GLACIATIOX OF HIGH ASIA. 283 



feet. Some of the glaciers of this region are said to have a length as great 

 as that of the longest in the Alps. 



The mountain system of the Altai is much less extensive than that of the 

 Thian-Schan; still it is a range of importance, being comparable with the 

 Alps in magnitude, and having formerly been a mining region of great pro- 

 ductiveness. The western Hanks of the Altai are steppe-like in character, 

 for the prevailing southwesterly winds have before reaching them become 

 completely dried of their moisture. The northeast winds, on the other hand, 

 although cold, do bring refreshing and fertilizing rains to the slopes on that 

 de of the rancre. The mean elevation of the Altai is not as great as that 



SI 



of the Alps, hardly exceeding 5,000 feet. The highest point has an eleva- 

 tion of about 11,000 feet, and around this there are perpetual snows, and a 

 glacier of over a mile in length. 



It is not possible to go into fuller details in regard to the present glacia- 

 tion of the northern and northeastern sides of High Asia. Enough has 

 been said, it is believed, to show clearly how entirely dependent on climatic 

 conditions is the distribution of snow and ice all through that vast area. It 

 cannot fill to have become apparent to the reader that however low the 

 mean temperature of a great mountain region like that of Central Asia may 

 be rendered by its extreme altitude, it will not be covered with perpetual 

 snow, or much less with anything resembling a general ice-sheet. The 

 exterior ranges will receive the bulk of the precipitation, and only the very 

 summits of the highest chains, inside the mass, will be tipped with eternal 

 snow. No doulit if the high area were large enougli its interior would be 

 entirely bare of snow, no matter how elevated it might be. As illustrative of 

 how snow and ice collect, where the climatic conditions are favorable, even 

 in close proximity to regions of high mean temperature, a few words may 

 be added in regard to the magnificent glacier systems of the Himalayas. 

 Here, and especially on the southern slopes of that range, as has already 

 been explained,* the precipitation is very large, the winds prevailing during 

 a large part of the year sweeping across the heated waters of the ocean to 

 the south, and carrying the moisture thus collected to be deposited on the 

 flanks of the mountains which rise to bar their passage. 



In that portion of the Himalayan ranges which lies at the head of the 

 Indus, or the northwest-southeast trending division of the whole mass, the 

 distribution of the snow and glaciers has been carefully studied by Mr. Drew, 



o 



* See avlr, pp. 199, 200. 



