chap. ix. Elevation of Valparaiso. 239 



shells at the distance of two leagues from the shore. 

 Inland there are some wide, gravel-capped plains, inter- 

 sected by many broad, flat-bottomed valleys (now carry- 

 ing insignificant streamlets) with their sides cut into 

 successive wall-like escarpments, rising one above 

 another, and in many places, according to M. Gay, 

 worn into caves. The one cave (0. del Obispo) which 

 I examined, resembled those formed on many sea-coasts, 

 with its bottom filled with shingle. These inland 

 plains, instead of sloping towards the coast, are inclined 

 in an. opposite direction towards the Cordillera, like the 

 successively rising terraces on the inland or eastern side 

 of Chiloe : some points of granite, which project through 

 the plains near the coast, no doubt once formed a chain 

 of outlying islands, on the inland shores of which 

 the plains were accumulated. At Bucalemu, a few 

 miles northward of the Rapel, I observed at the foot 

 and on the summit-edge of a plain, ten miles from the 

 coast, many recent shells, mostly comminuted, but 

 some perfect. There were, also, many at the bottom of 

 the great valley of the Maypu. At San Antonio, shells 

 are said to be collected and burnt for lime. At the 

 bottom of a great ravine (Quebrada Onda, on the road 

 to Casa Blanca), at the distance of several miles from 

 the coast, I noticed a considerable bed, composed ex- 

 clusively of Mesodesma donaciforme, Desh., lying on a 

 bed of muddy sand : this shell now lives associated 

 together in great numbers, on tidal flats on the coast of 

 Chile. 



Valparaiso. 



During two successive years I carefully examined, 

 part of the time in company with Mr. Alison, into all 

 the facts connected with the recent elevation of this 

 neighbourhood. In very many parts a beach of broken 



