Glacial Landscapes in the UK
The Ice Age and UK Glaciation
During the last Ice Age (the Pleistocene, ending roughly 10,000 years ago), ice sheets and glaciers covered much of the UK — approximately as far south as a line from the Severn Estuary to the Wash. The landscapes of Snowdonia, the Lake District, the Scottish Highlands, and the Yorkshire Dales were all sculpted by glacial processes.
How Glaciers Form and Move
Glaciers form when snow accumulates over many years, compresses, and turns into dense glacial ice. A glacier grows when accumulation (snowfall) exceeds ablation (melting/evaporation). Glaciers move downhill under their own weight by two mechanisms:
- Basal sliding — meltwater beneath the glacier lubricates the base, allowing it to slide over bedrock
- Internal deformation — ice crystals within the glacier deform and flow under pressure
Glacial Erosion Processes
| Process | Description |
|---|---|
| Plucking | Meltwater freezes onto rock at the base/sides of the glacier; as the glacier moves, it pulls chunks of rock away |
| Abrasion | Rocks frozen into the base of the glacier scrape across the bedrock like sandpaper, creating scratches called striations |
| Freeze-thaw weathering | Water enters cracks in rock above the glacier, freezes and expands by ~9%, widening the crack; repeated cycles shatter the rock, producing scree |
Erosional Landforms
Corries (Cirques)
1. Snow accumulates in a north-facing hollow (less sun, less melting)
2. Repeated freeze-thaw weathering steepens the back wall
3. The glacier rotates within the hollow (rotational slip), eroding a deep armchair-shaped basin by plucking and abrasion
4. A raised lip forms at the front where erosion is less intense
5. When the glacier melts, the hollow may fill with water to form a tarn (corrie lake)
Example: Red Tarn on Helvellyn, Lake District — a classic corrie with a tarn and steep back wall.
Aretes and Pyramidal Peaks
- An arete forms when two corries erode back-to-back on either side of a ridge, creating a narrow, knife-edge ridge (e.g. Striding Edge, Helvellyn)
- A pyramidal peak forms when three or more corries erode into a mountain from different sides, leaving a sharp, pointed summit (e.g. Snowdon in Wales; the Matterhorn in the Alps)
Glacial Troughs (U-Shaped Valleys)
- A glacier fills a pre-existing V-shaped river valley
- The glacier erodes the valley sides and floor by plucking and abrasion, widening and deepening it
- The result is a valley with a flat floor and steep, straight sides — a U-shape
- Truncated spurs — the interlocking spurs of the original river valley are sliced off by the glacier, leaving steep cliff faces
- Hanging valleys — smaller tributary glaciers erode less deeply; when the ice melts, their valleys are left high above the main valley floor, often with waterfalls cascading down (e.g. valleys above Nant Ffrancon, Snowdonia)
- Ribbon lakes — long, narrow lakes formed in hollows eroded in softer rock on the valley floor (e.g. Windermere, Lake District — England's largest natural lake, ~17 km long)
Example: Nant Ffrancon, Snowdonia — a classic glacial trough with a flat floor, steep sides, truncated spurs, and hanging valleys with waterfalls.
Glacial Transportation and Deposition
Glaciers carry huge amounts of rock debris called moraine:
| Type | Location |
|---|---|
| Lateral moraine | Material carried along the edges (sides) of the glacier, from freeze-thaw weathering of the valley sides |
| Medial moraine | Formed when two glaciers merge and their lateral moraines combine in the middle |
| Ground moraine | Material dragged along the base of the glacier, often creating a layer of till (boulder clay) |
| Terminal moraine | A ridge of material deposited at the furthest point the glacier reached (the snout) |
Depositional Landforms
- Erratics — large boulders transported by the glacier and deposited far from their origin, often of a completely different rock type to the surrounding area (e.g. Norber Erratics, Yorkshire Dales — dark Silurian gritstones sitting on lighter limestone)
- Drumlins — smooth, elongated hills of glacial till, shaped like an upturned egg or spoon; the steep end (stoss) faces the direction the glacier came from; the gentle end (lee) tapers away. They often occur in groups called swarms (e.g. Ribble Valley, Lancashire). They indicate the direction of ice movement.
- Till (boulder clay) — unsorted glacial deposits left behind as the glacier melts; a mixture of clay, sand, gravel, and boulders
Land Use in Glaciated Upland Areas
Glacial landscapes are used for:
- Farming — mainly sheep grazing on steep valley sides; dairy/arable farming on flat valley floors with fertile glacial soils
- Tourism — walking, climbing, water sports on ribbon lakes (Lake District receives ~20 million visitors/year)
- Forestry — coniferous plantations on valley sides
- Reservoirs — U-shaped valleys are ideal for damming (e.g. Thirlmere, Lake District)
- Quarrying — slate, granite (controversy over landscape damage)
Conflicts
- Tourism vs. farming (footpath erosion, litter, traffic congestion, dog worrying sheep)
- Development vs. conservation (housing pressure vs. National Park protection)
- Quarrying vs. landscape preservation (jobs vs. visual impact and noise)