Ch 10 - Plate Tectonics
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25 terms
Terms | Definitions |
|---|---|
 tectonic plates | blocks of rock that ride on top of the asthenosphere |
| island arc | a chain of volcanic islands that forms near the collision of two oceanic plates |
| terrane | a piece of lithosphere that has a unique geologic history and that may be part of a larger piece of lithosphere, such as a continent |
| Pacific Ring of Fire | a zone of active volcanoes that encircles the Pacific Ocean |
| convergent boundary | the boundary between tectonic plates that are colliding |
| divergent boundary | the boundary between tectonic plates that are moving away from each other |
| continental drift | the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations |
| Laurasia | the large northern landmass that separated after the break up of Pangaea including North America, Europe, and Asia |
| Gondwanaland | the large southern landmass that separated after the break up of Pangaea including South America, Africa, India, Antarctica, and Australia |
| rifting | the process by which Earth's crust breaks apart; can occur within continental crust or oceanic crust. |
| sea-floor spreading | the process by which new oceanic lithosphere (sea floor) forms as magma rises to Earth's surface and solidifies at a mid-ocean ridge |
| Panthalassa | the single, large ocean that covered Earth's surface during the time the supercontinent Pangaea existed |
| paleomagnetism | the study of the alignment of magnetic minerals in rock, specifically as it relates to the reversal of Earth's magnetic poles; also the magnetic properties that rock acquires during formation |
| Pangaea | the supercontinent that formed 300 million years ago and that began to break up beginning 250 million years ago |
| plate tectonics | the theory that explains how large pieces of the lithosphere, called plates, move and change shape |
| deep-ocean trench | a deep valley that forms along the boundary where an ocean plate subducts |
| transform boundary | a boundary between tectonic plates that are sliding past each other horizontally |
| mid-ocean 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 |
| rift valley | a narrow valley that forms where the plates separate |
| convection | the movement of heated material due to differences in density created by temperature differences |
| supercontinent cycle | The process by which supercontinents form and break apart over millions of years |
| geomagnetic reversal time scale | alternating periods of normal and reversed polarity in oceanic crust |
| subduction zone | the region along a plate boundary where one plate moves underneath another |
| lithosphere | The solid, outer layer of Earth that consists of the crust and the rigid upper part of the mantle |
| asthenosphere | The solid, plastic-like layer of the mantle that flows very slowly, which allows tectonic plates to move on top of it |
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