Year 9 Geography**

• What is an ice age?


  A geological period characterised by colder global temperatures and thick ice sheets covering vast expanses of land.
• What is a glaciation?

  A period within an ice age characterised by colder global temperatures.
• What is an inter-glacial period?

  A period within an ice age characterised by warmer global temperatures.
• What is an ice cap?

  An area of ice <50,000km²
• What is an ice sheet?

  An area of ice >50,000km²
• What is a glacier?

  A slowly moving body of compressed snow.
• What is moraine?

  A moraine is any accumulation of unconsolidated debris that occurs in glaciated regions, previously carried along by a glacier.
• What is a drumlin?

  An elongated hill formed from moraine.
• Label the diagram below:

  A) Arête

  B) Tarn

  C) Corrie

  D)

  E) Ribbon lake

  F) Truncated Spur

  G) Pyramidal Peak

  H) Misfit stream

  I) U-shaped valley

  J) Alluvial fan

  
• Match the terms to the definitions:

  • Pyramidal Peak
  • Arête
  • Corrie
  • Tarn
  • Alluvial fan
  • Ribbon lake
  • Misfit stream
  • Truncated spur
  • U-shaped valley
  • Hanging valley

  
• Formation of a corrie:

  1. Snow collects in a sheltered hollow on the side of a mountain. This becomes compacted and the air is squeezed out leaving ice.
  2. The back wall of the corrie gets steeper due to freeze-thaw and plucking.
  3. The base of the corrie becomes deeper due to abrasion.
  4. As the glacier gets heavier, it moves downhill. The glacier moves out of the hollow in a circular motion called rotational slip.
  5. Due to less erosion at the front of the glacier, a corrie lip is formed.
  6. After the glacier has melted, a lake forms in the hollow. This is called a corrie lake or tarn.
• Formation of a corrie:


  1. Snow collects in a sheltered hollow on the side of a mountain. This becomes compacted and the air is squeezed out leaving ice.
  2. The back wall of the corrie gets steeper due to freeze-thaw and plucking.
  3. The base of the corrie becomes deeper due to abrasion.
  4. As the glacier gets heavier, it moves downhill. The glacier moves out of the hollow in a circular motion called rotational slip.
  5. Due to less erosion at the front of the glacier, a corrie lip is formed.
  6. After the glacier has melted, a lake forms in the hollow. This is called a corrie lake or tarn.

  
• What are the two forms of glacial erosion called?

  Plucking and abrasion
• Abrasion - as the glacier moves downhill, rocks that have been frozen into the base and sides of the glacier scrape the rock beneath. The rocks scrape the bedrock like sandpaper, leaving scratches behind.
• Plucking - rocks become frozen into the bottom and sides of the glacier. As the glacier moves downhill it plucks the rocks frozen into the glacier from the ground.
• Freeze-thaw


  • During the day when temperatures are higher, the snow melts and water enters the cracks in the rock.
  • When the temperature drops below 0°C the water in the crack freezes and expands by about 9 per cent.

  
• Hanging valley

  Small, elevated valley above the main valley floor
• Corrie

  Armchair-shaped hollow with steep back and sides
• Alluvial fan

  Distinctive shaped collection of rocks
• U-shaped valley


  Steep-sided valley with a flat, wide floor
• Ribbon lake


  Narrow, deep body of water on the valley floor
• Arête


  A sharp, knife-edged ridge that sits between two corries.
• Pyramidal peak


  Triangular shaped rock with steep sides/faces
• Tarn


  Water that has gathered on the floor of a corrie
• Misfit stream


  Small stream found at the end of a glacial valley
• Truncated spur

  Ridge that has been cut off and blunted by a glacier
• What is erosion?

  The breakdown of rock by water, wind or ice.
• What is weathering?

  The breakdown of rock in situ i.e. not caused by force.