earth science topic 12 vocabulary
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asthenosphere
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The solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it
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continental crust
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The portion of the earth's crust that primarily contains granite, is less dense than oceanic crust, and is 20-50 km thick
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convergent plate boundary
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the boundary between two colliding plates; often associated with mountains, ocean trenches and volcanic arcs.
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crust
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the outermost portion of the lithosphere
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divergent plate boundary
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the boundary between two plates that are spreading apart at mid - ocean ridge or continental rift zone.
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earthquake
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a natural, rapid shaking of the lithosphere caused when rocks are displaced due to the released energy in stored rocks.
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epicenter
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the place on the earth's surface lying directly above the focus, or the origin of an earthquake.
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faulted
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rock layers that are offset or displaced along a type of crack called a fault.
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folded
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the bends in layered rock due to movement in the lithosphere; a type of deformed rock.
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hotspot
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major region of volcanic activity that are usually in the interior of plates away from plate boundaries.
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inner core
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the innermost zone of earth's core, which is thought to be composed of iron and nickel in a solid state.
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island arc
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a curved series of volcanoes and volcanic island that can stretch hundreds of miles; form at subduction zones where plates converge and magma rises to form volcanoes.
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lithosphere
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the whole crust and the uppermost portion of the mantle.
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lithospheric plate
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section of the lithosphere that moves around earth's solid surface.
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mantle
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the mostly solid part of earth between the crust and the outer core.
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mid - ocean ridge
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a mountain range at the bottom of the ocean, composed mostly of volcanoes and lava flows.
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moho
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the interface, or boundary zone, between earth's crust and mantle; short for Mohorovicic discontinuity.
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oceanic crust
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the portion of earth's crust that is usually below the oceans and not associated with continental areas; thinner and higher in density than continental crust and basaltic rather than granitic in composition.
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ocean trench
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the long, steep and narrow depression produced by the bending down of subducting plates, which warps the crust.
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original horizontality
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a concept that states that sedimentary rocks and some extrusive igneous rocks form in horizontal layers parallel to earth's surface.
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outer core
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the zone of earth between the mantle and the inner core; composed of iron and nickel.
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plate
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section of the lithosphere that moves around earth's solid surface.
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plate tectonic theory
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states that earth's lithosphere is divided into sections called plates that can move up and down or sideways on the plastic part of the upper mantle.
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P - waves
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the waves in earthquakes that travel through earth's interior and cause particles through which they travel to vibrate in the direction the waves are moving.
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S - waves
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earthquake waves that move through earth's interior and cause the particles through which they travel to vibrate at right angles to the direction of the wave motion.
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seismic waves
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the energy waves given off by earthquakes.
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subduction
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the plate tectonic process in which one of the plates at a convergent boundary sinks under the other plate and eventually melts into the asthenosphere.
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tectonic plate
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section of the lithosphere that moves around earth's solid surfaces.
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transform plate boundary
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a boundary at which plates side by each other, such as the san andreas fault that separates the north american and pacific plates.
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tsunami
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very fast large wavelength ocean wave or waves produced by impact events and disturbances of the ocean floor caused by earthquakes, volcanic eruptions, or landslides.
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uplifted
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raised up; as in mountain building.
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volcanic eruption
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the giving off of gases, lava and lava rock onto earth's surface through the opening of a volcano.
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volcano
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a mound or mountain composed of extrusive igneous rock.
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young mountains
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mountains that are presently rising because they are at the location of converging plates or at the site of a hot spot.
