294 Searles V. Wood—The Cause of the Glacial Period. 
A dictum, however, of Dr. Tyndall that a mere refrigeration could 
not have caused the Glacial period, because by diminishing the 
evaporation it would, so to speak, have cut off glaciers at their source, 
and that greater condensation was the essential factor in the problem, 
appears to have disinclined geologists to accept, what I believe to be, 
the only true explanation of the cause of this important episode in 
the earth’s history; and therefore, as in my memoir “on the Newer 
Pliocene Period in England,” a regard for the space I was occupying 
in the Journal of the Geological Society precluded my examining, 
and endeavouring to show there, why the view at which I had arrived 
of the cause of the Glacial period was not impaired by this (erroneous 
as I regard it) dictum of Dr. Tyndall, I propose doing this as briefly 
as I can in the pages of the GroLtocicaL MaGaziIne. 
The view adopted by some that the Glacial period was one in 
which ice caps were formed at the poles, whether synchronously or 
alternately with each other, is founded on the assumption that the 
poles, and the area immediately around them, must be the parts of 
the earth on which the greatest quantity of ice accumulates. This, 
however, though probably true of marine (or floe) ice, is pretty 
clearly not so of land ice at the Arctic, whatever may be the 
case at the Antarctic pole. The. exploration of the north side of 
Greenland, by Smith’s Sound, has disclosed that this extremity of 
that region, although it is 20° of latitude nearer the pole, and has 
a much colder climate, is rather less, than more, buried under land 
ice than is South Greenland, so far as that -can be seen from the 
Davis’ Strait side; while the existence of sea, though this be ice- 
bound, on the north side shows that the Greenland ice is in no way 
connected with a polar cap. Where the German Expedition of 
1869-70 was able to penetrate the floe-blocked sea on the east side 
of Greenland, and to land, they found that part of the region to be 
less buried under land ice than is the west side between Cape Farewell 
(which is 13° of lat. to the south of the place where they landed), 
and Disco ;! and it has long been known that the main land of North 
America, lying West of Davis’ Straits and Baffin’s Bay, in latitudes 
corresponding to the deepest buried parts of Greenland, is almost 
free from land ice. 
While it is thus clear that land ice is but subordinately dependent 
on the intensity of the cold, and essentially on the amount of snowfall, 
U.S. Geological Survey) writing in ‘‘ Nature”’ of 18th January, 1883 (p. 262), observes 
that “‘in America, where there is now great activity in the investigation of glacial 
phenomena, the evidence of a single interglacial period is cumulative and overwhelm- 
ing, while there is no evidence whatever of more than one.” 
1 A sketch of the country taken by Payer from Payer’s Spitze (a peak 7000 feet 
high in lat. 73° N.) is published in the ‘‘ Leisure Hour”’ for Nov. 1871. Instead of 
the uniformly level pall of ice burying everything as far as the eyes of observers who 
have penetrated 30 miles inland upon it can reach (and which from its elevation 
buries the highest of such hills as those which lie as islands uncovered by it between 
this ice pall and the sea, and rise to 2000 feet), in West Greenland, this view shows 
the snow-covered area of East Greenland as everywhere peaked, with the rocks in some 
pais protruding. A range of mountains in the furthest west that could be seen, 
y 
ounded the otherwise almost boundless view, the principal peak of which range the 
explorers estimated to be 14,000 feet high. 
