Incipient tunnel channels

Sjogren, Darren; Fisher, Timothy G.; Taylor, Lawrence D.; Jol, Harry M.; Munro‐Stasiuk, Mandy J.

doi:10.1016/s1040-6182(01)00091-x

Cited by 61 publications

(54 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indistinct valleys may be due to partial burial during re-advance events or by melt out of debris rich ice obscuring them (Kehew et al, 1999). Sjogren et al (2002) also identified indistinct valleys in Michigan that are eroded into the hummocky terrain.…”

Section: Previous Work and Observations In Study Areamentioning

confidence: 91%

“…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%

“…Mooers, 1989), to indistinct valleys often associated with hummocky terrain and characterised by beaded or crenulated planforms, or as a series of aligned depressions (e.g. Kehew et al, 1999;Sjogren et al, 2002). Indistinct valleys may be due to partial burial during re-advance events or by melt out of debris rich ice obscuring them (Kehew et al, 1999).…”

Section: Previous Work and Observations In Study Areamentioning

confidence: 99%

“…However, this fragmented appearance may also arise by differential erosion along the length of a drainage route (Fig. 8a, e, f; see also Sjogren et al, 2002) or due to water cutting up into the ice as well as down into the sediment (e.g. Fowler, 2011;Livingstone et al, 2016).…”

Section: Morphology Of Tunnel Valleysmentioning

confidence: 99%

See 3 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.

View full text Add to dashboard Cite

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.

show abstract

Section: Previous Work and Observations In Study Areamentioning

confidence: 91%

Section: Previous Work and Observations In Study Areamentioning

confidence: 99%

Section: Previous Work and Observations In Study Areamentioning

confidence: 99%

Section: Morphology Of Tunnel Valleysmentioning

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.

View full text Add to dashboard Cite

show abstract

“…Clark and Walder (1994) showed that eskers from the LIS were concentrated over the impermeable crystalline bedrock of the Canadian Shield, where subglacial meltwater was more likely to carve R-channels into the base of the ice. In contrast, over softer permeable 15 sediments, meltwater was more likely to drain into and across the till, carving much shallower channels or 'canals' in a more distributed system (Sjogren et al, 2002). This broad pattern is also seen in the FIS (Boulton et al, 2009) and, while eskers can clearly form over softer sedimentary beds, they are typically less common and depict a more chaotic and fragmentary pattern (Shilts et al, 1987;Storrar et al, 2014a).…”

Section: Subglacial Hydrology Of Ice Sheets and Subglacial Lakesmentioning

confidence: 99%