318 PORTILLO PASS. LoHaP. Xv, 
the course of a few years, was discovered by a man who threw a 
stone at his loaded donkey, and thinking that it was very heavy, 
he picked it up, and found it full of pure silver: the vein occurred 
at no great distance, standing up like a wedge of metal. The 
miners, also, taking a crowbar with them, often wander on Sun- 
days over the mountains. In this south part of Chile, the men 
who drive cattle into the Cordillera, and who frequent every 
ravine where there is a little pasture, are the usual disco- 
verers. 
20th.—As we ascended the valley, the vegetation, with the 
exception of a few pretty alpine flowers, became exceedingly 
scanty ; and of quadrupeds, birds, or insects, scarcely one could 
be seen. The lofty mountains, their summits marked with afew 
patches of snow, stood well separated from each other; the val- 
leys being filled up with an immense thickness of stratified allu- 
vium. The features in the scenery of the Andes which struck 
me most, as contrasted with the other mountain chains with which 
Tam acquainted, were,—the flat fringes sometimes expanding 
into narrow plains on each side of the valleys,—the bright co- 
lours, chiefly red and purple, of the utterly bare and precipitous 
hills of porphyry,—the grand and continuous wall-like dikes,— 
the plainly-divided strata which, where nearly vertical,. formed 
the picturesque and wild central pinnacles, but where less in- 
clined, composed the great massive mountains on the outskirts 
of the range,—and lastly, the smooth conical piles of fine and 
-brightly-coloured detritus, which sloped up at a high angle from 
the base of the mountains, sometimes to a height of more than 
2000 feet. ; 
I frequently observed, both in Tierra del Fuego and within 
.the Andes, that where the rock was covered during the greater 
part of the year with snow, it was shivered in a very extraordi- 
nary manner into small angular fragments. Scoresby* has ob- .-..-.: 
served the same fact in Spitzbergen. The case appears to me 
rather obscure: for that part of the mountain which is protected 
by a mantle of snow, must be less subject to repeated and great 
changes of temperature than any other part. I have sometimes 
thought, that the earth and fragments of stone on the surface, 
were verhaps less effectually removed by slowly percolating snow- 
* Scoresby’s Arctic Regions, vol. i. p. 122. 
