Page:Popular Science Monthly Volume 9.djvu/307

Rh north were then high, but this cannot he said to he proved. That the arctic lands have been at some time raised higher than now, is shown by the fiords of the northern coasts, which, as first pointed out by Dana, must have been excavated by subaërial erosion; but a large part of that erosion may have been effected in the Tertiary age, and perhaps it was chiefly accomplished then.

When a dense forest clothed the arctic lands, and spread over continuous land-surfaces to Europe and Asia, these now half-submerged fiords were valleys traversed by flowing streams; for the abundant Tertiary vegetation of the far north proves the country to have been well watered. That these fiords were filled with glaciers during the Ice period is certain, as the bottoms and sides of many of them are glaciated, but this would happen again with a depression of temperature, and without a depression of sea-level. The fact that the glaciated surface of the bottoms of fiords in Sweden and America passes under the sea, and reaches as far as observation can be carried, is not the proof of elevation it has been claimed to be, for the glaciers that now reach the sea must score their beds to the depth of several hundred feet, before their extremities are lifted up by the one-tenth greater gravity of water, and are floated off as icebergs.

Prof. J. W. Dawson holds the view that the Glacial period was one of depression at the north, as he finds marine shells in the bowlder clay of the St. Lawrence Valley; and he attributes much of the glaciation of Eastern North America to icebergs dragged over the submerged land.

Croll says ("Climate and Time," p. 391):

According to the investigations of Bohtlingk and Kjerulf, Scandinavia was 600 feet lower during the Glacial period than now. Erdmann, on the contrary, supposes that Sweden was higher during the Glacial epoch than at the present day, from the fact that polished