chap. ix. and Action of Sea on the Land. 277 



probable, considering, first, the difference in the force 

 and number of the shocks now yearly affecting different 

 parts of this coast; and, secondly, the fact of single 

 areas, such as that of the province of Concepcion, having 

 been uplifted very unequally during the same earth- 

 quake. It would, in most cases, be very hazardous to 

 infer an inequality of elevation, from shells being found 

 on the surface or in superficial beds at different heights ; 

 for we do not know on what their rate of decay depends ; 

 and at Coquimbo one instance out of many has been 

 given, of a promontory, which, from the occurrence of 

 one very small collection of lime-cemented shells, has 

 indisputably been elevated 242 feet, and yet on which, 

 not even a fragment of shell could be found on careful 

 examination between this height and the beach, although 

 many sites appeared very favourable for the preservation 

 of organic remains : the absence, also, of shells on the 

 gravel-terraces a short distance up the valley of Co- 

 quimbo, though abundant on the corresponding terraces 

 at its mouth, should be borne in mind. 



There are other epochs, besides that of the existence 

 of recent Mollusca, by which to judge of the changes 

 of level on this coast. At Lima, as we have just seen, 

 the elevation has been at least eighty-five feet, within 

 the Indo-human period; and since the arrival of the 

 Spaniards in 1530, there has apparently been a sinking 

 of the surface. At Valparaiso, in the course of 220 

 years, the rise must have been less than nineteen feet ; 

 but it has been as much as from ten to eleven feet in 

 the seventeen years subsequently to 1817, and of this 

 rise only a part can be attributed to the earthquake 

 of 1822, the remainder having been insensible and 

 apparently still, in 1834, in progress. At Chiloe the 

 elevation has been gradual, and about four feet du ring- 

 four years. At Coquimbo, also, it has been gradual, 



