There are also numerous instances in Sicily of terraces of denudation. One of these occurs on the east coast to the north of Syracuse, and the same is resumed to the south beyond the town of Noto, where it may be traced forming a continuous and lofty precipice, a b, [fig. 94.], facing towards the sea, and constituting the abrupt termination of a calcareous formation, which extends in horizontal strata far inland. This precipice varies in height from 500 to 700 feet, and between its base and the sea is an inferior platform, c b, consisting of similar white limestone. All the beds dip towards the sea, but are usually inclined at a very slight angle: they are seen to extend uninterruptedly from the base of the escarpment into the platform, showing distinctly that the lofty cliff was not produced by a fault or vertical shift of the beds, but by the removal of a considerable mass of rock. Hence we may conclude that the sea, which is now undermining the cliffs of the Sicilian coast, reached at some former period the base of the precipice a b, at which time the surface of the terrace c b must have been covered by the Mediterranean. There was a pause, therefore, in the upward movement, when the waves of the sea had time to carve out the platform c b; but there may have been many other stationary periods of minor duration. Suppose, for example, that a series of escarpments e, f, g, h, once existed, and that the sea, during a long interval free from subterranean movements, advances along the line c b, all preceding cliffs must have been swept away one after the other, and reduced to the single precipice a b.
Fig. 94.
Fig. 95.
Valley called Gozzo degli Martiri, below Melilli, Val di Noto.
That such a series of smaller cliffs, as those represented at e, f, g, h, [fig. 94.], did really once exist at intermediate heights in place of the single precipice a b, is rendered highly probable by the fact, that in certain bays and inland valleys opening towards the east coast of Sicily, and not far from the section given in [fig. 94.], the solid limestone is shaped out into a great succession of ledges, separated from each other by small vertical cliffs. These are sometimes so numerous, one above the other, that where there is a bend at the head of a valley, they produce an effect singularly resembling the seats of a Roman amphitheatre. A good example of this configuration occurs near the town of Melilli, as seen in the annexed view ([fig. 95.]). In the south of the island, near Spaccaforno, Scicli, and Modica, precipitous rocks of white limestone, ascending to the height of 500 feet, have been carved out into similar forms.