Definitions

escarpment

escarpment

[ih-skahrp-muhnt]
escarpment or scarp, long cliff, bluff, or steep slope, caused usually by geologic faulting (see fault) or by erosion of tilted rock layers. An example of a fault scarp is the north face of the San Jacinto Mts. in California. Examples of erosional escarpments include the Palisades along the Hudson River and the long break separating the coastal region from the inland area in Texas, roughly paralleling the coast.
In geomorphology, an escarpment is a transition zone between different physiogeographic provinces that involves a sharp, steep elevation differential, characterized by a cliff or steep slope. Escarpment is generally used interchangeably with scarp (from the Italian scarpa). Some sources will differentiate between an escarpment and scarp. Escarpment then refers to the margin between two landforms, while scarp refers to or is synonymous with a cliff or steep slope. The surface of the steep slope is called a scarp face. 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 fault (faulting).

Most commonly, an escarpment is a transition from one series of sedimentary rocks to another series of a different age and composition. When sedimentary beds are tilted and exposed to the surface, erosion and weathering may occur differentially based on the composition. Less resistant rocks will erode faster, retreating until the point they are overlain by more resistant rock (see cross section schematic). When the dip of the bedding is gentle, a cuesta is formed. Steeper dips (greater than 30-40°) form hogbacks.

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.

Significant escarpments

Africa

Antarctica

Asia

Australia and New Zealand

Europe

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North America

See also

References

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