tongues of mineral and organic horizons, organic and mineral intrusions and oriented rock fragments. Organic matter is accumulated on top of the permafrost and ice or sand wedges are a common features. Turbels occur primarily in the zone of continuous permafrost. Orthels: soils that show little or no cryoturbation (less than one-third of the depth of the active layer). Patterned ground (except for polygons) generally is lacking. Orthels occur primarily within the zone of discontinuous permafrost, and in alpine areas. See also Active layer Pedogenesis Pedology (soil study) Soil classification References Soil Survey Staff: Keys to Soil Taxonomy. 12th edition. Natural Resources Conservation Service. U.S. Department of Agriculture. Washington D.C., USA, 2014. Further reading W. Zech, P. Schad, G. Hintermaier-Erhard: Soils of the World. Springer, Berlin 2022, Chapter 2.3.1. External links profile photos (with classification) WRB homepage profile photos (with classification) IUSS World of Soils Pedology Types of soil Geography of the Arctic Permafrost