1633.] 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 scoriae 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 la Ventana. This mountain is visible from the anchorasre 

 at Bahia Blanca ; and Capt. Fitz Roy calculates its height to be 

 3340 feet an altitude very remarkable on this eastern side of 

 the continent. I am 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 j 



