Within a permafrost zone, the layer of unfrozen ground that lies between the permafrost and the seasonally thawed active layer. Talik most often occurs below rivers and lakes, or where groundwater upwelling occurs along fractures (Delisle (1998) J. Quat. Scis 13). See Grosse et al. (2007) Geomorph. 86, 1–2. For the role of talik in the formation of pingoes, see Gurney (1998) PPG 22, 3.