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An escarpment is a steep slope or long cliff that forms as an effect of faulting or erosion and separates two relatively level areas of differing elevations. Usually escarpment is used interchangeably with scarp. Some sources differentiate the two terms, however, where escarpment refers to the margin between two landforms, while scarp is synonymous with a cliff or steep slope. The surface of the steep slope is called a scarp face. This (escarpment) is a ridge which has a gentle (dip) slope on one side and a steep (scarp) slope on the other side.
Formation and description
Scarps are generally formed by one of two processes: either by differential erosion of sedimentary rocks, or by vertical movement of the Earth's crust along a geologic fault. Most commonly, an 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.
More loosely, the term scarp describes the zone between coastal lowlands and continental plateaus which have a marked, abrupt change in elevation caused by coastal erosion at the base of the plateau.
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.
Erosion of escarpments
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. These varying levels of erosion can lead to strange features forming in the exposed rock.
- Elgeyo escarpment (Great Rift Valley)
- God's Window (South Africa)
- Great Escarpment, Southern Africa
- Bandiagara Escarpment (Mali)
- Zambezi Escarpment (Zambia)
- East coast, (Madagascar)
Australia and New Zealand
- New Zealand
- Sweden, Estonia and Russia
- Victoria Lines
- Florida Escarpment, Gulf of Mexico
- Sigsbee Escarpment, Gulf of Mexico
- Canada and the United States
- Pembina Escarpment (Manitoba, North Dakota)
- Niagara Escarpment (Ontario, Illinois, Michigan, New York, and Wisconsin)
- 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
- Devil's Slide (Northern California)
- Allegheny Front (Pennsylvania-Maryland-West Virginia)
- Balcones Fault (Texas)
- Bergen Hill (New Jersey)
- Blue Ridge Escarpment (South Carolina-Georgia)
- Book Cliffs (Utah-Colorado)
- Caprock Escarpment (Texas)
- Catskill Escarpment (New York)
- Cody Scarp (Florida)
- Elkhorn Scarp (San Andreas Fault)
- Helderberg Escarpment (New York)
- Hell's Half Acre (central Wyoming)
- Highland Rim encircling the Nashville Basin (actually a geologic dome) in Middle Tennessee
- Knobstone Escarpment (Southern Indiana)
- Mescalero Ridge (New Mexico)
- Missouri Escarpment (North Dakota)
- Mogollon Rim (Arizona)
- Muldraugh Hill (Kentucky)
- Pine Ridge (Nebraska and South Dakota)
- Pottsville Escarpment (Kentucky-Tennessee; see Cumberland Plateau)
- Sierra Nevada range (eastern slope) in California
- Portage Escarpment (Ohio)
- Potrero Hills in Richmond, California
- The Caribbean
- Easterbrook, D. J. (1999) Surface processes and landforms. (Second Ed). Prentice Hall, Upper Saddle River, New Jersey.
- Summary: Escarpments, US Army Corps of Engineers.