Glaciated Landscapes

What you'll learn

This revision guide covers glaciated landscapes as examined in WJEC GCSE Geography. You'll study how ice shapes the land through erosion and deposition, creating distinctive landforms in upland areas. The guide explains the processes at work, the features they create, and uses real UK examples you need to know for your exam.

Key terms and definitions

Glacier — a large mass of ice that moves slowly downhill under its own weight, eroding and transporting material as it flows

Plucking — a glacial erosion process where meltwater freezes onto rock, and as the glacier moves, it pulls away blocks of rock from the bedrock

Abrasion — erosional process where rock fragments frozen into the base and sides of a glacier scrape and grind the underlying bedrock, acting like sandpaper

Moraine — material (rock, clay, sand) transported and deposited by a glacier, classified by position as lateral, medial, terminal or ground moraine

Corrie (or cirque) — an armchair-shaped hollow eroded into a mountainside by a small glacier, often containing a small lake (tarn) after the ice melts

Arête — a sharp, narrow ridge formed when two corries erode back-to-back on either side of a mountain

U-shaped valley — a steep-sided, flat-bottomed valley with a wide floor, formed when a glacier deepens and widens a former V-shaped river valley

Drumlin — a smooth, elongated hill made of glacial till, with a blunt end facing the direction from which the ice advanced and a tapered end pointing downstream

Core concepts

Formation of glaciers and ice movement

Glaciers form in areas where snow accumulation exceeds melting over many years. In upland Britain, this occurred during ice ages when temperatures were much lower than today. Snow compacts into ice under its own weight, eventually forming a glacier thick enough to flow downhill.

The glacier moves through two main mechanisms:

• Internal deformation: ice crystals slide over each other under pressure
• Basal sliding: meltwater at the glacier base lubricates movement over bedrock

At the base and sides of the glacier, temperatures and pressure cause freeze-thaw cycles. Meltwater enters cracks in rocks, freezes overnight, expands and widens the cracks. This freeze-thaw weathering breaks up bedrock, providing material for glacial erosion.

Glacial erosion processes and landforms

Erosion processes

Two main erosion processes shape glaciated landscapes:

Plucking occurs when meltwater seeps into joints in the bedrock and freezes. As the glacier moves, it pulls away chunks of rock. This is most effective where the bedrock is well-jointed and at the base of glaciers where pressure melting occurs.

Abrasion happens when rocks frozen into the glacier scrape across the bedrock surface, grinding it down and creating striations (scratch marks). The rock fragments act like sandpaper or a giant file. This process produces rock flour — fine sediment that gives glacial meltwater its distinctive milky colour.

Corries

A corrie forms in a hollow on a mountainside where snow accumulates. The process works as follows:

1. Snow collects in a north- or east-facing hollow (in the Northern Hemisphere these receive less sun and stay cold)
2. Snow compacts into ice and begins to rotate, eroding the hollow deeper through abrasion and plucking
3. The back wall becomes steeper through plucking and freeze-thaw weathering
4. A rock lip forms at the front edge where erosion is less intense
5. After the ice melts, a circular lake (tarn) often fills the hollow

Example: Red Tarn below Helvellyn in the Lake District occupies a classic corrie.

Arêtes and pyramidal peaks

When two corries erode back-to-back, the land between them forms a narrow, knife-edged ridge called an arête. Striding Edge on Helvellyn is a famous UK example.

When three or more corries erode around a mountain summit, they create a sharp, pointed peak called a pyramidal peak. Snowdon in Wales demonstrates this feature clearly.

U-shaped valleys

Glaciers moving down former river valleys transform them dramatically:

1. The glacier erodes vertically through abrasion and plucking, deepening the valley floor
2. The ice also erodes sideways, widening the valley
3. Interlocking spurs from the original river valley are removed, creating truncated spurs
4. The result is a steep-sided, flat-bottomed, wide valley with a characteristic U-shape in cross-section

Example: Nant Ffrancon valley in Snowdonia shows a classic U-shaped profile with steep sides rising over 500 metres.

Hanging valleys

Tributary glaciers are smaller than the main glacier and erode less deeply. When the ice melts, tributary valleys are left "hanging" above the main valley floor. Streams from hanging valleys often form waterfalls as they descend to the main valley.

Example: Multiple hanging valleys exist in the Lake District, with waterfalls cascading into the main valleys.

Ribbon lakes

Long, narrow lakes occupying the floor of glaciated valleys are called ribbon lakes. They form where:

• Glaciers erode softer rock more deeply, creating a hollow
• A terminal moraine (deposited at the glacier snout) dams the valley
• The glacier over-deepens the valley floor through rotational movement

Example: Wastwater in the Lake District is England's deepest lake (79 metres) and occupies a glacially over-deepened valley.

Glacial deposition processes and landforms

Glaciers transport huge amounts of material. When the ice melts, this glacial till (also called boulder clay) is deposited. Till is unsorted, unstratified material ranging from fine clay to large boulders.

Erratics

Glacial erratics are rocks transported by ice and deposited far from their source area. The rock type differs from the local geology. By mapping erratics, geographers can track ice movement direction.

Example: Norber erratics in Yorkshire are dark Silurian rocks resting on white Carboniferous limestone, carried several kilometres by ice.

Terminal moraines

Material deposited at the furthest point reached by a glacier forms a terminal moraine — a ridge of till marking the maximum ice extent. The glacier acts like a bulldozer, pushing material forward until it melts.

Lateral and medial moraines

Lateral moraines are ridges of till deposited along the sides of a glacier, formed from material falling onto the glacier edges from valley walls.

When two glaciers merge, their lateral moraines combine to form a medial moraine — a ridge of material running down the centre of the enlarged glacier.

Drumlins

Drumlins are smooth, oval-shaped hills composed of glacial till:

• The blunt (stoss) end faces upstream (the direction from which ice came)
• The tapered (lee) end points downstream
• They typically occur in swarms of hundreds
• Heights range from 5-50 metres, lengths from 100-1000 metres

Formation theories suggest drumlins form when glaciers deposit material around obstacles, moulding it into streamlined shapes.

Example: The Ribble Valley in Lancashire contains extensive drumlin fields, with swarms of elongated hills creating a distinctive "basket of eggs" landscape.

Glaciated landscapes in the UK

During the last Ice Age (ending approximately 10,000 years ago), ice sheets covered much of northern Britain. Major glaciated upland areas include:

Snowdonia, Wales: Features corries (such as on Cadair Idris), arêtes, U-shaped valleys (Nant Ffrancon), and pyramidal peaks (Snowdon itself).

The Lake District, England: Contains all major erosional features — corries (Red Tarn), arêtes (Striding Edge, Sharp Edge), U-shaped valleys, ribbon lakes (Wastwater, Windermere), and hanging valleys with waterfalls.

The Scottish Highlands: Ben Nevis shows corries and arêtes, while Glen Coe demonstrates a classic glaciated valley.

Lowland areas show depositional features, particularly drumlin fields in the Ribble Valley and till deposits across much of northern England.

Worked examples

Question 1: Describe the formation of a corrie (4 marks)

Model answer: Snow accumulates in a hollow on a mountainside, often north- or east-facing where it receives less sun [1]. The snow compacts into ice which begins to move in a rotational manner [1]. Plucking and freeze-thaw weathering steepen the back wall of the hollow [1]. Abrasion deepens the hollow floor, while a rock lip forms at the front where erosion is less intense [1].

Mark scheme notes: One mark per valid developmental point. Must include specific processes (plucking, abrasion, freeze-thaw) and explain the rotation/movement of ice.

Question 2: Explain how glaciers erode the landscape (6 marks)

Model answer: Glaciers erode through two main processes: plucking and abrasion [1]. Plucking occurs when meltwater enters cracks in the bedrock and freezes [1]. As the glacier moves forward, it pulls away blocks of rock attached to the ice [1]. This is most effective where rock is well-jointed [1]. Abrasion happens when rocks frozen into the base of the glacier scrape across the bedrock like sandpaper [1]. This grinding action creates striations (scratch marks) and produces fine rock flour that makes meltwater look milky [1].

Mark scheme notes: Needs detailed explanation of processes with developmental points. Better answers distinguish between the two processes and explain mechanisms rather than just describing results.

Question 3: Study the photograph showing a U-shaped valley. Explain how this landform was created (6 marks)

Model answer: Originally, a river created a V-shaped valley with interlocking spurs [1]. During the ice age, a glacier filled the valley and began to move downhill under its own weight [1]. The glacier eroded the valley floor through abrasion, where rocks frozen into the ice scraped the bedrock, deepening the valley [1]. Plucking also occurred where meltwater froze onto jointed rock and the glacier pulled away blocks [1]. The glacier also eroded sideways, widening the valley significantly [1]. This created the characteristic steep sides and flat, wide floor visible in the photograph, with truncated spurs where interlocking spurs were removed [1].

Mark scheme notes: Must explain transformation from river valley to glaciated valley. Include specific erosion processes and describe resulting shape characteristics.

Common mistakes and how to avoid them

• Confusing erosion and deposition: Remember plucking and abrasion are erosion processes (removing material), while moraines and drumlins are depositional features (deposited material). Learn which process creates which landform.

• Vague process descriptions: Don't just say "ice erodes the rock." Specify whether plucking or abrasion is occurring and explain the mechanism (e.g., "meltwater freezes in cracks, then the glacier pulls rock away").

• Mixing up landform names: A corrie is the hollow; a tarn is the lake that may fill it afterwards. An arête is the ridge between two corries; a pyramidal peak needs three or more corries. Be precise.

• Forgetting directional information: Drumlins have a blunt end facing the direction ice came from (upstream) and a pointed end facing downstream. Corries in the Northern Hemisphere often face north or east. These details earn marks.

• Not using UK examples: WJEC expects UK case study knowledge. Learn specific examples like Helvellyn, Nant Ffrancon, or the Ribble Valley drumlins to support answers.

• Weak diagrams: If asked to draw a diagram, label it fully with feature names and add annotations explaining processes. A sketch without labels earns minimal marks.

Exam technique for "Glaciated Landscapes"

• Command word awareness: "Describe" means state features you can see (shape, size, appearance). "Explain" means give reasons and processes — you must say how/why something forms. "Explain" questions carry more marks and need developed points showing cause and effect.

• Use the mark scheme strategically: A 4-mark question needs 4 developed points. Don't write two paragraphs; write four distinct points. Check you've made enough separate points to earn full marks.

• Link processes to landforms: Always connect specific processes (plucking, abrasion, freeze-thaw) to the landforms they create. This shows understanding beyond memorisation.

• Resource interpretation: Photograph and diagram questions test whether you can identify features and explain them. Practice recognising U-shaped valleys, corries, arêtes and other features from images before the exam.

Quick revision summary

Glaciers form where snow accumulates and compacts into ice that flows downhill. Erosion through plucking (pulling away rock blocks) and abrasion (grinding bedrock) creates corries, arêtes, pyramidal peaks, and U-shaped valleys with hanging valleys and ribbon lakes. Deposition of glacial till creates moraines (terminal, lateral, medial) and drumlins (streamlined hills). UK examples include Snowdonia, the Lake District, and Scottish Highlands for erosional features, and the Ribble Valley for depositional landforms. Exam success requires naming specific processes, explaining formation sequences, and using located examples.