What is Plate tectonics?
[[File:Plates tect2 en.svg|thumb|250px|The tectonic plates of the world were mapped in the second half of the 20th century.]] [[File:Tectonicplates Serret.png|thumb|250px|Tectonic plates on a different map projection]] [[File:Quake epicenters 1963-98.png|thumb|250px|Global earthquake [[epicenter]]s, 1963–1998]] [[File:Global plate motion 2008-04-17.jpg|thumb|250px|right|Global tectonic plate movement]] '''Plate tectonics''' is a [[theory]] of [[geology]]. It explains movement of the [[Earth]]'s [[lithosphere]]. The lithosphere is the [[Earth's crust]] and the upper part of the [[Earth's mantle|mantle]]. The lithosphere is divided into plates, some of which are very large and can be entire [[continent]]s. Heat from the [[Mantle (geology)|mantle]] is the source of energy driving plate tectonics. Exactly how this works is still a matter of debate. This theory includes the idea of [[continental drift]].<ref name='Turcotte-and-Schubert_2002'/> == Earth's crust == The outermost part of the [[structure of the Earth]] is made up of two layers. The lithosphere, above, is solid. It includes the [[Crust (geology)|crust]] and the uppermost part of the mantle. Below the lithosphere is the [[asthenosphere]]. The asthenosphere is like a solid or a hot [[viscosity|viscous]] liquid. It can flow like a liquid on long time scales. Large [[convection]] currents in the asthenosphere transfer heat to the surface, where plumes of less dense [[magma]] break apart the plates at the spreading centers. The deeper mantle below the asthenosphere is more rigid again. This is caused by extremely high pressure. === Continental and oceanic plates === There are two types of tectonic plates: oceanic and continental. An [[ocean]]ic plate is a tectonic plate at the bottom of the oceans. It is primarily made of [[mafic]] rocks, rich in [[iron]] and [[magnesium]]. It is thinner than the continental crust (generally less than 10 kilometers thick) and [[density|denser]]. It is also younger than continental crust. When they collide, the oceanic pl