their bones and their rude tools.
Contemporaneously with these Europeans of the River-drift there
certainly lived some kind of men, of a similar low grade of culture, in
the Mississippi valley and on both the Atlantic and Pacific slopes of
North America. Along with these ancient Americans lived some terrestrial
mammals that still survive, such as the elk, reindeer, prairie wolf,
bison, musk-ox, and beaver; and many that have long been extinct, such
as the mylodon, megatherium, megalonyx, mastodon, Siberian elephant,
mammoth, at least six or seven species of ancestral horse, a huge bear
similar to the cave bear of ancient Europe, a lion similar to the
European cave lion, and a tiger as large as the modern tiger of Bengal.

[Sidenote: Elevation and subsidence.]

Now while the general relative positions of those stupendous abysses
that hold the oceans do not appear to have undergone any considerable
change since an extremely remote geological period, their shallow
marginal portions have been repeatedly raised so as to add extensive
territories to the edges of continents, and in some cases to convert
archipelagoes into continents, and to join continents previously
separated. Such elevation is followed in turn by an era of subsidence,
and almost everywhere either the one process or the other is slowly
going on. If you look at a model in relief of the continents and
ocean-floors, such as may be seen at the Museum of Comparative Zooelogy
in Cambridge, showing the results of a vast number of soundings in all
parts of the world, you cannot fail to be struck with the shallowness of
Bering Sea; it looks like a part of the continent rather than of the
ocean, and indeed it is just that,--an area of submerged continent. So
in the northern Atlantic there is a lofty ridge running from France to
Greenland. The British islands, the Orkney, Shetland, and Faeroe groups,
and Iceland are the parts of this ridge high enough to remain out of
water. The remainder of it is shallow sea. Again and again it has been
raised, together with the floor of the German ocean, so as to become dry
land. Both before and since the time when those stone tools were dropped
into the red gravel from which Mr. Cresson took them the other day, the
northwestern part of Europe has been solid continent for more than a
hundred miles to the west of the French and Irish coasts, the Thames and
Humber have been tributaries to the Rhine, which emptied into the Arctic
ocean,