Earth:Escarpment

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Short description: Steep slope or cliff separating two relatively level regions
Escarpment face of a cuesta, broken by a fault, overlooking Trenton, Cloudland Canyon State Park, and Lookout Mountain in the U.S. state of Georgia

An escarpment is a steep slope or long cliff that forms as a result of faulting or erosion and separates two relatively level areas having different elevations.

The terms scarp and scarp face are often used interchangeably with escarpment.[citation needed] Some sources differentiate the two terms, with escarpment referring to the margin between two landforms, and scarp referring to a cliff or a steep slope.[1][2] In this usage an escarpment is a ridge which has a gentle slope on one side and a steep scarp on the other side.

More loosely, the term scarp also describes a zone between a coastal lowland and a continental plateau which shows a marked, abrupt change in elevation[3] caused by coastal erosion at the base of the plateau.

Formation and description

Scarps are generally formed by one of two processes: either by differential erosion of sedimentary rocks, or by movement of the Earth's crust at a geologic fault. The first process is the more common type: the escarpment is a transition from one series of sedimentary rocks to another series of a different age and composition. Escarpments are also frequently formed by faults. When a fault displaces the ground surface so that one side is higher than the other, a fault scarp is created. This can occur in dip-slip faults, or when a strike-slip fault brings a piece of high ground adjacent to an area of lower ground.

Schematic cross section of a cuesta, dip slopes facing left, and harder rocklayers in darker colors than softer ones

Earth is not the only planet where escarpments occur. They are believed to occur on other planets when the crust contracts, as a result of cooling. On other Solar System bodies such as Mercury, Mars, and the Moon, the Latin term rupes is used for an escarpment.

Shaded and colored image from the Shuttle Radar Topography Mission—shows an elevation model of New Zealand's Alpine Fault running about 500 km (300 mi) long. The escarpment is flanked by a chain of hills squeezed between the fault and the mountains of New Zealand's Southern Alps. Northeast is towards the top.

Erosion

When sedimentary beds are tilted and exposed to the surface, erosion and weathering may occur. Escarpments erode gradually and over geological time. The mélange tendencies of escarpments results in varying contacts between a multitude of rock types. These different rock types weather at different speeds, according to Goldich dissolution series so different stages of deformation can often be seen in the layers where the escarpments have been exposed to the elements.

Significant escarpments

Africa

  • Elgeyo escarpment (Great Rift Valley)
  • Great Escarpment, Southern Africa
    • Including the Drakensberg and God's Window in Mpumalanga's Eastern Escarpment
  • Bandiagara Escarpment (Mali)
  • Zambezi Escarpment (Zambia)
  • East coast, Madagascar

Antarctica

  • Usas Escarpment

Asia

  • Alam-Kuh, Iran
  • Sharon Escarpment, Israel
  • Tuwaiq, Saudi Arabia
  • Vindhya Range, India
  • Western Ghats, India
  • Wulian Feng, China

Australia and New Zealand

  • Australia
  • New Zealand
    • The western slope of the Southern Alps (along the Alpine Fault)
    • The Kaimai escarpment, above the Hauraki Plains
    • The Paekakariki escarpment between Paekakariki and Pukerua Bay (with State Highway 59 and the North Island Main Trunk).

Europe

  • England
    • Cotswold escarpment
    • Chiltern escarpment
    • North Downs
    • South Downs
    • A common placename denominating an escarpment in England is "edge" as in
      • Alderley Edge
      • Edge Hill famous as the place of the first battle of the English Civil War
      • Kinver Edge
      • The Lincoln Edge
      • Stanage Edge
      • Wenlock Edge
  • Scotland
    • Quiraing, Trotternish, Isle of Skye
  • Wales
    • Eglwyseg
    • Black Mountain (range)
    • Black Mountains, Wales
    • Pen y Fan
  • France
    • La Côte d'Or is famous for its wines and has given its name to a département, Côte-d'Or.
    • Le Pays de Bray, a clay vale enclosed by chalk escarpments.
  • Sweden, Estonia and Russia
  • Malta
    • Victoria Lines
The Sierra Escarpment in California

North America

At the Florida Escarpment, seen in the eastern Gulf of Mexico, the sea bed drops precipitously from less than 300 to 3,000 m (1,000 to 10,000 ft) over a short distance.
  • Atlantic Seaboard Fall Line
  • Florida Escarpment, Gulf of Mexico
  • Sigsbee Escarpment, Gulf of Mexico
  • Canada and the United States
    • Manitoba Escarpment (Manitoba, Saskatchewan)
    • Pembina Escarpment (Manitoba, North Dakota)
    • Niagara Escarpment (east to west: New York, Ontario, Michigan, Wisconsin, and Illinois)
    • Eardley Escarpment (Mattawa Fault, Gatineau Park, Quebec)
    • Onondaga (geological formation) (Ontario and New York)
    • Devil's Rock (Lake Temiskaming, Ontario)
    • Scarborough Bluffs (Toronto, Ontario)
  • United States
    • Allegheny Front (West Virginia-Maryland-Pennsylvania)
    • Blue Ridge Escarpment (North Carolina–Virginia)
    • Balcones Fault (Texas )
    • Bergen Hill (New Jersey)
    • Black River Escarpment (Wisconsin)
    • Book Cliffs (Colorado–Utah)
    • Caprock Escarpment (Texas )
    • Catskill Escarpment (New York)
    • The Chinese Wall (Montana)
    • Cody Scarp (Florida)
    • Devil's Slide (California )
    • Helderberg Escarpment (New York)
    • Hell's Half Acre (Wyoming)
    • Knobstone Escarpment (Indiana )
    • Lewiston Hill (Idaho-Washington)
    • Magnesian Escarpment (Wisconsin)
    • Mescalero Ridge (New Mexico)
    • Missouri Escarpment (North Dakota)
    • Mogollon Rim (Arizona)
    • Muldraugh Hill (Kentucky)
    • Pine Ridge (Nebraska–South Dakota)
    • Portage Escarpment (Ohio)
    • Potrero Hills in (California )
    • Pottsville Escarpment (Kentucky–Tennessee )
    • The Rimrocks (Montana)
    • Sierra Nevada eastern slope (California )
  • The Caribbean
    • Bahamas Escarpment (Bahamas)

South America

See also

References

  1. ↑ Easterbrook, Don J. (1999). Surface Processes and Landforms. Prentice Hall. ISBN 978-0-13-860958-0. [page needed]
  2. ↑ Summary: Escarpments, US Army Corps of Engineers.
  3. ↑ "Scarps and Terraces". Radford University. https://www.radford.edu/jtso/GeologyofVirginia/CoastalPlain/CPPhysio-16.html. 
  4. ↑ Lidmar-Bergström, Karna (1988). "Denudation surfaces of a shield area in southern Sweden". Geografiska Annaler 70 A (4): 337–350. doi:10.2307/521267. 
  5. ↑ Wörner, Gerhard; Uhlig, Dieter; Kohler, Ingrid; Seyfried, Hartmut (15 February 2002). "Evolution of the West Andean Escarpment at 18°S (N. Chile) during the last 25 Ma: uplift, erosion and collapse through time". Tectonophysics 345 (1): 183–198. doi:10.1016/S0040-1951(01)00212-8. Bibcode: 2002Tectp.345..183W. 



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