THE PHYSICS OF THE EARTH. 



209 



the mountain chains south of Tibet, and by the great earthquake 

 belt still persisting in the valleys of the Ganges and Brahmaputra. 

 In the case of North America the plateaus are broader and cor- 

 respondingly lower than those of South America and Asia. But 

 if the sea gave rise to the uplifts connected with the Andes and 

 Himalayas, can anyone doubt that the plateaus of North America 

 are due to the same cause? The total voluvie of the North American 



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Fig. 5. Relief Map of Asia. (From Frye's Complete Geography, by 

 permission of Ginn & Co., Publishers.) The mountains along the east 

 coast illustrate the successive stages in the recession of the Pacific Ocean. 

 At some future time the border of the continent will extend to the string 

 of islands running from Kamchatka to the Philippines, the shallow seas of 

 Japan and China becoming inland valleys. 



