How do glaciers modify the earth’s surface through erosion?

Transportation and erosion
Entrainment is the picking up of loose material by the glacier from along the bed and valley sides. Entrainment can happen by regelation or by the ice simply picking up the debris.
Basal Ice Freezing is thought to be to be made by glaciohydraulic supercooling, though some studies show that even where physical conditions allow it to occur, the process may not be responsible for observed sequences of basal ice.
Plucking is the process involves the glacier freezing onto the valley sides and subsequent ice movement pulling away masses of rock. As the bedrock is greater in strength than the glacier, only previously loosened material can be removed. It can be loosened by local pressure and temperature, water and pressure release of the rock itself.
Supraglacial debris is carried on the surface of the glacier as lateral and medial moraines. In summer ablation, surface melt water carries a small load and this often disappears down crevasses.
Englacial debris is moraine carried within the body of the glacier.
Subglacial debris is moved along the floor of the valley either by the ice as ground moraine or by meltwater streams formed by pressure melting.
Deposition
Lodgement till is identical to ground moraine. It is material that is smeared on to the valley floor when its weight becomes too great to be moved by the glacier.
Ablation till is a combination of englacial and supraglacial moraine. It is released as a stationary glacier begins to melt and material is dropped in situ.
Dumping is when a glacier moves material to its outermost or lowermost end and dumps it.
Deformation flow is the change of shape of the rock and land due to the glacier.

more.........

http://www.answers.com/topic/glacier#Transportation_and_erosion