- Occurs when there is a reduction in the gradient of the valley floor.
- This leads to the thickening of the ice mass .
- Erosion is at its maximum.
- Occurs when there is an increase in the gradient of the valley floor.
- The ice accelerates and becomes thinner.
- This leads to less erosion.
- As the galcier moves over bedrock friction occurs.
- The lower ice is under a great deal of pressure from the mass of the glacier, this combined with friction results in some melting.