354 Pampean Formation part n. 



not. however, extend this conclusion to the calcareous 

 rocks of the Pampas, more especially as the underlying 

 tertiary strata in Western Bancla Oriental show that at 

 that period there was a copious emission of carbonate 

 of lime in connection with volcanic action. 



The Pampean formation, judging from its similar 

 composition, and from the apparent absolute specific 

 identity of some of its mammiferous remains, and from 

 the generic resemblance of others, belongs over its vast 

 area — throughout Banda Oriental, Entre Rios, and the 

 wide extent of the Pampas as far south as the Colorado, 

 — to the same geological epoch. The mammiferous 

 remains occur at all depths from the top to the bottom 

 of the deposit ; and I may add that nowhere in the 

 Pampas is there any appearance of much superficial 

 denudation : some bones which I found near the 

 Guardia del ALonte were embedded close to the surface : 

 and this appears to have been the case with many of 

 those discovered in Banda Oriental : on the ATatanzas, 

 twenty miles south of Buenos Ayres, a Glyptodon was 

 embedded five feet beneath the surface ; numerous 

 remains were found by S. IManiz, near Luxan, at an 

 average depth of eighteen feet ; in Buenos Ayres a 

 skeleton was disinterred at sixty feet depth, and on the 

 Parana I have descried two skeletons of the Mastodon 

 only five or six feet above the very base of the deposit. 

 With respect to the age of this formation, as judged of 

 by the ordinary standard of the existence of Mollusca, 



districts where the surrounding rocks are not calcareous. ATnjor 

 Charters in a Paper read before the Royal Geographical Society 

 (April 13th, 1840, and abstracted in the ' Athenaeum,' p. 317), states 

 that this is the case in parts of Mexico, and that he has observed 

 similar appearances in many parts of South Africa. The circum- 

 stance of the uppermost stratum round the rugged Sierra Yentana 

 consisting of calcareous or marly matter, without any covering of 

 alluvial matter, strikes me as very singular, in whatever manner we 

 view the deposition and elevation of the Pampean formation. 



