Ragnarok : the age of fire and gravel

58 THE DRIFT,

CHAPTER VIII. GREAT HEAT A PREREQUISITE.

Now, it will be observed that the principal theories assigned for the Drift go upon the hypothesis that it was produced by extraordinary masses of ice—ice as icebergs, ice as glaciers, or ice in continental sheets. The scientists admit that immediately preceding this Glacial age the climate was mild and equable, and these great formations of ice did not exist. But none of them pretend to say how the ice came or what caused it. Even Agassiz, the great apostle of the ice-origin of Drift, is forced to confess :

“We have, as yet, no clew to the source of this great and sudden change of climate. Various suggestions haye been made—among others, that formerly the inclination of the earth’s axis was greater, or that a submersion of the continents under water might have produced a decided increase of cold ; but none of these explanations are satisfactory, and science has yet to find any cause which accounts for all the phenomena connected with it.”*

Some have imagined that a change in the position of the earth’s axis of rotation, due to the elevation of extensive mountain-tracts between the poles and the equator, might have caused a degree of cold sufficient to produce the phenomena of the Drift ; but Geikie says—

“Tt has been demonstrated that the protuberance of the earth at the equator so vastly exceeds that of any

* “ Geological Sketches,” p. 210.