In a warm glacier, meltwater will drain into the ice through a network of veins, moulins, channels, and conduits, which can connect to an englacial system, discharging at the snout, or to a subglacial system of channels, linked cavities, subglacial lakes, and water films. These englacial and subglacial systems may become connected during the melt season; in cold glaciers, however, the superglacial and subglacial drainage systems are always separate. Hydrological features related to the evolution of the glacier drainage system include supraglacial routing, moulin types, and chasms (Yde and Knudsen (2005) Geografiska A 87, 3).