A hoodoo (also called a tent rock, fairy chimney, or earth pyramid) is a tall, thin spire of rock formed by erosion. Hoodoos typically consist of relatively soft rock topped by harder, less easily eroded stone that protects each column from the elements. They generally form within sedimentary rock and volcanic rock formations.

Hoodoos range in size from the height of an average human to heights exceeding a 10-story building. Hoodoo shapes are affected by the erosional patterns of alternating hard and softer rock layers. Minerals deposited within different rock types can cause hoodoos to have different colors throughout their height.