XXII. — On the Volcanic District of Naples, 

 By G. POULETT SCROPE, Esq., F.G.S. F.R.S. &c. 



[Read March 2nd, 1827.] 



IHE volcanic formations of the vicinity of Naples, being for the most part 

 easily accessible from that much-frequented capital, have been described in 

 considerable detail by many geologists, particularly in the works of Menard 

 de la Groye, Necker de Saussure, Brieslak, and the lately published volume of 

 Dr. Daubeny. I intend therefore in the following memoir, to avoid as much 

 as possible the repetition of facts already made public through these well- 

 known channels, and to confine myself to such observations as I do not re- 

 member to have seen in print, and such general views of the subject as our 

 continually increasing knowledge of the mode of production of similar forma- 

 tions may appear to warrant. 



I consider the volcanic district of Naples to include not only Somma, Vesu- 

 vius, the coast of Sorrento, and the immediate environs of Naples, Pozzuoli, 

 and Cuma ; but also the islands of Procida and Ischia, with which they are as 

 closely connected in composition as in geographical situation. This linear 

 group, which ranges N.E.^ — S.W., is terminated at either extremity by the 

 two principal volcanic mountains of Ischia and Vesuvius. The latter, as I 

 have mentioned in a previous memoir, seems to be in communication with 

 the group of Albano and Rome, through the intervention of the Rocca 

 Monfina and other minor vents of volcanic matter scattered along that remark- 

 able longitudinal valley which divides the limestone range of the Sabine hills 

 from the principal trunk of the Apennines. Another chain of volcanic pro- 

 ducts seems to take off also from Ischia towards the Ponza group, through 

 the islands of Ventotiene and San Stefano, maintaining a parallel direction 

 with that first mentioned, and indeed with the general range of the escarp- 

 ment of the elevated Apennine strata, at the foot of which these explosions 

 have found an issue. 



It is certainly a remarkable confirmation of the opinion elsewhere expressed, 

 as to the general parallelism of lines of volcanic eruption to the nearest linear 



VOL. II. — SECOND SERIES. 2 Y 



