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Define delta kames

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Natural lakes are formed by melt water streams. Sometimes material deposited in these lakes forms deltas, called delta kames.

Kames are amongst the most varied landforms resulting from deposition by glacial meltwater. A kame (Scots kaim a hill) may occur as an isolated hill but more generally each kame is one mound in a low-lying terrain of many hummocks, terraces, ridges and hollows. Kames often occur in association with kettle holes in kame and kettle topography. Eskers may also occur between the kames. Meltwater channels may be cut into and between the kames. These associations indicate that kames are formed close to ice margins in situations where there are large volumes of both meltwater and debris.

The sediments inside kames are often exposed by quarrying. Bedded and sorted sand and gravel predominates but often sharp lateral variations are apparent in the calibre of the material, indicating rapid changes in flow velocity. Small details may reveal much about the events during deposition. The sloping beds of delta foresets indicate sand deposition in a pond or lake. Sands clasts, rounded blocks of now-loose sand, show that beds of saturated sands were frozen prior to transport. Beds of sand and gravel may be displaced by faults or rucked by folds, signs that the sides of the kame may have slumped after deposition or that ice has pushed forward again. Some kames are capped by till, indicating a late readvance of ice or deposition in a pond beneath the ice. Ice wedge casts on the surface of the kame point to the development of permafrost during and after ice retreat

Kames form in the chaotic zone of melting ice, water and oozing sediment close to the ice margin. Virtually any hollow within the decaying front may fill with water and receive sediment - crevasses, moulins and larger cavities. As the ice melts, the kame begins to emerge as a hump but its side are saturated and no longer supported by ice and so slumping is possible. Buried blocks of ice melt slowly to leave water-filled kettle holes.
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