Page:Great Neapolitan Earthquake of 1857.djvu/211

Rh ribs of Southern Italy; but our notions thus limited, convey no true idea of the physical features of the country. These ridges determine, the great forms and directions of the water-sheds, but by no means those of the vast tract of subordinate mountain ranges and culminations, by which these axial chains are surrounded and buttressed.

From the Tronto, to Gargano, the lateral mountains tend on the whole, to stretch parallel to the lines of the rivers, which fall with north-eastern courses into the Adriatic; and hence, the lines of mountain and valley, are generally transverse to the axial chain on this side.

On the opposite side, between the great axial chain and the transverse axis, from Naples to Monte Acuto, the great rivers, such as the Carigliano and the Volturno, take in tributaries from every point of the compass, and indicate, the extreme irregularity that prevails, in the alignment of the secondary ridges. This is also, to a less extent, true of the great trapezoidal area, between Salerno and Monte Acuto on the north, the gulfs of Salerno and Policastro on the west and south, and the southern continuation of the axial chain from Monte Acuto on the east. The southern branches, however, of the largest river within this boundary, the Salaris or Sole, have a nearly south to north course. Eastward of the axial chain of Monte Acuto, and over the whole province of Basilicata, the rivers all run, nearly parallel to each other, and in a direction almost exactly from N.W. to S. E. into the Gulf of Tarauto; but the directions of the secondary ridges are, on the whole, distinctly transverse to the river courses, which make their way through breaks or depressions, or wind round the teminals of the short and abrupt ridges. So that on the whole the