Their Barrenness, However, Is Not Owing To Their Height:

The limit of trees in this region is four hundred toises higher; since, judging according to the analogy of other mountains, this limit would be found here only at a height of eighteen hundred toises.

The absence of large trees on the two rocky summits of the Silla may be attributed to the aridity of the soil, the violence of the winds blowing from the sea, and the conflagrations so frequent in all the mountains of the equinoctial region.

To reach the eastern peak, which is the highest, it is necessary to approach as near as possible the great precipice which descends towards Caravalleda and the coast. The gneiss as far as this spot preserves its lamellar texture and its primitive direction; but where we climbed the summit of the Silla, we found it had passed into granite. Its texture becomes granular; the mica, less frequent, is more unequally spread through the rock. Instead of garnets we met with a few solitary crystals of hornblende. It is, however, not a syenite, but rather a granite of new formation. We were three quarters of an hour in reaching the summit of the pyramid. This part of the way is not dangerous, provided the traveller carefully examines the stability of each fragment of rock on which he places his foot. The granite superposed on the gneiss does not present a regular separation into beds: it is divided by clefts, which often cross one another at right angles. Prismatic blocks, one foot wide and twelve long, stand out from the ground obliquely, and appear on the edges of the precipice like enormous beams suspended over the abyss.

Having arrived at the summit, we enjoyed, for a few minutes only, the serenity of the sky. The eye ranged over a vast extent of country: looking down to the north was the sea, and to the south, the fertile valley of Caracas. The barometer was at 20 inches 7.6 lines; the thermometer at 13.7 degrees. We were at thirteen hundred and fifty toises of elevation. We gazed on an extent of sea, the radius of which was thirty-six leagues. Persons who are affected by looking downward from a considerable height should remain at the centre of the small flat which crowns the eastern summit of the Silla. The mountain is not very remarkable for height: it is nearly eighty toises lower than the Canigou; but it is distinguished among all the mountains I have visited by an enormous precipice on the side next the sea. The coast forms only a narrow border; and looking from the summit of the pyramid on the houses of Caravalleda, this wall of rocks seems, by an optical illusion, to be nearly perpendicular. The real slope of the declivity appeared to me, according to an exact calculation, 53 degrees 28 minutes.* (* Observations of the latitude give for the horizontal distance between the foot of the mountain near Caravalleda, and the vertical line passing through its summit, scarcely 1000 toises.) The mean slope of the peak of Teneriffe is scarcely 12 degrees 30 minutes. A precipice of six or seven thousand feet, like that of the Silla of Caracas, is a phenomenon far more rare than is generally believed by those who cross mountains without measuring their height, their bulk, and their slope. Since the experiments on the fall of bodies, and on their deviation to the south-east, have been resumed in several parts of Europe, a rock of two hundred and fifty toises of perpendicular elevation has been in vain sought for among all the Alps of Switzerland. The declivity of Mont Blanc towards the Allee Blanche does not even reach an angle of 45 degrees; though in the greater number of geological works, Mont Blanc is described as perpendicular on the south side.

At the Silla of Caracas, the enormous northern cliff is partly covered with vegetation, notwithstanding the extreme steepness of its slope. Tufts of befaria and andromedas appear as if suspended from the rock. The little valley which separates the domes towards the south, stretches in the direction of the sea. Alpine plants fill this hollow; and, not confined to the ridge of the mountain, they follow the sinuosities of the ravine. It would seem as if torrents were concealed under that fresh foliage; and the disposition of the plants, the grouping of so many inanimate objects, give the landscape all the charm of motion and of life.

Seven months had now elapsed since we had been on the summit of the peak of Teneriffe, whence we surveyed a space of the globe equal to a fourth part of France. The apparent horizon of the sea is there six leagues farther distant than at the top of the Silla, and yet we saw that horizon, at least for some time, very distinctly. It was strongly marked, and not confounded with the adjacent strata of air. At the Silla, which is five hundred and fifty toises lower than the peak of Teneriffe, the horizon, though nearer, continued invisible towards the north and north-north-east. Following with the eye the surface of the sea, which was smooth as glass, we were struck with the progressive diminution of the reflected light. Where the visual ray touched the last limit of that surface, the water was lost among the superposed strata of air. This appearance has something in it very extraordinary. We expect to see the horizon level with the eye; but, instead of distinguishing at this height a marked limit between the two elements, the more distant strata of water seem to be transformed into vapour, and mingled with the aerial ocean. I observed the same appearance, not in one spot of the horizon alone, but on an extent of more than a hundred and sixty degrees, along the Pacific, when I found myself for the first time on the pointed rock that commands the crater of Pichincha; a volcano, the elevation of which exceeds that of Mont Blanc.* (* See Views of Nature, Bohn's edition, page 358.) The visibility of a very distant horizon depends, when there is no mirage, upon two distinct things:

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