From the town the ruins of a mole, called Caligula's Bridge, run out into the sea (see [fig. 88], p. 509).[713] This mole, which is believed to be eighteen centuries old, consists of a number of piers and arches, thirteen of which are now standing, and two others appear to have been overthrown. Mr. Babbage found, on the sixth pier, perforations of lithodomi four feet above the level of the sea; and, near the termination of the mole on the last pier but one, marks of the same, ten feet above the level of the sea, together with great numbers of balani and flustra. The depth of the sea, at a very small distance from most of the piers, is from thirty to fifty feet.
a, Remains of Cicero's villa, N. side of Puzzuoli.[714]
b, Ancient cliff now inland.
c, Terrace (called La Starza) composed of recent submarine deposits.
d, Temple of Serapis.
Coast north of Puzzuoli.—If we then pass to the north of Puzzuoli, and examine the coast between that town and Monte Nuovo, we find a repetition of analogous phenomena. The sloping sides of Monte Barbaro slant down within a short distance of the coast, and terminate in an inland cliff of moderate elevation, to which the geologist perceives at once that the sea must, at some former period, have extended. Between this cliff and the sea is a low plain or terrace, called La Starza (c, [fig. 89]), corresponding to that before described on the southeast of the town; and as the sea encroaches rapidly, fresh sections of the strata may readily be obtained, of which the annexed is an example.
Section on the shore north of the town of Puzzuoli:—
| Ft. | In. | |
| 1. Vegetable soil | 1 | 0 |
| 2. Horizontal beds of pumice and scoriæ, with broken fragments of unrolled bricks, bones of animals, and marine shells | 1 | 6 |
| 3. Beds of lapilli, containing abundance of marine shells, principally Cardium rusticum, Donax trunculus, Lam., Ostrea edulis, Triton cutaceum, Lam., and Buccinum serratum, Brocchi, the beds varying in thickness from one to eighteen inches | 10 | 0 |
| 4. Argillaceous tuff, containing bricks and fragments of buildings not rounded by attrition. | 1 | 6 |