glaciers

• what is a glacier?

  - consists of fallen snow that over many years has been compressed into a large, dense ice mass
• what are glacials?


  periods of very cold and dry climate during which large land and sea ice masses grow and valley glaciers extend to lower levels. last glacial ended 10000yrs ago
• what are interglacials?


  warmer periods during which the extent of ice masses and valley begin to retreat. currently in one known as the Holocene
• what structure is ice?

  fluid

  > solid that can flow
• what does KaBP stand for?

  thousand years before present
• explain temperate glaciers


  around 0 degrees

  erosion transportation and deposition occur

  grey in colour as a result of rock particles within ice

  melt (partly) in summer

  are lubricated

  behave as a frozen river
• explain polar glaciers


  temp permanently below 0 degrees

  permanently frozen - no melting

  white/blue colour as less rock within ice

  minimal erosion, transportation or deposition

  move mainly by internal deformation
• what is an iceberg?


  a chunk of ice which has detached from a main glacier by calving and now is floating
• number of years since the last major ice age in uk ended?

  18000 years
• the % of the worlds surface covered in ice?

  10%
• no. of countries that have existing glaciers?

  47
• estimated age of Antarctic ice sheet in yrs?

  40 million yrs
• no. of glaciers in Alaska?

  100000
• % of worlds water stored in glaciers?

  75%
• what is diagenesis?


  ice formation
• what is ablation?


  melting
• glacial budget

  
• what is sublimation?


  term for when ice changes directly from a solid to a gaseous form or vapour without passing through a liquid phase
• what are the 7 stages of ice formation?

  1- snow fall

  2- weight increases

  3 - snow is compacted

  4 - air is compressed and squeezed out

  5 - neve (new) ice

  6 - firn ice (1 year old)

  7 - glacial/blue ice
• a glacier is a system which has inputs stores and outputs, the balance of these determine what 5 things?

  1 how much ice is within the glacier

  2 the speed at which the glacier will move

  3 the erosive power of the glacier

  4 amount of meltwater produced by a glacier

  5 landforms produced by glacier
• explain net balance in a northern hemisphere glacier

  summer: ablation>accumulation

  winter: ablationsummer the glacier will advance

  summer budget > winter the glacier will retreat
• what does it mean when glaciers are said to be in dynamic equilibrium?

  - they will always oppose a change
• 6 factors affecting glacial systems

  climate

  geology

  aspect

  latitude

  altitude

  relief
• how does climate affect glacial systems?

  wind

  > can carry out erosion

  > aeolian processes

  
  

  precipitation

  > more precipitation = increased net gain

  affected by latitude

  increased lat = decreased precipitation

  
  

  temp

  > if temp rises above 0 degrees there will a inc in ablation & higher outputs
• how does geology affect glacial systems?

  weaker rocks (limestone) are more easily weathered

  > inc outputs and input

  
  

  - jointed rocks are permeable (freeze thaw and solution)

  
  

  - porous rocks allow water in (frost shattering)
• what is lithology?


  refers to the physical and chemical composition of rocks
• how does aspect affect glacial systems?

  - the compass direction something is facing

  > NE facing sloped have shortest daylight hours and least insulation
• how does latitude affect glacial systems?

  high latitude areas

  > cold, dry climate

  > little seasonal variation

  > will develop under large stable ice sheets
• how does altitude affect glacial systems?

  - temp decreases at a rate of approx 0.6 degrees C at 100m

  > less gravitational pull so air particles are less spaced out - mountains are colder
• how does relief affect glacial systems?

  the steeper the relief - more potential energy

  > glacier will have more energy to move downslope
• what is chelation?


  removal of metallic cations which decomposes minerals and rocks
• what is solution?


  salts dissolve into one substance

  > physical breakdown
• what is hyrdolysis?


  secondary mineral produced

  > chemical reaction
• what is weathering?


  breakdown or matter
• what is erosion?


  removal/ transportation of matter
• what are the 4 glacial erosion and mass movement processes?

  plucking

  abrasion

  mass movement

  rock fall
• what is plucking?


  occurs when rocks and stones become frozen to the base or sides of the glacier

  plucked when the glacier moves

  leaves behind a jagged landscapes

  sharp edges called Nunataks
• what is abrasion?


  occurs when rocks and stones become embedded in the base and sides of the glacier

  rub against bedrock as glacier moves

  weathers away the landscapes and leaves behind smooth polished surfaces which may have striations on them (scratches)
• what is mass movement?


  occurs when gravity > friction
• what is a rock fall?

  on slopes of 40 degrees or more,

  material falls to the base of the slope because of gravity

  transport processes may remove this material