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Page:Great Neapolitan Earthquake of 1857.djvu/234

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184
PRIOR TO VOLCANIC ACTION.

arrangement of strata is invariable for upwards of a mile. And to this fact surely Fonseca alludes, when he says that between Rionero and Barili the limestone strata are inclined almost at right angles to the declivity of the mountain. (Fonseca, 'Geognostic Observations on the Vulture.') Along a brook which runs near Barili, from the north-west side, the same strata of limestone and marl on the right bank are elevated towards the west 44 degrees, and on the left bank, towards the north, 31 degrees; and, one being almost opposite the other, their displacement cannot be referred to the action of the Vulture. In a valley situated to the north of Rapolla, the waters which run through it pass over limestone strata; and in one place where these are very apparent we have found them elevated 55 degrees towards the north-east, not to mention some which are even nearer to the vertical position. Lastly, omitting other facts of a similar nature which are less conspicuous, along the little river which runs round the hill of Melfi in the north-west side, some strata of grey argil are seen, which have the same inclination as the hill; and in the west side, not very distant from the bridge, commonly called Gaetaniello, there are some strata of red marl, containing fucoids, inclined 70 degrees towards the north-east. Their elevation cannot be attributed to the principal volcanoes of the Vulture; nor does it agree with the centre of action of the volcano of Melfi, as then they would have been inclined to the east. From these facts it is natural to conclude that the displacements observable in the neptunian rocks of the volcanic region of Vulture were not occasioned by the same forces which gave rise to the volcanoes, but rather that they occurred previously to their eruptions. This opinion is strengthened by the fact, that they present the same appearances as have been observed in other places, where the distance from the Vulture and the particular manner of dislocation prove that the eruptive volcanic force could not have occasioned such displacements. We shall select, from many instances which we might quote, that of the lofty eminence which we recently mentioned, on which the city of Monteverde is built. It lies to the north-west, distant in a direct line little more than four miles from the lakes of Monticchio. It is chiefly composed of large strata of Macigno, some of which are upwards of