8uO ELEVATION OF THE LLAXOS. 



de los Vertentes (group of Canastra and the Brazilian 

 Pyrenees'), 450 toises. Further west, the surface of the soil 

 seems to present but slight undulations ; but no measure of 

 height has been made beyond the meridian of Villaboa. 

 Considering the system of the mountains of Brazil in their 

 real limits, we find, except some conglomerates, the same 

 absence of secondary formations as in the system of the 

 mountains of the Orinoco (group of Parime). These se- 

 condary formations, which rise to considerable heights in the 

 Cordillera of Venezuela and Cumana, belong only to the 

 low regions of Brazil. 



B. Plains (Llanos) or Basins. 



In that part of South America situated on the east of the 

 Andes, we have successively examined three systems of 

 mountains, those of the shore of Venezuela, of the Parime, 

 and Brazil: we have seen that this mountainous region, 

 which equals the Cordillera of the Andes, not in mass, but 

 in area and horizontal section of surface, is three times less 

 elevated, much less rich in precious metals adhering to the 

 rock, destitute of recent traces of volcanic fire, and, with 

 the exception of the coast of Venezuela, little exposed to 

 the violence of earthquakes. The average height of the 

 three systems diminishes from north to south, from 750 to 

 400 toises ; those of the culminant points (maxima of the 

 height of each group) from 1350 to 1000 or 900 toises. 

 Hence it results that the loftiest chain, with the exception 

 of the small insulated system of the Sierra Nevada of Santa 

 Marta, is the Cordillera of the shore of Venezuela, which is 

 itself but a continuation of the Andes. Directing our at- 

 tention northward, we find in Central America (lat. 12 30), 

 and North America (lat. 30 70), on the east of the Andes 

 of Guatimala, Mexico, and Upper Louisiana, the same regular 

 lowering which struck us towards the south. In this vast 

 extent of land, from the Cordillera of Venezuela to the 

 polar circle, eastern America presents two distinct systems, 

 the group of the mountains of the "West Indies (which in 

 its eastern part is volcanic) and the chain of the Alleghanies. 

 The former of these systems, partly covered by the ocean, 

 may be compared, with respect to 'its relative position and 



