OCR A-Level Geography H481
Coastal Landscapes
Glaciated Landscapes
Dryland Landscapes
Earth’s Life Support Systems
Changing Spaces; Making Places
Trade in the Contemporary World
Global Migration
Human Rights
Power and Borders
Climate Change
Disease Dilemmas
Exploring Oceans
Future of Food
Hazardous Earth
Geographical Skills
Glaciated Landscapes
Permafrost, patterned ground and pingos
- 2 things to know
- Component 01
Overview
Recall questions on periglacial environments, continuous, discontinuous and sporadic permafrost, the active layer, frost heave and patterned ground, ice wedges, open-system and closed-system pingos in the Mackenzie Delta, relict periglacial features in Britain, and the effects of present-day warming.
What you need to know
Answer each one before you reveal it.
Distinguish continuous permafrost from discontinuous permafrost.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What does the term periglacial mean?
Model answer
It describes cold environments at or near the margins of ice, where the ground freezes but there is no permanent ice cover.
- 2
Define permafrost.
Model answer
Permafrost is ground that remains at or below 0 °C for at least two consecutive years.
- 3
What is the active layer?
Model answer
It is the surface layer of ground that thaws each summer and refreezes each winter, ranging from about 0.3 m in the high Arctic to several metres at the warmer margins of the permafrost zone.
- 4
Distinguish continuous permafrost from discontinuous permafrost.
Model answer
Continuous permafrost underlies almost the whole ground surface in the coldest regions, while discontinuous permafrost occurs in patches separated by unfrozen ground.
- 5
What is sporadic permafrost?
Model answer
It is isolated islands of permanently frozen ground covering less than about half the area, found at the warm margins of the periglacial zone.
- 6
Roughly what proportion of the land surface of the northern hemisphere is underlain by permafrost?
Model answer
About a quarter of it.
Other ways to work this
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