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
Warm-based and cold-based ice, and the mechanisms of glacier movement
- 3 things to know
- Component 01
Overview
Recall questions on warm-based and cold-based glaciers and the pressure melting point, basal sliding, regelation, enhanced basal creep and internal deformation, the velocity profile of a valley glacier, extending and compressing flow, crevasses, glacier surges and the effect of summer meltwater.
What you need to know
Answer each one before you reveal it.
Why is a cold-based glacier associated with very little erosion?
Compare typical rates of movement of warm-based and cold-based glaciers.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is a warm-based glacier?
Model answer
It is a glacier whose base is at the pressure melting point, so meltwater is present at the bed and the ice can slide over it.
- 2
What is a cold-based glacier?
Model answer
It is a glacier whose base is well below the pressure melting point, so the ice is frozen to the bedrock and cannot slide.
- 3
What is the pressure melting point?
Model answer
It is the temperature at which ice melts under a given pressure, and it falls below 0 °C as the weight of overlying ice increases.
- 4
Name two sources of heat that can bring the base of a thick glacier to its pressure melting point.
Model answer
Geothermal heat rising from the rock beneath and frictional heat generated as the ice moves over its bed.
- 5
Why is a cold-based glacier associated with very little erosion?
Model answer
The ice is frozen to its bed and moves almost entirely by internal deformation, so debris is not dragged across the rock and abrasion and plucking barely occur.
- 6
Compare typical rates of movement of warm-based and cold-based glaciers.
Model answer
Warm-based glaciers commonly move tens to hundreds of metres a year, while cold-based glaciers may move only a few metres a year.
Other ways to work this
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