Glaciation Flashcards
1
Q
4 periglacial landforms
A
Ice wedges
Patterned ground
Pingos
Loess
2
Q
Ice wedge polygons
A
- downward narrowing masses of ice between 2-3m wide at base and extend below ground up to 10m
- formed by refreezing of active layer during winter causing soil to contract and cracks open. During melting in summer cracks fill with meltwater and sediment then freeze the following winter, widening and deepening the crack
3
Q
Patterned ground
A
- covers features like: nets, polygons, steps and stripes
- formed by movements resulting from frost action:
- frost push caused by hydrostatic pressure propels stone upwards, whilst frost heave causes stones to migrate outwards to form circles - this provides basis for all patterns
- up doming of circle crested by heaving mean larger stones roll outwards due to gravity, leaving finer sediment in centre
- as a result, a stone polygons are elongated into nets/stripes which has clear relationship between type of patterned ground and slope angle
- beyond 30 degrees angle, patterned ground can no longer form and rock avalanches may occur
4
Q
Pingos
A
-ice cored hills between 30-70m high and diameter between 100-500m
- growth of ice cores forces up overlying sediments, causing dilation cracks, once the ice core is exposed it melts which causes top of Pingo to collapse, forming a crater
- most Pingos circular in shape
- smaller Pingos tend to have curved top
- large usually have exposed ice at top and melting of this often forms crater which are sometimes filled with water to cause a lake
5
Q
7 macro features (<1km)
A
- Cirque/corrie/cŵn
- Arête
- Pyramidal peak
- Truncated spur
- U-shaped valley
- Hanging valley
- Ribbon lake
6
Q
4 meso features (10m-1km, usually found in macro features)
A
- Whalebacks
- Crag and tail
- Rochester moutonneees
- Knock an’ Lochan
7
Q
3 micro features (few metres and less)
A
- Chatter marks
- Striations
- Crescentic gouges
