A slope which declines in steepness with movement downslope, also known as a waning slope. Claessens et al. (2007) Geomorph. 74, 1–4 find that steep concave slopes are one of the main factors responsible for landslides in Uganda. Most often, the concave element of a slope occurs as a basal concavity. Where the scarp is not being undercut, the base and the crest make straight-line intersections with the mid-section to form a sharp basal concavity and crestal convexity (Nash and Beaujon (2006) Geomorph. 75, 3–4). The basal concavity is poorly developed in humid temperate environments (J. Gerrard 1988).