Page:Great Neapolitan Earthquake of 1857.djvu/225

Rh some nearly supercretaceous deposits; yet in the Vulture district, where the order of position between the neptunian and volcanic rocks is in several places very easily seen, I have never found the igneous rocks, lying beneath any of the various rocks of the third series; so that we may maintain that the emergence from the sea of the sub-Apennine deposits, took place previously to the first fires of the Vulture. There are also in this same volcanic region frequent and extensive fresh-water formations; but, contrary to what has been observed of the marine deposits, they lie invariably above the rocks of igneous origin, and closely resemble the sedimentary deposits which are in process of deposition in our own days, under very restricted conditions, in like places abounding in water. Pursuing a chronological order, we shall briefly speak of these when we have concluded our remarks on the volcanoes of the Vulture district.

The rocks of which the oldest formations of aqueous origin in the kingdom of Naples are composed, are almost exclusively calcareous, and include many varieties, which seldom constitute an essential difference. The most frequent of these varieties is the compact, with conchoidal fracture, of a white, or clear smoke-gray colour. Another variety, somewhat less abundant, has a granular texture more or less distinct, in which oftener than in the preceding, small cavities lined with crystals of the same substance are found. Passing over several varieties of minor importance, we shall enumerate four others. The first has a brecciated structure, enlivened by gay colours, and is capable of receiving a beautiful polish. Of this we have magnificent specimens in the marbles of Vitulano, and Mondragone, in Terra di Lavoro. The second is of a beautiful white colour, and pulverizes easily at a touch. It may be seen between Piedimonte di Alife and S. Potito at the foot of Matese in the district of Melfi, after the 77th milestone on the road from Valva, and in many other places. The third variety, not very different from the preceding in appearance, is that which geologists denominate chalk, and which, so far as we know, is only found at Monte