plate tectonics

plate tectonics
plate tectonics plate tectonics, n. (Geol.) A geological theory which holds that the crust of the earth (the lithosphere) is divided into a small number of large separate plates which float and move slowly around on the more plastic asthenosphere, breaking apart and moving away from each other at points where magma upwells from below, and, driven by such upwellings and other currents on the athenosphere, sliding past each other, colliding with each other, and in some cases being submerged (subducted) one below the other. This theory is now widely accepted, and explains many geological phenomena such as the clustered locations of earthquakes, mountain building, volcanism, and the similarities observed between the geology of continents, such as South America and Africa which are now far apart, but, according to the theory, were once joined together. The motions of such tectonic plates are very slow, typically only several centimeters per year, but over tens and hundreds of millions of years, cause very large changes in the relative positions of the continents. The consequence of such movement of plates is called {continental drift}. [PJC]

The Collaborative International Dictionary of English. 2000.

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  • plate tectonics — plate tectonic, adj. Geol. a theory of global tectonics in which the lithosphere is divided into a number of crustal plates, each of which moves on the plastic asthenosphere more or less independently to collide with, slide under, or move past… …   Universalium

  • plate tectonics — Tectonics Tec*ton ics, n. 1. The science, or the art, by which implements, vessels, dwellings, or other edifices, are constructed, both agreeably to the end for which they are designed, and in conformity with artistic sentiments and ideas. [1913… …   The Collaborative International Dictionary of English

  • plate tectonics — n. Geol. the theory that the earth s surface consists of plates, or large crustal slabs, whose constant motion explains continental drift, mountain building, etc …   English World dictionary

  • Plate tectonics — The tectonic plates of the world were mapped in the second half of the 20th century …   Wikipedia

  • plate tectonics — noun the branch of geology studying the folding and faulting of the earth s crust • Syn: ↑tectonics, ↑plate tectonic theory • Members of this Topic: ↑Pangaea, ↑Pangea • Hypernyms: ↑morphology, ↑ …   Useful english dictionary

  • plate tectonics — /pleɪt tɛkˈtɒnɪks/ (say playt tek toniks) noun a theory concerning the movements of the earth s lithosphere that explains how tectonic plates ride on the moving asthenosphere; supporting the theory of continental drift and sea floor spreading.… …  

  • plate tectonics — N UNCOUNT Plate tectonics is the way that large pieces of the earth s surface move slowly around. [TECHNICAL] …   English dictionary

  • plate tectonics — plate′ tecton′ics n. gel a geologic theory that describes the earth s crust as divided into a number of rigid plates, movement of which accounts for such phenomena as continental drift and the distribution of earthquakes • Etymology: 1965–70… …   From formal English to slang

  • plate tectonics — plate tec tonics n [U] technical the study of the forming and movement of the large sheets of rock that form the surface of the Earth …   Dictionary of contemporary English

  • plate tectonics — plate tec tonics noun uncount SCIENCE the study of the large layers of rock under the surface of the Earth, and how they were formed and move …   Usage of the words and phrases in modern English

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