glacial breach

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glacial breach A glacially eroded trough that cuts through a ridge and so breaches a former divide. It is formed when the outflow of a glacier (or ice sheet) is impeded, so that the thickness of the glacier consequently increases, and ultimately a higher escape route (the breach) is exploited. This process is called ‘glacial diffluence’ when a single glacier spills out of its valley, and ‘glacial transfluence’ when several breaches are formed, owing to the accumulation of a large ice sheet. The many breaches through the western Highlands of Scotland were caused by the accumulation of transfluent ice east of the main watershed.

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