vi MOUNTAINS 225 



as lofty as they are now, but which were more 

 or less completely levelled by the action of air 

 and water, just as is happening now to the 

 present mountain ranges. 



Movements of elevation and subsidence are 

 still going on in various parts of the world. 

 Scandinavia is rising in the north, and sink- 

 ing at the south. South America is rising on 

 the west and sinking in the east, rotating in 

 fact on its axis, like some stupendous pendu- 

 lum. 



The crushing and folding of the strata to 

 which mountain chains are due, and of which 

 the Alps afford such marvellous illustrations, 

 necessarily give rise to Earthquakes, and the 

 slight shocks so frequent in parts of Switzer- 

 land 1 appear to indicate that the forces which 

 have raised the Alps are not yet entirely spent, 

 and that slow subterranean movements are still 

 in progress along the flanks of the mountains. 



But if the mountain chains are due to com- 

 pression, the present valleys are mainly the 

 result of denudation. As soon as a mountain 

 range is once raised, all nature seems to con- 



1 In the last 150 years more than 1000 are recorded. 

 Q 



