Abrasion - This process occurs when material the glacier is carrying rubs away at the valley floor and sides. The action of abrasion is likened to sandpaper.
Plucking- Plucking occurs when the glacier freezes on to and in to rock outcrops. As the ice moves forward it pulls away any material which is frozen to or in the glacier. This process creates a jagged landscape. Solifluction- This occurs when the active layer thaws in the summer, the excessive lubrication reduces the friction between the soil particles. This allows part of the active layer to move downslope. Subglacial meltwater-erosion - The meltwater under the glacier is able to erode both chemically and physically. Chemically the meltwater can cause solution of the underlying rock, particularly if the rock is limestone or chalk. Freeze-thaw- is a weathering process which effects glacial landforms. Freeze thaw occurs when water enters cracks or joints in the rock and freezes, causing it to expand. This expantion puts pressure which pirses the joints apart. This process can cause rock to be loosened and will then used in the process of abrasion. Pressure release- As glaciers begin to melt the pressure which they exert on to the underlying rock is reduced. This can cause fracturing as dilation of the rock occurs. |
Periglacial Processes
Freeze - thaw action (frost shattering)
Nivation
NIvation occurs beneath the snow in hollows, usually on the North or East facing slopes. Underlying rock begins to disintergrate due to freeze thaw and chemical weathering. Snow which melts in the spring moves weathered particles downslope which are transported in meltwater and by solifluction. This causes Nivation Hollows which can become enlarged and create Corries.
Nivation
NIvation occurs beneath the snow in hollows, usually on the North or East facing slopes. Underlying rock begins to disintergrate due to freeze thaw and chemical weathering. Snow which melts in the spring moves weathered particles downslope which are transported in meltwater and by solifluction. This causes Nivation Hollows which can become enlarged and create Corries.