mesa, in geology

mesa māˈsə [key] [Span.,=table], name given in the SW United States to a small, isolated tableland or a flat-topped hill. Two or more of the sides are steep and usually perpendicular and some have all four sides practically perpendicular. Their bold lines make them a picturesque part of the landscape, and they are frequently deep red or yellow in color. Mesas originate from the erosion of plateaus that were capped by hard rock, usually in arid regions. Cliffs form, retreating as the soft layers beneath the cap rock are eroded. As the soft rock wears away, the upper cliff breaks along cracks and eventually produces a mesa. A butte is the last stage of the sequence, before the feature's complete consumption by erosion. The strata, or layers of rock, in a mesa are horizontal, or nearly so. The many “table mountains” are mesas. Two celebrated mesas are the Mesa Verde in Colorado and the Enchanted Mesa (Mesa Encantada) in New Mexico.

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