​PLATEAU (a French term, olderplatel, for a flat piece of wood, metal, &c., fromplat, flat), in physical geography, an elevated region of level or gently undulating land-surface, the term being synonymous with “table-land.” The most clearly defined plateaus have steep flanks in contrast with their level summits, but the term does not necessarily connote a steep ascent from the surrounding country. Indeed, it is applied to such diverse forms as the high-lying plains encircled by the higher elevations of the Andes, and to those of the west of North America, which rise almost imperceptibly from the low central plains. A plateau may have its origin either in the upheaval of strata which preserve their original horizontal position during the process, or in the prolonged denudation of an originally broken surface. The two forms are distinguished respectively as Plateaus of Deposition and Plateaus of Erosion.