26 THE POPULAR SCIENCE MONTHLY. 



sistency, the lava-flows have always been produced upon the slope or 

 at the base of the mountain. At each of the orifices of issue the pro- 

 jections forced out by tumultuous jets of gas have formed adventitious 

 cones of dimensions often considerable, like those of il Toppo, il Trip- 

 piti, and il Garifoli ; and we may count some ten such cones around 

 Epomeo, all of which have been centers of activity and furnished large 

 flows. 



The appearance of Ischia was relatively of recent date ; it is not 

 placed farther back than the older quaternary. The foundation of the 

 island was begun by submarine eruptions, above which opened the 

 crater of Epomeo, at first appearing above the surface of the sea as an 

 annular reef, from which were thrown out jets of trachytic scoria. 

 The island was raised up in successive stages by the accumulation of 

 the projected, matter around the orifice of issue. The proof of this is 

 drawn from the fact that we may still find on the sides of Mount 

 Epomeo, carried to a height of four hundred and seventy metres, 

 masses of marine shells of species yet living in the Mediterranean, en- 

 cased in clays that have resulted from the decomposition of trachytic 

 tufas under water. The whole of this trachytic mass is itself estab- 

 lished on marls and clays, including numerous remains of Mediterra- 

 nean shells, and has evidently acquired its present relief within the 

 historical epoch. 



The most ancient of the recorded eruptions in Ischia was that of 

 Montagnone, to which is ascribed the origin of the vast crater of regular 

 form that still existed before the recent earthquake, in a state of per- 

 fect preservation, in the northwestern part of Ischia. About 470 b. c, 

 successive eruptions at Point Comacchia gave rise to the vast flows of 

 Manecoco and Bale, which extended far into the sea and prolonged the 

 point to the north. Numerous efforts have been made since these an- 

 cient times to plant colonies on this unstable land, even then fertile 

 and covered with a luxuriant vegetation. 



Lyell, who made a long exploration of the island in 1828, relates 

 that first the Erythreans and afterward the Chalcideans, who had set- 

 tled in the island before the Christian era, were driven away by the 

 incessant earthquakes and the mephitic exhalations escaping from 

 every point. At a later time, 280 b. c, Hiero, king of Syracuse, tried 

 to found a colony there, but it was soon driven away by a formidable 

 explosion preceding the great flows of lava which gave rise to the 

 masses now forming the promontories of Zaro and Camso. 



The same fate befell the Grecian colonies which afterward tried at 

 different times to occupy the island. The eruption that forced the 

 retreat of the first Grecian colony gave rise to Monte Rosato, that 

 cone of projections the sudden formation of which is comparable to 

 that of Monte Nuovo. The last-named mountain was raised in Sep- 

 tember, 1538, in forty-eight hours, at Puzzuoli, after a succession of 

 formidable shocks which occasioned great disasters in the Phlegrean 



