Page 242 - Lokmanya Tilak Samagra (khand 2)

THE GLACIAL PERIOD 29
then produce the climatic changes it did in the Pleistocene period.
This reply practically concedes that the high eccentricity of the
earth's orbit, combined with the occurrence of winter when the
earth is at aphelion, is not by itself sufficient to bring about a
Glacial period; and it may, therefore, be well urged that a Glacial
epoch may occur even when the eccentricity is not at its maximum.
Another point in which Dr. Croll's theory conflicts with the geolo-
gical evidence is the date of the close of the last Glacial epoch,
ascertained, by the American geologists, from estimates based
on the erosion of valleys since the close of the last Glacial period.
It is pointed out in the last chapter that these estimates do not
carry the beginning of the Post-Glacial period much further
than about 10,000 years ago at the best; while Dr. Croll's calcula-
tion would carry it back to 80 or 100 thousand years. This is a
serious difference and even Prof. Geikie, who does not entirely
accept the American view, is obliged to admit that though Dr.
Croll's theory is the only theory that accounts for the succession of
Glacial epochs and therefore, the only correct theory, yet the for-
mula employed by him to calculate the values of the eccentricity
of the earth's orbit may be incorrect and that we may thus account
for the wide discrepancy between his inference and the conclu-
sions based upon hard geological facts, which cannot be lightly
set aside.* The judgment recently pronounced by Mr. Hudleston
is still more severe. In his opening address, as President of the
geological section of the meeting of the British Association in
1898, he is reported to have remarked, , " There is ,probably
nothing more extraordinary in the history of modern investiga-
tion than the extent to which geologists of an earlier date permitted
themselves to be led away by the fascinating theories of Croll.
The astronomical explanation of that 'Will-o' -the-wisp', the cause
of the great Ice Age, is at present greatly discredited and we begin
to estimate at their true value those elaborate calculations which
were made to account for events, which, in all probability, never
occurred. Extravagance begets extravagance and the unreasonable
peculations of men like Belt and Croll have caused some of our
recent students to suffer from the nightmare. "t This criticism
appears to be rather severe; for though Dr. Croll's elaborate

"Fragments of Earth Lore. p. 287.
t See The Nature, Sept. I 5, T 8g8.