Flashcards
Glaciers
Cards in this deck (29)
- 1Factors affecting the snow line?quantity of snow fall, steepness of slope, exposure of an area to sun + prevailing wind, type + velocity of wind, presence/ absence of large bodies of water, distance from equator
- 2How glaciers form...Zone of accumulation- snow added
Zone of ablation- snow removed - 3First stage of glacier formationsnow falls as flakes with a feathery structure that traps air
- 4Second stage...snow accumulates and becomes more compressed from layers above. Gradually turns into a more compact form of snow called 'neve' or 'firn'
- 5Third stage...continuos melting and refreezing fills gaps in the snow
- 6Alpine glacier/ warm glacier?Smallest type, retreats in summer and advances in winter due to temps, glacier moves quickly due to meltwater, they erode, transport and deposit
- 7Polar glacier/ cold• Found in areas below 0 degrees so little melting/ movement
• Ice sheets also smaller ice caps/ ice fields
• Movement is slower as they are frozen to beds and move internally
Less erosion, transportation and deposition - 8Valley glacierlarge mass of ice flows down a previously smaller valley in periglacial area
- 9Piedmont glacierlarges lobes of ice which forms where valleys ice spreads out as it reaches lower areas
- 10Niche glaciersmall patches of glacier ice on upland slopes
- 11Ice capshuge flattened dome shaped ice that form on high plateaus, similar to ice sheets but smaller than 50,000km2, more than that =ice sheets
- 12ice shelfextension of an ice sheet that reach out over sea, can be up to 1000km thick
- 13Why does a glacier move at different speeds?Different parts of glacier move at different speeds due to different degrees of friction, because of this the top (brittle + cracks) forms crevasses
- 14Main factors affecting ice movement?Friction, ice temp, mass, meltwater and gravity
- 15type and rate of movement in a glaciercompressional flow, internal flow, basal flow, rotational flow, extensional flow, crevasses
- 16why does the bottom layer of glacial ice turn blue/ green?due to no air
- 17how do glaciers move?weight of ice due to gravity, temp, melt water, mouldable lower layer (ductile zone), removes obstacles by becoming attached to constant freezing & thawing outer layers
- 18Basal flow/ sliding?large blocks of ice move in short jerks, melt water lubricates base formed by pressure of weight (pressure melting), it reduces friction, where obstacle meltwater allows glacier to flow over and then refreezes
- 19Internal flow/ internal deformationslow movement within glacier, ice crystals slip + slide over each other(gravity), surface ice moves faster= crevasses, takes place in all glaciers
- 20Creepstress builds due to obstacle in path, flows around it and erodes sides
- 21Surgesexcessive melt water under glacier= rapid movement (250-300 m per day)
- 22extended flowvalley becomes steeper, ice flows faster + becomes thinner as it stretches,= crevasses and less erosion
- 23Compressing flowvalley becomes less steep, ice slows + thickens then piles up. Crevasses may close and lots of erosion
- 24Rotational flowcurved movement back and forth, important in formation of corrie
- 25INPUTSsnow + rain, avalanches along valley side, eroded sediment picked up by ice
- 26TRANSFERS STORED PROCESSESIce flow
Ice
Erosion, transportation & deposition - 27OUTPUTSwater vapour, melt water, sediment deposited, calving (ice bergs breaking off)
- 28Zone of accumulationoccurs in upper reaches of glacier where yearly additions of snow exceeding losses due to melting + evaporation. Surface zone covered in snow. INPUTS EXCEED OUTPUTS.
- 29Zone of ablationlosses of snow + ice from melting, evaporation + sublimation are greater than the additions. OUTPUTS EXCEED INPUTS- NET LOSS OF ICE
Information
- Description
- A Levels Geography (Cold Environments ) Flashcards on Glaciers, created by Alice Kimpton on 21/09/2015.
- Created by
- Alice Kimpton
- Views
- 167
- Rating