Note 2 — The Cause of the Ice Age.

The writer prefers the nomenclature of Dr. Geikie and others using the term Ice Age rather than Glacial Epoch, or Period. The duration of this age was not recorded in the same manner and terms as either previous or succeeding ages; this is due to the inactivity, or even absolute suspension of the great forces, heat and moisture, over continental areas during this age; under estimates of its duration are thus liable to be made.