Solifluction
Slow downslope movement of soil in cold regions due to freezing and thawing, forms lobes
Ice Heave
Ice crystals expand and force soil up
Ice Wedges
Water gets into a small crack, expands and grows every year with freeze-thaw, forms ice-wedge polygons
Thermokarst
Thawing of ice-rich permafrost or the melting of massive ice blocks, irregular pits and depressions develop by thaw settlement
Permafrost
Soil, regolith, bedrock that is below 0°
Continuous, discontinuous, or sporadic
25% of exposed land in the Northern Hemisphere
Active layer that freezes and thaws with seasons
Impacts of Melting Permafrost
Ecosystem damage → habitats, lakes disappear
Infrastructure damage → roads, houses, pipes
Landslides → loose debris
Coastal erosion
Methane
Pingos
Conspicuous conical mound or circular hill, with a core of ice, found on tundra where permafrost is present
Form under initially frozen lakes (closed system) or by groundwater forcing through permafrost (open system)
Patterned Ground
Polygons, stone circles, stripes
Freeze-thaw cycles → frost heave
active layer freezes → ice crystals develop → increases volume of soil → frost heave (hydrostatic pressure) → forms small domes on surface
stones → lower specific heat capacity → expand further → push up → fall forming circles or stripes