EXISTING GLACIERS. 15 



great extent of territory lying in high latitudes, glaciers 

 are for two reasons relatively infrequent : 1. The land in 

 the more northern latitudes is low. 2. The dryness of the 

 atmosphere in the interior of the continent is such that it 

 unduly limits the snow-fall. Long before they reach the 

 central plateau of Asia, the currents of air which sweep 

 over the continent from the Indian Ocean have parted 

 with their burdens of moisture, having left them in a 

 snowy mantle upon the southern flanks of the Himalayas. 

 As a result, we have the extensive deserts of the interior, 

 where, on account of the clear atmosphere, there is not 

 snow enough to resist continuously the intense activity of 

 the unobstructed rays of the sun. 



In spite of their high latitude and considerable eleva- 

 tion above the sea-level, glaciers are absent from the Ural 

 Mountains, for the range is too narrow to afford neve- 

 fields of sufficient size to produce glaciers of large ex- 

 tent. 



The Caucasus Mountains present more favourable con- 

 ditions, and for a distance of one hundred and twenty 

 miles near their central portion have an average height of 

 12,000 feet, with individual peaks rising to a height of 

 16,000 feet or more; but, owing to their low latitude, the 

 line of perpetual snow scarcely reaches down to the 11,- 

 000-foot level. So great are the snow-fields, however, 

 above this height that many glaciers push their way down 

 through the narrow mountain-gorges as far as the 6,000- 

 foot level. 



The Himalaya Mountains present many favourable con- 

 ditions for the development of glaciers of large size. The 

 range is of great extent and height, thus affording ample 

 gathering-places for the snows, while the relation of the 

 mountains to the moisture-laden winds from the Indian 

 Ocean is such that they enjoy the first harvest of the clouds 

 where the interior of Asia gets only the gleanings. As is 



to be expected, therefore, all the great rivers which course 

 3 



