The road between Viso and San Mateo, a distance of about three leagues, is exceedingly difficult and dangerous. The ravine becomes narrowed to a mere cleft, between walls of mountain rising on either side to the height of more than a thousand feet; sometimes perpendicularly, and at other times inclining inwards, so as to form gigantic arches. The path runs along the base of these mountains, washed by the foaming waves of the stream; or it winds up the side of the precipice, over huge fragments of rock, which, being loosened by the rain, afford no secure footing for the heavily laden mules. Frequently these loosened blocks give way, and roll down into the valley. The journey from Viso to San Mateo is associated in my mind with the recollection of a most mortifying accident. A mass of rock, such as I have just described, gave way, and rolling down the precipice, hurled one of my mules into the foaming abyss. My most valuable instruments, a portion of my collections, my papers, and--to me an irreparable loss--a diary carefully and conscientiously kept for the space of fourteen months, were in a moment buried in the river. Two days afterward the current washed the dead mule ashore at Matucanas, but its load was irrecoverably lost.
Every year many beasts of burthen, and even travellers, perish on this road. In the Tambo de Viso I met an officer who, with two of his sons, was coming from the Sierra. He had placed the youngest before him, and the other, a boy of ten years of age, was seated on the mule's crupper. When they were within about half a league from Viso, a huge mass of rock, rolling down from the mountain, struck the elder boy, and hurled him into the river. The afflicted father was anxiously seeking to recover the body of his lost child.
San Mateo is on the right bank of the river, and is the largest village in this valley. It corresponds in situation with Culluay in the Quebrada of Canta; as Matucanas corresponds with the village of Obrajillo. San Mateo is 10,947 feet above the level of the sea.[62] The soil produces abundance of potatoes, Ocas (_Oxalis tuberosa_) and Ullucas (_Tropæolum tuberosum_). Maize ripens here perfectly, but the heads are small. The lucerne is also small, but very abundant; it is very much exposed to injury from the frost, and is only good for use during the five rainy months of the year. Five hundred feet higher, that is to say, about 11,500 feet above the sea, is the boundary elevation for the growth of lucerne.