nonsorted circle

nonsorted circle:    A type of patterned ground whose mesh (shape) is dominantly circular and has a nonsorted appearance due to the absence of a border of rock fragments. Vegetation characteristically outlines the pattern by forming a bordering ridge. Diameters commonly range from 0.5 to 3 m. Nonsorted circles include mud boils, earth hummocks, turf hummocks, and frost boils. Nonsorted circles have various origins. Some, such as mud and earth hummocks and frost boils, involve cryoturbation activity and differential heave of frost-susceptible materials. Others, such as mud boils, involve hydraulic pressures and diapir-like displacement of water-saturated sediments.

   Compare: sorted circle, frost boil, patterned ground.

   NRC & GG

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circle — A form of patterned ground whose horizontal mesh is dominantly circular. Compare: nonsorted circle, patterned ground. GG … Glossary of landform and geologic terms
earth hummock — A type of hummock consisting predominantly of a core of silty and clayey mineral soil and showing evidence of cryoturbation. Earth hummocks are a type of nonsorted circle. Compare: turf hummock, hummock [ patterned ground ], nonsorted… … Glossary of landform and geologic terms
patterned ground — A general term for any ground surface exhibiting a discernibly ordered, more or less symmetrical, morphological pattern of ground and, where present, vegetation. Patterned ground is characteristic of, but not confined to, permafrost regions or … Glossary of landform and geologic terms
frost boil — A small mound of fresh soil material formed by frost action. A type of nonsorted circle commonly found in fine grained sediment underlain by permafrost, or formed in areas affected by seasonal frost. Compare: patterned ground. NRC … Glossary of landform and geologic terms
turf hummock — A hummock consisting of vegetation and organic matter with or without a core of mineral soil or stones (typically 10 50 cm height; 20 90 cm diameter). Groups of hummocks can form a type of patterned ground common to tundra or wet areas (e.g.,… … Glossary of landform and geologic terms

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