04 THE RIO CA8STQUIAKE. 



traversed. These veins jure several inches broad, and then 

 masses proved that their date and formation are very 

 different. I saw distinctly that, wherever they crossed each 

 other, the veins containing mica and black schorl traversed 

 and drove out of their direction those which contained only 

 white quartz and feldspar. According to the theory of 

 Werner, the black veins were consequently of a more recent 

 formation than the white. Being a disciple of the school of 

 Freyberg, I could not but pause with satisfaction at the 

 rock of Uinumane, to observe the same phenomena near the 

 equator, which I had so often seen in the mountains of my 

 own country. I confess that the theory which considers 

 veins as clefts filled from above with various substances, 

 pleases me somewhat less now than it did at that period ; 

 but these modes of intersection and driving aside, observed 

 in the stony and metallic veins, do not the less merit the 

 attention of travellers as being one of the most general and 

 constant of geological phenomena. On the east of Javita, 

 all along the Cassiquiare, and particularly in the mountains 

 of Duida, the number of veins in the granite increases. 

 These veins are full of holes and druses; and their frequency 

 seems to indicate that the granite of these countries is not 

 of very ancient formation. 



We found some lichens on the rock Uinumane, opposite 

 the island of Chamanare, at the edge of the rapids ; and as 

 the Cassiquiare near its mouth turns abruptly from east to 

 south-west, we saw for the first time this majestic branch of 

 the Orinoco in all its breadth. It much resembles the Eio 

 Xegro in the general aspect of the landscape. The trees of 

 the forest, as in the basin of the latter river, advance as far 

 as the beach, and there form a thick coppice ; but the Cassi- 

 quiare has white waters, and more frequently changes its 

 direction. Its breadth, near the rapids of Uinumane, almost 

 surpasses that of the Eio Negro. . I found it everywhere 

 from two hundred and fifty to two hundred and eighty 

 toises, as far as above Yasiva. Before we passed the island 

 of Grarigave, we perceived to the north-east, almost at the 

 horizon, a little hill with a hemispheric summit ; the form 

 which in every zone characterises mountains of granite. 

 Continually surrounded by vast plains, the solitary rocks 

 and hills excite the attention of the traveller. Contiguom 



