Are long subglacial bedforms indicative of fast ice flow?

Stokes, Chris R.; Clark, Chris D.

doi:10.1080/030094802760260355

Cited by 188 publications

(111 citation statements)

References 49 publications

(41 reference statements)

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“…Based on appearance and dimensions, the grooves and ridges are similar to (mega-scale) glacial lineations (MSGLs; e.g. [1,3,12,29,63,64,76]), which are closely associated with fast ice-flow [47]. Even though lineations in Kongsfjorden are much shorter (max.…”

Section: Streamlined Bedforms: Glacial Lineationsmentioning

confidence: 99%

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Submarine landform assemblages and sedimentary processes related to glacier surging in Kongsfjorden, Svalbard

Streuff

Forwick

Szczuciński

et al. 2015

Arktos

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Section: Streamlined Bedforms: Glacial Lineationsmentioning

confidence: 99%

“…fast ice-flow (e.g. [76]), when processes of erosion and re-deposition deform soft subglacial sediments into sets of grooves and ridges (cf. e.g.…”

Section: Streamlined Bedforms: Glacial Lineationsmentioning

confidence: 99%

Submarine landform assemblages and sedimentary processes related to glacier surging in Kongsfjorden, Svalbard

Streuff

Forwick

Szczuciński

et al. 2015

Arktos

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“…Their high elongation indicates formation beneath fastflowing ice, because more than 85% of them have elongations ratios greater than 10:1 (Fig. 10C) (Stokes and Clark, 2002). The bedforms include whalebacks, which are often associated with periods of former fast-flow (Jansson et al, 2003).…”

Section: Bedform Progression and Elongationmentioning

confidence: 99%

“…The downstream change in elongation ratio of subglacial bedforms at the substrate boundary results from a change in basal conditions, from motion over bedrock surfaces, to motion upon a less resistant sedimentary bed. Unlike landsystem 2, mean elongation in landsystem 3 is likely to be a more reliable proxy for palaeo-ice velocity (Stokes and Clark, 2002), and thus, the MSGLs record rapid flow similar to that of modern ice streams (Bamber et al, 2000;King et al, 2009).…”

Section: Landsystem 3 -Sub-ice Stream Footprintmentioning

confidence: 99%

Bedform signature of a West Antarctic palaeo-ice stream reveals a multi-temporal record of flow and substrate control

Graham

Larter

Gohl

et al. 2009

Quaternary Science Reviews

175

173

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a b s t r a c tThe presence of a complex bedform arrangement on the sea floor of the continental shelf in the western Amundsen Sea Embayment, West Antarctica, indicates a multi-temporal record of flow related to the activity of one or more ice streams in the past. Mapping and division of the bedforms into distinct landform assemblages reveals their time-transgressive history, which implies that bedforms can neither be considered part of a single downflow continuum nor a direct proxy for palaeo-ice velocity, as suggested previously. A main control on the bedform imprint is the geology of the shelf, which is divided broadly between rough bedrock on the inner shelf, and smooth, dipping sedimentary strata on the middle to outer shelf. Inner shelf bedform variability is well preserved, revealing information about local, complex basal ice conditions, meltwater flow, and ice dynamics over time. These details, which are not apparent at the scale of regional morphological studies, indicate that past ice streams flowed across the entire shelf at times, and often had onset zones that lay within the interior of the Antarctic Ice Sheet today. In contrast, highly elongated subglacial bedforms on sedimentary strata of the middle to outer shelf represent a timeslice snapshot of the last activity of ice stream flow, and may be a truer representation of fast palaeo-ice flow in these locations. A revised model for ice streams on the shelf captures complicated multi-temporal bedform patterns associated with an Antarctic palaeo-ice stream for the first time, and confirms a strong substrate control on a major ice stream system that drained the West Antarctic Ice Sheet during the Late Quaternary.

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“…Boulton and Clark, 1990;Clark, 1994;Stokes and Clark, 2002). Collectively, these highly elongate ice-directional landforms are known as 'mega-scale glacial lineations' (Clark, 1993).…”

Section: Previous Work Using Large-scale Bedrock Forms To Infer Palamentioning

confidence: 99%

Megagrooves and streamlined bedrock in NW Scotland: The role of ice streams in landscape evolution

2008

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New multibeam bathymetry data, onshore high-resolution elevation data (NEXTMap) and fieldwork in the Ullapool area of NW Scotland reveal large-scale megagrooves and streamlined bedrock forms in a well-defined ~20-km wide zone. The landsystem is typical of a coherent flow corridor within a grounded ice sheet on bedrockdominated terrain. We describe the morphology of the large-scale features, discuss their likely formation, and consider the wider implications for ice-sheet dynamics. Based on the strongly convergent bedform distribution, the presence of megagrooves and highly elongate bedrock forms, we interpret the erosional landscape to be the signature of a fast-flowing tributary that once fed the The Minch palaeo-ice stream -a major artery of the last British-Irish ice sheet. The exact genesis of bedrock megagrooves remains uncertain, although focused subglacial abrasion is likely to have carved most of the shallow, strongly parallel, features; whilst glacial meltwater may have carved or modified others. Bedform morphometry is used to discriminate zones reflecting the degree of glacial streamlining (elongation ratios <5:1 or >5:1). We interpret these zones to represent the transition from potentially cold-based slow ice-sheet flow to warm-based fast flow. Based on these results, and the presence of ribbed moraines, we suggest a bedform continuum model for onset zones of palaeoice streams on rigid beds. Rapid spatial bedform evolution is suggested to reflect an increase in subglacial erosive power that may be diagnostic of palaeo-ice-sheet thermal boundaries (i.e. from cold-to warm-based), and is also consistent with the expected downstream increase in ice velocity within an ice-stream onset zone. Finally, this study speculates on the role played by basal meltwater in ice-stream initiation and the role of ice streams and their tributaries in landscape evolution.

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Are long subglacial bedforms indicative of fast ice flow?

Cited by 188 publications

References 49 publications

Submarine landform assemblages and sedimentary processes related to glacier surging in Kongsfjorden, Svalbard

Submarine landform assemblages and sedimentary processes related to glacier surging in Kongsfjorden, Svalbard

Bedform signature of a West Antarctic palaeo-ice stream reveals a multi-temporal record of flow and substrate control

Megagrooves and streamlined bedrock in NW Scotland: The role of ice streams in landscape evolution

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