Page:Popular Science Monthly Volume 12.djvu/72

62 of earlier date than the glaciation of the districts in which they are found.

I propose to state briefly some of the general arguments that have influenced my opinion, and then to deal with the special question of the age of the deposits at Hoxne, which the advocates of the postglacial theory put forward as being undoubtedly in their favor.

Let us first take into consideration the age of the beds containing the remains of the mammoth, the woolly rhinoceros, and their companions, with which the palæolithic implements are so often found. Wherever, in Europe, the relation of these beds to the bowlder-clay can be clearly seen, they are of distinctly older age. Thus, in Russia, Sir Roderick I. Murchison has recorded the discovery of the bones of the mammoth and woolly rhinoceros, near Moscow, in reddish clay covered with erratic blocks, on the plains thirteen miles distant from the river. And if we follow the northern drift southward from Moscow, as I have done, we find it gradually changes from clay with bowlders to the clay without bowlders that covers the southern plains. Around the sea of Azov, cliffs of this glacial clay, one hundred feet high, can be followed continuously for miles, and its junction below with the older beds is sharply defined. It rests on a fresh-water deposit containing shells of species of Unto, Cyclas, and Paludina, and at this horizon fragments of the tusks and bones of the mammoth are abundant, and are always undoubtedly older than the glacial clay. In a similar position the same remains have been found at Odessa and other places in the south of Russia.

Nor has the theory of the post-glacial age of the remains of the mammoth remained unchallenged by eminent geologists in England. Prof. Phillips and Mr. Godwin Austen long ago recorded their conviction that they belonged to an earlier period than the deposition of the bowlder-clay, and that when they occur in newer beds they have been derived from an older formation. The remains are so plentiful in the caves of the north of England that it is certain that the mammoth and rhinoceros were abundant. Yet nowhere in the glaciated parts of the country have the bones been found excepting where preserved from the action of the ice in caverns and fissures.

Thus, in tracing the limits of the northern ice on the eastern side of England, I have found that Durham and Northumberland were probably completely overflowed by it, excepting the upper parts of the Cheviots, as pointed out to me by Mr. Richard Howse. The ice streamed through from the west, around the southern and northern flanks of the Cheviots, down the valleys of the Tyne and the Tweed, and when approaching the eastern coast was deflected to the south by the great mass of ice that occupied and was flowing down the bed of