330 CONTEMPORANEOUS DEPOSITION [CTI.U-. xvi. 



cable; for we know from the shells strewed on the surface and 

 embedded in loose sand or mould, that the land for thousands of 

 miles along both coasts has lately been submerged. The explana- 

 tion, no doubt, must be sought in the fact, that the whole southern 

 part of the continent has been for a long time slowly rising ; and 

 therefore that all matter deposited along shore in shallow water, 

 must have been soon brought up and slowly exposed to the wearing 

 action of the sea-beach; and it is only in comparatively shallow 

 water that the greater number of marine organic beings can flourish, 

 and in such water it is obviously impossible that strata of any great 

 thickness can accumulate. To show the vast power of the wearing 

 action of sea-beaches, we need only appeal to the great cliffs along 

 the present coast of Patagonia, and to the escarpments or ancient 

 sea-cliffs at different levels, one above another, on that same line 

 of coast. 



The old underlying tertiary formation at Coquimbo, appears to 

 be of about the same age with several deposits on the coast of 

 Chile (of which that of Navedad is the principal one), and with 

 the great formation of Patagonia. Both at Navedad and in Patagonia 

 there is evidence, that since the shells (a list of which has been 

 seen by Professor E. Forbes) there intombed were living, there has 

 been a subsidence of several hundred feet, as well as an ensuing 

 elevation. It may naturally be asked, how it comes that, although 

 no extensive fossiliferous deposits of the recent 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 re- 

 mains, should have been deposited and preserved at different 

 points in north and south 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 number- 

 less 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 



