DEPTH OF THE TALLEtS. 
317 
The first is so encompassed that no drop of n ater can escape 
except hy evapoi'atioir ; it is like the enclosed valley of 
Mexico and of those numerous circular basins which have 
been discerned in the moon, and which are surrounded by 
lofty mountains. An immense alpine lake characterizes the 
basin of Tiabuanaeo or Titicaca; this phenomenon is the 
more worthy of attention, as in South America there are 
scarcely any of those resen'oirs of fresh water which aro 
found at the foot of the European Alps, on the northern and 
southern slopes, and which are permanent during the season 
of drought. The other basins of the Andes, for instance, those 
of Jauia, the Epper Maranon, ami Cauca, pour their waters 
into natural canals, which may be considered as so many 
crevices situated either at one of the extremities ot th^e basin 
or on its banks, nearly in the middle of the lateral chain. 1 
dwell on this articulated form of the Andes, on those knots 
or transverse ridges, because, in the contiiuiation ot the Andes 
called the Cordilleras of the shore ot Venezuela, we shall 
find the same transverse dykes, and the same phenomena. 
The ramification of the Andes and of all the great masses 
of mountains into several chains, merits particular considera- 
tion in reference to the height more or less considerable ol 
the bottom of the enclosed basins, or longitudinal valleys. 
Geologists have hitherto directed more attention to the suc- 
cessive narrowing of these basins, their depth compared with 
the walls of rock that surround them, and the correspondence 
between the re-entering and the salient angles, than to the 
level of the bottom of the vaUeys. No precise measure has 
j-et fixed the absolute height of the three basins ot Titicaca, 
occupy 23,300 square leagues of this surface, and the three basins con- 
tained between lat. 6° and 20’ south measure /200 square 
ductinir 33 200 square leagues for the whole ot the enclosed basins and 
tmrweSi^'Ta^Lde^o’, the area of the Cordilleras elevated m 
the form of walls, to be 2.r,700 square leagues, whence ' 
bending the bnots, and allowing for the intle.xmn of the ‘'''““i'®) 
breadth of the Andes of 18 to 20 leagues The «"“'\Xues 
the Rio Magdalena are not comprehended in these 0“ ^ 
on account of the diverging direction of the chain, east of Cipoplayaand 
*^'*‘weconK’iu its primitive state, without respect to the gap or 
cleft of the mountains, known by the name of Desagbue de Hue- 
buetoca. 
