Gelisols are young soils with little profile development. Cold temperatures and frozen conditions for much of the year slow the process of soil formation. The principal defining feature of these soils is the presence of a permafrost layer(see Plates 5 and 14).Permafrost is a layer of material that remains at temperatures below 0℃ for more than two consecutive years. It may be a hard, ice-cemented layer of soil material(e.g., designed Cfm in profile descriptions), or, if dry, it may be uncemented(e.g., designated Cff). In Gelisols, the permafrost layer lies within 100 cm of the soil surface, unless cryoturbation is evident within the upper 100 cm, in which case the permafrost may begin as deep as 200 cm from the soil surface.