Introductionby Edwin S. Clarke, P.E., (F.ASCE),
Permafrost is defined as soil that remains frozen for more than two years. At elevations less than 304.8 m (1000 ft.), it is frequently encountered north of latitude 60. It may also be found south of latitude 60 at higher elevations or in areas with colder climates. In general, permafrost is associated with polar regions and exists as a layer of continuously frozen soil underlying a thin, active layer of soils that undergo annual freeze/thaw cycles.
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