Earth science semester two volcanoes.
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28 terms
Terms | Definitions |
|---|---|
 Volcano. | A weak spot in the crust where magma comes to the surface. |
| Tephra. | Bits of rock dropped from the air in a volcanic explosion. |
| Lava. | When magma reaches the surface it is clasified as lava. |
| Magma. | Molten rock material under the surface of the earth. |
| Magma chamber. | A pocket beneath a volcano were magma Colects. |
| Pipe. | A long tube that carries magna from the magma chamber to the Earth's surface. |
| Vent. | An opening were molten rock and gas leave the volcano. |
| Crater. | A bowl shaped opening at the top of a volcanoes vent. |
| Caldera. | A huge hole left by the collapse of a volcanic mountain. |
| Convergent boundry. | A plate boundary where two plates move toward each other. |
| Island Arc. | A string of islands formed by volcanos along a deep ocean trench. |
| Divergent boundary. | A plate boundary were two plates move away from each other. |
| Hot spot. | An area where magma from deep within the mantle melts through crust above it. |
| Subduction. | The process by which ocean floor sinks beneath a deep ocean trench and back into the mantle. |
| Cindercone volcano. | A steep cone shaped hill or small mountain made of volcanic ash cinders and bombs piled up around a volcanoes open. |
| Composite volcano. | Tall coned shaped mountains were layers of lava alternate with layers of ash. |
| stratovolcano. | A composite volcano cone built up of interlayerd lava flows and pyroclastic materials. |
| Shield volcano. | A low flat gently sloping volcano made from basaltic lava/magma. |
| Active volcano. | A volcano that is eurupting or shows signs of future eurupting. |
| Viscosity. | A liquids resistance to flow. |
| Extinct volcano. | A volcano that has not erupted for thousands of years and probably will not erupt again. |
| Silica. | A material found in magma that is formed from the elements oxygen and silicon. |
| Granitic magma. | Magma rich in silica and low in magnesium and iron, light colored and low density. |
| Andesitic magma. | Type of magma with a medium amount of silica content. |
| Basaltic magma. | Silica Content: About 50% Gas Content: Least Viscosity: Least viscous. |
| Pahoehoe. | A hot, fast-moving type of lava that hardens to form smooth, ropelike coils. |
| Aa | A slow-moving type of lava that hardens to form rough chunks; cooler that pahoehoe. |
| Pyroclastic flow. | The expulsion of ash, cinders, bombs, and gases during an explosive volcanic eruption. |
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