388 PASSAGE OF CORDILLERA. March, 1835. 



The features in the scenery of the Andes which struck me 

 most, as contrasted with the few other mountain chains with 

 which I am acquainted, were, — the flat fringes sometimes 

 expanding into narrow plains on each side the valleys, — the 

 bright colours, chiefly red and purple, of the utterly bare 

 and precipitous hills, — the grand and continuous wall-like 

 dikes, — the strongly-marked strata which, when nearly ver- 

 tical, form the most picturesque and wild pinnacles, but 

 where less inclined, great massive mountains ; the latter 

 occupying the outskirts of the range, and the former the 

 more lofty and central parts, — lastly, the smooth conical 

 piles of fine and brightly-coloured detritus, which slope at 

 a high angle from the flanks of the mountains to their bases, 

 some of the piles having a height of more than two thou- 

 sand 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 extraordinary manner into small angular fragments. 

 Scoresby* has observed the same fact in Spitzbergen: he 

 says, " The invariably broken state of the rocks appeared to 

 have been the eff"ect of frost. On calcareous rocks, some 

 of which are not impervious to moisture, the effect is such 

 as might have been expected ; but how frost can operate in 

 this way on quartz is not so easily understood." The whole 

 phenomenon appears to me rather obscure : for that part of 

 the mountain which is covered during many months by a 

 mantle of snow, must be less subject to repeated and great 

 changes of temperature than any other, yet it is the most 

 afi'ected. I have sometimes thought, that the earth and 

 fragments of stone lying on the surface, were perhaps less 

 eff'ectuaUy removed by means of slowly percolating snow- 

 water,t than by the agency of rain, and therefore that the 



* Scoresby's Arctic Regions, vol. i., p. 122. 



t I have heard it remarked in Shropshire, that the water, when the 

 Severn is flooded from long-continued rain, is much more turbid, than 

 when it proceeds from the snow melting on the Welsh mountains. The 



