Location, Formation and Climate of a Glaciated Landscape

Worked Example: Calculating Temperature Range

An exam may require you to calculate the temperature range from a climate graph.

• Formula: $\text{Range} = \text{Maximum Temperature} - \text{Minimum Temperature}$

• Step 1: Read the data. July max is $16^\circ\text{C}$ and January min is $3^\circ\text{C}$.

• Step 2: Substitute into the formula: $16 - 3$

• Step 3: Final answer with units: $13^\circ\text{C}$.

Worked Example: Calculating Lapse Rate

Temperatures decrease by $1^\circ\text{C}$ for every $100\text{m}$ of altitude gained.

• Step 1: Identify sea level temperature and target altitude. Sea level = $8^\circ\text{C}$, Snowdon summit = $1,085\text{m}$.

• Step 2: Calculate temperature drop: $1,085 \div 100 = 10.85^\circ\text{C}$ (round to $10.8$ or $10.9$ depending on specific exam guidance).

• Step 3: Subtract from sea level temperature: $8 - 10.8 = -2.8^\circ\text{C}$.

Glacial Formation Processes and Landforms

You can easily snap a brittle twig, but try breaking solid rock with just frozen water. During the Pleistocene Ice Age (peaking 20,000 years ago and ending 11,500 years ago), ice sheets up to 1 km thick carved the UK's uplands.

The growth or retreat of a glacier is determined by the glacial budget:

If accumulation (snow/ice inputs) exceeds ablation (melting/evaporation), the glacier advances. As it moves, it shapes the landscape via two main erosional processes:

• Plucking: Meltwater at the glacier's base freezes into cracks in the bedrock. As the ice moves, it tears chunks of rock away.
• Abrasion: Rocks embedded in the ice act like sandpaper, grinding the bedrock and leaving scratches called striations.

The Sequence of Corrie Formation:

1. Snow accumulates in a sheltered north-facing hollow.
2. Compaction turns snow into glacial ice.
3. Rotational slip (circular ice movement) deepens the hollow floor, while plucking steepens the back wall.
4. Abrasion deepens the base, leaving a rock lip at the edge.
5. Post-glaciation, the ice melts and the hollow fills with water to form a tarn (e.g., Red Tarn on Helvellyn).

Other erosional landforms include U-shaped valleys (e.g., Langdale), arêtes (e.g., Striding Edge), and pyramidal peaks (e.g., Helvellyn). Depositional landforms include ribbon lakes (e.g., Windermere) and drumlins (e.g., Vale of Eden).

Factors Driving Post-Glacial Landscape Change

A landscape is never truly finished; it is constantly being reshaped by both natural forces and human activity. The Lake District covers 2,362 km² and is a sparsely populated (18 people per km²) "paraglacial" environment, meaning it is modified by non-glacial processes today.

Physical Drivers:

• Weathering: Temperature fluctuations around 0°C cause freeze-thaw weathering. Water enters rock cracks, freezes, and expands by 9%, eventually shattering the rock to form active scree slopes (e.g., Wasdale Screes).
• Solifluction: In summer, the active layer of soil thaws. The meltwater can NOT drain away because the frozen permafrost beneath it is impermeable. The saturated soil loses cohesion and flows slowly downhill under gravity (even on 1-5 degree slopes), forming solifluction lobes. If this occurs specifically over a permafrost layer, it is called gelifluction.
• Rivers & Climate Change: Small misfit stream/rivers flow through massive U-shaped valleys. They did NOT and could NOT carve these valleys themselves, but increased storm frequency (e.g., Cumbria floods 2009/2015) is accelerating modern river erosion.

Human Drivers:

• Tourism: The Lake District receives 15.8–18.14 million visitors annually, bringing in up to £2.1bn. However, 4 million walkers average 6km each, causing severe footpath erosion, soil compaction, and subsequent gullying.
• Farming: Extensive sheep farming (e.g., Herdwick sheep) on steep relief causes overgrazing, destroying vegetation cover and accelerating soil erosion.
• Forestry & Water Supply: Large coniferous plantations (Sitka Spruce) are planted by the Forestry Commission to provide timber and stabilize soils. Additionally, glaciated valleys are flooded for water storage; Haweswater Reservoir supplies 25% of North West England’s water.