2.4 Flashcards
Erosion
The removal of weakened material by glacial ice includes plucking, abrasion, crushing and basal melting
Entrainment
Small rock fragments are trapped (entrained) by basal ice freezing around them and apply suffice drag it pull them along
Transport
Rock debris is transported on the ice surface (supra-glacial) within the ice (englacial) and at the base of the ice (subglacial)
Deposition
Till is sediment deposition directly by glacier ice. Fluvio-glacial debris is deposited by glacial meltwater
Abrasion
-Individual stones which lead to micro-feature such as striations and chatter marks
Plucking
- Glacial quarrying
- Quarrying is a two-stage process with the initial widening of the joints by fracture and the subsequent entrainment of the loosened material
- Plucking is dependent on the rock type
Fracture and traction
-Crushing effect of the weight of moving the ice passing over the rock
Dilation
-Occurs as overlying material is moved, causing fractures in the rock parallel to erosion surfaces such as the bedrock adjusts to the unloading
Meltwater erosion
-Mechanical and chemical, glacial meltwater can dissolve minerals and carry away the solutes
Supraglacial
Sources include material falling from hillsides being washed or blown on to the glacier from the surrounding land, plus atmospheric fall-out such as volcanic ash
Subglacial
Material eroded from the glacier bed and the valley walls, material frozen to the base from subglacial streams, as well as englacial material that has worked its way down through the glacier or ice sheet
Macro-scale
Ice sheet eroded knock and lochan landscapes, cirques, arētes and pyramidal peaks, glacial troughs, ribbon lakes, till plains, terminal moraines, sandurs
Meso-scale
Crab and tail, roches moutonnées: drumlins, Kames, eskers and Jamie terraces, kettle holes
