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
Martian soil as an unconsolidated and chemically weathered surficial layer of fine-grained mineral or organic material exceeding centimeter scale thickness, with or without coarse elements and cemented portions. Martian dust generally connotes even finer materials than Martian soil, the fraction which is less than 30 micrometres in diameter. Disagreement over the significance of soil's definition arises due to the lack of an integrated concept of soil in the literature. The pragmatic definition "medium for plant growth" has been commonly adopted in the planetary science community but a more complex definition describes soil as "(bio)geochemically/physically altered material at the surface of a planetary