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Alternatively, drumlins may be residual, with the landforms resulting from erosion of material between the landforms. The dilatancy of glacial till was invoked as a major factor in drumlin formation. [14] In other cases, drumlin fields include drumlins made up entirely of hard bedrock (e.g. granite or well-lithified limestone). [15]
Drumlins and ribbed moraines are also landforms left behind by retreating glaciers. Many depositional landforms result from sediment deposited or reshaped by meltwater and are referred to as fluvioglacial landforms. Fluvioglacial deposits differ from glacial till in that they were deposited by means of water, rather than the glacial itself, and ...
Drumlins may be composed of stratified or unstratified till ranging in size from sand to boulders. The non-uniformity of drumlin composition is representative of the diverse origin of the sediments. [38] Banding or layering of till may occur in drumlins as till accumulates on the drumlin formation in successive layers. [38]
Various models about the formation of flutes have been proposed. The most widely accepted model is the Cavity Infill Model. [2] [3] [7] According this model, the formation of a flute is initiated when basal melting lodges a boulder on the subglacial bed of a glacial. Once the boulder is lodged, the passing glacial ice can no longer move the ...
Drumlin – Elongated hill formed by glacial action and drumlin field – Elongated hill formed by glacial action; Esker – Long, winding ridge of stratified sand and gravel associated with former glaciers; Fjord – Long, narrow inlet with steep sides or cliffs, created by glacial activity
Drowned drumlin in Clew Bay, Ireland Till-unsorted (Glacial flour to boulders) deposited by receding/advancing glaciers, forming moraines, and drumlins. Moraines (Terminal) material deposited at the end; (ground) material deposited as glacier melts; (lateral) material deposited along the sides. Drumlins Smooth elongated hills composed of till.
Till plains are also the location in which drumlins, drumlin fields, flutes, and additional moraines form, all composed of glacial till. [4] The material composition of till plains vary greatly, and is dependent on the travel path of the transporting glacier, indicated by the provenance of the deposited material.
Drumlins are found in groups called drumlin fields or drumlin camps. One of these fields is found east of Rochester, New York; it is estimated to contain about 10,000 drumlins. Although the process that forms drumlins is not fully understood, their shape implies that they are products of the plastic deformation zone of ancient glaciers.