1835.] OF THE TERTIARY FORMATIONS. 331 



favourable to most living creatures, that a thick and widely ex- 

 tended covering of sediment could be spread out, without 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 contem- 

 poraneous subsidence are generally widely extensive, as I am 

 strongly inclined to believe from my examination of the Coral Eecfs 

 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 consider- 

 able 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 2lst. I set out in company with Don Jose Edwards to the 

 silver-mine of Arqueros, and thence up the valley of Coquimbo. 

 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 not be fully appreciated in England, 

 namely, the absence of fleas ! The rooms in Coquimbo swarm with 

 them ; but they will not live here at the height of only three or four 

 thousand feet : it can scarcely be the trifling diminution of tem- 

 perature, but some other cause which destroys these troublesome 

 insects at this place. The mines are now in a bad state, though 

 they formerly yielded about 2000 pounds in weight of silver a year. 

 It has been said that " a person with a copper-mine will gain ; with 

 silver he may gain ; but with gold he is sure to lose." This is not 

 true : all the large Chilian fortunes have been made by mines^ of 

 the more precious metals. A short time since an English physician 

 returned to England from Copiapo, taking with him the profits of 

 one share in a silver-mine, which amounted to about 24,000 pounds 

 sterling. No doubt a copper-mine with care is a sure game, whereas 

 the other is gambling, or rather taking a ticket in a lottery. The 

 owners lose great quantities of rich ores; for no precautions can 

 prevent robberies. I heard of a gentleman laying a bet with 



