32 THE ICE AGE IN CANADA. 



influence of gravity." (Trotter, in Proc, Koyal Society of 

 London, XXXVIIL, 107.) 



Woeickoff s conclusions may be summed up as follows: 



" 1. The great expanse of ocean in the southern hemis- 

 phere is favourable to the deposit of snow and formation 

 of glaciers, by furnishing a great evaporating surface, and 

 at the same time a low general temperature facilitating 

 precipitation. This applies to the antarctic continent, 

 and also permits the formation of glaciers far to the north 

 in New Zealand and in South America. 



" 2. On the other hand, the present condition of the 

 northern hemisphere is unfavourable to glaciers, because 

 the sea is so warm that deposition near the coasts is 

 rather as rain than snow up to pretty high latitudes, 

 while the continents are so wide that there is little 

 precipitation in their interior. 



" 3. Thus there are no glaciers in eastern Siberia, even 

 in the mountains, where the mean temperature is only 15 C 

 to 16 C., and central Asia generally is unfavourable to 

 glaciation on account of its dryness, while eastern Asia is 

 acted on by the monsoons. If, therefore, the extent of 

 land in Asia has not materially changed since the Pliocene 

 period, there could not have been great glaciers there 

 since that period. Even the submergence of the great 

 plain of China could not materially affect this result, 

 though it might cause glaciers in the mountains of 

 Japan. 



" 4. To explain the great Pleistocene glaciers, of which 

 traces are found in western Europe, it is necessary to 

 suppose that the temperature was lower, either on account 

 of submergence of the low lands or of diversion of warm 

 currents, or both causes may have operated. A submer- 

 gence connecting the White and Baltic seas would greatly 



