View source for Tectonic plate

== Introduction ==
[[Tectonic plates|Tectonic plates]] are large pieces of the Earth's lithosphere that fit together to form the planet's surface. These plates are constantly moving, albeit very slowly, due to the convective forces in the underlying [[asthenosphere|asthenosphere]]. The study of these plates and their movement is known as [[plate tectonics|plate tectonics]], a field that has revolutionized the understanding of Earth's geological history and the processes that shape its surface.

== Composition and Structure ==
Tectonic plates are composed of two types of lithosphere: oceanic and continental. [[Oceanic lithosphere|Oceanic lithosphere]] is denser and thinner, composed primarily of [[basalt|basalt]] and [[gabbro|gabbro]]. In contrast, [[continental lithosphere|continental lithosphere]] is thicker and less dense, composed mainly of [[granite|granite]] and [[andesite|andesite]]. The boundary between the lithosphere and the asthenosphere is known as the [[Mohorovičić discontinuity|Mohorovičić discontinuity]], or Moho.

[[Image:Detail-59196.jpg|thumb|center|Photograph of a cross-section of the Earth's crust showing the different layers.|class=only_on_mobile]]
[[Image:Detail-59197.jpg|thumb|center|Photograph of a cross-section of the Earth's crust showing the different layers.|class=only_on_desktop]]

== Plate Boundaries ==
There are three types of plate boundaries: divergent, convergent, and transform. At [[divergent boundaries|divergent boundaries]], plates move apart from each other, creating space for new lithosphere to form. This is where [[seafloor spreading|seafloor spreading]] occurs. At [[convergent boundaries|convergent boundaries]], plates move towards each other, causing one plate to subduct beneath the other, forming deep [[oceanic trench|oceanic trenches]] and potentially leading to volcanic activity. At [[transform boundaries|transform boundaries]], plates slide past each other horizontally, leading to intense seismic activity.

== Plate Tectonics and Geological Activity ==
The movement of tectonic plates is responsible for most of the Earth's geological activity, including [[earthquake|earthquakes]], [[volcano|volcanoes]], and [[mountain building|mountain building]]. Earthquakes occur when the stress accumulated at plate boundaries is released in the form of seismic waves. Volcanoes form when magma from the asthenosphere reaches the surface, which often occurs at convergent and divergent boundaries. Mountain building, or orogeny, occurs primarily at convergent boundaries where continental lithosphere is involved.

== Plate Tectonics and Earth's History ==
The movement of tectonic plates over geologic time has dramatically reshaped the Earth's surface. This process, known as [[continental drift|continental drift]], was first proposed by Alfred Wegener in the early 20th century. The supercontinent [[Pangaea|Pangaea]], which existed around 300 million years ago, is one of the most well-known examples of continental drift. The breakup of Pangaea led to the formation of the current continents and ocean basins.

== See Also ==
* [[Lithosphere]]
* [[Asthenosphere]]
* [[Seafloor spreading]]
* [[Continental drift]]
* [[Pangaea]]

[[Category:Geology]]
[[Category:Earth Science]]
[[Category:Plate Tectonics]]