Editing Horst and graben

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{{Short description|Topography consisting of alternating raised and lowered fault blocks}} 
[[Image:Fault-Horst-Graben.svg|right|thumb|upright=1.35|Diagram of horsts and grabens]]

In [[geology]], '''horst and graben''' (or '''range and valley''') refers to topography consisting of alternating raised and lowered [[fault block]]s known as [[Horst (geology)|horst]]s and [[graben]]s. The features are created by [[Normal fault|normal faulting]] and [[rifting]] caused by [[Extensional tectonics|crustal extension]].<ref name=":0">{{Cite web|date=2020-04-22|title=Horst and Graben|url=https://www.nps.gov/articles/horst-and-graben.htm|website=[[National Park Service]]}}</ref> Horst and graben are formed when normal faults of opposite [[Strike and dip|dip]] occur in pairs with parallel [[Strike and dip|strike]], and are always formed together. Each feature can range in size from a few centimeters up to tens of kilometers, and the vertical displacement can be up to several thousand meters. The movement on either side of each block is typically equal, resulting in little tilting.<ref name=":1">{{Cite web|title=horst and graben|url=https://www.britannica.com/science/horst|access-date=|website=[[Encyclopædia Britannica]]|language=en}}</ref>

== Features ==

=== Horst ===
{{Main|Horst (geology)}}
A horst is a section of crust that has been lifted relative to the blocks on either side, which is a result of its bounding faults [[Strike and dip|dipping]] away from each other.<ref name=":1" /> Horsts can form features such as plateaus, mountain ranges or ridges on either side of the valleys.<ref name=":0" />

=== Graben ===
{{Main|Graben}}
A graben is a section of crust that has lowered relative to the blocks on either side, which is a result of its bounding faults [[Strike and dip|dipping]] towards each other.<ref name=":1" /> The plural of graben can be either graben or grabens. Graben form low-lying features such as basins and rift valleys.<ref name=":0" /><ref name=":1" /> They can be very long relative to their width.

== Examples ==

* The [[Basin and Range Province]] in the western United States is an extensive region of alternating valleys and ridges caused by horst and graben as well as [[tilted block faulting]].<ref name=":0" />

* The [[Condroz]] and [[Ardennes]] regions of [[Wallonia]] are good examples of a succession of horst and graben.

* The [[Satpura Range]] is a horst in India and is flanked by [[Narmada River|Narmada]] Graben in the north and much smaller but parallel [[Tapti River|Tapi]] Graben in the south.<ref>{{Cite book|url=https://books.google.com/books?id=BtsLCwAAQBAJ&dq=satpura+horst&pg=PA766|title=The Making of India: Geodynamic Evolution|last=Valdiya|first=K. S.|date=2015-11-26|publisher=Springer|isbn=9783319250298|language=en}}</ref><ref>{{Cite book|date=2017-01-01|chapter=Satpura Horst and Narmada–Tapi Grabens|language=en|volume=22|pages=237–247|doi=10.1016/B978-0-444-63971-4.00010-4|issn=0928-2025|title=Neotectonism in the Indian Subcontinent - Landscape Evolution|series=Developments in Earth Surface Processes|last1=Valdiya|first1=K.S.|last2=Sanwal|first2=Jaishri|isbn=9780444639714}}</ref><!-- add more examples, turn into a table -->

==See also==
* [[Rift (geology)]]
*[[Half-graben]]
*[[Basin and range topography]]

== References ==
{{Reflist}}

{{Structural geology}}

[[Category:Structural geology]]


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