Plate tectonics
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Plate tectonics : the theory that explains how large pieces of the lithosphere called plates move and change shape.
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Continental Drift : the hypothesis that states that the continents once formed a singe landmass broke up and drifted to their present locations.
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Pangaea : the super continent that formed 300 million years ago and that brgan to break up 250 million years ago.
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Asthenosphere : 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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Lithosphere : the solid outer layer of earth that consists of the crust and the rigid upper part of the mantle.
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Mid-Oceanic ridge : a long undersea mountain chain that has a steep narrow valley at its center that forms as magma rises from the asthenosphere and that creates new oceanic lithosphere (sea floor) as tectonic plates move apart.
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Rift valleys : the process by which earth's crust breaks apart can occur within continental crust or oceanic crust.
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Subduction : the process in which a solid changes directly into a gas the term sometime also used for the reverse process.