Three views of slope: (a) cross-section, (b) overhead/landscape view (dashed lines indicate the path of surface water flow), and (c) emphasizing how the shape of the slope can influence drainage (arrows indicate direction of water flow).

Relief, or topography, describes the shape, slope, and elevation of the land. Relief has an effect on soil formation through soil wetness, soil temperature, and the erosion rate. The topography of an area can mitigate or enhance weathering caused by climatic factors. It is also responsible for the external drainage condition of a soil or location. Soils on steep slopes or summits tend to be drier than in flatter areas because of increased runoff. Soils in low-lying areas or flat slopes tend to be wetter since there is little runoff and more water accumulation from upland areas.
Steep slopes have thinner A horizons and overall less soil development. Erosion tends to prevent accumulation of A materials because soil particles are washed away quickly. On gentle slopes with less erosion or removal, thicker A horizons are common. At the “foot” and “toe” of a slope, A horizons tend to be thicker because of deposition from upland areas.