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