what is permafrost
Permafrost is soil, rock or sediment that is frozen more than two consecutive years. In areas not overlain by ice, it exists beneath a layer of soil, rock or sediment, which freezes and thaws annually and is called the active layer.xceptions occur in un-glaciated Siberia and Alaska where the present depth of permafrost is a relic of climatic conditions during glacial ages where winters were up to 11 Â°C (20 Â°F) colder than those of today.