190 



several hundred feet above the road at the highest part of 

 the pass to which it gives its name, consists of tlie latter 

 rock, enclosing large rolled masses of porphyry. On the hills 

 that we passed in the morning, although at a less elevation, 

 there were no shrubs, the cold wind that sweeps unobstructed 

 over the smooth sward, being inimical to the growth of 

 young plants, which, on the contrary, find shelter among 

 the masses of rock on the ascent to La Viuda, where stunted 

 shrubs are very common. 



The pass of La Viuda is said to be 15,000 feet above the 

 level of the sea.* On gaining the summit, a league from 

 the bottom of the mountain, we came upon a more open 

 country than we had seen since the commencement of our 

 journey, though the prospect was still somewhat limited, the 

 lowest situation being, of course, chosen for the road, from 

 which we only had a partial view of the higher mountains 

 in the distance, covered with perpetual snow. We descended 

 very gradually among low ranges of black limestone, with 

 impressions of shells ; a very extensive formation in this part 

 of the Andes. The skirts of the hills, and the little vallies 

 and tracts of level ground between them, were covered with 

 verdure, and the deeper hollows were occupied by lakes, 

 the water of which was of a dark blue colour^ more intense 

 than that of the waters of the ocean ; in some of them, the 

 deeper tint was varied by patches of bright turquoise, from 

 the bottom being of a whitish colour, and the water less deep. 



We had long passed the region of trees, and even shrubs 

 had disappeared. The most conspicuous plant was a low, 

 spreading Cactus^ in large patches among the rocks; being 

 covered with abortive spines like white hairs: it had, at a 

 distance, exactly the appearance of wool. Near La Viuda, 

 I observed Culcitium rvfescens, and a species of Trevoa ; a 



* I am sorry to find that I have mislaid a memorandum of the altitudes of 

 the principal places between Lima and Pasco; they were measured barometri- 

 cally by Don Mariano Rivero, and published in Lima, in the Manorial de las 

 Ciencins Naturales, of which he was one of the conductors. As the list includes 

 several of the places where Ruiz and Pavon collected, I liope I shall be able 

 to procure a copy of it for an early number of the Botanical Miscellany. 



