On the formation of the tunnel valleys of the southern Laurentide ice sheet

Hooke, Roger LeB.; Jennings, Carrie E.

doi:10.1016/j.quascirev.2006.01.018

Cited by 104 publications

(81 citation statements)

References 40 publications

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“…Boulton and Hindmarsh, 1987;Boulton et al, 2007aBoulton et al, , b, 2009). Hooke and Jennings (2006) adapted this hypothesis, suggesting that initial headward erosion by piping was followed by more rapid enlargement when the conduit tapped into a subglacial lake, thereby combining both scenarios in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the impoundment of meltwater behind an ice margin frozen to its bed has been linked to tunnel valley formation, for example, along the southern terrestrial margins of the former Laurentide and European ice sheets where permafrost was prevalent (e.g. Piotrowski, 1994;Cutler et al, 2002;Hooke and Jennings, 2006). Genesis is typically thought to occur via repeated low to moderate magnitude floods that may be at or below bankfull flow (e.g.…”

Section: Introductionmentioning

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%

“…1b) typically invokes erosion of soft-sediment beds in low-pressure subglacial channels (Boulton and Hindmarsh, 1987;Mooers, 1989;Praeg, 2003;Boulton et al, 2009). In this model, high water pressures transmitted through the substrate to the ice-sheet terminus initiates failure and headward erosion of a conduit (by piping) (Shoemaker, 1986;Boulton and Hindmarsh, 1987;Hooke and Jennings, 2006;Boulton et al, 2009). As the fluid pressure of the conduit is lower than the surrounding substrate, meltwater flows towards the conduit, the walls are enlarged by sapping (i.e.…”

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: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

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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“…It is suggested that a subglacial drainage system was created in the late phase of ice advance , and contributed to stabilisation of the ice sheet by evacuating large volumes of water from the ice/ bed interface (Piotrowski, 1994;Jennings, 2006;Hermanowski & Piotrowski, 2007). Even though some subglacial water may have accumulated in pore space in dilated till (Hooke & Jennings, 2006) its volume probably would not be sufficient enough to erode substantial tunnel valleys commonly found in the study area. Considering these conditions that occurred in the lobe area raise the question of location of subglacial water storage.…”

Section: Discussionmentioning

confidence: 96%

Substratum morphology and significance during the Weichselian Odra ice lobe advance in northeast Germany and northwest Poland

Hermanowski

2015

Geologos

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In the Polish Lowlands, three main ice lobes, referred to as Odra, Vistula and Mazury, formed during the Last Scandinavian Glaciation. These lobes protruded at least several kilometres beyond the main ice margin and it is believed that they represent terminal parts of the ice streams. Applied geostatistical analysis based on numerous geological data has allowed an approximate reconstruction of the Odra ice lobe substratum in the area of northwest Poland and northeast Germany. A spatial representation of the Odra lobe substratum clearly illustrates the adverse slope of the glacier bed, but also indicates areas morphologically prone to ice streaming. It is suggested that the ice took advantage of local topography that enabled advance out of the Baltic basin; consequently, the ice followed a topographic low which, in combination with favourable hydraulic conditions of its substratum, likely initiated ice streaming.

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Experimental modeling of pressurized subglacial water flow: Implications for tunnel valley formation

et al. 2016

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Tunnel valleys are elongated hollows commonly found in formerly glaciated areas and interpreted as resulting from subglacial meltwater erosion beneath ice sheets. Over the past two decades, the number of studies of terrestrial tunnel valleys has continuously increased, and their existence has been hypothesized also on Mars, but their formation mechanisms remain poorly understood. We introduce here an innovative experimental approach to examine erosion by circulation of pressurized meltwater within the substratum and at the ice/substratum interface. We used a permeable substratum (sand) partially covered by a viscous, impermeable, and transparent cap (silicon putty), below which we applied a central injection of pure water. Low water pressures led to groundwater circulation in the substratum only, while water pressures exceeding a threshold that is larger than the sum of the glaciostatic and lithostatic pressures led to additional water circulation and formation of drainage landforms at the cap/substratum interface. The formation of these drainage landforms was monitored through time, and their shapes were analyzed from digital elevation models obtained by stereo-photogrammetry. The experimental landforms include valleys that are similar to natural tunnel valleys in their spatial organization and in a number of diagnostic morphological criteria, such as undulating longitudinal profiles and "tunnel" shapes. These results are consistent with the hypothesis that overpressurized subglacial water circulation controls the formation of tunnel valleys.Tunnel valleys are elongated and overdeepened hollows, up to hundreds of kilometers long, several kilometers wide and hundreds of meters deep, and their formation is generally attributed to subglacial meltwater erosion [Ó Cofaigh, 1996;Huuse and Lykke-Andersen, 2000]. They are generally exposed at the emplacement of former ice sheet margins

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On the formation of the tunnel valleys of the southern Laurentide ice sheet

Cited by 104 publications

References 40 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

Substratum morphology and significance during the Weichselian Odra ice lobe advance in northeast Germany and northwest Poland

Experimental modeling of pressurized subglacial water flow: Implications for tunnel valley formation

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