270 Natural History of Volcanos and Earthquakes. 



throwing up so many red hot stones and fragments of rock, as to 

 form a mountain within twenty-four hours* 



The last occurrence we shall mention, and which is still fresh 

 in our memory, namely, the volcanic island which appeared in 

 July, 1830, in the Mediterranean, between the southwest coast 

 of Sicily and Pantellaria, shews, that these phenomena may take 

 place in two different ways. New islands may be formed in the 

 sea either by the elevation of solid rock, by violently breaking' 

 and raising up the original strata, or merely by the heaping up of 

 the loose masses which are ejected.f This event was of the lat- 

 ter description, and in its ephemeral existence exactly resembles 

 the above-mentioned case in the Azores. Under which of these 

 forms such volcanic productions appear, may depend on the na- 

 ture and thickness of the rocks to be broken through, on the depth 

 of the sea at the place of the eruption, and the strength of the 

 volcanic force. However, the visible part of this island may, 

 perhaps, as is the case with many others, only have been the 

 summit of a peak situated in the centre of a crater of elevation, 

 which remained buried in the sea, similar to the cones of many 

 land volcanos, which, if they had been situated in the sea, would 

 have been unable long to withstand the action of the waves, as is 

 the case with most of these islands. Hoffmann,! who approached 

 very near to this island, shortly after its appearance, saAV quite 

 plainly, that it was nothing else than the edge of a crater, the 

 walls of which were gradually raised above the surface of the wa- 

 ter by the materials ejected from it. From this crater vapors 

 rose uninterruptedly with great violence, yet without noise, which 

 were succeeded by the ejection of slags, sand, and ashes. The 

 appearance of this island was also preceded by a noise resembling 

 thunder, and by the elevation of a mass of black colored water to 

 a height of eighty-two feet, columns of smoke rising at the same 

 time to a great height. The accounts leave us in uncertainty 

 respecting one of the most important circumstances — whether 

 fire rose out of the crater or not. However, Hoffmann and his 

 companions are inclined to the more probable opinion, that this 

 volcano vomited no fire, and that what some observers took for 



* Annal. de Cliitn. et de Phys. t. xxvii, p. 382. 



t See, on the contrary, Von Humboldt in his Reise, t. i, p. 254, note. 



X Poggendorff's Ann. t. xxiv, p. 75. 



