i9o6 I SEE— THE CAUSE OF EARTHQUAKES. 311) 



3. In Vol. II, p. 121, Suess shows that the " prevaiHng tangential 

 movement in the Alps and Pyrenees " is toward the north. Thus 

 for the Alps, Lombardy is the most active ancient sea trough ; and 

 in the case of the Pyrenees, Suess shows that most of Spain was then 

 in the bed of the sea, and has since arisen (pp. 123-128). 



4. That the Sierra Nevada folds were produced by tangential 

 movement from the side of the Pacific is generally recognized by 

 geologists. Dana and others long ago have remarked the same 

 thing about the Andes (Suess, Vol. I, p. 539), and recently, Cham- 

 berlin has written me that most of the mountains give evidence of 

 having been upheaved by lateral thrusts from the direction of the sea. 



In view of these facts is not the significance of the asymmetry of 

 mountain chains perfectly plain? The unsymmetrical build of the 

 chains shows that the forces by which they were formed were di- 

 rected from the sea. And, as these forces could not have been 

 subaerial, they must have been subterranean, working just under 

 the earth's crust, and identical with those observed in earthquakes, 

 when lava is expelled from the sea and pushed under the adjacent 

 coast, along which the mountains always run so exactly parallel. 



By no possibility could any supposed contraction of the earth 

 have given rise to these features in mountain structure, since in 

 that case it would be impossible for the shape of the ranges and 

 tilting of the strata, pointing to lateral thrust, to be always directed 

 from the sea. The arrangement and structure of mountains thus 

 contradicts the contraction theory of the globe, and shows that any 

 supposed effect of contraction was insensible. 



§ 18. Criticism of the contraction theory of the formation of a 

 range such as the Alps. 



In addition to the considerations advanced by Fisher, as ex- 

 plained elsewhere in this paper^ to show that mountains formed by 

 wrinkles in the crust would in no case exceed a very small height, 

 and should, moreover, be distributed with some uniformity over 

 the globe, we may here consider some objections to the view that 

 a chain such as the Alps has been produced by shrinkage. 



To get Elie de Beaumont's theory clearly before us, we quote it 

 as given by Lyell, '* Principles of Geology," 12th ed., Vol. I, p. 119: 



" The origin of these chains depends not on partial volcanic action or a 



