1833.] SIERRA VENTANA. 107 
Insignificant as this stream is, the Jesuit Falconer, whose 
information is generally so very correct, figures it as a consider- 
able river, rising at the foot of the Cordillera. With respect 
to its source, I do not doubt that this is the case; for the Gau- 
chos assured me, that in the middle of the dry summer, this 
stream, at the same time with the Colorado, has periodical floods ; 
which can only originate in the snow melting on the Andes. It 
is extremely improbable that a stream so small as the Sauce 
then was, should traverse the entire width of the continent ; and 
indeed, if it were the residue of a large river, its waters, as in 
other ascertained cases, would be saline. During the winter 
we must look to the springs round the Sierra Ventana as the 
source of its pure and limpid stream. I suspect the plains of 
Patagonia, like those of Australia, are traversed by many water- 
courses, which only perform their proper parts at certain periods. 
Probably this is the case with the water which flows into the 
head of Port Desire, and likewise with the Rio Chupat, on the 
banks of which masses of highly cellular scoriz were found by 
the officers employed in the survey. 
As it was early in the afternoon when we arrived, we took 
fresh horses, and a soldier for a guide, and started for the Sierra 
de Ja Ventana. This mountain is visible from the anchorage 
at Bahia Blanca; and Capt. Fitz Roy calculates its height to be 
8340 feet—an altitude very remarkable on this eastern side of 
the continent. Iam not aware that any foreigner, previous to 
my visit, had ascended this mountain; and indeed very few of 
the soldiers at Bahia Blanca knew anything about it. Hence 
we heard of beds of coal, of gold and silver, of caves, and of 
forests, all of which inflamed my curiosity, only to disappoint it. 
The distance from the posta was about six leagues, over a level 
plain of the same character as before. The ride was, however, 
interesting, as the mountain began to show its true form. When 
we reached the foot of the main ridge, we had much difficulty in 
finding any water, and we thought we should have been obliged 
to have passed the night without any. At last we discovered 
some by looking close to the mountain, for at the distance even 
of a few hundred yards, the streamlets were buried and entirely 
lost in. the friable calcareous stone and loose detritus. I do not 
think Nature ever made a more solitary, desolate pile of rock; 
