The origin of major incisions within the Pleistocene deposits of the North Sea

Wingfield, R.T.R.

doi:10.1016/0025-3227(90)90131-3

Cited by 127 publications

(115 citation statements)

References 31 publications

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“…They are observed in many formerly glaciated landscapes around the world, and tend to be orientated parallel to the direction of former ice flow (e.g. Ussing, 1903;Wright, 1973;Attig et al, 1989;Wingfield, 1990;Piotrowski, 1994;Patterson, 1997;Huuse and LykkeAnderson, 2000;Jørgensen and Sandersen, 2006). Features with similar dimensions have also been described beneath current ice masses (e.g.…”

Section: Introductionmentioning

confidence: 92%

“…It has been proposed that the development of a toe frozen to its bed along the fringe of an ice sheet acted as a barrier to water flow facilitating tunnel valley formation by subglacial ponding and outburst cycles (e.g. Wingfield, 1990;Piotrowski, 1994Piotrowski, , 1997Cutler et al, 2002). Moreover, freezing of sediment deposited in channels under the thin fringe of the ice sheet during winter months may have helped to prevent creep-closure of incipient tunnel valleys, thereby stabilising and preserving their forms from year to year.…”

Section: Wider Geographical Distribution Of Tunnel Valleysmentioning

confidence: 99%

“…Genesis is typically thought to occur via repeated low to moderate magnitude floods that may be at or below bankfull flow (e.g. Wright, 1973;Boyd et al, 1988;Wingfield, 1990;Piotrowski, 1994;Cutler et al, 2002;Hooke and Jennings, 2006;Jørgensen and Sandersen, 2006). Catastrophic erosion of entire tunnel valley networks by massive sheet floods has also been proposed (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation

Livingstone

Clark

2016

Earth Surf. Dynam.

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Abstract. Tunnel valleys have been widely reported on the bed of former ice sheets and are considered an important expression of subglacial meltwater drainage. Although known to have been cut by erosive meltwater flow, the water source and development of channels has been widely debated; ranging between outburst flood events through to gradually occurring channel propagation. We have mapped and analysed the spatial pattern and morphometry of tunnel valleys and associated glacial landforms along the southern sector of the former Laurentide Ice Sheet from high-resolution digital elevation models. Around 2000 tunnel valleys have been mapped, revealing an organised pattern of sub-parallel, semi-regularly spaced valleys that form in distinctive clusters. The tunnel valleys are typically < 20 km long, and 0.5-3 km wide, although their width varies considerably down-valley. They preferentially terminate at moraines, which suggests that formation is time dependent; while we also observe some tunnel valleys that have grown headwards out of hill-hole pairs. Analysis of cross-cutting relationships between tunnel valleys, moraines and outwash fans permits reconstruction of channel development in relation to the retreating ice margin. This palaeo-drainage reconstruction demonstrates incremental growth of most valleys, with some used repeatedly or for long periods, during deglaciation, while others were abandoned shortly after their formation. Our data and interpretation support gradual (rather than a single-event) formation of most tunnel valleys with secondary contributions from flood drainage of subglacial and or supraglacially stored water down individual tunnel valleys. The distribution and morphology of tunnel valleys is shown to be sensitive to regional factors such as basal thermal regime, ice and bed topography, timing and climate.

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Section: Introductionmentioning

confidence: 92%

Section: Wider Geographical Distribution Of Tunnel Valleysmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation

Livingstone

Clark

2016

Earth Surf. Dynam.

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“…We report 22 examples beneath the North Sea which are contained in the TUNNEL VALLEY layer and derive from Balson & Jeffrey (1991). It has been argued that 'enclosed deeps' (elongate, blind-ended, 100 m deep depressions in the bed of the North Sea) are also tunnel valleys eroded by jökulhlaups from huge subglacial lakes (Wingfield 1990). However, some controversy exists over the genesis of these features (Ehlers & Wingfield 1991) and they have not been included in the database for this reason.…”

Section: Tunnel Valleysmentioning

confidence: 99%

Map and GIS database of glacial landforms and features related to the last British Ice Sheet

Clark¹,

Evans²,

Khatwa³

et al. 2004

Boreas

199

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meltwater channels, tunnel valleys, trimlines, limit of key glacigenic deposits, glaciolacustrine deposits, ice-dammed lakes, erratic dispersal patterns, shelf-edge fans, and the Loch LomondReadvance limit of the main ice cap. The GIS contains over 20000 features split into thematic layers (as above). Individual features are attributed such that they can be traced back to their published sources. Given that the published sources of information that underpin this work were derived by a piecemeal effort over 150 years then our main caveat is of data consistency and reliability. It is hoped that this compilation will stimulate greater scrutiny of published data, assist in palaeo-glaciological reconstructions, and facilitate use of field-evidence in numerical ice sheet modelling. It may also help direct field workers in their future investigations.

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“…Modern subglacial drainage systems are largely inaccessible to all but indirect methods such as geophysical, geochemical and monitoring techniques (Hodgkins, 1997;Dowdeswell & Siegert, 2003;Rippin et al, 2003;Bingham et al, 2005;Smith et al, 2009). Studies centred upon the geological record or recently deglaciated areas have focussed primarily upon evidence derived from the landform record (Dahl, 1965;Röthlisberger, 1972;Nye, 1973;Walder, 1986Walder, , 2010Kamb et al, 1985;Fowler, 1987;Kamb, 1987;Wingfield, 1990;Brennand & Shaw, 1995;Ó Cofaigh, 1996;Piotrowski, 1997). Sedimentary evidence for subglacial drainage networks has proven more elusive.…”

Section: Introductionmentioning

confidence: 99%

Sedimentary and structural evolution of a relict subglacial to subaerial drainage system and its hydrogeological implications: an example from Anglesey, north Wales, UK

Lee

Wakefield

Phillips

et al. 2015

Quaternary Science Reviews

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Subglacial drainage systems exert a major control on basal-sliding rates and glacier dynamics. However, comparatively few studies have examined the sedimentary record of subglacial drainage. This is due to the paucity of modern analogues, the limited recognition and preservation of upper flow regime deposits within the geological record, and the difficulty of distinguishing subglacial meltwater deposits from other meltwater sediments (e.g. glacier outburst flood deposits). Within this study, the sedimentological and structural evolution of a subglacial to subaerial (ice-marginal / proglacial) drainage system is examined. Particular emphasis is placed upon the genetic development and preservation of upper flow regime bedforms and specifically recognising them within a subglacial meltwater context. Facies attributed to subglacial meltwater activity record sedimentation within a confined, but progressively enlargening, subglacial channel system produced under dune to upper flow regime conditions. Bedforms include rare large-scale sinusoidal bedding with syn-depositional deformation produced by current-induced traction and shearing within the channel margins. Subglacial sedimentation culminated with the abrupt change to a more ephemeral drainage regime indicating channel-abandonment or a seasonal drainage regime. Retreat of the ice margin, led to the establishment of subaerial drainage with phases of sheet-flow punctuated by channel incision and anastomosing channel development under diurnal, ablation-related, seasonal discharge. The presence of extensive hydrofracture networks demonstrate that proglacial groundwater-levels fluctuated markedly and this may have influenced later overriding of the site by an ice stream.

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The origin of major incisions within the Pleistocene deposits of the North Sea

Cited by 127 publications

References 31 publications

Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation

Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation

Map and GIS database of glacial landforms and features related to the last British Ice Sheet

Sedimentary and structural evolution of a relict subglacial to subaerial drainage system and its hydrogeological implications: an example from Anglesey, north Wales, UK

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