The Arctic Home in the Vedas c5.4

c5.4

It was in the Quarternary or the Pleistocene period that the mild climate of these regions underwent sudden alterations, producing what is called the Glacial period. The limits of this Glacial period may not so exactly coincide with those of the Pleistocene as to enable us to say that they were mathematically coextensive, but still in a rough sense we may take these two periods as coinciding with each other. It is impossible within the limits of a short chapter to give even a summary of the evidence proving the existence of one or more Glacial epochs in the Pleistocene period. We may, however, briefly indicate its nature and see what the geologists and the physicists have to say as regards the causes that brought about such extensive changes of climate in the Quarternary era. The existence of the Glacial period is no longer a matter of doubt, though scientific men are not agreed as to the causes which produced it. Ice-sheets have not totally disappeared from the surface of the earth, and we can still watch the action of ice as glaciers in the valleys of the Alps or in the lands near the Pole, like Greenland which is still covered with a sheet of ice so thick as to make it unfit for the growth of plants or the habitation of animals. Studying the effects of glacial action in these places geologists have discovered abundant traces of similar action of ice in former times over the whole of Northern Europe and America. Rounded and scratched stones, till or boulder clay, and the 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 examination 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 considered as conclusively established.