192 



Elevation of La Plata. 



PAET II. 



will be referred to in a succeeding chapter), abounding 

 with shells of an Azara, much worn, but which in 

 general form and appearance closely resemble, and are 

 probably identical with, the A. labiata. Besides these 

 shells, cellular, highly crystalline rock, formed of the 

 casts of small bivalves, is found near Ensenada ; and 

 likewise beds of sea-shells, which from their appearance 

 appear to have lain on the surface. Sir W. Parish has 

 given me some of these shells, and Iff, d'Orbigny pro- 

 nounces them to be, 



1. Buccinanops globulosum, 



d'Orbig. 



2. Olivancillaria auricularia, 



do. 



3. Yenns flexuosa, Lam. 



4. Cytherfea (imperfect). 



5. Mactra Isabellei, d'Orbig. 



6. Ostrea pulchella, do. 



Besides these, Sir W. Parish procured l (as named 

 by Mr. G. B. Sowerby) the following shells : — 



7. Voluta colocynthis. 



8. V. angulata. 



9. Buccirmm (not spec. ?). 



All these species (with, perhaps, the exception of 

 the last) are recent, and live on the South American 

 coast. These shell-beds extend from one league to six 

 leagues from the Plata, and must lie many feet above 

 its level. I heard, also, of beds of shells on the Som- 

 borombon, and on the Rio Salado, at which latter 

 place, as M. d'Orbigny informs me, the Mactra Isabellei 

 and Venus sinuosa are found. 



During the elevation of the Provinces of La Plata, 

 the waters of the ancient estuary have but little affected 

 (with the exception of the sand-hills on the banks of 

 the Parana and Uruguay) the outline of the land. 

 M. Parchappe, 2 however, has described groups of sand- 

 dunes scattered over the wide extent of the Pampas 



1 ' Buenos Ayres,' &c, by Sir W. Parish, p. 168. 

 1 D'Orbigny's ' Voyage Geolog.' p. 44. 



