The rock and subsoil that lies above a mineral deposit such as a coal seam.
A sterile stratum that lies above the stratum being investigated
To overload or overtax.
Subsidence below ground in a mine, which can cause the ground level above to drop.
A potential, unsuspected, hidden problem, hazard, or danger that is easily encountered but not immediately obvious.
A type of trap consisting of a concealed pit in the ground, which the victim is supposed to fall into and not be able to get out from.
An antipattern.