All Topics  
Divergent boundary

 

 
   Email Print
   Bookmark   Link
 

 

Divergent boundary
 
 
  Topics Divergent boundary Topic Home

In plate tectonics
Plate tectonics

Plate tectonics describes the large scale motions of Earth's lithosphere. The theory encompasses the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, understood during the 1960s....
, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates
List of tectonic plates

This is a list of tectonic plates on Earth. Tectonic plates are pieces of the Earth's Crust and uppermost mantle, together referred to as the lithosphere....
 that are moving away from each other. These areas can form in the middle of continent
Continent

A continent is one of several large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents ? they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia ....
s but eventually form ocean basins. Divergent boundaries within continents initially produce rifts which produce rift valley
Rift valley

A rift valley is a linear-shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault . This action is manifest as crustal extension, a spreading apart of the surface which is subsequently further deepened by the forces of erosion....
s. If the rifting process stops, a failed rift results.






Discussion
Ask a question about 'Divergent boundary'
Start a new discussion about 'Divergent boundary'
Answer questions from other users
Full Discussion Forum



Encyclopedia


In plate tectonics
Plate tectonics

Plate tectonics describes the large scale motions of Earth's lithosphere. The theory encompasses the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, understood during the 1960s....
, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates
List of tectonic plates

This is a list of tectonic plates on Earth. Tectonic plates are pieces of the Earth's Crust and uppermost mantle, together referred to as the lithosphere....
 that are moving away from each other. These areas can form in the middle of continent
Continent

A continent is one of several large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents ? they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia ....
s but eventually form ocean basins. Divergent boundaries within continents initially produce rifts which produce rift valley
Rift valley

A rift valley is a linear-shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault . This action is manifest as crustal extension, a spreading apart of the surface which is subsequently further deepened by the forces of erosion....
s. If the rifting process stops, a failed rift results. Therefore, most active divergent plate boundaries are between oceanic plate
Oceanic crust

Oceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or Sima ....
s and are often called mid-oceanic ridges. Divergent boundaries also form Volcanic Islands.

Although still an area of active research, it appears that according to complex convection
Convection

Convection in the most general terms refers to the movement of molecules within fluids . Convection is one of the major modes of heat transfer and mass transfer....
 within the Earth
Earth

Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
's mantle
Mantle (geology)

The mantle is a part of an astronomical object. The interior of the Earth, similar to the other terrestrial planets, is chemically divided into layers....
 material rises to the base of the lithosphere
Lithosphere

File:Plates tect2 en.svgFile:Earth-crust-cutaway-english.svgThe lithosphere is the rigid outermost shell of a rocky planet....
 beneath the divergent plate boundary. This supplies the area with vast amounts of heat and a reduction in pressure that melts rock
Rock (geology)

In geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock....
 from the asthenosphere
Asthenosphere

The asthenosphere is the mechanically weak ductily-deforming region of the upper Mantle of the Earth. It lies below the lithosphere, at depths between 100 and 200 km below the surface, but perhaps extending as deep as 400 km ....
 (or upper mantle) beneath the rift area forming large flood basalt
Flood basalt

A flood basalt or trap basalt is the result of a giant volcanic eruption or series of eruptions that coats large stretches of land or the ocean floor with basalt lava....
 or lava flows. Each eruption occurs in only a part of the plate boundary at any one time, but when it does occur, it fills in the opening gap as the two opposing plates move away from each other. The average rate of movement is comparable to how fast human fingernails grow, (about 2 cm a year).

Over millions of years, the plates have moved many hundreds of kilometers away from both sides of the divergent plate boundary. Because of this, rocks closest to the boundary are younger than rocks further away on the same plate.

Examples

  • The Mid-Atlantic Ridge
    Mid-Atlantic Ridge

    The Mid-Atlantic Ridge is a mid-ocean ridge, a divergent tectonics plate boundary located along the floor of the Atlantic Ocean, and the longest mountain range in the world....
  • Red Sea Rift
    Red Sea Rift

    The Red Sea Rift is a spreading center between two tectonic plates, the African Plate and the Arabian Plate. It extends down the length of the Red Sea, stretching from the southern end of the Dead Sea Transform to a triple junction with the Aden Ridge and the East African Rift in the Afar Depression of eastern Africa....
  • East African Rift
    East African Rift

    The East African Rift is part of the larger Great Rift Valley. It is a continental rift zone that appears to be a developing Divergent boundary....
  • West Antarctic Rift
    West Antarctic Rift

    The West Antarctic Rift is a major, active rift lying between East Antarctica and West Antarctica. It encompasses the Ross Sea, the area under the Ross Ice Shelf and a part of West Antarctica....
  • East Pacific Rise
    East Pacific Rise

    The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate....
  • Pacific-Antarctic Ridge
    Pacific-Antarctic Ridge

    The Pacific-Antarctic Ridge is a divergent tectonics plate boundary located on the seafloor of the South Pacific Ocean, separating the Pacific Plate from the Antarctic Plate....
  • Galapagos Rise
    Galapagos Rise

    The Galapagos Rise is a divergent boundary located between the South American coast and the triple junction of the Nazca Plate, the Cocos Plate, and the Pacific Plate....
  • Gakkel Ridge
    Gakkel Ridge

    The Gakkel Ridge is a mid-oceanic ridge, a divergent tectonics plate boundary between the North American Plate and the Eurasian Plate. It is located in the Arctic Ocean between Greenland and Siberia with a length of about 1,800 kilometers....
  • Explorer Ridge
    Explorer Ridge

    The Explorer Ridge is a mid-ocean ridge, a divergent plate tectonics boundary located about west of Vancouver Island, British Columbia, Canada....


Other plate boundary types

  • Convergent boundary
    Convergent boundary

    In plate tectonics, a convergent boundary or convergent plate boundary, also known as a destructive plate boundary , is an actively deforming region where two tectonic plates or fragments of lithosphere move toward one another and collide....
  • Transform boundary


See also

  • Seafloor spreading
    Seafloor spreading

    Seafloor spreading occurs at mid-ocean ridges, where new oceanic crust is formed through volcano and then gradually moves away from the ridge....
  • Plate tectonics
    Plate tectonics

    Plate tectonics describes the large scale motions of Earth's lithosphere. The theory encompasses the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, understood during the 1960s....
  • Continental drift
    Continental drift

    Continental drift is the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912....
  • Subduction zone