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Table of Contents


1........................................ What is a volcano?
2.........................................Plate Tectonics
3........................................ Volcanic features
4........................................ Shield volcanoes
5........................................ Cinder cones
6.........................................Stratovolcanoes (composite volcano)
7.........................................Super volcanoes
8.........................................Submarine volcanoes
9.........................................Subglacial volcanoes
10...................................... Lava composition


Page 1
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What is a volcano?


When pressure from the molten rock beneath the earth's surface becomes too great, the rock, usually accompanied by lava or gases, escapes through a fissure or vent in the crust of the earth. "Volcano" is the term given to both the vent and the conical mountain left by the overflow of the erupted lava, rock and ash.

More than 80% of the earth's surface comes from volcanoes. Innumerable volcanic eruptions formed the sea floor and some mountains; gaseous emissions from volcanoes formed the earth's atmosphere.

The name "volcano" is said to have come from Vulcano, a volcanic island in the Aeolian Islands of Italy. The name Vulcano originates from Vulcan, a god of fire in Roman mythology. The study of volcanoes is called volcanology (sometimes spelled vulcanology).

There are more than 500 active volcanoes in the world. More than half of these volcanoes are part of the "Ring of Fire," a region that encircles the Pacific Ocean. The world's largest active volcano is Mauna Loa in Hawaii. Taller than Mount Everest, Mauna Loa's summit rises 56,000 ft (17,000 m) from its base below sea level.