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Show 128 NEWER rLIOCENE PERIOD. [Ch.X. scribed. Masses of alternating lava and tuff, the pt'Oducts of su b marm· e erup t'w ns, might on their emer.g ence become hills and islands; the level intervening plains m1ght afterwards ap-pear, covere d partly by the ashes drifted and deposited by water, an d Partly by those which would fall after the laying dry of the tract. The last features imparte~ to t.he physical geography would be derived from such eruptwns m the open air as those of Monte N uovo and the minor cones of Ischia. No signs of diluvial waves.-Such a conversion of a large tract of sea into land might possibly take place while the sur. face of the contiguous country underwent but slight modification. No great wave was caused by the permanent rise of the coast neat· Puzzuoli in the year 1538, because the upheaving operation appears to have been effected by a long succession of minor shocks*· A series of such movements, therefore, might produce an island like Ischia without throwing a diluvial rush . of waters upon low parts of the neighbouring continent. The advocates of paroxysmal elevations may, perhaps, contend that the rise of Ischia must have been anterior to the birth of all the cones of loose scorire scattered over the Phlegrrean Fields, for, according to them, the sudden rise of marine strata causes inundations which devastate adjoining continents. But the absence of any signs of such floods in the volcanic region of Campania does not appear to us to warrant the conclusion, either that Ischia was raised previously to the production of the volcanic cones, or that it may not have been rising dul'ing the whole period of their formation. We learn from the study of the mutations now in progress, that one part of the earth's surface may, for an indetlnite period, be the scene of continued change, while another, in the immediate vicinity, remains stationary. ·vve need go no farther than our own country to illustrate this principle; for, reasoning ft'Om what has taken place in the last ten centuries, we must anticipate that in the course of the next 4000 or 5000 years, a long strip of land, skirting the line of our eastern "' Sec vol. i, p. 457, first edition; p. 527, second edition. Ch.X.] MARINE NEWER PLIOCENE STRATA. 129 coast, will be devoured by the ocean, while part of the interior immediate]~ adjacent, will remain at rest and entirely undis~ turbed. 'I he analogy holds true in regions where the volcanic fires are at work, for part of the Philosopher's Tower on Etna has stood for the last 2000 years, at the height of more than 9000 feet above the sea, between the foot of the highest cone and ~he edge of the precipice which overhangs the Val del Bove, whilst large tracts of the surrounding district have been the scenes of tremendous convulsions. The great cone above has more than once been blown into the a. i'r , and agam· re-newed; the earth has sunk down in the neighbouring Cis-terna*; the cones of 1811 and 1819 have started up, on the ledge of rock below, pouring out of their craters two mighty streams of lava ; the watery deluge of 1755 has rushed down from the steep desert region, into the Val del Bove, rolling along vast heaps of rocky fragments towards the sea. fissures several miles in length, have opened on the flanks ~f Et ~ c·it i·e s ~n d '11 na' VI ages have been shattered by partial earthquakes, or buried under lava and ashes ;-yet the tower has stood as if placed on the most perilous point in Europe to commemorat ~ he sta.b T ' e I 1ty of one part of the earth's surface, while others in Immediate proximity have been subject to most wonderful and terrific vicissitudes. Marine Newer Pliocene strata only visible in count-ries of earlhquakes.-In concluding what we have to say of the marine and. volcanic .f orma.t ions of the newer Pli'ocene perw. d , we may n~tiCe the highly Interesting fact, that the marine strata of this er~ have hitherto been found at great elevations in those count_nes ~nly where violent earthquakes have occurred during t~e histor~c~l ages. We do not deny that some partial deposits _contammg recent marine shells have been discovered at considerable height in several maritime countries in Europe an~ else~ here, far from the existing theatres of volcanic action . but ;:~:~~ed d~posits of great extent and thickness, and replete 'with species, have only been observed to enter largely into the Vor .. III. * See nbove, p. 96. K |