380 MAN AND THE GLACIAL PERIOD. 



America and Europe combined comprise about six mill- 

 ion square miles. At a moderate estimate, the ice was 

 three-quarters of a mile deep. Here, therefore, there 

 would be between four and five million cubic miles of 

 water, which had first relieved the ocean-becls of the press- 

 ure of its weight, and then concentrated its force over 

 the elevated areas of the northern hemisphere. This dis- 

 turbance of the equilibrium, by the known transfer of 

 force from one part of the earth's crust to another, cer- 

 tainly gives much plausibility to the theory of Jamieson, 

 Winchell, Le Coute, and Upham, that the Glacial period 

 partly contained in itself its own cure, and by the weight 

 of its accumulated weight of ice helped to produce that 

 depression over the glaciated area which at length ren- 

 dered the accumulation of ice there impossible. 



This general view of the known causes in operation 

 during the Glacial period will go far towards answering 

 an objection that has probably before this presented itself 

 to the reader's mind. It seems clear that the Glacial 

 period in the southern hemisphere has been nearly con- 

 temporaneous with that of the northern. The Glacial 

 period proper of the southern hemisphere is long since 

 passed. The existing glaciers of New Zealand, of the 

 southern portion of the Andes Mountains, and of the 

 Himalaya Mountains are but remnants of those of former 

 days. In the light of the considerations just presented, 

 it would not seem improbable that the same causes should 

 produce these similar effects in the northern and the 

 southern hemisphere contemporaneously. At any rate, it 

 would not seem altogether unlikely that the pressure of 

 ice during the climax of the Glacial period upon the 

 northern hemisphere (which, as we have seen, there is 

 reason to believe aided in the depression of the continent 

 to below its present level in the latter part of the Glacial 

 period) should have contributed towards the elevation of 

 mountains in other parts of the world, and so to the 



