The pyramids are built of this nummulitic limestone.
The one-celled animal in its shell is, however, no longer a
microscopic grain. It sometimes forms wonderful shells, an inch
or more in diameter, in which as many as a thousand chambers
succeed each other, in spiral order, from the centre. The beds
containing it are found from the Pyrenees to Japan.
That this vast warm ocean, stretching southward over a large part
of what is now the Sahara, should give a semitropical aspect even
to Central Europe and Asia is not surprising. But this genial
climate was still very general over the earth. Evergreens which
now need the warmth of Italy or the Riviera then flourished in
Lapland and Spitzbergen. The flora of Greenland--a flora that
includes magnolias, figs, and bamboos--shows us that its
temperature in the Eocene period must have been about 30 degrees
higher than it is to-day.* The temperature of the cool Tyrol of
modern Europe is calculated to have then been between 74 and 81
degrees F. Palms, cactuses, aloes, gum-trees, cinnamon trees,
etc., flourished in the latitude of Northern France. The forests
that covered parts of Switzerland which are now buried in snow
during a great part of the year were like the forests one finds
in parts of India and Australia to-day.
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