of an flee Bge. 215 



ation, but none of them can be said to be en- 

 tirely satisfactory. It is well known that the 

 chief factors in the production of glaciers are 

 moisture and cold. Cold alone is not suffi- 

 cient; neither is moisture, unless we can pre- 

 cipitate it in the form of snow. Cold is op- 

 posed to the production of moisture, and this 

 is a flaw in the argument presented by the last 

 theory, unless we can couple with it another 

 set of conditions which we will discuss later. 



The solution, if it is ever reached, is perhaps 

 more likely to be found in the realm of meteor- 

 ology than geology. 



It is unnecessary to change the conditions 

 of temperature or the amount of moisture now 

 existing in order to produce the great glacier 

 again, provided this moisture could be precipi- 

 tated, enough of it, in the right place as snow. 

 For instance, if in Switzerland, where the con- 

 ditions are nearly balanced, the annual pre- 

 cipitation could be slightly increased we should 

 have a condition that would precipitate more 

 snow in winter than would melt in summer. 

 And the glaciers would gradually accumulate 

 in size until they would fill the valleys and 

 gorges to the same extent as formerly pre- 

 vailed. There only needs to be such a change 

 in the meteorological conditions as will cause 

 a greater precipitation in that part of the 

 globe favorable to glaciers, as, for instance, in 

 the northern part of North America toward 



