SUBMARINE VOLCANOES. 



261 



Near Santorini, in the Grecian Archipelago, submarine volcanoes 

 have repeatedly burst forth, during the last two thousand years, and 

 formed several new islands : three of the ancient eruptions are re- 

 corded by Pliny, Strabo, and Seneca. The last eruption was in the 

 year 1767. 



So recently as the year 1831, a submarine volcano, attended with 

 all the phenomena before described, broke out, not far from the 

 island of Sicily. It was visited by some French geologists in Sep- 

 tember, soon after the eruptions had so far subsided as to allow them 

 to land. Its circumference was found, by measurement, to be seven 

 hundred and eighty yards, its height about two hundred and twenty 

 feet. It appeared to be composed entirely of scoriae and loose vol- 

 canic fragments ; in the centre of these, were some hard globular 

 blocks of lava, but they appeared to have been projected from the 

 crater. The borders of the crater were about two hundred feet 

 high on one side, and about forty on the other ; the bottom was filled 

 with orange-coloured water, and covered with a thick froth. White 

 vapours issued continually, not only from the surface of the water, 

 which appeared to be in a state of ebullition, but from innumerable 

 fissures in the whole ground, and from the adjacent sea. The black 

 sand on one side of the island, for about fifty or sixty feet, appeared 

 burning. Bubbles of gas or vapour rose, apparently from the inte- 

 rior of the earth, and they threw up, with a slight detonation, volca- 

 nic sand and particles. This volcanic island had risen from the 

 depth of about five or six hundred feet below the surface of the sea. 

 M. Prevot states his belief that this volcano ejected currents of sub- 

 marine lava ; and though the island is composed of scoriae and frag- 

 ments thrown out of the crater, which is what the French denomi- 

 nate a crater of eruption, yet that it was preceded by an upheaving 

 of the soil, (souUvement,) and that there is a belt of rocks at the 

 base, which are the border of a crater of elevation, {cratere de sou- 

 levement.) M. Prevot anticipated, that owing to the loose materials 

 of which this island is composed, it would not long resist the action 

 of the waves. Indeed, the island appeared to have suffered consid- 

 erable degradation before the French geologists landed, for Captain 

 Senhouse, who visited it the preceding month, August 3d, stated its 

 circumference to be about one mile and a quarter. According to 

 Captain Swinburne, who, on the 19th of July, observed some of the 

 earliest eruptions from this volcano, the external diameter of the 

 crater was estimated at from seventy to eighty yards ; it was not 

 then more than about twenty feet above the sea. The agitated wa- 

 ter in the crater escaped by an opening on one side : he says, "Af- 

 ter the volcano had emitted, for some time, its usual quantities of 

 white steam, suddenly the whole aperture was filled with an enormous 

 mass of hot cinders and dust, rushing upwards to the height of sev- 

 eral hundred feet, with a loud roaring noise ; then falling into the 

 sea, on all sides, with a still louder noise. Renewed explosions of 



