The melting of ice produces a great deal of water which has the capacity to carry much debris. As the water often flows under considerable pressure, it has a high velocity and is very turbulent. It can theredore pick up and transport a larger amount of material than a normal river of similar size. It is now believed that this water, with its load is responsible for the creation of subglacially valleys that are often deep and riddled with potholes.
When the meltwater discharge decreases, the resultant loss of energy cases the material being carried by the meltwater to be desposited. As with all water deposition, the heavier particles will be dropped first, resulting in sorting of the material. Deposits may also be found in layers (stratified) as a result of seasonal variations in the meltwater flow. The main features produced by fluvioglacial deposition are eskers, kames and the outwash plain. Lakes on the outwash plain may have layered deposits in them called varves.
Moulins are exciting fluvioglacial features. They have key features as detailed below:
• Roughly circular, vertical/nearly vertical shaft in a glacier
• 10m wide
• Carry meltwater from the surface
One video link from the BBC