Even
a tulip-tree has been found among them. Now how is this to be
explained?
Either we must say that the climate of Greenland was then so much
warmer than now, that it had summers probably as hot as those of New
York; or we must say that these leaves and stems were floated thither
from the United States. But if we say the latter, we must allow a
change in the shape of the land which is enormous. For nothing now
can float northward from the United States into Baffin's Bay. The
polar current sets OUT of Baffin's Bay southward, bringing icebergs
down, not leaves up, through Davis's Straits. And in any case we
must allow that the hills of Disco Island were then the bottom of a
sea: or how would the leaves have been deposited in them at all?
So much for the change of climate and land which can be proved to
have gone on in Greenland. It has become colder. Why should it not
some day become warmer again?
Now for England. It can be proved, as far as common sense can prove
anything, that England was, before the age of ice, much warmer than
it is now, and grew gradually cooler and cooler, just as, while the
age of ice was dying out, it grew warmer again.
Now what proof is there of that?
This. Underneath London--as, I dare say, many of you know--there
lies four or five hundred feet of clay.
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