Page:Encyclopædia Britannica, Ninth Edition, v. 10.djvu/383

RECENT on HUMAN rER1oD.] be no doubt that he inhabited Europe after the greatest extension of the ice, but while the rivers were still larger than now from the melting snow, and flowed at higher levels. T he proofs of the existence of man in former geological periods are not to be sought for in the occurrence of his own bodily remains, as in the case of other animals. His bones are indeed now and then to be found, but in the vast majority of cases his former presence is revealed by the im- plements he has left behind him, formed of stone, metal, or bone. .lany years ago the archaeologists of Denmark, azlopting the subdivisions of the Latin poets, classified the prehistoric traces of man in three great divisions—those of (l) the Stone Age, (2) the Bronze Age, and (3) the Iron Age. There can be no doubt that-, on the whole, this has been the general order of succession. Men used stone and bone before they had discovered the use of metal. N ever- theless, the use of stone long survived the introduction of bronze and iron. In fact, in many European countries where metal has been known for many centuries, there are districts where stone implements are still employed, or where they were in use until quite recently. It is obvious also that, as there are still barbarous tribes un- acquainted with the fabrication of metal, the Stone Age is not yet extinct in many parts of the world. In this in- stance we again see how geological periods run into each other. The nature or shape of the implement cannot there- fore be always a very satisfactory proof of antiquity. lVe must judge of it by the circumstances under which it was found. From the fact that in north-western Europe the ruder kind of stone weapons occurs in what are certainly the older deposits, while others of more highly finislied work- manship are found in later accumulations, the Stone Age has been subdivided into an early or Palzeolithic and a later or Neolithic epoch. There can be no doubt, however, that the later was in great measure coeval with the age of bronze, and even to some extent of iron. The deposits which contain the history of the human periol are cavern—loam, river—alluvia, lake-bottoiiis, peat- niosses, sand-dunes, and other superficial accumulations. Most calcareous districts abound in underground tunnels and caverns which have been dissolved by the passage of water from the surface (ante, p. 271). In a large number of cases these cavities have communicated with the outer surface, so that terrestrial animals, including man himself, have made use of them as places of retreat, or have fallen or been washed into them. The floors of some of them are covered with loam or cave-eartli, resulting from the deposit of the silt carried in the water which formerly flowed through them. Very commonly also, a deposit of stalag- mite has formed from the drip of the roof. Hence any organic remains which may have found their way to these floors have been sealed up and admirably preserved. Above the present levels of the rivers there lie platforms or terraces of alluvium, sometimes to a height of 80 or 100 feet. These deposits are fragments of the river gravels and loams laid down when the streams flowed at that elevation, and therefore before the valleys were widened and deepened to their present form. River action is at the best but slow. To erode the valleys to so great a depth beneath the level of the upper alluvia, must have demanded a period of many centuries. There can therefore be no doubt of the high antiquity of these deposits. They have yielded the remains of many mammals, some of them extinct, together with the flint flakes made by man. From the nature and structure of some of the high-lying gravels, there can be little doubt that they were formed at a time when the rivers were larger than now, and were liable to be frozen and to be obstructed by large accumulations of ice. Vile are thus able to connect the formations of the human period with some of the later phases of the Ice Age in the west of Europe. GEOLOGY 369 From the evidence of caverns and river-alluvia of Britain, Germany, and France, Dawkins enumerates about fifty mammals as among the chief inhabitants of Europe during the early human period. They include many of the ani- mals still found wild in Europe, Asia, or Africa, such as the marmot, hare, beaver, lemming, leopard, lynx, wild cat, otter, brown bear, wolf, fox, African elephant, musk sheep, clianiois, wild boar, horse, reindeer, and hippopotamus. It will be observed what a remarkable mixture there is in this list of forms now found in alpine or arctic regions, on the one hand, with others only now to be seen in warm lati- tudes. Probably there continued to be great alternations of climate and changes in the distribution of food, so that migrations successively from opposite quarters took place into central and western Europe. But among the denizens of these regions were some that have been long extinct, such as the mammoth, Elep/ms antz'quus, 1l[rzcIza2'ro(Ius latidens, the woolly rhinoceros, the Irish elk, and others. That man was the contemporary of these extinct forms is shown both by the association of his flint weapons with their remains, and by the discovery of a tusk of the mammoth with an admirable outline of the animal carved upon it. This valuable relic, with bones of the reindeer and st.ag admirably sculptured into likenesses of these animals, was found in one of the caves of Perigord in central France. From the beds of lakes, and from peat-mosses, evidences of more advanced civilization have been obtained. In Switzerland and elsewhere, remains of wooden pile-dwellings have been observed during times when the water has been low. Associated with these are weapons and implements of stone, in other cases of bronze and of iron, pottery, rude kinds Jof cloth, seeds of different cereals, and bones of do- mesticated animals. The dog, swine, goat, horned sheep, and other familiar animals appear as the companions of man. But there is evidence that some of the creatures which he tamed to his use were not natives of Europe, but had their original stocks in central Asia, and that some of his grains must likewise have been introduced. Hence we have glimpses into some of the early human migrations from that eastern centre whence so many successive waves of popula- tion have invaded Europe. The later chronicles of the geologist merge insensibly into those of the archaeologist. The latter claims as his field whatever belongs to the history of man on the globe; the former includes the history of man in that larger history of the earth of which a brief outline has been given in the foregoing pages. POST—TERTIARY SERIES IN NORTH AMERICA. The general succession of events in post-Tertiary times appears to have been nearly the same over the northern hemisphere both in the New and the Old World. In North America we have the same sharply-defined line between the older post-Tertiary deposits and previous fornia- tions, due to the glacial conditions which, overspreading these regions, in great measure destroyed the superficial accumulations of the immediately preceding eras. The Quaternary or post-Tertiary formations are grouped by American geologists in the following subdivisions :— 4. Recent. and Peat, alluvium, blown sand, “alkali” deposits, Prehistoiic geyser deposits, cave deposits, artificial mounds. Rivei'-terraces loess 3.T-".cc.... . ’ ‘ an Raised beaches. 2. Champlain ....S'a.z'2'caz'a sand, Champlain clays, Leda clay. 1. Glacial ...... ..Bouldci' clays, uiistratified clays, saiids, and gravels. 1. Glacial. —As in Europe, the glacial deposits increase in thick- ness and variety from south to north. The southern limit of the iinstratified drift lies somewhere in the neighbourhood of the 39th parallel of north latitude, and the deposit ranges from the Atlantic westward to the meridian of 98°. It spieads, therefore, aeioss British North Anieriea, and is found over a considerable area of the north-eastern States. It rises to a height of 5800 feet among

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