Page:Great Neapolitan Earthquake of 1857 Vol 2.djvu/95

58 The ridge is four or five times as long east and west, as north and south. The long axis runs about 70° E. of north, and the general configuration may be seen from Diagram No. 301, in plan. Fig. 1, and in north and south section Fig. 2, and east and west section Fig. 3 (Sketches, Coll. Roy. Soc). The top, of the ridge occupied by the town, is nearly level, but beyond its verge, circumscribed in many places, by parts of the ancient towered walls. The flanks slope down rapidly, to the bosoms of the great basins below. Looking northward from the town, the basin spreads away for miles, with low, rounded, swelling, knolls and hills, some rising tolerably high, but all, like the ridge of Potenza itself, covered over deeply, with clay and diluvium. The highest summits visible are the ridges of the Serra della Fontana, to the N.W. ten miles away.

From the south side, a rolling mass of mountain and valley spreads away, abutting up much closer upon Potenza, to the west and south, and amongst which the Bosco de Cerrito and Monte Acuto rise high. To the S.E. we look up the straight little valley of the Vasento to Vignola; only about three miles away. No limestone is visible, except in the highest peaks: all is rounded clay, and beneath the town and everywhere around it, appears to be a vast variety of argillaceous rocks, passing continually into sandstones, and again alternated with the clays and slate beds. These are twisted in all directions, and do not, upon the whole, seem to have any determinate horizontal position. Beneath Potenza, there are obscure indications that the rock is argillaceous, and that the beds have their strike, something about the lengthway of the ridge, and dip towards the north and N.W. generally.