t least became dry land, and carried
vegetation.

And yet we have not done. There is another world to tell of yet.

For these beds (known as the Woolwich and Reading beds) dip under
that vast bed of London clay, four hundred and more feet thick, which
(as I said in my last chapter) was certainly laid down by the estuary
of some great tropic river, among palm-trees and Anonas, crocodiles
and turtles.

Is the reader's power of belief exhausted?

If not: there are to be seen, capping almost every high land round
London, the remains of a fifth world. Some of my readers may have
been to Ascot races, or to Aldershot camp, and may recollect the
table-land of the sandy moors, perfectly flat atop, dreary enough to
those to whom they are not (as they have long been to me) a home and
a work-field. Those sands are several hundred feet thick. They lie
on the London clay. And they represent--the reader must take
geologists' word for it--a series of beds in some places thousands of
feet thick, in the Isle of Wight, in the Paris basin, in the volcanic
country of the Auvergne, in Switzerland, in Italy; a period during
which the land must at first have swarmed with forms of tropic life,
and then grown--but very gradually--more temperate, and then colder
and colder still; till at last set in that age of ice, which spread
the boulder pebbles over all rocks and soils indiscriminately, from
the Lake mountains to within a few miles of London.

For everywhere about those Ascot moors, the top of the sands has been
ploughed by shore-ice in winter, as they lay a-wash in the shallow
sea; and over them, in many places, is spread a thin sheet of ice
gravel, more ancient, the best geologists think, than the boulder and
the boulder-clay.

If any of my readers ask how long the period was during which those
sands of Ascot Heath and Aldershot have been laid down, I cannot
tell. But this we can tell. It was long enough to see such changes
in land and sea, that maps representing Europe during the greater
part of that period (as far as we can guess at it) look no more like
Europe than like America or the South Sea Islands. And this we can
tell besides: that that period was long enough for the Swiss Alps to
be lifted up at least 10,000 feet of their present height. And that
was a work which--though God could, if He willed it, have done it in
a single day--we have proof positive was not done in less than ages,