Buenos Ayres presents on its eastern territories a tract of land so nearly level that many of its principal rivers, unable to roll themselves forward with sufficient impetus, form large shallow lakes, and it has been calculated that the great Paraguay in its course southward does not fall above one foot in height between the 18th and 22d degrees of south latitude.
These immense levels are covered with a strong and luxuriant herbage, which pastures innumerable herds of half-wild horses and cattle. No hill or swelling rises in this expanse to a greater elevation than 600 feet above the plain, so that if placed on one of these eminences, the eye wanders over a space resembling the ocean, uninterrupted, save by the dark spots formed here and there by the grazeing cattle, or by the travelling waggons and escorts.
But on the west the viceroyalty offers a very different scene, a vast chain of mountains, whose summits are lost in the frozen regions of the air, elevate their eternal barriers between the plains of the La Plata, and the kingdoms of Peru and Chili. From this the main chain of the Andes, a secondary Cordillera, branches out between 15° and 20° of south latitude, and traversing the province of Chiquitos, it appears to, and in fact does connect the Andes of Peru and Chili with the mountain country of Brazil and Paraguay.
From it flow, on the north, the rivers that empty themselves into the Maranon, whilst its southern flank supplies the streams which swell the La Plata. This chain, named the Cordillera of Chiquitos, has not been explored by any scientific traveller, and being inhabited by savage nations, its structure and disposition are almost unknown.
The next remarkable features of this interesting country are its lakes and rivers. In the flat plains of La Plata the Los Xarayes is formed by the collected waters of the torrents which flow, during the rainy season, from the mountains of Chiquitos, and the Paraguay swelling over its banks at that period, inundates an expanse of flat land under the 17° of south latitude to an extent of 330 miles in length, and 120 in breadth; but when the waters of the Paraguay abate, this lake becomes a marsh infested with multitudes of alligators. Its banks swarm with jaguars, pumas, monkeys, stags, &c. and with venomous reptiles and insects. It is never navigable for any other vessels than canoes and small barks, in which the Portuguese cross it from their settlements in Cuyaba. Besides this lake there are many others of great size, formed in a similar manner, such as Aguaracatay, in the 25th degree, Ypoa in the 26th degree, and Neembuco in the 27th degree of south latitude.
There are also several smaller ones which are formed by the inability of the rivers to continue their course without inundating the land in the vicinity of their banks to find an outlet; these are permanent, but generally of no depth, such as Mandiha in 25° 20', Ypacary in 25° 23', and the Iberi between the 20th and 29th degree of south latitude.
This last lake gives rise to three rivers which fall into the Great Parana; viz. the Sta. Lucia, the Batela and the Corrientes from its south-west extremity, and to the Mirinay, which taking a south-east course falls into the Uruguay.
Lake Iberi is shallow and filled with aquatic plants, but is diversified with islands, on which feed deer and other animals; these islands are unlike the plain surrounding the lake, being in general covered with wood, and many settlements have been made on its banks, which are in beautiful situations, supplied with plenty of game, and fish, and it overflows twice a year.
Titicaca or Chucuito is not only among the largest but the most remarkable lakes of La Plata. It is situated between the two Cordilleras of the Andes, in the north-west part of Los Charcas, and being formed by the surrounding mountains, has no outlet, and is in some parts from 420 to 480 feet in depth: its circumference is about 240 miles, containing many islands, of which Titicaca the largest, is three leagues long and one wide, and is famous as having been the supposed residence of Manco Capac.
This lake is navigable for the largest vessels, but is subject to dreadful storms owing to the tremendous gusts of wind which rush from the Andes.