The Ægean Sea has ever been the theatre of igneous phenomena, and the three little islands of Thera, Therasia, and Aspronisi, which shut in the Bay of Santorin, are built up chiefly of volcanic materials.38 In 1573 an eruptive cone suddenly appeared; in 1707 the inhabitants of Santorin saw rise up a short distance from their shores a rock that increased in size for several days and then suddenly split up. This splitting up was succeeded by a great eruption of incandescent materials; an eruption which lasted for no less than five years, forming at the end of that time an island some 400 feet high by 3,279 feet in circumference. In 1866, after many violent shocks of earthquake, the ground was rent asunder on this island and masses of volcanic matter were belched forth, whilst on the other side of the island the soil sank to such a degree that canoes were used to get to houses which but the day before were nine feet above the sea-level. This eruption went on until 1870, and the quantity of scoriæ vomited forth during its continuance welded three islets, which had hitherto been separate, to the principal island, of which they now form part. On entering the Bay of Santorin we see on every side banks of lava, beds of scoriæ, and piles of cinders of a purplish-gray color rising in cliffs to a height of more than 1,312 feet. All these materials are the result of innumerable eruptions, and the central crater of the volcano is probably situated about the middle of the bay. It is supposed that at one time a conical mountain, from 1,958 to 2,600 feet high, rose where soundings now give a depth of water of over 1,300 feet. A sudden break up of the mountain probably produced this abyss, and formidable eruptions have led to the pouring forth of immense quantities of pumice-stone. The three islets mentioned above would be the remains of the old central cone, and a bed of pumice-stone from 98 to 131 feet thick is spread over the whole of their surface, telling of a violent cataclysm of which neither history nor tradition has preserved the memory. The letters of Pliny the Younger39 say that the eruption of Vesuvius which caused the destruction of Portici lasted five days, and we know that the houses are covered with a uniformly distributed bed of pumice-stone some thirteen feet thick, and of cinders about three feet thick. Everything points to the conclusion that a very similar catastrophe overtook Santorin; there too whole villages were buried beneath cinders, stones, and molten lava, belched forth by a volcano in action; there too men were the witnesses and the victims of the eruption, as is proved by an accidental circumstance which took place some twenty-three years after.40