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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 erupted from fissures. |
fissure | are long cracks in Earth. |
conduit | a tube-like 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 the 50 km in diameter, that can form when the summit or side of a volcano collapses into the magma chamber during or after an eruption. |
shield valcano | broad volcano with gently sloping sides built by nonexplosive eruptions of basaltic lava that accumulates in layers. |
cinder cone | steep-sided, generally small volcano that is build by the accumulation of tephra around the vent. |
composite valcano | generally cone-shaped with concave slopes; built by violent eruptions of volcanic fragments and lava that accumulate in alternating layers. |