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A meltwater channel (or sometimes a glacial meltwater channel) is a channel cut into ice, bedrock or unconsolidated deposits by the flow of water derived from the melting of a glacier or ice-sheet. [1] The channel may form on the surface of, within, beneath, along the margins of or downstream from the ice mass.
The valley wall prevents meltwater streams from flowing outward away from the glacial snout. Instead, glacial meltwater is diverted laterally along the ice margin and deposits sediments between the glacier and valley wall. [25] As the glacier retreats, the process may repeat creating a stepped slope or terrace referred to as a kame terrace.
Glacial streams are also commonly referred to as "glacier stream" or/and "glacial meltwater stream". The movement of the water is influenced and directed by gravity and the melting of ice . [ 1 ] The melting of ice forms different types of glacial streams such as supraglacial, englacial, subglacial and proglacial streams. [ 1 ]
Glacial striations are usually multiple, straight, and parallel, representing the movement of the glacier using rock fragments and sand grains, embedded in the base of the glacier, as cutting tools. Large amounts of coarse gravel and boulders carried along underneath the glacier provide the abrasive power to cut trough-like glacial grooves .
Meltwater is often found during early spring when snow packs and frozen rivers melt with rising temperatures, and in the ablation zone of glaciers where the rate of snow cover is reducing. Meltwater can be produced during volcanic eruptions , in a similar way in which the more dangerous lahars form.
They can be up to 10 meters wide and are typically found on ice sheets and flat areas of a glacier in a region of transverse crevasses. Moulins can reach the bottom of the glacier, hundreds of meters deep, [ 3 ] [ 4 ] [ 5 ] or may only reach the depth of common crevasse formation (about 10–40 m) where the stream flows englacially. [ 6 ]
It is frozen to its bed. A temperate glacier is at a melting point temperature throughout the year, from its surface to its base. This allows the glacier to slide on a thin layer of meltwater. Most glaciers in alpine regions are temperate glaciers. Gradient of the slope. Thickness of the glacier [4] Subglacial water dynamics
Subglacial streams are conduits of glacial meltwater that flow at the base of glaciers and ice caps. [1] Meltwater from the glacial surface travels downward throughout the glacier, forming an englacial drainage system consisting of a network of passages that eventually reach the bedrock below, where they form subglacial streams. [1]