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43 Cards in this Set
- Front
- Back
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galaxy
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a large group of stars held together by gravity
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Milky Way
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Our outer galaxy
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spectrum
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a band of colors made when white light is broken up
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expansion redshift
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the shift of a spectrum of a galaxy toward longer(redder)wavelengths due to the expansion of space
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big bang
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the beginning of the universe, when the density of the universe was very high
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background radiation
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electromagnetic radiation left over from the big bang
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quasar
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an extremely bright, extremely distant, high-energy source
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crust
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Earth's solid, rocky surface containing the continents and ocean floor
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original horizontality
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the idea that many kinds of rocks form in flat, horizontal layers
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continental drift
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the idea that a supercontinent split apart into pieces, the continents, which drifted in time to their present locations
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sea-floor spreading
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the idea that new crust is forming at ridges in the sea floor, spreading apart the crust on either side of the ridges
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magma
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hot,molten rock below Earth's surface
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plate tectonics
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the idea that Earth's surface is broken into plates that move
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mantle
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Earth's layer beneath the crust
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subduction
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where plates collide, the sliding of a denser ocean plate under another plate
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fault
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a huge in the crust, at or below the surface, the sides of which may show evidence of motion
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focus
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the point where an earthquake starts, where rocks begin to slice past each other
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seismic wave
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a vibration that spreads out away from a focus when an earthquake happens
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epicenter
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the point on Earth's surface directly above the focus
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aftershock
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the shaking of the crust after the the initial shaking of an earthquake
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seismograph
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a sensitive device that detects the shaking of the crust
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magnitude
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the amount of energy released by an earthquake
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hot spot
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a very hot part of the mantle, where magma can melt through a plate moving above it
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vent
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a central opening in a volcanic area through which magma may escape
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lava
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magma that reaches Earth's surface and flows out of a vent
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crater
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a cuplike hollow that forms at the top of a volcano around the vent
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cinder-cone volcano
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a steep-sided cone that forms from e eruptions of hot rocks, ranging from particles to boulders
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shield volcano
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a wide, gently sloped cone that forms from flows of lava
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composite volcano
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a cone formed from e eruptions of hot rocks followed by a flow of lava, over and over
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geothermal energy
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heat from below Earth's surface
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fold mountain
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a mountain made mostly of rock layers folded by being squeezed together
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fault-block mountain
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a mountain made by huge tilted blocks of rocks separated from surrounding rocks by faults
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weathering
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the breaking down of rocks into smaller pieces by natural processes
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erosion
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the picking up and removal of rock particles
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soil
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a mixture of weathered rock, decayed plant and animal matter, living things, air, and water
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soil horizon
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any of the layers of soil from the surface to the bedrock below
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groundwater
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water that soaks into the soil and rock by collecting in spaces between rock particles
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humus
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material in soil formed by the breakdown of plant and animal material
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mass wasting
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the downhill movement of Earth material caused by gravity
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desposition
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the dropping off of sediment
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glacier
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a huge sheet of ice and snow that moves slowly over the land
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till
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a jumble of many sizes of sediment deposited by a glacier
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moraine
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a deposit of many sizes of sediment in front of or along the sides of a glacier
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