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 |
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.
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.