54 Dr Gillies's Observations on 



them in such high preservation, that their extent and dimen- 

 sions could be distinctly traced to a great extent, although there 

 is every reason to conclude that they have been rarely trodden 

 on by the foot of the traveller, since the discovery and conquest 

 of these countries by the Spaniards, now more than 300 years 

 ago. I examined the road in several places, at some distance 

 from each other, and found it to measure fifteen feet in breadth. 

 The principal preparation which it seemed to have undergone 

 was that of levelling, and the removal of all impediments, such 

 as shrubs, large stones, &c. ; its surface consisted principally 

 of the soil, gravel, and small stones, which characterized the 

 surrounding district, and seemed altogether to constitute a 

 road sufficient for all the purposes of communication, in a coun- 

 try where it is so little liable to injury from the elements, and 

 to a people who made all their journeys on foot, and possessed 

 no other beasts of burden except the llamas and alpacas, none 

 of which, it is probable, ever accompanied them to such a dis- 

 tance from their native country. The circumstance which ap- 

 peared the most remarkable, was the total absence of every kind 

 of shrubs from the line of road, unless where it had been crossed 

 by some occasional mountain torrent, or more permanent water- 

 course, which, carrying down with it some of the neighbouring 

 shrubs, had left them there to take root : with this exception, 

 its surface exhibited no other vegetation, except occasional tufts 

 of grass, or of some herbaceous plants. Such inconsiderable 

 encroachments of vegetation, during so long a period of time, 

 may at first sight appear somewhat extraordinary, yet is easily 

 accounted for in a climate such as that which charactei'izes 

 the Valley of Uspallata, where it seldom rains, and where 

 scarcely any dew falls ; so that there generally does not exist 

 sufficient moisture to nourish any other than a scanty vegeta- 

 tion, consisting of some thorny and resinous shrubs, with a few 

 patches of grass, and other less conspicuous plants. This re- 

 markable difference in the vegetation of the line of road, and 

 the surrounding country, renders the former particularly evi- 

 dent, more especially when viewed from the elevated part of 

 it, which approaches the base of the mountains, where it is 

 called La Punta del Cerro Negro. From this situation it may 

 )t»e Isaced. as far as the eye can reach, in one continuetl line, 



