Plateau

Learn how basaltic rock composing the Columbia Plateau was once lava, from a series of volcanic fissure eruptionsSee all videos for this article

plateau, extensive area of flat upland usually bounded by an escarpment (i.e., steep slope) on all sides but sometimes enclosed by mountains. The essential criteria for plateaus are low relative relief and some altitude.

Although plateaus stand at higher elevation than surrounding terrain, they differ from mountain ranges in that they are remarkably flat. Some plateaus, like the Altiplano in southern Peru and western Bolivia, are integral parts of mountain belts. Others, such as the Colorado Plateau (across which the Colorado River has cut the Grand Canyon), were produced by processes very different from those that built neighbouring mountain ranges. Some plateaus—for example, the Deccan plateau of central India—occur far from mountain ranges. The differences among plateaus can be ascribed to the different geologic processes that have created them.