Glacial Landforms
- Created by: Tom
- Created on: 09-05-13 16:28
corries
- glaciers normally form on the side of a mountain peak this is where there is most accumulation and less ablation
- the side that gets least sun and coldest winds.
- snow collects in hollows and turns into ice. basal sliding with abrasion and plucking deepen the hollow into a corrie
- when the ice in the hollow is thick enough, it flows over the lip and downhill as a glacier. frostshattering and plucking steepen the back wall of the corrie.
corrie diagram
arete
- an arete is a steep-sided ridge - its formed when two glaciers flow in parrallel valleys. the glaciers erode the sides of the valley, which sharpens the mountain ridge in between them.
Pyramidal peak
- a pyramidal peak is a pointed mountain peak with at least three sides. it forms where three or more corries form back to back
Glacial trough
- (also called u-shaped valleys) are steep sifed valleys with flat bottoms. there formed by erosion of a v-shaped valley by a glacier. as the glacier erodes through the v-shaped valley it makes them deeper and wider
hanging valleys
- hanging valeys ae valleys formed by tributary glaciers - they erode the valley floor much less deeply because theyre smaller than the main glacier. so when the glaciers melt, the valleys get left at a higher level than the glacier trough formed by the main glacier.
truncated spurs
- truncated spurs are formed when ridges of land (spurs) stick out into the main valley are chopped off (truncated) as the main valley glacier moves past.
valley steps
- valley steps are steps in the glacial trough. they're formed when the glacier erodes the valley floor more deeply. this happens when another glacier joins it or where there's less resistant (softer) rock
Tarns
- tarns are lakes that form in corries after a glacier has retreated.
ribbon lakes
- ribbon lakes are long, thin lakes that form after a glacier retreats. they form in dips caused by erosion of bands of less resistant rocks, or behind dams of debris left by the glacier.
fjords
- fjords are long, deep inlets that form when a valley thats been erroded by a glacier is flooded by sea level rise after the ice has melted
roche moutonnee
- a roche moutonnee is a resistant (hard) mass of rock on the valley floor. the upstream (stoss) side is smooth, because it was smoothed by abrasion as the glacier went over. the downside (lee) side is steep and rough where the glacier plucked at it
roche moutonnee diagram
Lateral Moraine
- lateral moraine is a deposit of till left where the sides of the glacier were after it melts
medial moraine
- medial moraine is a deposit of till in the centre of the valley where two glaciers converge (two lateral moraines join together)
terminal moraine
- terminal moraine build up at the end of the glacier, and is deposited as semicircular hillocks of till
drumlins
- drumlins are half-egg shaped hills of till, up to 1500, long and 100m high. the upstream (stoss) end is wide and tall and the downstream (lee) end is narrow and low.
- nobody's really sure why drumlins are egg-shaped - it may be that till got stuck around a rock or little hill sticking out into the glacier. it may be that an original mound of dropped till got streamlined when the ice readvanced over it.
- drumlins often form in groups. there are drumlins in ribble valley in lancashire. there are also a whole bunch of drumlins under the water level in clew bay, ireland
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