 Esker!
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| ESKER
it is a long , winding ridge of stratified sand & gravel. these are frequently several miles in length, most of esker are believed to form in ice-walled tunnels by streams which flowed within & under glaciers. after the retaining ice walls melt away, stream deposits remain as long winding ridges.it it is also form above the glaciers by accumulation of sediment in supraglacial channels, increvasses, in linear zones between stagnant blocks, the rate of plastic flow & melting of the basic ice determines the size & shape of the subglacial tunnel. this in turn determines shape, composition, structure of Esker. they are no often found as continuous ridges, but have gaps that seperate the winding segments. the ridge crests of eskers are not usually level for very long & are generally knobby. Eskers can be borad-crested / sharp-crested with steepsides. they can reach hundreds of kilometers in high. the concentration of rock debris in the ice & the rate at which sediment is delivered to the tunnel by melting & from upstream transport determines the amount of sediments in Eskers. the sediments consists of coarse-grained, water-laid sand & gravel. cross-bedding is common in Esker.
the name Esker is derived from Irish word eiscier means " a ridge of one seperating two plains surfaces". the mason esker at 22 miles is one of the longest Esker in the US.
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Linear Mode
