Plate Tectonics
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Created by:
mshsglobalscience on January 2, 2010
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28 terms
Terms | Definitions |
|---|---|
 asthenosphere | the soft layer of the mantle on which the lithosphere floats |
| continental crust | The portion of the earth's crust that primarily contains granite, is less dense than oceanic crust, and is 20-50 km thick |
| convection | the transfer of heat by the movement of currents within a fluid |
| crust | the outer layer of the Earth |
| inner core | a dense sphere of solid iron and nickel at the center of the earth |
| lithosphere | the solid, outer layer of the earth that consists of the crust and the rigid upper part of the mantle |
| oceanic crust | The portion of earth's crust that primarily contains basalt, is relatively dense, and is about 5 km thick |
| outer core | a layer of molten iron and nickel that surrounds the inner core of Earth |
| mid-ocean ridge | a large system of undersea mountain chain where new ocean floor is produced; a constructive (divergent) plate boundary; great deal of volcanic activity |
| mantle convection | Hot rock rises slowly and plastically from deep within Earth, then cools, flows sideways, and sinks. |
| molten rock | rock that is so hot it is a very thick, slow-moving liquid. |
| plate boundaries | when plates interact with each other |
| sea floor spreading | the theory that new crust is constantly being added to the oceanic crust at mid-ocean ridges |
| subduction zones | occurs when one oceanic plate is forced down into the mantle beneath a second plate |
| tectonic plates | individual sections of the lithosphere of the earth. They fit together in a way similar to a jigsaw puzzle, but are always moving very slowly, floating on the molten rock of the lower mantle. |
| transform faults | faults where there is no loss or gain in plate material, plates slide past each other and are areas of earthquakes |
| convergent boundaries | is a place where 2 plates come together. At places where oceanic crust converges, the denser oceanic crust will dive under the other (subduction). At places where oceanic crust and continental crust converge, the denser oceanic crust will dive under (subduction) the less dense continental crust. At places where 2 continental crusts converge, subduction does not take place. Rather, the plates crash and squeeze rock up into mountains!!! |
| divergent boundaries | is a place where 2 plates move apart. Most of these types of boundaries occur at the mid-ocean ridge. On land, this boundary is called a rift valley, such as the Great Rift Valley in East Africa and the Rio Grande in Texas. |
| viscosity | resistance of a substance to flow |
| rift valley | a deep valley that forms where two plates move apart |
| volcanic island arc | Linear group of volcanoes that form due to subduction of an oceanic plate under another oceanic plate |
| transform boundary | the boundary between tectonic plates that are sliding past each other horizontally |
| deep sea trenches | a deep valley along the ocean floor through which oceanic crust slowly sinks toward the mantle |
| Continental Drift Theory | theory proposed by Alfred Wegener in 1915 that continents drifted apart based on matching coastlines of continents, matching rock types, geographical features, fossils, coal deposits indicating similar climates in areas that are no far apart from each other, etc. not accepted though by scientific community b/c there was no explanation for what moved the continents |
| Plate Tectonic Theory | Describes the formation, motion, and interaction of crustal plates. Combines older theories of sea-floor spreading and continental drift |
| Alfred Wegener | A German scientist who proposed the theory of continental drift |
| Hess | american geologist who studied mid ocean ridges and supported Wegener's hypothesis |
| Gondwana | an ancient continent made up of present-day Africa, South America, Antarctica, Australia, and India |
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