Definition: channel cut by glacial meltwater under, along or in front of an ice margin. Meltwater may flow under hydrostatic pressure within the glacier and the resultant channels will show up-down long profiles. Alternatively, water may flow under gravity. Meltwater channels are recognizable from their anomalous topographic positions and their large size (misfit) relative to the streams that now occupy them.
Some of the best developed meltwater channels on Orkney are to be found in north Hoy. The moraine complex at Rackwick illustrated above includes several proglacial and subglacial channels cut into drift. In contrast, rock-cut channels at higher elevations, including Red Glen below, are developed on the lee side of cols and relate to higher levels of the last and earlier ice sheets.