Transient subglacial hydrology of a thin ice sheet: insights from the Chasm esker, British Columbia, Canada

Burke, Matthew J.; Brennand, Tracy A.; Perkins, Andrew J.

doi:10.1016/j.quascirev.2012.09.004

Cited by 41 publications

(70 citation statements)

References 65 publications

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“…Mean sinuosity is in accordance with data from other areas (e.g. Clark et al, 2004;H€ attestrand and Clark, 2006;Burke et al, 2012), but maximum sinuosity is higher, likely due to the large sample size (Table 3). Sinuosity is significant because it is an important parameter for dye-tracing experiments and numerical models of subglacial channels.…”

Section: Esker Sinuositysupporting

confidence: 86%

“…Bolduc (1992) measured the sinuosity of esker ridges in Labrador and found that sinuosity varied between 1.00 and 1.32. A recent study of the Chasm esker, British Columbia, Canada (Burke et al, 2012) noted a sinuosity value of 1.07. Our extraction of sinuosity values for the esker ridges mapped in the UK and Kola Peninsula by Clark et al (2004) and H€ attestrand and indicate a mean esker ridge sinuosity of 1.03 and 1.06, respectively (Fig.…”

Section: Sinuositymentioning

confidence: 99%

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Morphometry and pattern of a large sample (>20,000) of Canadian eskers and implications for subglacial drainage beneath ice sheets

Storrar¹,

Stokes²,

Evans³

2014

Quaternary Science Reviews

107

120

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a b s t r a c tIce sheet flow is strongly influenced by the nature and quantity of meltwater entering the subglacial system. Accessing and monitoring contemporary drainage systems beneath ice sheets is notoriously difficult, but it is possible to utilise the exposed beds of palaeo-ice sheets. In particular, eskers record deposition in glacial drainage channels and are widespread on the exposed beds of former ice sheets. However, unlike some other common glacial landforms (e.g. drumlins) there have been relatively few attempts to investigate and quantify their characteristics at the ice sheet scale. This paper presents data on the distribution, pattern, and morphometry of a large (>20,000) sample of eskers in Canada, formed under the Laurentide Ice Sheet, including quantification of their length, fragmentation, sinuosity, lateral spacing, number of tributaries, and downstream elevation changes. Results indicate that eskers are typically very long (hundreds of km) and often very straight (mean sinuosity approximates 1). We interpret these long esker systems to reflect time-transgressive formation in long, stable conduits under hydrostatic pressure. The longest eskers (in the Keewatin sector) are also the least fragmented, which we interpret to reflect formation at an ice margin experiencing stable and gradual retreat. In many locations, the lateral distance between neighbouring eskers is remarkably consistent and results indicate a preferred spacing of around 12 km, consistent with numerical models which predict esker spacing of 8e25 km. In other locations, typically over soft sediments, eskers are rarer and their patterns are more chaotic, reflecting fewer large R-channels and rapidly changing ice sheet dynamics. Comparison of esker patterns with an existing ice margin chronology reveals that the meltwater drainage system evolved during deglaciation: eskers became more closely spaced with fewer tributaries as deglaciation progressed, which has been interpreted to reflect increased meltwater supply from surface melt. Eskers show no preference to trend up or down slopes, indicating that ice surface was an important control on their location and that the conduits were, in places, close to ice overburden pressure.

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Section: Esker Sinuositysupporting

confidence: 86%

Section: Sinuositymentioning

confidence: 99%

Morphometry and pattern of a large sample (>20,000) of Canadian eskers and implications for subglacial drainage beneath ice sheets

Storrar¹,

Stokes²,

Evans³

2014

Quaternary Science Reviews

107

120

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“…Channelized subglacial flow discharged toward ice margins and into rapidly evolving ice-marginal and proglacial lakes. Other evidence for this subglacial hydrologic system includes single and anabranching eskers, and channels carved into bedrock on the Interior Plateau (Burke et al, 2012b).…”

Section: Pattern Of Deglaciationmentioning

confidence: 95%

Deglaciation of the Cordillera of Western Canada at the end of the Pleistocene

Clague

2017

CIG

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“…Consequently, eskers have been used to infer former ice sheet dynamics (e.g., Shilts, 1984;Aylsworth and Shilts, 1989;Clark and Walder, 1994;Brennand, 2000;Storrar et al, 2014) and to test numerical models (e.g., Boulton et al, 2009). However, much debate remains as to the processes responsible for esker formation (Cummings et al, 2011) and, although recent work has shown that the glacial hydrologic system is never in steady state (e.g., Gray, 2005;Wingham et al, 2006;Fricker et al, 2007;Bell, 2008;Stearns et al, 2008;Bartholomaus et al, 2011), and that eskers may actually record relatively short lived and dynamic events (e.g., Brennand, 1994;Burke et al, 2008Burke et al, , 2010Burke et al, , 2012aCummings et al, 2011), numerical models have typically assumed steady state esker formation (e.g., Hooke and Fastook, 2007;Boulton et al, 2009). Detailed work on glacial lake outburst flood (GLOF) eskers at contemporary glaciers has demonstrated that the balance between water supply and sediment supply drive esker formation (Burke et al, , 2010.…”

Section: Background and Rationalementioning

confidence: 99%