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glaciated landscapes sg2 (after glaciation: (winding valley becomes a…
glaciated landscapes sg2
pressure release: upper layers are removed by erosion, rock left behind can expand, if rock has layers they open, now easier for water to enter then freeze-thaw occurs
slides: occur when mass of material moves downwards along a straight line slip plane until it impacts the bottom of a slope. may occur from steepening of valley sides - erosion
slumps. occur where material slips down a curved slip plane + rotational movement leaves series of 'steps' behind. - common in weaker rocks
rockfalls: occur on steeps (over 70 degrees) bare rock detached from the slope by physical weathering processes and fall to the foot - gravity - forms scree
polising: rock flow carried as subglacial debris. polishes rock as it travels over, and when rock flour is present
rock flour: glacier moves landscape, rock is polished. glacial debris is worn down by this process forming the flour
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positive feedback: plucking, small rocks in glacier are removed = more subglacial debris - more pressure release - meltwater seeps in cracks from pressure release back to plucking
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englacial debris: carried within the glacier. comes from surface debris fallen down a crevasse/or sunken into the glacier from localised pressure melting
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lodgement till: deposited material by advancing glacier due to basal melting. can be enhanced by localised pressure melting of particles under weight and pressure
ablation till: material deposited as ice melts away from retreating/stagnant glaciers. (coasrser than lodgement till) most glacial depositional landforms are of this type; typicllay angular, unsorted, unstratified and no orientation
glacial trough: if glacier becomes large enough over time, it can flow over the lip of corrie and follow the line of a river valley down the mountain side. v-shaped cross-section of the river valley is eroded forming a gt
in the upland area v-shaped profiles are deepened by erosion along the river. the river follows the winding course around the hillsides forming interlocking spurs
after glaciation:
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interlocking spurs are removed by erosive force of the glacier, forming truncated spurs
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hanging valley: one main valley and another. smaller = less erosive power. larger = more so deepening occurs
rock bars are present with hard rock, rock basing is present with soft rock. rock bars = extending flow. compressing flow = basins with more erosion