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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.
The meltwater then flows through various different streams either entering inside the glacier into englacial channels or under the glacier into subglacial channels. [2] Finally, the water leaves the glacier through proglacial streams or lakes. [2] Proglacial streams do not only act as the terminus point but can also receive meltwater. [2]
A kame delta (or ice-contact delta, morainic delta [1]) is a glacial landform formed by a stream of melt water flowing through or around a glacier and depositing material, known as kame (stratified sequence of sediments) deposits. Upon entering a proglacial lake at the end (terminus) of a glacier, the river/stream deposit these sediments. This ...
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 .
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]
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]
Note the variable width and the interruption between segments of the course. There is also evidence of other sediment-filled channels adjacent to this (e.g., two smaller lakes to the right) Subglacial meltwater flow is common to all theories; hence a key to understanding channel formation is an understanding of subglacial meltwater flow.