579 



suits, that the same formations do not consti- 

 tute the region of plains and of mountains. 



If we may be permitted to judge of the struc- 

 ture of the whole Sierra Parime, from the con- 

 siderable part which I have examined in 6° of 

 longitude, and 4° of latitude, we may believe it 

 to be entirely composed of gneiss-granite; I 

 saw some beds of green-stone, and amphibolic 

 slate, but neither mica-slate, clay-slate, nor 

 banks of green lime-stone, although many phe- 

 nomena render the presence of the former of those 

 rocks probable, on the east of the Maypuresand 

 in the chain of Pacaraina. The geological forma- 

 tion of the groupe ofParime, is consequently still 

 more simple than that of the Brazilian groupe, in 

 which granites, gneiss, and mica-slate, are cover- 

 ed with thonschiefer, chloritous quartz (I tacolu- 

 mite),grauwakke, and transition limestone*; but 

 those two groupes have in common, as we have 

 already mentioned, the absence of a real sys- 

 tem of secondary rocks ; we find in both some 

 fragments only of sand-stone or silicious con- 

 glomerate. In the Cordillera of the shore of 

 Venezuela ^, the granitic formations predomi- 

 nate ; but they are wanting towards the east, 

 and especially in the southern chain, where we 



■ 



* See my Essay on the position of rocks, p. 96, and 

 Eschwege, Geogn. Gemalde, pp. 7, 17, 24. 



t On its limits and divisions, see Vol. vi, pp, 485 — 505, 



2 q 2 



