The vertical height of a quarry or opencast face from top to toe; i.e., the height of overburden and coal, ore, or stone. A face height is chosen that can be reached by the excavator so that all scaling of loose material can be accomplished by the machine, thus eliminating the necessity for workers to go over the face on ropes to bar off loose ground. Where the height exceeds this figure, a form of benching may be adopted.