The unweathered rock which underlies the soil and regolith or which may be exposed at the land surface. Bedrock gouges and cracks are small cracks, gouges, and indentations created on bedrock surfaces. Both chattermarks and crescentic gouges are shallow crescentic furrows: in crescentic gouges the convexity is turned forward in the direction of ice flow, in chattermarks it is turned backwards (Glasser and Bennett (2004) PPG 28, 1). Crescentic cracks are vertical fractures of the rock without the removal of bedrock fragments, with a forward-turned concavity. A bedrock channel cannot substantially widen, lower, or shift its bed without eroding bedrock (Turowski et al. (2008) Geomorph. 99 (1–4), 26. These channels erode through a suite of processes that are poorly understood (A. Goudie and K. J. Gregory 2011), but bedrock may be removed by plucking along pre-existing joints or fractures, by cavitation, abrasion, and dissolution (Whipple et al. (2000) Geol. Soc. Amer. Bull. 112, 490).