I9I3.] SEE— ORIGIN OF HIMALAYA MOUNTAINS. 499 



feet, while eastern Tibet has an elevation of only ii,ooo feet. The 

 breadth also varies from some 200 miles on the West to 500 miles 

 at the eastern extremity (General Strachey, article "Himalayas," 

 Encyclopedia Britannica, 9th edition). 



Accordingly, if we take the wider part of western Tibet as 

 having a sectional height of 3 miles and a breadth of 250 miles, 

 the product in miles is 750, exactly the same.as in the Andes and the 

 Rocky Mountains. Further east in Tibet the width may be 500 

 miles, and the height about 2 miles, which gives a sectional product 

 of 1,000. This is larger than the average Andean product adopted 

 above, and more like that of the Rocky Mountain plateau west of 

 Colorado. 



But the circumstance that the sectional volumes of three great 

 plateaus in the three leading continents of the globe should all be 

 so nearly equal is fully as impressive a fact as the related fact that 

 all of these plateaus should overlook the same great ocean by which 

 they were elevated. 



Altogether the similarity in the volumes of sections of these 

 three greatest plateaus is so striking as to make it difficult to deny 

 that it constitutes practically a mathematical demonstration that 

 these plateaus were uplifted by the Pacific Ocean. The relation- 

 ships here brought out as to the volumes of these plateaus, in addi- 

 tion to the situations about the Pacific Ocean could not well be 

 accounted for by chance, even if we did not know the cause of 

 mountain formation. But as the cause of mountain formation is 

 fully understood, the cause which has built the plateaus is also 

 clearly shown, and it is impossible to consider any other explanation 

 than that here outlined. 



3. General Law that v^here a Continuous Plateau Increases 

 IN Width, it Decreases in Elevation. 

 This law doubtless results from the process of uplifting by 

 which the mountains and plateaus have been raised above the sea. 

 For example, in case of the continuous plateau crowned with moun- 

 tain crests which surrounds the Pacific Ocean from Cape Horn to 

 Alaska, and then extends down the southeastern shores of Asia, 



