Glacial Landscapes in the UKTopic Summary
Knowledge Organiser: Glacial Processes — Erosion, Transport, Deposition
This topic summary covers Knowledge Organiser: Glacial Processes — Erosion, Transport, Deposition within Glacial Processes for GCSE Geography. Revise Glacial Processes in Glacial Landscapes in the UK for GCSE Geography with 15 exam-style questions and 20 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 17 of 17 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 17 of 17
Practice
15 questions
Recall
20 flashcards
Knowledge Organiser: Glacial Processes — Erosion, Transport, Deposition
Key Terms
- Accumulation: Addition of snow/ice to glacier (upper zone)
- Ablation: Loss of ice by melting, sublimation, calving (lower zone)
- Firn: Granular intermediate stage between snow and glacier ice
- Basal sliding: Glacier movement over a meltwater film on bedrock
- Plucking: Glacier freezes onto and tears out bedrock blocks
- Abrasion: Embedded rocks grind bedrock — produces striations + rock flour
- Till: Unsorted, unstratified sediment deposited directly by ice
- Fluvioglacial: Sorted, stratified sediment deposited by meltwater
- Moraine: Ridge/accumulation of till deposited by a glacier
- Erratic: Boulder carried far from its source by a glacier
- Striation: Scratch in bedrock showing direction of past ice movement
Glacial Processes at a Glance
- Freeze-thaw: Water → freezes → expands 9% → shatters rock → angular debris
- Plucking: Meltwater refreezes in joints → glacier tears out blocks → jagged surface
- Abrasion: Embedded rocks drag over bedrock → striated, polished surface + rock flour
- Transport positions: Supraglacial (angular) → Englacial (sub-angular) → Subglacial (rounded + striated)
- Till: Unsorted (all sizes mixed) — water does NOT sort
- Fluvioglacial: Sorted + stratified — water DOES sort by particle size
Moraine Types
- Terminal: Furthest advance — ridge across valley
- Recessional: Pause during retreat — ridge up-valley of terminal
- Lateral: Along valley sides — freeze-thaw debris from valley walls
- Medial: Centre of glacier — two lateral moraines merge at tributary junction
- Ground: Across valley floor — till deposited beneath moving ice; may form drumlins
Must-Know Facts and Evidence
- Water expands 9% in volume when it freezes (freeze-thaw pressure)
- Freeze-thaw exerts up to ~2,000 tonnes/m² pressure on rock
- Striations in bedrock prove direction of past ice movement
- Rydal Cave, Lake District — striations prove ice moved southward
- Athabasca Glacier has retreated ~1.5 km since 1890 (negative budget)
- Rhône Glacier has retreated ~3 km since 1870 — photographic record
- Norwegian erratics on Yorkshire coast — evidence of British Ice Sheet extent
- Roche moutonnée: stoss side = smooth (abrasion); lee side = jagged (plucking)
- Ice always flows forward — "retreat" means snout moves up-valley as ablation > accumulation
- Mnemonic: ICE CAPS (Ice, Cracks, Erosion, Carrying, Abrasion, Plucking, Sorted/Unsorted)
Common Mistakes
- Confusing plucking and abrasion: Plucking tears out rock blocks when meltwater refreezes in joints, leaving a jagged surface; abrasion uses embedded debris to grind the bedrock smooth, producing striations and rock flour — never describe both as "scraping"
- Saying glaciers "move back" when retreating: Ice always flows forward — "retreat" means the snout position moves up-valley because ablation exceeds accumulation; the ice itself still moves downslope
- Confusing till and fluvioglacial deposits: Till is unsorted and unstratified (deposited directly by ice); fluvioglacial sediment is sorted and stratified (deposited by meltwater) — the sorting tells you the agent of deposition
- Not naming UK evidence: Always support process explanations with named UK examples — Rydal Cave striations (Lake District) prove past ice direction; Norwegian erratics on the Yorkshire coast prove the extent of the British Ice Sheet