2 So Recent Elevatory Movements, paet n. 



starts, such, as those accompanying recent earthquakes, 

 or. as is most probable, by such starts conjointly with a 

 gradual upward movement, or by great aud sudden 

 upheavals, I have no direct evidence. But as on the 

 eastern coast, I was led to think, from the analogy of 

 the last hundred feet of elevation in La Plata, and from 

 the nearly equal size of the pebbles over the entire 

 width of the terraces, and from the upraised shells 

 being all littoral species, that the elevation had been 

 gradual ; so do I on this western coast, from the analogy 

 of the movements now in progress, and from the vast 

 numbers of shells now living exclusively on or close to 

 the beach, which are strewed over the whole surface of 

 the land up to very considerable heights, conclude, that 

 the movement here also has been slow and gradual, 

 aided probably by small occasional starts. We know 

 at least that at Coquimbo, where five escarpments occur 

 in a height of 364 feet, that the successive elevations, 

 if they have been sudden, cannot have been very great. 

 It has, I think, been shown that the occasional preserva- 

 tion of shells, unrolled and unbroken, is not improbable 

 even during a quite gradual rising of the land ; and 

 their preservation, if the movement has been aided by 

 small starts, is quite conformable with what actually 

 takes place during recent earthquakes. 



Judging from the present action of the sea, along 

 the shores of the Pacific, on the deposits of its own 

 accumulation, the present time seems in most places to 

 be one of comparative rest in the elevatory movement, 

 and of denudation of the land. Undoubtedly this is 

 the case along the whole great length of Patagonia. 

 At Chiloe, however, we have seen that a narrow sloping 

 frino-e, covered with vegetation, separates the present 

 sea-beach from a line of low cliffs, which the waves 

 lately reached; here, then, the land is gaining in 



