Curb
6. Brow - line of intersection of the slope surface of a bench (spoil heap tier) with the surface of platforms (upper or lower), respectively called upper and lower brows. The lower brow of the lower bench is called the outline of the pit bottom, the upper brow of the upper bench (line of intersection of the slope of the upper bench with the ground surface) - the pit outline
Source: "Instruction on monitoring deformations of pits, slopes of benches and spoil heaps at quarries and development of measures to ensure their stability" (approved by Gosgortekhnadzor USSR 21.07.1970)