What are glaciers?

  • The last Ice Age ended 10,000 years ago
  • Today only 10% of the earth is covered by ice sheets, ice caps and valley glaciers
  • A glacier is like a very slow moving river of ice
  • They are formed in areas of high snowfall in winter and cool temperatures in summer.
  • This means that the snow that accumulates in the winter and isn't lost by melting or evaporation during the summer.
  • These conditions occur in polar and high alpine regions.
  • There are two main types of glaciers: valley glaciers and continental glaciers.

How does a glacier form?

  • A glacier forms when snow accumulates over time
  • The snow becomes compressed under the weight of more snowfalls 
  • This turns the accumulated snow to ice
  • The ice becomes even more compressed and air is forced out
  • The ice crystals become larger as the air spaces become smaller and this turns the ice blue!
  • Eventually the combined weight of the ice and the force of gravity forces the ice to start moving (very slowly of course)

Key points

  • A glacier is an open system with inputs, flows, stores and outputs
  • The balance between accumulation (how much snow enters the glacier) and ablation (how much is melted) determines whether a glacier will move forward (advance) or move backwards (retreat)
  • The front end of the glacier is called the snout
  • Frost shattering is a type of physical weathering
  • Plucking and abrasion are processes of glacial erosion
  • There are five features of erosion
  • There are three main features of deposition

This video looks at Glaciation in action

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