- 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)
- 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