescence of a monument1 both on the north side of the ,teviot2 and the ,eildon ,hills1 which1 as all the world knows1 are near ,melrose4 ,after he has sated himself with the rare beauty of this landscape 7and still finer panoramic views are to be had from the top of ,blackhall ,hill1 ,hownam ,law1 the ,cheviot1 as also from various points on the line of the ,roman ,road and other paths across the hills into ,england71 the observer will hardly fail to be struck by the great variety of outlines exhibited4 ,some of the hills1 especially those to the west and north-west1 are grouped in heavy masses1 and present for the most part a soft1 rounded contour1 the hills being broad atop and flowing into each other with long1 smooth slopes4 ,other elevations1 such as those to the east and north-east of ,carter ,fell1 while showing similar long gentle slopes1 yet are somewhat more irregular in form and broken in outline1 the hills having frequently a lumpy contour4 ,very noteworthy objects in the landscape also are the little isolated hills of the low grounds1 such as ,rubers ,law1 and the ,dunian1 above ,jedburgh4 ,they rise1 as ,i have said1 quite suddenly out of that low gently undulating country that sinks softly into the vales of the ,teviot and the ,tweed4 ,this variety arises from the geological structure of the district4 ,the hills vary in outline partly because they are made up of different kinds of rock1 and partly owing to the mode in which these rocks have been arranged4 ,but notwithstanding all this variety of outline1 one may notice a certain sameness too4 ,flowing outlines are more or less conspicuous all over the landscape4 ,many of the hills1 especially as we descend into ,teviotdale1 seem to have been smoothed or rounded off1 as it were1 so as to present their steepest faces as a rule towards the south-west4 ,and if we take the compass-bearing of the hill-ridges of the same district1 we shall find that these generally trend from south-west to north-east ,so much1 then1 at present for the surface configuration of the ,cheviot region4 ,when we come to treat of the various rock-masses1 and to describe the superficial accumulations underneath which these are often concealed1 we shall be in a better position to give an intelligible account of the peculiar form of the ground1 and the causes to which that configuration must be ascribed4 ,the solid rocks which enter into the composition of the ,cheviots consist mainly of 7#a7 hard grey and blue rocks1 called greywack by geologists1 with which are associated blue and grey shale2 7#b7 various old igneous rocks2 and 7#c7 sandstones1 red and white1 interbedded with which occur occasional dark shales4 ,now1 before we can make any endeavour towards reconstructing in outline the physical geography of the ,cheviot ,hills during past ages1 it is necessary that we should discover the order in which the rock-masses just referred to have been amassed4 ,i shall first describe1 therefore1 some sections where the members of the different series are found in juxtaposition1 for the purpose of pointing out which is the lowest-lying1 and consequently the oldest1 and which occupy the uppermost and intermediate positions4 ,illustration3 ,,fig #a4--;,conglomerate and ,red ,sandstone1 etc41 c1 resting on ,greywack and ,shale1 g4 ,the first section to which reference may be made is exposed in the course of the ,river ,jed1 at ,allars ,mill1 a little above ,jedburgh4 ,this section is famous in its way as having been described and figured by ,dr4 ,hutton1 who may be said to have founded the present system of physical geology4 ,in the bed of the stream are seen certain confused ridges of a greyish blue rock running right across the river course--that is1 in a direction a little north of east and south of west4 ,these ridges are the exposed edges of beds of greywack and shale1 which are here standing on end4 ,the beds are somewhat irregular1 being inclined from the vertical1 now in one direction and now in another1 or1 as a geologist would say1 the dip changes rapidly1 sometimes being up the valley and sometimes down4 ,the same beds continue up the steep bank of the river for a yard or two1 and are there capped by another set of rocks altogether1 namely1 by soft red sandy beds which at the bottom become conglomeratic--that is to say1 they are charged with water-worn stones4 ,the annexed diagram 7,fig4 #a7 will show the general appearances presented3 g represents the vertical greywack and shale1 and c the overlying deposits of conglomerate and red sandy beds4 ,now let us see what this section means4 ,what1 in the first place1 is greywack8 ,the term itself has really no meaning1 being a name given by the miners in the ,harz ,mountains to the unproductive rocks associated with the vein-stones which they work4 ,when we break the rock we may observe that it is a granular mixture of small particles of quartz1 to which sometimes felspar and other minerals are added4 ,the grains are bound together in a hardened matrix of argillaceous or clayey and silicious matter1 blue1 or grey1 or green1 or brown and yellow1 as the case may be4 ,at ,allars ,mill1 and generally throughout the ,cheviot district1 the prevailing colour is a pale greyish blue or bluish grey2 but shades of green and brown often occur4 ,the component particles of the rock are usually rounded or water-worn4 ,again1 we notice that the ridges and bands of rock that traverse the course of the ,jed at ,allars ,mill are merely the outcrops of successive strata or beds4 ,it is clear then that greywack and the grey shales that accompany it are aqueous rocks--that is to say1 they consist of hardened sediment1 which has undoubtedly been deposited in successive layers of variable thickness by water in motion4 ,but since the sediments of rivers and currents are laid down in approximately horizontal planes1 it is evident that if the greywack and shale be sedimentary deposits they have suffered considerable disturbance since the time of their formation2 for1 as we have seen1 the beds1 instead of being horizontal or only gently inclined1 actually approach the vertical4 ,the fact is1 that the outcrops which we see are only the truncated portions of what were formerly rapid undulations or folds of the strata1 the tops of the folds or arches having been cut away by geological agencies1 to which ,i shall refer by-and-by4 ,what were at one time horizontal strata have been crumpled up into great folds1 the folds being squeezed tightly together1 and their upper portions planed away before the overlying red sandy beds were laid down4 ,the accompanying diagram 7,fig4 #b7 may serve to make all this clearer4 ,let ,a ,a represent the present surface of the ground1 and ,b ,b a depth of say fifty feet or a hundred feet from the surface4 ,the continuous lines between ,a and ,b represent the greywack beds as we now see them in section2 the dotted lines above ,a ,a indicate the former extension of the strata1 and the dotted lines below ,b ,b their continuation below that datum line4 ,hence it is obvious that in a succession of vertical or highly inclined beds1 we may have the same strata repeated many times1 the same beds coming again and again to the surface4 ,thus the stratum at ,s is evidently the same bed as that at ,w1 ,x1 ,y1 and ,z4 ,illustration3 ,fig #b4 ,such great foldings or redoublings of strata are most probably originated during subsidence of a portion of the earth's crust4 ,while the ground is slowly sinking down1 the strata underneath are perforce compelled to occupy less space laterally1 and this they can only do by yielding amongst themselves4 ,all folding or contortion on the large scale--that1 namely1 which has affected areas of strata extending over whole countries--seems to have taken place under great pressure2 in other words1 to have been produced at considerable depths from the earth's surface4 ,we can conceive1 therefore1 of a wide tract of land sinking down for hundreds of feet1 and producing at the surface comparatively little change4 ,but a depression of a few hundred feet at the surface implies a considerably greater depression at a depth of several thousand feet from the surface1 and it is at great depths1 therefore1 that the most violent folding must take place4 ,consequently considerable contortion1 and much folding1 and lateral crushing and reduplication of strata may occur1 and yet no trace of this be observable at the surface1 save only a gentle depression4 ,for example1 in ,greenland1 a movement of subsidence has been going on for many years--the land has been slowly sinking down4 ,the rocks at the surface are of course quite undisturbed by this widely-extended movement1 but the strata at great depths may be undergoing much compression and contortion4 ,it follows from such considerations1 that if we now get highly contorted strata covering wide areas at the surface1 we suspect that very considerable denudation has taken place4 ,that is to say1 large masses of rock have been removed by the geological agents of change1 so as to expose the once deeply-buried tops of the arched or curved and folded strata4 ,we may therefore infer from a study of the phenomena in the ,jed at ,allars ,mill1 first1 that the red sandy beds are younger than the greywack and shale1 seeing that they rest upon them2 and1 second1 that a very long period of time must have elapsed between the deposition of the older and the accumulation of the younger set of strata2 for it is obvious that considerable time was required for the consolidation and folding of the greywack1 and an incalculable lapse of ages was also necessary to allow of the gradual wearing away by rain1 frost1 and running water of the great thickness of rocks underneath which the greywack was crumpled4 ,and all this took place before the horizontally-bedded red sandstone and conglomerate gathered over the upturned ends of the underlying strata4 ,the succession of rocks at ,allars ,mill is seen in many other places in the ,cheviot district1 but enough has been said to prove that the greywack beds are the older of the two sets of strata4 ,there is another class of rocks1 the relative position of which we must now ascertain1 for no one shall wander much or far among the ,cheviots without becoming aware of the existence of other kinds of rock than greywack and sandstone4 ,many of the hills east of ,oxnam and ,jed ,waters1 for example1 are composed of igneous masses--of rocks which have had a volcanic origin4 ,as we shall afterwards see1 the whole north-eastern section of the ,cheviots is built up of such rocks4 ,at present1 however1 we are only concerned with the relation which these bear to the greywack and the red sandy beds4 ,now at various localities--for example1 in ,edgerston ,burn1 on the hill-face south of ,plenderleith1 and again along the steep front of ,hindhope and ,blackball ,hills1 which are on the crest of the ,cheviots--we find that the igneous rocks rest upon the greywack and shale 7see ,fig4 #c7 precisely in the same way as do the red sandy beds4 ,they therefore belong to a later date than the greywack4 ,in other places1 again1 we meet with the conglomerates and red sandstones 7c1 ,fig4 #d7 resting upon and wrapping round the igneous rocks1 i1 and thus it becomes quite obvious that the latter occupy an intermediate position between the greywack and shale on the one hand1 and the conglomerate and red sandstone upon the other4 ,illustration3 ,fig4 #c4--;,igneous rocks 7i1 a7 resting on ,greywack and ,shale1 g4 ,illustration3 ,fig4 #d4--;c1 ,conglomerate and ,sandstones1 resting on ,igneous rocks1 i4 ,we have now cleared the way so far1 preparatory to an attempt to trace the geological history of the ,cheviots4 ,the three sets of rocks1 whose mutual relations we have been studying1 are those of which the district is chiefly composed2 but1 as we shall see in the sequel1 there are others1 not certainly of much extent1 but nevertheless having an interesting story to tell us4 ,nor shall we omit to notice the superficial accumulations of clay1 gravel1 sand1 silt1 alluvium1 and peat2 monuments as they are of certain great changes1 climatic and geographical1 which have characterised not the ,cheviots only1 but a much wider area4 ,,ii4 ,if we draw a somewhat straight line from ,girvan1 on the coast of ,ayrshire1 in a north-east direction to the shores of the ,north ,sea1 near ,dunbar1 we shall find that south of that line1 up to the ,english border1 nearly the whole country is composed of various kinds of greywack and shale like the basement beds of the ,cheviot district4 ,here and there1 however1 especially in certain of the valleys and some of the low-lying portions of this southern section of ,scotland1 one comes upon small isolated patches and occasional wider areas of younger strata1 which rest upon and conceal the greywacks and shales4 ,such is the case in ,teviotdale1 the ,cheviot district1 and the country watered by the lower reaches of the ,tweed1 in which regions the bottom beds are hidden for several hundreds of square miles underneath younger rocks4 ,indeed1 the greywack and shale form but a very small portion of the surface in the ,cheviots1 appearing upon a coloured geological map like so many islands or fragments1 as it were1 which have somehow been detached from the main masses of greywack of which the ,lammermuirs and the uplands of ,dumfries and ,selkirk shires are composed4 ,although the bottom rocks of the ,cheviot ,hills are thus apparently separated from the great greywack area1 there can be no doubt that they are really connected with it1 the connection being obscured by the overlying younger strata4 ,for if we could only strip off these latter1 if we could only lift aside the great masses of igneous rock and sandstone that are piled up in the ,cheviot ,hills and the adjoining districts1 we should find that the bottom upon which these rest is everywhere greywack and shale4 ,in part proof of this it may be mentioned that at various places in those districts which are entirely occupied by sandstone and igneous rock1 the streams have cut right down through the younger rocks so as to expose the bottom beds1 as in ,jed ,water at ,allars ,mill4 ,again1 when we trace out the boundaries of any detached areas of greywack we invariably find these bottom beds disappearing on all sides underneath the younger strata by which they are surrounded4 ,one such isolated area occurs in the basin of the ,oxnam ,water1 between ,littletonleys and ,bloodylaws1 a section across which would exhibit the general appearance shown in the accompanying diagram 7,fig4 #e74 ,another similarly isolated patch is intersected by ,edgerston ,burn and the ,jed ,water between ,paton ,haugh and ,dovesford4 ,but the largest of these detached portions appears1 forming the crest of the ,cheviots1 at the head of the ,river ,coquet4 ,there the basement beds occupy the watershed1 extending westward1 some three or four miles1 as far as the sandstones of ,hungry ,law1 while to the north and east they plunge under the igneous rocks of ,brownhart ,law and the ,hindhope ,hills4 ,now it is evident that all those detached and isolated areas of greywack and shale are really connected underground1 and not only so1 but they also piece on in the same way to the great belt of similar strata that stretches from sea to sea across the whole breadth of ,scotland4 ,indeed1 we may observe in the ,cheviot district how long and massive promontories of greywack jut out from that great belt1 and extend often for miles into the areas that are covered with younger strata1 as1 for example1 in the ,brockilaw and ,wolfelee ,hills4 ,a generalised section across the greywack regions of the ,cheviot ,hills would therefore present the appearances shown in the annexed diagram 7,fig4 #f71 in which ,g represents the basement beds1 ,i the igneous rocks1 and ,c the red sandstones1 etc4 ,illustration3 ,fig4 #e4--,section across ,greywack area of ,oxnam ,water2 ,g1 ,greywack and ,shale2 ,c1 ,sandstone1 etc4 ,illustration3 ,fig4 #f4--;,diagram section across ,greywack districts of ,cheviot ,hills4 ,throughout the whole of the district under review the bottom beds are observed to dip at a high angle--the strata in many places being actually vertical--and the edges or crops of the strata run somewhat persistently in one direction1 namely1 from south by west to north by east2 or1 as a geologist would express it1 the beds have an approximately south-west and north-east strike4 ,now as the dip is sometimes to north-west and sometimes to south-east1 it is evident that the rocks have been folded up in a series of rapid convolutions1 and that some of the beds must be often repeated4 ,from the character of the fossils which the bottom beds have yielded we learn that the strata belong to that division of past time which is known as the ,silurian age4 ,these fossils appear to be of infrequent occurrence1 and the creatures of which they are the relics occupied rather a humble place in the scale of being4 ,they are called graptolites 7from their resemblance to pens71 an extinct group of hydroid zoophytes1 apparently resembling the sertularians of our own seas4 ,the general appearance of the ,silurian strata of the ,cheviots is indicative of deposition in comparatively quiet water1 but how deep that water was one cannot say4 ,upon the whole1 the beds look not unlike the sediments that gather in calm reaches of the sea1 such as estuaries1 betokening the presence of some not distant land from which fine mud and sand were washed down4 ,another proof that some of the strata at all events were accumulated not far from a shore-line1 is found in certain coarse bands of grit and pebbles1 which are not likely to have been formed in deep water4 ,this evidence1 however1 cannot be considered decisive1 and in the present state of our knowledge all that we can assert with anything like confidence is simply this3--,that during the deposition of the ,silurian strata the whole of the ,cheviot area lay under water--existed1 in short1 as a muddy sea-bottom1 in the slime of which flourished here and there1 in favourable spots1 those minute hydroid animals called graptolites4 ,between the deposition of the ,silurian and the formation of the rocks that come next in order a long interval elapsed1 during which the mud1 sand1 and grit that gathered on the floor of the ancient sea were hardened into solid masses1 and eventually squeezed together into great folds and undulations4 ,it has already been pointed out that these changes could hardly have been effected save under extreme pressure1 and this consideration leads us to infer that a great thickness of strata has been removed entirely from the ,cheviot district1 so as to leave no trace of its former existence4 ,long before the deposition of the younger strata that now rest upon and conceal the ,silurian rocks1 the action of the denuding forces--the sea1 frosts1 rain1 and rivers--had succeeded in not only sweeping gradually away the strata underneath which the bottom beds were folded1 but in deeply scarping and carving these bottom beds themselves4 ,can we form any reasonable conjecture as to the geological age of the strata underneath which the bottom beds of the ,cheviots were folded1 and which1 as we have seen1 had entirely disappeared before the younger rocks of the district were accumulated8 ,well1 it is obvious that the missing strata must have been of later formation than the bottom beds1 and it is equally evident that they must have been of much more ancient date than the igneous rocks of the ,cheviot ,hills4 ,now1 as we shall afterwards see1 these igneous rocks belong to the ,old ,red ,sandstone age1 that is to say1 to the age that succeeded the ,silurian4 ,how is it then1 if the bottom beds be really of ,silurian and the igneous rocks of ,old ,red ,sandstone age1 that a gap is said to exist between them8 ,the explanation of this apparent contradiction is not far to seek4 ,when we compare the fossils that occur in the ,silurian strata of the ,cheviot ,hills and the districts to the west1 with the organic remains disinterred from similar strata elsewhere1 as in ,wales for example1 we find that the bottom beds of the ,cheviots were in all probability accumulated at approximately the same time as certain strata that occur in the middle division of the ,upper ,silurian4 ,in ,wales and in ,cumberland the strata that approximate in age to the ,silurian of the ,cheviots are covered by younger strata belonging to the same formation which reach a thickness of several thousand feet4 ,it may quite well be1 therefore1 that the succession of ,silurian strata in the ,cheviots was at one time more complete than it is now4 ,the upper portions of the formation which are so well developed in ,wales and ,cumberland1 and which are likewise represented to a small extent in ,scotland1 had in all probability their equivalents in what are our border districts4 ,in other words1 there are good grounds for believing that the existing ,silurian rocks of the ,cheviots were in times preceding the ,old ,red ,sandstone age covered with younger strata belonging to the same great system4 ,the missing ,silurian strata of the ,cheviots may have attained a thickness of several thousand feet1 and underneath such a mass of solid rock the lower-lying strata might well have been consolidated and subsequently squeezed into folds4 ,we now pass on to consider the next chapter in the geological history of the ,cheviot ,hills4 ,as we proceed in our investigations it will be noticed that the evidence becomes more abundant1 and we are thus enabled to build up the story of the past with more confidence1 and with fuller details4 ,for it is with geological history as with human records--the further back we go in time the scantier do the facts become4 ,the rocks upon which ,nature writes her own history are palimpsests1 on which the later writing is ever the most easily deciphered4 ,nay1 she cannot compile her newer records without first destroying some of those compiled in earlier times4 ,the sediments accumulating in modern lake and sea are but the materials derived from the degradation of the rocks we see around us1 just as these in like manner have originated from the demolition of yet older strata4 ,thus the further we trace back the history of our earth1 the more fragmentary must we expect the evidence to be2 and conversely1 the nearer we approach to the present condition of things the more abundant and satisfactory must the records become4 ,accordingly1 we find that the igneous rocks of the ,cheviot ,hills tell us considerably more than the ancient ,silurian deposits upon which they rest4 ,the surface of the latter appears to be somewhat irregular underneath the igneous rocks1 showing that hills and valleys1 or an undulating table-land1 existed in the ,cheviot district prior to the appearance of the younger formation4 ,but before we attempt to summarise the history of that formation1 it is necessary to give some description1 however short1 of the rocks that compose it4 ,these consist chiefly of numerous varieties of a rock called porphyrite by geologists1 piled in more or less irregular beds1 one on top of another1 in a somewhat confused manner4 ,the colour of the freshly fractured rocks is very variable1 being usually some shade of blue or purple2 but pink1 red1 brown1 greenish1 and dark grey or almost black varieties also occur4 ,some of the rocks are finely crystalline2 others1 again1 are much coarser1 while many are compact1 or nearly so1 a lens being required to detect a crystalline texture4 ,the mineral called felspar is usually scattered more or less abundantly through the matrix or base1 which itself is composed principally of felspathic materials4 ,besides distinct scattered crystals of felspar1 other minerals often occur in a similar manner2 mica and hornblende being the commonest4 ,occasionally the rocks contain numerous circular1 oval1 or flattened cavities1 which are sometimes so abundant as to give the appearance of a kind of coarse slag to the porphyrite4 ,these little cavities1 however1 are usually filled up with mineral matter--such as calcspar1 calcedony1 jasper1 quartz1 etc4 ,sometimes also cracks1 crannies1 and crevices of some size have been sealed up with similar minerals4 ,now nearly all these appearances are specially characteristic of rocks which have at one time been in a state of igneous fusion2 nor can there be any doubt that the ,cheviot porphyrites are merely solidified lava-beds1 which have been poured out from the bowels of the earth4 ,in modern lavas we may notice not only a crystalline texture1 but frequently also we observe those in our porphyrites4 ,such cavities are due to the expansive force of the vapours imprisoned in the molten mass at the time of eruption4 ,they form chiefly towards the upper surface of a lava stream1 and are often drawn out or flattened in the direction in which the lava flows4 ,thus a stream of lava1 as it creeps on its way1 becomes slaggy and scoriaceous or cindery above and in front1 and as the molten mass within continues to flow1 the slags and cinders that cover its face tumble down before it1 and form the pavement upon which the stream advances4 ,in this way slags and cinders become incorporated with the bottom of the lava1 and hence it is that so many volcanic rocks are scoriaceous1 as well below as above4 ,the vapours which produce the cavities usually contain minerals in solution1 and these1 as the lava cools1 are frequently deposited1 partially filling up the vesicles1 so as to form what are called geodes4 ,but many of the cavities have been filled in another way--by the subsequent infiltration of water carrying mineral matter in solution4 ,and since we know that all rocks are so permeated by water1 it is clear that the cavities may have received their contents during many successive periods1 after the solidification of the rock in which they occur4 ,it is in this manner that the jaspers1 calcedony1 and beautiful agates of commerce have been formed4 ,rocks abundantly charged with cavities are said to be vesicular1 and when the vesicles are filled with mineral matter1 then the mass becomes1 in geological language1 amygdaloidal1 from the almond-like shape assumed by the flattened vesicles4 ,now all the appearances described above1 and many others hardly less characteristic of true lavas1 are to be met with amongst those porphyrites which1 as ,i have said1 form the major portion of the ,cheviot ,hills4 ,from the valley of the ,oxnam1 east by ,cessford1 ,morebattle1 and ,hoselaw1 and south by ,edgerston1 ,letham1 ,browndeanlaws1 and ,hindhope1 the porphyrites extend over the whole area1 sweeping north-east across the border on to the heights above the ,rivers ,glen and ,till4 ,in the hills at ,hindhope we notice a good display of the oldest beds of the series4 ,at the base occurs a very peculiar rock resting upon the ,silurian1 and thus forming the foundation of the porphyrites4 ,it varies in colour1 being pink1 grey1 green1 red1 brown1 or variously mottled4 ,sometimes it is fine-grained and gritty1 like a soft1 coarse-grained sandstone2 at other times it is not unlike a granular porphyrite2 but when most typically developed it consists of a kind of coarse angular gravel embedded in a gritty matrix4 ,the stones sometimes show distinct traces of arrangement into layers2 but they are often heaped rudely together with little or no stratification at all4 ,they consist chiefly of fragments of porphyrites2 but bits of ,silurian rocks also occur amongst them4 ,this peculiar deposit unquestionably answers to the heaps of dust1 sand1 stones1 and bombs which are shot out of modern volcanoes2 it is a true tuff--that is1 a collection of loose volcanic ejectamenta4 ,upon what kind of surface did it fall8 ,long before the eruptions began1 the ,silurian rocks had been sculptured into hills and valleys by the action chiefly of the sub-arial forces1 and it was upon these hills and in these valleys that the igneous materials accumulated4 ,it is difficult to say1 however1 whether at this period the ,cheviot district was above or under water4 ,the traces of bedding in the tuff would seem to indicate the assorting power of water2 but the evidence is too slight to found upon1 because we know that in modern eruptions1 loose ejectamenta frequently assume a kind of irregular bedded arrangement4 ,for aught we can say to the contrary1 therefore1 dry land may have extended across what is now southern ,scotland and northern ,england when the first rumblings of volcanic disturbance shook the ,cheviot area4 ,be that as it may1 we know that the volcanic outbursts began in those old times1 as they almost invariably commence now1 by a discharge of sand1 small stones1 blocks1 and cinders4 ,these1 we may infer1 covered a wide area round the centre of dispersion--the chief focus of eruption being probably in the vicinity of the big ,cheviot1 where a mass of granite seems to occupy the core or deep-seated portion of the old volcanic centre4 ,the locality where the tuff occurs is some nine miles or so distant from this point1 and the intervening ground could hardly have escaped being more or less thickly sprinkled with the same materials4 ,the whole of that intervening ground1 however1 now lies deeply buried under the massive streams of once-molten rock that followed in succession after the first dispersion of stones and dbris4 ,although1 as ,i have said1 it may be doubted whether at the beginning of their activity the ,cheviot volcanoes were sub-aqueous1 yet there are not a few facts that lead to the inference that the eruption of the porphyrites took place for the most part1 if not exclusively1 under water4 ,the beds are occasionally separated by layers of sandstone1 grit1 and conglomerate2 but such beds are rare1 and true tuffs are rarer still4 ,if the outbursts had been sub-arial1 we ought surely to have met with these latter in greater abundance1 while we should hardly have expected to find such evidently water-arranged strata as do occur here and there4 ,the porphyrites themselves present certain appearances which lead to the same conclusion4 ,thus we may observe how the bottoms of the beds frequently contain baked or hardened sand and mud1 showing that the molten rock had been poured out over some muddy or sandy bottom1 and had caught up and enclosed the soft1 sedimentary materials1 which now bear all the marks of having been subjected to the action of intense heat4 ,sometimes1 indeed1 the old lava-streams seem to have licked up beds of unconsolidated gravel1 the water-worn stones being now scattered through their under portions4 ,as no fossils occur in any of the beds associated with the porphyrites1 one cannot say whether the latter flowed into the sea or into great freshwater lakes4 ,neither can we be certain that towards their close the eruptions were not sub-arial4 ,they may quite well have been so4 ,the porphyrites attain a thickness of probably not less than fifteen hundred or two thousand feet1 and the beds which we now see are only the basal1 and therefore the older portions of the old volcanoes4 ,the upper parts have long since disappeared1 the waste of the igneous masses having been so great that only the very oldest portions now remain1 and these1 again1 are hewn and carved into hill and valley4 ,any loose accumulation of stones and dbris1 therefore1 which may have been thrown out in the later stages of the eruptions1 must long ere this have utterly disappeared4 ,we can point to the beds which mark the beginning of volcanic activity in the ,cheviots2 we can prove that volcanoes continued in action there for long ages1 great streams of lava being poured out--the eruptions of which were preceded and sometimes succeeded by showers of stones and dbris2 we can show1 also1 that periods of quiescence1 more or less prolonged1 occasionally intervened1 at which times water assorted the sand and mud1 and rounded the stones1 spreading them out in layers4 ,but whether this water action took place in the sea or in a lake we cannot tell4 ,indeed1 for aught one can say1 some of the masses of rounded stones ,i refer to may point to the action of mountain torrents1 and thus be part evidence that the volcanoes were sub-arial4 ,if we are thus in doubt as to some of the physical conditions that obtained in the ,cheviot district during the accumulation of the porphyrites and their associated beds1 we are left entirely to conjecture when we seek to inquire into the conditions that prevailed towards the close of the volcanic period4 ,for just as we have proof that before this period began the ,silurian strata had been subjected to the most intense denudation--had1 in short1 been worn into hill and valley--so do we learn from abundant evidence that the rocks representing the old volcanoes of the ,cheviots are merely the wrecks of formerly extensive masses4 ,not only have the upper portions of these volcanoes been swept away1 but their lower portions1 likewise1 have been deeply incised1 and thousands of feet of solid rock have been carried off by the denuding forces4 ,and by much the greater part of all this waste took place before the accumulation of those sandstones which now rest upon the worn outskirts of the old volcanic region4 ,,iii4 ,some reference has already been made 7see p4 #fd7 to the general appearance presented by the valleys of the ,cheviots4 ,in their upper reaches they are often rough and craggy2 narrow dells1 in fact1 flanked with steep shingle-covered slopes1 and occasionally overlooked by beetling cliffs1 or fringed with lofty scaurs of decomposing rocks4 ,as we follow down the valleys they gradually widen out2 the hill-slopes becoming less steep1 and retiring from the stream so as to leave a narrow strip of meadow-land through which the clear waters canter gaily on to the low grounds of the ,teviot4 ,in their middle reaches these upland dales are not infrequently well cultivated to a considerable height1 as in the districts between ,hownam and ,morebattle1 and between ,belford and ,yetholm--the former in the valley of the ,kale1 and the latter in that of the ,bowmont4 ,it is noticeable that all the narrower and steeper reaches lie among ,silurian strata and ,old ,red ,sandstone porphyrites4 ,no sooner do we leave the regions occupied by these tough and hard rock-masses than the whole aspect of the scenery changes4 ,the surrounding hills immediately lose in height and fall away into a softly undulating country1 through which the streams and rivers have dug for themselves deep romantic channels4 ,nevertheless1 it is a fact1 as we shall see by-and-by1 that south-west of the region occupied by the igneous rocks of the ,cheviot ,hills1 all the higher portions of the range 7,hungry ,law1 ,carter ,fell1 ,peel ,fell1 etc47 are built up of sandstones4 ,for the present1 however1 ,i confine attention to those valleys whose upper reaches lie either wholly or in part among igneous rocks or ,silurian strata4 ,a typical and certainly the most beautiful example is furnished us by the vale of the ,river ,jed4 ,this stream rises among the sandstone heights which have just been mentioned as composing the south-west portion of the ,cheviot range4 ,the first seven or eight miles of its course lead us through a broad open valley1 which has been hollowed out almost exclusively in sandstones and shales2 by-and-by1 however1 we are led into a ,silurian tract1 and thereupon the valley contracts and the hill-slopes descend more steeply to the stream4 ,but we soon leave the grassy glades of this ,silurian tract and enter all at once upon what may be termed the lower reaches of the ,jed4 ,no longer cooped up in the rocky gully1 painfully worn for itself in the hard greywack and shales1 the stream now winds through a much deeper and broader channel which has evidently been excavated with greater ease4 ,precipitous banks and scaurs here overlook the river at every bend1 the banks becoming higher and higher and retiring further and further from each other1 as the water glides on its way1 until at last they fairly open upon the broad vale of the ,teviot4 ,sometimes the river flows along one side of its valley for a considerable distance1 and whenever this is the case1 it gives us a line of bold cliffs which are usually flanked on the opposite side by sloping ground4 ,this is the general character of all valleys of erosion1 and especially of the lower reaches of the ,jed4 ,a glance at the cliffs and scaurs of the ,jed shows that they consist of horizontal or gently undulating strata of soft earthy1 friable1 shaly sandstone1 arranged in thin beds and bands1 which alternate rapidly with crumbling1 sandy1 and earthy shales2 the whole forming a loose and unconsolidated mass that readily becomes a prey to the action of the weather1 rain1 frost1 and running water4 ,the prevailing colour is a dull red1 but pale yellow1 white1 green1 and purple discolorations are visible when the strata are closely scanned4 ,the finest sections occur between ,glen ,douglas and ,inchbonnie1 and at ,mossburnford1 but the cliffs throughout present the same general appearance1 and are picturesque in the highest degree4 ,everywhere the banks are thickly wooded1 and even the steep red scaurs are dashed and flecked with greenery1 which droops and springs from every ledge and crevice in which a root can fix itself4 ,how vivid and striking is the contrast between the fresh delicate green of early summer and the rich warm tint of these rocks1 which when lit up by the setting sun seem almost to glow and burn6 ,well may the good folk of ,jedburgh be proud of the lovely valley in which their lot is cast4 ,in no similar district in ,scotland will the artist meet with a greater number of such delicious bits1 in which all the charms of wood and water1 of meadow and rock are so harmoniously combined4 ,it is not with the scenic beauties of the ,jed1 however1 that we have at present to do4 ,i wish the reader to examine with me certain appearances visible at the base of the red beds1 where these rest upon those older rocks which have formed the subject of the preceding papers4 ,in the bed of the river at ,jedburgh1 we see the junction between the red beds and the ,silurian strata1 and may observe how the bottom portions of the former1 which repose immediately upon the greywacks1 are abundantly charged with well-rounded and water-worn stones4 ,many of these stones consist of greywack1 hardened grit1 and other kinds of rock1 and most of them undoubtedly have been derived from ,silurian strata4 ,in other districts where the old igneous rocks of the ,cheviots form the pavement upon which the red beds repose1 the stones in the lower portions of the latter are made up chiefly of rounded fragments of the underlying porphyrites4 ,all which clearly shows that the red beds have been built out of the ruins of the older strata of the district4 ,this is unquestionably the origin not only of the conglomerates1 but of all the red beds through which the ,river ,jed cuts its way from the base of the hills to the ,teviot4 ,when we trace out the boundary of these beds1 we find that this leads us along the base of the hills1 close to the hill-foot2 and not only so1 but it frequently takes us into the hill-valleys also4 ,and this shows that the ,cheviots had already been deeply excavated by streams before any portion of the red beds was deposited4 ,i have said that the red beds are approximately horizontal2 sometimes1 however1 they have a decided dip or inclination1 and when this is continuous1 it is invariably in a direction away from the hills4 ,thus as we traverse the ground from the hill-foot to the ,teviot1 we pass over the outcrops of the red beds and slowly rise from a lower to a higher geological position4 ,the strata1 however1 are generally so flat that their dip is often not greater than the average slope or inclination of the ground4 ,hence when we ascend the valley-slopes from the stream1 we soon reach the higher beds of the series1 as1 for example1 in the undulating heights that overlook the ,jed in the neighbourhood of ,jedburgh4 ,in that district a number of quarries have been opened1 in which the upper beds of the red series are well exposed1 as at ,ferniehirst1 ,tudhope1 etc4 ,these consist of thick beds of greyish white1 yellowish1 and reddish sandstones1 which1 unlike the crumbling earthy deposits below1 are quite suitable for building purposes4 ,scales of fish and plant remains are often met with in the thick sandstones1 but the underlying earthy1 friable red beds appear to be quite destitute of any organic remains4 ,let us now briefly recapitulate the main facts we have just ascertained4 ,they are these3--#a4 ,all the low grounds that abut upon the hills are composed of horizontal or nearly horizontal strata1 which consist chiefly of red earthy beds1 passing down into conglomerates1 and up into whitish and reddish sandstones4 #b4 ,the conglomeratic portion forms the boundary of the series1 fringing the outskirts of the hills1 and resting sometimes upon ,silurian strata and sometimes upon ,old ,red ,sandstone igneous rocks4 #c4 ,fossils occur in the white and red sandstones1 but seem to be wanting in the underlying red earthy beds4 ,illustration3 ,fig4 #g4--,s1 ,silurian strata2 i1 ,old ,red ,sandstone ,igneous ,rocks2 a#a1 ,conglomerate2 a#b1 ,red earthy beds2 a#c1 ,white and ,red ,sandstones4 ,the accompanying diagram 7,fig4 #g7 gives a generalised view of the relation borne by the red beds to the older rocks of the ,cheviots4 ,it will be seen that the former rest unconformably upon the ,old ,red ,sandstone igneous rocks1 and also1 of course1 upon the ,silurian strata4 ,the section shows that the red beds lie upon a worn and denuded surface4 ,now this speaks to the lapse of a long period of time4 ,it may be remembered that we had some grounds for believing that the latest eruptions of the ,cheviot volcanoes were sub-arial4 ,the evidence now enables us to advance further1 and to state that after the close of the volcanic period1 the whole ,cheviot district existed as an elevated tract of dry land1 from which streams flowed north and south4 ,and for so long a time did these conditions endure1 that the rivulets and streams were enabled to scoop out many channels and broad valleys before any of the outlying red beds had come into existence4 ,before the conglomerate beds were laid down1 the ancient volcanic bank of the ,cheviots had thus suffered great erosion4 ,this is what unconformability means4 ,it points to the prolonged continuance of a land-surface1 subject as that must always be to the wearing action of the sub-arial forces4 ,rain and frost disintegrate the rocks1 and running water rolls the dbris from higher to lower levels1 and piles it up in the form of gravel1 sand1 and mud in lakes and the sea4 ,while the old volcanic country of the ,cheviots was being thus denuded1 it would appear that a wide extent of land existed in the ,northern ,highlands and ,southern ,uplands of ,scotland1 and also in what are now the lake districts of ,england and the hilly tracts of ,wales4 ,and in all these regions valleys were formed1 which at a subsequent time were more or less filled up with newer deposits4 ,the presence of the red beds that sweep round the base of the ,cheviot ,hills shows unmistakably that a period of submergence followed these land conditions4 ,all the low grounds of ,southern ,scotland disappeared beneath a wide sheet of water1 which stretched from the foot of the ,lammermuirs up to the base of the ,cheviots1 and here and there entered the valleys1 and so extended into the hills4 ,this water1 however1 does not seem to have been that of an open sea2 rather was it portion of a great freshwater lake1 brackish lagoon1 or inland sea4 ,the lowest beds of the red series are merely hardened layers and masses of gravel and rolled shingle1 which would seem at first sight to indicate the former action of waves along a sea-beach4 ,there are certain appearances1 however1 which lead one to suspect that these ancient shingle beds may have had quite another origin4 ,in some places the stones exactly resemble those which are found so abundantly in glacial deposits4 ,they are sub-angular and blunted1 and1 like glaciated stones1 occasionally show stri or scratches4 ,this1 however1 is very rarely the case4 ,most of the stones appear subsequently to have been rolled about in water1 and in this process they must have lost any ice-markings they may have had1 and become smoothed and rounded like ordinary gravel stones4 ,the same appearances may be noted in the glacier valleys of ,norway and ,switzerland1 where at the present day the glaciated stones which are pushed out at the lower ends of the glaciers are rolled about in the streams1 and soon lose all trace of ice-work4 ,it is impossible1 however1 to enter here into all the details of the evidence which lead one to suspect that glaciers may have existed at this early period among the ,cheviot and ,lammermuir ,hills4 ,in the latter district1 the conglomerates occur in such masses and so exactly resemble the morainic dbris and ice-rubbish of modern glacial regions1 that the late ,sir ,a4 ,c4 ,ramsay long ago suggested their ice-origin4 ,let us conceive1 then1 that when the ancient lake or inland sea of which ,i have spoken reached the base of the ,cheviots1 glaciers may have nestled in the valleys4 ,streams issuing from the lower ends of these would sweep great quantities of gravel down the valleys to the margin of the lake1 and it is quite possible that there might be enough wave-action to spread the gravel out along the shores4 ,it is evident1 however1 that the main heaps of shingle would gather opposite what were at that time the mouths of glacier valleys2 and it is just in such positions that we now meet with the thickest masses of conglomerate4 ,ere long1 however1 the supposed glaciers would seem to have melted away1 and only fine sand and mud1 with here and there small rounded stones and grit1 accumulated round the shores of the ancient lake4 ,of course1 during all this time fine-grained sediment gathered over the deeper parts of the lake-bottom4 ,we have no evidence to show what kind of creatures1 if any1 inhabited the land at this time2 nor do any fossils occur in the red earthy beds to throw light upon the conditions of life that may have obtained in the lake4 ,if glaciers really existed and sent down ice-cold water1 the conditions would hardly be favourable to life of any kind2 for glacial lakes are generally barren4 ,but the absence of fossils may be due to other causes than this4 ,it is a remarkable fact1 that red strata are1 as a rule1 unfossiliferous1 and the few fossils which they do sometimes yield are generally indicative rather of lacustrine and brackish-water1 than marine conditions4 ,the paucity or absence of organic remains seems to have been often due to the presence in the water of a superabundance of salts4 ,now this excessive salinity may have arisen in either of two ways4 ,first1 we may suppose some wide reach of the sea to have been cut off from communication with the open ocean by an elevation of a portion of its bed2 and in this case we should have a lagoon of saltwater1 which evaporation would tend to concentrate to such a degree1 that by-and-by nothing would be able to live in its waters4 ,or1 again1 we may have a lake so poisoned by the influx of springs and streams1 carrying various salts in solution1 as to render it uninhabitable by life of any kind1 either animal or vegetable4 ,many red sandstone deposits1 as ,sir ,a4 ,c4 ,ramsay has pointed out1 are evidently lagoon-formations1 which is proved by the presence of associated beds of rock-salt1 gypsum1 and magnesian limestone4 ,they have slowly accumulated in great inland seas or lakes having no outlet1 whose waters were subject to evaporation and concentration1 although now and then they seem to have communicated more or less freely with the ocean4 ,the red earthy beds of the ,jed1 however1 though unfossiliferous1 yet contain no trace of rock-salt or magnesian limestone4 ,the only character they have in common with the salt-bearing strata of the ,new ,red ,sandstone of ,england is their colour1 due to the presence of peroxide of iron1 which we can hardly conceive could have been deposited in the mud of a sea communicating freely with the ocean4 ,but a quiet lake1 fed by rivulets and streams that drained an old volcanic district1 is precisely the kind of water-basin in which highly ferruginous mud and sand might be expected to accumulate4 ,such a lake1 tainted with the various salts1 etc41 carried into it by streams and springs 7some of which may have been thermal2 for1 as we shall see presently1 the volcanic forces1 although quiescent1 were yet not extinct71 might well be unfitted for either animal or plant1 and probably this is one reason why the red earthy beds of the ,jed are so unfossiliferous4 ,after some time1 the physical conditions in the regions under review experienced some further modification4 ,considerable depression of the land supervened1 and the waters of our inland sea or lake rose high on the slopes of the ,cheviots4 ,mark now how the character of the sediment changes4 ,the prevailing red colour has disappeared1 and white1 yellow1 and pale greenish or grey sand begins to be poured over the bed of the lake4 ,even yet1 however1 ferruginous matter exists in sufficient quantity to tint the sediment red in some places4 ,with the appearance of these lighter-coloured sandy deposits1 the conditions seem to have become better fitted to sustain life4 ,fish of peculiar forms1 which1 like the gar-pike of ,north ,american lakes1 were provided with a strong scaly armour of tough bone1 began to abound1 weeds grew in the water1 and the neighbouring land supported a vegetation now very meagrely represented by the few remains of plants which have been preserved4 ,in some places fish-scales are found in considerable abundance4 ,they belong to several genera and species which are more or less characteristic of the ,old ,red ,sandstone formation4 ,the most remarkable form was the ,pterichthys1 or wing-finned fish4 ,its blunt-shaped head and the anterior portion of its body were sheathed in a solid case of bone1 formed by the union of numerous bony scales or plates4 ,two curious curved spine-like arms occupied the place of pectoral fins1 and may have been used by the creature in paddling along the bottom of the sea or lake in which it lived4 ,the posterior part of the body was covered with bony scales1 but these were not suturally united4 ,other kinds of fish were the ,holoptychius and ,coccosteus1 both of which were1 like the ,pterichthys1 furnished with bony scales4 ,the scales of the former overlapped1 and had a curious wrinkled surface4 ,the head of the ,coccosteus was protected by a large bony shield or buckler1 and a similar bony armour covered the ventral region4 ,the organic remains of these fish-bearing strata are too scanty1 however1 to enable us to form any idea of the kind of climate which characterised the district at this long-past period2 but if we rely upon the fossils which have been met with in strata of the same or approximately the same age elsewhere1 we may be pretty sure the climate was genial1 and nourished on the land an abundant vegetation1 consisting of ferns1 great reeds1 and club-mosses1 which attained the dimensions of large trees1 conifers1 and other strange trees which have no living analogues4 ,it seems most likely that when the land sank down in the ,cheviot district1 so as to allow the old lake to reach as it were a higher level1 some communication with the outlying ocean was effected4 ,red ferruginous mud would then cease to accumulate1 or gather only now and then2 the deposits would for the most part be white or yellow1 or pale green2 and fish would be able to come in from the sea4 ,the communication with the ocean1 however1 was probably never very free1 but liable to frequent interruption4 ,here1 then1 ends the third great period of time represented by the rocks of the ,cheviot district4 ,the first period1 as we have seen1 closed with the deposition of the ,silurian strata4 ,thereafter supervened a vast lapse of time1 not recorded in the ,cheviots by the presence of any rocks1 but represented in other regions by younger members of the ,silurian system4 ,during this unrecorded portion of past time1 the ,silurian strata of the ,cheviots were hardened1 compressed1 folded1 upheaved to the light of day1 and worn into hills and valleys by the action of the sub-arial forces4 ,then began the second period of rock-forming in our district4 ,volcanoes poured out successive beds of molten matter and showers of stones and ashes1 and so built up the rock-masses of the highest parts of the ,cheviot ,hills4 ,these eruptions belong to the ,old ,red ,sandstone age1 and form a portion of what we term the ,lower ,old ,red ,sandstone4 ,after the extinction of the volcanoes1 another prolonged period elapsed1 which is not accounted for in the ,cheviots by the presence of any rocks4 ,then it was1 as we know1 that the great volcanic bank was denuded and worn into a system of hills and valleys4 ,now1 since it is evident that the red beds of the ,jed and other places are also of ,old ,red ,sandstone age1 it follows that they must belong to a higher place in the ,old ,red ,sandstone formation than the much-denuded igneous rocks upon which they rest unconformably4 ,the reasonable conclusion seems to be that the denudation or wearing away of the ,lower ,old ,red ,sandstone igneous rocks of the ,cheviots was effected during that period which is represented in other districts of ,scotland by what is called the ,middle ,old ,red ,sandstone1 so that the ,jed beds will thus rank as ,upper ,old ,red ,sandstone4 ,illustration3 ,fig4 #h4--s1 ,silurian strata2 i1 ,cheviot ,igneous ,rocks 7,lower ,old ,red ,sandstone72 r1 ,upper ,old ,red ,sandstone series2 c1 ,kelso ,igneous ,rocks 7,lower ,carboniferous72 d1 ,lower ,carboniferous ,sandstones1 ,shales1 etc4 ,i come now to speak of certain rocks which1 although they are developed chiefly beyond the limits of our district1 yet require a little consideration before we can complete our account of the geological history of the ,cheviots4 ,the rocks referred to consist chiefly of old lava-beds1 which very closely resemble those of the ,lower ,old ,red ,sandstone4 ,they appear on the south side of the ,tweed valley below ,kelso1 whence they extend south-west and west1 crossing the river at ,makerstoun1 and sweeping north to form the hills about ,smailholm1 ,stichill1 and ,hume 7,fig4 #h74 ,all to the east of these rocks1 the valley of the ,tweed is occupied by a great thickness of grey sandstones1 and grey and blue shales and clays1 with which are associated thin cement-stone bands1 and occasional coarse sandy limestones called cornstone4 ,these strata rest upon the outskirts of the ,kelso igneous rocks1 and are clearly of later date than these1 since in their lower beds1 which are often conglomeratic1 we find numerous rounded fragments of the igneous rocks upon which the sandstones and shales abut4 ,the latter have yielded a number of fossils1 both animals and plants1 to which ,i shall refer presently4 ,in the bed of the ,teviot near ,roxburgh1 and elsewhere1 the ,kelso igneous rocks are found reposing upon whitish and reddish sandstones1 which are evidently the upper members of the red beds of the ,jed ,water and other localities4 ,strata closely resembling the grey sandstones and shales of the ,tweed valley appear among the ,cheviot ,hills at the head of the ,jed ,water1 where they are marked by the presence of thick massive sandstones1 which form all the tops of the hills between ,hungry ,law and the heights that overlook the sources of the ,liddel ,water--the greatest height reached being at ,carter ,fell1 which is #ahae feet above the sea-level4 ,the strata at this place contain some impure limestone and thin seams of coal1 while beds of lava and tuff appear intercalated in the series4 ,illustration3 ,fig4 #i4--,section across old volcanic neck4 ,the dotted line above suggests the original form of the volcano2 b1 plug of igneous rock which rose in a molten state and cooled in the vent4 ,now let us rapidly sum up what seem to be the inferences suggested by these briefly-stated facts4 ,we have seen that the ,upper ,old ,red ,sandstone began to be deposited in a lake which1 as time wore on1 probably communicated with the sea1 while the land was undergoing a process of depression1 so that the area of deposition was thus widely increased1 and sediment gradually accumulated in places and at levels which had existed as land when the ancient lake first appeared in the ,cheviot district4 ,the old lava-beds of ,kelso show that the volcanic forces1 which had long been quiescent1 again became active4 ,great floods of molten matter issued from the bowels of the earth1 and poured over the bottom of the inland sea4 ,but all the larger volcanoes of this period were confined to the centre of the ,tweed valley4 ,not a few little isolated volcanoes1 however1 seem to have dotted the sea-bottom beyond the limits of the ,kelso area4 ,from these1 showers of stones were ejected1 and sometimes also they poured out molten matter4 ,their sites are now represented by rounded hills which stand up1 more or less abruptly1 above the level of the undulating tracts in which they occur 7,fig4 #i74 ,among the most marked are ,rubers ,law1 ,black ,law1 the ,dunian1 and ,lanton ,hill4 ,of course it is only the plugged-up vents or necks that now remain2 all the loose ejectamenta by which these must at one time have been surrounded have long since been worn and washed away4 ,at last the ,kelso volcanoes became extinct1 and the little ones also probably died out at the same time4 ,another long period now ensued1 during which the inland sea disappeared1 and its dried-up bed was subjected to the denuding action of the sub-arial forces4 ,the volcanic rocks of the ,kelso district suffered considerable erosion1 while the softer sandy strata amongst which they were erupted no doubt experienced still greater waste4 ,ere long1 however1 the scene again changes2 and what is now the vale of ,tweed becomes a wide estuary1 the shores of which are formed at first by the ,kelso igneous rocks4 ,into this estuary1 rivers and streams carry the spoil of the ,southern ,uplands1 and strew its bed with sand and mud4 ,occasionally ferns and large coniferous trees are floated down1 and1 getting water-logged1 sink to the bottom1 where they become entombed in the slowly accumulating sediment4 ,the character of these buried plants shows that the climate must have been genial4 ,they belong to species which are characteristic of the ,carboniferous system1 and we look upon them with interest as the forerunners of that vast plant-growth which by-and-by was to cover wide areas in ,britain1 and to give rise to our coal-seams1 the source of so much national wealth4 ,in the waters of the estuary1 minute crustaceous creatures called cyprides abounded1 and with these was associated a number of small molluscs1 chiefly univalves4 ,here and there considerable quantities of calcareous mud and sand gathered on the bed of the estuary1 and formed in time beds of cement-stone1 and impure limestone or cornstone4 ,how long that condition of things obtained in the ,tweed valley we cannot tell2 but we know that after a very considerable thickness of sediment had accumulated1 estuarine conditions prevailed over the south-west end of what is now the ,cheviot range4 ,this points to a considerable depression of the land4 ,in this same region volcanic action appeared1 and streams of lava and showers of fragmental materials were ejected--the remains of which are seen in ,hungry ,law1 ,catcleugh ,shin1 and the head-waters of the ,jed4 ,genial climatic conditions continued2 and here and there1 along what were either low islets or the flat muddy shores of the estuary1 plants grew in sufficient quantity to form masses of vegetation which1 subsequently buried under mud and sand1 were compressed and mineralised1 and so became coal4 ,the only place where these are now met with is on the crest of the ,cheviots at ,carter ,fell4 ,the process of depression still continuing1 thick sand gradually spread over the site of the submerged forests4 ,to trace the physical history immediately after this1 we must go out of the ,cheviot district2 and it may suffice if ,i merely state that these estuarine or lacustrine conditions1 which prevailed for a long time not only over the ,tweed and ,cheviot areas but in various other parts of ,scotland1 at last gave place to the sea4 ,in this sea1 corals1 sea-lilies1 and numerous molluscs and fishes abounded--all pointing to the prevalence of genial climatic conditions4 ,the organic remains and the geological position of the estuarine beds of the ,tweed and the ,cheviots--resting as they do upon the ,upper ,old ,red ,sandstone--prove them to belong to the ,lower series of the great ,carboniferous system4 ,it was some time during the ,carboniferous period that wide sheets of melted matter were forcibly intruded among the ,old ,red ,sandstone and the ,lower ,carboniferous strata of the ,cheviot district2 but although these are now visible at the surface1 as at ,southdean1 ,bonchester1 etc41 they never actually reached that surface at the time of their irruption4 ,they cooled in the crust of the earth amongst the strata between which they were intruded1 and have only been exposed to view by the action of the denuding forces which have worn away the sedimentary beds by which they were formerly covered4 ,a very wide blank next occurs in the geological history of the ,cheviots4 ,we have no trace of the many great systems1 comprising vast series of strata and representing long eras of time1 which we know1 from the evidence supplied by other regions1 followed after the deposition of the ,lower ,carboniferous strata4 ,the ,middle and ,upper ,carboniferous groups are totally wanting1 so likewise is the ,permian system2 and all the great series of ,secondary systems1 of which the major portion of ,england is composed1 are equally absent4 ,nay1 even ,tertiary accumulations are wanting4 ,there is one very remarkable relic1 however1 of ,tertiary times1 and that is a long dyke or vertical wall of basalt-rock which traverses the country from east to west1 crossing the crest of the ,cheviots near ,brownhart ,law1 and striking west by north through ,belling ,hill1 by the ,rule ,water at ,hallrule ,mill1 on towards ,hawick4 ,this is one of a series of such dykes1 common enough in some parts of ,scotland1 which become more numerous as we approach the west coast1 where they are found associated with certain volcanic rocks of ,tertiary age1 in such a way as to lead to the belief that they all belong to the same period4 ,the melted rock seems to have risen and cooled in great cracks or fissures1 and seldom to have overflowed at the surface4 ,indeed it is highly probable that many or even most of the dykes never reached the surface at all1 but have been exposed by subsequent denudation of the rocks that once overlaid them4 ,such would appear to have been the case with the great dyke of the ,cheviot district4 ,we can only conjecture what the condition of this part of southern ,scotland was in the long ages that elapsed between the termination of the ,lower ,carboniferous period and the close of the ,tertiary ages4 ,it is more than likely that it shared in some of the submergences that ensued during the deposition of the upper group of the ,carboniferous system2 but after that it may have remained1 for aught we can tell1 in the condition of dry land all through those prolonged periods which are unrecorded in the rocks of the ,cheviot ,hills1 but have left behind them such noteworthy remains in ,england and other countries4 ,of one thing we may be sure1 that during a large part of those unrecorded ages the ,cheviot district could not have been an area of deposition4 ,rather must it have existed for untold eras as dry land2 and this explains and accounts for the enormous denudation which the whole country has experienced2 for there can be little doubt that the ,lower ,carboniferous strata of ,carter ,fell were at one time continuous with the similar strata of the lower reaches of the ,tweed valley4 ,yet hardly a trace of the missing beds remains in any part of the country between the ridge of the hills at the head of the ,jed ,water and the ,tweed at ,kelso4 ,only little patches are found capping the high ground opposite ,jedburgh1 as at ,hunthill1 etc4 ,thus more than a thousand feet of ,lower ,carboniferous strata1 and probably not less than five hundred or six hundred feet of ,old ,red ,sandstone rocks1 have been slowly carried away1 grain by grain1 from the face of the ,cheviot district since the close of the ,lower ,carboniferous period4 ,,iv4 ,in the first of these papers some reference was made to the configuration of the ground in the ,cheviot district4 ,we have seen that the outlines assumed by the country have been determined in large measure by the nature of the rocks4 ,thus where igneous masses abound1 the hills present a more or less irregular1 and broken or lumpy contour1 while the valleys are frequently narrow and deep4 ,in the tracts occupied by ,silurian strata1 we have1 as a rule1 broad-topped hill-masses with a smoothly-rounded outline1 whose slopes generally fall away with a long gentle sweep into soft green valleys1 along the bottoms of which the streams often flow in deep gullies and ravines4 ,where the country is formed of sandstones1 and other associated strata1 the hills are generally broad and well-rounded1 but the outline is not infrequently interrupted by lines of cliff and escarpment4 ,these strata1 however1 are confined chiefly to the low-grounds1 where they form a gently-undulating country1 broken here and there1 as in ,dunian ,hill1 ,bonchester ,hill1 ,rubers ,law1 etc41 by abrupt cones and knobs of igneous rock4 ,it is evident1 then1 that the diversified character of the ,cheviot ,hills and the adjoining low-grounds depends on the character of the rocks and also1 as we shall see presently1 upon geological structure4 ,each kind of rock has its own peculiar mode of weathering4 ,all do not crumble away under the action of rain1 frost1 and running water in precisely the same manner4 ,some which yield equally and uniformly give rise to smooth outlines1 others of more irregular composition1 such as many igneous rocks1 break up and crumble unequally in a capricious and eccentric way1 and these in the course of time present a hummocky1 lumpy1 and rough irregular configuration4 ,and as soft and readily-weathered rocks must wear away more rapidly than indurated and durable masses1 it follows that the former will now be found most abundantly at low levels1 while the latter will enter most extensively into the composition of the hills4 ,but the contour of a country depends not only upon the relative durability of the rocks1 but also upon the mode of their occurrence in the crust of the earth4 ,strata1 as we have seen1 do not all lie in one way2 some are horizontal1 others are inclined to the horizon1 while yet others are vertical4 ,again1 many rocks are amorphous2 that is to say1 they occur in somewhat thick masses which show no trace of a bedded arrangement4 ,such differences of structure and arrangement influence in no small degree the weathering and denudation of rocks1 and cannot be left out of account when we are seeking to discover the origin of the present configuration of our hills and valleys4 ,thus1 escarpments and the terraced aspect of many hill-slopes are due to inequalities in the strata of which such hills are built up4 ,the softer strata crumble away more rapidly under the touch of the atmospheric forces than the harder beds which rest upon them1 and hence the latter are undermined1 and their exposed ends or crops1 losing support1 fall away and roll down the slopes4 ,the igneous rocks of the ,cheviots are arranged in beds2 but so massive are these1 that frequently a hill proves to be composed from base to summit of one and the same sheet of old lava4 ,hence there is a general absence of that terraced aspect which is so conspicuous in hills that are built up of bedded rock-masses4 ,here and there1 however1 the beds are not so massive1 several cropping out upon a hill-side2 and whenever this is the case 7as near ,yetholm7 we find the hill-slopes presenting the usual terraced appearance--a series of cliffs and escarpments1 separated by intervening slopes1 rising one above the other4 ,in the ,silurian districts no such terraces or escarpments exist1 the general high dip of the strata1 which often approaches the vertical1 precluding any such contour4 ,in a region composed of highly-inclined greywack and shale1 however1 we should expect to find that where the strata are of unequal durability1 the harder beds will stand up in long narrow ridges1 separated by intervening hollows1 which have been worn out along the outcrops of the softer and more easily-denuded beds4 ,and such appearances do show themselves in some parts of the ,silurian area4 ,as a rule1 however1 the ,silurian strata are not thick-bedded1 and harder and softer bands alternate so rapidly that they yield on the whole a smooth surface under the action of the atmospheric forces4 ,in the low-lying districts1 which1 as ,i have said1 are mostly occupied by sandstones and shaly beds1 all the abrupt isolated hills are formed of igneous rocks1 which are much harder and tougher than the strata that surround them4 ,it is quite evident that these hills owe their present appearance to the durable nature of their constituent rocks1 which now project above the general level of the surface1 simply because they have been better able to resist the denuding agents than the softer rocks that once covered and concealed them4 ,we see1 then1 that each kind of rock has its own particular mode of weathering1 and that the configuration of a country depends primarily upon this and upon geological structure4 ,indeed1 so close is the connection between the geology and the surface-outline of a country1 that to a practised observer the latter acts as an unfailing index to the general nature of the underlying rocks1 and tells him at a glance whether these are igneous like basalt and porphyrite1 aqueous like sandstone and shale1 or hardened and altered strata like greywack4 ,but while one cannot help noticing how in the ,cheviot district the character of the scenery depends largely upon the nature and structure of the rocks1 he shall1 nevertheless1 hardly fail to observe that flowing outlines are more or less conspicuous over all the region4 ,and as he descends into the main valleys1 he shall be struck with the fact that the hill-slopes seem to be smoothed off in a direction that coincides with the trend of these valleys4 ,in short1 he cannot help noticing that the varied configuration that results from the weathering of different rock-masses has been subsequently modified by some agent which seems to have acted universally over the whole country4 ,in the upper reaches of the ,cheviot valleys1 the rocks have evidently been rounded off by some force pressing upon them in a direction coinciding with that of the valleys2 but soon after entering upon their lower reaches1 we notice that the denuding or moulding force must have turned gradually away to the north-east--the northern spurs of the ,cheviots1 and the low-grounds that abut upon these being smoothed off in a direction that corresponds exactly with the trend of that great strath through which flow the ,teviot and the ,tweed1 from ,melrose downwards4 ,throughout this broad strath1 which extends from the base of the ,lammermuirs to the foot of the ,cheviots1 and includes the whole of ,teviotdale1 the ground presents a remarkable closely-wrinkled surface1 the ridges and intervening hollows all coinciding in direction with the general trend of the great strath1 which is south-west and north-east2 but turning gradually round to east1 as we approach the lower reaches of the ,tweed4 ,passing round the north-eastern extremity of the ,cheviot range into ,northumberland1 we observe that the same series of ridges and hollows continues to follow an easterly direction until we near the sea-board1 when the trend gradually swings round to the south-east1 as in the neighbourhood of ,belford and ,bamborough1 where the ridges run parallel with the coast-line4 ,the ridges and hollows are most conspicuous in the low-grounds of ,roxburghshire and ,berwickshire1 especially in the regions between ,kelso and ,smailholm1 and between ,duns and ,coldstream4 ,the dwellers along the banks of the ,tweed are quite familiar with the fact that the roads which run parallel with the river are smooth and level1 for they coincide with the trend of the ridges and hollows2 whilst those that cross the country at right angles to this direction must of course traverse ridge after ridge1 and are therefore exceedingly uneven4 ,in this low-lying district most of the ridges are composed of superficial deposits of stony and gravelly clay and sand1 and the same is the case with those that sweep round the north-eastern spurs of the ,cheviots by ,coldstream and ,ancroft4 ,some ridges1 however1 consist either of solid rock alone1 as near ,stichill1 or of rock and overlying masses of clay and stones4 ,in the hilly regions1 again1 nearly all the ridges are of rock alone1 especially in the districts lying between ,melrose and ,selkirk and between ,selkirk and ,hawick4 ,indeed1 the hills drained by the upper reaches of the ,teviot and its tributaries are more or less fluted and channelled1 as it were--many long parallel narrow hollows having been driven out along their slopes and even frequently across their broad tops4 ,this scolloped and ridged aspect of the hills1 however1 disappears as we approach the upper reaches of the hill-valleys4 ,from ,skelfhill ,pen 7#agde feet7 by ,windburgh ,hill 7#affb feet71 on through the ridge of the ,cheviot watershed1 none of the hills shows any appearance of a uniformly-wrinkled surface4 ,illustration3 ,fig4 #aj4--,rounded ,rocks1 with superficial deposits1 t t t1 heaped up against steep faces4 ,the arrows indicate direction followed by the smoothing agent4 ,a close inspection of the rock-ridges satisfies one that they have been smoothed off by some agent pressing upon them in a direction that coincides with their own trend2 and not only so1 but the smoothing agent1 it is clearly seen1 must have come from the watersheds and then pressed outwards to the low-grounds which are now watered by the ,teviot and the ,tweed4 ,this is shown by the manner in which the rocks have been smoothed off1 for their smooth faces look towards the dominant watersheds1 while their rough and unpolished sides point away in the opposite direction4 ,sometimes1 however1 we find that more or less steeply projecting rocks face the dominant watersheds4 ,when such is the case1 there is usually a long sloping tail behind the crag--a tail which is composed chiefly of superficial deposits4 ,the hills between ,hume and ,stichill afford some good examples4 ,the two kinds of appearances are exhibited in the accompanying diagram 7,figs4 #aj1 #aa47 ,the appearance shown in ,fig4 #aj is of most common occurrence in the upland parts of the country1 while crag and tail 7as shown in ,fig4 #aa7 is seen to greatest advantage in the open low-grounds4 ,in both cases it will be observed that superficial deposits 7t7 nestle behind a more or less steep face of rock4 ,illustration3 ,fig4 #aa4--;,crag and ,tail2 boss of hard rock1 c2 intersecting sandstones1 s2 superficial deposits heaped up in rear of crag1 t4 ,the arrow indicates direction followed by smoothing agent4 ,when the rocks have not been much exposed to the action of the weather1 they often show a polished surface covered with long parallel grooves and stri or scratches4 ,such polished and scratched surfaces are best seen when the superficial deposits have been only recently removed4 ,often1 too1 when we tear away the thick turf that mantles the hill-slopes1 we find the same phenomena4 ,indeed1 wherever the rocks have not been much acted upon by the weather1 and thus broken up and decomposed1 we may expect to meet with more or less well-marked grooves and stride4 ,now the remarkable circumstance about these scratches is this--they agree in direction with the trend of the rock-ridges and the hollows described above4 ,nor can we doubt that the superficial markings have all been produced by one and the same agent4 ,in the upper valleys of the ,cheviots1 the scratches coincide in direction with the valleys1 which is1 speaking generally1 from south to north1 but as we approach the low-grounds they begin to turn more to the east 7just1 as we have seen1 is the case with the ridges and hollows71 until we enter ,england to the east of ,coldstream1 where the stri point first nearly due east1 but eventually swing round to the south-east1 as is well seen upon the limestone rocks between ,lowick and ,belford4 ,in ,teviotdale the general trend of the stri is from south-west to north-east1 a direction which continues to hold good until the lower reaches of the ,tweed are approached1 when1 as we have just mentioned1 they begin to turn more and more to the east4 ,thus it becomes evident that the denuding agent1 whatever it was1 that gave rise to these ridges and scratched rock-surfaces must have pressed outwards from all the dominant watersheds1 and1 sweeping down through the great undulating strath that lies between the ,cheviots and the ,lammermuirs1 must have gradually turned away to the east and south as it rounded the northern spurs of the former range1 so as to pass south-east over the contiguous maritime districts of ,northumberland4 ,a few words now as to the character of the superficial deposits which enter so largely into the composition of the long parallel banks and ridges in the low-grounds of ,roxburghshire1 ,berwickshire1 and the northern part of ,northumberland4 ,the most conspicuous and noteworthy deposit is a hard tough tenacious clay1 which is always more or less well-charged with blunted and sub-angular stones and boulders1 scattered pell-mell through the mass4 ,this clay is as a rule quite unstratified--it shows no lines of bedding1 and although here and there it contains irregular patches and beds of gravel and sand1 yet it evidently does not owe its origin to the action of water4 ,its colour in the upper part of ,teviotdale and the ,cheviots is generally a drab-brown1 or pale grey and sometimes yellow1 while here and there1 as in the upper reaches of the ,jed valley1 it is a dark dingy bluish grey4 ,in the lower parts of ,teviotdale and in the ,tweed district it is generally red or reddish brown4 ,the stones in the clay have all been derived from the rocks of the region in which it occurs4 ,thus in ,teviotdale we find that in the higher reaches of the dale which are ,silurian the stones and boulders consist of various kinds of greywack1 etc4 ,in the lower reaches1 however1 when we pass into the ,red ,sandstone area1 we note that the clay begins to contain fragments of red sandstone1 while the clay itself takes on a reddish tinge1 until we get down to the vale of the ,tweed1 where not only is the clay very decidedly red1 but its sandstone boulders also are very numerous4 ,the same appearances present themselves in passing outwards from the ,cheviots4 ,at first the clay contains only stones that have been derived from the upper parts of the hills1 but by-and-by1 as we near the low-grounds1 other kinds begin to make their appearance1 so that by the time we reach the ,tweed we may obtain from the clay specimens of every kind of rock that occurs within the drainage-area of the ,teviot and the lower reaches of the ,river ,tweed4 ,look at the stones1 and you shall observe that all the harder and finer-grained specimens are well-smoothed and covered with stri or scratches1 the best marked of which run parallel with the longer axis of each stone and boulder4 ,these scratches are evidently very similar to those markings that cover the surface of the underlying solid rock1 and we may feel sure1 therefore1 that the denuding agent which smoothed and scratched the solid rocks had also something to do with the stones and boulders of the clay4 ,underneath the stony clay1 or ,till1 as it is called1 we find here and there certain old river gravels4 ,we know that these gravels are river-formations1 because not only do they lie at the bottom of the river-valleys1 but the stones1 we can see1 have been arranged by water running in one constant direction1 and that direction is always down the valley in which the gravels chance to occur4 ,frequently1 however1 there is no trace of such underlying gravels1 but the till rests directly upon the solid rocks4 ,now what do all these appearances mean8 ,it is clear that there is no natural agent in this country engaged in rounding and scratching the rocks1 or in accumulating a stony clay like till4 ,in alpine regions1 however1 we know that glaciers1 as they slowly creep down their valleys1 grind and polish and scratch the rocks over which they pass1 and that underneath the moving ice one may detect smoothed and striated stones precisely resembling those that occur in till4 ,frost in such alpine regions splits up the rocks of the cliffs and mountain-slopes that overlook a glacier1 and immense masses of angular stones and dbris1 thus loosened1 roll down and accumulate along the flanks of the ice-streams4 ,eventually such accumulations are borne slowly down the valley upon the back of the glacier1 and are dropped at last over the terminal front of the ice1 where they become intermingled with the stones and rubbish1 which are pushed or washed out from underneath the ice4 ,these heaps and masses of angular dbris and stones are called moraines1 and one can see that in ,switzerland the glaciers must at some time have been much larger1 for ancient moraines occur far down in the low-grounds of that country--the glaciers being now confined to the uppermost reaches of the deep mountain-valleys4 ,moreover1 we may note how the mountain-slopes overlooking the present puny glaciers have been rubbed by ice up to a height of sometimes a thousand feet and more above the level of the existing ice-streams4 ,now since the aspect presented by the glaciated rock-surfaces of ,switzerland is exactly paralleled by the rounded and smoothed rocks of ,scotland1 there can be no doubt that the latter have had a similar origin4 ,again1 we find throughout the low-grounds of ,switzerland a deposit of till precisely resembling that which is so well developed in ,teviotdale and the valley of the ,tweed4 ,and as there can be no doubt that the ,swiss till has been produced by the action of glacier ice1 we are compelled to believe the same of the till in ,scotland4 ,let us further note that in the deep mountain-valleys of ,switzerland the glacial deposits consist for the most part of coarse morainic dbris--of such materials1 in short1 as the terminal moraines of existing glaciers are mainly composed4 ,not infrequently this morainic dbris has been more or less acted upon by the rivers that escape from the glaciers1 and the angular stones have been rounded and arranged in bedded masses4 ,it is only when we get out of the mountain-valleys and approach the low-grounds that the till1 or stony clay1 begins to appear abundantly4 ,the same phenomena characterise the ,cheviot district4 ,in the upper reaches of the mountain-valleys at the heads of the ,teviot1 the ,kale1 the ,bowmont1 etc41 either till does not occur or it is thin and often concealed below masses of rude morainic dbris and gravel4 ,out in the low-grounds1 however1 till1 as we have already remarked1 is the most conspicuous of all the superficial deposits4 ,from these facts it may be inferred that till indicates the former presence of great confluent glaciers1 while morainic dbris in hill-valleys points to the action of comparatively small local and isolated glaciers4 ,what1 then1 are the general conclusions which may be derived from a study of the rock-ridges1 flutings1 and stri1 and the till of the ,cheviot district8 ,clearly this3 that the whole country has at one time been deeply buried under glacier ice4 ,the evidence shows us that the broad strath stretching between the ,lammermuirs and the ,cheviots must have been filled to overflowing with a great mass of ice that descended from the uplands of ,peebles and ,selkirk and the broad-topped heights that overlook the sources of the ,teviot4 ,the ,cheviots appear to have been quite buried underneath this wide sea of ice1 and so likewise were the ,lammermuirs4 ,at the same time1 as we know1 all ,scotland was similarly enveloped in a vast sheet of snow and ice1 which streamed out from the main watersheds of the country1 and followed the lines of the chief straths--that is to say1 the general slope of the ground4 ,the track of the ice in the ,cheviot district is very distinctly marked4 ,in ,teviotdale it followed the trend of the valley1 and1 grinding along the outcrop of the ,silurian strata1 deepened old hollows and scooped out new ones in the soft shaly beds1 while the intervening harder strata1 which offered greater resistance to the denuding action of the ice1 did not wear so easily1 and so were rounded off1 and formed a series of ridges running parallel to the eroded hollows4 ,the stones and rubbish1 dragged along underneath the ice1 necessarily increased as the glacier mass crept on its way4 ,the rocks were scratched and grooved by the stones that were forced over them1 and the polishing was completed by the finer sand and clay which resulted from the grinding process4 ,wherever a rock projected there would be a tendency for the stones and clay and sand to gather behind it4 ,one may notice the same kind of action upon the bed of a stream1 where the sediment tends to collect in the rear of prominent stones and boulders4 ,and we can hardly fail to have observed further that the sediment of a river often arranges itself under the action of the current in long banks1 which run parallel to the course of the water4 ,underneath the ice-sheet the stones1 sand1 and clay behaved in the same way4 ,behind projecting rocks in sheltered nooks and hollows1 they accumulated1 while in places exposed to the full sweep of the ice-stream they were piled up and drawn out into long parallel banks and ridges1 the trend of which coincided with that of the ice-flow4 ,the presence of confused and irregular patches and lenticular beds of sand1 clay1 and gravel in the till is not difficult to understand when we know that there is always more or less water flowing on underneath a glacier4 ,such streams must assort the dbris1 and roll angular fragments into rounded stones and pebbles2 but the materials thus assorted in layers will ever and anon be crushed up so as to be either partially or wholly obliterated by the slowly moving glacier4 ,as the stones and clay were derived from the underlying rocks1 it is no wonder that the colour of the till should vary4 ,in the ,silurian tracts it is pale yellowish1 or bluish grey1 and the stones consist chiefly of fragments of ,silurian rocks1 all blunted and smoothed1 and often beautifully polished and striated4 ,when we get into the ,red ,sandstone region of the low-grounds the colour of the clay begins by-and-by to change1 and fragments of red sandstone become commingled with the ,silurian stones1 until ere long the colour of the deposit is decidedly red1 and sandstone fragments abound4 ,everywhere the stones show that they have been carried persistently in one direction1 and that is out from the watershed1 and down the main valleys4 ,the direction of the ice-marks upon the solid rocks1 and the trend of the drums1 as the parallel ridges of till are termed1 show that the ice-sheet of ,teviotdale and ,tweed gradually turned away to the east and south-east as it swept round the north-eastern spurs of the ,cheviots4 ,now we may well ask why the ice did not go right out into the ,north ,sea1 which is apparently the course it ought to have followed4 ,the same curious deflection affected the great ice-stream that occupied the basin of the ,forth4 ,when it got past ,north ,berwick1 that stream1 instead of flowing directly east into the ,north ,sea1 turned away to the south-east and overflowed the northern spurs of the ,lammermuirs1 bringing with it into the valley of the ,tweed stones and boulders which had travelled all the way from the ,highlands4 ,it is obvious there must have been some impediment to the flow of the ,scottish ice into the basin of the ,north ,sea4 ,what could have blocked its passage in that direction8 ,at the very time that ,scotland lay concealed beneath its ice-sheet1 ,norway and ,sweden were likewise smothered in ice which attained a thickness of not less than five or six thousand feet4 ,the whole basin of the ,baltic was occupied by a vast glacier which flowed south into ,northern ,germany1 and this sheet was continuous with glacier-ice that crossed over ,denmark4 ,when we consider how shallow the ,north ,sea is 7it does not average more than forty fathoms between ,scotland and the ,continent71 we cannot doubt that the immense masses of ice descending from ,norway could not possibly have floated off1 but must actually have crept across the bottom of that sea until they abutted upon and coalesced with the ,scottish ice1 so as to form one vast mer de glace4 ,thus it was that the ,scandinavian ice blocked up the path of the ,scottish glaciers into the basin of the ,north ,sea1 and compelled them to flow south-east into ,england4,h ,had there been no such obstruction to the passage of the ,scottish glaciers1 it is impossible to believe that snow and ice could ever have accumulated to such a depth in ,scotland4 ,the ,scottish ice reached a thickness of some three thousand feet in its deeper parts4 ,it is evident1 however1 that had there been a free course for the glaciers1 they would have moved off before they could have attained this thickness4 ,and we can hardly doubt1 therefore1 that it was the damming-up of their outlet by the great ,scandinavian ice-sheet that enabled them to deepen to such an extent in the valleys and low-grounds of ,scotland4 ,h ,in the extreme north of ,scotland we find that the ,scottish ice was1 in like manner1 compelled to turn aside and overflow ,caithness from south-east to north-west4 ,when the ice-sheet was at its thickest1 the ,cheviots were completely covered1 nevertheless they served to divide the ice-flow between ,scotland and ,england1 although here and there one finds that the ice passed over some of the lower summits1 carrying with it boulders and stones4 ,this is by no means an uncommon circumstance in ,scotland and other glaciated countries4 ,thus we note that ,highland boulders have been brought into the vale of the ,tweed across the ,lammermuirs2 and in the same way boulders from the heights overlooking ,eskdale have been carried over some of the lower hill-tops into the vale of the ,teviot4 ,in like manner the ,swedish ice occasionally overflowed the lower mountain-tops of the dividing ridge or watershed into ,norway4 ,what wonder now that the ,cheviot area should exhibit so many flowing outlines1 that the hills should be so smoothed and rounded and fluted1 that the low-grounds should be cumbered with such heaps of clay and striated stones8 ,long before the great glaciers appeared1 the rocks were weathered and worn by the action of the usual atmospheric forces1 and each had assumed its own peculiar outline2 but how greatly has this been modified by the grinding action of the ice-sheet6 ,to what an extent have projecting rocks been rubbed1 and how great is the destruction that has befallen the loose accumulations of river gravel1 sand1 and clay that gathered in the valleys before the advent of the ,ice ,age6 ,all that now remains of these are a few patches preserved here and their underneath the till4 ,the ,cheviots can tell us nothing of the kinds of plants and animals that clothed and peopled the country in pre-glacial times4 ,all we learn is that streams and rivers flowed as they flow now1 and that by-and-by everything was changed1 and the land disappeared underneath a vast covering of snow and ice4 ,in my concluding paper ,i will show how this ice period passed away1 and how the present condition of things succeeded4 ,v4 ,i have described the condition of the ,cheviot district during the climax of the ,ice ,age as one of intense arctic cold1 the whole ridge of hills being then completely smothered in snow and ice4 ,this excessive climate1 however1 did not last continuously throughout the so-called glacial period1 but was interrupted by more than one mild interglacial epoch4 ,we have evidence in ,scotland1 as in other countries1 to show that the great confluent ice-masses melted away so as to uncover all the low-grounds and permit the reappearance of plants and animals4 ,rivers again watered the land1 and numerous lakes diversified the face of the country4 ,willows1 hazels1 and alders grew in the sheltered valleys1 oak-trees flourished in the low-grounds1 and ,scots firs clustered upon the hill-slopes4 ,a strong1 grassy vegetation covered wide areas1 and sedges and rushes luxuriated in marshy places and encroached upon the margins of the lakes4 ,the mammoth1 or woolly-coated elephant1 roamed over the land1 and among its congeners were the extinct ox1 the horse1 the ,irish elk1 and the reindeer4 ,after such a temperate condition of things had continued for some time--perhaps for thousands of years--the land1 during the last interglacial epoch1 became gradually submerged to a depth of several hundred feet1 and a cold1 ungenial sea1 in which flourished species of northern and arctic shells1 covered the low-grounds of ,scotland4 ,the cold continuing to increase1 our glaciers descended for the last time from the mountains and encroached upon the bed of the sea1 until they became confluent1 fairly usurping the floor of the ,german ,ocean1 and pushing back the western seas as far as1 and even beyond1 the islands of the ,outer ,hebrides4 ,there is good reason to believe that such great changes of climate occurred several times during the glacial period1 which thus seems to have consisted of an alternation of cold and genial epochs4 ,but as the last phase in this extraordinary series of changes was a cold one1 during which great glaciers scoured the face of the country1 we now obtain only a few scattered traces of the genial conditions that characterised the preceding mild interglacial epochs4 ,vegetable accumulations1 lake and river deposits with mammalian remains1 marine beds and their shelly contents1 were all ploughed up by the ice1 and to a very large extent demolished4 ,here and there1 however1 we find in the till or boulder-clay that marks the last cold epoch1 wasted fragments of trees1 tusks of mammoths1 and broken sea-shells2 while underneath the till we occasionally come upon old lake deposits with vegetable and mammalian remains1 or1 as the case may be1 beds of marine origin well stocked with sea-shells of arctic species4 ,and these freshwater and marine beds repose1 in many cases1 upon an older accumulation of till1 which belongs to an earlier cold epoch of the glacial period4 ,in the ,cheviot district proper1 the traces of mild1 interglacial conditions are very slight1 but in the immediate neighbourhood we find them more strongly marked4 ,thus1 in the valley of the ,slitrig1 near ,hawick1 we notice freshwater beds with peaty matter lying between a lower and an upper till or boulder-clay2 and interglacial freshwater beds also appear in the neighbouring county of ,peebles1 particularly in the valley of the ,leithan ,water4 ,again1 in the valley of the ,tweed near ,carham1 there occur interglacial beds in which ,i detected numerous bones of water-rats and frogs4 ,these interglacial remains acquire a peculiar interest when we come to view the superficial deposits of ,scotland in connection with those of ,england and the ,continent2 for1 as ,i have endeavoured to show elsewhere1,i it is most likely that the ancient gravels of ,england1 which contain the earliest traces of man1 belong for the most part to interglacial times2 and the extraordinary changes of climate described above may therefore have been actually witnessed by human eyes4 ,indeed1 ,i believe it was the advent of the last cold epoch of the ,ice ,age that drove out the old tribes who used the rude flint implements that are now found in the gravel deposits and caves of ,england1 and who occupied the ,british area along with hippopotami1 rhinoceroses1 elephants1 lions1 hynas1 and other animals4 ,the men who entered ,britain after the final disappearance of arctic conditions1 were more advanced in civilisation1 and were accompanied by a very different assemblage of animals--by a group represented by oxen1 sheep1 dogs1 and other creatures1 most of which are still indigenous to ,britain4 ,i ,great ,ice ,age4 ,but to return to the ,cheviots4 ,when the final cold epoch had reached its climax1 and the ice-sheet began to melt away for the last time1 the tops of the hills then once more became uncovered1 and large blocks1 detached by the action of the frost1 fell upon the surface of the glaciers1 and were borne down the valleys1 some of them to become stranded here and there on hill-slopes1 others to be carried far away from the ,cheviot area and dropped at last over ,northumberland and ,durham1 or even further south4 ,as the melting of the ice continued1 and the glacier of the ,tweed ceased to reach the sea1 great accumulations of gravel and sand were formed4 ,underneath the ice1 sub-glacial streams ploughed out the till1 and paved their hidden courses with gravel and sand4 ,in summer-time1 the whole surface of the ,tweed glacier was abundantly washed with water1 which1 pouring down by clefts and holes in the ice1 swelled all the sub-glacial streams and rivers4 ,at the same time1 floods descending from the ,lammermuirs and the ,cheviots1 pushed with them vast quantities of shingle1 gravel1 and sand1 part of which was swept upon the surface of the ,tweed glacier1 while much seems to have gathered along its flanks1 forming banks and ridges running parallel with the course of the valley4 ,at last the time came when the ice had fairly vanished from the lower reaches of the ,tweed1 and we now walk over its bed and mark the long ridges and banks of shingle and gravel that were formed by the sub-glacial streams and rivers1 and the somewhat similar accumulations that gathered along the sides of the glacier at the foot of the ,lammermuir ,hills4 ,here and there1 also1 we note the heaps 7i4e4 moraines7 of shingle1 earth1 clay1 and dbris1 with large erratics which travelled on the surface of the ice1 and were dropped upon the ground as that ice melted away4 ,all the loose erratics that lie at the surface in the lower reaches of the ,tweed valley have come from the west4 ,some of them rest upon hard rock1 others upon till1 and yet others crown the tops and slopes of gravel and sand hillocks1 or appear in low mounds of morainic origin4 ,in the valleys of the ,cheviot ,hills one traces the footsteps of the retiring glaciers in mounds and hummocks of rude earthy dbris1 blocks1 and rock-rubbish4 ,these are terminal moraines1 and they indicate certain pauses in the recession of the ice4 ,the most remarkable examples occur in the valley of the ,kale ,water at ,blinkbonny1 a mile or so above the village of ,eckford4 ,at that place a bank of morainic matter at one time blocked up the valley of the ,kale1 and thus formed a wide and extensive lake that stretched up to and beyond ,morebattle4 ,numerous curious hillocks of gravel and sand are banked against the moraine1 and point to the action of the flood-waters that escaped from the melting glacier4 ,other gravelly moraine mounds occur higher up the same valley1 as near ,grubbit ,mill4 ,these last tell us of a time when the ,kale glacier had retreated still further1 so as to have its terminal front near where ,morebattle now is4 ,wreaths and hummocks of gravel and sand1 extending from ,grubbit to the north-east1 along the hollow in the hills that leads to ,yetholm ,loch1 indicate the course taken by a portion of the torrents that escaped from the ice in summer-time4 ,in other hill-valleys1 similar indications of ancient local glaciers may be seen4 ,some of the most conspicuous of these appear upon the slopes and in the high valleys within the drainage-areas of the ,jed and the ,kale4 ,they consist chiefly of mounds and hillocks1 made up of coarse earthy dbris and rock-rubbish2 sometimes these are solitary and rest in the throat of a valley1 at other times they are scattered all over the hill-slopes and valley-bottom4 ,one can have no doubt as to what they mean3 they indicate clearly the presence of insignificant glaciers that were soon to vanish away4 ,the larger and better-defined mounds are true terminal moraines1 while the scattered heaps of rubbish point out for us the beds in which the glaciers lay4 ,thus1 from the sea-coast up to the highest ridge of this border country1 we follow the spoor of the melting ice2 passing from massive and wide-spread deposits of till1 gravel1 and sand1 and angular dbris in the low-grounds1 up to insignificant heaps and scatterings of rock-rubbish and angular boulders at the higher levels of the country4 ,several more or less extensive flats in the hill-valleys indicate the former presence of lakes which have become obliterated by the action of the streams4 ,but by far the most conspicuous example of such silted-up lakes is that of the ,kale valley1 to which reference has already been made4 ,in the later stages of the ,ice ,age that river-valley must have existed as a lake from ,marlfield up to and beyond ,morebattle4 ,indeed1 there is evidence to show that even within historical times a considerable lake overspread the flat grounds in this neighbourhood4 ,the name ,morebattle is supposed to mean the village by the lake1 and1 up to a few years ago1 there was a sheet of water called ,linton ,loch a little to the east of ,morebattle4 ,but this has been drained by the proprietor1 and is now represented by only two insignificant pools4 ,the present course of the ,kale between ,marlfield and ,kalemouth is of post-glacial age--the old pre-glacial and interglacial course being filled up with drifted materials4 ,as the appearances at this place are somewhat typical of many of the valleys of the ,cheviot district1 ,i may briefly summarise the history of the ,morebattle lake4 ,before the advent of the last great age of ice the ,kale would seem to have flowed from ,marlfield1 close to the line now followed by the turnpike road as far as ,easter ,wooden1 after which it passed near the present sites of ,blinkbonny and ,mosstower1 and so on to the ,teviot1 which it joined some little distance above ,kalemouth4 ,during the ,ice ,age many of the old river-courses were completely choked up with clay1 stones1 and gravel1 so that when the ice melted away the rivers did not always or even often regain their old channels4 ,thus1 in the case of the ,kale1 we find that the present course of the river below ,marlfield is of recent or post-glacial age1 having been excavated by the river since the close of the glacial epoch4 ,the old or pre-glacial course lies completely choked up and concealed under the rubbish shot into it at a time when glacier-ice filled all the valley of the ,kale down to ,marlfield4 ,at this latter place the ,kale glacier seems to have made a considerable pause--it ceased for some time to retreat--and thus a heavy bank of gravel1 sand1 shingle1 earth1 blocks1 and angular rubbish gathered in front of it1 and obliterated the old river-course into which they were dropped4 ,when the glacier at last disappeared1 a lake was formed above the morainic dam that closed the valley below ,marlfield1 and the outflow of the lake took place at a point lying some little distance to the north of the old or pre-glacial course of the ,kale4 ,by slow degrees the river excavated a new channel for itself in the ,old ,red ,sandstone rocks1 and in doing so gradually lowered the level of the waters4 ,this and the silting action of the ,kale and its feeders slowly converted the lake-hollow into a broad alluvial flat through which the river now winds its way4 ,another extensive lake seems to have occupied the vale of the ,teviot between ,jedfoot and ,eckford1 and similar old lake-beds occur in several of the hill-valleys4 ,one good example is seen in the valley of the ,oxnam ,water1 where the flat tract that extends from the old village of ,oxnam up to the foot of the ,row ,hill indicates the former presence of a lake which has been drained by the stream cutting for itself a gorge in ,silurian greywacks and shales4 ,in many other valleys it is easy to see that the streams do not always occupy their pre-glacial courses1 and some of the old forsaken courses are still patent enough4 ,thus1 a glance at the hollow that extends from ,mossburnford on the ,jed to ,hardenpeel on the ,oxnam is enough to convince one that in pre-glacial1 and probably in early post-glacial times also1 a considerable stream has flowed from what is now the vale of the ,jed into the valley of the ,oxnam4 ,in all the valleys we meet with striking evidence to show that the streams and rivers must formerly have been larger than they are now4 ,certain banks and ridges of gravel fringe the valley-slopes at considerable heights1 and indicate the action of deeper and broader currents than now make their way towards the sea4 ,it is probable that these high-level gravel terraces date their existence back to the close of the ,ice ,age1 when local glaciers still lingered in some of the mountain-valleys1 and when in summer-time great floods and torrents descended from the hills4 ,an extremely humid climate seems to have characterised ,scotland even in post-glacial times1 as may be gathered from the phenomena of her peat-mosses4 ,very little peat occurs on the ,scottish side of the ,cheviots1 and it is conspicuous chiefly on the very crest of the hills1 where it attains a thickness that varies from a foot or two up to five or six yards4 ,here and there we detect the remains of birch under the peat1 but the peat itself is composed chiefly of bog-moss and heather4 ,the evidence so abundantly supplied by the peat-mosses in other parts of ,scotland shows that after the ,ice ,age had passed away the ,scottish area became clothed with luxuriant forests of oak1 pine1 and other trees4 ,at that time the ,british ,islands appear to have been joined to themselves and the ,continent across the upraised beds of the ,irish ,sea and the ,german ,ocean4 ,races of men who used polished stone implements and sailed in canoes that were hollowed out of single oaks inhabited the country1 together with certain species of oxen 7now either extinct or domesticated71 the elk1 the beaver1 the wolf1 and other animals1 such as the dog and the sheep1 which are still indigenous4 ,the climate was more excessive then than it is now--the summers being warmer and the winters colder4 ,by-and-by1 however1 submergence ensued1 the great wooded plain that seems once to have extended between ,britain and the ,continent disappeared below the waves1 and the climate of this country became more humid4 ,the old forests began to decay and the peat-mosses to increase1 until by-and-by large areas in the low-grounds passed into the condition of dreary moor and morass1 and even the brushwood and stunted trees of the hills died down and became enveloped in a mantle of bog-moss4 ,a study of the present condition of the ,scottish peat-mosses leads one to believe that the rate of increase is now much exceeded by the rate of decay1 and that the eventual disappearance of the peat that clothes hill-tops and valley-bottoms is only a question of time4 ,draining and other agricultural operations have no doubt influenced to some extent this general decay of the peat-mosses2 but there is reason to suspect that the change of climate1 to which the decay of the peat is due1 may really be owing to some cosmical cause4 ,quite recently an accomplished ,norwegian botanist has come to similar conclusions regarding the peat-mosses of the ,scandinavian peninsula4 ,we have now traced the geological history of the ,cheviot district down to the ,recent ,period4 ,from this point the story of the past must be continued by the archologist1 and into his province ,i will not trespass further than to indicate some of the more remarkable traces which the early human occupants of the upland valleys left behind them4 ,before doing so1 however1 ,i may briefly recapitulate the general results we have obtained from our rapid review of the glacial and post-glacial deposits4 ,a study of these has taught us that the ,cheviot ,hills and the adjoining low-grounds participated in those arctic conditions under the influence of which all ,scotland and a large portion of ,england were buried beneath a wide-spread mer de glace4 ,the ,cheviots themselves were completely smothered under a mass of glacier-ice which extended across the vale of the ,tweed1 and was continuous over the ,lammermuirs with the vast sheet that filled all the great lowlands of central ,scotland4 ,but although the ,cheviots were thus overwhelmed1 they yet served to divide the ice-flow1 for we find that the gelid masses moved outwards from the hills towards the valley of the ,tweed1 turning gradually away to east and south-east to creep over the north part of ,england4 ,how far south the ice-sheet reached has not yet been determined1 but its moraine profonde or till may be traced to the edge of the ,thames valley2 and ,i have picked up in ,norfolk ice-worn fragments of igneous rock1 which have been derived from the ,cheviots themselves1 showing that ,scottish ice actually invaded the low-grounds south of the ,wash4 ,such severe glacial conditions1 after continuing for a long time1 were interrupted more than once by intervening periods characterised by a milder and more genial climate4 ,the great mer de glace then melted out of the valleys1 and for aught that we can say the snow and ice may even have vanished from the hills themselves4 ,vegetation now covered the country1 and herds of the mammoth1 the old extinct ox1 the ,irish elk1 the reindeer1 the horse1 and probably other creatures1 roamed over the now deserted beds of the glaciers4 ,it was probably at this time that ,palolithic man lived in ,britain4 ,he was contemporaneous with lions1 elephants1 rhinoceroses1 hippopotami1 mammoths1 reindeer1 and other animals of southern and northern habitats1 the former living in ,england when the climate was genial1 but being replaced by the northern species when the temperature began again to fall1 and snow and glaciers once more reappeared and crept downwards and outwards from the hills4 ,towards the close of the interglacial period the land became submerged to a considerable extent1 and species of arctic shells lived over the sites of the drowned land where the mammoth and its congeners had flourished4 ,by-and-by the cold so far increased that another great ice-sheet filled up the shallow sea1 and as it slowly ground over the face of the land and the sea-bottom1 it scoured out and demolished to a large extent all loose fluviatile1 lacustrine1 and marine accumulations4 ,when at last the ice melted away1 it left the ground cumbered with stony clay1 and with much gravel and sand and morainic dbris4 ,it is underneath these deposits that we yet obtain now and again fragments of the life of that interglacial epoch4 ,but in all the regions visited by the last great incursion of the mer de glace1 such relics are comparatively rare2 it is only when we get beyond the districts that were overwhelmed that the ancient interglacial remains are well preserved4 ,beyond the southern extremity reached by the latest general ice-sheet--that is to say1 in the regions south of the ,humber1 we find the country often sprinkled with tumultuous heaps and wide-spread sheets of gravel and brick-earth1 which seem to owe their origin to the floods and torrents that escaped from the melting ice4 ,these waters1 sweeping over the land1 carried along with them such relics of man and beast as lay at the surface1 washing away interglacial river-deposits1 and scattering the materials far and wide over the undulating low-grounds of central and eastern ,england4 ,mr4 ,s4 ,b4 ,j4 ,skertchly1 of the ,geological ,survey of ,england1 has shown that such is the origin of the so-called river-gravels with ancient flint implements and mammalian remains in the districts watered by the ,little ,ouse1 the ,waveney1 and other rivers in that part of ,england4 ,these gravels could not possibly have been deposited by the present rivers1 for they are found capping the hills at a height of more than eighty feet above the sources of the streams4 ,the whole aspect of the gravels1 indeed1 betokens the action of rapid floods and torrents1 such as must have been discharged abundantly in summer-time from the melting ice-sheet that lay at no great distance to the north4 ,when the ice-sheet vanished away1 it left the ground covered thickly in many places with its various deposits4 ,rivers and streams were thus often debarred from their old channels1 and were forced to cut out for themselves new courses1 partly in drifted materials1 and partly in solid rock4 ,a number of lakes then existed which have since been silted up4 ,so long as glaciers lingered in the hill-valleys1 the rivers seem to have flowed in greater volume than they now do4 ,by-and-by the bare and treeless country became clothed with a luxuriant forest-growth1 and was tenanted by animals1 many of which are still indigenous to our country1 while others have become locally extinct1 such as wolf1 beaver1 and wild boar4 ,in certain of the old lake-beds of the ,cheviot district numerous remains of red-deer and other animals have been turned out in the search for marl1 and in land drainage and reclamation operations--the red-deer antlers being sometimes of noble dimensions4 ,it seems probable that in early post-glacial times our country was joined to the ,continent and shared in a continental climate1 the summers being then warmer and the winters colder than now4 ,the men who lived in ,britain after the final disappearance of the great glaciers used stone implements1 which were often polished and highly finished1 and they sailed in canoes1 being probably a race of active hunters and fishers4 ,they belong to the archologist's ,neolithic or new-stone period--the ,palolithic or old-stone period being of much older date1 and separated1 as ,i believe1 from ,neolithic times by the intervention of the last cold epoch of the ,ice ,age4 ,to the forest epoch succeeded a time when the climate became very humid1 a result which may have been due in large part to the separation of ,britain from the ,continent4 ,it was then that the ancient forests began to decay1 and peat-mosses to increase4 ,how long such humid conditions of climate characterised the country we can hardly say1 but we know that nowadays our peat-mosses do not grow so rapidly as they once did1 and indeed almost everywhere the rate of decay is greater than the rate of increase4 ,this points to a further change of climate1 and brings us at once face to face with the present4 ,and now a few words1 in conclusion1 as to the old camps and other remains that occur so abundantly in the valleys of the ,cheviot ,hills4 ,in many of the hill-valleys1 especially towards their upper reaches1 as in the valleys of the ,kale and the ,bowmont1 almost every hill is marked by the presence of one or more circular or oval camps or forts4 ,they are generally placed in the most defensible positions1 on the very tops of the hills or on projecting spurs and ridges4 ,most of them are of inconsiderable dimensions1 and could not have afforded protection to any large number of men1 for many hardly exceed one hundred feet in diameter4 ,not a few consist of only a single circular or oval rampart with an external ditch--the rampart being composed of the rude dbris which was dug out to form the ditch4 ,others1 however1 are not only much larger 7five to six hundred feet in diameter71 but surrounded1 in whole or in part1 with two or more ramparts separated by intervening ditches2 and ,i have noticed that as a rule the side which must have been most easily assailable was protected by several ramparts rising one above the other4 ,from the extraordinary number of these hill-forts one has the impression that the upper valleys of the ,cheviots must at one time have been thickly peopled1 probably in pre-,roman times4 ,it is easy to see that the camps or forts overlooking a valley often bear a certain relation to each other1 as if the one had been raised to support the other1 and not infrequently we can trace well-marked intrenchments extending across a hill-ridge1 or along a hill-slope for a distance of not much short of a mile1 and evidently having some strategic connection with the forts or camps in their vicinity4 ,i found no trace of any dwellings1 either near the forts or in the vicinity of the terraces4 ,the only indications of what may have been the walls of such appear within a fortified camp1 called the ,moat ,hill1 at ,buchtrig4 ,this is an isolated knoll of rock1 which has been strongly fortified--large slabs and blocks of the porphyrite of which it is composed having been wedged out with infinite pains to form circular ramparts4 ,the walls are of course nearly level with the ground and grassed over1 but they indicate little square enclosures1 which may very possibly have been huts closely huddled together4 ,this fort is oval1 and measures five hundred feet by two hundred and seventy4 ,in the same neighbourhood we also meet with plentiful marks of ancient cultivation and with places of sepulture--all of which may without much doubt be referred to the same period as the camps and forts4 ,the slopes of the hills are often marked with broad horizontal terraces1 that remind one strongly of the lazy-beds of the ,hebrides4 ,they are evidently the cultivated grounds of the hill-men1 and doubtless the hill-slopes were selected for various reasons1 chief among which would be their retired and somewhat inaccessible position4 ,the ease with which they could be drained and irrigated would be another of their recommendations2 and we must bear in mind that at this early date the low-grounds were covered with forests and morasses1 and therefore not so easily cultivated as the hill-slopes4 ,here and there we notice also little conical hillocks or tumuli4 ,they were formerly much more numerous1 and by-and-by they will doubtless all disappear4 ,numbers1 even within recent years1 have been pulled down1 partly to clear the ground1 and partly for the sake of the stones of which they are composed4 ,this is much to be regretted2 for their destruction simply means the obliteration of historical records1 the loss of which can never be made good4 ,i asked a farmer what had become of the tumuli which at one time1 according to the ,ordnance ,survey map1 were dotted over the hill behind his house4 ,if it's the wee knowes 7knolls7 you mean1 ,i pu'd them down1 for they were jist in the way4 ,there was naething o' importance below the stanes1 only a wheen worthless bits o' pottery6 ,and the worthy pointed to a heap of stones behind a neighbouring dyke1 where ,i afterwards found some fragments of the pottery which had been so ruthlessly demolished4 ,these tumuli are no doubt old burial-places1 and much information concerning the habits of our ancient predecessors might often be obtained by a careful examination of the mounds1 when it is deemed essential to remove them4 ,but1 surely1 after all1 they might be spared1 for they can seldom be so very much in the way2 and1 at all events1 if they must be removed1 might it not be well to communicate the fact of their approaching demolition to some local archological society1 or to any member of the ,berwickshire ,naturalists' ,club1 who for the sake of science would1 ,i feel certain1 do what was possible to preserve an accurate account of their contents8 ,standing-stones are met with now and again1 either singly or in groups1 and sometimes they form circles4 ,it is most likely that they were raised by the same people who made the forts and tilled the horizontal lazy-beds4 ,one can only conjecture that they may have been designed as memorial stones1 to mark the place where a chief or person of consequence was slain in battle4 ,they may also mark burial-places1 or indicate the site of some deed of prowess or other action or circumstance worthy of being remembered4 ,antiquarians at one time considered that all these stones were relics of druidical worship2 but it is needless to say that this view has long been abandoned4 ,that the ancient inhabitants of the ,cheviots may have had some kind of religion is exceedingly probable1 but it must have been of a very primitive kind1 not more advanced than that of the ,north ,american ,indians4 ,such are some of the more notable relics of the people who lived in the valleys of the ,cheviot ,hills in pre-,roman times4 ,these valleys1 as ,i have said1 seem to have supported a numerous population1 who tilled the slopes and probably hunted in the forests of the adjoining low-grounds4 ,that they lived in fear of foes is sufficiently evident from the number of their intrenchments and fortified camps1 to which they would betake themselves whenever their enemies appeared4 ,what effect the ,roman occupation had on the dwellers among these hills we cannot tell4 ,the great ,watling ,street passes across the ,cheviots1 and there are some old circular forts and camps quite close to that wonderful road1 along which many a battalion of ,roman soldiers must have marched2 and these forts1 if of pre-,roman age1 were not at all likely to have been held by the natives after ,watling ,street was made4 ,in the remoter fastnesses of the hills1 however1 the old tribes may have continued to crop their lazy-beds1 to hunt1 and tend their herds1 during the ,roman occupation1 and the old forts may have been in requisition long after the last ,roman had disappeared over the borders4 ,but ,i have already1 ,i fear1 delayed too long over the old history of the ,cheviot ,hills1 and must now draw my meagre sketches to a close4 ,in my first paper ,i said that these hills were a terra incognita to the tourist4 ,those who visit the district must not therefore expect to meet with hotel accommodation4 ,but knowing pedestrians will not be much disturbed with this information1 and will probably find1 after they have concluded their wanderings1 that the hospitality and general heartiness for which our stalwart ,borderers were famous in other days are still as noteworthy characteristics as they used to be4 ,v4 ,the ,long ,island1 or ,outer ,hebrides4,j ,j ,good ,words1 #ahgi4 ,i4 ,that long range of islands and islets which1 extending from latitude #ef #dg' ,n4 to latitude #eh #cb' ,n41 acts as a great natural breakwater to protect the north-west coast of ,scotland from the rude assaults of the ,atlantic billows is not much visited by the ordinary tourist4 ,during the season the steamers now and again1 it is true1 deposit a few wanderers at ,tarbert and ,stornoway1 some of whom may linger for a shorter or longer time to try a cast for salmon in ,loch ,laxdail1 while others1 on similar piscatorial deeds intent1 may venture inland as far as ,gearaidh nah ,aimhne 7,garrynahine74 ,others1 again1 who are curious in the matter of antiquities1 may visit the weird standing-stones of ,callernish1 or even brave the jolting of a trap along the somewhat rough road that leads from ,tarbert to ,rodel1 in order to inspect the picturesque little chapel there1 and take rubbings of its quaint tombstones with their recumbent effigies of knights1 and ,crusaders' swords1 and somewhat incomprehensible ,latinity4 ,occasionally a few bolder spirits may be tempted by the guide-books to visit ,barra ,head1 with its ruddy cliffs and clouds of noisy sea-birds1 or even to run north to the extremity of the ,long ,island to view the wonders of the ,butt of ,lewis4 ,but1 as a rule1 the few summer visitants who are landed at ,stornoway content themselves with a general inspection of the grounds about ,sir ,james ,mathieson's residence1 while those who are dropped at ,tarbert on ,saturday are usually quite ready to depart on ,monday with the steamer that brought them4 ,the fact is that hotel accommodation in the ,outer ,hebrides is rather limited1 and the means of locomotion through the islands is on the same slender scale4 ,those1 therefore1 who are not able and willing to rough it had better not venture far beyond ,tarbert and ,stornoway4 ,when the islands are first approached they present1 it must be confessed1 a somewhat forbidding aspect4 ,bare1 bleak rocks1 with a monotonous rounded outline1 crowd along the shore1 and seem to form all but the very highest portions of the land that meet our view1 while such areas of low-ground as we can catch a glimpse of appear to be everywhere covered with a dusky mantle of heath and peat4 ,but1 although the general character of the scenery is thus tame and sombre1 yet there are certain districts which in their wild picturesqueness are hardly surpassed by many places in the northern ,highlands1 while one may search the coast-line of the mainland in vain for cliffs to compare with those gaunt walls of rock1 against which the great rollers of the ,atlantic continually surge and thunder4 ,it is wonderful1 too1 how1 under the influence of a light-blue sky1 flecked with shining silvery clouds1 the sombre peat-lands lighten up and glow with regal purple and ruddy brown4 ,with such a sky above him1 and with a lively breeze fresh from the ,atlantic and laden with the sweetness of clover and meadow-hay and heather-bloom sweeping gaily past him1 what wanderer in the ,outer ,hebrides need be pitied8 ,and such days are by no means so rare in these islands as many a jaundiced ,lowlander has maintained4 ,it is true that heavy mists and drizzling rain are often provokingly prevalent1 and ,i cannot forget the experience of a sad-hearted exile1 who had resided continuously for a year in ,lewis1 and who1 upon being asked what kind of climate that island enjoyed1 replied3 ,sir1 it has no climate4 ,there are nine months of winter1 and three months of very bad weather4 ,for myself1 ,i can say that my experience of the climate in ,june1 ,july1 and early ,august of several years has been decidedly favourable4 ,during those months ,i found comparatively few days in which a very fair amount of walking and climbing could not be accomplished with ease and pleasure1 and that is a good deal more than one could venture to say of ,skye and many parts of the west coast of the mainland4 ,the greatest drawback to one's comfort are the midges1 which in these islands are beyond measure bloodthirsty1 and quite as obnoxious as the most carnivorous mosquitoes4 ,smoking1 and all the other arts and devices by which the designs of these tiny pests are usually circumvented1 have no effect upon the ,hebridean vampires4 ,in the low-grounds especially they make life a burden4 ,but those who have already become acquainted with the ,ross-shire midges1 and yet have preserved their equanimity1 may feel justified in braving the ferocity of the ,hebridean hosts4 ,and if they do so ,i believe they will be well repaid for their courage4 ,to the hardy pedestrian1 especially1 who likes to escape from the beaten track laid down in guide-books1 it will be a pleasure in itself to roam over a region which has not yet come entirely under the dominion of ,mr4 ,cook4 ,if he be simply a lover of the picturesque he will yet not be disappointed1 and possibly he may pick up a few hints in these notes as to those districts which are most likely to repay him for his toil in reaching them4 ,but if to his love of the picturesque he joins a taste for archological pursuits1 then ,i can assure him there is a rich and by no means exhausted field of study in the antiquities of the ,long ,island4 ,interesting1 however1 as are the relics of prehistoric and later times which one meets with1 yet it is the geologist1 perhaps1 who will be most rewarded by a visit to these islands4 ,the physical features of the ,outer ,hebrides are1 as already stated1 somewhat monotonous1 but this is quite consistent with considerable variety of scenic effect4 ,all the islands are not equally attractive1 although the configuration of hills and low-grounds remains persistently the same from the ,butt of ,lewis to ,barra ,head4 ,the most considerable island is that of which ,lewis and ,harris form the northern and southern portions respectively4 ,by far the larger part of the former is undulating moorland1 the only really mountainous district being that which adjoins ,harris in the south4 ,a good general idea of the moorlands is obtained by crossing the island from ,stornoway to ,garrynahine4 ,what appeared at first to be only one vast extended peat-bog is then seen to be a gently-undulating country1 coated1 it is true1 with much peat in the hollows1 but clad for the most part with heath1 through which ever and anon peer bare rocks and rocky dbris4 ,now and again1 indeed1 especially towards the centre of the island1 the ground rises into rough round-topped hills1 sprinkled sparingly with vegetation4 ,one of the most striking features of the low-grounds1 however1 is the enormous number of freshwater lakes1 which are so abundant as to form no small proportion of the surface4 ,they are1 as a rule1 most irregular in outline1 but have a tendency to arrange themselves in two directions--one set trending from south-east to north-west1 while another series is drawn out1 as it were1 from south-west to north-east4 ,i am sure that ,i am within the mark in estimating the freshwater lakes in the low-grounds of ,lewis to be at least five hundred in number4 ,in the mountain-district the lakes are1 of course1 confined to the valleys1 and vary in direction accordingly4 ,harris and the southern part of ,lewis are wholly mountainous1 and show hardly a single acre of level ground4 ,the mountains are often bold and picturesque1 especially those which are over #afjj feet in height4 ,they are also exceedingly bare and desolate1 the vegetation on their slopes being poor and scanty in the extreme4 ,some of the hills1 indeed1 are absolutely barren4 ,in ,north ,harris we find the highest peaks of the ,outer ,hebrides3 these are the ,clisham1 #bfbb feet1 and the ,langa1 #bdch feet4 ,the glens in this elevated district are often wild and rugged1 such as the ,bealach-,miavag and the ,bealach-na-,ciste1 both of which open on ,west ,loch ,tarbert4 ,but amid all this ruggedness and wild disorder of broken crag and beetling precipice1 even a very non-observant eye can hardly fail to notice that the general contour or configuration of the hills is smooth1 rounded1 and flowing1 up to a rather well-marked level1 above which the outline becomes broken and interrupted1 and all the rounded and smoothed appearance vanishes4 ,the contrast between the smoothly-flowing contour of the lower elevations and the shattered and riven aspect of the harsh ridges1 sharp peaks1 and craggy tors above1 is particularly striking4 ,the mammillated and dome-shaped masses have a pale1 ghastly grey hue1 their broad bare surfaces reflecting the light freely1 while at higher elevations the abundant irregularities of the rocks throw many shadows1 and impart a darker aspect to the mountain-tops4 ,the appearances now described are very well seen along the shores of ,west ,loch ,tarbert4 ,all the hills that abut upon that loch show smoothed and rounded faces1 and this character prevails up to a height of #afjj feet1 or thereabout1 when all at once it gives way1 and a broken1 interrupted contour succeeds4 ,thus the top of the ,tarcall ridge in ,south ,harris is dark1 rough1 and irregular1 while the slopes below are grey1 smooth1 and flowing4 ,the same is conspicuously the case with the mountains in ,north ,harris1 the ruinous and sombre-looking summits of the ,langa and the ,clisham soaring for several hundred feet above the pale grey mammillated hills that sweep downwards to the sea4 ,after having familiarised themselves with the aspect of the hills as seen from below1 the lover of the picturesque1 not less than the geologist1 will do well to ascend some dominant point from which an extensive bird's-eye view can be obtained4 ,for such purpose ,i can recommend the ,tarcall and ,roneval in ,south ,harris1 the ,clisham and the ,langa in ,north ,harris1 and ,suainabhal in ,lewis4 ,the view from these hills is wonderfully extensive and very impressive4 ,from ,suainabhal one commands nearly all ,lewis2 and what a weird picture of desolation it is6 ,an endless succession of bare1 grey1 round-backed rocks and hills1 with countless lakes and lakelets nestling in their hollows1 undulates outwards over the districts of ,uig and ,pairc4 ,away to the north spread the great moorlands with their lochans1 while immediately to the south one catches a fine panoramic view of the mountains of ,harris4 ,and then those long straggling arms of the sea1 reaching into the very heart of the island--how blue1 and bright1 and fresh they look6 ,i suppose the natives of the ,lewis must have been fishermen from the very earliest times4 ,it seems hardly possible otherwise to believe that the bare rocks and peat-bogs1 which form the major portion of its surface1 could ever have supported a large population2 and yet there is every evidence to show that this part of the ,long ,island was tolerably well populated in very early days4 ,the great standing-stones of ,callernish and the many other monoliths1 both solitary and in groups1 that are scattered along the west coast of ,lewis1 surely betoken as much4 ,and those curious round towers1 or places of refuge and defence1 which are so well represented in the same district1 although they may be much younger in date than the monoliths of ,callernish1 tell the same tale4 ,from the summits of the ,clisham and the ,langa the view is finer than that obtained from ,suainabhal4 ,the former overlook all the high-grounds of ,harris and ,lewis1 and the monotonous moors with their countless straggling lakes and peaty tarns4 ,indeed1 they dominate nearly the whole of the ,long ,island1 the hills of distant ,barra being quite distinguishable4 ,of course1 the lofty island of ,rum1 and ,skye with its ,coolins1 are both clearly visible1 the whole view being framed in to eastward by the mountains of ,ross and ,sutherland4 ,on a clear day1 which1 unfortunately1 ,i did not get1 one should be quite able to see ,st4 ,kilda4 ,hardly less extensive is the view obtained from ,roneval 7#aejf feet7 in the south of ,harris4 ,far away to the west lie ,st4 ,kilda and its little sister islet of ,borerey4 ,southwards stretch the various islands of the ,outer ,hebrides--,north ,uist1 ,benbecula1 ,south ,uist1 and ,barra4 ,how plainly visible they all are--a screen of high mountains facing the ,minch1 and extending1 apparently1 along their whole eastern margin--with broad lake-dappled plains sweeping out from the foot-hills to the ,atlantic4 ,in the east1 ,skye with its spiky ,coolins spreads before one1 and north of ,skye we easily distinguish ,ben ,slioch and the mountains of ,loch ,maree and ,loch ,torridon4 ,south ,harris lies1 of course1 under our feet1 and it is hard to give one who has not seen it an adequate notion of its sterile desolation4 ,round-backed hills and rocks innumerable1 scraped bare of any soil1 and supporting hardly a vestige of vegetation2 heavy mountain-masses with a similar rounded contour1 and equally naked and desolate2 blue lakelets scattered in hundreds among the hollows and depressions of the land3 such is the general appearance of the rocky wilderness that stretches inland from the shores of the ,minch4 ,then all around lies the great blue sea1 shining like sapphire in the sun1 and flecked with tiny sails1 where the fishermen are busy at their calling4 ,from what has now been said1 it will readily be understood that there is not much cultivable land in ,harris and the hilly parts of ,lewis4 ,what little there is occurs chiefly along the west coast1 a character which we shall find is common to most of the islands of the ,outer ,hebrides4 ,in the neighbourhood of ,stornoway1 and over considerable areas along the whole west coast of ,lewis1 the moorlands have been broken in upon by spade and plough1 with more or less success4 ,but natural meadow-lands1 such as are frequently met with on the west side of many of the islands both of the ,outer and ,inner ,hebrides1 are not very common in ,lewis4 ,one of the most notable features of the hillier parts of the ,long ,island are the enormous numbers of loose stones and boulders which are everywhere scattered about on hill-top1 hill-side1 and valley-bottom4 ,harris is literally peppered with them1 and they are hardly less abundant in the other islands4 ,they are of all shapes and sizes--round1 sub-angular1 and angular4 ,one great block in ,barra ,i estimated to weigh seven hundred and seventy tons4 ,many measure over three or four yards across1 while myriads are much smaller4 ,these boulders are sometimes utilised in a singular way4 ,in ,harris1 there being only one burial-place1 the poor people have often to carry their dead a long distance1 and this of course necessitates resting on the journey4 ,to mark the spot where they have rested1 the mourners are wont to erect little cairns by the road-side1 many of which are neatly built in the form of cones and pyramids1 while others are mere shapeless heaps of stones thrown loosely together4 ,instead of raising cairns1 however1 they occasionally select some boulder1 and make it serve the purpose by canting it up and inserting one or more stones underneath4 ,occasionally ,i have seen in various parts of the mainland great boulders cocked up at one end in the same way4 ,some of these may be in their natural position1 but as they often occupy conspicuous and commanding situations1 ,i am inclined to think that the cromlech-builders may have tampered with them for memorial purposes4 ,the present custom of the ,harris men may therefore be a survival from that far-distant period when ,callernish was in its glory4 ,north ,uist is truly a land of desolation and dreariness4 ,bare1 rocky hills1 which are remarkable for their sterile nakedness even in the ,long ,island1 form the eastern margin1 and from the foot of these the low1 undulating rocky and peaty land stretches for some ten or twelve miles to the ,atlantic4 ,the land is everywhere intersected by long1 straggling inlets of sea-water1 and sprinkled with lakes and peaty tarns innumerable4 ,along the flat ,atlantic coast1 which is overlooked by some sparsely-clad hills1 are dreary stretches of yellow sand blown up into dunes4 ,near these are a few huts and a kirk and manse4 ,not a tree1 not even a bush higher than heather1 is to be seen4 ,peat1 and water1 and rock2 rock1 and water1 and peat--that is ,north ,uist4 ,the neighbourhood of ,lochmaddy1 which is the residence of a sheriff-substitute1 and rejoices besides in the possession of a jail1 is depressing in the extreme4 ,it is made up of irregular bits of flat land all jumbled about in a shallow sea1 so that to get to a place one mile in direct distance you may have to walk five or six miles1 or even more4 ,i could not but agree with the natives of the more coherent parts of the ,long ,island1 who are wont to declare that ,lochmaddy is only the clippings of creation--the odds and ends and scraps left over after the better lands were finished4 ,north ,uist1 however1 boasts of some interesting antiquities--,picts' houses1 and a great cairn called the ,barp1 inside of which1 according to tradition1 rest the remains of a wicked prince of the good old days4 ,notwithstanding these1 there are probably few visitors who will not pronounce ,north ,uist to be a dreary island4 ,benbecula is precisely like ,north ,uist1 but it lacks the bare mountains of the latter4 ,there is only one hill1 indeed1 in ,benbecula2 all the rest is morass1 peat1 and water4 ,massive mountains fringe all the eastern shores of ,south ,uist1 and send westward numerous spurs and foot-hills that encroach upon the machars1 or good lands1 so as to reduce then to a mere narrow strip1 bordering on the ,atlantic4 ,save the summits of ,beinn ,mhor 7#bjcc feet7 and ,hecla 7#aihh feet71 which are peaked and rugged1 all the hills show the characteristic flowing outline which has already been described in connection with the physical features of ,harris4 ,the low-grounds are1 as usual1 thickly studded with lakes1 and large loose boulders are scattered about in all directions4 ,barra is wholly mountainous1 and1 except that it is somewhat less sterile1 closely resembles ,harris in its physical features1 the hills being smoothed1 rounded1 and bare1 especially on the side of the island that faces the ,minch4 ,of the smaller islands that lie to the south1 such as ,papey1 ,miuley1 and ,bearnarey1 the most noteworthy features are the lofty cliffs which they present to the ,atlantic4 ,for the rest1 they show precisely the same appearances as the hillier and barer portions of the larger islands--rounded rocks with an undulating outline1 dotted over with loose stones and boulders1 and now and again half-smothered in yellow sand1 which the strong winds blow in upon them4 ,there is thus1 as ,i have said1 considerable uniformity and even monotony throughout the whole range of the ,outer ,hebrides4 ,i speak1 however1 chiefly as a geologist4 ,an artist1 no doubt1 will find infinite variety1 and as he wends his way by moorland1 or mountain-glen1 or sea-shore1 scenes are constantly coming into view which he will be fain to transfer to his sketch-book4 ,the colour-effects1 too1 are often surprisingly beautiful4 ,when the rich meadow-lands of the west coast are in all their glory1 they show many dazzling tints and shades1 the deep tender green being dashed and flushed with yellow1 and purple1 and scarlet1 and blue1 over which the delighted eye wanders to a belt of bright sand upon the shore1 and the vast azure expanse of the ,atlantic beyond4 ,inland are the heath-clad moors1 sprinkled with grey boulders and masses of barren rock1 and interspersed with lakes1 some of which are starred with clusters of lovely water-lilies4 ,behind the moorlands1 again1 rise the grim1 bald mountains1 seamed and scarred with gullies1 and in their very general nakedness and sterility offering the strongest contrast to the variegated border of russet moor1 and green meadow1 and yellow beach that fringe the ,atlantic coast4 ,all through the islands1 indeed1 the artist will come upon interesting subjects4 ,a most impressive scene may sometimes be witnessed on crossing the ,north ,ford1 between ,north ,uist and ,benbecula4 ,at low-water1 the channel or sound between these two islands1 which is five miles in breadth1 disappears and leaves exposed a wide expanse of wet sand and silt1 dotted with black rocks and low tangle-covered reefs and skerries4 ,on the morning ,i passed over1 ragged sheets of mist hung low down on the near horizon1 half-obscuring and half-revealing the stony islets1 and crags1 and hills that lay between the ford and the ,minch4 ,seen through such a medium1 the rocks assumed the most surprising forms1 sometimes towering into great peaks and cliffs1 at other times breaking up1 as it were1 into low reefs and shoals1 and anon dissolving in grey mist and vapour4 ,at other times the thin cloud-curtain would lift1 and then one fancied one saw some vast city with ponderous walls and battlements1 and lofty towers and steeples1 rising into the mist-wreaths that hung above it1 while from many points on the ,benbecula coast1 where kelp was being prepared1 clouds of smoke curled slowly upwards1 as if from the camp-fires of some besieging army4 ,the track of the ford winds round and about innumerable rocks1 upon which a number of natives1 each stooping solitary and silent to his or her work1 were reaping the luxuriant seaweed for kelp-making4 ,their silence was quite in keeping with the general stillness1 which would have been unbroken but for the harsh scream of the sea-birds1 as they ever and anon rose scared from their favourite feeding-grounds while we plodded and plashed on our way4 ,the artist who could successfully cope with such a scene would paint a singularly weird and suggestive picture4 ,but1 to return to the physical features of the ,long ,island1 what1 we may ask1 is the cause of that general monotony of outline to which reference has so frequently been made8 ,at first we seem to get an answer to our question when we are told that the islands of the ,outer ,hebrides are composed chiefly of one and the same kind of rock4 ,everyone nowadays has some knowledge of the fact that the peculiar features of any given district are greatly due to the character and arrangement of the rock-masses4 ,for example1 who is not familiar with the outline of a chalk country1 as distinguished from the contour of a region the rocks of which are composed1 let us say1 of alternating beds of limestone and sandstone and masses of old volcanic material8 ,the chalk country1 owing to the homogeneousness of its component strata1 has been moulded by the action of weather and running water into an undulating region with a softly-flowing outline1 while the district of composite formation has yielded unequally to the action of ,time's workers--rains1 and frosts1 and rivers--and so is diversified with ridge1 and escarpment1 and knolls1 and crags4 ,when1 therefore1 we learn that the ,outer ,hebrides are composed for the most part of the rock called gneiss and its varieties1 we seem to have at once found the meaning of the uniformity and monotony4 ,it is true that although pink and grey gneiss and schistose rocks prevail from the ,butt of ,lewis to ,barra ,head1 yet there are some other varieties occasionally met with--thus soft red sandstone and conglomerate rest upon the gneissic rocks near ,stornoway1 but they occur nowhere else throughout the ,long ,island4 ,now and again1 however1 the gneiss gives place to granite1 as on the west coast of ,lewis near ,carloway2 and here and there the strata are pierced by vertical dykes and curious twisted and reticulated veins of basalt-rock4 ,all these1 however1 hold but a minor and unimportant place as constituents of the islands4 ,gneiss is beyond question the most prevalent rock1 and we seem justified in assigning the peculiar monotony of the ,outer ,hebridean scenery to that fact4 ,but when we come to examine the matter more attentively1 we find that there is still some important factor wanting4 ,we have not got quite to the solution of the question4 ,when we study the manner in which the gneiss and gneissic rocks disintegrate and break up at the sea-coast or along the flanks of some rugged mountain-glen1 we see they give rise to an irregular uneven surface4 ,they do not naturally decompose and exfoliate into rounded dome-shaped masses1 such as are so commonly met with all through the islands1 but rather tend to assume the aspect of rugged tors1 and peaks1 and ridges4 ,the reason for this will be more readily understood when it is learned that the gneissic rocks of the ,outer ,hebrides are for the most part arranged in strata1 which1 notwithstanding their immense antiquity--7they are the oldest rocks in ,europe7--and the many changes they have undergone1 are yet1 as a rule1 quite distinguishable4 ,the strata are seldom or never horizontal1 but are usually inclined at a high angle1 either to north-east or south-west1 although sometimes1 as in the vicinity of ,stornoway1 the dip or inclination of the beds is to south-east4 ,throughout the major portion of the ,long ,island1 however1 the outcrop of the strata runs transversely across the land from south-east to north-west4 ,now we know that when this is the case strata of variable composition and character give rise to long escarpments and intervening hollows--the escarpments marking the outcrops of the harder and more durable beds1 and the hollows those strata that are softer and more easily eroded by the action of the denuding forces1 water and frost4 ,when the dip of the strata is north-east we expect the escarpments to face the south-west1 and the reverse will be the case when the strata incline in the opposite direction4 ,seeing then that the ,outer ,hebrides are composed chiefly of gneissic rocks and schists which yield unequally to the weather1 and which1 in the course of time1 would naturally give rise to lines of sharp-edged escarpments or ridges and intervening hollows1 with now and again massive hills and mountains showing great cliffs and a generally broken and irregular outline1 why is it that such rugged features are so seldom present at low levels1 and are only conspicuous at the very highest elevations8 ,the rocks of the ,outer ,hebrides are of immense antiquity1 and there has therefore been time enough for them to assume the irregular contour which we might have expected4 ,but in place of sharp-rimmed escarpments1 and tors1 and broken shattered ridges1 we see everywhere a rounded and smoothly-flowing configuration which prevails up to a height of #afjj feet or thereabout1 above which the rocks take on the rugged appearance which is natural to them4 ,by what magic have the strata at the lower levels escaped in such large measure from the action of rain and frost1 which have furrowed and shattered the higher mountain-tops8 ,i have said that long lines of escarpment and ridges1 corresponding to the outcrops of the harder and more durable strata1 are not apparent in these islands4 ,a trained eye1 however1 is not long in discovering that such features1 although masked and obscured1 are yet really present4 ,the round-backed rocks are drawn out1 as it were1 in one persistent direction1 which always agrees with the strike or outcrop of the strata2 and in many districts one notices also that long hollows traverse the land from south-east to north-west in the same way4 ,such alternating hollows and rounded ridges are very conspicuous in ,barra and the smaller islands to the south1 and they may likewise be noted in most of the larger islands also4 ,looking at these and other features1 the geologist has no hesitation in concluding that the whole of the islands have been subjected to some powerful abrading force1 which has succeeded to a large extent in obliterating the primary configuration of the land4 ,the rough ridges have been rounded off1 the sharp escarpments have been bevelled1 the abrupt tors and peaks have been smoothed down4 ,here and there1 it is true1 the dome-shaped rock-masses are beginning again to break up under the action of the weather so as to resume their original irregular configuration4 ,and1 doubtless1 after the lapse of many ages1 rain and frost will gradually succeed in destroying the present characteristic flowing outlines1 and the islands will then revert to their former condition1 and rugged escarpments1 sharp peaks1 and rough broken hummocks and tors will again become the rule4 ,but for a long time to come these grey ,western ,islands will continue to present us with some of the most instructive examples of rounded and mammillated rock-masses to be met with in ,europe4 ,from ,barra ,head in ,bearnarey to the ,butt of ,lewis we are constantly confronted by proofs of the former presence of that mysterious abrading power1 which has accommodated itself to all the sinuosities of the ground1 so that from the sea-level up to a height of #afjj feet at least1 the eye rests almost everywhere upon bare round-backed rocks and smoothed surfaces4 ,,ii4 ,in the preceding article ,i have described the peculiar configuration of the ,long ,island--rounded and flowing for the most part--and have pointed out how that softened outline is not such as the rocks would naturally assume under the influence of the ordinary agents of erosion with which we are familiar in this country4 ,the present contour has superseded an older set of features1 which1 although highly modified or disguised1 and often well-nigh obliterated1 are yet capable of being traced1 and are1 no doubt1 the conformation assumed by the rocks under the long-continued action of rain and frost and running water4 ,we have now to inquire what it was that removed or softened down the primal configuration ,i refer to1 and gave to the islands their present monotonous1 undulating contour4 ,any one fresh from the glacier-valleys of ,switzerland or ,norway could have little doubt as to the cause of the transformation4 ,the smoothed and rounded masses of the ,outer ,hebrides are so exactly paralleled by the ice-worn1 dome-shaped rocks over which a glacier has flowed1 that our visitor would have small hesitation in ascribing to them a similar origin2 and the presence of the countless perched blocks and boulders which are scattered broadcast over the islands would tend to confirm him in his belief4 ,a closer inspection of the phenomena would soon banish all doubt from his mind2 for1 on the less-weathered surfaces1 he would detect those long parallel scratches and furrows which are the sure signs of glacial action1 while1 in the hollows and over the low-grounds1 he would be confronted with that peculiar deposit of clay and sand and glaciated stones and boulders which are dragged on underneath flowing ice4 ,having satisfied ourselves that the rounded outline of the ground is the result of former glacial action1 our next step is to discover1 if we can1 in what direction the abrading agent moved4 ,did the ice1 as we might have supposed1 come out of the mountain-valleys and overflow the low country8 ,if that had been the case1 then we should expect to find the glacial markings radiating outwards in all directions from the higher elevations4 ,thus the low-grounds of ,uig1 in ,lewis1 should give evidence of having been overflowed by ice coming from the ,forest of ,harris2 the undulating1 rocky1 and lake-dappled region that extends between ,loch ,roag and ,loch ,erisort should be abraded and striated from south-west to north-east4 ,instead of this1 however1 the movement has clearly been from south-east to north-west4 ,all the prominent rock-faces that look towards the ,minch have been smoothed off and rounded1 while in their rear the marks of rubbing and abrading are much less conspicuous4 ,it is evident that the south-east exposure has borne the full brunt of the ice-grinding--the surfaces that are turned in the opposite direction1 or towards the ,atlantic1 having been in a measure protected or sheltered by their position4 ,the striations or scratches that are seen upon the less-weathered surfaces point invariably towards the north-west1 and from their character and the mode in which they have been graved upon the rock1 we are left in no doubt as to the trend of the old ice-plough--which was clearly from south-east to north-west4 ,nor is it only the low-grounds that are marked in this direction4 ,ascend ,suaina 7#acjj feet71 and you shall find it showing evident signs of having been abraded all over1 from base to summit4 ,the same1 indeed1 is the case with all the hills that stretch from sea to sea between ,uig and ,loch ,seaforth4 ,beinn ,mheadonach1 ,ceann ,resort1 ,griosamul1 and ,liuthaid1 are all strongly glaciated from south-east to north-west4 ,north and ,south ,harris yield unequivocal evidence of having been overflowed by ice which did not stream out of the mountain-valleys1 but crossed the island from the ,minch to the ,atlantic4 ,a number of mountain-glens1 coming down from the ,forest of ,harris1 open out upon ,west ,loch ,tarbert1 and these we see have been crossed at right angles by the ice--the mountains between them being strongly abraded from south-east to north-west4 ,it is the same all over ,south ,harris1 which affords the geologist every evidence of having been literally smothered in ice1 which has moved in the same persistent direction4 ,the rock-faces that look towards the ,minch are all excessively naked2 they have been terribly ground down and scraped1 and the same holds good with every part of the island exposed to the south-east4 ,now1 the mode in which the rocks have been so ground1 scraped1 rounded1 and smoothed betokens very clearly the action of land-ice1 and not of floating-ice or icebergs4 ,the abrading agent has accommodated itself to all the sinuosities of the ground1 sliding into hollows and creeping out of them1 moulding itself over projecting rocks1 so as eventually to grind away all their asperities1 and convert rugged tors and peaks into round-backed1 dome-shaped masses4 ,it has carried away the sharp edges of escarpments and ridges1 and has deepened the intervening hollows in a somewhat irregular way1 so that now these catch the drainage of the land and form lakes4 ,steep rocks facing the ,minch have been bevelled off and rounded atop1 while in their rear the ice-plough1 not being able to act with effect1 has not succeeded in removing the primeval ruggedness of the weathered strata4 ,i have said that the movement of the ice was from south-east to north-west4 ,but a close examination of the ice-markings will show that the flow was very frequently influenced by the form of the ground4 ,minor features it was able to disregard1 but some prominent projecting rock-masses succeeded in deflecting the ice that flowed against them4 ,for example1 if we study the rocks in ,north ,harris1 we shall find that the ,langa and the ,clisham have served as a wedge to divide the ice1 part of which flowed away into ,lewis1 while the other current or stream crept out to sea by ,west ,loch ,tarbert4 ,the ,langa and the ,clisham1 indeed1 raised their heads above the glacier mass--they were islets in a sea of ice4 ,it is for this reason that they and the ,tarcull ridge in ,south ,harris have not been smoothed and abraded1 but still preserve their weathered outline4 ,all surfaces below a height of #afjj feet which are exposed to the south-east1 and which have not been in recent times broken up by the action of rain and frost1 exhibit strongly-marked glaciation4 ,but above that level no signs of ancient ice-work can be recognised4 ,we see now why it is that the hill-slopes opposite the ,minch should1 as a rule1 be so much more sterile than those which slope down to the ,atlantic4 ,the full force of the ice was exerted upon the south-east front1 in the rear of which there would necessarily be comparatively quiet ice4 ,for the same reason we should expect to find much of the rock dbris which the ice swept off the south-east front sheltering on the opposite side4 ,neither clay nor sand nor stones would gather under the ice upon the steep rocks that face the ,minch4 ,the movement there was too severe to permit of any such accumulation4 ,but stones and clay and sand were carried over and swept round the hills1 and gradually accumulated in the rear of the ice-worn rocks1 just in the same way as gravel and sand are heaped up behind projecting stones and boulders in the bed of a stream4 ,hence it is that the western margin of ,harris is so much less bleak than the opposite side4 ,considerable taluses of till1 as the sub-glacial dbris is called1 gather behind the steeper crags1 and ragged sheets of the same material extend over the low-grounds4 ,all the low-grounds of ,lewis are in like manner sprinkled with till4 ,over that region the ice met with but few obstacles to its course1 and consequently the dbris it forced along underneath was spread out somewhat equally4 ,but wherever hills and peaks and hummocks of rock broke the regularity of the surface1 there great abrasion took place and no till was accumulated4 ,thus the position and distribution of this sub-glacial dbris or bottom-moraine tell the same tale as the abraded rocks and glacial stri1 and clearly indicate an ice-flow from the south-east4 ,this is still further proved by the manner in which the upturned ends of the strata are frequently bent over underneath the till in a north-westerly direction1 while the fragments dislodged from them and enclosed in the sub-glacial dbris stream away as it were to the same point of the compass4 ,not only so1 but in the west of ,lewis1 where no red sandstone occurs1 we find boulders of red sandstone enclosed in the till1 which could not have been derived from any place nearer than ,stornoway4 ,in other words1 these boulders have travelled across the island from the shores of the ,minch to the ,atlantic sea-board4 ,having said so much about the glaciation of ,lewis and ,harris1 ,i need not do more than indicate very briefly some of the more interesting features of the islands further south4 ,i spent some time cruising up and down the ,sound of ,harris1 and found that all the islets there had been ground and scraped by ice flowing in the normal north-west direction1 and sub-glacial dbris occurs on at least one of the little islands--,harmetrey4 ,but all the phenomena of glaciation are met with in most abundance in the dreary island of ,north ,uist4 ,the ridge of mountains that guards its east coast has been battered1 and ground down1 and scraped bare in the most wonderful manner1 while the melancholy moorlands are everywhere sprinkled with till1 full of glaciated stones1 many of which have travelled west from the coast range4 ,benbecula shows in like manner a considerable sprinkling of till1 and the trend of the glacial stri is the same there as in ,north ,uist1 namely1 a little north of west4 ,there are no hills of any consequence in ,benbecula1 but the highly-abraded and barren-looking mountains that fringe the eastern margin of ,north ,uist are continued south in the islands of ,roney and ,fuiey1 either of which it would be hard to surpass as examples of the prodigious effect of land-ice in scouring1 scraping1 and grinding the surface over which it moves4 ,south ,uist presents the same general configuration as ,north ,uist1 its east coast being formed of a long range of intensely glaciated mountains1 in the rear of which ragged sheets and heaps of sub-glacial dbris are thrown and scattered over the low1 undulating tract that borders the ,atlantic4 ,no part of either ,benbecula or ,north ,uist has escaped the action of ice1 but in ,south ,uist that knot of high-ground which is dominated by the fine mountains of ,beinn ,mhor and ,hecla towered above the level of the glacier-mass1 and have thus been the cause of considerable deflection of the ice-flow4 ,the ice-stream divided1 as it were1 part flowing round the north flank of ,hecla1 and part streaming past the southern slopes of ,beinn ,mhor4 ,but the ice-flow thus divided speedily reunited in the rear of the mountains1 the southern stream creeping in from the south-east1 and the northern stream stealing round ,hecla towards the south-west4 ,the track of this remarkable deflection and reunion is clearly marked out by numerous stri all over the low-grounds that slope outwards to the ,atlantic coast4 ,the till1 it need hardly be added1 affords the same kind of evidence as the sub-glacial deposits of the other islands1 and points unmistakably to a general ice-movement across ,south ,uist from the ,minch to the ,atlantic4 ,the influence which an irregular surface has in causing local deflections of an ice-flow is also well seen in ,barra1 where the stri sometimes point some #e or #aj1 and sometimes #be and even #ce north of west--these variations being entirely due to the configuration of the ground4 ,this island is extremely bare in many places1 more especially over all the region that slopes to the ,minch4 ,the ,atlantic border is somewhat better covered with soil1 as is the case with ,south ,uist and the other islands already described4 ,vatersey1 ,saundry1 ,papey1 ,miuley1 and ,bearnarey1 are all equally well glaciated2 but as they show little or no low-ground with gentle slopes1 they have preserved few traces of sub-glacial dbris4 ,in this respect they resemble the rockier and hillier parts of the large islands to the north4 ,till1 however1 is occasionally met with1 as for example on the low shores of ,vatersey ,bay1 and on the southern margin of ,miuley4 ,doubtless1 if it were carefully looked for it would be found sheltering in patches in many nooks and hollows1 protected from the grind of the ice that advanced from the south-east4 ,i saw it in several such places in the islet of ,bearnarey1 where the stri indicated an ice-flow as usual towards the north-west4 ,we have now seen that the whole of the ,long ,island has been ground1 and rubbed1 and scraped by land- or glacier-ice which has traversed the ground in a prevalent south-east and north-west direction4 ,we have seen also that this ice attained so great a thickness that it was able to overflow all the hills up to a height of #afjj feet above the sea4 ,it is needless to say that such a mass could not have been nurtured on the islands themselves4 ,they have no gathering grounds of sufficient extent1 and if they had1 the ice would not have taken the peculiar direction it did4 ,instead of flowing across the islands it would have radiated outwards from the mountain-valleys4 ,where1 then1 did the ice come from8 ,looking across the ,minch we see ,skye and the mountains of the north-west ,highlands1 and those regions1 as we know1 have also been subjected to extreme glaciation4 ,from the appearances presented by the mountains of ,ross-shire we are compelled to believe that all that region was buried in ice up to a height of not less than #cjjj feet--the ice-sheet was probably even as much as #cejj feet in thickness4 ,the evidence shows that the under portion of this vast ice-sheet flowed slowly off the country into the ,minch by way of the great sea-lochs4 ,thus we know that an enormous mass crept down ,loch ,carron and united with another great stream stealing out from the mountains of ,skye1 to flow north through the hollows of ,raasay ,sound and the ,inner ,sound into the ,minch4 ,so deep was the ice that it completely smothered the island of ,raasay 7#abgb feet high7 and overflowed all the lofty trappean table-lands of ,skye4 ,from the ,coolins1 as a centre-point1 another movement of the ice-sheet was towards the south-west1 against the islands of ,rum1 ,cannay1 and ,eigg4 ,further north similar vast masses of ice streamed out into the ,minch1 from ,loch ,torridon1 ,gairloch1 ,loch ,ewe1 and ,loch ,broom4 ,the direction of the glaciation in the north of ,skye1 which is towards north-west1 shows that the glacier-mass which overflowed that area must eventually have reached the shores of the ,long ,island4 ,in short1 there cannot be a reasonable doubt that the immense sheet of ice that streamed off the north-west ,highlands must have filled up entirely the basin of the ,minch1 and thereafter streamed across the ,outer ,hebrides4 ,but it may be objected that if the ,outer ,hebrides were overflowed by ice that streamed from the mainland across the north end of ,skye1 we ought to get many fragments of ,skye rocks and ,ross-shire rocks too in the sub-glacial dbris or till of ,lewis and ,harris1 and the north end of ,north ,uist4 ,but all such fragments are apparently wanting4 ,true1 there are bits of stone like the igneous rocks of ,skye often met with in the ,hebridean till1 but as veins or dykes of precisely the same kind of rock occur in the ,long ,island itself1 we cannot say that the stones referred to are other than native4 ,a little reflection will show us1 however1 that it is extremely improbable indeed that stones derived from ,skye and the mainland should ever have been dragged on under the ice1 and deposited amongst the till of the ,long ,island4 ,there is only one part of the whole ,outer ,hebrides where we might have anticipated that fragments from the mainland should occur2 and there1 sure enough1 they put in an appearance4 ,but before ,i attempt to explain the non-occurrence of ,skye rocks in the till of the ,outer ,hebrides1 let me show in a few words what the glaciation of the ,long ,island1 ,skye1 and the north-west ,highlands teaches us as to the general aspect presented by the ice-sheet4 ,the height reached by the surface of the ice in ,ross-shire and the ,long ,island respectively indicates of course that the main movement was from the mainland4 ,we must conceive of an immense sheet of solid ice filling up all the inequalities of the land1 obliterating the glens1 and sweeping across the hill-tops2 and not only so1 but occupying the wide basin of the ,minch to the entire exclusion of the sea1 the surface of the ice rising so high that it overtopped the whole of the ,outer ,hebrides1 and left only the tips of a few of the higher mountains uncovered4 ,the slope of the surface was persistently outwards from the mainland1 and the striation of the ,long ,island indicates clearly that the dip or inclination of that surface was towards the north-west4 ,nay1 more than this1 we are now enabled for the first time to say with some approach to certainty what was the precise angle of that inclination4 ,if we take the upper surface of the ice in ,ross-shire to have been #cjjj feet 7and it was not less71 then the slope between the mainland and the ,outer ,hebrides was only #be feet in the mile1 or about #a in #baj4 ,it is quite possible1 however1 and even probable1 that the actual height attained by the ice-sheet in the north-west ,highlands was more than #cjjj feet4 ,i think it may yet turn out to have been #cejj feet1 and if this were so it would give an inclination for the surface of the ice of about #ce feet in the mile4 ,in either case the slope was so very gentle that to the eye it would have appeared like a level plain4 ,over the surface of this plain would be scattered here and there a solitary big erratic or two1 while in other places long trains of large and small angular boulders would stream outwards4 ,all these would be derived from such mountain in ,skye and the mainland as were able to keep their heads above the level of the ice-flow2 while a few also might be dislodged by the frost and rolled down upon the glacier from the tips of the ,clisham and the ,langa in ,harris1 and ,hecla and ,beinn ,mhor in ,south ,uist4 ,every such block1 it is evident1 would be carried across the buried ,hebrides1 out into the ,atlantic in the direction indicated by the glaciation of the ,long ,island--that is1 towards the north-west4 ,but while the upper strata of the ice doubtless followed that particular course1 it is obvious that this could not be the case with the under portion of the great sheet1 the path of which would be controlled in large measure by the form of the ground over which the ice moved4 ,the upper strata that overflowed the ,outer ,hebrides1 as we have seen1 were locally deflected again and again by important obstacles1 and it is quite certain that the same would take place with the deeper portions of the ice-flow4 ,it is well known that the sea along the inner margin of the ,long ,island is very deep4 ,in many places it reaches a depth of #fjj feet1 and occasionally the sounding-lead plunges down for upwards of #gjj feet4 ,it would seem1 however1 that these great depths did not exist before the advent of the ice-sheet1 but that the bottom of the ,minch along the eastern borders of the ,long ,island was then some #bej or #cjj feet shallower than now1 the floor of the sea having since been excavated in the manner ,i shall presently describe4 ,it is quite apparent1 therefore1 that the long ridge of the ,outer ,hebrides must have offered an insuperable obstacle to the direct passage of the bottom-ice out to the ,atlantic4 ,here was a great wall of rock shooting up from the floor of the ,minch1 at a high angle1 to a height ranging in elevation from #djj feet to upwards of #cjjj feet4 ,it is simply impossible that the lower strata of the ice that occupied the bed of the ,minch could climb that precipitous barricade4 ,they were necessarily deflected1 one portion creeping to north-east and another to south-west1 but both hugging the great wall of rock all the way4 ,we see precisely the same result taking place in the bed of every stream4 ,let us stand upon an almost submerged boulder1 and note how the water is deflected to right and left1 and we shall observe at the same time that the boulder1 by obstructing the current1 forces the water downwards upon the bed of the stream1 the result being that a hollow is dug out in front4 ,now1 in a similar manner1 the ice1 squeezed and pressed against the ,hebridean ridge by the steady flow of the great current that crossed the ,minch1 necessarily acted with intense erosive force upon its bed4 ,hence in the course of time it scooped out a series of broad deep trenches along the whole inner margin of the ,long ,island1 the amount of the excavation reaching from #bjj to #cjj feet4 ,similar excavated basins occur in like positions opposite all the precipitous islands of the ,inner ,hebrides4 ,wherever1 indeed1 the ice-sheet met with any great obstruction to its flow1 there excessive erosion took place1 and a more or less deep hollow was dug out in front of the opposing cliff1 or crag1 or precipitous mountain4 ,while1 therefore1 the upper strata of the ice-sheet overflowed the ,outer ,hebrides from south-east to north-west1 the under portions of the same great ice-flow were compelled by the contour of the ground to creep away to north-east and south-west1 until they could steal round the ridge and so escape outwards to the ,atlantic4 ,this being the case1 we have a very simple and obvious explanation of the absence of ,skye rocks in the till of the ,long ,island4 ,one sees readily enough that the sub-glacial dbris dragged across the ,minch would naturally be carried away to south-west and north-east by the under-tow or deflected ice4 ,it is quite impossible that any ,skye fragments or bits of rock from the mainland could travel over the bed of the ,minch1 and then be pushed up the precipitous rock wall of the ,long ,island4 ,there is only one place in all the ,outer ,hebrides where we might expect to meet with extraneous boulders in the till1 and that is in the north of ,lewis1 where the land shelves gently into the sea1 and the great rocky ridge terminates4 ,here the under-strata of the ice would begin to steal up upon the land1 favoured by its gentle inclination1 and in that very place accordingly we meet with a deposit of till in which are found many boulders of a hard red sandstone1 and some of various porphyries which are quite alien to the ,long ,island4 ,moreover1 the till itself in that locality is much more of a clay than the usual sub-glacial dbris in other parts of ,lewis1 and contains numerous fragments of sea-shells4 ,all this is quite in keeping with the other evidence4 ,the extreme north end of ,lewis was overflowed by the under-current that crept up the bed of the ,minch1 hugging the ,hebridean ridge1 and dragging along with it a muddy mass interspersed with the shells and other marine exuvi that lay in its path1 and numerous stones1 some of which may have come from ,skye1 while others were derived from the mainland4 ,i have already said enough1 perhaps1 about the abrasion of the ,hebrides1 but ,i may add a few words upon the origin of the freshwater lakes4 ,many of these rest in complete rock-basins2 others1 again1 seem to lie partly upon solid rock and partly upon till2 while yet others appear to occupy mere shallow depressions in the surface of the till4 ,all of them thus owe their origin to the action of the ice-sheet4 ,as one might have expected1 the great majority lie along the outcrop of the gneissic strata1 which1 as a rule1 corresponds pretty closely to the flow of the ice4 ,hence the general trend of the lakes is from south-east to north-west4 ,in many cases in fashioning these rock-basins the ice has merely deepened in an irregular manner previously existing hollows1 which are now1 of course1 filled with water4 ,in not a few places1 however1 the lakes are drawn out in other directions--this being due usually to changes in the strike or outcrop of the strata4 ,for example1 over a considerable district in the south of ,lewis many lake-hollows extend from south-west to north-east1 or at right angles to the direction of the ice-flow4 ,such lakes are usually dammed up at one or both extremities by glacial dbris4 ,thus most of the features characteristic of the ,outer ,hebrides owe their origin directly or indirectly to the action of that great sheet of ice which swept over the islands during what is called the ,glacial ,period4 ,and there is no region in northern ,europe where the immensity of the abrading agent can be more vividly realised4 ,from a study of the phenomena there exhibited we for the first time obtain a definite idea of the surface-slope1 and are able to plumb the old ice-sheet1 and ascertain with some approach to accuracy its exact thickness4 ,in the deeper parts of the area1 between the mainland and the ,long ,island1 its thickness was not less than #chjj feet4 ,of course this great depth of ice could not have been derived exclusively from the snow that fell on the mountains of the north-west ,highlands4 ,doubtless the precipitation took place over its whole surface1 just as is the case in ,greenland and over the ,antarctic continent4 ,the winter cold must have been excessive1 but the precipitation necessary to sustain such a mass of ice implies great evaporation2 in other words1 the direct heat of the sun per diem in summer-time was probably considerably in excess of what it is now in these latitudes4 ,the west and south-west winds must have been laden with moisture1 the greater portion of which would necessarily fall in the form of snow4 ,we see something analogous to this taking place in the ,antarctic regions at the present day4 ,that quarter of the globe has its summer in perihelion1 and1 therefore1 must be receiving then more heat per diem than our hemisphere does in its summer season1 which1 as every one knows1 happens when the earth is furthest removed from the sun4 ,but1 notwithstanding this1 the summer of the ,antarctic continent is cold and ungenial--the presence of the great ice-sheet there cooling the air and causing most of the moisture to fall as snow4 ,paradoxical as it may seem1 therefore great summer heat is almost1 if not quite1 as necessary as excessive winter cold for the production and maintenance of a wide continental glacier4 ,,iii4 ,when we last took a peep at the ,outer ,hebrides we found those luckless islands all but obliterated under an immense sheet of ice extending from the mainland out into the ,atlantic4 ,how far west the great glacier spread itself we cannot as yet positively say2 but if the known slope of its surface between the north-west ,highlands and the ,long ,island continued1 as there is every reason to believe it would1 then it is extremely probable that the ice flowed out to the edge of the great ,scottish submarine plateau4 ,here the sudden deepening of the ,atlantic would arrest its progress and cause it to break up into icebergs4 ,in those old times1 therefore1 a steep wall of ice would extend all along the line of what is now the edge of the #ajj-;fathoms plateau4 ,from this wall large tabular masses would ever and anon break away and float off into the ,atlantic--a condition of things which is closely paralleled at present along the borders of the ice-drowned ,antarctic continent4 ,by-and-by1 however1 a great change took place1 and the big ice-sheet melted off the ,long ,island and vanished from the ,minch4 ,we read the evidence for this change of climate in certain interesting deposits which occur in considerable bulk at the northern extremity of ,lewis1 and in smaller patches in the ,eye peninsula of the same island4 ,in those districts the old sub-glacial dbris or till is covered with beds of clay and sand in which many marine exuvi are found--shells of molluscs1 entomostraca1 foraminifera1 etc4 ,they clearly prove1 then1 that after the ice-sheet had vanished ,lewis was submerged in the sea to a depth of not less than #bjj feet1 and they also prove that the temperature of the sea was much the same then as now1 for the shells all belong to species that are still living in these northern waters4 ,it is very remarkable that the marine deposits in question seem to occur nowhere else in any part of the ,long ,island4 ,we cannot believe that the submergence was restricted to the very limited areas where the shell-beds are met with3 it must1 on the contrary1 have affected a very large portion1 if not the whole1 of the ,outer ,hebrides4 ,why1 then1 do not we meet with shelly sands and clays1 with raised beaches and other relics of the former occupation of these islands by the sea1 covering wide areas in the low-grounds8 ,how can we explain the absence of such relics from all those districts which1 being much under the level of #bjj feet1 must necessarily have at one time formed part of the sea-floor8 ,the explanation is not difficult to discover4 ,resting upon the surface of the shell-beds at ,ness and ,garabost we find an upper or overlying accumulation of sub-glacial dbris or till4 ,at ,ness this upper till closely resembles1 in general appearance1 the lower deposit that rests directly upon the rocks4 ,it is a pell-mell accumulation of silty clay1 crammed with glaciated stones1 amongst which are many fragments of red sandstone and some extra-,hebridean rocks1 and interspersed through it occur also broken fragments of sea-shells4 ,the marine deposits lying below are usually much confused and contorted1 and here and there they are even violently commingled with the upper till4 ,they show1 generally1 a most irregular surface under that accumulation1 and are evidently only the wreck of what they must at one time have been4 ,now the presence of this upper till proves beyond doubt that the intense arctic conditions of climate once more supervened4 ,a big ice-sheet again filled up the basin of the ,minch and flowed over the ,long ,island--its under-tow creeping along the inner margin of the lofty rock-barrier as before1 and eventually stealing over the low-ground at the ,butt1 where its bottom-moraine or till was dragged over the marine deposits1 and confusedly commingled with them4 ,the upper strata of the ice that streamed across the islands renewed the work of abrasion1 and succeeded in scraping away all traces of the late occupation by the sea4 ,if any such now exist they must lie buried under the till that cloaks the low-ground on the western margins of the islands4 ,hence it is that we find not a vestige of shelly beds in any part of the ,long ,island which was exposed to the full brunt of the ice-flow4 ,at ,garabost they have been ploughed through in the most wonderful manner1 and only little patches remain4 ,at ,ness1 however1 they are more continuous4 ,this is owing to the circumstance that the ground in that neighbourhood is low-lying and offered no obstacle to the passage of the ice out to sea4 ,hence the shell-beds were not subjected to such excessive erosion as overtook them along the whole eastern border of the ,long ,island4 ,eventually1 however1 this later advance of the ice-sheet ceased4 ,the climate grew less arctic1 and the great glacier began to melt away1 until the time came that its upper strata ceased to overflow the islands4 ,they then passed away to north and south1 along the hollow now occupied by the ,minch1 following the same path as the bottom-ice4 ,considerable snow-fields1 however1 still covered the ,outer ,hebrides1 and large local glaciers occupied all the mountain-valleys1 and1 descending to low levels1 piled up their terminal moraines4 ,some of these local glaciers appear to have gone right out into the ,minch1 as in ,south ,uist1 and may have coalesced with the great glacier that still filled that basin4 ,it was during this condition of things that most of the great perched blocks that are scattered so profusely over the islands began to be dropt into their present positions4 ,during the climax of glacial cold1 when the upper strata of the ice-sheet streamed across the ,hebrides1 large fragments of rock would certainly be wrenched off and carried on underneath the ice2 but as only a few of the ,hebridean mountain-tops were then exposed1 there would be a general absence of such enormous erratics as are detached by frost and rolled down upon the surface of a glacier1 and any such superficially-borne erratics would be transported1 of course1 far beyond the ,long ,island into the ,atlantic4 ,when the ice had ceased to overflow the islands1 boulders derived from ,skye and the mainland would no longer be carried so directly out to the ,atlantic1 but would travel thither by the more circuitous route1 which the now diminished ice-sheet was compelled to follow4 ,as the snow and ice melted off the ,hebrides1 the rocks would begin to be exposed to the action of intense frost1 and many fragments1 becoming dislodged and falling upon nv1 small local ice-sheets1 and glaciers1 would be stranded on hill-slopes and sprinkled over the low-grounds1 along with much broken dbris and rock-rubbish4 ,eventually all the lower-grounds would be deserted by the ice1 glaciers would die out of the less elevated valleys1 and linger in only a few of the glens that drain the higher mountain-masses4 ,such local glaciers have flowed often at right angles to the direction followed by the great ice-sheet4 ,thus1 the ice-markings in the glens that come down from the ,forest of ,harris to ,west ,loch ,tarbert1 run from north to south1 while the trend of the older glaciation on the intervening high-grounds is from south-east to north-west4 ,the morainic rubbish and erratics of this latest phase in the glacial history of the ,long ,island may be traced down almost to the water's edge1 showing plainly that there has been no great submergence of that region since the disappearance of glacial conditions4 ,this is somewhat remarkable1 because along the shores of central and southern ,scotland we have indisputable evidence to show that the land was drowned to the depth of at least fifty feet in post-glacial times4 ,in the ,outer ,hebrides1 however1 there are no traces of any post-glacial submergence exceeding a dozen feet or so2 that is to say1 there is no proof that the ,outer ,hebrides have been of much less extent than they are now4 ,on the contrary1 we have many reasons for believing that they were within comparatively recent times of considerably larger size1 and were even in all probability united to the mainland4 ,the abundance of large trees in the peat-mosses1 and the fact that these ancient peat-covered forests extend out to sea1 are alone sufficient to convince one that the ,outer ,hebrides have been much reduced in area since the close of the glacial period4 ,these now bleak islands at one time supported extensive forests1 although nowadays a tree will hardly grow unless it be carefully looked after4 ,that old forest period coincided in all probability with the latest continental condition of the ,british ,islands--when the broad plains which are now drowned under the ,german ,ocean formed part of a great forest-land1 that included all the ,british ,islands1 and extended west for some distance into tracts over which now roll the waves of the ,atlantic4 ,the palmy days of the great ,british forests1 however1 passed away when the ,german ,ocean came into existence4 ,the climatic conditions were then not so favourable for the growth of large trees2 and in the uplands of our country1 and what are now our maritime districts1 the forests decayed1 and were gradually overgrown by and buried under peat-mosses4 ,the submergence of the land continued after that1 until central and southern ,scotland were reduced to a considerably smaller size than now1 and then by-and-by the process was reversed1 and the sea once more retreated1 leaving behind it a number of old raised beaches to mark the levels at which it formerly stood4 ,the greatest submergence that overtook central and southern ,scotland in times posterior to the latest continental condition of ,britain did not exceed fifty feet1 or thereabout2 and the extreme limits reached by the sea in the period that supervened between the close of the glacial epoch and the age of forests was not more than one hundred feet4 ,the ,outer ,hebrides1 however1 were certainly not smaller in post-glacial times than they are now1 and we have no evidence to show that after the age of forests had passed away the sea rose higher than a dozen feet or so above its present level4 ,now there are only two ways in which all this can be accounted for4 ,either the ,hebrides remained stationary1 or stood at a level higher than now1 while the central and southern parts of ,scotland were being submerged2 or else there has been a very recent depression within the ,hebridean area1 which has carried down below the sea all traces of late glacial and post-glacial raised beaches4 ,all we know for certain is1 that the only raised beaches in the ,long ,island are met with in low maritime regions at only a few feet above the present high-water mark4 ,my own impression is that the whole district has been submerged within comparatively recent times2 for if the present coast-line had endured since the close of the glacial period1 or even since the last continental condition of ,britain1 ,i should have expected the sea to have done more than it has in the way of excavation and erosion4 ,in a former article ,i have spoken of the sand-dunes and sandy flats of the west coast of the ,long ,island4 ,these receive their greatest development in ,north ,uist1 ,benbecula1 and ,south ,uist4 ,along the whole western margin of these islands stretch wide shoals and banks of yellow sand and silt1 and similar shoals and banks cover the bed of the shallow sounds or channels4 ,in the middle of the ,sound of ,harris one may often touch the bottom with an oar1 and even run one's boat aground4 ,it is the same in the ,sound of ,barra1 while1 as ,i have already mentioned1 one may walk at low-water from ,benbecula into the adjacent islands of ,north and ,south ,uist4 ,where does all this sand come from8 ,certainly not from the degradation of the islands by the sea1 for the sounds appear to be silting up1 and the general appearance of the sandy flats along the west coast indicates that the land is upon the whole gaining rather than losing4 ,i have no doubt at all that this sand and silt are merely the old sub-glacial dbris which the ice-sheet spread over the low shelving plateau that extends west under the ,atlantic to the #ajj-;fathoms line4 ,that plateau must have been thickly covered with till1 and with heaps and sheets of gravel and sand and silt1 and it is these deposits1 sifted and winnowed by the sea1 which the tides and waves sweep up along the ,atlantic margin of the islands4 ,there are many other points of interest to that ,i might touch upon1 but ,i have said enough perhaps to indicate to any intelligent observer the kind of country he may be led to expect in the ,long ,island4 ,of course the history of the glacial period is very well illustrated in many parts of the mainland1 which are much easier of access than the ,outer ,hebrides4 ,but these islands contain1 at least1 one bit of evidence which does not occur anywhere else in ,britain4 ,in them we obtain1 for the first time1 data for measuring the actual slope of the ice-sheet4 ,it does not follow1 however1 that the inclination of the surface towards the ,atlantic was the same all over the area covered by the ice-sheet4 ,the slope of the sheet that flowed east into the basin of the ,german ,ocean1 for example1 may have been1 and probably was1 less than that of the ,hebridean ice-flow4 ,but apart altogether from this particular point1 ,i think there is no part of the ,british ,islands where the evidence for the former action of a great ice-sheet is more abundant and more easily read1 or where one may realise with such vividness the conditions that obtained during that period of extraordinary climatic vicissitudes1 which geologists call the ,glacial ,epoch4 ,leaving these old arctic scenes1 and coming down to the actual present1 no one1 ,i think1 can wander much about the ,outer ,hebrides without pondering over the fate of the islanders themselves4 ,many writers have asserted that the ,celt of these rather out-of-the-way places is a lazy1 worthless creature1 whom we ,saxons should do our best to weed out4 ,one cannot help feeling that this assertion is unfair and cruel4 ,the fact is1 we judge him by a wrong standard4 ,he is by nature and long-inherited habits a fisherman1 and has been wont to cultivate only so much land as should suffice for the sustenance of himself and those immediately dependent upon him4 ,in old times he was often enough called upon to fight1 wrongly or rightly1 and thus acquired that proud bearing which it has taken so many long years of misery to crush out4 ,he is1 as a rule1 totally unfit for the close confinement and hard work which are the lot of the great mass of our mechanics--does not see the beauty of that1 and has rather a kind of contempt for the monotonous drudgery of large manufacturing towns4 ,one of the few situations in town that he cares to fill is that of police-constable4 ,give him a life in the open air1 however trying it may be1 and he will be quite content if he can make enough to feed himself and family4 ,if the fishing chance to be very profitable he does not1 as a rule1 think of saving the surplus he has made1 but looks forward rather to a spell of idleness1 when he can smoke his pipe and talk interminable long talks with his neighbours4 ,no doubt this1 judged by our own standard1 is all very shocking4 ,why doesn't he put his money in the savings-bank1 and by-and-by die and leave it to those who come after him8 ,simply because he is a ,celt1 and not a ,saxon4 ,of course one knows how it will all end4 ,ere long the unadulterated ,celt will be driven or improved out of these islands1 and will retire to other lands1 where1 mingling and intermarrying with ,teutons1 he will eventually disappear1 but not without leavening the races amongst which he is destined to vanish4 ,and who will take his place in the ,long ,island8 ,probably a few farmers1 a few shepherds1 and a sprinkling of gamekeepers2 and it is just possible that a few fishermen also may be allowed to settle down here and there upon the coast4 ,one may see the process going on at present4 ,large tracts that once supported many villages are now quite depopulated4 ,the time will come when somebody in ,parliament will move for the reduction of the ,civil ,service estimates by the amount of the sheriff-substitute's salary1 and when the jail at ,lochmaddy will have nothing higher in the scale of being to imprison than some refractory ram4 ,one may be pardoned for wishing that he could foretell for the islands another fate than this4 ,it is sad to think that a fine race of people is thus surely passing away from amongst us1 for1 despite all that can be urged against them1 they are what ,i say4 ,the fishermen of ,lewis and ,barra are bold1 stalwart fellows1 whom it would be difficult to peer amongst any similar class of men on the mainland4 ,and all through the island one meets with equally excellent specimens of our kind4 ,many a brave soldier who fought our battles in the great ,french wars hailed from these outer islands4 ,pity it is that no feasible plan to prevent the threatened scattering of the race has yet been brought forward4 ,some day we may regret this1 and come to think that though mutton and wool in the ,long ,island are desirable1 yet islanders would have been better4 ,postscript4--,on pages #aec4d ,i have described the second general ice-sheet that overflowed the ,outer ,hebrides as having eventually become resolved into a series of local ice-sheets and glaciers4 ,subsequent research1 however1 has since led me to believe that the district ice-sheets and local glaciers referred to were not the direct descendants of the last great ice-sheet4 ,they appear to have come into existence long after that ice-sheet had entirely disappeared4 ,see ,article ,x4 ,,vi4 ,the ,ice ,age in ,europe and ,north ,america4,k ,k ,address to the ,geological ,society of ,edinburgh1 #ahhd4 ,in casting about for a subject upon which to address you this evening1 ,i thought ,i could hardly do better than give you the result of a comparison which ,i have recently been able to make between the glacial phenomena of ,europe and ,north ,america4 ,the subject of glaciation seems to be now somewhat worn2 but ,i gather from the fact that writers can still be found who see in our superficial deposits strong evidence of the ,deluge1 that a short outline of what we really do know may not be unacceptable4 ,in the short time at our disposal1 it is obvious that ,i cannot enter into much detail1 and that many interesting questions must remain untouched4 ,it will be as well1 therefore1 that ,i should at the outset define the limits of the present inquiry1 and state clearly what are the chief points to which ,i wish to direct your attention4 ,my main object1 then1 will be to bring into prominence such evidence as seems to betoken in a special manner the uniformity of conditions that obtained in the northern hemisphere during the ,ice ,age4 ,in other words1 ,i shall confine myself to a description of certain characteristic and representative phenomena which are common to ,europe and ,north ,america1 with the view of showing that the physical conditions of the glacial period were practically the same in both continents4 ,the phenomena which might be considered under this head embrace nearly all the facts with which glacialists are familiar1 but ,i purpose restricting myself to three questions only1 viz43-- #ast4 ,the extent of glaciation4 #bnd4 ,changes of climate during the ,ice ,age4 #crd4 ,the results of fluvio-glacial action4 ,the consideration of these questions1 even if it were exhaustive 7which it cannot be on this occasion71 would still leave the general subject very incomplete1 for we must forego the discussion of all such interesting topics as the connection between glaciation and submergence1 the formation of rock-basins1 and the origin of the geographical distribution of our faunas and floras4 ,confining my inquiry within the limits just specified1 ,i shall begin by sketching broadly the general results obtained by glacialists in ,europe1 and thereafter ,i shall proceed to give an outline of the corresponding conclusions arrived at by ,american observers4 ,i4 ,the ,extent of ,glaciation in ,europe4 ,to what extent1 then1 let us ask1 has ,europe been glaciated8 ,what areas have been covered with perennial snow and ice8 ,owing to the fulness and clearness of the evidence1 we are able to give a very definite answer to this question4 ,it is hardly too much to say that we are as well acquainted with the distribution of glacier-ice in ,europe during the ,ice ,age as we are with that of existing snow-fields and glaciers4 ,the nature of the evidence upon which our knowledge is based is doubtless familiar to many whom ,i have the pleasure of now addressing1 but for the sake of those who have not such familiarity with the subject ,i may be allowed to indicate very briefly its general character4 ,a rock-surface over which ice has flowed for any considerable time exhibits either an abraded1 worn1 and smoothed appearance1 or the rocks are disrupted and broken1 and larger or smaller fragments are found to have been removed and carried forward in the direction followed by the ice4 ,now1 ice-worn and shattered rock-surfaces of this description1 such as can be seen underneath existing glaciers1 occur more or less abundantly over vast regions in ,europe4 ,they are met with from the ,north ,cape south as far as ,leipzig1 and from the ,outer ,hebrides east to the valley of the ,petchora and the foot-slopes of the ,ural ,mountains4 ,nor are they confined to northern ,europe4 ,they appear again and again in ,france and ,spain and ,italy1 and in the low-grounds of middle ,europe1 where they occupy positions now far removed from the influence of glacial action4 ,such ice-worn and disrupted rock-surfaces not only prove that glacier-ice formerly covered large portions of our ,continent1 but they also indicate for us the directions in which that enveloping ice moved4 ,the smoother surfaces in question are very frequently marked with coarse and fine parallel scratches and grooves of precisely the same nature and origin as the scratches and grooves which characterise the rocky bed of a modern glacier4 ,and these markings1 having been produced by the sand1 grit1 and stones which are pushed and dragged over the rocks by flowing ice1 necessarily discover for us the path of glacial movement4 ,but all rocks subjected to glacial action are not necessarily smoothed and polished4 ,sometimes1 owing to structural peculiarities1 and for various other reasons1 rocks cannot resist the pressure of the ice1 but are crushed and broken1 and the resulting fragments are rolled and dragged forward in the direction of ice-flow4 ,in this manner the path of a glacier becomes strewed with dbris which has from time to time been forced from its rocky bed4 ,there is really no mystery1 therefore in tracking the spoor of extinct glaciers2 for we have two sets of facts to aid us1 either of which might suffice to indicate the extent and direction of glaciation4 ,consider1 however1 for a moment1 what one observes in connection with rock-striation4 ,we have1 in the first place1 the rounding and smoothing1 and the parallel ruts and stri4 ,not only so1 but we frequently find that one side of prominent projecting knolls and hills is more highly worn and abraded than the other4 ,often1 indeed1 one side may show no trace whatsoever of abrasion4 ,here1 again1 we have clear evidence of the direction of ice-flow4 ,who can doubt that the worn and abraded rocks look towards the point whence the ice came1 and that the non-glaciated rocks in the rear have been sheltered by the rocks in front8 ,it is for this reason that in the mountainous regions of northern ,europe the striated and smoothed rock-surfaces invariably look up the valleys1 while the broken and unworn rock-ledges face in the opposite direction4 ,once more1 note the manner in which the sub-glacial rock-rubbish1 consisting of clay1 sand1 grit1 stones1 and boulders1 has been amassed4 ,in places where the ice must have moved more or less rapidly1 as on considerable slopes1 no accumulation took place1 while in the rear of projecting crags and knobs of rock1 sub-glacial materials often gathered deeply4 ,again1 over low-lying tracts1 where the motion of the ice would necessarily be retarded1 clay1 sand1 and stones tended to collect4 ,and this particularly appears to have been the case in those regions where the slow-creeping and gradually thinning ice-sheet approached its terminal line4 ,hence it is that we encounter such thick and wide-spread sheets of sub-glacial detritus upon the undulating low-grounds and plains of southern ,sweden1 ,denmark1 ,schleswig-,holstein1 ,holland1 northern ,germany1 ,poland1 and ,russia4 ,the sub-glacial dbris to which ,i specially refer is known as ,till or ,boulder-clay in this country1 as ,krosstenslera in ,sweden1 as ,geschiebelehm or ,geschiebemergel in ,germany1 and as ,grundmorne or ,moraine profonde in ,switzerland4 ,its general characters are too well known to require more than the briefest summary4 ,in general this peculiar accumulation is an unstratified clay1 containing1 scattered higgledy-piggledy through it1 stones and boulders of all shapes and sizes4 ,many of these rock-fragments are smoothed and striated1 and even the smallest particles1 when viewed under the microscope1 often show delicate scratches4 ,frequently1 too1 the clay is excessively hard and tough1 and in many places it shows a kind of pseudo-lamination1 which is generally more or less crumpled1 and often highly involved4 ,these appearances prove that the clay has not only been subjected to intense pressure1 but has actually been rolled over upon itself4 ,i need only refer to the plentiful occurrence of slickensides in such clays--the joints by which the clay is often traversed showing such polishing clearly on their faces4 ,these1 and many other facts which time forbids me to mention1 have received an explanation which has now been generally adopted by ,european glacialists4 ,the boulder-clay or till is considered by them to represent the ground- or bottom-moraine of glacier-ice4 ,there used to be a notion prevalent amongst geologists in our country that this clay was almost peculiar to these islands4 ,it occurs1 however1 in most countries of ,europe4 ,vast regions in the north are more or less continuously covered by it1 and we meet with it abundantly also upon the low-grounds of ,switzerland1 from which it may be followed far down the great valley of the ,rhone into the sunny plains of ,france4 ,the lower valleys of the ,pyrenees and other ,spanish ranges show it well1 and it is conspicuous likewise in northern ,italy1 especially over the low tracts at the mouths of the great lake-valleys4 ,in all those places one can see boulder-clay of as pronounced a character as any to be met with in ,scotland4 ,danish1 ,dutch1 ,german1 and ,russian geologists have of late years devoted much attention to the study of this clay1 which is so remarkably developed in their respective countries4 ,it has been long well known that a large proportion of the stones and boulders contained in the till are of northern derivation1 but it is only of recent years that we have ascertained the particular routes by which those wanderers or erratics have travelled4 ,the rock-fragments in question have been tracked back1 as it were1 to their parent masses1 and thus1 partly in this way1 and partly by the evidence of ice-worn surfaces1 we have been enabled to follow the spoor of the great northern ice-sheet in a most satisfactory manner4 ,let one or two examples suffice4 ,boulders derived from ,lapland and ,finland occur in the till at ,st4 ,petersburg1 and have been traced south-east to ,moscow4 ,again1 fragments carried from ,gottland1 in the ,baltic1 are met with in the boulder-clay of east ,prussia1 and have been followed south to beyond ,berlin4 ,in like manner boulders of well-known ,scanian rocks appear in the boulder-clay of ,leipzig4 ,so also ,swedish and ,norwegian rock-fragments are seen in the boulder-clay of ,denmark1 ,hanover1 and ,holland4 ,very wide areas in northern ,germany are covered with an almost continuous sheet of glacial detritus1 so that it is only occasionally that the underlying rocks crop out at the surface4 ,striated rock-surfaces are therefore by no means so commonly exposed as in regions like the ,lowlands of ,scotland4 ,they are not wanting1 however1 and their evidence is very striking4 ,thus1 in the neighbourhood of ,leipzig and ,dresden1 we find glacial stri impressed upon certain highly-abraded and ice-worn hillocks of porphyry1 the stri being the work of ice which flowed into ,saxony from the north4 ,similar stri21 having a general southerly trend1 occur at ,rdersdorf1 near ,berlin1 at ,gommern1 near ,magdeburg1 at ,velpke in ,brunswick1 at ,osnabrck in ,hanover1 and at other places4 ,again1 we encounter remarkable evidence of the powerful pressure exerted by the ice in the displacement and removal of huge blocks of strata4 ,in ,saxony1 for example1 the ,tertiary strata are turned up1 pushed out of place1 and involved in boulder-clay to such an extent that the brown coals have often been mined for in this strange position4 ,witness also the extensive displacements and dislocations of the ,cretaceous formation in the ,danish islands of the ,baltic4 ,so great are the contortions and displacements of the ,chalk in ,moen1 that these disturbances were formerly attributed to subterranean action4 ,along the north-east coast of that island1 cliffs #djj feet in height exhibit the ,cretaceous beds thrown upon end1 twisted1 bent1 and even inverted1 boulder-clay being squeezed into and between the disjointed and ruptured rock-masses4 ,from a study of these and similar phenomena1 it has been demonstrated that during the climax of the ,ice ,age a very large part of northern ,europe was buried under a thick covering of glacier-ice4 ,and it has been conclusively shown that this ice-sheet streamed outwards in all directions from the high-grounds of ,scandinavia1 for which reason it is often spoken of as the ,scandinavian ice-sheet4 ,but as it was fed1 not from the snow-fields of ,scandinavia alone1 but from the precipitation of snow over its whole surface1 it is better1 ,i think1 to speak of it as the northern ice-sheet4 ,in the extreme north of ,scandinavia the ice flowed northward into the ,arctic ,ocean1 while south of the dominant watershed of ,lapland and ,sweden its course in those high latitudes was east and south-east4 ,it filled up the depressions of the ,white ,sea1 the ,gulf of ,bothnia1 and the ,baltic1 extending east to the valley of the ,petchora and the base of the ,ural ,mountains1 and south-east to ,kazan1 some #bjj miles east of ,nijnii-,novgorod4 ,from this point its terminal front trended a little west of south1 until it reached the fiftieth parallel of latitude4 ,undulating a few miles south and north of this parallel1 it swept directly west through ,russia into ,galicia1 till it touched the foot-hills of the ,carpathian range4 ,after this we follow it along the northern base of the ,riesen ,gebirge1 the ,erz ,gebirge1 and the ,harz1 and thence westward through ,hanover1 and into the ,low ,countries1 as far south at least as the mouth of the ,rhine4 ,throughout the vast regions lying west and north of this terminal line1 the track followed by the ice has been well ascertained4 ,it was east and south-east in ,russia1 southerly in east ,prussia1 south-westerly in ,denmark1 ,hanover1 and ,holland4 ,the action of a mass of glacier-ice1 reaching a thickness of several thousand feet1 must necessarily have resulted in extensive erosion of the rocks over which it passed4 ,everywhere1 therefore1 throughout the vast area just indicated1 we meet with evidence of severe erosion4 ,but1 as one should expect1 such erosion is most marked in the hilly regions--in those areas where steep slopes induced more rapid motion of the ice1 and where projecting crags and hills opposed the advance of the eroding agent4 ,all such prominent obstructions were energetically assailed--abraded1 rounded1 worn1 and smoothed1 or crushed1 shattered1 dislocated1 and displaced4 ,the high-grounds of ,scandinavia and ,finland1 formed for the most part of tough1 crystalline rocks1 or of more or less durable strata1 show everywhere roches moutonnes--smoothed and rounded rocks--while innumerable rock-basins have been scooped out in front of prominent crags and hills4 ,in ,denmark and other countries1 where less durable rocks prevail1 the strata have often been broken and disrupted1 and pushed out of place4 ,but as regions formed of such rocks are generally gently-undulating1 and seldom show abrupt crags and hills1 they oppose few obstructions to the advance of an ice-sheet4 ,when the northern ice-sheet flowed into ,russia and ,germany1 it crept over a low-lying and1 for the most part1 gently-undulating surface2 and although here and there the form of the ground favoured glacial erosion and disruption1 and extensive displacements of rock-masses took place1 yet1 upon the whole the low-lying regions referred to became areas of accumulation4 ,the sub-glacial detritus--ground out or wrenched away from the rough ,scandinavian plateau and the uplands of ,finland--was dragged on underneath the ice1 and spread over the great plains lying to the south-east and south1 as the gradually attenuated ice-sheet crawled to its terminal line4 ,my friend ,dr4 ,amund ,helland1 the well-known ,norwegian geologist1 has made an estimate of the amount of rock-dbris derived from ,scandinavia and ,finland which lies scattered over the low-grounds of northern ,europe4 ,according to him1 the area in ,denmark1 ,holland1 ,germany1 and ,russia 7exclusive of ,finland71 over which northern detritus is scattered1 contains about #b1ajj1jjj square kilometres1 and the average thickness of the deposits is about #aej feet1 of which1 however1 only two-thirds1 or #ajj feet1 are of northern origin1 the remaining third consisting of local materials4 ,taking1 then1 #ajj feet as fairly representing the average thickness of the rock-rubbish derived from ,finland and ,scandinavia1 the area of which is given as #hjj1jjj square kilometres1 there is enough of this material to raise the general surface of those lands by #bee feet4 ,the same amount of material would suffice to fill up all the numerous lakes of ,finland and ,sweden sixteen or seventeen times over4 ,or1 if tumbled into the ,baltic1 it would fill the basin of that sea one and a half times4 ,in short1 enough northern rock-dbris lies upon the low-grounds of northern ,europe1 which1 were it restored to the countries from which it has been taken1 would obliterate all the lake-hollows of ,finland and ,sweden1 raise the level of those lands by #hj feet1 and fill up the entire basin of the ,baltic1 with all its bays4 ,and yet this estimate leaves out of account all the material which the ice-sheet carried away from ,norway and the ,british ,islands4 ,of the glaciation of our own land ,i need say very little4 ,the configuration of our country necessarily made it a centre of dispersion during the ,ice ,age1 and the ice which covered ,ireland1 ,scotland1 and the major portion of ,england radiated outwards from the dominant elevations of the land4 ,but as the ice creeping outwards from those centres became confluent1 the directions which it followed were often considerably modified1 especially upon the low-grounds4 ,we know that the ,british ice-sheet not only covered the land up to near the tops of our higher mountains1 but filled up all our seas and extended into the ,atlantic beyond the coasts of ,ireland and the ,outer ,hebrides--these latter islands having been glaciated from the east by the ice that flowed outwards from the mainland4 ,another point upon which we are now well assured is the fact that the ,british and ,scandinavian ice-sheets coalesced1 so that the basin of the ,north ,sea completely brimmed over with glacier-ice4 ,finally1 then1 in contemplating the physical conditions that obtained in northern ,europe at the climax of the ,ice ,age1 we have to picture to ourselves the almost total obliteration under a vast ice-sheet of all the land-features of the ,british ,islands1 ,scandinavia1 and ,finland1 and the adjacent low-lying tracts of ,denmark1 ,holland1 ,germany1 ,poland1 and ,russia4 ,if at that distant date a prehistoric man could have stood on the summit of ,snaehatten1 he would have seen an apparently interminable plain of snow and ice1 bounded only by the visible horizon4 ,could he have followed the plain southwards in hopes of escaping from it1 he would have descended its gently-sloping surface by imperceptible gradations for a distance of #gjj miles1 before he reached its termination at the foot of the mountains of middle ,germany4 ,or1 could he have set out upon an easterly course1 he would have crossed the ,gulf of ,bothnia1 buried several thousand feet beneath him1 and touched the foot-slopes of the ,ural ,mountains before he gained the terminal front of the ice-cap1 a distance of #afjj miles4 ,on the other hand1 had he walked south-west in the direction of ,ireland1 he would have traversed the area of the ,north ,sea at a height of several thousand feet above its bed1 and1 crossing the ,british area1 would only have reached the ice-front at a point some #ej miles beyond the coast of ,ireland4 ,here he would have seen the ice-sheet presenting a steep face to the assaults of the ,atlantic1 and breaking away in massive tabular bergs1 like those which are calved by the ice-cap of the ,antarctic regions4 ,i must now pass rapidly in review the facts relating to the glaciation of the mountainous regions which lay outside of the area covered by the northern ice-sheet4 ,the glaciers of the ,alps of ,switzerland1 about which so much has been written1 and the study of which first gave ,venetz1 ,charpentier1 and ,agassiz the clue to the meaning of striated rocks1 boulder-clay1 and erratics1 are1 as is well known1 the puny descendants of former gigantic ice-flows4 ,at the culmination of the ,ice ,age all the mountain-valleys of ,switzerland and northern ,italy were choked with glaciers that streamed out upon the low-grounds4 ,along the northern slopes of the ,alps1 as in ,bavaria and ,wrtemberg1 these glaciers coalesced to form a considerable ice-sheet1 and so likewise did the glaciers that descended from ,switzerland1 ,savoy1 and ,dauphiny1 into the great valley of the ,rhone4 ,even in north ,italy the same was the case with the glaciers that occupied the valleys in which now lie ,lakes ,orta1 ,maggiore1 ,varese1 ,lugano1 and ,como--the united ice-flows of those valleys forming a glacier which deployed upon the plains of the ,po1 with a frontage of not less than #dj miles4 ,to the north of the ,alps1 the ,vosges ,mountains and the ,black ,forest1 the ,harz1 the ,erz ,gebirge1 the ,riesen ,gebirge1 and the ,bhmer-,wald--all had their perennial ice and glaciers1 although none of those elevated tracts now reaches the snow-line4 ,it was the same with the ,carpathians and the ,urals1 amongst which we meet with relics of much larger ice-streams than any that now exist in the ,alps4 ,considerably further south were the glaciers of the ,despoto ,dagh of ,roumelia4 ,great glaciers also in former times descended from the ,caucasus1 and in many hilly regions of ,asia ,minor indubitable traces of similar large ice-flows have been detected4 ,the high-grounds of central ,france1 and the mountains of ,beaujolais and ,lyonnais supported considerable glaciers1 while from the ,pyrenees numerous glaciers of the first class flowed out upon the low-grounds of ,france1 and considerable ice-streams occupied the mountain-valleys on the ,spanish side4 ,other ,peninsular chains--the ,serra da ,estrella1 the ,sierra ,guadarama1 and the ,sierra ,nevada--had likewise their snow-fields and ice-streams4 ,the same was the case with the ,apennines and the ,apuan ,alps of ,italy1 the traces of former glacial action being conspicuous over a considerable part of ,tuscany4 ,even in ,corsica we encounter the same evidence of glaciation--striated rock-surfaces and moraines--which point to the former descent of considerable glaciers from ,monte ,rotondo4 ,but rock-stri and moraines are not the only proofs of former cold and humid conditions having prevailed over middle and southern ,europe at the climax of the glacial period4 ,the limestone-breccias of ,gibraltar have been described by ,professor ,ramsay and myself1 and we have shown that these could only have been formed under the influence of excessive frost and melting snows4 ,the limestone of the ,rock has been broken up along the ridge1 and its fragments showered down the slopes1 at a time when these were more or less thickly covered with snow4 ,resting upon and imbedded in this snow1 the rock-rubbish would be carried downward and outward during the gradual melting that took place in summer4 ,and in this way immense accumulations of dbris were borne forwards over the low-grounds that extended from the base of the ,rock into regions which are now partially submerged4 ,breccias which have probably had a similar origin occur also in ,corsica1 ,malta1 and ,cyprus1 and doubtless they will yet be recognised in many other places4 ,again1 over wide areas in northern ,france and the south of ,england1 we meet with extensive sheets of earthy clay and rock-rubbish1 which have certainly been heaped up under very different conditions of climate than obtain now4 ,this stony earth has evidently travelled down the gentle slopes of the land1 under the influence of frost and melting snow1 in much the same way as ice-driven rock-rubbish and soil move slowly down the slopes of such dreary regions as ,patagonia and certain low-lying tracts within the ,arctic ,circle4 ,,ii4 ,changes of ,climate in ,europe during the ,ice ,age4 ,we come next to the very interesting question of alternations of climate during the ,ice ,age4 ,the evidence under this head has accumulated to such an extent within recent years as to convince most students of ,pleistocene geology that very extensive changes of climate characterised the glacial period4 ,how many such changes took place we are not yet in a position to say1 but we know that the intensely arctic condition of things which has just been described was interrupted more than once by what have been termed interglacial epochs1 during which a mild and genial climate prevailed over middle and northern ,europe4 ,for some time it was believed that such interglacial epochs had only a local significance1 that they bespoke mere transitory retreats of the ice-fields1 such as are known to have taken place within historical times in the glacier-valleys of the ,alps4 ,but increased observation and reflection have shown that this explanation of the phenomena of interglacial beds will not suffice4 ,it is impossible to enter here upon details1 but ,i may briefly state that the evidence in question is two-fold4 ,first1 we have the stratigraphical evidence4 ,we have ascertained the existence1 over wide areas in this and other glaciated countries1 of several successive sheets of boulder-clay1 which are often separated from each other by fossiliferous aqueous strata4 ,it has been demonstrated that each of these sheets of sub-glacial detritus is the accumulation of a separate and distinct ice-flow4 ,second1 we have the evidence of fossil organic remains4 ,we find1 for example1 that the flora which covered the low-grounds of middle and temperate ,europe during a certain stage of the glacial or ,pleistocene period1 consisted of plants which are now restricted to the tops of our mountains and to northern ,scandinavia4 ,the characteristic fauna associated with that flora embraced the reindeer1 glutton1 mammoth1 woolly rhinoceros1 ,arctic fox lemming1 chamois1 and so forth4 ,we know1 indeed1 that man hunted the reindeer and the mammoth in the south of ,france4 ,similar testimony to the coldness and humidity of the climate is borne by the land- and freshwater shells which occur in certain ,pleistocene deposits in ,italy1 ,corsica1 southern ,france1 ,switzerland1 ,germany1 etc4 ,that this flora and fauna were contemporaneous with the great glaciation of our ,continent has been as well ascertained as the fact of the ,roman occupation of ,britain4 ,but if the evidence of organic remains strongly confirms and supports that supplied by the distribution of glacial deposits in ,europe1 no less forcibly does it corroborate the physical evidence as to the former existence of a warm and genial interglacial climate4 ,during interglacial times a most abundant mammalian fauna roamed over all temperate ,europe--a fauna comprising such animals as ,irish deer1 urus1 bison1 horse1 stag1 saiga1 brown bear1 grisly bear1 several species of elephant1 rhinoceros1 and hippopotamus1 hyna1 lion1 leopard1 etc4 ,a like tale of genial conditions is told by the land- and freshwater shells1 which occur in some of the ,pleistocene deposits of ,england1 ,france1 ,belgium1 ,germany1 ,switzerland1 and ,italy4 ,the testimony of the associated flora is just as striking4 ,how genial and equable must have been the climate which permitted plants like the ,canary laurel1 the ,judas-tree1 the fig-tree1 and others to flourish side by side in the north of ,france1 with such forms as the hazel1 willow1 ash1 and sycamore6 ,the most noteworthy additions to our knowledge of interglacial conditions which have recently been made are the results obtained by ,m4 ,gaudry in the valley of the ,seine1 and by ,dr4 ,penck in ,bavarian ,tyrol1 the latter of whom has shown that there have been at least three great advances of the ,alpine glaciers1 separated by long-continued mild conditions1 during which the glaciers receded far into the mountains4 ,it is interesting to observe that we have1 especially in our own islands1 good evidence to show that during the glacial period considerable oscillations of the relative level of land and sea took place4 ,thus1 it has been ascertained1 that just before the latest epoch of extensive glaciation1 the ,british ,islands were largely submerged in the sea4 ,to what depth this remarkable submergence was carried we do not know1 because any marine deposits which may have been accumulated at that time over the drowned country were for the most part obliterated by the action of the ice-sheet which subsequently covered and reglaciated our lands4,l ,but the few fragments of such marine deposits as have been preserved show us that the depression reached more than #ejj feet in ,scotland 7i4e41 measured from the present sea-level71 and exceeding #ajjj feet in ,wales and ,ireland4 ,we note1 then1 in passing1 that the only great ,pleistocene submergence of these lands of which geologists have any knowledge took place before the appearance of the last general ice-sheet that overflowed our low-grounds4 ,the submergences of a later date were of inconsiderable importance1 hardly exceeding #ajj feet or thereabouts below the present sea-level4 ,the latest occupant of our islands and of northern ,europe was not the sea1 but ice4 ,the ,palocrystic ,sea1 which we have been recently assured would account for our glacial phenomena1 is of the stuff that dreams are made of4 ,there is not a jot or tittle of evidence for the former existence of such a sea over any part of ,britain or the continent of ,europe4 ,l ,i no longer believe in this great submergence4 ,the marine shells in the high-level drift-deposits of our islands are erratics1 carried by the ice-sheet which occupied the basin of the ,irish ,sea4 ,that the low-grounds were submerged but the amount of the submergence has not been ascertained2 probably it did not exceed a few hundred feet4 ,it is not necessary for my present purpose to enter further into the evidence of interglacial conditions4 ,the latest northern ice-sheet was preceded by a long epoch of mild and genial conditions1 during which elephants and hippopotami ranged north as far at least as ,yorkshire2 while middle ,germany1 as we know from the testimony of its interglacial deposits1 enjoyed a similar delightful climate4 ,and yet the immediately preceding glacial epoch had seen all those fertile regions covered with an ice-sheet that extended south as far as the fiftieth parallel of latitude4 ,now the question with which ,i am at present concerned is the extent of the latest general glaciation4 ,did the last great ice-sheet reach as far south as its predecessor8 ,it certainly did not4 ,its bottom-moraine has now been mapped out and distinguished from that of the older ice-sheet1 and we know that it does not extend so far south as the latter4 ,it is entirely absent over all the region to the west of the ,river ,elbe1 from near ,dresden to ,hamburg and the coast of ,holland4,m ,so that western ,germany and ,holland1 which were covered by ice during the epoch of greatest glaciation1 were not invaded by the ice-sheet underneath which the upper boulder-clay was accumulated4 ,this latest ice-sheet1 however1 overwhelmed all ,mecklenburg and ,mark ,brandenburg1 and streamed south nearly as far as ,saxony2 its southern margin extended east through ,silesia1 by ,liegnitz and ,breslau1 into ,poland and ,russia4 ,but the precise line it followed in the latter country has yet to be ascertained4 ,we may surmise1 however1 that it nowhere reached so far south or east as the ice-flow of the earlier epoch4 ,i may add that the southern termination of the latest ice-sheet is in many places marked out by heaps1 mounds1 and ridges of earthy sand1 gravel1 rolled stones1 and erratics2 in short1 by terminal moraines4 ,these1 however1 are frequently highly degraded and washed down4 ,m ,klockmann1 ,jahrb4 der k4 preuss4 geol4 ,landesanstalt fr #ahhc1 p4 #ccj4 ,of the extension of glacier-ice in the ,british ,islands at the epoch in question ,i shall only say that the glaciation of ,scotland was hardly1 if at all1 less extensive than during the climax of the ,ice ,age4 ,ireland1 too1 appears to have been almost as thickly mantled2 but the ice-sheet that covered ,england and ,wales did not extend so far south as that of the penultimate glacial epoch1 a considerable area in ,east ,anglia and the midland counties remaining apparently free from invasion4 ,the ,scandinavian and ,british ice-sheets1 however1 again coalesced upon the floor of the ,north ,sea4 ,,iii4 ,the ,results of ,fluvio-glacial ,action in ,europe4 ,the third question which ,i now proceed to consider is the result produced by the rivers and torrents of the ,ice ,age4 ,this1 ,i am aware1 is a wide subject1 and one upon which much has been written4 ,but there are a few points which may be advantageously discussed for the purpose of bringing into prominent view the conditions which obtained in the river-valleys of ,europe during the last great extension of glacier-ice4 ,a little consideration will serve to convince one that the intense glacial conditions that obtained in our ,continent during the cold epochs of the glacial period were due to a low temperature1 combined with excessive snow-fall4 ,the winters1 we can have no doubt1 must have been prolonged and severe4 ,but mere low temperature will not account for the enormous precipitation of snow4 ,for this1 great evaporation was required4 ,and we are therefore forced to admit that the direct heat of the sun in summer must have been greater than it is in the same regions at the present day4 ,now1 if this were really the case 7and ,i do not see how otherwise the facts can be explained71 then we ought to meet with evidence of swollen rivers1 torrents1 and widespread inundations everywhere outside of the glaciated areas4 ,and this is precisely what we do find4 ,immense accumulations of coarse gravels are widely spread over all the valleys that head in regions which were formerly the sites of snow-fields and glaciers4 ,these gravels are of such a character and are so distributed as to make it certain that they could not have been transported to and deposited in their present positions by rivers like those which now wind their way down the valleys of middle ,europe4 ,still more remarkable are the enormous sheets of loam which are spread over much wider areas and reach to more considerable heights than the gravels4 ,the origin of the gravels is sufficiently evident2 they are simply the coarser detritus1 swept along by the enormously flooded rivers of the glacial period1 and meet with their analogues in the torrential gravels of modern glacier-valleys in the ,alps and other elevated regions4 ,the more widely-spread loams1 according to the opinion of most glacialists1 represent the finer mud and silt deposited from the muddy waters of the same period4 ,but the height to which such gravels and loams ascend is so great that those who hold them to be of fluvio-glacial origin have found it difficult to maintain this view4 ,some writers1 indeed1 who have not sufficiently considered the weight of the evidence in its favour1 have set it aside1 and boldly suggested all kinds of wonderful hypotheses in its place4 ,one imaginative author1 for example1 believes the wide-spread loams to be of volcanic origin1 while another finds in the same deposits strong evidence of the ,deluge4 ,by a well-known and experienced observer1 the famous lss of middle ,europe is considered to be an olian accumulation--that is to say1 a wind-blown deposit--the result of long-continued or frequently-repeated dust-storms4 ,this is the opinion of ,baron ,richthofen1 whose great work on ,china is so justly esteemed4 ,he infers that at the time of the formation of our lss central ,europe was a dry desiccated region1 just as wide areas in central ,asia are in our own day4 ,he does not attempt to show us1 however1 how such climatic conditions could ever obtain in ,europe4 ,in point of fact1 the geographical conditions of our ,continent have not changed materially since ,pleistocene times1 and the presence of the wide ,atlantic ,ocean1 that laves all our western shores1 is of itself sufficient to preclude the possibility of such a climate having obtained in middle ,europe4 ,richthofen's theory likewise fails to account for the geographical distribution of the lss1 and for many facts relating to its geology4 ,only one of these last shall ,i mention4 ,the lss is intimately associated with accumulations1 the glacial and fluvio-glacial origin of which cannot be doubted4 ,it belongs1 in fact1 to the glacial series1 and was laid down at a time when vast snow-fields and ice-sheets existed1 and when it is quite impossible that a dry climate could have characterised any part of our ,continent4 ,in common with most geologists1 ,i believe that the lss is simply an inundation-mud1 deposited in temporary lakes and over flooded areas during the summer meltings of the snow- and ice-fields2 and ,i shall now try to show how the occurrence at high levels of gravels and such loams as the lss may be accounted for without having recourse to volcanic action or to winds1 or even to the ,deluge4 ,i shall invoke no agencies other than those which we are perfectly well assured were in full operation during the ,ice ,age4 ,now1 ,i ask you1 in the first place1 to bear in mind that while a glacial epoch continued1 extreme conditions could not have been restricted to the areas undergoing glaciation4 ,there is abundant evidence1 indeed1 to show that heavy1 snows occasionally covered other regions1 and that in such places severe frosts acted upon the rocks and soils even of the low-grounds4 ,need we wonder if at a time when the northern ice-sheet approached the fiftieth parallel of latitude in middle ,europe1 when almost every mountain-group of central and southern ,europe had its snow-fields and glaciers--need we wonder if at such a time the climate of wide areas outside of the glaciated tracts was extremely ungenial8 ,the more closely the superficial accumulations of such areas are studied1 the more clearly do we perceive in them the evidence of cold and humid conditions4 ,try1 then1 to picture to yourselves the probable aspect of those regions during a glacial epoch4 ,immediately south of the northern ice-sheet deep snows must have buried large tracts of country1 and such snows may have endured often for long years1 notwithstanding the great melting that took place in summer4 ,even much further south1 as in ,spain and ,italy1 deep snows would cover the lesser hills and hill-ranges1 while frost would act energetically in many a district where such action is now either inconsiderable or unknown4 ,such being the general conditions that must have obtained in the non-glaciated areas1 let us very briefly consider what the results of such conditions must necessarily have been4 ,every one has noticed1 during the more or less rapid melting of snow in winter and early spring1 that our streams and rivers are then much muddier than when in summer and autumn they are swollen by heavy rains4 ,this of course is due to the action of frost1 by means of which rocks are disintegrated and soils are broken up and pulverised1 so that when thaw supervenes1 the superficial covering becomes soaked with moisture like a sponge4 ,to such an extent does this take place1 that one may often see the saturated soil creeping1 slipping1 and even flowing down the slopes4 ,the effect of mere thaw is of course much intensified when the water derived from melting snows is present4 ,rills and tiny brooks then become converted into dark muddy torrents1 and enormous quantities of fine-grained detritus are eventually swept into the rivers4 ,the rivers rise in flood and inundate their plains1 over the surface of which considerable deposits of loam and silt often accumulate4 ,we cannot doubt that similar but much more intense action must have taken place over very wide regions in ,europe during a glacial epoch4 ,such having necessarily been the case1 we are not required to suppose that the lss and similar loams have been deposited entirely by rivers flowing from glaciers4 ,it is doubtless true that most of the rivers headed in those days in glacier regions1 and must in consequence have been highly discoloured with glacial mud1 and probably a very large proportion of the loams in question consists of the fine flour of rocks--the result of glacial grinding4 ,but the action of frost and thaw and melting snow upon the low-grounds1 such as ,i have described1 cannot be ignored1 and seems to have played a more important rle than has yet been recognised4 ,i think it helps us better to explain the well-known fact that land-shells are more or less commonly distributed through the lss4 ,one can readily understand1 at all events1 how snail-shells might be swept down the slopes of the land at the time of the spring thaws1 and how large numbers might find their way eventually into the swollen glacial rivers4 ,i have often observed1 during the melting of snow and the thawing of soils1 quantities of snail-shells in the very act of being swept into our brooks and rills4 ,and we are all familiar with the fact that1 after a spring-flood has subsided1 snail-shells1 along with vegetable dbris1 are often plentifully stranded upon the valley-slopes and flood-plains of our rivers4 ,admitting1 then1 that the lss and similar accumulations are simply inundation-loams formed at a time when glaciers were discharging immense volumes of muddy water1 and when the low-grounds were liable every summer to the denuding action of melting snows1 and so forth1 ,i have yet to account for the fact that these supposed inundation-loams sometimes occur at a height of #ajj feet1 or even of #cjj feet1 above the present levels of the rivers4 ,two theories have been advanced in explanation1 each of which seems to me to contain an element of truth4 ,it has1 in the first place1 been maintained1 as by ,prestwich1 that the lss at the higher levels was probably deposited long before the rivers had excavated their channels to their present depths4 ,thus1 during flood1 they would be enabled to overflow tracts which they could not possibly have reached when they had deepened their valleys to a much greater degree4 ,but while we must fully admit that the erosion effected by the rivers of the ,pleistocene or ,glacial period was excessive1 yet we find it difficult or impossible to believe that great valleys1 several miles in width1 and two or three hundred feet in depth1 were excavated in hard ,devonian and other equally durable rocks by the swollen and active rivers of the ,ice ,age4 ,and although it is extremely probable that the lss at the highest levels is older than the similar deposit at the lowest levels of such a valley as the ,rhine1 yet this does not get us out of our difficulty4 ,the other view to which ,i have alluded takes little or no account of river-erosion1 but maintains that the floods of the ,ice ,age were sufficiently great to reach the highest levels at which river-gravels and loams occur4 ,it is likely enough that1 under present conditions1 we can form but a very inadequate idea of the vast bodies of freshwater which formerly swept down our valleys1 but we may be pardoned if we express our inability to conceive of our ,european rivers flowing with a breadth of many miles1 and a depth of two or three hundred feet4 ,a few years before his death1 ,mr4 ,darwin made a suggestion to me1 which ,i think gives us the true solution of the problem4 ,he thought that during an ,ice ,age great beds of frozen snow might have accumulated over the low-grounds outside of the glaciated areas 7in the manner ,i have already described71 and that many valleys might have been filled to a considerable depth during a large part of the year with blown snow1 afterwards congealed4 ,in autumn1 when the running water failed1 the lines of drainage might in many cases be more or less choked1 and it would be a mere chance whether the drainage1 together with gravel1 sand1 and mud1 would follow precisely the same lines during the next summer4 ,such action being repeated year after year1 it might well happen that many river-valleys might become largely filled with rudely alternating layers of frozen snow and fluviatile detritus4 ,and if this were so1 the flooded rivers in summer would be enabled to overflow much wider and more elevated tracts than they could otherwise have reached4 ,as the climate became less excessive1 we can conceive of the frozen snows gradually melting1 and of river-detritus being deposited at lower and lower levels in the valleys4 ,the probability of such frozen masses having choked up valleys and impeded the drainage during the ,ice ,age is not a mere plausible conjecture4 ,in the far north of ,alaska--in a region which was certainly not overflowed by the ,north ,american ice-cap--extensive sheets of ice occur1 more or less deeply buried under thick soil4 ,nor can there be much doubt that these ice-masses date back to the ,glacial period itself1 seeing that in the soils which overlie them we meet with remains of the mammoth and other contemporaneous mammalian forms4 ,here1 then1 we have direct proof of the fact of frozen snow and ice having accumulated in the hollows of the land outside of the glaciated areas4,n ,n ,i have given ,mr4 ,darwin's views1 and discussed the origin of the ,pleistocene fluvio-glacial deposits at some length in ,prehistoric ,europe1 chaps1 viii4 and ix4 ,to this work ,i refer for detailed geological evidence in support of the view advocated above4 ,now1 if such conditions existed in the valleys of middle ,europe1 the widespread loss of those regions is readily accounted for4 ,the occurrence of irregular sheets and shreds of gravel and loam at heights of more than a hundred feet above a valley-bottom offers no difficulty--it is in fact precisely the kind of phenomenon we might have expected4 ,we are therefore not required to go out of our way to dream about impossible volcanic action1 or to call upon the winds of heaven to help us1 or upon the waters of the ,deluge to float us out of our difficulties4 ,but while ,i believe the views ,i have now advocated sufficiently account for the appearances presented by the ancient valley-gravels and loams of central ,europe1 there are two very considerable areas of lss which require some further explanation4 ,the first of these is that broad belt of lss which extends from west to east across the plains of northern ,germany1 and the northern boundary of which coincides with the limits reached by the last great ice-sheet1 from which it spreads south to the foot-hills of the ,harz1 and other mountains of middle ,europe4 ,here we have a sheet of lss which bears no apparent relation to the valley-systems of the region in which it occurs4 ,but the fact of its northern boundary being coincident with the terminal front of the last great northern ice-sheet at once suggests its origin4 ,it is evident that this ice-sheet must have blocked the rivers flowing north1 and dammed back their waters4,o ,a wide sheet of muddy water must therefore have extended east and west over the very area which is now covered by the belt of lss in question4 ,this temporary lake would doubtless be subject to great alternations of level--a portion draining away perhaps under the ice-sheet--but the water would for the most part make its way westward1 and eventually escape into the ,english ,channel4 ,from the waters of this great lake1 fed by many large glacial rivers1 abundant precipitation of loam and silt must have taken place4 ,o ,the late ,mr4 ,belt1 as is well known1 was of opinion that all the rivers flowing north in ,europe and ,asia were dammed back by a great ,polar glacier1 and that all the low-tracts in the northern portions of the two continents were thus covered by wide inland seas of freshwater4 ,as ,i do not believe that such a ,polar ice-cap existed during the ,glacial period1 ,i cannot agree with ,mr4 ,belt that the alluvial plains of northern ,siberia mark the sites of ice-dammed lakes4 ,the second and by far the most extensive sheet of lss in ,europe is the so-called black earth1 or tchernozem1 with which such enormous tracts in southern ,russia are covered4 ,this widespread lss--for such it really is--,i have elsewhere tried to show consists of the flood-loam and inundation-muds laid down by the water escaping along the margin of the northern ice-sheet1 which discharged its drainage in the direction of the ,black ,sea1 its black colour being due to the grinding down and pulverising of the black ,jurassic shales which extend over such wide regions in middle ,russia4 ,,iv4 ,the ,extent of ,glaciation in ,north ,america4 ,the various phenomena of glaciation which go to prove that a great ice-sheet formerly covered a wide region in northern ,europe are developed on a still more extensive scale in ,north ,america4 ,smoothed and striated rock-surfaces1 crushed and dislocated rock-masses1 and enormous accumulations of morainic dbris and fluvio-glacial detritus1 all combine to tell the same tale4 ,the morainic accumulations of ,north ,america have been distributed upon the same principles as the similar deposits of our own ,continent4 ,boulder-clay of precisely the same character as that of ,scotland and ,scandinavia1 of ,switzerland and north ,italy1 covers vast tracts in the low-grounds of the ,british ,possessions and the northern ,states of the ,union1 where it forms enormous sheets1 varying in thickness from #cj or #ej up to #ajj feet or more4 ,in the rough ,laurentian high-lands1 however1 it is more sparingly developed1 and the same is the case in the hilly regions of ,new ,england4 ,in short1 it thickens out upon the low-grounds1 and thins off upon the steeper slopes1 while it attains its greatest thickness and forms the most continuous sheets in the country that lies south of the great lakes4 ,the southern limits of this deposit form a kind of rude semi-circle4 ,from ,new ,york the boundary-line has been followed north-west through ,new ,jersey and ,pennsylvania to beyond the forty-second parallel1 after which it turns to the south-west1 passing down through ,ohio to ,cincinnati 7#ci72 then1 striking west and south-west through ,indiana1 it traverses the southern portion of ,illinois4 ,its course after it reaches the valley of the ,missouri has been only approximately determined1 but it turns at last rather abruptly to the north-west1 sweeping away in that direction through ,kansas1 ,nebraska1 ,dakota1 and ,montana4 ,the general course followed by the ice-sheet underneath which this boulder-clay was formed has been well ascertained1 partly by the evidence of the clay and its contents1 and partly by that of roches moutonnes and striated rocks4 ,the observations of geologists in ,canada and the ,states leave it in no doubt that an enormous sheet of ice flowed south over all the tracts which are now covered with boulder-clay4 ,during a recent visit to ,canada and the ,states1 ,i had opportunities of examining the glacial deposits at various points over a somewhat extensive area1 and everywhere ,i found the exact counterparts of our own accumulations4 ,in ,minnesota1 ,wisconsin1 ,iowa1 ,illinois1 ,indiana1 and ,ohio1 and again in ,new ,york1 ,connecticut1 and ,massachusetts1 and the low-grounds of ,canada1 ,i recognised boulder-clay of precisely the same character as that with which we are familiar at home4 ,the glacial phenomena of the ,hudson valley and of the lower part of the ,connecticut ,river were especially interesting4 ,in those regions the evidence of a southward flow of the ice is most conspicuous1 and the phenomena1 down to the smallest details1 exactly recalled those of many parts of ,europe4 ,professor ,dana1 under whose guidance ,i visited the ,connecticut valley1 showed me1 at a considerable height upon the valley-slope1 an ancient water-course1 charged with gravel and shingle1 which could not possibly have been laid down under present conditions4 ,it was1 in fact1 a sub-glacial water-course1 and resembled the similar water-courses which are associated with boulder-clay in our own country4 ,if ,i met with only familiar glacial phenomena in the low-lying tracts traversed by me1 ,i certainly saw nothing strange or abnormal in the hillier tracts4 ,in passing over the dreary regions between the valley of the ,red ,river and ,lake ,superior ,i was constantly reminded of the bleak tracts of ,archan gneiss in the north-west of ,scotland1 and of the similar rough broken uplands in many parts of ,scandinavia and ,finland4 ,the whole of that wild land is moutonne4 ,rough tors and crags are smoothed off1 while boulder-clay nestles on the lee-side4 ,in the hollows between the roches moutonnes are straggling lakes and pools and bogs innumerable4 ,frequently1 too1 one comes upon rounded cones and smooth banks of morainic gravel and sand1 and heaps of coarse shingle and boulders1 while erratics in thousands are scattered over the whole district4 ,if you wish to have a fair notion of the geological aspect of the region ,i refer to1 you will find samples of it in many parts of the ,outer ,hebrides and western ,ross-shire and ,sutherland4 ,cover those latter districts with scraggy pines1 and their resemblance to the uplands of ,canada will be complete4 ,from descriptions given by travellers it would appear that morainic detritus--mounds and sheets of stony clay1 gravel and sand1 shingle1 boulders1 and erratics--are more or less plentifully sprinkled over all the ,british ,possessions and the islands of the ,arctic ,archipelago2 so that we have every reason to believe that the ice-sheet which left its moraines at ,new ,york and ,cincinnati extended northwards to the ,arctic ,ocean4 ,nor can there be much doubt that this same mer de glace became confluent in the west with the great glaciers that streamed outwards from the ,rocky ,mountains2 while we know for a certainty that the southern portion of ,alaska1 together with ,british ,columbia and ,vancouver ,island1 were buried in ice that flowed outwards into the ,pacific4 ,along the eastern sea-board north of ,new ,york city there is no tract which has not been overflowed by ice4 ,the islands in ,boston ,harbour are made up for the most part of tough boulder-clay2 and boulder-clay and striated rocks occur also in ,maine1 ,new ,brunswick1 ,nova ,scotia1 and ,newfoundland4 ,thus we may say that the ice-covered region of ,north ,america was bounded on the north by the ,arctic1 on the west by the ,pacific1 and on the east by the ,atlantic ,oceans4 ,the ,rocky ,mountains1 however1 divided the great mer de glace that overflowed ,canada and the ,states from the ice that streamed outwards to the ,pacific4 ,measured from the base of the ,rockies to the ,atlantic1 the mer de glace of ,canada and the ,states must have exceeded #bejj miles in width1 and it stretched from north to south over #dj degrees of latitude4 ,outside of this vast region and the great mountain-ranges of the far west1 there are few hilly areas in the ,states which reach any considerable elevation4 ,south of the mers de glace of the north and west1 no such mountain-groups as those of middle and southern ,europe occur1 and consequently we do not expect to meet with many traces of local glaciation4 ,nevertheless1 these have been recognised in the ,alleghany ,mountains1 ,west ,virginia1 and in the ,unaka ,mountains1 between ,tennessee and ,north ,carolina4 ,but the glaciers of those minor hill-ranges were of course mere pigmies in comparison with the enormous ice-streams that flowed down the valleys of the ,rocky ,mountains and the ,sierra ,nevada4 ,even as far south as the ,sierra ,madre of ,mexico glaciers seem formerly to have existed2 and ,mr4 ,belt has described the occurrence of what he considered to be boulder-clays at a height of #bjjj to #cjjj feet in ,nicaragua4 ,i have mentioned the fact that in ,europe we have1 outside of the glaciated areas1 certain accumulations 7such as the ,gibraltar breccias7 which could only have been formed under the influence of extreme cold4 ,similar accumulations occur in ,north ,carolina1 where they have been carefully studied by ,mr4 ,w4 ,c4 ,kerr4 ,according to ,mr4 ,kerr1 these deposits have crept down the declivities of the ground under the influence of successive freezings and thawings2 and now that attention has been called to such phenomena1 our ,american friends will doubtless detect similar appearances in many other places4 ,the facts which ,i have now briefly indicated suffice to show that during the climax of glaciation ,north ,america must have presented very much the same appearance as ,europe4 ,each continent had its great northern ice-sheet1 south of which local glaciers existed in hilly districts1 many of which are now far below the limits of perennial snow4 ,we may note1 also1 that in each continent the mers de glace attained their greatest development over those regions which at the present day have the largest rainfall4 ,following the southern limits of glaciation in ,europe1 we are led at first directly east1 until we reach central ,russia1 when the line we follow trends rapidly away to the north-east4 ,the like is the case with ,north ,america4 ,trace the southern boundary of the ice-sheet west of ,new ,york1 and you find1 when you reach the valley of the ,missouri1 that it bends away to the north-west4 ,now we can hardly doubt that one principal reason for the non-appearance of the mer de glace in the far east of ,europe and the far west of ,america was simply a diminishing snow-fall4 ,those non-glaciated regions which lay north of the latitudes reached by the ice-sheets were dry regions in glacial times for the same reasons that they are dry still4 ,the only differences between glacial ,europe and ,america were differences due to geographical position and physical features4 ,the glaciation of the ,urals was comparatively unimportant1 because those mountains1 being flanked on either side by vast land-areas1 could have had only a limited snow-fall2 while the mountain-ranges of western ,north ,america1 on the other hand1 being situated near the ,pacific1 could not fail to be copiously supplied4 ,for obvious reasons1 also1 the ,north ,american ice-sheet greatly exceeded that of ,europe4 ,in all other respects the conditions were similar in both continents4 ,v4 ,changes of ,climate in ,north ,america during the ,ice ,age4 ,american geologists are now pretty well agreed that their interglacial deposits--the existence of which is not disputed--have precisely the same meaning as the similar deposits which occur in ,europe4 ,they tell of great climatic changes4 ,at present1 however1 there is no certain evidence in the ,american deposits of more than one interglacial epoch2 but the proofs of such an epoch having obtained are overwhelming4 ,the occurrence again and again of fossiliferous beds intercalated between two separate and distinct sheets of boulder-clay and morainic accumulations1 leaves us in no doubt that we are dealing with precisely the same phenomena which confront us in ,europe4 ,no mere partial recession and re-advance of the mer de glace will account for the facts4 ,we have seen that during the culmination of the ,glacial period the ,american ice-sheet overflowed ,ohio1 ,indiana1 and ,illinois4 ,now interglacial deposits occur as far north as the ,canadian shores of ,lakes ,ontario and ,superior1 so that all the country to the south must have been uncovered by ice before those interglacial deposits were laid down4 ,but the evidence entitles us to say much more than this4 ,the interglacial beds of ,ohio1 ,indiana1 ,illinois1 and other ,states1 afford abundant evidence of a great forest-growth having covered the regions vacated by the ice of the penultimate glacial epoch4 ,the trees of this forest-land included sycamore1 beech1 hickory1 red-cedar1 and others2 and amongst the plants were grape vines of enormous growth1 which1 according to ,professor ,cox1 indicate perhaps the luxuriance of a warmer climate4 ,at all events1 the climate that nourished such a forest-growth could not have been less genial than the present4 ,and such being the case1 we may reasonably infer that the vast regions to the north of the lakes were no more inhospitable then than they are now4 ,to this genial interglacial epoch succeeded the last glacial epoch1 when a great ice-sheet once more enveloped a wide area4 ,in the extreme east this latest mer de glace appears to have reached as far south as that of the earlier epoch2 but as we follow its terminal moraines westward they lead us further and further away from the southern limits attained by the preceding ice-sheet4 ,these great terminal moraines form an interesting study1 and the general results obtained by ,american observers have been very carefully put together by ,professor ,chamberlin4 ,i traversed wide regions of those moraines in ,indiana1 ,illinois1 ,wisconsin1 and ,minnesota1 and1 so far as my observations went1 ,i could only confirm the conclusions arrived at by ,professor ,chamberlin and others4 ,the mounds1 banks1 cones1 and ridges are unquestionably moraines--of enormous dimensions1 no doubt1 but in all their phenomena strictly analogous to similar gravelly moraines in our own country and the ,continent4 ,many of the ,american moraines consist almost entirely of water-worn material--sand1 gravel1 shingle1 and boulders1 together with large angular and sub-angular erratics4 ,these deposits are generally stratified1 and frequently show diagonal or false-bedding4 ,in this and other respects they exactly reproduce--but of course on a much larger scale--our ,scottish kames1 and the similar accumulations of north ,germany and ,finland1 and the low-grounds of ,italy opposite the mouths of the great ,alpine lakes4 ,the kames of ,wisconsin again and again reminded me of the gravelly moraines that cover the ground for many miles round the lower end of ,lake ,garda4 ,it is this gravelly and sandy aspect of the ,american moraines that is most conspicuous1 water-assorted materials seeming everywhere to form their upper and outer portions4 ,now and again1 however1 a deep cutting discloses underneath and behind such water-worn detritus a mass of confused materials1 consisting of clay1 sand1 gravel1 shingle1 and boulders1 which are angular and sub-angular1 often smoothed and striated1 and of all shapes and sizes4 ,according to ,mr4 ,chamberlin1 this unstratified material is indistinguishable from true till1 and is doubtless to be regarded as till pushed up into corrugations by the mechanical action of the ice4 ,this grand series of moraines stretches from the peninsula of ,cape ,cod across the northern ,states1 and passes in a north-westerly direction into the ,british ,possessions1 over which it has been followed for some #djj miles4 ,the disposition of the moraines1 forming as they do a series of great loops1 shows that the ice-sheet terminated in a number of lobes or gigantic tongue-like processes4 ,nothing seen by me suggested any marine action2 on the contrary1 every appearance1 as ,i have said1 betokened the morainic origin of the mounds2 and ,mr4 ,chamberlin assured me that their peculiar distribution was everywhere suggestive of this origin4 ,no one who has traversed the regions ,i refer to is at all likely to agree with ,sir ,w4 ,dawson's view1 that the ,american mounds1 etc41 are the shore-accumulations of an ice-laden sea4 ,the morainic origin of these accumulations having been demonstrated by ,american geologists1 we are now able to draw another parallel between the ,european and ,american glacial deposits4 ,we have seen that in ,europe the ice-sheet of the latest glacial epoch was by no means so extensive as that of the preceding glacial epoch4 ,the same was the case in ,north ,america4 ,moreover1 in ,america1 just as in ,europe1 the latest occupant of the land was not the sea1 but glacier-ice4 ,in ,scotland and ,scandinavia the gradual disappearance of the latest ice-sheets was marked by a partial submergence1 which in the former country did not greatly exceed #ajj feet1 and in the latter #gjj feet4 ,in ,america1 in like manner1 we find traces of a similar partial submergence4 ,in ,connecticut this did not exceed #dj or #ej feet1 but increased to some #ejj feet in the ,st4 ,lawrence1 and to over #ajjj feet in the ,arctic regions4 ,if there ever was during the ,glacial period a greater submergence than this in ,north ,america it must have taken place in earlier glacial or interglacial times1 but of such a submergence no trace has yet been recognised4 ,in this respect the ,american record differs somewhat from our own1 for in ,britain we have evidence of a submergence of over #ajjj feet1 which supervened in times immediately preceding the latest great extension of continental ice4,p ,but nowhere in middle ,europe1 and nowhere in ,north ,america1 in the region south and west of the great lakes1 is there any trace of a general marine submergence4 ,the ,palocrystic ,sea is as idle a dream for the northern ,states of ,america as it is for any part of ,europe4 ,p ,see footnote1 p4 #agc4 ,,vi4 ,the ,results of ,fluvio-glacial ,action in ,north ,america4 ,the close analogies which obtain between the glacial and interglacial deposits of ,europe and ,north ,america are equally characteristic of the fluvio-glacial accumulations of the two continents4 ,as in ,europe1 so in ,america we meet with considerable sheets of gravel and shingle1 sand1 fine clay1 and loam1 which are evidently of freshwater origin4 ,in the gently-undulating tracts of the northern ,states those deposits often spread continuously over wide regions2 in the hillier districts1 however1 they are most characteristic of the valleys4 ,they are very well represented1 for example1 in the ,connecticut valley1 where they have been carefully studied by ,professor ,dana4 ,like the similar deposits of our own ,continent1 they have been laid down by the torrents and swollen rivers of the ,glacial period4 ,the great range of moraines which marks the extreme limits reached by the latest ice-sheet is generally associated with sheets of gravel and sand1 which one can see at a glance are of contemporaneous origin1 having been spread out by the water escaping from the melting ice4 ,nor can one doubt that the vast sheets of lss in the ,missouri and ,mississippi valleys are strictly analogous in origin1 as they are in structure and disposition1 to the lss of ,europe4 ,i have spoken of the probable existence of a glacial lake formed by the damming back of the ,rhine and other rivers by the ,european ice-sheet4 ,now1 in ,north ,america we meet with evidence of the same phenomenon4 ,when the last ice-sheet of that continent attained its maximum development1 all the water escaping from its margin in the north ,states necessarily flowed south into the ,mississippi and ,missouri rivers4 ,but in course of time the ice melted away beyond the drainage-area of those rivers1 and disappeared from the valley of the ,red ,river of the north1 which1 it will be remembered1 empties itself northward into ,lake ,winnipeg4 ,when the ice-front had retired so far it naturally impeded the drainage of the ,red ,river basin1 and thus formed a vast glacial lake1 the limits of which have been approximately mapped out by ,mr4 ,upham1 by whom the ancient lake has been designated ,lake ,agassiz4 ,the deposits laid down in this lake consist of finely laminated clays1 etc41 which resemble in every particular the similar unfossiliferous clays so frequently found associated with glacial accumulations in ,europe4 ,had the drainage of the ,red ,river valley been south instead of north1 the clays and loams of the far north-west would not have been arrested and spread out where they now are1 and ,manitoba would have been covered for the most part with loose shingle1 gravel1 and sand4 ,thus the final disappearance of the ,american ice-sheet was marked by the formation not only of moraines1 but of flood-gravels and torrential- and inundation-deposits of the same character as those with which we are familiar at home4 ,wherever similar geographical conditions prevailed1 there similar geological results followed4 ,,vii4 ,conclusion4 ,there are many other points of resemblance between the glacial and fluvio-glacial accumulations of the two continents1 but to these time forbids any reference4 ,indeed1 ,i cannot recall any signal difference4 ,such differences as do occur are due simply to the varying conditions of the two continental areas4 ,the glacial phenomena of ,north ,america are a repetition of those of ,europe1 but upon a much grander scale4 ,the boulder-clays of the former continent1 in their composition1 structure1 and distribution1 exactly recall our own4 ,interglacial beds occur under similar circumstances in both continents2 and the same is the case with the gravelly moraines and fluvio-glacial accumulations4 ,we are driven1 then1 to the conclusion that the physical conditions of the ,glacial period were practically the same in ,europe and ,north ,america4 ,what those conditions were ,i have already indicated1 and have shown that the results arrived at by geologists are not vague dreams and speculations1 but a logical induction from well-ascertained facts4 ,before we can believe that volcanic eruptions1 a general deluge1 or a ,palocrystic ,sea have produced the many varied phenomena of our glacial formations1 either in whole or in part1 we must first shut our eyes and then erase from our minds all knowledge of the facts which have been so laboriously gathered by a long succession of competent observers4 ,illustration3 ,,plate ,,iii ,,distribution ,,of ,,ice ,,past ,,and ,,present4 ,,polar ,,view ,,of ,,the ,,world ,,on ,,lamberts ,,equal ,,area ,,projection ,,vii4 ,the ,intercrossing of ,erratics in ,glacial ,deposits4,q ,q ,the ,scottish ,naturalist1 #ahha4 ,among the many phenomena connected with the glacial deposits of this country which have puzzled geologists there is none more remarkable than the intercrossing of erratics4 ,the fact that such wandered blocks have apparently crossed each other's tracks in their journeys appears at first sight inexplicable on the assumption that their transport has been effected by land-ice4 ,the phenomena in question1 therefore1 have always been appealed to by those who uphold the iceberg origin of our boulder-clays1 etc41 as evidence decisively in favour of their views4 ,no one can deny that any degree and amount of intercrossing might take place in the case of icebergs4 ,we can readily conceive how floating ice1 detached from a long line of coast1 might be compelled by shifting winds and changing currents to tack about again and again1 so as to pursue the most devious course1 and scatter their stony burdens in the most erratic manner over the sea-bottom2 while1 on the other hand1 it is quite impossible to understand how a similar irregular distribution of erratics could take place under one and the same glacier flowing in a determinate direction4 ,it is little wonder1 then1 that the curious phenomena of the intercrossing of erratics should have had much importance attached to it by the upholders of the iceberg theory1 seeing that all the other proofs which have been adduced in favour of this theory have only served to demonstrate its insufficiency4 ,upon the facts connected with the intercrossing of erratics1 the supporters of this time-honoured theory are now making what ,i must believe is their last stand4 ,i purpose therefore1 in this paper1 to give a short outline of those facts1 with the view of showing that so far from being antagonistic to the land-ice theory1 they are in complete harmony with it2 and indeed must be considered as affording an additional demonstration of its truth4 ,some years ago ,i called attention to the fact that in the middle districts of ,scotland the boulder-clay not infrequently contains a curious commingling of northern and southern erratics4,r ,i showed that this was the case throughout a belt of country extending from the sea-coast near ,ayr1 north-east to the valley of the ,irvine1 and thence across the watershed into the ,avon1 and east to ,lesmahagow1 then down the valley of the ,clyde to ,carluke1 stretching away to the east by ,wilsontown1 and thereafter continuing along the crest of the ,pentlands and the northern slopes of the ,lammermuir ,hills1 by ,reston and ,ayton1 to the sea4 ,all along this line1 ,i remarked1 we have a 'debatable ground' of variable breadth1 throughout which we find a commingling in the till of stones which have come from north and from south4 ,south of it1 characteristic ,highland stones do not occur1 and north of it stones derived from the south are similarly absent4 ,the explanation of these facts is obvious4 ,the belt of ground referred to was evidently the meeting-place of the ,highland and southern mers de glace4 ,here the two opposing ice-flows coalesced and became deflected by their mutual pressure to right and left--one great current going east and another west4 ,it is evident that the line of junction between the two mers de glace could not be rigorously maintained in one and the same position during a period of glaciation1 but would tend to oscillate backwards and forwards1 according as one or the other ice-sheet prevailed4 ,sometimes the southern ice-sheet would be enabled to push back the northern mer de glace1 while at other times the converse would take place4 ,nor is it necessary to suppose that the advance of one ice-sheet was general along the whole line4 ,on the contrary1 it is most likely that the movement was quite irregular--an ice-sheet advancing in some places1 while at other points its line of junction with the opposing ice-sheet remained stationary1 or even retrograded4 ,such movements would obviously give rise to oscillations in the sub-glacial dbris of clay and stones2 and thus we have a simple and natural explanation of those intercrossings of erratics which are so characteristic of that region which ,i have termed the debatable ground4 ,and this conclusion is borne out by the fact that the glacial stri of the same debatable ground afford like evidence of oscillation in the trend of the ice-flow4 ,r ,great ,ice ,age1 #bnd edit41 p4 #fji4 ,along the base of the ,highland mountains in ,forfarshire1 etc41 we meet with similar intercrossings of erratics4 ,thus we occasionally encounter in the boulder-clays overlying the ,silurian regions erratics of ,old ,red ,sandstone rocks which have come from the east or south-east2 while the abundant presence of erratics of ,silurian origin1 on the other hand1 bespeak an ice-flow from the west towards the low-grounds4 ,in some places within the ,silurian area we encounter a greyish-blue boulder-clay containing ,silurian fragments only1 while in other places within the same area the boulder-clay becomes reddish1 and is charged with many boulders of ,old ,red ,sandstone rocks4 ,now the greyish-blue till could only have been laid down by glacier-ice descending from the ,silurian high-grounds to ,strathmore1 while the red boulder-clay points to a partial invasion of the ,silurian regions by land-ice1 which had previously traversed the lower-lying ,old ,red ,sandstone areas4 ,these apparently contradictory movements are readily accounted for by the former presence in the area of the ,north ,sea of the great ,scandinavian mer de glace4 ,dr4 ,james ,croll was the first to point out that the glacial phenomena of ,caithness and the ,shetlands could only be accounted for by the advance of the ,scandinavian ice-sheet towards our coasts1 where it encountered and deflected the ,scottish ice-sheet out of its normal course--a sagacious induction1 which the admirable and exhaustive researches of my colleagues1 ,messrs4 ,b4 ,n4 ,peach and ,j4 ,horne1 have now firmly established4 ,the lower blue boulder-clay was evidently accumulated at a time when the ,scottish ice was able to flow more or less directly east or south-east towards what is now the coast-line2 while the overlying red boulder-clay points to a subsequent period when the presence of the ,scandinavian mer de glace was sufficiently great to compel the ,scottish ice out of its normal course1 and cause it to flow in a north-easterly direction4 ,in doing so it now and again passed from tracts of ,old ,red ,sandstone to invade the ,silurian area1 and thus an overlying red boulder-clay was here and there accumulated upon the surface of a greyish-blue till in which not a single fragment of any ,old ,red ,sandstone rock occurs4 ,recently ,messrs4 ,b4 ,n4 ,peach and ,j4 ,horne1 in a most instructive paper on the ,glaciation of ,caithness1,s have described some remarkable comminglings of material which occur in a region where the glacial stri afford equally striking evidence of conflicting ice-movements4 ,these phenomena are developed here and there along a line which indicates the meeting-place of two rival ice-streams1 on each side of which the boulder-clay presents different characteristics--the one boulder-clay being the moraine profonde of the ice that flowed ,,ene4 and ,,nne4 towards the ,caithness plain1 while the other is an accumulation formed underneath the ice that streamed across that plain from ,,se4 to ,,nw4 ,these phenomena are thus1 as my colleagues remark1 quite analogous to those met with in the middle districts of ,scotland1 as described by me1 and referred to in a preceding paragraph4 ,now it is obvious that while these examples of intercrossings of erratics and cross-hatching of stri all go strongly to support the land-ice theory of the glacial phenomena1 they at the same time negative the notion of floating-ice having had anything to do with the production of the phenomena under review4 ,s ,proceedings ,royal ,physical ,society1 ,edinburgh1 #ahha4 ,before considering the evidence adduced by ,mr4 ,mackintosh and others as to the intercrossings of erratics in the drift-deposits of ,england1 ,i shall mention some of the more remarkable examples of the same phenomena which have been noticed by continental geologists4 ,the first cases ,i shall cite are those which have been observed in the glacial accumulations of the ,rhone valley in eastern ,france4 ,the land-ice origin of these accumulations has never been called in question1 and as the intercrossings of erratics in that region are not only more common1 but much more striking and apparently inexplicable than any which have been noticed elsewhere1 it will be admitted that they of themselves afford a strong presumption that the conflicting courses followed by the erratics in certain regions of our own country are the result rather of oscillations in the flow of land-ice than of the random and eccentric action of icebergs4 ,the researches of ,swiss and ,french glacialists have proved that during the climax of the ,glacial period an enormous area in the low-grounds of eastern ,france was covered with a huge mer de glace1 formed by the union of the great ,rhone glacier with the glaciers descending from the mountains of ,savoy and ,dauphiny4 ,a line drawn from ,bourg by way of ,chatillon1 ,villeneuve1 ,trvoux1 and ,lyons to ,vienne1 and thence south-east by ,beaurepaire to the valley of the ,isre1 a few miles above ,st4 ,marcellin1 indicates roughly the furthest limits reached by the mer de glace4 ,over all the low-grounds between that terminal line and the mountains are found widespread sheets of boulder-clay and sand and gravel1 together with loose erratics4 ,now and again1 too1 well-marked terminal moraines make their appearance1 while the rock-surfaces1 when these are visible and capable of bearing and retaining glacial markings1 present the usual aspect of roches moutonnes4 ,the same kinds of morainic materials and ice-markings may of course be followed up into the valleys not only of the ,alps properly so-called1 but also into those of the hills of ,bugey and the secondary mountain-chain of ,savoy and ,dauphiny4 ,it has indeed long been known that local glaciers formerly occupied the mountain-valleys of ,bugey4 ,for example1 a number of small glaciers have descended from the slopes of the mountains west of ,belley 7such as ,bois de la ,morgue1 ,bois de ,lind1 etc47 to the ,rhone1 and again from ,mont du ,chat to the north-west4 ,these glaciers were quite independent of the greater ice-streams of the neighbouring ,alps of ,savoy1 and the same was the case with the glaciers of that mountainous tract which extends from ,nantua south to ,culoz1 between the valleys of the ,ain and the ,rhone4 ,from this elevated region many local glaciers descended1 such as that of the ,valromey1 which flowed for a distance of some twenty miles from north to south4 ,again1 similar local glaciers have left abundant traces of their former presence throughout the mountainous belt of land that stretches between ,chambery and ,grenoble to the west of the valley of the ,isre4 ,the moraines of all those local glaciers1 charged as they are with the dbris of the neighbouring heights1 clearly indicate that the local glaciers flowed each down its own particular valley4 ,there are certain other appearances1 however1 which seem at first sight to contradict this view4 ,sometimes1 for example1 we encounter in the same valleys erratics which do not belong to the drainage-system within which they occur1 but have without doubt been derived from the higher ,alps of ,switzerland and ,savoy4 ,and the course followed by these foreign erratics has crossed at all angles that which the local glaciers have certainly pursued--occasionally1 indeed1 the one set of erratics has travelled in a direction exactly opposed to the trend taken by the others4 ,as examples1 ,i may cite the case of the erratics which occur in ,petit ,bugey4 ,in this district we encounter many locally-derived erratics which have come from ,mont du ,chat to the west of the ,lac du ,bourget--that is to say1 they have travelled in a north-westerly direction4 ,but in the same neighbourhood are found many erratics of ,alpine origin which have been carried from north-east to south-west1 or at right angles to the course followed by the local erratics4 ,again1 in the valley of the ,seran we have evidence in erratics and terminal moraines of a local glacier which flowed south as far as the ,lyons and ,geneva ,railway1 in the neighbourhood of which1 a few miles to the west of ,culoz1 its terminal moraines may be observed4 ,this is the extinct ,glacier du ,valromey of ,,mm4 ,falsan and ,chantre4 ,now it is especially worthy of note that in the same valley we have distinct evidence of an ice-flow from south to north--i4e41 up the valley4 ,erratics and morainic materials which are unquestionably of ,alpine origin have been followed a long way up the ,seran valley--for two-thirds of its length at least4 ,before they could have entered that valley and approached the slopes of ,romey1 they must have travelled down the valley of the ,rhone from the higher ,alps of ,savoy in a south-west and south direction until they rounded the ,montagne du ,grand ,colombier4 ,it was only after they had rounded this massive mountain-ridge that they could pursue their course up the valley of the ,seran1 in a direction precisely opposite to that which they had previously followed4 ,these and many similar and even more remarkable examples of the intercrossings of streams of erratics are described by ,,mm4 ,falsan and ,chantre1 and graphically portrayed in their beautiful and instructive work on the ,ancient ,glaciers and ,erratic ,deposits of the ,basin of the ,rhone2 and the explanation of the phenomena given by them is extremely simple and convincing4 ,the local erratics and moraines pertain partly to the commencement and partly to the closing stage of the ,glacial period4 ,long before the south branch of the great glacier of the ,rhone had united with the glacier of the ,arve1 and this last with the glaciers of ,annecy and ,beaufurt1 and before these had become confluent with the glacier of the ,isre1 etc41 the secondary mountain-ranges of ,savoy and ,dauphiny and the hills of ,bugey were covered with very considerable snow-fields1 from which local glaciers descended all the valleys to the low-ground4 ,but when the vast ice-flows of ,switzerland1 ,upper ,savoy1 etc41 at last became confluent1 they completely overflowed many of the hilly districts which had formerly supported independent snow-fields and glaciers1 and deposited their bottom-moraines over the morainic dbris of the local glaciers4 ,in other cases1 where the secondary hill-ranges were too lofty to be completely drowned in the great mer de glace1 long tongues of ice dilated into the valleys1 and compelled the local ice out of its course2 sometimes1 as in the case of the ,valromey1 forcing it backward up the valleys down which it formerly flowed4 ,but when once more the mighty mer de glace was on the wane1 then the local glaciers came again into existence1 and reoccupied their old courses4 ,and thus it is that in the hilly regions at the base of the higher ,alps1 and even out upon the low-grounds and plains1 we encounter that remarkable commingling of erratics which has been described above4 ,not infrequently1 indeed1 we find one set of moraines superposed upon another1 just as in the low-grounds of northern ,germany1 etc41 we may observe one boulder-clay overlying another1 the erratics in which give evidence of transport in different directions4 ,the observations recorded by ,,mm4 ,falsan and ,chantre1 and their colleagues1 thus demonstrate that intercrossings of erratics of the most pronounced character have been brought about solely by the action of glaciers4 ,in the case of the erratics and morainic accumulations of the basin of the ,rhone1 the action of icebergs is entirely precluded4 ,i may now mention some of the more remarkable examples of intercrossings of erratics which have been recorded from the glacial accumulations of north ,germany1 etc4 ,an examination of the glacial stri1 roches moutonnes1 and boulder-clays of ,saxony leads to the conviction1 according to ,credner1 ,penck1 ,torell1 ,helland1 and others1 that the whole of that region has been invaded by the great ,scandinavian mer de glace which flowed into ,saxony from ,,nne4 to ,,ssw4 ,erratics from southern ,sweden and ,gothland occur in the boulder-clay1 and the presence of these1 taken in connection with the direction of the glaciation1 leaves us no alternative but to agree with the conclusions arrived at by the ,saxon geologists4 ,but1 apparently in direct contradiction of this conclusion1 we have evidence to show that boulders of the same kinds of rock occur in ,denmark and ,holland1 pointing to a former ice-flow from north-east to south-west and west4 ,thus boulders derived from ,gothland occur at ,grningen in ,holland1 while fragments from the island of land are met with in ,fax2 and erratics from the borders of the ,gulf of ,finland are encountered at ,hamburg4 ,indeed1 when geologists come to examine the erratics in north ,germany and ,poland generally1 they find evidence of apparently two ice-flows--one of which went south-south-west1 south1 and south-east--spreading out1 as it were1 in a fan-shape towards the southern limits reached by the great ,northern ,drift1--while the other seems to have followed the course of the ,baltic depression1 overflowing the low-grounds of northern ,prussia1 ,holland1 etc41 in a south-west and west direction4 ,now1 it is quite evident that no one mer de glace could have followed these various directions at one and the same time4 ,the explanation of the apparent anomaly1 however1 is not far to seek4 ,it is reasonable to infer that long before the mer de glace had attained its maximum dimensions1 when as yet it was confined to the basin of the ,baltic and was only able to overflow the northern regions of ,prussia1 etc41 its course would be determined by the contour of the pavement upon which it advanced4 ,it would1 therefore1 be compelled to follow the ,baltic depression1 and for a long time it would carry erratics from ,finland1 the ,baltic islands1 and eastern ,sweden in a south-west and west-south-west direction4 ,and this would continue to be the direction even after a considerable portion of the low-grounds of ,prussia1 etc41 had been overflowed4 ,but when the ice-sheet was enabled to advance south into ,saxony1 ,poland1 and ,lithuania1 erratics from ,finland1 the ,baltic islands1 etc41 would necessarily cease to travel towards the west1 and hold on a south-south-east1 south1 and south-south-west course4 ,again1 when the mer de glace was on the decline1 a time would return when the ice1 as before1 would be controlled in its flow by the ,baltic depression1 and this would give rise to a further distribution of erratics in a prevalent west-by-south direction4,t ,t ,for a fuller discussion of the distribution of erratics on the ,continent1 ,i may refer to ,appendix1 ,note ,b1 in ,prehistoric ,europe1 where the reader will find references to the literature of this interesting subject4 ,continental geologists now recognise a distinct stage of the ,ice ,age1 during which their ,upper ,diluvium was deposited by a great glacier that occupied the basin of the ,baltic4 ,this ,great ,baltic ,glacier appears to have been contemporaneous with the local ice-sheets and valley-glaciers of the ,highlands and other mountain-tracts of our island4 ,see ,article ,x4 #ahib4 ,no one of late years has been more assiduous in the collection of facts relating to the intercrossing of erratics in the drift-deposits of ,england than ,mr4 ,d4 ,mackintosh4,u ,he has written many instructive and interesting descriptions of the phenomena in question1 which he justly thinks are of prime importance from a theoretical point of view4 ,in a recent paper,v he presents us with the results of a systematic survey of the direction and limits of dispersion of the erratics of the west of ,england and east of ,wales1 which he evidently is of opinion afford strong support to the iceberg theory1 while at the same time they are directly opposed to the theory of transport by land-ice4 ,i have attentively considered all the arguments advanced by ,mr4 ,mackintosh in favour of his views--the one upon which he apparently lays most stress being that of the intercrossings of erratics observed by him--and ,i shall now proceed to point out how the phenomena described by him are most satisfactorily explained by the land-ice theory4 ,they seem to me1 indeed1 to lend additional support to that theory1 in the same manner as the intercrossings of boulders observed in ,scotland1 northern ,germany1 etc41 and sub-alpine regions of ,france4 ,mr4 ,mackintosh calls attention to the fact that erratics of the well-known ,criffel granite are found scattered over a large part of the plain of ,cumberland1 from which they extend south along the coast to near the mouth of the estuary of the ,duddon4 ,they reappear on the coast in the neighbourhood of ,blackpool and ,liverpool1 and again at intervals on the coasts of north ,wales from ,flint to ,colwyn ,bay1 and thence to ,penmaenmawr and the neighbourhood of ,beaumaris4 ,they are dispersed over the peninsula of ,wirral and the ,cheshire plain1 etc41 and they have been followed south-east as far as the neighbourhood of ,cardington1 near ,church ,stretton1 ,burton1 ,wolverhampton1 ,stafford1 ,hare ,castle1 ,macclesfield1 and ,manchester4 ,this great stream of boulders1 therefore1 spreads out to south-east1 south1 and south-west3 the erratics1 to quote ,mr4 ,mackintosh1 have radiated from an area much smaller than their terminal breadth4 ,the same is the case1 ,i may remark in passing1 with erratics in the boulder-clays of ,scotland1 ,scandinavia1 north ,germany1 etc41 as also with those in the drift-deposits of the great ,rhone glacier and other ancient glaciers both on the north and south side of the ,alps4 ,now1 the course followed by the ,criffel erratics is crossed at an acute angle by the path pursued by many boulders of ,eskdale granite1 and various felspathic rocks derived from the ,cumberland mountains4 ,for example1 ,cumberland erratics of the kinds mentioned occur near ,st4 ,asaph and ,moel-y-,tryfane and in ,anglesey1 and they have been followed over a wide district in ,cheshire1 etc41 extending as far south as ,church ,stretton and ,wolverhampton1 and as far east as ,rochdale4 ,more than this1 we find that numerous erratics of felstone1 derived from the mountain of ,great ,arenig1 in north ,wales1 have gone to north-east as far as ,halkin ,mountain1 in ,flintshire1 ,eryrys1 near ,llanarmon1 and ,chirk1 from which last-named place they have been traced in a south-easterly direction to ,birmingham1 ,bromsgrove1 etc4 ,a glance at the map of ,england will show that this south-easterly drift of erratics crosses at an acute angle the paths followed by the ,criffel granite boulders and the erratics derived from ,cumberland1 so that we have now several intercrossings to account for4 ,how can this be done by the land-ice theory8 ,u ,this enthusiastic geologist died in #ahia4 ,v ,quart4 ,journ4 ,geol4 ,soc41 vol4 xxxv4 p4 #dbe ,the explanation seems to me obvious1 for the phenomena are1 after all1 less striking than similar appearances which have been observed in ,scotland1 especially by my colleagues1 ,messrs4 ,peach and ,horne1 in ,caithness and the ,orkney and ,shetland ,islands2 and they are certainly less intricate than the facts recorded by ,,mm4 ,falsan and ,chantre concerning the intercrossing1 interosculation1 and direct opposition of erratic paths in ,savoy and ,dauphiny4 ,we have only to reflect that the great mer de glace--to which1 as ,i believe1 all the ,english phenomena are due--did not come into existence and attain its maximum dimensions in the twinkling of an eye1 nor could it afterwards have disappeared in the same sudden manner4 ,on the contrary1 a period of local glaciation must have preceded the appearance of the great ice-sheet4 ,at first1 and for a long time1 permanent snow would be confined to the higher elevations of the land1 and glaciers would be limited to mountain-valleys2 but as the temperature fell the snow-line would gradually descend1 until at last1 probably after a prolonged period1 it reached what is now the sea-level4 ,thus the formation of nv and glacier-ice would eventually take place over what are now our low-grounds1 and other tracts also1 which are now submerged4 ,it is quite impossible that the vast sheets of ice which can be demonstrated to have covered ,scotland1 a large part of ,england1 ,ireland1 ,scandinavia1 and north ,germany1 and even the limited area of the ,fare ,islands1 could possibly have been fed by the snow-fields of mountain-heights only4 ,the precipitation and accumulation of snow1 and the formation of nv and glacier-ice1 must have taken place over enormous regions in what are now the temperate latitudes of ,europe4 ,it is obvious that the direction of ice-flow in the basin of the ,irish ,sea opposite the south of ,scotland and the west of ,england1 while preserving a general southerly trend1 would vary at different periods4 ,before the mer de glace in that basin had attained its climax there must have been a time when the ice1 streaming outwards from the high-grounds of ,cumberland1 was enabled to push its way far westward out into the basin of the ,irish ,sea4 ,at that time it was still able to hold its own against the pressure exerted by the ,scottish ice4 ,but as the general mer de glace increased in thickness1 the course of the ,cumberland ice would be diverted ever further and further to the south-east1 until1 eventually1 the ,scottish ice came to hug the coast of ,cumberland1 and to overflow ,lancashire in its progress towards the south-east4 ,so gorged with ice did the basin of the ,irish ,sea become1 that a portion of the ,scottish ice was forced over the plain of ,cumberland and up the valley of the ,eden1 where it coalesced with the ice coming north from the ,shap district1 and thereafter flowed in an easterly direction to join the great mer de glace of the ,north ,sea basin4 ,thus the intercrossings of the ,criffel and ,cumberland erratics described by ,mr4 ,mackintosh receive a ready explanation by the land-ice theory4 ,nor do the intercrossings of the ,welsh erratics with those derived from ,scotland and ,cumberland offer any difficulty4 ,the ice coming from the ,welsh mountains would naturally be deflected towards south-east by the mer de glace that streamed in that direction1 and might quite well have carried its characteristic boulders as far as ,birmingham before the general mer de glace had attained its greatest dimensions4 ,but when that period of maximum glaciation arrived1 the ,welsh boulders would be unable to travel so far towards the east1 and the ,scottish and ,cumberland boulders would then cross the path formerly followed by the felstone erratics from ,great ,arenig4 ,again1 it is evident that when the mer de glace was gradually decreasing similar oscillations of the ice-flow would take place1 but in reverse order1 and thus would give rise to a second series of intercrossings4 ,moreover1 we must remember that the ,glacial period was characterised by several great changes of climate4 ,it was not one continuous and prolonged period of cold conditions1 but consisted rather of a succession of arctic and genial climates2 so that the same countries were overrun at different epochs by successive mers de glace1 each of which would rework1 denude1 and redistribute to a large extent the morainic materials of its predecessor1 and thus might well cause even greater complexity in the dispersion of erratics than has yet been recognised anywhere in these islands4 ,mr4 ,mackintosh refers to the occurrence of chalk-flints and ,lias fossils associated with northern erratics in the drift-deposits of the west of ,england1 the presence of which1 he thinks1 is fatal to the theory of transport by land-ice4 ,thus1 he says1 chalk-flints1 etc41 have been met with at ,lillieshall 7east of ,wellington71 at ,strethill 7near ,ironbridge71 at ,seisdon 7between ,wolverhampton and ,bridgenorth71 at ,wolverhampton1 near ,stafford1 and near ,bushbury4 ,chalk-flints have also been found as far west as ,malvern and ,hatfield ,camp1 south of ,ledbury4 ,all these erratics have crossed ,england from the east1 according to ,mr4 ,mackintosh and other observers4 ,not only so1 but1 as ,mr4 ,mackintosh remarks1 those found at ,wolverhampton1 ,birmingham1 etc41 must have crossed the course of the northern boulders near its southerly termination4 ,and since both northern and eastern erratics are found associated in the same drift-deposit1 it seems to him impossible to explain the intercrossing by land-ice or glaciers4 ,now1 on the contrary1 those eastern erratics are scattered over the very districts where ,i should have expected to find them4 ,the observations of geologists in ,east ,anglia have shown that that region has been invaded by the mer de glace of the ,north ,sea basin4,w ,this remarkable glacial invasion is proved not only by the direction followed by stones of local derivation1 and by boulders which have come south from ,scotland and the northern counties1 but by the occurrence in the boulder-clay at ,carnelian ,bay and ,holderness of erratics of certain well-known ,norwegian rocks1 which have been recognised by ,mr4 ,amund ,helland4 ,the occurrence of chalk-flints and fragments of ,oolitic rocks in the neighbourhoods mentioned by ,mr4 ,mackintosh thus only affords additional evidence in favour of the land-ice origin of the drift-deposits described by him4 ,the mer de glace that flowed down the east coast of ,england seems to have encroached more and more upon the land1 until eventually it swept over the low-lying ,midlands in a south-westerly direction1 and coalesced with the mer de glace that streamed inland from the basin of the ,irish ,sea1 and the ice that flowed outwards from the high-grounds of ,wales4 ,the united ice-stream would thereafter continue on its south-westerly course down the ,severn valley to the ,bristol ,channel4 ,i have no doubt that ,mr4 ,mackintosh will yet chronicle the occurrence of chalk-flints and other eastern erratics from localities much further to the south than ,ledbury4 ,w ,see ,mr4 ,skertchly's description of ,east ,anglian deposits in ,great ,ice ,age1 #bnd edit41 p4 #ceh4 ,again1 considerable stress has been laid by ,mr4 ,mackintosh upon the occurrence of chalk-flints in the drift-deposits of ,blackpool1 ,dawpool1 ,parkgate1 ,halkin ,mountain1 ,wrexham1 the peninsula of ,wirral1 ,runcorn1 ,delamere1 ,crewe1 ,leylands1 ,piethorne 7near ,rochdale71 and other places4 ,all these flints1 ,mr4 ,mackintosh remarks1 belong to the basin of the ,irish ,sea1 and have almost certainly crossed the general course of the northern boulders on their way from ,ireland4 ,here1 unfortunately1 the ,irish ,sea intervenes to conceal the evidence that is needed to enable us to track the exact path followed by the erratics in question4 ,i am not so certain as ,mr4 ,mackintosh that the chalk-flints he refers to came from the north of ,ireland4 ,chalk-flints occur pretty numerously in the drift-deposits in the maritime districts of north-eastern ,scotland1 which we have every reason to believe have been derived from an area of ,cretaceous rocks covering the bottom of the adjacent sea2 and for aught one can say to the contrary1 patches of chalk-with-flints may occur in like manner in the bed of the ,irish ,sea4 ,i cannot at present remember whether any boulders of the basalt-rocks1 which are associated with the ,chalk in the north of ,ireland1 have been recognised in the drifts of the west of ,england2 but if the chalk-flints really came from ,antrim1 it is more than probable that they would be accompanied by fragments of the hard igneous rocks which overlie the ,cretaceous strata of north ,ireland4 ,chalk and chalk-flints occur in the boulder-clay of the ,isle of ,man1 where they are associated1 ,mr4 ,horne tells us1 with ,criffel granite and fragments of a dark trap-rock4,x ,possibly these last are basalt-rocks from ,antrim4 ,it seems reasonable1 therefore1 to believe that erratics of ,irish origin have found their way to the ,isle of ,man2 and if this be so1 it may be permissible to assume that the chalk-flints of ,blackpool1 etc4 7and perhaps also some of the basalt-rocks71 have come from the same quarter4 ,mr4 ,horne has no doubt that the ,irish erratics were brought to the ,isle of ,man by land-ice4 ,referring to the conclusion arrived at by ,mr4 ,close that the ,irish mer de glace was probably not less than #cjjj feet in depth1 he remarks3 ,it is highly probable that this great mass of ,irish ice succeeded1 after a hard battle 7i4e41 with the ,scottish ice-sheet71 in reaching the ,manx coast-line4 ,it is not to be supposed that the normal momentum of the respective ice-sheets remained constant4 ,the moving force must have varied with changing conditions4 ,on the other hand1 it is quite possible that there may have been an 'under-tow' of the ice from the north-east coast of ,ireland1 which would easily account for ,antrim chalk and chalk-flints in the ,manx till4 ,i would go further1 and state my conviction that before the united ice-sheets had attained their maximum development1 it is almost certain that the ice flowing into the ,irish ,sea basin by the ,north ,channel would for a long time exceed in mass the coalescent glaciers that descended from the ,southern ,uplands of ,scotland1 and would therefore be enabled to extend much further to the east than it could at a later date1 when the general mer de glace had reached its climax4 ,it might thus have advanced as far as and even beyond the ,isle of ,man4 ,this inference is based upon the simple fact that the area drained by the mer de glace of the ,north ,channel was very much greater than the area extending from the watershed of the ,southern ,uplands of ,scotland to the ,isle of ,man4 ,erratics from the north of ,ireland would thus travel down the bed of the ,north ,channel1 and eventually be distributed over a wide area up to and possibly even some distance beyond the ,isle of ,man4 ,but as the ,scottish and ,cumbrian ice-flows gradually increased in importance1 the mer de glace coming from the ,north ,channel would be forced further and further to the west1 until the ice-flow issuing from the high-grounds of ,kirkcudbright at last succeeded in reaching the middle of the ,irish ,sea basin4 ,this gradual modification of the general ice-flow in that basin would of course give rise to a redistribution of the ground-moraine1 and the ,irish erratics would then travel onwards underneath the ,scottish ice1 and eventually reach the low-grounds of ,lancashire and ,cheshire1 along with erratics from ,criffel and the ,cumbrian mountains4 ,it is1 therefore1 quite unnecessary to suppose that the mer de glace of the ,north ,channel actually crossed the whole breadth of the basin of the ,irish ,sea to invade ,lancashire1 ,cheshire1 and north ,wales4 ,had this been the case1 chalk-flints1 chalk1 and many other kinds of rock derived from the north of ,ireland1 and even from ,arran and ,argyll1 would have abounded in the drifts of the west of ,england4 ,erratics coming from ,ireland could not possibly have travelled underneath ,irish ice further east than the ,isle of ,man4 ,there or thereabouts1 as ,i have said1 the mer de glace of the ,north ,channel would begin to encounter the ice streaming down from the uplands of ,galloway and the mountains of ,cumberland3 and as the ice from these quarters increased in thickness1 it would gradually override what had formerly been the bottom-moraine or till of the ,north ,channel mer de glace4 ,thus ,irish erratics would become commingled with erratics from ,criffel1 etc41 and be carried forward in a southerly and south-easterly direction4 ,the chalk-flints in the drifts of ,lancashire1 ,cheshire1 etc41 are probably therefore remanis--the relics of the bottom-moraine of the ,north ,channel mer de glace rearranged and redistributed4 ,and this is why they and other ,irish rocks are so comparatively rare in the glacial accumulations of the west of ,england4 ,x ,trans4 ,edin4 ,geol4 ,soc41 vol4 ii41 #ahgd4 ,thus all the instances of intercrossings adduced by ,mr4 ,mackintosh as favouring the iceberg theory1 and condemning its rival1 ,i would cite as proving exactly the opposite4 ,so far from presenting any real difficulty to an upholder of the land-ice theory1 they1 in point of fact1 as ,i have already remarked1 lend that view additional support4 ,it is not my purpose to criticise all the arguments and reasons advanced by ,mr4 ,mackintosh in favour of his special views1 but ,i may be allowed a few remarks on the somewhat extraordinary character of the agents which1 according to him1 were mainly instrumental in producing the drift-phenomena of western ,england4 ,before doing so1 however1 ,i may point out that1 in ascribing the transport of erratics in that region 7and1 by implication1 the formation of the boulder-clays1 etc41 with which most of these erratics are associated7 to floating-ice and sea-currents1 ,mr4 ,mackintosh has failed to furnish us with any fossil evidence to show that western ,england was under water at the time the boulder-clays and erratics were being accumulated4 ,he speaks of cold and warm currents1 but where do we find any traces of the marine organisms which must have abounded in those waters8 ,where are the raised sea-beaches which must have marked the retreat of the sea8 ,where do we encounter any organic relics that might help us to map out the zones of shallow and deep water8 ,the sea-shells1 etc41 which occur in the boulder-clays are undeniably remanis2 they are erratics just as much as the rock-fragments with which they are associated4 ,similar assemblages of organic remains are met with in the till of ,caithness1 where shallow-water and deep-sea shells1 and shells indicative of genial and again of cold conditions1 are all confusedly distributed throughout one and the same deposit4 ,the same or analogous facts are encountered in the ,blocklehm of some parts of ,prussia1 marine and freshwater shells occurring commingled in the boulder-clay4 ,nay1 even in the moraine profonde of the ancient ,rhone glacier1 broken and well-preserved shells of ,miocene and ,pliocene species appear enclosed in the tumultuous accumulation of clay1 sand1 and erratics4 ,and precisely similar phenomena confront us in the glacial deposits of the neighbourhood of ,lago ,lugano4 ,mr4 ,mackintosh refers to the so-called stratification of the boulder-clay1 as if that were a proof of accumulation in water4 ,but a rude kind of bedding1 generally marked by differences of colour1 and sometimes by lines of stones1 was the inevitable result of the sub-glacial formation of the boulder-clay4 ,the lines of bedding are due to the shearing of the clay under great pressure1 and may be studied in the boulder-clay of ,switzerland and ,italy1 and in the till not only of the ,lowlands but of the ,highlands of ,scotland4 ,occasionally the lines are so close that the clay sometimes presents the appearance of rude and often wavy and irregular lamination--a section of such a boulder-clay reminding one sometimes of that of a gnarled gneiss or crumpled schist4 ,and these appearances may be noted in boulder-clays which occupy positions that preclude the possibility of their being marine--as in certain valleys of the ,highlands1 such as ,strathbraan1 and in the neighbourhood of ,como1 in ,italy4 ,this lamination is merely indicative of the intense pressure to which the till was subjected during its gradual accumulation under the ice4 ,it is assuredly not the result of aqueous action4 ,aqueous lamination is due to sifting and winnowing--the coarser or heavier and finer or lighter particles being separated in obedience to their different specific gravity1 and arranged in layers of more or less regularity according to circumstances4 ,there is nothing of this kind of arrangement1 however1 in the so-called stratified boulder-clay4 ,if the clay of an individual lamina be washed and carefully sifted1 it will be found to be composed of grains of all shapes1 sizes1 and weights1 down to the finest and most impalpable flour4 ,it is impossible to believe that such a heterogeneous assemblage of grains could have been dropt into water without the particles being separated and sifted in their progress to the bottom4 ,of course1 every one knows that patches and beds of laminated clay and sand of veritable aqueous origin occur now and again in boulder-clay4 ,i suppose there is no boulder-clay without them4 ,i have seen them in the till of ,italy and ,switzerland1 where they show precisely the same features as the similar laminated clays in the till of our own islands4 ,but these included patches and beds point merely to the action of sub-glacial waters1 such as we know circulate under the glaciers of the ,alps1 of ,norway1 and of ,greenland4 ,again1 ,i would remark that ,mr4 ,mackintosh has ignored all the evidence which has been brought forward from time to time to demonstrate the sub-glacial origin of boulder-clay1 and to prove the utter insufficiency of floating-ice to account for the phenomena4 ,and he adduces no new facts in support of the now discredited iceberg theory1 unless it be his statement that flat striated rock-surfaces 7such as those near ,birkenhead7 have been caused by floating-ice--the dome-shaped roches moutonnes being1 on the other hand the work of land-ice4 ,as a matter of personal observation1 ,i can assure ,mr4 ,mackintosh that flat striated surfaces are by no means uncommonly associated in one and the same region with roches moutonnes4 ,what are roches moutonnes but the rounded relics of what were formerly rough uneven tors1 projecting bosses1 and prominent rocks8 ,the general tendency of glacial action is to reduce the asperities of a land-surface2 hence projecting points are rounded off1 while flat surfaces are simply1 as a rule1 planed smoother4 ,mr4 ,mackintosh might traverse acres of such smoothed rock-surfaces in regions where the strata are comparatively horizontal--for example1 in the case of the basaltic plateaux of the ,fares and of ,iceland1 which have certainly been glaciated by land-ice4 ,similar flat glaciated surfaces are met with again and again both in the ,highlands and ,lowlands of ,scotland1 occupying positions and associated with roches moutonnes and till of such a character as to prove beyond any doubt that they no less certainly are the result of the action of land-ice4 ,but it is needless to discuss the probability or possibility of glaciation of any kind being due to floating-ice4 ,we know that glaciers can and do polish and striate rock-surfaces2 no one1 however1 can say the same of icebergs3 and until some one can prove to us that icebergs have performed this feat1 or can furnish us with well-considered reasons for believing them to be capable of it1 glacialists will continue sceptical4 ,but leaving these and other points which serve to show the weakness of the cause which ,mr4 ,mackintosh supports with such keen enthusiasm1 ,i may1 in conclusion1 draw attention to certain very remarkable theoretical views of his which seem to me to be not only self-contradictory1 but opposed to well-known natural laws4 ,briefly stated1 his general view is that the erratics of the west of ,england have been distributed by floating-ice during a period of submergence--the scattering of erratics and the accumulation of the associated glacial deposits having commenced at or about the time when the land began to sink1 and continued until the submergence reached some #bjjj feet below the present sea-level4 ,in applying this hypothesis to explain the phenomena1 ,mr4 ,mackintosh makes rather free use of sea-currents and winds4 ,for example1 he holds that a current coming from ,criffel carried with it boulder-laden ice which flowed south-west to the ,isle of ,man1 south to north ,wales1 and south-east in the direction of ,blackpool and ,manchester1 ,liverpool and ,wolverhampton1 ,dawpool and ,church ,stretton4 ,now1 in the first place1 it is very strange that there is not a vestige or trace of any such submergence1 either in the neighbourhood of ,criffel itself or in the region to the north of it4 ,the whole of that region has been striated and rubbed by land-ice coming down from the watershed of the ,galloway mountains1 to the north of which the stri1 roches moutonnes1 and tracks followed by erratics1 indicate an ice-flow towards the north-west1 north1 and north-east4 ,it is1 therefore1 absolutely certain that at the time the granite erratics are supposed to have sailed away from ,criffel on floating-ice1 the whole of the ,southern ,uplands of ,scotland were covered with a great ice-field extending from ,wigtown to ,berwickshire2 so that1 according to ,mr4 ,mackintosh's hypothesis1 we should be forced to believe that an ocean-current originated in ,criffel itself6 ,but waiving this and other insuperable objections which will occur to any geologist who is familiar with the glacial phenomena of the south of ,scotland1 and confining myself to the evidence supplied by the ,english drifts1 ,i would remark that ,mr4 ,mackintosh's hypothesis is not consistent with itself4 ,a current flowing in the direction supposed could not possibly have permitted floating-ice to sail from ,cumbria to the ,isle of ,man1 to ,moel-y-,tryfane and ,colwyn ,bay4 ,mr4 ,mackintosh admits this himself1 but infers that the transport of the ,cumbrian erratics may have taken place at a different time4 ,but how could this be1 seeing that the ,criffel and ,cumbrian erratics occur side by side in one and the same deposit8 ,again1 the hypothesis of an ocean-current coming from ,criffel is inconsistent with the presence of the ,irish chalk-flints in the drifts of the west of ,england4 ,did these also come at a different time8 ,and what about the dispersion of erratics from ,great ,arenig1 which have gone north-east and north-north-east1 almost exactly in the face of the supposed ,criffel current8 ,here an ocean-current is obviously out of the question2 and accordingly we are told that this dispersion of ,welsh boulders was probably the result of wind4 ,but why should this wind have propelled the floating-ice so far and no further in an easterly direction8 ,surely if floating-ice was swept outwards from ,great ,arenig as far as ,eryrys1 bergs must have been carried now and again much further to the east4 ,and if they did not sail eastwards1 what became of them8 ,did they all melt away immediately when they came into the ice-laden current that flowed towards the south-east8,y ,a still greater difficulty remains4 ,the ,criffel and ,cumbrian erratics suddenly cease when they are followed to the south1 great quantities of them being accumulated over a belt of country extending from beyond ,wolverhampton to ,bridgenorth4 ,what was it that defined the southern limits of these northern boulders8 ,it is clear that it could not have been high-ground1 for the ,severn valley1 not to speak of low-lying regions further to the north-east1 must have been submerged according to ,mr4 ,mackintosh's hypothesis4 ,there was therefore plenty of sea-room for the floating-ice to escape southwards4 ,and yet1 notwithstanding this1 vast multitudes of bergs and floes1 as soon as they arrived at certain points1 suddenly melted away and dropt their burdens6 ,in what region under the sun does anything like that happen at the present day8 ,mr4 ,mackintosh thinks that the more or less sharply-defined boundary-line reached by the erratics could only have resulted from close proximity to a persistent current of water 7or air87 sufficiently warm to melt the boulder-laden ice4 ,he does not tell us1 however1 where this warm current of water or air came from1 or in what direction it travelled4 ,he forgets some of his own facts connected with the appearance of erratics of eastern derivation1 and which1 according to him1 point to an ocean-current that flowed across from ,lincolnshire into the very sea in which the ,criffel granite and ,cumbrian boulders were being dropt4 ,the supposed warm ocean-current1 then1 if such it was rather than air1 could hardly have come from the east4 ,neither is it at all likely that it could have come from the west1 sheltered as the region of the ,severn valley must have been by the ice-laden mountains of ,wales4 ,again1 the south is shut to us2 for there are no erratics in the south of ,england from which to infer a submergence of that district4 ,if it be true that all the northern erratics which are scattered over the low-grounds of ,england1 ,denmark1 ,holland1 ,germany1 ,poland1 and ,russia1 owe their origin to boulder-laden ice carried by ocean-currents1 no such warm water as ,mr4 ,mackintosh desiderates could possibly have come from the east or south-east4 ,we are left1 then1 to infer that the supposed warm current,z must have flowed up the ,severn valley directly in the face of the ,criffel current1 underneath which it suddenly plunged at a high temperature1 the line of junction between it and the cold water being sharply defined1 and retaining its position unchanged for a long period of time6 ,however absurd this conclusion may be1 it is forced upon us if we admit the hypothesis at present under review4 ,for we must remember that the floating-ice is supposed to have melted whenever it came into contact with the warm current4 ,the erratics occur up to a certain boundary-line1 where they are concentrated in enormous numbers1 and south of which they do not appear4 ,here1 then1 large and small floes alike must have vanished at once6 ,certainly a very extraordinary case of dissolution4 ,y ,mr4 ,mackintosh says nothing about the carry or direction of the erratics in west and south ,wales4 ,were the paths of these erratics delineated upon a map1 we should find it necessary to suppose that the wind- or sea-current by which the floating-ice was propelled had flowed outwards in all directions from the dominant heights6 ,z ,it must have likewise flowed in more or less direct opposition to the current which1 in accordance with the iceberg hypothesis1 transported boulders southwards from the high-grounds of south ,wales6 ,if we dismiss the notion of a warm ocean-current for that of a warm wind1 we do not improve our position a whit4 ,where did the warm wind come from8 ,not1 certainly1 from the ice-laden seas to the east4 ,are we to suppose1 then1 that it flowed in from the south or south-west8 ,if so1 we might well ask how it came to pass that in the immediate proximity of such a very warm wind as the hypothesis demands1 great snow-fields and glaciers were allowed to exist in ,wales8 ,passing that objection1 we have still to ask how this wind succeeded in melting large and small masses of floating-ice with such rapidity that it prevented any of them ever trespassing south of a certain line8 ,it is obvious that it must have been an exceedingly hot wind2 and that1 just as the hypothetical warm ocean-current must have suddenly dived under the cold water coming from the north1 so the hot wind1 after passing over the surface of the sea until it reached a certain more or less well-defined line1 must have risen all at once and flowed vertically upwards into the cold regions above4 ,thus1 in seeking to escape from what he doubtless considers the erroneous and extravagant views of land-glacialists1 ,mr4 ,mackintosh adopts a hypothesis which lands him in self-contradictions and a perfect sea of troubles--a kind of chaos1 in fact4 ,in attempting to explain the drifts of western ,england and east ,wales he has ignored the conditions that must have obtained in contiguous regions--thus forgetting that nothing in the world is single1 and that one ought not to infer physical conditions for one limited area without stopping to inquire whether these are in consonance with what is known of adjacent districts1 or in harmony with the existing phenomena of nature4 ,i have so strongly opposed ,mr4 ,mackintosh's explanation of the sudden termination of the northern erratics in the neighbourhood of ,wolverhampton and elsewhere1 that perhaps ,i ought to offer an explanation of my own1 that it may1 in its turn1 undergo examination4 ,i labour under the disadvantage1 however1 of not having studied the drifts in and around ,wolverhampton1 etc41 and the suggestion which ,i shall throw out must therefore be taken for what it is worth4 ,it seems to me1 then1 that the concentration of boulders in the neighbourhood of ,wolverhampton1 and the limits reached by the northern erratics generally1 mark out1 in all probability1 the line of junction between the mer de glace coming from the basin of the ,irish ,sea and that flowing across the country from the vast mer de glace that occupied the basin of the ,german ,ocean4 ,along this line the southerly transport of the northern boulders would cease1 and here they would therefore tend to become concentrated4 ,but it is most likely that now and again they would get underneath the ice-flow that set down the ,severn valley1 and ,i should anticipate that they will yet be detected1 along with erratics of eastern origin1 as far south even as the ,bristol ,channel4 ,if it be objected to this view that erratics from ,great ,arenig have been met with south of ,wolverhampton1 at ,birmingham and ,bromsgrove1 ,i would reply that these erratics were probably carried south either before or after the general mer de glace had attained its climax--at a period when the ,welsh ice was able to creep out further to the east than it could when the invasion of the ,north ,sea ice was at its height4 ,i cannot conclude this paper without expressing my admiration for the long-continued and successful labours of the well-known geologist whose views ,i have been controverting4 ,although ,i have entered my protest against his iceberg hypothesis1 and have freely criticised his theoretical opinions1 ,i most willingly admit that the practical results of his unwearied devotion to the study of those interesting phenomena with which he is so familiar have laid all his fellow-workers under a debt of gratitude4 ,,viii4 ,recent ,researches in the ,glacial ,geology of the ,continent4,,aa ,,aa ,presidential ,address to the ,geological ,section of the ,british ,association1 ,newcastle1 #ahhi4 ,,the ,president of this section must often have some difficulty in selecting a subject for his address4 ,it is no longer possible to give an interesting and instructive summary of the work done by the devotees of our science during even one year4 ,so numerous have the students of geological science become--so fertile are the fields they cultivate--so abundant the harvests they reap1 that one in my present position may well despair of being able to take stock of the numerous additions to our knowledge which have accumulated within the last twelve months4 ,neither is there any burning question which at this time your ,president need feel called upon to discuss4 ,true1 there are controversies that are likely to remain unsettled for years to come--there are still not a few matters upon which we must agree to differ--we do not yet see eye to eye in all things geological4 ,but experience has shown that as years advance truth is gradually evolved1 and old controversies die out1 and so doubtless it will continue to be4 ,the day when controversies shall cease1 however1 is yet1 ,i hope1 far in the future2 for should that dull and unhappy time ever arrive1 it is quite certain that mineralogists1 petrologists1 palontologists1 and geologists shall have died out of the world4 ,following the example of many of my predecessors1 ,i shall confine my remarks to certain questions in which ,i have been specially interested2 and in doing so ,i shall endeavour to steer clear1 as far as ,i can1 of controversial matters4 ,my purpose1 then1 is to give an outline of some of the results obtained during the last few years by ,continental workers in the domain of glacial geology4 ,those who are not geologists will probably smile when they hear one declare that wielders of the hammer are extremely conservative--that they are slow to accept novel views1 and very tenacious of opinions which have once found favour in their eyes4 ,nevertheless1 such is the case1 and well for us that it is so4 ,however captivating1 however imposing1 however strongly supported by evidence a new view may appear to be1 we do well to criticise1 to sift the evidence1 and to call for more facts and experiments1 if such are possible1 until the proofs become so strong as to approach as near a demonstration as geologists can in most cases expect such proofs to go4 ,the history of our science1 and indeed of most sciences1 affords abundant illustration of what ,i say4 ,how many long years were the views of sub-arial erosion1 as taught by ,hutton and ,playfair1 canvassed and controverted before they became accepted6 ,and even after their general soundness had been established1 how often have we heard nominal disciples of these fathers of physical geology refuse to go so far as to admit that the river-valleys of our islands have been excavated by epigene agents6 ,if1 as a rule1 it takes some time for a novel view to gain acceptance1 it is equally true that views which have long been held are only with difficulty discarded4 ,between the new and the old there is a constant struggle for existence1 and if the latter should happen to survive1 it is only in a modified form4 ,i have often thought that a history of the evolution of geological theories would make a very entertaining and instructive work4 ,we should learn from it1 amongst other things1 that the advance of our science has not always been continuous--now and again1 indeed1 it has almost seemed as if the movement had been retrograde4 ,knowledge has not come in like an overwhelming flood--as a broad majestic river--but rather like a gently-flowing tide1 now advancing1 now retiring1 but ever1 upon the whole1 steadily gaining ground4 ,the history ,i speak of would also teach us that many of the general views and hypotheses which have been from time to time abandoned as unworkable1 are hardly deserving of the reproach and ridicule which we in these latter days may be inclined to cast upon them4 ,as the ,scots proverb says3 ,it is easy to be wise behindhand4 ,it could be readily shown that not a few discarded notions and opinions have frequently worked for good1 and have rather stimulated than checked inquiry4 ,such reflections should be encouraging to every investigator1 whether he be a defender of the old or an advocate of the new4 ,time tries all1 and each worker may claim a share in the final establishment of the truth4 ,perhaps there is no department of geological inquiry that has given rise to more controversy than that which ,i have selected for the subject of this address4 ,hardly a single step in advance has been taken without vehement opposition4 ,but the din of contending sides is not so loud now--the dust of the conflict has to some extent cleared away1 and the positions which have been lost or maintained1 as the case may be1 can be readily discerned4 ,the glacialist who can look back over the last twenty-five years of wordy conflict has every reason to be jubilant and hopeful4 ,many of those who formerly opposed him have come over to his side4 ,it is true he has not had everything his own way4 ,some extreme views have been abandoned in the struggle2 that of a great ,polar ice-sheet1 for example1 as conceived of by ,agassiz4 ,i am not aware1 however1 that many serious students of glacial geology ever adopted that view4 ,but it was quite an excusable hypothesis1 and has been abundantly suggestive4 ,had ,agassiz lived to see the detailed work of these later days1 he would doubtless have modified his notion and come to accept the view of large continental glaciers which has taken its place4 ,the results obtained by geologists who have been studying the peripheral areas of the drift-covered regions of our ,continent1 are such as to satisfy us that the drifts of those regions are not iceberg-droppings1 as we used to suppose1 but true morainic matter and fluvio-glacial detritus4 ,geologists have not jumped to this conclusion--they have only accepted it after laborious investigation of the evidence4 ,since ,dr4 ,otto ,torell1 in #ahge1 first stated his belief that the ,diluvium of north ,germany was of glacial origin a great literature on the subject has sprung up1 a perusal of which will show that with our ,german friends glacial geology has passed through much the same succession of controversial phases as with us4 ,at first icebergs are appealed to as explaining everything--next we meet with sundry ingenious attempts at a compromise between floating-ice and a continuous ice-sheet4 ,as observations multiply1 however1 the element of floating-ice is gradually eliminated1 and all the phenomena are explained by means of land-ice and ,schmelz-wasser alone4 ,it is a remarkable fact that the iceberg hypothesis has always been most strenuously upheld by geologists whose labours have been largely confined to the peripheral areas of drift-covered countries4 ,in the upland and mountainous tracts1 on the other hand1 that hypothesis has never been able to survive a moderate amount of accurate observation4 ,even in ,switzerland--the land of glaciers--geologists at one time were of opinion that the boulder-clays of the low-grounds had a different origin from those which occur in the mountain-valleys4 ,thus1 it was supposed that at the close of the ,pleistocene period the ,alps were surrounded by great lakes or by gulfs of some inland sea1 into which the glaciers of the high valleys flowed and calved their icebergs--these latter scattering erratics and earthy dbris over the drowned areas4 ,sartorius von ,waltershausen,,ab set forth this view in an elaborate and well-illustrated paper4 ,unfortunately for his hypothesis no trace of the supposed great lakes or the inland sea has ever been detected3 on the contrary1 the character of the morainic accumulations1 and the symmetrical grouping and radiation of the erratics and perched blocks over the foot-hills and low-grounds1 show that these last have been invaded and overflowed by the glaciers themselves4 ,even the most strenuous upholders of the efficacy of icebergs as originators of some boulder-clays1 admit that the boulder-clay or till1 of what we may call the inner or central region of a glaciated tract is the product of land-ice4 ,under this category comes the boulder-clay of ,norway1 ,sweden1 and ,finland1 and of the ,alpine ,lands of central ,europe1 not to speak of the hilly parts of our own islands4 ,,ab ,untersuchungen ber die ,klimate der ,gegenwart und der ,vorwelt1 etc4--,natuurkundige ,verhandelingen v4 d4 ,holland4 ,maatsch4 d4 ,wetensch4 te ,haarlem1 #ahfe4 ,when we come to study the drifts of the peripheral areas1 it is not difficult to see why these should be considered to have had a different origin4 ,they present certain features which1 although not absent from the glacial deposits of the inner region1 are not nearly so characteristic of such upland tracts4 ,i refer especially to the frequent interstratification of boulder-clays with well-bedded deposits of clay1 sand1 and gravel2 and to the fact that these boulder-clays are often less compressed than those of the inner region1 and have even occasionally a silt-like character4 ,such appearances do seem at first to be readily explained on the assumption that the deposits have been accumulated in water opposite the margin of a continental glacier or ice-sheet--and this was the view which several able investigators in ,germany were for some time inclined to adopt4 ,but when the phenomena came to be studied in greater detail1 and over a wider area1 this preliminary hypothesis did not prove satisfactory4 ,it was discovered1 for example1 that giants' kettles,,ac were more or less commonly distributed under the glacial deposits1 and such kettles could only have originated at the bottom of a glacier4 ,again1 it was found that pre-glacial accumulations were plentifully developed in certain places below the drift1 and were often involved with the latter in a remarkable way4 ,the brown-coal formation in like manner was violently disturbed and displaced1 to such a degree that frequently the boulder-clay is found to underlie it4 ,similar phenomena were encountered in regions where the drift overlies the ,chalk--the latter presenting the appearance of having been smashed and shattered--the fragments having often been dragged some distance1 so as to form a kind of friction-breccia underlying the drift1 while large masses are often included in the clay itself4 ,all the facts pointed to the conclusion that these disturbances were due to tangential thrusting or crushing1 and were not the result of vertical displacements1 such as are produced by normal faulting1 for the disturbances in question die out from above downwards4 ,evidence of similar thrusting or crushing is seen in the remarkable faults and contortions that so often characterise the clays and sands that occur in the boulder-clay itself4 ,the only agent that could produce the appearances1 now briefly referred to1 is land-ice1 and we must therefore agree with ,german geologists that glacier-ice has overflowed all the drift-covered regions of the peripheral area4 ,no evidence of marine action in the formation of the stony clays is forthcoming--not a trace of any sea-beach has been detected4 ,and yet1 if these clays had been laid down in the sea during the retreat of the ice-sheet from ,germany1 surely such evidence as ,i have indicated ought to be met with4 ,to the best of my knowledge the only particular facts which have been appealed to1 as proofs of marine action1 are the appearance of bedded deposits in the boulder-clays1 and the occasional occurrence in the clays themselves of a sea-shell4 ,but other organic remains are also met with now and again in similar positions1 such as mammalian bones and freshwater shells4 ,all these1 however1 have been shown to be derivative in their origin--they are just as much erratics as the stones and boulders with which they are associated4 ,the only phenomena1 therefore1 that the glacialist has to account for are the bedded deposits which occur so frequently in the boulder-clays of the peripheral regions1 and the occasional silty and uncompressed character of the clays themselves4 ,,ac ,these appear to have been first detected by ,professor ,berendt and ,professor ,e4 ,geinitz4 ,the intercalated beds are1 after all1 not hard to explain4 ,if we consider for a moment the geographical distribution of the boulder-clays1 and their associated aqueous deposits1 we shall find a clue to their origin4 ,speaking in general terms1 the stony clays thicken out as they are followed from the mountainous and high-lying tracts to the low-grounds4 ,thus they are of inconsiderable thickness in ,norway1 the higher parts of ,sweden1 and in ,finland1 just as we find is the case in ,scotland1 northern ,england1 ,wales1 and the hilly parts of ,ireland4 ,traced south from the uplands of ,scandinavia and ,finland1 they gradually thicken out as the low-grounds are approached4 ,thus in southern ,sweden they reach a thickness of #dc metres or thereabout1 and of #hj metres in the northern parts of ,prussia1 while over the wide low-lying regions to the south they attain a much greater thickness--reaching in ,holstein1 ,mecklenburg1 ,pomerania1 and west ,prussia1 a depth of #abj to #adj metres1 and still greater depths in ,hanover1 ,mark ,brandenburg1 and ,saxony4 ,in those regions1 however1 a considerable portion of the diluvium consists1 as we shall see presently1 of water-formed beds4 ,the geographical distribution of the aqueous deposits1 which are associated with the stony clays1 is somewhat similar4 ,they are very sparingly developed in districts where the boulder-clays are thin4 ,thus they are either wanting1 or only occur sporadically in thin irregular beds1 in the high-grounds of northern ,europe generally4 ,further south1 however1 they gradually acquire more importance1 until in the peripheral regions of the drift-covered tracts they come to equal and eventually to surpass the boulder-clays in prominence4 ,these latter1 in fact1 at last cease to appear1 and the whole bulk of the diluvium1 along the southern margin of the drift area1 appears to consist of aqueous accumulations alone4 ,the explanations of these facts advanced by ,german geologists are quite in accordance with the views which have long been held by glacialists elsewhere1 and have been tersely summed up by ,dr4 ,jentzsch4,,ad ,the northern regions1 he says1 were the feeding-grounds of the inland-ice4 ,in those regions melting was at a minimum1 while the grinding action of the ice was most effective4 ,here1 therefore1 erosion reached its maximum--ground-moraine or boulder-clay being unable to accumulate to any thickness4 ,further south melting greatly increased1 while ground-moraine at the same time tended to accumulate--the conjoint action of glacier-ice and sub-glacial water resulting in the complex drifts of the peripheral area4 ,in the disposition and appearance of the aqueous deposits of the diluvium we have evidence of an extensive sub-glacial water-circulation--glacier-mills that gave rise to giants' kettles--chains of sub-glacial lakes in which fine clays gathered--streams and rivers that flowed in tunnels under the ice1 and whose courses were paved with sand and gravel4 ,nowhere do ,german geologists find any evidence of marine action4 ,on the contrary1 the dovetailing and interosculation of boulder-clay with aqueous deposits are explained by the relation of the ice to the surface over which it flowed4 ,throughout the peripheral area it did not rest so continuously upon the ground as was the case in the inner region of maximum erosion4 ,in many places it was tunnelled by rapid streams and rivers1 and here and there it arched over sub-glacial lakes1 so that accumulation of ground-moraine proceeded side by side with the formation of aqueous sediments4 ,much of that ground-moraine is of the usual tough and hard-pressed character1 but here and there it is somewhat less coherent and even silt-like4 ,now a study of the ground-moraines of modern glaciers affords us a reasonable explanation of such differences4 ,dr4 ,brckner,,ae has shown that in many places the ground-moraine of the ,alpine glaciers is included in the bottom of the ice itself4 ,the ground-moraine1 he says1 frequently appears as an ice-stratum abundantly impregnated with silt and rock-fragments--it is like a conglomerate or breccia which has ice for its binding material4 ,when this ground-moraine melts out of the ice--no running water being present--it forms a layer of unstratified silt or clay1 with stones scattered irregularly through it4 ,such being the case in modern glaciers1 we can hardly doubt that over the peripheral areas occupied by the old northern ice-sheet boulder-clay must frequently have been accumulated in the same way4 ,nay1 when the ground-moraine melted out and dropt here and there into quietly-flowing water it might even acquire in part a bedded character4 ,,ad ,jahrb4 d4 knigl4 preuss4 geologischen ,landesanstalt fr #ahhd1 p4 #dch4 ,,ae ,die ,vergletscherung des ,salzachgebietes1 etc43 ,geographische ,abhandlungen herausgegeben v4 ,a4 ,penck1 ,band i4 ,heft #a4 ,the limits reached by the inland-ice during its greatest extension are becoming more and more clearly defined1 although its southern margin will probably never be so accurately determined as that of the latest epoch of general glaciation4 ,the reasons for this are obvious4 ,when the inland-ice flowed south to the ,harz and the hills of ,saxony it formed no great terminal moraines4 ,doubtless many erratics and much rock-rubbish were showered upon the surface of the ice from the higher mountains of ,scandinavia1 but owing to the fanning-out of the ice on its southward march1 such superficial dbris was necessarily spread over a constantly-widening area4 ,it may well be doubted1 therefore1 whether it ever reached the terminal front of the ice-sheet in sufficient bulk to form conspicuous moraines4 ,it seems most probable that the terminal moraines of the great inland-ice would consist of low banks of boulder-clay and aqueous materials-the latter1 perhaps1 strongly predominating1 and containing here and there larger and smaller angular erratics which had travelled on the surface of the ice4 ,however that may be1 it is certain that the whole region in question has been considerably modified by subsequent denudation1 and to a large extent is now concealed under deposits belonging to later stages of the ,pleistocene period4 ,the extreme limits reached by the ice are determined rather by the occasional presence of rock-stri and roches moutonnes1 of boulder-clay and northern erratics1 than by recognisable terminal moraines4 ,the southern limits reached by the old inland-ice appear in this way to have been tolerably well ascertained over a considerable portion of central ,europe4 ,some years ago ,i published a small sketch-map,,af showing the extent of surface formerly covered by ice4 ,on this map ,i did not venture to draw the southern margin of the ice-sheet in ,belgium further south than ,antwerp1 where northern erratics were known to occur1 but the more recent researches of ,belgian geologists show that the ice probably flowed south for some little distance beyond ,brussels4,,ag ,here and there in other parts of the ,continent the southern limits reached by the northern drift have also been more accurately determined1 but1 so far as ,i know1 none of these later observations involves any serious modification of the sketch-map referred to4 ,,af ,prehistoric ,europe1 #ahha4 ,,ag ,see a paper by ,m4 ,e4 ,delvaux3 ,ann4 de la4 ,soc4 gol4 de ,belg41 t4 xiii4 p4 #aeh4 ,i have now said enough1 however1 to show that the notion of a general ice-sheet having covered so large a part of ,europe1 which a few years ago was looked upon as a wild dream1 has been amply justified by the labours of those who are so assiduously investigating the peripheral areas of the great northern drift4 ,and perhaps ,i may be allowed to express my own belief that the drifts of middle and southern ,england1 which exhibit the same complexity as the ,lower ,diluvium of the ,continent1 will eventually be generally acknowledged to have had a similar origin4 ,i have often thought that whilst politically we are happy in having the sea all round us1 geologically we should have gained perhaps by its greater distance4 ,at all events we should have been less ready to invoke its assistance to explain every puzzling appearance presented by our glacial accumulations4 ,i now pass on to review some of the general results obtained by continental geologists as to the extent of area occupied by inland-ice during the last great extension of glacier-ice in ,europe4 ,it is well known that this latest ice-sheet did not overflow nearly so wide a region as that underneath which the lowest boulder-clay was accumulated4 ,this is shown not only by the geographical distribution of the youngest boulder-clay1 but by the direction of rock-stri1 the trend of erratics1 and the position of well-marked terminal moraines4 ,gerard de ,geer has given a summary,,ah of the general results obtained by himself and his fellow-workers in ,sweden and ,norway2 and these have been supplemented by the labours of ,berendt1 ,e4 ,geinitz1 ,hauchecorne1 ,keilhack1 ,klockmann1 ,schrder1 ,wahnschaffe1 and others in ,germany1 and by ,sederholm in ,finland4,,ai ,from them we learn that the end-moraines of the ice circle round the southern coasts of ,norway1 from whence they sweep south-east by east across the province of ,gottland in ,sweden1 passing through the lower ends of ,lakes ,wener and ,wetter1 while similar moraines mark out for us the terminal front of the inland-ice in ,finland--at least two parallel frontal moraines passing inland from ,hango ,head on the ,gulf of ,finland through the southern part of that province to the north of ,lake ,ladoga4 ,further north-east than this they have not been traced2 but1 from some observations by ,helmersen1 ,sederholm thinks it probable that the terminal ice-front extended north-east by the north of ,lake ,onega to the eastern shores of the ,white ,sea4 ,between ,sweden and ,finland lies the basin of the ,baltic1 which at the period in question was filled with ice1 forming a great ,baltic glacier which overflowed the land ,islands1 ,gottland1 and land1 and which1 fanning-out as it passed towards the south-west1 invaded1 on the south side1 the ,baltic provinces of ,germany1 while1 on the north1 it crossed the southern part of ,scania in ,sweden and the ,danish islands to enter ,jutland4 ,,ah ,zeitschrift d4 deutsch4 geolog4 ,ges41 ,bd4 xxxvii41 p4 #agg4 ,,ai ,for papers by ,berendt and his associates see especially the ,jahrbuch d4 k4 preuss4 geol4 ,landesanstalt1 and the ,zaitschr4 d4 deutsch4 geol4 ,ges4 for the past few years4 ,geinitz3 ,forsch4 z4 d4 ,lands- u4 ,volkskunde1 i4 #e2 ,leopoldina1 xxii41 p4 #cg2 ,i4 ,beitrag z4 ,geologie ,mecklenburgs1 #ahhj1 pp4 #df1 #ef4 ,sederholm3 ,fennia1 ,i4 ,no4 #g4 ,the upper boulder-clay of those regions is now recognised as the ground-moraine of this latest ice-sheet4 ,in many places it is separated from the older boulder-clay by interglacial deposits--some of which are marine1 while others are of freshwater and terrestrial origin4 ,during interglacial times the sea that overflowed a considerable portion of north ,germany was evidently continuous with the ,north ,sea1 as is shown not only by the geographical distribution of the interglacial marine deposits1 but by their ,north ,sea fauna4 ,german geologists generally group all the interglacial deposits together1 as if they belonged to one and the same interglacial epoch4 ,this perhaps we must look upon as only a provisional arrangement4 ,certain it is that the freshwater and terrestrial beds which frequently occur on the same or a lower level1 and at no great distance from the marine deposits1 cannot in all cases be contemporaneous with the latter4 ,possibly1 however1 such discordances may be accounted for by oscillations in the level of the interglacial sea--land and water having alternately prevailed over the same area4 ,two boulder-clays1 as we have seen1 have been recognised over a wide region in the north of ,germany4 ,in some places1 however1 three or more such boulder-clays have been observed overlying one another throughout considerable areas1 and these clays are described as being distinctly separate and distinguishable the one from the other4,,aj ,whether they1 with their intercalated aqueous deposits1 indicate great oscillations of one and the same ice-sheet--now advancing1 now retreating--or whether the stony clays may not be the ground-moraines of so many different ice-sheets1 separated the one from the other by true interglacial conditions1 future investigations must be left to decide4 ,,aj ,h4 ,schrder3 ,jahrb4 d4 k4 preuss4 geol4 ,landesanstalt fr #ahhg 1 p4 #cfj4 ,the general conclusions arrived at by those who are at present investigating the glacial accumulations of northern ,europe may be summarised as follows3-- #a4 ,before the invasion of northern ,germany by the inland-ice the low-grounds bordering on the ,baltic were overflowed by a sea which contained a boreal and arctic fauna4 ,these marine conditions are indicated by the presence under the lower boulder-clay of more or less well-bedded fossiliferous deposits4 ,on the same horizon occur also beds of sand1 containing freshwater shells1 and now and again mammalian remains1 some of which imply cold and others temperate climatic conditions4 ,obviously all these deposits may pertain to one and the same period1 or more properly to different stages of the same period--some dating back to a time when the climate was still temperate1 while others clearly indicate the prevalence of cold conditions1 and are therefore probably somewhat younger4 #b4 ,the next geological horizon in ascending order is that which is marked by the ,lower ,diluvium--the glacial and fluvio-glacial detritus of the great ice-sheet which flowed south to the foot of the ,harz ,mountains4 ,the boulder-clay on this horizon now and again contains marine1 freshwater1 and terrestrial organic remains--derived undoubtedly from the so-called pre-glacial beds already referred to4 ,these latter1 it would appear1 were ploughed up and largely incorporated with the old ground-moraine4 #c4 ,the interglacial beds which next succeed contain remains of a well-marked temperate fauna and flora1 which point to something more than a mere partial or local retreat of the inland-ice4 ,the geographical distribution of the beds1 and the presence in these of such forms as ,elephas antiquus1 ,cervus elephas1 ,c4 megaceros1 and a flora comparable to that now existing in northern ,germany1 justify geologists in concluding that the interglacial epoch was one of long duration1 and characterised in ,germany by climatic conditions apparently not less temperate than those that now obtain4 ,one of the phases of that interglacial epoch1 as we have seen1 was the overflowing of the ,baltic provinces by the waters of the ,north ,sea4 #d4 ,to this well-marked interglacial epoch succeeded another epoch of arctic conditions1 when the ,scandinavian inland-ice once more invaded ,germany1 ploughing through the interglacial deposits1 and working these up in its ground-moraine4 ,so far as ,i can learn1 the prevalent belief among geologists in north ,germany is that there was only one interglacial epoch2 but1 as already stated1 doubt has been expressed whether all the facts can be thus accounted for4 ,there must always be great difficulty in the correlation of widely-separated interglacial deposits1 and the time does not seem to me to have yet come when we can definitely assert that all those interglacial beds belong to one and the same geological horizon4 ,i have dwelt upon the recent work of geologists in the peripheral areas of the drift-covered regions of northern ,europe1 because ,i think the results obtained are of great interest to glacialists in this country4 ,and for the same reason ,i wish next to call attention to what has been done of late years in elucidating the glacial geology of the ,alpine ,lands of central ,europe--and more particularly of the low-grounds that stretch out from the foot of the mountains4 ,any observations that tend to throw light upon the history of the complex drifts of our own peripheral areas cannot but be of service4 ,it is quite impossible to do justice in this brief sketch to the labours of the many enthusiastic geologists who within recent years have increased our knowledge of the glaciation of the ,alpine ,lands4 ,at present1 however1 ,i am not so much concerned with the proofs of general glaciation as with the evidence that goes to show how the ,alpine ground-moraines have been formed1 and with the facts which have led certain observers to conclude that the ,alps have endured several distinct glaciations within ,pleistocene times4 ,swiss geologists are agreed that the ground-moraines which clothe the bottoms of the great ,alpine valleys1 and extend outwards sometimes for many miles upon the low-grounds beyond1 are of true glacial origin4 ,now these ground-moraines are closely similar to the boulder-clays of this country and northern ,europe--like them1 they are frequently tough and hard-pressed1 but now and again somewhat looser1 and less firmly coherent4 ,frequently also they contain lenticular beds1 and more or less thick sheets of aqueous deposits--in some places the stony clays even exhibiting a kind of stratification--and ever and anon such water-assorted materials are commingled with stony clay in the most complex manner4 ,these latter appearances are1 however1 upon the whole best developed upon the low-grounds that sweep out from the base of the ,alps4 ,the only question concerning the ground-moraines that has recently given rise to much discussion is the origin of the materials themselves4 ,it is obvious that there are only three possible modes in which those materials could have been introduced to the ground-moraine3 either they consist of superficial morainic dbris which has found its way down to the bottom of the old glaciers by crevasses2 or they may be made up of the rock-rubbish1 shingle1 gravel1 etc41 which doubtless strewed the valleys before these were occupied by ice2 or1 lastly1 they may have been derived in chief measure from the underlying rocks themselves by the action of the ice that overflowed them4 ,the investigations of ,penck1 ,blaas1 ,bhm1 and ,brckner appear to me to have demonstrated that the ground-moraines are composed mostly of materials which have been detached from the underlying rocks by the erosive action of the glaciers themselves4 ,their observations show that the regions studied by them in great detail were almost completely buried under ice--so that the accumulation of superficial moraines was for the most part impossible2 and they advance a number of facts which prove positively that the ground-moraines were formed and accumulated under ice4 ,i cannot here recapitulate the evidence1 but must content myself by a reference to the papers in which this is fully discussed4,,ak ,these geologists do not deny that some of the material may occasionally have come from above1 nor do they doubt that pre-existing masses of rock-rubbish and alluvial accumulations may also have been incorporated with the ground-moraines2 but the enormous extent of the latter1 and the direction of transport and distribution of the erratics which they contain cannot be thus accounted for1 while all the facts are readily explained by the action of the ice itself1 which used its sub-glacial dbris as tools with which to carry on the work of erosion4 ,,ak ,penck3 ,die ,vergletscherung der deutschen ,alpen4 ,blaas3 ,zeitschrift d4 ,ferdinandeums1 #ahhe4 ,bhm3 ,jahrb4 d4 k4 k4 geol4 ,reichsanstalt1 #ahhe1 ,bd4 xxxv41 ,heft #c4 ,brckner3 ,die ,vergletscherung d4 ,salzachgebietes1 etc41 #ahhf4 ,professor ,heim and others have frequently asserted that glaciers have little or no eroding power1 since at the lower ends of existing glaciers we find no evidence of such erosion being in operation4 ,but the chief work of a glacier cannot be carried on at its lower end1 where motion is reduced to a minimum1 and where the ice is perforated by sub-glacial tunnels and arches1 underneath which no glacial erosion can possibly take place2 and yet it is upon observations made in just such places that the principal arguments against the erosive action of glaciers have been based4 ,if all that we could ever know of glacial action were confined to what we can learn from peering into the grottoes at the terminal fronts of existing glaciers1 we should indeed come to the conclusion that glaciers do not erode their rocky beds to any appreciable extent4 ,but as we do not look for the strongest evidence of fluviatile erosion at the mouth of a river1 but in its valley--and mountain-tracks1 so if we wish to learn what glacier-ice can accomplish1 we must study in detail some wide region from which the ice has completely disappeared4 ,when this plan has been followed1 it has happened that some of the strongest opponents of glacial erosion have been compelled by the force of the evidence to go over to the other camp4 ,dr4 ,blaas1 for example1 has been led by his observations on the glacial formations of the ,inn valley to recant his former views1 and to become a formidable advocate of the very theory which he formerly opposed4 ,to his work and the memoirs by ,penck1 ,brckner1 and ,bhm already cited1 and especially to the admirable chapter on glacier-erosion by the last-named author1 ,i would refer those who may be anxious to know the last word on this much-debated question4 ,the evidence of interglacial conditions within the ,alpine lands continues to increase4 ,these are represented by alluvial deposits of silt1 sand1 gravel1 conglomerate1 breccia1 and lignites4 ,penck1 ,bhm1 and ,brckner find evidence of two interglacial epochs1 and maintain that there have been three distinct and separate epochs of glaciation in the ,alps4 ,no mere temporary retreat and re-advance of the glaciers1 according to them1 will account for the various phenomena presented by the interglacial deposits and associated morainic accumulations4 ,during interglacial times the glaciers disappeared from the lower valleys of the ,alps--the climate was temperate1 and probably the snow-fields and glaciers approximated in extent to those of the present day4 ,all the evidence conspires to show that an interglacial epoch was of prolonged duration4 ,dr4 ,brckner has observed that the moraines of the last glacial epoch rest here and there upon lss1 and he confirms ,penck's observations in south ,bavaria that this remarkable formation never overlies the morainic accumulations of the latest glacial epoch4 ,according to ,penck and ,brckner1 therefore1 the lss is of interglacial age4 ,there can be little doubt1 however1 that lss does not belong to any one particular horizon4 ,wahnschaffe,,al and others have shown that throughout wide areas in north ,germany it is the equivalent in age of the ,upper ,diluvium1 while ,schumacher,,am points out that in the ,rhine valley it occurs on two separate and distinct horizons4 ,professor ,andre has likewise shown,,an that there is an upper and lower lss in ,alsace--each characterised by its own special fauna4 ,,al ,abhandl4 z4 geol4 ,specialkarte v4 ,preussen1 etc41 ,bd4 vii4 ,heft #a2 ,zeitschr4 d4 ,zeutsch4 geol4 ,ges41 #ahhe1 p4 #ijd2 #ahhf1 p4 #cfg4 ,,am ,hygienische ,topographie von ,strassburg i4 ,e41 #ahhe4 ,,an ,abhandl4 z4 geol4 ,specialkarte a4 ,elsass-,lothringen1 ,bd4 iv4 ,heft #b4 ,there is still considerable difference of opinion as to the mode of formation of this remarkable accumulation4 ,by many it is considered to be an aqueous deposit2 others1 following ,richthofen1 are of opinion that it is a wind-blown accumulation2 while some incline to the belief that it is partly the one and partly the other4 ,nor do the upholders of these various hypotheses agree amongst themselves as to the precise manner in which water or wind has worked to produce the observed results4 ,thus1 amongst the supporters of the aqueous origin of the lss1 we find this attributed to the action of heavy rains washing over and rearranging the material of the boulder-clays4,,ao ,many1 again1 have held it probable that lss is simply the finest loam distributed over the low-grounds by the flood-waters that escaped from the northern inland-ice and the mers de glace of the ,alpine lands of central ,europe4 ,another suggestion is that much of the material of the lss may have been derived from the denudation of the boulder-clays by flood-water1 during the closing stages of the last cold period4 ,it is pointed out that in some regions1 at least1 the lss is underlaid by a layer of erratics1 which are believed to be the residue of the denuded boulder-clay4 ,we are reminded by ,klockmann,,ap and ,wahnschaffe,,aq that the inland-ice must have acted as a great dam1 and that wide areas in ,germany1 etc41 would be flooded1 partly by water derived from the melting inland-ice1 and partly by waters flowing north from the hilly tracts of middle ,germany4 ,in the great basins thus formed there would be a commingling of fine silt material derived from north and south1 which would necessarily come to form a deposit having much the same character throughout4 ,,ao ,laspeyres3 ,erluterungen z4 geol ,specialkaret v ,preussen1 etc41 ,blatt4 ,grbzig1 ,zrbig1 und ,petersberg4 ,,ap ,klockmann3 ,jahrb4 d4 k4 preuss4 geol4 ,landesanstalt fr #ahhc1 p4 #bfb4 ,,aq ,wahnschaffe3 ,op4 cit41 and ,zeitschr4 d4 deutsch4 geol4 ,ges41 #ahhf1 p4 #cfg4 ,from what ,i have myself seen of the lss in various parts of ,germany1 and from all that ,i have gathered from reading and in conversation with those who have worked over lss-covered regions1 ,i incline to the opinion that lss is for the most part of aqueous origin4 ,in many cases this can be demonstrated1 as by the occurrence of bedding and the intercalation of layers of stones1 sand1 gravel1 etc41 in the deposit2 again1 by the not infrequent appearance of freshwater shells2 but1 perhaps1 chiefly by the remarkable uniformity of character which the lss itself displays4 ,it seems to me reasonable also to believe that the flood-waters of glacial times must needs have been highly charged with finely-divided sediment1 and that such sediment would be spread over wide regions in the low-grounds--in the slackwaters of the great rivers and in the innumerable temporary lakes which occupied1 or partly occupied1 many of the valleys and depressions of the land4 ,there are different kinds of lss or lss-like deposits1 however1 and all need not have been formed in the same way4 ,probably some may have been derived1 as ,wahnschaffe has suggested1 from denudation of boulder-clay4 ,possibly also1 some lss may owe its origin to the action of rain on the stony clays1 producing what we in this country would call rain-wash4 ,there are other accumulations1 however1 which no aqueous theory will satisfactorily explain4 ,under this category comes much of the so-called ,berglss1 with its abundant land-shells1 and its generally unstratified character4 ,it seems likely that such lss is simply the result of sub-arial action1 and owes its origin to rain1 frost1 and wind acting upon the superficial formations1 and rearranging their finer-grained constituents4 ,and it is quite possible that the upper portion of much of the lss of the lower-grounds may have been re-worked in the same way4 ,but ,i confess ,i cannot yet find in the facts adduced by ,german geologists any evidence of a dry-as-dust epoch having obtained in ,europe during any stage of the ,pleistocene period4 ,the geographical position of our ,continent seems to me to forbid the possibility of such climatic conditions1 while all the positive evidence we have points to humidity rather than dryness as the prevalent feature of ,pleistocene climates4 ,it is obvious1 however1 that after the flood-waters had disappeared from the low-grounds of the ,continent1 sub-arial action would come into play over the wide regions covered by the glacial and fluvio-glacial deposits4 ,thus1 in the course of time1 these deposits would become modified1--just as similar accumulations in these islands have been top-dressed1 as it were1 and to some extent even rearranged4 ,i am strengthened in these views by the conclusions arrived at by ,m4 ,falsan--the eminent ,french glacialist4 ,covering the plateaux of the ,dombes1 and widely spread throughout the valleys of the ,rhone1 the ,ain1 the ,isre1 etc41 in ,france there is a deposit of lss1 he says1 which has been derived from the washing of the ancient moraines4 ,at the foot of the ,alps1 where black schists are largely developed1 the lss is dark grey1 but west of the secondary chain the same deposit is yellowish1 and composed almost entirely of silicious materials1 with only a very little carbonate of lime4 ,this limon or lss1 however1 is very generally modified towards the top by the chemical action of rain--the yellow lss acquiring a red colour4 ,sometimes it is crowded with calcareous concretions1 but at other times it has been deprived of its calcareous element and converted into a kind of pulverulent silica or quartz4 ,this1 the true lss1 is distinguished from another lehm1 which ,falsan recognises as the product of atmospheric action--formed1 in fact1 in situ1 from the disintegration and decomposition of the subjacent rocks4 ,even this lehm has been modified by running water--dispersed or accumulated locally1 as the case may be4,,ar ,,ar ,falsan3 ,la ,priode glaciaire1 p4 #ha4 ,all that we know of the lss and its fossils compels us to include this accumulation as a product of the ,pleistocene period4 ,it is not of post-glacial age--even much of what one may call the remodified lss being of late ,glacial or ,pleistocene age4 ,i cannot attempt to give here a summary of what has been learned within recent years as to the fauna of the lss4 ,the researches of ,nehring and ,liebe have familiarised us with the fact that1 at some particular stage in the ,pleistocene period1 a fauna like that of the alpine steppe-lands of western ,asia was indigenous to middle ,europe1 and the recent investigations by ,woldrich have increased our knowledge of this fauna4 ,at what horizon1 then1 does this steppe-fauna make its appearance8 ,at ,thiede ,dr4 ,nehring discovered in so-called lss three successive horizons1 each characterised by a special fauna4 ,the lowest of these faunas was decidedly arctic in type2 above that came a steppe-fauna1 which last was succeeded by a fauna comprising such forms as mammoth1 woolly rhinoceros1 ,bos1 ,cervus1 horse1 hyna1 and lion4 ,now1 if we compare this last fauna with the forms which have been obtained from true post-glacial deposits--those deposits1 namely1 which overlie the younger boulder-clays and flood-accumulations of the latest glacial epoch1 we find little in common4 ,the lion1 the mammoth1 and the rhinoceros are conspicuous by their absence from the post-glacial beds of ,europe4 ,in place of them we meet with a more or less arctic fauna1 and a high-alpine and arctic flora1 which as we all know eventually gave place to the flora and fauna with which ,neolithic man was contemporaneous4 ,as this is the case throughout north-western and central ,europe1 we seem justified in assigning the ,thiede beds to the ,pleistocene period1 and to that interglacial stage which preceded and gradually merged into the last glacial epoch4 ,that the steppe-fauna indicates relatively drier conditions of climate than obtained when perennial snow and ice covered wide areas of the low-ground goes without saying1 but ,i am unable to agree with those who maintain that it implies a dry-as-dust climate1 like that of some of the steppe-regions of our own day4 ,the remarkable commingling of arctic- and steppe-faunas discovered in the ,bhmer-,wald,,as by ,woldrich shows1 ,i think1 that the jerboas1 marmots1 and hamster-rats were not incapable of living in the same regions contemporaneously with lemmings1 arctic hares1 ,siberian social voles1 etc4 ,but when a cold epoch was passing away the steppe-forms probably gradually replaced their arctic congeners1 as these migrated northwards during the continuous amelioration of the climate4 ,,as ,woldrich3 ,sitzungsb4 d4 kais4 ,akad4 d4 ,w4 math4 nat4 ,cl41 #ahhj1 p4 #g2 #ahha1 p4 #agg2 #ahhc1 p4 #igh4 ,if the student of the ,pleistocene faunas has certain advantages in the fact that he has to deal with forms many of which are still living1 he labours at the same time under disadvantages which are unknown to his colleagues who are engaged in the study of the life of far older periods4 ,the ,pleistocene period was distinguished above all things by its great oscillations of climate--the successive changes being repeated and producing correlative migrations of floras and faunas4 ,we know that arctic and temperate faunas and floras flourished during interglacial times1 and a like succession of life-forms followed the final disappearance of glacial conditions4 ,a study of the organic remains met with in any particular deposit will not necessarily1 therefore1 enable us to assign these to their proper horizon4 ,the geographical position of the deposit1 and its relation to ,pleistocene accumulations elsewhere1 must clearly be taken into account4 ,already1 however1 much has been done in this direction1 and it is probable that ere long we shall be able to arrive at a fair knowledge of the various modifications which the ,pleistocene floras and faunas experienced during that protracted period of climatic changes of which ,i have been speaking4 ,we shall even possibly learn how often the arctic1 steppe-1 prairie-1 and forest-faunas1 as they have been defined by ,woldrich1 replaced each other4 ,even now some approximation to this better knowledge has been made4 ,dr4 ,pohlig1,,at for example1 has compared the remains of the ,pleistocene faunas obtained at many different places in ,europe1 and has presented us with a classification which1 although confessedly incomplete1 yet serves to show the direction in which we must look for further advances in this department of inquiry4 ,,at ,pohlig3 ,sitzungsb4 d4 niederrheinischen ,gesellschaft zu ,bonn1 #ahhd2 ,zeitschr4 d4 deutsch4 geolog4 ,ges41 #ahhg1 p4 #gih4 ,for a very full account of the diluvial ,european and northern ,asiatic mammalian faunas by ,woldrich1 see ,mm4 de l',acad4 des ,sciences de ,st4 ,ptersbourg1 viie sr41 t4 xxxv41 #ahhg4 ,during the last twenty years the evidence of interglacial conditions both in ,europe and ,america has so increased that geologists generally no longer doubt that the ,pleistocene period was characterised by great changes of climate4 ,the occurrence at many different localities on the ,continent of beds of lignite and freshwater alluvia1 containing remains of ,pleistocene mammalia1 intercalated between separate and distinct boulder-clays has left us no other alternative4 ,the interglacial beds of the ,alpine ,lands of central ,europe are paralleled by similar deposits in ,britain1 ,scandinavia1 ,germany1 and ,france4 ,but opinions differ as to the number of glacial and interglacial epochs--many holding that we have evidence of only two cold stages and one general interglacial stage4 ,this1 as ,i have said1 is the view entertained by most geologists who are at work on the glacial accumulations of ,scandinavia and north ,germany4 ,on the other hand1 ,dr4 ,penck and others1 from a study of drifts of the ,german ,alpine ,lands1 believe that they have met with evidence of three distinct epochs of glaciation1 and two epochs of interglacial conditions4 ,in ,france1 while some observers are of opinion that there have been only two epochs of general glaciation1 others1 as1 for example1 ,m4 ,tardy1 find what they consider to be evidence of several such epochs4 ,others again1 as ,m4 ,falsan1 do not believe in the existence of any interglacial stages1 although they readily admit that there were great advances and retreats of the ice during the ,glacial period4 ,m4 ,falsan1 in short1 believes in oscillations1 but is of opinion that these were not so extensive as others have maintained4 ,it is1 therefore1 simply a question of degree1 and whether we speak of oscillations or of epochs1 we must needs admit the fact that throughout all the glaciated tracts of ,europe1 fossiliferous deposits occur intercalated among glacial accumulations4 ,the successive advance and retreat of the ice1 therefore1 was not a local phenomenon1 but characterised all the glaciated areas4 ,and the evidence shows that the oscillations referred to were on a gigantic scale4 ,the relation borne to the glacial accumulations by the old river alluvia which contain relics of palolithic man early attracted attention4 ,from the fact that these alluvia in some places overlie glacial deposits1 the general opinion 7still held by some7 was that palolithic man must needs be of post-glacial age4 ,but since we have learned that all boulder-clay does not belong to one and the same geological horizon--that1 in short1 there have been at least two1 and probably more1 epochs of glaciation--it is obvious that the mere occurrence of glacial deposits underneath palolithic gravels does not prove these latter to be post-glacial4 ,all that we are entitled in such a case to say is simply that the implement-bearing beds are younger than the glacial accumulations upon which they rest4 ,their horizon must be determined by first ascertaining the relative position in the glacial series of the underlying deposits4 ,now1 it is a remarkable fact that the boulder-clays which underlie such old alluvia belong1 without exception1 to the earlier stages of the ,glacial period4 ,this has been proved again and again1 not only for this country but for ,europe generally4 ,i am sorry to reflect that some twenty years have now elapsed since ,i was led to suspect that the palolithic deposits were not of post-glacial but of glacial and interglacial age4 ,in #ahga-gb ,i published a series of papers in the ,geological ,magazine in which were set forth the views ,i had come to form upon this interesting question4 ,in these papers it was maintained that the alluvia and cave-deposits could not be of post-glacial age1 but must be assigned to pre-glacial and interglacial times1 and in chief measure to the latter4 ,evidence was led to show that the latest great development of glacier-ice in ,europe took place after the southern pachyderms and palolithic man had vacated ,england--that during this last stage of the ,glacial period man lived contemporaneously with a northern and alpine fauna in such regions as southern ,france--and lastly1 that palolithic man and the southern mammalia never revisited north-western ,europe after extreme glacial conditions had disappeared4 ,these conclusions were arrived at after a somewhat detailed examination of all the evidence then available--the remarkable distribution of the palolithic and ossiferous alluvia having1 as ,i have said1 particularly impressed me4 ,i coloured a map to show at once the areas covered by the glacial and fluvio-glacial deposits of the last glacial epoch1 and the regions in which the implement-bearing and ossiferous alluvia had been met with1 when it became apparent that the latter never occurred at the surface within the regions occupied by the former4 ,if ossiferous alluvia did here and there appear within the recently glaciated areas it was always either in caves1 or as infra- or interglacial deposits4 ,since the date of these researches our knowledge of the geographical distribution of ,pleistocene deposits has greatly increased1 and implements and other relics of palolithic man have been recorded from many new localities throughout ,europe4 ,but none of this fresh evidence contradicts the conclusions ,i had previously arrived at2 on the contrary1 it has greatly strengthened my general argument4 ,professor ,penck was1 ,i think1 the first on the ,continent to adopt the views referred to4 ,he was among the earliest to recognise the evidence of interglacial conditions in the drift-covered regions of northern ,germany1 and it was the reflections which those remarkable interglacial beds were so well calculated to suggest that led him into the same path as myself4 ,dr4 ,penck has published a map,,au showing the areas covered by the earlier and later glacial deposits in northern ,europe and the ,alpine ,lands1 and indicating at the same time the various localities where palolithic finds have occurred1 and in not a single case do any of the latter appear within the areas covered by the accumulations of the last glacial epoch4 ,,au ,archiv fr ,anthropologie1 ,bd4 xv4 ,heft #c1 #ahhd4 ,a glance at the papers which have been published in ,germany within the last few years will show how greatly students of the ,pleistocene ossiferous beds have been influenced by what is now known of the interglacial deposits and their organic remains4 ,professors ,rothpletz,,av and ,andre1,,aw ,dr4 ,pohlig,,ax and others1 do not now hesitate to correlate with those beds the old ossiferous and implement-bearing alluvia which lie altogether outside of glaciated regions4 ,,av ,rothpletz3 ,denkschrift d4 schweizer4 ,ges4 fr d4 gesammt4 ,nat41 ,bd4 xxviii4 #ahha4 ,,aw ,andre3 ,abhandl4 z4 geolog4 ,specialkarte v4 ,elsass-,lothringen1 ,bd4 iv4 ,heft #b1 #ahhd4 ,,ax ,pohlig3 op4 cit4 ,the relation of the ,pleistocene alluvia of ,france to the glacial deposits of that and other countries has been especially canvassed4 ,rothpletz1 in the paper ,i have cited1 includes these alluvia amongst the interglacial deposits1 and in the present year 7#ahhi7 we have an interesting essay on the same subject by the accomplished secretary of the ,anthropological and ,archological ,congress which met recently in ,paris4 ,m4 ,boule,,ay correlates the palolithic cave- and river-deposits of ,france with those of other countries1 and shows that they must be of interglacial age4 ,his classification1 ,i am gratified to find1 does not materially differ from that given by myself a number of years ago4 ,he is satisfied that in ,france there is evidence of three glacial epochs and two well-marked interglacial horizons4 ,the oldest of the palolithic stages of ,mortillet 7,chellenne7 culminated according to ,boule during the last interglacial epoch1 while the more recent palolithic stages 7,moustrienne1 ,solutrenne1 and ,magdalnienne7 coincided with the last great development of glacier-ice4 ,the ,palolithic age1 so far as ,europe is concerned1 came to a close during this last cold phase of the ,glacial period4 ,,ay ,boule3 ,revue d',anthropologie1 #ahhi1 t4 #a4 ,there are many other points relating to glacial geology which have of late years been canvassed by ,continental workers1 but these ,i cannot discuss here4 ,i have purposely indeed restricted my remarks to such parts of a wide subject as ,i thought might have interest for glacialists in this country1 some of whom may not have had their attention directed to the results which have recently been attained by their fellow-labourers in other lands4 ,had time permitted ,i should gladly have dwelt upon the noteworthy advances made by our ,american brethren in the same department of inquiry4 ,especially should ,i have wished to direct attention to the remarkable evidence adduced in favour of the periodicity of glacial action4 ,thus ,messrs4 ,chamberlin and ,salisbury1 after a general review of that evidence1 maintain that the ,ice ,age was interrupted by one chief interglacial epoch and also by three interglacial sub-epochs or episodes of deglaciation4 ,these authors discuss at some length the origin of the lss1 and come to the general conclusion that while deposits of this character may have been formed at different stages of the ,glacial period1 and under different conditions1 yet upon the whole they are best explained by aqueous action4 ,indeed a perusal of the recent geological literature of ,america shows a close accord between the theoretical opinions of many ,transatlantic and ,european geologists4 ,thus as years advance the picture of ,pleistocene times becomes more and more clearly developed4 ,the conditions under which our old palolithic predecessors lived--the climatic and geographical changes of which they were the witnesses--are gradually being revealed with a precision that only a few years ago might well have seemed impossible4 ,this of itself is extremely interesting1 but ,i feel sure that ,i speak the conviction of many workers in this field of labour when ,i say that the clearing up of the history of ,pleistocene times is not the only end which they have in view4 ,one can hardly doubt that when the conditions of that period and the causes which gave rise to these have been more fully and definitely ascertained we shall have advanced some way towards the better understanding of the climatic conditions of still earlier periods4 ,for it cannot be denied that our knowledge of ,palozoic1 ,mesozoic1 and even early ,cainozoic climates is unsatisfactory4 ,but we may look forward to the time when much of this uncertainty will disappear4 ,meteorologists are every day acquiring a clearer conception of the distribution of atmospheric pressure and temperature and the causes by which that distribution is determined1 and the day is approaching when we shall be better able than we are now to apply this extended meteorological knowledge to the explanation of the climates of former periods in the world's history4 ,one of the chief factors in the present distribution of atmospheric temperature and pressure is doubtless the relative position of the great land- and water-areas2 and if this be true of the present1 it must be true also of the past4 ,it would almost seem1 then1 as if all one had to do to ascertain the climatic conditions of any particular period1 was to prepare a map depicting with some approach to accuracy the former relative position of land and sea4 ,with such a map could our meteorologists infer what the climatic conditions must have been8 ,yes1 provided we could assure them that in other respects the physical conditions did not differ from the present4 ,now there is no period in the past history of our globe the geographical conditions of which are better known than the ,pleistocene4 ,and yet1 when we have indicated these upon a map1 we find that they do not give the results which we might have expected4 ,the climatic conditions which they seem to imply are not such as we know did actually obtain4 ,it is obvious1 therefore1 that some additional and perhaps exceptional factor was at work to produce the recognised results4 ,what was this disturbing element1 and have we any evidence of its interference with the operation of the normal agents of climatic change in earlier periods of the world's history8 ,we all know that various answers have been given to such questions4 ,whether amongst these the correct solution of the enigma is to be found1 time will show4 ,meanwhile1 as all hypothesis and theory must starve without facts to feed on1 it behoves us as working geologists to do our best to add to the supply4 ,the success with which other problems have been attacked by geologists forbids us to doubt that ere long we shall have done much to dispel some of the mystery which still envelopes the question of geological climates4 ,,ix4 ,the ,glacial ,period and the ,earth-,movement ,hypothesis4,,az ,,az ,this article contains the substance of two papers1 one read before the ,victoria ,institute1 in #ahib2 the other an address delivered to the ,geological ,society of ,edinburgh1 in #ahia4 ,perhaps no portion of the geological record has been more assiduously studied during the last quarter of a century than its closing chapters4 ,we are now in possession of manifold data concerning the interpretation of which there seems to be general agreement4 ,but while that is the case1 there remain1 nevertheless1 certain facts or groups of facts which are variously accounted for4 ,nor have all the phenomena of the ,pleistocene period received equal attention from those who have recently speculated and generalised on the subject of ,pleistocene climate and geography4 ,yet1 we may be sure1 geologists are not likely to arrive at any safe conclusions as to the conditions that obtained in ,pleistocene times1 unless the evidence be candidly considered in all its bearings4 ,no interpretation of that evidence which does not recognise every outstanding group of facts can be expected to endure4 ,it may be possible to frame a plausible theory to account for some particular conspicuous phenomena1 but should that theory leave unexplained a residuum of less conspicuous but nevertheless well-proved facts1 then1 however strongly it may be fortified1 it must assuredly fall4 ,as already remarked1 there are many phenomena in the interpretation of which geologists are generally agreed4 ,it is1 for example1 no longer disputed that in ,pleistocene times vast sheets of ice--continental mers de glace--covered broad areas in ,europe and ,north ,america1 and that extensive snow-fields and large local glaciers existed in many mountain-regions where snow-fields and glaciers are now unknown1 or only meagrely developed4 ,it is quite unnecessary1 however1 that ,i should give even the slightest sketch of the aspect presented by the glaciated tracts of our hemisphere at the climax of the ,ice ,age4 ,the geographical distribution and extent of the old snow-fields1 glaciers1 and ice-sheets is matter now of common knowledge4 ,it will be well1 however1 to understand clearly the nature of the conditions which obtained at the climax of glacial cold--at that stage1 namely1 when the ,alpine glaciers reached their greatest development1 and when so much of ,europe was cased in snow and ice4 ,this we shall best do by comparing the present with the past4 ,now in our day the limits of perennial snow are attained at heights that necessarily vary with the latitude4 ,this is shown as follows3-- ,region4 ,n4 ,lat4 ,height of ,snow-,line4 ,iceland1 #fe #c1jgj feet4 ,norway1 #fa #e1ahj-e1egj ,n4 ,urals1 #ei #cj' #d1gij ,alps1 #df #h1hhd or #i1jjj ,caucasus1 #dc #aj1fjj-aa1jjj ,apennines1 #db #cj' #i1ebj ,etna1 #cg #cj' #i1ecj ,sierra ,nevada1 #cg #aa1ahg ,thus in traversing ,europe from north to south the snow-line may be said to rise from #cjjj feet to #aa1jjj feet in round numbers4 ,it is possible from such data to draw across the map a series of isochional lines1 or lines of equal perennial snow1 and this has been done by my friend1 ,professor ,penck of ,vienna4,,ba ,it will be understood that each isochional line traverses those regions above which the line of nv is estimated to occur at the same height4 ,thus the isochional line of #ajjj metres 7#cbhj feet7 runs from the north of ,norway down to lat4 #fd on the west coast1 whence it must pass west to the south of ,iceland4 ,the line of #aejj metres 7#dibj ft47 is traced from the north end of the ,urals in a westerly direction4 ,it then follows the back-bone of the ,scandinavian peninsula1 passes over to ,scotland1 and thence strikes west along lat4 #ee4 ,for each of these lines good data are obtainable4 ,the line of #bjjj metres 7#fefj ft47 is1 however1 hypothetical4 ,it is estimated to extend from the ,ural ,mountains1 about the lat4 of #eg1 over the mountains of middle ,germany and above the north of ,france4 ,the line of #bejj metres 7#hbjj ft47 passes from the southern termination of the ,urals1 in lat4 #ea1 to the east ,carpathians1 thence along the north face of the ,alps1 thereafter south-west across the ,cevennes to the north-west end of the ,pyrenees2 and thence above the ,cantabrian and the ,portuguese ,highlands to the coast in lat4 #ci4 ,the line of #cjjj metres 7#ihdj ft47 is estimated to occur above the ,caspian ,sea1 near lat4 #dd1 and extends west through the north end of the ,caucasus to the ,balkans4 ,thence it is traced north-west to the ,alps1 south-west to the ,pyrenees1 which range it follows to the west1 and thereafter sweeps south above the coast at ,cadiz4 ,the line of #cejj metres 7#aa1dhj ft47 runs from the ,caucasus south-west across ,asia ,minor to the ,lebanon ,mountains2 thence it follows the direction of the ,mediterranean1 and traverses ,morocco above the north face of the ,atlas range4 ,finally the line of #djjj metres 7#ac1abj feet7 is estimated to trend in the same general direction as the last-mentioned line1 but1 of course1 further to the south4 ,although these isochional lines are to some extent conjectural1 yet the data upon which they are based are sufficiently numerous and well-known to prevent any great error1 and we may admit that the lines represent with tolerable accuracy the general position of the snow-line over our ,continent4 ,so greatly has our knowledge of the glaciation of ,europe increased during recent years1 that the height of the snow-line of the ,glacial period has been determined by ,,mm4 ,simony1 ,partsch1 ,penck1 and ,hfer4 ,their method is simple enough4 ,they first ascertain the lowest parts of a glaciated region from which independent glaciers have flowed4 ,this gives the maximum height of the old snow-line4 ,next they determine the lowest point reached by such glaciers4 ,it is obvious that the snow-line would occur higher up than that1 but at a lower level than the actual source of the glaciers2 and thus the minimum height of the former snow-line is approximately ascertained4 ,the lowest level from which independent glaciers formerly flowed1 and the terminal point reached by the highest-lying glaciers having been duly ascertained1 it is possible to determine with sufficient accuracy the mean height of the old snow-line4 ,the required data are best obtained1 as one might have expected1 in the ,pyrenees and amongst the mountains of middle and southern ,europe4 ,in those regions the snow-line would seem to have been some #cjjj feet or so lower than now4 ,from such data ,professor ,penck has constructed a map showing the isochional lines of the ,glacial period4 ,these lines are1 ,i need hardly say1 only approximations1 but they are sufficiently near the truth to bring out the contrast between the ,ice ,age and the present4 ,thus the isochional of #ajjj metres1 which at present lies above northern ,scandinavia1 was pushed south to the latitude of southern ,france and north ,italy2 while the isochional of #bjjj metres 7now overlying the extreme north of ,france and north ,germany7 passed in glacial times over the northern part of the ,mediterranean4,,bb ,,ba ,geographische ,wirkungen der ,eiszeit1 ,verhandl4 d4 vierten deutschen ,geographentages zu ,mnchen1 #ahhd4 ,,bb ,it is interesting to note that while in the ,tatra 7north ,carpathians7 the snow-line was depressed in glacial times to the extent of #bgjj feet only1 in the ,alps it descended some #djjj feet or more below its present level4 ,with the snow-line of that great chain at such an elevation it is obvious that only a few of the higher points of the ,apennines could rise into the region of nv4 ,this is the reason why moraines are met with in only the higher valleys of that range4 ,isochional lines are not isotherms4 ,their height and direction are determined not only by temperature1 but by the amount and distribution of the snow-fall4 ,nevertheless1 the position of the snow-line in ,europe during the ,ice ,age enables us to form a rough estimate of the temperature4 ,at present in middle ,europe the temperature falls #a ,f4 for every #cjj feet of ascent4 ,hence if we take the average depression of the snow-line in glacial times at #cjjj feet1 that would correspond approximately to a lowering of the temperature by #aj4;,,bc ,this may not appear to be much1 but1 as ,penck points out1 were the mean annual temperature to be lowered to that extent it would bring the climate of northern ,norway down to southern ,germany1 and the climate of ,sweden to ,austria and ,moravia1 while that of the ,alps would be met with over the basin of the ,mediterranean4 ,,bc ,professor ,brckner thinks the general lowering of temperature may not have exceeded #e-a_/b to #g ,f4 ,verhandlungen der #gc ,jahresversammlung der schweizerischen ,naturforschenden ,gesellschaft in ,davos1 #ahij4 ,let it be noted further that this lowering of the temperature--this displacement of climatic zones1 was experienced over the whole continent--extending on the one hand south into ,africa1 and on the other east into ,asia4 ,but while the conditions in northern and central ,europe were markedly glacial1 further south only more or less isolated snow-capped mountains and local glaciers appeared--such1 for example1 as those of the ,sierra ,nevada1 the ,apennines1 ,corsica1 the ,atlas1 the ,lebanon1 etc4 ,in connection with these facts we may note also that the ,azores were reached by floating ice2 and ,i need only refer in a word to the evidence of cold wet conditions as furnished by the plant and animal remains of the ,pleistocene tufas1 alluvia1 and peat of southern ,europe4 ,again in north ,africa and ,syria we find1 in desiccated regions1 widespread fluviatile accumulations1 which1 in the opinion of a number of competent observers1 are indicative of rainy conditions contemporaneous with the ,glacial period of ,europe4 ,when we compare the conditions of the ,ice ,age with those of the present we are struck with the fact that the former were only an exaggeration of the latter4 ,the development of glaciation was in strict accordance with existing conditions4 ,thus in ,pleistocene times ,north ,america was more extensively glaciated than northern ,europe1 just as to-day ,greenland shows more snow and ice than ,scandinavia4 ,no traces of glaciation have been observed as yet in northern ,asia or in northern ,alaska1 and to-day the only glaciers and ice-sheets that exist in northern regions are confined to the formerly glaciated areas4 ,again1 in ,pleistocene ,europe glacial phenomena were more strongly developed in the west than in the east4 ,large glaciers1 for example1 existed in central ,france1 and a considerable ice-flow poured into the basin of the ,douro4 ,but in the same latitudes of eastern ,europe we meet with few or no traces of ice-action4 ,again1 the ,vosges appear to have been more severely glaciated than the mountains of middle ,germany2 and so likewise the old glaciers of the western ,alps were on a much more extensive scale than those towards the east end of the chain4 ,similar contrasts may be noted at the present day4 ,thus we find glaciers in ,norway under lat4 #fj1 while in the ,ural ,mountains in the same latitude there is none4 ,the glaciers of the western ,alps1 again1 are larger than those in the eastern part of the chain4 ,the ,caucasus region1 it is true1 has considerable glaciers1 but then the mountains are higher4 ,now turn for a moment to ,north ,america4 ,the eastern area was covered by one immense ice-sheet1 while in the mountainous region of the west gigantic glaciers existed4 ,in our own day we see a similar contrast4 ,in the north-east lies ,greenland well-nigh drowned in ice1 while the north-west region on the other hand1 although considerably higher and occurring in the same latitude1 holds only local glaciers4 ,we may further note that at the present day very dry regions1 even when these are relatively lofty and in high latitudes1 such as the uplands of ,siberia1 contain no glaciers4 ,and the same was the case in the ,glacial period4 ,these facts are sufficient to show that the conditions of glacial times bore an intimate relation to those that now obtain4 ,could the requisite increase of precipitation and lowering of temperature take place1 we cannot doubt that ice-sheets and glaciers would reappear in precisely the same regions where they were formerly so extensively developed4 ,no change in the relative elevation of the land would be required--increased precipitation accompanied by a general lowering of the snow-line for #cjjj or #cejj feet would suffice to reintroduce the ,ice ,age4 ,from the foregoing considerations we may conclude3--7#a7 ,that the cold of the ,glacial period was a general phenomenon1 due to some widely-acting cause--a cause sufficient to influence contemporaneously the climate of ,europe and ,north ,america2 7#b7 that glaciation in our continent increased in intensity from east to west1 and from south to north2 7#c7 that where now we have the greatest rainfall1 in glacial times the greatest snow-fall took place1 and the snow tended most to accumulate2 7#d7 that in the extreme south of ,europe1 and in north ,africa and west ,asia1 increased rain precipitation accompanied lowering of temperature1 from which it may be inferred that precipitation in glacial times was greater generally than it is now4 ,having considered the climatic conditions that obtained at the climax of the ,glacial period1 ,i have next to recapitulate what is known as to the climatic changes of ,pleistocene times4 ,it is generally admitted that the glacial conditions of which ,i have been speaking were repeated twice1 some say three times1 during the ,pleistocene period2 while others maintain that even a larger number of glacial episodes may have occurred4 ,two glacial epochs1 at all events1 have been recognised generally both in ,europe and ,north ,america4 ,these were separated by an interglacial stage of more genial conditions1 the evidence for which is steadily increasing4 ,no one now calls in question the existence of interglacial deposits1 but1 as their occurrence is rather a stumbling-block in the way of certain recently resuscitated hypotheses1 some attempt has been made to minimise their importance--to explain them away1 in fact4 ,it has been suggested1 for example--7and the suggestion is by no means new7--that the deposits in question only show that there were local oscillations during the advance and retreat of the old ice-sheets and glaciers4 ,this1 however1 is not the view of those who have observed and described interglacial beds--who know the nature of the organic remains which they have yielded1 and the conditions under which the beds must have been accumulated4 ,i need not refer to the interglacial deposits of our own country further than to remark that they certainly cannot be explained away in that summary fashion4 ,the peat and freshwater beds that lie between the lower and upper tills in the neighbourhood of ,edinburgh1 for example1 are of themselves sufficient to prove a marked and decided change of climate4 ,no mere temporary retreat and re-advance of the ice-sheet will account for their occurrence4 ,the lower till is unquestionably the bottom-moraine of an ice-sheet which1 in that region1 flowed towards the east4 ,when the geographical position of the deposits in question is considered it becomes clear that an easterly flow of ice in ,mid-,lothian proves beyond gainsaying that during the accumulation of the lower till all ,scotland was drowned in ice4 ,but when water once more flowed over the land-surface--when a temperate flora1 composed of hazels and other plants1 again appeared1 it is obvious that the ice-sheet had already vanished from central ,scotland4 ,this is not the case of a mere temporary recession of the ice-front4 ,it is impossible to believe that a temperate or even cold-temperate flora could have flourished in central ,scotland at a period when thick glacier-ice mantled any portion of our ,lowlands4 ,again1 in the upper till we read the evidence of a recurrence of extreme glacial conditions--when central ,scotland was once more overwhelmed by confluent ice-streams coming from the ,highlands and the southern ,uplands4 ,similar evidence of recurrent glacial conditions1 ,i need hardly remind you1 has been detected in other parts of the country4 ,we are justified1 then1 in maintaining that our interglacial beds point to distinct oscillations of climate--oscillations which imply a long lapse of time4 ,continental observers are equally convinced that the interglacial epoch1 of which so many interesting relics have been preserved over a wide region1 was marked at its climax by a temperate climate and endured for a long period4 ,the interglacial beds of northern and central ,europe form everywhere marked horizons in the glacial series4 ,geologists sometimes forget that in every region where glacial accumulations are well developed1 good observers had recognised an upper and lower series of drift-deposits long before the idea of two separate glacial epochs had presented itself4 ,thus1 in north ,germany1 so clearly is the ,upper differentiated from the ,lower ,diluvium that the two series had been noted and mapped as separate accumulations for years before geologists had formulated the theory of successive ice-epochs4,,bd ,the division of the ,german ,diluvium into an upper and a lower series is as firmly established as any other well-marked division in historical geology4 ,the stratigraphical evidence has been much strengthened1 however1 by the discovery between upper and lower boulder-clays of true interglacial beds1 containing lignite1 peat1 diatomaceous earth1 and marine1 brackish1 and freshwater molluscs1 fish1 etc41 and now and again bones of ,pleistocene mammals4,,be ,a similar strongly-marked division characterises the glacial accumulations of ,sweden1 as has been clearly shown by ,de ,geer1,,bf who thinks that the older and younger epochs of glaciation were separated by a protracted period of interglacial conditions4 ,in short1 evidence of a break in the glacial succession has been traced at intervals across the whole width of the ,continent1 from the borders of the ,north ,sea to central ,russia4 ,m4 ,krischtafowitsch has recently detected in the neighbourhood of ,moscow,,bg certain fossiliferous interglacial beds1 the flora and fauna of which indicate a warmer and moister climate than the present4 ,the interglacial stage1 he says1 must have been of long duration1 and separated in ,russia as in western ,europe two distinct epochs of glaciation4 ,,bd ,wahnschaffe3 ,forschungen zur deutschen ,landes- und ,volkskunde von ,dr4 ,a4 ,kirchhoff1 ,bd4 vi41 ,heft #a4 ,,be ,for interglacial beds of north ,germany see ,helland3 ,zeitschr4 d4 deutsch4 geol4 ,ges41 xxxi41 #hgi2 ,penck3 ,ibid41 xxxi41 #aeg2 ,lnderkunde von ,europa 7,das deutsche ,reich71 #ahhg1 #eab2 ,dames3 ,samml4 gemeinverstndl4 wissensch4 ,vortrge1 von ,virchow u4 ,holtzendorff3 xx4 ,ser41 #dgi ,heft2 ,schrder3 ,jahrb4 d4 k4 geol4 ,landensanst4 f4 #ahhe1 p4 #bai4 ,for further references see ,wahnschaffe1 op4 cit4 ,i have not thought it worth while in this paper to refer to the interglacial deposits of our own islands4 ,a general account of them will be found in my ,great ,ice ,age1 and ,prehistoric ,europe4 ,the interglacial phenomena of the ,continent seem to be less known here than they ought to be4 ,,bf ,zeitschrift d4 deutsch4 geolog4 ,gesellschaft1 ,bd4 xxxvii1 p4 #aig4 ,,bg ,anzeichen einer interglaziren ,epoche in ,central-,russland1 ,moskau1 #ahia4 ,no mere temporary retreat and re-advance of the ice-front can account for these phenomena4 ,the occurrence of remains of the great pachyderms at ,rixdorf1 near ,berlin1 and the character of the flora met with in the interglacial beds of north ,germany and ,russia are incompatible with glacial conditions in the low-grounds of northern ,europe4 ,the interglacial beds1 described by ,dr4 ,c4 ,weber,,bh as occurring near ,grnenthal1 in ,holstein1 are among the more recent discoveries of this kind4 ,these deposits rest upon boulder-clay1 and are overlaid by another sheet of the same character1 and belong1 according to ,weber1 to that great interglacial period which preceded the last ice-sheet of northern ,europe4 ,the section shows #h feet of peat resting on freshwater clay1 #b feet thick1 which is underlaid by some #aj feet of coral sand1 with bryozoa4 ,the flora and fauna have a distinctly temperate facies4 ,it is no wonder1 then1 that ,continental geologists are generally inclined to admit that north ,germany and the contiguous countries have been invaded at least twice by the ice-sheets of two separate and distinct glacial epochs4 ,this is not all1 however4 ,while every observer acknowledges that the ,diluvium is properly divided into an upper and a lower series1 there are some geologists who have described the occurrence of three1 and even more boulder-clays--the one clearly differentiated from the other1 and traceable over wide areas4 ,is each of these to be considered the product of an independent ice-sheet1 or do they only indicate more or less extensive oscillations of the ice-front8 ,the boulder-clays are parted from each other by thick beds of sand and clay1 in some of which fossils have occasionally been detected4 ,it is quite possible that such stratified beds were deposited during a temporary retreat of the ice-front1 which when it re-advanced covered them up with its bottom-moraine4 ,on the other hand1 the phenomena are equally explicable on the assumption that each boulder-clay represents a separate epoch of glaciation4 ,until the stratified beds have yielded more abundant traces of the life of the period1 our judgment as to the conditions implied by them must be suspended4 ,it is worthy of note in this connection1 however1 that in ,north ,america the existence of one prolonged interglacial epoch has been well established1 while distinct evidence is forthcoming of what ,chamberlin discriminates as stages of deglaciation and re-advancing ice4,,bi ,,bh ,neues ,jahrbuch f4 ,mineralogie1 ,geologie1 u4 ,palontologie1 #ahia1 ,bd4 ii41 pp4 #fb1 #bbh2 #ahib1 ,bd4 i41 p4 #aad4 ,,bi ,sixth ,annual ,report1 ,u4 ,s4 ,geol4 ,survey1 #ahhd-e1 ,p4 #cae4 ,when we turn to the ,alpine ,lands1 we find that there also the occurrence of former interglacial conditions has been recognised4 ,the interglacial deposits1 as described by ,heer and others1 are well known4 ,these form as definite a geological horizon as the similar fossiliferous zone in the ,diluvium of northern ,germany4 ,the lignites1 as ,heer pointed out1 represent a long period of time1 and this is still further illustrated by the fact that considerable fluviatile erosion supervened between the close of the first and the advent of the later glacial epoch4 ,no mere temporary retreat and re-advance of the ice will account for the phenomena4 ,let us for a moment consider the conditions under which the accumulations in question were laid down4 ,the glacial deposits underlying the lignite beds contain1 amongst other erratics1 boulders which have come from the upper valley of the ,rhine4 ,this means1 of course1 that the ancient glacier of the ,rhine succeeded in reaching the ,lake of ,zurich2 and it is well known that it extended at the same time to ,lake ,constance4 ,that glacier1 therefore exceeded sixty miles in length4 ,one cannot doubt that the climatic conditions implied by this great extension were excessive1 and quite incompatible with the appearance in the low-grounds of ,switzerland of such a flora as that of the lignites4 ,the organic remains of the lignite beds indicate a climate certainly not less temperate than that which at present characterises the district round the ,lake of ,zurich4 ,we may safely infer1 therefore1 that during interglacial times the glaciers of the ,alps were not more extensively developed than at present4 ,again1 as the lignites are overlaid by glacial deposits1 it is obvious that the ,rhine glacier once more reached ,lake ,zurich--in other words1 there was a return of the excessive climate that induced the first great advance of that and other ,swiss glaciers4 ,that these advances were really due to extreme climatic conditions is shown by the fact that it was only under such conditions that the ,scandinavian flora could have invaded the low-grounds of ,europe1 and entered ,switzerland4 ,it is impossible1 therefore1 that the interglacial flora could have flourished in ,switzerland while the immigration of these northern plants was taking place4 ,lignites of the same age as those of ,drnten and ,utznach occur in many places both on the north and south sides of the ,alpine chain4 ,at ,imberg1 near ,sonthofen1 in ,bavaria1 for example1 they are described by ,penck,,bj as being underlaid and overlaid by thick glacial accumulations4 ,the deposits in question form a terrace along the flanks of the hills1 at a height of #gjj feet above the ,iller4 ,the flora of the lignite has not yet been fully studied1 but it is composed chiefly of conifers1 which must have grown near where their remains now occur--that is at #cjjj feet1 or thereabout1 above the sea4 ,it is incredible that coniferous forests could have flourished at that elevation during a glacial epoch4 ,a lowering of the mean annual temperature by #c ,c4 only would render the growth of trees at that height almost impossible1 and certainly would be insufficient to cause the glaciers of ,algau to descend to the foot of the mountains1 as we know they did--a distance of at least twenty-four miles4 ,the ,imberg lignites1 therefore1 are evidence of a climate not less temperate than the present4 ,more than this1 there is clear proof that the interglacial stage was long continued1 for during that epoch the ,iller had time to effect very considerable erosion4 ,the succession of changes shown by the sections near ,sonthofen are as follows4 #a4 ,the ,iller ,valley is filled with glacier-ice which flows out upon the low-grounds at the base of the ,alps4 #b4 ,the glacier retreats1 and great sheets of shingle and gravel are spread over the valley4 #c4 ,coniferous forests now grow over the surface of the gravels2 and as the lignite formed of their remains attains a thickness of ten feet in all1 it obviously points to the lapse of some considerable time4 #d4 ,eventually the forests decay1 and their dbris is buried under new accumulations of shingle and gravel4 #e4 ,the ,iller cuts its way down through all the deposits to depths of #fhj to #gbj feet4 #f4 ,a glacier again descends and fills the valley1 but does not flow so far as that of the earlier glacial stage4 ,,bj ,die ,vergletscherung der deutschen ,alpen1 #ahhb1 p4 #bef4 ,in this section1 as in those at ,drnten and ,utznach1 we have conclusive evidence of two glacial epochs1 sharply marked off the one from the other4 ,nor does that evidence stand alone1 for at various points between ,lake ,geneva and the lower valley of the ,inn similar interglacial deposits occur4 ,sometimes these appear at the foot of the mountains1 as at ,mrschweil on ,lake ,constance2 sometimes just within the mountain area1 as at ,imberg2 sometimes far in the heart of the ,alpine ,lands1 as at ,innsbruck4 ,professor ,penck has further shown1 and his observations have been confirmed by ,brckner1 ,blaas1 and ,bhm1 that massive sheets of fluviatile gravel are frequently met with throughout the valleys of the ,alps1 occupying interglacial positions4 ,these gravels are exactly comparable to the interglacial gravels of the ,sonthofen sections4 ,and it has been demonstrated that they occur on two horizons1 separated the one from the other by characteristic ground-moraine1 or boulder-clay4 ,the lower gravels rest on ground-moraine1 and the upper gravels are overlaid by sheets of the same kind of glacial detritus4 ,in short1 three separate and distinct ground-moraines are recognised4 ,the gravels1 one cannot doubt1 are simply the torrential and fluviatile deposits laid down before advancing and retreating glaciers2 and it is especially to be noted that each sheet of gravel1 after its accumulation1 was much denuded and cut through by river-action4 ,in a word1 as ,penck and others have shown1 the valleys of ,upper ,bavaria have been occupied by glaciers at three successive epochs--each separated from the other by a period during which much river-gravel was deposited and great erosion of the valley-bottoms was effected4 ,on the ,italian side of the ,alps1 similar evidence of climatic changes is forthcoming4 ,the lignites and lacustrine strata of ,val ,gandino1 and of ,val ,borlezza1 as ,i have elsewhere shown1,,bk are clearly of interglacial age4 ,from these deposits many organic remains have been obtained--amongst the animals being ,rhinoceros hemitoechus and ,r4 leptorhinus4 ,according to ,sordelli1 the plants indicate a climate as genial as that of the plains of ,lombardy and ,venetia1 and warmer therefore than that of the upland valleys in which the interglacial beds occur4 ,professor ,penck informs me that some time ago he detected evidence in the district of ,lake ,garda of three successive glacial epochs--the evidence being of the same character as that recognised in the valleys of the ,bavarian ,alps4 ,,bk ,prehistoric ,europe1 p4 #cjc4 ,in the glaciated districts of ,france similar phenomena are met with4 ,thus in ,cantal1 according to ,m4 ,rames1,,bl the glacial deposits belong to two separate epochs4 ,the older morainic accumulations are scattered over the surface of the plateau of ,archan schistose rocks1 and extend up the slopes of the great volcanic cone of that region to heights of #bcjj to #ccjj feet4 ,one of the features of these accumulations are the innumerable gigantic erratics1 known to the country folk as cimetire des enrags4 ,sheets of fluvio-glacial gravel are also associated with the moraines1 and it is worthy of note that both have the aspect of considerable age--they have evidently been subjected to much denudation4 ,in the valleys of the same region occurs a younger series of glacial deposits1 consisting of conspicuous lateral and terminal moraines1 which1 unlike the older accumulations1 have a very fresh and well-preserved appearance4 ,with them1 as with the older moraines1 fluvio-glacial gravels are associated4 ,m4 ,rames shows that the interval that supervened between the formation of the two series of glacial deposits must have been prolonged1 for the valleys during that interval were in some places eroded to a depth of #ijj feet4 ,not only was the volcanic massif deeply incised1 but even the old plateau of crystalline rocks on which the volcanic cone reposes suffered extensive denudation in interglacial times4 ,m4 ,rames further recognises that the second glacial epoch was marked by two advances of the valley-glaciers1 separated by a marked episode of fusion1 the evidence for which is conspicuous in the valley of the ,cre4 ,,bl ,bull4 ,soc4 ,gol4 de ,france1 #ahhd4 ,the glacial and interglacial phenomena of ,auvergne are quite analogous to those of ,cantal4 ,dr4 ,julien has described the morainic accumulations of a large glacier that flowed from ,mont ,dore4 ,after that glacier had retreated a prolonged period of erosion followed1 when the morainic deposits were deeply trenched1 and the underlying rocks cut into4 ,in the valleys and hollows thus excavated freshwater beds occur1 containing the relics of an abundant flora1 together with the remains of elephant 7,e4 meridionalis71 rhinoceros 7,r4 leptorhinus71 hippopotamus1 horse1 cave-bear1 hyna1 etc4--a fauna comparable to that of the ,italian interglacial deposits4 ,after the deposition of the freshwater beds1 glaciers again descended the ,auvergne valleys and covered the beds in question with their moraines4,,bm ,,bm ,des ,phnomnes glaciaires dans le ,plateau central de ,france1 etc4 ,according to the researches of ,martins1 ,collomb1 ,garrigou1 ,piette1 and ,penck1 there is clear evidence in the ,pyrenees of two periods of glaciation1 separated by an interval of much erosion and valley-excavation4 ,penck1 indeed1 has shown that the valleys of the ,pyrenees have been occupied at three successive epochs by glaciers--each epoch being represented by its series of moraines and by terraces of fluvio-glacial detritus1 which occur at successively lower levels4 ,i have referred in some detail to these discoveries of interglacial phenomena because they so strongly corroborate the conclusions arrived at a number of years ago by glacialists in our own country4 ,many additional examples might be cited from other parts of ,europe1 but those already given may serve to show that at least one epoch of interglacial conditions supervened during the ,pleistocene period4 ,before leaving this part of my subject1 however1 ,i may point out the significant circumstance that long before much was known of glaciation1 and certainly before the periodicity of ice-epochs had been recognised1 ,collomb had detected in the ,vosges conspicuous evidence of two successive glaciations4,,bn ,,bn ,preuves de l'existence d'anciens glaciers dans les valles des ,vosges1 #ahdg1 p4 #ada4 ,having shown that alike in the regions formerly occupied by the great northern ice-sheet1 and in the ,alpine ,lands of central and southern ,europe1 alternations of cold and genial conditions characterised the so-called ,glacial period1 we may now glance at the evidence supplied by those ,pleistocene deposits that lie outside of the glaciated areas4 ,of these we have a typical example in the river-accumulations of the ,rhine ,valley between ,ble and ,bingen4 ,here and there these deposits have yielded remains of extinct and no longer indigenous mammals and relics of ,palolithic man--one of the most interesting deposits from which mammalian remains have been obtained being the ,sands of ,mosbach1 between ,wiesbaden and ,mayence4 ,the fauna in question is characteristically ,pleistocene1 nor can it be doubted that the ,mosbach ,sands belong to the same geological horizon as the similar fluviatile deposits of the ,seine1 the ,thames1 and other river-valleys in western ,europe4 ,dr4 ,kinkelin has shown1,,bo and with him ,dr4 ,schumacher agrees1,,bp that the ,mosbach deposits are of interglacial age2 while ,dr4 ,pohlig has no hesitation in assigning them to the same horizon4,,bq ,it is true there are no glacial accumulations in the region where they occur1 but they rest upon a series of unfossiliferous gravels which are recognised as the equivalents of the fluvio-glacial and glacial deposits of the ,vosges1 the ,black ,forest1 the ,alps1 etc4 ,these gravels are traced at intervals up to considerable heights above the ,rhine1 and contain numerous erratics1 some of which are several feet in diameter1 while a large proportion are not at all water-worn1 but roughly and sharply angular4 ,the blocks have unquestionably been transported by river-ice1 and imply therefore cold climatic conditions4 ,the overlying ,mosbach ,sands have yielded not only ,elephas antiquus and ,hippopotamus major1 but the reindeer1 the mammoth1 and the marmot--two strongly contrasted faunas1 betokening climatic changes similar to those that marked the accumulation of the river-deposits of the ,thames1 the ,seine1 etc4 ,of younger date than the ,mosbach ,sands is another series of unfossiliferous gravels1 which1 like the older series1 are charged with ice-floated erratics4 ,the beds at ,mosbach are thus shown to be of interglacial age3 they occupy the same geological horizon as the interglacial beds of ,switzerland and other glaciated tracts in central and northern ,europe4 ,,bo ,kinkelin3 ,bericht ber die ,senckenberg4 naturf4 ,ges4 in ,frankfurt a4 ,m41 #ahhi4 ,,bp ,schumacher3 ,mittheilungen d4 ,commission fr d4 geolog4 ,landes-,untersuch4 v4 ,elsass-,lothringen1 ,bd4 ii41 #ahij1 p4 #ahd4 ,,bq ,zeitschr4 d4 deutsch4 geolog4 ,ges41 #ahhg1 p4 #hjf4 ,to this position must likewise be assigned the ,pleistocene river-alluvia of other districts4 ,there is no other horizon1 indeed1 on which these can be placed4 ,that they are not of post-glacial age is shown by the fact that in many places the angular gravels and flood-loams of the ,glacial period overlie them4 ,and that they cannot all belong to pre-glacial times is proved by the frequent occurrence underneath them of glacial or fluvio-glacial accumulations4 ,it is quite possible1 of course1 that here and there in the valleys of western and southern ,europe some of the ,pleistocene alluvia may be of pre-glacial age4 ,but in the main these alluvia must be regarded as the equivalents of the glacial and interglacial deposits of northern and ,alpine districts4 ,this will appear a reasonable conclusion when we bear in mind that long before the ,pliocene period came to a close the climate of ,europe had begun to deteriorate4 ,in ,england1 as we know1 glacial conditions supervened almost at the advent of the ,pleistocene period4 ,and the same was the case in the ,alpine ,lands of the south4 ,again1 in the glaciated areas of north and south alike1 the closing stage of the ,pleistocene was characterised by cold climatic conditions4 ,and thus in those regions the glacial and interglacial epochs were co-extensive with that period4 ,it follows1 therefore1 that the ,pleistocene deposits of extra-glacial areas must be the equivalents of the glacial and interglacial accumulations elsewhere4 ,if we refused to admit this we should be puzzled indeed to tell what the rivers of western and southern ,europe were doing throughout the long-continued ,glacial period4 ,there is no escape from the conclusion that the ,pleistocene river-alluvia and cave-accumulations must be assigned to the same general horizon as the glacial and interglacial deposits4 ,this is now admitted by ,continental palontologists who find in the character of ,pleistocene organic remains abundant proof that the old river-alluvia and cave-accumulations were laid down under changing climatic conditions4 ,did neither glacial nor interglacial deposits exist1 the relics of the ,pleistocene flora and fauna met with in extra-glacial regions would yet lead us to the conclusion that after the close of the ,pliocene period1 extremely cold and very genial climates alternated up to the dawn of the present4 ,thus during one stage of the ,pleistocene clement winters and cool summers permitted the wide diffusion and intimate association of plants which have now a very different range4 ,temperate and southern species like the ash1 the poplar1 the sycamore1 the fig-tree1 the judas-tree1 etc41 overspread all the low-grounds of ,france as far north at least as ,paris4 ,it was under such conditions that the elephants1 rhinoceroses1 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 further north still1 and from the borders of ,asia to the western ocean4 ,despite the presence of numerous fierce carnivora--lions1 hynas1 tigers1 and others--,europe at that time1 with its shady forests1 its laurel-margined streams1 its broad and deep-flowing rivers--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 ,but during another stage of the ,pleistocene period1 the climate of our continent presented the strongest contrast to those genial conditions4 ,at that time 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 inhabitated the low-lying maritime districts of ,corsica and ,sardinia4 ,the land and freshwater molluscs of many ,pleistocene deposits tell a similar tale3 high alpine1 boreal1 and hyperborean forms are characteristic of those deposits in central ,europe2 even in the southern regions of our continent the shells testify to a former colder and wetter climate4 ,it was during the climax of these conditions that the caves of ,aquitaine were occupied by those artistic men who appear to have delighted in carving and engraving4,,br ,such1 in brief1 is the testimony of the ,pleistocene flora and fauna of extra-glacial regions4 ,it is from the deposits in these regions1 therefore1 that we derive our fullest knowledge of the life of the period4 ,but a comparison of their organic remains with those that occur in the glacial and interglacial deposits of alpine and northern lands shows us that the ,pleistocene accumulations of glacial and extra-glacial countries are contemporaneous--for there is not a single life-form obtained from interglacial beds which does not also occur in the deposits of extra-glacial regions4 ,the converse is not true--nor is that to be wondered at1 for interglacial deposits have only been sparingly preserved4 ,in regions liable to glaciation such superficial accumulations must frequently have been ploughed up and incorporated with ground-moraine4 ,it was only in the extra-glacial tracts that alluvia of interglacial age were at all likely to be preserved in any abundance4 ,to appreciate fully the climatic conditions of the ,pleistocene period1 therefore1 it is necessary to combine the evidence derived from the glaciated areas with that obtained from the lands that lay beyond the reach of the ice-plough4 ,the one is the complement of the other1 and this being so1 it is obvious that any attempted explanation of the origin of the ,glacial period which does not fully realise the importance of the interglacial phase of that period cannot be accepted4 ,,br ,prehistoric ,europe1 p4 #fg4 ,but if the climatic changes of ,pleistocene times are the most important phenomena which the geologist who essays to trace the history of that period is called upon to consider1 he cannot ignore the evidence of contemporaneous geographical mutations4 ,these are so generally admitted1 however1 that it is only necessary here to state the well-known fact that everywhere throughout the maritime tracts of the glaciated lands of ,europe and ,north ,america frequent changes in the relative level of land and sea took place during ,pleistocene and post-glacial times4 ,i must now very briefly review the evidence bearing on the climatic conditions of post-glacial times4 ,and first1 let it be noted that the closing stage of the ,pleistocene period was one of cold conditions1 accompanied in north-western ,europe by partial depression of the land below its present level4 ,this is shown by the late-glacial marine deposits of central ,scotland and the coast-lands of ,scandinavia4 ,the historical records of the succeeding post-glacial period are furnished chiefly by raised beaches1 river- and lake-alluvia1 calcareous tufas1 and peat-bogs4 ,an examination of these has shown that the climate1 at first cold1 gradually became less ungenial1 so that the ,arctic-alpine flora and northern fauna were eventually supplanted in our latitude by those temperate forms which1 as a group1 still occupy this region4 ,the amelioration of the climate was accompanied by striking geographical changes1 the ,british ,islands becoming united with themselves and the opposite coasts of the continent4 ,the genial character of the climate at this time is shown by the great development of forests1 the remains of which occur under our oldest peat-bogs4 ,not only did trees then grow at greater altitudes in these regions than is at present the case1 but forests ranged much further north1 and flourished in lands where they cannot now exist4 ,in ,orkney and ,shetland1 in the far north of ,norway1 and even in the ,fare ,islands and in ,iceland relics of this old forest-epoch are met with4 ,in connection with these facts reference may be made to the evidence obtained from certain raised beaches on both sides of the ,n4 ,atlantic1 and from recent dredgings in the intervening sea4 ,the occurrence of isolated colonies of southern molluscs in our northern seas1 and the appearance in raised beaches of many forms which are now confined to the waters of more southern latitudes1 seem to show that in early post-glacial times the seas of these northern latitudes were warmer than now4 ,and it is quite certain that the southern forms referred to are not the relics of any pre-glacial or interglacial immigration4 ,they could only have entered our northern seas after the close of the ,glacial period1 and their evidence taken in connection with that furnished by the buried trees of our peat-bogs1 leads to the conclusion that a genial climate supervened after the cold of the last glacial epoch and of earliest post-glacial times had passed away4 ,to this genial stage succeeded an epoch of cold humid conditions1 accompanied by geographical changes which resulted in the insulation of ,britain and ,ireland--the sea encroaching to some extent on what are now our maritime regions4 ,the climate was less favourable to the growth of forests1 which began to decay and to become buried under widespread accumulations of growing peat4 ,at this time glaciers reappeared in the glens of the ,scottish ,highlands1 and here and there descended to the sea4 ,the evidence for these is quite conspicuous1 for the moraines are found resting on the surface of post-glacial beaches4 ,thus my friend ,mr4 ,l4 ,hinxman1 of the ,geological ,survey1 tells us that at the foot of ,glen ,thraill well-formed moraines are seen in section reposing on beach-deposits at the distance of about three-quarters of a mile above the head of ,loch ,torridon4,,bs ,the evidence of this recrudescence of glacial conditions in post-glacial times is not confined to ,scotland4 ,i believe it will yet be recognised in many other mountain-regions2 but already ,prof4 ,penck has detected it in the valleys of the ,pyrenees4,,bt ,dr4 ,kerner von ,marilaun has also described similar phenomena in the higher valleys of ,tyrol1 while ,professor ,brckner has obtained like evidence in the ,salzach region4,,bu ,,bs ,for ,scottish post-glacial glaciers see ,j4 ,geikie3 ,scottish ,naturalist1 ,jan41 #ahhj2 ,prehistoric ,europe1 pp4 #chf1djg2 ,penck3 ,deutsche geographische ,bltter1 ,bd4 vi41 p4 #cbc2 ,verhand4 d4 ,ges4 f4 ,erdkunde1 ,berlin1 #ahhd1 ,heft #a2 ,hinxman3 ,trans4 ,edin4 ,geol4 ,soc41 vol4 vi41 p4 #bdi4 ,,bt ,die ,eiszeit in den ,pyrenen3 ,mitth4 d4 ,vereins4 f4 ,erdkunde1 ,leipzig1 #ahhc4 ,,bu ,kerner3 ,mitth4 k4 k4 geograph4 ,ges4 ,wien1 #ahij1 p4 #cjg2 ,sitzungsb4 d4 kais4 ,akad4 d4 ,wissensch4 in ,wien1 ,bd4 c41 ,abth4 i41 #ahia2 ,brckner3 ,x4 ,jahresbericht d4 geograph4 ,ges4 v4 ,bern1 #ahia4 ,i have elsewhere traced the history of the succeeding stages of the post-glacial period1 and brought forward evidence of similar but less strongly-marked climatic changes having followed upon those just referred to1 and my conclusions1 ,i may add1 have been supported by the independent researches of ,professor ,blytt in ,norway4 ,but these later changes need not be considered here1 and ,i shall leave them out of account in the discussion that follows4 ,it is sufficient for my present purpose to confine attention to the well-proved conclusion that in early post-glacial times genial climatic conditions obtained1 and that these were followed by cold and humid conditions1 during the prevalence of which considerable local glaciers reappeared in certain mountain-valleys4,,bv ,,bv ,for a full statement of the evidence see ,prehistoric ,europe1 chaps4 xvi41 xvii4 ,we speak of ,pleistocene or ,glacial and of ,post-glacial periods as if the one were more or less sharply marked off from the other4 ,of course1 that is not the case1 and in point of fact it would be for many reasons preferable to include them under some general term4 ,taken together they form one tolerably well-defined cycle of time1 characterised above all by its remarkable climatic changes--by alternations of cold and genial conditions1 which were most strongly contrasted in the earlier stages of the period4 ,it is further worthy of note that various oscillations of the sea-level appear to have taken place again and again both in the earlier and later stages of the cycle4 ,we may now proceed to inquire whether the phenomena we have been considering can be accounted for by movements of the earth's crust--a view which has recently received considerable support1 more especially in ,america4 ,i need hardly say that the view in question is no novelty4 ,many years ago1 while our knowledge of the ,pleistocene phenomena was somewhat rudimentary1 it was usual to infer that glaciation had been induced by elevation of the land4 ,this did not seem an unreasonable conclusion1 for above our heads1 at a less or greater elevation1 according to latitude1 an ,arctic climate prevails4 ,one could not doubt1 therefore1 that if a land-surface were only sufficiently uplifted it would reach the snow-line1 and become more or less extensively glaciated4 ,but with the increase of our knowledge of ,pleistocene and post-glacial conditions1 such a ready interpretation failed to satisfy1 although not a few geologists have continued to defend the earth-movement hypothesis1 as accounting fairly well for the phenomena of the ,glacial period4 ,by these staunch believers in the adequacy of that view1 it has been pointed out that elevation might not only lift lands into the region of eternal snow1 but1 by converting large areas of the sea-bed into land1 would greatly modify the direction of ocean-currents1 and thus influence the climate4 ,what might not be expected to happen were the ,gulf ,stream to be excluded from northern regions8 ,what would be the fate of the temperate latitudes of ,north ,america and ,europe were that genial ocean-river to be deflected into the ,pacific across a submerged ,isthmus of ,panama8 ,the possibility of such changes having supervened in ,pleistocene times has often been present to my mind1 but ,i long ago came to the conclusion that they could not account for the facts4 ,moreover1 ,i have never been able to meet with any evidence in favour of the postulated earth-movements4 ,having carefully studied all that has been advanced of late years in support of the hypothesis in question ,i find myself more than ever constrained to oppose it1 not only because it is grounded on no basis of fact1 but because it altogether fails to explain the conditions that obtained in ,pleistocene and post-glacial times4 ,there are various forms in which the hypothesis has appeared1 and these ,i shall now consider seriatim1 and with such brevity as may be4 ,it has been maintained1 for example1 that at the advent of the ,glacial period vast areas of northern and north-western ,europe1 together with enormous regions in the corresponding latitudes of ,north ,america1 stood several thousand feet higher than at present4 ,but when we ask what evidence can be adduced to prove this we get no satisfactory reply4 ,we are simply informed that a glacial climate must have resulted from great elevation1 and that the latter1 therefore1 must have taken place at the beginning of the ,glacial period4 ,some writers1 however1 have ventured to give reasons for their faith4 ,thus ,mr4 ,w4 ,upham1 pointing to the evidence of the fiords of ,north ,america1 and to the fact that drowned river-valleys have been traced outwards across the #ajj-;fathoms line of the marginal plateau to depths of over #cejj feet1 maintains that the whole continent north of the ,gulf of ,mexico stood at the commencement of the ,glacial period some #cjjj feet at least higher than now4 ,of course he cites the fiords of ,europe as evidence of a similar great upheaval for the northern and north-western regions of our ,continent4 ,mr4 ,upham even favours the notion that during glacial times a land-connection probably existed between ,north ,america and ,europe1 by way of the ,british ,islands1 ,iceland1 and ,greenland4 ,when this uplifting attained its maximum1 and brought on the ,glacial period1 he says1 ,north ,america and north-western ,europe stood #bejj to #cjjj feet above their present height4,,bw ,,bw ,american ,geologist1 vi41 p4 #cbg4 ,that fiords are simply submerged land-valleys has long been recognised3 that they have been formed mainly by the action of running water--just in the same way as the mountain-valleys of ,norway and ,scotland--has been the belief for many years of most students of physical geology4 ,but it is hard to understand why they should have been cited by ,mr4 ,upham in support of his contention1 seeing that their evidence seems to militate strongly against the very hypothesis he strives to maintain4 ,no one acquainted with the physical features and geological structure of ,scotland and ,norway can doubt that the valleys which terminate in fiords are of great geological antiquity4 ,their excavation by fluviatile action certainly dates back to a period long anterior to the advent of the ,ice ,age4 ,and a like tale is told by the fiords and drowned valley-troughs of ,north ,america1 which cannot be referred to so recent a period as post-,tertiary times4 ,those who are convinced that our continental areas have persisted throughout long ons of geological time1 and that rivers frequently have survived great geological revolutions--cutting their way across mountain-elevations as fast as these were uplifted--will readily believe that some of the submarine river-troughs of ,north ,america1 such as that of the ,hudson1 may belong even to ,secondary times4,,bx ,it would be hard to say at what particular date the excavation of the ,scottish ,highland valleys commenced--but it was probably during the later part of the ,palozoic era4 ,the process has doubtless been retarded and accelerated frequently enough1 during successive movements of depression and elevation1 but it was practically completed before the beginning of ,pleistocene times1 and that is all that we may trouble about here4 ,precisely the same conclusion holds good for ,norway3 and such being the case it is obvious that the question of the origin and age of the fiords has no bearing on the problem of the glacial climate and its cause4 ,in point of fact the evidence1 as already remarked1 tells against the earth-movement hypothesis1 for it shows us that1 during a period when ,europe and ,north ,america stood several thousand feet higher1 and extended much further seawards1 rivers1 and not glaciers1 were the occupants of our mountain-valleys4 ,it was not until all those valleys had come to assume much the appearance they now present that general glaciation supervened4 ,,bx ,professor ,dana inclines to date the erosion of the ,hudson trough so far back as the ,jura-,trias period4--,american ,journ4 ,science1 xl41 p4 #dce4 ,we are not without direct evidence1 however1 as to the geographical conditions that obtained in the ages that immediately preceded the ,pleistocene period4 ,the distribution of the ,pliocene marine beds of ,britain entitles us to assume that at the time of their accumulation our lands did not extend quite so far to the south and east as now4 ,the absence of similar deposits from the coast-lands of ,north ,america is supposed to support the view of great continental elevation in pre-glacial times4 ,all it seems to prove1 however1 is that in ,pliocene times the ,north ,american continent was not less extensive than it is at present4 ,it is even quite possible that in glacial times pre-existing ,pliocene beds may have been ploughed out by the ice1 just as seems to have been the case in the north-east of ,scotland4 ,but without going so far back as ,pliocene times1 we meet with evidence almost everywhere throughout the maritime regions of the glaciated areas of ,europe and ,north ,america1 to show that immediately before those tracts became swathed in ice the geographical conditions were much the same as at present4 ,the shelly boulder-clays in various parts of our islands1 and the similar occurrence of marine and brackish-water shells in and underneath the ,diluvium of north ,germany1 etc41 prove clearly enough that just before the coming-on of glacial conditions neither ,britain nor the present maritime lands of the ,continent were far removed from the sea4 ,it is true that the buried river-channels of ,scotland indicate a pre-glacial elevation of some #bjj or #cjj feet above the existing sea-level1 but it is quite certain that the ,minch1 ,st4 ,george's ,channel1 the ,irish ,sea1 the ,north ,sea1 and the ,baltic were all in existence at the commencement of the ,glacial period4 ,and we are led to similar conclusions with regard to the geographical conditions of ,north ,america at that time1 from the occurrence of marine shells in the boulder-clays of ,canada and ,new ,england4 ,we note indeed that there is abundant evidence of land-submergence during glacial times4 ,indeed1 we may say that the ,pleistocene marine deposits of northern latitudes are almost invariably indicative of colder conditions than now obtain4 ,if it be true that cold climatic conditions were contemporaneous in our latitude with submergence1 it is equally true that an extensive land-surface in north-west ,europe has1 sometimes at least1 co-existed with markedly genial conditions4 ,in ,tertiary times1 for example1 as the ,oligocene deposits of ,scotland1 the ,fare ,islands1 ,iceland1 and ,greenland testify1 a land-connection existed between ,europe and the ,north ,american continent4 ,again1 it has been shown that during the interglacial phase of the ,pleistocene period ,britain was continental1 and enjoyed at the time a peculiarly genial climate4 ,and somewhat similar geographical and climatic conditions again supervened in post-glacial times4 ,in other words1 when the land was more elevated and extensive than now1 it enjoyed a warmer climate4 ,nor can we escape the conclusion that the excavation of the fiord-valleys of northern latitudes1 which is a very old story 7far older than the ,pleistocene71 was the work not of glaciers but of running water1 at a time when north-western ,europe and the corresponding regions of ,america were much more elevated than they are now4 ,thus there appears to be no evidence either direct or indirect in favour of the view that glacial conditions were superinduced by great continental elevation4 ,but it may be argued that even although no evidence can be cited in proof of such elevation1 still1 if the glacial phenomena can be well explained by its means1 we may be justified in admitting it as a working hypothesis4 ,movements of elevation and depression have frequently taken place--the ,pleistocene marine deposits themselves testify to oscillations of the sea-level--and there can be no objection1 therefore1 to such postulations as are made by the hypothesis under review4 ,all this is readily granted1 but ,i deny that the conditions that obtained in ,pleistocene times can be accounted for by elevation and depression4 ,let us see how the desiderated elevation of northern lands would work4 ,were north-western ,europe and the corresponding latitudes of ,north ,america to be upheaved for #cjjj feet1 and a land-passage to obtain between the two continents by way of the ,fare ,islands1 ,iceland1 and ,greenland1 how would the climate be affected8 ,it is obvious that under such changed conditions the elevated lands in higher latitudes might well be subjected to more or less extensive glaciation4 ,norway would become uninhabitable and glaciers might well appear in the mountain-valleys of ,scotland4 ,but it may be doubted whether the climate of ,france and ,spain1 or the corresponding latitudes of ,north ,america1 would be much affected4 ,for were a land-passage to appear between ,britain and ,greenland no ,arctic current would flow into the ,north ,atlantic1 while no portion of the ,gulf ,stream would be lost in ,arctic seas4 ,the ,north ,atlantic would then form a great gulf round which a warm ocean-current would circulate4 ,the temperature of that sea1 therefore1 would be raised and the prevailing westerly and south-westerly winds of ,europe would be warmer than now4 ,however much such warm moist winds might increase the snow-fall in ,north ,britain and ,scandinavia1 we cannot suppose they could have much influence in central and southern ,europe1 and in ,north ,africa2 and still less could they affect the climate of ,asia ,minor and the mountainous regions of the far east1 in most of which evidence of extensive glaciation occurs4 ,and how1 we may ask1 could the postulated geographical changes bring about the glaciation of the mountainous tracts on the ,pacific sea-board8 ,in fine1 we may conclude that however much the geographical changes referred to might affect north-western ,europe and north-eastern ,america1 they are wholly insufficient to account for the glacial phenomena of other regions4 ,the continuous research of recent years has shown that the lowering of temperature of glacial times was not limited to the lands which would be affected by any such elevation as that we are considering4 ,a marked and general displacement of climatic zones took place over the whole continent of ,europe2 and similar changes supervened in ,north ,america and ,asia4 ,are we then to suppose that all the lands within the ,northern ,hemisphere were extensively and contemporaneously upheaved8 ,we may now consider another form of the earth-movement hypothesis4 ,it has frequently been suggested that our glacial phenomena may have been caused by the submergence of the ,isthmus of ,panama1 and the deflection of the ,equatorial ,current into the ,pacific4 ,but it may be doubted whether a submergence of that isthmus1 unless very extensive indeed1 would result in more than a partial escape of ,atlantic water into the ,pacific basin4 ,the ,counter ,current of the ,pacific which now strikes against the isthmus might even sweep into the ,caribbean ,sea1 and join the ,equatorial on its way to the ,gulf of ,mexico4 ,but putting that consideration aside1 what evidence have we that the ,isthmus of ,panama was submerged during the glacial epoch8 ,none whatsoever1 it may be replied4 ,it is only a pious opinion4 ,considerable movements of elevation and depression of the islands in the ,caribbean ,sea would seem to have taken place at a comparatively recent date1 but those movements may quite well belong to ,pliocene times4 ,whether they be of ,pliocene or ,pleistocene age1 however1 no one has yet proved that the ,isthmus of ,panama was sufficiently submerged1 either at the one time or the other1 to permit the escape of the ,atlantic ,equatorial into the ,pacific basin4 ,but let it be supposed that the isthmus has become so deeply submerged that the ,equatorial ,current is wholly deflected1 and that no ,gulf ,stream issues through the ,straits of ,florida to temper the climate of higher latitudes4 ,what would result from such an unhappy change8 ,can any one conversant with the geographical distribution of the glacial phenomena imagine that the conditions of the ,glacial period could be thus reproduced8 ,norway might indeed become a second south ,greenland1 and perennial snow and ice might appear in the mountainous tracts of the ,british ,islands4 ,the climate of ,hudson's ,bay and the surrounding lands might be experienced in the ,baltic and its neighbourhood1 and what are now the temperate latitudes of ,europe1 north of the #ejth parallel1 would possibly approach ,siberia in character4 ,but surely these changes are not comparable to the conditions of the ,glacial period4 ,the absence of a ,gulf ,stream would not sensibly affect the climate of south-eastern ,europe and ,asia1 and could not have the smallest influence on that of the ,pacific coast-lands of ,north ,america4 ,yes1 but if we conceive the submergence of the ,isthmus of ,panama to coincide with great elevation of northern lands1 would not such geographical conditions bring about a glacial epoch comparable to that of ,pleistocene times8 ,it is hard to see how they could4 ,no doubt the climate of all those regions that would be affected by the withdrawal of the ,gulf ,stream alone would become still more deteriorated if they stood some #cjjj feet higher than now4 ,a vast area in the north-west of ,europe would certainly be uninhabitable1 but it is for the advocates of the earth-movement hypothesis to explain why those inhospitable regions should necessarily be covered with an ice-sheet4 ,for the production of great snow-fields and continental ice-sheets1 considerable precipitation1 no less than a low temperature1 is requisite4 ,under the conditions we have been imagining1 however1 precipitation would probably be much less than it is at present4 ,but to whatever extent north-west ,europe might be glaciated1 it is obvious that the geographical revolutions referred to could have little influence on the climate of south-eastern ,europe1 not to mention central and eastern ,asia4 ,nor could they possibly influence the climate of the ,pacific coast-lands of ,north ,america4 ,and yet1 as is well known1 the climate of all those regions was more or less profoundly affected during the ,glacial period4 ,to account for the widespread evidences of glaciation by means of elevation it would therefore seem necessary to infer that all the affected areas were in ,pleistocene times uplifted en masse into the ,arctic zone that stretches above our heads4 ,now it seems easier to believe that the snow-line was lowered by several thousand feet than that the continents were elevated to the same extent4 ,glaciation1 as we have seen1 was developed in the same directions and over the same areas as we should expect it to be were the snow-line to be generally depressed4 ,to put it in another way1 were the snow-line by some means or other to be lowered over ,europe1 ,asia1 and ,north ,america1 then1 with sufficient precipitation1 great ice-fields and glaciers would reappear in the very regions which they visited during ,pleistocene times4 ,neither elevation nor depression of the land would be required to bring about such a result4 ,certain advocates of the earth-movement hypothesis1 however1 do not maintain that all the glaciated areas were uplifted at one and the same time4 ,the glaciation of the ,alps1 they think1 may have taken place earlier or later than that of north-western ,europe1 while the ice-period of the ,rocky ,mountains may not have coincided with that of eastern ,north ,america4 ,it is not impossible1 they suppose1 that the glaciation of the ,himalayas may have been caused by an uplifting of that great chain1 quite independent of similar earth-movements in other places4 ,it can be demonstrated1 however1 that the glaciation of the ,alps and of northern ,europe were contemporaneous1 and the facts go far to prove that the glaciers of the ,rocky ,mountains and the inland-ice of north-east ,america likewise co-existed4 ,at all events all the old glacial accumulations of our hemisphere are of ,pleistocene age1 and it is for the advocates of the hypothesis under review to prove that they are not contemporaneous4 ,their doubts on the subject probably arise from the simple fact that they are well aware how highly improbable or even impossible it is that all those glaciated lands could have been pushed up within the snow-line at one and the same time4 ,let me1 however1 advance to another objection4 ,we know that the ,glacial period was interrupted by at least one interglacial epoch of temperate and even genial conditions4 ,two glacial epochs with one protracted interglacial epoch are now generally admitted4 ,how do the supporters of the earth-movement hypothesis explain this remarkable succession of climatic changes8 ,their views as to the cause of glacial conditions we have considered4 ,if we can believe that the glacial phenomena were due to elevation of the land1 then we need have no difficulty in understanding how glacial conditions would disappear when the continents again subsided to a lower level4 ,not only did ,north ,america and ,europe lose all their early glacial elevation1 but by a lucky coincidence the ,isthmus of ,panama reappeared1 and the ,gulf ,stream resumed its beneficent course into the ,north ,atlantic4 ,this we are to suppose was the cause of the interglacial epoch4 ,but ,i would point out that the geographical conditions which are thus inferred to have brought about the disappearance of the glacial climate1 and to have ushered in the interglacial epoch1 are precisely those that now obtain--and1 nevertheless1 we are not yet in the enjoyment of a climate like that of interglacial times4 ,the strangely equable conditions that permitted the development of the remarkable ,pleistocene flora and fauna are not experienced in the ,europe of our day4 ,and what about the second glacial epoch8 ,are we to suppose that once more the lands were greatly uplifted1 and that convenient ,isthmus of ,panama was again depressed8 ,did the ,alps1 the ,pyrenees1 and the plateau of central ,france--in all of which we have distinct evidence of at least two glacial epochs--did these heights1 one may ask1 rise up to bring about their earlier glaciation1 sink down again to induce interglacial conditions1 and once more become uplifted at the succeeding cold epoch1 to subside eventually in order to cause a final retreat of their glaciers8 ,but the climatic changes to be accounted for were in all probability more numerous and complex than those just referred to4 ,competent observers have adduced unmistakable evidence of three epochs of glaciation in the ,alpine ,lands of ,europe4 ,and we are not without distinct hints that similar changes have taken place in northern and western ,europe4 ,nor in this connection can we ignore the evidence of several interglacial episodes which ,mr4 ,chamberlin and others have detected in the glaciated tracts of ,north ,america4 ,even this is not all1 for the upholders of the earth-movement hypothesis have still further to account for the climatic oscillations of post-glacial times4 ,if it be hard enough to allow the possibility of one great movement of elevation having affected so enormous an area of our hemisphere1 if we find it extremely difficult to believe either that one such widespread movement1 or that a multitude of local movements1 each more or less independent of the other1 could have lifted the glaciated regions successively within reach of the snow-line--we shall yet find it impossible to admit that such remarkable upheavals could be repeated again and again4 ,we seem driven to conclude1 therefore1 that the earth-movement hypothesis fails to explain the phenomena of ,pleistocene times4 ,one cannot deny1 indeed1 that glaciation might be induced locally by elevation of the land4 ,it is quite conceivable that mountains now below the limits of perennial snow might come to be ridged up to such an extent as to be capable of sustaining snow-fields and glaciers4 ,and such local movements may possibly have happened here and there during the long-continued ,pleistocene period4 ,but the glacial phenomena of that period are on much too grand a scale and far too widely distributed to be accounted for in that way4 ,and if the occurrence of even one glacial epoch cannot be thus explained1 we may leave the supporters of the earth-movement hypothesis to show us what light is thrown by their urim and thummim on the origin of succeeding interglacial and glacial climates4 ,there is yet another physical condition of the ,pleistocene and post-glacial periods which any adequate explanation must embrace4 ,i refer to the oscillation of sea-level1 of which so many proofs are forthcoming4 ,it is very remarkable that almost everywhere throughout the maritime regions of formerly glaciated areas we find evidence of submergence4 ,so commonly is this the case1 that geologists have long suspected that the connection between glaciation and submergence might be one of cause and effect4 ,the possible influence of great ice-sheets in disturbing the relative level of land and sea is a question1 therefore1 of very great importance4 ,it is one1 however1 which must be solved by physicists4 ,croll and others have advocated the view that the great accumulations of ice of the ,glacial period may have displaced the earth's centre of gravity1 and thus caused the sea to rise upon the glaciated hemisphere4 ,the various results arrived at by physicists are hardly comparable1 because each has used different data1 but it seems probable that we have in this view a vera causa of oscillations of the sea-level4 ,another hypothesis would explain the rise of the sea as due to the attractive influence of the great ice-masses1 but ,dr4 ,drygalski's and ,mr4 ,woodward's elaborate investigations would seem to have demonstrated that this notion does not account for the facts4 ,yet another speculation has been advanced4 ,mr4 ,jamieson has suggested that the mere weight of the ice-sheets would suffice to press down the earth's crust into a supposed liquid substratum1 and this explanation has met with much acceptance4 ,unfortunately our knowledge of the condition of the earth's interior is so very limited that we cannot be certain as to how the crust would be affected by the weight of an ice-sheet4 ,no doubt ,mr4 ,jamieson's hypothesis gives a specious explanation of certain geological phenomena1 but if there be no liquid substratum underlying a thin crust it cannot be true4 ,at present the prevalent view of physicists appears to be that the earth is substantially solid4 ,professor ,george ,darwin has shown that the prominent inequalities of the earth's surface could not be sustained unless the crust be as rigid as granite for a depth of #ajjj miles4 ,if the earth be solid throughout1 he remarks1 then at #ajjj miles from the surface the material must be as strong as granite4 ,if it be fluid or gaseous inside1 and the crust #ajjj miles thick1 that crust must be stronger than granite1 and if only #bjj or #cjj miles in thickness1 much stronger than granite4 ,this conclusion is obviously strongly confirmatory of ,sir ,william ,thomson's view1 that the earth is solid throughout4 ,but many geologists find it hard to account for the convolutions of strata and other structural phenomena on the supposition that the earth is entirely solid1 and they are inclined1 therefore1 to adopt the hypothesis of a sub-crust layer of liquid matter4 ,whether this be actually the condition or not physicists must be left to determine4 ,all that we need note is1 that if there be any force in ,professor ,darwin's argument1 it is obvious that the crust is possessed of great rigidity1 and could not be readily deformed by the mere weight of an ice-sheet4 ,according to ,dr4 ,drygalski1 however1 the presence of an ice-sheet1 by reducing the temperature of the underlying crust1 would bring about contraction1 and in this way cause the surface to sink4 ,when the ice-sheet had disappeared1 then free radiation of earth-heat would be resumed1 the depressed isogeotherms would rise1 and a general warming of the upper portion of the lithosphere would take place4 ,but the space occupied by the depressed section1 owing to the spheroidal form of the earth1 would be smaller than that which it occupied before sinking had commenced1 and consequently when the ice vanished expansion of the crust would follow1 and the land-surface would then rise again4 ,the whole question is one for physicists to decide upon1 but ,i may point out that if ,drygalski's explanation be well founded1 then it is obvious that it throws no light upon the origin and subsequent disappearance of an ice-sheet4 ,somehow or other this ice-sheet comes into existence1 and the cooling and contracting crust sinks below it2 and that depressed condition of the glaciated area must continue so long as the ice-sheet remains unmelted4 ,re-elevation can only take place when1 owing to some other cause or causes1 the climate changes and the ice-sheet vanishes4 ,those who advocate the earth-movement hypothesis as an explanation of the origin of extensive glaciation have welcomed ,mr4 ,jamieson's view as harmonising well with their conclusions4 ,they contend1 as we have seen1 that glacial conditions were induced by an extensive upheaval of the crust in northern latitudes1 accompanied by a depression of the ,isthmus of ,panama4 ,they then proceed to point out that the ice-sheets brought about their own dissolution by pressing down the crust1 and introducing with submergence a disappearance of glacial conditions4 ,see now how much they take for granted4 ,in the first place1 they assume an amount of pre-glacial or early glacial elevation of northern regions for which not a scrap of evidence can be adduced1 while they can give no proof of contemporaneous depression of the ,isthmus of ,panama4 ,next1 relying on ,mr4 ,jamieson's hypothesis1 they take for granted that the ice-sheets1 called into existence by their postulated earth-movements1 succeeded in depressing the earth's surface even below its present level4 ,that is to say1 the land1 which1 according to them1 was in glacial times some #cjjj feet higher than now1 sank down under the weight of its glacial covering for1 say1 #cfjj feet in north-western ,europe4 ,in ,north ,america1 in like manner1 all the pre-glacial elevation was lost--the land sinking below its present level for some #bjj feet in ,new ,england1 for #ebj feet at ,montreal1 for #ajjj to #aejj feet in ,labrador1 and for #ajjj to #bjjj feet in the ,arctic regions4 ,now1 even if we concede the reasonableness of ,mr4 ,jamieson's hypothesis1 and admit that a certain degree of deformation may take place under the mere weight of an ice-sheet1 it is difficult to believe that the crust can be so readily deformed as the supporters of the earth-movement hypothesis seem to imply4 ,if it could yield so readily to pressure1 one is at a loss to understand how a great ice-sheet could accumulate--the ice would simply float off as the land subsided4 ,take the case of north-western ,europe4 ,the ice-sheet that covered ,scotland did not attain1 on the average1 #cjjj feet in thickness1 and yet we are to suppose that it was able to depress the land for some #fjj feet below its present level--that is to say1 for #cfjj feet below its assumed pre-glacial elevation4 ,either the ice depressed the crust to that remarkable extent1 or the land upon which the ice accumulated was not nearly so high as the advocates of the earth-movement hypothesis have supposed4 ,but the average ,i have taken for the thickness of the ,scottish ice-sheet is excessive1 for it was only in the low-grounds that the mer de glace attained such a depth4 ,a large part of our country1 however1 is mountainous1 and the mountain-tops were1 of course1 not nearly so thickly mantled with ice as the valleys4 ,and the same to even a larger extent holds good for the ,scandinavian peninsula4 ,if we take the thickness of the ,scandinavian ice-sheet that coalesced with that of ,scotland as #djjj feet1 we shall be over the mark4 ,now1 ,i ask1 is it possible to believe that a sheet of ice of that thickness actually pressed down the crust of the earth for not less than #cfjj feet8 ,but if we accept the earth-movement hypothesis1 as it has been recently advocated1 that is what we must believe4 ,if we cannot do so1 then we cannot accept the assumption of great elevation of the land in pre-glacial and glacial times4 ,let me put the case shortly3 if the glacial marine beds and raised beaches of the ,atlantic borders of ,europe and ,north ,america owe their origin to depression induced by the weight of an ice-sheet1 then it is quite certain that at the advent of glacial conditions the land could not have been so highly elevated as the advocates of the earth-movement hypothesis suppose4 ,but if we are to accept the notion of great elevation of the land1 then we must conclude that the submergence to which the raised beaches testify cannot have been caused by the pressure of ice-sheets4 ,it is hardly necessary to pursue this particular subject further1 but before leaving it1 attention may be drawn for a moment to the curious conclusion that the ice-sheets were self-destructive4 ,one is left to guess at what particular stage the sinking process began1 but if the earth's crust were as readily deformed as the extreme views ,i have been examining would compel one to imply1 then depression must have commenced almost immediately with the accumulation of snow and ice4 ,the several ice-sheets must soon have attained their maximum thickness1 and their disappearance must have been correspondingly rapid4 ,and yet all the evidence goes to show that a glacial epoch endured for a comparatively long time--for a time sufficient to account for a prodigious amount of rock-erosion1 and for the accumulation of vast sheets of glacial dbris and fluvio-glacial detritus4,,by ,,by ,it must not be inferred from the above remarks that ,i deny the possibility of deformation of the crust having been induced by the old ice-sheets4 ,the geological evidence is certainly suggestive of such having been the case4 ,but ,i much doubt whether the sinking of the surface was brought about by the mere weight of the ice pressing the crust down into a subjacent liquid layer4 ,dr4 ,drygalski's explanation would better account for the geological phenomena1 but1 according to ,rev4 ,osmond ,fisher1 it cannot be maintained4 ,if it be difficult to understand how the earth-movement hypothesis can account for the origin of one glacial epoch1 the difficulty is not lessened when we remember that there are two or more such epochs to account for4 ,and until the advocates of that hypothesis can furnish us with some reliable evidence1 they can hardly expect us to believe in their mysterious upheavals and depressions of northern and temperate regions1 and in the no less wonderfully rhythmic movements of the ,isthmus of ,panama4 ,in fine1 the views which ,i have been controverting seem to me to be untenable1 inasmuch as they are founded on mere assumptions1 and do not even give a reasonable and intelligible explanation of the phenomena of glaciated regions1 while they practically ignore or leave unsolved the problem of interglacial conditions4 ,some five-and-twenty years have now elapsed since my lamented friend and colleague1 ,james ,croll1 published his well-known physical theory of the ,glacial period4 ,that theory1 as you all know1 has been frequently criticised by physicists and others1 to whose objections ,croll made a final reply in his ,climate and ,cosmology4 ,in that work he has successfully defended his views1 and even added considerably to the strength of his general argument4 ,i am not aware that since then any serious objections to ,croll's theory have appeared4 ,the only one indeed that seems to have attracted attention is that which has been urged especially by certain ,american geologists4 ,their belief is that the close of the ,glacial period must have taken place at a much more recent date than ,croll has inferred4 ,and this belief of theirs is based upon various estimates which have been made as to the time required for the erosion of valleys and the accumulation of alluvial deposits since the ,glacial period4 ,thus1 according to ,mr4 ,gilbert1 the post-glacial gorge of ,niagara1 at the present rate of erosion1 must have been excavated within #gjjj years2 while ,mr4 ,winchell1 from similar measurements of the post-glacial erosion of the ,falls of ,st4 ,anthony1 concludes that #hjjj years have elapsed since the close of the ,ice ,age4 ,i might cite a number of similar estimates that tend to show that since the close of the ,glacial period only #gjjj or #aj1jjj years have elapsed4 ,what will archologists say to this conclusion8 ,we know that ,egypt was already occupied by a civilised people nearly #fjjj years ago1 and their marvellously advanced civilisation at that time presupposes1 according to ,egyptologists1 many thousands of years of development4 ,are we1 then1 prepared to admit that the close of the ,ice ,age coincided with the dawn of ,egyptian civilisation8 ,but all ,american observers are not so parsimonious with regard to post-glacial time4 ,thus ,professor ,spencer has given the age of the ,falls of ,niagara as #bd1jjj years1 and he informed me recently that this does not represent half of the time since the formation of the third great series of glacial deposits of the ,canadian uplands4 ,in our own ,continent similar estimates have been based on the rate of erosion of river-valleys1 the rate of accumulation of alluvial deposits1 of peat-bogs1 of stalagmite in caves1 and what not1 with results that1 to say the least1 are rather discordant4 ,the fact is that all such measurements and estimates1 however carefully conducted and cautiously made1 are in the nature of things unreliable4 ,we are insufficiently acquainted with all the factors of the problem to be solved1 and ,i cannot therefore agree with those who attribute much weight to conclusions based on such uncertain data4 ,dr4 ,croll's theory may eventually be modified1 but ,i feel sure that it will not be overturned by the inconclusive and unsatisfactory estimates to which ,i have referred4 ,moreover1 opponents of that theory may be reminded that its truth does not rest on the accuracy of its author's conclusion as to the date of the last ,ice ,age4 ,that periods of high eccentricity of the earth's orbit have occurred is beyond all doubt1 but whether the formul employed by ,croll in calculating the date of the last great cycle can be relied upon for that purpose is quite another question4 ,at present1 so far as ,i understand the facts1 the glacial and the interglacial phenomena are explained by the astronomical theory1 and by no other4 ,it gives a simple1 coherent1 and consistent interpretation of the climatic vicissitudes of the ,pleistocene and post-glacial periods1 and in especial it is the only theory that throws any light on the very remarkable climates of interglacial times4 ,x4 ,the ,glacial ,succession in ,europe4,,bz ,,bz ,trans4 ,royal ,soc4 ,edinburgh1 vol4 xxxvii4 7#ahib74 ,for many years geologists have recognised the occurrence of at least two boulder-clays in the ,british ,islands and the corresponding latitudes of the ,continent4 ,it is no longer doubted that these are the products of two separate and distinct glacial epochs4 ,this has been demonstrated by the appearance of intercalated deposits of terrestrial1 freshwater1 or1 as the case may be1 marine origin4 ,such interglacial accumulations have been met with again and again in ,britain1 and they have likewise been detected at many places on the ,continent1 between the border of the ,north ,sea and the heart of ,russia4 ,their organic contents indicate in some cases cold climatic conditions2 in others1 they imply a climate not less temperate or even more genial than that which now obtains in the regions where they occur4 ,nor are such interglacial beds confined to northern and north-western ,europe4 ,in the ,alpine ,lands of the central and southern regions of our ,continent they are equally well developed4 ,impressed by the growing strength of the evidence1 it is no wonder that geologists1 after a season of doubt1 should at last agree in the conclusion that the glacial conditions of the ,pleistocene period were interrupted by at least one protracted interglacial epoch4 ,not a few observers go further1 and maintain that the evidence indicates more than this4 ,they hold that three or even more glacial epochs supervened in ,pleistocene times4 ,this is the conclusion ,i reached many years ago1 and ,i now purpose reviewing the evidence which has accumulated since then1 in order to show how far it goes to support that conclusion4 ,in our islands we have1 as already remarked1 two boulder-clays1 of which the lower or older has the wider extension southwards1 for it has been traced as far as the valley of the ,thames4 ,the upper boulder-clay1 on the other hand1 does not extend south of the midlands of ,england4 ,in the north of ,england1 and throughout ,scotland and the major portion of ,ireland1 it is this upper boulder-clay which usually shows at the surface4 ,the two clays1 however1 frequently occur together1 and are exposed again and again in deep artificial and natural sections1 as in pits1 railway-cuttings1 quarries1 river-banks1 and sea-cliffs4 ,sometimes the upper clay rests directly upon the lower2 at other times they are separated by alluvial and peaty accumulations or by marine deposits4 ,the wider distribution of the lower till1 the direction of transport of its included erratics1 and the trend of the underlying roches moutonnes and rock-stri1 clearly show that the earlier mer de glace covered a wider area than its successor1 and was confluent on the floor of the ,north ,sea with the ,scandinavian ice-sheet4 ,it was during the formation of the lower till1 in short1 that glaciation in these islands attained its maximum development4 ,the interglacial beds1 which in many places separate the lower from the upper till1 show that after the retreat of the earlier mer de glace the climate became progressively more temperate1 until eventually the country was clothed with a flora essentially the same as the present4 ,wild oxen1 the great ,irish deer1 and the horse1 elephant1 rhinoceros1 and other mammals then lived in ,britain4 ,from the presence of such a flora and fauna we may reasonably infer that the climate during the climax of interglacial times was as genial as now4 ,the occurrence of marine deposits associated with some of the interglacial peaty beds shows that eventually submergence ensued2 and as the shells in some of the marine beds are boreal and arctic forms1 they prove that cold climatic conditions accompanied the depression of the land4 ,to what extent the land sank under water we cannot tell4 ,it may have been #ejj feet or not so much1 for the evidence is somewhat unsatisfactory4 ,the upper boulder-clay of our islands is the product of another mer de glace1 which in ,scotland would seem to have been hardly less thick and extensive than its predecessor4 ,like the latter1 it covered the whole country1 overflowed the ,outer ,hebrides1 and became confluent with the ,scandinavian inland-ice on the bed of the ,north ,sea4 ,but it did not flow so far to the south as the earlier ice-sheet4 ,it is well known that this later mer de glace was succeeded in our mountain-regions by a series of large local glaciers1 which geologists generally believe were its direct descendants4 ,it is supposed1 in short1 that the inland-ice1 after retreating from the low-grounds1 persisted for a time in the form of local glaciers in mountain-valleys4 ,this view ,i also formerly held1 although there were certain appearances which seemed to indicate that1 after the ice-sheet had melted away from the ,lowlands and shrunk far into the mountains1 a general advance of great valley-glaciers had taken place4 ,i had observed1 for example1 that the upper boulder-clay is often well developed in the lower reaches of our mountain-valleys--that1 in fact1 it may be met with more or less abundantly up to the point at which large terminal moraines are encountered4 ,more than this1 ,i had noticed that upland valleys1 in which no local or terminal moraines occur1 are usually clothed and paved with boulder-clay throughout4 ,again1 the aspect of valleys which have been occupied by large local glaciers is very suggestive4 ,above the point at which terminal moraines occur only meagre patches of till are met with on the bottoms of the valleys4 ,the adjacent hill-slopes up to a certain line may show bare rock1 sprinkled perchance with erratics and superficial morainic detritus2 but above this line1 if the acclivity be not too great1 boulder-clay often comes on again4 ,these appearances are most conspicuously displayed in the southern ,uplands of ,scotland1 particularly in south ,ayrshire and ,galloway1 and long ago they led me to suspect that the local glaciers into which our latest mer de glace was resolved1 after retreating continuously towards the heads of their valleys1 so as to leave the boulder-clay in a comparatively unmodified condition1 had again advanced and ploughed this out1 down to the point at which they dropped their terminal moraines4 ,subsequent observations in the ,highlands and the ,inner and ,outer ,hebrides confirmed me in my suspicion1 for in all those regions we meet with phenomena of precisely the same kind4 ,my friends and colleagues1 ,messrs4 ,peach and ,horne1 had independently come to a similar conclusion2 and the more recent work of the ,geological ,survey in the north-west ,highlands1 as they inform me1 has demonstrated that after the dissolution of the general ice-sheet underneath which the upper boulder-clay was accumulated1 a strong recrudescence of glacial conditions supervened1 and a general advance of great valley-glaciers took place--the glaciers in many places coalescing upon the low-grounds to form united mers de glace of considerable extent4 ,the development of these large glaciers1 therefore1 forms a distinct stage in the history of the ,glacial period4 ,they were of sufficient extent to occupy all the fiords of the northern and western ,highlands1 at the mouths of which they calved their icebergs1 and they descended the valleys on the eastern slopes of the land into the region of the great lakes1 at the lower ends of which we encounter their outermost terminal moraines4 ,the ,shetland and ,orkney ,islands and the ,inner and ,outer ,hebrides at the same time nourished local glaciers1 not a few of which flowed into the sea4 ,such1 for example1 was the case in ,skye1 ,harris1 ,south ,uist1 and ,arran4 ,the broad ,uplands of the south were likewise clothed with snow-fields that fed numerous glaciers4 ,these were especially conspicuous in the wilds of ,galloway1 but they appeared likewise in the ,peeblesshire hills2 and even in less elevated tracts they have left more or less well-marked traces of their former presence4 ,it is to this third epoch of glaciation that ,i would assign the final scooping out of our lake-basins and the completion of the deep depressions in the beds of our ,highland fiords4 ,all the evidence1 indeed1 leads to the conviction that the epoch was one of long duration4 ,it goes without saying that what holds good for ,scotland must1 within certain limits1 hold good also for ,ireland and ,england4 ,in ,wales and the ,cumberland lake district1 and in the mountain-regions of the sister island1 we meet with evidence of similar conditions4 ,each of those areas has obviously experienced intense local glaciation subsequent to the disappearance of the last big ice-sheet4 ,attention must now be directed to another series of facts which help us to realise the general conditions that obtained during the epoch of local glaciation4 ,in the basin of the estuary of the ,clyde1 and at various other places both on the west and east coasts of ,scotland1 occur certain clays and sands1 which overlie the upper boulder-clay1 and in some places are found wrapping round the kames and osar of the last great ice-sheet4 ,these beds are charged with the relics of a boreal and arctic fauna1 and indicate a submergence of rather more than #ajj feet4 ,in the lower reaches of the rivers ,clyde1 ,forth1 and ,tay the clays and sands form a well-marked terrace1 and a raised sea-beach1 containing similar organisms1 occurs here and there on the sea-coast1 as between ,dundee and ,arbroath1 on the southern shores of the ,moray ,firth1 and elsewhere4 ,when the terraces are traced inland they are found to pass into high-level fluviatile gravels1 which may be followed into the mountain-valleys1 until eventually they shade off into fluvio-glacial detritus associated with the terminal moraines of the great local glaciers4 ,it is obvious1 in short1 that the epoch of local ice-sheets and large valley-glaciers was one also of partial submergence4 ,this is further shown by the fact that in some places the glaciers that reached the sea threw down their moraines on the #ajj-;feet beach4 ,it must have been an epoch of much floating ice1 as the marine deposits contain now and again many erratics1 large and small1 and are1 moreover1 frequently disturbed and contorted as if from the grounding of pack-ice4 ,the phenomena which ,i have thus briefly sketched suffice to show that the epoch of local glaciation is to be clearly distinguished from that of the latest general mer de glace4 ,i have long suspected1 indeed1 that the two may have been separated by as wide an interval of time as that which divided the earlier from the later epoch of general glaciation4 ,again and again ,i have searched underneath the terminal moraines1 in the faint hope of detecting interglacial accumulations4 ,my failure to discover these1 however1 did not weaken my conviction1 for it was only by the merest chance that interglacial beds could ever have been preserved in such places4 ,i feel sure1 however1 that they must occur among the older alluvia of our ,lowlands4 ,indeed1 as ,i shall point out in the sequel1 it is highly probable that they are already known1 and that we have hitherto failed to recognise their true position in the glacial series4 ,although we have no direct evidence to prove that a long interglacial epoch of mild conditions immediately preceded the advent of our local ice-sheets and large valley-glaciers1 yet the indirect evidence is so strong that we seem driven to admit that such must have been the case4 ,to show this ,i must briefly recapitulate what is now known as to the glacial succession on the ,continent4 ,it has been ascertained1 then1 that the ,scandinavian ice has invaded the low-grounds of ,germany on two separate occasions1 which are spoken of by ,continental geologists as the first and second glacial epochs4 ,the earlier of these was the epoch of maximum glaciation1 when the inland ice flowed south into ,saxony1 and overspread a vast area between the borders of the ,north ,sea and the base of the ,ural ,mountains4 ,this ice-sheet unquestionably coalesced with the mer de glace of the ,british ,islands4 ,its bottom-moraine and the associated fluvio-glacial detritus are known in ,germany as ,lower ,diluvium1 and the various phenomena connected with it clearly show that the inland-ice radiated outwards from the high-grounds of ,scandinavia4 ,the terminal front of that vast mer de glace is roughly indicated by a line drawn from the south coast of ,belgium round the north base of the ,harz1 and by ,leipzig and ,dresden to ,krakow1 thence north-east to ,nijnii ,novgorod1 and further north to the head-waters of the ,dvina and the shores of the ,arctic ,sea near the ,tcheskaia ,gulf4 ,the lower diluvium is covered in certain places by interglacial deposits and an overlying upper diluvium--a succession clearly indicative of climatic changes4 ,in the interglacial beds occur remains of ,elephas antiquus and other ,pleistocene mammals1 and a flora which denotes a genial temperate climate4 ,one of the latest discoveries of interglacial remains is that of two peat-beds lying between the lower and upper diluvium near ,grnenthal in ,holstein4,,ca ,among the abundant plant-relics are pines and firs 7no longer indigenous to ,schleswig-,holstein71 aspen1 willow1 white birch1 hazel1 hornbeam1 oak1 and juniper4 ,associated with these are ,ilex and ,trapa natans1 the presence of which1 as ,dr4 ,weber remarks1 betokens a climate like that of western middle ,germany4 ,amongst the plants is a water-lily1 which occurs also in the interglacial beds of ,switzerland1 but is not now found in ,europe4 ,the evidence furnished by this and other interglacial deposits in north ,germany shows that1 after the ice-sheet of the lower diluvium had melted away1 the climate became as temperate as that now experienced in ,europe4 ,another recent find of the same kind,,cb is the diluvial peat1 etc41 of ,klinge1 in ,brandenburg1 described by ,professor ,nehring4 ,these beds have yielded remains of elk 7,cervus alces71 rhinoceros 7species not determined71 a small fox 7871 and ,megaceros4 ,this latter is not the typical great ,irish deer1 but a variety 7,c4 megaceros1 var4 ,ruffii1 ,nehring74 ,the plant-remains include pine1 fir 7,picea excelsa71 hornbeam1 warty birch 7,betula verrucosa71 various willows 7,salix repens1 ,s4 aurita1 ,s4 caprea 81 ,s4 cinerea71 hazel1 poplar 7871 common holly1 etc4 ,it is worthy of note that here also the interglacial water-lily 7,cratopleura7 of ,schleswig-,holstein and ,switzerland makes its appearance4 ,dr4 ,weber writes me that the facies of this flora implies a well-marked temperate insular climate 7,seeklima74 ,the occurrence of holly in the heart of the ,continent1 where it no longer grows wild1 is particularly noteworthy4 ,the evidence furnished by such a flora leads one to conclude that at the climax of the genial interglacial epoch1 the ,scandinavian snow-fields and glaciers were not more extensive than they are at present4 ,,ca ,neues ,jahrbuch f4 ,min4 ,geol4 u4 ,palont41 #ahia1 ii41 pp4 #fb1 #bbh2 ,ibid41 #ahib1 i41 p4 #aad4 ,,cb ,naturwissenschaftliche ,wochenschrift1 ,bd4 vii4 7#ahib71 ,no4 #d1 p4 #ca4 ,the plants were determined by ,dr4 ,weber1 ,professor ,wittmack1 and ,herr ,warnstorf4 ,more recent investigations have considerably increased our knowledge of this flora4 ,see ,naturwissenschaftliche ,wochenschrift1 ,bd4 vii4 7#ahib71 ,nr4 #bd1 #be4 ,ausland1 #ahib1 ,nr4 #bj2 ,neues ,jahrb4 f4 ,min41 etc41 #ahic1 ,bd4 i41 p4 #ie4 ,the presence of the upper diluvium1 however1 proves that such genial conditions eventually passed away1 and that an ice-sheet again invaded north ,germany4 ,but this later invasion was not on the same scale as that of the preceding one4 ,the geographical distribution of the upper diluvium and the position of large terminal moraines put this quite beyond doubt4 ,the boulder-clay in question spreads over the ,baltic provinces of ,germany1 extending south as far as ,berlin1,,cc and west into ,schleswig-,holstein and ,denmark4 ,at the climax of this later cold epoch glaciers occupied all the fiords of ,norway1 but did not advance beyond the general coast-line4 ,norway at that time must have greatly resembled ,greenland--the inland-ice covering the interior of the country1 and sending seawards large glaciers that calved their icebergs at the mouths of the great fiords4 ,in the extreme south1 however1 the glaciers did not quite reach the sea1 but piled up large terminal moraines on the coast-lands1 which may be followed thence into ,sweden in an easterly direction by the lower end of ,lake ,wener and through ,lake ,wetter4 ,a similar belt of moraines marks out the southern termination of the ice-sheet in ,finland4 ,between ,sweden and ,finland lies the basin of the ,baltic1 which1 at the epoch in question was filled with ice1 forming a great ,baltic glacier4 ,this glacier overflowed the land ,islands1 ,gottland1 and land1 fanning out as it passed towards the south-west and west1 so as to invade on the south the ,baltic provinces of ,germany1 while in the north it traversed the southern part of ,scania1 and overwhelmed the ,danish islands as it spread into ,jutland and ,schleswig-,holstein4 ,the course of this second ice-sheet is indicated by the direction of transport of erratics1 etc41 and by the trend of rock-stri and roches moutonnes1 as well as by the position of its terminal and lateral moraines4 ,,cc ,not quite so far south4 ,there is no reason to believe that the ice-sheet of the so-called ,great ,baltic ,glacier advanced beyond the ,baltic ridge4 ,the upper boulder-clay south of that ridge is the ground-moraine of an earlier glaciation--the equivalent of our upper boulder-clay4 ,see note1 page #cbd4 ,nov4 #a1 #ahib4 ,such1 then1 is the glacial succession which has been established by geologists in ,scandinavia1 north ,germany1 and ,finland4 ,the occurrence of two glacial epochs1 separated by a long interval of temperate conditions1 has been proved4 ,the evidence1 however1 does not show that there may not have been more than two glacial epochs4 ,there are certain phenomena1 indeed1 connected with the glacial accumulations of the regions in question which strongly suggest that the succession of changes was more complex than is generally understood4 ,several years ago ,dr4 ,a4 ,g4 ,nathorst adduced evidence to show that a great ,baltic glacier1 similar to that underneath which the upper diluvium was amassed1 existed before the advent of the vast mer de glace of the so-called first glacial epoch1,,cd and his observations have been confirmed and extended by ,h4 ,lundbohm4,,ce ,the facts set forth by them prove beyond doubt that this early ,baltic glacier smoothed and glaciated the rocks in southern ,sweden in a direction from south-east to north-west1 and accumulated a bottom-moraine whose included erratics are equally cogent evidence as to the trend of glaciation4 ,that old moraine is overlaid by the lower diluvium--i4e41 the boulder-clay1 etc41 of the succeeding vast mer de glace that flowed south to the foot of the ,harz--the transport of the stones in the superjacent clay indicating a movement from ,,nne4 to ,,ssw41 or nearly at right angles to the trend of the earlier ,baltic glacier4 ,it is difficult to avoid the conclusion that we have here to do with the products of two distinct ice-epochs4 ,but hitherto no interglacial deposits have been detected between the boulder-clays in question4 ,it might1 therefore1 be held that the early ,baltic glacier was separated by no long interval of time from the succeeding great mer de glace1 but may have been merely a stage in the development of the latter4 ,it is at all events conceivable that before the great mer de glace attained its maximum extension1 it might have existed for a time as a large ,baltic glacier4 ,i would point out1 however1 that if no interglacial beds had been recognised between the lower and the upper diluvium1 geologists would probably have considered that the last great ,baltic glacier was simply the attenuated successor of the preceding continental mer de glace4 ,but we know this was not so2 the two were actually separated by a long epoch of genial temperate conditions4 ,,cd ,beskrifning4 till geol4 ,kartbl4 ,trolleholm3 ,sveriges ,geologiska ,underskning1 ,ser4 ,aa41 ,nr4 #hg4 ,,ce ,om de ldre baltiska isstrmmen i sdra ,sverige3 ,geolog4 ,frening4 i ,stockholm ,frhandl41 ,bd4 x41 p4 #aeg4 ,there are certain other facts that may lead us to doubt whether in the glacial phenomena of the ,baltic coast-lands we have not the evidence of more than two glacial epochs4 ,three1 and even four1 boulder-clays have been observed in east and west ,prussia4 ,they are separated1 the one from the other1 by extensive aqueous deposits1 which are sometimes fossiliferous4 ,moreover1 the boulder-clays in question have been followed continuously over considerable areas4 ,it is quite possible1 of course1 that all those boulder-clays may be the product of one epoch1 laid down during more or less considerable oscillations of an ice-sheet4 ,in this view of the case the intercalated aqueous deposits would indicate temporary retreats1 while the boulder-clays would represent successive re-advances of one and the same mer de glace4 ,on the other hand1 it is equally possible1 if not more probable1 that the boulder-clays and intercalated beds are evidence of so many separate glacial and interglacial epochs4 ,we cannot yet say which is the true explanation of the facts4 ,but these being as they are1 we may doubt if ,german glacialists are justified in so confidently maintaining that their lower and upper diluvial accumulations are the products of the first and second glacial epochs4 ,indeed1 as ,i shall show presently1 the upper diluvium of north ,germany and ,finland cannot represent the second glacial epoch of other parts of ,europe4 ,for a long time it has been supposed that the glacial deposits of the central regions of ,russia were accumulated during the advance and retreat of one and the same ice-sheet4 ,in #ahhh1 however1 ,professor ,pavlow brought forward evidence to show that the province of ,nijnii ,novgorod had been twice invaded by a general mer de glace4 ,during the first epoch of glaciation the ice-sheet overflowed the whole province1 while only the northern half of the same region was covered by the mer de glace of the second invasion4 ,again1 ,professor ,armachevsky has pointed out that in the province of ,tchernigow two types of glacial deposits appear1 so unlike in character and so differently distributed that they can hardly be the products of one and the same ice-sheet4 ,but until recently no interglacial deposits had been detected1 and the observations just referred to failed1 therefore1 to make much impression4 ,the missing link in the material evidence has now happily been supplied by ,m4 ,krischtafowitsch4,,cf ,at ,trozkoje1 in the neighbourhood of ,moscow1 occur certain lacustrine formations which have been long known to ,russian geologists4 ,these have been variously assigned to ,tertiary1 lower glacial1 post-glacial1 and pre-glacial horizons4 ,they are now proved1 however1 to be of interglacial age1 for they rest upon and are covered by glacial accumulations4 ,amongst their organic remains are oak 7,quercus pedunculata71 alder 7,alnus glutinosa1 ,a4 incana71 white birch1 hazel1 ,norway maple 7,acer platanoides71 ,scots fir1 willow1 water-lilies 7,nuphar1 ,nympha71 mammoth1 pike1 perch1 ,anadonta1 wing-cases of beetles1 etc4 ,the character of the plants shows that the climate of central ,russia was milder and more humid than it is to-day4 ,,cf ,bull4 de la ,soc4 ,impr4 des ,naturalistes de ,moskau1 ,no4 #d1 #ahij4 ,it is obvious that the upper and lower glacial deposits of central ,russia cannot be the equivalents of the upper and lower diluvium of the ,baltic coast-lands4 ,the upper diluvium of those regions is the bottom-moraine of the so-called great ,baltic glacier4 ,at the time that glacier invaded north ,germany1 ,finland was likewise covered with an ice-sheet1 which flowed towards the south-east1 but did not advance quite so far as the northern shores of ,lake ,ladoga4 ,a double line of terminal moraines1 traced from ,hango ,head on the ,gulf of ,finland1 north-east to beyond ,joensuu1 puts this beyond doubt4,,cg ,the morainic deposits that overlie the interglacial beds of central ,russia cannot1 therefore1 belong to the epoch of the great ,baltic glacier4 ,they are necessarily older4 ,in short1 it is obvious that the upper and lower glacial accumulations near ,moscow must be on the horizon of the lower diluvium of north ,germany4 ,and if this be so1 then it is clear that the latter cannot be entirely the product of one and the same mer de glace4 ,when the several boulder-clays described by ,schrder and others as occurring in the ,baltic provinces of ,germany are reinvestigated1 they may prove to be the bottom-moraines of as many distinct and separate glacial epochs4 ,,cg ,sederholm1 ,fennia1 i41 ,no4 #g2 ,frosterus1 ibid41 iii41 ,no4 #h2 ,ramsay1 ibid41 iv41 ,no4 #b4 ,it may be contended that the glacial and interglacial deposits of central ,russia are perhaps only local developments--that their evidence may be accounted for by the oscillations of one single mer de glace4 ,this explanation1 as already pointed out1 has been applied to the boulder-clays and intercalated aqueous beds of the lower diluvium of north ,germany1 and the prevalent character of the associated organic remains makes it appear plausible4 ,it is quite inapplicable1 however1 to the similar accumulations in central ,russia4 ,during the formation of the freshwater beds of ,trozkoje1 no part of ,russia could have been occupied by an ice-sheet2 the climate was more genial and less continental than the present4 ,yet that mild interglacial epoch was preceded and succeeded by extremely arctic conditions4 ,it is impossible that such excessive changes could have been confined to central ,russia4 ,germany1 and indeed all northern and north-western ,europe1 must have participated in the climatic revolutions4 ,so far1 then1 as the evidence has been considered1 we may conclude that three glacial and two interglacial epochs at least have been established for northern ,europe4 ,if this be the case1 then a similar succession ought to occur in our own islands2 and a little consideration of the evidence already adduced will suffice to show that it does4 ,it will be remembered that the lower and upper boulder-clays of the ,british ,islands are the bottom-moraines of two separate and distinct ice-sheets1 each of which in its time coalesced on the floor of the ,north ,sea with the inland-ice of ,scandinavia4 ,it is obvious1 therefore1 that our upper boulder-clay cannot be the equivalent of the upper diluvium of the ,baltic coast-lands1 of ,sweden1 ,denmark1 and ,schleswig-,holstein4 ,de ,geer and others have shown that while the great ,baltic glacier was accumulating the upper diluvium of ,north ,germany1 etc41 the inland-ice of ,norway calved its icebergs at the mouths of the great fiords4 ,thus1 during the so-called second glacial epoch of ,scandinavian and ,german geologists1 the ,norwegian inland-ice did not coalesce with any ,british mer de glace4 ,the true equivalent in this country of the upper diluvium is not our upper boulder-clay1 but the great valley-moraines of our mountain-regions4 ,it is our epoch of large valley-glaciers which corresponds to that of the great ,baltic ice-flow4 ,our upper and lower boulder-clays are on the horizon of the lower diluvium of ,germany and the glacial deposits of central ,russia4 ,it will now be seen that the evidence in ,britain is fully borne out by what is known of the glacial succession in the corresponding latitudes of the ,continent4 ,i had inferred that our epoch of large valley-glaciers formed a distinct stage by itself1 and was probably separated from that of the preceding ice-sheet by a prolonged interval of interglacial conditions4 ,one link in the chain of evidence1 however1 was wanting3 ,i could not point to the occurrence of interglacial deposits underneath the great valley-moraines4 ,but these1 as we have seen1 form a well-marked horizon on the ,continent1 and we cannot doubt that a similar interglacial stage obtained in these islands4 ,we may feel confident1 in fact1 that genial climatic conditions supervened on the dissolution of the last great mer de glace in ,britain1 and that the subsequent development of extensive snow-fields and glaciers in our mountain-regions was contemporaneous with the appearance of the last great ,baltic glacier4 ,we need not be surprised that interglacial beds should be well developed underneath the bottom-moraine of that great glacier1 while they have not yet been recognised below the corresponding morainic accumulations of our ,highlands and ,uplands4 ,the conditions in the low-grounds of the ,baltic coast-lands favoured their preservation1 for the ice in those regions formed a broad mer de glace1 under the peripheral areas of which sub-glacial erosion was necessarily at a minimum and the accumulation at a maximum4 ,in our ,scottish mountain-valleys1 however1 the very opposite was the case4 ,the conditions obtaining there were not at all comparable to those that characterised the low-grounds of northern ,germany1 etc41 but were quite analogous to those of ,norway1 where1 as in our own mountain-regions1 interglacial beds are similarly wanting4 ,it is quite possible1 however1 that patches of such deposits may yet be met with underneath our younger moraines1 and they ought certainly to be looked for4 ,but whether they occur or not in our mountain-valleys1 it is certain that some of the older alluvia of our ,lowlands must belong to this horizon4 ,hitherto all alluvial beds that overlie our upper boulder-clay have been classified as post-glacial2 but since we have ascertained that our latest mer de glace was succeeded by genial interglacial conditions1 we may be sure that records of that temperate epoch will yet be recognised in such ,lowland tracts as were never reached by the glaciers of the succeeding cold epoch4 ,hence1 ,i believe that some of our so-called post-glacial alluvia will eventually be assigned to an interglacial horizon4 ,amongst these may be cited the old peat and freshwater beds that rest upon the upper boulder-clay at ,hailes ,quarry1 near ,edinburgh4 ,to the same horizon1 in all probability1 belong the clays1 with ,megaceros1 etc41 which occur so frequently underneath the peat-bogs of ,ireland4 ,an interesting account of these was given some years ago by ,mr4 ,williams1,,ch who1 as a collector of ,megaceros remains1 had the best opportunity of ascertaining the nature of the deposits in which these occur4 ,he gives a section of ,ballybetagh ,bog1 nine miles south-east of ,dublin1 which is as follows3-- #a4 ,boulder-clay4 #b4 ,fine tenacious clay1 without stones4 #c4 ,yellowish clay1 largely composed of vegetable matter4 #d4 ,brownish clay1 with remains of ,megaceros4 #e4 ,greyish clay4 #f4 ,peat4 ,,ch ,geol4 ,mag41 #ahha1 p4 #ced4 ,the beds overlying the boulder-clay are evidently of lacustrine origin4 ,the fine clay 7,no4 #b71 according to ,mr4 ,williams1 is simply reconstructed boulder-clay4 ,after the disappearance of the mer de glace the land would for some time be practically destitute of any vegetable covering1 and rain would thus be enabled to wash down the finer ingredients of the boulder-clay that covered the adjacent slopes1 and sweep them into the lake4 ,the clay formed in this way is described as attaining a considerable thickness near the centre of the old lake1 but it thins off towards the sides4 ,the succeeding bed 7,no4 #c7 consists so largely of vegetable dbris that it can hardly be called a clay4 ,mr4 ,williams describes it as a bed of pure vegetable remains that has been ages under pressure4 ,he notes that there is a total absence in this bed of any tenacious clay like that of the underlying stratum1 and infers1 therefore1 that the rainfall during the growth of the lacustrine vegetation was not so great as when the subjacent clay was being accumulated4 ,the remains of ,megaceros occur resting on the surface of the plant-bed and at various levels in the overlying brownish clay1 which attains a thickness of three to four feet4 ,the latter is a true lacustrine sediment1 containing a considerable proportion of vegetable matter1 interstratified with seams of clay and fine quartz-sand4 ,according to ,mr4 ,williams1 it was accumulated under genial or temperate climatic conditions like the present4 ,between this bed and the overlying greyish clay 7from #cj inches to #c feet thick7 there is always in all the bog deposits examined by ,mr4 ,williams a strongly-marked line of separation4 ,the greyish clay consists exclusively of mineral matter1 and has evidently been derived from the disintegration of the adjacent granitic hills4 ,mr4 ,williams is of opinion that this clay is of aqueo-glacial formation4 ,this he infers from its nature and texture1 and from its abundance4 ,why1 he asks1 did not this mineral matter come down in like quantity all the time of the deposit of the brown clay which underlies it8 ,simply because1 during the genial conditions which then existed1 the hills were everywhere covered with vegetation2 when the rain fell it soaked into the soil1 and the clay being bound together by the roots of the grasses1 was not washed down1 just as at the present time1 when there is hardly any degradation of these hills taking place4 ,he mentions1 further1 that in the grey clay he obtained the antler of a reindeer1 and that in one case the antlers of a ,megaceros1 found embedded in the upper surface of the brown clay1 immediately under the grey clay1 were scored like a striated boulder1 while the under side showed no markings4 ,mr4 ,williams also emphasises the fact that the antlers of ,megaceros frequently occur in a broken state--those near the surface of the brown clay being most broken1 while those at greater depths are much less so4 ,he shows that this could not be the result of tumultuous river-action--the elevation of the valley precluding the possibility of its receiving a river capable of producing such effects4 ,moreover1 the remains show no trace of having been water-worn1 the edges of the teeth of the great deer being as sharp as if the animal had died but yesterday4 ,mr4 ,williams thinks that the broken state of the antlers is due to the pressure of great masses of ice on the surface of the clay in which they were embedded1 the wide expanse of the palms of the antlers exposing them to pressure and liability to breakage2 and even1 in many instances1 when there was #ab or #ad inches in circumference of solid bone almost as hard and sound as ivory1 it was snapped across4 ,it is remarkable that in this one small bog nearly one hundred heads of ,megaceros have been dug up4 ,mr4 ,williams' observations show us that the ,megaceros-beds are certainly older than the peat-bogs with their buried timber4 ,when he first informed me of the result of his researches 7#ahhj71 ,i did not believe the ,megaceros-beds could be older than the latest cold phase of the ,ice ,age4 ,i thought that they were later in date than our last general mer de glace1 and ,i think so still1 for they obviously rest upon its ground-moraine4 ,but since ,i now recognise that our upper boulder-clay is not the product of the last glacial epoch1 it seems to me highly probable that the ,megaceros-beds are of interglacial age--that1 in short1 they occupy the horizon of the interglacial deposits of north ,germany1 etc4 ,the appearances described by ,mr4 ,williams in connection with the grey clay seem strongly suggestive of ice-action4 ,ballybetagh ,bog occurs at an elevation of #hjj feet above the sea1 in the neighbourhood of the ,three ,rock ,mountain 7#adgi feet71 and during the epoch of great valley-glaciers the climatic conditions of that region must have been severe4 ,but without having visited the locality in question ,i should hesitate to say that the phenomena necessarily point to local glaciation4 ,probably frost1 lake-ice1 and thick accumulations of snow and nv might suffice to account for the various facts cited by ,mr4 ,williams4 ,i have called special attention to these ,irish lacustrine beds1 because it is highly probable that the post-glacial age of similar alluvia occurring in many other places in these islands has hitherto been assumed and not proved4 ,now that we know1 however1 that a long interglacial stage succeeded the disappearance of the last general mer de glace1 we may feel sure that the older alluvia of our ,lowland districts cannot belong exclusively to post-glacial times4 ,the local ice-sheets and great glaciers of our third glacial epoch were confined to our mountain-regions2 and in the ,lowlands1 therefore1 which were not invaded1 we ought to have the lacustrine and fluviatile accumulations of the preceding interglacial stage4 ,a fresh interest now attaches to our older alluvia1 which must be carefully re-examined in the new light thus thrown upon them4 ,turning next to the ,alpine ,lands of central ,europe1 we find that geologists there have for many years recognised two glacial epochs4 ,hence1 like their confrres in northern ,europe1 they speak of first and second glacial epochs4,,ci ,within recent years1 however1 ,professor ,penck has shown that the ,alps have experienced at least three separate periods of glaciation4 ,he describes three distinct ground-moraines1 with associated river-terraces and interglacial deposits in the valleys of the ,bavarian ,alps1 and his observations have been confirmed by ,professor ,brckner and ,dr4 ,bhm4,,cj ,the same glacialists1 ,i understand1 have nearly completed an elaborate survey of the eastern ,alps1 of which they intend shortly to publish an extended account4 ,the results obtained by them are very interesting1 and fully bear out the conclusions already arrived at from their exploration of the ,bavarian ,alps4,,ck ,a similar succession of glacial epochs has quite recently been determined by ,dr4 ,du ,pasquier in north ,switzerland4,,cl ,nor is this kind of evidence confined to the north side of the ,alps4 ,on the shores of ,lake ,garda1 between ,sal and ,brescia1 three ground-moraines1 separated by interglacial accumulations1 are seen in section4 ,the interglacial deposits consist chiefly of loams--the result of sub-arial weathering--and attain a considerable thickness4 ,from this ,penck infers that the time which has elapsed since the latest glaciation is less than that required for the accumulation of either of the two interglacial series--a conclusion which1 he says1 is borne out by similar observations in other parts of the ,alpine region4,,cm ,,ci ,morlot3 ,bulletin de la ,soc4 ,vaud4 d4 ,sciences nat41 #ahed1 #aheh1 #ahfj4 ,deicke3 ,bericht4 d4 ,st4 ,gall4 naturf4 ges41 #aheh4 ,heer3 ,urwelt der ,schweiz4 ,mhlberg3 ,festschrift d4 aarg4 naturf4 ,ges4 z4 ,feier ihrer #ejj ,sitz41 #ahfi4 ,rothpletz3 ,denkschr4 d4 schweizer4 ,ges4 f4 d4 ges4 ,naturwissensch41 ,bd4 xxviii41 #ahha4 ,wettstein3 ,geologie v4 ,zurich u4 ,umgebung1 #ahhe4 ,baltzer3 ,mitteil4 d4 naturf4 ,ges4 ,bern1 #ahhg4 ,renevier3 ,bull4 de la ,soc4 helvt4 d4 ,sciences nat41 #ahhg4 ,,cj ,penck3 ,die ,vergletscherung d4 deutschen ,alpen1 #ahhb4 ,brckner3 ,die ,vergletscherung des ,salzachgebietes1 ,geogr4 ,abhandl4 ,wien1 ,bd4 i4 ,bhm3 ,jahrb4 der k4 k4 geol4 ,reichsanst41 #ahhd1 #ahhe4 ,see also ,o4 ,fraas1 ,neues ,jahrb4 f4 ,min4 ,geol4 u4 ,palont41 #ahhj1 ,bd4 i4 p4 #bah2 ,e4 ,fugger and ,c4 ,kastner1 ,verhandl4 d4 k4 k4 geol4 ,reichsanst41 #ahhc1 p4 #acf4 ,,ck ,mittheil4 des deutsch4 u4 oesterreich4 ,alpenvereins1 #ahij1 ,no4 #bj u4 #bc4 ,,cl ,beitrge z4 geolog4 ,karte der ,schweiz1 #ca ,lief41 #ahia2 ,archiv4 d4 ,sciences phys4 et nat41 #ahia1 p4 #dd4 ,,cm ,die grosse ,eiszeit1 ,himmel u4 ,erde4 ,although the occurrence of such sub-erial products intercalated between separate morainic accumulations is evidence of climatic changes1 still it does not tell us how far the glaciers retreated during an interglacial stage4 ,fortunately1 however1 lignite beds and other deposits charged with plant remains are met with occupying a similar position1 and from these we gather that during interglacial times the glaciers sometimes retired to the very heads of the mountain-valleys1 and must have been smaller than their present representatives4 ,of such interglacial plant-beds1 which have been met with in some twenty localities1 the most interesting1 perhaps1 is the breccia of ,htting1 in the neighbourhood of ,innsbruck4,,cn ,this breccia rests upon old morainic accumulations1 and is again overlaid by the later moraines of the great ,inn glacier4 ,from the fact that the breccia yielded a number of supposed extinct species of plants1 palontologists were inclined to assign it to the ,pliocene4 ,professor ,penck1 however1 prefers to include it in the ,pleistocene system1 along with all the glacial and interglacial deposits of the ,alpine ,lands4 ,according to ,dr4 von ,wettstein1 the flora in question is not ,alpine but ,pontic4 ,at the time of the formation of the breccia the large-leaved ,rhododendron ponticum flourished in the ,inn ,valley at a height of #abjj metres above the sea2 the whole character of the flora1 in short1 indicates a warmer climate than is now experienced in the neighbourhood of ,innsbruck4 ,it is obvious1 therefore1 that in interglacial times the glaciers must have shrunk back1 as ,professor ,penck remarks1 to the highest ridges of the mountains4 ,,cn ,penck3 ,die ,vergletscherung der deutschen ,alpen1 p4 #bbh4 ,verhandl4 d4 k4 k4 geol4 ,reichsanst41 #ahhg1 ,no4 #e2 ,himmel und ,erde1 #ahia4 ,bhm3 ,jahrb4 d4 k4 k4 geol4 ,reichsanst41 #ahhd1 p4 #adg4 ,blaas3 ,ferdinandeums ,zeitschr41 iv4 ,folge2 ,bericht4 d4 naturwissensch4 ,vereins1 #ahhi1 p4 #ig4 ,we may now glance at the glacial succession which has been established for central ,france4 ,more than twenty years ago ,dr4 ,julien brought forward evidence to show that the region of the ,puy de ,dme had witnessed two glacial epochs4,,co ,during the first of these epochs a large glacier flowed from ,mont ,dore4 ,after its retreat a prolonged interglacial epoch followed1 during which the old morainic deposits and the rocks they rest upon were much eroded4 ,in the valleys and hollows thus excavated freshwater beds occur which have yielded relics of an abundant flora1 together with the remains of ,elephas meridionalis1 ,rhinoceros leptorhinus1 etc4 ,after the deposition of these freshwater alluvia1 glaciers again descended the valleys and covered the interglacial beds with their moraines4 ,similar results have been obtained by ,m4 ,rames from a study of the glacial phenomenon of ,cantal1 which he shows belong to two separate epochs4,,cp ,the interval between the formation of the two series of glacial accumulations must have been prolonged1 for the valleys during that interval were in some places eroded to a depth of #ijj feet4 ,m4 ,rames further recognises that the second glacial epoch was distinguished by two advances of valley-glaciers1 separated by a marked episode of fusion4 ,dr4 ,julien has likewise noted the evidence for two episodes of fusion during the first extension of the glaciers of the ,puy de ,dme4 ,,co ,des ,phnomnes glaciaires dans le ,plateau central de la ,france1 c42 ,paris1 #ahfi4 ,,cp ,bull4 ,soc4 gol4 de ,france1 #ahhd2 see also ,m4 ,boule1 ,bull4 de la ,soc4 philomath4 de ,paris1 #h;e sr4 i41 p4 #hg4 ,two glacial epochs have similarly been admitted for the ,pyrenees2,,cq but ,dr4 ,penck some years ago brought forward evidence to show that these mountains1 like the ,alps1 have experienced three separate and distinct periods of glaciation4,,cr ,,cq ,garrigou3 ,bull4 ,soc4 gol4 de ,france1 #b;e sr4 xxiv41 p4 #egg4 ,jeanbernat3 ,bull4 de ,soc4 d',hist4 nat4 de ,toulouse1 iv41 pp4 #aad1 #ach4 ,piette3 ,bull4 ,soc4 gol4 de ,france1 #c;e sr4 ii41 pp4 #ejc1 #ejg4 ,,cr ,mitteilungen d4 ,vereins f4 ,erdkunde zu ,leipzig1 #ahhc4 ,we may now return to ,scotland1 and consider briefly the changes that followed upon the disappearance of the local ice-sheets and large valley-glaciers of our mountain-regions4 ,the evidence is fortunately clear and complete4 ,in the valley of the ,tay1 for example1 at and below ,perth1 we encounter the following succession of deposits3-- #f4 ,recent alluvia4 #e4 ,carse-deposits1 #de feet above sea-level4 #d4 ,peat and forest bed4 #c4 ,old alluvia4 #b4 ,clays1 etc41 of #ajj-;feet beach4 #a4 ,boulder-clay4 ,the old alluvia 7#c7 are obviously of fluviatile origin1 and show us that after the deposition of the clays1 etc41 of the #ajj-;feet beach the sea retreated1 and allowed the ,tay and its tributaries to plough their way down through the marine and estuarine deposits of the third glacial epoch4 ,these deposits would appear to have extended at first as a broad and approximately level plain over all the lower reaches of the valleys4 ,through this plain the ,tay and the ,earn cut their way to a depth of more than #ajj feet1 and gradually removed all the material over a course which can hardly be less than #b miles in breadth below the ,bridge of ,earn1 and considerably exceeds that in the ,carse of ,gowrie4 ,no organic remains occur in the old alluvia1 but the deposits consist principally of gravel and sand1 and show not a trace of ice-action4 ,immediately overlying them comes the well-known peat-bed 7#d74 ,this is a mass of vegetable matter1 varying in thickness from a few inches up to #c or #d feet4 ,in some places it seems to be made up chiefly of reed-like plants and sedges and occasional mosses1 commingled with which are abundant fragments of birch1 alder1 willow1 hazel1 and pine4 ,in other places it contains trunks and stools of oak and hazel1 with hazel-nuts--the trees being rooted in the subjacent deposits4 ,it is generally highly compressed and readily splits into lamin1 upon the surface of which many small reeds1 and now and again wing-cases of beetles1 may be detected4 ,a large proportion of the woody dbris--twigs1 branches1 and trunks--appears to have been drifted4 ,a dug-out canoe of pine was found1 along with trunks of the same tree1 in the peat at ,perth4 ,the ,carse-deposits 7#e71 consisting principally of clay and silt1 rest upon the peat-bed4 ,the occurrence in these deposits of ,scrobicularia piperata and oyster-shells leaves us in no doubt as to their marine origin4 ,they vary in thickness from #aj up to fully #dj feet4,,cs ,,cs ,for a particular account of the ,tay-valley ,succession1 see ,prehistoric ,europe1 p4 #che4 ,a similar succession of deposits is met with in the valley of the ,forth1,,ct and we cannot doubt that these tell precisely the same tale4 ,i have elsewhere,,cu adduced evidence to show that the peat-bed1 with drifted vegetable dbris1 which underlies the ,carse accumulations of the ,forth and ,tay is on the same horizon as the lower buried forest of our oldest peat-bogs1 and the similar bogs that occur in ,norway1 ,sweden1 ,denmark1 ,schleswig-,holstein1 ,holland1 etc4 ,underneath the lower buried forest of those regions occur now and again freshwater clays1 charged with the relics of an arctic-alpine flora2 and quite recently similar plant remains have been detected in old alluvia at ,corstorphine1 near ,edinburgh4 ,when the beds below our older peat-bogs are more carefully examined1 traces of that old arctic flora will doubtless be met with in many other parts of these islands4 ,it was this flora that clothed north-western ,europe during the decay of the last district ice-sheets of ,britain and the disappearance of the great ,baltic glacier4 ,,ct ,proc4 ,roy4 ,soc4 ,edin4 #ahhc-hd1 p4 #gde2 ,mem4 ,geol4 ,survey1 ,scotland1 ,explanation of ,sheet #ca4 ,,cu ,prehistoric ,europe1 chaps4 xvi41 xvii4 ,the dissolution of the large valley-glaciers of this country was accompanied by a general retreat of the sea--all the evidence leading to the conviction that our islands eventually became united to the ,continent4 ,the climatic conditions1 as evidenced by the flora of the lower buried forest1 were decidedly temperate--probably even more genial than they are now1 for the forests attained at that time a much greater horizontal and vertical range4 ,this epoch of mild climate and continental connection was eventually succeeded by one of submergence1 accompanied by colder conditions4 ,britain was again insulated--the sea-level in ,scotland reaching a height of #de-ej feet above present high-water4 ,to this epoch pertain the ,carse-clays of the ,forth and ,tay4 ,a few erratics occur in these deposits1 probably betokening the action of floating ice1 but the beds more closely resemble the modern alluvial silts of our estuaries than the tenacious clays of the #ajj-;feet terrace4 ,when the ,carse-clays are followed inland1 however1 they pass into coarse river-gravel and shingle1 forming a well-marked high-level alluvial terrace of much the same character as the yet higher-level fluviatile terrace which is associated in like manner with the marine deposits of the #ajj-;feet beach4 ,of contemporaneous age with the ,carse-clays1 with which indeed they are continuous1 are the raised beaches at #de-ej feet4 ,these beaches occur at many places along the ,scottish coasts1 but they are seldom seen at the heads of our sea-lochs4 ,when the sea stood at this level1 glaciers of considerable size occupied many of our mountain-valleys4 ,in the west they came down in places to the sea-coast1 and dropped their terminal moraines upon the beach-deposits accumulating there4 ,thus1 in ,arran,,cv and in ,sutherland1,,cw these moraines are seen reposing on the raised beaches of that epoch4 ,and ,i think it is probable that the absence of such beaches at the heads of many of the sea-lochs of the ,highland area is to be explained by the presence there of large glaciers1 which prevented their formation4 ,,cv ,british ,association ,reports 7#ahed73 ,trans4 of ,sections1 p4 #gh4 ,,cw ,l4 ,hinxman3 ,paper read before ,edin4 ,geol4 ,soc41 ,april #ahib4 ,thus1 there is clear evidence to show that after the genial epoch represented by the lower buried forest1 a recrudescence of glacial conditions supervened in ,scotland4 ,many of the small moraines that occur at the heads of our mountain-valleys1 both in the ,highlands and ,southern ,uplands1 belong in all probability to this epoch4 ,they are characterised by their very fresh and well-preserved appearance4,,cx ,it is not at all likely that these later climatic changes could have been confined to ,scotland4 ,other regions must have been similarly affected4 ,but the evidence will probably be harder to read than it is with us4 ,had it not been for the existence of our lower buried forest1 with the overlying ,carse-deposits1 we could hardly have been able to distinguish so readily between the moraines of our third glacial epoch and those of the later epoch to which ,i now refer4 ,the latter1 we might have supposed1 simply marked a stage in the final retreat of the antecedent great valley-glaciers4 ,,cx ,prehistoric ,europe 7chaps4 xvi41 xvii47 gives a fuller statement of the evidence4 ,i have elsewhere traced the history of the succeeding stages of the ,pleistocene period1 and adduced evidence of similar1 but less strongly-marked1 climatic changes having followed upon those just referred to1 and my conclusions have been supported by the independent researches of ,professor ,blytt in ,norway4 ,but these later changes need not be considered here4 ,it is sufficient for my general purpose to confine attention to the well-proved conclusion that after the decay of the last district ice-sheets and great glaciers of our third glacial epoch genial conditions obtained1 and that these were followed by cold and humid conditions1 during the prevalence of which glaciers reappeared in many mountain-valleys4 ,we have thus1 as it seems to me1 clear evidence in ,europe of four glacial epochs1 separated the one from the other by protracted intervals of genial temperate conditions4 ,so far1 one's conclusions are based on data which cannot be gainsaid1 but there are certain considerations which lead to the suspicion that the whole of the complex tale has not yet been unravelled1 and that the climatic changes were even more numerous than those that ,i have indicated4 ,let it be noted that glacial conditions attained their maximum during the earliest of our recognised glacial epochs4 ,with each recurring cold period the ice-sheets and glaciers successively diminished in importance4 ,that is one of the outstanding facts with which we have to deal4 ,whatever may have been the cause or causes of glacial and interglacial conditions1 it is obvious that those causes1 after attaining a maximum influence1 gradually became less effective in their operation4 ,such having been the case1 one can hardly help suspecting that our epoch of greatest glaciation may have been preceded by an alternation of cold and genial stages analogous to those that followed it4 ,if three cold epochs of progressively diminished severity succeeded the epoch of maximum glaciation1 the latter may have been preceded by one or more epochs of progressively increased severity4 ,that something of the kind may have taken place is suggested by the occurrence of the old moraine of that great ,baltic glacier that preceded the appearance of the most extensive mer de glace of northern ,europe4 ,the old moraine in question1 it will be remembered1 underlies the lower diluvium4 ,unfortunately1 the very conditions that attended the glaciation of ,europe render it improbable that any conspicuous traces of glacial epochs that may have occurred prior to the period of maximum glaciation could have been preserved within the regions covered by the great inland-ice4 ,their absence1 therefore1 cannot be held as proving that the lower boulder-clays of ,britain and northern ,europe are the representatives of the earliest glacial epoch4 ,the lowest boulder-clay1 ,i believe1 has yet to be discovered4 ,it is in the ,alpine ,lands that we encounter the most striking evidence of glacial conditions anterior to the epoch of maximum glaciation4 ,the famous breccia of ,htting has already been referred to as of interglacial age4 ,from the character of its flora1 ,ettinghausen considered this accumulation to be of ,tertiary age4 ,the assemblage of plants is certainly not comparable to the well-known interglacial flora of ,drnten4 ,according to the researches of ,dr4 ,r4 von ,wettstein1,,cy the ,htting flora has most affinity with that of the ,pontic ,mountains1 the ,caucasus1 and southern ,spain1 and implies a considerably warmer climate than is now experienced in the ,inn ,valley4 ,this remarkable deposit1 as ,dr4 ,penck pointed out some ten years ago1 is clearly of interglacial age4 ,his conclusions were at once challenged1 on the ground that the flora had a ,tertiary and not a ,pleistocene facies2 consequently1 it was urged that1 as all glacial deposits were of ,pleistocene age1 this particular breccia could not be interglacial4 ,but in this1 as in similar cases1 the palontologist's contention has not been sustained by the stratigraphical evidence1 and ,dr4 ,penck's observations have been confirmed by several highly-competent geologists1 as by ,,mm4 ,bhm and ,du ,pasquier4 ,the breccia is seen in several well-exposed sections resting upon the moraine of a local glacier which formerly descended the northern flanks of the ,inn ,valley1 opposite ,innsbruck1 where the mountain-slopes under existing conditions are free from snow and ice4 ,nor is this all1 for certain erratics appear in the breccia1 which could only have been derived from pre-existing glacial accumulations1 and their occurrence in this accumulation at a height of #aaej metres shows that before the advent of the ,htting flora the whole ,inn ,valley must have been filled with ice4 ,the plant-bearing beds are in their turn covered by the ground-moraine of a later and more extensive glaciation4 ,to bring about the glacial conditions that obtained before the formation of the breccia1 the snow-line1 according to ,penck1 must have been at least #ajjj metres lower than now2 while1 to induce the succeeding glaciation1 the depression of the snow-line could not have been less than #abjj metres4 ,these observations have been extended to many other parts of the ,alps1 and the conclusion arrived at by ,professor ,penck and his colleagues1 ,professor ,brckner and ,dr4 ,bhm1 is briefly this--that the maximum glaciation of those regions did not fall in the first but in the second ,alpine glacial epoch4 ,,cy ,sitzungsberichte d4 ,kais4 ,acad4 d4 ,wissensch4 in ,wien1 mathem4-naturw4 ,classe1 ,bd4 xcvii4 ,abth4 i41 #ahhh4 ,the glacial phenomena of northern and central ,europe are so similar--the climatic oscillations which appear to have taken place had so much in common1 and were on so grand a scale--that we cannot doubt they were synchronous4 ,we may feel sure1 therefore1 that the epoch of maximum glaciation in the ,alps was contemporaneous with the similar epoch in the north4 ,and if this be so1 then in the oldest ground-moraines of the ,alps we have the records of an earlier glacial epoch than that which is represented by the lower boulder-clays of ,britain and the corresponding latitudes of the ,continent4 ,in other words1 the ,htting flora belongs to an older stage of the ,glacial period than any of the acknowledged interglacial accumulations of northern ,europe4 ,the character of the plants is in keeping with this conclusion4 ,the flora has evidently much less connection with the present flora of the ,alps than the interglacial floras of ,britain and northern ,europe have with those that now occupy their place4 ,the ,htting flora1 moreover1 implies a considerably warmer climate than now obtains in the ,alpine regions1 while that of our interglacial beds indicates a temperate insular climate1 apparently much like the present4 ,the high probability that oscillations of climate preceded the advent of the so-called first mer de glace of northern ,europe must lead to a re-examination of our ,pliocene deposits1 with a view to see whether these yield conclusive evidence against such climatic changes having obtained immediately before ,pleistocene times4 ,by drawing the line of separation between the ,pleistocene and the ,pliocene at the base of our glacial series1 the two systems in ,britain are strongly marked off the one from the other4 ,there is1 in short1 a distinct break in the succession4 ,from the ,cromer ,forest-bed1 with its abundant mammalian fauna and temperate flora1 we pass at once to the overlying arctic freshwater bed and the superjacent boulder-clay that marks the epoch of maximum glaciation4,,cz ,amongst the mammalian fauna of the ,forest-bed are elephants 7,elephas meridionalis1 ,e4 antiquus71 hippopotamus1 rhinoceros1 7,r4 etruscus71 horses1 bison1 boar1 and many kinds of deer1 together with such carnivores as bears1 ,machrodus1 spotted hyna1 etc4 ,the freshwater and estuarine beds which contain this extensive fauna rest immediately upon marine deposits 7,weybourn ,crag71 the organic remains of which have a decidedly arctic facies4 ,here1 then1 we have what at first sight would seem to be another break in the succession4 ,the ,forest-bed1 one might suppose1 indicated an interglacial epoch1 separating two cold epochs4 ,but ,mr4 ,clement ,reid1 who has worked out the geology of the ,pliocene with admirable skill1,,da has another explanation of the phenomena4 ,it has long been known that the organic remains of the marine ,pliocene of ,britain denote a progressive lowering of temperature4 ,the lower member of the system is crowded with southern forms1 which indicate warm-temperate conditions4 ,but when we leave the ,older and pass upwards into the ,newer ,pliocene those southern forms progressively disappear1 while at the same time immigrants from the north increase in numbers1 until eventually1 in the beds immediately underlying the ,forest-bed1 the fauna presents a thoroughly arctic facies4 ,during the formation of the ,older ,pliocene with its southern fauna our area was considerably submerged1 so that the ,german ,ocean had then a much wider communication with the seas of lower latitudes4 ,at the beginning of ,newer ,pliocene times1 however1 the land emerged to some extent1 and all connection between the ,german ,ocean and more southern seas was cut off4 ,when at last the ,forest-bed series began to be accumulated1 the southern half of the ,north ,sea basin had become dry land1 and was traversed by the ,rhine in its course towards the north1 the ,forest-bed representing the alluvial and estuarine deposits of that river4 ,,cz ,in some places1 however1 certain marine deposits 7,leda myalis bed7 immediately overlie the ,forest-bed4 ,,da ,mem4 of ,geol4 ,survey1 ,pliocene ,deposits of ,britain4 ,see postea1 footnote1 p4 #cag4 ,mr4 ,reid1 in referring to the progressive change indicated by the ,pliocene marine fauna1 is inclined to agree with ,professor ,prestwich that this was not altogether the result of a general climatic change4 ,he thinks the successive dying out of southern forms and the continuous arrival of boreal species was principally due to the ,north ,sea remaining fully open to the north1 while all connection with southern seas was cut off4 ,under such conditions1 he says1 there was a constant supply of arctic species brought by every tide or storm1 while at the same time the southern forms had to hold their own without any aid from without2 and if one was exterminated it could not be replaced4 ,doubtless the isolation of the ,north ,sea must have hastened the extermination of the southern forms1 but the change could not have been wholly due to such local causes4 ,similar1 if less strongly-marked1 changes characterise the marine ,pliocene of the ,mediterranean area1 while the freshwater alluvia of ,france1 etc41 furnish evidence in the same direction4 ,the ,cromer ,forest-bed overlies the ,weybourn ,crag1 the marine fauna of which has a distinctly ,arctic facies4 ,the two cannot1 therefore1 be exactly contemporaneous3 the marine equivalents of the ,forest-bed are not represented4 ,but ,mr4 ,reid points out that several arctic marine shells of the ,weybourn ,crag occur also in the ,forest-bed1 while certain southern freshwater and terrestrial shells common in the latter are met with likewise in the former1 commingled with the prevailing arctic marine species4 ,he thinks1 therefore1 that we may fairly conclude that the two faunas occupied adjacent areas4 ,one can hardly accept this conclusion without reserve4 ,it is difficult to believe that a temperate flora and mammalian fauna like those of the ,forest-bed clothed and peopled eastern ,england when the adjacent sea was occupied by arctic molluscs1 etc4 ,surely the occurrence of a few forms1 which are common to the ,forest-bed and the underlying ,crag1 does not necessarily prove that the two faunas occupied adjacent districts4 ,mr4 ,reid1 indeed1 admits that some of the marine shells in the ,forest-bed series may have been derived from the underlying ,crag4 ,were the marine equivalents of the ,forest-bed forthcoming we might well expect them to contain many ,crag forms1 but the facies of the fauna would most probably resemble that of the existing ,north ,sea fauna4 ,again1 the appearance in the ,weybourn ,crag of a few southern shells common to the ,forest-bed does not seem to prove more than that such shells were contemporaneous somewhere with an arctic marine fauna4 ,but it is quite possible that they might have been carried for a long distance from the south2 and1 even if they actually existed in the near neighbourhood of an arctic marine fauna1 we may easily attach too much importance to their evidence4,,db ,i cannot think1 therefore1 that ,mr4 ,reid's conclusion is entirely satisfactory4 ,after all1 the ,cromer ,forest-bed rests upon the ,weybourn ,crag1 and the evidence as it stands is explicable in another way4 ,it is quite possible1 for example1 that the ,forest-bed really indicates an epoch of genial or temperate conditions1 preceded1 as it certainly was eventually succeeded1 by colder conditions4 ,,db ,the inference that the ,forest-bed occupies an interglacial position is strengthened by the evidence of certain marine deposits which immediately overlie it4 ,these 7known collectively as the ,leda myalis bed7 occur in irregular patches1 which1 from the character of their organic remains1 cannot all be precisely of the same age4 ,in one place1 for example1 they are abundantly charged with oysters1 having valves united1 and with these are associated other species of molluscs that still live in ,british seas4 ,at another place no oysters occur1 but the beds yield two arctic shells1 ,leda myalis and ,astarte borealis1 and some other forms which have no special significance4 ,professor ,otto ,torell pointed out to ,mr4 ,reid that these separate deposits could not be of the same age1 for the oyster is sensitive to cold and does not inhabit the seas where ,leda myalis and ,astarte borealis flourish4 ,from a consideration of this and other evidence ,mr4 ,reid concludes that it is possible that the deposits indicate a period of considerable length1 during which the depth of water varied and the climate changed4 ,two additional facts may be noted3 ,leda myalis does not occur in any of the underlying ,pliocene beds1 while the oyster is not found in the ,weybourn and ,chillesford ,crag1 though common lower down in the ,pliocene series4 ,these facts seem to me to have a strong bearing on the climatic conditions of the ,forest-bed epoch4 ,they show us that the oyster flourished in the ,north ,sea before the period of the ,weybourn ,crag--that it did not live side by side with the arctic forms of that period--and that it reappeared in our seas when favourable conditions returned4 ,when the climate again became cold an arctic fauna 7including a new-comer1 ,leda myalis7 once more occupied the ,north ,sea4 ,if it be objected that this would include as interglacial what has hitherto been regarded by most as a ,pliocene mammalian fauna1,,dc ,i would reply that the interglacial age of that fauna has already been proved in central ,france4 ,the interglacial beds of ,auvergne1 with ,elephas meridionalis1 rest upon and are covered by moraines1,,dd and with these have been correlated the deposits of ,saint-,prest4 ,again1 in northern ,italy the lignites of ,leffe and ,pianico1 which1 as ,i showed a number of years ago1,,de occupy an interglacial position1 have likewise yielded ,elephas meridionalis and other associated mammalian forms4 ,,dc ,elephas meridionalis is usually regarded as a type-form of the ,newer ,pliocene1 but long ago ,dr4 ,fuchs pointed out that in ,hungary this species is of quaternary age3 ,verhandl4 d4 k4 k4 geolog4 ,reichsanstalt1 #ahgi1 pp4 #di1 #bgj4 ,it matters little whether we relegate to the top of the ,pliocene or to the base of the ,pleistocene the beds in which this species occurs4 ,that it is met with upon an interglacial horizon is certain2 and if we are to make the ,pleistocene co-extensive with the glacial and interglacial series we shall be compelled to include in that system some portion of the ,newer ,pliocene4 ,,dd ,julien3 ,des ,phnomnes glaciaires dans le ,plateau central1 etc41 #ahfi4 ,boule3 ,revue d',anthropologie1 #ahgi4 ,,de ,prehistoric ,europe1 p4 #cjf4 ,professor ,penck writes me that he and the ,swiss glacialist1 ,dr4 ,du ,pasquier1 have recently examined these deposits1 and are able to confirm my conclusion as to their interglacial position4 ,there can be no doubt1 then--indeed it is generally admitted--that the cold conditions that culminated in our ,glacial period began to manifest themselves in ,pliocene times4 ,moreover1 as it can be shown that ,elephas meridionalis and its congeners lived in central ,europe after an epoch of extensive glaciation1 it is highly probable that the ,forest-bed1 which contains the relics of the same mammalian fauna1 is equivalent in age to the early interglacial beds of ,france and the ,alpine ,lands4 ,we seem1 therefore1 justified in concluding that the alternation of genial and cold climates that succeeded the disappearance of the greatest of our ice-sheets was preceded by analogous climatic changes in late ,pliocene times4 ,i shall now briefly summarise what seems to have been the glacial succession in ,europe3-- #a4 ,weybourn ,crag2 ground-moraine of great ,baltic glacier underlying lower diluvium2 the oldest recognised ground-moraines of central ,europe4 ,glacial ,these accumulations represent the earliest glacial epoch of which any trace has been discovered4 ,it would appear to have been one of considerable severity1 but not so severe as the cold period that followed4 #b4 ,forest-bed of ,cromer2 ,htting breccia2 lignites of ,leffe and ,pianico2 interglacial beds of ,interglacial central ,france4 ,earliest recognised interglacial epoch2 climate very genial4 #c4 ,lower boulder-clays of ,britain2 lower diluvium of ,scandinavia and north ,germany 7in part72 lower glacial deposits of south ,germany and central ,russia2 ground-moraines and high-level gravel-terraces of ,alpine ,lands1 etc42 ,glacial terminal moraines of outer zone4 ,the epoch of maximum glaciation2 the ,british and ,scandinavian ice-sheets confluent2 the ,alpine glaciers attain their greatest development4 #d4 ,interglacial freshwater alluvia1 peat1 lignite1 etc41 with mammalian remains 7,britain1 ,germany1 etc41 central ,russia1 ,alpine ,lands1 etc472 and marine deposits 7,britain1 ,baltic coast-lands74 ,interglacial ,continental condition of ,british area2 climate at first cold1 but eventually temperate4 ,submergence ensued towards close of the period1 with conditions passing from temperate to arctic4 #e4 ,upper boulder-clay of ,britain2 lower diluvium of ,scandinavia1 ,germany1 etc41 in part2 upper glacial series in central ,russia2 ground-moraines and gravel-terraces in ,alpine ,lands4 ,scandinavian and ,british ice-sheets again ,glacial confluent1 but mer de glace does not extend quite so far as that of the preceding cold epoch4 ,conditions1 however1 much more severe than those of the next succeeding cold epoch4 ,alpine glaciers deposit the moraines of the inner zone4 #f4 ,freshwater alluvia1 lignite1 peat1 etc4 7some of the so-called post-glacial alluvia of ,britain2 interglacial beds of north ,germany1 etc42 ,alpine ,lands7872 marine deposits of ,britain and ,baltic coast-lands74 ,interglacial ,britain probably again continental2 climate at first temperate and somewhat insular2 submergence ensues with cold climatic conditions--,scotland depressed for #ajj feet2 ,baltic provinces of ,germany1 etc41 invaded by the waters of the ,north ,sea4 #g4 ,ground-moraines1 terminal moraines1 etc41 of the mountain regions of ,britain2 upper diluvium of ,scandinavia1 ,finland1 north ,germany1 etc42 great terminal moraines of same regions2 terminal moraines in the large longitudinal valleys of the ,alps 7,penck74 ,major portion of ,scottish ,highlands covered ,glacial by ice-sheet2 local ice-sheets in ,southern ,uplands of ,scotland and mountain districts in other parts of ,britain2 great valley-glaciers sometimes coalesce on low-grounds2 icebergs calved at mouths of ,highland sea-lochs2 terminal moraines dropped upon marine deposits then forming 7#ajj-;feet beach74 ,scandinavia shrouded in a great ice-sheet1 which broke away in icebergs along the whole west coast of ,norway4 ,epoch of the last great ,baltic glacier4 #h4 ,freshwater alluvia 7with arctic plants72 lower buried forest and peat 7,britain and north-west ,europe generally74 ,carse-clays and raised beaches of #de to #ej-;feet level in ,scotland4 ,interglacial ,britain again continental2 climate at first cold1 subsequently becoming temperate3 great forests4 ,eventual insulation of ,britain2 climate humid1 and probably colder than now4 #i4 ,local moraines in mountain-valleys of ,britain1 here and there resting on #de to #ej-;feet beach2 so-called post-glacial moraines in the upper valleys of the ,alps4 ,probably final appearance of glaciers in our ,glacial islands4 ,some of these glaciers attained a considerable size1 reaching the sea and shedding icebergs4 ,it may be noted here that the decay of these latest glaciers was again followed by emergence of the land and a recrudescence of forest-growth 7upper buried forest74 ,a word of reference may now be made to that remarkable association of evidence of submergence1 with proofs of glacial conditions1 which has so frequently been noted by geologists4 ,take1 for example1 the succession in ,scotland1 and observe how each glacial epoch was preceded and apparently accompanied by partial submergence of the land3-- #a4 ,epoch of ,greatest ,mer de ,glace 7lower boulder-clay72 ,british and ,scandinavian ice-sheets coalescent4 ,followed by wide land-surface ,continental ,britain1 with genial climate4 ,submergence of land--to what extent is uncertain1 but apparently to #ejj feet or so4 #b4 ,epoch of ,lesser ,mer de ,glace 7upper boulder-clay72 ,british and ,scandinavian ice-sheets coalescent4 ,followed by wide land-surface ,continental ,britain1 with genial climate4 ,submergence of land for #ajj feet or thereabout4 #c4 ,epoch of ,local ,ice-sheets in ,mountain ,districts2 glaciers here and there coalesce on the low-grounds2 icebergs calved at mouths of ,highland sea-lochs 7moraines on #ajj-;feet beach74 ,followed by wide land-surface ,continental ,britain1 with genial climate4 ,submergence of land for #ej feet or thereabout4 #d4 ,epoch of ,small ,local ,glaciers1 here and there descending to sea 7moraines on #ej-;feet beach74 ,these oscillations of the sea-level did not terminate with the emergence of the land after the formation of the #ej-;feet beach4 ,there is evidence to show that subsequent to the retreat of the small local glaciers 7#d7 and the emergence of the land1 our shores extended seawards beyond their present limits1 but how far we cannot tell4 ,with this epoch of re-emergence the climate again became more genial1 our forests once more attaining a greater vertical and horizontal range4 ,submergence then followed 7the #be to #cj-;feet beach71 accompanied by colder and more humid conditions1 which1 while unfavourable to forest-growth1 tended greatly to increase the spread of peat-bogs4 ,we have no evidence1 however1 to show that small local glaciers again appeared4 ,finally the sea retired1 and the present conditions ensued4 ,it will be seen that the submergence which preceded and probably accompanied the advent of the lesser mer de glace 7#b7 was greater than that which heralded the appearance of the local ice-sheets 7#c71 as that in turn exceeded the depression that accompanied the latest local glaciers 7#d74 ,there would seem1 therefore1 to be some causal connection between cold climatic conditions and submergence4 ,this is shown by the fact that not only did depression immediately precede and accompany the appearance of ice-sheets and glaciers1 but the degree of submergence bore a remarkable relation to the extent of glaciation4 ,many speculations have been indulged in as to the cause of this curious connection between glaciation and depression2 these1 however1 ,i will not consider here4 ,none of the explanations hitherto advanced is satisfactory1 but the question is one well deserving the attention of physicists1 and its solution would be of great service to geology4 ,a still larger question which the history of these times suggests is the cause of climatic oscillations4 ,i have maintained that the well-known theory advanced by ,james ,croll is the only one that seems to throw any light upon the subject1 and the observations which have been made since ,i discussed the question at length1 some fifteen years ago1 have added strength to that conviction4 ,as ,sir ,robert ,ball has remarked1 the astronomical theory is really much stronger than ,croll made it out to be4 ,in his recently-published work1 ,the ,cause of an ,ice ,age1 ,sir ,robert says that the theory is so thoroughly well based that there is no longer any ground for doubting its truth4 ,we have even shown1 he continues1 that the astronomical conditions are so definite that astronomers are entitled to direct that vigorous search be instituted on this globe to discover the traces of those vast climatic changes through which astronomy declares that our earth must have passed4 ,in concluding this paper1 therefore1 ,i may shortly indicate how far the geological evidence seems to answer the requirements of the theory4 ,following ,croll1 we find that the last period of great eccentricity of the earth's orbit extended over #afj1jjj years--the eccentricity reaching its highest value in the earlier stages of the cycle4 ,it is obvious that during this long cycle the precession of the equinox must have completed seven revolutions4 ,we might therefore expect to meet with geological evidence of recurrent cold or glacial and genial or interglacial epochs2 and not only so1 but the records ought to show that the earlier glacial epoch or epochs were colder than those that followed4 ,now we find that the epoch of maximum glaciation supervened in early ,pleistocene times1 and that three separate and distinct glacial epochs of diminished severity followed4 ,of these three1 the first would appear to have been almost as severe as that which preceded it1 and it certainly much surpassed in severity the cold epochs of the later stages4 ,but the epoch of maximum glaciation1 or the first of the ,pleistocene series1 was not the earliest glacial epoch4 ,it seems to have been preceded by one of somewhat less severity than itself1 but which nevertheless1 as we gather from the observations of ,penck and his collaborators1 was about as important as that which came after the epoch of maximum glaciation4 ,hence it would appear that the correspondence of the geological evidence with the requirements of the astronomical theory is as close as we could expect it to be4 ,four glacial with intervening genial epochs appear to have fallen within ,pleistocene times2 while towards the close of the ,pliocene1 or at the beginning of the ,pleistocene period1 according as we choose to classify the deposits1 an earlier glacial epoch followed by genial interglacial conditions1 supervened4 ,in this outline of a large subject it has not been possible to do more than indicate very briefly the general nature of the evidence upon which the chief conclusions are based4 ,i hope1 however1 to have an opportunity ere long of dealing with the whole question in detail4 ,note4--,since the original publication of this ,essay1 renewed investigation and study have led me to conclude that the correlation of the ,british and ,continental glacial series is even more simple than ,i had supposed4 ,i believe the use of the terms ,lower and ,upper in connection with the ,diluvial deposits of the ,continent has hitherto blinded us to the obvious succession of the boulder-clays4 ,in ,britain we have1 as shown above1 a lower boulder-clay1 an upper boulder-clay1 and the still younger boulder-clays 7ground-moraines71 and terminal moraines of our district ice-sheets and valley-glaciers4 ,in the low-grounds of the ,continent the succession is precisely similar4 ,thus the lower boulder-clay that sweeps south into ,saxony represents the lower boulder-clay of ,britain4 ,in like manner1 the upper boulder-clay of western and middle ,germany1 of ,poland1 and western and north-western ,russia1 is the equivalent of our own upper boulder-clay4 ,lastly1 the so-called upper diluvium and the great terminal moraines of the ,baltic coast-lands are on the horizon of the younger boulder-clays and terminal moraines of the mountainous areas of the ,british ,islands4 ,the so-called lower diluvium of the ,baltic coast-lands thus represents not the lower but the upper diluvium of western and middle ,germany1 ,poland1 etc4 ,german geologists are of opinion that the upper boulder-clays of the ,baltic coast-lands and of the valley of the ,elbe are the ground-moraines of one and the same ice-sheet1 which1 on its retreat1 piled up the terminal moraines of the ,baltic ,ridge4 ,i believe the two boulder-clays in question are quite distinct1 and that the terminal moraines referred to mark the furthest advance of the last great ,baltic glacier4 ,the contemporaneity of the two boulder-clays has been taken for granted simply because they are each underlaid by a lower boulder-clay4 ,but1 as we have seen1 the upper boulder-clay of the ,baltic coast-lands is underlaid not by one only1 but by two1 and in some places even by three other boulder-clays--phenomena which never present themselves in the regions not invaded by the last great ,baltic glacier4 ,three or four boulder-clays occur in the coast-lands of the ,baltic because those regions were overflowed successively by three or four separate ice-sheets4 ,only two boulder-clays are met with south and east of the ,baltic ,ridge1 because the tracts lying south and south-east of that ridge were traversed by only two mers de glace--namely1 by that of the epoch of maximum glaciation and by the less extensive ice-sheet of the next succeeding cold period4 ,in the region between the ,elbe and the mountains of middle ,germany only one boulder-clay appears1 because that region has never been invaded by more than one ice-sheet4 ,the succession thus indicated may be tabulated as follows3-- #a4 ,epoch of ,earliest ,baltic ,glacier4 ,lowest boulder-clay of southern ,sweden2 lowest boulder-clay of ,baltic provinces of ,prussia2 horizon of the ,weybourn ,crag4 #b4 ,epoch of ,greatest ,mer de ,glace4 ,lower boulder-clays of middle and southern ,germany1 central ,russia1 ,british ,islands2 second boulder-clay of ,baltic provinces of ,prussia4 #c4 ,epoch of ,lesser ,mer de ,glace4 ,upper boulder-clay of western and middle ,germany1 ,poland1 and west central ,russia2 upper boulder-clay of ,britain2 third boulder-clay of ,baltic provinces of ,prussia4 #d4 ,epoch of ,last ,great ,baltic ,glacier4 ,upper boulder-clay and terminal moraines of ,baltic coast-lands2 district and valley-moraines of ,highlands and ,uplands of ,british ,islands4 #e4 ,epoch of ,small ,local ,glaciers4 ,valley-moraines in mountainous regions of ,britain1 etc4 ,the evidence on which these conclusions are based is set forth at some length in a forthcoming re-issue of my ,great ,ice ,age4--,nov4 #a1 #ahib4 ,illustration3 ,,plate ,,iv ,,sketch ,,map ,,of ,,northern ,,europe ,,showing ,,areas ,,covered ,,by ,,ice ,,during ,,the ,,epoch ,,of ,,maximum ,,glaciation1 ,,and ,,by ,,the ,,great ,,baltic ,,glacier ,,and ,,the ,,local ,,ice-,,sheets ,,of ,,britain ,,at ,a ,,later ,,date4 ,the ,edinburgh ,geographical ,institute ,j4 ,g4 ,bartholomew ,f4,r4,g4,s 99 99 99 99 99 ,explanation of ,plate ,,iv4 ,map of ,europe showing the areas occupied by ice during the ,epoch of ,maximum ,glaciation 7,second ,glacial ,epoch71 and the extent of glaciation in ,scandinavia1 ,finland1 ,baltic coast-lands1 etc41 and the ,british ,islands during the ,fourth ,glacial ,epoch4 ,for the limits of the greater glaciation on the ,continent1 ,habenicht1 ,penck1 ,nikitin1 and ,nathorst have been followed4 ,the ,great ,baltic ,glacier is chiefly after ,de ,geer4 ,,xi4 ,the ,geographical ,evolution of ,europe4,,df ,,df ,the ,scottish ,geographical ,magazine1 vol4 ii41 #ahhf4 ,it is one of the commonplaces of geology that the ,present is built up out of the ruins of the ,past4 ,every rock beneath our feet has its story of change to tell us4 ,mountains1 valleys1 and plains1 continents and islands1 have passed through vicissitudes innumerable1 and bear within them the evidence of a gradual development or evolution4 ,looking back through the vista of the past one sees the dry lands gradually separating from the ocean1 and gathering together into continental masses according to a definite plan4 ,it is this slow growth1 this august evolution1 carried on through countless ons1 which most impresses the student of physical geology4 ,the earth seems for the time as if endowed with life1 and like a plant or animal to pass through its successive stages of development until it culminates in the present beautiful world4 ,this conception is one of comparatively recent growth in the history of geological science4 ,hutton1 the father of physical geology1 had indeed clearly perceived that the dry lands of the globe were largely composed of the dbris of former land-surfaces--that there had been alternate elevations and depressions of the earth's crust1 causing now sea and now land to predominate over given areas4 ,but the facts known in this day could not possibly have suggested those modern ideas of geographical evolution1 which are the outcome of the multifarious observation and research of later years4 ,it is to ,professor ,dana1 the eminent ,american geologist1 that we are indebted for the first clear enunciation of the views which ,i am now about to illustrate4 ,according to him the great oceanic basins and continental ridges are of primeval antiquity--their origin is older than that of our oldest sedimentary formations4 ,it is not maintained that the present lands have always continued above the level of the sea4 ,on the contrary1 it can be proved that many oscillations of level have taken place within each continental area1 by which the extent and outline of the land have been modified again and again4 ,notwithstanding such changes1 however1 the great continental ridges would appear to have persisted from the earliest geological times as dominant elevations of the earth's crust4 ,some portions of these1 as ,dana remarks1 may have been submerged for thousands of feet1 but the continents have never changed places with the oceans4 ,i shall presently indicate the nature of the evidence by which it is sought to prove the vast age of our continental masses1 but before doing so it will be well to give an outline of the facts which go to show that the oceanic depressions of the globe are likewise of primeval antiquity4 ,the memorable voyage of the ,challenger has done much to increase our knowledge of the deep seas and the accumulations forming therein4 ,the researches of the scientific staff of the expedition1 and more particularly those of ,mr4 ,murray1 have indeed given a new impulse to the study of the larger questions of physical geology1 and have lent strong support to the doctrine of the permanence of the oceanic basins and continental ridges4 ,one of the most important facts brought before our attention by ,mr4 ,murray is the absence of any land-derived materials from the sediments now gathering in the deeper abysses of the ocean4 ,the coasts of continents and continental islands are strewn1 as every one knows1 with the wreck of the land--with gravel1 sand1 and mud1 derived from the demolition of our rocks and soils4 ,the coarser dbris accumulates upon beaches and in shallow littoral waters1 while the finer materials are swept further out to sea by tidal and other currents--the sediment being gradually sifted as it is borne outwards into deeper water1 until only the finest mud and silt remain to be swept forward4 ,as the floor of the ocean shelves down to greater depths the transporting power of currents gradually lessens1 and finally land-derived sediment ceases to appear4 ,such terrigenous materials may be said to extend from the littoral zone down to depths of #bjjj feet and more1 and to a distance of #fj to #cjj miles from shore4 ,they are confined1 therefore1 to a comparatively narrow belt round the margins of continents and islands4 ,and thus there are vast regions of the oceanic depressions over which no terrigenous or land-derived materials are accumulating4 ,instead of these we meet with a remarkable red clay and various kinds of ooze1 made up largely of the shells of foraminifera1 pelagic mollusca1 and radiolarians1 and the frustules of diatoms4 ,the red clay is the most widely distributed of abysmal deposits4 ,indeed1 it seems to form a certain proportion of all the deep-sea organic oozes1 and may be said1 therefore1 to exist everywhere in the abysmal regions of the oceanic basins4 ,it is extremely fine-grained1 and owes its deep brown or red colour to the presence of the oxides of manganese and iron4 ,scattered through the deposit occur particles of various minerals of volcanic origin1 together with lapilli and fragments of pumice1 i4e41 volcanic ejectamenta4 ,such materials may have been thrown out from terrestrial volcanoes and carried by the winds or floated by currents until they became water-logged and sank2 or they may to some extent be the relics of submarine eruptions4 ,whatever may have been their immediate source1 they are unquestionably of volcanic origin1 and are not associated with any truly terrigenous sediment4 ,the red clay is evidently the result of the chemical action of sea-water on volcanic products2 and many facts conspire to show that its formation is an extremely slow process4 ,thus1 remains of vertebrates1 consisting of the ear-bones of whales1 beaks of ziphius1 and teeth of sharks1 are often plentifully present1 and there is no reason to suppose1 as ,,mm4 ,murray and ,renard point out1 that the parts of the ocean where these remains occur are more frequented by whales and sharks than other regions where similar relics are rarely or never dredged up4 ,of these remains some have all the appearance of having lain upon the sea-bottom for a very long time1 for they belong to extinct species1 and are either partially coated or entirely surrounded with thick layers of manganese-iron4 ,in the same red clay occur small metallic spherules which are of cosmic origin--in other words1 meteoric dust4 ,the accumulation of all these substances in such relatively great abundance shows us that the oceanic basins have remained unchanged for a vast period of time1 and assures us that the formation of the abysmal red clay is extremely slow4 ,when we come to examine the rocks which enter into the framework of our continents1 we find that they may be roughly classed under these heads3-- #ast1 ,terrestrial and ,aqueous ,rocks4 #b;d1 ,igneous ,rocks4 #c;d1 ,crystalline ,schists4 ,by far the largest areas of land are composed of rocks belonging to the first class4 ,these consist chiefly of the more or less indurated sediments of ancient rivers1 lakes1 and seas--namely1 conglomerate1 sandstone1 shale1 limestone1 etc4 ,and now and again1 interstratified with such aqueous beds1 we meet with rocks of terrestrial origin1 such as lignite1 coal1 and the dbris of former glacial action4 ,now1 most of our aqueous rocks have been accumulated in the sea1 and thus we arrive at the conclusion that the present continental areas have from time to time been largely submerged--that the sea has frequently covered what are now the dry lands of the globe4 ,but one remarkable fact stands out1 and it is this3 ,nowhere amongst the sedimentary rocks of the earth's crust do we meet with any ancient sediments which can be likened to the red clay now slowly accumulating in the deeper abysses of the ocean4 ,there are no rocks of abysmal origin4 ,many of our limestones have undoubtedly formed in deep1 clear water1 but none of these is abysmal4 ,portions of ,europe may now and again have been submerged for several thousand feet1 but no part of this or any other continent1 so far as we yet know1 has within geological time been depressed to depths comparable to those of the present oceanic basins4 ,nay1 by far the larger portions of our marine formations have accumulated in comparatively shallow water--sandstones and shales 7sand and mud7 being by far the most common kinds of rock that we encounter4 ,in short1 aqueous strata have1 as a rule1 been deposited at no great depth and at no great distance from dry land2 the rocks are built up mostly of terrigenous material2 and even the purer limestones and chalks1 which we may suppose accumulated in seas of moderate depth1 not infrequently contain some terrestrial relic which has been drifted out to sea1 and afford other evidence to show that the nearest land was never very far away4 ,followed along their outcrop such rocks sooner or later become mixed and interbedded with ordinary sedimentary matter4 ,thus1 for example1 the thick carboniferous limestone of ,wales and the ,midlands of ,england must have accumulated in the clear water of a moderately deep sea4 ,but when this limestone is traced north into ,northumberland it begins to receive intercalations of sandstone and shale1 which become more and more important1 until in ,scotland they form by much the larger portion of the series--the enormous thick limestones of the south being represented by only a few inconsiderable beds1 included1 along with seams of ironstone and coal1 in a thick succession of sandstones and shales4 ,of the igneous rocks and the crystalline schists ,i need not speak at present1 but ,i shall have something to say about them before ,i have done4 ,having learned that no truly abysmal rocks enter into the composition of our continents1 of what kind of rocks1 we may ask1 are the islands composed8 ,well1 some of those islands are built up of precisely the same materials as we find in the continents4 ,this is the case with most islands which are not separated from continental areas by profoundly deep seas4 ,thus our own islands with their numerous satellites are geologically one with the adjacent continent4 ,their present separation is a mere accident4 ,were the ,european area1 with the adjacent sea-bed1 to be elevated for a few hundred feet we should find that ,britain and ,ireland form geologically part and parcel of the continent4 ,and the same is the case with ,nova ,zembla and ,spitzbergen in the north1 and with the ,mediterranean islands in the south4 ,there is another large class of islands1 however1 which are characterised by the total absence of any of those sedimentary rocks of which1 as ,i have just said1 our continents and continental islands are chiefly built up4 ,the islands referred to are scattered over the bosom of the great ocean1 and are surrounded by profoundly deep water4 ,some are apparently composed entirely of coral1 others are of volcanic origin1 and yet others are formed partly of volcanic rock and partly of coral4 ,thus we have two distinct kinds of island3-- #ast1 ,islands which have at one time evidently been connected with adjacent continents1 and which are therefore termed continental islands2 and #b;d1 ,oceanic islands1 which rise1 as it were1 from profound depths in the sea1 and which have never formed part of the continents4 ,the fauna and flora of the former class agree with those of the neighbouring continents1 although some modifications are met with1 especially when the insulation has been of long standing4 ,when such has been the case the species of plants and animals may be almost entirely distinct4 ,nevertheless1 such ancient continental islands agree with those which have been separated in more recent geological times in containing both indigenous amphibians and mammals4 ,oceanic islands1 on the other hand1 contain no indigenous mammals or amphibians1 their life consisting chiefly of insects and birds1 and usually some reptiles--just such a fauna as might have been introduced by the influence of winds and of oceanic currents carrying driftwood4 ,such facts1 as have now been briefly summarised1 point clearly to the conclusion that the oceanic basins and continental areas are of primeval antiquity4 ,all the geological facts go to prove that abysmal waters have never prevailed over the regions now occupied by dry land2 nor is there any evidence to show that continental land-masses ever existed in what are now the deepest portions of the ocean4 ,the islets dotted over the surface of the ,pacific and the other great seas are not the relics of a vast submerged continent4 ,they are either the tops of submarine volcanic mountains1 or they are coral structures founded upon the shoulders of degraded volcanoes and mountain-chains1 and built up to the surface by the indefatigable labours of the humble polyp4 ,we come then to the general conclusion that oceanic basins and intervening continental ridges are great primeval wrinkles in the earth's crust--that they are due to the sinking down of that crust upon the cooling and contracting nucleus4 ,these vast wrinkles had come into existence long before the formation of our oldest geological strata4 ,all our rocks may1 in short1 be looked upon as forming a mere superficial skin covering and concealing the crystalline materials which no doubt formed the original surface of the earth's crust4 ,having premised so much1 let me now turn to consider the geological history of our own ,continent1 and endeavour to trace out the various stages in its evolution4 ,of course ,i can only do so in a very brief and general manner2 it is impossible to go into details4 ,we shall find1 however1 that the history of the evolution of ,europe1 even when sketched in outline1 is one full of instruction for students of physical geography1 and that it amply bears out the view of the permanency of the greater features of the earth's surface4 ,the oldest rocks that we know of are the crystalline schists and gneiss1 belonging to what is called the ,archan system4 ,the origin of these rocks is still a matter of controversy--some holding them to be part of the primeval crust of the globe1 or the chemical precipitates of a primeval ocean1 others maintaining that they are altered or metamorphosed rocks of diverse origin1 a large proportion having consisted originally of aqueous or sedimentary rocks1 such as sandstone and shale2 while not a few are supposed to have been originally eruptive igneous rocks4 ,according to some geologists1 therefore1 the ,archan rocks represent the earliest sediments deposited over the continental ridges4 ,it is supposed that here and there those ridges rose above the surface of what may have been a boiling or highly-heated ocean1 from whose waters copious chemical precipitations took place1 while gravel and shingle gathered around the shores of the primeval lands4 ,according to other writers1 however1 the ,archan rocks were probably accumulated under normal conditions4 ,they consist1 it is contended1 partly of sediment washed down from some ancient land-surface1 and distributed over the floor of an old sea 7just as sediments are being transported and deposited in our own day71 and partly of ancient igneous rocks4 ,their present character is attributed to subsequent changes1 superinduced by heat and pressure1 at a time when the masses in question were deeply buried under later formations1 which have since been washed away4 ,in a word1 we are still quite uncertain as to the true origin of the ,archan rocks4 ,not infrequently they show a bedded structure1 and in that respect they simulate the appearance of strata of sedimentary origin4 ,it is very doubtful1 however1 whether this bedded structure is any evidence of an original aqueous arrangement4 ,we know now that an appearance of bedding has been induced in originally amorphous rocks during great earth-movements4 ,granite masses1 for example1 have been so crushed and squeezed as to assume a bedded aspect1 and a similar structure has been developed in many other kinds of rock subjected to enormous pressure4 ,whatever may have been the origin of the bedded structure of the ,archan rocks1 it is certain that the masses have been tilted up and convoluted in the most remarkable manner4 ,hitherto they have yielded no unequivocal trace of organic remains--the famous ,eozoon being now generally considered as of purely mineral origin4 ,the physical conditions under which the ,archan gneiss and schist came into existence are thus quite undetermined1 but geologists are agreed that the earliest land-surfaces1 of the former existence of which we can be quite certain1 were composed of rocks4 ,and this brings us to the beginning of reliable geological history4 ,all subsequent geological time--that1 namely1 of which we have any record preserved in the fossiliferous strata--is divided into four great eras1 namely the ,palozoic1 the ,mesozoic1 the ,cainozoic1 and the ,post-,tertiary eras1 each of which embraces various periods1 as follows3-- ,post-,tertiary ,recent4 ,pleistocene4 ,pliocene4 ,tertiary or ,miocene4 ,cainozoic ,oligocene4 ,eocene4 ,cretaceous4 ,secondary or ,jurassic4 ,mesozoic ,triassic4 ,permian4 ,carboniferous4 ,primary or ,devonian and ,old ,red ,sandstone4 ,palozoic ,silurian4 ,cambrian4 ,archan1 ,fundamental ,gneiss4 ,leaving the ,archan1 we find that the next oldest strata are those which were accumulated during the ,cambrian period1 to which succeeded the ,silurian1 the ,devonian and ,old ,red ,sandstone1 the ,carboniferous1 and the ,permian periods--all represented by great thicknesses of strata1 which overspread wide regions4 ,now1 at the beginning of the ,cambrian period1 we have evidence to show that the primeval continental ridge was still largely under water1 the dry land being massed chiefly in the north4 ,at that distant date a broad land-surface extended from the ,outer ,hebrides north-eastwards through ,scandinavia1 ,finland1 and northern ,russia4 ,how much further north and north-west of the present limits of ,europe that ancient land may have extended we cannot tell1 but it probably occupied wide regions which are now submerged in the shallow waters of the ,arctic ,ocean4 ,in the north of ,scotland a large inland sea or lake existed in ,cambrian times1,,dg and there is some evidence to suggest that similar lacustrine conditions may have obtained in the ,welsh area at the beginning of the period4 ,south of the northern land lay a shallow sea covering all middle and southern ,europe4 ,that sea1 however1 was dotted here and there with a few islands of ,archan rocks1 occupying the site of what are now some of the hills of middle ,germany1 such as the ,riesen ,gebirge1 the ,erz ,gebirge1 the ,fichtel ,gebirge1 etc41 and possibly some of the ,archan districts of ,france and the ,iberian peninsula4 ,,dg ,the ,red ,sandstones of the north-west ,highlands are now believed to be of pre-,cambrian age4 ,the succeeding period was one of eminently marine conditions1 the wide distribution of ,silurian strata showing that during the accumulation of these1 enormous tracts of our ,continent were overflowed by the sea4 ,none of these deposits1 however1 is of truly oceanic origin4 ,they appear for the most part to have been laid down in shallow seas1 which here and there may have been moderately deep4 ,during the formation of the ,lower ,silurian the whole of the ,british area1 with the exception perhaps of some of the ,archan tracts of the north-west1 seems to have been under water4 ,the submergence had commenced in ,cambrian times1 and was continued up to the close of the ,lower ,silurian period4 ,during this long-continued period of submergence volcanic activity manifested itself at various points--our country being represented at that time by groups of volcanic islands1 scattered over the site of what is now ,wales1 and extending westward into the ,irish region1 and northwards into the districts of ,cumberland and south ,ayrshire4 ,towards the close of the ,lower ,silurian period considerable earth-movements took place1 which had the effect of increasing the amount of dry land1 the most continuous mass or masses of which still occupied the northern and north-western part of our ,continent4 ,in the beginning of ,upper ,silurian times a broad sea covered the major portion of middle and probably all southern ,europe4 ,numerous islands1 however1 would seem to have existed in such regions as ,wales1 and the various tracts of older ,palozoic and ,archan rocks of middle ,germany4 ,many of these islands1 however1 were partially and some entirely submerged before the close of ,silurian times4 ,the next great period--that1 namely1 which witnessed the accumulation of the ,devonian and ,old ,red ,sandstone strata--was in some respects strongly contrasted to the preceding period4 ,the ,silurian rocks1 as ,i have said1 are eminently marine4 ,the ,old ,red ,sandstones1 on the other hand1 appear to have been accumulated chiefly in great lakes or inland seas1 and they betoken therefore the former existence of extensive lands1 while the contemporaneous ,devonian strata are of marine origin4 ,towards the close of the ,upper ,silurian period1 then1 we know that considerable upheavals ensued in western and north-western ,europe1 and wide stretches of the ,silurian sea-bottom were converted into dry land4 ,the geographical distribution of the ,devonian in ,europe1 and the relation of that system to the ,silurian1 show that the ,devonian sea did not cover so broad an expanse as that of the ,upper ,silurian4 ,the sea had shallowed1 and the area of dry land had increased when the ,devonian strata began to accumulate4 ,in trying to realise the conditions that obtained during the formation of the ,devonian and the ,old ,red ,sandstone1 we may picture to ourselves a time when the ,atlantic ,ocean extended eastwards over the south of ,england and the north-east of ,france1 and occupied the major portion of central ,europe1 sweeping north-east into ,russia1 and how much further we cannot tell4 ,north of that sea stretched a wide land-surface1 in the hollows of which lay great lakes or inland seas1 which seem now and again to have had communication with the open ocean4 ,it was in these lakes that the ,old ,red ,sandstone was accumulated1 while the ,devonian or marine rocks were formed in the wide waters lying to the south4 ,submarine volcanoes were active at that time in ,germany2 and similarly in ,scotland numerous volcanoes existed1 such as those of the ,sidlaw ,hills and the ,cheviots4 ,the ,carboniferous system contains the record of a long and complex series of geographical changes1 but the chief points of importance in the present rapid review may be very briefly summed up4 ,in the earlier part of the period marine conditions prevailed4 ,thus we find evidence to show that the sea extended further north than it did during the preceding ,devonian period4 ,during the formation of the mountain-limestone1 a deep sea covered the major portion of ,ireland and ,england1 but shallowed off as it entered the ,scottish area4 ,a few rocky islets were all that represented ,ireland and ,england at that time4 ,passing eastwards1 the ,carboniferous sea appears to have covered the low-grounds of middle ,europe and enormous tracts in ,russia4 ,the deepest part of the sea lay over the ,anglo-,hibernian and ,franco-,belgian areas2 towards the east it became shallower4 ,probably the same sea swept over all southern ,europe1 but many islands may have diversified its surface1 as in ,brittany and central ,france1 in ,spain and ,portugal1 and in the various areas of older ,palozoic and ,archan rocks in central and south-west ,europe4 ,in the latter stages of the ,carboniferous period1 the limits of the sea were much circumscribed1 and wide continental conditions supervened4 ,enormous marshes1 jungles1 and forests now overspread the newly-formed lands4 ,another feature of the ,carboniferous was the great number of volcanoes--submarine and sub-arial--which were particularly abundant in ,scotland1 especially during the earlier stages of the period4 ,the rocks of the ,permian period seem to have been deposited chiefly in closed basins4 ,when1 owing to the movement of elevation or upheaval which took place in late ,carboniferous times1 the carboniferous limestone sea had been drained away from extensive areas in central ,europe1 wide stretches of sea still covered certain considerable tracts4 ,these1 however1 as time went on1 were cut off from the main ocean and converted into great salt lakes4 ,such inland seas overspread much of the low-lying tracts of ,britain and middle ,germany1 and they also extended over a broad space in the north-east of ,russia4 ,it was in these seas that the ,permian strata were accumulated4 ,the period1 it may be added1 was marked by the appearance of volcanic action in ,scotland and ,germany4 ,so far1 then1 as our present knowledge goes1 that part of the ,european continent which was the earliest to be evolved lay towards the north-west and north4 ,all through the ,palozoic era a land-surface would seem to have endured in that direction--a land-surface from the denudation or wearing down of which the marine sedimentary formations of the bordering regions were derived4 ,but when we reflect on the great thickness and horizontal extent of those sediments1 we can hardly doubt that the primeval land must have had a much wider range towards the north and north-west than is the case with modern ,europe4 ,the lands1 from which the older ,palozoic marine sediments of the ,british ,islands and ,scandinavia were obtained1 must1 for the most part1 be now submerged4 ,in later ,palozoic times land began to extend in the ,spanish peninsula1 northern ,france1 and middle ,europe1 the denudation of which doubtless furnished materials for the elaboration of the contemporaneous strata of those regions4 ,southern ,europe is so largely composed of ,mesozoic and ,cainozoic rocks that we can say very little as to the condition of that area in ,palozoic times1 but the probabilities are that it continued for the most part under marine conditions4 ,in few words1 then1 we may conclude that while after ,archan times dry land prevailed in the north and north-west1 marine conditions predominated further south4 ,ever and anon1 however1 the sea vanished from wide regions in central ,europe1 and was replaced by terrestrial and lacustrine conditions4 ,further1 as none of the ,palozoic marine strata indicates a deep ocean1 but all consist for the most part of accumulations formed at moderate depths1 it follows that there must have been a general subsidence of our area to allow of their successive deposition--a subsidence1 however1 which was frequently interrupted by long pauses1 and sometimes by movements in the opposite direction4 ,the first period of the ,mesozoic era1 namely1 the ,triassic1 was characterised by much the same kind of conditions as obtained towards the close of ,palozoic times4 ,a large inland sea then covered a considerable portion of ,england1 and seems to have extended north into the south of ,scotland1 and across the area of the ,irish ,sea into the north-east of ,ireland4 ,another inland sea extended westward from the ,thringer-,wald across the ,vosges into ,france1 and stretched northwards from the confines of ,switzerland over what are now the low-grounds of ,holland and northern ,germany4 ,in this ancient sea the ,harz ,mountains formed a rocky island4 ,while terrestrial and lacustrine conditions thus obtained in central and northern ,europe1 an open sea existed in the more southerly regions of the continent4 ,towards the close of the period submergence ensued in the ,english and ,german areas1 and the salt lakes became connected with the open sea4 ,during the ,jurassic period the regions now occupied in ,britain and ,ireland by the older rocks appear to have been chiefly dry land4 ,scotland and ,ireland1 for the most part1 stood above the sea-level1 while nearly all ,england was under water--the hills of ,cumberland and ,westmoreland1 the ,pennine chain1 ,wales1 the heights of ,devon and ,cornwall1 and a ridge of ,palozoic rocks which underlies ,london1 being the chief lands in south ,britain4 ,the same sea overflowed an extensive portion of what is now the ,continent4 ,the older rocks in the north-west and north-east of ,france1 and the central plateau of the same country1 formed dry land2 all the rest of that country was submerged4 ,in like manner the sea covered much of eastern ,spain4 ,in middle ,europe it overflowed nearly all the low-grounds of north ,germany1 and extended far east into the heart of ,russia4 ,it occupied the site of the ,jura ,mountains1 and passed eastward into ,bohemia1 while on the south side of the ,alps it spread over a large part of ,italy1 extending eastward so as to submerge a broad area in ,austria-,hungary and the ,turkish provinces4 ,thus the northern latitudes of ,europe continued to be the site of the chief land-masses1 what are now the central and southern portions of the ,continent being a great archipelago with numerous islands1 large and small4 ,the ,jurassic rocks1 attaining as they do a thickness of several thousand feet1 point to very considerable subsidence4 ,the movement1 however1 was not continuous1 but ever and anon was interrupted by pauses4 ,taken as a whole1 the strata appear to have accumulated in a comparatively shallow sea1 which1 however1 was sufficiently deep in places to allow of the growth1 in clear water1 of coral-reefs4 ,towards the close of the ,jurassic period a movement of elevation ensued1 which caused the sea to retreat from wide areas1 and thus when the ,cretaceous period began the ,british region was chiefly dry land4 ,middle ,europe would seem also to have participated in this upward movement4 ,eventually1 however1 subsidence again ensued4 ,most of what are now the low-grounds of ,britain were submerged1 the sea stretching eastwards over a vast region in middle ,europe1 as far as the slopes of the ,urals4 ,the deepest part of this sea1 however1 was in the west1 and lay over ,england and northern ,france4 ,further east1 in what are now ,saxony and ,bohemia1 the waters were shallow1 and gradually became silted up4 ,in the ,mediterranean basin a wide open sea existed1 covering large sections of eastern ,spain and southern ,france1 overflowing the site of the ,jura ,mountains1 drowning most of the ,alpine ,lands1 the ,italian peninsula1 the eastern borders of the ,adriatic1 and ,greece4 ,in short1 there are good grounds for believing that the ,cretaceous ,mediterranean was not only much broader than the present sea1 but that it extended into ,asia1 overwhelming vast regions there1 and communicated with the ,indian ,ocean4 ,summing up what we know of the principal geographical changes that took place during the ,mesozoic era1 we are impressed with the fact that1 all through those changes1 a wide land-surface persisted in the north and north-west of the ,european area1 just as was the case in ,palozoic times4 ,the highest grounds were the ,urals and the uplands of ,scandinavia and ,britain4 ,in middle ,europe the ,pyrenees and the ,alps were as yet inconsiderable heights1 the loftiest lands being those of the ,harz1 the ,riesen ,gebirge1 and other regions of ,palozoic and ,archan rocks4 ,the lower parts of ,england and the great plains of central ,europe were sometimes submerged in the waters of a more or less continuous sea2 but ever and anon elevation ensued1 and the sea was divided1 as it were1 into a series of great lakes4 ,in the south of ,europe a ,mediterranean ,sea would appear to have endured all through the ,mesozoic era--a ,mediterranean of considerably greater extent1 however1 than the present4 ,thus we see the main features of our ,continent were already clearly outlined before the close of the ,cretaceous period4 ,the continental area then1 as now1 consisted of a wide belt of high-ground in the north1 extending roughly from south-west to north-east2 south of this a vast stretch of low-grounds1 sweeping from west to east up to the foot of the ,urals1 and bounded on the south by an irregular zone of elevated land having approximately the same trend2 still further south1 the maritime tracts of the ,mediterranean basin4 ,during periods of depression the low-grounds of central ,europe were invaded by the sea1 and the ,mediterranean at the same time extended north over many regions which are now dry land4 ,it is in these two low-lying tracts1 therefore1 and the country immediately adjoining them1 that the ,mesozoic strata of ,europe are chiefly developed4 ,a general movement of upheaval,,dh supervened at the close of the ,cretaceous period1 and the sea which1 during that period1 overflowed so much of middle ,europe had largely disappeared before the beginning of ,eocene times4 ,the southern portions of the continent1 however1 were still mostly under water1 while great bays and arms of the sea extended northwards now and again into central ,europe4 ,on to the close of the ,miocene period1 indeed1 southern and south-eastern ,europe consisted of a series of irregular straggling islands and peninsulas washed by the waters of a genial sea4 ,towards the close of early ,cainozoic times1 the ,alps1 which had hitherto been of small importance1 were greatly upheaved1 as were also the ,pyrenees and the ,carpathians4 ,the floor of the ,eocene sea in the ,alpine region was ridged up for many thousands of feet1 its deposits being folded1 twisted1 inverted1 and metamorphosed4 ,another great elevation of the same area was effected after the ,miocene period1 the accumulations of that period now forming considerable mountains along the northern flanks of the ,alpine chain4 ,notwithstanding these gigantic elevations in south-central ,europe--perhaps in consequence of them--the low-lying tracts of what is now southern ,europe continued to be largely submerged1 and even the middle regions of the continent were now and again occupied by broad lakes which sometimes communicated with the sea4 ,in ,miocene times1 for example1 an arm of the ,mediterranean extended up the ,rhone valley1 and stretched across the north of ,switzerland to the basin of the ,danube4 ,after the elevation of the ,miocene strata these inland stretches of sea disappeared1 but the ,mediterranean still overflowed wider areas in southern ,europe than it does in our day4 ,eventually1 however1 in late ,pliocene times1 the bed of that sea experienced considerable elevation1 newer ,pliocene strata occurring in ,sicily up to a height of #cjjj feet at least4 ,it was probably at or about that period that the ,black ,sea and the ,sea of ,asov retreated from the wide low-grounds of southern ,russia1 and that the inland seas and lakes of ,austria-,hungary finally vanished4 ,,dh ,i now doubt whether any vertical upheaval of a wide continental area is possible4 ,the so-called continental uplifts are probably in most cases rather negative than positive elevations4 ,in other words1 the land seems to rise simply because the sea retreats owing perhaps to the sinking of the crust within the great oceanic basins4 ,see on this subject1 ,article ,,xiii4 ,the ,cainozoic era is distinguished in ,europe for its volcanic phenomena4 ,the grandest eruptions were those of ,oligocene times4 ,to that date belong the basalts of ,antrim1 ,mull1 ,skye1 the ,fare ,islands1 and the older series of volcanic rocks in ,iceland4 ,these basalts speak to us of prodigious fissure eruptions1 when molten rock welled up along the lines of great cracks in the earth's crust1 flooding wide regions1 and building up enormous plateaux1 of which we now behold the merest fragments4 ,the ancient volcanoes of central ,france1 those of the ,eifel country and many other places in ,germany1 and the volcanic rocks of ,hungary1 are all of ,cainozoic age2 while1 in the south of ,europe1 ,etna1 ,vesuvius1 and other ,italian volcanoes date their origin to the later stages of the same great era4 ,thus before the beginning of ,pleistocene times all the main features of ,europe had come into existence4 ,since the close of the ,pliocene period there have been many great revolutions of climate2 several very considerable oscillations of the sea-level have taken place1 and the land has been subjected to powerful and long-continued erosion4 ,but the greater contours of the surface which began to appear in ,palozoic times1 and which in ,mesozoic times were more strongly pronounced1 had been fully evolved by the close of the ,pliocene period4 ,the most remarkable geographical changes which have taken place since then have been successive elevations and depressions1 in consequence of which the area of our ,continent has been alternately increased and diminished4 ,at a time well within the human period our own islands have been united to themselves and the ,continent1 and the dry land has extended north-west and north1 so as to include ,spitzbergen1 the ,fare ,islands1 and perhaps ,iceland4 ,on the other hand1 our islands have been within a recent period largely submerged4 ,the general conclusion1 then1 to which we are led by a review of the greater geographical changes through which the ,european continent has passed is simply this--that the substructure upon which all our sedimentary strata repose is of primeval antiquity4 ,our dry lands are built up of rocks which have been accumulated over the surface of a great wrinkle of the earth's crust4 ,there have been endless movements of elevation and depression1 causing minor deformations1 as it were1 of that wrinkle1 and inducing constant changes in the distribution of land and water2 but no part of the continental ridge has ever been depressed to an abysmal depth4 ,the ridge has endured through all geological time4 ,we can see also that the land has been evolved according to a definite plan4 ,certain marked features begin to appear very early in ,palozoic times1 and become more and more pronounced as the ages roll on4 ,all the countless oscillations of level1 all the myriad changes in the distribution of land and water1 all the earthquake disturbances and volcanic eruptions--in a word1 all the complex mutations to which the geological record bears witness--have had for their end the completion of one grand design4 ,a study of the geological structure of ,europe--an examination of the manner in which the highly folded and disturbed strata are developed--throws no small light upon the origin of the larger or dominant features of our ,continent4 ,the most highly convoluted rocks are those of ,archan and ,palozoic age1 and these are developed chiefly in the north-western and western parts of the ,continent4 ,highly contorted strata likewise appear in all the mountain-chains of central ,europe--some of the rocks being of ,palozoic1 while others are of ,mesozoic and of ,cainozoic age4 ,leaving these mountains for the moment out of account1 we find that it is along the western and north-western sea-board where we encounter the widest regions of highly-disturbed rocks4 ,the ,highlands of ,scandinavia and ,britain are composed1 for the most part1 of highly-flexed and convoluted rocks1 which speak to titanic movements of the crust2 and similar much-crushed and tilted rock-masses occur in north-west ,france1 in ,portugal1 and in western ,spain4 ,but when we follow the highly-folded ,palozoic strata of ,scandinavia into the low-grounds of the great plains1 they gradually flatten out1 until in ,russia they occur in undisturbed horizontal positions4 ,over thousands of square miles in that country the ,palozoic rocks are just as little altered and disturbed as strata pertaining to ,mesozoic and ,cainozoic times4 ,these facts can have but one meaning4 ,could we smooth out all the puckerings1 creases1 foldings1 and flexures which characterise the ,archan and ,palozoic rocks of western and north-western ,europe1 it is certain that these strata would stretch for many miles out into the ,atlantic4 ,obviously they have been compressed and crumpled up by some force acting upon them from the west4 ,now1 if it be true that the basin of the ,atlantic is of primeval origin1 then it is obvious that the sinking down of the crust within that area would exert enormous pressure upon the borders of our continental area4 ,as cooling and contracting of the nucleus continued1 subsidence would go on under the oceanic basin1 depression taking place either slowly and gradually1 during protracted periods1 or now and again more or less suddenly4 ,but whether gradually or suddenly effected1 the result of the subsidence would be the same upon the borders of our ,continent2 the strata along the whole western and north-western margins of the ,european ridge would necessarily be flexed and disturbed4 ,away to the east1 however1 the strata1 not being subject to the like pressure1 would be left in their original horizontal positions4 ,now it can be shown that the mountains of ,scandinavia and the ,british ,islands are much older than the ,alps1 the ,pyrenees1 and many other conspicuous ranges in central and southern ,europe4 ,our mountains and those of ,scandinavia are the mere wrecks of their former selves4 ,originally they may have rivaled--they probably exceeded--the ,alps in height and extent4 ,it is most likely1 indeed1 that the areas of ,palozoic rocks in ,france1 ,portugal1 and ,spain also attained mountainous elevations4 ,but the principal upheaval of the western margins of our ,continent was practically completed before the close of the ,palozoic period1 and since that time those elevated regions have been subjected to prodigious erosion1 the later formations being in large measure composed of their dbris4 ,i do not1 of course1 wish it to be understood that there has been no upheaval affecting the west of ,europe since ,palozoic times4 ,the tilted position of many of our ,mesozoic strata clearly proves the contrary4 ,but undoubtedly the main disturbances which produced the folding1 fracturing1 and contortion of the ,palozoic strata of western ,europe took place before the close of the ,palozoic period4 ,the mountains of ,britain and ,scandinavia are amongst the oldest in ,europe4 ,when we come to inquire into the origin of the mountains of central ,europe we have little difficulty in detecting the chief factors in their formation4 ,an examination of the ,pyrenees1 the ,alps1 and other hill-ranges having the same general trend shows us that they consist of flexed and convoluted rocks4 ,they are1 in short1 mountains of elevation1 ridged up by tangential thrusts4 ,of this we need not have the slightest doubt4 ,if1 for example1 we approach the ,alps from the low-grounds of ,france1 we observe the strata as we come towards the ,jura beginning to undulate--the undulations becoming more and more marked1 and passing into sharp folds and plications1 until1 in the ,alps1 the beds become twisted1 convoluted1 and bent back upon themselves in the wildest confusion4 ,now1 speaking in general terms1 we may say that similar facts confront us in connection with every true mountain-range in central ,europe4 ,let it be noted1 further1 that all those ranges have the same trend1 which we may take to be approximately east and west1 or nearly at right angles to the trend of the ,palozoic high-grounds of western and north-western ,europe4 ,looked at broadly1 our continental ridge may be said to be traversed from west to east by two wide depressions or troughs1 separated by the intervening belt of higher grounds just referred to4 ,the former of these troughs corresponds to the great central plain1 which passes through the south of ,england1 north-east ,france1 the ,low ,countries1 and ,denmark1 whence it sweeps east through ,germany1 and expands into the wide low-grounds of ,russia4 ,the southern trough or depression embraces the maritime tracts of the ,mediterranean and the regions which that sea covers4 ,such1 then1 are the dominant features of our ,continent1 to which all others are of subordinate importance4 ,now it cannot be doubted that the two great troughs are belts of subsidence in the continental ridge itself4 ,and their existence explains the origin of the mountain-ranges which separate them4 ,we know that the northern trough is of extreme antiquity2 it is older1 at all events1 than the ,silurian period4 ,even at that distant date its southern limits were marked out by ridges of ,archan rocks1 which seem to have formed islands in what is now middle ,germany1 and probably also in ,switzerland and central ,france4 ,the appearance of those ,archan rocks in central ,europe was doubtless due to a ridging up of the crust induced by those parallel movements of subsidence which produced the northern and southern troughs4 ,the northern trough was probably always the shallower depression of the two1 for we have evidence to show that1 again and again in ,mesozoic and later times1 the seas which overflowed what are now the central plains of ,europe were of less considerable depth than that which occupied the ,mediterranean trough4 ,as time rolled on1 therefore1 the northern trough eventually became silted up2 but so low even now is the level of that trough that a relatively slight depression would cause the sea to inundate most extensive regions in middle ,europe4 ,in ,cainozoic times1 as we have seen1 the last great elevation of the ,alps was effected--an elevation which can hardly have been due to any other cause than the more or less abrupt depression of the earth's crust under the ,mediterranean basin4 ,the area of that sea is now much less considerable than it was in ,tertiary times--a change due in part to silting up1 but chiefly perhaps to the sinking down of its bed to profounder depths4 ,thus we may conclude that from a very early period--a period ante-dating the formation of our oldest fossiliferous strata--the physical structure of our ,continent had already been planned4 ,the dominant features of the primeval continental ridge are those which have endured through all geological time4 ,they are the lines along which the beautiful lands in which we dwell have been constructed4 ,tilted and convoluted1 broken and crushed by myriad earth-movements--scarred1 furrowed1 worn and degraded by the frosts1 the rains1 the rivers1 and the seas of countless ages--the rocks of our ,continent are yet eloquent of design4 ,where the ignorant sees nothing save confusion and discord1 the thoughtful student beholds everywhere the evidence of a well-ordered evolution4 ,such is the conclusion to which we are led by all geological research4 ,illustration3 ,,sketch-,,maps ,,illustrating ,,the ,,geographical ,,evolution ,,of ,,continental ,,areas ,by ,,professor ,,james ,,geikie1 ,,ll4,d41 ,d4,c4,l41 ,f4,r4,s4 ,,plate ,v ---------------------------------------- ------------------- ,,map ,,showing ,,the ,,map ,,showing ,,the ,,area ,,of ,,continental ,,plateau ,,area ,,of ,,continental ,,plateau ,,occupied ,,by ,,sea ,,in ,,occupied ,,by ,,sea ,,in ,,pal,,ozoic ,,times4 ,,tertiary ,,times4 ---------------------------------------- ------------------- ,,map ,,showing ,,the ,,map ,,showing ,,the ,,area ,,of ,,continental ,,plateau ,,areas ,,of ,,dominant ,,depression ,,occupied ,,by ,,sea ,,in ,,and ,,elevation4 ,,mesozoic ,,times4 7,below ,above the #ajjj fathom ,contour ,line7 ---------------------------------------- ------------------- ,the ,edinburgh ,geographic ,institute ,j4 ,g4 ,bartholomew1 ,f4,r4,g4,s4 ,,xii4 ,the ,evolution of ,climate4,,di ,,di ,address delivered before the ,royal ,physical ,society at the opening of the ,session #ahhi-ij4 ,one of the most interesting questions with which geological science has to deal is that of the evolution of climate4 ,although there is no general agreement as to how former climatic fluctuations came about1 yet the prevalent opinion is that in the past1 just as in the present1 the character of the climate must have depended mainly on latitude and the relative position of the great land- and water-areas4 ,this was the doctrine taught by ,lyell1 and its cogency none will venture to dispute4 ,it is true he postulated a total redistribution of oceans and continents--a view which the progress of science has shown to be untenable4 ,we can no longer speculate with him on the possibility of all the great land-areas having been grouped at one time round the equator1 and at some other period about the poles4 ,on the contrary1 the evidence goes to show that the continents have never changed places with the ocean--that the dominant features of the earth's crust are of primeval antiquity1 and ante-date the oldest of the fossiliferous formations4 ,the whole question of climatic changes1 therefore1 must be reconsidered from the point of view of the modern doctrine of the permanency of continental and oceanic areas4 ,but before proceeding to this discussion1 it may be well to glance for a moment at the evidence from which it has been inferred that the climate of the world has varied4 ,among the chief proofs of climatic fluctuations are the character and the distribution of former floras and faunas4 ,it is true1 fossils are1 for the most part1 relics of extinct forms1 and we cannot assert of any one of these that its environment must have been the same as that of some analogous living type4 ,but1 although we can base no argument on individual extinct forms1 it does not follow that we are precluded from judging of the conditions under which a whole suite of extinct organisms may have lived4 ,doubtless1 we can only reason from the analogy of the present2 but1 when we take into account all the forms met with in some particular geological system1 we seem justified in drawing certain conclusions as to the conditions under which they flourished4 ,thus1 should we encounter in some great series of strata many reef-building corals1 associated with large cephalopods and the remains of tree-ferns and cycads1 which last from their perfect state of preservation could not have drifted far before they became buried in sediment1 we should surely be entitled to conclude that the strata in question had been deposited in the waters of a genial sea1 and that the neighbouring land likewise enjoyed a warm climate4 ,again should a certain system1 characterised by the presence of some particular and well-marked flora and fauna1 be encountered not only in sub-tropical and temperate latitudes but also far within the ,arctic ,circle1 we should infer that such a flora and fauna lived under climatic conditions of a very different kind from any that now exist4 ,the very presence1 in the far north1 of fossils having such a geographical distribution would show that the temperature of polar seas and lands could not have been less than temperate4 ,when such broad methods of interpretation are applied to the problems suggested by former floras and faunas1 we seem compelled to conclude that the conditions which determined the distribution of life in bygone ages must have been1 upon the whole1 more uniform and equable than they are now4 ,it is unnecessary that ,i should go into detailed proof2 but ,i may refer1 by way of illustration1 to what is known of the ,silurian and ,carboniferous fossils of the arctic regions4 ,most of these occur also in the temperate latitudes of ,europe and ,north ,america1 while many are recognised as distinctive types of the same strata nearly all the world over4 ,as showing how strongly the former broad distribution of life-forms is contrasted with their present restricted range1 ,professor ,heilprin has cited the ,brachiopoda4 ,taking existing species and varieties as being #ace in number1 he remarks that there is scarcely a single species which can be said to be strictly cosmopolitan in its range1 although not a few are very widely distributed2 and1 if we except boreal and hyperboreal forms1 but a very limited number whose range embraces opposite sides of the same ocean4 ,on the other hand1 if we accept the data furnished by ,richthofen concerning the ,chinese ,brachiopoda we find that out of a total of thirteen ,silurian and twenty-four ,devonian species1 no less than ten of the former and sixteen of the latter recur in the equivalent deposits of western ,europe3 and1 further1 that the ,devonian species furnish eleven1 or nearly #ej per cent4 of the entire number1 which are cosmopolitan or nearly so4 ,again1 of the twenty-five ,carboniferous species1 ,north ,america holds fully fifteen1 or #fj per cent41 and a very nearly equal number are cosmopolitan4 ,the same palontologist reminds us that by far the greater number of fossils which occur in the ,palozoic strata of ,australia are present also in regions lying well within the limits of the north temperate zone4 ,in fact1 he continues1 the relationship between this southern fauna and the faunas of ,europe and ,north ,america is so great as to practically amount to identity4 ,but1 side by side with such evidence of broad distribution1 we are confronted with facts which go to show that1 even at the dawn of ,palozoic times1 the oceanic areas at all events had their more or less distinct life-provinces4 ,while many of the old forms were cosmopolitan1 others were apparently restricted in their range4 ,it would be strange1 indeed1 had it been otherwise2 for1 however uniform the climatic conditions may have been1 still that uniformity was only comparative4 ,an absolutely uniform world-climate is well-nigh inconceivable4 ,all we can maintain is that the conditions during certain prolonged periods were so equable as to allow of the general diffusion of species over vastly greater areas than now2 and that such conditions extended from low latitudes up to polar regions4 ,now1 among the chief factors which in our day determine the limitation of faunas and floras1 we must reckon latitude and the geographical position of land and water4 ,what1 then1 it may be asked1 were the causes which allowed of the much broader distribution of species in former ages8 ,it is obvious that before a completely satisfactory answer to that question can be given1 our knowledge of past geographical conditions must be considerably increased4 ,if we could prepare approximately correct maps and charts to indicate the position of land and sea during the formation of the several fossiliferous systems1 we should be able to reason with some confidence on the subject of climate4 ,but1 unfortunately1 the preparation of such correct maps and charts is impossible4 ,the data for compilations of the kind required are still inadequate1 and it may well be doubted whether1 in the case of the older systems1 we shall ever be able to arrive at any detailed knowledge of their geographical conditions4 ,nevertheless1 the geological structure of the earth's crust has been so far unravelled as to allow us to form certain general conceptions of the conditions that must have attended the evolution of our continents4 ,and it is with such general conceptions only that ,i have at present to deal4 ,i said a little ago that the question of geological climates must now be considered from the point of view of the permanency of the great dominant features of the earth's crust4 ,i need not recapitulate the evidence upon which ,dana and his followers have based this doctrine of the primeval antiquity of our continental and oceanic areas4 ,it is enough if ,i remind you that by continental areas we simply mean certain extensive regions in which elevation has1 upon the whole1 been in excess of depression2 by oceanic area1 on the other hand1 is meant that vast region throughout which depression has exceeded elevation4 ,thus1 while the area of permanent or preponderating depression has1 from earliest geological times1 been occupied by the ocean1 the continental areas have been again and again invaded by the sea--and even now extensive portions are under water4 ,it is not only the continental dry land1 therefore1 but all the bordering belt of sea-floor which does not exceed #ajjj fathoms or so in depth1 that must be included in the region of dominant elevation4 ,were the whole of this region to be raised above the level of the sea1 the present continents would become connected so as to form one vast land-mass1 or continental plateau4 7,d1 ,plate ,,iv47 ,all the sedimentary strata with which we are acquainted have been accumulated over the surface of that great plateau1 and consequently are of comparatively shallow-water origin4 ,they show us1 in fact1 that at no time in geological history has that plateau ever been drowned in depths at all comparable to those of the deeper portions of our oceanic troughs4 ,the stratified rocks teach us1 moreover1 that the present land-areas have been gradually evolved1 and that1 notwithstanding many oscillations of level1 these areas have continued to increase in extent--so that there is probably more land-surface now than at any previous era in the history of our globe4 ,to give even a meagre outline of the evidence bearing upon this interesting subject is here impossible4 ,all that ,i can do is to indicate very briefly some of the general results to which that evidence seems to lead4 ,the oldest rocks with which we are acquainted are the so-called ,archan schists,,dj ,but these have hitherto yielded no unequivocal traces of organic life1 and as their origin is still doubtful1 it would obviously be futile to speculate upon the geographical conditions of the earth's surface at the time of their formation4 ,reliable geological history only begins with the fossiliferous strata of the ,palozoic era4 ,from these we learn that in the ,european area the ,archan rocks of ,britain1 ,scandinavia1 and ,finland formed1 at that time1 the most extensive tract of dry land in our part of the world4 ,how far beyond the present limits of ,europe that ancient northern land extended we cannot tell2 but it probably occupied considerable regions which are now submerged in the waters of the ,arctic ,ocean4 ,further south1 the continental plateau appears to have been1 for the most part1 overflowed by a shallow sea1 the surface of which was dotted by a few islands of ,archan rocks1 occupying the sites of what are now some of the hills of middle ,germany and the ,archan districts of ,france and the ,iberian ,peninsula4 ,archan rocks occur likewise in ,corsica and ,sardinia1 and again in ,turkey3 they also form the nuclei of most of the great ,european mountain-chains1 as the ,pyrenees1 the ,alps1 the ,carpathians1 and the ,urals4 ,these areas of crystalline schists may not1 it is true1 have existed as islands at the beginning of ,palozoic times1 for they were doubtless ridged up by successive elevations at later dates2 but their very presence as mountain-nuclei is sufficient to show that at a very early geological period1 the continental plateau could not have been covered by any great depth of sea4 ,we can go further than this--for all the evidence points to the conclusion that1 even so far back as ,cambrian times1 the dominant features of the present ,european continent had been1 as it were1 sketched out4 ,looked at broadly1 that part of the great continental plateau upon which our ,european lands have been gradually built up may be said to be traversed from west to east by two wide depressions1 separated by an intervening elevated tract4 ,the former of these depressions corresponds to the great ,central ,plain which passes through the south of ,england1 north-east of ,france1 and the ,low ,countries1 whence it sweeps through ,germany1 to expand into the extensive low-grounds of central and northern ,russia4 ,the southern depression embraces the maritime tracts of the ,mediterranean1 and the regions which that sea covers4 ,to these dominant features all the others are of subordinate importance4 ,the two great troughs are belts of depression in the continental plateau itself4 ,the northern one is of extreme antiquity--it is older1 at all events1 than the ,cambro-,silurian period4 ,even at that distant date its southern limits were marked out by ridges of ,archan rock1 which1 as ,i have said1 seem to have formed islands in what is now central ,europe4 ,it was probably always the shallower depression of the two1 for we have evidence to show that again and again1 in ,mesozoic and later times1 the sea that overflowed what are now the central lowlands of ,europe was of less considerable depth than that which occupied the ,mediterranean trough4 ,,dj ,i need hardly remind geologists that some of the so-called ,archan schists may really be the highly altered accumulations of later geological periods4 ,if we turn to ,north ,america1 we find similar reason to conclude1 with ,professor ,dana1 that the general topography of that region had likewise been foreshadowed as far back as the beginning of the ,palozoic era4 ,dana tells us that even then the formation of its chief mountain-chains had been commenced1 and its great intermediate basins were already defined4 ,the oldest lands of ,north ,america were built up1 as in ,europe1 of azoic rocks1 and were grouped chiefly in the north4 ,archan masses extend over an enormous region1 from the shores of the ,arctic ,ocean down to the great lake country1 and they are seen likewise in ,greenland and many of the ,arctic islands4 ,they appear also in the long mountain-chains that run parallel with the coast-lines of the ,continent4 ,in a word1 the present distribution of the ,archan rocks1 and their relation to overlying strata1 lead to the belief that in ,north ,america1 just as in ,europe1 they form the foundation-stones of that continent1 and stretch continuously throughout its whole extent4 ,we know comparatively little of the geology of the other great land-masses of the globe1 but from such evidence as we have there is reason to believe that these in their general structure have much the same story to tell as ,europe and ,north ,america4 ,in ,south ,america1 ,archan rocks extend over vast areas in the east and north-east1 and reappear in the lofty mountain-chains of the ,pacific border4 ,they have been recognised also in various parts of ,africa1 alike in the north and east1 in the interior1 and in the west and south4 ,in ,asia1 again1 they occupy wide areas in the ,indian ,peninsula2 they are well developed in the ,himalaya1 while in ,china and the mountains and plateaux of central ,asia1 azoic rocks1 which are probably of ,archan age1 are well developed4 ,the crystalline schists1 which cover extensive tracts in ,australia and in the northern island of ,new ,zealand1 have also been referred to the same age4 ,thus1 all the world over1 ,archan rocks seem to form the surface of the ancient continental plateau upon which all other sedimentary strata have been accumulated4 ,and in every region where ,palozoic rocks occur1 we have evidence to prove that at the time these last were formed vast areas of the old continental plateau were under water4 ,the geological structure of the ,palozoic tracts of ,europe and ,america has shown us that1 during the protracted period of their accumulation1 and notwithstanding many oscillations of level1 the land-surface continued to increase4 ,the same growth of dry land characterised ,mesozoic and ,cainozoic times--the primeval depressions that traverse the continental plateau became more and more silted up1 and the sea eventually disappeared from extensive regions which it had overflowed in ,palozoic ages4 ,this land-growth1 of course1 was not everywhere continuous4 ,again and again1 throughout wide tracts1 depression was in excess of sedimentation and elevation4 ,even at the present time1 broad tracts of what was once dry land are submerged4 ,but the simple fact that the younger fossiliferous strata do not extend over such wide areas as the older systems1 is sufficient proof that our land-masses have all along tended to grow1 and to become more and more consolidated4 ,reference has already been made to the remarkable fact that no abysmal accumulations have yet been detected amongst the stratified rocks of the earth's crust4 ,ordinary clastic rocks1 such as shale1 sandstone1 and conglomerate--altered or unaltered1 as the case may be--form by far the largest proportion of our aqueous strata1 and speak to us only of shallow waters4 ,it is true that some of our limestones must have accumulated in moderately deep clear seas1 yet none of these limestones is of abysmal origin4 ,they prove that portions of the continental plateau have now and again been submerged for several thousand feet1 but afford no evidence of depths comparable to those of the present oceanic basins4 ,the enormous thickness obtained by the sedimentary strata can only be explained on the supposition that deposition took place over a gradually sinking area4 ,and thus it can be shown that1 within the continental plateau1 movements of depression have been carried on more or less continuously during vast periods of time--and yet so gradually1 that sedimentation was able to keep pace with them4 ,take1 for example1 the ,cambrian strata of ,wales and ,shropshire--all1 apparently1 shallow-water deposits--which attain a thickness of #cj1jjj feet1 or thereabout2 or the ,silurian strata of the same regions1 which are not much less than #bj1jjj feet thick2 and similar great depths of sedimentary rocks might be cited from ,north ,america4 ,passing on to later periods1 we find like evidence of long-continued depression in the thick sediments of the younger ,palozoic systems4 ,it is noteworthy1 however1 that when we come down to still later ages1 the movements of depression1 as measured by the depths of the strata1 appear to have become less and less extensive and profound4 ,each such movement of depression was eventually brought to a close by one or more movements of upheaval--slowly or more rapidly effected1 as the case may have been4 ,here1 then1 we are confronted with the striking fact that the continental plateau has1 from time to time1 sunk down over wide areas to depths exceeding those of existing oceans1 and yet at so slow a rate1 that sedimentation prevented the depressed regions from becoming abysmal4 ,it is obvious1 then1 that such areas are now dry land simply because1 in the long-run1 sedimentation and upheaval have been in excess of depression4 ,and yet1 notwithstanding the numerous upheavals which have taken place over the continental plateau1 these have succeeded in doing little more than drain away the sea more or less completely from the great primeval depressions by which that plateau is traversed4 ,if it be true1 therefore1 that the continental plateau owes its existence to the sinking down of the earth's crust within the oceanic basins--if the continents have been squeezed up by the tangential thrusts exerted by the sinking areas that surround them--then it follows that while lands have been gradually extending over the continental plateau1 the bed of the ocean has been sinking to greater and greater depths4 ,if this general conclusion holds good1 it is obvious that the oceanic troughs of early geological times could not have been so deep as they are now4 ,during the ,palozoic period1 the most continuous areas of dry land1 as we have seen1 were distributed over the northern parts of our hemisphere1 while1 further south1 groups of islands indicated the continuation of the continental plateau4 ,doubtless ,south ,america1 ,africa1 ,asia1 and ,australia were1 at that distant date1 represented by similar detached areas of dry land4 ,in a word1 the primeval continental plateau was still largely under water4 ,judging from the character and broad distribution of the ,palozoic marine faunas the temperature of the sea was wonderfully uniform4 ,there is certainly nothing to indicate the existence of such climatic zones as those of the present4 ,we know very little of the terrestrial life of early ,palozoic times--the ,cambro-,silurian strata are essentially marine4 ,land-plants1 however1 become more numerous in the ,old ,red ,sandstone1 and1 as every one knows1 they abound in the succeeding ,carboniferous and ,permian systems4 ,and the testimony of these floras points to the same conclusion as that furnished by the marine faunas4 ,the ,carboniferous floras of the arctic regions1 and of temperate ,europe and ,america1 not only have the same facies1 but a considerable number of the species is common to both areas2 while many ,european species occur in the ,carboniferous strata of ,australia and other distant lands4 ,this common facies1 and the presence of numerous cosmopolitan forms1 surely indicate the former prevalence of remarkably uniform climatic conditions4 ,the conditions1 of course1 need not--indeed1 could not--have been absolutely uniform4 ,at present the various climates which our globe experiences depend upon the amount of heat received directly and indirectly from the sun--oceanic and arial currents everywhere modifying the results that are due to latitude4 ,it cannot have been otherwise in former times4 ,in all ages the tropics must have received more direct sun-heat than temperate and polar regions2 and however much the climatic conditions of the ,palozoic era may have differed from the present--however uniformly temperature may have been distributed--still1 as ,i have said1 absolute uniformity was impossible4 ,it was doubtless owing to the fact that the dry lands of ,palozoic times were not only much less extensive than now1 but more interrupted1 straggling1 and insular1 that the climate of the globe was so equable4 ,under such geographical conditions1 great oceanic currents would have a much freer course than is now possible1 and warm water would find its way readily across wide regions of the submerged continental plateau into the highest latitudes4 ,the winds blowing athwart the land would everywhere be moist and warm1 and no such marked differences of temperature1 such as now obtain1 would distinguish the arctic seas from those of much lower latitudes4 ,at the same time1 the comparatively shallow water overlying the submerged areas of the continental plateau would favour the distribution of species1 and thus bring about that wide distribution of cosmopolitan forms and general similarity of facies1 which are such marked features of the ,palozoic faunas4 ,it is even quite possible that migration may have taken place here and there across the great oceanic depression itself2 for it may well be doubted whether1 at so early a period1 the depression had sunk down to its present depth below the level of the continental plateau4 ,yet1 notwithstanding such facilities for migration1 and the consequent similarity of facies ,i have referred to1 the ,palozoic faunas of different regions have usually certain distinctive characters4 ,even at the very dawn of the era the marine faunas were already grouped into provinces1 sometimes widely separated from one another1 at other times closely adjacent1 so that it is evident that barriers to migration here and there existed4 ,it could hardly have been otherwise2 for local and more widely-spread movements of elevation and depression took place again and again during ,palozoic times4 ,while the younger ,palozoic systems were being accumulated1 excess of upheaval over depression resulted in the gradual increase of the land4,,dk ,the continental plateau came more and more to the surface1 in spite of many oscillations of level4 ,it is quite possible1 nay1 even probable that this persistent growth of land1 and consequent modification of oceanic currents may have rendered the climatic conditions of later ,palozoic times less uniform3 but1 if so1 such diminished uniformity has left no recognisable impress on either faunas or floras2 for fossils characteristic of the ,devonian and ,carboniferous strata of temperate latitudes occur far within the ,arctic ,circle4 ,,dk ,see footnote p4 #cda4 ,descending to the ,mesozoic era1 we find that the character and distribution of marine faunas are still indicative of uniformity4 ,there could have been little difference of temperature at that time between arctic seas and those of our own latitude4 ,cosmopolitan species abounded in the ,jurassic waters1 but were relatively less numerous in those of the ,cretaceous period4 ,professor ,neumayr maintains that already1 in the ,jurassic period1 the climate had become differentiated into zones4 ,this1 he thinks1 is indicated by the fact that coral reefs abound in the ,jurassic strata of central ,europe1 while they are wanting in the contemporaneous deposits of boreal regions4 ,dr4 ,heilprin1 on the other hand1 is of opinion that this and certain other distinctive features of separate ,jurassic life-provinces may not have been due to differences of temperature1 but rather to varying physical conditions1 such as character of the sea-bottom1 depth of water1 and so forth4 ,perhaps the safest conclusion we can come to1 in the present state of the evidence1 is that the climatic conditions of the ,mesozoic era were1 upon the whole1 less obviously uniform than those of earlier ages1 but that marked zones of climate like the present had not as yet been evolved4 ,at the same time1 when we consider how many great geographical revolutions took place during the period in question1 we must be prepared to admit that these could hardly fail to influence the climate1 and thus to have induced modifications in the distribution of faunas and floras4 ,and probably evidence of such modifications will yet be recognised1 if indeed the phenomena referred to by ,neumayr be not a case in point4 ,it may be noted1 further1 that while1 according to many botanists1 the plants of the ,palozoic periods bespeak not only uniform climatic conditions but the absence of marked seasonal changes1 those of late ,mesozoic times are indicative of less uniformity4 ,the ,cretaceous conifers1 for example1 show regular rings of growth1 and betoken the existence of seasons1 which were less marked1 however1 than is now the case4 ,the geographical changes of ,mesozoic times were notable in many respects4 ,the dominant features of ,europe1 already foreshadowed in early ,palozoic times1 had become more clearly outlined before the close of the ,cretaceous period4 ,notwithstanding many movements of depression1 the chief land-areas continued to show themselves in the north and north-west4 ,the highest grounds were the ,urals1 and the uplands of ,scandinavia and ,britain4 ,in middle ,europe the ,pyrenees and the ,alps were as yet inconsiderable heights1 the loftiest lands in that region being those of the ,harz1 the ,riesen ,gebirge1 and other tracts of ,archan and ,palozoic rocks4 ,the lower parts of ,england and the great lowland plains of central ,europe were sometimes submerged in the waters of a wide1 shallow sea1 but ever and anon elevation ensued1 new lands appeared1 and these waters became divided into a series of large inland seas and lakes4 ,in the south1 a deep ,mediterranean sea would appear to have persisted all through the ,mesozoic era--a sea of considerably greater extent1 however1 than the present4 ,while in ,europe the dominant features of the continental plateau run approximately east and west1 in ,north ,america they follow nearly the opposite direction4 ,in early ,mesozoic times1 vast tracts of dry land extended across the northern and eastern sections of the latter area4 ,over the ,rocky ,mountain region1 low lands and saline lakes appear to have stretched1 while further west the area of the ,great ,plateau and the ,pacific slope were covered by the sea4 ,towards the end of the ,mesozoic era1 the land in the far west became more continuous--a broad belt extending in the direction of the ,pacific coast-line from ,mexico up to high northern latitudes4 ,in short1 before the ,cretaceous period closed1 the major portion of ,north ,america had been evolved4 ,a considerable tract of what is now the western margin of the continent1 however1 was still under water1 while from the ,gulf of ,mexico 7then much wider than now7 a broad ,mediterranean sea swept north and north-west through ,texas and the ,rocky ,mountain region to communicate with the ,arctic ,ocean4 ,all to the east of this inland sea was then1 as it is now1 dry land4 ,thus1 up to the close of the ,cretaceous period1 in ,america and ,europe alike1 oceanic currents coming from the south had ready access across the primeval continental plateau to the higher latitudes4 ,southern ,europe indeed1 during ,mesozoic times1 was simply a great archipelago1 having free communication on the one hand across the low-grounds of central and northern ,russia with the arctic seas1 and1 on the other1 across vast regions in ,asia with the ,indian ,ocean4 ,of the other great land-masses of the globe our knowledge is too limited to allow us to trace their geographical evolution with any confidence4 ,but from the very wide distribution of ,mesozoic strata in ,south ,america1 ,africa1 ,asia1 and ,australia1 there can be no doubt that1 at the time of their accumulation1 enormous tracts in those regions were then under water4 ,the land-masses1 in short1 were not so continuous and compact as they are at present4 ,and although we must infer that considerable areas of ,mesozoic land are now submerged1 yet these cannot but bear a very small proportion to the wide regions which have been raised above the sea-level since ,mesozoic times4 ,in short1 from what we do know of the geological structure of the continents in question1 we can hardly doubt that they have passed through geographical revolutions of a like kind with those of ,europe and ,north ,america4 ,everywhere over the great continental plateau elevation appears1 in the long-run1 to have been in excess of depression1 so that1 in spite of many subsidences1 the tendency of the land throughout the world has been to extend its margins1 and to become more and more consolidated4 ,the ,mesozoic lands were larger than those of the preceding ,palozoic era1 but they were still penetrated in many places by the sea1 and warm currents could make their way over wide tracts that are now raised above the sea-level4 ,under such circumstances approximately uniform conditions of climate could not but obtain4 ,great geographical changes supervened upon the close of the ,cretaceous period4 ,north ,america then acquired nearly its present outline4 ,its ,mediterranean sea had vanished1 but the ,gulf of ,mexico still overflowed a considerably wider region than now1 while a narrow margin of the ,pacific border of the continent continued submerged4 ,in ,europe elevation ensued1 and the sea which had overspread so much of the central and eastern portions of our ,continent disappeared4 ,southern ,europe1 however1 was still largely under water1 while bays and inlets extended northwards into what are now the central regions of the ,continent4 ,on to the close of the ,miocene period1 indeed1 the southern and south-eastern tracts of ,europe were represented by straggling islands4 ,in middle ,cainozoic times the ,alps1 which had hitherto been of small importance1 were considerably upheaved1 as were also the ,pyrenees and the ,carpathians2 and a subsequent great elevation of the ,alpine area was effected after the ,miocene period4 ,notwithstanding these gigantic movements1 the low-lying tracts of what is now southern ,europe continued to be largely submerged1 and even the central regions of the ,continent were now and again occupied by broad lakes1 which sometimes communicated with the sea4 ,after the elevation of the ,miocene strata1 these inland seas disappeared1 but the ,mediterranean still overflowed wider areas than it does to-day4 ,eventually1 however1 in late ,pliocene times1 the bed of that sea experienced considerable elevation2 and it was probably at or about this stage that the ,black ,sea and the ,sea of ,asov retreated from the broad low-grounds of southern ,russia1 and that the inland seas and lakes of ,austria-,hungary finally vanished4 ,the movements of upheaval1 which caused the ,cretaceous seas to disappear from such broad areas of the continental plateau1 induced many changes in the floras and faunas of the globe4 ,a notable break in the succession occurs between the ,cretaceous and the ,eocene1 hardly one species of higher grade than the protozoa passing from one system to the other4 ,in the ,cainozoic deposits we are no longer confronted with numerous cosmopolitan species--the range of marine forms has become much more restricted4 ,nevertheless1 the faunas and floras continue to be indicative of much warmer climates for arctic and temperate latitudes than now obtain4 ,but1 at the same time1 differentiation of climate into zones is distinctly marked4 ,in the early ,cainozoic period1 our present temperate latitudes supported a flora of decidedly tropical affinities1 while the fauna of the adjacent seas had a similar character4 ,later on the climate of the same latitudes appears to have passed successively through sub-tropical and temperate stages4 ,in short1 a gradual lowering of the temperature is evinced by the character and distribution both of floras and faunas4 ,the differentiation of the climate during one stage of the ,cainozoic era is well illustrated by the ,miocene flora4 ,thus1 at a time when ,italy was clothed with a tropical vegetation1 in which palm-trees predominated1 middle ,europe had its extensive forests of evergreens and conifers1 while in the region of the ,baltic conifers and deciduous trees were the prevalent forms4 ,when one takes into consideration the fact that1 notwithstanding many oscillations of level1 the land during ,cainozoic times was gradually extending1 and the sea disappearing from wide regions which it had formerly covered1 one can hardly doubt that the seemingly gradual change from tropical to temperate conditions was due1 in large measure1 to that persistent continental growth4 ,i confess1 however1 that it is difficult to account for the very genial climate which continued to prevail over the arctic regions4 ,so far as one can gather from the evidence at present available1 some of the marine approaches to those latitudes had been cut off by the movements of elevation which brought the ,cainozoic era to a close1 while the arctic lands were perhaps more extensive than they are now4 ,the ,cretaceous ,mediterranean ,sea of ,north ,america had vanished1 and we cannot prove that the ,tertiary ,sea of southern ,europe communicated across the low-grounds of ,russia with the ,arctic ,ocean4 ,we know1 however1 that the archipelago of southern ,europe was in direct connection with the ,indian ,ocean1 and it is most probable that a wide arm of the same sea stretched north from the ,aralo-,caspain area through ,siberia4 ,indeed1 much of what are now the lowlands of western and northern ,asia was probably sea in ,tertiary times4 ,it seems likely1 therefore1 that1 even at this late period1 marine currents continued to reach the ,arctic ,zone across the continental plateau4 ,when the warm waters of the ,indian ,ocean eventually ceased to invade ,europe1 and the ,mediterranean became much restricted in area1 the climate of the whole ,continent could not fail to be profoundly affected4 ,there is yet another line of evidence to which brief reference may be made4 ,i have spoken of the remarkable uniformity of climatic conditions which obtained in ,palozoic times1 and of the gradual modification of these conditions which subsequently supervened4 ,now1 it is worthy of note that in their lithological characters the oldest sedimentary strata themselves likewise exhibit a prevalent uniformity which in later systems becomes less and less conspicuous4 ,the ,cambro-,silurian mechanical sediments1 for example1 maintain much the same character all the world over2 and the like is true1 although in a less degree1 of the marine accumulations of the ,devonian period4 ,the corresponding mechanical deposits of later ,palozoic ages continue to show more and more diversity1 but at the same time they preserve a similarity of character over much more extensive areas than is found to be the case with the analogous sediments of the ,mesozoic era4 ,finally1 these last are more or less strongly contrasted with the marine mechanical accumulations of ,cainozoic times1 which are altogether more local in character4 ,this increasing differentiation is quite in keeping with what we know of the evolution of our land-areas4 ,in early ,palozoic ages1 when insular conditions prevailed and the major portion of the primeval continental plateau was covered by shallow seas1 it is obvious that mechanical sediments would be swept by tidal and other currents over enormous areas1 and that these sediments would necessarily assume a more or less uniform character4 ,indeed1 ,i suspect that much of the sediment of those early seas may have been the result of tidal scour1 and that marine erosion was more generally effective then than it is now4 ,with the gradual growth of the land and the consequent deflection and limitation of currents1 marine mechanical sediments would tend to become more and more local in character4 ,thus the increasing differentiation which we observe in passing from the earlier to the later geological systems is just what might have been expected4 ,summing up1 now1 the results of this rapid review of the evidence1 we seem justified in coming to the following conclusions3-- 7#a47 ,in ,palozoic times1 ,europe and ,north ,america were represented by considerable areas of dry land1 massed chiefly in the higher latitudes1 while further south groups of smaller islands were scattered over the submerged surface of the primeval continental plateau4 ,the other continents appear1 in like manner1 to have been represented by islands--some of which may have reached continental dimensions4 ,a very remarkable uniformity of climate accompanied these peculiar geographical conditions4 7#b47 ,in ,mesozoic times1 the primeval continental plateau came more and more to the surface1 but the land-areas were still much interrupted1 so that currents from tropical regions continued to have ready access to high latitudes4 ,the climate of the whole globe1 therefore1 was still uniform1 but apparently not so markedly as in the preceding era4 7#c47 ,in ,cainozoic times1 the land-masses continued to extend1 and the sea to retreat from hitherto submerged areas of the continental plateau2 and this persistent land-growth was accompanied by a gradual lowering of the temperature of northern and temperate latitudes1 and a more and more marked differentiation of climate into zones4 ,having thus very briefly sketched the geographical evolution of the land during ,palozoic1 ,mesozoic1 and ,tertiary times1 and come to the general conclusion that climate has varied according to the relative position of land and sea1 ,i have next to consider the geographical and climatic conditions of the ,quaternary period4 ,these1 however1 are now so well known1 that ,i need to no more than remind you that1 so far as the chief features of our lands are considered1 all these had come into existence before the dawn of the ,ice ,age4 ,the greater contours of the surface1 which were foreshadowed in ,palozoic times1 and which in ,mesozoic times were more clearly indicated1 had been fully evolved by the close of the ,pliocene period4 ,the connection between the ,mediterranean and the ,indian ,ocean probably ceased in late ,pliocene times4 ,the most remarkable geographical changes which have taken place since then within ,european regions have been successive elevations and depressions1 in consequence of which the area of our ,continent has been alternately increased and diminished4 ,at a time well within the human period1 our own islands have been united to themselves and the ,continent1 and the dry land has extended north-west and north1 so as to include ,spitzbergen1 the ,fare ,islands1 and perhaps ,iceland4 ,on the other hand1 our islands have been within a recent period largely submerged4 ,similarly1 in ,north ,america1 we are furnished with many proofs of like oscillations of level having taken place in ,quaternary times4 ,is it possible1 then1 to explain the climatic vicissitudes of the ,pleistocene period by means of such oscillations8 ,many geologists have tried to do so1 but all these attempts have failed4 ,it is quite true that a general elevation of the land in high latitudes would greatly increase the ice-fields of arctic regions1 and might even give rise to perennial snow and glaciers in the mountain-districts of our islands4 ,but it is inconceivable that any such geographical change could have brought about that general lowering of temperature over the whole northern hemisphere which took place in ,pleistocene times4 ,for we have to account not only for the excessive glaciation of northern and north-western ,europe1 and of the northern parts of ,north ,america1 but for the appearance of snow-fields and glaciers in much more southern latitudes1 and in many parts of ,asia where no perennial snow now exists4 ,moreover1 we have to remember that arctic conditions of climate obtained in north-western ,europe even when the land was relatively much lower than it is at present4 ,the arctic shell-beds of our own and other temperate regions sufficiently prove that geographical conditions were not the only factor concerned in bringing about the peculiar climate of the ,pleistocene period4 ,then1 again1 we must not forget that at certain stages of the same period genial conditions of climate were coincident with a much wider land-surface in north-western ,europe than now exists4 ,the very fact that interglacial deposits occur in every glaciated region is enough of itself to show that the arctic conditions of the ,pleistocene could not have resulted entirely from a mere elevation of land in the northern parts of our hemisphere4 ,the only explanation of the peculiar climatic vicissitudes in question which seems to meet the facts1 so far as these have been ascertained1 is the well-known theory advanced by ,dr4 ,croll4 ,after carefully considering all the objections which have been urged against that theory1 there is only one1 as it seems to me1 that is deserving of serious attention4 ,this objection is not based on any facts connected with the ,pleistocene deposits themselves1 but on evidence of quite another kind4 ,it is admitted that were the ,pleistocene deposits alone considered1 ,croll's theory would fully account for the phenomena4 ,but1 it is argued1 we cannot take the ,pleistocene by itself1 for if that theory be true1 then climatic conditions similar to those of the ,pleistocene must have supervened again and again during the past4 ,where1 then1 we are asked1 is there any evidence in ,palozoic1 ,mesozoic1 or ,cainozoic strata of former widespread glacial conditions8 ,if continental ice-sheets1 comparable to those of the ,pleistocene1 ever existed in the earlier ages1 surely we ought to find more or less unmistakable traces of them4 ,now1 at first sight1 this looks a very plausible objection1 but it has always seemed to me to be based upon an assumption that is not warranted by our knowledge of geographical evolution4 ,dr4 ,croll always admitted implicitly that high eccentricity of the earth's orbit might have happened again and again without inducing glacial conditions like those of the ,pleistocene4 ,the objection takes no account of the fact that the excessive climate of the ,glacial period was only possible because of special geographical conditions--conditions that do not appear to have been fully evolved before ,pliocene times4 ,no one has seen this more clearly than ,mr4 ,wallace1,,dl with the general drift of whose argument ,i am quite at one4 ,in earlier ages1 the warm water of the tropics overflowed wide areas of our present continents--most of the dry land was more or less insular1 and the seas within the ,arctic ,circle were certainly not cold as at present1 but temperate and even genial4 ,if we go back to ,cambro-,silurian times1 we find only the nuclei1 as it were1 of our existing continents appearing above the surface of widespread shallow seas4 ,it is quite impossible1 therefore1 that under such geographical conditions1 great continuous ice-sheets1 like those of the ,pleistocene1 could have existed--no matter how high the eccentricity of the earth's orbit may have been4 ,the most that could have happened during such a period of eccentricity would be the accumulation of snow-fields on mountains and plateaux of sufficient height1 the formation here and there of local glaciers1 and the descent of these in some places to the sea4 ,and what evidence of such local glaciation might we now expect to find8 ,no old land-surface of that far-distant period has come down to us3 we look in vain for ,cambro-,silurian roches moutonnes and boulder-clay or moraines4 ,the only evidence we could expect is just that which actually occurs1 namely1 erratics 7some of them measuring five feet and more in diameter7 embedded in marine deposits4 ,it may be said that a few erratics are hardly sufficient to prove that a true ,glacial period supervened in ,cambro-,silurian times1 and ,i do not insist that they are4 ,but ,i certainly maintain that if any lowering of the temperature were induced by high eccentricity of the earth's orbit during ,cambro-,silurian times1 then ice-floated erratics are the only evidence of refrigeration that we need ever hope to find4 ,the geographical conditions of early ,palozoic times forbade the formation of enormous ice-sheets like those of the ,pleistocene period4 ,extreme climatic changes were then impossible1 and periods of high eccentricity might have come and gone without inducing any modifications of flora and fauna which we could now recognise4 ,we are ignorant of the terrestrial life of the globe at that distant period1 and our knowledge of the marine fauna is not sufficient to enable us to deny the possibility of moderate fluctuations in the temperature of the seas of early ,palozoic times4 ,moreover1 we must not forget there were then no such barriers to migration as now exist4 ,if the conditions became temporarily unsuitable1 marine organisms were free to migrate into more genial waters1 and to return to their former habitats when the unfavourable conditions had passed away4 ,,dl ,see ,island ,life4 ,the uniform climate so characteristic of the ,cambro-,silurian period appears to have prevailed likewise during the later stages of the ,palozoic era4 ,this we gather from a general consideration of the floras and faunas1 and their geographical distribution4 ,the dry land1 as we have seen1 continued to increase in extent2 but vast areas of the primeval continental plateau of the globe still continued under water1 and currents from southern latitudes flowed unrestricted into polar regions4 ,during the protracted lapse of time required for the formation of the later ,palozoic systems several periods of high eccentricity must have occurred4 ,but1 so far as one can judge1 the disposition of the larger land-areas was never such as to induce a true ,ice ,age4 ,nevertheless we are not without evidence of ice-action in ,old ,red ,sandstone1 ,carboniferous1 and ,permian strata4 ,and it seems to me probable that the erratic accumulations referred to may really indicate local action1 of more or less intensity1 brought about by such lowering of the temperature as would supervene during a period of high eccentricity4 ,it is true we may explain the phenomena by inferring the existence of mountains of sufficient elevation--and this1 indeed1 is the usual explanation4 ,but it is doubtful whether those who adopt that view have fully considered what it involves4 ,take1 for example1 the case of the breccias and conglomerates of the ,lammermuir ,hills1 which have all the appearance of being glacial and fluvio-glacial detritus4 ,these deposits overlie the highly-denuded ,silurian greywacks of ,haddingtonshire in the north and of ,berwickshire in the south1 and have evidently been derived from the intervening high-grounds--the width of which between the ,old ,red ,sandstone accumulations in question does not exceed eight or nine miles4 ,the breccias reach a height of #acjj feet1 while the dominating point of the intervening uplands is #agjj feet4 ,under present geographical conditions it is doubtful whether perennial snow and glaciers of any size at all could exist in the region of the ,lammermuirs at a less altitude than #gjjj feet or more4 ,but between the breccias of ,haddingtonshire and the equivalent deposits in ,berwickshire there is no space for any intermediate range of mountains of circumdenudation of such a height4 ,moreover1 we must remember that under the extremely uniform conditions which obtained in ,palozoic times the snow-line could not possibly have been attained even at that elevation4 ,when the ,devonian coral-reefs described by ,dupont were growing in the sea that overflowed western ,europe1 to what height must the southern uplands of ,scotland have been elevated in order to reach the snow-line6 ,we may make what allowance we choose for the denudation which the ,silurian rocks of the ,lammermuirs must have experienced since the deposition of the ,old ,red ,sandstone1 but it is simply a physical impossibility that mountains of circumdenudation of the desiderated height could ever have existed in the ,lammermuir region at the time the coarse breccias were being accumulated4,,dm ,it seems to me1 then1 that these breccias are in every way better accounted for by a lowering of temperature due to increased eccentricity of the orbit4 ,this view frees us from the necessity of postulating excessive upheavals over very restricted areas1 and of creating ,alps where no ,alps could have existed4 ,,dm ,it may be objected that the conglomerates were probably not marine1 but deposited in lakes1 the beds of which may have been much above sea-level4 ,but from all that we know of the ,old ,red ,sandstone of ,scotland it would appear that the lakes of the period now and again communicated with the sea1 and were probably never much above its level4 ,when we consider the enormous thickness of the strata that constitute any of our larger coal-fields1 we can hardly doubt that one or more periods of high eccentricity must have occurred during their accumulation4 ,it does not follow1 however1 that we should be able to detect in these strata any evidence of alternating cold and warm epochs4 ,so long as ocean-currents from the tropics found ready entrance to polar regions across vast tracts of what is now dry land1 extreme and widespread glacial conditions were impossible4 ,any lowering of temperature due to cosmical causes might indeed induce new snow-fields and glaciers to appear1 or existing ones to extend themselves in northern regions and the most elevated lands of lower latitudes2 but such local glaciation need not have seriously affected any of the areas in which coal-seams were being formed4 ,for nothing appears more certain than this--that our coal-seams as a rule were formed over broad1 low-lying alluvial lands1 and in swamps and marshes1 along the margins of estuaries or shallow bays of the sea4 ,some seams1 it is true1 are evidently formed of drifted vegetable dbris1 but the majority point to growth in situ4 ,the strata with which they are associated are shallow-water sediments which could only have been deposited at some considerable distance from any mountain-regions in which glaciers were likely to exist4 ,it is idle1 therefore1 to ask for evidence of glacial action amongst strata formed under such conditions4 ,the only evidence of ice-work we are likely to get is that of erratics4 ,and these are not wanting1 although it is probable that most of those which are found embedded in coals have been transported by rafts of vegetable matter or in the roots of trees4 ,the same explanation1 however1 will not account for the boulders which ,sir ,william ,dawson has recorded from the coal-fields of ,nova ,scotia4 ,he describes them as occurring on the outside of a gigantic esker of ,carboniferous age1 and thinks they were probably dropped there by floating-ice at a time when coal-plants were flourishing in the swamps on the other side of the gravel embankment4 ,if the disposition of the land-areas in ,carboniferous times rendered such an ice-age as that of the ,pleistocene impossible--in other words1 if the effects flowing from high eccentricity of the orbit must to a large extent have been neutralised--the flora and fauna of the period can hardly be expected to yield any recognisable evidence of fluctuating climatic conditions4 ,when our winter happened in aphelion new snow-fields might have appeared1 or already existing glaciers might have increased in size2 while1 with the winter in perihelion1 the temperature in northern latitudes would doubtless be raised4 ,but the general result would simply be an alternation of warm and somewhat cooler conditions4 ,and such fluctuations of climate might readily have taken place without materially modifying2 the life of the period4 ,the breccias of the ,permian system have been described by ,ramsay as of glacial origin4 ,some geologists agree with him1 while others do not--and many have been the ingenious suggestions which these last have advanced in explanation of the phenomena4 ,some have tried to show how the stones and blocks in the breccias may have been striated without having recourse to the agency of glacier-ice1 but they cannot explain away the fact that many of the stones 7which vary in size from a few inches to three or four feet in diameter7 have travelled distances of thirty or forty miles from the parent rocks4 ,similar erratic accumulations1 which may belong to the same system or to the ,carboniferous1 occur in ,india and ,australia4 ,according to ,dr4 ,blanford1 the ,indian boulder-beds are clearly indicative of ice-action1 and he does not think that they can be explained by an assumed former elevation of the ,himalaya4 ,on the contrary1 he is of opinion that the facts are best accounted for by a general lowering of the temperature1 due probably to the action of cosmical causes4 ,daintree1 ,wilkinson1 ,r4 ,oldham1 and others who have studied the ,australian erratic beds have likewise stated their belief that these are of true glacial origin4 ,i may pass rapidly over the ,mesozoic systems1 taking note1 however1 of the fact that in them we encounter evidence of ice-action of much the same kind as that met with in ,palozoic strata4 ,while1 on the one hand1 the ,mesozoic floras and faunas bespeak climatic conditions similar to those of earlier ages1 but probably not quite so uniform2 on the other1 the occurrence of erratics in various marine accumulations is sufficient to show that now and again ice floated across seas1 the floors of which were tenanted by reef-building corals4 ,the geographical conditions continued unfavourable to the formation of extensive ice-sheets in temperate latitudes1 no matter how high the eccentricity of the orbit might have been4 ,the erratics which occur in certain ,jurassic and ,cretaceous deposits are admitted by most geologists to have been ice-borne4 ,now1 it is highly improbable that the transporting agent could have been coast-ice1 for it is hardly possible to conceive of ice forming on the surface of a sea in which flourished an abundant ,mesozoic fauna4 ,the erratics1 therefore1 seem to imply the existence in ,mesozoic times of local glaciers1 which here and there descended to the sea1 as in the north-east of ,scotland4 ,the erratics in the ,scottish ,jurassic are evidently of native origin1 and it is most improbable that those which have been met with in the ,chalk of ,england and ,france could have floated from any very great distance4 ,how1 then1 can we explain the appearance of local glaciers in these latitudes during ,mesozoic times8 ,the geographical conditions of the period could not have favoured the formation of perennial snow and ice in our area1 unless our lands were at that time much more elevated than now4 ,and this is the usual explanation4 ,it is supposed that mountains much higher than any we now possess probably existed in such regions as the ,scottish ,highlands4 ,it is easy to imagine the former existence of such mountains4 ,so long a time has elapsed since the ,jurassic period1 that the ,archan and ,palozoic areas cannot but have suffered prodigious denudation in the interval4 ,but1 when one considers how very lofty1 indeed1 those mountains must have been1 in order to reach the snow-line of ,jurassic times1 one may be excused for expressing a doubt as to whether the suggested explanation is reasonable4 ,at all events1 the phenomena are1 to say the least1 as readily explicable on the supposition that the snow-line was temporarily lowered by cosmical causes4 ,even with eccentricity at a high value1 no great ice-sheets1 indeed1 could have existed1 but local snow-fields and glaciers might have appeared in such mountain-regions as were of sufficient height4 ,and this might have happened without producing any great difference in the temperature of the sea1 or any marked modification in the distribution of life4 ,in short1 we should simply have1 as before1 an alternation of warm and somewhat cooler climates1 but nothing approaching to the glacial and interglacial epochs of the ,pleistocene4 ,these conclusions seem to me to be strongly supported by the evidence of ice-action during ,tertiary times4 ,the gigantic erratics of the ,alpine ,eocene do not appear to have been derived from the ,alps1 but rather from the ,archan area of southern ,bohemia4 ,the strata in which they occur are1 for the most part1 unfossiliferous2 they contain only fucoidal remains1 and are presumably marine4 ,how is it possible to account for the appearance of these erratics in marine deposits in central ,europe at a time when1 as evidenced by the ,eocene flora and fauna the climate was warm8 ,are we to infer the former existence of an extremely lofty range of ,bohemian ,alps which has since vanished8 ,is it not more probable that here1 too1 we have evidence of a lowering of the snow-line1 induced by cosmical causes1 which brought about the appearance of snow-fields and glaciers in a mountain-tract of much less elevation than would have been required in the absence of high eccentricity of the orbit8 ,if it be objected that such cosmical causes must have had some effect upon the distribution of life1 ,i reply that very probably they had1 although not to any extreme extent4 ,the researches of ,mr4 ,starkie ,gardner have shown that the flora of the ,english ,eocene affords distinct evidence of climatic changes4 ,but as the geographical conditions of that period precluded the possibility of extensive glaciation1 and could only1 at the most1 have induced local glaciers to appear in elevated mountain-regions1 it seems idle to cite the non-occurrence of erratics and morainic accumulations in the ,eocene of ,england and ,france as an argument against the application of ,croll's theory to the case of the erratics of the ,flysch4 ,i repeat1 then1 that under the geographical conditions of the ,eocene1 all the more obvious effects likely to have resulted from the passage of a period of high eccentricity would be the appearance of a few local glaciers1 the existence of which could have had no more influence on the climate of adjacent lowlands than is notable in similar circumstances in our own day4 ,it is absurd1 therefore1 to expect to find evidence in ,eocene strata of as strongly contrasted climates as those of the glacial and interglacial deposits of the ,pleistocene4 ,there must1 doubtless1 have been alternations of climate in our hemisphere2 but these would consist simply of passages from warm to somewhat cooler conditions--just such changes1 in fact1 as are suggested by the plants of the ,english ,eocene4 ,the evidence of ice-action in the ,miocene strata is even more striking than that of which ,i have just been speaking4 ,the often-cited case of the erratics of the ,superga near ,turin ,i need do little more than mention4 ,these erratics were undoubtedly carried by icebergs1 calved from ,alpine glaciers at a time when northern ,italy was largely submerged4 ,the erratic deposits are unfossiliferous1 and are underlaid and overlaid by fossiliferous strata1 in none of which are any erratics to be found4 ,what is the meaning of these intercalated glacial accumulations8 ,can we believe it possible that the ,miocene glaciers were enabled to reach the sea in consequence of a sudden movement of elevation1 which must have been confined to the ,alps themselves8 ,then1 if this be so1 we must go a step further1 and suppose that1 after some little time1 the ,alps were again suddenly depressed1 so that the glaciers at once ceased to reach the sea-coast4 ,for1 as ,dr4 ,croll has remarked1 had the lowering of the ,alps been effected by the slow process of denudation1 it must have taken a long course of ages to have lowered them to the extent of bringing the glacial state to a close4 ,and we should1 in such a case1 find a succession of beds indicating a more or less protracted continuance of glacial conditions1 and not one set of erratic accumulations intercalated amongst strata1 the organic remains in which are clearly suggestive of a warm climate4 ,the occurrence of erratics in the ,miocene of ,italy is all the more interesting from the fact that in the ,miocene of ,france and ,spain similar evidence of ice-action is forthcoming4 ,opponents of ,dr4 ,croll's theory have made much of ,baron ,nordenskild's statement that he could find no trace of former glacial action in any of the fossiliferous formations within the ,arctic regions4 ,he is convinced that an examination of the geognostic condition1 and an investigation of the fossil flora and fauna of the polar lands1 show no signs of a glacial era having existed in those parts before the termination of the ,miocene period4 ,well1 as we have seen1 there is no reason to believe that the geographical conditions in our hemisphere1 at any time previous to the close of the ,pliocene period1 could have induced glacial conditions comparable to those of the ,pleistocene ,ice ,age4 ,the strata referred to by ,nordenskild1 are1 for the most part1 of marine origin1 and their faunas are sufficient to show us that the ,arctic seas were formerly temperate and genial4 ,if any ice existed then1 it could only have been in the form of glaciers on elevated lands4 ,and it is quite possible that these1 during periods of high eccentricity1 may have descended to the sea and calved their icebergs2 and1 if so1 erratics may yet be found embedded here and there in the ,arctic fossiliferous formations1 although ,nordenskild failed to see them4 ,one might sail all round the ,palozoic coast-lines of ,scotland without being able to observe erratics in the strata1 and yet1 as we know1 these have been encountered in the interior of the country4 ,the wholesale scattering of erratics at any time previous to the ,pleistocene1 must have been exceptional even in arctic regions1 and consequently one is not surprised that they do not everywhere stare the observer in the face4 ,the general conclusion1 then1 to which ,i think we may reasonably come1 is simply this3--,that geological climate has been determined chiefly by geographical conditions4 ,so long as the lands of the globe were discontinuous and of relatively small extent1 warm ocean-currents reaching polar regions produced a general uniformity of temperature--the climate of the terrestrial areas being more or less markedly insular in character4 ,under these conditions1 the sea would nowhere be frozen4 ,but when the land-masses became more and more consolidated1 when owing to the growth of the continents the warm ocean-currents found less ready access to arctic regions1 then the temperature of those regions was gradually lowered1 until eventually the seas became frost-bound1 and the lands were covered with snow and ice4 ,but while the chief determining cause of climate has been the relative distribution of land and water1 it is impossible to doubt that during periods of high eccentricity of the orbit1 the climate must have been modified to a greater or less extent4 ,in our own day the geographical conditions are such that1 were eccentricity to attain a high value1 the climate of the ,pleistocene would be reproduced1 and our hemisphere would experience a succession of alternating cold and genial epochs4 ,but in earlier stages of the world's history1 the geographical conditions were not of a kind to favour the accumulation of vast ice-fields4 ,during a period of extreme eccentricity1 there would probably be fluctuations of temperature in high latitudes2 but nothing like the glacial and interglacial epochs of the ,pleistocene could have occurred4 ,at most1 there would be a general lowering of the temperature1 sufficient to render the climate of arctic seas and lands somewhat cooler1 and probably to induce the appearance in suitable places of local glaciers2 and1 owing to precession of the equinox1 these cooler conditions would be followed by a general elevation of the temperature above the normal for the geographical conditions of the period4 ,in ,palozoic and ,mesozoic times1 the effects of high eccentricity of the orbit appear to have been1 in a great measure1 neutralised by the geographical conditions1 with a possible exception in the ,permian period4 ,but in ,tertiary times1 when the land-masses had become more continuous1 the cosmical causes of change referred to must have had greater influence4 ,and ,i cannot help agreeing with ,dr4 ,croll that the warm climates of the ,arctic regions during that era were1 to some extent1 the result of high eccentricity4 ,in concluding this discussion1 ,i readily admit that our knowledge of geographical evolution is as yet in its infancy4 ,we have still very much to learn1 and no one will venture to dogmatise upon the subject4 ,but ,i hope ,i have made it clear that the evidence1 so far as it goes1 does not justify the confident assertions of ,dr4 ,croll's opponents1 that his theory is contradicted by what we know of the climatic conditions of ,palozoic1 ,mesozoic1 and ,cainozoic times4 ,on the contrary1 it seems to me to gain additional support from the very evidence to which ,nordenskild and others have appealed4 ,note4--,the accompanying sketch-maps 7,plate ,,iv47 require a few words of explanation4 ,the geology of the world is still so imperfectly known that any attempt at graphic representation of former geographical conditions cannot but be unsatisfactory4 ,the approximate positions of the chief areas of predominant elevation and depression during stated periods of the past may have been ascertained in a general way2 but when we try to indicate these upon a map1 such provisional reconstructions are apt to suggest a more precise and definite knowledge than is at present attainable4 ,for it must be confessed that there is hardly a line upon the small maps 7,a1 ,b1 ,c7 which might not have been drawn differently4 ,this1 of course1 is more especially true of ,south ,america1 ,africa1 ,asia--of large areas of which the geological structure is unknown4 ,but although the boundaries of the land-masses shown upon the maps referred to are thus confessedly provisional1 the maps nevertheless bring out the main fact of a gradual growth and consolidation of the land-areas--a passage from insular to continental conditions4 ,i need hardly say this is no novel idea4 ,it was clearly set forth by ,professor ,dana upwards of forty years ago 7,silliman's ,journal1 #ahdf1 p4 #ceb2 #ahdg1 pp4 #agf1 #cha71 and it received some years later further illustration from ,professor ,guyot1 who insisted upon the insular character of the climate during ,palozoic times 7,the ,earth and ,man1 #ahej74 ,it must be understood that the maps 7,a1 ,b1 ,c7 are not meant to exhibit the geographical conditions of the world at any one point of time4 ,in ,map ,a1 for example1 the area coloured blue was not necessarily covered by sea at any particular stage in the ,palozoic era4 ,it simply represents approximately the regions tended4 ,but1 as already stated1 numerous oscillations of level occurred in ,palozoic times1 so that many changes in the distribution of land and water must have taken place down to the close of the ,permian period4 ,the land-areas shown upon the map are simply those which appear to have been more or less persistent through all the geographical changes referred to4 ,similar remarks apply to the other maps representing the more or less persistent land-areas of ,mesozoic and ,tertiary times4 ,thus1 for example1 there are reasons for believing that ,madagascar was joined to the mainland of ,africa at some stage of the ,mesozoic era1 but was subsequently insulated before ,tertiary times4 ,again1 as ,mesozoic era a land-connection obtained between ,new ,zealand and ,australia4 ,the same naturalist also points out that a chain of islands1 now represented by numerous islets and shoals1 served in ,tertiary times to link ,madagascar to ,india4 ,map ,d shows the areas of predominant elevation and depression4 ,the area coloured brown represents the great continental plateau1 which extends downwards to #ajjj fathoms or so below the present sea-level4 ,the area tinted blue is the oceanic depression4 ,from the present distribution of plants and animals1 we infer that considerable tracts which are now submerged have formerly been dry land--some of these changes having taken place in very recent geological times4 ,and the same conclusions are frequently suggested by geological evidence4 ,there can be little doubt that ,europe in ,tertiary times extended further into the ,northern ,ocean than it does now4 ,and it is quite possible that in the ,mesozoic and ,palozoic eras considerable land-areas may likewise have appeared here and there in those northern regions which are at present under water4 ,there is1 indeed1 hardly any portion of the continental plateau which is now submerged that may not have been land at some time or other4 ,but after making all allowance for such possibilities1 the geological evidence1 as far as it goes1 nevertheless leads to the conclusion that upon the whole a wider expense of primeval continental plateau has come to the surface since ,tertiary times than was ever exposed during any former period of the world's history4 ,mr4 ,marcou states 7,american ,geologist1 #ahij1 p4 #bbi7 that the idea of a gradual growth of land-areas originated with ,elie de ,beaumont1 who was in the habit of showing such maps1 and used them in his lectures at ,paris as early as #ahcf4 ,professor ,beudant published three of these same maps for the ,jurassic1 ,cretaceous1 and ,tertiary seas in his ,cours lmentaire de ,gologie 7#ahda72 and ,professor ,carl ,vogt in his ,lehrbuch der ,geologie und ,petrefactenkunde 7#ahde71 which was confessedly based on ,elie de ,beaumont's lectures during #ahdd-df1 gives four maps of the ,carboniferous1 ,jurassic1 ,cretaceous1 and ,tertiary seas4 ,,xiii4 ,the ,scientific ,results of ,dr4 ,nansen's ,expedition4,,dn ,,dn ,from ,the ,scottish ,geographical ,magazine1 #ahia4 ,in the ,appendix to his most interesting and instructive work1 ,the ,first ,crossing of ,greenland1 ,dr4 ,nansen treats of the scientific results of his remarkable journey4 ,the detailed enumeration of these results1 he tells us1 would have been out of place in a general account of his expedition1 but will appear in due time elsewhere4 ,hence he confines attention in his present work to such questions as are of most obvious interest1 such as the extent1 outward form1 and elevation of the inland-ice of ,greenland4 ,by way of introduction his readers are presented with some account of the geological history of the country1 which1 although it contains nothing that was not already familiar to geologists1 will doubtless prove interesting to others4 ,after indicating that ,greenland would appear to be composed almost exclusively of ,archan schists and granitoid eruptive rocks1 the author glances at the evidence which the ,mesozoic and ,cainozoic strata of the west coast have supplied as to the former prevalence of genial climatic conditions4 ,heer is cited to show that during the formation of the ,cretaceous beds the mean temperature of north ,greenland was probably between #gj and #gb ,f41 while in later ,cainozoic times it could not have been less than #ee ,f41 in #gj ,n4,l4 ,these conclusions are based on the character of the fossil floras4 ,now the mean annual temperature on the west coast of ,greenland1 where the relics of these old floras occur1 is about #ae ,f41 from which it is inferred that there has been a decrease of #dj since ,cainozoic times4 ,in those times1 says ,dr4 ,nansen1 the country must have rejoiced in a climate similar to that of ,naples1 while in the earlier ,cretaceous period it must have resembled that of ,egypt4 ,he then refers to the well-known fact that1 long after the deposition of the ,cainozoic beds of ,greenland1 intensely arctic conditions supervened1 when the inland-ice of that country extended much beyond its present limits4 ,this was the ,glacial period of geologists1 during which all the northern regions of ,america and ,europe1 down to what are now temperate latitudes were likewise swathed in ice4 ,various hypotheses have been advanced in explanation of these strange climatic vicissitudes1 and some of them are very briefly discussed by ,dr4 ,nansen4 ,none of the suggested solutions of the problem quite satisfies him2 but he appears to look with most favour on the view that great climatic revolutions in what are now polar regions may have resulted from movements of the earth's axis4 ,he admits1 however1 that there are certain strong objections to this hypothesis1 and concludes that we have not yet got any satisfactory explanation to cover all the facts of the case4 ,in discussing the question of a possible wandering of the pole1 the author cites certain astronomical observations to show that the position of the axis is even now slowly changing1 the movement amounting to half a second in six months4 ,this is not much2 but if the change1 as he remarks1 were to continue at the same rate for #cfjj years1 the shift would amount to one degree4 ,thus in a period of no more than #gb1jjj to #ajh1jjj years ,greenland might be brought into the latitude required for the growth of such floras as those of ,cainozoic and ,mesozoic times4 ,geologists will readily concede these or longer periods if they be required1 but they will have graver doubts than ,dr4 ,nansen as to whether any such great changes in the axis are possible4 ,the astronomical observations referred to1 even if they were fully confirmed1 do not show that the movement is constant in one direction4 ,they indicated1 as he mentions1 a slight increase of latitude during the first quarter of #ahhi1 followed in the second quarter of the same year by a decrease1 which continued to ,january1 #ahij4 ,since the publication of ,professor ,george ,darwin's masterly paper on the influence of geological changes on the earth's axis of rotation1 geologists have felt assured that the great climatic revolutions to which the stratified rocks bear witness must be otherwise explained than by a wandering of the pole4 ,indeed1 the geological evidence alone is enough to show that profound climatic changes have taken place while the pole has occupied its present position4 ,thus1 there is no reasonable grounds for doubting that during the ,glacial period the pole was just where we find it to-day4 ,for1 under existing geographical conditions1 could a sufficient lowering of temperature be brought about1 snow-fields and ice-sheets would gather and increase over the very same areas as we know were glaciated in ,pleistocene times4 ,still further1 we have only to recall the fact that several extreme revolutions of climate supervened during the so-called ,glacial period1 to see how impossible it is to account for the phenomena by movements of the earth's axis4 ,if it be true that the great climatic changes of the ,pleistocene period did not result from a wandering to and fro of the pole1 then it is not at all likely that the ,mesozoic and ,cainozoic climates of ,greenland were induced by any such movement4 ,but does the geological evidence justify us in believing that the climates in ,greenland during ,cretaceous and ,tertiary times really resembled those of ,egypt and southern ,italy8 ,it may be strongly doubted if it does4 ,palontologists1 like other mortals1 find it hard to escape the influence of environment4 ,they are apt to project the actual present into the past1 without1 perhaps1 fully considering how far they are justified in doing so4 ,because there occur in ,cretaceous and ,tertiary strata1 within ,arctic regions1 certain assemblages of plants which find their nearest representatives in southern ,italy and ,egypt1 surely it is rather rash to conclude that ,greenland has experienced climates like those now characteristic of ,mediterranean lands4 ,all that the evidence really entitles us to assume is simply that the winter temperature of ,greenland was formerly much higher than it is now4 ,that great caution is required in comparing past with present climatological conditions may be seen by glancing for a moment at the character of the flora which lived in ,europe during the interglacial phase of the ,pleistocene period4 ,the plants of that period are for the most part living species1 so that while dealing with these we are on safer ground than when we are treating of the floras of periods so far removed from us as those of ,tertiary and ,cretaceous times4 ,now1 in the ,pleistocene flora of ,europe we find a strange commingling of species1 such as we nowhere see to-day over any equally wide area of the earth's surface4 ,during ,pleistocene times many plants which are still indigenous to southern ,france flourished side by side in that area with species which are no longer seen in the same region2 some of these last having retreated because unable to support the cold of winter1 while others have retired to the mountains to escape the dryness of the summer4 ,similar evidence is forthcoming from the ,pleistocene accumulations of ,italy1 northern ,france1 and ,germany4 ,in a word1 clement winters and relatively cool and humid summers permitted the wide diffusion and intimate association of plants which have now a very different distribution1 temperate and southern species formerly flourishing together over vast areas of southern and central ,europe4 ,and similarly we find that during the same period the regions in question were tenanted by southern and temperate forms of animal life--elephants1 rhinoceroses1 and hippopotamuses1 together with cervine1 bovine1 and other forms1 not a few of which are still indigenous to our ,continent--that ranged from the shores of the ,mediterranean up to our own latitudes4 ,we cannot doubt1 indeed1 that the present geographical distribution of plants and animals differs markedly from anything that has yet been disclosed by the researches of geologists4 ,the climatic conditions of our day are exceptional as compared with those of earlier times1 and the occurrence in ,greenland of southern types of plants1 therefore1 does not justify us in concluding that climates like those of southern ,italy and ,egypt were ever characteristic of arctic regions4 ,it is a low winter temperature rather than a want of great summer heat that restricts the range northward of southern floras4 ,if ,greenland could be divested of its inland-ice--if its winter temperature never fell below that of our own island--it would doubtless become clothed in time with an abundant temperate flora4 ,judging from what is known of the various floras and faunas that have successively clothed and peopled the world1 from ,palozoic down to the close of ,cainozoic times1 the general climatic conditions of the globe1 prior to the ,glacial period1 would seem to have been prevalently insular rather than continental as they are now4 ,the lands appear to have been formerly much less continuous1 and ocean currents from southern latitudes had consequently freer access to high northern regions than is at present possible4 ,in no other way can we account for the facts connected with the geographical distribution and extent of the fossiliferous formations4 ,but are we to infer1 from the occurrence of similar assemblages of marine organic remains in arctic1 temperate1 and tropical latitudes1 that the shores of primeval ,greenland were washed by waters as warm as those of the tropics8 ,surely not3 an absence of very cold water in the far north is all that we seem justified in assuming4 ,and so1 in like manner1 the presence in ,greenland of fossil floras having the same general facies as those that occur in the corresponding strata of more southern latitudes1 does not compel us to believe that conditions at all similar to what are now met with in warm-temperate and sub-tropical lands ever obtained in arctic regions4 ,a relatively high winter temperature alone would permit the range northward of many tribes of plants which are now restricted to southern latitudes4 ,yet1 under the most uniform insular climatic conditions that we can conceive of1 there must always have been differences due to latitude--although such differences were never apparently so marked as they are now4 ,in order to appreciate the character of the climate which must have prevailed when the lands of the globe were much more interrupted and insular than at present1 we have only to consider how greatly isothermal lines1 even under existing continental conditions1 are deflected by ocean-currents4 ,in the ,north ,atlantic1 for example1 the winter isotherm of #cb ,f4 is deflected northward from the parallel of ,new ,york to that of ,hammerfest--a displacement of at least #cj of latitude4 ,the ,arctic ,sea now occupies a partially closed basin1 into which only one considerable current enters from the south4 ,but in earlier ages the case was otherwise1 and there was often communication across what are now our continental areas4 ,instead of being girdled1 as at present1 by an almost continuous land-mass1 the ,arctic ,sea seems to have formed with the circumjacent ocean one great archipelago4 ,thus freely open to the influx of southern currents1 it is not difficult to believe that the seas of the far north might never be frozen1 and that an inland-ice like that of ,greenland would be impossible4 ,the present cold summers of that country1 as the late ,dr4 ,croll has insisted1 are due not so much to high latitude as to the presence of snow and ice4 ,could these be removed1 the summers would be as warm at least as those of ,england4 ,now the occurrence in arctic regions of ,palozoic and ,mesozoic marine faunas is strongly suggestive of the former presence there of genial waters having free communication with lower latitudes2 and it is to the presence of these warm currents1 flowing uninterruptedly through polar regions1 that we would attribute the high winter temperature and uniform climate to which the fossil floras and faunas of ,greenland bear testimony4 ,if these views be at all reasonable1 it seems unnecessary to call to our aid hypothetical changes in the position of the earth's axis4 ,it may be admitted1 however1 that the climate of the ,arctic regions must have been from time to time more or less affected by those cosmical causes to which ,croll has appealed4 ,so long1 however1 as insular conditions prevailed1 the changes induced by a great increase in the eccentricity of the earth's orbit would not necessarily be strongly marked4 ,dr4 ,nansen objects to ,croll's well-known theory that it cannot account for the recurrence of conditions so favourable as to explain the existence in ,greenland of a climate comparable to what we now find in tropical regions4 ,no doubt it cannot1 but1 as we maintain1 there is no good reason for supposing that tropical or sub-tropical climates ever characterised any area within the ,arctic ,circle4 ,the remarkable association in ,europe1 during so recent a period as the ,pleistocene1 of southern and temperate species of plants and animals1 ought to warn us against taking the present distribution of life-forms as an exact type of the kind of distribution which characterised earlier ages4 ,it is safe to say that were our present continental areas to become broken up into groups of larger and smaller islands1 so as to allow of a much less impeded oceanic circulation1 the resulting climatic conditions would offer the strongest contrast to the present4 ,and as the lands of the globe were apparently in former times more insular than they are now1 it is hazardous to compare the climates of the present with those of the past4 ,it is reasonable to infer1 from the occurrence in ,greenland of fossil floras which find their nearest representatives in southern ,europe and north ,africa1 that the winters of the far north were formerly mild and clement4 ,but we cannot conclude1 from the same evidence1 that the ,arctic summers were ever as hot as those of our present warm-temperate and sub-tropical zones4 ,but if the recent expedition has thrown no new light on the disputed question as to the cause of the high temperature which formerly prevailed in ,greenland1 it is needless to say that it has added considerably to our knowledge of the present physical conditions of that country4 ,the view held by many that ,greenland must be wrapped in ice has been amply justified1 and we can now no longer doubt that the inland-ice covers the whole country from the #geth parallel southwards4 ,a section of ,greenland in the latitude at which it was crossed by ,nansen and his comrades gives an almost exact mathematical curve1 approximating very closely to the arc of a circle described with a radius of about #fejj miles4 ,the whole way across the surface coincides tolerably accurately with this arc1 though it falls away somewhat abruptly at the coasts1 and a little more abruptly on the east side than the west4 ,taking the observations of other ,arctic travellers with his own1 ,nansen is led to the conclusion that the surface of the inland-ice forms part of a remarkably regular cylinder1 the radius of which nevertheless varies not a little at different latitudes1 increasing markedly from the south1 and consequently making the arc of the surface flatter and flatter as it advances northwards4 ,he points out that this remarkable configuration must to a certain extent be independent of the form of the underlying land-surface1 which1 to judge from the character of the wild and mountainous coast-lands1 probably resembles ,norway in its general configuration--if1 indeed it be not a group of mountainous islands4 ,the buried interior of ,greenland must in fact be a region of high mountains and deep valleys1 all of which have totally disappeared under the enveloping mer de glace4 ,it is obvious1 as ,dr4 ,nansen remarks1 that the minor irregularities of the land have had no influence whatever upon the form of the upper surface of the ice-sheet4 ,that surface-form has simply been determined by the force of pressure--the quasi-viscous mass attaining its maximum thickness towards the central line of the country1 where resistance to the movement due to pressure must necessarily have been greatest4 ,thus although the larger features of the ice-drowned land may have had some influence in determining the position of the ice-shed1 it is not by any means certain that this central line coincides with the dominant ridge or watershed of the land itself4 ,for1 as ,nansen reminds us1 the ice-shed of the ,scandinavian inland-ice of glacial times certainly lay about #ajj miles to the east of the main water-parting of ,norway and ,sweden4 ,similar facts1 we may add1 have been noticed in connection with the old ice-sheets of ,scotland and ,ireland4 ,the greatest elevation attained by the expedition was #ijjj feet4 ,how deeply buried the dominating parts of the land-surface may be at that elevation one cannot tell4 ,it is obvious1 however1 that the mer de glace must be very unequal in thickness4 ,according to ,dr4 ,nansen the average elevation of the valleys in the interior cannot much exceed #bcjj or #ccjj feet1 so that the ice lying above such depressions must have a thickness of #egjj to #fgjj feet4 ,it cannot1 of course1 lie so deeply over mountain-ridges4 ,the eroding power of such a glacier-mass must be enormous1 and ,dr4 ,nansen does not doubt that the buried valleys of ,greenland are being widened and deepened by the grinding of the great ice-streams that are ever advancing towards the sea4 ,the expedition met with no streams of surface-water on the inland-ice2 indeed1 the amount of superficial melting in the interior was quite insignificant4 ,and yet1 as is well known1 many considerable streams and rivers flow out from underneath the inland-ice all the year round4 ,it is obvious1 therefore1 that this water-supply does not come from superficial sources1 as1 according to ,dr4 ,nansen1 it is usually supposed to do4 ,but surely it has long been recognised that such rivers as the ,mary ,minturn must be derived from sub-glacial melting4 ,and the various causes to which our author attributes this melting have already frequently been pointed out4 ,earth-heat--the influence of pressure in lowering the melting-point of ice--and the friction induced by the movement of the ice itself have all long ago been recognised as factors tending to produce the sub-glacial water-drainage of an ice-sheet4 ,dr4 ,nansen's speculations on the origin of the drumlins and kames of formerly glaciated areas will interest geologists1 but are not so novel as he supposes4 ,his description of what are known as drumlins is not quite correct4 ,these long lenticular banks cannot be said to lie upon boulder-clay1 but are merely a structural form of that accumulation4 ,and it is hardly the case that geologists have performed the most acrobatic feats in trying to explain the origin of the banks in question4 ,the usual explanation is that they have been formed underneath the ice as ground-moraine--the upper surface of which varies in configuration--being sometimes approximately even1 as in broad mountain-valleys2 at other times ridged and corrugated1 as in open lowlands4 ,and these modifications of surface are supposed to have resulted from the varying movement and pressure of the overlying ice-sheet4 ,the drumlins1 in fact1 would appear to be analogous to the banks that accumulate in the beds of rivers4 ,many drumlins1 indeed1 are composed partly of solid rock and partly of boulder-clay1 which would seem to have accumulated in the lee of the projecting rock1 much in the same way as gravel and sand gather behind any large boulder in a stream-course4 ,dr4 ,nansen1 apparently1 to some extent confounds drumlins with kames and sar1 of which certainly many strange and conflicting explanations have been hazarded4 ,these1 however1 differ essentially from drumlins1 for they consist exclusively1 or almost exclusively1 of water-worn and more or less water-assorted materials4 ,and one widely-accepted view of their origin is that they have accumulated in tunnels underneath an ice-sheet4 ,this is practically the same view as ,dr4 ,nansen's4 ,he thinks that when an ice-sheet has its under-surface furrowed by running water1 the ground-moraine will tend to be pressed up into the river-channels4 ,the water will1 in this way1 be compelled to hollow out the roof of its tunnel to a greater degree1 and as the stream continues to work upwards the moraine will follow it1 so as to partially fill the tunnel and form a ridge along the back of which the sub-glacial stream will run4 ,the material forming the upper portion of the ridge will thus come to be composed mainly of water-worn and stratified detritus1 derived from the erosion of the ground-moraine4 ,this is an ingenious suggestion which may be of good service in some cases1 but it is certainly inapplicable to most kames and sar4 ,if it were a complete explanation we ought to find these ridges consisting of an upper water-assorted portion and a lower unmodified morainic portion 7boulder-clay74 ,but this is not the case1 for most kames consist entirely1 from top to bottom1 of water-assorted materials4 ,they are found running across an even or gently-undulating surface of boulder-clay1 and sometimes they rest not on boulder-clay but solid rock4 ,dr4 ,nansen considers another geological question which has given rise to much controversy1 and is still far from being settled--namely1 whether the oscillations of level which have left such conspicuous traces in northern regions are in any way connected with the appearance and disappearance of great ice-sheets4 ,can a big ice-sheet push down the earth's crust by its weight8 and does the crust rise again as the ice melts away8 ,could a thick ice-sheet exercise sufficient attraction upon the sea to cause it to rise upon the land1 and thus explain the origin of some of the so-called raised beaches of this and other formerly glaciated lands8 ,can the weight of a great ice-sheet shift the earth's centre of gravity1 and1 if so1 to what extent8 ,each of these questions has been answered in the affirmative and the negative by controversialists1 and1 until the geological evidence has been completely sifted1 each1 doubtless1 will continue to be alternately affirmed and denied4 ,all that need be pointed out here is that some of the movements which occurred during the ,pleistocene period were on much too large a scale to be explicable by any of the hypotheses referred to4 ,,xiv4 ,the ,geographical ,development of ,coast-lines4,,do ,,do ,presidential ,address to the ,geographical ,section of the ,british ,association1 ,edinburgh1 #ahib4 ,amongst the many questions upon which of late years light has been thrown by deep-sea exploration and geological research1 not the least interesting is that of the geographical development of coast-lines4 ,how is the existing distribution of land and water to be accounted for8 ,are the revolutions in the relative position of land and sea1 to which the geological record bears witness1 due to movements of the earth's crust or of the hydrosphere8 ,why are coast-lines in some regions extremely regular1 while elsewhere they are much indented8 ,about #aej years ago the prevalent belief was that ancient sea-margins indicated a formerly higher ocean-level4 ,such was the view held by ,celsius1 who1 from an examination of the coast-lands of ,sweden1 attributed the retreat of the sea to a gradual drying up of the latter4 ,but this desiccation hypothesis was not accepted by ,playfair1 who thought it much more likely that the land had risen4 ,it was not1 however1 until after ,von ,buch had visited ,sweden 7#ahjf-ahjh71 and published the results of his observations1 that ,playfair's suggestion received much consideration4 ,von ,buch concluded that the apparent retreat of the sea was not due to a general depression of the ocean-level1 but to elevation of the land--a conclusion which subsequently obtained the strong support of ,lyell4 ,the authority of these celebrated men gained for the elevation theory more or less complete assent1 and for many years it has been the orthodox belief of geologists that the ancient sea-margins of ,sweden and other lands have resulted from vertical movements of the crust4 ,it has long been admitted1 however1 that highly-flexed and disturbed strata require some other explanation4 ,obviously such structures are the result of lateral compression and crumpling4 ,hence geologists have maintained that the mysterious subterranean forces have affected the crust in different ways4 ,mountain-ranges1 they conceive1 are ridged up by tangential thrusts and compression1 while vast continental areas slowly rise and fall1 with little or no disturbance of the strata4 ,from this point of view it is the lithosphere that is unstable1 all changes in the relative level of land and sea being due to crustal movements4 ,of late years1 however1 ,trautschold and others have begun to doubt whether this theory is wholly true1 and to maintain that the sea-level may have changed without reference to movements of the lithosphere4 ,thus ,hilber has suggested that sinking of the sea-level may be due1 in part at least1 to absorption1 while ,schmick believes that the apparent elevation and depression of continental areas are really the results of grand secular movements of the ocean4 ,the sea1 according to him1 periodically attains a high level in each hemisphere alternately1 the waters being at present heaped up in the southern hemisphere4 ,professor ,suess1 again1 believing that in equatorial regions the sea is1 on the whole1 gaining on the land1 while in other latitudes the reverse would appear to be the case1 points out this is in harmony with his view of a periodical flux and reflux of the ocean between the equator and the poles4 ,he thinks we have no evidence of any vertical elevation affecting wide areas1 and that the only movements of elevation that take place are those by which mountains are upheaved4 ,the broad invasions and transgressions of the continental areas by the sea1 which we know have occurred again and again1 are attributed by him to secular movements of the hydrosphere itself4 ,apart from all hypothesis and theory1 we learn that the surface of the sea is not exactly spheroidal4 ,it reaches a higher level on the borders of the continents than in mid-ocean1 and it varies likewise in height at different places on the same coast4 ,the attraction of the ,himalaya1 for example1 suffices to cause a difference of #cjj feet between the level of the sea at the delta of the ,indus and on the coast of ,ceylon4 ,the recognition of such facts has led ,penck to suggest that the submergence of the maritime regions of north-west ,europe and the opposite coasts of ,north ,america1 which took place at a recent geological date1 and from which the lands in question have only partially recovered1 may have been brought about by the attraction exerted by the vast ice-sheets of the ,glacial period4 ,but1 as ,drygalski1 ,woodward1 and others have shown1 the heights at which recent marine deposits occur in the regions referred to are much too great to be accounted for by any possible distortion of the hydrosphere4 ,the late ,james ,croll had previously endeavoured to show that the accumulation of ice over northern lands during glacial times would suffice to displace the earth's centre of gravity1 and thus cause the sea to rise upon the glaciated tracts4 ,more recently other views have been advanced to explain the apparently causal connection between glaciation and submergence1 but these need not be considered here4 ,whatever degree of importance may attach to the various hypotheses of secular movements of the sea1 it is obvious that the general trends of the world's coast-lines are determined in the first place by the position of the dominant wrinkles of the lithosphere4 ,even if we concede that all raised beaches1 so-called1 are not necessarily the result of earth-movements1 and that the frequent transgressions of the continental areas by oceanic waters in geological times may possibly have been due to independent movements of the sea1 still we must admit that the solid crust of the globe has always been subject to distortion4 ,and this being so1 we cannot doubt that the general trends of the world's coast-lines must have been modified from time to time by movements of the lithosphere4 ,as geographers we are not immediately concerned with the mode of origin of those vast wrinkles1 nor need we speculate on the causes which may have determined their direction4 ,it seems1 however1 to be the general opinion that the configuration of the lithosphere is due simply to the sinking-in and doubling-up of the crust on the cooling and contracting nucleus4 ,but it must be admitted that neither physicists nor geologists are prepared with a satisfactory hypothesis to account for the prominent trends of the great world-ridges and troughs4 ,according to the late ,professor ,alexander ,winchell1 these trends may have been the result of primitive tidal action4 ,he was of opinion that the transmeridional progress of the tidal swell in early incrustive times on our planet would give the forming crust structural characteristics and aptitudes trending from north to south4 ,the earliest wrinkles to come into existence1 therefore1 would be meridional or submeridional1 and such1 certainly1 is the prevalent direction of the most conspicuous earth-features4 ,there are many terrestrial trends1 however1 as ,professor ,winchell knew1 which do not conform to the requirements of his hypothesis2 but such transmeridional features1 he thought1 could generally be shown to be of later origin than the others4 ,this is the only speculation1 so far as ,i know1 which attempts1 perhaps not altogether unsuccessfully1 to explain the origin of the main trends of terrestrial features4 ,according to other authorities1 however1 the area of the earth's crust occupied by the ocean is denser than that over which the continental regions are spread4 ,the depressed denser part balances the lighter elevated portion4 ,but why these regions of different densities should be so distributed no one has yet told us4 ,neither does ,le ,conte's view1 that the continental areas and the oceanic depressions owe their origin to unequal radial contraction of the earth in its secular cooling1 help us to understand why the larger features of the globe should be disposed as they are4 ,geographers must for the present be content to take the world as they find it4 ,what we do know is that our lands are distributed over the surface of a great continental plateau of irregular form1 the bounding slopes of which plunge down more or less steeply into a vast oceanic depression4 ,so far as geological research has gone1 there is reason to believe that these elevated and depressed areas are of primeval antiquity--that they ante-date the very oldest of the sedimentary formations4 ,there is abundant evidence1 however1 to show that the relatively elevated or continental area has been again and again irregularly submerged under tolerably deep and wide seas4 ,but all historical geology seems to assure us that the continental plateau and the oceanic hollows have never changed places1 although from time to time portions of the latter have been ridged up and added to the margins of the former1 while ever and anon marginal portions of the plateau have sunk to very considerable depths4 ,we may thus speak of the great world-ridges as regions of dominant elevation1 and of the profound oceanic troughs as areas of more or less persistent depression4 ,from one point of view1 it is true1 no part of the earth's surface can be looked upon as a region of dominant elevation4 ,our globe is a cooling and contracting body1 and depression must always be the prevailing movement of the lithosphere4 ,the elevation of the continental plateau is thus only relative4 ,could we conceive the crust throughout the deeper portions of the oceanic depression to subside to still greater depths1 while at the same time the continental plateau remained stationary1 or subsided more slowly1 the sea would necessarily retreat from the land1 and the latter would then appear to rise4 ,it is improbable1 however1 that any extensive subsidence of the crust under the ocean could take place without accompanying disturbance of the continental plateau2 and in this case the latter might experience in places not only negative but positive elevation4 ,during the evolution of our continents1 crustal movements have again and again disturbed the relative level of land and sea2 but since the general result has been to increase the land-surface and to contract the area occupied by the sea1 it is convenient to speak of the former as the region of dominant elevation1 and of the latter as that of prevalent depression4 ,properly speaking1 both are sinking regions1 the rate of subsidence within the oceanic trough being in excess of that experienced over the continental plateau4 ,the question of the geographical development of coast-lines is therefore only that of the dry lands themselves4 ,the greater land-masses are all situated upon1 but are nowhere co-extensive with1 the area of dominant elevation1 for very considerable portions of the continental plateau are still covered by the sea4 ,opinions may differ as to which fathoms-line we should take as marking approximately the boundary between that region and the oceanic depression2 and it is obvious1 indeed1 that any line selected must be arbitrary and more or less misleading1 for it is quite certain that the true boundary of the continental plateau cannot lie parallel to the surface of the ocean4 ,in some regions it approaches within a few hundreds of fathoms of the sea-level2 in other places it sinks for considerably more than #ajjj fathoms below that level4 ,thus1 while a very moderate elevation would in certain latitudes cause the land to extend to the edge of the plateau1 an elevation of at least #aj1jjj feet would be required in some other places to bring about a similar result4 ,although it is true that the land-surface is nowhere co-extensive with the great plateau1 yet the existing coast-lines may be said to trend in the same general direction as its margins4 ,so abruptly does the continental plateau rise from the oceanic trough1 that a depression of the sea-level1 or an elevation of the plateau1 for #aj1jjj feet1 would add only a narrow belt to the ,pacific coast between ,alaska and ,cape ,horn1 while the gain of land on the ,atlantic slope of ,america between #cj ,n4,l4 and #dj ,s4,l4 would not be much greater4 ,in the higher latitudes of the northern hemisphere1 however1 very considerable geographical changes would be accomplished by a much less amount of elevation of the plateau4 ,were the continental plateau to be upheaved for #cjjj feet1 the major portion of the ,arctic ,sea would become land4 ,thus1 in general terms1 we may say that the coast-lines of arctic and temperate ,north ,america and ,eurasia are further withdrawn from the edge of the continental plateau than those of lower latitudes4 ,in regions where existing coast-lines approach the margin of the plateau1 they are apt to run for long distances in one determinate direction1 and1 whether the coastal area be high or not1 to show a gentle sinuosity4 ,their course is seldom interrupted by bold projecting headlands or peninsulas1 or by intruding inlets1 while fringing or marginal islands rarely occur4 ,to these appearances the northern regions1 as every one knows1 offer the strongest contrast4 ,not only do they trend irregularly1 but their continuity is constantly interrupted by promontories and peninsulas1 by inlets and fiords1 while fringing islands abound4 ,but an elevation of some #djj or #ejj fathoms only would revolutionise the geography of those regions1 and confer upon the northern coast-lines of the world the regularity which at present characterises those of western ,africa4 ,it is obvious1 therefore1 that the coast-lines of such lands as ,africa owe their regularity primarily to their approximate coincidence with the steep boundary-slopes of the continental plateau1 while the irregularities characteristic of the coast-line of north-western ,europe and the corresponding latitudes of ,north ,america are determined by the superficial configuration of the same plateau1 which in those regions is relatively more depressed4 ,i have spoken of the general contrast between high and low northern latitudes2 but it is needless to say that in southern regions the coast-lines exhibit similar contrasts4 ,the regular coast-lines of ,africa and ,south ,america have already been referred to2 but we cannot fail to recognise in the much-indented sea-board and the numerous coastal islands of southern ,chile a complete analogy to the fiord regions of high northern latitudes4 ,both are areas of comparatively recent depression4 ,again1 the manifold irregularities of the coasts of south-eastern ,asia1 and the multitudes of islands that serve to link that continent to ,australia and ,new ,zealand1 are all evidence that the surface of the continental plateau in those regions is extensively invaded by the sea4 ,a word or two now as to the configuration of the oceanic trough4 ,there can be no doubt that this differs very considerably from that of the land-surface4 ,it is1 upon the whole1 flat or gently-undulating4 ,here and there it swells gently upwards into broad elevated banks1 some of which have been traced for great distances4 ,in other places narrower ridges and abrupt mountain-like elevations diversify its surface1 and project again and again above the level of the sea1 to form the numerous islets of ,oceania4 ,once more1 the sounding-line has made us acquainted with the notable fact that numerous deep depressions--some long and narrow1 others relatively short and broad--stud the floor of the great trough4 ,i shall have occasion to refer again to these remarkable depressions1 and need at present only call attention to the fact that they are especially well-developed in the region of the western ,pacific1 where the floor of the sea1 at the base of the bounding slopes of the continental plateau1 sinks in places to depths of three and even of five miles below the existing coast-lines4 ,one may further note the fact that the deepest areas of the ,atlantic are met with in like manner close to the walls of the plateau--a long ridge1 which rises midway between the continents and runs in the same general direction as their coast-lines1 serving to divide the trough of the ,atlantic into two parallel hollows4 ,but1 to return to our coast-lines and the question of their development1 it is obvious that their general trends have been determined by crustal movements4 ,their regularity is in direct proportion to the closeness of their approach to the margin of the continental plateau4 ,the more nearly they coincide with the edge of that plateau1 the fewer irregularities do they present2 the further they recede from it1 the more highly are they indented4 ,various other factors1 it is true1 have played a more or less important part in their development1 but their dominant trends were undoubtedly determined at a very early period in the world's history--their determination necessarily dates back1 in short1 to the time when the great world-ridges and oceanic troughs came into existence4 ,so far as we can read the story told by the rocks1 however1 it would seem that in the earliest ages of which geology can speak with any confidence1 the coast-lines of the world must have been infinitely more irregular than now4 ,in ,palozoic times1 relatively small areas of the continental plateau appeared above the level of the sea4 ,insular conditions everywhere prevailed4 ,but as ages rolled on1 wider and wider tracts of the plateau were exposed1 and this notwithstanding many oscillations of level4 ,so that one may say there has been1 upon the whole1 a general advance from insular to continental conditions4 ,in other words1 the sea has continued to retreat from the surface of the continental plateau4 ,to account for this change1 we must suppose that depression of the crust has been in excess within the oceanic area1 and that now and again positive elevation of the continental plateau has taken place1 more especially along its margins4 ,that movements of elevation1 positive or negative1 have again and again affected our land-areas can be demonstrated1 and it seems highly probable1 therefore1 that similar movements may have been experienced within the oceanic trough4 ,two kinds of crustal movement1 as we have seen1 are recognised by geologists4 ,sometimes the crust appears to rise1 or1 as the case may be1 to sink over wide regions1 without much disturbance or tilting of strata1 although these are now and again more or less extensively fractured and displaced4 ,it may conduce to clearness if we speak of these movements as regional4 ,the other kind of crustal disturbance takes place more markedly in linear directions1 and is always accompanied by abrupt folding and mashing together of strata1 along with more or less fracturing and displacement4 ,the plateau of the ,colorado has often been cited as a good example of regional elevation1 where we have a wide area of approximately horizontal strata apparently uplifted without much rock-disturbance1 while the ,alps or any other chain of highly-flexed and convoluted strata will serve as an example of what we may term axial or linear uplifts4 ,it must be understood that both regional and axial movements result from the same cause--the adjustment of the solid crust to the contracting nucleus--and that the term elevation1 therefore1 is only relative4 ,sometimes the sinking crust gets relief from the enormous lateral pressure to which it is subjected by crumpling up along lines of weakness1 and then mountains of elevation are formed2 at other times1 the pressure is relieved by the formation of broader swellings1 when wide areas become uplifted relatively to surrounding regions4 ,geologists1 however1 are beginning to doubt whether upheaval of the latter kind can affect a broad continental area4 ,probably1 in most cases1 the apparent elevation of continental regions is only negative4 ,the land appears to have risen because the floor of the oceanic basin has become depressed4 ,even the smaller plateau-like elevations which occur within some continental regions may in a similar way owe their dominance to the sinking of contiguous regions4 ,in the geographical development of our land1 movements of elevation and depression have played an important part4 ,but we cannot ignore the work done by other agents of change4 ,if the orographical features of the land everywhere attest the potency of plutonic agents1 they no less forcibly assure us that the inequalities of surface resulting from such movements are universally modified by denudation and sedimentation4 ,elevated plains and mountains are gradually demolished1 and the hollows and depressions of the great continental plateau become slowly filled with their detritus4 ,thus inland-seas tend to vanish1 inlets and estuaries are silted up1 and the land in places advances seaward4 ,the energies of the sea1 again1 come in to aid those of rain and rivers1 so that under the combined action of all the superficial agents of change1 the irregularities of coast-lines become reduced1 and1 were no crustal movement to intervene1 would eventually disappear4 ,the work accomplished by those agents upon a coast-line is most conspicuous in regions where the surface of the continental plateau is occupied by comparatively shallow seas4 ,here full play is given to sedimentation and marine erosion1 while the latter alone comes into prominence upon shores that are washed by deeper waters4 ,when the coast-lines advance to the edge of the continental plateau1 they naturally trend1 as we have seen1 for great distances in some particular direction4 ,should they preserve that position1 undisturbed by crustal oscillation1 for a prolonged period of time1 they will eventually be cut back by the sea4 ,in this way a shelf or terrace will be formed1 narrow in some places1 broader in others1 according to the resistance offered by the varying character of the rocks4 ,but no long inlets or fiords can result from such action4 ,at most the harder and less readily demolished rocks will form headlands1 while shallow bays will be scooped out of the more yielding masses4 ,in short1 between the narrower and broader parts of the eroded shelf or terrace a certain proportion will tend to be preserved4 ,as the shelf is widened1 sedimentation will become more and more effective1 and in places may come to protect the land from further marine erosion4 ,this action is especially conspicuous in tropical and sub-tropical regions1 which are characterised by well-marked rainy seasons4 ,in such regions immense quantities of sediment are washed down from the land to the sea1 and tend to accumulate along shore1 forming low alluvial flats4 ,all long-established coast-lines thus acquire a characteristically sinuous form1 and perhaps no better examples could be cited than those of western ,africa4 ,to sum up1 then1 we may say that the chief agents concerned in the development of coast-lines are crustal movements1 sedimentation1 and marine erosion4 ,all the main trends are the result of elevation and depression4 ,considerable geographical changes1 however1 have been brought about by the silting up of those shallow and sheltered seas which1 in certain regions1 overflow wide areas of the continental plateau4 ,throughout all the ages1 indeed1 epigene agents have striven to reduce the superficial inequalities of that plateau1 by levelling heights and filling up depressions1 and thus1 as it were1 flattening out the land-surface and causing it to extend4 ,the erosive action of the sea1 from our present point of view1 is of comparatively little importance4 ,it merely adds a few finishing touches to the work performed by the other agents of change4 ,a glance at the geographical evolution of our own ,continent will render this sufficiently evident4 ,viewed in detail1 the structure of ,europe is exceedingly complicated1 but there are certain leading features in its architecture which no profound analysis is required to detect4 ,we note1 in the first place1 that highly-disturbed rocks of ,archan and ,palozoic age reach their greatest development along the north-western and western borders of our ,continent1 as in ,scandinavia1 the ,british ,islands1 north-west ,france1 and the ,iberian peninsula4 ,another belt of similarly disturbed strata of like age traverses central ,europe from west to east1 and is seen in the south of ,ireland1 ,cornwall1 north-west ,france1 the ,ardennes1 the ,thringer-,wald1 the ,erz ,gebirge1 the ,riesen ,gebirge1 the ,bhmer-,wald1 and other heights of middle and southern ,germany4 ,strata of ,mesozoic and ,cainozoic age rest upon the older systems in such a way as to show that the latter had been much folded1 fractured1 and denuded before they came to be covered with younger formations4 ,north and north-east of the central belt of ancient rocks just referred to1 the sedimentary strata that extend to the shores of the ,baltic and over a vast region in ,russia1 range in age from ,palozoic down to ,cainozoic times1 and are disposed for the most part in gentle undulations--they are either approximately horizontal or slightly inclined4 ,unlike the disturbed rocks of the maritime regions and of central ,europe1 they have obviously been subjected to comparatively little folding since the time of their deposition4 ,to the south of the primitive back-bone of central ,europe succeeds a region composed superficially of ,mesozoic and ,cainozoic strata for the most part1 which1 along with underlying ,palozoic and ,archan rocks1 are often highly-flexed and ridged up1 as in the chains of the ,jura1 the ,alps1 the ,carpathians1 etc4 ,one may say1 in general terms1 that throughout the whole ,mediterranean area ,archan and ,palozoic rocks appear at the surface only when they form the nuclei of mountains of elevation1 into the composition of which rocks of younger age largely enter4 ,from this bald and meagre outline of the general geological structure of ,europe1 we may gather that the leading orographical features of our ,continent began to be developed at a very early period4 ,unquestionably the oldest land-areas are represented by the disturbed ,archan and ,palozoic rocks of the ,atlantic sea-board and central ,europe4 ,examination of those tracts shows that they have experienced excessive denudation4 ,the ,archan and ,palozoic masses1 distributed along the margin of the ,atlantic1 are the mere wrecks of what1 in earlier ages1 must have been lofty regions1 the mountain-chains of which may well have rivalled or even exceeded in height the ,alps of to-day4 ,they1 together with the old disturbed rocks of central ,europe1 formed for a long time the only land in our area4 ,between the ancient ,scandinavian tract in the north and a narrow interrupted belt in central ,europe1 stretched a shallow sea1 which covered all the regions that now form our ,great ,plain2 while immediately south of the central belt lay the wide depression of the ,mediterranean--for as yet the ,pyrenees1 the ,alps1 and the ,carpathians were not4 ,both the ,mediterranean and the ,russo-,germanic sea communicated with the ,atlantic4 ,as time went on land continued to be developed along the same lines1 a result due partly to crustal movements1 partly to sedimentation4 ,thus the relatively shallow ,russo-,germanic sea became silted up1 while the ,mediterranean shore-line advanced southwards4 ,it is interesting to note that the latter sea1 down to the close of ,tertiary times1 seems always to have communicated freely with the ,atlantic1 and to have been relatively deep4 ,the ,russo-,germanic sea1 on the contrary1 while now and again opening widely into the ,atlantic1 and attaining considerable depths in its western reaches1 remained on the whole shallow1 and ever and anon vanished from wide areas to contract into a series of inland-seas and large salt lakes4 ,reduced to its simplest elements1 therefore1 the structure of ,europe shows two primitive ridges--one extending with some interruptions along the ,atlantic sea-board1 the other traversing central ,europe from west to east1 and separating the area of the ,great ,plain from the ,mediterranean basin4 ,the excessive denudation which the more ancient lands have undergone1 and the great uplifts of ,mesozoic and of ,cainozoic times1 together with the comparatively recent submergence of broad tracts in the north and north-west1 have not succeeded in obscuring the dominant features in the architecture of our ,continent4 ,i now proceed to trace1 as rapidly as ,i can1 the geographical development of the coast-lines of the ,atlantic as a whole1 and to point out the chief contrasts between them and the coast-lines of the ,pacific4 ,the extreme irregularity of the ,arctic and ,atlantic shores of ,europe at once suggests to a geologist a partially-drowned land1 the superficial inequalities of which are accountable for the vagaries of the coast-lines4 ,the fiords of ,norway and ,scotland occupy what were at no distant date land-valleys1 and the numerous marginal islands of those regions are merely the projecting portions of a recently-sunken area4 ,the continental plateau extends up to and a little beyond the one hundred fathoms line1 and there are many indications that the land formerly reached as far4 ,thus the sunken area is traversed by valley-like depressions1 which widen as they pass outwards to the edge of the plateau1 and have all the appearance of being hollows of sub-arial erosion4 ,i have already mentioned the fact that the ,scandinavian uplands and the ,scottish ,highlands are the relics of what were at one time true mountains of elevation1 corresponding in the mode of their formation to those of ,switzerland1 and1 like these1 attaining a great elevation4 ,during subsequent stages of ,palozoic time1 that highly-elevated region was subjected to long-continued and profound erosion--the mountain-country was planed down over wide regions to sea-level1 and broad stretches of the reduced land-surface became submerged4 ,younger ,palozoic formations then accumulated upon the drowned land1 until eventually renewed crustal disturbance supervened1 and the marginal areas of the continental plateau again appeared as dry land1 but not1 as before1 in the form of mountains of elevation4 ,lofty table-lands now took the place of abrupt and serrated ranges and chains--table-lands which1 in their turn1 were destined in the course of long ages to be deeply sculptured and furrowed by sub-arial agents4 ,during this process the ,european coast-line would seem to have coincided more or less closely with the edge of the continental plateau4 ,finally1 after many subsequent movements of the crust in these latitudes1 the land became partially submerged--a condition from which north-western and northern ,europe would appear in recent times to be slowly recovering4 ,thus the highly-indented coast-line of those regions does not coincide with the edge of the plateau1 but with those irregularities of its upper surface which are the result of antecedent sub-arial erosion4 ,mention has been made of the ,russo-,germanic plain and the ,mediterranean as representing original depressions in the continental plateau1 and of the high-grounds that extend between them as regions of dominant elevation1 which1 throughout all the manifold revolutions of the past1 would appear to have persisted as a more or less well-marked boundary1 separating the northern from the southern basin4 ,during certain periods it was no doubt in some degree submerged1 but never apparently to the same extent as the depressed areas it served to separate4 ,from time to time uplifts continued to take place along this central belt1 which thus increased in breadth1 the younger formations1 which were accumulated along the margins of the two basins1 being successively ridged up against nuclei of older rocks4 ,the latest great crustal movements in our ,continent1 resulting in the uplift of the ,alps and other east and west ranges of similar age1 have still further widened that ancient belt of dominant elevation which in our day forms the most marked orographical feature of ,europe4 ,the ,russo-,germanic basin is now for the most part land1 the ,baltic and the ,north ,sea representing its still submerged portions4 ,this basin1 as already remarked1 was probably never so deep as that of the ,mediterranean4 ,we gather as much from the fact that1 while mechanical sediments of comparatively shallow-water origin predominate in the former area1 limestones are the characteristic features of the southern region4 ,its relative shallowness helps us to understand why the northern depression should have been silted up more completely than the ,mediterranean4 ,we must remember also that for long ages it received the drainage of a much more extensive land-surface than the latter--the land that sloped towards the ,mediterranean in ,palozoic and ,mesozoic times being of relatively little importance4 ,thus the crustal movements which ever and anon depressed the ,russo-,germanic area were1 in the long-run1 counterbalanced by sedimentation4 ,the uplift of the ,alps1 the ,atlas1 and other east and west ranges1 has greatly contracted the area of the ,mediterranean1 and sedimentation has also acted in the same direction1 but it is highly probable that that sea is now as deep as1 or even deeper than1 it has ever been4 ,it occupies a primitive depression in which the rate of subsidence has exceeded that of sedimentation4 ,in many respects1 indeed1 this remarkable transmeridional hollow--continued eastward in the ,red ,sea1 the ,black ,sea1 and the ,aralo-,caspian depression--is analogous1 as we shall see1 to the great oceanic trough itself4 ,in the earlier geological periods linear or axial uplifts and volcanic action again and again marked the growth of land on the ,atlantic sea-board4 ,but after ,palozoic times1 no great mountains of elevation came into existence in that region1 while volcanic action almost ceased4 ,in ,tertiary times1 it is true1 there was a remarkable recrudescence of volcanic activity1 but the massive eruptions of ,antrim and western ,scotland1 of the ,fare ,islands and ,iceland1 must be considered apart from the general geology of our ,continent4 ,from ,mesozoic times onwards it was along the borders of the ,mediterranean depression that great mountain uplifts and volcanoes chiefly presented themselves2 and as the land-surface extended southwards from central ,europe1 and the area of the ,mediterranean was contracted1 volcanic action followed the advancing shore-lines4 ,the occurrence of numerous extinct and of still existing volcanoes along the borders of this inland-sea1 the evidence of recent crustal movements so commonly met with upon its margins1 the great irregularities of its depths1 the proximity of vast axial uplifts of late geological age1 and the frequency of earthquake phenomena1 all indicate instability1 and remind us strongly of similarly constructed and disturbed regions within the area of the vast ,pacific4 ,let us now look at the ,arctic and ,atlantic coast-lines of ,north ,america4 ,from the extreme north down to the latitude of ,new ,york the shores are obviously those of a partially-submerged region4 ,they are of the same type as the coasts of north-western ,europe4 ,we have every reason to believe also that the depression of ,greenland and north-east ,america1 from which these lands have only partially recovered1 dates back to a comparatively recent period4 ,the fiords and inlets1 like those of ,europe1 are merely half-drowned land-valleys1 and the continental shelf is crossed by deep hollows which are evidently only the seaward continuations of well-marked terrestrial features4 ,such1 for example1 is the case with the valleys of the ,hudson and the ,st4 ,lawrence1 the submerged portions of which can be followed out to the edge of the continental plateau1 which is notched by them at depths of #dgd and #fbb fathoms respectively4 ,there is1 in short1 a broad resemblance between the coasts of the entire ,arctic and ,north ,atlantic regions down to the latitudes already mentioned4 ,everywhere they are irregular and fringed with islands in less or greater abundance--highly-denuded and deeply-incised plateaux being penetrated by fiords1 while low-lying and undulating lands that shelve gently seaward are invaded by shallow bays and inlets4 ,comparing the ,american with the opposite ,european coasts one cannot help being struck with certain other resemblances4 ,thus ,hudson ,bay at once suggests the ,baltic1 and the ,gulf of ,mexico1 with the ,caribbean ,sea1 recalls the ,mediterranean4 ,but the geological structure of the coast-lands of ,greenland and ,north ,america betrays a much closer resemblance between these and the opposite shores of ,europe than appears on a glance at the map4 ,there is something more than a mere superficial similarity4 ,in eastern ,north ,america and ,greenland1 just as in western ,europe1 no grand mountain uplifts have taken place for a prodigious time4 ,the latest great upheavals1 which were accompanied by much folding and flexing of strata1 are those of the ,appalachian chain and of the coastal ranges extending through ,new ,england1 ,nova ,scotia1 and ,newfoundland1 all of which are of ,palozoic age4 ,considerable crustal movements affected the ,american coast-lines in ,mesozoic times1 and during these uplifts the strata suffered fracture and displacement1 but were subjected to comparatively little folding4 ,again1 along the maritime borders of north-east ,america1 as in the corresponding coast-lines of ,europe1 igneous action1 more or less abundant in ,palozoic and early ,mesozoic times1 has since been quiescent4 ,from the mouth of the ,hudson to the ,straits of ,florida the coast-lines are composed of ,tertiary and ,quaternary deposits4 ,this shows that the land has continued down to recent times to gain upon the sea--a result brought about partly by quiet crustal movements1 but to a large extent by sedimentation1 aided1 on the coasts of ,florida1 by the action of reef-building corals4 ,although volcanic action has long ceased on the ,american sea-board1 we note that in ,greenland1 as in the west of ,scotland and north of ,ireland1 there is abundant evidence of volcanic activity at so late a period as the ,tertiary4 ,it would appear that the great plateau-basalts of those regions1 and of ,iceland and the ,fare ,islands1 were contemporaneous1 and were possibly connected with an important crustal movement4 ,it has long been suggested that at a very early geological period ,europe and ,north ,america may have been united4 ,the great thickness attained by the ,palozoic rocks in the eastern areas of the latter implies the existence of a wide land-surface from which ancient sediments were derived4 ,that old land must have extended beyond the existing coast-line1 but how far we cannot tell4 ,similarly in north-west ,europe1 during early ,palozoic times1 the land probably stretched further into the ,atlantic than at present4 ,but whether1 as some think1 an actual land-connection subsisted between the two continents it is impossible to say4 ,some such connection was formerly supposed necessary to account for life common to the ,palozoic strata of both continents1 and which1 as they were probably denizens of comparatively shallow water1 could only have crossed from one area to another along a shore-line4 ,it is obvious1 indeed1 that if the oceanic troughs in those early days were of an abysmal character1 a belt of shallow water would be required to explain the geographical distribution of cosmopolitan marine life-forms4 ,but if it be true that subsidence of the crust has been going on through all geological time1 and that the land-areas have nothwithstanding continued to extend over the continental plateau1 then it follows that the oceanic trough must be deeper now than it was in ,palozoic times4 ,there are1 moreover1 certain geological facts which seem hardly explicable on the assumption that the seas of past ages attained abysmal depths over any extensive areas4 ,the ,palozoic strata which enter so largely into the framework of our lands have much the same appearance all the world over1 and were accumulated for the most part in comparatively shallow water4 ,a petrographical description of the ,palozoic mechanical sediments of ,europe would serve almost equally well for those of ,america1 of ,asia1 or of ,australia4 ,take in connection with this the fact that ,palozoic faunas had a very much wider range than those of ,mesozoic and later ages1 and were characterised above all by the presence of many cosmopolitan species1 and we can hardly resist the conclusion that it was the comparative shallowness of the ancient seas that favoured that wide dispersal of species1 and enabled currents to distribute sediments the same in kind over such vast regions4 ,as the oceanic area deepened and contracted1 and the land-surface increased1 marine faunas were gradually restricted in their range1 and the cosmopolitan marine forms diminished in numbers1 while sediments1 gathering in separate regions1 became more and more differentiated4 ,for these and other reasons which need not be entered upon here1 ,i see no necessity for supposing that a ,palozoic ,atlantis connected ,europe with ,north ,america4 ,the broad ridge upon which the ,fare ,islands and ,iceland are founded seems to pertain as truly to the oceanic depression as the long ,dolphin ,ridge of the ,south ,atlantic4 ,the trend of the continental plateau in high latitudes is shown1 as ,i think1 by the general direction of the coast-lines of north-western ,europe and east ,greenland1 the continental shelf being submerged in those regions for a few hundred fathoms only4 ,how the ,icelandic ridge came into existence1 and what its age may be1 we can only conjecture4 ,it may be a wrinkle as old as the oceanic trough which it traverses1 or its origin may date back to a much more recent period4 ,we may conceive it to be an area which has subsided more slowly than the floor of the ocean to the north and south2 or1 on the other hand1 it may be a belt of positive elevation4 ,perhaps the latter is the more probable supposition1 for it seems very unlikely that crustal disturbances1 resulting in axial and regional uplifts1 should have been confined to the continental plateau only4 ,be that as it may1 there is little doubt that land-connection did obtain between ,greenland and ,europe in the ,cainozoic times along this ,icelandic ridge1 for relics of the same ,tertiary flora are found in ,scotland1 the ,fare ,islands1 ,iceland1 and ,greenland4 ,the deposits in which these plant-remains occur are associated with great sheets of volcanic rocks1 which in the ,fare ,islands and ,iceland reach a thickness of many thousand feet4 ,of the same age are the massive basalts of ,jan ,mayen1 ,spitzbergen1 ,franz-,joseph ,land1 and ,greenland4 ,these lavas seem seldom to have issued from isolated foci in the manner of modern eruptions1 but rather to have welled up along the lines of rectilineal fissures4 ,from the analogy of similar phenomena in other parts of the world it might be inferred that the volcanic action of these northern regions may have been connected with a movement of elevation1 and that the ,icelandic ridge1 if it did not come into existence during the ,tertiary period1 was at all events greatly upheaved at that time4 ,it would seem most likely1 in short1 that the volcanic action in question was connected mainly with crustal movements in the oceanic trough4 ,similar phenomena1 as is well known1 are met with further south in the trough of the ,atlantic4 ,thus the volcanic ,azores rise like ,iceland from the surface of a broad ridge which is separated from the continental plateau by wide and deep depressions4 ,and so again1 from the back of the great ,dolphin ,ridge1 spring the volcanic islets of ,st4 ,paul's1 ,ascension1 and ,tristan d',acunha4 ,i have treated of the ,icelandic bank at some length for the purpose of showing that its volcanic phenomena do not really form an exception to the rule that such eruptions ceased after ,palozoic or early ,mesozoic times to disturb the ,atlantic coast-lines of ,europe and ,north ,america4 ,as the bank in question extends between ,greenland and the ,british ,islands1 it was only natural that both those regions should be affected by its movements4 ,but its history pertains essentially to that of the ,atlantic trough2 and it seems to show us how transmeridional movements of the crust1 accompanied by vast discharges of igneous rock1 may come in time to form land-connections between what are now widely-separated areas4 ,let us next turn our attention to the coast-lines of the ,gulf of ,mexico and the ,caribbean ,sea4 ,these enclosed seas have frequently been compared to the ,mediterranean1 and the resemblance is self-evident4 ,indeed1 it is so close that one may say the ,mexican-,caribbean ,sea and the ,mediterranean are rather homologous than simply analogous4 ,the latter1 as we have seen1 occupies a primitive depression1 and formerly covered a much wider area4 ,it extended at one time over much of southern ,europe and northern ,africa1 and appears to have had full communication across ,asia ,minor with the ,indian ,ocean1 and with the ,arctic ,ocean athwart the low-lying tracts of north-western ,asia4 ,similarly1 it would seem1 the ,mexican-,caribbean ,sea is the remaining portion of an ancient inland-sea which formerly stretched north through the heart of ,north ,america to the ,arctic ,ocean4 ,like its ,european parallel1 it has been diminished by sedimentation and crustal movements4 ,it resembles the latter also in the greatness and irregularity of its depths1 and in the evidence which its islands supply of volcanic action as well as of very considerable crustal movements within recent geological times4 ,along the whole northern borders of the ,gulf of ,mexico the coast-lands1 like those on the ,atlantic sea-board of the ,southern ,states1 are composed of ,tertiary and recent accumulations1 and the same is the case with ,yucatan2 while similar young formations are met with on the borders of the ,caribbean ,sea and in the ,antilles4 ,the ,bahamas and the ,windward ,islands mark out for us the margin of the continental plateau1 which here falls away abruptly to profound depths4 ,one feels assured that this portion of the plateau has been ridged up to its present level at no distant geological date4 ,but notwithstanding all the evidence of recent extensive crustal movements in this region1 it is obvious that the ,mexican-,caribbean depression1 however much it may have been subsequently modified1 is of primitive origin4,,dp ,,dp ,professor ,suess thinks it is probable that the ,caribbean ,sea and the ,mediterranean are portions of one and the same primitive depression which traversed the ,atlantic area in early ,cretaceous times4 ,he further suggests that it may have been through the gradual widening of the central ,mediterranean that the ,atlantic in later times came into existence4 ,before we leave the coast-lands of ,north ,america1 ,i would again point out their leading geological features4 ,in a word1 then1 they are composed for the most part of ,archan and ,palozoic rocks2 no great linear or axial uplifts marked by much flexure of strata have taken place in those regions since ,palozoic times2 while igneous action virtually ceased about the close of the ,palozoic or the commencement of the ,mesozoic period4 ,it is not before we reach the shores of the ,southern ,states and the coast-lands of the ,mexican-,caribbean ,sea that we encounter notable accumulations of ,mesozoic1 ,tertiary1 and younger age4 ,these occur in approximately horizontal positions round the ,gulf of ,mexico2 but in the ,sierra ,nevada of northern ,colombia and the ,cordilleras of ,venezuela the ,tertiary strata enter into the formation of true mountains of elevation4 ,thus the ,mexican-,caribbean depression1 like that of the ,mediterranean1 is characterised not only by its irregular depths and its volcanic phenomena1 but by the propinquity of recent mountains of upheaval1 which bear the same relation to the ,caribbean ,sea as the mountains of north ,africa do to the ,mediterranean4 ,we may now compare the ,atlantic coasts of ,south ,america with those of ,africa4 ,the former coincide in general direction with the edge of the continental plateau1 to which they closely approach between ,cape ,st4 ,roque and ,cape ,frio4 ,in the north-east1 between ,cape ,paria1 opposite ,trinidad1 and ,cape ,st4 ,roque1 the continental shelf attains a considerably greater breadth1 while south of ,cape ,frio it gradually widens until1 in the extreme south1 it runs out towards the east in the form of a narrow ridge1 upon the top of which rise the ,falkland ,islands and south ,georgia4 ,excluding from consideration for the present all recent alluvial and ,tertiary deposits1 we may say that the coast-lands from ,venezuela down to the south of ,brazil are composed principally of ,archan rocks2 the eastern borders of the continent further south being formed of ,quaternary and ,tertiary accumulations4 ,so far as we know1 igneous rocks are of rare occurrence on the ,atlantic sea-board4 ,palozoic strata approach the coast-lands at various points between the mouths of the ,amazons and ,la ,plata1 and these1 with the underlying and surrounding ,archan rocks1 are more or less folded and disturbed1 while the younger strata of ,mesozoic and ,cainozoic age 7occupying wide regions in the basin of the ,amazons1 and here and there fringing the sea-coast7 occur in approximately horizontal positions4 ,it would appear1 therefore1 that no great axial uplifts have taken place in those regions since ,palozoic times4 ,the crustal movements of later ages were regional rather than axial2 the younger rocks are not flexed and mashed together1 and their elevation 7negative or positive7 does not seem to have been accompanied by conspicuous volcanic action4 ,the varying width of the continental shelf is due to several causes4 ,the ,orinoco1 the ,amazons1 and other rivers descending to the north-east coast1 carry enormous quantities of sediment1 much of which comes to rest on the submerged slopes of the continental plateau1 so that the continental shelf tends to extend seawards4 ,the same process takes place on the south-east coast1 where the ,rio de la ,plata discharges its muddy waters4 ,south of latitude #dj ,s41 however1 another cause has come into play4 ,from the mouth of the ,rio ,negro to the terminal point of the continent the whole character of the coast betokens a geologically recent emergence1 accompanied and followed by considerable marine erosion4 ,so that in this region the continental shelf increases in width by the retreat of the coast-line1 while in the north-east it gains by advancing seawards4 ,it is to be noted1 however1 that even there1 in places where the shores are formed of alluvia1 the sea tends to encroach upon the land4 ,the ,atlantic coast of ,africa resembles that of ,south ,america in certain respects1 but it also offers some important contrasts4 ,as the northern coasts of ,venezuela and ,colombia must be considered in relation rather to the ,caribbean depression than to the ,atlantic1 so the ,african sea-board between ,cape ,spartel and ,cape ,nun pertains structurally to the ,mediterranean region4 ,from the southern limits of ,morocco to ,cape ,colony the coastal heights are composed chiefly of ,archan and ,palozoic rocks1 the low shore-lands showing here and there strata of ,mesozoic and ,tertiary age together with still more recent deposits4 ,the existing coast-lines everywhere advance close to the edge of the continental plateau1 so that the submarine shelf is relatively narrower than that of eastern ,south ,america4 ,the ,african coast is still further distinguished from that of ,south ,america by the presence of several groups of volcanic islands--,fernando ,po and others in the ,gulf of ,guinea1 and ,cape ,verde and ,canary ,islands4 ,the last-named group1 however1 notwithstanding its geographical position1 is probably related rather to the ,mediterranean depression than to the ,atlantic trough4 ,the geological structure of the ,african coast-lands shows that the earliest to come into existence were those that extend between ,cape ,nun and the ,cape of ,good ,hope4 ,the coastal ranges of that section are much denuded1 for they are of very great antiquity1 having been ridged up in ,palozoic times4 ,the later uplifts 7negative or positive7 of the same region were not attended by tilting and folding of strata1 for the ,mesozoic and ,tertiary deposits1 like those of ,south ,america1 lie in comparatively horizontal positions4 ,between ,cape ,nun and ,cape ,spartel the rocks of the maritime tracts range in age from ,palozoic to ,cainozoic1 and have been traced across ,morocco into ,algeria and ,tunis4 ,they all belong to the ,mediterranean region1 and were deposited at a time when the southern shores of that inland sea extended from a point opposite the ,canary ,islands along what is now the southern margin of ,morocco1 ,algeria1 and ,tunis4 ,towards the close of the ,tertiary period the final upheaval of the ,atlas took place1 and the ,mediterranean1 retreating northwards1 became an almost land-locked sea4 ,i need hardly stop to point out how the ,african coast-lines have been modified by marine erosion and the accumulation of sediment upon the continental shelf4 ,the extreme regularity of the coasts is due partly to the fact that the land is nearly co-extensive with the continental plateau1 but it also results in large measure from the extreme antiquity of the land itself4 ,this has allowed of the cutting-back of headlands and the rilling up of bays and inlets1 a process which has been going on between ,morocco and ,cape ,colony with probably little interruption for a very prolonged period of time4 ,we may note also the effect of the heavy rains of the equatorial region in washing down detritus to the shores1 and in this way protecting the land to some extent from the erosive action of the sea4 ,what now1 let us ask1 are the outstanding features of the coast-lines of the ,atlantic ,ocean8 ,we have seen that along the margins of each of the bordering continents the last series of great mountain-uplifts took place in ,palozoic times4 ,this is true alike for ,north and ,south ,america1 for ,europe and ,africa4 ,later movements which have added to the extent of land were not marked by the extreme folding of strata which attended the early upheavals4 ,the ,mesozoic and ,cainozoic rocks1 which now and again form the shore-lands1 occur in more or less undisturbed condition4 ,the only great linear uplifts or true mountains of elevation which have come into existence in western ,europe and northern ,africa since the ,palozoic period trend approximately at right angles to the direction of the ,atlantic trough1 and are obviously related to the primitive depression of the ,mediterranean4 ,the ,pyrenees and the ,atlas1 therefore1 although their latest elevation took place in ,tertiary times1 form no exceptions to the rule that the extreme flexing and folding of strata which is so conspicuous a feature in the geological structure of the ,atlantic sea-board dates back to the ,palozoic era4 ,and the same holds true of ,north and ,south ,america4 ,there all the coastal ranges of highly flexed and folded strata are of ,palozoic age4 ,the ,cordilleras of ,venezuela are no doubt a ,tertiary uplift1 but they are as obviously related to the ,caribbean depression as the ,atlas ranges are to that of the ,mediterranean4 ,again1 we note that volcanic activity along the borders of the ,atlantic was much less pronounced during the ,mesozoic period than it appears to have been in the earlier ages4 ,indeed1 if we except the great ,tertiary basalt-flows of the ,icelandic ridge and the ,arctic regions1 we may say that volcanic action almost ceased after the ,palozoic era to manifest itself upon the ,atlantic coast-lands of ,north ,america and ,europe4 ,but while volcanic action has died out upon the ,atlantic margins of both continents1 it has continued during a prolonged geological period within the area of the ,mediterranean depression4 ,and in like manner the corresponding depression between ,north and ,south ,america has been the scene of volcanic disturbances from ,mesozoic down to recent times4 ,along the ,african coasts the only displays of recent volcanic action that appertain to the continental margin are those of the ,gulf of ,guinea and the ,cape de ,verde ,islands4 ,the ,canary ,islands and ,madeira may come under the same category1 but1 as we have seen1 they appear to stand in relationship to the ,mediterranean depression and the ,tertiary uplift of ,north ,africa4 ,of ,iceland and the ,azores ,i have already spoken1 and of ,ascension and the other volcanic islets of the ,south ,atlantic it is needless to say that they are related to wrinkles in the trough of the ocean1 and therefore have no immediate connection with the continental plateau4 ,thus in the geographical development of the ,atlantic coast-lines we may note the following stages3--,first1 in ,palozoic times the formation of great mountain-uplifts1 frequently accompanied by volcanic action4 ,second1 a prolonged stage of comparative coastal tranquillity1 during which the maritime ranges referred to were subject to such excessive erosion that they were planed down to low levels1 and in certain areas even submerged4 ,third1 renewed elevation 7negative or positive7 whereby considerable portions of the much-denuded ,archan and ,palozoic rocks1 now largely covered by younger deposits1 were converted into high-lands4 ,during this stage not much rock-folding took place1 nor were any true mountains of elevation formed parallel to the ,atlantic margins4 ,it was otherwise1 however1 in the ,mediterranean and ,caribbean depressions1 where coastal movements resulted in the formation of enormous linear uplifts4 ,moreover1 volcanic action is now and has for a long time been more characteristic of these depressions than of the ,atlantic coast-lands4 ,i must now ask you to take a comprehensive glance at the coast-lines of the ,pacific ,ocean4 ,in some important respects these offer a striking contrast to those we have been considering4 ,time will not allow me to enter into detailed description1 and ,i must therefore confine attention to certain salient features4 ,examining first the shores of the ,americas1 we find that there are two well-marked regions of fiords and fringing islands--namely1 the coasts of ,alaska and ,british ,columbia1 and of ,south ,america from #dj ,s4,l4 to ,cape ,horn4 ,although these regions may be now extending seawards in places1 it is obvious that they have recently been subject to submergence4 ,when the fiords of ,alaska and ,british ,columbia existed as land-valleys it is probable that a broad land-connection obtained between ,north ,america and ,asia4 ,the whole ,pacific coast is margined by mountain-ranges1 which in elevation and boldness far exceed those of the ,atlantic sea-board4 ,the rocks entering into their formation range in age from ,archan and ,palozoic down to ,cainozoic1 and they are almost everywhere highly disturbed and flexed4 ,it is not necessary1 even if it were possible1 to consider the geological history of all those uplifted masses4 ,it is enough for my purpose to note the fact that the coastal ranges of ,north ,america and the principal chain of the ,andes were all elevated in ,tertiary times4 ,it may be remarked further that1 from the ,mesozoic period down to the present1 the ,pacific borders of ,america have been the scene of volcanic activity far in excess of what has been experienced on the ,atlantic sea-board4 ,geographically the ,asiatic coasts of the ,pacific offer a strong contrast to those of the ,american borders4 ,the latter1 as we have seen1 are for the most part not far removed from the edge of the continental plateau4 ,the coasts of the mainland of ,asia1 on the other hand1 retire to a great distance1 the true margin of the plateau being marked out by that great chain of islands which extends from ,kamchatka south to the ,philippines and ,new ,guinea4 ,the seas lying between those islands and the mainland occupy depressions in the continental plateau4 ,were that plateau to be lifted up for #fjjj or #gjjj feet the seas referred to would be enclosed by continuous land1 and all the principal islands of the ,east ,indian ,archipelago--,sumatra1 ,java1 ,celebes1 and ,new ,guinea1 would become united to themselves as well as to ,australia and ,new ,zealand4 ,in short1 it is the relatively depressed condition of the continental plateau along the western borders of the ,pacific basin that causes the ,asiatic coast-lines to differ so strikingly from those of ,america4 ,from a geological point of view the differences are less striking than the resemblances4 ,it is true that we have as yet a very imperfect knowledge of the geological structure of eastern ,asia1 but we know enough to justify the conclusion that in its main features that region does not differ essentially from western ,north ,america4 ,during ,mesozoic and ,cainozoic times the sea appears to have overflowed vast tracts of ,manchooria and ,china1 and even to have penetrated into what is now the great ,desert of ,gobi4 ,subsequent crustal movements revolutionised the geography of all those regions4 ,great ranges of linear uplifts came into existence1 and in these the younger formations1 together with the foundations on which they rested1 were squeezed into folds and ridged up against the nuclei of ,palozoic and ,archan rocks which had hitherto formed the only dry land4 ,the latest of these grand upheavals are of ,tertiary age1 and1 like those of the ,pacific slope of ,america1 they were accompanied by excessive volcanic action4 ,the long chains of islands that flank the shores of ,asia we must look upon as a series of partially submerged or partially emerged mountain-ranges1 analogous geographically to the coast-ranges of ,north and ,central ,america1 and to the youngest ,cordilleras of ,south ,america4 ,the presence of numerous active and recently extinct volcanoes1 taken in connection with the occurrence of many great depressions which furrow the floor of the sea in the ,east ,indian ,archipelago1 and the profound depths attained by the ,pacific trough along the borders of ,japan and the ,kurile and ,aleutian ,islands--all indicate conditions of very considerable instability of the lithosphere4 ,we are not surprised1 therefore1 to meet with much apparently conflicting evidence of elevation and depression in the coast-lands of eastern ,asia1 where in some places the sea would seem to be encroaching1 while in other regions it is retreating4 ,in all earthquake-ridden and volcanic areas such irregular coastal changes may be looked for4 ,so extreme are the irregularities of the sea-floor in the area lying between ,australia1 the ,solomon ,islands1 the ,new ,hebrides1 and ,new ,zealand1 and so great are the depths attained by many of the depressions1 that the margins of the continental plateau are harder to trace here than anywhere else in the world4 ,the bottom of the oceanic trough throughout a large portion of the southern and western ,pacific is1 in fact1 traversed by many great mountain-ridges1 the summits of which approach the surface again and again to form the numerous islets of ,polynesia4 ,but notwithstanding the considerable depths that separate ,australia from ,new ,zealand there is geological evidence to show that a land-connection formerly linked both to ,asia4 ,the continental plateau1 therefore1 must be held to include ,new ,caledonia and ,new ,zealand4 ,hence the volcanic islets of the ,solomon and ,new ,hebrides groups are related to ,australia in the same way as the ,liu-kiu1 ,japanese1 and ,kurile ,islands are to ,asia4 ,having rapidly sketched the more prominent features of the ,pacific coast-lines1 we are in a position to realise the remarkable contrast they present to the coast-lines of the ,atlantic4 ,the highly-folded strata of the ,atlantic sea-board are the relics of great mountains of upheaval1 the origin of which cannot be assigned to a more recent date than ,palozoic times4 ,during subsequent crustal movements no mountains of corrugated strata were uplifted along the ,atlantic margins1 the ,mesozoic and ,cainozoic strata of the coastal regions showing little or no disturbance4 ,it is quite in keeping with all this that volcanic action appears to have been most strongly manifested in ,palozoic times4 ,so many long ages have passed since the upheaval of the ,archan and ,palozoic mountains of the ,atlantic sea-board that these heights have everywhere lost the character of true mountains of elevation4 ,planed down to low levels1 partially submerged and covered to some extent by newer formations1 they have in many places been again converted into dry lands1 forming plateaux--now sorely denuded and cut up into mountains and valleys of erosion4 ,why the later movements along the borders of the ,atlantic basin should not have resulted in the wholesale plication of the younger sedimentary rocks is a question for geologists4 ,it would seem as if the ,atlantic margins had reached a stage of comparative stability long before the grand ,tertiary uplifts of the ,pacific borders had taken place2 for1 as we have seen1 the ,mesozoic and the ,cainozoic strata of the ,atlantic coast-lands show little or no trace of having been subjected to tangential thrusting and crushing4 ,hence one cannot help suspecting that the retreat of the sea during ,mesozoic and ,cainozoic ages may have been due rather to subsidence of the oceanic trough and to sedimentation within the continental area than to positive elevation of the land4 ,over the ,pacific trough1 likewise1 depression has probably been in progress more or less continuously since ,palozoic times1 and this movement alone must have tended to withdraw the sea from the surface of the continental plateau in ,asia and ,america4 ,but by far the most important coastal changes in those regions have been brought about by the crumpling-up of the plateau1 and the formation of gigantic mountains of upheaval along its margins4 ,from remotest geological periods down almost to the present1 the land-area has been increased from time to time by the doubling-up and consequent elevation of coastal accumulations1 and by the eruption of vast masses of volcanic materials4 ,it is this long-continued activity of the plutonic forces within the ,pacific area which has caused the coast-lands of that basin to contrast so strongly with those of the ,atlantic4 ,the latter are incomparably older than the former--the heights of the ,atlantic borders being mountains of denudation of vast geological antiquity1 while the coastal ranges of the ,pacific slope are creations but of yesterday as it were4 ,it may well be that those ,cordilleras and mountain-chains reach a greater height than was ever attained by any ,palozoic uplifts of the ,atlantic borders4 ,but the marked disparity in elevation between the coast-lands of the ,pacific and the ,atlantic is due chiefly to a profound difference in age4 ,had the ,pacific coast-lands existed for as long a period and suffered as much erosion as the ancient rocks of the ,atlantic sea-board1 they would now have little elevation to boast of4 ,the coast-lines of the ,indian ,ocean are not1 upon the whole1 far removed from the margin of the continental plateau4 ,the elevation of ,east ,africa for #fjjj feet would add only a narrow belt to the land4 ,this would still leave ,madagascar an island1 but there are geological reasons for concluding that this island was at a far distant period united to ,africa1 and it must therefore be considered as forming a portion of the continental plateau4 ,the great depths which now separate it from the mainland are probably due to local subsidence1 connected with volcanic action in ,madagascar itself and in the ,comoro ,islands4 ,the southern coasts of ,asia1 like those of ,east ,africa1 approach the edge of the continental plateau1 so that an elevation of #fjjj feet would make little addition to the land-area4 ,with the same amount of upheaval1 however1 the ,malay ,peninsula1 ,sumatra1 ,java1 and ,west ,australia would become united1 but without extending much further seawards4 ,land-connection1 as we know1 existed in ,mesozoic times between ,asia1 ,australia1 and ,new ,zealand1 but the coast-lines of that distant period must have differed considerably from those that would appear were the regions in question to experience now a general elevation4 ,the ,archan and the ,palozoic rocks of the ,malay ,peninsula and ,sumatra are flanked on the side of the ,indian ,ocean by great volcanic ridges1 and by uplifts of ,tertiary strata1 which continue along the line of the ,nicobar and the ,andaman ,islands into ,burma4 ,thus the coast-lines of that section of the ,indian ,ocean exhibit a geographical development similar to that of the ,pacific sea-board4 ,elsewhere1 as in ,hindustan1 ,arabia1 and ,east ,africa1 the coast-lines appear to have been determined chiefly by regional elevations of the land or subsidence of the oceanic trough in ,mesozoic and ,cainozoic times1 accompanied by the out-welling of enormous floods of lava4 ,seeing1 then1 that the ,pacific and the ,indian ,oceans are pre-eminently regions which1 down to a recent date1 have been subject to great crustal movements and to excessive volcanic action1 we may infer that in the development of their coast-lines the sea played a very subordinate part4 ,the shores1 indeed1 are largely protected from marine erosion by partially emerged volcanic ridges and by coral islands and reefs1 and to a considerable extent also by the sediment which in tropical regions especially is swept down to the coast in great abundance by rains and rivers4 ,moreover1 as the geological structure of these regions assures us1 the land would appear seldom to have remained sufficiently long at one level to permit of much destruction by waves and tidal currents4 ,in fine1 then1 we arrive at the general conclusion that the coast-lines of the globe are of very unequal age4 ,those of the ,atlantic were determined as far back as ,palozoic times by great mountain-up lifts along the margin of the continental plateau4 ,since the close of that period many crustal oscillations have taken place1 but no grand mountain-ranges have again been ridged up on the ,atlantic sea-board4 ,meanwhile the ,palozoic mountain-chains1 as we have seen1 have suffered extensive denudation1 have been planed down to sea-level1 and even submerged4 ,subsequently converted into land1 wholly or partially as the case may have been1 they now present the appearance of plains and plateaux of erosion1 often deeply indented by the sea4 ,no true mountains of elevation are met with anywhere in the coast-lands of the ,atlantic1 while volcanic action has well-nigh ceased4 ,in short1 the ,atlantic margins have reached a stage of comparative stability4 ,the trough itself1 however1 is traversed by at least two well-marked banks of upheaval--the great meridional ,dolphin ,ridge1 and the approximately transmeridional ,fare-,icelandic belt--both of them bearing volcanic islands4 ,but while all the coast-lands of the ,atlantic proper attained relative stability at an early period1 those of the ,mediterranean and ,caribbean depressions have up to recent times been the scenes of great crustal disturbance4 ,gigantic mountain-chains were uplifted along their margins at so late a period as the ,tertiary1 and their shores still witness volcanic activity4 ,it is upon the margins and within the trough of the ,pacific ,ocean1 however1 that subterranean action is now most remarkably developed4 ,the coast-lines of that great basin are everywhere formed of grand uplifts and volcanic ranges1 which1 broadly speaking1 are comparable in age to those of the ,mediterranean and ,caribbean depressions4 ,along the north-eastern margin of the ,indian ,ocean the coast-lines resemble those of the ,pacific1 being of like recent age1 and similarly marked by the presence of numerous volcanoes4 ,the northern and western shores1 however 7as in ,hindustan1 ,arabia1 and ,east ,africa71 have been determined rather by regional elevation or by subsidence of the ocean-floor than by axial uplifts--the chief crustal disturbances dating back to an earlier period than those of the ,east ,indian ,archipelago4 ,it is in keeping with this greater age of the western and northern coast-lands of the ,indian ,ocean that volcanic action is now less strongly manifested in their vicinity4 ,i have spoken of the comparative stability of the earth's crust within the ,atlantic area as being evidenced by the greater age of its coastal ranges and the declining importance of its volcanic phenomena4 ,this relative stability is further shown by the fact that the ,atlantic sea-board is not much disturbed by earthquakes4 ,this1 of course1 is what might have been expected1 for earthquakes are most characteristic of volcanic regions and of those areas in which mountain-uplifts of recent geological age occur4 ,hence the coast-lands of the ,pacific and the ,east ,indies1 the borders of the ,caribbean ,sea1 the volcanic ridges of the ,atlantic basin1 the lands of the ,mediterranean1 the ,black ,sea1 and the ,aralo-,caspian depressions1 the shores of the ,red ,sea1 and vast tracts of southern ,asia1 are the chief earthquake regions of the globe4 ,it may be noted1 further1 that shocks are not only most frequent but most intense in the neighbourhood of the sea4 ,they appear to originate sometimes in the volcanic ridges and coastal ranges1 sometimes under the floor of the sea itself4 ,now earthquakes1 volcanoes1 and uplifts are all expressions of the one great fundamental fact that the earth is a cooling and contracting body1 and they indicate the lines of weakness along which the enormous pressures and strains induced by the subsidence of the crust upon its nucleus find relief4 ,we cannot tell why the coast-lands of the ,atlantic should have attained at so early a period a stage of relative stability--why no axial uplifts should have been developed along their margins since ,palozoic times4 ,it may be that relief has been found in the wrinkling-up of the floor of the oceanic trough1 and consequent formation of the ,dolphin ,ridge and other great submarine foldings of the crust2 and it is possible that the growth of similar great ridges and wrinkles upon the bed of the ,pacific may in like manner relieve the coast-lands of that vast ocean1 and prevent the formation of younger uplifts along their borders4 ,i have already remarked that two kinds of elevatory movements of the crust are recognised by geologists--namely1 axial and regional uplifts4 ,some1 however1 are beginning to doubt1 with ,professor ,suess1 whether any vast regional uplifts are possible4 ,yet the view that would attribute all such apparent elevations of the land to subsidence of the crust under the great oceanic troughs is not without its difficulties4 ,former sea-margins of very recent geological age occur in all latitudes1 and if we are to explain these by sub-oceanic depression1 this will compel us to admit1 as ,suess has remarked1 a general lowering of the sea-level of upwards of #ajjj feet4 ,but it is difficult to believe that the sea-floor could have subsided to such an extent in recent times4 ,suess thinks it is much more probable that the high-level beaches of tropical regions are not contemporaneous with those of higher latitudes1 and that the phenomena are best explained by his hypothesis of a secular movement of the ocean--the water being1 as he contends1 alternately heaped up at the equator and the poles4 ,the strand-lines in high latitudes1 however1 are certainly connected with glaciation in some way not yet understood2 and if it cannot be confidently affirmed that they indicate regional movements of the land1 the evidence1 nevertheless1 seems to point in that direction4 ,in concluding this imperfect outline-sketch of a large subject1 ,i ought perhaps to apologise for having trespassed so much upon the domains of geology4 ,but in doing so ,i have only followed the example of geologists themselves1 whose divagations in territories adjoining their own are naturally not infrequent4 ,from much that ,i have said1 it will be gathered that with regard to the causes of many coastal changes we are still groping in the dark4 ,it seems not unlikely1 however1 that as light increases we may be compelled to modify the view that all oscillations of the sea-level are due to movements of the lithosphere alone4 ,that is a very heretical suggestion2 but that a great deal can be said for it any one will admit after a candid perusal of ,suess's monumental work1 ,das ,antlitz der ,erde4 ,illustration3 ,,plate ,,vi ,,bathy-,,hypsometrical ,,map ,,of ,,the ,,world ,,note ,the map is coloured to show the surface relief of the ,globe without water in the ,ocean ,basins4 ,,explanation ,,of ,,colouring ,the ,colouring is graded from the ,darkest ,tint at the ,highest ,level to the ,lightest ,tint on the ,lowest4 ,the ,edinburgh ,geographical ,institute ,j4 ,g4 ,bartholomew ,f4,r4,g4,s4 ,,edinburgh ,,printed ,,by ,,st ,,giles' ,,printing ,,company1 #cb ,,york ,,place4 ,,the ,,end4 ,other ,works by ,professor ,james ,geikie4 ---------------------------------------- ------------------------- ,the ,great ,ice ,age4 7,new ,edition in ,preparation47 ,medium #hvo4 ,maps and ,illustrations4 ,price1 #bds4 ,prehistoric ,europe3 ,a ,geological ,sketch4 ,demy #hvo4 ,maps and ,illustrations4 ,price1 #bes4 ,outlines of ,geology3 ,for ,junior ,students and ,general ,readers4 ,post #hvo4 ,illustrations4 ,price1 #abs4 ,songs and ,lyrics1 by ,heinrich ,heine and other ,german ,poets2 done into ,english ,verse4 ,price1 #ds4 ---------------------------------------- ------------------------- 99 99 99 99 99 ,transcriber's ,note ,hyphenation was not standardized4 ,the section labeled ,explanation of ,plate ,,iii4 7p4 #cbe7 in the original printed version appears to describe ,plate ,,iv and changed accordingly4 ,paragraphs split by illustrations were rejoined4 ,some plates were moved to end of the chapter4