A glacial-process model: The role of spatial and temporal variations in glacier thermal regime

Mooers, Howard D.

doi:10.1130/0016-7606(1990)102<0243:agpmtr>2.3.co;2

Cited by 42 publications

(16 citation statements)

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“…Eskers and tunnel channels are confidently attributed to subglacial fluvial action (Ringrose, 1982;Shaw, 1983a;Boyd et al, 1988;Sharpe, 1988). Nevertheless, there is vigorous debate on whether they are products of steady-state flows and incremental formation as suggested by Mooers (1989), or are products of catastrophic drainage and were formed synchronously along their full lengths (Wright, 1973;Boyd et al, 1988;Sharpe, 1988;Shaw and Gilbert, 1990). Other tunnels and cavities did not give rise to landforms, but sediment deposited within them is now part of complex stratigraphic sequences (Dreimanis et al, 1987;Shaw, 1987).…”

Section: Glaciofluvial Processesmentioning

confidence: 95%

A qualitative view of sub-ice-sheet landscape evolution

Shaw

1994

Progress in Physical Geography: Earth and Environment

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Qualitative analysis of sub-ice-sheet landscapes is based on processes inferred from landform and sediment. Striation and plucking give information on the dynamic and thermodynamic conditions at the ice bed. Lodgement and melt-out tills indicate that basal accretion and freezing conditions were followed by melting during till deposition, under sliding ice in the case of lodgement and stagnant ice in the case of melt-out. Surging is inferred from evidence of low icesheet profiles. Melt-out appears to have taken place over large areas in periods of stagnation following surges. Interbedded stratified sediment and melt-out till indicate decoupling of the ice from its bed during relatively minor subglacial drainage events. The bulk of glacial erosion, transport and deposition took place during ice-sheet advance. Over-ridden proglacial sediment, lodgement/deformation and melt-out tills, with subglacial sorted beds, were eroded by cataclysmic meltwater outburst floods that produced erosional and depositional drumlins, flutings, Rogen moraines and vast tracts of scoured bedrock. These floods marked a dramatic change in glacier regime over large areas of ice sheets. Low ice-sheet profiles caused widespread stagnation; glacial erosion and transport came to a halt. Extensive esker systems attest to a regional, integrated subglacial drainage network. Tunnel channels, glaciotectonic landforms and hummocky moraine are other elements of the subglacial landscape related directly or indirectly to meltwater storage and outburst floods. Models of landscape evolution are based on the conclusions derived from the analysis of sediment, form and process.

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Section: Glaciofluvial Processesmentioning

confidence: 95%

A qualitative view of sub-ice-sheet landscape evolution

Shaw

1994

Progress in Physical Geography: Earth and Environment

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“…However, Shreve (1972) has argued that wide tunnel valleys and small eskers may form with no change in discharge, and Boulton and Hindmarsh (1987) have demonstrated that tunnel valleys may be excavated by relatively small streams. Indeed, there are numerous examples of eskers associated with, at the mouths of and developed along the axes of tunnel valleys and deep troughs cut by subglacial meltwaters (Michalska, 1969;Wright, 1973;Krüger, 1983;Mooers, 1989Mooers, , 1990. We therefore suggest that the esker may represent the distal end of a glacial conduit system that originated within the North Sea Basin (Fig.…”

Section: Sediment Provenancementioning

confidence: 99%

The Age and Origin of the Blakeney Esker of North Norfolk: Implications for the Glaciology of the Southern North Sea Basin

Gale

Hoare

2007

Glacial Sedimentary Processes and Products

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The age and origin of the Blakeney ridge of eastern England have been debated for over a century. The feature is shown to be an esker formed in the late stages locally of a glaciation of Middle Quaternary age. The weight of evidence indicates that the esker was associated with the ice that laid down the Marly Drift of central north Norfolk, although this cannot be demonstrated conclusively. The flows that formed the Blakeney esker were subglacial. They took place from northwest to southeast along the length of the ridge, with at least the final phase occurring under hydrostatic pressure. It is likely that the esker developed during a glacial stillstand and under steep hydraulic gradients close to the ice sheet terminus. Although the esker conduit appears to have functioned largely as a Röthlisberger channel, there is evidence of simultaneous incision of the glacial bed. A valley is cut into bedrock beneath the esker. The esker and the buried valley may form the distal components of one of the broadly north-south aligned subglacial valleys that were trenched across the southern North Sea Basin in Middle Quaternary times. The complex assemblage of proglacial glaciofluvial landforms found to the south of the esker may represent the products of transport along the subglacial valley. The ice lobe that occupied the southern North Sea Basin may have left similar buried valley-proglacial fan complexes elsewhere along the northern fringe of East Anglia.

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“…For example in the southern Laurentide Ice Sheet, Colgan et al (2003) have documented a sequential change from frozen bed to active temperate and then to surging conditions during ice sheet recession, based upon the occurrence of three characteristic landsystems: Landsystem A (fluted till plains and low-relief push moraines) records active temperate ice recession; Landsystem B (drumlinized zone grading into moderate-to high-relief moraines and ice-walled lake plains) represents a polythermal ice sheet margin in which sliding and deforming bed processes gave way to a marginal frozen toe zone; and Landsystem C, which comprises the diagnostic landforms and sediments of surging activity. This change in ice sheet marginal dynamics during recession is communicated also in a conceptual model of spatial and temporal variations in glacial landform development presented by Mooers (1990) based on evidence from central Minnesota and relating to the operation of the Rainy and Superior lobes of the southern Laurentide Ice Sheet. The dynamics of the Rainy Lobe varied little during ice recession and the geomorphology records the operation of three zones: 1) a debriscovered ice zone fed by englacial thrusting and stacking of debrisrich ice; 2) a basal freeze-on zone; and 3) a thawed bed zone.…”

Section: Introductionmentioning

confidence: 97%

Glacial landsystems of Satujökull, Iceland: A modern analogue for glacial landsystem overprinting by mountain icecaps

Evans

2011

Geomorphology

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A glacial-process model: The role of spatial and temporal variations in glacier thermal regime

Cited by 42 publications

References 0 publications

A qualitative view of sub-ice-sheet landscape evolution

A qualitative view of sub-ice-sheet landscape evolution

The Age and Origin of the Blakeney Esker of North Norfolk: Implications for the Glaciology of the Southern North Sea Basin

Glacial landsystems of Satujökull, Iceland: A modern analogue for glacial landsystem overprinting by mountain icecaps

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