1835.] SHINGLE TERRACES AT COQUIMBO. 341 



formed by the denuding power of the sea, during long 

 periods of rest in the gradual elevation of the cpntinent. 



Shells of many existing species not only lie on the surface 

 of the terraces at Coquimbo (to a height of 250 feet), but are 

 embedded in a friable calcareous rock, which in some places 

 is as much as between twenty and thirty feet in thickness, 

 but is of little extent. These modern beds rest on an 

 ancient tertiary formation containing shells, apparently all 

 extinct. Although I examined so many hundred miles of 

 coast on the Pacific, as well as Atlantic side of the continent, 

 I found no regular strata containing sea-shells of recent 

 species, excepting at this place, and at a few points north- 

 ward on the road to Guasco. This fact appears to me 

 highly remarkable ; for the explanation generally given by 

 geologists, of the absence in any district of stratified 

 fossiliferous deposits of a given period, namely, that the 

 surface then existed as dry land, is not here applicable ; 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 sub- 

 merged. The explanation, no doubt, must be sought in 

 the met 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 obviousl}'^ 

 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 at 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 reoent 



