Sphagnum moss and peat cores are characteristic of palsas, structures that develop in areas unfavorable tothe formation of this layer. Aggradation of this layer around sandy s
Sphagnum moss and peat cores are characteristic of palsas, structures that develop in areas unfavorable tothe formation of this layer. Aggradation of this layer around sandy sediments of drained lake bottoms formsconical hills topped by talik, a structure known as a pingo. Giant holes in this layer on the Yamal Peninsulahave created concern about methane release. This layer underlays the active layer, and the thermal offset is thedifference in the mean annual ground surface temperature and the temperature at the top of this layer. Collapseof this layer is associated with collapse-scar bogs, thermokarst lakes, and drunken trees. For 10 points,name this thick layer of soil that remains frozen year-round in cold climates. 