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EVIDENCES OF GLACIATION IN AND ABOUT GREATER NEW YORK*
THE ICE AGE
At the
end of that long course of geological time, from the Archaean to the
Tertiary, which built up the solid portions of the earth in their
present configuration, geologists recognize in the evidence before them
the proof of a remarkable period—a period so startling that it might
justly be accepted with hesitation, were not the conception
unavoidable before a series of facts as extraordinary as itself and
which, partaking of its astonishing character, are explained upon no
simpler hypothesis. This era is known as the glacial. It has left its
monuments over the surface of either hemisphere and written its
history upon their rocks.
It
was an epoch of arctic rigidity. The cold regions of the pole extended
their contracted circles over the temperate latitudes and enveloped in
a mantle of ice lands which had been the home, of an abundant and
tropical vegetation. The skirts of the glacial sea which spread its icy
surface over the polar lands became so expanded as to hide the surface
of the earth within its frigid folds down to the latitude of 390
north. The evidence which has established the presence of these arctic
conditions is complete and irrefragable, and, though there is to-day a
recession from the former extreme positions of glacialists, there can
be no wholesale denial of the facts. In America especially the proofs
are more convincing than anywhere else in the world.
It was Agassiz who first insisted, perhaps almost with trepi-
*I
have been permitted in the opening pages of this article to
appropriate language used in a paper by myself in the Popular Science
Monthly in 187a
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