86 J. Oroll—Examination of Wallaces Modification of the 
Wallace maintains that they are high lands. ‘‘It is,” he says, 
“only where there are lofty mountains or elevated plateaus, as 
in Greenland, etc., that thes accompanied by perpetual 
snow cover the country. The north polar area is free from 
any accumulation of Soniadeut 3 ice, excepting the high tats 
of Greenland and Grinnel Land.” And in regard to the Ant- 
arctic continent, he says, ‘‘T'he much greater quantity of ice at 
the south pole is undoubtedly due to the presence of a large 
extent of high land.” Were it not for these extensive high 
lands and lofty mountains, Greenland and the Antarctic 
permanent snow and ice. e, however, nowhere, so far as I. 
can find, offers any proof for the conclusion that those regions 
possess extensive highlands, elevated plateaus, and lofty moun- 
tains sufficient to account for these icy mantles. In the paper 
just referred to (Phil. Mag., November, 1883), I have discussed 
this subject at considerable length, and have arrived at conclu- 
sions ee the opposite of those advocated by Mr. 
Wallace, viz: that Greenland and likely the greater part of 
the Antarctic regions consist of land probably not much above 
sea-level, and that the mass of ice under which they are buried 
must be due to some other cause than elevation of se tare 
Mr. Wallace's Modification of the Theory Examined. — Mr. 
Wallace’s chief, and, I may say, only real canades of my 
ct is this. I give it in his own words: 
case Wi thern Sole: during the Glacial epoch, then the 
glacial conditions would be continued, and perhaps even intensi- 
fied, when sun approached nearest to the earth in winter, m- 
stead of their _ being at the time, as Mr. Croll maintains, an almost 
perpetual spring.”—p. 503. 
“When geographical conditions and eccentricity combine to 
fe a severe glacial epoch, the changing phases of precession 
ave very little, if any, effect on the character of the climate, as 
mild or glacial, though it may modify the seasons; but when the 
eccentricity becomes moderate and the resulting climate less 
severe, then the changing phases of precession bring about a ¢ con- 
ages aes alteration and even a partial reversal of the climate.” 
ce “It follows that towards the equatorial limits of a glaci- 
ated country alternations of climate may occur during a period of 
high eccentricity, while near the pole, where the whole country is 
completely ice-clad, no amelioration may take place. Exactly the 
same thing will occur inversely with mild Arctic climates.” —p. 154- 
