Page:Great Neapolitan Earthquake of 1857.djvu/502

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Great Rock Fractures

position. On examining the hard ferruginous beds, of thick, blue grey, flinty limestone at A (plan and section) I found, with some surprise, that they exhibited at the exposed south face, for about 200 feet in length, numerous large fresh-made fractures, running nearly vertically, right through the whole of the strata, up to the dense but soft clay beds to the north. Further to the east the beds are covered up by clays on both sides, and the ends of the strata alone visible. These were much obscured by the torrents of creamy clays that the rain was washing over them; but yet I was enabled to trace similar fractures across the tops of the beds, and extending vertically downwards through them, for a distance of about 250 yards eastward. To the westward, the torrent runs through these indurated beds, and cuts off those to the west of it from any contact visible with the clays.

At the base of the vertical beds below A, in the bed of the torrent, great masses of freshly-fractured and fallen rock were lying, and in several of the fractures, the widest of which was open, on an average, about an inch, on the south face, of the nearly vertical beds, I found fresh fractured splintering fragments in various spots. These had dropped down a few inches only, and I could replace and fit them into the spots from which they had fallen in the jaws of the fissures. There could be no mistake as to the freshness of the fractures, for all the old and weathered portions of the rock, were a deep iron rust, in colour; but the fresh-broken surfaces, a bright blue grey, of a deep tint. Many large fragments from the tops of the upcrop of the beds, had also been detached at weathered fissures, from the south face, and lay thrown into the bottom of the torrent.