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San Martin's designs on Guayaquil having got wind, Bolivar marched the Columbian troops across the Cordillera, successfully invaded Quito, and was hastening towards Guayaquil, with a view of being beforehand with San Martin, of whose intentions upon that province he was aware.
Hence it results, that the clearing of forests, the want of permanent springs, and the existence of torrents, are three phenomena closely connected together. Countries situated in opposite hemispheres, as, for example, Lombardy bordered by the Alps, and Lower Peru inclosed between the Pacific and the Cordillera of the Andes, afford striking proofs of the justness of this assertion.
The plain, apparently with its usual gravel covering, slopes up to the foot of the Cordillera to the height of between 3,200 and 3,300 feet.
This near approach of different climates is common in the Cordillera of the Andes; but everywhere, at Mexico, at Quito, in Peru, and in New Granada, it is only after a long journey into the interior, either across plains or along rivers, that we reach the great cities, which are the central points of civilization.
On the other hand, these several circumstances, as well as the continuous union of the basins at the foot of the Cordillera, with the great plain of the Rio Rapel which still retains the marks of sea-action at various levels, and their general similarity in form and composition with the many plains near the coast, which are either similarly marked or are strewed with upraised marine remains, fully convince me that the mountains bounding these basin-plains were breached, their islet-like projecting rocks worn, and the loose stratified detritus forming their now level surfaces deposited, by the sea, as the land slowly emerged.
In other parts of the great American cordillera some of the simplest and youngest mountain ridges in the world are found. In southern Oregon, for example, lava blocks have been broken and uplifted and now stand with steep fresh faces on one side and with the old surface inclining more gently on the other.
At first it appears rather surprising, that the trade-wind along the northern parts of Chile and on the coast of Peru, should blow in so very southerly a direction as it does; but when we reflect that the Cordillera, running in a north and south line, intercepts, like a great wall, the entire depth of the lower atmospheric current, we can easily see that the trade-wind must be drawn northward, following the line of mountains, towards the equatorial regions, and thus lose part of that easterly movement which it otherwise would have gained from the earth's rotation.
Collected by M. Domeyko from the same locality, apparently near Arqueros: Terebratula aenigma and Terebratula ignaciana, in same block of limestone: Pecten Dufreynoyi. Ostrea hemispherica. Hippurites Chilensis. Turritella Andii. Nautilus Domeykus. In a collection from the Cordillera, given me: the specimens all in the same condition: Pecten Dufreynoyi. Turritella Andii. Terebratula ignaciana.
I found him most hospitable; indeed it is impossible to bear too strong testimony to the kindness with which travellers are received in almost every part of South America. The next day I hired some mules to take me by the ravine of Jolquera into the central Cordillera.
Nor let it be assumed that the Peuquenes and Portillo ranges have undergone only movements of elevation; for we shall hereafter see, that the bottom of the sea subsided several thousand feet during the deposition of strata, occupying the same relative place in the Cordillera, with those of the Peuquenes ridge; moreover, we shall see from the unequivocal evidence of buried upright trees, that at a somewhat later period, during the formation of the Uspallata chain, which corresponds geographically with that of the Portillo, there was another subsidence of many thousand feet: here, indeed, in the valley of Tenuyan, the accumulation of the coarse stratified conglomerate to a thickness of fifteen hundred or two thousand feet, offers strong presumptive evidence of subsidence; for all existing analogies lead to the belief that large pebbles can be transported only in shallow water, liable to be affected by currents and movements of undulation and if so, the shallow bed of the sea on which the pebbles were first deposited must necessarily have sunk to allow of the accumulation of the superincumbent strata.
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