368 NORTHERN CHILE chap. 



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

 of Httle 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 northward 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 submerged. The explanation, 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 extensi\'e 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 tertiar}^ epoch, 

 sedimentary matter containing fossil remains should have been 

 deposited and preserved at different points in north and south 



