Sept. 1833. SIERRA VENTANA. 125 



Gauchos assured me, that in the middle of the dry summer, 

 this stream, at the same time with the Colorado, has perio- 

 dical 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 

 anchorage at Bahia Blanca ; and Capt. FitzRoy calculates 

 its height to be 3500 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 

 any thing 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 de- 

 tritus. I do not think nature ever made a more solitary. 



