In these lakes, according to some maps, the great Rio Colorado rises, which flows into the Atlantic, in about 40° south latitude.
The eastern part of Cujo is watered by several rivers, but of them very little is known, as these parts are mostly immense plains, in which the herbage is of such a height as to conceal the cattle and animals that feed in them. Unlike the savannahs of the Orinoco and the La Plata, they possess lofty and beautiful trees; of these a species of cocoa palm is the most singular, its leaves and branches commence from the ground, and though they bear some resemblance to those of the cocoa-nut, they are hard and sharp like the aloe, and the tree, which never exceeds eighteen feet in height, bears a fruit also resembling that of the cocoa, but containing no kernel or edible substance.
Its trunk is very large, and consists of several concentric layers, each of which to the heart, are finer as they approach the centre, and from a yellow decrease by shades to a perfect white. Of these fibrous coats, the natives make cloth which is strong and flexible, but not so soft as that of flax. The other trees of Cujo are those which are peculiar to the warm regions of Chili and La Plata; of them, the cactus family bear a large proportion, and the nopal or opuntia feeds the cochineal insect, of which, however, none are exported.
The animals of Cujo are similar to those of Buenos Ayres, or Tucuman, as jaguars, cougars or pumas, wild swine, deer, &c. The jaguars grow to a great size, even as large as an ass, and their skin, like that of the African tiger, is beautifully variegated with white, yellow and black. The natives hunt them for their skin, arming themselves in these encounters with long lances of hard wood; but they seldom attack the animal singly, three Indians usually composing the hunting party, and exerting all their address and courage to kill it. The cold parts of this province abound with vicunas, llamas, &c.
Alligators, iguanas, and other amphibious animals, frequent the lakes and rivers, which are abundantly supplied with fish.
Birds are as numerous in Cuyo as in Paraguay, from the great condor to the beautiful little picaflor, or humming-bird. Ostriches, or rather cassowaries, frequent the plains, and are so fleet in their half-running half-flying motion, that the swiftest horse is soon tired of the pursuit.
The insect and reptile tribes are as numerous as in the other warm tracts of America, and only disappear as the land elevates itself towards the cold regions of the air. Large grass-hoppers, or locusts, are so abundant in the plains, that they frequently cover several miles of country, destroying every green thing they settle on.
The northern parts of Cuyo furnish gold and silver, but the mines of these metals have been till lately unworked, owing to the poverty, or rather want of numbers of the inhabitants. Its mountains also yield lead, sulphur, coal and gypsum, while the lakes and plains furnish salt.
In the neighbourhood of St. Juan de la Frontera, the hills are wholly composed of strata of white marble of a beautiful grain. It is used by the inhabitants in making fine lime, and in building bridges over the small canals, with which they irrigate their fields.
In this country, through which the road from Buenos Ayres to Chili passes, besides the tambos or military posts of the ancient Peruvians, there are several singular monuments of a far more ancient date. These are however very imperfectly known; but one of them, on a low range of hills, between Mendoza and La Punta, has been repeatedly visited. It consists of a large stone pillar or obelisk, 150 feet in height, and twelve in diameter, on which are curious marks, supposed to resemble eastern characters; and near a river is another stone, containing the same characters, the figures of several animals, and the print of a foot, of which, the Spanish priests have availed themselves, to impress their converts with the idea, that it was the work of one of the Apostles, who left this mark as a token of his mission.