Emergent drumlins and their clones: from till dilatancy to flow instabilities

Clark, Chris D.

doi:10.3189/002214311796406068

Cited by 82 publications

(84 citation statements)

References 82 publications

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“…Certainly a similar regularity of arrangement and frequency of spacing has been recorded on other palaeo-ice stream beds (Spagnolo and others, 2014), and this may imply some common mechanism of formation (e.g. Clark, 2010;Fowler and Chapwanya, 2014 for drumlins).…”

supporting

confidence: 72%

Subglacial processes on an Antarctic ice stream bed. 1: Sediment transport and bedform genesis inferred from marine geophysical data

et al. 2016

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ABSTRACT. The spatial pattern and morphometry of bedforms and their relationship to sediment thickness have been analysed in the Marguerite Bay Palaeo-ice stream Trough, western Antarctic Peninsula. Over 17 000 glacial landforms were measured from geophysical datasets, and sediment thickness maps were generated from acoustic sub-bottom profiler data. These analyses reveal a complex bedform pattern characterised by considerable spatial diversity, influenced heavily by the underlying substrate. The variability in length and density of mega-scale lineations indicates an evolving bedform signature, whereby landforms are preserved at different stages of maturity. Lineation generation and attenuation is associated with regions of thick, soft till where deformation was likely to be the greatest. The distribution of soft till and the localised extent of grounding-zone wedges (GZWs) indicate a dynamic sedimentary system characterised by considerable spatio-temporal variability in sediment erosion, transport and deposition. ).

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confidence: 72%

Subglacial processes on an Antarctic ice stream bed. 1: Sediment transport and bedform genesis inferred from marine geophysical data

et al. 2016

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“…[19][20][21][22][23][24][25][26]). An early review of drumlin formation theories is that of Menzies [27], and a more recent one is that of Clark [28].…”

Section: Introductionmentioning

confidence: 99%

An instability theory for the formation of ribbed moraine, drumlins and mega-scale glacial lineations

Fowler

Chapwanya

2014

Proc. R. Soc. A.

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We present a theory for the coupled flow of ice, subglacial water and subglacial sediment, which is designed to represent the processes which occur at the bed of an ice sheet. The ice is assumed to flow as a Newtonian viscous fluid, the water can flow between the till and the ice as a thin film, which may thicken to form streams or cavities, and the till is assumed to be transported, either through shearing by the ice, squeezing by pressure gradients in the till, or by fluvial sediment transport processes in streams or cavities. In previous studies, it was shown that the dependence of ice sliding velocity on effective pressure provided a mechanism for the generation of bedforms resembling ribbed moraine, while the dependence of fluvial sediment transport on water film depth provides a mechanism for the generation of bedforms resembling mega-scale glacial lineations. Here, we combine these two processes in a single model, and show that, depending largely on the granulometry of the till, instability can occur in a range of types which range from ribbed moraine through three-dimensional drumlins to mega-scale glacial lineations.

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“…Clark, 2010;Menzies, 1989;Rose, 1987;Fowler, 2010). The size and shape of large numbers of palaeo-landforms have been mapped from exposed former ice sheet beds by satellite, airborne and shipboard systems (e.g.…”

Section: Introductionmentioning

confidence: 99%

Subglacial landforms beneath Rutford Ice Stream, Antarctica: detailed bed topography from ice-penetrating radar

King

Pritchard

Smith

2016

Earth Syst. Sci. Data

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Abstract. We present a digital elevation model of the bed of Rutford Ice Stream, Antarctica, derived from radioecho sounding data. The data cover an 18 × 40 km area immediately upstream of the grounding line of the ice stream. This area is of particular interest because repeated seismic surveys have shown that rapid erosion and deposition of subglacial sediments has taken place. The bed topography shows a range of different subglacial landforms including mega-scale glacial lineations, drumlins and hummocks. This data set will form a baseline survey which, when compared to future surveys, should reveal how active subglacial landscapes change over time. These data also allow comparison between subglacial landforms in an active system with those observed in deglaciated areas in both polar regions. The data set comprises observed ice thickness data, an interpolated bed elevation grid, observed surface elevation data and a surface elevation grid. The data set is available at http://doi.org/269.

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Emergent drumlins and their clones: from till dilatancy to flow instabilities

Cited by 82 publications

References 82 publications

Subglacial processes on an Antarctic ice stream bed. 1: Sediment transport and bedform genesis inferred from marine geophysical data

Subglacial processes on an Antarctic ice stream bed. 1: Sediment transport and bedform genesis inferred from marine geophysical data

An instability theory for the formation of ribbed moraine, drumlins and mega-scale glacial lineations

Subglacial landforms beneath Rutford Ice Stream, Antarctica: detailed bed topography from ice-penetrating radar

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