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PCS Earth Science
Chapter 17 Vocabulary - Plate Tectonics
| Term | Definition |
|---|---|
| continental drift | Wegener's hypothesis that Earth's continents were joined as a single landmass, called Pangaea, that broke apart about 200 million years ago and slowly moved to their current positions |
| convection | process by which, in a fluid being heated, the warmer part of the mass will rise and the cooler parts will sink |
| convergent boundary | place where two of Earth's tectonic plates are moved toward each other; is associated trenches, island arcs, and folded mountains |
| divergent boundary | place where two of Earth's tectonic plates are moving apart; is associated with volcanism, earthquakes, and high heat flow, and is found primarily on the sea floor |
| isochron | line on a map that connects points of the same age |
| magnetic reversal | changes in Earth's magnetic field over geologic time, recorded in ocean-floor rocks and continental basalt flows |
| magnetometer | device used to map the ocean floor that detects small changes in magnetic fields |
| paleomagnetism | study of Earth's magnetic record using data gathered from iron-bearing minerals in rocks that have recorded the orientation of Earth's magnetic field at the time of their formation |
| Pangaea | ancient landmass made up of all the continents that begin to break apart about 200 million years ago |
| ridge push | tectonic process associated with convection currents in Earth's mantle that occurs when the weight of an elevated ridge pushes an oceanic plate toward a subduction zone |
| rift valley | long, narrow depression that forms when continental crust begins to separate at a divergent boundary |
| seafloor spreading | Hess' theory that new ocean crust is formed at mid-ocean ridges and destroyed at deep-sea trenches; occurs in a continuous cycle of magma intrucion and spreading |
| slab pull | tectonic process associated with convection currents in Earth's mantle that occurs as the weight of the subducting plate pulls the trailing lithosphere into a subduction zone |
| subduction | process by which one tectonic plate slips beneath another tectonic plate |
| theory of plate tectonics | states that the Earth's crust and upper mantle are broken into plates, which are huge rock slabs that move in different directions and at different rates over Earth's surface |
| transform boundary | place where two tectonic plates slide horizontally past each other that is characterized by long faults and shallow earthquakes |
Created by:
Ms.Sala
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