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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]
Diagram illustrating (i) tunnel in glacier before retreat of ice, forming (ii) meandering esker in The Ice Melts: Deposition, p. 6 of "Pennsylvania and the Ice Age" published 1999 by PA DCNR Bureau of Topographic and Geologic Survey; The Bridgenorth Esker: geomorphology and sedimentology
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
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]
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 ...
Kames are sometimes compared to drumlins, but their formation is distinctively different. A drumlin is not originally shaped by meltwater, but by the ice itself and has a quite regular shape. It occurs in fine-grained material, such as clay or shale, not in sands and gravels. And drumlins usually have concentric layers of material, as the ice ...
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.
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...