glaciation - physical Landscapes in UK

• 3 regions in the UK that was once glaciated

  • Scottish Highlands
  • North Wales
  • Lake District
• Glacial


  when a phase causes glaciers to freeze (cooler)
• Interglacial 


  when a phase causes glaciers to melt (warmer)
• Quaternary

  • began 2.5 million years ago
  • also know as the ice age
  • we are in this phase (but we are leaving it due to global warming)
  • Devensian = the last glaciation in Britain
• Glacial ice formation

  It is formed by annual snow fall during winter, each year as snow accumulates, the layers of snow beneath are compressed. The neve becomes increasingly dense eventually forming dark blue glacial ice.
• Neve


  Snow which survives one summer
• During winter = glacier advances

  During summer = glacier retreats
• Mass movement 


  something which involves gravity to pull it down. For example rockfall, mudslides and avalanches
• Geomorphic process


  a process which changes an object's shape, size and elevation from the ground.

  e.g. mass movement, freeze-thaw weathering, erosion
• Freeze-thaw weathering


  a major process in glaciated areas, where water in the cracks freezes overnight (as it is colder) which expands the cracks by 9% and thaws during daytime. this repeating process causes crack to weaken and the scree (jagged pieces of rock) to break off from the valley side and into the glacier.
• moraine


  rocks and debris which are left behind or inside a moving glacier.
• Glaciers create U shaped valleys
• The glacial debris and rocks at the bottom of the glacier erodes the landscape as freeze-thaw weathering provides scree for the glacier.
• There are 2 glacial erosion processes called abrasion and plucking.
• Abrasion (glacial)


  trapped moraine and scree at the bottom of the moving glacier scrapes along the landscape creating a sandpaper effect, forming U shaped valleys.
• Plucking (glacial)


  Glacial meltwater can enter the cracks in the valley sides, as it refreezes and wraps itself around protrusion and rips it out of the valley side when the glacier moves again.
• Basal sliding (movement)


  pressure melting (friction), melts the bottom of the ice creating a thin film of water beneath the glacier. It acts as a lubricant allowing the glacier to slide as there is less friction.
• Internal deformation (movement)


  individual ice crystals can move and re-orientate itself when a glacier is moving over a large protrusion, it moves in layers but it is a very slow process.
• Rotational slip (movement)


  Snow accumulating at the top push the glacier down and the meltwater at the bottom of a glacier makes it easier to slip.
• Glaciers advance during the winter when accumulation of winter snow higher up exceeds any melting of ice lower down at the snout.
• Glaciers retreat in summer when melting at the snout lower down exceeds any accumulation of snow higher up (if any).
• Glacial transportation


  Glaciers can transport material on top, inside or under the moving ice.
• Bulldozing


  Glaciers are huge masses of ice, so the snout (end) pushes material in front of it like a bulldozer.
• Deposition (glacial)

  • happens seasonally during summer periods of glacial retreat due to the heat which causes ablation (melting)
  • material can be deposited during winter when a glacier becomes too overloaded with debris
• Moraine/till


  deposited by a glacier and has not been acted on with the influence of meltwater.
• Characteristics of moraine/till

  • deposited by ice
  • angular and jagged shaped
  • large range size
  • unsorted
• Characteristics of outwash

  • deposited by glacial meltwater
  • rounded shape
  • generally smaller size
  • sorted
• Outwash


  deposited by a glacier with the influence from the glacier meltwater
• Erosional landforms formed by glaciers

  • corrie - bowl shaped
  • arete - steep sided ridge
  • pyramidal peak - pointed mountain peak
  • glacial trough - U shaped valley
  • hanging valley - forms a waterfall
  • truncated spurs - an interlocking spur with the end cut off
  • ribbon lake - long narrow deep lakes found U shaped valleys
• Corrie 


  A bowl shaped depression formed by glacial erosion like rotational slip, generally faces northwards. Creates a lake called a tarn once the ice has melted.
• Tarn


  a small mountain lake or pool created once ice has melted.
• Arete


  Very narrow and steeped rocky sided ridge, usually formed in between 2 corries.
• Pyramidal peak


  a very steep sided, pointed peak formed in the middle of 3 or more corries. e.g. The Matterhorn, Switzerland
• Glacial trough


  Steep sided, symmetrical U shaped valley slopes with broad and wide valley floors that are deepened my glacial ice.
• Hanging valley


  when a smaller tributary valley glacier (doesn't erode as deep) joins onto a much large valley glacier. When the glacial ice melts it leaves behind a hanging valley.
• Truncated spur


  The ends of a former interlocking spur that has been eroded and bulldozed by an advancing valley glacier, cutting of the ends of the interlocking spur.
• Ribbon lake


  A long, narrow and very deep lake found in a glacial trough with lots of smaller tributary glaciers which fed in to the main valley glacier. Once melted created a ribbon lake.
• Depositional landforms formed by glaciers

  • lateral moraine - linear ridges of deposited till
  • medial moraine - deposited till found in the middle junction of 2 glaciers
  • terminal moraine - a crescent shape ridge across the end of the glacial trough
  • drumlins - elongated asymmetrical shaped hills
  • erratics - large, odd shaped rocks
• Lateral moraine


  linear ridges of deposited till which is found along the sides of a glacier.
• Medial moraine


  linear ridges of deposited till found in the junction between 2 glaciers.