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Plate Tectonics

Importance Of Plate Tectonics

Plate tectonics revolutionized the way geologists view Earth. This new paradigm brings together nearly all the divisions of geologic study. Like the theory of evolution in biology, plate tectonics is the unifying concept of geology. Plate tectonics' initial appeal and rapid acceptance resulted from its ability to provide answers to many nagging questions about a variety of seemingly unrelated phenomena. Plate tectonics also revitalized the field of geology by providing a new perspective from which to interpret many old ideas. Finally, plate tectonics explains nearly all of Earth's major surface features and activities. These include faults and earthquakes, volcanoes and volcanism, mountains and mountain building, and even the origin of the continents and ocean basins.

See also Earth science.



Hancock, P.L., and B.J. Skinner, eds. The Oxford Companion to the Earth. New York: Oxford University Press, 2000.

Tarbuck, Edward. D., Frederick K. Lutgens, and Tasa Dennis. Earth: An Introduction to Physical Geology. 7th ed. Upper Saddle River, NJ: Prentice Hall, 2002.

Winchester, Simon. The Map That Changed the World: William Smith and the Birth of Modern Geology. New York: Harper Collins, 2001.


Buffett, Bruce A. "Earth's Core and the Geodynamo." Science (June 16, 2000): 2007–2012.

Hellfrich, George, and Bernard Wood. "The Earth's Mantle." Nature (August 2, 2001): 501–507.


United States Department of the Interior, U.S. Geological Survey. "This Dynamic Earth: The Story of Plate Tectonics." February 21, 2002 [cited March 11, 2003]. <http://pubs.usgs.gov/publications/text/dynamic.html>.

K. Lee Lerner

Clay Harris


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—The addition of sediment or rock to a plate's margin at a subduction zone. Material is scraped off the subducting plate and adheres to the edge of the overriding plate.


—A dense, dark colored igneous rock, with a composition rich in iron and magnesium (a mafic composition).

Convection cells

—The circular movement of a fluid in response to alternating heating and cooling. Convection cells in the earth's interior involve molten rock that rises upwards below midoceanic ridges.


—The movement of two plate margins toward one another; usually associated with plate subduction or the collision of two continents.


—The outermost layer of the earth, situated over the mantle and divided into continental and oceanic crust.


—The separation of two plate margins as they move in opposing directions; usually associated with either sea floor spreading or continental rifting.


—A light-colored igneous rock that is less dense than basalt due to an abundance of lighter elements, such as silicon and oxygen (a felsic composition).

Hot spots

—Areas in the mantle, associated with rising plumes of molten rock, which produce frequent, localized volcanic eruptions at Earth's surface.

Magnetic reversals

—Periods during which the earth's magnetic poles flip-flop; that is, the orientation of Earth's magnetic field reverses. During these periods of reversed magnetism, compass needles point toward the south pole.


—The thick, dense layer of rock that underlies Earth's crust.


—Volcanic islands of intermediate to felsic composition that were too buoyant to subduct, and therefore formed the first continental crust.

Mid-oceanic ridges

—Continuous submarine mountain ranges, composed of basalt, where new sea floor is created.

Ocean trench

—A deep depression in the sea floor, created by an oceanic plate being forced downward into the subsurface by another, overriding plate.


—Large regions of the earth's surface, composed of the crust and uppermost mantle, which move about, forming many of Earth's major geologic surface features.

Sea-floor spreading

—The part of plate tectonics that describes the movement of the edges of two of the plates forming Earth's crust away from each other under the ocean. Sea-floor spreading results in the formation of new submarine surfaces.


—In plate tectonics, the movement of one plate down into the mantle where the rock melts and becomes magma source material for new rock.

Transform motion

—Horizontal plate movement in which one plate margin slides past another.

Additional topics

Science EncyclopediaScience & Philosophy: Planck mass to PositPlate Tectonics - Continental Drift Versus Plate Tectonics, An Overview Of Tectonic Theory, Proofs Of Tectonic Theory, Rates Of Plate Movement