scarp

A scarp is a steep slope or cliff produced by differential erosion, structural displacement, or human excavation. In geology and geomorphology, scarps are the steep faces at the boundary between rock units of different resistance or along fault lines. A related term, escarpment, denotes a long, continuous cliff or slope that marks such a boundary over a larger scale.

Scarps formed by faulting are called fault scarps; they occur where vertical movement along a fault raises or lowers a block relative to its neighbor, creating an exposed steep face. Scarps can also arise where erosion or weathering wears away softer rock more rapidly than harder rock, leaving a pronounced step or cliff in the landscape. Over geologic time, scarps may retreat or migrate as erosion continues.

In military architecture, the term scarp refers to the inner face of a ditch or moat facing the interior of a fortification; it is usually steep or vertical, with the outer ditch face called the counterscarp. The word also appears in archaeology and geomorphology to denote a vertical or near-vertical surface cut into sediment or soil, such as the face exposed by excavation or terrace formation.

Scarps can be found in many landscapes, including faulted mountain fronts, riverbanks where the bank is undercut, and coastal cliffs where wave action undercuts a shoreline. They are important for understanding tectonics, erosion processes, and landscape evolution.