Briefly, then, the geologist assures us that when the cold of the Glacial Age was at its maximum glaciers streamed down from all the mountains of Scotland, Wales, and Northern England; that the ice was thick enough to overtop all the smaller hills, and on the plains it united in one great sea of ice some thousands of feet in thickness, that it stretched as far south as the latitude of London, England. But that to the west the ice streamed out across, the Irish Sea, the islands to the west of Scotland, and ended far out into what is now the Atlantic.23 But these glaciers, vast as they were, were very small compared with the glaciers that streamed out from the mountains of Norway and Sweden. These great glaciers invaded England to the south-west, beat back the glacier ice of Scotland from the floor of the North Sea, overran Denmark, and spread their mantle of bowlder clay far south into Germany.24 While such was the condition of things to the north, the glaciers of the Alps were many times greater than at present. All the valleys were filled with glacier ice, and they spread far out on the plains of Southern Germany and westward into France. The mountains of Southern France and the Pyrenees also supported their separate system of glaciers. Ice also descended from the mountains of Asia Minor and North Africa.25 In America we meet with traces of glaciers on a vast scale; but we can not pause to describe them here.26