276 CLIMATIC CONDITIONS OF THE GLACIAL EPOCH. 



liighlaiid an!l the other nearly so, it will he desirable to say something before 

 proceeding to consider tlie grander and more complicated features of High 

 Asia itself. These ranges are the Caucasus and the Ural, two chains so 

 distinct and well marked in geographical position as to be easily separated 

 from all others. The Ural is especially an independent chain, disconnected 

 Avith any other system of moiaitains as well by its meridional direction as 

 by its isolated character; while the Caucasus, abutting at its two extremities 

 on the Black and Caspian Seas, is so far removed by these depressions from 

 the great line of elevations of Central Asia and Soutliern Europe of which it 

 in reality forms a part, as to be most easily limited on all sides. All the other 

 Asiatic chains are so connected with the great central mass of that continent 

 as to ])e only with difficulty separated into precisely limited groups. 



Both tlie Caucasus and the Ural form links in the partly artificial and 

 partly natural boundary-line between Europe and Asia. The first mentioned 

 has many features in common witii the Alps, and it might with propriety be 

 considered a part of the great mountain system of Southern Europe. These 

 ranges lie nearly within the same parallels of latitude, and their average 

 elevation is not very different. The western end of one abuts squarely on 

 the Black Sea; that of the other curves ai'ound to meet the Mediterranean. 

 The Caucasus rises quite abruptly from its base, and forms a somewhat nar- 

 rower and more compact mass than that of the Alps. Taking these facts 

 into consideration, it will be apparent that a considerable similarity in the 

 present glacial character of the two ranges is to be expected. This is. indeed 

 the case, as is shown by the statements of the various geological explorers 

 of the Caucasus, especially Abich, who has devoted so many years of labor 

 to tliat chain. The Alpine glaciers are more numerous, and in most cases 

 extend to a greater length than those of the Caucasus, since the al)rupt- 

 ness of the latter chain is unfavorable to the development of those high 

 plateaux and vast cirques which only can give birth to masses of ice like 

 those of the Gorner and Aletsch. Owing partly to the simplicity of structure 

 and compressed form of the Caucasus, and partly also, as appears probable, to 

 ])urely climatic conditions, the glaciers in this range do not descend to a very 

 low level. By far the most important snow and ice masses of the Caucasus 

 are in the central portion of the range to which the grand peaks of Elbruz 

 (18,572'), Koschtantau (17.123'), Dychtau (16,928'), and Kasbek (16,546') 

 belong. The average height of this portion of the chain along a length of 

 about 120 miles is fully 12,000 feet, and it is here only that glaciers which 



