What is the difference between a glacier and an ice sheet?

A glacier is a persistent body of dense ice that moves under its own weight, typically found in mountain valleys (alpine glaciers) or as smaller ice masses. An ice sheet is a massive glacier covering over 50,000 km² of land, such as the Antarctic and Greenland ice sheets. Ice sheets flow outward from a central dome and can be several kilometres thick, whereas glaciers are more confined by topography.

How do drumlins form?

Drumlins are streamlined, elongated hills formed beneath a moving glacier. They are composed of till (unsorted glacial sediment) and are shaped by the ice flow, with a steep stoss (up-ice) side and a gentle lee (down-ice) side. Their formation is not fully understood, but they are thought to result from variations in basal sliding and sediment deformation, often occurring in swarms called 'drumlin fields'.

What is the difference between a lateral moraine and a terminal moraine?

Lateral moraines are ridges of debris deposited along the sides of a glacier, formed by material falling from valley walls onto the ice. Terminal moraines are ridges of till and rock debris deposited at the glacier's snout, marking its maximum advance. While lateral moraines are parallel to ice flow, terminal moraines are perpendicular and often arc-shaped.

How does glacial erosion create a U-shaped valley?

A U-shaped valley forms when a glacier erodes a pre-existing V-shaped river valley. The glacier's weight and movement cause abrasion and plucking on the valley floor and sides, widening and deepening the valley. The characteristic U-shape results from the glacier's ability to erode both the bottom and sides, creating steep valley walls and a flat floor. After deglaciation, the valley often has a misfit stream (a small river in a large valley).

What is permafrost and why is it important?

Permafrost is ground that remains at or below 0°C for at least two consecutive years. It is important because it stores vast amounts of organic carbon, which, if thawed, could release greenhouse gases (CO₂ and methane) and accelerate climate change. Permafrost also affects infrastructure in cold regions, causing ground instability when it thaws. In periglacial landscapes, permafrost influences processes like solifluction and ice wedge formation.

How do glaciers contribute to sea-level rise?

Glaciers contribute to sea-level rise when they lose mass faster than they gain it, primarily through melting and calving (ice breaking off into the ocean). This adds water to the oceans from land-based ice. Ice sheets in Greenland and Antarctica are the largest contributors, but mountain glaciers also play a significant role. The rate of sea-level rise depends on the balance between accumulation (snowfall) and ablation (melting and calving).

How to Revise Glacial Systems and Landscapes — AQA A-Level Geography

Explain the processes of glacial erosion, transportation, and deposition. Understand the factors affecting glacial movement

Examiner Tips for Glacial Systems and Landscapes

Use diagrams to illustrate erosional and depositional features.
Link processes to specific landform examples.
Explain how climate change impacts glacial movement.
In explanation questions, use a step-by-step process approach: e.g., for a corrie, start with nivation hollow enlargement, then rotational flow, then plucking and abrasion, concluding with lip formation and tarn.
For analysis of landscapes, employ a systems framework linking inputs (snow accumulation), processes (erosion, transport, deposition), and outputs (landform assemblages) over time.
Always support descriptions with annotated sketches, clearly labelling key features like truncated spurs, hanging valleys, and misfit streams to demonstrate understanding of scale and sequence.
When discussing glacial landscapes, use technical vocabulary precisely (e.g., 'till' vs. 'outwash', 'subglacial' vs. 'supraglacial') to access higher mark bands.
Use specific case studies (e.g., Tuktoyaktuk Peninsula, Russia) to exemplify periglacial landforms and climate change impacts.

Common Mistakes in Glacial Systems and Landscapes

Confusing plucking with abrasion.
Forgetting that glacial movement is influenced by both internal and external factors.
Misidentifying depositional landforms.
Misidentifying drumlins as purely erosional features, overlooking their subglacial depositional origin and streamlined morphology.
Assuming all U-shaped valleys are solely a product of glacial erosion without acknowledging the role of pre-existing fluvial valleys in guiding ice flow.
Confusing the direction of ice flow from striations; students often interpret the crescentic overdeepenings on the down-ice side incorrectly.

Key Marking Points

Explain how plucking and abrasion cause glacial erosion.
Describe how glaciers transport material (supraglacial, englacial, subglacial).
Identify and explain depositional features like moraines and drumlins.
Discuss factors affecting glacial movement (e.g., basal sliding, internal deformation).
Award credit for accurately distinguishing between subglacial and ice-marginal depositional environments, supported by annotated diagrams.
Credit explanations that link specific erosional processes (e.g., plucking, abrasion) to the resultant micro-scale features (e.g., striations, chattermarks) and macro-scale landforms.

← Back to AQA A-Level Geography

Glacial Systems and Landscapes

AQA

A-Level

Glacial processes involve erosion, transportation, and deposition of material by glaciers. Factors like climate, slope, and ice thickness affect glacial movement. Understanding these processes is key to interpreting glacial landscapes.

Objectives

Exam Tips

Pitfalls

Key Terms

Mark Points

Topic Overview

Glacial systems and landscapes form a key component of the AQA A-Level Geography specification, focusing on the processes, landforms, and environments associated with cold climates. This topic explores how glaciers operate as systems, with inputs (e.g., snowfall, debris), stores (e.g., ice, moraine), transfers (e.g., basal sliding, internal deformation), and outputs (e.g., meltwater, sediment). Understanding these systems is crucial for explaining the formation of distinctive landscapes, such as U-shaped valleys, corries, and drumlins, and for appreciating the dynamic nature of glaciated regions in the past and present.

This topic matters because glacial landscapes cover about 10% of Earth's land surface today and were far more extensive during the Pleistocene ice ages. Studying glacial systems helps students understand past climate change, as glacial landforms are key indicators of former ice extent. Moreover, contemporary glacial retreat due to global warming has significant implications for sea-level rise, water resources, and geohazards. By linking glacial processes to broader environmental systems, students develop a holistic understanding of physical geography and its relevance to current global challenges.

Within the wider AQA A-Level Geography course, glacial systems and landscapes connect to other topics such as water and carbon cycles, climate change, and hazards. For example, the role of glaciers in storing freshwater links to the water cycle, while the impact of glacial erosion on sediment transport relates to coastal systems. This topic also provides a foundation for understanding periglacial environments and the impacts of climate change on cold environments, making it an integrated part of the physical geography curriculum.

Key Concepts

Core ideas you must understand for this topic

→Glacial system: inputs (snow, debris), stores (ice, moraine), transfers (basal sliding, internal deformation), and outputs (meltwater, sediment).
→Erosional processes: abrasion (rock fragments scraping the bed) and plucking (ice freezing onto bedrock and pulling it away).
→Depositional landforms: till (unsorted sediment) and moraines (lateral, medial, terminal, ground) formed by glacial deposition.
→Glacial landforms: corries (armchair-shaped hollows), arêtes (sharp ridges), U-shaped valleys, and drumlins (elongated hills indicating ice flow direction).
→Periglacial processes: freeze-thaw weathering, solifluction (slow soil flow), and permafrost (permanently frozen ground).

What You Need to Demonstrate

Key skills and knowledge for this topic

Explain how plucking and abrasion cause glacial erosion.
Describe how glaciers transport material (supraglacial, englacial, subglacial).
Identify and explain depositional features like moraines and drumlins.
Discuss factors affecting glacial movement (e.g., basal sliding, internal deformation).
Award credit for accurately distinguishing between subglacial and ice-marginal depositional environments, supported by annotated diagrams.
Credit explanations that link specific erosional processes (e.g., plucking, abrasion) to the resultant micro-scale features (e.g., striations, chattermarks) and macro-scale landforms.
Reward responses that integrate the concept of glacial mass balance and ice flow dynamics into the analysis of landscape development, showing how landforms reflect glacial advance and retreat cycles.
Mark positively for referencing classic case studies (e.g., Lake District or Swiss Alps) with precise landform examples and spatial relationships.

Marking Points

Key points examiners look for in your answers

Explain how plucking and abrasion cause glacial erosion.
Describe how glaciers transport material (supraglacial, englacial, subglacial).
Identify and explain depositional features like moraines and drumlins.
Discuss factors affecting glacial movement (e.g., basal sliding, internal deformation).
Award credit for accurately distinguishing between subglacial and ice-marginal depositional environments, supported by annotated diagrams.
Credit explanations that link specific erosional processes (e.g., plucking, abrasion) to the resultant micro-scale features (e.g., striations, chattermarks) and macro-scale landforms.
Reward responses that integrate the concept of glacial mass balance and ice flow dynamics into the analysis of landscape development, showing how landforms reflect glacial advance and retreat cycles.
Mark positively for referencing classic case studies (e.g., Lake District or Swiss Alps) with precise landform examples and spatial relationships.
Award credit for accurately describing the role of diurnal and seasonal freeze-thaw cycles in frost shattering.
Credit explanations linking ice segregation to patterned ground formation, such as stone polygons.
Assessors should expect clear diagrams or written descriptions of pingo formation (open-system and closed-system).
For climate change impact, credit for referencing specific examples like the Alaskan North Slope or Siberian permafrost and incorporating quantitative data on temperature rise.
Marks awarded for evaluating the significance of positive feedback loops, such as methane release amplifying warming.

Examiner Tips

Expert advice for maximising your marks

💡Use diagrams to illustrate erosional and depositional features.
💡Link processes to specific landform examples.
💡Explain how climate change impacts glacial movement.
💡In explanation questions, use a step-by-step process approach: e.g., for a corrie, start with nivation hollow enlargement, then rotational flow, then plucking and abrasion, concluding with lip formation and tarn.
💡For analysis of landscapes, employ a systems framework linking inputs (snow accumulation), processes (erosion, transport, deposition), and outputs (landform assemblages) over time.
💡Always support descriptions with annotated sketches, clearly labelling key features like truncated spurs, hanging valleys, and misfit streams to demonstrate understanding of scale and sequence.
💡When discussing glacial landscapes, use technical vocabulary precisely (e.g., 'till' vs. 'outwash', 'subglacial' vs. 'supraglacial') to access higher mark bands.
💡Use specific case studies (e.g., Tuktoyaktuk Peninsula, Russia) to exemplify periglacial landforms and climate change impacts.
💡Always define key terms such as ‘active layer’, ‘talik’, and ‘thermokarst’ in your responses.
💡When discussing climate change, structure your answer to show both environmental and socio-economic consequences, and always link back to the processes.
💡Include annotated diagrams where appropriate, as these can effectively illustrate complex landform evolution and gain credit.
💡Use specific terminology: In exam answers, use precise terms like 'abrasion', 'plucking', 'basal sliding', and 'till' to demonstrate knowledge. Avoid vague language like 'ice scrapes the rock'.
💡Link processes to landforms: When describing a landform, always explain the processes that formed it. For example, for a corrie, mention freeze-thaw weathering, plucking, and abrasion, and how rotational slip creates the overdeepened hollow.
💡Include diagrams: In the exam, labelled diagrams of landforms (e.g., a corrie or U-shaped valley) can gain marks. Practice drawing simple, clear diagrams with arrows showing processes like ice flow and erosion.

Common Mistakes

Pitfalls to avoid in your exam answers

Confusing plucking with abrasion.
Forgetting that glacial movement is influenced by both internal and external factors.
Misidentifying depositional landforms.
Misidentifying drumlins as purely erosional features, overlooking their subglacial depositional origin and streamlined morphology.
Assuming all U-shaped valleys are solely a product of glacial erosion without acknowledging the role of pre-existing fluvial valleys in guiding ice flow.
Confusing the direction of ice flow from striations; students often interpret the crescentic overdeepenings on the down-ice side incorrectly.
Overgeneralising that all moraines mark stable ice margins, failing to distinguish between end, recessional, and push moraines in terms of formation and climatic significance.
Confusing periglacial with glacial environments; failing to distinguish that periglacial areas are not covered by ice but are subject to intense frost action.
Incorrectly assuming that permafrost is continuous across all periglacial regions without acknowledging discontinuous and sporadic zones.
Oversimplifying the climate change impact as solely landscape change, neglecting the broader implications for carbon release and infrastructure damage.
Misconception: Glaciers move only by sliding. Correction: Glaciers move by both basal sliding (where meltwater reduces friction) and internal deformation (ice crystals deforming under pressure). The dominant process depends on temperature and bed conditions.
Misconception: All glacial landforms are formed by erosion. Correction: While many landforms are erosional (e.g., U-shaped valleys), others are depositional (e.g., drumlins, terminal moraines). Students must distinguish between the two and explain the processes involved.
Misconception: Glacial landscapes are static. Correction: Glacial landscapes are dynamic, with ongoing processes of erosion, transport, and deposition. Even after deglaciation, periglacial processes continue to modify the landscape.

Frequently Asked Questions

Common questions students ask about this topic

Before You Start

Prior knowledge that will help with this topic

•Understanding of the water cycle and the role of ice as a store.
•Basic knowledge of weathering and erosion processes from earlier geography topics.
•Familiarity with systems thinking (inputs, outputs, stores, flows) as applied in physical geography.

Key Terminology

Essential terms to know

Abrasion, plucking, freeze-thaw
Basal sliding, internal deformation
U-shaped valleys, corries, arêtes, pyramidal peaks
Moraines, drumlins, erratics
Permafrost dynamics and thermal regimes
Freeze-thaw weathering and mass movement
Patterned ground and frost heave
Thermokarst and landscape degradation
Climate change and permafrost thaw
Environmental feedback mechanisms

Likely Command Words

How questions on this topic are typically asked

Explain

Describe

Identify

Discuss

Analyse

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Practice questions tailored to this topic