1833.] AT SANTA Ft, 135 



introduction to an old Catalonian Spaniard, who treated me 

 with the most uncommon hospitality. The Bajada is the 

 capital of Entre Rios. In 1825 the town contained 6000 

 inhabitants, and the province 30,000 ; yet, few as the in- 

 habitants are, no province has suffered more from bloody 

 and desperate revolutions. They boast here of repre- 

 sentatives, ministers, a standing army, and governors : so 

 it is no wonder that they have their revolutions. At some 

 future day this must be one of the richest countries of La 

 Plata. The soil is varied and productive ; and its almost 

 insular form gives it two grand lines of communication by 

 the rivers Parana and Uruguay. 



I was delayed here five days, and employed myself in 

 examining the geology of the surrounding country, which 

 was very interesting. We here see, at the bottom of the 

 cliffs, beds containing sharks' teeth and sea-shells of extinct 

 species, passing above into an indurated marl, and from 

 that into the red clayey earth of the Pampas, with its 

 calcareous concretions and the bones of terrestrial quad- 

 rupeds. This vertical section clearly tells us of a large bay 

 of pure salt-water, gradually encroached on, and at last 

 converted into the bed of a muddy estuary, into which 

 floating carcasses were swept. At Punta Gorda, in Banda 

 Oriental, I found an alteration of the Pampaean estuary 

 deposit, with a limestone containing some of the same 

 extinct sea-shells ; and this shows either a change in the 

 former currents, or more probably an oscillation of level in 

 the bottom of the ancient estuary. Until lately, my reasons 

 for considering the Pampaean formation to be an estuary 

 deposit were — its general appearance, its position at the 

 mouth of the existing great river the Plata, and the presence 

 of so many bones of terrestrial quadrupeds ; but now 

 Professor Ehrenberg has had the kindness to examine for 

 me a little of the red earth, taken from low down in the 

 deposit, close to the skeletons of the mastodon, and he finds 

 in it many infusoria, partly salt-water and partly fresh- 

 water forms, with the latter rather preponderating ; and 

 therefore, as he remarks, the water must have been 

 brackish. M. A. d'Orbignv found on the banks of the 

 Parana, at the heii^^ht of a hundred feet, great beds of an 

 estuary shell, now living a hundred miles lower down nearer 

 the sea ; and I found similar shells at a less height on the 

 banks of the Uruguay : this shows that just before the 



