A hoodoo, sometimes called a fairy chimney, is a tall spire or column of rock that stands above the bottom of an arid drainage basin or badland. Hoodoo columns are composed of soft sedimentary rock that are topped by a capstone of harder, less easily-eroded stone that protects the column from erosion and the elements during its formation.

Formerly a subsurface sedimentary layer, a hoodoo is formed when surrounding sediments are slowly eroded away over great lengths of time in geologically stable areas.
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