Fault scarp
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A fault scarp is a steep terrain slope or an apparent step in the ground.
It can be caused by differential erosion along an old inactive fault (a sort of old rupture) with hard & weak rock, or by an active geologic fault.
Active scarps are usually formed by tectonics, e.g. when an earthquake changes the elevation of the ground, and can be caused by any type of fault, including strike-slip faults, whose motion is primarily horizontal.
Fault scarps may be only a few centimeters or many meters high. Fault-line scarps are coincident with faults, but are most typically formed by the erosion of weaker rocks that have been brought alongside more resistant ones by the fault's movements. In the case of old eroded fault scarps, active erosion may have moved the physical cliff back away from the actual fault location which may be buried beneath a talus (fan) or the valley fill.
The Teton Range in Wyoming is an example of an inactive fault scarp. The Hurricane Cliffs, west of Zion National Park in Utah is a prominent example of a fault scarp along an old essentially inactive fault. Other examples include the scarps bounding the East African Rift Valley and the Rio Grande Rift in New Mexico.
In other parts of the world, many fault scarps in the Eastern and Western Alps should be mentioned, or a famous one in New Zealand. It can be seen at Maruia Falls on the Shenandoah Highway (State Hwy 65), South Island. The 1929 Murchison Earthquake raised the upstream side by about four metres thereby creating a fault scarp and as a result also, a waterfall.
See also: embankment, steepening, valley shoulder.
