I833-] SIERRA VENTANA. 77 



hundred feet from the basin of green turf on which Bahia Blanca stands, 

 we entered on a wide desolate plain. It consists of a crumbling 

 argillaceo-calcareous rock, which, from the dry nature of the climate, 

 supports only scattered tufts of withered grass, without a single bush or 

 tree to break the monotonous uniformity. The weather was fine, bu' 

 the atmosphere remarkably hazy ; I thought the appearance forebodea 

 a gale, but the Gauchos said it was owing to the plain, at some great 

 distance in the interior, being on fire. After a long gallop, having 

 changed horses twice, we reached the Rio Sauce : it is a deep, rapid, 

 little stream, not above twenty-five feet wide. The second posta on the 

 road to Buenos Ayres stands on its banks; a little above there is a 

 ford for horses, where the water does not reach to the horses' belly ; 

 but from that point, in its course to the sea, it is quite impassable, 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 considerable river, rising at 

 the foot of the Cordillera. With respect to its source, I do not doubi 

 that this is the case ; for the Gauchos assured me, that in the middle ot 

 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. -'robably 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 Captain Fitz Roy calculates its height to be 3,340 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 Blarca 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 ; it 



