Escarpment

In geology, an escarpment is a transition zone between different physiogeographic provinces that involves an elevation differential, often involving high cliffs. Most commonly, an escarpment, also called a scarp (from the German word scharf meaning sharp), is a transition from one series of sedimentary rocks to another series of a different age and composition. In such cases, the escarpment usually represents the line of erosional loss of the newer rock over the older (see also Cuesta).

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

Escarpment face of a cuesta, broken by a fault. Cumberland Plateau, Tennessee.

Escarpments are also frequently formed by faults. These are called fault scarps. In some cases land may be lifted to an elevation above the surrounding area by a thrust fault, or the reverse with a normal fault. A strike-slip fault may bring a piece of high ground adjacent to an area of lower ground. The latter is common in California along the San Andreas fault and the many other strike-slip faults in the area.

In England escarpments are found in a diagonal line across the country from the Yorkshire coast on the North Sea to the Hampshire coast on the English Channel. There the features of an escarpment include the scarp slope (the leading edge); the dip slope, dry valleys, coombes (both found in chalk downland), and clay vales occur on the side away from the scarp.

There are escarpments on other planets besides Earth. They are believed to be created when the crust contracts; as a result of cooling.

More loosely the term is used to describe the zone between coastal lowlands and continental plateau which have a marked change in altitude.

Map of the Alpine Fault escarpment, beside New Zealand's Southern Alps. About 500 km (300 mi) long.

Significant escarpments

* Africa
**God's Window (South Africa)
**Bandiagara Escarpment (Mali)
* Australia
**Darling Scarp
*Canada and the United States
**Niagara Escarpment (Ontario, Wisconsin, Michigan, and New York)
**Onondaga (geological formation) (Ontario and New York)
*England (significant within England!)
**Cotswold escarpment
**North Downs
**South Downs
**A colloquial adjective to describe escarpments 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
***Wenlock Edge
*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.
*New Zealand
**Southern Alps (western slope, along the Alpine Fault)
*United States
**Allegheny Front (Pennsylvania-Maryland-West Virginia)
**Catskill Escarpment (New York)
**Cody Scarp (Florida)
**Pottsville Escarpment (Kentucky-Tennessee; see Cumberland Plateau)
**Highland Rim encircling the Nashville Basin (actually a geologic dome) in Middle Tennessee
**Missouri Escarpment (North Dakota)
**Muldraugh Hill (Kentucky)
**Balcones Fault (Texas)
**Mogollon Rim (Arizona)
**Sierra Nevada range (eastern slope) in California.

The Sierra Escarpment in California.

See also

* List of scarps on Mercury