chap. xv. Movements of South America. 599 



show us, that the continent at that period must have 

 stood only a few fathoms below its present level, and 

 that afterwards it subsided over a wide area, 700 or 

 800 feet. The manner in which it has since been re- 

 brought up to its actual level, was described in detail 

 in the Eighth and Ninth Chapters. It was there shown 

 that recent shells are found on the shores of the Atlan- 

 tic, from Tierra del Fuego northward for a space of at 

 least 1,180 nautical miles, and at the height of about 

 100 feet in La Plata, and of 400 feet in Patagonia. 

 The elevatory movements on this side of the continent 

 have been slow ; and the coast of Patagonia, up to the 

 height in one part of 950 feet and in another of 1,200 

 feet, is modelled into eight great, step-like, gravel- 

 capped plains, extending for hundreds of miles with the 

 same heights ; this fact shows that the periods of denu- 

 dation (which, judging from the amount of matter 

 removed, must have been long-continued) and of eleva- 

 tion were synchronous over surprisingly great lengths 

 of coasts. On the shores of the Pacific, upraised shells 

 of recent species, generally, though not always, in the 

 same proportional numbers as in the adjoining sea, 

 have actually been found over a north and south space 

 of 2,075 miles, and there is reason to balieve that they 

 occur over a space of 2,480 miles. The elevation on 

 this western side of the continent has not been equable ; 

 at Valparaiso, within the period during which upraised 

 shells have remained undecayed on the surface, it has 

 been 1,300 feet, whilst at Coquimbo, 200 miles north- 

 ward, it has been within this same period only 252 

 feet. At Lima, the land has been uplifted at least 

 eighty-feet since Indian man inhabited that district; 

 but the level within historical times apparently has 

 subsided. At Coquimbo, in a height of 364 feet, the 

 elevation has been interrupted by five periods of com- 



