366 
SLOPES OP EIVPE-STSTEMS. 
It IS bounded by plains on the left bank, from the Caeslquiaro 
to the mouth of the Atabapo, and flows in a basin which, 
geologically speaking, according to one great division of the 
surface of bouth America into three basins, we have called 
the basin of the Eio JNegro and the Amazon. The low 
the soiitliern and northern 
dejvities of the Parime and Brazil mountains, and which the 
geologist ought to mark by one name, contain, according to 
J Pr^'se anguage of hydrography, two basinf of 
ivers, those of the Upper Orinoco and the Amazon, separated 
by a ridge that runs from Javita towards Esmeralda. Erom 
these considerations it results, that a geological basin (sit 
\enia verbo) may have several recipients, and several emis- 
sancs, divided by small ndges almost imperceptible; it mav 
at the sanie time contain waters that flow to the sea by 
different furrows independent of each other, and the systems 
mlaiid rivers flowing into lakes more or less charged with 
safuie matter. A basin of a river, or hydrographic basin, has 
I ut one recipient, one emissary ; it, by a bifurcation, it gives 
Lr*"* another hydrographic basin, it is 
because the bed of the river, or the principal recipient, 
approaches so near the banks of the basin or the ridge of 
partition that tlie riilge partlv crosses it. 
1 of the inequalities of the surface of the 
globe does not present any strongly marked limits between 
the mountainous counti-y and the low regions, or geologic 
basins. Even where real chains of mountains rise like rockv 
dykes issuing from a crevice, spurs more or less considerable 
seem to indicate a lateral upheaving. While I admit the 
?nrl .flehunig the groups of mountains 
and the basins or continuous plains, I have attempted to 
calculate their surfaces according to the statements contained 
n the preceding sheets. 
SOUTH AMERICA. 
I. Mountainous part: 
.4ndes 
Littoral Chain of Venezuela 
Sierra Nevada de Merida 
Group of the Parime 
System of the Brazil mountains 
Square 
Marine Lrazues 
.. 58.900 
1,900 
200 
. 25,800 
.. 27,000 
114,400 
