378 THE UPHEAVAL OF MOUNTAINS. 



and the Andes for the greater part of its extent 

 "consists of two parallel chains whose crests are separated 

 by broad plateau-like valleys, from 20 to 60 miles wide, and 

 from 8000 to 13,000 feet high. Near the northern termination 

 there are three diverging chains instead of two, and near the 

 southern there is but one. Numerous cross swells connect 

 the ranges, separating the high valley into a number of distinct 

 basins." * 



It now seems to be regarded almost as a matter of 

 ascertained fact that the great mountain chains of the 

 world are the results of upheavals which have taken 

 place from time to time from within the crust of the 

 earth; and we think that this is susceptible of proof 

 so clear, that it would be difficult to refute the truth 

 of the proposition. 



There is the incontrovertible fact, for instance, " that 

 all the great mountain chains on the globe were originally 

 part of the sea bottom;" f this is shown beyond the 

 possibility of a doubt by the presence of numerous 

 marine shells existing in the rocks of which the 

 mountains are built up: such shells are found in the 

 Alps "at heights of 10,000 feet or more over sea 

 level." In the Rocky Mountains at " a height of 1 1,000 

 feet," and in the Himalayas "at 16,500 feet." More- 

 over the rocks in which these fossil remains of the 

 ancient sea are thus found are sedimentary rocks 

 that is to say, strata gradually formed during ages 

 by the deposit of water. It is evident that this must 



* The Origin of Mountain Ranges in relation to Geology and History 

 etc, by T. Mellard Reade, C.E., 1886, p. 66. 



-j- Extract from a Lecture on " Mountain Architecture " delivered by 

 Professor Sir A. Geikie at the City Hall, Glasgow, 27 th Jan. 18/6, publ. 

 1877, p. ii. 



Ibid., p. 12. 



