Polar Husky A to Z
Pingo & Permafrost
Pingos are like cone-shaped icebergs on land - covered by dirt!
Pingos can be found where there is permanent permafrost in Siberia, Greenland, Alaska, Canada - even in Antarctica. Some rise 210 feet (70m) above the surrounding tundra and are 3000 feet (2 km) in diameter. The first to discover 'pingos' were the Danish botanist Erling Porsild. Yes, maybe you guessed it. He is indeed in family with GoNoth! team member Mille Porsild. It is her great-uncle!
But long before Erling ever wrote about pingos - Arctic people had found great use for them: as huge walk-in freezers. They would simply dig into the pingo making a storage room to keep food good and frozen through the Arctic summer!
Pingo is an Inuit word meaning "hill."
For a pingo to be born, there must first be a body of water -like a lake- that is on top of a stretch of permafrost. Once the top of this lake freezes, dirt and plant material blown around by the wind can collect on top of the lake, creating a kind of lid. Then, the water above the permafrost and below the ice-earth lid will, at some point, freeze, forcing it upward.
Pingos usually grow about an inch (a few centimeters) per year and the largest take decades or even centuries to form. All pingos eventually break down and collapse. The longest they are believed to last is about 1000 years.
Permafrost is ground that always stays at or below the freezing point of water (32° F or 0° C). About 20% of the Earth's land mass is covered by permafrost!
The topmost layer of permafrost -called the active layer- is thin and thaws during the summer, which allows some plants to grow there. The thickness of active layers varies each year, but averages about 2-12 feet (0.6 - 4 m) thick. Permafrost can run very deep...
*It has been calculated that the time required to form the deep permafrost underlying Prudhoe Bay, Alaska is 500,740 years!
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