Landscapes
Geography: Edexcel A Level, topic 2.4.1
Glacial Landscape Processes and Scales
Many areas of the world contain a variety of old glacial and periglacial environments. They create a number of distinctive landscapes in both upland and lowland areas that can be used to study the extent of previous ice cover.
Glacial landscape processes
- Glacial erosion is the removal of rock material by ice through abrasion, plucking and meltwater flow from ice margins.
- Glacial debris entrainment is sediment being incorporated into glacial ice and carried along with the ice.
- Glacial sediment transport - sediment on top of (supraglacial), within (englacial) or at the base (subglacial) of ice being moved.
- Glacial deposition is when material is dropped from the ice at the margin or the base of a glacier and deposited, or deposited from meltwater.
Glacial landscape scales
- Landforms that vary in scale provide evidence of former glacial and periglacial conditions. Some landforms you may find at different scales (from big to small) are:
- Macro-scale - corries (cirques), aretes, pyramidal peaks, glacial troughs, ribbon lakes, till plains, end-moraines, knock and lochans.
- Meso-scale - roches moutonnees, drumlins, kames, eskers, kettle holes.
- Micro-scale - striations, chattermarks, erratics.
Glacial Landform Locations
Many areas of the world, although several are now ice-free, contain a variety of relict glacial and periglacial environments.
Subglacial and ice-marginal
- Subglacial areas would have been covered by either warm or cold-based ice for thousands of years at a time and dominated by the action of erosion and erosional landforms.
- Ice-marginal areas were at the edges of ice sheets and valley glaciers. This was where deposition from ice was dominant.
Proglacial and periglacial
- Proglacial areas occur in front of ice masses where meltwater deposition and wind action on glacially eroded sediments took place.
- Periglacial areas had no ice cover but were underlain by permafrost.
Glacial and periglacial Britain
Test yourself on Landscapes
What do we call sediment carried on top of a glacier?
Which of these are examples of macro-scale glacial landforms?
What kind of areas had no ice cover but were underlain by permafrost?