tract of dry land encompassed with water; in which sense it stands contradistinguished from Continent, or Terra Firma.

Several naturalists are of opinion, that the islands were formed at the deluge; others think, that there have been new islands formed by the casting up of vast heaps of clay, sand, mud, &c.; others think they have been separated from the continent by violent storms, inundations, and earthquakes. These last have observed, that the East Indies, which abound in islands more than any other part of the world, are likewise more annoyed with earthquakes, tempests, lightnings, volcanoes, &c. than any other part. Others again conclude, that islands are as ancient as the world, and that there were some at the beginning; and among other arguments, support their opinion from Gen. x. 5, and other passages of Scripture.

Varenius thinks that there have been islands produced each of these ways. St Helena, Ascension, and other steep rocky islands, he supposes to have come by the sea's overflowing their neighbouring campaigns; but by the heaping up huge quantities of sand, and other terrestrial matter, he thinks the islands of Zealand, Japan, &c., were formed. Sumatra and Ceylon, and most of the East India islands, he thinks, were rent off from the main land; and concludes, that the islands of the Archipelago were formed in the same way, imagining it probable that Deucalion's flood might contribute towards it. The ancients had a notion that Delos, and a few other islands, rose from the bottom of the sea; which, how fabulous soever it may appear, agrees with later observations. Seneca takes notice, that the island Thera rose thus out of the Aegean sea in his time, of which the mariners were eye witnesses.

It is indeed very probable, that many islands have existed not only from the deluge, but from the creation of the world; and we have undoubted proofs of the formation of islands in all the different ways above mentioned. Another way, however, in which islands are frequently formed in the South sea, is by the coralline insels. On this subject there is a curious dissertation by Alexander Dalrymple, Esq. in the Philosophical Transactions for the year 1768, to which we refer the reader. See also Geography Index.

ISLANDS of Ice. See ICE-Island.

Floating ISLANDS. Histories are full of accounts of floating islands; but the greatest part of them are either false or exaggerated. What we generally see of this kind is no more than the concretion of the lighter and more viscous matter floating on the surface of the water in cakes; and, with the roots of the plants, forming conglomerates of different sizes, which, not being fixed to the shore in any part, are blown about by the winds, and float on the surface. These are generally found in lakes, where they are confined from being carried too far; and, in process of time, some of them acquire a very considerable size. Seneca tells us of many of these floating islands in Italy; and some later writers have described not a few of them in other places. But, however true these accounts might have been at the time when they were written, very few proofs of their authenticity are now to be found; the floating islands having either disappeared again, or been fixed to the sides in such a manner as to make a part of the shore. Pliny tells us of a great island which at one time swam about in the lake Cutilia in the country of Reatium, which was discovered to the old Romans by a miracle; and Pomponius tells us, that in Lydia there were several islands so loose in their foundations, that every little accident shook and removed them.

(or Iceland) Crystal. See CRYSTAL, Island; MINERALOGY Index.