Thaw depth thaw line than clays. Yet another factors are the vegetation and the percentage of the soil organic matter, which influence the bulk density of the soil, and hence thermal conductivity. 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
San Joaquin (soil) in California by the survey. All were considered to have agricultural importance. Since then, three of these series have either been dropped from the official listings or have been combined with other soil series recognized at a later date. Thus, the San Joaquin soil is the oldest, continuously recognized soil series within the state. (More than 1,500 soil series are currently recognized in California.) Nearly one-half million acres (2,000 km²) of this soil have now been identified and mapped in many counties in California. With proper management, this soil has produced many billions of dollars of food wealth for the