Spooner Hills, northwest Wisconsin: High-relief hills carved by subglacial meltwater of the Superior Lobe

Johnson, Mark D.

doi:10.1130/0-8137-2337-x.83

Cited by 12 publications

(7 citation statements)

References 7 publications

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“…4, 11; and see also Attig et al, 1989;Mooers, 1989;Patterson, 1997;Smed, 1988;Johnson, 1999;Cutler et al, 2002;Jørgensen and Sandersen, 2006) suggests formation and growth is intimately associated with pauses or slow-downs in ice margin fluctuations and that meltwater drained to the ice margin. The implication is that tunnel valley formation requires a relatively stable ice-sheet configuration to allow headward growth or recharge of source storage areas.…”

Section: Morainesmentioning

confidence: 99%

“…There is a rich history of work on tunnel valleys beneath the southern margin of the former Laurentide Ice Sheet (Wright, 1973;Attig et al, 1989;Mooers, 1989;Patterson, 1994Patterson, , 1997Clayton et al, 1999;Johnson, 1999;Kehew et al, 1999Kehew et al, , 2013Cutler et al, 2002;Sjogren et al, 2002;Fisher et al, 2005;Kozlowski et al, 2005;Jennings, 2006;Hooke and Jennings, 2006;Kehew and Kozlowski, 2007). In this section we briefly summarise key observations arising from this work, which need to be incorporated into any model of tunnel valley formation.…”

Section: Previous Work and Observations In Study Areamentioning

confidence: 99%

“…In Wisconsin, Michigan and Minnesota, bands of hills are observed to occur upstream of tunnel valleys (Johnson, 1999). These are interpreted as erosional remnants of an anastomosing subglacial meltwater system that drained through the inter-hill depressions.…”

Section: Previous Work and Observations In Study Areamentioning

confidence: 99%

“…At their downstream end, tunnel valleys often terminate at outwash fans some of which contain coarse boulder-gravel material (e.g. Attig et al, 1989;Mooers, 1989;Patterson, 1994;Clayton et al, 1999;Johnson, 1999;Kehew et al, 1999;Cutler et al, 2002;Derouin, 2008). Palaeo-discharge estimates from the boulder deposits imply large discharges, and this has been used as evidence for outburst flood events (Cutler et al, 2002).…”

Section: Previous Work and Observations In Study Areamentioning

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: Morainesmentioning

confidence: 99%

Section: Previous Work and Observations In Study Areamentioning

confidence: 99%

Section: Previous Work and Observations In Study Areamentioning

confidence: 99%

Section: Previous Work and Observations In Study Areamentioning

confidence: 99%

See 2 more Smart Citations

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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“…bSpooner Hills,Q observed to have formed up-ice of tunnel valleys in the Superior lobe in Wisconsin (Johnson, 1999), are an up-glacier component of the subglacial meltwater landsystem and should be included in any model of the ice-lobe drainage system but they are so large that they sometimes go unrecognized. They are hills comprised of older glacial sediment and represent erosional remnants formed by a more anastomosing subglacial drainage system.…”

Section: Subglacial Drainagementioning

confidence: 99%

Terrestrial ice streams—a view from the lobe

Jennings

2006

Geomorphology

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The formation and evolution of an isolated submarine valley in the North Channel, Irish Sea: an investigation of Beaufort's Dyke

Callaway

Quinn²,

Brown

et al. 2011

J Quaternary Science

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Beaufort's Dyke is a submarine depression located in the North Channel of the Irish Sea. With a maximum depth of 312 m, the dyke is one of the deepest areas within the European continental shelf. Integration and interpretation of 450 km of sparker seismic data and full-coverage bathymetric data derived from multi-beam echo sounder surveys allow for the investigation of the formation processes of Beaufort's Dyke and the evolution of geomorphological features within it. The dyke, formed by composite subglacial processes dominated by subglacial meltwater discharge, is interpreted as a tunnel valley. The regional isolation of Beaufort's Dyke may be explained by the bounding of the North Channel by the bedrock masses of Ireland and Scotland, coupled with the exploitation of structural weakness along a fault plane and presence of halite in the eroded substrate enhancing the erosive potential of the overlying glacier. Beaufort's Dyke has probably been maintained as an open feature by strong rectilinear tidal currents. The morphology of lunate sediment waves and a large parabolic bedform towards the south of the dyke contradict the observed dominant S-N mean hydrodynamic flow recorded within the North Channel, suggesting an alternative hydrodynamic regime either within the dyke or during bedform creation

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Spooner Hills, northwest Wisconsin: High-relief hills carved by subglacial meltwater of the Superior Lobe

Cited by 12 publications

References 7 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

Terrestrial ice streams—a view from the lobe

The formation and evolution of an isolated submarine valley in the North Channel, Irish Sea: an investigation of Beaufort's Dyke

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