26 PHYSIOGRAPHIC GEOLOGY. 



Facing the still greater Indian Ocean, and looking southward, stand 

 the Himalayas, — the loftiest of mountains, — called the Himalayas as 

 far as Cashmere, and from there, where a new sweep in the curve be- 

 gins, the Hindoo Koosh, — the whole over 2,000 miles in length: not so 

 long, it is true, as the Andes, but continued as far as the ocean in front 

 continues. The mean height of the Himalayas has been estimated at 

 1 6,000 feet ; over forty of the peaks surpass Chimborazo. The Kuen 

 Lun Mountains, to the north of the Himalayas, make another crest 

 to the great chain, with Thibet between the two. Going westward, 

 the mountains decline, though there are still ridges of great elevation. 



On the north there are the wide Siberian plains, backed by the 

 Altai, about half the Himalayas in height. The Altai thus have the 



Fig. 20. 



same relation to the Himalayas as the Appalachians to the Rocky 

 Mountains, or the Brazilian Mountains to the Andes, yet with a 

 striking difference in the immense shore-plain between them and the 

 sea. 



The sketch (Fig. 20) presents the general features to the eye. At 

 a, there is the elevated land of India ; between a and b, the low river- 

 plain at the base of the Himalayas ; at b, the Himalayas ; b to c, 

 Plains of Thibet ; c, the Kuen Lun ridge ; c to d, Plains of Mongolia 

 and Desert of Gobi ; at d, the Altai ; d to n, the Siberian plains. 



The interior region of the continent, in its eastern half, is the plateau 

 of Gobi and Mongolia, which, at 4,000 feet, is low compared with the 

 mountains in front and rear. More to the westward, the region c d 

 becomes intersected by the lofty Thian-shan Range. Still farther 

 westward, the surface declines into the great depression occupied by 

 the Caspian and Aral, part of which is below tide-level (p. 13). 



The interior drainage-system for Asia is without outlet. The waters 

 are shut up within the great basin, the Caspian and Aral being the 

 seas which receive the part of those waters not lost in the plains. 

 The Volga and other streams, from a region of a million of square 

 miles, flow into the Caspian. 



The Urals stand as a partial barrier between Asia and Europe, 

 parallel nearly with the mountains of Norway. 



Europe has its separate system of elevations and interior plains ; 

 but it is not necessary to dwell on it here. 



