Chapter 9

[AJ]The phenomena of this period, with reference to rainfall, melting snows, and valley deposits, must be noticed in the next chapter.

This table will suffice at least to reduce the great glacier controversy to its narrowest limits, when we have added the one further consideration that glaciers are the parents of icebergs, and that the question is not of one or the other exclusively, but of the relative predominance of the one or the other in certain given times and places. Both theories admit a great Post-pliocene subsidence. The abettors of glaciers can urge the elevation of the surface, the supposed powers of glaciers as eroding agents, and the transport of boulders. Those whose theoretical views lean to floating ice, believe that they can equally account for these phenomena, and can urge in support of their theory the occurrence of drift wood in the inland clay and boulder clay, and of sea-shells in the marginal clay and boulder clay, and the atmospheric decomposition of rock in the Pliocene period, as a source of the material of the clays, while to similar causes they can attribute the erosion of the deep valleys piled with the Post-pliocene deposits. They can also maintain that the general direction of striation and drift implies the action of sea currents, while they appeal to local glaciers to account for special cases of glaciated rocks at the higher levels.

How long our continental plateaus remained under the icy seas of the Glacial period we do not know. Relatively to human chronology, it was no doubt a long time; but short in comparison with those older subsidences in which the great PalÃ¦ozoic limestones were produced. At length, however, the changecame. Slowly and gradually, or by intermittent lifts, the land rose: and as it did so, shallow-water sands and gravels were deposited on the surface of the deep-sea clays, and the sides of the hills were cut into inland cliffs and terraces, marking the stages of recession of the waters. At length, when the process was complete, our present continents stood forth in their existing proportions ready for the occupancy of man.

The picture which these changes present to the imagination is one of the most extraordinary in all geological history. We have been familiar with the idea of worlds drowned in water, and the primeval incandescent earth shows us the possibility of our globe being melted with fervent heat; but here we have a world apparently frozen out destroyed by cold, or doubly destroyed by ice and water. Let us endeavour to realise this revolution, as it may have occurred in any of the temperate regions of the Northern Hemisphere, thickly peopled with the magnificent animals that had come down from the grand old Miocene time. Gradually the warm and equable temperature gives place to cold winters and chilly wet summers. The more tender animals die out, and the less hardy plants begin to be winter-killed, or to fail to perfect their fruits. As the forests are thus decimated, other and hardier species replace those which disappear. The animals which have had to confine themselves to sheltered spots, or which have perished through cold or want of food, are replaced by others migrating from the mountains, orfrom colder regions. Some, perhaps, in the course of generations, become dwarfed in stature, and covered with more shaggy fur. Permanent snow at length appears upon the hill-tops, and glaciers plough their way downward, devastating the forests, encroaching on the fertile plains, and at length reaching the heads of the bays and fiords. While snow and ice are thus encroaching from above, the land is subsiding, and the sea is advancing upon it, while great icebergs drifting on the coasts still further reduce the temperature. Torrents and avalanches from the hills carry mud and gravel over the plains. Peat bogs accumulate in the hollows. Glaciers heap up confused masses of moraine, and the advancing sea piles up stones and shingle to be imbedded in mud on its further advance, while boreal marine animals invade the now submerged plains. At length the ice and water meet everywhere, or leave only a few green strips where hardy Arctic plants still survive, and a few well-clad animals manage to protract their existence. Perhaps even these are overwhelmed, and the curtain of the Glacial winter falls over the fair scenery of the Pliocene. In every locality thus invaded by an apparently perpetual winter, some species of laud animals must have perished. Others may have migrated to more genial climes, others under depauperated and hardy varietal forms may have continued successfully to struggle for existence. The general result must have been greatly to diminish the nobler forms of life, and to encourage only those fittedfor the most rigorous climates and least productive soils.

Could we have visited the world in this dreary period, and have witnessed the decadence and death of that brilliant and magnificent flora and fauna which we have traced upward from the Eocene, we might well have despaired of the earthâ€™s destinies, and have fancied it the sport of some malignant demon; or have supposed that in the contest between the powers of destruction and those of renovation the former had finally gained the victory. We must observe, however, that the suffering in such a process is less than we might suppose. So long as animals could exist, they would continue to enjoy life. The conditions unfavourable to them would be equally or more so to their natural enemies. Only the last survivors would meet with what might be regarded as a tragical end. As one description of animal became extinct, another was prepared to occupy its room. If elephants and rhinoceroses perished from the land, countless herds of walruses and seals took their places. If gay insects died and disappeared, shell-fishes and sea-stars were their successors.

Thus in nature there is life even in death, and constant enjoyment even when old systems are passing away. But could we have survived the Glacial period, we should have seen a reason for its apparently wholesale destruction. Out of that chaos came at length an Eden; and just as the Permian prepared the way for the Mesozoic, so the glaciers and icebergsof the Post-pliocene were the ploughshare of God preparing the earth for the time when, with a flora and fauna more beautiful and useful, if less magnificent than that of the Tertiary, it became as the garden of the Lord, fitted for the reception of His image and likeness, immortal and intelligent Man. We need not, however, with one modern school of philosophy, regard man himself as but a descendant of Miocene apes, scourged into reason and humanity by the struggle for existence in the Glacial period. We may be content to consider him as a son of God, and to study in the succeeding chapters that renewal of the Post-pliocene world which preceded and heralded his advent.

In the meantime, our illustration,[AK]borrowed in part from the magnificent representation of the Post-pliocene fauna of England, by the great restorer of extinct animals, Mr. Waterhouse Hawkins, may serve to give some idea of the grand and massive forms of animal life which, even in the higher latitudes, survived the Post-pliocene cold, and only decayed and disappeared under that amelioration of physical conditions which marks the introduction of the human period.

[AK]Page 301.

CHAPTER XII.

CLOSE OF THE POST-PLIOCENE, AND ADVENT OF MAN.

Inclosing these sketches it may seem unsatisfactory not to link the geological ages with the modern period in which we live; yet, perhaps, nothing is more complicated or encompassed with greater difficulties or uncertainties. The geologist, emerging from the study of the older monuments of the earthâ€™s history, and working with the methods of physical science, here meets face to face the archÃ¦ologist and historian, who have been tracing back in the opposite direction, and with very different appliances, the stream of human history and tradition. In such circumstances conflicts may occur, or at least the two paths of inquiry may refuse to connect themselves without concessions unpleasant to the pursuers of one or both. Further, it is just at this meeting-place that the dim candle of traditional lore is almost burnt out in the hand of the antiquary, and that the geologist finds his monumental evidence becoming more scanty and less distinct. We cannot hope as yet to dispel all the shadows that haunt this obscure domain, but can at least point out some of the paths which traverse it. In attempting this, we may first classify the time involved as follows: (1) The earlier Post-plioceneperiod of geology may be called theGlacialera. It is that of a cold climate, accompanied by glaciation and boulder deposits. (2) The later Post-pliocene may be called thePost-glacialera. It is that of re-elevation of the continents and restoration of a mild temperature. It connects itself with the pre-historic period of the archÃ¦ologist, inasmuch as remains of man and his works are apparently included in the same deposits which hold the bones of Post-glacial animals. (3) TheModernera is that of secular human history.

It may be stated with certainty that the Pliocene period of geology affords no trace of human remains or implements; and the same may I think be affirmed of the period of glaciation and subsidence which constitutes the earlier Post-pliocene. With the rise of the land out of the Glacial sea indications of man are believed to appear, along with remains of several mammalian species now his contemporaries. ArchÃ¦ology and geology thus meet somewhere in the pre-historic period of the former, and in the Post-glacial of the latter. Wherever, therefore, human history extends farthest back, and geological formations of the most modern periods exist and have been explored, we may expect best to define their junctions. Unfortunately it happens that our information on these points is still very incomplete and locally limited. In many extensive regions, like America and Australia, while the geological record is somewhat complete, the historic record extends back at most a few centuries, and thepre-historic monuments are of uncertain date. In other countries, as in Western Asia and Egypt, where the historic record extends very far back, the geology is less perfectly known. At the present moment, therefore, the main battle-field of these controversies is in Western Europe, where, though history scarce extends farther back than the time of the Roman Republic, the geologic record is very complete, and has been explored with some thoroughness. It is obvious, however, that we thus have to face the question at a point where the pre-historic gap is necessarily very wide.

Taking England as an example, all before the Roman invasion is pre-historic, and with regard to this pre-historic period the evidence that we can obtain is chiefly of a geological character. The pre-historic men are essentially fossils. We know of them merely what can be learned from their bones and implements embedded in the soil or in the earth of the caverns in which some of them sheltered themselves. For the origin and date of these deposits the antiquary must go to the geologist, and he imitates the geologist in arranging his human fossils under such names as the â€œPaleolithic,â€ or period of rude stone implements; the â€œNeolithicâ€ or period of polished stone implements; the Bronze Period, and the Iron Period; though inasmuch as higher and lower states of the arts seem always to have coexisted, and the time involved is comparatively short, these periods are offar less value than those of geology. In Britain the age of iron is in the main historic. That of bronze goes back to the times of early Phoenician trade with the south of England. That of stone, while locally extending far into the succeeding ages, reaches back into an unknown antiquity, and is, as we shall see in the sequel, probably divided into two by a great physical change, though not in the abrupt and arbitrary way sometimes assumed by those who base their classification solely on the rude or polished character of stone implements. We must not forget, however, that in Western Asia the ages of bronze and iron may have begun two thousand years at least earlier than in Britain, and that in some parts of America the Palaeolithic age of chipped stone implements still continues. We must also bear in mind that when the archÃ¦ologist appeals to the geologist for aid, he thereby leaves that kind of investigation in which dates are settled by years, for that in which they are marked merely by successive physical and organic changes.

Turning, then, to our familiar geological methods, and confining ourselves mainly to the Northern Hemisphere and to Western Europe, two pictures present themselves to us: (!) The physical changes preceding the advent of man; (2) The decadence of the land animals of the Post-pliocene age, and the appearance of those of the modern.

In the last chapter I had to introduce the readerto a great and terrible revolution, whereby the old Pliocene continents, with all their wealth of animals and plants, became sealed up in a mantle of Greenland ice, or, slowly sinking beneath the level of the sea, were transformed into an ocean-bottom over which icebergs bore their freight of clay and boulders. We also saw that as the Post-pliocene age advanced, the latter condition prevailed, until the waters stood more than a thousand feet deep over the plains of Europe. In this great glacial submergence, which closed the earlier Post-pliocene period, and over vast areas of the Northern Hemisphere, terminated the existence of many of the noblest forms of life, it is believed that man had no share. We have, at least as yet, no record of his presence.

Out of these waters the land again rose slowly and intermittently, so that the receding waves worked even out of hard rocks ranges of coast cliff which the further elevation converted into inland terraces, and that the clay and stones deposited by the Glacial waters were in many places worked over and rearranged by the tides and waves of the shallowing sea before they were permanently raised up to undergo the action of the rains and streams, while long banks of sand and gravel were stretched across plains and the mouths of valleys, constituting â€œkames,â€ or â€œeskers,â€ only to be distinguished from moraines of glaciers by the stratified arrangement of their materials.

Further, as the land rose, its surface was greatly and rapidly modified by rains and streams. There is the amplest evidence, both in Europe and America, that at this time the erosion by these means was enormous in comparison with anything we now experience. The rainfall must have been excessive, the volume of water in the streams very great; and the facilities for cutting channels in the old Pliocene valleys, filled to the brim with mud and boulder-clay, were unprecedented. While the area of the land was still limited, much of it would be high and broken, and it would have all the dampness of an insular climate. As it rose in height, plains which had, while under the sea, been loaded with thedÃ©brisswept from the land, would be raised up to experience river erosion. It was the spring-time of the Glacial era, a spring eminent for its melting snows, its rains, and its river floods.[AL]To an observer living at this time it would have seemed as if the slow process of moulding the continents was being pushed forward with unexampled rapidity. The valleys were ploughed out and cleansed, the plains levelled and overspread with beds of alluvium, giving new features of beauty and utility to the land, and preparing the way for the life of the Modern period, as if to make up for the time which had been lost in the dreary Glacial age. It will readily be understood how puzzling these deposits havebeen to geologists, especially to those who fail to present to their minds the true conditions of the period; and how difficult it is to separate the river alluvia of this age from the deposits in the seas and estuaries, and these again from the older Glacial beds. Further, in not a few instances the animals of a cold climate must have lived in close proximity to those which belonged to ameliorated conditions, and the fossils of the older Post-pliocene must often, in the process of sorting by water, have been mixed with those of the newer.

[AL]Mr. Tylor has well designated this period as the Pluvial age.Journal of the Geological Society, 1870.

Many years ago the brilliant and penetrating intellect of Edward Forbes was directed to the question of the maximum extent of the later Post-pliocene or Post-glacial land; and his investigations into the distribution of the European flora, in connection with the phenomena of submerged terrestrial surfaces, led to the belief that the land had risen until it was both higher and more extensive than at present. At the time of greatest elevation, England was joined to the continent of Europe by a level plain, and a similar plain connected Ireland with its sister islands. Over these plains the plants constituting the â€œGermanicâ€ flora spread themselves into the area of the British Islands, and herds of mammoth, rhinoceros, and Irish elk wandered and extended their range from east to west. The deductions of Forbes have been confirmed and extended by others; and it can scarcely be doubted that in the Post-glacial era, the land regained fully the extent which it had possessed in thetime of the Pliocene. In these circumstances the loftier hills might still reach the limits of perpetual snow, but their glaciers would no longer descend to the sea. What are now the beds of shallow seas would be vast wooded plains, drained by magnificent rivers, whose main courses are now submerged, and only their branches remain as separate and distinct streams, The cold but equable climate of the Post-pliocene would now be exchanged for warm summers, alternating with sharp winters, whose severity would be mitigated by the dense forest covering, which would also contribute to the due supply of moisture, preventing the surface from being burnt into arid plains.

It seems not improbable that it was when the continents had attained to their greatest extension and when animal and vegetable life had again over-spread the new land to its utmost limits, that man was introduced on the eastern continent, and with him several mammalian species, not known in the Pliocene period, and some of which, as the sheep, the goat, the ox, and the dog, have ever since been his companions and humble allies. These, at least in the west of Europe, were the â€œPalaeolithicâ€ men, the makers of the oldest flint implements; and armed with these, they had to assert the mastery of man over broader lands than we now possess, and over many species of great animals now extinct. In thus writing, I assume the accuracy of the inferences from the occurrence of worked stones with the bones ofpost-glacial animals, which must have lived during the condition of our continents above referred to. If these inferences are well founded, not only did man exist at this time, but man not even varietally distinct from modern European races. But if man really appeared in Europe in the Post-glacial era, he was destined to be exposed to one great natural vicissitude before his permanent establishment in the world. The land had reached its maximum elevation, but its foundations, â€œstanding in the water and out of the water,â€ were not yet securely settled, and it had to take one more plunge-bath before attaining its modern fixity. This seems to have been a comparatively rapid subsidence and re-elevation, leaving but slender traces of its occurrence, but changing to some extent the levels of the continents, and failing to restore them fully to their former elevation, so that large areas of the lower grounds still remained under the sea. If, as the greater number of geologists now believe, man was then on the earth, it is not impossible that this constituted the deluge recorded in that remarkable â€œlog bookâ€ of Noah preserved to us in Genesis, and of which the memory remains in the traditions of most ancient nations. This is at least the geological deluge which separates the Post-glacial period from the Modern, and the earlier from the later pre-historic period of the archÃ¦ologists.[AM]

[AM]I have long thought that the narrative in Gen. vii. and viii. can be understood only on the supposition that it is a contemporary journal or log of an eye-witness incorporated by the author of Genesis in his work. The dates of the rising and fall of the water, the note of soundings over the hill-tops when the maximum was attained, and many other details, as well as the whole tone of the narrative, seem to require this supposition, which also removes all the difficulties of interpretation which have been so much felt.

Very important questions of time are involved in this idea of Post-glacial man, and much will depend, in the solution of these, on the views which we adopt as to the rate of subsidence and elevation of the land. If, with the majority of British geologists, we hold that it is to be measured by those slow movements now in progress, the time required will be long. If, with most Continental and some American geologists, we believe in paroxysmal movements of elevation and depression, it may be much reduced. We have seen in the progress of our inquiries that the movements of the continents seem to have occurred with accelerated rapidity in the more modern periods. We have also seen that these movements might depend on the slow contraction of the earthâ€™s crust due to cooling, but that the effects of this contraction might manifest themselves only at intervals. We have further seen that the gradual retardation of the rotation of the earth furnishes a cause capable of producing elevation and subsidence of the land, and that this also might be manifested at longer or shorter intervals, according to the strength and resisting power of the crust. Under the influence of this retardation, so long as the crust of the earth did not give way, the waters would be driven toward the poles, and thenorthern land would be submerged; but so soon as the tension became so great as to rupture the solid shell, the equatorial regions would collapse, and the northern land would again be raised. The subsidence would be gradual, the elevation paroxysmal, and perhaps intermittent. Let us suppose that this was what occurred in the Glacial period, and that the land had attained to its maximum elevation. This might not prove to be permanent; the new balance of the crust might be liable to local or general disturbance in a minor degree, leading to subsidence and partial re-elevation, following the great Post-glacial elevation. There is, therefore, nothing unreasonable in that view which makes the subsidence and re-elevation at the close of the Post-glacial period somewhat abrupt, at least when compared with some more ancient movements.

But what is the evidence of the deposits formed at this period? Here we meet with results most diverse and contradictory, but I think there can be little doubt that on this kind of evidence the time required for the Post-glacial period has been greatly exaggerated, especially by those geologists who refuse to receive such views as to subsidence and elevation as those above stated. The calculations of long time based on the gravels of the Somme, on the cone of the TiniÃ¨re, on the peat bogs of France and Denmark, on certain cavern deposits, have all been shown to be more or less at fault; and possibly none of these reach further back than the six or seven thousandyears which, according to Dr. Andrews, have elapsed since the close of the boulder-clay deposits in America.[AN]I am aware that such a statement will be regarded with surprise by many in England, where even the popular literature has been penetrated with the idea of a duration of the human period immensely long in comparison with what used to be the popular belief; but I feel convinced that the scientific pendulum must swing backward in this direction nearer to its old position. Let us look at a few of the facts. Much use has been made of the â€œconeâ€ or delta of the TiniÃ¨re on the eastern side of the Lake of Geneva, as an illustration of the duration of the Modern period. This little stream has deposited at its mouth a mass ofdÃ©briscarried down from the hills. This being cut through by a railway, is found to contain Roman remains to a depth of four feet, bronze implements to a depth of ten feet, stone implements at a depth of nineteen feet. The deposit ceased about three hundred years ago, and calculating 1300 to 1500 years for the Roman period, we should have 7000 to 10,000 years as the age of the cone. But before the formation of the present cone, another had been formed twelve times as large. Thus for the two cones together, a duration of more than 90,000 years is claimed. It appears, however, that this calculation has been made irrespective of two essential elements in the question. No allowance has been made for the fact that the inner layers of a cone aree necessarily smaller than the outer; nor for the further fact that the older cone belongs to a distinct time (the pluvial age already referred to), when the rainfall was much larger, and the transporting power of the torrent great in proportion. Making allowance for these conditions, the age of the newer cone, that holding human remains, falls between 4000 and 5000 years. The peat bed of Abbeville, in the north of France, has grown at the rate of one and a half to two inches in a century. Being twenty-six feet in thickness, the time occupied in its growth must have amounted to 20,000 years; and yet it is probably newer than some of the gravels on the same river containing flint implements. But the composition of the Abbeville peat shows that itâ€™s a forest peat, and the erect stems preserved in it prove that in the first instance it must have grown at the rate of about three feet in a century, and after the destruction of the forest its rate of increase down to the present time diminished rapidly almost to nothing. Its age is thus reduced to perhaps less than 4000 years. In 1865 I had an opportunity to examine the now celebrated gravels of St. Acheul, on the Somme, by some supposed to go back to a very ancient period. With the papers of Prestwich and other able observers in my hand, I could conclude merely that the undisturbed gravels were older than the Roman period, but how much older only detailed topographical surveys could prove; and that taking into account the probabilities of a different level of the land, awooded condition of the country, a greater rainfall, and a glacial filling of the Somme valley with clay and stones subsequently cut out by running water the gravels could scarcely be older than the Abbeville peat. To have published such views in England would have been simply to have delivered myself into the hands of the Philistines. I therefore contented myself with recording my opinion in Canada. Tylor[AO]and Andrews[AP]have, however, I think, subsequently shown that my impressions were correct. In like manner, I fail to perceive, and I think all American geologists acquainted with the pre-historic monuments of the western continent must agree with me, any evidence of great antiquity in the caves of Belgium and England, the kitchen-middens of Denmark, the rock-shelters of France, the lake habitations of Switzerland. At the same time, I would disclaim all attempt to resolve their dates into precise terms of years. I may merely add, that the elaborate and careful observations of Dr. Andrews on the raised beaches of Lake Michigan, observations of a much more precise character than any which, in so far as I know, have been made of such deposits in Europe, enable him to calculate the time which has elapsed since North America rose out of the waters of the Glacial period as between 5500 and 7500 years. This fixes at least the possible duration of the human period in North America, though I believe there areother lines of evidence which, would reduce the residence of man in America to a much shorter time. Longer periods have, it is true, been deduced from the delta of the Mississippi and the gorge of Niagara; but the deposits of the former have been found by Hilgard to be in great part marine, and the excavation of the latter began at a period probably long Anterior to the advent of man.

[AN]â€œTransactions, Chicago Academy,â€ 1871.

[AO]â€œJournal of Geological Society,â€ vol. xxv.

[AP]â€œSillimanâ€™s Journal,â€ 1868.

But another question remains. From the similarities existing in the animals and plants of regions in the southern hemisphere now widely separated by the ocean, it has been inferred that Post-pliocene land of great extent existed there; and that on this land men may have lived before the continents of the northern hemisphere were ready for them. It has even been supposed that, inasmuch as the flora and fauna of Australia have an aspect like that of the Eocene Tertiary, and very low forms of man exist in that part of the world, these low races are the oldest of all, and may date from Tertiary times. Positive evidence of this, however, there is none. These races have no monuments; nor, so far as known, have they left their remains in Post-pliocene deposits. It depends on the assumptions that the ruder races of men are the oldest; and that man has no greater migratory powers than other animals. The first is probably false, as being contrary to history; and also to the testimony of palaeontology with reference to the laws of creation. The second is certainly false; for we know that man has managedto associate himself with every existing fauna and flora, even in modern times; and that the most modern races have pitched their tents amid tree-ferns and ProteaceÃ¦, and have hunted kangaroos and emus. Further, when we consider that the productions of the southern hemisphere are not only more antique than those of the northern, but, on the whole, less suited for the comfortable subsistence of man and the animals most useful to him; and that the Post-pliocene animals of the southern hemisphere were of similar types with their modern successors, we are the less inclined to believe that these regionswould be selected as the cradle of the human race.

CONDENSED TABULAR VIEW NEOZOICClick on table to view larger version.

CHAPTER XIII.

CLOSE OF THE POST-PLIOCENE, AND ADVENT OF MAN.(Continued.)

Turningfrom these difficult questions of time, we may now look at the assemblage of land-animals presented by the Post-glacial period. Here, for the first time in the great series of continental elevations and depressions, we find the newly-emerging land peopled with familiar forms. Nearly all the modern European animals have left their bones in the clays, gravels, and cavern deposits which belong to this period; but with them are others either not now found within the limits of temperate Europe, or altogether extinct. Thus the remarkable fact comes out, that the uprising land was peopled at first with a more abundant fauna than that which it now sustains, and that many species, and among these some of the largest and most powerful, have been weeded out, either before the advent of man or in the changes which immediately succeeded that event. That in the Post-glacial period so many noble animal species should have been overthrown in the struggle for existence, without leaving any successors, at least in Europe, is one of the most remarkable phenomena in the history of life on our planet.

According to. Pictet,[AQ]the Post-glacial beds of Europe afford ninety-eight species of mammals, of which fifty-seven still live there, the remainder being either locally or wholly extinct. According to Mr. Boyd Dawkins,[AR]in Great Britain about twelve Pliocene species survived the Glacial period, and reappeared in the British Islands in the Post-glacial. To these were added forty-one species making in all fifty-three, whose remains are found in the gravels and caves of the latter period. Of these, in the Modern period twenty-eight, or rather more than one-half, survive, fourteen are wholly extinct, and eleven are locally extinct.

[AQ]PalÃ¦ontologie.

[AR]â€œJournal of Geological Society,â€ and PalÃ¦ontographical Societyâ€™s publications.

BRITAIN IN THE POST-PLIOCENE AGE.Musk-sheep, Hippopotamus, Machairodus, Mammoth, Wooly Rhinoceros, Long-fronted Ox, and Irish stag. The animals are taken from Mr. Waterhouse Hawkinsâ€™s picture, â€œStruggles of Life among British Animals of the Antediluvian Times.â€ London: 1853. The landscape is that of the later part of the cold Post-pliocene period.

Among the extinct beasts, were some of very remarkable character. There were two or more species of elephant, which seem in this age to have overspread, in vast herds, all the plains of Northern Europe and Asia; and one of which we know, from the perfect specimen found embedded in the frozen soil of Siberia, lived till a very modern period; and was clothed with long hair and fur, fitting it for a cold climate. There were also three or four species of rhinoceros, one of which at least (theR. Tichorhinus) was clad with wool like the great Siberian mammoth. With these was a huge hippopotamus (H. major), whose head-quarters would, however, seem to have been farther south than England, or which perhaps inhabited chiefly the swamps along the large rivers running through areas now under the sea. The occurrence of such an animal shows an abundant vegetation, and a climate so mild, that the rivers were not covered with heavy ice in winter; for the supposition that this old hippopotamus was a migratory animal seems very unlikely. Another animal of this time, was the magnificent deer, known as the Irish elk; and which perhaps had its principal abode on the great plain which is now the Irish Sea. The terrible machairodus, or cymetar-toothed tiger, was continued from the Pliocene; and in addition to species of bear still living, there was a species of gigantic size, probably now extinct, the cave bear. Evidences are accumulating, to show that all or nearly all these survived until the human period.

If we turn now to those animals which are only locally extinct, we meet with some strange, and at first sight puzzling anomalies. Some of these are creatures now limited to climates much colder than that of Britain. Others now belong to warmer climates. Conspicuous among the former are the musk-sheep, the elk, the reindeer, the glutton, and the lemming. Among the latter, we see the panther, the lion, and the Cape hyena. That animals now so widely separated as the musk-sheep of Arctic America and the hyena of South Africa, could ever have inhabited the same forests, seems a dream of the wildest fancy. Yet it is not difficult to find a probable solution of the mystery. In North America, at the presentday, the puma, or American lion, comes up to the same latitudes with the caribou, or reindeer, and moose; and in Asia, the tiger extends its migrations into the abodes of boreal animals in the plains of Siberia. Even in Europe, within the historic period, the reindeer inhabited the forests of Germany; and the lion extended its range nearly as far northward. The explanation lies in the co-existence of a densely wooded country with a temperate climate; the forests affording to southern animals shelter from the cold or winter; and equally to the northern animals protection from the heat of summer. Hence our wonder at this association of animals of diverse habitudes as to climate, is merely a prejudice arising from the present exceptional condition of Europe. Still it is possible that changes unfavourable to some of these animals, were in progress before the arrival of man, with his clearings and forest fires and other disturbing agencies. Even in America, the megalonyx, or gigantic sloth, the mammoth, the mastodon, the fossil horse, and many other creatures, disappeared before the Modern period; and on both continents the great Post-glacial subsidence or deluge may have swept away some of the species. Such a supposition seems necessary to account for the phenomena of the gravel and cave deposits of England, and Cope has recently suggested it in explanation of similar storehouses of fossil animals in America.[AS]

[AS]Proceedings of the American Philosophical Society, April 1871.

Among the many pictures which this fertile subject calls up, perhaps none is more curious than that presented by the Post-glacial cavern deposits. We may close our survey of this period with the exploration of one of these strange repositories; and may select Kentâ€™s Hole at Torquay, so carefully excavated and illumined with the magnesium light of scientific inquiry by Mr. Pengelly and a committee of the British Association.

The somewhat extensive and ramifying cavern of Kentâ€™s Hole is an irregular excavation, evidently due partly to fissures in limestone rock, and partly to the erosive action of water enlarging such fissures into chambers and galleries. At what time it was originally cut we do not know, but it must have existed as a cavern at the close of the Pliocene or beginning of the Post-pliocene period, since which time it has been receiving a series of deposits which have quite filled up some of its smaller branches.

First and lowest, according to Mr. Pengelly, is a â€œbrecciaâ€ or mass of broken and rounded stones, with hardened red clay filling the interstices. Most of the stones are of the rock which forms the roof and walls of the cave, but many, especially the rounded ones, are from more distant parts of the surrounding country. In this mass, the depth of which is unknown, are numerous bones, all of one kind of animal, the cave bear, a creature which seems to have lived in Western Europe from the close of the Pliocene down to the modern period. It must have been one of theearliest and most permanent tenants of Kentâ€™s Hole at a time when its lower chambers were still filled with water. Next above the breccia is a floor of â€œstalagmiteâ€ or stony carbonate of lime, deposited from the drippings of the roof, and in some places three feet thick. This also contains bones of the cave bear, deposited when there was less access of water to the cavern. Mr. Pengelly infers the existence of man at this time from a single flint flake and a single flint chip found in these beds; but mere flakes and chips of flint are too often natural to warrant such a conclusion. After the old stalagmite floor above mentioned was formed, the cave again received deposits of muddy water and stones; but now a change occurs in the remains embedded. This stony clay, or â€œcave earthâ€ has yielded an immense quantity of teeth and bones, including those of the elephant, rhinoceros, horse, hyena, cave bear, reindeer, and Irish elk. With these were found weapons of chipped flint, and harpoons, needles, and bodkins of bone, precisely similar to those of the North American Indians and other rude races. The â€œcave earthâ€ is four feet or more in thickness, It is not stratified, and contains many fallen fragments of rock, rounded stones, and broken pieces of stalagmite. It also has patches of the excrement of hyenas, which the explorers suppose to indicate the temporary residence of these animals; and in one spot, near the top, is a limited layer of burnt wood, with remains which indicate the cooking and eating of repasts of animal food by man. It is clear that when this bed was formedthe cavern was liable to be inundated with muddy water, carrying stones and other heavy objects, and breaking up in places the old stalagmite floor. One of the most puzzling features, especially to those who take an exclusively uniformitarian view, is, that the entrance of water-borne mud and stones implies a level of the bottom of the water in the neighbouring valleys of about 100 feet above its present height. The cave earth is covered by a second crust of stalagmite, less dense and thick than that below, and containing only a few bones, which are of the same general character with those below, but include a fragment of a human jaw with teeth. Evidently, when this stalagmite was formed, the influx of water-borne materials had ceased, or nearly so; but whether the animals previously occupying the country still continued in it, or only accidental bones, etc., were introduced into the cave or lifted from the bed below, does not appear.

The next bed marks a new change. It is a layer of black mould from three to ten inches thick. Its microscopic structure does not seem to have been examined; but it is probably a forest soil, introduced by growth, by water, by wind, and by ingress of animals, at a time when the cave was nearly in its present state, and the surrounding country densely wooded. This bed contains bones of animals, all of them modern, and works of art ranging from the old British times before the Roman invasion up to the porter-bottles and dropped halfpence of modern visitors.Lastly, in and upon the black mould are many fallen blocks from the roof of the cave.

There can be no doubt that this cave and the neighbouring one of Brixham have done very much to impress the minds of British geologists with ideas of the great antiquity of man, and they have, more than any other Post-glacial monuments, shown the persistence of some animals now extinct up to the human age. Of precise data for determining time, they have, however, given nothing. The only measures which seed to have been applied, namely, the rate of growth of stalagmite and the rate of erosion of the neighbouring valleys, are, from the very sequence of the deposits, obviously worthless; and the only apparently available constant measure, namely, the fall of blocks from the roof, seems not yet to have been applied. We are therefore quite uncertain as to the number of centuries involved in the filling of this cave, and must remain so until a surer system of calculation is adopted. We may, however, attempt to sketch the series of events which it indicates.

The animals found in Kentâ€™s Hole are all â€œPost-glacial.â€ They therefore inhabited the country after it rose from the great Glacial submergence. Perhaps the first colonists of the coasts of Devonshire in this period were the cave bears, migrating on floating ice, and subsisting, like the Arctic bear, and the black bears of Anticosti, on fish, and on the garbage cast up by the sea. They found Kentâ€™s Hole a sea-side cavern, with perhaps some of its galleries still full ofwater, and filling with, breccia, with which the bones of dead bears became mixed. As the land rose, these creatures for the most part betook themselves to lower levels, and in process of time the cavern stood upon a hill-side, perhaps several hundreds of feet above the sea; and the mountain torrents, their beds not yet emptied of glacial detritus, washed into it stones and mud and carcases of animals of many species which had now swarmed across the plains elevated out of the sea, and multiplied in the land. This was the time of the cave earth; and before its deposit was completed, though how long before, a confused and often-disturbed bed of this kind cannot tell, man himself seems to have been added to the inhabitants of the British land. In pursuit of game he sometimes ascended the valleys beyond the cavern, or even penetrated into its outer chambers; or perhaps there were even in those days rude and savage hill-men, inhabiting the forests and warring with the more cultivated denizens of plains below, which are now deep under the waters. Their weapons, lost in hunting, or buried in the flesh of wounded animals which crept to the streams to assuage their thirst, are those found in the cave earth. The absence of human bones may merely show that the mighty hunters of those days were too hardy, athletic, and intelligent, often to perish from accidental causes, and that they did not use this cavern for a place of burial. But the land again subsided. The valley of that now nameless river, of which the Rhine the Thames, and the Severn may have alike been tributaries,disappeared under the sea; and some tribe, driven from the lower lands, took refuge in this cave, now again near the encroaching waves, and left there the remains of their last repasts ere they were driven farther inland or engulfed in the waters. For a time the cavern may have been wholly submerged, and the charcoal of the extinguished fires became covered with its thin coating of clay. But ere long it re-emerged to form part of an island, long barren and desolate; and the valleys having been cut deeper by the receding waters, it no longer received muddy deposits, and the crust formed by drippings from its roof contained only bones and pebbles washed by rains or occasional land floods from its own clay deposits. Finally, the modern forests overspread the land, and were tenanted by the modern animals. Man returned to use the cavern again as a place of refuge or habitation, and to leave there the relics contained in the black earth. This seems at present the only intelligible history of this curious cave and others resembling it; though, when we consider the imperfection of the results obtained even by a large amount of labour, and the difficult and confused character of the deposits in this and similar caves, too much value should not be attached to such histories, which may at any time be contradicted or modified by new facts or different explanations of those already known. The time involved depends very much, as already stated, on the question whether we regard the Post-glacial subsidence and re-elevation as somewhat sudden, or asoccupying long ages at the slow rate at which some parts of our continents are now rising or sinking.[AT]

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