[CAUSES OF CLIMATAL CHANGE.]

DEDICATED TO
DR. T. STERRY HUNT, F.R.S.,
Whose Work in
the Chemical and Cosmical Relations of Geology
is beyond all Praise,
and is destined to command
in the Future
even greater Acceptance than in the Past.

Various Theories as to Changes of Climate—The Astronomical Theory of Croll—The Geographical Theory of Lyell—Objections of a Geological Character to the Former—Testimony of Geology and Physical Geography in Favour of the Latter

North America in Periods of Warm and Cold Submergence.(A) Early Cretaceous. (B) Glacial or Pleistocene.
Shaded portion land. Unshaded portion.—Snow-clad mountains.—Crosses.—Ice-laden sea.
These maps illustrate the probable geographical conditions of warm and cold periods. ([p. 388.])

[CHAPTER XIV.]

CAUSES OF CLIMATAL CHANGE.