In the latter part of
the Cretaceous the land rises. The chalk ocean of Europe is
gradually reduced to a series of inland seas, separated by masses
and ridges of land, and finally to a series of lakes of brackish
water. The masses of the Pyrenees and Alps begin to rise; though
it will not be until a much later date that they reach anything
like their present elevation. In America the change is even
greater. A vast ridge rises along the whole western front of the
continent, lifting and draining it, from Alaska to Cape Horn. It
is the beginning of the Rocky Mountains and the Andes. Even
during the Cretaceous period there had been rich forests of
Mesozoic vegetation covering about a hundred thousand square
miles in the Rocky Mountains region. Europe and America now begin
to show their modern contours.
It is important to notice that this great uprise of the land and
the series of disturbances it entails differ from those which we
summed up in the phrase Permian Revolution. The differences may
help us to understand some of the changes in the living
population. The chief difference is that the disturbances are
more local, and not nearly simultaneous.
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