Glaciers
glaciers
- Created by: Hayley Williams
- Created on: 07-05-11 15:46
key words
Fluvioglacial = processes and landforms associated with the action of glacial melt water
Glacier = tongue shaped mass of ice moving slowly down a glacier
Ice Sheet = body of ice covering an area of at least 50,000 km2
Ice Cap = body of ice covering an area below 50,000kmw2
Periglacial = process and landforms associated with the fringe of an area near to an ice sheet or glaciers
Tundra = climatic an vegetation type
Temperate Glaciers = melt in summer, releasing huge amounts of melt water acting as a lubricant, reducing friction
Polar Glaciers = occur in areas where the temperature is permanently blows 0 degrees, slow movement as they are frozen to their beds
Compressing Flow = occurs when there is a reduction in the gradient of the valley floor
Extending Flow = occurs when the valley gradient becomes steeper
Basal Flow = as glacier moves over ice their is friction
Surges = occur when there is a build up of meltwater under the glacier
Internal Flow = occurs when ice crystals orientate themselves in the direction of the glaciers movement
Creep = occurs when stress builds up with a glaicer allowing ice to behave as a flow
Rotational Flow = occurs within a glacier where ice moving downhill can pivot at a point productin rotational movement
Ablation = melting
Zone of accumulation = inputs exceed outputs, mass is gained
Zone of ablation = outputs exceed inputs, mass is lossed
Equilibrium = separates net loss from net gain
Net Balance = difference between the total accumulation and total ablation in one year
Glacial Advance = supply exceeds losses and the snout moves down the valley
Glacial Retreat = glacier shrinks in size and snout moves up the glacier
Abrasion = occurs when the material that the glacier is carrying rubs away on the valley floor or sides
Plucking = glacial freezes onto and into rock outcrops as the ice moves forwards it pulls away massed of rock, leaving a jagged landscape
Freezethaw action/ frost shattering = occurs in areas where the temperature rises in that day but decreases as night. Water with enters the cracks freezes and expands by 9%
Nivation = process that operates underneath a patch of snow
Corrie = arm chair shaped hollow with a steep back wall and often contains a small lake
Arete = when 2 corries like back to back or side to side, enlargement occurs leaving a narrow steep ridge
Pyramidal Peak = when 3 or more corries develop, sharp appearence due to frost shattering
Glacial Trough = U shaped valley, straighten, widen and deepen
Trough end = glacial valley end abruptly at their heads with a steep wall
Ribbon Lakes = rock basins filled with these
Fjord = form when sea levels rise
Hanging Valleys = at the side of the main valley
Truncated Spurs = areas of land projecting from the river valley sides are removed by the glacier
Rouch Mountatins = small areas of rock on the valley floor are not completely removed
Supra Glacial = transported on the surface of the glacier
Englacial = buried within the glacier
Subglaical = found at the base
Till/boulder clay = material that is depostitied directly by the ice
Ablation Till = produced at the snout when the ice melts, producing terminal, push and recessional moraines
Drumlin = rounded hill
Stoss = steeping end of drumlin
Lee = sloping end of drumlin
Swarms = grounds of drumlins
Moraines = lines of series of mounds of material, running across the glacial valley
Terminal Moraine = found that the end/snout of the glacier
Recessional Moraine = series of moraines that form along the valley, marking points where retreat halted
Stratified = layered
Eskers = deposits made by subglacial streams, have long ridges and are sinuous
Kames = mounds of fluvioglacial material
Outwash Plains = found at the front of the snout
Permafrost = permanetly frozen ice
Continuous Permafrost = found in coldest regions, no melting occurs
Discontinuous Permafrost = occurs in slightly warmer regions, there are gaps in the permafrost
Sporadic Permafrost = found when the annual temperature is around freezing point
Solifucation = when the active layer thaws in summer, excessive lubrication reduces the friction between soil particles
Frost Heave = as active layer starts to refreeze, ice crystals begin to develop
Groundwater freezing = where the permafrost is thin, water is able to seep through the upper layers of the ground and then freeze
Inputs: snowfall, avalanches, accumulation
Stores: glacier ice, melt water
Throughputs: ice movement, flooding
Outputs: melting, evaporation, and ablation
Altitude: height of thing above reference level
latitude: angular difference between north and south equator measured in degrees
Glacial budget = balance between glacial accumulation and glacial ablation
accumulation zone has a positive net balance as accumulation exceeds ablation and the ablation zone has a negative net balance as melting exceeds accumulation
Crushing is the weight of the overlying rock that caused the weak rock to break up
Erosion factors include
- debris which is the quantiy of rock debris below the glacier
- velocity, the higher velocity will create stress along the bed
- cold based and frozen to their beds
- warm based allow basal sliding and abrasion to occur
- ice thickness, the thicker the ice the more effective that abrasion is
The main processes of fluvioglacial erosion are attrition, abrasion, corrosion, hydraulic action, caviation
The main processes of fluvioglacial depotition are: meltwater discharge decreases causing the loss of energy, the meltwater is deposited. Heavy particles will be dropped first, deposits are also found in layers
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