404 
THE RIO CASSIQUIARE. 
traversed. These veins are several inches broad, and theil 
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 
I'reyberg, I could not but pause witii 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 Chamauare, 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 Kio_ 
Negro 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 Bio Negro. I found it everywhere 
from two hundred and fifty to two hundred and eighty 
toises, as far as above Vasiva. Before we passed the island 
of Garigave, 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. Contiguoul 
