This Is The Cordillera Of The Andes.

Summits of trap-porphyry rise beyond three thousand three hundred toises, and the mean height of the chain* is one thousand eight hundred and fifty toises.

(* In New Grenada, Quito, and Peru, according to measurements taken by Bouguer, La Condamine, and myself.) It stretches in the direction of a meridian, and sends into each hemisphere a lateral branch, in the latitudes of 10 degrees north, and 16 and 18 degrees south. The first of these two branches, that of the coast of Caracas, is of considerable length, and forms in fact a chain. The second branch, the Cordillera of Chiquitos and of the sources of the Guapore, is very rich in gold, and widens toward the east, in Brazil, into vast tablelands, having a mild and temperate climate. Between these two transverse chains, contiguous to the Andes, an isolated group of granitic mountains is situated, from 3 to 7 degrees north latitude; which also runs parallel to the Equator, but, not passing the meridian of 71 degrees, terminates abruptly towards the west, and is not united to the Andes of New Grenada. These three transverse chains have no active volcanoes; we know not whether the most southern, like the two others, be destitute of trachytes or trap-porphyry. None of their summits enter the limit of perpetual snow; and the mean height of the Cordillera of La Parime, and of the littoral chain of Caracas, does not reach six hundred toises, though some of its summits rise fourteen hundred toises above the level of the sea.* (* We do not reckon here, as belonging to the chain of the coast, the Nevados and Paramos of Merida and of Truxillo, which are a prolongation of the Andes of New Grenada.) The three transverse chains are separated by plains entirely closed towards the west, and open towards the east and south-east. When we reflect on their small elevation above the surface of the ocean, we are tempted to consider them as gulfs stretching in the direction of the current of rotation. If, from the effect of some peculiar attraction, the waters of the Atlantic were to rise fifty toises at the mouth of the Orinoco, and two hundred toises at the mouth of the Amazon, the flood would submerge more than the half of South America. The eastern declivity, or the foot of the Andes, now six hundred leagues distant from the coast of Brazil, would become a shore beaten by the waves. This consideration is the result of a barometric measurement, taken in the province of Jaen de Bracamoros, where the river Amazon issues from the Cordilleras. I found the mean height of this immense river only one hundred and ninety-four toises above the present level of the Atlantic. The intermediate plains, however, covered with forests, are still five times higher than the Pampas of Buenos Ayres, and the grass-covered Llanos of Caracas and the Meta.

Those Llanos which form the basin of the Orinoco, and which we crossed twice in one year, in the months of March and July, communicate with the basin of the Amazon and the Rio Negro, bounded on one side by the Cordillera of Chiquitos, and on the other by the mountains of Parime. The opening which is left between the latter and the Andes of New Grenada, occasions this communication.

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