glaciated landscapes 2

Question 1

weathering and erosion

Answer 1

Weathering: the breaking down or dissolving of rocks and minerals in situ (still) ftw, tree roots.
- pressure release: weight of overlying ice in glacier is lost due to melting, underlying rock expands and fractures.
- organic acids: decomposition occurs causing soil water to become more acidic and react with minerals.
- carbonation: rain combines with dissolved CO2 from atmosphere to produce weak carbonic acis, reacts with calcium carbonate creating calcium bicarbonate.
Erosion: wearing away of rocks as the glacier advances e.g. abrasion, plucking.

Question 2

transportation, mass movement and deposition

Answer 2

Transportation: material is either supraglacial (carried on glacier surface), englacial (carried within glacier) or subglacial(transported at the base).
Mass movement: downslope transportation of material under gravity: sliding (material moves downwards along a straight line slip plane), slumping (material slips down curves plane) or rockfall (caused by continuous FTW.
Deposition: glaciers deposit their load as till: material deposited directly by ice, or as fluvial material: deposited my meltwater. Till is angular, unsorted, no orientation, not stratified, not sorted.

Question 3

erosional features

Answer 3

1 - corries: nivation at a small hollow, snow accumulates, through diagenesis becomes ice and moves due to gravity. FTW, plucking and abrasion deepen hollow creating steep back wall and rock lip.
2 - arete: occurs when 2 back to back corries erode (via FTW, plucking etc) backwards into mountain creating a steep narrowed knife edge ridge. Edge is continuously sharpened via FTW which also causes scree slopes.
3 - pyramidal peak: formed when 3 or more corries erode backwards. Plucking, abrasion, FTW cause it to deepen and sharpen. Summit is continuously sharpened via FTW.

Question 4

erosional features 2

Answer 4

4: glacial trough: large amounts of meltwater and subglacial debris produce greater erosive power, erosion takes place. When ice recreates a ribbon lake is left in the valley.
5: Roche moutonees - these are masses of more resistant rock on the floor of a glacial trough. Lee side: gentle slope and stoss: steep side.

Question 5

moraine

Answer 5

Terminal moraine: marks the maximum extent of glacier, ice melts at snout and deposits debris. This is a ridge f till extending across a glacial trough.
Recessional moraine: forms during episodes of retreat, continues to retreat and deposit creating stages of till between the snout and terminal moraine. it is a series of ridges running t across the glacial trough parallel to one another.
Lateral moraine: material is loosened by FWT, debris is carries at the side and top of glacier. This is a ridge of till running along the edge of a glacial valley.

Question 6

till sheets, drumlins and erratic’s

Answer 6

1 - till sheets; an extensive flat plain of unsorted drift created when large quantities of till are depostied as the glacier retreats.
2 - drumlins: a streamlines hill of subglacial material. Glacier melts and loses energy depositing material. Glaciers still move so drumlins have a streamline shape reflecting the direction of the glacier. Stoss end: steep bit, lee slope: the slope. Material is unsorted, unstratified and angular.
3 - erratic’s: large boulders foreign to the local geology: boulder are plucked from one place and transported hundreds of km to another, when ice melts they are deposited in an area with different geology.