Observations on Mount Vesuvius, Mount Etna, and Other Volcanos; In a Series of Letters, Addressed to the Royal Society (Paperback)

Excerpt: ...had been evidently formed by subterraneous fire. The high grounds, which extend from Castel-a-Mare, to the point of Minerva towards the island of Caprea, and from the promontory that divides the bay of Naples from that of Salerno, are of lime-stone. The plain of Sorrento, that is bounded by these high grounds, beginning at the village of Vico, and ending at that of Massa, is wholly composed of the same sort of tufa as that about Naples, except that the cinders or pumice stones intermixed in it are larger than in the Naples tufa. I conceive then that there has been an explosion in this spot from the bottom of the sea. This plain, as I have remarked to be the case with all soils produced by subterraneous fire, is extremely fertile; whilst the ground about it, being of another nature, is not so. The island of Caprea does not shew any signs of having Pg 116 been formed by subterraneous fire; but is of the same nature as the high grounds last mentioned, from which it has been probably detached by earthquakes, or the violence of the waves. Rovigliano, an island, or rather a rock, in the bay of Castel-a-Mare, is likewise of lime-stone, and seems to have belonged to the original mountains in its neighbourhood: in some of these mountains there are also petrified fish and fossil shells, which I never have found in the mountains which I suppose to have been formed by explosion 34 . You have now, Sir, before you the nature of the soil, from Caprea to Naples. The soil on which this great metropolis stands has been evidently produced by explosions, Pg 117 some of which seem to have been upon the very spot on which this city is built; all the high grounds round Naples, Pausilipo, Puzzole, Baia, Misenum, the islands of Procita and Ischia, appear to have been raised by explosion. You can trace still in many of these heights the conical shape that was naturally given them at first, and even the craters out of which the matter issued, though to be sure others of...