A saucer-, cup-, or trough-shaped depression or hollow formed by deflation on a pre-existing sand deposit. The adjoining accumulation of sand, the depositional lobe, derived from the depression, and possibly other sources, is normally considered part of the blow-out (Hesp (2002) Geomorph. 48, 1–3). Blow-outs usually result from the removal of vegetation; see Dech et al. (2005) Catena 60, 2.