ef, in which I find Professor Hughes, of
Cambridge, coincides with me,[133] that the interglacial periods are
merely an ingenious expedient to get rid of the difficulties attending
the hypothesis of the universal glaciation of the northern hemisphere.

But, though man is thus geologically modern, it is held that
historically his existence on earth may have been very ancient,
extending perhaps ten or twenty, or even a hundred times longer than
the period of six or seven thousand years supposed to be proved by
sacred history. Let us first, as plainly and simply as possible,
present the facts supposed thus to extend the antiquity of man, and
then inquire as to their validity and force as arguments in this
direction.

The arguments from geology in favor of a great antiquity for man may
be summarized thus: (1) Human remains are found in caverns under very
thick stalagmitic crusts, and in deposits of earth which must have
accumulated before these stalagmites began to form, and when the
caverns were differently situated with reference to the local
drainages. (2) Remains of man are found under peat-bogs which have
grown so little in modern times that their antiquity on the whole
must be very great. (3) Implements, presumably made by men, are found
in river-gravels so high above existing riverbeds that great physical
changes must have occurred since they were accumulated. (4) One case
is on record where a human bone is believed to have been found under a
deposit of glacial age. (5) Human remains have been found under
circumstances which indicate that very important changes of level have
taken place since their accumulation. (6) Human remains have been
found under circumstances which indicate great changes of climate as
intervening between their date and that of the modern period. (7) Man
is known to have existed, in Europe at least, at the same time with
some quadrupeds formerly supposed to have been extinct before his
introduction. (8) The implements, weapons, etc., found in the oldest
of these repositories are different from those known to have been used
in historic times.

These several heads include, I think, all the really material evidence
of a geological character. It is evidence of a kind not easily
reducible into definite dates, but there can be no doubt that its
nature, and the rapid accumulation of facts within a small number of
years, have created a deep and widespread conviction among geologists
and archaeologis