Bench: a flat section in steep terrain. Characteristically narrow, flat or gently sloping with steep or vertical slopes on either side. A bench can be formed by various geological processes. Natural erosion of a landscape often results in a bench being formed out of a hard strip of rock edged by softer, sedimentary rock. The softer rock erodes over time, leaving a narrow strip of rock resulting in a bench. Coastal benches form out of continuous wave erosion of a coastline.