The effects of snow on a landscape. The main processes are backwall failure, sliding and flow, niveo-aeolian sediment transport, supra- and ennival-sediment flows, niveo-fluvial erosion, development of pronival stone pavements, accumulation of alluvial fans and basins, and pronival solifluction (Christiansen (1998) ESPL 23, 8). For the factors influencing the effects of nivation, see Raczkowska (1995) Geograf. Annal. A 77, 4. Nivation may produce the shallow pits known as nivation hollows. In time, these hollows may trap more snow and may deepen further with more nivation so that cirques or thermocirques are formed; see Kariya (2005) Catena 62, 1.