continent to the south--England, probably an island at the
beginning of the period, united to the continent by new beds--the
Mammoth ranging up to where we now stand.

Then a period of upheaval. The German Ocean becomes dry land. The
Thames, a far larger river than now, runs far eastward to join the
Seine, and the Rhine, and other rivers, which altogether flow
northward, in one enormous stream, toward the open sea between
Scotland and Norway.

And with this, a new creation of enormous quadrupeds, as yet
unknown. Countless herds of elephants pastured by the side of that
mighty river, where now the Norfolk fisherman dredges their teeth
and bones far out in open sea. The hippopotamus floundered in the
Severn, the rhinoceros ranged over the south-western counties;
enormous elk and oxen, of species now extinct, inhabited the vast
fir and larch forests which stretched from Norfolk to the farthest
part of Wales; hyenas and bears double the size of our modern ones,
and here and there the sabre-toothed tiger, now extinct, prowled out
of the caverns in the limestone hills, to seek their bulky prey.

We see, too, a period--whether the same as this, or after it, I know
not yet--in which the mountains of Wales and Cumberland rose to the
limits of eternal frost, and Snowdon was indeed Snowdon, an alp down
whose valleys vast glaciers spread far and wide; while the reindeer
of Lapland, the marmot of the Alps, and the musk ox of Hudson's Bay,
fed upon alpine plants, a few of whose descendants still survive, as
tokens of the long past age of ice. And at every successive
upheaval of the western mountains the displaced waters of the ocean
swept over the lower lands, filling the valley of the Thames and of
the Wey with vast beds of drift gravel, containing among its chalk
flints, fragments of stone from every rock between here and Wales,
teeth of elephants, skulls of ox and musk ox; while icebergs,
breaking away from the glaciers of the Welsh Alps, sailed down over
the spot where we now are, dropping their imbedded stones and silt,
to confuse more utterly than before the records of a world rocking
and throbbing above the shocks of the nether fire.

At last the convulsions get weak. The German Ocean becomes sea once
more; the north-western Alps sink again to a level far lower even
than their present one; only to rise again, but not so high as
before; sea-beaches and sea-shells fill many of our lower valleys;
whales by hundreds ar