These are three in number Ponza, Palmarola and Zannone; while Ventotene (also of volcanic formation) is about midway between Ponza and Ischia.
The group is of volcanic origin, and includes Palmarola (anc. Palmaria), Zannone (Sinonia), Ventotene (Pandateria, pop. in 1901, 1986) and San Stefano.
Remnants of a former inner zone of more ancient rocks may be seen in the Apuan Alps, in the islands off the Tuscan coast, in the Catena Metallifera, Cape Circeo and the island of Zannone, as well as in the Calabrian peninsula.
The word usage examples above have been gathered from various sources to reflect current and historial usage. They do not represent the opinions of YourDictionary.com.