Some idea can be had of these three regions from a map of the Mediterranean shown in [Fig. 12]. The principal volcanoes are Vesuvius, Etna, Stromboli, and Vulcano, a mountain, by the way, that gave its name to all volcanic mountains. In this chapter we will describe the volcano of Vesuvius, the most active, though by no means the largest of the volcanoes of the Mediterranean.
But, before doing this, it will be well first to describe briefly the volcanic districts surrounding Vesuvius.
As shown in [Fig. 13], this district includes Vesuvius, Procida, and Ischia.
Fig. 12. The Mediterranean
Ischia is a small island measuring about five miles from east to west, and three miles from north to south. There were such terrific volcanic eruptions on this island long before the Christian Era, that several Greek colonies were forced to abandon it. A colony established long afterwards, about 380 b. c., by the king of Syracuse also had to depart. Strabo, the Grecian geographer (born about 63 b. c.), states that, according to tradition, terrific earthquakes occurred on the island a little before his time, and its principal mountain threw out large quantities of molten rock, which flowed into the sea. At the time of this eruption there were earthquake waves in the sea, the waters of which slowly receded, leaving large portions of the bottom uncovered, and rushing, afterwards, violently over the land, caused great destruction. It was during this disturbance, so Strabo asserts, that the island of Procida was formed by being violently torn from Ischia.
