above the water, and in four years had grown into a large volcanic cone, the summit of which was 3,000 feet above sea-level. [Illustration: Ideal Landscape of the Carboniferous Period Showing Lepidodendra and other Giant Ferns and Mosses whose remains are found in the Coal-Measures] Unfortunately, the phenomena of recent volcanic eruptions under the sea are for the most part inaccessible. Here and there, as in the Bay of Naples, at Etna, among the islands of the Greek Archipelago, and at Tahiti, elevation of the sea-bed has taken place, and brought to the surface beds of tuff or of lava, which have consolidated under water. Both Vesuvius and Etna began their career as submarine volcanoes. The Islands of Santorin and Therasia form the unsubmerged portions of a great crater-rim rising round a crater which descends 1,278 feet below sea-level. Confining attention to vents now active, of which the total number may be about 300, the chief facts regarding their distribution over the globe may be thus summarized. (1) Volcanoes occur along the margins of the ocean-basins, particularly along lines of dominant mountain ranges, which either form part of the mainland of the continents or extend as adjacent lines of islands. The vast hollow of the Pacific is girdled with a wide ring of volcanic foci. (2) Volcanoes rise, as a striking feature, from the submarine ridges that traverse the ocean basins. All the oceanic islands are either volcanic or formed of coral, and the scattered coral-islands have in all likelihood been built upon the tops of submarine volcanic cones. (3) Volcanoes are situated not far from the sea. The only exceptions to this rule are certain vents in Manchuria and in the tract lying between Tibet and Siberia; but of the actual nature of these vents very little is yet known. (4) The dominant arrangement of volcanoes is in series along subterranean lines of weakness, as in the chain of the Andes, the Aleutian Islands, and the Malay Archipelago. A remarkable zone of volcanic vents girdles the globe from Central America eastward by the Azores and Canary Islands to the Mediterranean, thence to the Red Sea, and through the chains of islands from the south of Asia to New Zealand and the heart of the Pacific. (5) On a smaller scale the linear arrangement gives place to one in groups, as in Italy, Iceland, and the volcanic islands of the great oceans.