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24 Cards in this Set
- Front
- Back
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Any fragment ejected during an eruption.
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tephra
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Smallest ejected material that is < .25mm.
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dust
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Tephra that is larger than dust, and that is < 2mm.
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ash
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Tephra that varies in size between 2-64mm, and that also means "little stone".
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lapilli
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Largest tephra that has angular edges. This large tephra can be thrown at great distances.
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volcanic block
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Lava that hardens in air as a round ball and that will flatten on impact.
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volcanic bomb
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Rapidly moving volcanic debris with hot rocks and poisenous gases.
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pyroclastic flow
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A stream of lava that is usually basaltic.
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lava flows
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Hardened lava that blocks a vent. It can cause pressure build-up.
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lava plug
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Tephra that is deposited at a volcano's base or around it's vent.
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alluvium
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A mud flow that usually results from snow melting fast during an eruption, mixing with tephra or pyroclastic flow.
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lahar
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An underground channel through which lava flows, leaving tunnels behind, once lava has exited.
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lava tube
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Flat section of land built up by layers of lava flows, often from fissures.
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lava plateau
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Where magma rises near the surface causing land to swell, but not to form a volcano.
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lava dome
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Lava flows resulting in smooth, ropey surfaces.
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pahoehoe
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Lava flow resulting in rough, jagged surfaces.
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aa
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Compacted dust and ash resulting in a sedimentar rock.
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tuff
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Water increases the chance of rocks melting and high water content=lower melting temperature.
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How water affects magama formation.
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With LOW pressure, the temperature decreases so these rocks will melt closer the surface.
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How pressure affects "wet rocks".
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With HIGH pressure, the temperature will increase so these rocks will melt and form deeper in the earth.
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How pressure affects "dry" rocks.
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How thick something is, depending on temperature and composition.
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Viscosity
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This lava has low viscosity, with 52% or less of silica due to rocks in upper mantle.
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Viscosity of Basaltic Lava.
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This lava has high viscosity, with 66% or higher of silica due to the mixing of silica and water-rich continental crust.
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Viscosity of Rhyolitic Lava.
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This lava has medium viscosity, with 52-66% of silica due to the melting of oceanic crust.
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Viscosity of Andesitic Lava.
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