chap. ix. and Action of Sea on the Land. 279 



where, in a height of 364 feet, there are five, — at Guasco, 

 where there are six, of which five may perhaps cor- 

 respond with those at Coquimbo, but if so, the subse- 

 quent and intervening elevatory movements have been 

 here much more energetic, — at Lima, where, in a height 

 of about 250 feet, there are three terraces, and others, 

 as it is asserted, at considerably greater heights. The 

 almost entire absence of ancient marks of sea-action at 

 defined levels along considerable spaces of coast, as near 

 Valparaiso and Concepcion, is highly instructive, for as 

 it is improbable that the elevation at these places alone 

 should have been continuous, we must attribute the 

 absence of such marks to the nature and form of the 

 coast-rocks. Seeing over how many hundred miles of 

 the coast of Patagonia, and on how many places on the 

 shores of the Pacific, the elevatory process has been 

 interrupted by periods of comparative rest, we may 

 conclude, conjointly with the evidence drawn from 

 other quarters of the world, that the elevation of the 

 land is generally an intermittent action. From the 

 quantity of matter removed in the formation of the 

 escarpments, especially of those of Patagonia, it appears 

 that the periods of rest in the movement, and of denu- 

 dation of the land, have generally been very long. In 

 Patagonia, we have seen that the elevation has been 

 equable, and the periods of denudation synchronous 

 over very wide spaces of coast ; on the shores of the 

 Pacific, owing to the terraces chiefly occurring in the 

 valleys, we have not equal means of judging on this 

 point ; and the very different heights of the upraised 

 shells at Coqaimbo, Valparaiso, and Concepcion seem 

 directly opposed to such a conclusion. 



Whether on this side of the continent the elevation, 

 between the periods of comparative rest when the 

 escarpments were formed, has been by small sudden 



