Late Wisconsin landform distribution and glacier-bed conditions in Wisconsin

Attig, John W.; Mickelson, David M.; Clayton, Lee

doi:10.1016/0037-0738(89)90128-0

Cited by 120 publications

(85 citation statements)

References 7 publications

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“…We estimate that ∼ 80 % of these tunnel valleys have been previously identified and mapped during more localised investigations (e.g. Wright, 1973;Attig et al, 1989;Patterson, 1997;Fisher et al, 2005). The map reveals a tendency for tunnel valleys to cluster together with large intervening areas where no or very few valleys occur.…”

Section: Is There a Characteristic Spatial Distribution And Arrangement?mentioning

confidence: 81%

“…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%

“…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%

“…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%

“…11b). Outwash fans are particularly common in the Chippewa, Wisconsin, Langlade, Green Bay, Superior and Wadena lobes (see also Attig et al, 1989;Clayton et al, 1999;Cutler et al, 2002;Fisher and Taylor, 2002), and at the downstream end of the large bedrock tunnel valleys in Lake Superior (Regis …”

Section: Outwash Fansmentioning

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: Is There a Characteristic Spatial Distribution And Arrangement?mentioning

confidence: 81%