Tectonics edexcel a-level

• Adaptation meaning

  • strategies to reduce the impacts of hazard events
• Upland erosional features:

  • cirques/corries
  • arêtes
  • pyramidal peaks
  • glacial troughs
  • truncated spurs
  • hanging valleys
  • ribbon lakes
• cirques/carries -

  accumulation of snow and water in a nivation hollow that ovetime forms and compresses into ice.

  freeze-thaw weathering, abrasion and plucking help deepen the bottom of the nivation hollow.

  overtime the ice will melt and the deep nivation hollo will transform into a lake
• arêtes -

  to curries/cirques form side by side
• pyramidal peaks-

  when two or three cirques/carries erode a mountain
• truncated spurs-

  preglacial interlocking spurs of a river valley is widened and deepend by a glacier.

  erosional processes remove the mountain spurs by cutting them
• hanging valleys-

  occurs when the main glacier leaves a large rough deep and wide enough for smaller glaciers to join it

  the smaller glaciers often create a small waterfall
• ribbon lakes-

  after de-glaciation water fills hollows within the glacial trough which is often sat on impermeable ground
• landforms created due to ice sheet scouring:

  • roaches mountoneés
  • whalebacks
  • knock-an-lochan
  • crag and tail
• roaches mountoneés-

  formed beneath a warm based ice with basal meltwater

  formed due to abrasion on the stops side and plucking on the lee side

  
• whalebacks-

  formed beneath a relatively warm-based ice that is thick and slow moving with no basal meltwater

  
• knock-an-lochan -

  occur due to alternating bands of hard and soft rock
• crag and tail -

  produced by selective erosion and deposition beneath an ice sheett

  strong rock that has resisted glacial erosion and forms an abstraction to the ice producing a ‘pressure shadow’ in its lee
• Reasons for glacial deposition:

  1. velocity is reduced
  2. they become overloaded with debris
  3. when ablation increases
• the formation of ice contact depositional features:

  • ice erratics
  • ice moraines - lateral, medial, end and terminal
  • drumlins
• erratics-

  rock debris falls ontop of the glacier often due to erosIona features attacking the valley sides

  the debris is then carried and deposited when ablation increases + heavier weight
• ice morraines-

  occur at the edges of glaciers. most are linear with nature
• drumlins -

  an oval shaped hill that is created by friction between the ice sheet(glacier) and the geology below.
• The formation of lowland depositional landforms:

  • lodgement till
  • ablation till
• lodgement till -

  subglacial material that becomes lodge in the glacier bed ie. Drumlins

  tends to be more rounded and angular

  elongated and oriented with the flow of ice
• ablation till-

  loss of debris carried due to the glacier melting

  • is more angular and less spherical
  • less compacted
  • occurs both sub-glacially and supraglacially along th margins of the glacier