10 



CHILI. 



successively, till the whole embankment was wash- 

 ed away, and the valley left as we now see it. 



The stones all bear the marks of having come 

 from some distance, and may possibly have been 

 deposited by a river flowing, in ancient times, from 

 the snowy Andes ; while some vast, though tran- 

 sient cause, may, at one operation, have scooped 

 out the valley, filled it with water, and left a bar- 

 rier of adequate strength to retain it for a time : 

 by a succession of sudden disruptions of this dam, 

 the lake would be made to stand at different 

 levels ; and the washing of the water down the 

 sides of the banks would bring along with it the 

 loose stones, gravel, and mud, to the water's 

 edge, where their velocity being checked, they 

 would be deposited in the form of level beaches. 

 In the Alpine valleys of Savoy, circumstances 

 precisely analogous frequently occur : a great ava- 

 lanche dams up a stream, and forms a lake, which 

 stands at different levels, as the barrier of ice suc- 

 cessively breaks away. 



According to the Huttonian theory of the 

 earth, it is supposed that vast masses of solid land 

 have been forced up, from time to time, from the 



