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Romance of Modern Geology

<h2 class="nobreak" id="CHAPTER_XXIII">CHAPTER XXIII</h2> <h3>THE ICE AGE</h3></div> For some reason or reasons concerning which there has been a great deal of speculation but not a large amount of agreement, the closing stages of the last geologic era which precedes our own and which links the great past to the present, were distinguished by great cold and by widespread fields of ice. Ice-sheets spread over six or eight million square miles of the earth's surface where not long before mild climates had prevailed. Were it not for this great Ice Age and for its far-reaching effects on the conditions under which Man has developed, this period, which is sometimes called the Pleistocene, (from Greek words meaning the "most recent"), would be more properly joined to the era which we have just been discussing, the two periods constituting a single period of great land elevation and of ocean-shrinking. This period, however, is now thought to be much more important than it was formerly, and perhaps longer in duration. More than half the ice-covered land lay in North America and more than half the rest in Europe. The glaciation, therefore, was probably confined to certain parts of the world and did not stretch all over the planet. -270- But the whole world felt its effects; even in tropical regions ice and glaciers occurred on mountains where they did not exist before and do not exist now, and on mountains which now have glaciers the ice descended to levels 5000 feet below the point where it now stops. The southern hemisphere was affected as well as the northern, but to a much less degree. In Patagonia and New Zealand glaciers crept down from the mountains and spread out on the plains. Glaciers formed on the mountainous tracts of Tasmania and Australia where none exist now. Most of the higher mountains of the southern hemisphere bore glaciers. The Antarctic regions were presumably buried beneath ice and snow as they are at present, but of that we are not certain. In Asia ice-fields far greater than those existing to-day affected the higher mountains, and from the Lebanon to the Caucasus and from the Himalayas to Siberia and China traces of glaciers are found where they are not to be seen now. Yet on the plateaux and lowlands of Asia ice-sheets were far less extensive than in Europe and in North America. In Europe there were large glaciers in the southern mountains and extensive ice-sheets on the southern plains. Radiating from the Scandinavian highlands a succession of great ice-sheets crept forth on the lowlands of Russia, Germany, Denmark, Holland, and Belgium, and crossing the shallow basin of the North Sea touched the shores of Great Britain, where they were met by ice radiating from the mountains of these isles. From the Alps gigantic glaciers descended to the lowlands -271- in all directions. Then the Rhine glacier moved out far beyond the mountains and joined with the glaciers of Savoy and Dauphiny on the plains of France, while from the Southern Alps glaciers invaded the fertile plains of Italy. Glaciers of similar size and extent descended into the valleys of the Rhine and Danube. The Pyrenees, some of the higher mountains of the Spanish plateau, the higher mountains of France, the Apennines, the Carpathians, the Balkans, the Urals, all had their ice-sheets. Iceland and the Faroe Islands were buried under ice, and even Corsica had snowfields and glaciers, some of which were not small. Nearly one half of North America was buried in ice. Strangely enough, it was not the whole northern half, but the north-eastern half that was specially ice-invaded, and, more strangely still, not so much the mountainous portions, though these were affected, as the plains. Alaska was largely free from ice except on or about the mountains: and there was less ice on the western plains than in the valley of the Mississippi. Much the greater part of the four million square miles of ice-field lay on the plains of Canada and in the upper Mississippi valley. The Missouri and Ohio rivers like two great arms embraced the borders of the ice-fields to which they owe their origin. We do not propose to examine the several theories which have been proposed to account for this extraordinary cold, for none is completely acceptable or accepted, but we may just mention them. Dr. Croll a -272- century ago suggested that the cold may have been due to the alterations in the shape of the earth's orbit, alterations which astronomers tell us take place regularly, though very slowly and at intervals of millions of years. If so, this glacial period was only the last of many glacial periods; the traces of the earlier ones having, however, been for the most part obliterated and destroyed. Sir Charles Lyell has urged that geographical changes (elevations and subsidences) would of themselves be sufficient to bring about a glacial period, which (he says) would be the result of a great continent being formed round the North Pole while oceanic conditions prevailed at the Equator. Another theory is that the heat given out by the sun is not always equal, being sometimes more (when even polar countries enjoy a warm climate) and sometimes less (when only the equatorial regions are habitable). The objection to this theory is, of course, that we have no proof that our sun is of greatly variable heat. Whatever may have been the cause of the glacial period, we know as a proved fact that a long time ago (as measured by years, although the event itself is among the latest of the many changes recorded in the geological history of the earth) the climate of the British Isles was so intensely cold that the greater part of this country was covered with ice and snow, and we know also that this intense cold was sufficient to change in many respects the habits and appearance of the animals and vegetation of the earth. How much this was the case can be gathered from the fact that in the -273- period which preceded it animals which now live in the tropics roamed in the Arctic circle, and figs and magnolias grew in Greenland. The last word we shall have to say on the climatic conditions of this period is that the Ice Age had its sub-periods and divisions like all other epochs and in them the ice sometimes retreated, and consequently in parts of the earth where there had been snow and ice, and where there were to be ice and snow again, the wintry conditions retreated (for centuries, perhaps, at a time), and the valleys and plains basked during these intervals in sun and rain and warmth. These epochs are called "inter-glacial epochs." The life of the regions not much affected by the rigours of snow and ice is gradually being ascertained by geologists now. One of its most marked features was the retreat of the northern and Asiatic animals before the advancing ice towards the warmer tropics and Equator; these animals journeyed back northward again whenever the retreating ice would let them. The great Proboscideans, the Mastodon and the Mammoth were members of this group, and so were the bear, the bison, the musk ox. With these mingled towards the south several types (which were gradually becoming extinct in North America) such as the horse, tapir, llama, and the sabre-tooth cat. A second prominent feature was a southern group in the western hemisphere, consisting of gigantic sloths, armadillos, and water-hogs; and now for the first time the interest of animal life shifts to South America. -274- "There are many instances," says Sir Edward Ray Lankester in his book on Extinct Animals, "in which small living animals were represented in the past by gigantic forms very close in structure to the little living beasts, but of much greater size. Hence it is concluded that these particular living animals are the reduced and dwindled representatives of a race of primeval monsters. There is some truth in this, as may be seen from the history of the living sloths and armadillos of South America, as compared with the extinct gigantic sloths and armadillos dug up in that country. But it is a great mistake to conclude from this that it is a law of nature that recent animals are all small and insignificant as compared with their representatives in the past. That is simply not true. Recent horses are bigger than extinct ones; recent elephants are much bigger than their earlier elephantine ancestors. There never has been any creature of any kind—mammal, reptile, bird, or fish—in any geological period we know of, so big as some of the existing whales, the Sperm Whale, the great Rorqual, and the whalebone whales. "It is true that there were enormous reptiles in the past, far larger than any living crocodiles, standing fourteen feet at the loins, and measuring eighty feet from the tip of the snout to the end of the tail; but their bodies did not weigh much more than a big African elephant, and were small compared with whales. So let us be under no illusions as to extinct monsters, and proceed to look at those of South America with simple courage and confidence in our own day." -275- The peculiar productions of South America in the way of animals appear to be the members of the group of mammals called Edentata found nowhere else. When, however, South America, which once was an island, joined on to North America, numbers of animals, mastodons, horses, tigers, and tapirs, emigrated from north to south, and perhaps proved too much for the aboriginal or native beasts. At any rate, all the big South American mammals died out, and now there are left only the small tree sloths, the small armadillos, and the strange-looking ant-eaters. But in quite late geological deposits of South America we find the bones of gigantic armadillos and of gigantic ground sloths, which lasted on till the time when man appeared on the scene. The Glyptodon, of which there were several different kinds, was an enormous armadillo as big as an ox. Like their small, puny, modern descendants, they carried on their backs a hard case of bones, something like the shell of a tortoise. The modern armadillo's shell, however, is jointed so that the little animal can roll itself up into a ball, and in this direction, therefore, the armadillo, though it has decreased so much in size, has advanced in adaptability. The Megatherium was nearly as big as an elephant, and its skeleton, though so much larger, is very similar to those of the small sloths of present-day South America. Its teeth also are very much like theirs. But whereas the living sloths climb trees, as they have learnt to do, the Megatherium's method was more primitive though -276- quite as effective. It stood on the ground and pulled the trees down in order to eat the young branches. The Mylodon, which lived at the same time, was not so big, and its habits were similar. It had a number of little bony pieces scattered in its skin in the region of the back, like the pieces forming the bony case of the ancient armadillos; but the pieces in this case were not closely fitted together. It was supposed that the Mylodon, like all the peculiar gigantic animals of South America, had become extinct as long ago as the Mammoth (of which we shall say more presently) or of the woolly rhinoceros which used to haunt Fleet Street. All these extinct South American animals were distinguished by peculiarly shaped teeth, and had no teeth at all in front. They are called, therefore, Edentata, and their representatives to-day are much smaller. But some years ago Dr. Nordenskjold, a Scandinavian traveller, while exploring in Patagonia, found a vast cavern called the Ultima Speranza cave, on the western coast. From this cavern the settlers who lived close by had removed an enormous piece of skin covered with greenish-brown hair, and studded on its inner side with little knobs of bone. The skin was dry but sound. When it was placed in water it gave out a smell which, though unpleasant, was very interesting, for it showed that the animal which had worn it could not have been dead thousands or even many hundreds of years. It was, in fact, evidently a piece of the skin of a Mylodon, which had survived in this region until modern times. -277- Further explorations were made in the cavern by Dr. Moreno, of La Plata, and other naturalists, and an immense quantity of bones was obtained, and more portions of the skin of Mylodon with the hair on. The cavern had been inhabited probably several centuries ago by Indians, for human bones and weapons were obtained. The remains of as many as twenty Mylodons have been obtained from the cavern, and many of the bones are cut or broken in a way which leads us to suspect that the human inhabitants of the cave cut up the dead Mylodons for food, and split their bones to obtain the marrow! Some of the Mylodon bones, skulls, jaw-bones, leg-bones, etc., are smeared with blood and have pieces of cartilage and tendon attached. There are other evidences which go to show that the Indians may have kept the Mylodons alive in the cave and fed them with hay brought from the outside. Anybody who would care to see the last of the great extinct animals can inspect some of these remains at the museum in Cromwell Road, London. Besides the relics of the Mylodon and of Man the cavern has yielded bones and teeth, and many horny hoofs belonging to a kind of extinct horses; and this constitutes one of the puzzling things about this cave treasure. The cave is in a part of the country very difficult to reach, and though Sir Thomas Holdich and Mr. Hesketh Prichard made efforts to reach it again and explore it systematically and scientifically, there is -278- a great deal about it that seems likely to remain unexplained. The bones that were found are not buried in lime or any preserving stone; but lie in sand where one would expect them to have perished long ago if they had been of any great age. Yet side by side with them are the bones of a long-extinct horse; and there is no tradition among the Indians to-day of any huge beast corresponding to the Mylodon. Sir E. Ray Lankester has pointed out that the whole of South America has been submerged and has risen (and is rising still) for many centuries. Possibly the rocks and high lands where the Mylodon cavern occurs formed an island during the submergence, where a number of early animals took refuge and survived until the re-elevation of the land—and so lived on in the present condition of the land surface until fifty or a hundred years ago. The great land tortoises (like the Galapagan[17] tortoise) have similarly survived on a few equatorial islands. Possibly, though it does not seem very likely, the Mylodon is still living in similar caverns in this region, as yet unvisited by man. <div class="footnote"> [17] Of the Galapagos Islands. </div> In Australia, the land of the marsupials or mammals with pouches, the bones of many gigantic creatures belonging to that tribe of animal have been found. Giant kangaroos, twice as tall as the biggest living kangaroo, wombats and voles as big as a rhinoceros, have been discovered. One of these is the Diprotodon, which Sir Richard Owen reconstructed much in the same way that he reconstructed the Moa, and of which Dr. Stirling has since found complete specimens in a morass in South Australia. <div class="figcenter"> <ANTIMG class="w100" src="images/fpage278.png" width-obs="452" height-obs="643" alt="" /> <div class="figcaption">Diprotodon Equal in size to a large rhinoceros. (Remains found in Australia.) </div> </div> -279- Last of all of the great extinct mammals which we shall mention is the Mammoth, which has a peculiar interest because, like the Mylodon, it certainly survived until man was on the earth, as there are many more evidences to prove. In one of the caves of France inhabited by prehistoric men and thickly strewn with the chipped flints which they used as tools and weapons, as well as with the bones of extinct animals which they ate, a piece of Mammoth's tusk has been found on which is rudely but cleverly carved, evidently by the men who lived there, the picture of a Mammoth. (There are besides, antlers on which a reindeer is very cleverly and artistically outlined. Even the tuft of hair below the chin is shown, and the great feet and the extra toes are correctly pictured. Clearly the men who drew this reindeer lived with the reindeer; and besides the reindeer, living near these men in the south of France, was the great Mammoth.) The Mammoth was like an Indian elephant, but with a coarse hairy pelt. It was rather bigger than the big Indian elephant, and its tusks had a different curvature; but we may dispose of the popular idea that it was bigger than any elephant. No Siberian Mammoth has yet been found higher at the shoulders than nine feet six inches, whereas the African elephant stands eleven -280- feet and sometimes more at the shoulders. Among the fossil elephants of Southern Europe and of North America (Elephas imperator) there are two which stood from twelve to thirteen feet high. The remains of the Mammoth are left all over the north of Europe and Asia and of the countries which were subjected to glacial influences. Even in England its teeth and tusks are constantly found, and in the Natural History Museum there is a whole skull with enormous tusks, which was dug up in a brickfield at Ilford. Probably this animal continued to exist longer in Asia and Siberia than in our own part of the world: and the cold and ice preserved their remains so well that whole carcases have been dug up. One such instance is historic. In 1799 a native chief near Lake Onkoul, in Siberia, while seeking for Mammoth teeth, perceived a great shapeless mass among the ice. He watched it for some years, till at the end of the fifth year the ice melted and disclosed the carcase of a whole Mammoth. In the month of March, 1804, Schumakhoff cut off the horns (the tusks), which he exchanged with the merchant Bultunof for goods of the value of fifty roubles (not quite eight pounds sterling). It was not till two years after this that Mr. Adams, of the St. Petersburg Academy, who was travelling with Count Golovkin, sent by the Czar of Russia on an embassy to China, having been told at Yakutsk of the discovery of an animal of extraordinary magnitude on the shores of the Frozen Ocean, near the mouth of the River Lena, -281- betook himself to the place. He found the Mammoth still in the same place, but very much mutilated. The Yakuts of the neighbourhood had cut off the flesh, with which they fed their dogs; wild beasts, such as white bears, wolves, wolverenes, and foxes, had also fed upon it, and traces of their footsteps were seen around. The skeleton, almost entirely cleared of its flesh, remained whole, with the exception of one foreleg. The spine of the back, one scapula, the pelvis, and the other three limbs were still held together by the ligaments and by parts of the skin; the other scapula was found not far off. The head was covered with a dry skin; one of the ears was furnished with a tuft of hairs; the balls of the eyes were still distinguishable; the brain still occupied the cranium, but seemed dried up; the point of the lower lip had been gnawed and the upper lip had been destroyed so as to expose the teeth; the neck was furnished with a long flowing mane; the skin, of a dark-grey colour, covered with black hairs and a reddish wool, was so heavy that ten persons found great difficulty in transporting it to the shore. There was collected, according to Mr. Adams, more than thirty-six pounds weight of hair and wool which the white bears had trod into the ground while devouring the flesh. This Mammoth was a male, so fat and well fed, according to the assertion of the Tungusian chief, that its belly hung down below the joints of its knees. Its tusks were nine feet six inches in length, measured along the curve, and its head without the tusks weighed four hundred and fourteen pounds -282- avoirdupois. Mr. Adams took every care to collect all that remained of this unique specimen of an ancient creation, and forwarded the parts to St. Petersburg, a distance of 11,000 versts (7330 miles). He succeeded in repurchasing what he believed to be the tusks at Yakutsk, and the Emperor of Russia, who became the owner of this precious relic, paid him 8000 roubles. The skeleton is deposited in the museum of the Academy of St. Petersburg, and the skin still remains attached to the head and the feet. A very curious example of the Siberian Mammoth was discovered only a few years ago by a Lamut of one of the Arctic villages, and through the energy of Dr. Herz was eventually removed in pieces to St. Petersburg. In the Zoological Museum there the reconstructed Mammoth now crawls out of a huge pit, for it was by falling into a pit that this fine beast met his death hundreds of generations ago. It was sunk in frozen ground, and this cold-storage treatment had preserved it in an extraordinary manner. If the Siberian natives who discovered it partially buried in alluvial deposit had not uncovered it, so that the sun was able to play on the carcase and produced decay, this wonderful primeval monster might almost have been got out whole. As it was the frozen ground had so kept the remains that Dr. Herz found well-preserved fragments of food between the teeth, and the remains of a hearty meal in the stomach. There is no doubt that the Mammoth fell into the crevice or pit and damaged himself so much -283- in the fall that he could not crawl out. One cannot help feeling some relief that he died after a short death-struggle. A good deal of the very old meat of this body was eagerly eaten by the native dogs. <hr class="chap x-ebookmaker-drop" /> -284- <div style="break-after:column;"></div>

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