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Updated: May 24, 2025
We suffered much from the suffocating dust of the pumice-stone, in which we were continually enveloped. In the midst of this plain are tufts of the retama, which is the Spartium nubigenum of Aiton. M. de Martiniere, one of the botanists who perished in the expedition of Laperouse, wished to introduce this beautiful shrub into Languedoc, where firewood is very scarce.
The latter almost all proceed from lateral eruptions, and consequently have been exposed to an enormous pressure in the interior of the volcano. In the plain of Retama, the basaltic lavas disappear under heaps of ashes, and pumice-stone reduced to powder. These lavas, destitute of amphibole and mica, are of a blackish brown, often varying to the deepest olive green.
Such was the crater of Teneriffe before the last peak rose within its basin. Now retama, a hardy bitter shrub, grows in these plains of pumice; the flats of it are pumice and rapilli, white and brown. But the ancient crater walls stand unbroken for miles, though here and there they have been swept away, some say by floods of water belched from the pit.
It has already been observed, that from the level of the sea to Portillo, and as far as the entrance on the elevated plain of the Retama, that is, two-thirds of the total height of the volcano, the ground is so covered with plants, that it is difficult to make geological observations.
On the side toward Orotava the mountain resembles those pyramids with steps that are seen at Fayoum and in Mexico; for the elevated plains of Retama and Rambleta form two tiers, the first of which is four times higher than the second. If we suppose the total height of the Peak to be 1904 toises, the Rambleta is 1820 toises above the level of the sea.
The peak of Teneriffe presents two of these elevated plains, the uppermost of which, at the foot of the Piton, is as high as Etna, and of very little extent; while the lowermost, covered with tufts of retama, reaches as far as the Estancia de los Ingleses. This rises above the level of the sea almost as high as the city of Quito, and the summit of Mount Lebanon.
Vincent nevertheless asserted, that lavas including fragments of granite have been found on the elevated plain of Retama; and M. Broussonnet informed me, that on a hill above Guimar, fragments of mica-slate, containing beautiful plates of specular iron, had been found.
Notwithstanding the difference of composition in the recent lavas of the Peak, there is a certain regularity of position, which must strike the naturalist least skilled in geognosy. The great elevated plain of Retama separates the black, basaltic, and earthlike lava, from the vitreous and feldsparry lava, the basis of which is obsidian, pitch-stone, and phonolite.
We were then high above the clouds, the whole country below our feet being entirely shut out by them. The region of the retama was at last gained, 7000 feet above the sea. It is a peculiar broom found nowhere else but in Teneriffe. We stopped before this in a shady spot, where, among heaths and ferns, a few laurels waved around, imparting coolness to the air.
We beheld the plants divided by zones, as the temperature of the atmosphere diminished with the elevation of the site. Tufts of retama, loaded with flowers, adorn the valleys hollowed out by the torrents, and encumbered with the effects of the lateral eruptions. Below the retama, lies the region of ferns, bordered by the tract of the arborescent heaths.
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