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
Dryland Landscapes
Frost-shattered debris, nivation hollows and solifluction deposits
- 2 things to know
- Component 01
Overview
Recall questions on relict periglacial landforms in warm deserts, frost shattering and recognising its debris, relict scree slopes, nivation hollows and their aspect, solifluction and its deposits, and how warming affects periglacial features in drylands and polar deserts.
What you need to know
Answer each one before you reveal it.
How does frost shattering break rock apart?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why do some warm deserts contain landforms made by frost?
Model answer
During the cold stages of the Pleistocene these areas were far colder, so periglacial processes operated there, and the landforms they produced survive today as relict features.
- 2
Define the term periglacial.
Model answer
Periglacial describes the cold conditions found beyond the margins of ice sheets and glaciers, where frost action and frozen ground rather than moving ice dominate the landscape.
- 3
How does frost shattering break rock apart?
Model answer
Water held in a crack expands by about 9% as it freezes and forces the crack wider, and repeated cycles of freezing and thawing eventually split the rock into angular fragments.
- 4
How can frost-shattered debris be recognised in the field?
Model answer
It consists of very angular, poorly sorted fragments with sharp unworn edges, usually forming a blocky sheet on flat ground or a scree at the foot of a rock face.
- 5
How can you tell that a scree slope in a dryland is relict rather than active?
Model answer
The debris is stable and often cemented, and it is colonised by lichen, soil and plants, with no fresh angular material lying at the surface or newly fallen onto it.
- 6
What is nivation?
Model answer
Nivation is the combination of frost weathering, chemical weathering and removal of debris by meltwater that operates beneath and around a patch of snow lying through the summer.
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