Plate Tectonics and Plate Motion

Plate tectonics theory

Plate tectonics is the scientific theory that Earth's rigid lithosphere is divided into large and small tectonic plates that have moved slowly for billions of years. These plates float on the hotter, weaker asthenosphere and consist of oceanic crust, continental crust, and underlying lithospheric mantle. The theory developed from continental drift and gained broad acceptance after evidence for seafloor spreading emerged in the 1960s. Plate interactions occur at three main types of boundaries: divergent boundaries, where plates separate and new crust forms; convergent boundaries, where plates collide, causing subduction or mountain building; and transform boundaries, where plates slide past one another. These movements produce earthquakes, volcanoes, mountain ranges, mid-ocean ridges, and oceanic trenches. Plate motion is driven mainly by the sinking of cold, dense oceanic lithosphere at subduction zones, with contributions from mantle convection and gravitational sliding from elevated ridges.

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Earth’s lithosphere and asthenosphere

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