Cold Environments: Periglacial Processes and Landforms

Andrew_Ellinas
Mind Map by Andrew_Ellinas, updated more than 1 year ago
Andrew_Ellinas
Created by Andrew_Ellinas almost 6 years ago
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A Levels Geography (Physical Geography-AS) Mind Map on Cold Environments: Periglacial Processes and Landforms, created by Andrew_Ellinas on 05/09/2014.

Resource summary

Cold Environments: Periglacial Processes and Landforms
1 Periglacial: Environments experiencing long cold winters and short warm summers, typically with permafrost but not covered by ice (glacial)
2 Permafrost
2.1 Ground that becomes permanently frozen to depths of over 100 meters.
2.2 Permafrost Table: The upper surface of the permafrost.
2.3 Active Layer: The top few centimetres of soil that may temporarily melt during summer, when temperatures briefly rise above 0 degrees C.
3 Periglacial Processes
3.1 Frost Shattering and Frost Heave
3.1.1 Frost Shattering: Water that expands when turned to ice-breaking apart rocks and sediments and forming a rock-strewn landscape called a felsenmeer
3.1.2 Leads to accumulation of scree at base of cliffs.
3.1.3 Frost Heave: Soils become very bumpy and irregular. Freezing soil water just below the surface expands and pushes up the ground above.
3.2 Nivation
3.2.1 Covers a range of processes associated with snow.
3.2.2 Includes the effects of frost shattering, which operates around the edges of the snow - gradually causing the underlying rock to disintergrate.
3.2.3 Meltwater removes any rock debris to reveal an ever enlarging nivation hollow.
4 Periglacial Landforms
4.1 Solifluction Lobes
4.1.1 Downslope movement of rock and soil material in response to gravity.
4.1.2 Occur in reasonably think and saturated active layer
4.2 Ice Wedges
4.2.1 Meltwater flows into cracks when permafrost contracts. The Meltwater refreezes in the winter to form ice wedges, which expand and force the cracks to widen.
4.2.2 Influence ground surface by forming narrow ridges - due to frost heave
4.3 Patterned Ground
4.3.1 As ice wedges become more extensive, a polygonal pattern may be formed on the ground surface-with ice wedges and their ridges marking the sides of the polygons
4.3.2 Stone Polygons
4.3.2.1 Stone Polygons tend to form on shallower slopes, and are directly associated with ice wedges. Frost heave causes expansions of the ground and lifts soil particles upwards.
4.3.2.2
4.4 Pingos
4.4.1 Water collects underneath the ground, as the sediment gradually freezes, the water collected becomes trapped and pressurized freezes as well.
4.4.2 This expansion causes the land to lift, creating a hill or mound
4.4.3 In the summer, the ice melts and forces the ground above to collapse inwards
4.4.4 Can be up to 60 meters high, and 600 meters in diameter.
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