1835.] VILLA VICENCIO. 329 



cross a long and most sterile traversia of fifteen leagues. 

 The soil in parts was absolutely bare, in others covered 

 by numberless dwarf cacti, armed with formidable spines, 

 and called by the inhabitants "little lions." There were, 

 also, a few low bushes. Although the plain is nearly 

 three thousand feet above the sea, the sun was very 

 powerful ; and the heat, as well as the clouds of im- 

 palpable dust, rendered the travelling extremely irksome. 

 Our course during the day lay nearly parallel to the 

 Cordillera, but gradually approaching them. Before 

 sunset we entered one of the wide valleys, or rather bays, 

 which open on the plain : this soon narrowed into a 

 ravine, where a little higher up the house of Villa Vicencio 

 is situated. As we had ridden all day without a drop of 

 water, both our mules and selves were very thirsty, and 

 we looked out anxiously for the stream which flows down 

 this valley. It was curious to observe how gradually 

 the water made its appearance: on the plain the course 

 was quite dry ; by degrees it became a little damper ; 

 then puddles of water appeared ; these soon became 

 connected ; and at Villa Vicencio there was a nice little 

 rivulet. 



March 'Tpth. — The solitary hovel which bears the Im- 

 posing name of Villa Vicencio, has been mentioned by 

 every traveller who has crossed the Andes. I stayed here 

 and at some neighbouring mines during the two succeeding 

 days. The geology of the surrounding country is very 

 curious. The Uspallata range is separated from the main 

 Cordillera by a long narrow plain or basin, like those so 

 often mentioned in Chile, but higher, being six thousand 

 feet above the sea. This range has nearly the same 

 geographical position with respect to the Cordillera, which 

 the gigantic Portillo line has, but it is of a totally different 

 origin : it consists of various kinds of submarine lava, 

 alternating with volcanic sandstones and other remarkable 

 sedimentary deposits ; the whole having a very close 

 resemblance to some of the tertiary beds on the shores 

 of the Facillc. P'rom this resemblance 1 expected to find 

 silicified wood, which is generally characteristic of those 

 formations. I was gratified in a very extraordinary 

 manner. In the central part of the range, at an elevation 

 of about seven thousand feet, I observed on a bare slope 

 some snow-white projecting columns. These were petrified 

 trees, eleven being silicified, and from thirty to fort 



