1833.] SIEKKA VENTANA. 101 



sea, it is quite impasscible, and hence makes a most useful barrier 

 against the Indians. 



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 Gauchos 

 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 ex- 

 tremely 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. Fitz Eoy 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 as- 

 cended 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 



