Plate tectonics

Simplified map of Earth's principal tectonic plates, which were mapped in the second half of the 20th century (red arrows indicate direction of movement at plate boundaries)
Diagram of the internal layering of Earth showing the lithosphere above the asthenosphere (not to scale)
Divergent boundary
Convergent boundary
Transform boundary
Plate motion based on Global Positioning System (GPS) satellite data from NASA JPL. Each red dot is a measuring point and vectors show direction and magnitude of motion.
Detailed map showing the tectonic plates with their movement vectors.
Alfred Wegener in Greenland in the winter of 1912–13.
Global earthquake epicenters, 1963–1998. Most earthquakes occur in narrow belts that correspond to the locations of lithospheric plate boundaries.
Map of earthquakes in 2016
Seafloor magnetic striping.
A demonstration of magnetic striping. (The darker the color is, the closer it is to normal polarity)
Plate tectonics map

Generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large tectonic plates which have been slowly moving since about 3.4 billion years ago.

- Plate tectonics
Simplified map of Earth's principal tectonic plates, which were mapped in the second half of the 20th century (red arrows indicate direction of movement at plate boundaries)

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Satellite image of a fault in the Taklamakan Desert. The two colorful ridges (at bottom left and top right) used to form a single continuous line, but have been split apart by movement along the fault.

Fault (geology)

Planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements.

Planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements.

Satellite image of a fault in the Taklamakan Desert. The two colorful ridges (at bottom left and top right) used to form a single continuous line, but have been split apart by movement along the fault.
Normal fault in La Herradura Formation, Morro Solar, Peru. The light layer of rock shows the displacement. A second normal fault is at the right.
A fault in Morocco. The fault plane is the steeply leftward-dipping line in the centre of the photo, which is the plane along which the rock layers to the left have slipped downwards, relative to the layers to the right of the fault.
Normal fault and drag folds (eastern flanks of the Bighorn Mountains, Wyoming, USA)
Microfault showing a piercing point (the coin's diameter is 18 mm)
Schematic illustration of the two strike-slip fault types
Normal faults in Spain, between which rock layers have slipped downwards (at photo's centre)
Cross-sectional illustration of normal and reverse dip-slip faults
Oblique-slip fault
Listric fault (red line)
Salmon-colored fault gouge and associated fault separates two different rock types on the left (dark gray) and right (light gray). From the Gobi of Mongolia.
Inactive fault from Sudbury to Sault Ste. Marie, Northern Ontario, Canada

Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults.

Diagram of the geological process of subduction

Subduction

Geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries.

Geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries.

Diagram of the geological process of subduction
The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone
Oceanic plates are subducted creating oceanic trenches.
350 px

Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the heavier plate dives beneath the second plate and sinks into the mantle.

Mid-ocean ridge cross-section (cut-away view)

Mid-ocean ridge

Mid-ocean ridge cross-section (cut-away view)
World distribution of mid-oceanic ridges
Map of Marie Tharp and Bruce Heezen, painted by Heinrich C. Berann (1977), showing the relief of the ocean floors with the system of mid-ocean ridges
A mid-ocean ridge, with magma rising from a chamber below, forming new oceanic lithosphere that spreads away from the ridge
Rift zone in Þingvellir National Park, Iceland. The island is a sub-aerial part of the Mid-Atlantic Ridge
Age of oceanic crust. The red is most recent, and blue is the oldest.
Oceanic crust is formed at an oceanic ridge, while the lithosphere is subducted back into the asthenosphere at trenches.
Magnesium/calcium ratio changes at mid-ocean ridges
Oceanic ridge and deep sea vent chemistry
Plates in the crust of the earth, according to the plate tectonics theory
Seafloor magnetic striping
A demonstration of magnetic striping

A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics.

The asthenosphere shown at a subduction boundary

Asthenosphere

Mechanically weak and ductile region of the upper mantle of Earth.

Mechanically weak and ductile region of the upper mantle of Earth.

The asthenosphere shown at a subduction boundary
The asthenosphere in relation to the other layers of Earth's structure

The asthenosphere is a part of the upper mantle just below the lithosphere that is involved in plate tectonic movement and isostatic adjustments.

The tectonic plates of the world were mapped in the second half of the 20th century. Plate tectonic theory successfully explains numerous observations about the Earth, including the distribution of earthquakes, mountains, continents, and oceans.

Scientific theory

Explanation of an aspect of the natural world and universe that has been repeatedly tested and corroborated in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results.

Explanation of an aspect of the natural world and universe that has been repeatedly tested and corroborated in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results.

The tectonic plates of the world were mapped in the second half of the 20th century. Plate tectonic theory successfully explains numerous observations about the Earth, including the distribution of earthquakes, mountains, continents, and oceans.
The first observation of cells, by Robert Hooke, using an early microscope. This led to the development of cell theory.
In quantum mechanics, the electrons of an atom occupy orbitals around the nucleus. This image shows the orbitals of a hydrogen atom (s, p, d) at three different energy levels (1, 2, 3). Brighter areas correspond to higher probability density.
Precession of the perihelion of Mercury (exaggerated). The deviation in Mercury's position from the Newtonian prediction is about 43 arc-seconds (about two-thirds of 1/60 of a degree) per century.

These qualities are certainly true of such established theories as special and general relativity, quantum mechanics, plate tectonics, the modern evolutionary synthesis, etc.

A bathymetric map of the Mid-Atlantic Ridge (shown in light blue in the middle of the Atlantic Ocean)

Mid-Atlantic Ridge

A bathymetric map of the Mid-Atlantic Ridge (shown in light blue in the middle of the Atlantic Ocean)
Pangaea's separation animated
Basaltic rocks of the Mid-Atlantic Ridge observed by the Hercules ROV during the 2005 Lost City Expedition

The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world.

The colours indicate the age of oceanic crust, wherein redder indicates younger age, and bluer indicates older age. The lines represent tectonic plate boundaries.

Oceanic crust

The colours indicate the age of oceanic crust, wherein redder indicates younger age, and bluer indicates older age. The lines represent tectonic plate boundaries.
Continental and oceanic crust on the Earth's upper mantle

Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates.

Upper mantle (Earth)

Very thick layer of rock inside the planet, which begins just beneath the crust and ends at the top of the lower mantle at 670 km. Temperatures range from approximately 200 C at the upper boundary with the crust to approximately 900 C at the boundary with the lower mantle.

Very thick layer of rock inside the planet, which begins just beneath the crust and ends at the top of the lower mantle at 670 km. Temperatures range from approximately 200 C at the upper boundary with the crust to approximately 900 C at the boundary with the lower mantle.

Cross-section of the Earth, showing the paths of earthquake waves. The paths curve because the different rock types found at different depths change the waves' speed. S waves do not travel through the core
Chikyu drilling ship

However, when large forces are applied to the uppermost mantle, it can become weaker, and this effect is thought to be important in allowing the formation of tectonic plate boundaries.

Abraham Ortelius by Peter Paul Rubens, 1633

Continental drift

Hypothesis that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed.

Hypothesis that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed.

Abraham Ortelius by Peter Paul Rubens, 1633
Antonio Snider-Pellegrini's Illustration of the closed and opened Atlantic Ocean (1858)
Alfred Wegener
Fossil patterns across continents (Gondwanaland)
Mesosaurus skeleton, MacGregor, 1908

The idea of continental drift has been subsumed into the science of plate tectonics, which studies the movement of the continents as they ride on plates of the Earth's lithosphere.

The internal structure of Earth

Crust (geology)

Outermost solid shell of a rocky planet, dwarf planet, or natural satellite.

Outermost solid shell of a rocky planet, dwarf planet, or natural satellite.

The internal structure of Earth
Plates in the crust of Earth

There is no evidence of plate tectonics.