204 



PATAGONIA. 



Jan. 1834. 



I have called these step-like plains level, because they 

 appear to be absolutely so to the eye, but in truth they rise a 

 little between the edge of one line of cliff and the base of the 

 next above it. Their slope is about the same as that of the 

 gradually shoaling bottom of the neighbouring sea. The ele- 

 vation of 350 feet is gained by three steps ; one of about 100 

 feet, the second 250, and the third 350. Over these three 

 plains marine remains are frequently scattered, but they are 

 especially abundant on the lower one. The shells are the 

 same as the now existing littoral species, and the muscle and 

 turbo yet partially retain their blue and purple colours. 



We have now stated the problem, which is to be explained 

 so as to connect together these various phenomena. At first 

 I could only understand the grand covering of gravel, by the 

 supposition of some epoch of extreme violence, and the suc- 

 cessive lines of cliff, by as many great elevations, the precise 

 action of which I could not however follow out. Guided by 

 the " Principles of Geology and having under my view the 

 vast changes going on in this continent, which at the present 

 day seems the great workshop of nature, I came to another, 

 and I hope more satisfactory conclusion. The importance of 

 any view which may explain the agency by which such vast 

 beds of shingle have been transported over the surface of the 

 successive plains, cannot be doubted. Whatever the cause 

 may have been, it has determined the condition of this 

 desert country, with respect to its form, nature, and capabi- 

 lities of supporting life. 



There are proofs, that the whole coast has been elevated 

 to a considerable height within the recent period ; and on 

 the shores of the Pacific, where successive terraces likewise 

 occur, we know that these changes have latterly been very 

 gradual. There is indeed reason for believing, that the 

 uplifting of the ground during the earthquakes in Chile, 

 although only to the height of two or three feet, has been a 

 disturbance which may be considered as a great one, in com- 

 parison to the series of lesser and scarcely sensible move- 

 ments which are likewise in progress. Let us then imagine 



