Thaw depth Thaw depth In soil science, the thaw depth or thaw line is the instantaneous level down to which the soil has warmed to zero degrees celcius. The active layer thickness is the maximum thaw depth over a period of two years. The layer of soil over the thaw depth is called the active layer, while the soil below is called permafrost. The term frost front refers to the varying position of the thaw line during the periods of freezing/thawing. The knowledge of the thaw depth is important for the two major reasons: its influence on the ecology and on construction
Overburden between two areas of economic interest, such as the material separating coal seams within strata. Overburden is also used for all soil and ancillary material above the bedrock horizon in a given area. By analogy, overburden is also used to describe the soil and other material that lies above a specific geologic feature, such as a buried astrobleme, or above an unexcavated site of archeological interest. In particle physics, the overburden of an underground laboratory may be important to shield the facility from cosmic radiation that can interfere with experiments. In arboriculture, the word is also used for the soil