How does meltwater form at the base of a glacier during basal slip?

Meltwater forms due to pressure melting (where overlying ice pressure lowers the melting point) or from geothermal heat rising from the Earth's interior.

Describe how the glacier moves during basal slip.

The glacier slides as a single mass over the bed, moving on a thin layer of meltwater that reduces friction between ice and bedrock.

Why does water refreeze on the downstream side of an obstacle during regelation creep?

Reduced pressure on the downstream side raises the melting point, allowing the water to refreeze.

Edexcel A-Level Geography 9GE0

Tectonic Processes and Hazards

Topic overview Global distribution of tectonic hazards and plate boundary processes The structure of the Earth and mantle convection Ridge push, slab pull and sea-floor spreading Destructive and constructive plate margins Collision and transform margins Magma composition and eruption style The Benioff zone and earthquake magnitude Seismic waves and their effects Volcanic hazards and tsunamis Hazard, vulnerability, resilience and the risk equation The Pressure and Release model The impacts of tectonic hazards Measuring hazards, and the hazard profile Speed of onset, areal extent, duration and predictability Why impacts differ between countries Education, buildings, healthcare and income as factors in vulnerability Governance at local and national level Population density, isolation and urbanisation How development level shapes disaster outcomes Trends in tectonic disasters, data reliability and sampling Mega-disasters and multiple-hazard zones Theoretical frameworks for prediction, impact and management Land-use zoning and hazard-resistant design Monitoring, prediction, preparedness and aid

Glaciated Landscapes and ChangeLandscape

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Coastal Landscapes and ChangeLandscape

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Glaciated Landscapes and Change

Basal slip and internal deformation

3 things to know
Paper 1

Overview

Recall questions on regelation creep, the role of meltwater, and how ice crystals deform under pressure.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Process

What characteristic of temperate glaciers allows them to move faster than polar glaciers?

Process

What role does water play in the process of basal sliding?

Key term

What happens to the meltwater produced during regelation creep?

Questions from this subtopic

Each one with the model answer underneath.

1
What characteristic of temperate glaciers allows them to move faster than polar glaciers?
Model answer
Temperate glaciers are warm-based with meltwater present at their base, which facilitates faster movement through basal slip.
2
How does meltwater form at the base of a glacier during basal slip?
Model answer
Meltwater forms due to pressure melting (where overlying ice pressure lowers the melting point) or from geothermal heat rising from the Earth's interior.
3
What role does water play in the process of basal sliding?
Model answer
Water lubricates the contact between ice and rock, reducing friction and allowing the glacier to slide.
4
Describe how the glacier moves during basal slip.
Model answer
The glacier slides as a single mass over the bed, moving on a thin layer of meltwater that reduces friction between ice and bedrock.
5
What happens to the meltwater produced during regelation creep?
Model answer
The meltwater flows around the obstacle as liquid water.
6
Why does water refreeze on the downstream side of an obstacle during regelation creep?
Model answer
Reduced pressure on the downstream side raises the melting point, allowing the water to refreeze.

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Tectonic Processes and Hazards

Glaciated Landscapes and Change

Coastal Landscapes and Change

Globalisation

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