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Plate Tectonics
flashcards on plate tectonics
| Question | Answer |
|---|---|
| continental drift | the theory that the continents were once a huge supercontinent, but broke apart from this Pangaea to drift and settle in the places where they are today |
| mid ocean ridge | a long, undersea mountain chain that has a steep, narrow valley at its center, that forms as magma rises from the astheno- sphere, and that creates new oceanic lithosphere (sea floor) as tectonic plates move apart (262) |
| sea floor spreading | the process by which new oceanic lithosphere (sea floor) forms when magma rises to Earth’s surface at mid- ocean ridges and solidifies, as older, existing sea floor moves away from the ridge (263) |
| paleomagnetism | the study of the alignment of magnetic minerals in rock, specifically as it relates to the reversal of Earth’s mag- netic poles; also the magnetic properties that rock acquires during formation (263) |
| plate tectonics | the theory that explains how large pieces of the lithosphere, called plates, move and change shape (267) |
| lithosphere | the solid, outer layer of Earth that consists of the crust and the rigid upper part of the mantle (31, 267) |
| asthenosphere | the solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tec- tonic plates to move on top of it (31, 267) |
| convection | the movement of matter due to differences in density that are caused by tem- perature variations; can result in the transfer of energy as heat (526) |
| crust | the thin and solid outermost layer of Earth above the mantle (30) |
| mantle | in Earth science, the layer of rock between Earth’s crust and core (30) |
| outer core | outer part of the core, liquid mantle |
| divergent boundary | the boundary between two tectonic plates that are moving away from each other (269) |
| convergent boundary | the boundary between tectonic plates that are colliding (270) |
| transform boundary | the boundary between tectonic plates that are sliding past each other horizontally (271) |
| subduction | at a transform boundary, when one plate slides under another plate |
| trench | a long, narrow, and steep depression that forms on the ocean floor as a result of subduction of a tectonic plate |
| rifting | the process by which Earth’s crust breaks apart; can occur within continental crust or oceanic crust (275) |
| Pangaea | the supercontinent that formed 300 million years ago and that began to break up 200 million years ago (278) |
| earthquake | a movement or trembling of the ground that is caused by a sudden release of energy when rocks along a fault move |
| elastic rebound | the sudden return of elastically deformed rock to its undeformed shape |
| focus | the location within Earth along a fault at which the first motion of an earthquake occurs |
| epicenter | the point on Earth’s surface directly above an earthquake’s starting point, or focus |
| body wave | in geology, a seismic wave that travels through the body of a medium |
| surface wave | in geology, a seismic wave that travels along the surface of a medium and that has a stronger effect near the surface of the medium than it has in the interior |
| p wave | a primary wave, or compression wave; a seismic wave that causes particles of rock to move in a back-and-forth direction parallel to the direction in which the wave is traveling; P waves are the fastest seismic waves and can travel through solids, |
| s wave | a secondary wave, or shear wave; a seismic wave that causes particles of rock to move in a side-to-side direction perpendicular to the direction in which the wave is traveling; S waves are the secondfastest seismic waves and can travel only through |
| seismograph | a tracing of earthquake motion that is recorded by a seismograph ( |
| seismogram | a tracing of earthquake motion that is recorded by a seismograph |
| magnitude | a measure of the strength of an earthquake |
| tsunami | a giant ocean wave that forms after a volcanic eruption, submarine earthquake, or landslide |
| seismic gap | an area along a fault where relatively few earthquakes have occurred recently but where strong earthquakes are known to have occurred in the past |
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imcguire981
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