Ch, X.] OUTLINE OF COUNTRY HOW CAUSED. 127 



suited from the decomposition of felspathic lava which abounds 

 in Ischia, the materials having been transported by rivers and 

 marine currents, and spread over the bottom of the sea where 

 testacea were living. We may observe generally of these sub- 

 marine tuffs, lavas, and clays, of Campania, that they strictly 

 resemble those around the base of Etna, and in parts of the Val 

 di Noto before described. 



External configuration of the country how caused. When 

 once we have satisfied ourselves by inspection of the marine 

 shells imbedded in tuffs at high elevations, that a mass of land 

 like the island of Ischia has been raised from beneath the waters 

 of the sea to its present height, we are prepared to find signs 

 of the denuding action of the waves impressed upon the outward 

 form of the island, especially if we conceive the upheaving force 

 to have acted by successive movements. Let us suppose the 

 low contiguous island of Procida to be raised by degrees until 

 it attains the height of Ischia, we should in that case expect 

 the steep cliffs which now face Misenum to be carried upwards 

 and to become precipices near the summit of the central moun- 

 tain. Such, perhaps, may have been the origin of those pre- 

 cipices which appear on the north and south sides of the ridge 

 which forms the summit of Epomeo in Ischia. The northern 

 escarpment is about 1000 feet in height, rising from the hollow 

 called the Cavo delle Neve above the village of Panella. The 

 abrupt manner in which the horizontal tuffs are there cut off, 

 in the face of the cliff, is such as the action of the sea, working 

 on soft materials, might ^easily have produced, undermining 

 and removing a great portion of the mass. A heap of shingle 

 which lies at the base of a steep declivity on the flanks of 

 Epomeo, between the Cavo delle Neve and Panella, may once, 

 perhaps, have been a sea-beach, for it certainly could not have 

 been brought to the spot by any existing torrents. 



There is no difficulty in conceiving that if a large tract of the 

 bed of the sea near Ischia should now be gradually upheaved 

 during the continuance of volcanic agency, this newly-raised land 

 might present a counterpart to the Phlegraean fields before de- 



