Ground plan of the coast of the Bay of Baiæ, in the environs of Puzzuoli

Temple of Jupiter Serapis.—This celebrated monument of antiquity, a representation of which is given in the frontispiece,[711] affords in itself alone, unequivocal evidence that the relative level of land and sea has changed twice at Puzzuoli since the Christian era; and each movement, both of elevation and subsidence, has exceeded twenty feet. Before examining these proofs, I may observe, that a geological examination of the coast of Baiæ, both on the north and south of Puzzuoli, establishes, in the most satisfactory manner, an elevation, at no remote period, of more than twenty feet, and, at one point, of more than thirty feet; and the evidence of this change would have been complete, if even the temple had, to this day, remained undiscovered.

Coast south of Puzzuoli.—If we coast along the shore from Naples to Puzzuoli, we find, on approaching the latter place, that the lofty and precipitous cliffs of indurated tuff, resembling that of which Naples is built, retire slightly from the sea; and that a low level tract of fertile land, of a very different aspect, intervenes between the present sea-beach and what was evidently the ancient line of coast.

The inland cliff may be seen opposite the small island of Nisida, about two miles and a half southeast of Puzzuoli (see Map, [fig. 40], p. 361), where, at the height of thirty-two feet above the level of the sea, Mr. Babbage observed an ancient mark, such as might have been worn by the waves; and, upon farther examination, discovered that, along that line, the face of the perpendicular rock, consisting of very hard tuff, was covered with barnacles (Balanus sulcatus, Lamk.), and drilled by boring testacea. Some of the hollows of the lithodomi contained the shells; Fig. 87.

a, Antiquities on hill S. E. of Puzzuoli
(see ground plan, [fig. 86]).
b, Ancient cliff now inland.
c, Terrace composed of recent
submarine deposit. while others were filled with the valves of a species of Area.[712] Nearer to Puzzuoli, the inland cliff is eighty feet high, and as perpendicular as if it was still undermined by the waves. At its base, a new deposit, constituting the fertile tract above alluded to, attains a height of about twenty feet above the sea; and, since it is composed of regular sedimentary deposits, containing marine shells, its position proves that, subsequently to its formation, there has been a change of more than twenty feet in the relative level of land and sea.

The sea encroaches on these new incoherent strata; and as the soil is valuable, a wall has been built for its protection; but when I visited the spot in 1828, the waves had swept away part of this rampart, and exposed to view a regular series of strata of tuff, more or less argillaceous, alternating with beds of pumice and lapilli, and containing great abundance of marine shells, of species now common on this coast, and amongst them Cardium rusticum, Ostrea edulis, Donax trunculus, Lamk., and others. The strata vary from about a foot to a foot and a half in thickness, and one of them contains abundantly remains of works of art, tiles, squares of mosaic pavement of different colors, and small sculptured ornaments, perfectly uninjured. Intermixed with these I collected some teeth of the pig and ox. These fragments of building occur below as well as above strata containing marine shells. Puzzuoli itself stands chiefly on a promontory of the older tufaceous formation, which cuts off the new deposit, although I detected a small patch of the latter in a garden under the town.

Fig. 88.
VIEW OF BAY OF BAIÆ.

1. Puzzuoli.2. Temple of Serapis.3. Caligula's Bridge.4. Monte Barbaro.5. Monte Nuovo.
6. Baths of Nero.7. Baiæ.8. Castle of Baiæ.9. Bauli.10. Cape Misenum.
11. Mount Epomeo in Ischia.12. South Part of Ischia.