Size and shape characteristics of drumlins, derived from a large sample, and associated scaling laws

Clark, Chris D.; Hughes, Anna L.C.; Greenwood, Sarah L.; Spagnolo, Matteo; Ng, Felix

doi:10.1016/j.quascirev.2008.08.035

Cited by 203 publications

(256 citation statements)

References 63 publications

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“…Our aim is to provide a foundation for future work on the morphometry and spatial characteristics of eskers (similar to drumlins: see e.g. Clark, Hughes, Greenwood, Spagnolo, & Ng, 2009), as well as the factors controlling how and where they form in relation to ice margin retreat, with a view to ultimately providing a more robust model of how subglacial meltwater drainage systems operate on a large scale.…”

Section: Introductionmentioning

confidence: 99%

A map of large Canadian eskers from Landsat satellite imagery

2013

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Meltwater drainage systems beneath ice sheets are a poorly understood, yet fundamentally important environment for understanding glacier dynamics, which are strongly influenced by the nature and quantity of meltwater entering the subglacial system. Contemporary sub-ice sheet meltwater drainage systems are notoriously difficult to study, but we can utilise exposed beds of palaeo-ice sheets to further our understanding of subglacial drainage. In particular, eskers record deposition in glacial drainage channels and are widespread on the exposed beds of former ice sheets. This paper presents a 1:5,000,000 scale map of .20,000 large eskers (typically . 2 km long) deposited by the Laurentide Ice Sheet (LIS), mapped from Landsat imagery of Canada, in order to establish a dataset suitable for analysis of esker morphometry and drainage patterns at the ice sheet scale. Comparisons between eskers mapped from Landsat imagery and aerial photographs indicate that, in most areas, approximately 75% of eskers are detected using Landsat. The data presented in this map build on and extend previous work in providing a consistent map of an unprecedented sample of eskers for quantitative analysis. It offers an alternative perspective on the problems surrounding ice-sheet meltwater drainage and can be used for: (i) detailed investigations of esker morphometry and distribution from a large sample size; (ii), testing of numerical models of meltwater drainage routing that predict esker characteristics (e.g. channel spacing, sinuosity), (iii) assessment of the factors that control esker location and formation; and (iv), a refined understanding of ice margin configurations during retreat of the LIS.

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Section: Introductionmentioning

confidence: 99%

A map of large Canadian eskers from Landsat satellite imagery

2013

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“…Clark and Meehan 2001;Hughes et al, 2007;Clark et al, 2009). Following the methodology of Clark et al, (2009), three relief-shaded (hillshade) models were produced.…”

Section: Digital Geomorphological Mappingmentioning

confidence: 99%

“…Clark and Meehan 2001;Hughes et al, 2007;Clark et al, 2009). Following the methodology of Clark et al, (2009), three relief-shaded (hillshade) models were produced. Two models were artificially illuminated from the northwest (315°; figure 2) and the northeast (045°) at an inclination of 45° to highlight landforms orientated orthogonal to the illumination direction.…”

Section: Digital Geomorphological Mappingmentioning

confidence: 99%

“…The elongation ratio (Clark et al, 2009) and amplitude of the hummocks were used to discriminate three landform-assemblages (LA1, LA2 and LA3). LA1 was further subdivided in to 3 zones (LA1.1, 1.2 and 1.3; figure 3).…”

Section: Digital Geomorphological Mappingmentioning

confidence: 99%

“…In particular, the availability of enhanced resolution data sets (e.g. NextMAP™) has led to the increasing use of DEMs for the mapping of glacial landforms Clark et al, 2009) as they represent a direct quantification of landform morphology (Clark and Meehan, 2001). The integration, manipulation and analysis of DEM data has also been enabled by the development of Geographical Information Systems (GIS) (Napieralski et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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A morphological, sedimentological and geophysical investigation of the Woore Moraine, Shropshire, England

Parkes¹,

Waller²,

Knight³

et al. 2009

Proceedings of the Geologists' Association

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Subglacial bed form morphology controlled by ice speed and sediment thickness

Barchyn

Dowling

Stokes

et al. 2016

Geophysical Research Letters

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Subglacial bed forms (drumlins, ribbed moraines, and megascale glacial lineations) are enigmatic repetitive flow‐parallel and flow‐transverse landforms common in glaciated landscapes. Their evolution and morphology are a potentially powerful constraint for ice sheet modeling, but there is little consensus on bed form dynamics or formative mechanisms. Here we explore shallow sediment bed form dynamics via a simple model that iterates (i) down‐flow till flux, (ii) pressure gradient‐driven till flux, and (iii) entrainment and deposition of sediment. Under various boundary conditions, replicas of subglacial bed forms readily emerge. Bed form dynamics mirror those in subaqueous and aeolian domains. Transitions between ribbed moraines and elongate flow‐parallel bed forms are associated with increasing ice speeds and declining sediment thickness. These simulations provide quantitative flux estimates and suggest that widely observed transitions in shallow sediment subglacial bed forms (e.g., ribbed moraines to drumlinoids to megascale glacial lineations) are manifestations of subtle variations in ice velocity and sediment thickness.

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Size and shape characteristics of drumlins, derived from a large sample, and associated scaling laws

Cited by 203 publications

References 63 publications

A map of large Canadian eskers from Landsat satellite imagery

A map of large Canadian eskers from Landsat satellite imagery

A morphological, sedimentological and geophysical investigation of the Woore Moraine, Shropshire, England

Subglacial bed form morphology controlled by ice speed and sediment thickness

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