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.

Berriedale Wood in Hoy

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.

Red Glen MWC bell

  • During the periods of maximum cold in the Quaternary, major ice sheets covered Scotland. An ice stream hundreds of metres thick curved out from the Moray Firth to cross the plain of Caithness and flow over Orkney towards ice limits close to the edge of continental shelf.

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  • In the gently-dipping sandstone terrain of Orkney, it is often difficult to pick out classic landforms of glacial erosion. Low-lying areas often show a pronounced SW-NE grain to the topography, parallel to the main direction of ice sheet flow. ...

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  • Glacial deposition is largely confined to low-lying areas on Orkney, where thicknesses of till may exceed 10 m. The glacial deposits drape the landscape, smoothing its outlines. Ice-marginal features are largely unrecognised outside Hoy ...

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  • Westray is the furthest northwest of the Orkney islands. The total area is 47 square kilometres, not huge but the irregular shape gives it a long coastline of almost 80 kilometres, a good place to look for glacial striations. The bedrock of the whole of the island is made up of the cyclical Rousay Flagstone Formation. ...

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