Glacial erosion + Deposition landforms Flashcards
1
Q
Glacial erosion + Deposition landforms
A
- Corries
- Aretes
- Glacial troughs
- Hanging valleys
- Truncated Spurs
- Roches Moutonnees
- Drumlins
- Erratics
- Moraines
- Till plains
2
Q
Corries
A
- Nant Ffrancon Valley
- Semi-circular hollow, high up at the head of the glacial valley
= Preglacial times = snow collects in hollows - Layers of snow compressed = Firn + Ice
3
Q
Processes of Corries
A
- Nivation = frost shattering, freeze-thaw and solifluction (top soil thaws during summer)
- Plucking = steepens backwall
- Rotational movement - meltwater due to pressure, abrades floor = deepens
- Rock lip = erosion decreases
- Tarn = ice melts
4
Q
Aretes
A
- Wast water - Lake district
- Narrow, knife-edged ridge w/ steep sides in glaciated regions
5
Q
Processes of aretes
A
- Adjacent corries erode backwards or sideways towards each other = steep
- Erosion of backwall + plucking = loosens material
- Frost shattering
6
Q
Glacial troughs
A
- Wast water - Lake District
- Glaciers flow into pre-existing river valleys
- Widen + Deepen = steep sides and wide flat base.
7
Q
Processes of glacial troughs
A
- Abrasion and plucking
- Freeze-thaw weathering on sides + Plucking
- Interlocking spurs bulldozed = steep sides
8
Q
Hanging valleys
A
- Milford Sound, New Zealand
- Tributary glaciated valley perched above level of main glaciated valley floor
- Former tributary valleys occupied by ice = less erosive power
9
Q
Processes of hanging valleys
A
- Main valley ice has gone = tributary valley is cut off by truncated spurs of main valley
- Tributary valley left hanging = waterfall
10
Q
Truncated spurs
A
- Blencathra, Lake District
- Glaciers straighten valley, cutting off spurs and leaving cliffs
11
Q
Processes of truncated spurs
A
- Ice flow concentrated in valley = erodes floor and sides
= Abrasion and Plucking - Freeze-thaw weathering + plucking =weaken rocks
= Abrasion
12
Q
Roches moutonnes
A
- Central Park, New York
- Isolated rock = 5-30m tall
- Smooth on on eside and jagged on the other
13
Q
Processes of roches moutonnes
A
- Glaciers don’t erode floor in uniform way = more resistant rocks not eroded
- Obstacle, pressure increases = melting
- Basal sliding = Abrade
- Striations
Lee side = pressure falls, water refreezes + plucking
14
Q
Drumlins
A
- Barnoldswick, UK
- Smooth, elongated mounds of till
- Long axis - parallel to direction of ice movement
- Stoss (steep) = faces direction from which the ice came
- Lee = gentler, streamline appearance
= Till and fluvial glacial sediments
15
Q
Theory of Drumlins
A
- Subglacial formation
- Ice become overloaded with material, reducing capacity of glacier
- Once deposited = moulded by later ice movement
