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Chapter 18
Term | Definition |
---|---|
Volcanism | describes all the processes associated with the discharge of magma, hot water, and steam |
Hot spot | unusually hot area in earth's mantle where high-temperature plumes of mantle material rise toward the surface |
Flood basalt | huge amounts of lava that erupt from fissures |
Fissure | process in which heavy atomic nuclei split into smaller, lighter atomic nuclei |
Conduit | a tubelike structure that allows lava to reach the surface |
Vent | opening in Earth's crust through which lava erupts and flows out onto the surface |
Crater | bowl-shaped depression that forms around the central vent at the summit of a volcano |
Caldera | larger crater, up to 50 km in diameter, that can form when the summit or side of a volcano collapse into the magma chamber during or after an eruption |
Shield volcano | broad volcano with gently sloping sides built by nonexplosive eruptions of basaltic lava that accumulates in layers |
Cinder cone | steep-sides, generally small volcano that is built by the accumulation of tephra around the vent |
Composite volcano | generally cone-shaped with concave slopes; built by violent eruptions of volcanic fragments and lava the accumulate in alternating layers |