"Plate tectonics is the scientific theory that Earth's lithosphere comprises a number of large tectonic plates which have been slowly moving since about 3.4 billion years ago."
The theory that the Earth's crust is made up of a series of large plates that move and interact with one another over time, leading to the formation of mountains, earthquakes, and other geological features.
Geologic time scale: A chronological ordering of the events in Earth's history.
Continental drift: The slow movement of continents over geologic time.
Seafloor spreading: The process whereby new oceanic crust is formed at mid-ocean ridges and spreads out from there.
Plate boundaries: The regions where different tectonic plates meet and interact with one another.
Plate tectonic theory: The scientific understanding that Earth's lithosphere is divided into several large plates that move and interact with one another.
Convection currents: The circulating flows of magma in the mantle that cause the movement of the Earth's tectonic plates.
Subduction zones: The regions where one tectonic plate is forced under another and into the mantle.
Volcanism: The phenomenon of volcanic eruptions and the formation of new land masses.
Earthquakes: The sudden release of energy from within the Earth's crust, often caused by the movement of tectonic plates.
Geologic hazards: The potential risks posed by earthquakes, volcanic eruptions, and other geologic events.
Divergent Plate Boundaries: These are boundaries where tectonic plates move away from each other, and new crust is formed. This process is known as seafloor spreading.
Convergent Plate Boundaries: At these boundaries, plates move towards each other, and one plate is usually subducted (or pushed) under the other. This forms deep ocean trenches and volcanic arcs above the subduction zone.
Transform Plate Boundaries: These boundaries are where plates slide past each other horizontally. This results in a lot of seismic activity and the formation of faults.
Hotspots: These are areas of volcanic activity that are not associated with plate boundaries. A hotspot is thought to be caused by a deep mantle plume.
Supercontinental Cycles: Over millions of years, continents collide and rift apart, eventually forming supercontinents. The most recent supercontinent was Pangaea, which formed about 300 million years ago.
Continental Drift: This refers to the movement of continents over time. Alfred Wegener first proposed the idea of continental drift in 1915, but it was not widely accepted until the theory of plate tectonics was developed in the 1960s.
Ridge Push: This is a force that is created at mid-ocean ridges, where new crust is formed. As new crust is added, the older crust is pushed away, creating a force that helps drive plate movement.
Slab Pull: This force is created when a denser plate is subducted under a less dense plate. As the slab sinks into the mantle, it pulls the rest of the plate along with it.
"The model builds on the concept of continental drift, an idea developed during the first decades of the 20th century."
"Plate tectonics came to be accepted by geoscientists after seafloor spreading was validated in the mid-to-late 1960s."
"Earth's lithosphere is broken into seven or eight major plates."
"Where the plates meet, their relative motion determines the type of plate boundary: convergent, divergent, or transform."
"Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries."
"The relative movement of the plates typically ranges from zero to 10 cm annually."
"Tectonic plates are composed of the oceanic lithosphere and the thicker continental lithosphere, each topped by its own kind of crust."
"Along convergent plate boundaries, the process of subduction, or of one plate moving under another, carries the edge of one plate down under the other plate and into the mantle."
"The lost surface is balanced by the formation of new oceanic crust along divergent margins by seafloor spreading."
"This process of plate tectonics is also referred to as the conveyor belt principle."
"Tectonic plates are able to move because Earth's lithosphere has greater mechanical strength than the underlying asthenosphere."
"Plate movement is driven by a combination of the motion of the seafloor away from spreading ridges due to variations in topography and density changes in the crust."
"At subduction zones, the relatively cold, dense oceanic crust sinks down into the mantle forming the downward convecting limb of a mantle cell. This is the strongest driver of the plates."
"The relative importance of other proposed factors such as active convection, upwelling and flow inside the mantle, and tidal drag of the moon, and their relationship to each other is still the subject of debate."