SICILY (Ital. Sicilia), an island of the Mediterranean sea belonging to Italy, separated from the mainland by the Straits of Messina, which at their narrowest part are about 2m. in width. In shape it is roughly triangular, whence the ancient poetical name of Trinacria, referring to its three promontories of Pelorum (now Faro) in the north-east, Pachynus (now Passero) in the south east, and Lilybaeum (now Boeo) in the west. Its area, exclusive of the adjacent small islands, is 9,86osq.m.; while the area of the whole group is 9,936 sq.m. Pop. (1931) 3,896,866.
The island occupies that part of the Mediterranean in which the shallowing of the waters divides that sea into two basins, and in which there are numerous indications of frequent changes in a recent geological period. The channel between Cape Bon in Tunis and the south-west of Sicily (a distance of 8om.) is, on the whole, shallower than the Straits of Messina, being for the most part under Ioo fathoms in depth, and exceeding zoo fathoms only for a very short interval, while the Straits of Messina have almost everywhere a depth exceeding 15o fathoms.
The north coast is generally steep and cliff-bound and abund antly provided with good harbours, of which that of Palermo is the finest. In the west and south and in the south part of the east side, the hills are much lower and recede farther from the sea. The coast is for the most part flat, more regular in outline and less favourable to shipping, while in the east, where the sea bottom sinks rapidly down towards the eastern basin of the Mediterranean, steep rocky coasts prevail except opposite the plain of Catania. In the northern half of this coast the lava streams of Mount Etna stand out for a distance of about 2om. in a line of bold cliffs and promontories.
The surface of Sicily lies for the most part more than 500f t. above the level of the sea. Caltanissetta, in the centre, stands ',goof t. above sea-level. Considerable mountains occur only in the north, where the lower slopes of all the heights form one continuous series of olive-yards and orangeries. Of the rest of the island the greater part forms a plateau varying in elevation and mostly covered with wheat fields. The only plain of any great extent is that of Catania, watered by the Simeto, in the east ; to the north of this plain the active volcano of Etna rises with an exceedingly gentle slope to the height of 0,868f t. from a base 400sq.m. in extent. This is the highest ele
vation of the island. The steep and narrow crystalline ridge which trends north-eastwards, and is known to geographers by the name of the Peloritan mountains, does not reach 4,000f t. The Nebrod ian mountains, a limestone range connected with the Peloritan range and having an east and west trend, rise to a somewhat greater height, and farther west, about the middle of the north coast, the Madonie culminate at the height of nearly 6,5ooft. From the western end of the Nebrodian mountains a lower range (in some places under i,5ooft. in height) winds on the whole south-eastwards in the direction of Cape Passaro. With the ex ception of the Simeto, the principal perennial streams—the Salso, the Platani and the Belice—enter the sea on the south coast.
Geology.—In general, the older beds occur along the northern coast, and progressively newer and newer beds are found towards the south. Folding, however, has brought some of the older beds to the surface in the hills which lie to the north and north-east of Sciacca. The Monti Peloritani at the north-eastern extremity of the island consist of gneiss and crystalline schists ; but with this exception the whole of Sicily is formed of Mesozoic and later deposits, the Tertiary beds covering by far the greater part. Triassic rocks form a discontinuous band along the northern coast, and are especially well developed in the neighbourhood of Palermo. They rise again to the surface in the southern part of the island, in the hills which lie to the north of Sciacca and Bivona. In both areas they are accompanied by Jurassic, and occasionally by Cretaceous, beds; but of the latter there are only a few small patches. In the south-eastern part of the island there are also a few very small outcrops of Mesozoic beds. The Eocene and Oligocene form a broad belt along the northern coast, very much more continuous than the Mesozoic band, and from this belt a branch extends southwards to Sciacca. Another patch of considerable size lies to the east of Piazza Armerina. Miocene and Pliocene deposits cover nearly the whole of the country south of a line drawn from Etna to Marsala ; and there is also a considerable Miocene area in the north about Mistretta. Vol canic lavas and ashes of a recent geological period form not only the whole of Etna but also much of the Monti Ibiei in the south.