Earth Science
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secure2455 on September 29, 2010
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41 terms
Terms | Definitions |
|---|---|
 aa flow | a type of lava flow that has a jagged blocky surface |
| batholith | A mass of rock formed when a large body of magma cools inside the crust |
| caldera | a large crater caused by the violent explosion of a volcano that collapses into a depression |
| cinder cone | a steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and bombs piled up around a volcano's opening |
| columnar joint | a pattern of cracks that from during cooling of molten rock to generate columns that are usually six sided |
| composite cone | a volcano composed of both lava flows and pyroclastic material |
| conduit | a pipe-like oopening through which magma moves toward Earth's surface. |
| continental volcanic arc | mountains formed by igneous activity associated with the subduction of oceanic lithosphere beneath a continent |
| crater | a bowl-shaped opening at the top of a volcano |
| decompression melting | Partial melting of hot mantle rock when it moves upward and the pressure is reduced to the extent that the melting point drops to the temperature of the body. |
| dike | a tabular-shaped intrusive igneous feature that cuts through the surrounding rock |
| eruption column | the towering cloud of ash debris etc. from a volcano |
| fissure | a long narrow depression in a surface, crevice; crack |
| fissure eruption | the eruption of magma out of a crack in the lithosphere, rather than from a single pipe or vent |
| flood basalt | Flows of basalt that come from fissures and cover big areas of land hundreds of meters thick |
| fumarole | a vent in a volcanic area from which fumes or gases escape |
| geothermal gradient | the gradual increase in temperature with depth in the crust |
| hot spot | an area where magma from deep within the mantle melts through the crust above it |
| intraplate volcanism | Volcanoes that are created within a plate and not on a plate boundary, normal mantle material asend, and these form when a plate moves over a hot spot |
| laccolith | when magma pushes up the earth's surface and cools forming a dome |
| lahar | an avalanche of volcanic water and mud down the slopes of a volcano |
| lava tube | a long tunnel formed by pahoehoe lava as it cools along the surface |
| mantle plume | A buoyant mass of hot rock rising through Earth's mantle. As it nears the surface of Earth, some of the plume melts and erupts at the surface forming a "hot spot." |
| pahoehoe flow | a lava flow with a smooth-to-ropey surface |
| parasitic cone | a volcanic cone that forms on the flank of a larger volcano. |
| partial melting | The process by which most igneous rocks melt. Since individual minerals have different melting points, most igneous rocks melt over a temperature range of a few hundred degrees. If the liquid is squeezed out after some melting has occurred, a melt with a higher silica content results. |
| pipe | a vertical conduit thru which magmatic materials have passed. |
| pluton | large mass of intrusive igneous rock believed to have solidified deep within the earth |
| pyroclastic flow | The expulsion of ash, cinders, bombs, and gases during an explosive volcanic eruption |
| pyroclastic materials | the volcanic rock ejected during an eruption including ash, bombs, and blocks |
| scoria cone | a rather small volcano built primarily of pyroclastics ejected from a single vent with hardened lava |
| shield volcano | A low, flat, gently sloping volcano built from many flows of fluid, low-viscosity basaltic lava |
| sill | a slab of volcanic rock formed when magma squeezes between layers of rock |
| stratovolcanoes | volcanoes from half-mafic, half-felsic eruptions (tall and steep - like Mt. Fuji/ Mt. St. Helens) |
| vent | a hole for the escape of gas or air |
| viscosity | a liquid's resistance to flow |
| volatiles | gaseous components of magma dissolved in the melt. They will readily vaporize at surface pressures |
| volcanic island arc | a chain of volcanic islands generally located a few hundred kilometers from a trench where there is active subduction of one oceanic plate beneath another |
| volcanic rock | Formed when magma erupted, cooled, and solidified within a kilometer or less of the earth's surface |
| volcano | a fissure in the earth's crust (or in the surface of some other planet) through which molten lava and gases erupt |
| island arc | A string of islands formed by the volcanoes along a deep ocean trench |
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