224 



ing rock was no longer a ferruginous sandstone, 

 but granite passing into gneiss. 



April 26th. We advanced only two or three 

 leagues, and passed the night on a rock near 

 the Indian plantations or conucos of Guapasoso. 

 The river losing itself by it's inundations in the 

 forests, and it's real banks being unseen, the 

 traveller can set his foot on the land only where 

 a rock or a small table-land rises above the 

 water. The granite of those countries, by the 

 disposition which the thin lamina? of black mica 

 affect, sometimes resembles graphic granite ; 

 but most frequently, and this determines the 

 age of it's formation, it passes into a real gneiss. 

 It's beds, very regularly stratified, run from 

 south-west to north-east, as in the Cordillera on 

 the shore of Caraccas. The dip of the granite- 

 gneiss is 70° north-west. It is traversed by an 

 infinite number of veins of quartz, which are 

 singularly transparent, and three or four, and 

 sometimes fifteen inches thick. I found no 

 cavity, (druse,) no crystallized substance, not 

 even rock-crystal ; and no trace of pyrites, or 

 any other metallic substance. I enter into 

 these particulars on account of the chimerical 

 ideas, that have been spread ever since the six- 

 teenth century, after the voyages of Berreo and 

 Raleigh*, " on the immense riches of the great 

 and fine empire of Guyana." 



* Raleigh's work bears the pompous title of " The Disco- 



