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Flashcards

Glaciers - Earth Processes and Landforms

Sammie Bradley Environment Geography Degree BSc English 72 cards

Cards in this deck (72)

  1. 1What is a Glacier?A large mass of ice that moves down slope under it's own weight
  2. 2What is the cryosphere?Cryosphere - Earth's sphere of ice
  3. 3Identify 5 types of glacier1. Valley Glacier
    2. Tidewater Glacier
    3. Ice Sheets
    4. Ice Caps
    5. Sea Ice
  4. 4How do glaciers differ from ice caps/sheets?Glaciers are constrained by topography where ice caps and sheets over lie topography
  5. 5How is most glacial mass lost?Calving into the sea
  6. 6How long ago was the last glacial maximum?21,000 years ago
  7. 7How much ice has melted since the Devensian?50 million km2
  8. 8Which cycles are the main controls from the glacial/interglacial periods?Milankovitch cycles
  9. 9Describe and state the duration of eccentricityChange in shape of earth's orbit around the sun - 100,000 years
  10. 10Describe and state the duration of obliquityChange in the angle of earth's tilt - 37,000 years
  11. 11Describe and state the duration of precessionChange in direction of earths tilt - 23,000 years
  12. 12Are the milankovitch cycles alone enough to drive glacial/interglacial periods?No, feedback mechanism are needed
  13. 13Identify 4 feedback mechanismsEustatic change
    Isostatic change
    CO2
    Ice coverage / Albedo
  14. 14What is glacier mass balance?Annual measurement of the balance of accumulation and ablation
  15. 15Define the following terms: - Accumulation -AblationAccumulation - Growth of a glacier through increased snowfall and precipitation
    Ablation - Shrink of a glacier through increased melt and calving
  16. 16How do glaciers form?- Layers of snow
    - Lower layer compressed
    - Oxygen forced out
    - Becomes solid ice
  17. 17What is the fern line?The equilibrium line, mid point of accumulation and ablation
  18. 18What can the movement of the fern line tell us?Whether a glacier is growing or shrinking
  19. 19How do glaciers move?Sliding and Deformation
  20. 20What 3 factors affect glaciers rate movement?Bed roughness
    Lubrication (water) present
    Slope angle
  21. 21What is an ice stream?A section of the glacier that moves faster than the surrounding ice
  22. 22Define stressThe amount of force per unit area
  23. 23Thicker and Steeper Ice will flow....Faster
  24. 24Glaciers with more extreme ablation and accumulation will flow....Faster
  25. 25What is regelation?Friction around an obstruction generates heat. Ice melts. Flows around obstruction and refreezes.
  26. 26What is creep?The internal deformation of crystals in ice
  27. 27Identify 5 factors that influence the rate of creepBubbles
    Impurities
    Orientation of crystals
    Temperature
    Crystal size
  28. 28What is the formula for glacial movementGlacial Movement = Creep + Sliding + Sediment Deformation
  29. 29How fast do glaciers usually move?10 - 100 mm/y
  30. 30How fast is the quickest glacier?7000 mm/y
  31. 31Which factors has the most control over glacial movement?Lubrication present (Water)
  32. 32Describe the following locations: Supraglacial Englacial SubglacialSupraglacial - Glacier surface
    Englacial - Within glacier
    Subglacial - Glacial base
  33. 33Identify 3 heat sources of glacial meltingSolar energy
    Geothermal heat
    Frictional Heat
  34. 34What other source can add to meltwater pools?Rainfall
  35. 35Ultimately, where does all melt water end up?Beyond the snout of the glacier into rivers/seas/oceans
  36. 36What 3 industries will be particularly interested in glacial hydrology?Industry
    Hydro power
    Hazard management
  37. 37Why is glacier hydrology important?- Holds 75% of our freshwater
    - Major role in controlling landscape
    - Represents glacier mass balance
  38. 38How does supraglacial water reach the glacier baseFlow channels and vertical shafts/tunnels
  39. 39Where do drainage channels usually form?Along planes of weakness e.g. Crevasses
  40. 40What 3 things control glacial tunnels?Ice pressure and deformation
    Frictional melting of flowing water
    Discharge of meltwater
  41. 41Identify two types of subglacial drainageDiscrete and Distributed
  42. 42How does distributed drainage work?- Thin film of water between rock and ice
    - <1mm thick
    - Stores in cavities and flows between
  43. 43How can distributed drainage change with increased discharge?1. Path between cavities is eroded into channels to create discrete drainage areas
    OR
    2. Water pressure lifts ice and causes transport surges
  44. 44Name and describe the difference between the 2 channels in discrete drainageRothlisberger (R) channels - cut into ice
    Nye (N) channels - cut into sediment
  45. 45What is a proglacial lake?A meltwater lake that forms at the front of a retreating glacier that is damned by terminal moraine
  46. 46What is the definition of erosion?Process by which materials are removed from earth’s surface
  47. 47Why is our knowledge of glacial erosion so poor?1. Accessibility is poor and so it’s difficult to make direct measurements
    2. Glacial systems are very complex and interlinked so difficult to untangle
  48. 48Give 3 examples of glacial erosion1. Bedrock crushing
    2. Plucking/Quarrying
    3. Abrasion
  49. 49What is Bedrock crushing?Fracturing of bedrock from the weight of overlying ice
  50. 50What force produces the fracturing?Normal stress
  51. 51What’s the equation for Normal stress?Normal Stress = Thickness x Gravity x Ice Density
  52. 52What is plucking?The incorporation of loose debris at the base of a glacier as it moves
  53. 53What is glacial abrasion?The scouring of a bedrock by loose debris in the glacier base
  54. 54Identify 3 products of abrasionScouring
    Polishing
    Rounded of debris
  55. 55Under what conditions is glacial abrasion most effectiveLots of debris
    Harder tools
    Rapid movement
    Thick ice
    High pressure
    Meltwater flushing products
  56. 56Identify 4 chemical erosion processes that may occur in glaciated environmentsCarbonation
    Hydrolysis
    Oxidation
    Dissolution / Corrosion
  57. 57Under what conditions may chemical erosion be more effective?1. Influx of fresh water
    2. Freshly eroded surfaces
    3. Dissolved CO2
    4. Increased acidity
  58. 58How do glacier erosion rates differ between temperate and polar glaciers?Temperate glaciers 1mm/y
    Polar glaciers 0.01mm/y
  59. 59How is glacial debris transported when it falls into the accumulation or ablation zone?Accumulation - En or Subglacial
    Ablation - Supraglacial
  60. 60How does lodgement till form?When the forces at the base of the glacier are no longer sufficient to move the debris
  61. 61How does meltout till form?When debris is dropped from the glacier as it melts
  62. 62How does flow till form?When finer sediment mixes in with glacial meltwater to form a mobile slurry
  63. 63State the size and give 2 examples of Microscale landforms<1m
    Microcrag and tails
    Friction cracks
  64. 64State the size and give 3 examples of Mesoscale landformsBetween 1m - 1km
    Drumlin
    Roche Moutonee
    Meltwater channels
  65. 65State the size and give 3 examples of Macroscale landforms>1km
    Cirque
    U Shaped Valley
    Fjord
  66. 66Identify 3 ways in which moraines can be formed1. Glaciotechnic - pushed/placedby glacier
    2. Dump - fallen off glacier sides/front
    3. Ablation - melted out with retreat of ice
  67. 67What are Icehouse conditions?Periods of greater ice coverage
  68. 68What are Greenhouse conditions?Periods of little/no ice coverage
  69. 69Are we currently in an icehouse or greenhouse state?Icehouse
  70. 70When were the two most sever icehouse conditions?2.3 billion ya
    700 million ya
  71. 71What was the furthest extent of glaciers in severe icehouse conditionsFull coverage except a thick band around the equator
  72. 72Which 3 factors play the biggest role in % ice coverageCO2
    Solar Activity
    Tectonics

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Degree BSc Environment Geography Flashcards on Glaciers - Earth Processes and Landforms, created by Sammie Bradley on 10/06/2019.
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Sammie Bradley
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