Histosols that are primarily made up of only slightly decomposed organic materials, often called peat. Hemists – Histosols that are primarily made up of moderately decomposed organic materials. Saprists – Histosols that are primarily made up of highly decomposed organic materials, often called muck. Wassists - Histosols that have a field observable water table 2 cm or more above the soil surface for more than 21 hours of each day in all years. See also Acid sulfate soil Hydric soil Pedogenesis Pedology (soil study) Soil classification Soil type References IUSS Working Group WRB: World Reference Base for Soil Resources, fourth edition. International Union of Soil Sciences, Vienna 2022. (). Further reading W. Zech, P. Schad, G. Hintermaier-Erhard: Soils of the World. Springer, Berlin 2022, Chapter 3.3.1. External links profile photos (with classification) WRB homepage profile photos (with classification) IUSS World of Soils Pedology Types of soil