26 PHYSIOGRAPHIC GEOLOGY. 



Pacific on the east ; Africa and the Indian Ocean are on the south. 

 The Atlantic is the smallest ocean ; the North Pacific next, — for its 

 average depth is probably not over 13,000 feet (p. 12), and it is 

 much encumbered by islands to the west-of-south ; the Indian 

 Ocean next, — for it is full 5000 miles wide in front of the Asiatic 

 coast, and singularly free from islands. The boundary is a complex 

 one, and the land between the Atlantic and Pacific over 6000 

 miles broad. 



On the side of the small North Atlantic there are the moun- 

 tains of Norway and the British Isles, the former having a mean 

 height of 4000 feet. On the Pacific side there are loftier moun- 

 tains, extending in several ranges from the far north to southern 

 China, — the Stanovoi, Jablonoi, and the Khingan Ranges ; and off 

 the coast there is still another series of ranges, now partly sub- 

 merged, — viz., those of Japan and other linear groups of islands. 

 These stand in front of the interior chain, very much as the 

 Cascade Eange and Sierra Nevada of the Pacific border of America 

 are in advance of the summit-ridges of the Eocky Mountains, 

 and both are alike in being partly volcanic, with cones of great 

 altitude. 



Facing the still greater Indian Ocean, and looking southward, 

 stand the Himalayas, — the loftiest of mountains, — called the Hima- 

 layas as far as Cashmere, and from there, where a new sweep in 

 the curve begins, the Hindoo Cush, — the whole over 2000 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 16,000 feet ; over forty of the 

 peaks surpass Chimborazo. The Kuen-Luen 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 great Siberian plains, backed by the 

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



Fig. 20. 



d N 



the same relation to the Himalayas as the Appalachians to the 

 Rocky Mountains, or the Brazilian Mountains to the Andes, yet 



