Page:Geological Evidences of the Antiquity of Man.djvu/362

342 glacial epoch more complete, I shall describe in this chapter some other changes in physical geography, and in the internal structure of the earth's crust, which have happened in the post-pliocene period, because they differ in kind from any previously alluded to, and are of a class which were thought by the earlier geologists to belong exclusively to epochs anterior to the origin of the existing fauna and flora. Of this nature are those faults and violent local dislocations of the rocks, and those sharp bendings and foldings of the strata, which we so often behold in mountain chains, and sometimes in low countries also, especially where the rock-formations are of ancient date.

A striking illustration of such convulsions of post-pliocene date may be seen in the Danish island of Möen, which is situated about fifty miles south of Copenhagen. The island is about sixty miles in circumference, and consists of white chalk, several hundred feet thick, overlaid by boulder clay and sand, or glacial drift which is made up of several subdivisions, some unstratified and others stratified, the whole having a mean thickness of sixty feet, but sometimes attaining nearly twice that thickness. In one of the oldest members of the formation, fossil marine-shells of existing species have been found.

Throughout the greater part of Möen, the strata of the drift are undisturbed and horizontal, as are those of the subjacent chalk; but on the north-eastern coast they have been, throughout a certain area, bent, folded, and shifted, together with the beds of the underlying cretaceous formation. Within this area they have been even more deranged than is the English chalk with flints along the central axis