वेदों की प्राचीनता एवं काल-निर्णय / ओरायन (लोकमान्य बाल गंगाधर तिलक - खगोलीय वैदिक शोध)

THE GLACIAL PERIOD. 23 rounded appearance of rocks and mountains clearly point out that at one period in the history of our globe northern parts of Europe and America must have been covered for a long time with a sheet of ice several hundreds of feet in thickness. The ice which thus invaded the northern portion of America and Europe did not all radiate from the Pole. The evidence of the direction of the striæ, or scratches engraved on rocks by ice, undoubtedly proves that the ice-caps spread out from all elevated places or mountains in different directions. These ice-sheets of enormous thickness covered the whole of Scandinavia, filled up the North Sea, invaded Britain down to the Thames valley, greater portion of Germany and Russia as far south as Moscow and almost as far east as the Urals. It is calculated that at least a million of square miles in Europe and more in North America were covered by the debris of rocks ground down by these glaciers and ice-caps, and it is from this debris that geologists now infer the existence of an Ice Age in early times. The examina- tion of this debris shows that there are at least two series of boulder clay indicating two periods of glaciation. The debris of the second period has disturbed the first layer in many places, but enough remains to show that there were two distinct beds of boulder-clay and drifts, belonging to two different periods. Prof. Geikie mentions four such Glacial periods, with corresponding Inter-Glacial periods, as having occurred in succession in Europe during the Pleistocene period. But though this opinion is not accepted by other geologists, yet the existence of two Glacial epochs, with an intervening Inter-Glacial period, is now consider- ed as conclusively established. A succession of cold and warm climates must have chara- cterised these Glacial and Inter-Glacial periods, which were also accompanied by extensive movements of depression and elevation of land, the depression taking place after the land was weighed down with the enormous mass of ice. Thus