"From this interesting spot we proceeded towards the mountains of the Andes, and amongst the first low hills examined several springs of petroleum, about which it is curious to observe the remains of a variety of insects, birds, and animals, which, having got entangled there, have been unable to extricate themselves:--so tenacious is this substance that (as I was assured by an eye-witness) some years ago a lion was found in the same situation, which had made fruitless attempts to escape. Following the base of this lower range southward, after a few leagues we reached the banks of the river Atuel, a copious stream much larger than either the river of Mendoza or the Tunuyan:--its bed, very unlike that of the Diamante, is very little lower than the surrounding plains, which gradually slope off to the eastward for twelve or fourteen leagues, as I had an opportunity afterwards of observing. "The north bank, where we crossed it, seems admirably adapted for an agricultural settlement: it is there that the several roads diverge across the Cordillera to San Fernando, Curico, and Talca, in Chile; and to the south into the country of the Indians. We proceeded from thence towards the Planchon, along a succession of valleys rich in pasturage, but very bare of shrubbery: in several places we saw immense masses of gypsum, and passed a mountain from which is obtained an aluminous earth, much used in Chile as a pigment for dyeing. The pass of the Planchon is along the north shoulder of a lofty mountain, apparently composed of sonorous slaty strata. My barometer unfortunately got out of order before I reached the highest elevation; but, as vegetation extends to the top of the pass, it must be considerably lower than the passes of the Portillo and of Uspallata, on both of which all vegetation ceases long before reaching the higher points of the road. The descent from the Planchon is very rough, and in many places steep: at a distance of three leagues from the top we reached our resting-place, surrounded by luxuriant vegetation, and thence descended to Curico, along a valley with steep mountains on either side, and through a continuous thicket of lofty trees and shrubs, amongst which I may enumerate the Chilian cypress, the quillay, the canelo or cinnamon-tree, the caustic laurel, a variety of myrtles, a beautiful fascia, and others no less interesting.