Upper zone of soil that (in higher latitudes) experiences daily and seasonal freeze and thaw.
the soil above permafrost, that melts each year in the summer sun. The active layer is where plant roots and burrowing insects are found.
(Also called frost zone, mollisol.) That part of the soil included with the suprapermafrost layer (i.e., existing above permafrost) that usually freezes in winter and thaws in summer. Its bottom surface is the frost table, beneath which may lie permafrost or talik. The depth of the active layer varies anywhere from a few inches to several feet. Compare active permafrost.
The layer that is checked active. FIRE STATIONS is the active layer in the picture below.
ground cover overlying permafrost that freezes and thaws with the seasons; also known as seasonal frost.
A seasonally thawed surface layer of soil in arctic or alpine regions that lies above permanently frozen ground and is between a few centimeters and about 3 meters thick.
the top layer of soil in permafrost that is subjected to seasonal freezing and thawing
The layer of ground subject to annual thawing and freezing in areas underlain by permafrost
In environments containing permafrost, the active layer is the top layer of soil that thaws during the summer and freezes again during the autumn.