380 
GEAIflTE EOCKS. 
tution. of the coast aud the Sierra Parime, we prefer to 
treat of granite, gneiss, aud mica-slate, if not as one forma- 
tion, at least as three co-ordinate formations closely linked 
together The primitive clay-slate (urthonschiefer) is sub- 
ordinate to mica-slate, of which it is only a modification. 
It no more forms an independent stratum in the New Con- 
tinent, than in the Pyrenees and the Alps. 
(a) GrEANiTE which does not pass to gneiss is most com- 
mon in the western part of the coast-chain between Turmero, 
Valencia, and Porto Cabcllo, as well as in the circle of the 
Sierra Parime, near the Encaramada, and at the Peak of 
Duida. At the llincon del Diablo, between Jlariara and 
Hacienda de Cura, and at Chuao, it is coarse-grained, and 
contains fine crystals of felspar, 1-^ inches long. It is 
divided in prisms by perpendicular vents, or stratified regu- 
larly like secondary limestone, at Las Trincheras, the strait 
of Baraguan in the valley of the Orinoco, and near 
Ouapasoso, on the banks of the Atabapo. The stratified 
granite of Las Trincheras, giving birth to very hot springs 
(from 90-5° cent.), appears from the inclination'of its layers, 
to be superposed on gneiss which is seen further southward 
iji the islands of the lake of Valencia; but conjectures of 
superposition founded only on the hypothesis of an inde- 
finite prolongation of the strata, are doubtful ; and possibly 
the gi-anite masses which form a small particular zone in 
the northern range of the littoral Cordillera, between 70° 3' 
and 70° 50' long., were upheaved in piercing the gneiss. 
The latter rock is prevalent, both in descending from the 
Biiicon del Diablo southward to the hot-springs of Mariara, 
and towards the banka of the lake of Valencia, and in 
advancing on the east towards the group of Buenavista, 
the Silla of Caracas, and Cape Codera. In the region of the 
littoral chain of Venezuela, where granite seems to con- 
stitute an independent formation from 15 to 16 leagues in 
length, I saw no foreign or subordinate layers of gneiss, 
mica-slate, or primitive limestone.* 
* Primitive limestone, everywhere so common in mica-slate and gneiss, 
is found in the granite of the Pyrenees, at Port d’06, and in the moun- 
tains of Labourd. 
