An upstanding mass of rocks or boulders which rises above the gentler slopes which surround it. Tors were probably formed as a result of deep weathering and stripping in preglacial times, with additional sediment removal by mass movement under periglacial conditions in interglacial and interstadial times (Stroeven et al. (2002) Geomorph. 44, 1–2; see also Hätterstrand and Stroeven in the same issue). See Knight (1987) U. Aberdeen, Dept. Geog., discuss. paper 9, on structural controls on tor location.