Overburden

Origin

From - + burden.

Full definition of overburden

Verb

1. To overload or overtax

Noun

1. (geology) The rock and subsoil that lies above a mineral deposit such as a coal seam.
• 2004, Richard Fortey, The Earth, Folio Society 2011, p. 163:Such rocks have been changed by baking in a terrestrial pressure-cooker. Then they have been disinterred: kilometres of overburden must have been removed.
2. (archaeology) A sterile stratum that lies above the stratum being investigated