GEG 3107 Lecture Notes - Lecture 4: Permafrost, Palsa, Ice
5 Dec 2016
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Document Summary
True palsas are only found in peat, but mineral-cored and lithalsas also exist. Can be up to 10 m high, and 50 cm in diameter. Mainly found in discontinues permafrost zone, but may be found in continuous too. Found in areas of poor drainage (bogs and fens), caused by segregated ice. Natural cycle of growth and degradation [flow chart], independent of climate change (but climate change does have an effect) However as air temperatures rise, the degradation increases (and growth has slowed/stopped) Degrading palsas may release methane or co2 as the organic material breaks down. As mounds grow larger they begin to break apart (wind erosion ) Water is a major cause of palsa degradation. Norway: air temperature rise from -3 to -2, resulting in substantial degradation. Wolf creek: rapid change, but caused by animal activity, not climate change. Beavers came back and (re)built dams, which flooded the area.
