STRUCTURE OF EXISTING MOUNTAINS 389 



Uinta type, as defined by Powell ; where the sides are monoclines and the top 

 is flat . . . the anticline is not strictly flat on top, but undulates. . . ." 

 (p. 171). 



From this illuminating statement of Huntington, it would appear that 

 the Tian Shan uplift has been revived time after time, the high plateau 

 formed in each case progressing southward and northward bn each great 

 uplift, crushing its outwash gravels in the process and yet preserving a' 

 general undulation for the plateau surface itself. 



THE HIMALAYA 



This great mountain system consists of a series of parallel ridges or 

 plateaus which form the front ranges to the Tibetan Plateau, the Kuen 

 Lun forming the buttress of the same plateau to the north. The Tian 

 Shan and the Alai plateaus form a similar and similarly situated but less 

 magnificent feature to the north, being separated from the gTeat southern 

 form by the mountain knot of the Pamir. 



Godwen Austin^^ indicates six of these geological axes : 



(1) The main central Asian axis, the Kuen Lun forming the northern edge 

 of ridge of the Tibetan Plateau. 



(2) Trans-Himalaya of Muztagh or Karakorum. 



(3) The Ladakh chain. 



(4) The Zaskar, or main chain, rising to heights from 20,000 to 29,000 feet. 

 This is the range generally known as Himalaya. 



(5) Outer Himalaya. 



(6) The sub-Himalaya, in places very distinctly marked from the main 

 chain by open valleys (dhuns) or narrow valleys parallel to the main axis, of 

 the chain. This group includes the Siwaliks.^- 



"It appears, therefore, that the Himalayas grew southward in a series of 

 stages. These stages formed sub-Himalayan pressure ridges in front of the 

 main chain. ... In time the deposits of the i^resent Indo-Gangetic i)lain 

 will be involved in the fold." 



AMERICAN CORDILLERA 



The mountains of Xorth and South America have been ably described 

 by a number of illustrious observers. An excellent summary of the epics 

 of this galaxy is given in Chamberlin and Salisbury's Text-Book of Geol- 

 ogy. The great labors of Powell, Daly, Button, Gilbert, Lawson, W. T. 

 Lee, Le Conte, and Eansome might be mentioned in this connection. 



The existing mountains are the grander revivals of individual Cenozoic 

 uplifts exhibited as a vibratory and undulatory process extending through 



"Encyc. Brit., Ed. 11. vol. 13. Himalaya. 



12 p. Lake: Encyc. Brit.. Ed. 11. vol. 1.3. Himalaya. 



