AQA A-Level Geography 7037
Water and Carbon Cycles
Hot Desert Systems and LandscapesLandscape
Coastal Systems and LandscapesLandscape
Glacial Systems and LandscapesLandscape
HazardsHazards or ecosystems
Ecosystems Under StressHazards or ecosystems
Global Systems and Global Governance
Changing Places
Contemporary Urban EnvironmentsHuman option
Population and the EnvironmentHuman option
Resource SecurityHuman option
Glacial Systems and Landscapes
Periglacial Landforms and Processes
- 4 things to know
- Component 1
Overview
Recall questions on how frost heave forms patterned ground, stone circles and stripes, on ice wedges, open- and closed-system pingos and blockfields, and on the active layer, permafrost and solifluction with its lobes and terracettes.
What you need to know
Answer each one before you reveal it.
What causes the initial crack that begins ice-wedge formation?
What structural feature gives a pingo its dome shape?
Explain how frost heave and slope angle produce patterned ground.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What repeated process drives the formation of patterned ground in periglacial environments?
Model answer
Repeated freeze-thaw cycles cause frost heave and sorting of surface material.
- 2
Explain how frost heave contributes to patterned ground development.
Model answer
Frost heave pushes larger stones upward through the soil as ice lenses grow, bringing coarse material to the surface.
- 3
How do stones become arranged into polygons or stripes in patterned ground?
Model answer
After being heaved to the surface, stones migrate laterally through repeated freeze-thaw, accumulating at the edges of sorted patterns.
- 4
Under what slope conditions do stone circles form, and when do stone stripes develop instead?
Model answer
Stone circles form on flat or gently sloping ground; stone stripes develop on steeper slopes where gravity elongates the patterns.
- 5
What causes the initial crack that begins ice-wedge formation?
Model answer
Extreme winter cold causes thermal contraction of the frozen ground, opening a vertical crack in the permafrost.
- 6
What fills the crack in permafrost during spring, and what happens to it?
Model answer
Spring meltwater enters the crack and refreezes, adding a thin layer of ice to the wedge.
Other ways to work this
The same content, four other ways.
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