They Are Composed Of Enormous Masses Of Granite Of A Parallelopipedal Figure, But Rounded At The Edges, And Heaped One Upon Another.

The blocks are often eighty feet long, and twenty or thirty broad.

They would seem to have been piled up by some external force, if the proximity of a rock identical in its composition, not separated into blocks but filled with veins, did not prove that the parallelopipedal form is owing solely to the action of the atmosphere. These veins, two or three inches thick, are distinguished by a fine-grained quartz-granite crossing a coarse-grained granite almost porphyritic, and abounding in fine crystals of red feldspar. I sought in vain, in the Cordillera of Baraguan, for hornblende, and those steatitic masses that characterise several granites of the Higher Alps in Switzerland.

We landed in the middle of the strait of Baraguan to measure its breadth. The rocks project so much towards the river that I measured with difficulty a base of eighty toises. I found the river eight hundred and eighty-nine toises broad. In order to conceive how this passage bears the name of a strait, we must recollect that the breadth of the river from Uruana to the junction of the Meta is in general from 1500 to 2500 toises. In this place, which is extremely hot and barren, I measured two granite summits, much rounded: one was only a hundred and ten, and the other eighty-five, toises. There are higher summits in the interior of the group, but in general these mountains, of so wild an aspect, have not the elevation that is assigned to them by the missionaries.

We looked in vain for plants in the clefts of the rocks, which are as steep as walls, and furnish some traces of stratification. We found only an old trunk of aubletia* (* Aubletia tiburba.), with large apple-shaped fruit, and a new species of the family of the apocyneae.* (* Allamanda salicifolia.) All the stones were covered with an innumerable quantity of iguanas and geckos with spreading and membranous fingers. These lizards, motionless, with heads raised, and mouths open, seemed to suck in the heated air. The thermometer placed against the rock rose to 50.2 degrees. The soil appeared to undulate, from the effect of mirage, without a breath of wind being felt. The sun was near the zenith, and its dazzling light, reflected from the surface of the river, contrasted with the reddish vapours that enveloped every surrounding object. How vivid is the impression produced by the calm of nature, at noon, in these burning climates! The beasts of the forests retire to the thickets; the birds hide themselves beneath the foliage of the trees, or in the crevices of the rocks. Yet, amidst this apparent silence, when we lend an attentive ear to the most feeble sounds transmitted through the air, we hear a dull vibration, a continual murmur, a hum of insects, filling, if we may use the expression, all the lower strata of the air.

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