MWCs west of the Coire Cas ski car park
Elbow of capture at the head of the Ailnach gorge
Definition: channel cut by glacial meltwater under, along and 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
The early papers of Bremner (1929, 1930, 1932 and 1934) remain informative accounts of the range of meltwater channels to be found around the Cairngorms. The most obvious group of channels are those cut into the northern flanks of the mountains, including the Chalamain Gap.
These channels are large, rock-cut notches (Gaelic: eag), often with clear up-down profiles. The channels are part of the regional meltwater drainage systems mapped by Young (1974, 1975a, 1975b) and related to the Strathspey ice lobe, extending from Glen Feshie towards Abernethy Forest. The possibility of inheritance from earlier glacial phases is high.
Major rock-cut channels of the Northern Cairngorms. Streetmap view
Other meltwater channels are associated with depositional features on lower ground. These channels were cut by meltwater during the wastage of the last ice sheet. They made be cut in rock or in glacial or fluvioglacial deposits. The Am Beanaidh draining Gleann Einich occupies a channel cut through the Cadha Mor moraine and can be regarded as a proglacial meltwater channel. The channels on the slopes above the Gairn breach mark positions of the ice margin as it downwasted. Other channels formed subglacially and are associated with eskers, kames and kettles, with some of the best examples found in Glen More.
Marginal meltwater channels near the Gairn breach. Former meltwater flow from R to L.
Some of the largest channels are found along the Water of Caiplich. The capture of the Caiplich by the Ailnack seems to have been largely a result of meltwater cutting through the preglacial col at The Castle, yet the depth of Glen Loin also attests to a formerly considerable flow of meltwater along this valley.