The effectiveness of meltwater as an agent of erosion depends on: the susceptibility of the bedrock involved (particularly its structural weaknesses or proclivity to chemical attack); the water velocity and the level of turbulent flow; and the quantity of sediment in transport (Glasser and Bennett (2004) PPG 28, 3). A glacial margin channel is a stream running between the side of the glacier and the valley sides. Landforms of glacial meltwater erosion include both subglacial and ice-marginal meltwater channels.