342 FOSSILIFEROUS DEPOSITS, [chap. xvi. 



period, nor of any period intermediate between it and the 

 ancient tertiary epoch, have been preserved on either side of the 

 continent, yet that at this ancient tertiary epoch, sedimentary 

 matter containing fossil remains should have been deposited 

 and preserved at different points in north and south lines, 

 over a space of i loo miles on the shores of the Pacific, and 

 of at least 1350 miles on the shores of the Atlantic, and in 

 an east and west line of 700 miles across the widest part of 

 the continent ? I believe the explanation is not difficult, 

 and that it is perhaps applicable to nearly analogous facts 

 observed in other quarters of the world. Considering the 

 enormous power of denudation which the sea possesses, as 

 shown by numberless facts, it is not probable that a sedi- 

 mentary deposit, when being upraised, could pass through 

 the ordeal of the beach, so as to be preserved in sufficient 

 masses to last to a distant period, unless it were originally 

 of wide extent and of considerable thickness : now it is 

 impossible on a moderately shallow bottom, which alone is 

 favourable to most living creatures, that a thick and widely 

 extended covering of sediment could be spread out, unless 

 the bottom sank down to receive the successive layers. 

 This seems to have actually taken place at about the same 

 period in southern Patagonia and Chile, though these 

 places are a thousand miles apart. Hence, if prolonged 

 movements of approximately contemporaneous subsidence 

 are generally widely extensive, as I am strongly inclined 

 to believe from my examination of the Coral Reefs of the 

 great oceans — or if, confining our view to South America, 

 the subsiding movements have been coextensive with those 

 of elevation, by which, within the same period of existing 

 shells, the shores of Peru, Chile, TIerra del Fuego, 

 Patagonia, and La Plata have been upraised — then we can 

 see that at the same time, at far distant points, circumstances 

 would have been favourable to the formation of fossiliferous 

 deposits of wide extent and of considerable thickness ; and 

 such deposits, consequently, would have a good chance of 

 resisting the wear and tear of successive beach-lines, and 

 of lasting to a future epoch. 



May 2ist. — I set out in company with Don Jose Edwards 

 to the silver-mine of Arqueros, and thence up the valley of 

 Coqulmbo. Passing through a mountainous country, we 

 reached by nightfall the mines belonging to Mr. Edwards. 

 I enjoyed my night's rest here from a reason which will 



