Overburden

In mining, overburden (also called waste or spoil) is the material that lies above an area that lends itself to economical exploitation, such as the rock, soil, and ecosystem that lies above a coal seam or ore body. Overburden is distinct from tailings, the material that remains after economically valuable components have been extracted from the generally finely milled ore. Overburden is removed during surface mining, but is typically not contaminated with toxic components and may be used to restore an exhausted mining site to a semblance of its appearance before mining began.

A related term is interburden, meaning material that lies between two areas of economic interest, such as the material separating coal seams within strata.

Analogous uses

Overburden may also be used as a term to describe all soil and ancillary material above the bedrock horizon in a given area.

By analogy, overburden is also used to describe the soil and other material that lies above a specific geologic feature, such as a buried astrobleme, or above an unexcavated site of archeological interest.