Afault scarp is a small step-like offset of the ground surface in which one side of afault has shifted vertically in relation to the other.[1][2] Thetopographic expression of fault scarps results from the differential erosion of rocks of contrasting resistance and the displacement of land surface by movement along the fault.[3][4] Differential movement anderosion may occur either along older inactive geologic faults, or recentactive faults.[5][6][7]
Fault scarps often involve zones of highly fractured rock and discontinuities of hard and weak consistencies of rock. Bluffs can form from upthrown blocks and can be very steep, as in the case of Pakistan's coastal cliffs.[8] The height of the scarp formation tends to be defined in terms of the vertical displacement along the fault.[9] Active scarp faults may reflect rapidtectonic displacement[10] and can be caused by any type of fault includingstrike-slip faults.[11] Vertical displacement of ten meters may occur in fault scarps in volcanic bedrock, but is usually the result of multiple episodic movements of 5 to 10 meters per tectonic event.[12][13]
Due to the dramatic uplift along the fault, which exposes its surface, the fault scarp is very prone to erosion. This is especially true if the material being uplifted consists of unconsolidated sediment.[14] Weathering, mass wasting, and water runoff can soon wear down these bluffs, sometimes resulting in V-shaped valleys along runoff channels. Adjacent V-shaped valley formations give the remaining fault spurs a very triangular shape. This formation is known as atriangular facet; however, this landform is not limited to fault scarps.[15]
Fault scarps may vary in size from a few centimeters to many meters.[16]Fault-line scarps are typically formed due to the differential erosion of weaker rocks along a fault. Such erosion, occurring over long time periods, may shift a physicalcliff far from the actual fault location, which may be buried beneath atalus,alluvial fan or filled-in valley sediments. It may therefore be difficult to distinguish between fault scarps and fault-line scarps.[17]
TheTeton Range inWyoming is an example of an active fault scarp. The dramatic topography of the Tetons is due to geologically recent activity on theTeton Fault.[18]
^McCalpin, J.P.; Bruhn, R.L.; Pavlis, T.L; Gutierrez, F.; Guerrero, J.; Lucha, P. (2011). "Antislope scarps, gravitational spreading, and tectonic faulting in the western Yakutat microplate, south coastal Alaska".Geosphere.7 (5):1143–1158.doi:10.1130/GES00594.1.
^Strahler, Arthur N. (1960).Physical Geography (2nd ed.). New York: John Wiley & Sons, Inc. p. 475.
