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Show 126 NEWER PLIOCENE PERIOD. (Ch. X. loose lapilli. The subaqueous part may have bec.ome solid .by an aggregative process iike that which takes place m the settmg of mortar, while the rest of the ejections, having accumulated on dry land when the cone was raised above the water, may have remained in a loose state "'. Age of the volcanic and associated 'l'oofcs of Campania.- If we enquire into the evidence derivable from organic remains, respecting the age of the volcanic rocks of Campania, we £nd reason to conclude that such parts as do not belong to the recent, are referrible to the newer Pliocene period. In the solid tuff quarried out of the hills immediately behind Naples, are found recent shells of the genera Ostrea, Cm·dium, Buccinum, and Patella, all referrible to species now Iivincr in the Mediterranean f. In Ischia I collected marine b shells in beds of clay and tuff, not far from the summit of Epomeo, or San Nichola, about 2000 feet above the level of the sea, as also at another locality, about 100 feet below, on the southern declivity of the mountain, and others not far above the town of Moropano. At Casamicciol, and several places nenr the sea-shore, shells have long been observed in stratified tuff and clay. From these various points I obtained, during a short excursion in Ischia, 28 species of shells, all of which, with one exception, were identified by M. Deshayes with recent species t· As the highest parts of Epomeo are composed of regularly-stratified greenish tuff, and some beds near the summit contain the fossils above-mentioned, it is clear that that mountain was not only raised to its present height above the level of the sea, but was also formed since the Mediterranean was inhabited by the existing species of testacea. In the Ischian tuffs we find pumice, lapilli, angular fragments of trachytic lava, and other products of igneous ejections, interstratined with some deposits of clay, free from any intermixture of volcanic matter. 'l'hese clays might have re· "' Geol. Trans., vol. ii, part iii. p. 351. Seconcl Serks. 1' Scropc1 iuiil, ~ See the Jist of th~s~ !ihdls, Appendix II. Ch. X.] OUTLINE OF COUNTRY IIOW 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 submarine 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 count·ry 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 pr~sent height, we are prepared to find signs of the denudmg actiOn of the waves impressed upon the outward form of the island, especially if we conceive the upheaving force to have ~cted ~y successive ~ovements. Let us suppose the ~ow c~nt1guous I~land of Promda to be raised by degrees until It attams t~e he1~ht of Ischia, we should in that case expect the steep chffs winch now face Misenum to be carried upwards and to become precipices near the summit of the central mount~ i~. Su~h, perhaps, may have been the origin of those precipices wh1eh appear on the north and south sides of the ridcre which forms the summit of Epomeo in Ischia. The northe;n 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 ~he cliff, is such as the action of the sea, workin~ on soft matenals, might :easily have produced, undermininO' and removing a great portion of the mass · A 11 eap o f s hI' nO'1 e° which lies at the base of a steep declivity on the flanks 0 0 f Epohm eo, between the Cavo delle Neve and Panella, m ay once, per aps, have bee!1 a sea-beach, for it certainly could not have been brought to the spot by any existinO' torrents. 'rhere is no difficulty in conceiving th:t if a large tract of the ~e~. of the sea. near Ischia should now be gradua11y upheaved ~Jmg the continuance of volcanic agency' this newly-raised Jand mlght present a counterpart to the Phlegrman fields before de .. |