urope
during the Glacial Age.

In addition to these, there was also a large number of animals whose
home is in the temperate regions of the earth--animals that thrive in
neither extremes of heat and cold. This includes a great many animals
of the deer kind, several varieties of bears and horses; in fact, the
majority of those with which we are acquainted.<13>

Now, what conclusion follows from this assemblage of animals? Many
theories have been put forward in explanation. It has been suggested
that Europe at that time had a climate not unlike that of some portions
of the earth at present; that is, a long and severe Winter was followed
by a short but warm Summer. During the Winter reindeer and other
northern animals would press from the north in search of food, but would
retire on the approach of Spring, when their feeding grounds would
in turn be occupied by bisons and animals of a southern habitat. In
confirmation of this view it is pointed out that a vast collection of
bones, from the bottom of a sink-hole or pond in Derbyshire, England,
conclusively show that in the summer-time it was visited by bisons with
their calves, and in Winter by reindeer.<14> This theory is open to
a great many objections. As is well known, some animals make quite
extensive migrations annually, but we can scarcely believe that heavy,
unwieldy animals like the hippopotamus, were then such industrious
travelers as to wander every year from Italy to Northern England and
return.<15> But the very ground on which this theory rests, that of
strongly contrasted summers and winters, could not be true of Europe or
the western portions of it, owing to the presence of the Atlantic Ocean,
and the influence which it inevitably exerts on the climate.<16> We see,
then, that the presence of these different animals can be explained
only by supposing great secular changes in climate. Let us see if we can
strengthen this view by an appeal to the vegetation of this period.

We have seen how important a guide as to climate were the remains of the
vegetation of the early times. We therefore turn with more confidence to
such discoveries as will tell us of the flora of this age. But there are
many reasons why remains of plant growth should be few. As we shall soon
learn, this was a period of flooded rivers; and in the gravels and loams
thus formed is found our principal source of information as to the life
of the age. But such a rush of waters would form gravelly