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Encyclopedia > Rift valley
African Rift Valley. From left to right: Lake Upemba, Lake Mweru, Lake Tanganyika (largest), and Lake Rukwa.
African Rift Valley. From left to right: Lake Upemba, Lake Mweru, Lake Tanganyika (largest), and Lake Rukwa.
A rift valley near Quilotoa, Ecuador.
A rift valley near Quilotoa, Ecuador.

A rift valley in geology is a valley created by the formation of a rift. The Great Rift Valley, located in the Middle East and Africa, is the most famous of the world's rift valleys. Rift valleys are produced by tensional tectonic forces which occur at divergent plate boundaries. Rift valleys typically appear as a downdropped graben between a pair of faults, or vertical Earth movements. Rift valleys are often deep and flanked by volcanoes. The margins of rifts are commonly uplifted, so that the downfaulting of the rift floor is associated with the uplift of both margins. Which of these two processes initiates the composite rifting penomenon is still debated, but their co-occurrence is common. Where the extension that generates rifting is not normal to the rift axis but is somewhat oblique, a series of basins may develop along the axial zone, then, as extension continues, the basins merge to form the rift. Such basins are commonplace in the central and northern Red Sea, as well as other rifts. This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Northern section of the Great Rift Valley. ... Lake Mweru is a lake located on the border between Zambia and Democratic Republic of the Congo, about 150 km west of the southern end of Lake Tanganyika. ... Lake Tanganyika is a large lake in central Africa (3° 20 to 8° 48 South and from 29° 5 to 31° 15 East). ... Lake Rukwa is a lake in southwestern Tanzania. ... Image File history File linksMetadata Size of this preview: 800 × 343 pixelsFull resolution (1600 × 686 pixel, file size: 152 KB, MIME type: image/jpeg) I shot this photo in Ecuador, on the road between Zumbahua and Laguna Quilotoa. ... Image File history File linksMetadata Size of this preview: 800 × 343 pixelsFull resolution (1600 × 686 pixel, file size: 152 KB, MIME type: image/jpeg) I shot this photo in Ecuador, on the road between Zumbahua and Laguna Quilotoa. ... Quilotoa (key-low-TOE-ah) is a water-filled caldera and the westernmost volcano in the Ecuadorian Andes. ... This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... Fljótsdalur in East Iceland, a rather flat valley In geology, a valley (also called a vale or dale) is a depression with predominant extent in one direction. ... It has been suggested that this article or section be merged with Rift valley. ... Northern section of the Great Rift Valley. ... A map showing countries commonly considered to be part of the Middle East The Middle East is a region comprising the lands around the southern and eastern parts of the Mediterranean Sea, a territory that extends from the eastern Mediterranean Sea to the Persian Gulf. ... A world map showing the continent of Africa Africa is the worlds second-largest and second most-populous continent, after Asia. ... The tectonic plates of the world were mapped in the second half of the 20th century. ... USGS image A graben is a depressed block of land bordered by parallel faults. ... Old fault exposed by roadcut near Harrisburg, Pennsylvania. ... Cleveland Volcano in the Aleutian Islands of Alaska photographed from the International Space Station For other uses, see Volcano (disambiguation). ...


The most extensive rift valley is located along the crest of the mid-ocean ridge system and is the result of seafloor spreading. Existing continental rift valleys are usually the result of a failed arm (aulacogen) of a triple junction. Examples besides the Great Rift Valley include the Mississippi embayment and the Rio Grande Rift in North America. Oceanic Ridge Oceanic crust is formed at an oceanic ridge, while the lithosphere is subducted back into the asthenosphere at trenches. ... Age of oceanic crust. ... In geology, an aulacogen is a failed arm of a triple junction of a plate tectonics rift system. ... A triple junction is the point where three tectonic plates diverge. ... Northern section of the Great Rift Valley. ... This article may be too technical for most readers to understand. ... The Rio Grande Rift is a rift valley extending north from Mexico, near El Paso, Texas through New Mexico into central Colorado. ... North America North America is a continent [1] in the Earths northern hemisphere and (chiefly) western hemisphere. ...


The largest freshwater lakes in the world are all located in rift valleys.[1] Lake Baikal in Siberia, a World Heritage Site,[2], lies in an active rift valley. Baikal is both the deepest lake in the world and, with 20% of all of the liquid freshwater on earth, has the greatest volume.[3] Lake Tanganyika, second by both measures, is in the Albertine Rift, the westernmost arm of the active Great Rift Valley of East Africa and Southwest Asia. Lake Superior in North America, the largest freshwater lake by area, lies in the ancient and dormant Midcontinent Rift. Baikal redirects here. ... This article is about Siberia as a whole. ... A UNESCO World Heritage Site is a specific site (such as a forest, mountain, lake, desert, monument, building, complex, or city) that has been nominated and confirmed for inclusion on the list maintained by the international World Heritage Programme administered by the UNESCO World Heritage Committee, composed of 21 State... Lake Tanganyika is a large lake in central Africa (3° 20 to 8° 48 South and from 29° 5 to 31° 15 East). ... Northern section of the Great Rift Valley. ...  Eastern Africa (UN subregion)  East African Community  Central African Federation (defunct)  geographic, including above East Africa or Eastern Africa is the easternmost region of the African continent, variably defined by geography or geopolitics. ...  Southwest Asia in most contexts. ... For the the Quebec municipality, see Lac-Supérieur. ... North America North America is a continent [1] in the Earths northern hemisphere and (chiefly) western hemisphere. ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... For other uses, see Lake (disambiguation). ... Geological map of North America showing (in white) the Midcontinent Rift, here labeled Keweenawan Rift. ...


Notes

  1. ^ The World's Greatest Lakes. Retrieved on 2007-01-07.
  2. ^ Lake Baikal - World Heritage Site. World Heritage. Retrieved on 2007-01-13.
  3. ^ The Oddities of Lake Baikal. Alaska Science Forum. Retrieved on 2007-01-07.
  • Bonatti, E., 1985. Punctiform initiation of seafloor spreading in the Red Sea during transition from a continental to an oceanic rift. Nature, 316: 33-37.
  • Mart, Y., Dauteuil, O., 2000. Analogue experiments of propagation of oblique rifts. Tectonophysics, 316: 121-132.

  Results from FactBites:
 
Great Rift Valley - Academic Kids (669 words)
The Gulf of Aden is an eastward continuation of the rift - before the rift opened, the Arabian Peninsula was attached to the Horn of Africa - and from this point the rift continues as part of the Mid-oceanic ridge of the Indian Ocean.
In Kenya the valley is deepest to the north of Nairobi.
As the lakes in the Eastern Rift have no outlet to the sea, these lakes tend to be shallow and have a high mineral content as the evaporation of water leaves the salts behind.
Rift valley Summary (920 words)
Rifts commence as intracratonic, down-thrown blocks dominated by normal or oblique-extensional (transtensional) faults (e.g., the Rhine Graben in Germany and the East African Rift).
Rift valleys typically appear as a downdropped graben between a pair of faults, or vertical Earth movements.
Rift valleys are often associated with and flanked by volcanoes.
  More results at FactBites »

 
 

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