An assessment of fluting and “till esker” formation on the foreland of Sandfellsjökull, Iceland

Evans, David J. A.; Nelson, Chris D.; Webb, Caroline

doi:10.1016/j.geomorph.2009.08.016

Cited by 28 publications

(25 citation statements)

References 53 publications

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“…On the foreland, the short distance over which warm-based conditions prevailed was suffi cient for ice to construct fl utings but not to affect signifi cant changes in clast form before debris was raised into englacial positions at the snout. Evans et al (2010) have demonstrated that short distance transport of freshly plucked bedrock can result in fl utings that contain clasts which are striated and blocky (low C 40 ) but display low roundness. Calculations of the distance required to change volcanic clasts from angular to subrounded indicate that at least several hundred metres of transport in the subglacial traction zone are necessary (Humlum, 1985;Kjaer, 1999).…”

Section: Discussionmentioning

confidence: 99%

Controlled moraine development and debris transport pathways in polythermal plateau icefields: examples from Tungnafellsjökull, Iceland

Evans

2010

Earth Surf Processes Landf

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A modern landsystems analogue for plateau icefi eld glaciation is presented, based upon Tungnafellsjökull in the arid, cold interior of Iceland. Landform mapping and intensive clast form analysis on three separate forelands occupied during the Little Ice Age reveal variability in the morphology of moraines and the degree of clast modifi cation, which is interpreted as a function of the complex interplay between: (a) the effi cacy of glacial erosion; (b) passive versus active debris transfer mechanisms; and (c) the volume of debris provision for ice-marginal freeze-on mechanisms. A steep outlet bounded by rockwalls produced a landform assemblage and debris transport signature typical of valley glaciers, whereas two unconfi ned outlets produced a landform-sediment imprint typical of polythermal conditions. This comprises subglacial bedforms, relating to the initiation of warm-based ice by strain heating below icefalls at the plateau edge, terminating at arcs of ice-cored (controlled) moraine representative of frozen snout conditions. Patterns in clast form data on the unrestricted forelands refl ect the characteristics of glacier dynamics and thermal regimes at the margin of a plateau icefi eld, where bedrock steps of suffi cient size to initiate strain heating and bedrock abrasion and plucking are located only a short distance from the marginal freeze-on conditions of a snout creating debris-rich folia and controlled moraine. Additional englacial debris may well have been carried to the glacier margin through the development of ogives and englacial thrusting at the base of the icefall, thereby explaining the occurrence of striae on clasts that have otherwise been little modifi ed by glacial abrasion.

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Section: Discussionmentioning

confidence: 99%

Controlled moraine development and debris transport pathways in polythermal plateau icefields: examples from Tungnafellsjökull, Iceland

Evans

2010

Earth Surf Processes Landf

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“…Christoffersen et al, 2005;Evans et al, 2010;Larsen et al, 2006). Their origin in Icelandic settings is hypothesized to relate to the squeezing of dilatant till into an elongated cavity or R-channel immediately after meltwater evacuation, during a short period when the pressure gradient between the cavity and the till bed was steep and hence saturated till was subject to localized creep towards the elongate low pressure zone .…”

Section: Till and Morainementioning

confidence: 99%

“…However, the density of overridden moraines and widespread occurrence of sawtooth moraines (cf. Burki, Larsen, Fredin, & Margreth, 2009;Fredin & Burki, 2008;Matthews, Cornish, & Shakesby, 1979;Price, 1970) with unusually long limbs, geometrical ridges (crevasse infills) and numerous till eskers (sensu Christoffersen, Piotrowski, & Larsen, 2005;Evans, Nelson, & Webb, 2010;Larsen, Piotrowski, Christoffersen, & Menzies, 2006) are embellishments specific to this landsystem that reflect the intensive development of longitudinal crevassing in lobate snouts terminating at marginal-thickening till wedges (cf. Evans & Hiemstra, 2005) rather than outwash heads, as exemplified at Heinabergsjökull.…”

Section: Introductionmentioning

confidence: 99%

Fláajökull (north lobe), Iceland: active temperate piedmont lobe glacial landsystem

2015

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A 1:6250 map of the foreland of Fláajökull's north lobe as it appeared in 1989, together with a 1:350 scale map of a sample area of recently exposed glacial landforms from 2014, enables an assessment of the spatial and temporal evolution of glacial landform assemblages at the margin of an active temperate piedmont lobe terminating at ice-marginal thickening till wedges. The pattern of landform development captured in these maps indicates that the glacier margin developed strong longitudinal crevassing and well-developed ice-marginal pecten (threedimensional crenulations) during its historical recession. This is recorded by early recessional phase linear push moraines on well-drained distal slopes of the foreland and the later development of interrelated sawtooth moraines, crevasse squeeze ridges and till eskers, indicative of extending ice flow and poorly drained submarginal conditions. This landform record is a palaeoglaciological signature of a changing process-form regime inherent within the active temperate piedmont lobe landsystem model.

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“…Chandler, Evans, & Roberts, 2016;Chandler, Evans, Roberts, Ewertowski, & Clayton, 2015;Evans & Orton, 2014;Evans, Ewertowski, & Orton, 2015;Jóns-son et al, 2016). More specifically, the occurrence on these glacier forelands of widespread sawtooth moraines with unusually long limbs/crevasse infills ( Figure 1; Evans et al, 2015;Evans, Nelson, & Webb, 2010;Price, 1970) has been linked to the intensive development of longitudinal crevassing in lobate snouts, operating only over the most recent decades of ice recession and hence apparently linked to extending ice flow and poorly drained sub-marginal conditions. Such conditions appear to have prevailed since recession into prominent overdeepenings (Cook & Swift, 2012) located behind overridden moraine arcs and are therefore likely to dominate for several decades into the future if ice recession continues at its present rate (cf.…”

Section: Introductionmentioning

confidence: 99%

Skaftafellsjökull, Iceland: glacial geomorphology recording glacier recession since the Little Ice Age

2017

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Citation for published item:ivnsD hvid tF eF nd iwertowskiD wrek nd yrtonD ghris @PHIUA 9kftfellsj¤ okullD selnd X glil geomorphology reording glier reession sine the vittle se egeF9D tournl of mpsFD IQ @PAF ppF QSVEQTVF Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. A 1:5700 scale map of the recently deglaciated foreland of Skaftafellsjökull, Iceland as it appeared in 2007, depicts a typical active temperate glacial landsystem with a clear pattern of sequentially changing push moraine morphologies, including remarkable hairpin-shaped moraines, indicative of spatial and temporal variability in process-form regimes in glacier sub-marginal settings. Similar to other Icelandic glacier forelands, this demonstrates that the piedmont glacier lobes of the region have developed strong longitudinal crevassing and well-developed ice-marginal pecten during their historical recession from the Little Ice Age maximum moraines, likely driven by extending ice flow and poorly drained sub-marginal conditions typical of the uncovering of overdeepenings. Additionally, the localized development of a linear tract of kame and kettle topography is interpreted as the geomorphic and sedimentary signature of thrust stacked and gradually melting debris-rich glacier ice, a feature hitherto unrecognized in the Icelandic active temperate lobe landsystem signature. ARTICLE HISTORY

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An assessment of fluting and “till esker” formation on the foreland of Sandfellsjökull, Iceland

Cited by 28 publications

References 53 publications

Controlled moraine development and debris transport pathways in polythermal plateau icefields: examples from Tungnafellsjökull, Iceland

Controlled moraine development and debris transport pathways in polythermal plateau icefields: examples from Tungnafellsjökull, Iceland

Fláajökull (north lobe), Iceland: active temperate piedmont lobe glacial landsystem

Skaftafellsjökull, Iceland: glacial geomorphology recording glacier recession since the Little Ice Age

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