tor A high, isolated crag, pinnacle, or rocky peak; or a pile of rocks, much-jointed and usually granitic, exposed to intense weathering, and often assuming peculiar or fantastic shapes, e.g. the granite rocks standing as prominent masses on the moors of Devon and Cornwall, England. Linton (1955) suggested that a tor is a residual mass of bedrock resulting from subsurface rotting through the action of acidic groundwater penetrating along joint systems, followed by mechanical stripping of loose material. Periglacial processes may also be important in the formation of tors. Etymol: Celtic(?). Cf: core-stone; elephant rock.
Neuendorf, Klaus. Glossary of Geology, Fifth Edition, Revised . American Geosciences Institute. Kindle Edition.