Reply: Formation and reorientation of structure in the surge‐type glacier Kongsvegen, Svalbard

Woodward, John; Murray, Tavi; McCaig, A. M.

doi:10.1002/jqs.736

Cited by 15 publications

(4 citation statements)

References 15 publications

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“…Recent re-evaluation of the structures interpreted as thrusts at Kongsvegen, Svalbard, has led to the conclusion that the role of thrusting may have been overestimated (Woodward et al 2002(Woodward et al , 2003. As a consequence, Woodward et al (2002: p. 207) conclude that the model of englacial thrusting as an explanation of British 'hummocky moraine' formed during the Younger Dryas 'also must be questioned'.…”

Section: Implications and Model Applicabilitymentioning

confidence: 99%

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A test of the englacial thrusting hypothesis of ‘hummocky’ moraine formation: case studies from the northwest Highlands, Scotland

Lukas

2005

Boreas

148

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Lukas, S. 2005 (August): A test of the englacial thrusting hypothesis of 'hummocky' moraine formation: case studies from the northwest Highlands, Scotland. Boreas, Vol. 34, pp. 287-307. Oslo. ISSN 0300-9483.The melt-out of material contained within englacial thrust planes has been proposed to result in the formation of stacked moraine sequences with characteristic proximal rectilinear slopes. This model has been applied to explain the formation of Scottish Younger Dryas ice-marginal ('hummocky') moraines on the basis of these morphological characteristics. However, no sedimentological data exist to support this proposal. This article reviews hitherto proposed models of 'hummocky' moraine formation and presents detailed geomorphological and sedimentological results from the NW Scottish Highlands with the aims of reconstructing the dynamics of Younger Dryas glaciers and of testing the applicability of the englacial thrusting model. Exposures demonstrate that moraines represent terrestrial ice-contact fans throughout, with a variety of postdepositional deformation structures being identified in most cases, indicating that glacier retreat was incremental and oscillatory; proximal rectilinear slopes are interpreted as ice-contact faces formed after ice support was withdrawn during retreat. This evidence strongly suggests a temperate glacier regime and short glacier response times similar to those in present-day SW Norway or Iceland. It contradicts the thrusting model and the proposal that Svalbard might form a suitable analogue for Younger Dryas moraines in Scotland.

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Section: Implications and Model Applicabilitymentioning

confidence: 99%

“…Additional problems of their approach are inherent in the interpretation of the thrusts as such (e.g. Evans & Rea 1999;Woodward et al 2002Woodward et al , 2003 and the relatively little evidence that is used to support their model in Britain.…”

Section: Implications For Glacier Dynamicsmentioning

confidence: 99%

A test of the englacial thrusting hypothesis of ‘hummocky’ moraine formation: case studies from the northwest Highlands, Scotland

Lukas

2005

Boreas

148

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“…Hambrey and Huddart, 1995;Huddart and Hambrey, 1996;Bennett et al, 1996;Hambrey et al, 1997;Glasser et al, 1998;Bennett et al, 1998;Bennett, 2001). However, this model of moraine development by englacial thrusting is contentious (Evans, 2000), and the process has also been controversially reinterpreted as the reorientation of sediment-filled crevasses at Kongsvegen, Svalbard (Woodward et al, 2002;Glasser et al, 2003;Woodward et al, 2003). An improved understanding of these contemporary moraines will aid the interpretation of formerly glaciated areas, since morphological similarity has been suggested between some Svalbard and British Younger Dryas moraine mounds Bennett et al, 1998;Graham and Midgley, 2000;Midgley, 2001;Graham, 2002).…”

Section: Introductionmentioning

confidence: 99%

Sedimentology, Structural Characteristics and Morphology of a Neoglacial High‐Arctic Moraine‐Mound Complex: Midre Lovénbreen, Svalbard

Midgley

Glasser

Hambrey

2007

Glacial Sedimentary Processes and Products

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Detailed analyses of the sediments, structural characteristics and morphology of a Neoglacial morainemound complex at a high-Arctic, polythermal, land-based glacier -midre Lovénbreen, Svalbardhave been undertaken in order to evaluate their mode of formation and subsequent modification. Ten moraine mound lithofacies were identified: four types of diamicton, four types of gravel, sand and mud. A buried debris-bearing basal ice facies was also identified following excavation of a single moraine mound. The moraine mound lithofacies and buried basal ice reflect subglacial, glaciofluvial and basal ice layer processes. Structural attributes of the moraine mounds include faulting, folding and shearing. Three broad moraine mound morphological types are identified and characterised using Digital Elevation Models. Moraine mound formation is linked to elevation of sediment within the ice, associated with englacial thrusting. The recognition of buried ice in a moraine mound implies that on melting, the landform will become degraded. Hence the preservation potential of thrust-related features within these moraine mounds is low, unless the debris content of the ice is high.

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“…Ground-penetrating radar [Murray et al, 1997] and seismic surveys [Smith et al, 2002] showed that some of these structures continued to depth and intersected the bed near the thawed/frozen transition, which coincided with the downglacier extent of a surge that lasted from 1985 until 1995 [Smith et al, 2002]. However, some features once described as thrusts in similar polythermal surge-type glaciers have been re-interpreted as basal crevasse-fill structures [Woodward et al, 2002;Glasser et al, 2003a andWoodward et al, 2003].…”

Section: Field Observationsmentioning

confidence: 99%

Dynamics of ice flow and sediment transport at a polythermal glacier terminus: Storglaciaren, Sweden

Moore

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The cold-based termini of polythermal glaciers are usually assumed to adhere strongly to an immobile substrate and thereby supply significant resistance to flow of warm based ice upglacier. This compressive environment is often linked to uplift of basal sediment to the surface of the glacier by folding and thrust faulting. Herein, we present field evidence and numerical model results from the terminus of Storglaciären, Sweden, showing that the cold margin provides limited resistance to flow from upglacier. Ground-penetrating radar and thermistor data indicate that the 20-25 m thick cold surface layer meets the bed roughly 100 m from the ice margin. A heat and water balance, coupled with radar and field observations suggest that a meter-scale layer of subglacial till may be accreted in this zone. However, surface and basal velocity measurements and model results indicate that basal motion at rates

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Reply: Formation and reorientation of structure in the surge‐type glacier Kongsvegen, Svalbard

Cited by 15 publications

References 15 publications

A test of the englacial thrusting hypothesis of ‘hummocky’ moraine formation: case studies from the northwest Highlands, Scotland

A test of the englacial thrusting hypothesis of ‘hummocky’ moraine formation: case studies from the northwest Highlands, Scotland

Sedimentology, Structural Characteristics and Morphology of a Neoglacial High‐Arctic Moraine‐Mound Complex: Midre Lovénbreen, Svalbard

Dynamics of ice flow and sediment transport at a polythermal glacier terminus: Storglaciaren, Sweden

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