Rift
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[[Image:Horst graben.jpg|right|frame|[[USGS]] image]]
[[Image:Plates tect2 en.svg|thumb|Plates in the crust of the earth, according to the [[plate tectonics]] theory]]
In [[geology]], a '''rift''' is a place where the [[Earth]]'s [[Crust (geology)|crust]] and [[lithosphere]] are being pulled apart<ref>http://www.mantleplumes.org/VM_DecompressMelt.html Decompressional Melting During Extension of Continental Lithosphere</ref> and are examples of [[extensional tectonics]].<ref>http://www.le.ac.uk/geology/art/gl209/lecture4/lecture4.html Plate Tectonics: Lecture 2</ref>
Typical rift features are a central linear downdropped [[geologic fault|fault]] segment, called a [[graben]], with parallel normal faulting and rift-flank uplifts on either side forming a [[rift valley]], where the rift remains above sea level. The axis of the rift area commonly contains [[volcanic rocks]] and active [[volcanism]] is a part of many, but not all active rift systems.
Most rifts occur along the central axis of a [[mid-ocean ridge]], where new [[oceanic crust]] and lithosphere is created along a [[divergent boundary]] between two [[tectonic plate]]s.
Failed rifts are where continental rifting began, but then failed to continue to the point of break-up. Typically the transition from rifting to spreading develops at a [[triple junction]] where three converging rifts meet over a [[Hotspot (geology)|hotspot]]. Two of these evolve to the point of seafloor spreading, while the third ultimately fails, becoming an [[aulacogen]].
==Examples==
* The [[East African Rift]]
* The [[Red Sea Rift]]
* The [[Baikal Rift Zone]], the bottom of [[Lake Baikal]] is the deepest continental rift on the earth.
* The [[Gulf of Suez Rift]]
* [[Lake Timiskaming]] in [[Temiskaming Shores]], [[Ontario]]
* Throughout the [[Basin and Range Province]] in [[North America]]
* The [[Rio Grande Rift]] in the southwestern US
* The rift zone that contains the [[Gulf of Corinth]] in [[Greece]]
* The [[Reelfoot Rift]], an ancient buried failed rift underlying the [[New Madrid Seismic Zone]] in the [[Mississippi embayment]]
* The [[Rhine Rift]], in south western Germany, known as the [[Upper Rhine valley]]
* The [[Taupo Volcanic Zone]] in the north east [[North Island]] of [[New Zealand]]
* The [[Oslo Graben]] in [[Norway]]
* The [[Ottawa-Bonnechere Graben]] in Ontario and Quebec
* The [[Northern Cordilleran Volcanic Province]] in [[British Columbia]], [[Yukon]] and [[Alaska]]
* The [[West Antarctic Rift]] in [[Antarctica]]
* The [[Midcontinent Rift System]], a late [[Precambrian]] rift in central North America
==References==
{{Commonscat}}
{{Reflist}}
[[Category:Structural geology]]
[[Category:Plate tectonics]]
[[Category:Rift valleys]]
[[als:Grabenbruch]]
[[cs:Rift]]
[[de:Grabenbruch]]
[[es:Zona rift]]
[[fr:Rift]]
[[it:Rift]]
[[nl:Rift]]
[[pl:Ryft]]
[[pt:Rifte]]
[[ru:Рифт]]
[[sk:Rift]]
[[fi:Hautavajoama]]
[[sv:Gravsänka]]
[[uk:Рифтогенез]]