J. W. Judd — On Volcanos. 251 



have cut ravines hundreds of feet in depth through the hardest lava- 

 beds, leaving isolated portions of them forming high plateaux; 

 the sea has eaten into the coast-line, causing the hardest and most 

 solid masses to project as great promontories : and landslips, probably 

 resulting from earthquakes (to which the district is particularly 

 liable), have done much in bringing the central cone of Epomeo into 

 its present ruinous condition. But vast as are the changes which 

 have been produced by denuding forces upon these older portions of 

 the island, yet that these latter have all been formed within a period 

 which is, geologically speaking, very recent, is shown by the fact that, 

 with one or two exceptions, all the fossil shells found in the tuffs 

 (now raised to a height of 2000 feet in Epomeo) are still living in 

 the neighbouring Mediterranean. 



At various points, however, around this old extinct volcano of 

 Epomeo, and especially on its north-eastern side, we find a number 

 of cones and lava-streams, which by their fresh appearance are seen 

 to be clearly of much more recent elate ; and of some of these the 

 formation is recorded in historical documents. The relations of the 

 ruined central volcano of Ischia, with its lava-streams cut up by 

 denuding action into isolated plateaux, to the surrounding cinder- 

 cones and lavas, are precisely similar to those which were so long 

 ago shown by Mr. Scrope to subsist between the three great volcanos 

 of Central France and the numerous '■' puys " which surround them. 

 The series of efforts to which the Italian group of volcanos owes its 

 origin must evidently have taken place within a much shorter geo- 

 logical period than those of Central France, which go back as far as 

 the Older Miocene period ; while the latter are, however, apparently 

 quite extinct, the former are probably only passing through an inter- 

 val of repose separating periods of paroxysmal violence. 



Of the later-formed volcanic vents (" puys ") of Ischia, the prin- 

 cipal are Montagnone, Monte Eotaro with Monte Tabor, the Cas- 

 tiglione, the beautiful lake-crater known as the Lago del Bagno, 

 and the modern cinder-cone of the Cremate, of the formation of which 

 in 1301 we have the clearest historical records. 



Montagnone is a very perfect cone rising to the height of 1084 

 feet, and presenting at its summit a crater of oval form, the bottom 

 of which is 760 feet above the sea-level. The cone is almost com- 

 pletely made up of trachytic scorige and blocks of trachyte of all 

 sizes. Trachytic lava of extremely viscid character appears also to 

 have flowed from it, one narrow stream carrying away the eastern 

 side of the crater and flowing down towards Bagno, while a wider 

 current has broken down part of its northern side and cascaded down 

 a steep slope, exhibiting a remarkable banded structure where the 

 tension of the very imperfectly liquid mass has evidently been most 

 violent. Neither of these streams, however, was able to flow far, nor 

 to spread itself beyond the slope of the mountain. Many of the 

 Ischian lavas, indeed, appear to have been exuded in a condition of 

 such extreme viscosity that they accumulated immediately around 

 the vent in vast hummocky masses ; and in some cases it is difficult 

 to decide whether we are dealing with the highly scorified sur- 



