368 CHARLES DARWIN 



wards a long deep sandy plain, strewed with broken sea- 

 shells. There was very little water, and that little saline : 

 the whole country, from the coast to the Cordillera, is an un- 

 inhabited desert. I saw traces only of one living animal in 

 abundance, namely, the shells of a Bulimus, which were 

 collected together in extraordinary numbers on the driest 

 spots. In the spring one humble little plant sends out a few 

 leaves, and on these the snails feed. As they are seen only 

 very early in the morning, when the ground is slightly damp 

 with dew, the Guascos believe that they are bred from it. I 

 have observed in other places that extremely dry and sterile 

 districts, where the soil is calcareous, are extraordinarily 

 favourable to land-shells. At Carizal there were a few cot- 

 tages, some brackish water, and a trace of cultivation : but it 

 was with difficulty that we purchased a little corn and straw 

 for our horses. 



4th. Carizal to Sauce. We continued to ride over desert 

 plains, tenanted by large herds of guanaco. We crossed also 

 the valley of Chaneral; which, although the most fertile one 

 between Guasco and Coquimbo, is very narrow, and produces 

 so little pasture, that we could not purchase any for our 

 horses. At Sauce we found a very civil old gentleman, super- 

 intendent of a copper-smelting furnace. As an especial 

 favour, he allowed me to purchase at a high price an armful 

 of dirty straw, which was all the poor horses had for supper 

 after their long day's journey. Few smelting- furnaces are 

 now at work in any part of Chile ; it is found more profitable, 

 on account of the extreme scarcity of firewood, and from 

 the Chilian method of reduction being so unskilful, to ship the 

 ore for Swansea. The next day we crossed some mountains 

 to Freyrina, in the valley of Guasco. During each day's ride 

 further northward, the vegetation became more and more 

 scanty; even the great chandelier-like cactus was here re- 

 placed by a different and much smaller species. During the 

 winter months, both in northern Chile and in Peru, a uniform 

 bank of clouds hangs, at no great height, over the Pacific. 

 From the mountains we had a very striking view of this 

 white and brilliant aerial-field, which sent arms up the valleys, 

 leaving islands and promontories in the same manner, as the 

 sea does in the Chonos archipelago and in Tierra del Fuego. 



