ALICUDA, anciently Ericosa, one of the Lipari isles, on the northern coast of Sicily. The houses, which oc cupy only the east and south-east part of the island, are built with pieces of lava, and scarcely admit the light of day. They are situated on the declivity of the mountain, at great elevations, in order to be protected front the at tacks of the Tunisian and Turkish corsairs ; and appear, from below, like the nests of birds hanging from the (Jiffs. Though the continuity of the soil of Alicuda is perpetually broken by ledges of rocks and masses of lava ; vet the industry of the inhabitants has rendered these barren tracts so productive, by breaking them with pointed spades, that they produce barley and wheat, equal to what is obtained in any of the tEolian islands. The >oil also raises Indian figs, olive trees, and vines, from which a good wine is procured. Though the food of the inhabitants, who do not exceed 500, consists only of barley bread, wild fruits, and sometimes salt fish, yet, from the salubrity and genial temperature of the climate, they are remarkably healthy and cheerful. The island possesses no springs of fresh water ; and when there is a tract of dry weather, the inhabitants arc reduced to ex treme distress.
The island of Alicuda is completely inaccessible, ex cept on the cast and south-east coast. In Sailing round this volcanic island, the traveller is struck with the most sublime terror, while he surveys the craggy and precipitous barrier which defends it from the ocean. Every where huge pieces of rock, or immense masses of lava, which time and the dashing of the waves have precipitated from the neighbouring cliffs, raise their rug ged heads to a great height above the level of the water. The cliffs themselves present an aspect still more threatening and sublime. The deep and dark recesses, excavated in their base by the slow operation of the waves, terminate their concavity above in projecting crags, almost suspended in the air, seem to bid defiance to the laws of gravitation. Nor do these over hanging rocks consist of one solid mass. They are sometimes formed of large globular fragments, loose and unconnected ; and the wild birds, by merely perch ing upon their top, destroy their tottering equilibrium. and plunge them into the abyss below. The deep and winding ravines ; the rents with which the rocks arc torn asunder ; the frightful peaks and precipices which constantly arrest the eye, and the consolidated streams of lava broken in their course, give an air of horror and sublimity to the stupendous flanks of Alicuda.
In order to examine the geology of Alicuda, where the sides of the island had been laid bare by the sea, Spallanzani embarked on the eastern coast, and sailing a little to the north, he met with whole rocks, composed of globes of lava, porous, heavy, and blackish in its co lour, and having petrosilex for its base. It had a little
lustre, and a great degree of hardness. It assumed, upon being broken, a conchoidal figure ; it was attracted by the magnet, and emitted sparks under the stroke of steel. It contained little feldspar, but much schorl. These globes, which were of different sizes, sometimes a foot in diameter, were never arranged in beds, but al ways occurred in numerous heaps. About a mile and a half farther north, he perceived lava that was not globu lar, stretching to a great distance, and falling like a cataract into the sea. Its base is petrosilex, and its frac ture vitreous. It resembles iron in colour, and is full of schorlaceous crystallizations. A mile farther north, where the coast is less precipitous, appeared insulated masses of porphyry, which do not seem to have been touched by fire. This porphyry has petrosilex for its base. It has the colour of burned brick, and emits sparks under the stroke of steel : it is very compact, and without pores, excepting some cavities on the sur face, which are lined with crystals. These porphyritic locks resemble those of Egypt in hardness, polish, and lustre, and contain schorls and quantities of cubic and lamellar feldspar. A little farther on, where the coast again becomes steep, it is covered with tuffa, and lava again appears under the aspect of large currents, having for its base hornstone, light, porous, and penetrable by water. This lava with difficulty emits sparks under the stroke of steel ; and, when broken, feels clayish. It contains much feldspar, placed upon a dark red ground. Spallanzani perceived in the summit of the island, a hollow about half a mile in circuit, whch he supposed to have been a crater. (qv) As Spallanzani appears to have been very indifferently skilled in mineralogy, it is not easy, from his descrip tions, to refer the rocks of this island to any of the great formations, of which the crust of the globe is composed. It is highly probable, that Alicuda contains no true lava, but is composed of rocks that belong to the newest Iicetz trap, or second porphyry formations ; or it may even contain rocks of both these classes. The stream like appearance of this pretended lava, is apparently cau sed by the action of the atmosphere on the original strata of porphyry, &c. The valuable collection of mi nerals from the islands in the Mediterranean, now de posited in the museum of the university of Edinburgh, will enable when treating of those countries in suc ceeding articles, to offer new elucidations regarding their supposed volcanic origin and structure. See Voy ages dans les deux Sicile•s., par .Spallanz-um, tom. iii. chap. 18. p. 95. ; tom. iv. p. 95. Voyages dans les Isles de Li pari,/tar Doloinicu, p. 99. See also FELICUDA and GEOG NOSY, (r)