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17 Cards in this Set
- Front
- Back
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lava
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when magma reaches the Earth's surface, it is called lava. When lava cools it becomes rock.
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Give 4 key facts about volcanoes.
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1. volcanoes are eruptions of lava and ash
2. volcanoes are cone-shaped mountains or hills 3. volcanoes happen at both destructive and constructive boundaries, but not conservative boundaries 4. Volcanoes can occur on the seafloor |
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How are volcanoes formed? (5 steps)
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1. magma rises in cracks in the Earth's surface
2. pressure builds up 3. plates move > pressure released, magma released, explodes to the surface 4.lava from eruption cools to rock 5. over time a volcano is formed |
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Name 4 parts of a volcano
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1. magma chamber
2. main vent 3. secondary vents 4. crater |
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magma chamber
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a collection of magma below the Earth, inside the volcano
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main vent
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the main outlet through which magma escapes
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secondary vents
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smaller outlets through which magma escapes
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crater
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formed when an eruption blows the top off the volcano
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name 3 types of volcano
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1. active (frequent eruptions
2. dormant (temporarily inactive) 3. extinct (never likely to erupt again |
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name 2 types of volcano shape
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shield
composite |
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shield volcanoes
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1. found at constructive boundaries
2. low gentle slopes 3. formed by eruptions of slow, runny lava 4. eruptions frequent + gentle |
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composite volcanoes
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1. made up of lava + ash
2. found at destructive boundaries 3. eruptions can be pyroclastic flow rather than just lava 4. pyroclastic flow - very fast very hot |
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pyroclastic flow
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made up of
hot steam ash rock dust |
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supervolcanoes
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1. eruptions 1,000x the material as volcanoes
2. form a depression called a caldera 3. ridge of higher land around it 4. infrequent eruptions (100's of thousands of years apart) |
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give 3 negative effects of volcanoes
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1. loss of life
2. loss of wildlife, vegetation 3. lahars can further destroy settlements and vegetation |
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give 3 positive effects of volcanoes
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1. create interesting landscapes > attract tourists
2. add nutrients improving agriculture 3. high levels heat + energy > geothermal power |
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lahars
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rain or melted snow mix with ash and mud from eruption creating fast flowing mud flows
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