Highwall

The unexcavated face of exposed overburden and coal in a surface mine or in a face or bank on the uphill side of a contour mine excavation.
Found on http://www.coaleducation.org/glossary.htm

Highwall

The unexcavated face of exposed overburden and coal in a surface mine or in a face or bank on the uphill side of a contour mine excavation.
Found on http://www.rocksandminerals.com/glossary.htm
No exact match found