Plate Tectonics

Plate tectonics (from the Late Latin tectonicus, from the Greek: τεκτονικός "pertaining to building") is a scientific theory that describes the large-scale motions of Earth's lithosphere. The model builds on the concepts of continental drift, developed during the first decades of the 20th century. It was accepted by the geoscientific community after the concepts of seafloor spreading were developed in the late 1950s and early 1960s.

The lithosphere is broken up into tectonic plates. On Earth, there are seven or eight major plates (depending on how they are defined) and many minor plates. Where plates meet, their relative motion determines the type of boundary: convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates typically varies from zero to 100 mm annually.

Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle; the material lost is roughly balanced by the formation of new (oceanic) crust along divergent margins by seafloor spreading. In this way, the total surface of the globe remains the same. This prediction of plate tectonics is also referred to as the conveyor belt principle. Earlier theories (that still have some supporters) proposed gradual shrinking (contraction) or gradual expansion of the globe.

Tectonic plates are able to move because the Earth's lithosphere has a higher strength and lower density than the underlying asthenosphere. Lateral density variations in the mantle result in convection. Their movement is thought to be driven by a combination of the motion of seafloor away from the spreading ridge (due to variations in topography and density of the crust that result in differences in gravitational forces) and drag, downward suction, at the subduction zones. A different explanation lies in different forces generated by the rotation of the globe and tidal forces of the Sun and the Moon. The relative importance of each of these factors is unclear, and is still subject to debate (see also below).

Read more about Plate TectonicsKey Principles, Types of Plate Boundaries, Driving Forces of Plate Motion, Development of The Theory, Implications For Biogeography, Plate Reconstruction, Current Plates, Other Celestial Bodies (planets, Moons)

Other articles related to "plate tectonics, plates, tectonic, plate":

Plate Tectonics - Other Celestial Bodies (planets, Moons) - Exoplanets
... On Earth-sized planets, plate tectonics is more likely if there are oceans of water, however in 2007 two independent teams of researchers came to opposing conclusions about ...
Super-Earths - Characteristics
... would be more geologically active than Earth, with more vigorous plate tectonics due to thinner plates under more stress ... case, just barely large enough to sustain plate tectonics ... in the mantle acting on strong gravity would make the crust stronger and thus inhibit plate tectonics ...
Planetary Habitability - Planetary Characteristics - Mass
... quickly and end up geologically dead, lacking the volcanoes, earthquakes and tectonic activity which supply the surface with life-sustaining material and the atmosphere with ... Plate tectonics appear particularly crucial, at least on Earth not only does the process recycle important chemicals and minerals, it also fosters bio-diversity ... in fact lie on the lower boundary of habitability, since if it were any smaller, plate tectonics would be impossible ...
Mid-ocean Ridge - History - Impact
... Plate tectonics was a suitable explanation for sea floor spreading, and the acceptance of plate tectonics by the majority of geologists resulted in a major paradigm shift in geological thinking ... The red is most recent, and blue is the oldest Plates in the crust of the earth, according to the plate tectonics theory Seafloor magnetic striping A demonstration of magnetic ...
Afar Triple Junction - Plate Tectonics
... See also Plate tectonics The Aden Ridge, Red Sea Rift, and the East African Rift all meet at the Afar Triple Junction ... Here, the Arabian plate and Nubian and Somali proto-plates are being pulled apart, which forms three divergent plate boundaries ... Divergent plate boundaries are fundamental features of plate tectonics and are associated with rifts and mid-ocean ridges ...

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