Permafrost, earth that remains frozen year-round, can also mummify. One Siberian mummy, the 2,500 year-old Ice Maiden, was quite literally frozen in a block of ice after her burial chamber flooded and the water quickly froze. Because her burial chamber was constructed from permafrost earth, the ice that formed inside never melted.

Some of the best preserved and oldest natural mummies were found in thawing permafrost in Siberia, Alaska and Canada: like the 40.000 year old Russian mammoth calf "Dima" (discovered in 1977) or the 36.000 year old bison "Blue Babe" (discovered in 1979) from Fairbanks (Alaska) and a 40.000 year old black-footed ferret from the Yukon territory.