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.

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