The mixing of sediments and soils by animals or plants, for example, when earthworms turn over a soil; see D. R. Butler (1995). These sediments may be marine, lacustrine, or fluvial, where bed-sediment is engineered by plants and algae (Stazner (2012) Geomorph. 157–8, 49). Bioturbation is significant in downslope soil transport, particularly in soil formation, soil erosion, and soil creep; see Richards et al. (2012) ESPL 36, 9, 1240.