The mixture of soil and unconsolidated rock fragments deposited on, or at the foot of, a slope. See Coe et al. (2008) Geomorph. 96, 3–4 on colluvium and debris flows. Colluvial boulder deposits are relatively stable colluvium, consisting of linear fields of well-varnished hillslope boulders, ubiquitous on desert hillslopes (Liu and Broecker (2008) Geomorph. 93, 3–4).