Page:Great Neapolitan Earthquake of 1857.djvu/288

Rh sedges and the distant and dismal howl of some goatherd's dog.

The formation of this tufa seems to indicate the upheaval of the great plain at a recent geological period. The lime has no doubt come, from the ground-up, and dissolved limestone, of the cretaceous formations, that constitute the lower mountain range, between the great mountain masses, of Apennine limestone and the sea. The latter occasionally comes forward in grand developments as at the Tusciano (Fig. 123), where the ranges under Monte Polveracchio show beds of vast extent and thickness, with a nearly horizontal strike parallel with the coast, and a noble sweeping curve, dipping steeply inland (about 30°) towards the N.N.E. Far beyond are high and jagged peaks, and a lofty sierra, thinly covered with a hoary head of snow, bounds the horizon, and glitters against the cold grey sky. Some twelve miles further south, the Salaris crosses the plain in a deep channel with heavy slob banks in the diluvium, about 270 feet wide, and with a rapid current, and turbid mud-stained water, of about 20 feet in depth. It drains a large area, in a course of more than a hundred miles, and the quantity of calcareous matter, both in solution by carbonic acid, and in suspension as mud, that it constantly brings into the sea, must be even now producing very sensible effects upon the coast, the dissolved lime forming the cement, that rapidly agglomerates and hardens the calcareous mud into stone. This process seems also to be that, upon which the formation of the calcareous breccias found in such vast masses in the Apennines, has depended.

Looking eastward towards, the valley through which the