Gelisols

{
  "id": "MLC-T-ENV-012139",
  "term": "Gelisols",
  "field": "Environment",
  "definition": "The central concept of Gelisols is that of soils with gelic materials underlain by permafrost. Freezing and thawing are important processes in Gelisols. Diagnostic horizons may or may not be present. Permafrost influences pedogenesis by acting as a barrier to the downward movement of the soil solution. Cryoturbation (frost mixing) is an important process in many Gelisols and results in irregular or broken horizons, involutions, organic matter accumulation on the permafrost table, oriented rock fragments, and silt caps on rock fragments. Cryoturbation occurs when two freezing fronts, one from the surface and the other from the permafrost, merge during freeze-back in the autumn. Ice segregation is an important property of gelic materials and occurs when the soil solution migrates toward ice, increasing the volume of ice. Volume changes also occur as the water freezesDiagnostic horizons, including ochric, mollic, umbric, and histic epipedons and argillic, salic, gypsic, and calcic horizons, have been observed in Gelisols.",
  "subject": "Natural environments",
  "references": [
    "USDA Natural Resources Conservation Service Soil Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys (1999)"
  ],
  "url": "https://mlchart.com/terminology/environment/gelisols/"
}