Journal of the Royal Geographical Society of London/Volume 1/On the Columbretes, Volcanic Rocks near the coast of Valencia, in Spain
The increased avidity with which the study of nature is now pursued, has undeniably been aided by the geographical inquiries of the last century; and it is obvious that the same influence will still be strongly exerted in establishing a knowledge of the organic and inanimate relations of the globe. I therefore offer no excuse for drawing attention to the subject of the present communication.Much discussion has been lately directed towards St. Paul's, Santorin, and other volcanic islands, which enclose circular bays, or gulfs, whence the theory of 'craters of elevation' has arisen; and it may therefore be acceptable to learn that there is another, which, though almost in our neighbourhood, has not been suspected by geologists. About thirty-five miles to the eastward of the limestone range which separates the alluvial plains of Valencia
and Tortosa, and in a bearing with the northern capes of Majorca, is a group of rugged rocks, sometimes termed Monte Colibre—a name adopted by d'Anville, and also by the recondite editor of the 'Quarter Waggoner:' but they are more generally known amongst Mediterranean navigators as the Columbretes, though, as no plan has hitherto been published, geographers have had very indistinct uotions of their extent and geognosy. Tosiňo, the author of the best description we have of the Spanish coasts, remarks— 'It is said that the small islands and rocks amount to fourteen;' from whence, as well as from the erroneous position he has assigned them, his stating the bay to be on the N.E. side, and his describing the smaller islets as lying S.S.E. of the large one, we may infer that he did not personally visit them. The industrious Coronelli, in his lsolario, dismisses them thus:—' Tra la Majorica, e le foci del fiume Ebro, si vede la Mammeolibra, si piccola, e povera, che non havendo cos' alcuna di considerabile, non merita altra descrittione.'
My attention was first attracted to these rocks from perceiving a xebec at anchor in the port, while we were passing them in chase of a stranger; and I then admired the picturesque forms of the broken masses, which presented the appearance of being the wrecks of a more considerable island. But on a second visit I was so struck with their peculiarities that I examined them with some interest; and although giving appellations on such a coast may seem intrusive, I was led to call the highest hill by the well known name of Monte Colibre, and also to denominate the several rocks after those Spanish officers to whom geography and science are deeply indebted, in order that future visiters may distinguish them in description.
The largest of the Columbretes, from its comparative magnitude, may merit the name of island. A reference to the plan will at once show how evidently it has resulted from igneous causes, and that its harbour is the mere mouth of an ancient crater, though now forming a tolerably secure anchorage for vessels, in westerly winds. Here privateers, and especially, the corsairs of Barbary, have been known to lurk; and as the summit of the hill commands an extensive horizon, they have pounced upon their prey very unexpectedly. The port is somewhat more than a quarter of a mile across at the entrance; and as it forms a capacious basin, would hold several vessels, in case of need, in from five to twelve fathoms, on an indifferent bottom of mud, weed, and rocks. It is tolerably secure from all winds but those from N.E., E., and S.E.; though, in the latter case, craft might find shelter close to the Mammeolibre, the channel between which and the point is practicable for boats, having nowhere less than three fathoms depth. I was told, by a fisherman of Valencia. that fresh water might be obtained in small quantities, but we found none. By observations taken on Monte Colibre, the latitude of the station was in 39° 53′ 58″ N., the longitude 0° 44′ 27″ E. of Greenwich, and the magnetic variation was 17° 41′ W., in 1823.
Monte Colibre, or the north hill, is of so rounded a form as to assume the bell-shaped disposition incident to its affinities; a declivity dips from thence towards the middle of the island, from which there is a gradual ascent to a hilly hummock ou the south, giving the whole the appearance known to seamen as saddled. These hills are covered with an exuberance of dwarf olives, geraniums, prickly pears, myrtles, and brushwood; but every other part exhibits lavas, obsidian, and scoriae, as obdurate as if the fires to which they owe their origin had been but lately extinguished. A few rabbits were seen, and the margin abounded with crabs and other shell-fish; but what excited the greatest surprise, and indeed is very remarkable, was, that the seamen were actually impeded in their progress with the instruments, by the number of snakes which infested the whole space. They were generally between two and three feet long, finely striated with dark zig-zag lines, on a bright yellow ground, blending whiter at the belly, and of great beauty.
At the south point of Port Tosiňo are two high conical rocks of vitreous trachyte, which, to preserve Coronelli's term, I called Mammeolibre. They appear to have formed part of the continuation of the crater, from which the eastern portion has either been worn away by erosion, or has disappeared by subsidence; for there can be little doubt of its having been a complete cone when this spot was the theatre of burning eruptions. Indeed, the encroaching and destroying action of the sea is everywhere strongly attested by the figure of the shattered relics; and the overhanging precipices, with the shadows cast by a fervid sun over cavernous cliffs, enriched with the protruding faces, and surmounted by parallel strata of porphyritic conglomerate of various hues, heighten the effect of a scene which is splendid and characteristic, notwithstanding that the expanded horizon renders the foreground somewhat diminutive.
About a mile to the westward of Monte Colibre is a group of rugged rocks, of which Malaspina, the largest, is saddled in form, but of a bold and various surface; while the gentle inclination of its external flanks, as well as those of its neighbour Bauza, together with the scarped faces of their interior cliffs to the northward, gives them also the aspect of the rent cone of a former volcano,—perhaps a parasite of the larger one.
Bearing S. 16° W., and distant three nautical miles from the station on Monte Colibre, is Galiano, a high perforated rock resembling a ship under full sail; and several rocks and reefs stretch more than half a mile to the eastward of it, against and over which the sea breaks very heavily in gales. Nearly in mid-distance between Galiano and Malaspina lies Ferrer, a remarkable quoin-shaped phonolitic rock, with smaller ones in its vicinity; so that the Columbretes are divided into four detached clusters, with deep water in the channels between them. The approach on all sides is extremely bold, and the soundings gradual, diminishing from fifty fathoms, over a bottom of brown sand and broken shells, at three or four miles off, to forty and twenty in the passages between the rocks, except where Fidalgo, Lopez, and Luyundo reefs are placed. Even between Ferrer and Joachim, there are no less than thirty fathoms of depth.
The whole of these volcanic fragments consist of similar materials; and amongst the specimens which I brought away are compact lavas, some of which are speckled with white calcined substances, while others contain black acicular crystals, and numerous small clusters of brilliant yellow ones; the former having probably lost their water of crystallization from intense heat, and the latter been formed by the condensation of vapours in the cavities of inflated lavas, on cooling. Intermixed with the scoriae—which are highly tinged with iron, and so cellular as to resemble coarse pumice—are numerous masses of amorphous schorl; and both hyperstone and pearlstone occur.
The geological relations of these islets, however, are not the only interesting points relating to them: their ancient nomenclature requires also some elucidation. It is known that the Greek geographers applied the name of Ophiusa to an Iberian island, from its abounding with serpents, and that the Romans, for the same reason, called it Colubraria; but the identity of the place has rather been inferred than ascertained—custom having long conferred the name on Formentera; and, to countenance the application, we have been gravely told of the myriads of snakes which have caused it to remain uninhabited. But a visit to the spot proves the misnomer; for from its population (despite of Aigerine ravages) and its culture, together with the numerous vestiges of matamore granaries, it is readily seen that the present appellation has been a consequence of the excellence of its corn harvests. Iviza, or Ibiza, the Ebusus of Strabo, and Ebyssus? of Ptolemy, was undoubtedly called Pityusa major, and Formentera Pityusa minor,—names which they deserve still from their resinous pine-trees; and the peculiar boast of the natives is, that no venomous reptile can live in Formentera, whether from the presence of the semper virens, one of the snake-roots of antiquity, or that their earth has the quality of destroying serpents, as Pliny records that of Ebusus to have done, I know not. Suffice it, that the fact wars against the French encyclopaedists, and others, who have asserted this island to remain desert and uninhabited—'à cause de la quantite extraordinaire de serpens qui s'y trouvent;' and where, then, are we to look for the Ophiusa of the ancients, but in the Columbretes?