The Rio de la Plata forms the third great water system of South America. The Rio Grande, its principal stream, rises in the mountains of Minas Geraes, in Brazil, and runs 500 miles on the table-land from north to south before it takes the name of Paranà. For more than 100 miles it is a continued series of cataracts and rapids, the greatest of which, the Salta Grande, is in about 24° 5ʹ lat. Above the fall the river is three miles broad, when all at once it is confined in a rocky pass only 60 yards wide, through which it rushes over a ledge with thunderous noise, heard at the distance of many miles. The Paranà receives three large rivers on the right—the Paraguay, the Pilcomayo, and the Vermejo: all generally tend to the south, and unite at different distances before entering their primary at Corrientes. The Paraguay, 1200 miles long, is the finest of these: in its upper part it is singularly picturesque, adorned with palms and other tropical vegetation, and its channel islands are covered with orange-groves. It springs from a chain of seven lakes, on the southern slopes of the Campos Parecis, in Brazil, and may be ascended by vessels of considerable burthen through nineteen degrees of latitude. The Pilcomayo and Vermejo both come from Bolivia; the former traverses the desert of the Gran Chaco, the latter the district of Tarija. At Santa Fé the La Plata turns eastward, and before entering the Atlantic is augmented by the Uruguay from the north, which takes its name from the turbulence of its streams. The Rio de la Plata is 2700 miles long, and for 200 miles from its mouth, up to Buenos Ayres, it is never less than 170 miles broad. Were it not for the freshness of its water it might be mistaken for the ocean: it is, however, shallow, and loaded with mud, which stains the Atlantic for 200 miles from its mouth. The Paraguay is subject to dreadful floods. In 1812 the atmosphere was poisoned by the putrid carcases of drowned animals. The ordinary annual inundations of the Paranà, the principal or upper branch of the La Plata, cover 36,000 square miles. In consequence of the vast extent of the very level plains along the base of the Andes, the basins of the three great rivers are apparently united. So small are the elevations that determine their direction, that, with the exception of a portage of three miles, a vessel might sail from Buenos Ayres in 35° S. lat. to the mouth of the Orinoco in 9° N. lat. by inland navigation. The Colorado, which runs in a long shallow stream through the Pampas of Buenos Ayres to the Atlantic, is formed of two principal branches, one from the west, and the other from the north, which unite at a great distance from the Atlantic, into which the river flows.