This comparison covers Till vs Fluvioglacial Sediment — and Glacial vs Fluvial Transport 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 10 of 17 in this topic. Use this comparison to connect the idea to the wider topic before moving on to questions and flashcards.
⚖️ Till vs Fluvioglacial Sediment — and Glacial vs Fluvial Transport
Two comparisons that examiners frequently test: the difference between how ice and meltwater deposit sediment, and the difference between glacial and river transport processes.
Till vs Fluvioglacial Sediment
| Characteristic | Till (Glacial) | Fluvioglacial (Meltwater) |
|---|---|---|
| Deposited by | Ice directly | Meltwater (water) |
| Sorted? | Unsorted — all particle sizes mixed together | Sorted — larger particles deposited first, finer particles carried further |
| Layered? | Unstratified — no layers | Stratified — deposited in distinct horizontal layers |
| Particle shape | Angular to sub-rounded (subglacial till may be striated) | Rounded (water transport rounds edges) |
| Landforms | Moraines, drumlins | Eskers, kames, outwash plains |
Plucking vs Abrasion: A Direct Comparison
| Characteristic | Plucking | Abrasion |
|---|---|---|
| How it works | Ice freezes onto rock joints; glacier tears blocks away | Rock debris embedded in ice grinds against bedrock |
| Surface left behind | Jagged, irregular, stepped | Smooth, polished, with striations |
| Debris produced | Large, angular blocks | Fine rock flour + striated pebbles |
| Best conditions | Well-jointed rock; fast-moving temperate glacier | Lots of basal debris; high ice velocity; thick ice |
| Evidence in landscape | Roche moutonnée lee face; crag-and-tail features | Striations; polished rock surfaces; rock flour in meltwater |
Practice questions for Glacial Processes
What term describes the zone in a glacier where ice is lost through melting, evaporation and calving?
Explain how abrasion erodes the valley floor beneath a glacier.