ETNA, or YET.NA (now MONTE GIBELLO), is the largest volcano in Enrope. It is an isolated mountain, situated on the eastern coast of Sicily, and cut off from the chain of mountains which run parallel with the northern shore of the island, by a small valley, through which flows the Alcantara, and from the southern chain by a larger valley, which forms the basin of the Giaretta. Its eastern side rises directly from the Mediter ranean, 30 in. of coast being formed by the streams of its lavas. Its base is almost 90 in. in circumference, and from this it rises like an immense cone to the height of 10,874 feet.
The history of E. does not carry its far back geologically; an active volcano in the later portion of the tertiary period, it continues still to pour forth materials; and the ejected ashes, dust, and lapilli, together with the streams of molten lava, have, in the course of untold ages, built up this immense mountain. One central crater has been the prevailing outlet for these materials, and they have consequently arranged them selves into one central and dominant mound—the cone-shaped E.; but innumerable secondary and surrounding craters, each forming, by its ejected matter, an external smaller cone, exist on Etna. ,Many of these, in the progress of the growth of the moun tain, have been tfroxiiitd. and 'hid by the 'More ree6utzeruptions. Eipty, of them may be counted surrounding the upper portion of E., many being hills of considerable altitude, but all of them appearing only as trifling irregularities when viewed at a distance as. subordinate points of so imposing and colossal a mountain. Seen from the summit, they present a beautiful aspect; some bare and barren, others covered with the dark and somber pine, or with the gayer and more varied foliage of the oak, the beech, and the hawthorn, and all arranged in picturesque groups of various heights and sizes. But the most remarkable feature in E. is the Val del Bove, an immense gully excavating the eastern flank of the mountain, 5 m. across, and surrounded by nearly vertical precipices from 1000 to 5,000 IL high, on which are shown sections of innumerable lava-streams and beds of scoriae, traversed by highly inclined dikes. It has a singularly dreary and
blasted appearance.
The summit of E. rises considerably above the line of vegetation, and consequently presents, except where covered with snow, a dreary waste of black lava, scoria, and ashes, in the center of which, in a desolate plain, rises the crater-bearing cone. This is called the desert region. It is followed by 6 or 7 in. of the woody region, in which luxuriant forests of pine, oak, beech, poplar, and hawthorn abound, together with rich pasturage for herds and flocks. A varying breadth of from 2 to 11 m. of cultivated region surrounds the base of Etna. Its .great products are corn, oil, wine, fruit, and aromatic herbs.
The first recorded eruption of E. took place 476 n.c. The most remarkable that have occurred since are the following: 1169 A. D., when Catania and 15,000 of its inhabitants were destroyed; 1527, in which two villages and many human beings perished; the eruption which continued at intervals from 1664 to 1673, and destroyed many villages with their inhabitants. Numerous chasms were formed at this time; from one several miles long and 4 or 5 ft. wide were emitted a bright light and strong sulphurous from another, black smoke and quantities of stones were given out; and from others, streams of lava. In 1673, an immense volume of salt (?) water rushed down the moun tain: by some, it is supposed to have been ejected from the crater, but it is more probable that it arose from the sudden melting of the snows which covered the summit of the mountain. A very great eruption took place in 1852. Immense clouds of ash-gray dust were ejected. From two new mouths on the eastern flank there issued vast tor rents of lava, one of which was 2 m. broad, and at one time as much as 170 ft. deep. The next outbreak, in 1864-65, was of trifling importance. That of May, 1879, was much more violent; the clouds of smoke and showers of ashes and scoria being followed by the ejection of a torrent of lava from 200 to 300 ft. in width, which desolated a large tract of highly cultivated land.
The minerals peculiar to volcanic rocks occur at E., such as chrysolite, zeolite, selenite, alum, niter, vitriol, copper, mercury, and spicular iron.