a

emitted at that time, but Dolomieu states that in 1775 one of a vitreous character, now observed on the north-west slope of the crater, proceeded from the mountain. The rock composing the latter is trachytic, and encircling its present crater is a larger one, broken away on the side fronting Lipari, which may be considered perhaps the ancient crater of elevation within which the existing one was subsequently

thrown up.

Close to Vulcano is an isolated rock called Vulcanello, which, though without a crater, emits from its crevices vapours of a sulphureous nature, a feeble remnant of the volcanic action by which it was formerly itself thrown up from the bosom of the sea. It is probable, at least, that it is to this event that Aristotle * refers, when he states that in the island of Vulcano part of the ground swelled up, and rose with a noise into the form of a hillock, which burst and gave vent to a great quantity of air, carrying along with it flame and ashes, the latter in sufficient quantity to cover all the town of Lipari.

The time at which this event happened seems to be fixed by other writers, for Pliny † mentions an island which emerged workings of those mysterious forces which God himself has from the beginning implanted in matter to accomplish his divine purposes !

Fortunately for the author of this work, the writers in question are unlikely in the year 1847 to retain their authority, even if they ever possessed any, over his English readers or indeed over any who are bona fide members of a Protestant establishment.

They have now for the most part migrated into an atmosphere more congenial, it is to be hoped, to their spiritual constitution, than that of their own Mother Church, although, if I mistake not, they will have already found, to their no small discomfiture, that in an inquiring age, and under a liberal pontiff, the very priests of the communion they have joined no longer care to conceal their anxiety to get rid, so far as they are able, of that cumbrous legacy of fable and imposture which the ignorance and fraud of preceding ages have entailed upon their creed-excrescences however, which seem to be regarded by these recent proselytes with more fondness, in direct proportion to their grossness and extravagance :

Uti Balbinum polypus Agnæ.” * Vide Aristot. Tepi Metewpwv, lib. ii. c. 8.

+ “Ante nos et juxta Italiam inter Æolias insulas, item juxta Cretam emersit e mari M.M.D. passuum cum calidis fontibus, altera Olympiadis CLXIII. anno tertio in Tusco sinu ; flagrans hæc violento cum Aatu." - Pliny, lib. ii. c. 87.

from the sea among the Lipari islands in the 144th Olympiad, or about 200 years before Christ, whilst Orosius fixes the event as happening in the consulship of Marcellus and Labeo, which answers to the year 182 B.C.*

Whichever of these dates be preferred, it is equally clear that the island now called Vulcano cannot have been referred to, for Thucydides, who flourished at least 400 years before Christ, mentions Hiera (Vulcano) as being cultivated, which implies that a certain time had elapsed since its productiont. It is probable therefore, that the rock which Aristotle states as having been thrown up from the sea was that now called Vulcanello, which lies at a short distance from Vulcano.

South of Stromboli, and intermediate between it and the island of Lipari, are several rocks and small islets, which Dolomieu conjectured to be the parts of a large submerged island, six miles in diameter, which existed in the time of Strabo under the name of Euonymos.

The largest of these is the island of Panaria, next in size Basiluzzo, and the others mere rocks, namely Dattolo, Lisca Nera, and Lisca Bianca. The latter is regarded by Cluverius as the Euonymos of the ancients, whilst according to the view taken by Dolomieu, it would constitute only a part of what was once that island.

Hoffman however is disposed to consider these rocks and islets as the protruding points of a great submarine tract which has been elevated above the waters, taking just the contrary view of their origin from that adopted by preceding writers.

Panaria, according to this latter geologist, consists altogether of a description of trachyte resembling some of the clay porphyries found in older secondary formations, but

a

sometimes passing into pitchstone. It is particularly described by Abich*.

Basiluzzo consists of a rock so like to granite, that both Dolomieu and Spallanzani have set it down as such. It is however, by Hoffman's account, a singular variety of trachyte, the basis being an impure felspar containing numerous snowwhite crystals of glassy felspar, and numerous scales of mica. The resemblance to granite is occasioned by the presence of grains of a vitreous mineral much resembling quartz, though less hard, which form parallel striæ in the mass.

Another variety of trachyte which also puts on the appearance of granite is of a light grey colour and granular texture, in which glassy felspar is the predominant constituent, but differing from the ordinary kind in being traversed by a number of fine pores of an oblong shape, so as to impart a fibrous or striated appearance to the mass. Black mica and grains of the same vitreous substance which occurs in the other variety are likewise diffused through it.

Abich regards this rock as a species of trachytic porphyry with a per-centage of silica amounting to 69.87, and points out the remarkable passage of so slaty and friable a material as this into a true pumice in the upper parts of the rock where the pressure was least.

a

North-west of Lipari are three other volcanic islands, namely Salina, Felicudi and Alicudi.

Salina is, next to Lipari, the most important of the group, and comprehends two very lofty mountains rising to a height of not less than 3500 feet above the sea. The lower portion of the island is composed of tuff, but the upper of numerous alternations of this deposit with beds of lava containing much augite. On the summit are the remains of a crater. Pumiceous conglomerate makes its appearance in one part of the island, but it is unaccompanied by obsidian.

Felicudi, according to Gussone, as quoted by Hoffman, resembles very nearly in its constitution Salina, consisting of alternating beds of tuff and trachytic lava. Sulphureous vapours still rise from crevices in one part of the island.

• Ueber die Zusammenhang der vulk. Bild. p. 31.

Alicudi is a single conical mountain with traces of a crater on its summit. Here lava predominates over tuff, and one kind approaches nearly to clinkstone.

Ustica, which lies about forty miles north-west of Palermo, contains three large craters, broken away on the side of the sea, and constituted in a similar manner to the foregoing islands, namely a brown loose tuff, and thick beds of trachytic lava full of felspar and augite, and sometimes containing olivine. Pumice is also abundant in many parts of the island.

Marine shells are found in one place imbedded in the tuff, and in certain spots the latter is impacted together by a calcareous matter, so as to form a breccia of great hardness, in which the same shells occur as exist in the Mediterranean at the present time. It seems therefore to follow that this island has been heaved up from the bottom of the sea at a very recent period.

CHAPTER XV.

VOLCANIC ROCKS OF SICILY, &c.

Sulphur beds.-Mud volcano of Macaluba.- Lago Naftia.–Older volcanic

rocks of the Val di Noto.-Mount Etna-description of the volcanolong succession of lava beds and tuff accumulated one above the othermode in which the mountain was formed—description of its crater. History of its eruptions—antecedent to the Christian æra—subsequent to that epoch. Volcanic energy exerted in the neighbouring parts of the Mediterranean--inferred from the phænomena of the Marobia and seaquakes experienced off the coast—also by the elevation of a new island off the coast of Sciacca.- Products of Mount Etna. Island of Pantellaria--three kinds of igneous formations.

The Lipari islands are so placed with reference to Naples and Sicily, that they seem to form a link between the two countries, whence some have inferred that a subterranean communication passes through them, extending from Etna to Vesuvius. It would be necessary however to show, in a more satisfactory manner than has hitherto been done, that the condition of any one of these volcanos is influenced by that of the rest, before we venture to adopt such an opinion*; at present I shall content myself with pointing out by a detail of the structure of Sicily, so far as the latter is connected with the present subject, what degree of resemblance may subsist between the volcanic phænomena of that island and those of Naples †.

Nearly all the central portion of Sicily is occupied by a vast deposit of blue clay or marl, in which are contained numerous and thick beds, of selenite and gypsum, of common salt, of sulphur, of combinations of that mineral with iron and copper, and of the sulphuric acid with most of the earthy bases. The crystals of sulphate of strontian found in the sulphur mines are unrivalled for their beauty; and are inter

See the chronological table of the eruptions of Etna and Vesuvius, appended to this chapter.

+ See, for a more detailed account of the geology of Sicily, my memoir inserted in Jameson's Journal, vol. xiii.