IB Geography Periglacial Landforms and Processes

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