Introduction to Glaciofluvial Landforms

“Fluvioglacial” means erosion or deposition caused by flowing meltwter, from melting glaciers, ice sheets and ice caps. Glacial meltwater is usually very rich in sediment, which increases its erosive power.

Fluvioglacial landforms include sandar (also known as outwash plains; they are braided, sediment-rich streams that drain away downslope away from a glacier), kames and kettles, meltwater channels, and eskers.

Glaciofluvial outwash plain

Glaciofluvial systems are characterised by strong changes in flow magnitude and frequency. Flow magnitudes can fluctuate strongly on a daily basis, as melt increases and decreases over day and night. It also fluctuates seasonally, in the summer (ablation) and winter (accumulation) seasons.

Glacier meltwater can flow supraglacially (on top of the glacier ice), englacially (within the glacier ice), subglacially (below the glacier ice) and proglacially (in front of, and away from, glacier ice). Surface meltwater can reach the bed by draining through the bases of crevasses and moulins.

Fig. 1
A schematic illustration of a land-terminating section of the Greenland ice sheet, highlighting the main meltwater pathways and stores in the hydrological system. Critical areas of uncertainty regarding the future evolution of the hydrological system are numbered as discussed in the text: (1) darkening of the ice sheet, (2) surface firn densification processes, (3) surface to bed connections at higher elevations, (4) cryo-hydrologic warming, (5) rates of channelisation at the ice bed interface, (6) subglacial sediments and till deformation, and (7) basal melt rates. All of these processes are also relevant to tidewater glacier systems. From Nienow et al., 2017.

These pages outline some of the key glaciofluvial landforms associated with the passage of glacial meltwater. For more information, see Glacier Hydrology.