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PLEISTOCENE CLASSIFICATIONS.
By S. HAZZLEDINE WARREN, F.G.S.
Presidential Address, delivered February 1st, 1924.
Received October 27th, 1924.
INTRODUCTION.
AT the present time theories of the classification of the Pleisto-
cene Period are extraordinarily diverse, and represent
profound underlying differences of outlook. It would be
impossible within any reasonable limits of space to cover the
whole ground, and I shall only endeavour to touch certain
points which happen to appeal particularly to myself. Indeed,
Prof. Kendall has well said that no one man, even a man of
the widest experience, can possess all the qualifications necessary
for the satisfactory solution of this complex problem.
THE METHOD OF CLASSIFICATION.
The usual basis of classification is that founded on the
succession of ice ages worked out by James Geikie, Penck and
others. This Deperet replaces by his variations of sea-level.
On the present occasion I propose to invert the usual order,
and to take the human culture stages of France as the basis
of the time scale, and to refer the ice ages to them, instead of
vice versa. This is being done as an experiment, in order to
see how matters will work out on this basis.
It is open to the objection that the French culture stages
are not of world-wide application, but can the ice ages be said
to be of world-wide application when there are some who deny
that there was ever more than one ? Indeed, if we travel
north, we inevitably reach a point at which there has been but
one continuous ice age extending back from the present day to
some undetermined point long anterior to the ice age of Britain.
For myself, I thus believe in one unbroken ice age a little
further north, and in a broken ice age with interglacial stages
nearer the ice margin ; but I have an open mind to consider
how much these interglacial stages may import ; how far they
may have extended northward ; or how near to the edge of
the ice the temperate fauna and flora may have existed during
the abnormal conditions of the Pleistocene.
Further, it seems theoretically inevitable that there would
be a point further north where the first interglacial break would
correspond with the final disappearance of the ice at some
other point further south. In endeavouring to establish correla-
tions which centre mainly in south-eastern England it would
appear wiser to exclude from our minds the conditions of more
northern countries where apparent correspondence may be
deceptive.
Proc. Geol. Assoc, Vol. XXXV., Part 4, 1924. 18