850 
ELETATION OF THE LLAITOS. 
de los Verteiites (group of Cauastra and the Brazilian 
Pyrenees), 450 toises. Further west, the surface of the soil 
seems to present but slight undulations ; but no measure of 
lieight 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 Cumaua, 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 horizonta,! 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. Tlie average height of the 
three systems diminishes from north to south, from 750 to 
■100 toises ; those of the culminant points (maxima of the 
height of each group) from 1350 to 1000 or 900 toises. 
Ii eiice it results that tlie loftiest chain, with the exception 
of the small insulated system of tlie Sierra Xevada of Santa 
Marta, is the Cordillera' of the shore of Venezuela, which is 
itself but a continuation of tbe 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 (wiiieh in 
its eastern part is volcanic) and the chain of the Alleghanics. 
The former of these systems, partly covered by the ocean, 
may be compared, with respect to its relative position and 
