i86 PHYSIOGRAPHY. [chap. 



It is not difficult, however, to detect in the operations of 

 nature, counterbalancing forces which are capable of upheav- 

 ing the deposits that have been formed on the sea-bottom, 

 and of piling up fresh stores of solid matter upon the surface 

 of the earth. Among these elevatory, and therefore repara- 

 tive, agents, the most important place must be assigned 

 to earthquakes and volcanoes. After the occurrence of an 

 earthquake, it is by no means uncommon to find that the 

 level of the land has been shifted. Sometimes, it is true, 

 the surface is depressed, but more commonly the movement 

 is in the direction of elevation. 



Perhaps the best recorded example of such upheaval is 

 that which was observed by Admiral Fitzroy and Mr. 

 Darwin when examining the western coast of South America. 

 This region is peculiarly subject to subterranean distur- 

 bances, and in 1835 a violent earthquake, which destroyed 

 several towns, was felt along the coast of Chile, extending 

 from Copiapo to Chiloe. It was found, after the shock, 

 that the land in the Bay of Concepcion had been elevated 

 to the extent of four or five feet. At an island called Santa 

 Maria, about twenty-five miles south-west of Concepcion, the 

 upheaval was easily measured, vertically, on the steep cliffs ; 

 and the measurements showed that the south-western part 

 of the island was raised eight feet, while the northern end 

 was lifted more than ten feet high. Beds of dead mussels 

 were, in fact, hoisted ten feet above high-water mark ; and 

 an extensive rocky flat, previously covered by the sea, was 

 exposed as dry land. In like manner, the bottom of the 

 surrounding sea must have been elevated, for soundings all 

 round the island became shallower by about nine feet. It 

 is true, there was a partial subsidence shortly afterwards, but 

 this was far from sufficient to neutralize the upheaval, and 

 the net result showed a permanent elevation. It is considered 



