162 



ISLAND LIFE 



PAET I 



only accumulate where precipitation is greater than melt- 

 ing and evaporation, and this is never the case except in 

 areas exposed to the fall influence of the vapour-bearing 

 winds. The outer rim of the ice-sheet would inevitably 

 exhaust the air of so much of its moisture that what 

 reached the inner parts would produce far less snow than 

 would be melted by the long hot days of summer.^ The 

 accumulations of ice were therefore probably confined, in 

 the northern hemisphere, to the coasts exposed to moist 

 winds, and where elevated land and mountain ranges 

 afforded condensers to initiate the process of glaciation; 

 and we have already seen that the evidence strongly sup- 

 ports this view. Even with this limitation, however, the 

 mass of accumulated ice would be enormous, as indeed we 

 have positive evidence that it was, and might have caused 

 a sufficient shifting of the centre of gravity of the earth to 

 produce a submergence of about 150 or 200 feet. 



But this would only be the case if the accumulation of 

 ice on one pole was accompanied by a diminution on the 

 other, and this may have occurred to a limited extent 

 during the earlier stages of the glacial epoch, when alter- 

 nations of warmer and colder periods would be caused by 

 winter occurring in 2'>cri]ielion or aphelion. If, however, as 

 is here maintained, no such alternations occurred when 

 the excentricity was near its maximum, then the ice 

 would accumulate in the southern hemisphere at the same 

 time as in the northern, unless changed geographical condi- 

 tions, of which we have no evidence whatever, prevented 

 such accumulations. That there was such a greater ac- 

 cumulation of ice is shown by the traces of ancient glaciers 

 in the Southern Andes and in New Zealand, and also, 

 according to several writers, in South Africa ; and the in- 

 dications in all these localities point to a period so recent 

 that it must almost certainly have been contemporaneous 

 with the glacial period of the northern hemisphere.^ 



^ Dr. Croll objects to this argument, and adduces the case of Greenland 

 as showing that ice may accumulate far from sea. But the width of 

 Greenland is small compared with that of the supposed Antarctic ice-cap. 

 {Climate and Cosmology, p. 78.) 



2 The recent extensive glaciation of New Zealand is generally imputed by 

 the local geologists to a greater elevation of the land ; but I cannot help 



