escarpment

A long, continuous cliff or steep slope separating two relatively level surfaces — one high, one low. Escarpments form where resistant rock overlies weaker rock and erosion has retreated the face, or along fault lines where one side has been lifted. The Niagara Escarpment, the Caprock Escarpment of the Texas Panhandle, the Great Escarpment of southern Africa. An escarpment is the edge of a world — the place where one landscape drops away and another begins.