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12 Cards in this Set
- Front
- Back
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Continental Drift |
the gradual movement of the continents across the earth's surface through geological time. |
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Mid-Ocean Ridge |
a long, seismically active submarine ridge system situated in the middle of an ocean basin and marking the site of the upwelling of magma associated with seafloor spreading. An example is the Mid-Atlantic Ridge. |
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Sea Floor Spreading |
the formation of new areas of oceanic crust, which occurs through the upwelling of magma at midocean ridges and its subsequent outward movement on either side. |
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Convection Current |
a current in a fluid that results from convection. |
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Lithosphere |
the rigid outer part of the earth, consisting of the crust and upper mantle. |
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Asthenosphere |
the upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur. |
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Pangaea |
the hypothetical landmass that existed when all continents were joined, from about 300 to 200 million years ago. |
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Divergent Boundary |
A tectonic boundary where two plates are moving away from each other and new crust is forming from magma that rises to the Earth's surface between the two plates. |
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Transform Boundary |
The result of two massive plates pushing against one another is that massive amounts of energy build up. Occasionally this energy is released suddenly in the form of large earthquakes. |
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Deep Ocean Trench |
a long narrow steep-sided depression in the earth's oceanic crust,usually lying above a subduction zone |
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Subduction |
the sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate. |
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Convergent Boudary |
a major geologic discontinuity or suture marking the juncture of lithospheric plates that have been joined by plate tectonics. |
