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28 Cards in this Set
- Front
- Back
Parts of a volcano
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crater- bowl shaped area around central opening, lava-molten rock that flows from the vent above earth's surface,magma- molten rock below the earths surface, pipe-long tube through which magma moves, vent-the opening which molten rock and gas leave the volcano
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Why does magma rise
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b/c liquid magma is less dense than the surronding solid material
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What factors determine if a volcano will erupt?
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amount of gas dissolved in the magma, viscosity (resistance of magma), Magma temp (hotter it is the more fluid it is), silica content (the more the thicker it is)
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3 Stages of a volcano
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active-live
dormant- sleeping expected to become active in the future Extinct- dead, not erupted for thousands of years |
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3 types of volcano
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sheild, cinder cone, and composite
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Sheild Volcano
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thin layers of lava pour out gradually and build up a wide, gently sloping mt Ex:Mauna Loa
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Cinder Cone
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produce ash, cinders, and bombs, steep cone shpaed hill Ex:Paricutin
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Composite Volcano
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tall mountains, alternating ash and cinder and bombs
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What is an earthquake?
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the vibration of Earth produced by the rapid release of energy.
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Focus
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the source where enery radiates in all directions
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What are Earthquakes associated with?
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faults, explained by plate tectonics
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Body waves
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primary waves, secondary waves
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p-waves
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push-pull waves they can travel through all mediums, they arrive first
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s-waves
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right angle waves, they can travel through solids, they arrive second
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Surface Wave
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like ocean swells, they have an up and down motion and a side-to-side motion, produce the most damage, they arrive last
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epicenter
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the location on the surface directly above the focus
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2 ways to measure a earthquake
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Mercalli Intensity Scale, Richter Scale
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Tsunami
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seismic sea waves, produced by an earthquake
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law of superposition
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in a undeformed sequence of sedimentary rocks the oldest rock is on the bottom, and the youngest rock is on top
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Principle of Original Horizontality
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the layers of sediment are generally deposited in a horizontal position. if the layers are flat they have not been disturbed, and have their original horizontality
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Prinicple of Cross-Cutting relationships
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when a fault cuts through or a magma intrudes and crystallizes we can assume that the fault or the intrusion is younger than the rocks it intruded into
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unconformities
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gap in the geogical record, disconformity-erosional
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What are fossils?
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the remains or traces of prehistoric life, important time indicators
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Principle of Fossil Succession
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fossil organisms suceed one another in a definite and determinable order, and therefore any time period can be recognized by its fossil content
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What is a fossil index
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widespread geographically and are limited to a short span of geologic time
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radiometric dating
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absolute dating
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Precambrian
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mostly algee and microfossils
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3 Eras
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paleozoic-mostly invertebrates, mesozoic- mostly dinosaurs, cenozoic- mostly mammals
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