The Greatness Of The Mass, And The Height So Long Attributed To Points Whence Several Considerable Branches Issue, Was Founded Either On Theoretic Ideas Or On False Measures.

The Cordilleras were compared to rivers that swell as they receive a number of tributary streams.

Among the basins which the Andes present, and which form probably as many lakes or small inland seas, those of Titicaca, Rio Jauja and the Upper Maranon, comprise respectively 3500, 1300, and 2400 square leagues of surface.* (* I here subjoin some measures interesting to geologists. Area of the Andes, from Tierra del Fuego to the Paramo de las Rosas (latitude 9 1/4 degrees north), where the mountainous land of Tocuyo and Barquesimeto begins, part of the Cordillera of the shore of Venezuela, 58,900 square leagues, (20 to a degree) the four spurs of Cordova, Salta, Cochabamba and Beni alone, occupy 23,300 square leagues of this surface, and the three basins contained between latitude 6 and 20 degrees south measure 7200 square leagues. Deducting 33,200 square leagues for the whole of the enclosed basins and spurs, we find, in latitude 65 degrees, the area of the Cordilleras elevated in the form of walls, to be 25,700 square leagues, whence results (comprehending the knots, and allowing for the inflexion of the chains) an average breadth of the Andes of 18 to 20 leagues. The valleys of Huallaga and the Rio Magdalena are not comprehended in these 58,900 square leagues, on account of the diverging direction of the chain, east of Cipoplaya and Santa Fe de Bogota.) The first is so encompassed that no drop of water can escape except by evaporation; it is like the enclosed valley of Mexico,* (* We consider it in its primitive state, without respect to the gap or cleft of the mountains, known by the name of Desaghue de Huehuetoca.) and of those numerous circular basins which have been discerned in the moon, and which are surrounded by lofty mountains. An immense alpine lake characterizes the basin of Tiahuanaco or Titicaca; this phenomenon is the more worthy of attention, as in South America there are scarcely any of those reservoirs of fresh water which are found at the foot of the European Alps, on the northern and southern slopes, and which are permanent during the season of drought. The other basins of the Andes, for instance, those of Jauja, the Upper Maranon and Cauca, pour their waters into natural canals, which may be considered as so many crevices situated either at one of the extremities of the basin, or on its banks, nearly in the middle of the lateral chain. I dwell on this articulated form of the Andes, on those knots or transverse ridges, because, in the continuation of the Andes called the Cordilleras of the shore of Venezuela, we shall find the same transverse dykes, and the same phenomena.

The ramification of the Andes and of all the great masses of mountains into several chains merits particular consideration in reference to the height more or less considerable of the bottom of the enclosed basins, or longitudinal valleys.

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