582 



what remarkable, they are found in gneiss, and 

 not in ml caslate. 



We find at the back of this granitic, or 

 rather micaslate-gneiss soil of the southern 

 chain, on the south of the Villa of Cura, a tran- 

 sition soil, composed of greenstone, amphibolic 

 serpentine, micaceous limestone, and green and 

 carburated slate The most southern limit 

 of this territory is formed by volcanized rocks. 

 Between Parapara, Ortiz, and the Cerro de 

 Flores (lat. 9° 28'— 9° 34' ; long. 70° 2'— 70° 15'), 

 phonolithes and amygdaloides are found on the 

 very border of the basin of the Llanos, that vast 

 internal sea which heretofore filled the whole 

 space between the Cordilleras of Venezuela and 

 Parime. We shall here remark that, accord- 

 ing to the observations of Major Long and 

 Doctor James, trappean formations (bulleuses 

 dolerites and amygdaloides with pyroxene) also 

 border the plains or basin of the Mississipi, to- 

 wards the west, at the declivity of the Rocky 

 Mountains -f\ The ancient pyrogenie rocks 

 which I found near Parapara where they rise in 

 mounds with rounded summits, are the more 

 remarkable as no others have been hitherto dis- 



* Vol. iv, 279, &c. 



+ From the sources of the Canadian river to the Rio Colo- 

 rado de Natchitotches, See Long. Exped. Vol. ii, p. 91, 

 402. 



