OF THE TERTIARY FORMATIONS 101 



it is only in comparatively shallow water that the 

 greater number of marine organic beings can flour- 

 ish, 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 Coquim- 

 bo appears to be of about the same age with sev- 

 eral deposits on the coast of Chile (of which that 

 of Navedad is the principal one), and with the great 

 foraiation of Patagonia. Both at Navedad and in 

 Patagonia there is evidence that, since the shells 

 (a Hst 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 in- 

 termediate 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 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 sedi- 

 mentary deposit, when being upraised, could pass 

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