I9I3-] SEE— ORIGIN OF HIMALAYA MOUNTAINS. 497 



" Dr. See has arranged his facts with great ingenuity, and the presenta- 

 tion of his case is the most powerful argument which has ever been ad- 

 vanced in favor of the view held since the days of Strabo, Aristotle or 

 Pliny, that the expansive force of steam is the prime cause of volcanic and 

 seismic disturbances." 



In view of this general interest a few additional considerations 

 on the origin of the Himalayas may he important. For after care- 

 ful reflection I regard the Himalayas as the crucial test ; and as the 

 theory is triumphantly verified by a more complete study of this 

 great range, it must hereafter be regarded as firmly and permanently 

 established. 



2. The Volumes of the Plateaus of the Rocky Mountains, 

 OF the Andes, and of the Himalayas. 



In the four memoirs included in the Proceedings of this Society 

 for 1906-08, the new theory of mountain formation is treated with 

 considerable detail, but some numerical relations between the 

 plateaus above mentioned are worthy of more attention than they 

 have yet received. 



The Pacific plateau of North America is of variable width, being 

 less than 500 miles wide in Mexico, and perhaps 600 miles wide in 

 Canada, but from 1,000 to 1,500 miles wide in the United States. 

 Perhaps 750 miles wide would be a good average estimate of the 

 whole plateau. And the height may be taken as approximately 

 5,000 feet, or a mile above the sea. These average figures will 

 satisfactorily represent the Pacific plateau in North America. It is 

 noticed also in many places that where the plateau is broadest it is of 

 less average height; but where it is narrower the height is somewhat 

 increased. 



In the Andes the same principles prevail. The plateau is highest 

 in the region of Lake Titicaca, where the elevation is over 12,600 

 feet, or 2.5 miles. The width here does not exceed 300 miles. 

 Further north, near Quito, it narrows up, and is not over half this 

 width ; but in Colombia it again spreads out to a width of 300 or 

 400 miles, but is only about 6,000 or 8,000 feet in height, scarcely 

 more than half that along the more southern portion of the Andes. 



