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Why can some eskers extend for hundreds of kilometres?
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glacial landform
Eskers,
or narrow
ridges of
gravel and sand left by a retreating glacier,
wind through western
Nunavut, Canada, near the Thelon River.
Eskers are long, sinuous ridges composed of stratified sand and gravel that form within subglacial or englacial tunnels.12
The reason some eskers can extend for hundreds of kilometres is that they are deposited by meltwater streams flowing through pressurized tunnels at the base of massive ice sheets. These tunnels provide a confined, continuous pathway for sediment-laden water to transport and deposit material over vast distances as the glacier melts. While most esker segments are relatively short, these extensive, continuous ridges are remnants of the drainage systems that existed beneath the great ice sheets of the Pleistocene [Epoch].231