XVI 
CORRELATION OF TERTIARY BEES 
369 
lines, over a space of 1100 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 sedimentary 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, without 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 sedi¬ 
ment 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 
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 2 1st .—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 
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