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Show CHAPl'ER X. Tertiary formations of Cllompania-Comparison of the recor4ed ~hauges i~ this region with those commemorated hy geolo~ical monuments-~tffcr.c~ces m the composition of Somma and Vesuvius-D1kes of Somma, thClr ongm-Cause of the parallelism of their opposite sides-·Why coarser grained in the centreMinor cones of the Phlegrrean Fields-Age of the volcanic and associated rocks of Campania-Organic remains-External configuration of the country, llow produced-No signs of diluvial waves-Marine Newer Pliocene strata visible only in countries of earthquakes-Illustrations from Chili-PeruParallel roads of Coquimbo-West-Indian archipelago- Honduras- East. Indian archipelago-Red Sea. TERTIARY FORMATIONS OF CAMPANIA. Comparison of recorded changes with those commemorated by geological rnonuments.-IN the first volume we traced the various changes which the volcanic region of Naples is known to have unJergone during the last 2000 years, and, imperfect as are our historical records, the aggregate effect of igneous and aqueous agency, during that period, was shown to be far from insignificant. The rise of the modern cone of Vesuvius, since the year 79, was the most memorable event during those twenty centuries ; but in addition to this remarkable phenomenon, we enumerated the production of several new minor cones in Ischia, and of the Monte N uovo, in the year 1538. 'V e described the flowing of lava-currents upon the land and along the bottom of the sea, the showering down of volcanic sand, pumice, and scm·ire, in such abunclance that whole cities were lmried,-the filling up or shoaling of certain tracts of the sea, and the transportation· of tufaceous sediment by rivers and land-floods. We also explained the evidence in proof of a permanent alteration of the relative levels of the land and sea in severallocalitie~, and of the same tract having, near Puz. zuoli, been alternately upheaved, and depressed, to the amount of more than 20 feet. In connexion with these convulsions, Oh.X.] TERTIARY FORMATIONS OF CAMPANIA. 119 we pointed out that, on the shores of the Bay of Baire, there are recent tufaceous strata £lied with fabricated articles, mingled with tnarine shells. It was also shown that the sea has been making gradual advances upon the coast, not only sweep· ing away the soft tuffs of the Bay of Baire, but excavating precipitous cliffs, where the hard Ischian and Vesuvian lavas have flowed down into the deep. These events, we shall be told, although interesting, are the results of operations on a very inferior scale to those indicated by geological monuments. When we examine this same region, it will be said, we £nd that the ancient cone of Vesuvius, called Somma, is larger than the modern cone, and is intersected by a greater number of dikes,-the hills of unknown antiquity, such as Astroni, the Solfatara, and Monte Barbaro, formed by separate eruptions, in different parts of the Phle· grrean fields, far outnumber those of similar origin, which are recorded to have been thrown up within the historical era. In place of modern tuffs of slight thickness, and single flows of lava, we find, amongst the older formations, hills from 500 to more than 2000 feet in height, composed of an immense series of tufaceous strata, alternating with distinct lava-currents. We have evidence that in the lapse of past ages, districts, not mere) y a few miles square, were upraised to the height of 20 or 30 feet above their former level, but extensive and mountainous countries were uplifted to an elevation of more than 1000 feet, and at some points more than 2000 feet above the level of the sea. These and similar objections are made by those who com· pare the modern ea:ects of igneous and aqueous causes, not with a part but with the whole results of the same agency in antecedent ages. Thus viewed in the aggregate, the leading geological features of each district must always appear to be on a colossal scale, just as a large edifice of striking architec· tural beauty seems an effort of superhuman power, until we reflect on the innumerable minute parts of which it is composed. A mountain mass, so long as the imagination is occu • |