Geography 2010A/B Study Guide - Quiz Guide: Pediment, Blockfield, Frost Weathering
29 Aug 2018
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Document Summary
A number of models for cryoturbation have been advanced: some are supported by observations of soil movement and patterns of organic material included in the soil. Repeated heave and contraction generates an effective circulation of the soil. The result is that frost heave can produce a wide range of surface features that range from vegetated and bare mounds and hummocks, to sorted circles and polygons. Sorting likely occurs due to differential heaving of coarser clasts to the surface and away from the high centre of the mound: once the material is sorted, it remain so without further cryoturbation. In some cases, again in frost susceptible material (fine grained), hydrostatic pressure can result from water confinement in the active layer. Particularly when the soil surface is dry, this higher soil water pressure at depth can result in the ejection of mud to the surface to form a mud boil.
