208 SEE— FURTHER RESEARCHES ON 



[April 24, 



When the crust is thus rent mto blocks, some of them are re- 

 duced to small size, and eventually raised up, as in the vertical walls 

 of granite now seen in Smyth's channel, southern Chile, the Straits 

 of Magellan, Yosemite Valley, California, and the fiords of Nor- 

 way. These precipitous walls of granite could be pushed up only 

 by vertical forces, in earthquakes. It is noticeable that no such 

 isolated masses are found towering up in the plains of Kansas, the 

 desert of Sahara, and other inland regions far from the oceans. The 

 origin of faults and fault movements must therefore be sought in 

 the leakage of the oceans and in the resulting relief, which takes 

 place in the sea bottoms and along the borders of the continents. 



§ 26. On the Uplift of the Great Plateaus of the World and on 

 the Gradual Elezmtion of the Continents. — For reasons already amply 

 set forth in § 7, the process involved in the formation of the Andes 

 is clear and beyond dispute. Now it happens that the Andean pla- 

 teaus, such as those of Quito, Caxamarca, Cuzco and Titicaca, are 

 generally included between the eastern and western ranges of the 

 Andes, and were evidently uplifted by the same forces which formed 

 the mountains themselves. Accordingly it is clear that a plateau such 

 as that of Titicaca was therefore uplifted by the expulsion of lava 

 from under the sea. 



If now we pass from the Andes to the Himalayas, we shall find 

 that in like manner those great mountains of Asia were uplifted 

 principally by the Indian Ocean. The plateau of Thibet in the 

 Himalayas of Asia corresponds exactly wath that of Titicaca in the 

 Andes of South America ; and as the latter was formed with the 

 Andes, so also the plateau of Tibet was formed with the Himalayas. 

 This seems absolutely clear and incontrovertible. And a similar 

 mode of development must be ascribed to the table lands to the 

 east and west of Tibet, so that the principal plateaus of Asia, Tibet 

 and Iran, are clearly the work of the sea. 



The highest part of these plateaus is Tibet, with an average 

 elevation of about 15,000 feet, and a width of about 500 miles at the 

 highest part. At the middle it is somewhat wider, and to the west 

 it narrows into Little Tibet, less than half the width of Tibet proper. 

 It is evident that great Tibet was uplifted chiefly by movements 

 from the direction of the bay of Bengal; this is shown by the lay of 



