A map of large Canadian eskers from Landsat satellite imagery

Storrar, Robert D.; Stokes, Chris R.; Evans, David J. A.

doi:10.1080/17445647.2013.815591

Cited by 43 publications

(64 citation statements)

References 62 publications

(95 reference statements)

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“…This is achieved using a GIS dataset of eskers mapped from Landsat 7 ETMþ imagery of the whole of Canada, and covering almost 10,000,000 km 2 formerly occupied by the Laurentide Ice Sheet (LIS). These data are available as a map (Storrar et al, 2013), and were recently used to identify changes in esker density which may be associated with climatic changes (Storrar et al, 2014). Here, we build on this work and analyse esker patterns, distribution, length, fragmentation, sinuosity, spacing, tributaries, 'stream' ordering and slope, thereby providing an important dataset for testing both conceptual and numerical models of esker formation and providing new insights into channelised meltwater drainage at the ice sheet scale.…”

Section: Introductionmentioning

confidence: 98%

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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

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108

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: Introductionmentioning

confidence: 98%

“…They are common in formerly warm-based glaciated terrains (e.g. Prest et al, 1968;Clark et al, 2004;Aylsworth et al, 2012;Storrar et al, 2013), making them a useful indicator of subglacial meltwater drainage pathways. Meltwater drainage beneath ice sheets is of fundamental importance to our understanding of ice dynamics.…”

Section: Introductionmentioning

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

Self Cite

108

120

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“…River mouths formerly near (or under) thick ice have more variable sealevel histories, illustrating the divergent GIA histories result from different ice-sheet and solid-Earth models. and the mapped Canadian eskers from Storrar et al (2013). As there are few chronological controls on when these ice streams were active, ice divides are simply drawn between diverging ice streams.…”

Section: Methods: Data-driven Drainage Reconstructionmentioning

confidence: 99%

Reconstruction of North American drainage basins and river discharge since the Last Glacial Maximum

Wickert

2016

Earth Surf. Dynam.

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Abstract. Over the last glacial cycle, ice sheets and the resultant glacial isostatic adjustment (GIA) rearranged river systems. As these riverine threads that tied the ice sheets to the sea were stretched, severed, and restructured, they also shrank and swelled with the pulse of meltwater inputs and time-varying drainage basin areas, and sometimes delivered enough meltwater to the oceans in the right places to influence global climate. Here I present a general method to compute past river flow paths, drainage basin geometries, and river discharges, by combining models of past ice sheets, glacial isostatic adjustment, and climate. The result is a time series of synthetic paleohydrographs and drainage basin maps from the Last Glacial Maximum to present for nine major drainage basins -the Mississippi, Rio Grande, Colorado, Columbia, Mackenzie, Hudson Bay, Saint Lawrence, Hudson, and Susquehanna/Chesapeake Bay. These are based on five published reconstructions of the North American ice sheets. I compare these maps with drainage reconstructions and discharge histories based on a review of observational evidence, including river deposits and terraces, isotopic records, mineral provenance markers, glacial moraine histories, and evidence of ice stream and tunnel valley flow directions. The sharp boundaries of the reconstructed past drainage basins complement the flexurally smoothed GIA signal that is more often used to validate ice-sheet reconstructions, and provide a complementary framework to reduce nonuniqueness in model reconstructions of the North American ice-sheet complex.

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“…Carlson et al, 2009;Storrar, Stokes, & Evans, 2014a) and produced a large geomorphological imprint (e.g. Brennand, 2000;Brennand & Shaw, 1994;Mullins & Hinchey, 1989;Prest, Grant, & Rampton, 1968;Storrar, Stokes, & Evans, 2013), the geomorphological record of meltwater has to date played only a relatively minor role in ice sheet reconstructions. This is typically limited to providing supplementary information about ice geometries and flow direction (Kleman & Borgström, 1996), rather than to reconstruct basal and hydrological processes in space and time (see review by Greenwood, Clason, Helanow, & Margold, 2016).…”

Section: Introductionmentioning

confidence: 99%

Glacial geomorphology of the northern Kivalliq region, Nunavut, Canada, with an emphasis on meltwater drainage systems

Storrar

Livingstone

2017

Journal of Maps

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This paper presents a glacial geomorphological map of glacial lineations, ribbed terrain, moraines, meltwater channels (subglacial and ice-marginal/proglacial), eskers, glaciofluvial deposits, ice-contact outwash fans and deltas and abandoned shorelines on the bed of the former Laurentide Ice Sheet in northern Canada. Mapping was compiled from satellite imagery and digital elevation data and landforms were digitised directly into a Geographical Information System. The map reveals a complex glacial history characterised by multiple iceflow events, including fast-flowing ice streams. Moraines record a series of pauses or readvances during overall SE retreat towards the Keewatin Ice Divide. The distribution of subglacial meltwater landforms indicates that several distinctive scales and modes of drainage system operated beneath the retreating ice sheet. This includes a large (>100 km) integrated network of meltwater channels, eskers, ice-contact outwash fans and deltas and glaciofluvial deposits that originates at the northern edge of Aberdeen Lake. The map comprises zone 66 of the Canadian National Topographic System, which encompasses an area of 160,000 km 2 . It is presented at a scale of 1:500,000 and is designed to be printed at A0 size. ARTICLE HISTORY

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A map of large Canadian eskers from Landsat satellite imagery

Cited by 43 publications

References 62 publications

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

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

Reconstruction of North American drainage basins and river discharge since the Last Glacial Maximum

Glacial geomorphology of the northern Kivalliq region, Nunavut, Canada, with an emphasis on meltwater drainage systems

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