Periglacial landforms | Cryoturbation structures

Different types of cryoturbation (sedimentary deformations of cryogenic origin) are distinguished, interpreted in terms of mechanisms of formation and linked to their specific environmental conditions. Cryoturbations may originate from gravitational loading in the thawing soil (‘periglacial loading’), from hydrostatic pressure between frozen parts of the subsoil (‘cryohydrostatic pressure’), or from pressures due to differential frost penetration (‘cryostatic heave’). The first, and most common, process requires a reversed density gradient and conditions of liquefaction that are only possible during the degradation of the underlying frozen subsoil. The other two processes occur during the freezing process. Only large-amplitude deformations due to periglacial loading are indicative of the existence of perennially frozen ground and are therefore important paleoclimatic proxy indicators. All other cryoturbation types do not necessarily require permafrost conditions, but deep seasonal frost or repeated frost-thaw alternations may be sufficient.